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Dissertations / Theses on the topic 'Polypropene'
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1
Norris, Timothy Scott. "Surface treatments for adhesive bonding of polypropene." Thesis, Oxford Brookes University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261262.
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Tvrdý, Michal. "Stanovení kinetiky polymerace propenu na Zieglerových-Nattových katalyzátorech metodami násadové polymerace a Stopped-Flow za průmyslových podmínek." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401930.
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This thesis is focused on the determination of the propene polymerization kinetics on phthalate and nonphthalate diester Ziegler-Natta MgCl2-supported catalysts under the industrial conditions. The kinetic profiles were determined by various laboratory techniques for propene polymerization. For assessing the profiles were utilized batch gas and liquid polymerization modes in 2-litre and 4-litre reactors. Finally, the results were complemented with the runs performed in a unique Stopped-Flow apparatus, which allows polymerization of liquid propene at very short polymerization times. The kinetics profiles of both catalysts were determined and compared by combination of experimental data of these techniques. The basic properties of the synthesized polymeric powders were measured, such as the melt flow index, bulk density and amount of polypropene fraction soluble in cold xylene.
3
Tang, Eunice Wai Chong. "Preparation and characterization of polypropylene-polypropylene (PP-PP) composites /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?MECH%202003%20TANG.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 91-95). Also available in electronic version. Access restricted to campus users.
4
Wang, Xiaowei. "Adhesive bonding of polypropylene." Thesis, University of Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247559.
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Işık, Kıvanç Tanoğlu Metin. "Layered silicate/polypropylene nanocomposites/." [s.l.]: [s.n.], 2006. http://library.iyte.edu.tr/tezler/master/makinamuh/T000532.pdf.
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Ekstam, Hanna, and Benjamin Quarmochi. "Design av infästningsanordning för virveldämpare på drönare." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-106215.
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Arbetet syftar till att ta fram en hållbar infästning för virveldämpare till SSRS drönare av modell flygande vinge. Drönaren är specifikt framtagen för att användas till maritima sök och räddningsuppdrag och för att bidra till att utöka den svenska kustens säkerhet. Arbetet studerar ett landningsscenario för drönaren och utifrån detta tas en ny infästning fram. Infästningen av virveldämparen skall vara lätt att hantera för personalen, kräva minimalt med reparation och hålla för 50 landningar. Infästningen skall kunna utlösa och separera virveldämparen från vingen om det under landningen uppstår så stora krafter att dessa komponenter riskerar att ta skada. Arbetet följer DRM-struktur och syftar till att ta fram en prototyp med hjälp av en uttömmande idégenerering utförd med metoderna Speedstorming, Brainstorming och SCAMPER. Konceptsållningen sker med hjälp av anpassade poängsättningsmetoder och Pugh-analys. Det resulterande konceptet bestämmer vilka dimensioner som krävs för att kunna utföra hållfasthetsberäkningar på den valda infästningen, därefter skapas en prototyp vilken används för att utföra hållfasthetstester. De utförda beräkningarna och testerna gav olika resultat och den därav dragna slutsatsen medförde att materialegenskaper rörande elastisk deformation och variabler på hållfasthetstestet ej har beaktas. Testerna visade att den framtagna prototypen av expanderad polypropen hanterade de förutsedda krafterna väl även om testerna inte kunde utföras under helt verklighetstrogna landningsförhållanden. Slutresultatet av projektarbetet är att den framtagna infästningen av virveldämparen har, utifrån tillgängliga testningsmetoder, påvisat önskade egenskaper och att utförligare tester behöver genomföras för att avgöra om den uppfyller samtliga produktkrav.This work is aimed at producing durable attachments for winglets on a drone, model flying wing, owned by the SSRS. The drone is specifically developed to be used for maritime search and rescue missions and to contribute to increasing the security along the Swedish coast and major inland lakes. During this work only one landing scenario by the drone was studied while creating the attachments, which required to be easy to handle, minimal to no repair work and a durability for 50 landings. The attachments also need to be able to release in case of excessive force during landing which risks jeopardizing the integrity of the wing or winglet. The work followed the DRM-structure and aimed to create a prototype through an exhaustive idea generation technique in three steps using the methods Speedstorming, Brainstorming and SCAMPER. All of these methods go through voting, Pugh analysis and concept screening. After one concept had been singled out its dimensions were decided on and used in calculations to determine its strength. From this information a physical winglet attachment prototype made of expanded polypropylene was created and used in strength and durability tests. Calculations and tests were found to have varying results and the conclusion was made that the material properties regarding elastic deformation and test variables most likely had not fully been taken into account. The tests failed to generate a realistic landing scenario given the requirements but still gave a positive result concerning the prototype's ability to absorb shock loads at landing. This work has resulted in a preliminary winglet attachment prototype which through testing has shown satisfying shock absorbing abilities, and that further testing is required to decide whether the attachment can meet all of the set product requirements.
7
Yilmaz, Sule Seda. "Preparation And Characterization Of Organoclay-polypropylene Nanocomposites With Maleic Anhydride Grafted Polypropylene Compatibilizer." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613291/index.pdf.
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The aim of this study was to improve the mechanical properties &ldquoMoplen&rdquo
EP300L which is a heterophase copolymer. Polymer blends and nanocomposites were prepared by melt compounding method in a twin screw extruder. Nanofil®
5 (N5) and Nanofil®
8(N8) were used as the organoclays, and maleic anhydride grafted polypropylene (M) was used as the compatibilizer. The effects of additive concentrations and types of organoclays on the morphology, mechanical and thermal properties were investigated. Organoclay loading over 2 wt% prevented the intercalation mechanism resulting in large aggregates of clay, thus the material properties became poor even in the presence of compatibilizer. Compatibilizer addition improved the intercalation ability of the polymer, however a substantial increase in mechanical properties was not obtained up to 6 wt % loading of the compatibilizer. XRD analysis revealed that intercalated structures were formed with the addition of compatibilizer and organoclay. The nanocomposites that were prepared with N5 type organoclay showed delaminated structures at 6 wt % compatibilizer loading. v Nanofill ®
5 exhibited the highest improvements in mechanical properties, since the degree of organoclay dispersion was better in Nanofill ®
5 containing nanocomposites in comparison to Nanofill ®
8 containing ones. The DSC analysis indicated a insignificant reduction in the melting temperature of the ternary nanocomposites.
