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Dissertations / Theses on the topic 'HDPE'
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Al-Ati, Tareq. "Oxygen permeation of virgin HDPE films versus recycled HDPE films /." Online version of thesis, 1994. http://hdl.handle.net/1850/11875.
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Sejas, Orellana Alain Osvaldo. "Internacionalización de productos de HDPE." Tesis, Universidad de Chile, 2011. http://www.repositorio.uchile.cl/handle/2250/111452.
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Magíster en Gestión para la GlobalizaciónComo líder en la producción de tuberías plásticas en Chile, Vinilit S.A. desea evaluar una posible expansión de su línea de productos de tuberías de HDPE para la minería. En particular, la línea de productos para la minería, comprende tuberías de polietileno de alta densidad o HDPE, con diámetros que van desde 20 a 1200 mm de diámetro. El objetivo principal de esta Tesis, es determinar el mercado más apropiado para dicha expansión dentro de Sudamérica, junto con la mejor estrategia de entrada al mercado seleccionado. Para esto, se consideraron tanto los factores internos de la industria, como aquellos de nivel nacional y regional que puedan afectar el resultado de la iniciativa. Con este fin, lo primero fue seleccionar el país objetivo, evaluando variables macroeconómicas y características individuales de países de la región. Se concluye que Perú es la mejor alternativa por su menor inestabilidad, mayor tamaño de industria minera y no presencia de empresas pertenecientes al mismo consorcio de Vinilit comercializando estos productos. Luego, dada la naturaleza internacional del negocio, se realizó un análisis de los escenarios político, económico y social del país seleccionado, para determinar los efectos de estos en la inversión. En este sentido, la inestabilidad y baja transparencia del país, hacen necesario contar con apoyo de una empresa local. Tras la evaluación financiera del proyecto, se pudo apreciar que el costo de producción es el factor más crítico para la iniciativa, ya que esto, junto con la alta agresividad de la industria, hacen presente el riesgo de episodios de guerra de precios. Entonces, se hace muy importante diferenciar horizontalmente el producto dentro de sus competidores como un producto de alta calidad. Por otra parte, debido a la alta inversión requerida para el proyecto, se recomienda realizarla en dos etapas. Vale destacar, que la primera puede continuar sin necesidad de implementar la segunda, aunque con menores retornos esperados. Lo anterior, reduce el riesgo del proyecto, ya que se puede decidir si invertir en la segunda etapa a la vista de los resultados de la primera. Finalmente, en vista de los antecedentes estudiados, se puede concluir que el mercado se encuentra en expansión y que la inestabilidad de Perú es tal, que puede ser manejada por un socio local. Considerando además, flujos positivos y un plan de inversión divisible en dos etapas independientes, se recomienda proceder con la iniciativa.
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Ashraf, Ghulam S. K. "Valorisation of chemically contaminated HDPE." Thesis, Brunel University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367858.
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Mohammed, Tan I. "Properties of silane-crosslinked HDPE." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234047.
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Sejas, Orellana Alain Osvaldo. "Internacionalización de Productos de HDPE." Tesis, Universidad de Chile, 2012. http://www.repositorio.uchile.cl/handle/2250/102772.
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Soto, Juan José, and Danilo Sacandi. "Producción de geomembranas de HDPE." Bachelor's thesis, Universidad Nacional de Cuyo. Facultad de Ciencias Aplicadas a la Industria, 2017. http://bdigital.uncu.edu.ar/9328.
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El trabajo contiene el análisis y la evaluación técnico económica de la fabricación de geomembranas de polietileno de alta densidad a nivel industrial. El estudio realizado alcanza el nivel de prefactibilidad.
El producto es un bien de consumo intermedio, utilizándoselo en un importante número de
aplicaciones en obras de impermeabilización. El consumo nacional se encuentra cubierto en su mayor porcentaje por productos importados de países sudamericanos, siendo Chile, Colombia y Brasil los más representativos, mientras que en el ámbito local son pocas las empresas que desarrollan este tipo de producto, lideradas por IPESA S.A y Coverfilm S.A. La calidad del producto estará garantizada al trabajar bajo estándares establecidos en las normas GM 13, IRAM 78032 e IRAM 78028, siendo estos aspectos fundamentales para competir lealmente en el mercado y lograr la aceptación de los clientes.
Los objetivos de este estudio son: realizar un estudio de pre-factibilidad técnica y económica de la
instalación y puesta en marcha de una fábrica de producción de geomembranas de HDPE mediante la técnica de extrusión y conformado por burbuja; identificar y justificar la necesidad del uso de las geomembranas de HDPE en función de la variedad de aplicaciones que poseen; determinar la probable demanda futura de las geomembranas de HDPE en Argentina; analizar la oferta de las materias primas en el país y en el exterior, de manera de determinar la viabilidad de obtenerlas en el mercado interno o acudir a su importación; analizar y precisar la localización más conveniente para la instalación de la planta de producción; seleccionar la tecnología más conveniente en función de la capacidad de producción, costos de adquisición y características del producto a obtener; analizar costos de inversión, operación y fabricación de Geomembranas
de HDPE; determinar competitividad en el mercado interno con el fin de sustituir importaciones; determinar un marco legal que permita tener un respaldo para la aplicación del proyecto; contribuir a la concientización en la preservación del medio ambiente y mejora en el manejo de los recursos naturales.Fil: Soto, Juan José. Universidad Nacional de Cuyo. Facultad de Ciencias Aplicadas a la Industria.
Fil: Sacandi, Danilo. Universidad Nacional de Cuyo. Facultad de Ciencias Aplicadas a la Industria.
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Patzelt, Petr. "Creepová životnost vysokomolekulárního polyethylenu (HDPE)." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401905.
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The theoretical part of the thesis deals with the summary of material properties and testing parameters that influence SCG process. The experimental part is aimed on the comparison of different condition effects on the process of FNCT and PENT. Chosen temperatures for PENT were 70; 80 and 90 °C and the applied nominal stress 2,0; 2,4 and 2,8 MPa. In the case of FNCT the chosen temperatures were the same and the ligamental stress was 4 MPa for all used environments which were: water, Arkopal N110 solution and Dehyton PL solution. In addition, several experiments were measuered under applied nominal stresses 3; 4; 5; 6; 8 a 10 MPa and at 80 °C in Arkopal N110 solution. The morphology of crack surfaces was studied afterwards. The obtained data were used for evaluaion by a five parameter equation.
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Shelley, R. M. "Development of HDPE fuel tanks." Thesis, Loughborough University, 1987. https://dspace.lboro.ac.uk/2134/11033.
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Plastics fuel tanks have been used successfully abroad ; metal counterparts are still predominant in this country plastics tanks have to satisfy stringent performance regulations : low temperature impact tests ; permeability ; and fire resistance. Blow moulded high density polyethylene (HDPE) fuel tanks have superior strength to mass ratio compared with metal equivalents (the density of steel is about 8000 kg/m3 compared with HDPE, which has a density of under 1000 kg/m3 ). HDPE will tend to drip in a fire situation, thus reducing explosion risk. HDPE is the chosen material because it possesses inherent properties suitable for the blow moulding process : it has a high viscosity at low stresses ; and is highly inert. Rotational moulded HDPE fuel tanks can also be considered. However, these are shown to have inferior properties when compared with blow moulded tanks ; attraction of rotational moulding is the cheapness of equipment. Petrol immersion was found to enhance impact properties of HDPE, although yield stresses were lowered slightly. The thickness distributions of blow moulded fuel tanks were found to vary ; this is because of the present difficulty of predicting parison behaviour with respect to time. Thickness is important because of impact strength and permeation considerations. Impact properties of fuel tanks were assessed ; peak force of impact was found to be heavily dependent on thickness (raised to the power 1.1) and temperature of mould in the blow moulding process (a low mould temperature led to inferior properties). Pinch-offs were found to be particularly detrimental to impact properties. Cooling behaviour was investigated. With the aid of a cooling model for blow mouldings, it was found that a warm mould (40·C) could be used with internal air circulation to obtain a cooling time the same as that with a cold mould and no air circulation. Thus optimising mechanical strength and maintaining economic viability. Welding of injection moulded fittings to the main blow moulded body of the fuel tank was found to be faulty, in all of the tanks examined ; many weld failures have been reported in use. This work determines optimum welding conditions for HDPE grades, these are Rigidex H060-45P and Lupolen 426l-A.
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Hegni, Tonje. "Validering av materialmodell for polypropylen (HDPE)." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18801.
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Denne rapporten tar for seg validering av en hyperelastisk – viscoplastisk material modell som tidligere har blitt implementert i elementmetode koden LS – Dyna. Materialet som er evaluert er polyetylen (HDPE) som er levert av det tyske firmaet SIMONA. Material parameterne som er satt inn i den konstitutive material modellen er funnet fra eksperimentell testing og kalibrering.Modellen er validert ved å sammenligne resultater av to veldefinerte eksperimentelle tester ved numeriske forutsigelser. Det har blitt utført tester på plate med hull. Platene har en mer kompleks geometri grunnet hullet i platen, og vil derfor gi mer komplekse spenning og tøynings tilstander. I tillegg har platene veldefinerte randbetingelser. Disse har en mer komplisert sammensetning av trykk og strekk og vil derfor være mer realistiske, da en virkelig komponent brukt i industrien vil bli utsatt for både trykk og strekk samt påført last av ulike hastigheter. De eksperimentelle og simulerte testene er sammenlignet og evaluert i valideringskapittelet. Modellen fanger opp de viktigste egenskapene observert i testene.
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Soliman, Ahmed M. "Re-rounding of Deflected HDPE Pipes." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1555005546013105.
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Hampapa, Břetislav. "Reakce HDPE v tavenině iniciované peroxidy." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-216682.
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The thesis deals with HDPE modification by crosslinking. In the theoretical part, data available in the literature were reviewed. Modifications of the selected HDPE copolymer grade were carried out in a kneading device Brabender using 25 ml chamber size. After having optimized process conditions, there were performed a series of experiments in dependence on concentration of the initiator. Reological properties of polymer samples were investigated by melt flow indexes measured under different conditions. Changes in crystallinity and melting temperatures were evaluated from DSC heat flow measurements. The samples meeting characteristics supposed were selected for measuring complex viscosity on the Rheometer AR-G2 TA and for testing some mechanical properties on the device Zwick.