8
Lepoutre, Priscilla. "The microstructure of polypropylene blends with ethylene vinyl alcohol copolymer and maleated polypropylene /." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61816.
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Njoroge, Daniel [Verfasser]. "Thesis: Preparation and characterization of modified-graphene oxide/polypropylene nanocomposites : polypropylene nanocomposites / Daniel Njoroge." Berlin : epubli, 2016. http://www.epubli.de/.
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Can, Semra. "Characterization Of Serpentine Filled Polypropylene." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609434/index.pdf.
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ABSTRACT
CHARACTERIZATION OF SERPENTINE FILLED POLYPROPYLENE
Can, Semra
Ph.D., Department of Polymer Science and Technology
Supervisor: Prof. Dr. Teoman Tinçer March 2008, 158 pages In this study, the aim is to prepare polypropylene (PP)/serpentine composites and study their mechanical, thermal and morphological properties. Another objective is to explore whether it is possible to have PP/serpentine nanocomposites with melt intercalation method by using the advantage of the layer silicate structure of serpentine. The most widely used fillers in PP are talc and mica which belong to the phyllosilicates group of silicate minerals. So far, there has been almost no study employing serpentine as filler in either any polymers or PP, although it also belongs to the same group of minerals as talc and mica. Accordingly, it was planned to divide the work into the study of two groups. In group 1, for the compositions with 2, 5, 10 and 20 wt% serpentine, the particulate filler effects of serpentine both alone and in the presence of surface treatments with hydrochloric acid (HCl) and silane coupling agent (SCA) were investigated. The most impressive results in terms of static and dynamic mechanical properties were achieved with SCA rather than HCl. When the effect of serpentine without any treatment is considered, reinforcing effect of it can easily be observed without deteriorating the composite properties even at high filler loadings. In group 2, the nanofiller effects of serpentine in 2 and 5 wt% filled compositions by modification of both the filler and the matrix were aimed to be examined with melt intercalation method. In addition to HCl and SCA treatments, maleic anhydride grafted polypropylene (PP-g-MA) and quaternary ammonium salt (QAS) of cetyl-trimethyl-ammonium bromide were used as compatibilizer and intercalating agent, respectively. While the amount of QAS was kept constant, different percentages of compatibilizer were employed. The presence of QAS and PP-g-MA further improved the properties with respect to group 1 members. Interestingly, the percentage strain at break values did not decrease as much as group 1 compositions with the same filler content. It can be concluded that partial intercalation of group 2 compositions was achieved, according to the X-ray and TEM results. Keywords: Serpentine, PP/serpentine composites, SCA, PP-g-MA, serpentine nanocomposites
11
Mizutani, T., E. Nakane, K. Kaneko, and M. Ishioka. "Space Charge Dynamics in Polypropylene." IEEE, 2004. http://hdl.handle.net/2237/7166.
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Sura, Ravi Kishore. "Oriented crystallization of syndiotactic polypropylene." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/8293.
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13
Köller, Frank. "Modifizierte Polypropylene durch Metallocen-Katalyse." [S.l. : s.n.], 1998. http://deposit.ddb.de/cgi-bin/dokserv?idn=961143738.
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GIROIS, STEPHANE. "Photooxydation du polypropylene : aspects cinetiques." Paris, ENSAM, 1995. http://www.theses.fr/1995ENAM0041.
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Nous avons porte un nouveau regard sur la photooxydation du polypropylene homopolymere et d'un copolymere ethylene-propylene en utilisant des outils cinetiques pour decrire le mecanisme de photooxydation dans un but de prediction de duree de vie. La demarche consiste a identifier les produits d'oxydation formes par irtf en fonction de la duree d'exposition aux uv a differentes temperatures sous differentes intensites lumineuses, et se basant sur un mecanisme cinetique en boucle fermee, de proposer un modele qui caracterise la photoodegradation du materiau en fonction des conditions d'exposition. Le vieillissement photochimique de films minces ou l'oxydation n'est pas controlee par la diffusion de l'oxygene suggere un mecanisme efficace de coupure de chaine des le debut de l'exposition. La prise de masse des films dans la periode initiale caracterise une certaine homogeneite macroscopique de l'oxydation. Le caractere autoaccelere de l'accumulation des produits d'oxydation dans cette periode initiale et lineaire par la suite est compatible avec le schema cinetique en boucle fermee, c'est a dire une reaction en chaine dans laquelle la seule source de radicaux est la decomposition des hydroperoxydes par voie monomoleculaire. La vitesse elevee du processus de perte de masse ne peut etre expliquee que par un mecanisme de retroscission en cascade identique a une depolymerisation. L'etude de la photooxydation de pieces epaisses se traduit par la formation d'un profil d'oxydation dans une couche superficielle caracteristique d'un regime controle par la diffusion de l'oxygene. Les resultats suivent un comportement qui s'ecarte du modele theorique qui voudrait que l'epaisseur de la couche oxydee (eco) soit inversement proportionnelle a l'intensite. Nous avons attribue cette ecart a la microfissuration de surface qui permet a l'oxygene de penetrer dans les couches internes du materiau. Neanmoins, conformement au mecanisme cinetique en boucle fermee, eco varie peu avec l'intensite lumineuse. L'analyse par chromatographie d'exclusion sterique confirme la predominance d'un processus de coupure de chaine tres efficace qui s'accompagne neanmoins d'actes de reticulation en quantite significative. Le fait que la polymolecularite diminue avec l'oxydation est compatible avec l'hypothese d'un processus de coupure de chaine pseudo aleatoire a relative petite echelle
15
Menke, Tammo J. "Massschneidern der Eigenschaften von Polypropen-Mischungen und Olefincopolymeren." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964145863.
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Tam, Mei San. "Study of sisal fiber-reinforced polypropylene, polyethylene and polypropylene/polyethylene blend composites prepared by compression molding." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21175123a.pdf.