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SILVA, GEOVANE DE ALMEIDA SANTOS DA. "DEVELOPMENT AND CHARACTERIZATION OF HDPE/PA12 BLENDS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=35984@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTITUIÇÕES COMUNITÁRIAS DE ENSINO PARTICULARES
Blenda polimérica é a mistura física de dois ou mais polímeros, sem reação química intencional entre os componentes. O objetivo básico é combinar as melhores propriedades de cada componente da blenda que, consequentemente, terá propriedades intermediárias àquelas dos polímeros misturados. As maiores vantagens das blendas são a grande variedade e a versatilidade de suas aplicações, que, somadas à facilidade de processamento, possibilitam a produção dos mais diversos produtos, tornando-as competitivas em relação a outros materiais. Outra finalidade das blendas é otimizar a relação custo/benefício e melhorar a processabilidade de polímeros de alta temperatura. Os materiais utilizados neste trabalho foram o PEAD e a PA12, ambos os polímeros sendo de grande importância industrial. O objetivo do trabalho é produzir blendas poliméricas de PEAD/PA12, avaliar a sua miscibilidade e realizar ensaios para extrair suas propriedades. As blendas foram feitas em três composições: 75/25, 50/50 e 25/75 e foi feita a caracterização mecânica com ensaios de tração e fluência, química com análise FTIR e DRX, reológica e análise por MEV e os resultados foram usados para avaliar a combinação das propriedades dos polímeros puros nestas blendas.
Polymer blend is the physical mixture of two or more polymers without any intentional chemical reaction between the components. The basic goal is to combine the best properties of each blend component that, consequently, will have intermediary properties to those of the polymers used. The biggest advantages of the blends are the great variety and the versatility on their applications that added to the good processability, make possible the production of many products making them competitive in relation to other materials. Another objective of the blends is to optimize the cost/benefit relation and improve the processability of high temperature polymers. The materials used on this work were the HDPE and the PA12, both polymers being of great industrial importance. The interest of this work is to produce HDPE/PA12 blends and evaluate their miscibility and make tests to know their properties. The blends were made in three compositions: 75/25, 50/50 and 25/75 and it was done the mechanical characterization with uniaxial tension and creep behavior, chemical characterization with FTIR analysis and x-ray diffraction, rheology and SEM analysis and the results were used to evaluate the combination of the properties of the neat polymers used in these blends.
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Akchurin, Aydar. "Lubrication and Wear at Metal/HDPE Contacts." Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26503.
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In the thesis lubrication and wear at metal/HDPE contacts was addressed. In particular this type of contact occurs in artificial joint replacements. Wear of HDPE was recognized as a major factor limiting device performance.
In the thesis, fully implicit fully coupled numerical approach was developed to simulate lubrication and wear. Approach allows solving stationary and transient problems for rough surfaces in a wide range of parameters. Wear coefficients were estimated from experimental data.
Wear particles formed in wear process were investigated. Particles were found to be approximately 100 nm in diameter and spherical in shape. Considering theoretical solutions, it was concluded that debris may play a role of third-body abrasive wear particles.
In the summary section, some discussion was provided on the topic of theoretical modeling of friction and wear and recommendations for future research were formulated.
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Han, Xiao. "Critical Vertical Deflection of Buried HDPE Pipes." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1490790838331014.
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Laidlaw, Trudy Carol. "Influence of local support on corrugated HDPE pipe." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ39844.pdf.
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Sangam, Henri Pilakani. "Performance of HDPE geomembrane liners in landfill applications." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58232.pdf.
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Siskind, Esther. "Market development for recycled high density polyethylene (HDPE)." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/70176.
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Colom, Fajula Xavier. "Caracterització microestructural i mecànica de compòsits hdpe/fibres lignocel.lulòsiques." Doctoral thesis, Universitat Politècnica de Catalunya, 1999. http://hdl.handle.net/10803/6060.
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A partir de polietilè d'alta densitat i de fibres lignocel·lulòsiques provinents del trèmol (Populus tremula) s'han obtingut uns materials amb propietats úniques denominats compòsits. Aquests compòsits, amb un màxim de 40% de fibres lignocel·lulòsiques han estat tractats i modificats amb diferents agents (silà A-174 i epolè C-18) per millorar la compatibilitat entre la matriu de polietilè i el reforç fibrós. En una primera etapa les fibres lignocel·lulòsiques han estat pretractades amb cada un dels diferents tipus d'agents d'adhesió utilitzats i comentats prèviament, per seguidament barrejar aquestes fibres (en proporcions del 10, 20, 30 i 40%) amb la matriu d'HDPE.
Una vegada els dos components s'han homogeneïtzat, es sotmeten a un procés de mòlta per aconseguir, mitjançant compressió, les provetes corresponents. Finalment, el conjunt de provetes ha estat exposat a condicions climàtiques dràstiques (baixa temperatura i fatiga tèrmica, dues característiques significatives de l'hivern canadenc) durant períodes variables de temps (0, 15, 30, 60 i 90 dies).
Per tal d'avaluar tots i cada un dels paràmetres més significatius d'aquests compòsits, s'ha fet una caracterització orientada en dues vessants: estudi de la compatibilitat entre components del compòsit i estudi dels canvis estructurals que pateixen els compòsits degut a fenòmens d'envelliment provocats per exposició a les condicions climàtiques prèviament comentades.
L'estudi de compatibilitat es fonamenta en les possibles interaccions que s'originen entre els dos components en funció del tipus de tractament al que ha estat sotmès el compòsit (silà i epolè). Per valorar aquestes interaccions, s'han estudiat diferents propietats mecàniques, com ara la resistència a la tracció, el mòdul d'elasticitat, la deformació a trencament, la resiliència i la tenacitat, mitjançant una màquina universal d'assaigs. Tanmateix també s'ha fet una caracterització espectrefotomètrica FT-ir per comprovar els diferents mecanismes d'adhesió que actuen en la interfase fibra- matriu en funció del tipus de tractament i una caracterització morfològica, utilitzant la tècnica de microscòpia electrònica de rastreig (SEM). Amb els resultats obtinguts de la caracterització espectrefotomètrica, també s'ha realitzat un seguiment de la influència que cada component fa en la modificació del grau de cristal·linitat de l'altre.
L'estudi dels canvis estructurals que pateixen els compòsits degut a fenòmens d'envelliment s'ha fet partint de l'evolució de les propietats mecàniques bàsiques en funció dels diferents períodes d'exposició, on s'han caracteritzat els mateixos paràmetres definits anteriorment. Mitjançant valoració espectrefotomètrica s'han mesurat els canvis microestructurals (principalment de configuració), així com les modificacions en el grau de cristal·linitat que han tingut lloc sobre cada un dels diferents components del compòsit.
Cal afegir que les possibilitats que ofereix la tècnica espectrefotomètrica FT-ir ha permès dur a terme la realització d'aquesta tesi. L'estudi dels canvis en la microestructura dels compòsits esdevinguts a partir dels fenòmens prèviament esmentats no hauria pogut fer-se sense la possibilitat d'un processament adequat dels espectres, així com d'una subtracció espectral que permet la detecció de moltes bandes complexes i difícils de detectar mitjançant altres tècniques d'anàlisi.
Los materiales compuestos se han obtenido a partir de polietileno de alta densidad y fibras lignocelulósicas que provienen del alamo temblón. Estos materiales con un máximo del 40% de refuerzo lignocelulósico han sido tratadas y modificadas con distintos tipos de agentes de acoplamiento (Silano A-174 y epoleno C-18) para mejorar la compatibilidad entre la matriz y el refuerzo.
Las fibras tratadas previamente con cada uno de los distintos tipos de agentes de adhesión utilizados, se mezclan en distintas proporciones de las mismas (10,20,30 y 40%) con la matriz de HDPE.
Una vez ambos componentes se han homogenizado se someten a un proceso de molturación para obtener probetas tipo halterio mediante compresión. Estas probetas se han sometido durante distintos períodos de tiempo (hasta 90 días) a condiciones de exposición drásticas (baja temperatura y fatiga térmica, características significativas del invierno canadiense).
Para evaluar los parámetros más significativos de estos materiales compuestos se ha caracterizado la compatibilidad entre la matriz y el refuerzo, asimismo también se han estudiado los cambios estructurales que sufren estos materiales debido a fenómenos de envejecimiento provocados por la exposición de los mismos a las condiciones climáticas previamente comentadas.
Els estudio de compatibilidad se centra en las posibles interacciones que se originen entre ambos componentes en función del tipo de tratamiento al que se ha sometido dicho material compuesto (silano y epoleno). Para valorar las interacciones que se generen entre ambos componentes, se ha ensayado distintas propiedades mecánicas (resistencia a tracción, módulo de elasticidad, deformación a rotura, resilencia y tenaciadad, utilizando la máquina universal de ensayos. Asimismo, también se ha caracterizado mediante espectroscopia de infrarrojo (FTIR) los posibles mecanismos de adhesión que tienen lugar entre la matriz y el refuerzo en función del tipo de tratamiento, asi como la caracterización morfológica utilizando la técnica de microscopía electrónica de barrido (SEM). A partir de los resultados obtenidos se ha podido seguir la influencia que tiene cada componente en la modificación de los respectivos grados de cristalinidad.
El estudio de los cambios estructurales a los que se han visto sometido los distintos materiales compuestos, debido a fenómenos de envejecimiento, se ha realizado mediante el seguimiento de la evolución de las propiedades mecánicas en función de los distintos períodos de exposición. Mediante valoración espectofotométrica se han medido los cambios micorestrucutrales (cambios de configuración), así como las modificaciones en el grado de cristalinidad sobre cada uno de los componentes de material compuesto.
Composite materials have been obtained from high density polyethylene (HDPE) and lignocellulosic fibers from aspen wood. These materials with a maximum of 40% of lignocellulosic reinforcement have been treated and modified with different types of coupling agents (Silane A-174 and epolene C-18) to improve the compatibility between the matrix and the reinforcement.
Four contents (10.20.30 and 40%) of fibers treated previously with each one of the different types of adhesion or coupling agents, are mixed with HDPE matrix.