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Thesis (M.Sc.)--City University of Hong Kong, 2005.At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.
17
Msuya, Winston Filipo Seth. "The influence of physical ageing and morphology on yield in polypropylene." Thesis, [Hong Kong] : University of Hong Kong, 1988. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12434036.
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18
Lee, Tiehong. "A study of miscibility, morphology, crystallization and melting behavior of isotactic poly(propylene) in blends of poly(propylene) and poly(1-butene)." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-07292009-090250/.
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Psarreas, Alexandros. "Nitroxide-mediated controlled degradation of polypropylene." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2832.
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Nitroxide-mediated Controlled Degradation of Polypropylene Controlled-rheology polypropylene resins (CRPP) have been produced industrially for years using reactive extrusion processes employing peroxides as free radical initiators. The molecular weight characteristics of CRPP materials can be tailor-made depending on the final application in a very efficient and economic manner.
A PP-based nitroxide (NOR) with the trade name Irgatec CR76 has been recently developed by CIBA Chemicals, as a source of radicals and it is currently being evaluated for the production of CRPP. NORs are well-known as powerful stabilizers to protect plastics from the negative influence of light and heat, and easy in handling during processing. Preliminary experimental results exhibit a qualitative difference between Irgatec CR76 and other commonly used peroxides.
The purpose of this research work is to evaluate this new material as a potential replacement of commonly used peroxides in the production of CRPP. CRPP will be produced by reactive processing using varying amounts of Irgatec CR76 and the rheological properties of the materials produced will be investigated. By comparing results with Irgatec CR76 to those from other typical initiators, the effectiveness of Irgatec CR76 as an initiator will also be assessed.
The results of this research will have an impact not only on the potential extension of uses of the specific PP-based NOR (Irgatec CR76), but also, more generally, on the wider application of additives during degradation of PP. Potentially new materials can be produced with enhanced heat and light protection along with the other benefits inherent to standard CRPP.
20
Wu, Xiang. "Quantitative infrared dichroism of isotactic polypropylene." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/9382.
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Shindo, Nobuhiko. "Structural analysis of thick polypropylene moldings." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/10251.
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Wang, Xiao Chuan. "Branching of polypropylene through reactive extrusion." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21396.pdf.
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Laihonen, Sari J. "Polypropylene : Morphology, defects and electrical breakdown." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-268.
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Ahmed, Syed Iqbal. "Coloration of polypropylene : prospects and challenges." Thesis, Heriot-Watt University, 2006. http://hdl.handle.net/10399/2023.
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Khan, Shahid Wahab. "Rheological properties of talc-filled polypropylene." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/7567.
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In this study polypropylene was modified by a range of talc (Mg3(OH)2Si4OlO) fillers. Three different types of surface modifiers were also used, two types of silanes (octyltriethoxysilane and y-aminopropyltriethoxysilane) and maleic anhydride modified polypropylene plus polyethylene wax as an external lubricant. A series of compounds were prepared in an APV twin screw compounder, based on talc addition level, morphology, particle size, surface coatings and coupling agents. The study showed that addition of talc to PP increases the shear viscosity and the blend system generally follows the power law in the shear rate range studied. The experimental values obtained with talc-filled PP were compared with theoretical data obtained from the Maron-Pierce type equation. It was found that theory predicts a higher value of relative viscosity for some talc fillers. A model equation is proposed for talc-filled PP that predicts accurately relative viscosity of the compound for different volume fractions of talc filler. PP-filled with talc having predominantly acicular particles (high surface area), shows a highest shear viscosity values, since high surface area fillers tend to increase the occluded polymer increasing the effective filler volume. The addition of a high level of coating decreasess hearv iscosity of the system,a ddition of a reactivec oupling systems lightly increasess hearv iscosity. Wall slip for unfilled PP was consistently evident. The slip velocity increases systematically with shear stress, but there is a critical value below which slip velocity was negligible. Addition of talc decreased the slip velocity at a given stress. A mechanism of slip has been proposed whereby a 'slip layer' on the die surface provides a sharp, low energy interface over which, at sufficiently high shear stress, the fluid PP can slip. A new empirical model has been proposed to predict the slip velocity of filled PP, as a function of talc volume fraction. PP filled with 10 % wt. talc having predominantly acicular particles, showed a higher slip velocity than PP filled with talc of other morphologies. It was observed that slip velocity increased by coating talc (either by use of coating or coupling agents) due to modification of velocity distributions in the flow channel. Extrudate swell increases with increasing shear rate for unfilled and talc-filled PP compounds. Inclusion of talc generally decreases the swell over the entire range of shearr ates studied,b ecauset he addition of talc to PP increasesth e shear/extensional modulus and thereby decreasede lastic strain recovery. No appreciablei nfluence of particle size on swell ratio was observed. Coating talc with octyltriethoxysilane produces higher swell relative to uncoated filled PP, and higher coating levels consistently produced higher swell values. However, coupling agent 7- aminopropyltriethoxsilane and maleic anhydride modified polypropylene both reduced the swell of the filled polymer system, with a more pronounced effect in extension than in shear. Swell decreased with an increase in capillary length-todiameter ratio and increased with increase in shear rate, (or shear stress) with or without coating/coupling agent. Addition of talc fillers delayed the onset of melt fracture and higher loadings of talc completely suppressed the melt fracture in the range of shear rate studied. Melt fracture for unfilled and filled PP has been studied and quantified by the frequency of the melt distortion. A mechanism for polymer melt fracture has been proposed to explain the results, based on the tensile failure of the material in extensional deformation. It was found that shear rate and die L/D ratio were the major causes of changesin severity of melt fracture for the unfilled and talc-filled compoundss tudied. However, talc morphology and particle size did not have significant effects on the severity of melt fracture.
26
Metin, Dildare Tıhmınlıoğlu Funda. "Interfacial enhancement of polypropylene-zeolite composites/." [s.l.]: [s.n.], 2002. http://library.iyte.edu.tr/tezler/master/kimyamuh/T000132.pdf.
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27
Jodoin, Jeffrey Joseph. "The production of polypropylene microcellular foam." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/14857.
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28
Gupta, Saloni. "Physico-chemical properties of polypropylene glycols." Thesis, University of Greenwich, 2015. http://gala.gre.ac.uk/21538/.
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Poly(propylene glycol) (PPG) samples of different molecular mass were characterized using differential scanning calorimetry, modulated differential scanning calorimetry, thermogravimetry and thermally stimulated current (TSC) spectroscopy. It was shown, by TSC, that the glass transition temperature and the degree of molecular mobility increased with increasing molecular mass of PPG. Additional experiments showed that PPGs of molecular mass 425, 1000 and 2000 Da undergo one global relaxation process; however, PPG 2700 (Da) undergoes an additional relaxation process after the glass transition which has been attributed either to the release of the excess charge delocalised in the polymer structure or a liquid-liquid transition. Thermally induced phase separation in aqueous solutions of PPG has been examined using a variety of techniques including high sensitivity scanning calorimetry (HSDSC), hot stage microscopy, small angle neutron scattering, and turbidity measurements. The data suggest that phase separation is a consequence of PPG aggregation (droplets); the aggregates grow in size, as the temperature is raised further. It is postulated that phase separation occurs via nucleation and growth, which is corroborated by model fitting the calorimetric data using a mass action aggregation model. It is concluded that phase separation of PPG occurs as a result of the disruption of a hydrogen bonded network between water and PPG. The effect of five sugars (mannitol, maltose, raffinose, sucrose and trehalose) on the Tm (transition temperature) of aqueous PPG 1000 solutions was studied by HSDSC and turbidity measurements. All the sugars decreased the phase separation temperature of the PPG solutions, with trehalose and maltose showing the greatest effect. A series of experiments, using HPLC, showed that phase separated PPG (1000 Da) increased the apparent aqueous solubility of naphthalene.
29
liu, lei. "Polypropylene block copolymer synthesis by metathesis." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1625523936334755.
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Thiraphattaraphun, Linda. "Structure/property relationships in polypropylene nanocomposites." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/structureproperty-relationships-in-polypropylene-nanocomposites(388eafc0-a98e-4a78-be0d-4d647a122d87).html.
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In this work, structure/property relationships in polypropylene (PP) nanocomposites have been investigated for different nanofillers. Nanofillers of modified clay based on montmorillonite (MMT) and multi-wall carbon nanotubes (MWNTs) have been selected and incorporated to the PP matrix as either single nanofillers or hybrid nanofillers. Melt mixing via a twin screw extruder and further moulding by injection moulding have been used to prepare PP nanocomposites. Moreover, the dilution of MWNT masterbatch has been used to prepare PP/MWNT and PP/clay/MWNT nanocomposites. Three types of the PP nanocomposites have been obtained: PP/clay, PP/MWNT and PP/clay/MWNT nanocomposites. In all three types of the PP nanocomposites, α- and -PP crystals were observed in the wide angle X-ray diffraction (WAXD) patterns. Furthermore, the addition of nanofillers to the PP did not appear to affect the PP orientation. Slight PP orientation in the PP nanocomposites was shown in the two-dimensional X-ray diffraction (2D-XRD) patterns. Mixed clay layers were combined in the PP/clay and PP/clay/MWNT nanocomposites and investigated by WAXD as well as transmission electron microscopy (TEM). In addition, the aggregated and individual MWNTs were present in both the PP/MWNT and PP/clay/MWNT nanocomposites TEM images. A rough fracture surface with cracks was revealed from the scanning electron microscopy (SEM) images of the three types of PP nanocomposites. Polarized optical microscopy (POM) micrographs were taken at different temperatures during cooling in a hot stage and revealed the limitation of PP spherulite growth upon adding the nanofillers to the PP. The incorporation of nanofillers was found not to affect the glass transition temperature (Tg) of PP which investigated by dynamic mechanical analysis (DMA). However, the increase of both the peak melting temperature (Tm) and the peak crystallization temperature (Tc) of PP with adding the nanofillers was shown by differential scanning calorimetry (DSC) thermograms. In addition, the nanofillers also have been shown to act as nucleating agents. The thermal stability of PP in a nitrogen atmosphere was enhanced by the nanofillers when examined by thermogravimatric analysis (TGA). DMA and tensile testing were performed and showed that the nanofillers act as reinforcement for the PP. The distribution, orientation and deformation of MWNTs in the PP/MWNT and PP/clay/MWNT nanocomposites have been followed by Raman spectroscopy. Significant shifts of the Raman G'-band from the MWNTs was obtained during deformation of the MWNT nanocomposites and the hybrid clay/MWNT nanocomposites as the stress transfer from the PP matrix to the MWNTs has occurred. A correlation between calculated modulus from deformation and measured modulus from DMA and tensile testing has been found for PP/MWNT and PP/clay/MWNT nanocomposites. Finally, the PP nanocomposites have been considered for use in packaging applications.
31
Derakhshandeh, Maziar. "Crystallization of polypropylene : experiments and modeling." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55605.
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In this study, the quiescent crystallization of several polypropylenes (PPs) with different molecular characteristics was first examined using Differential Scanning Calorimetry (DSC) and Polarized Optical Microscopy (POM). The Avrami/Nakamura equation was employed to fit and predict crystallization kinetics under isothermal and non-isothermal conditions. The Avrami/Nakamura model was found to predict the non-isothermal crystallization data of the various PPs very well over a range of cooling rates. POM was used in line with a rotational rheometer to further examine the behaviour under quiescent condition at different temperatures and/or cooling rates. The growth rate of crystals was impeded exponentially with increase of temperature. To study the effect of flow on crystallization behaviour of PPs, the Anton Paar MCR-502 rotational rheometer equipped with various fixtures including parallel-plate and POM to induce shear flow was used. Generally, an increase in strain and strain rate or decrease of temperature is found to decrease the thermodynamic barrier for crystal formation and thus enhancing crystallization kinetics at temperatures between the melting and crystallization points. Popular models based on suspension theory, which are often used to relate the degree of crystallinity to normalized rheological functions are validated experimentally. It is found that the constant(s) of various suspension models should be dependent on the flow parameters in order for the suspension models to describe the effect of shear on FIC, particularly at higher shear rates. Finally, a capillary rheometer was used to investigate flow-induced crystallization (FIC) of various resins at high shear rates relevant to polymer processing. It is found that the crystallization kinetics are enhanced with increasing molecular weight indicating the importance of high-end tail of MWD on FIC. Various dies with different physics were used to investigate the effect of flow on FIC. The Cogswell analysis was applied on the capillary data to obtain the apparent extensional strain rate and strain as well as the apparent extensional viscosity. FIC was found to depend strongly on the L/D ratio of the capillary die. Finally, temperature impacted the FIC behaviour extensively since it alters the activation energy needed for the formation of macroscopic structures.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
32
Zeng, Fuquan. "Investigation into the colouration of polypropylene." Thesis, University of Manchester, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557624.