The above mixture was compression-molded into dog-bone shaped tensile test specimens. The molding temperature was slowly raised to 150ºC and samples were held at this temperature for 20 min. Then the samples were slowly cooled to room temperature keeping constant pressure during cooling. These test specimens have been submitted during different periods of time (up to 90 days) to drastic conditions of exposition (low temperature and thermal stress, main characteristics of the Canadian winter).
In order to evaluate the most significant parameters of these composite materials, we have studied two ways: the compatibility between both components: matrix and reinforcement and the structural changes to composites due to phenomena of aging caused by the exposition of these materials to the drastic climatic conditions previously commented.
The study of compatibility has been centered in the possible interactions that are originated between both components as a function of lignocellulosic fiber pretreatment. In order to evaluate the interactions that are generated between both components, different mechanical test has been tested (tensile strength, elasticity modulus, deformation at break, resilence and toughness) by mean an Instron Testing Machine. Moreover, the possible mechanisms of adhesion that take place between the matrix and the reinforcement as a function of different pretreatments has been characterized by means infrared spectroscopy (FTIR), and by the morphologic characterization using the scanning electronic microscopy (SEM). From the obtained results it has been possible to follow the influence that has each component in the modification of the respective degrees of crystallinity.
The study of the structural changes of different composite materials, due to aging phenomena, has been analized by means of the pursuit of the evolution of the mechanical properties based on the different periods of exposure time. Furthermore the microstructural changes (basically configurational and crystallinity) has been evaluated by means of spectroscopy technique.
The obtained results indicate that the macroscopic properties of the composite materials must depend on the lignocellulosic fiber content and whether or not a coupling agent is used. SEM micrographs of fracture surfaces show that the addition of coupling agents enhances their dispersion in the continuous HDPE phase. They also show that the silane coupling agent facilitates the direct contact between the lignocellulosic fibers and HDPE matrix more than untreated and epolene treated composites do. The tensile strength depends on both the lignocellulosic fiber content and the type of coupling agent used. The other mechanical properties (elasticity modulus, elongation at break and toughness) mainly depend on the lignocellulosic fiber content and, to a lesser extent, on the presence of a coupling agent. Silane-treated composites show the best mechanical performance as a consequence of significant interactions at the interface between the HDPE matrix and the lignocellulosic fibers.
The differences observed between the various composites studied are explained by means of different adhesion mechanisms. Interdiffusion takes place in untreated composites; multiple mechanism of adsorption-wettability, interdiffusion and, to a lesser extent, chemical bonds take place in epolene treated composites, and finally, the adhesion in composites modified with silane is mainly a chemical mechanism of covalent bonds.
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Chehab, Abdul Ghafar. "Time dependent response of pulled-in-place HDPE pipes." Thesis, Kingston, Ont. : [s.n.], 2008. http://hdl.handle.net/1974/1239.
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Russell, Alan Donald. "Microwave-assisted pyrolysis of HDPE using an activated carbon bed." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/244641.
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Plastics play an enormous role in modern manufacturing, but the extraction and refining of raw materials, followed by the synthesis of plastics themselves, represents an enormous energy investment into a product that is all too often simply “thrown away” into a landfill after a single use. Microwave-assisted pyrolysis is a recycling technique that allows the recovery of chemical value from plastic waste by breaking down polymers into useful smaller hydrocarbons using microwave heat in the absence of oxygen. This dissertation examines the use of a catalytic activated carbon bed in this procedure, using high density polyethylene (HDPE) as a model plastic. Initial tests with the batch input of HDPE produced a condensed pyrolysis oil comprising 35.5–45.3% aromatics, with the remainder primarily short-chain aliphatics. This oil was approximately three times lighter than that produced in the absence of catalyst, with a narrower range of molecular masses that matched those of the liquid transport fuels petrol and diesel (C5–C21). The non-condensable gases that resulted were short-chain aliphatics that could be used as feedstock for the creation of new chemicals (such as virgin HDPE), or fuels such as natural gas and LPG. The development of apparatus capable of adding sample in a continuous fashion enabled the processing of larger quantities of HDPE, and resulted in condensed products with a significantly higher aromatic content (>80% at 450°C), and which encompassed a somewhat narrower range of molecular masses compared with those produced in the batch mode; this was due to differences in kinetics and residence time that resulted from the different modes of sample introduction. As a result of processing larger quantities of HDPE it became apparent that the activated carbon deactivated over time, with a bed able to process around 3.5 times its mass in HDPE at 450°C before any significant changes in output products occurred. The decomposition of HDPE proceeds via thermal scission and radical-mediated mechanisms; high energy surface active sites facilitate the transfer of hydrogen and radicals, and this enhances overall cracking and lowers the activation energy for the formation of aromatics. Analysis of material deposited on the surface of the activated carbon confirmed that deactivation occurred through coking, with both cracking and deactivation thought to be enhanced by the formation of microwave-induced microplasmas. Overall, the microwave-assisted pyrolysis of HDPE using activated carbon produces a much narrower range of more valuable products compared with non-catalytic processing. While the process is not likely to be economic in its current form owing to the relatively rapid deactivation of the activated carbon, future configurations incorporating online reactivation may be able to economically provide a second use cycle for these materials, avoiding expending energy to extract and process increasingly scarce new raw material from the surface of the earth.
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Imamoglu, Baris. "Case history strain and force distribution in HDPE reinforced wall /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 149 p, 2009. http://proquest.umi.com/pqdweb?did=1889078531&sid=8&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Thesis (M.C.E.)--University of Delaware, 2009.Principal faculty advisors: Dov Leshchinsky and Christopher L. Meehan, Dept. of Civil & Environmental Engineering. Includes bibliographical references.
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Chastagner, Matthew Wayne. "Slit die rheology of HDPE and ABS based wood plastic composites." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Summer2005/m%5Fchastagner%5F072705.pdf.
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Pillo, Antonio. "Closed loop control of recycled HDPE crosslinking using an inline rheometer." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69771.
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This study involves the use of an inline rheometer (ILR) for process control. The ILR is a melt viscosity sensor that is mounted directly in the main process stream. This type of installation minimizes the measurement delay time, which is important for sensors used in process control applications.The ILR was used for the closed loop control of product viscosity of post-consumer recycled high density polyethylene crosslinking in a twin screw extruder. The manipulated variable is the feed rate of crosslinking agent. Internal model control, Dahlin control, and minimum variance control algorithms were successfully implemented.
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BECERRA, ANDRES FELIPE CRUZ. "HDPE CHARACTERIZATION BEFORE AND AFTER AGING IN DIFFERENT CONDITIONS AND MEDIUM." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=26152@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
O interesse deste trabalho está baseado no estudo da influência das diferentes condições e meios de envelhecimento nas propriedades mecânicas, térmicas, estruturais e químicas do polietileno de alta densidade (PEAD) utilizado para a fabricação das tubulações para o transporte de óleo e gás. Foram fabricados corpos de prova com o formato para o teste de tração tipo V segundo a norma ASTM D638. Para o desenvolvimento deste trabalho os corpos de prova foram submetidos a diferentes tipos de envelhecimento em diferentes meios, a saber: i) radiação UV com uma energia radiante de comprimento de onda de 365 nm e tempos de exposição de 8, 12 e 18 semanas; ii) envelhecimento sob temperatura, os corpos de prova foram imersos em três diferentes tipos de óleo lubrificantes, a 50, 70 e 90 graus celsius em tempos de 2, 3, 4 e 6 meses; iii) envelhecimento sob pressão, onde os corpos de prova foram submetidos a 7, 14 e 17 bar e imersos em água corrente a 50 graus celsius durante 1 e 2 semanas e no óleo padrão BASIC OB 440 a 70 graus celsius durante 1, 2 e 5 semanas. As amostras envelhecidas foram caracterizadas por difração de raios X, espectroscopia infravermelha, espectroscopia RAMAN, calorimetria diferencial de varredura, análise termogravimétrica, ensaio de tração, ensaios de fluência, índice de fluidez, microscopia eletrônica de varredura e microscopia óptica. Os resultados das caracterizações das amostras após envelhecimento foram comparados com os resultados obtidos do PEAD virgem, cujas propriedades foram obtidas usando os mesmos métodos de caracterização. Foi avaliado, ainda, o comportamento viscoelástico do PEAD, mediante a simulação matemática dos modelos viscoelásticos, partindo dos resultados experimentais dos testes de fluência antes e após de envelhecimento. Os resultados obtidos demostraram que comportamento mecânico do PEAD após ser envelhecido foi fortemente influenciado pelas diferentes variáveis, como temperatura, pressão, meio e tempo de exposição. Sendo que a soma de cada efeito gerado por cada parâmetro contribui para a variação do desempenho mecânico do polímero. Qualquer que seja a variável externa imposta ao PEAD, temperatura, tempo, pressão ou meio de exposição, sempre acarretam alterações nas propriedades mecânicas. Porém, dependendo de qual dos parâmetros mencionados anteriormente seja o predominante, o envelhecimento do PEAD será mais ou menos relevante. Da simulação do comportamento sob fluência, o modelo dos 4 parâmetros foi quem apresentou a melhor descrição gráfica e aproximação matemática do comportamento experimental.
The interest of this work was based on the study of the influence of different aging conditions and medium in mechanical, thermal, structural and chemical properties of high-density polyethylene (HDPE) used for the manufacture of line pipes for transporting oil and gas. Prototypes for type-V tensile testing according to ASTM D 638. For development this work, the samples were submitted to different types of aging in different medium, namely: i) UV irradiation with a radiant energy with 365 nm of wavelengths and exposure times of 8, 12 and 18 weeks; ii) For aging under temperature, the samples were immersed in three different types of lubricating oil, to 50, 70 and 90 celsius degree for periods of 2, 3, 4 and 6 months; iii) aging under pressure, where the samples were submitted to 7, 14 and 17 bar and immersed in ordinary water at 50 celsius degree for 1 and 2 weeks and pattern Oil BASIC B 440-70 celsius degree for 1, 2 and 5 weeks. The aged samples was characterized by X-ray diffraction, infrared spectroscopy, Raman spectroscopy, differential scanning calorimetric, thermal gravimetric analysis, tensile and creep tests, melt flow rate, scanning electron microscopy and optical microscopy. The results of the characterization of the samples after aging were compared with the results obtained from virgin HDPE, whose properties were obtained using the same characterization methods. Besides, was evaluated, the viscoelastic behavior of the HDPE, by mathematical simulation of viscoelastic models, based on experimental results of creep tests before and after aging. The results showed that mechanical behavior of HDPE after aging was strongly influenced by different variables, such as temperature, pressure, medium and exposure time. Since the sum of each effect generated by each parameter contributes to the variation of the mechanical performance of the polymer. Whichever the external variable imposed on HDPE - temperature, time, pressure, or exposure medium - always leads to changes in mechanical properties. However, depending on which of the parameters mentioned above is predominant, the aging HDPE will be more or less relevant. Simulating the creep behavior, the four parameters model was the one who presented the best graphic and mathematical description approximation of the experimental behavior.
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Scapini, Patrícia. "Morfologia e propriedades térmicas de compósitos de HDPE/EVA com POSS." reponame:Repositório Institucional da UCS, 2008. https://repositorio.ucs.br/handle/11338/370.
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Neste trabalho foram estudados compósitos que apresentam como matriz polimérica uma blenda composta por polietileno de alta densidade (HDPE) e copolímero etileno acetato de vinila (EVA) e como nanocarga, silsesquioxano poliédrico oligomérico (POSS). Os compósitos foram processados em câmara de mistura fechada e caracterizados quanto às propriedades térmicas e morfológicas. Para a preparação dos compósitos foram variadas as concentrações dos componentes da blenda (0, 25, 50, 75 e 100%) e da nanocarga (0, 0,5, 1, 1,5, 2, 5 e 10%). Os resultados de processamento mostraram que o aumento da concentração de POSS na matriz polimérica provocou a agregação do mesmo na matriz polimérica. As análises de calorimetria diferencial de varredura e termogravimetria indicaram que o POSS não afetou as temperaturas de fusão, cristalização e degradação da matriz polimérica. Os resultados de raios X indicaram que a presença do EVA no compósito promoveu o aparecimento de domínios cristalinos em concentrações menores de POSS. A microscopia eletrônica de varredura indicou que as amostras com 1% de POSS apresentam distribuição homogênea na matriz polimérica. Por outro lado, ocorreu a formação de agregados nas amostras com 5% de POSS. Os valores de Tg obtidos por análise térmica dinâmico-mecânica indicaram que o POSS causou um efeito plastificante na fase HDPE e uma redução da mobilidade na fase EVA. Ocorreu um aumento nos valores de módulo de armazenamento com a incorporação de POSS na matriz polimérica.Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-05-22T19:03:21Z No. of bitstreams: 1 Dissertacao Patricia Scapini.pdf: 2020883 bytes, checksum: 2c7249d3915135dd5f3cba151cf459db (MD5)
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In this study composites with a polymeric matrix comprising a blend of high density polyethylene (HDPE) and the copolymer ethylene vinyl acetate (EVA), and with polyhedral oligomeric silsesquioxane (POSS) as the nanoclay, were processed and characterized. The composites were processed in a closed mixing chamber and characterized in terms of their thermal and morphological properties. For the preparation of the composites the concentrations of the blend components (0, 25, 50, 75 and 100%) and of the nanoclay (0, 0.5, 1, 1.5, 2, 5 and 10%) were varied. The results of the processing showed that an increase in the POSS concentration in the polymeric matrix caused the aggregation of the system. The differential scanning calorimetry and thermogravimetry analyses indicated that the POSS did not affect the melt, crystallization and degradation temperatures of the polymeric matrix. The X-ray results indicated that the presence of EVA in the composite led to the appearance of crystalline domains at lower POSS concentrations. Scanning electron microscopy indicated that the samples with 1% of POSS have a homogeneous distribution in the polymeric matrix. However, the formation of aggregates occurred in samples with 5% of POSS. The Tg values obtained from the thermo dynamic mechanical analysis indicated that the POSS had a plasticizing effect on the HDPE phase and caused a reduction in the mobility of the EVA phase. There was an increase in the storage modulus values with the incorporation of POSS into the polymeric matrix.
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TORRES, AMELIA ANGELICA ULLOA. "PHYSICOCHEMICAL AGEING OF HDPE PIPES ASSIGNED TO THE TRANSPORTATION OF PETROLEUM DERIVATIVES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11035@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOAs tubulações de aço carbono são amplamente usadas em muitas redes de distribuição de transporte de derivados de petróleo. Estas apresentam dois inconvenientes (corrosão e perda da pressão devido à rugosidade interna elevada). Porem, diversas distribuidoras tentaram substituir as tubulações metálicas pelos tubos poliméricos. Entre o material não metálico, o polietileno de alta densidade (PEAD) parece ser uma alternativa mais viavél e econômico. Não obstante, sua aplicação industrial tem mostrado já alguns problemas, tais como inchamento e microfisuras, especialmente nas linhas de distribuição do álcool, óleo e combustível. Assim, nossa pesquisa foi dedicada ao estudo físico químico do envelhecimento do PEAD em contato com derivados do petróleo. Dois líquidos modelos (Diesel e Marcol) foram usados para analisar a influência da espécie aromática e parafínica no envelhecimento do polímero durante 150 dias a T=20°C e 50°C. Primeiramente, fizemos a caracterização do PEAD e dos líquidos modelos antes do envelhecimento, para entender as interações do polímero-líquido. No estudo de envelhecimento, as medidas gravimétricas com experiências TGA fazem possível avaliar a difusão do fluido dentro do PEAD. Os resultados mostraram que apesar da composição aromatica, o diesel, solubilizou as cadeias de baixo peso molecular do polímero. Foram realizados também testes de fluência para investigar os efeitos macroscópicos durante o envelhecimento do PEAD. Para períodos muito curtos de envelhecimento, a flexibilidade do PEAD foi devida à sorção do fluido, para tempos maiores de exposição no gasoil, a plastificação do PEAD é reduzida significativamente devido à extração de unidades poliméricas pequenas, mesmo na temperatura ambiente.
Carbon steel pipes are widely used for the transportation of petroleum derivates in many distribution networks. However, these pipes present two important drawbacks (corrosion, pressure loss due to high internal roughness...) For these reasons, several petroleum furnishers have examined the opportunity to substitute metallic pipes by polymeric tubes. Among the non-metallic material, high density polyethylene (HDPE) represent a good alternative from a technical and economic point of view. Nevertheless, its application at the industrial scale has already shown some problems such as sweeling and microcracks especially in lines assigned to the distribution of alcohol, oil and fuel. Our research work was devoted to the physicochemical study of the ageing of HDPE samples in contact with petroleum derivatives. Two model fluids (gasoil and Marcol) were used to analyse the influence of aromatic and paraffinic species on the polymer ageing during 150 days at different temperatures (T=20°C and 50° C). First, we made the characterization of the polymer and of the model fluids before ageing for understand the polymer-liquid interactions. In the ageing study, the gravimetric measurements with TGA experiments made it possible to evaluate the fluid diffusion inside the polymeric matrix. Important discrepancies were shown between gasoil and Marcol actions. In spite of its aromatic composition, the former was more powerful to solubilize low weight polymer chains. Creep tests were performed to investigate the macroscopic effects on the ageing on the HDPE. For very short periods of ageing time, the HDPE flexibilization was due to the fluid sorption. For higher exposure times in gasoil, the HDPE plasticization is significantly reduced because of the occurrence of the extraction of small polymeric units even at room temperature.
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INACIO, WILLIAM BUSCHLE ROMARIZ. "EFFECT OF REPROCESSING ON THE MECHANICAL PROPERTIES OF A HDPE/LDPE BLEND." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=34970@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROOs termoplásticos representam a grande maioria dos polímeros empregados hoje em dia e a grande vantagem de sua aplicação é que podem ser reaquecidos e moldados repetidamente. Com a crise do petróleo em 1973, os custos para transformar o petróleo em materiais plásticos se tornaram mais atrativos do que transformá-lo em materiais mais tradicionais. Com isso, os investimentos nas indústrias de transformação cresceram, ao mesmo tempo que a preocupação com o meio ambiente. Devido a facilidade de reprocessar esses materiais a temperaturas moderadas, muitas empresas passaram a reutilizar seus resíduos dentro de seus próprios processos. Neste escopo, esse trabalho tem como objetivo estudar o comportamento mecânico do polietileno de baixa densidade (PEBD) e de uma mistura física formada por polietileno de baixa densidade (PEAD) e polietileno de alta densidade, com uma proporção de 80/20, ao serem submetidos a diversos ciclos de processamento. Os materiais estudados foram preparados e doados pela Companhia de Canetas Compactor. Para este estudo, o material sofreu dez etapas de injeção/extrusão. A partir de ensaios de tração foram determinadas as tensões e cargas máximas suportadas, calculando-se em seguida o módulo de elasticidade, alongamento e tenacidade de cada material. A adição do PEAD é responsável por aumentar a resistência e a dureza do material. Do ponto de vista prático, o material reprocessado não apresentou mudanças significativas de performance. Análises por infravermelho mostraram que não há degradação por oxidação ao longo do processo de reciclagem.
Thermoplastics are the most used polymers nowadays on account of being easily reprocessable with high temperatures. During the oil crisis in 1973 the costs of transforming oil into plastic materials became more attractive than turning them into more traditional materials. Furthermore, the investments in transformation industries grew alongside the concern for the environment. Due to the ease of reprocessing these materials a lot of companies started recycling them within their process. In this context, the present study aims to analyze the mechanical behavior of a low density polyethylene (LDPE) and high density polyethylene (HDPE) blend and pure LDPE after 10 cycles of reprocessing. The polymers were donated by Companhia de Canetas Compactor. The materials suffered up to 10 cycles of injection moulding/extrusion. Tensile tests were made to determine the maximum yield stress and maximum load allowed. Afterwards, calculations were made to determine elongation, Young modulus and toughness. The HDPE addition was responsible to raise the materials yield stress and hardness. From a practical point of view the reprocessing didn t affect significantly the materials performance. FTIR analyses didn t detect oxidation through the process.
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Waldron, Calvin Michael. "Efficacy of Delmopinol in Preventing the Attachment of Campylobacter jejuni to Chicken, Stainless Steel and High-Density Polyethylene." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/50861.