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Polypropylene (PP) offers many advantages to the textile processor in terms of its durability and end use properties. However, a major technical flaw of PP is its inability to be dyed due to its relative lack of dye adsorption sites and high crystallinity. Therefore it is primarily mass pigmented, with pigment incorporated into the polymer melt prior to extrusion. While this approach offers a successful commercial route it does lack process flexibility. Some research has focused on modifying the polymer structure by incorporating dyeable copolymers or chemically degrading the base polymer by aqueous treatments to create polar groups for dye adsorption. However, both of these approaches have had little success due to processing difficulties, excessive deterioration of polymer properties and cost. In this study the primary thrust of the research has been to evaluate the use of dry gaseous fluorine treatments to modify the PP fibre and create dyeability and better colour fastness. XPS and FTIR indicate reaction between fluorine and the polypropylene fibre and the introduction of carboxyl groups and fluorine into the polymer. The introduction of these carboxyl groups and strongly electronegative negative fluorine leads to the fibre's enhanced basic dyeability. SEM analysis showed the impact of fluorine exposure on fibre surface morphology is relatively small. The effectiveness of pre-treatments on pigment dyeing and printing has also been evaluated. Colour fastness was significantly improved by a gaseous fluorine pretreatment of the textile substrate. The Helizarin Binder UDR pigment dyed system showed better performance in terms of colour fastness than other commercial binder systems evaluated. Optimisation of the binder to pigment ratio has been achieved in order to obtain good colour fastness. The dycability of moulded polyacetal zips was also examined in order to potentially replace the current mass pigmentation process. Fluorine pre-treatments showed no benefits in the overall colouration. properties in terms of long liquor dyeability or pigment dyeing. Of the disperse dyes evaluated the "high performance" SF and XF classes had the best colour fastness, in particular Dispersol Red CBN-SF, Dispersol Blue XF and Dispersol Flavine XF. A range of after-treatments were evaluated and a "reduction cleae, significantly improved the colour fastness. The polyacetal/polyester zip construction offered significant colouration difficulties due to the inherent problem of achieving a uniform, compatible, "soliX' dye shade. Although some success was achieved, commercial utilisation is less likely due to increasing process complexity.
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Manji, Aminmohamed. "Electro synthesis of propylene oxide in a bipolar trickle bed reactor." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25117.
Full textAbstract:
The synthesis of propylene oxide by electrolysis of dilute sodium bromide solution with propylene gas was investigated in an electrochemical
bipolar reactor consisting of six parallel fixed beds of graphite particles separated by polypropylene felt diaphragms.
One reactor was operated in single pass and recycle mode with two phase co-current flow of propylene and sodium bromide solution through the beds of graphite particles. The maximum pressure in the system was 2.22 atmospheres absolute.
The effects of superficial current density* (413 - 2687 A/m²), electrolyte (sodium bromide solution) concentration (0.2 M and 0.5 M), electrolyte flow rate (100 and 300 cm³ /min), propylene gas flow rate (100/1000/1500/2000 cm³/min at STP), reactor outlet temperature (30° and 60°C), bed thickness (six beds - 8.57/4.29/3.07 cm) and different carbon types (Union Carbide and Ultra Carbon) on the space time yield and selectivity for propylene oxide were measured. Depending on the condition for single pass runs, the space-time yield for propylene oxide was between 5.5 kg/hr m³ and 97.2 kg/hr m³, and the selectivity was between 54.5% and 87.3%. The current efficiency and the specific energy consumption varied from 14.0 to 58.2 percent and 5.7 to 59.9 Kwh/kg of propylene oxide. The space-time yield for propylene oxide increased with decreasing bed thickness. For the recycle mode the space-time yield decreases with time. The highest space time yield obtained after one hour of operation was 127.8 kg/hr m³ with a selectivity of 95.9%. The current efficiency for hydrogen, oxygen and dibromopropane was also determined.
*Superficial current density = applied current/electrode area.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
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Al-Shehri, Abdulhadi S. "Tensile and fracture behaviour of isotropic and die-drawn polypropylene-clay nanocomposites : compounding, processing, characterization and mechanical properties of isotropic and die-drawn polypropylene/clay/polypropylene maleic anhydride composites." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/5223.