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Campylobacter spp. are the second leading bacterial cause of food borne illness in the U.S. New antimicrobials that prevent bacterial attachment may be effective for reducing Campylobacter. Delmopinol hydrochloride (delmopinol) is a cationic surfactant that is effective for treating and preventing gingivitis and periodontitis. This study evaluated the effectiveness of delmopinol for reducing attachment of Campylobacter jejuni to chicken, stainless steel and high-density polyethylene.
Chicken pieces, steel and HDPE coupons were spot-inoculated with 0.1 mL of a Campylobacter jejuni culture. After 10 min, samples were sprayed with 0.5% or 1.0% delmopinol, 0.01% sodium hypochlorite, or distilled water. Contact times were 1, 10, or 20 min prior to rinsing with buffered peptone water. Rinses were serially diluted onto Campy Cefex Agar for enumeration. For additional samples, solutions were applied first, followed by inoculation with C. jejuni after 10 min. Cultures remained undisturbed for 1, 10, or 20 min. Then samples were rinsed and plated as above.
When C. jejuni was inoculated before treatments, 1% delmopinol application led to mean log reductions of 1.26, 3.70, and 3.72 log CFU/mL, greater than distilled water, for chicken, steel and HDPE respectively. When C. jejuni was inoculated after spray treatments, 1% delmopinol reduced C. jejuni by 2.72, 3.20, and 3.99 mean log CFU/mL more than distilled water for chicken, steel and HDPE respectively. Application of 1% delmopinol, either before or after bacteria inoculation, resulted in a significantly (p<0.05) greater log reduction than 0.01% sodium hypochlorite or distilled water. Delmopinol may be a promising antimicrobial treatment.Master of Science in Life Sciences
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Chladil, Martin. "Studium vztahu mezi vnitřní strukturou HDPE a odolností vůči rychlosti šíření trhliny SCG (Slow Crack Growth)." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2015. http://www.nusl.cz/ntk/nusl-217108.
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This thesis deals with the relation between structure and resistance to failure by the mechanism of slow crack growth (SCG) in HDPE. In the theoretical part there are summarized previously acquired knowledge about the production of PE and about the relation between structure and resistance to failure by the SCG mechanism. In the experimental part, three samples of HDPE with the same melt index MI and the same content of copolymer 1- hexene were synthesized by using three chromium catalysts commonly used for polymerization in industry. There samples were analyzed by GPC-IR-MALS and TREF in order to determine the distribution of side chain branches. The results were discussed with respect to the time to failure FNCT.
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Dickinson, A. J. "Examination of the effects of processing variables on the mechanical properties of HDPE." Thesis, Manchester Metropolitan University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376539.
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Antreou, Evangelia. "Improved microwave-assisted pyrolysis of HDPE using catalysts and a fluidised-bed reactor." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648805.
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Senderski, Tatiane Aparecida. "Efeito do agente compatibilizante PE-g-MAH em blenda polimérica híbrida LSZH/HDPE." Universidade Tecnológica Federal do Paraná, 2016. http://repositorio.utfpr.edu.br/jspui/handle/1/2829.
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CAPES; CNPq; Fundação AraucáriaEste trabalho apresenta um estudo sobre o efeito do agente compatibilizante de anidrido maleico (PE-g-MAH) nas propriedades da blenda polimérica híbrida contendo o composto low smoke zero halogen e polietileno de alta densidade (LSZH/HDPE), visando a obtenção de um material adequado para uso em cruzetas separadoras de cabos de telecomunicações. Os requisitos exigidos a esta função são capacidade de isolamento elétrico, para evitar que os campos magnéticos gerados pelos pares condutores causem interferência na transmissão de dados dos pares adjacentes, e resistência à flamabilidade, devido à crescente preocupação sobre os riscos à saúde e ambientais no caso de incêndios. Os compostos LSZH são utilizados na fabricação de cabos por serem materiais resistentes à chama e livres de halogênios, porém não detém capacidade de isolamento elétrico. O HDPE é um material dielétrico, mas não possui a resistência à flamabilidade. O PE-g-MAH é um agente compatibilizante que melhora a resistência a flamabilidade de blendas poliméricas híbridas pelo aumento da dispersão das cargas antichama. A blenda LSZH/HDPE foi analisada com a adição de diferentes proporções de compatibilizante com o objetivo de se obter a proporção que apresenta propriedades mais adequadas à aplicação em cruzetas separadoras. Foram fabricadas amostras contendo 75% de LSZH-A (índice de oxigênio 33 %) com aplicação de 8%, 10% e 12% de PE-g-MAH, e amostras contendo 75% do LSZH-B (índice de oxigênio 37 %) com a aplicação de 10% e 12 % de PE-g-MAH em blendas. Observou-se que a adição do compatibilizante aumenta a dispersão das cargas antichama, melhora a resistência a flamabilidade e diminui a capacidade de isolamento elétrico da blenda. A proporção 75/13/12 LSZH-B/HDPE/PE-g-MAH apresentou as propriedades mais apropriada para emprego em cruzetas separadoras, com índice de oxigênio de 33,6%, constante dielétrica em 1 MHz de 3,06, resistividade volumétrica de 3,05.10 15 Ohm.cm, resistência a tração de 14,47 MPa e alongamento a ruptura de 412 %.
This paper presents a study on the effect of the compatibilizing PE-g-MAH on the properties of the hybrid polymer blends of low smoke zero halogen and high density polyethylene LSZH / HDPE, aiming at obtaining a suitable material for use in cross web of telecommunication cables. The requirements for this function are electrical insulation capability, to avoid electromagnetic interference between the conductor pair’s constituent of the cable, and resistance to flammability, due to the growing concern about the health and environmental risks in the event of fires. LSZH compounds are used in the manufacture of cables because they are flame-resistant and halogen-free materials, but have no electrical insulation capacity. HDPE is a dielectric material, but it lacks the flammability resistance. PE-g-MAH is a compatibilizing that improves the flammability resistance of hybrid polymer blends by increasing the dispersion of the flame retardant loads. The LSZH / HDPE blend was analyzed with the addition of different proportions of PE-g-MAH in order to obtain the proportion that presents properties more suitable for the application in cross web. Samples containing 8%, 10% and 12% PE-g-MAH were prepared in blends containing 75% LSZH-A (LOI 33 %) and 10% and 12% PE-g-MAH samples in blends containing 75% of LSZH- B (LOI 37 %). It was observed that the addition of PE-g-MAH increases the dispersion of the flame-retardants, improves the flammability resistance and decreases the electrical insulation capacity of the blender. The ratio 75/13/12 LSZH-B / HDPE / PE-g-MAH presented the most suitable properties for use in cross web, with oxygen index of 33.6%, dielectric constant at 1 MHz of 3.06, resistivity 3.05.1015 Ohm.cm, tensile strength of 14.47 MPa and elongation at break of 412%.
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Carvalho, Carina Henriques. "Estudo da formação de ráfias de HDPE no transporte de frascos para iogurte." Master's thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/3154.
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Mestrado em Engenharia QuímicaEsta Dissertação teve como objectivo analisar os factores que influenciam a formação de ráfias de HDPE ao longo das condutas de transporte de frascos para iogurte líquido, na fábrica Logoplaste Castelo Branco, e propor medidas para a sua minimização. No início do trabalho procedeu-se a uma revisão da literatura sobre o transporte pneumático de partículas e os problemas de degradação subjacentes a ele, bem como sobre ferramentas da qualidade que permitissem implementar metodologias de análise e de resolução do problema em causa. A partir do estudo acima referido, e da análise do problema na fábrica, foram identificadas possíveis causas para o problema, as quais foram organizadas recorrendo ao diagrama de causa-efeito. Em paralelo foi feito um levantamento das condições de produção numa outra fábrica da Logoplaste, em Oliveira de Azeméis, onde não se registavam problemas de formação de ráfias. A partir do diagrama causa-efeito construído, identificaram-se como potenciais causas da formação de ráfias (i) a velocidade de transporte dos frascos, a limpeza das condutas, a geometria e o número de curvas bem como a temperatura dos frascos à entrada da conduta de transporte e (ii) o coeficiente de atrito entre os materiais utilizados no fabrico dos frascos e nas condutas. As primeiras foram estudadas em fábrica e a segunda a nível laboratorial, na Universidade do Minho. Os resultados obtidos revelaram que a velocidade de transporte dos frascos, tal como era referido na literatura, é um parâmetro determinante e a sua redução conduziu à quase total eliminação da formação de ráfias. Relativamente ao efeito da limpeza das condutas, não foi possível concluir inequivocamente, se este factor é de facto determinante devido ao reduzido número de medições efectuadas. O efeito da temperatura dos frascos à entrada da conduta de transporte não se revelou significativo. No que concerne o efeito dos coeficientes de atrito, os resultados obtidos não permitiram visualizar diferenças significativas entre os frascos das fábricas de Castelo Branco e de Oliveira de Azeméis. Os coeficientes de atrito obtidos, para os diferentes materiais testados, apresentam valores muito próximos, à excepção da placa em HDPE, razão pela qual a utilização deste material nas condutas de transporte dos frascos deve ser evitada. Por fim, tendo em conta a importância da velocidade de transporte dos frascos e a sua relação com a formação de ráfia, foi desenvolvido um modelo que permitisse estimar o tempo que os frascos demoram a percorrer o trajecto da conduta a partir do caudal de ar fornecido e das características das condutas. Com vista à determinação da queda de pressão do ar nas condutas da Logoplaste, adaptou-se a equação diferencial de Bernoulli, referente ao transporte de um gás compressível e escoamento isotérmico numa conduta. Apesar da limitação de dados, as aproximações feitas permitiram estimar o valor da queda de pressão para a conduta em estudo. Tendo em conta a escassez de informação que permitisse (i) calcular os caudais de ar reais e (ii) os valores de queda de pressão com o rigor suficiente, os parâmetros do modelo desenvolvido foram ajustados recorrendo a algumas aproximações. O tempo de transporte dos frascos estimado foi de 3,2 s, o qual apresenta um erro de 31% quando comparado com o valor medido na fábrica de 4,2s. Tendo em conta a simplicidade do modelo desenvolvido, o facto da resolução do mesmo ter sido feita utilizando valores aproximados dos caudais de ar utilizados na fábrica e o facto do cálculo da esfericidade dos frascos ser aproximada é notável a boa previsão do modelo. ABSTRACT: The aim of this thesis was to analyze the factors responsible for the formation of streamer in the pipelines for conveying bottles of liquid yogurt, at Logoplaste Castelo Branco Company, and to propose ways to minimized it. A literature review on pneumatic transport and the problems underlying degradation of particles was initially carried out, together with a survey of Quality Assurance Tools in order to implement methodologies which could contribute to the analysis and subsequent solution of the problem. From the study aforementioned and the analysis of the problem at the factory site the possible causes have been identified which were organized using a cause-effect diagram. In parallel, for comparison purposes, the production conditions of another factory site, in Oliveira de Azeméis where the formation of streamer does not exist, were also studied. From the cause-effect diagram it was possible to identify as potential causes for the formation of streamer: (i) velocity of the conveying bottles, the geometry and number of curves/bends, the frequency and method of cleaning of the pipelines and the temperature of the bottles at the entrance of the conveying pipe and (ii) the friction coefficient between the different materials used in the bottles and in the pipelines. The former were studied at the factory site and the latter in the laboratory at Universidade do Minho. In agreement with the literature, reduction of the conveying bottles velocity proved to be a determinant parameter as the formation of streamer was almost eliminated. As regards the effect of pipelines cleaning, in view of the limited number of measurements carried out the results are inconclusive. The effect of the temperature of the bottles at the entrance of the conveying pipe does not seem to be of major importance. The results obtained for the friction coefficients between the materials evaluated did not show any major differences except for HDPE and this is the reason why such material should not be used in these pipelines. Finally, in view of the importance of conveying bottles velocity for the formation of streamer, a model has been developed to estimate the time required to transport the bottles across the pipeline based on the air flow rate and the characteristics of the pipeline. In order to determine the pressure drop in Logoplaste pipelines, the differential Bernoulli equation, for a compressible gas pipelines under isothermal conditions. Despite the scarcity of data, the approximations that were made allowed the estimation of the pressure drop of pipeline under study. In view of the shortage of data to calculate values for the pressure drop and for the air flow rate with reasonable accuracy, the parameters of the model developed had to be adjusted with some approximations. The estimated time of transport of bottles and the experimental one are 3,2 s and 4,2 s respectively corresponding to an error of 31%. Taking into account the simplicity of the model and the approximations involved in the calculation of the air flow rates and of the sphericity, the prediction of the model developed can be considered remarkable.