Full textAbstract:
As a preliminary starting point for the present study, physical and mechanical properties of polypropylene nanocomposites (PPNCs) for samples received from Queen's University Belfast have been evaluated. Subsequently, polymer/clay nanocomposite material has been produced at Bradford. Mixing and processing routes have been explored, and mechanical properties for the different compounded samples have been studied. Clay intercalation structure has received particular attention to support the ultimate objective of optimising tensile and fracture behaviour of isotropic and die-drawn PPNCs. Solid-state molecular orientation has been introduced to PPNCs by the die-drawing process. Tensile stress-strain measurements with video-extensometry and tensile fracture of double edge-notched tensile specimens have been used to evaluate the Young's modulus at three different strain rates and the total work of fracture toughness at three different notch lengths. The polymer composite was analyzed by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, wide angle x-ray diffraction, and transmission electron microscopy. 3% and 5% clay systems at various compatibilizer (PPMA) loadings were prepared by three different mixing routes for the isotropic sheets, produced by compression moulding, and tensile bars, produced by injection moulding process. Die-drawn oriented tensile bars were drawn to draw ratio of 2, 3 and 4. The results from the Queen's University Belfast samples showed a decrement in tensile strength at yield. This might be explained by poor bonding, which refers to poor dispersion. Voids that can be supported by intercalated PP/clay phases might be responsible for improvement of elongation at break. The use of PPMA and an intensive mixing regime with a two-step master batch process overcame the compatibility issue and achieved around 40% and 50% increase in modulus for 3% and 5% clay systems respectively. This improvement of the two systems was reduced after drawing to around 15% and 25% compared with drawn PP. The work of fracture is increased either by adding nanoclay or by drawing to low draw ratio, or both. At moderate and high draw ratios, PPNCs may undergo either an increase in the size of microvoids at low clay loading or coalescence of microvoids at high clay loading, eventually leading to an earlier failure than with neat PP. The adoption of PPMA loading using an appropriate mixing route and clay loading can create a balance between the PPMA stiffness effect and the degree of bonding between clay particles and isotropic or oriented polymer molecules. Spherulites size, d-spacing of silicate layers, and nanoparticles distribution of intercalated microtactoids with possible semi-exfoliated particles have been suggested to optimize the final PPNCs property.
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Ecevit, Tuba Safiye. "Synthesis And Characterization Of Surface Sulfonated Polypropylene." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/3/12604846/index.pdf.
Full textAbstract:
ABSTRACT
SYNTHESIS AND CHARACTERIZATION OF SURFACE SULFONATED POLYPROPYLENE FILMS
Ecevit, Safiye Tuba
M.S., The Department of Polymer Science and Technology
Supervisor: Leyla Aras, Prof. Dr.
Co- Supervisor: Teoman Tinçer, Prof. Dr. March 2004, 44 pages The basic reseach on the surface sulfonation of the polypropylene is very important due to the surface design for higher functionalization. For this purpose, liquid-phase sulfonation of the polypropylene surfaces at various temperatures for different time periods were performed by concentrated sulphuric acid. The physical and chemical changes formed by the effect of the sulfonation on the polypropylene surfaces were determined by contact angle measurement, mechanical analysis, UV-Vis spectrometer, differential scanning calorimeter (DSC) and scanning electron microscopy (SEM). The surface polarity and wetting properties of the samples were evaluated by contact angle measurement. It is seen that, sulfonation at low temperatures and short time periods improve these two properties of the polypropylene surfaces. Sulfonation at high temperatures and long time periods however, cause the partial breakdown of the polymer by degradation. Noticeable color change due to the degradation and carbonization of the polypropylene films sulfonated at high temperature and long time were supported by the UV-Vis spectra of the samples. Mechanical properties of sulfonated PP films were investigated. Consequently, after the sulfonation process the mechanical properties of the PP films showed a general trend of decrease with sulfonation time for a given temperature and a very fast decrease at high temperature of sulfonation. Thermal characteristics were found by differential scanning calorimeter (DSC). Thermal analysis revealed that sulfonated PP film samples displayed an additional endothermic peak. The physical effects of the sulfonation were examined by scanning electron microscopy (SEM) which showed a hexagonal hole formations due to the bursting of the air bubbles within the PP films by the effect sulfonation. The lamelae formations were also seen around these holes.
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Yayla, Saniye. "Production And Characterization Of Polypropylene/organoclay Nanocomposites." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12608485/index.pdf.
Full textAbstract:
Polypropylene, PP, based nanocomposites were produced via melt blending method by using twin-screw extrusion in this study. The effects of organoclay type, compatibilizer type, and mixing order of components on the morphology, thermal, mechanical and flow properties of ternary nanocomposites were investigated. Terpolymer of ethylene/butyl acrylate/maleic anhydride, ethylene/methyl acrylate/glycidyl methacrylate, and copolymer of ethylene/glycidyl methacrylate elastomers were used as compatibilizer, whereas Cloisite®30B, Cloisite®
15A, and Cloisite®
25A were used as organoclay. iv In order to determine the optimum amount of compatibilizer, PP/compatibilizer blends were produced with different compositions. The content of compatibilizer was determined as 5 wt % based on the mechanical tests. Then, ternary nanocomposites were prepared with 5 wt % compatibilizer and 2 wt % organoclay contents. In addition, neat PP and PP/organoclay composites were prepared in order to make comparison. After that, the samples were characterized. According to the XRD analysis, the highest increase in the interlayer spacings of organoclays were observed in the PP/E-MA-GMA/Cloisite®
15A (23%) and PP/E-MA-GMA/ Cloisite®
25A (88.3%) ternary systems. SEM micrograms revealed that compatibilizer E-MA-GMA is the most compatible elastomer with PP. Thus, it was decided to investigate the effect of mixing order on the properties of these nanocomposites with E-MA-GMA. DSC analysis showed that the melting behavior of the nanocomposites does not change significantly with the presence of organoclay and compatibilizer. In addition, compatibilizers and organoclays have no significant nucleation activity in PP. The systems PP/E-MA-GMA/Cloisite®
15A and PP/E-MA-GMA/Cloisite®
25A have the highest improvements according to the results of mechanical tests. The results of mechanical tests showed that the mixing sequence (PEC), in which PP, organoclay and compatibilizer were compounded simultaneously in the first extrusion run, is the best sequence.
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Vange, Kjetil. "Validation of material model for polypropylene (PP)." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18517.
Full textAbstract:
Polymers are the up and coming engineering material. The number of possibleapplications is increasing fast and so is the need for a good polymer material model. Thescientists at SIMLab at NTNU have developed such a material model. In this thesis is thematerial model calibrated to represent an impact modified polypropylene used by Toyota.The validation started with the calibration. A review of the theoretical background of thematerial model and a detailed explanation of the calibration procedure are given todescribe the derivation of the calibrated material model. The model is then applied in FEsimulationsof the material tests and the two validation tests. The first validation test is aquasi-static tension test using a specimen with a centric hole. This test resembles thematerial tests but the centric hole makes the load response slightly more complex. Theother test is an impact test using a drop tower. This test validates the material modelsability to represent dynamic problems and also tests the representation of the strain ratedependency.The material model proves that it is capable of representing all the tests in this thesis quite accurately.