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Hudson, Benjamin S. "The Effect of Liquid Hot Filling Temperature on Blow-Molded HDPE Bottle Properties." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2716.pdf.
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Lindell, Wallgren Ida. "Alternativt material i behållare för konstgödselrampspridare : Förarbete för prototyp." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-11654.
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Överums Bruk AB tillverkar jordbruksmaskiner såsom konstgödselrampspridaren Wing Jet. Wing Jet har idag en konstgödselbehållare tillverkad i rostfritt stål och företaget önskar veta om det är möjligt och lämpligt att tillverka behållaren i plast/plastkomposit i syfte att minska produktionskostnaden av behållaren samt dess vikt. Detta arbete är begränsat till behållaren, övriga konstgödselspridaren ska inte behöva några förändringar för att byta den rostfria behållaren till en i plast/plastkomposit och det ingår inte i arbetet att tillverka en prototyp. Rotationsgjutning och handuppläggningsmetoden (glasfiberarmering) är två tillverkningsmetoder som är lämpliga att använda vid tillverkning av så stora objekt. Simuleringar av en rotationsgjuten behållare i materialet högdensitetspolyeten (HDPE) i programmet SolidWorks Simulation Standard resulterar i maximala effektivspänningar strax över materialets brottgräns då ett tryck baserat på ekvationer från europastandarden Eurocode 1-4: 2006 (Silor) anläggs på behållarens insida. Det uppstår dock deformationer på flera centimeter vilket i sig inte är ett problem, men det gör behållaren mindre estetiskt tilltalande (släta sidor buktar utåt). Behållarens vikt minskar till ca hälften av dagens och den är billigare att tillverka. Material och tillverkningsmetoder som resulterar i en behållare med högre styvhet i avseende att minska deformationen är rekommenderat att undersökas som vidare arbete. Exempel på detta är glasfiberarmerad polyester eller epoxi och ”sandwich”-konstruktioner. En sandwich-konstruktion består av två (eller fler) lager av ett material med en kärna, av t.ex. ett skum, mellan. Genomförda simuleringar är linjärelastiska, medan plaster allmänt är olinjära, så olinjära simuleringar bör genomföras innan prototyp tillverkas.Överums Bruk AB manufactures agricultural equipment such as the fertilizer spreader Wing Jet. Wing Jet has a container which today is manufactured from stainless steel and the company wishes to know if it is possible and suitable to manufacture the container from plastic/plastic composite with the purpose to lessen the containers production costs and weight. This work is limited to the container, the rest of the fertilizer spreader should not need any changes to switch the stainless steel container for a plastic/plastic composite one and the work does not include manufacturing a prototype. Rotational molding and hand lay-up (glass-fibre reinforcement) are two manufacturing processes which are suitable to use when manufacturing such large objects. Simulations of a rotational molded container in the material high density polyethylene (HDPE) in the program SolidWorks Simulation Standard results in maximum effective stresses just above the materials tensile strength when a pressure based on equations from the European standard Eurocode 1-4: 2006 (Silos and Tanks) are applied on the containers inside. However, deformations of several centimeters occurs which in itself is not a problem, though it makes the container less esthetically appealing (smooth sides bulges outward). The containers weight decreases to approximately half of that of today and it is cheaper to manufacture. Materials and manufacturing processes which results in a container with higher stiffness in the purpose of lessen the deformation is recommended to investigate as future work. Examples of this are glass-fibre reinforced polyester or epoxy and “sandwich”-constructions. A sandwich-construction is comprised of two (or more) layers of a material with a core, of e.g. foam, between. The simulations carried out are linear elastic, whereas plastics generally are non-linear, so non-linear simulations should be carried out before a prototype in manufactured.
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Guichard, Bryan. "Renforcement thermomécanique et amélioration des propriétés barrière aux essences du HDPE par des approches (nano)composites." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1031/document.
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Depuis quelques années, les polyoléfines et en particulier le Polyéthylène présentent un intérêt économique qui se traduit par un marché en croissance constante. Cependant, il est souvent nécessaire d’améliorer leurs propriétés d’usage notamment pour des problématiques liées à l’industrie automobile. Dans ce contexte, une amélioration des propriétés thermomécaniques et barrière aux vapeurs et liquides du Polyéthylène sur une gamme de température étendue constitue un nouveau challenge scientifique et environnemental. Dans cette étude, nous avons tout d’abord étudié l’impact de charges inorganiques et d’un recuit à 125°C sous air sur les propriétés thermomécaniques d’un HDPE. Le deuxième axe de recherche s’est concentré sur l’amélioration des propriétés barrière aux essences de ce polymère en favorisant les charges lamellaires pour leur haut facteur de forme induisant un effet de tortuosité élevé. L’impact de ce type de charges sur les phénomènes de sorption et d’extraction a été étudié dans le but de définir une formulation à base HDPE optimale pour limiter la perte physique d’oligomères et d’antioxydants. Le but de ces travaux étant de mieux comprendre les différents mécanismes mis en jeu, nous avons cherché à établir les relations Structure / Morphologie / Propriétés pour les deux axes d’étude développésIn the recent years, the use of polyolefin and especially Polyethylene are of economic interest resulting in a growing attention concerning the improvement of its properties of use, especially for automotive application. In this context, the reinforcement of its thermomechanical properties and the improvement of its barrier properties to different fuels over an extended temperature range constitute a major scientific and environmental challenge. In this study, we first decided to analyze the impact of silica particles and of an annealing at 125°C under air atmosphere on thermomechanical properties of a HDPE. The second area of research was focused on the improvement of its barrier properties to fuels by the addition of lamellar charges known for their high aspect ratio inducing a tortuosity effect. The impact of these particles on sorption and extraction phenomena was also studied to determine an optimal HDPE-based formulation in order to limit the physical loss of oligomers and antioxidants. The guideline of this project was the determination of Structure / Morphology / Properties relationships to have a better understanding of the involved mechanisms
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Sandoval, Paredes Carla María. "Análisis de los parámetros de la termofusión manual a socket en tuberías de HDPE." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2014. https://hdl.handle.net/20.500.12672/12742.
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La demanda de gas natural para fines domésticos ha hecho que aumente el ritmo de construcción de redes de polietileno de baja presión. La construcción de este tipo de redes implica el uso de técnicas de unión confiables, una de las cuales es la termofusión manual a socket. Dicha técnica es usada en otros países como Colombia y Venezuela. Sin embargo, existen diferencias entre los procedimientos utilizados, pues los parámetros como temperatura y tiempo de la fusión cambian. Por tal motivo, es necesario seleccionar adecuadamente los parámetros de fusión. El presente trabajo analiza estos parámetros en tuberías de HDPE tipo PE 80 de diámetros nominales de 32 y 20 mm, unos de los más utilizados en la construcción de redes de distribución para alimentar instalaciones residenciales.Trabajo de suficiencia profesional
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Contreras, Almidón Joaquín Alejandro. "Instalación de tuberías de polietileno (HDPE) para redes de alcantarillado: colector Torres de Marcavalle." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2005. https://hdl.handle.net/20.500.12672/11026.
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El documento digital no refiere asesorDescribe el proceso de instalación y habilitación de tuberías de polietileno (HDPE) para alcantarillado sanitario. Muestra las normas vigentes de instalación para el referido sistema y además muestra las especificaciones técnicas para la obra como; Colector Torres de Marcavalle con tubería de polietileno (HDPE) φ 8” en la ciudad de La Oroya - Yauli - Junín. También da mayor énfasis al sistema de control de calidad de la unión por termo fusión de las tuberías y las especificaciones técnicas que se tendrán en cuenta durante la ejecución de los trabajos. En la instalación del Colector “Torres de Marcavalle” ubicado en la ciudad de La Oroya – Yauli – Junín, se utiliza tubería de polietileno (HDPE) que cumple con la norma NTP ISO 8772 Tubos y Conexiones de Polietileno de Alta Densidad (HDPE), para sistemas enterrados de drenaje y alcantarillado. Se ejecuta teniendo en cuenta todos los aspectos técnicos contenidos en dicha Norma. Se concluye que el objetivo primordial es mejorar el sistema de recolección de aguas servidas del sector Torres de Marcavalle que pertenecen a DOE RUN PERU en la ciudad de La Oroya. Forman parte del proyecto Sewage, que además contempla similares obras para los sectores de Chulec, Sudete y Fundición.