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Sælen, Kristin. "Validation of material model for polypropylene (PP)." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18793.
Full textAbstract:
A hyperelastic-viscoplastic material model intended for thermoplastics has been developed by SIMLab at NTNU. This model formed the basis of the thesis, where a material model for the polymer polypropylene was calibrated and validated. Four rounds of material testing were carried out. Tension and compression tests formed the basis for a calibration of the material model. Two different component tests were used for validation; stretching of a plate with a hole and plate impact tests.The calibrated model was implemented as a user-defined material model in the non-linear finite element code LS-DYNA, and numerical simulations of the tension and compression tests were carried out in order to verify the calibrated parameters. The component tests were numerically simulated with the purpose of controlling the ability of the model to predict the behaviour of the material when subjected to more complex loading cases.The calibrated material model was able to capture the main characteristics of the experimental tests. The model does, however, have limitations, as it was not able to correctly predict all strain rate effects of the material at high strain rates, like viscoelasticity. A partly recalibration of the material model was carried out to enable the model to predict the material’s behaviour at high strain rates.
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Amer, Ismael. "Molecular weight effects on crystallization of polypropylene." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6649.
Full textAbstract:
Thesis (PhD)--University of Stellenbosch, 2011.ENGLISH ABSTRACT: The crystallization of polyolefins is an important parameter in determining the properties of such materials. The crystallization phenomenon generally depends on the molecular symmetry (tacticity) and molecular weight of the material. In this study, a series of polypropylenes was prepared using heterogeneous MgCl2-supported Ziegler catalysts with two different external donors, diphenyldimethoxysilane (DPDMS) and methyl-phenyldimethoxysilane (MPDMS), and two different homogeneous metallocene catalysts, racethylene- bis(indenyl) zirconium dichloride, Et(Ind)2ZrCl2 (EI), and rac-ethylene-bis(4,5,6,7- tetrahydro-1-indenyl) zirconium dichloride, Et(H4Ind)2ZrCl2 (EI(4H)). Molecular hydrogen was used as terminating agent. In order to establish a correlation between the molecular weight and the crystallization of these polymers, fractionation of the materials according to crystallizability was performed by means of temperature rising elution fractionation (TREF). This affords the opportunity of blending materials of different molecular weights but similar symmetry. These materials were characterized using various analytical techniques: differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), 13C nuclear magnetic resonance spectroscopy (13C-NMR), high temperature gel permeation chromatography (HT-GPC) and Fourier-transform infrared spectroscopy (FT-IR). DSC was used to study the bulk crystallization of different polypropylene blends, most of which showed only one melting peak. The latter is usually associated with a high degree of cocrystallization. Turbidity analysis of the different polypropylene polymers, obtained using solution crystallization analysis by laser light scattering (SCALLS), provided good crystallization information – similar to that provided by crystallization analysis fractionation (CRYSTAF) and TREF. It was also possible to differentiate between polypropylenes with similar chemical structure but different tacticity and molecular weight. SCALLS results also showed that the blends of different isotactic polypropylene polymers were miscible and cocrystallization had occurred, whereas, the blends of syndiotactic polypropylene and different isotactic polypropylenes were not miscible and some interaction between phases had occurred. Optical microcopy (OM) and scanning electronic microscopy (SEM) were used to study the morphological properties of different isotactic polypropylenes. Results revealed a welldefined and large spherulitic morphology of mixed a1 (disordered) and a2 (ordered) crystal form structures. OM and SEM images also clearly showed an effect of molecular weight and tacticity on the crystal structure of the different polypropylene samples. Finally, various homopolymers and blends were studied to investigate the effect of molecular weight on the mechanical properties of these materials. This was done using microhardness testing and dynamic mechanical analysis.
AFRIKAANSE OPSOMMING: Die kristallisasie van poliolefiene is ‘n belangrike faktor wat die eienskappe van hierdie tipe materiale bepaal. In die algemeen hang kristallisasie af van die molekulêre simmetrie (taktisiteit) en molekulêre massa van die materiaal. ‘n Reeks polipropilene is berei deur gebruik te maak van heterogene MgCl2-ondersteunde Ziegler-kataliste met twee verskillende elektron donors, difenieldimetoksisilaan (DPDMS) en metielfenieldimetoksisilaan (MPDMS), en twee verskillende homogene metalloseenkataliste, rac-etileen-bis(indeniel) sirkoniumdichloried, Et(Ind)2ZrCl2 (EI), en rac-etileen-bis(4,5,6,7-tetrahidro-1-indeniel) sirkoniumdichloried, Et(H4Ind)2ZrCl2 (EI(4H)). Molekulêre waterstof is gebruik as termineringssagent. Ten einde ‘n verband te bepaal tussen die molekulêre massa en kristallisasie van hierdie polimere is hulle gefraksioneer op die basis van hulle kristallisseerbaarheid deur gebruik te maak van temperatuurstyging-elueringsfraksionering (TREF). Deur hierdie tegniek verkry ons materiale van verskillende molekulêre massa maar met dieselfde taktisiteit wat ons kan vermeng. Verskeie tegnieke is gebruik om hierdie materiale te karakteriseer: differensiële skandeerkalorometrie (DSC), wyehoek X-straal diffraksie (WAXS), 13C-kernmagnetiese resonansspektroskopie (13C-KMR), hoë-temperatuur gelpermeasiechromotagrafie (HT-GPC) en Fourier-transform-infrarooispektroskopie (FT-IR). DSC is gebruik om die vaste-toestand kristallisasie van verskeie vermengde polipropilene te bestudeer., en net een smeltpunt is in meeste gevalle waargeneem. Laasgenoemde word gewoonlik verbind met ‘n hoë mate van kokristallisasie. Oplossingkristallisasie analise, dmv laserligverstrooiing (SCALLS), is gebruik om die turbiditeit van die verskillende polipropileen kopolimeervermengings te bepaal. Goeie inligting aangaande die kristallisasie in oplossing – soortgelyk aan dié wat dmv die kristallisasie-analise-fraksioneringstegniek (CRYSTAF) en TREF bepaal is, is verkry. Dit was ook moontlik om te onderskei tussen polipropilene met soortgelyke chemiese strukture maar verskillende taktisiteit en molekulêre massas. SCALLS data het ook getoon dat die vermengings van verskeie isotaktiese polipropileen polimere versoenbaar was en dat kokristallisasie plaasgevind het, terwyl vermengings van sindiotaktiese polipropileen en verskeie isotaktiese polipropilene nie versoenbaar was nie en dat ‘n mate van fase-skeiding plaasgevind het. Optiese mikroskopie (OM) en skandeer-elektronmikroskopie (SEM) is gebruik om die morfologiese eienskappe van verskillende isotaktiese polipropilene te bepaal. Goed gedefineerde en groot sferulitiese morfologie van gemengde a1 (onordelike struktuur) en a2 (ordelike struktuur) kristal-strukture is waargeneem. OM en SEM beelde het ook gewys dat molekulêre massa en taktisiteit ‘n effek het op die kristalstruktuur van die verskillende polipropileenmonsters. Laastens is die meganiese eienskappe van ‘n verskeidenheid homopolimere en vermengde materiale bestudeer, deur gebruik te maak van mikro-hardheid metings en dinamiesmeganiese analise (DMA).