Trabajo de suficiencia profesional
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Poma, García Charles. "Metodología de la instalación de tubería polietileno (HDPE) para emisor submarino industrial pesquero - Chimbote." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2013. https://hdl.handle.net/20.500.12672/12208.
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Elabora la metodología de instalación de tubería de polietileno (HDPE) para emisor submarino industrial pesquero, que nos permitirá solucionar el problema de la contaminación de los diferentes cuerpos de agua, ya que es un fenómeno que responde al creciente grado de actividad contaminante que se viene dando en las últimas décadas. El desarrollo de los procesos industriales y el incremento de transporte marítimo aunado al crecimiento poblacional han incidido en un brusco y extraordinario aumento en la recepción de los cuerpos de agua de sustancias externas contaminantes. El estudio determina el proceso de instalación del emisor submarino que brindara el servicio de disposición final de los efluentes generados por cada una de las empresas industriales pesqueras asociadas a APROCHIMBOTE. La recolección de los efluentes residuales previamente tratados, se realiza a través de tuberías, por lo que, en La Estación de Bombeo y en las respectivas Sub Estaciones de Bombeo, no se realizará ningún tratamiento en dichas instalaciones, ya que están recibiendo un efluente previamente tratado, con una calidad menor o igual a los Límites Máximos Permisibles establecidos en el D.S. N°010-2008-PRODUCE. Posteriormente, a través de un proceso de bombeo el efluente es trasladado hasta su disposición final ubicada fuera de la bahía, todo esto se realizará a través de un Emisor Submarino de Aprox. 4.2 Km de longitud. El punto de descarga o disposición final, se encuentra fuera de la bahía a una profundidad de Aprox. 30 metros, de grandes corrientes de dirección sur - norte, donde se logrará una dilución de 460 veces.Trabajo de suficiencia profesional
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Ayche, Nadim S. "The Effect of High Density Polyethylene (HDPE) Pipe Profile Geometry on its Structural Performance." Ohio University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1127140719.
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Lopez, Rodrigo, Christopher Arnold, Jesus Valencia, and Rex Tan. "Evaluation of HDPE and UHMWPE Sintering Process for the Production of Durable, Porous Plastic." Thesis, The University of Arizona, 2012. http://hdl.handle.net/10150/244432.
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Shaheer, Muhammad. "Effects of welding parameters on the integrity and structure of HDPE pipe butt fusion welds." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/16919.
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Butt fusion welding process is an extensively used method of joining for high density polyethylene (HDPE) pipe. With the increasing number of HDPE resin and pipe manufacturers and the diversity of industries utilising HDPE pipes, a wide range of different standards have evolved to specify the butt fusion welding parameters with inspection and testing methods, to maintain quality and structural integrity of welds. There is a lack of understanding and cohesion in these standards for the selection of welding parameters; effectiveness, accuracy, and selection of the test methods and; correlation of the mechanical properties to the micro and macro joint structure. The common standards (WIS 4-32-08, DVS 2207-1, ASTM F2620, and ISO 21307) for butt fusion welding were used to derive the six welding procedures. A total of 48 welds were produced using 180 mm outer diameter SDR 11 HDPE pipe manufactured from BorSafe™ HE3490-LS black bimodal PE100 resin. Three short term coupon mechanical tests were conducted. The waisted tensile test was able to differentiate the quality of welds using the energy to break parameter. The tensile impact test due to specimen geometry caused the failure to occur in the parent material. The guided side bend specimen geometry proved to be too ductile to be able to cause failures. A statistical t-test was used to analyse the results of the short term mechanical tests. The circumferential positon of the test specimen had no impact on their performance. Finite element analysis (FEA) study was conducted for the long term whole pipe tensile creep rupture (WPTCR) test to find the minimum length of pipe required for testing based on pipe geometry parameters of outer diameter and SDR. Macrographs of the weld beads supplemented with heat treatment were used to derive several weld bead parameters. The FEA modelling of the weld bead parameters identified the length to be a key parameter and provided insight into the relationship between the geometry of the weld beads and the stresses in the weld region. The realistic bead geometry digitised using the macrographs contributed a 30% increase in pipe wall stress due to the stress concentration effect of the notches formed between the weld beads and the pipe wall. The circumferential position of the weld bead had no impact on the pipe wall stresses in a similar manner to the results of the different mechanical tests. IV Nanoindentation (NI) and differential scanning calorimetry (DSC) techniques were used to study the weld microstructure and variation of mechanical properties across the weld at the resolutions of 100 and 50 microns, respectively. NI revealed signature 'twin-peaks and a valley' distribution of hardness and elastic modulus across the weld. The degrees of crystallinity obtained from DSC followed the NI pattern as crystallinity positively correlates with the material properties. Both techniques confirm annealing of the heat affected zone (HAZ) material towards the MZ from the parent material. The transmission light microscopy (TLM) was used to provide dimensions of the melt zone (MZ) which displays an hour glass figure widening to the size of the weld bead root length towards the pipe surfaces. Thermal FEA modelling was validated using both NI and TLM data to predict the HAZ size. The HAZ-parent boundary temperature was calculated to be 105 ⁰C. The 1st contribution of the study is to prove the existence of a positive correlation between the heat input calculated from FEA and the energy to break values obtained from the waisted tensile test. The 2nd contribution providing the minimum length of pipe for WPTCR based on the pipe dimensions. The 3rd contribution is the recommendation for the waisted tensile test with the test using the geometry designed to minimise deformation of the loading pin holes. The 4th contribution related the weld bead parameters to pipe wall stresses and the effect of notches as stress concentrators. The 5th contribution is a new method of visualising a welding procedure that can be used to not only compare the welding procedures but also predict the size of the MZ and the HAZ. The 6th contribution of the study is the proposal of new weld bead geometry that consist of the MZ bounded by the HAZ, for butt fusion welded joints of HDPE pipes.
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Hidalgo, Chávez Luis Carlos, and Díaz Fabio César Valencia. "Propuesta de mejora en el proceso de unión térmica en la fabricación de tubos de HDPE." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2017. http://hdl.handle.net/10757/621277.
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El objetivo de la tesis es reducir la entrega de productos fuera de plazo. Específicamente se aplicarán las herramientas de Ingeniería Industrial para cumplir con lo siguiente: Identificar procesos que puedan optimizarse para reducir tiempos de ejecución o restricciones en ellos. Establecer un plan de mantenimiento y medidas proactivas para evitar fallas intempestivas que paralizan el flujo de producción. Optimizar el recurso humano, formando personal eficiente y eficaz (Empowerment). La metodología de diagnóstico empleada inició con el levantamiento de información y aplicación de herramientas de Ingeniería Industrial para establecer la causa raíz del problema. Una vez determinada esta causa principal, se evaluaron y ejecutaron distintas metodologías tales como Teoría de Restricciones y herramientas de Sistemas Esbeltos (Lean). Con la ejecución de cada etapa y paso de las metodologías mencionadas se espera como resultado principal la reducción de las entregas de los productos fuera de plazo y la viabilidad económica adecuada para su implementación.Tesis
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Devkota, Jay P. "Variation of Manning’s Roughness Coefficient with Diameter, Discharge, Slope and Depth in Partially Filled HDPE Culverts." Youngstown State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1340991250.
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Shaheen, Ehab T. "Long Term Performance of Corrugated HDPE Pipes Produced with Post-Consumer Recycled Materials Under Constant Deflection." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1541422245636659.
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Mesquita, Fábio Agnelli. "Modificação das propriedades do polietileno de alta densidade por diferentes condições de extrusão." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-10012011-103025/.
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Devido à grande produção industrial do PEAD, o entendimento e controle de sua degradação durante o processamento é um importante objeto de estudo tanto para a indústria como no âmbito acadêmico. A degradação do PEAD pode ocorrer em qualquer estágio, desde a sua produção até o seu uso final, mas, para a maioria das aplicações, a fase em que ocorre a maior degradação e de forma mais rápida é durante o processamento, quando o polímero é exposto a condições severas de cisalhamento e temperatura. Este trabalho teve como objetivo avaliar as alterações na estrutura química e nas propriedades do PEAD provocadas por diferentes condições de extrusão (variando os perfis de temperatura) e com diferentes aditivos antioxidantes. Foi escolhido um PEAD bimodal de alta massa molar produzido no Brasil com catalisador Ziegler-Natta, destinado para a produção de filmes que são usados principalmente na produção de sacolas, bobinas picotadas e sacos para lixo. As amostras foram analisadas por diferentes técnicas: Cromatografia Líquida de Alta Eficiência (HPLC - High Performance Liquid Chromatography), Colorimetria, Tempo de Indução Oxidativa (OIT - Oxidation Induction Time), Espectroscopia no Infravermelho por Transformada de Fourier (FTIR - Fourier Transform Infrared Spectroscopy), Fracionamento por Cristalização (CRYSTAF - Crystallization Analysis Fractionation), Cromatografia por Permeação em Gel (GPC - Gel Permeation Chromatography), Índice de Fluidez (MFI Melt Flow Index) e Reometria. Os resultados mostraram uma sinergia muito grande entre o antioxidante primário tetrafenólico e o secundário fosfito na proteção da degradação do PEAD. No entanto, esses antioxidantes provocaram maior alteração de cor (Índice de Amarelecimento). Além disso, maiores temperaturas de processo provocaram maior grau de cisão das cadeias para o PEAD sem antioxidantes, mas isso foi menos efetivo com a proteção dos antioxidantes.Considering the large production of HDPE, understanding and controlling of its degradation during processing is an important issue for studies in both industry and academy. The degradation of HDPE may occur at any stage from manufacture to final disposal, but for the majority of applications the degradation during melting is observed to be faster and with higher intensity, due to polymer exposition to severe conditions of shear and to high temperatures. The present work aimed to evaluate chemical and properties changes of HDPE after different processing conditions (shifting temperature profiles) and with different antioxidant additives. The selected polymer was a bimodal HDPE produced in Brazil by Ziegller-Natta catalyst, which has been used to retail bags, perforated rolls and garbage bags. Samples were analyzed by different techniques as HPLC (High Performance Liquid Chromatography), Colorimetry, OIT (Oxidation Induction Time), FTIR (Fourier Transform Infrared Spectroscopy), CRYSTAF (Crystallization Analysis Fractionation), GPC (Gel Permeation Chromatography), MFI (Melt Flow Index) and Reometry. The results showed an intensive synergic effect between primary tetra phenolic and secondary phosphite antioxidants for the HDPE protection against degradation. On the other hand, these antioxidants caused strong color modifications, with regards to the Yellowness Index. In addition, higher processing temperatures increased chain scission of HDPE without antioxidant, but this effect was less effective after antioxidants protection.
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Gabriel, Leandro. "Preparação, irradiação e caracterização de blendas PEAD reciclado/EPDM." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-24112016-143050/.
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A reciclagem de refugos é um processo estratégico que viabiliza a expansão do mercado de plásticos, podendo gerar novos produtos. A obtenção de blendas poliméricas é uma alternativa nesse processo, já que é conhecida a perda de propriedades mecânicas dos termoplásticos nas etapas de reprocessamento. Neste trabalho, o polietileno de alta densidade (PEAD) reciclado teve adições de borracha do monômero etileno-propileno-dieno (EPDM) puro em baixos teores (1 %, 5 % e 10 %), cujo objetivo foi formar blendas miscíveis e um produto final mais resistente ao impacto. O PEAD foi submetido a quatro ciclos de moagem, extrusão e injeção (reprocessamento) e misturado ao EPDM puro por extrusão sem o uso de qualquer aditivo. Os grânulos da blenda formada foram usados para confeccionar os corpos-de-prova por injeção para seu uso nas distintas metodologias analíticas. O processo de irradiação gama foi aplicado nas doses de 50 kGy e 100 kGy e os parâmetros físico-químicos e mecânicos dessas amostras foram comparados aos das não irradiadas. Tanto as blendas irradiadas como as não irradiadas mostraramse visualmente e microscopicamente homogêneas, indicando a compatibilidade da mistura, que também é verificada por seu comportamento térmico. Os parâmetros mecânicos provenientes dos ensaios de tração e flexão, foram semelhantes nas amostras do termoplástico virgem e do reciclado; o processo de irradiação nas blendas gerou sua reticulação, sendo esta verificada não só pelo aumento dos valores desses parâmetros como também pelo aumento da fração gel. A resistência ao impacto aumentou cerca de duas vezes e meia nas amostras com maior teor de EPDM e cerca de 6 a 7 vezes nestas mesmas amostras irradiadas a 50 kGy e 100 kGy respectivamente. O novo material obtido tem fortes indicativos para a sua utilização na pequena e média indústria de plástico, uma vez que já com 1 % de EPDM apresentam melhores características mecânicas em relação ao termoplástico reciclado quatro vezes e essas características foram incrementadas após o processo de irradiação gama.Waste recycling is a process that allows for advances in plastics industry, particularly when new products are developed. Thus polymer blending is an alternative to recycling processes, since degradation of the mechanical properties of thermoplastics occurs during the reprocessing stages of the material. In this work, high density polyethylene (HDPE) was recycled and mixed to ethylene propylene diene pristine rubber (EPDM) in low concentrations (1%, 5 % and 10 %) to obtain a miscible blend and a final product with high resistance to impact. Pristine HDPE was submitted to four cycles of milling, extrusion and injection (reprocessing) and then mixed with EPDM by extrusion, free of any additives whatsoever. The resulting material was then injected to obtain standard samples submitted to several analytical methods during this research. Also, gamma irradiation process was performed with 50 kGy and 100 kGy absorbed doses; the physical-chemical and the mechanical parameters of these samples were compared to non-irradiated samples. Irradiated and non-irradiated blends were visually and microscopically homogeneous. This indicates a compatible mixture, something which was also verified from analysis of their thermal behavior; mechanical parameters such as stress-strain and flexural curves were similar for pristine and recycled HDPE thermoplastic. On the other hand, the irradiation process on blends generates thermoplastic molecular cross-linking which is verified from increased strength values of mechanical and gel fraction tests. Impact resistance had a 2.5 fold increase with samples with higher EPDM content and about 6-7 fold increase on irradiated samples with 50-100 kGy respectively. These new materials are aimed to small and medium-scale industries, for adding as low as 1% EPDM to the blends sharply improves their mechanical characteristics when compared to recycled thermoplastic. Also, these characteristics improve even further when these materials are gamma irradiated.
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Waldron, Calvin Michael. "The Recovery and Transfer of Aerosolized Listeria Innocua." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/78907.
Full textAbstract:
Airborne pathogenic bacteria can present a significant public health risk. Pathogenic Listeria monocytogenes can colonize numerous surfaces as well, through direct and indirect cross contamination. The physical environment can also affect the transmission and viability of Listeria (distance from the source, temperature, humidity, air flow). The purpose of this work was to explore the ability of Listeria innocua (a surrogate for L. monocytogenes) to contaminate a surface after it has become aerosolized in a bioaerosol chamber and a walk-in cooler.
L. innocua was nebulized into a 154 L biosafety chamber (~5 log CFU in 1 mL) at two relative humidity (RH) levels (83% and 65%). Oxford Listeria agar plates, stainless steel coupons and polyethylene (HDPE) coupons in the chamber were exposed to the aerosolized bacteria for 5, 10, 20 or 40 minutes. Also, at these times, air samples (100 L) were collected on to gelatin filters which were transferred to Oxford agar plates. In the second part of the research, L. innocua was nebulized into an 11 m3 walk-in cooler where RH ranged from ~29-37%. Aerosolized bacteria were collected on to Oxford agar plates for 10 min intervals and with 50 or 100 L air samples.
Recovery of L. innocua from steel, plastic and agar was significantly higher at 83% RH (2.7 cells/cm2) compared to 65% RH (0.45 cells/cm2). Mean cell recovery from air samples (gelatin filters) was significantly higher (p<0.05) when collected 5 or 10 minutes after nebulization at 83% humidity (mean 2.2 CFU/L) compared to collection after 20 or 40 minutes or compared to all times under 65% humidity (mean 0.4 CFU/L). Recovery from HDPE coupons (1.21 CFU/cm2) was 2.5 X recovery from Oxford agar (0.49 CFU/cm2). In the walk-in cooler, total estimated mean recovery from Oxford media at 10 min after nebulizing was 0.48%, but only 0.04% for samples collected after 60 minutes. The recovery of L. innocua from air samples after 60 min was one-fourth of the number recovered 5 min after nebulizing. No significant difference in recovery was found between plates at different distances (2 – 2.5 m) from the nebulizer in the walk-in cooler. Understanding the survival of aerosolized Listeria and how it can colonize over time on a food contact surface will enhance our efforts to prevent transmission on a small and large scale. The food industry will be able to implement better safety measures to prevent contamination by Listeria species.Ph. D.
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Pino, Monica. "Apatite deposition on NaOH-treated HDPE, PEEK and UHMWPE films for sclera materials in artificial cornea implants." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/1896/.
Full textAbstract:
Corneal disease is the second most common cause of blindness in the word. It is estimated that 45 million people worldwide are bilaterally blind and 10 million are affected by corneal blindness. Corneal blindness mostly affects the population in the equatorial zone, due to the high exposure to UV light. Corneal grafting presents complications such as rejections and the lack of donor material and resources. Conventional cornea grafting (keratoplasty) is not advised for patients with bilateral corneal blindness or for those who suffer from a range of clinical problems including tear deficiency, chemical burns and uncontrollable intraocular pressure. At present, an artificial cornea, i.e. a keratoprosthesis (KRPO), is the only alternative to keratoplasty (corneal donor transplantation). Cornea implants consist of a clear optic part and a surrounding ring known as the skirt, which needs to integrate with the sclera of the eye. Currently used skirt materials lead to poor tissue integration, a major failure of cornea implants. Better integration may be achieved when using a bioactive skirt material, which adapts to the metabolic activity of the cornea. For this purpose, high density polyethylene (HDPE), polyether ether ketone (PEEK) and ultra-high molecular weight polyethylene (UHMWPE) films provide interesting possible alternatives, if they can be rendered bioactive. This study investigated the potential of using surface modified polymer films to fabricate the skirt. To improve bioactivity of the materials a two-step treatment using chemical surface modification (immersion in NaOH) and formation of apatite layers from Simulated Body Fluid (SBF) was applied. The effectiveness of the different molarity of the NaOH on the formation of the bioactive layer was investigated. Results showed that with an increase in NaOH concentration the wettability improved but also some changes to the topography (increase/decrease of roughness) of the polymers were observed. Moreover, 10M NaOH treatments resulted in more rapid formation of the apatite layer when compared with a non-treated and lower molarity solution. As immersion time in SBF increased, further nucleation and growth produced a thicker apatite layer which can be expected to be highly bioactive. Interestingly, the apatite growth is dependent on both the concentration of NaOH solution and the structure of the polymer surface. It was concluded that hydroxyapatite layers were formed on HDPE, PEEK and UHMWPE films after they were incubated in 1.5 SBF, which promises to render such thin-film structures bioactive – a necessity if they are to be integrated into artificial cornea. The Ca/P molar ratio of the apatite deposited on the polymers increases with NaOH strength and SBF incubation time. The favourable effect of NaOH on apatite formation may at least partly be attributed to an increased wettability of the polymer films after such treatment, as well as to the modified topography. The apatite layer contained phosphate and carbonates ions, providing potentially good in vitro bioactivity on polymeric films. The inorganic layers are chemically stable as the calcium deposited on the films did not dissolve fully when immersed in water for one week. This demonstrates that polymer films can be rendered bioactive, using the described approach, hence providing potential materials suitable for artificial cornea implants.
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Enriquez, Sevilla Luis Javier. "Activity of phosphite antioxidants in synergistic blends in the thermal and photooxidation of high-density polyethylene (HDPE)." Thesis, Manchester Metropolitan University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364483.
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