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Khoshkava, Vahid. "Polypropylene (PP) nanocomposites incorporating nanocrystalline cellulose (NCC)." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121442.
Full textAbstract:
The main objective of this dissertation is to evaluate the feasibility of preparation of well dispersed polypropylene (PP)/nanocrystalline cellulose (NCC) nanocomposites by melt processing. There has been growing interest in using NCC as reinforcement in polymer systems because of its interesting properties and the abundant and renewable sources of cellulose. Preparation of polymer nanocomposites incorporating NCC has been mainly carried out using solution or water-assisted mixing. Only few attempts have been made to prepare it using melt mixing. Polypropylene (PP) is a commodity polymer with wide application in the automotive, pharmaceutical and packaging industries. In the first phase of this project, physical properties (shape, size and surface energy) of NCC are evaluated. An equation was introduced to estimate the dispersion energy of NCC in polymer matrices based on room and high temperature surface energy data. The influence of NCC surface modification on its interaction with a polar polymer (polylactic acid (PLA)) and non-polar polymer (PP) was evaluated.In the second phase of this project, the relationship between NCC agglomerate structure and its dispersion in polymer matrices is considered. The effect of various drying techniques on NCC agglomerate structure is investigated. It was found that spray drying and freeze drying of NCC aqueous suspensions result in dense and compact NCC aggregates. On the other hand, spray freeze drying of NCC aqueous suspensions could form agglomerates with more open or porous structures. The structure of the agglomerates depends on the initial concentration of the NCC aqueous suspension before spray freeze drying. In the low concentration regime (below ca. 2 wt.%), a web-like structure of inter-connected nano-scale fibers is formed. On the other hand, micron sized spherical-foam structure particles are formed at higher concentration (ca. 2 wt.% and above). The specific surface area of NCC powder produced using spray freeze drying increased by more than 30 times.Polypropylene nanocomposites containing spray dried NCC, freeze dried NCC, and spray freeze dried NCC (NCCSFD) were prepared in an internal batch mixer. Polarized light microscopy (PLM) and scanning electron microscopy (SEM) showed better dispersion of NCCSFD particles. The results of dynamic mechanical analysis (DMA) and tensile tests showed a considerable improvement in modulus and tensile strength of samples containing NCCSFD particles. Rheological measurements, including linear and non-linear viscoelastic tests, were performed on PP/NCC samples. Small amplitude oscillatory (SAOS) tests showed a large impact of NCCSFD incorporation on rheological characteristics of PP samples. Steady shear results revealed strong shear thinning and a yield stress for PP samples containing NCCSFD particles. The magnitude of yield stress and the degree of shear thinning increased with NCCSFD concentration. The effects of NCC structure (web-like and spherical-foam structure) on rheological properties were examined.Le principal objectif de cette dissertation consiste à évaluer la faisabilité de la préparation de polypropylène bien dispersé (PP) / la cellulose nanocristalline du (NCC) nanocomposites par traitement par fusion. Il ya un intérêt croissant à utiliser du (NCC) comme renforcement dans les systèmes de polymère à cause de ses propriétés intéressantes et les sources de cellulose abondante et renouvelable. La préparation de nanocomposites polymères incorporant du NCC a été principalement effectuée en utilisant une solution ou un mélange d'eau-assistée. Seulement quelques essais ont été faites à préparer en utilisant un mélange à l'état de fondre. Le polypropylène (PP) est un polymère produit à de larges applications dans l'industrie de l'automobile, produits pharmaceutiques et les industries d'emballage.Dans la première phase de ce projet, les propriétés physiques (forme, taille et d'énergie de surface) du NCC sont évaluées. Une équation a été présentée pour estimer l'énergie de la dispersion du NCC dans les matrices à base de polymère dans une la pièce et les données d'énergie de surface à haute température. L'influence de la modification de surface du NCC et son interaction avec un polymère polaire (acide polylactique (PLA)) et un polymère non polaire (PP) a été évaluée.Dans la deuxième phase de ce projet, la relation entre la structure d'agglomérat du NCC et sa dispersion dans des matrices de polymère est considérée. L'effet des diverses techniques de séchage sur la structure des agglomérats du NCC est examiné. On a constaté que séchage par pulvérisation et par lyophilisation du NCC, les suspensions aqueuses se traduisent dans les agrégats du NCC denses et compactes. D'autre part, la pulvérisation par lyophilisation des suspensions aqueuses du NCC pourrait former des agglomérats ou des structures poreuses plus ouvertes. La structure des agglomérats dépend de la concentration initiale de la suspension aqueuse du NCC avant la pulvérisation par lyophilisation. Dans le régime à faible concentration (en dessous de2%environ en poids), une structure en forme de bande de fibres interconnectée à l'échelle nanométrique est formée. D'autre part, le micron dimensionné des particules de structure sphérique est formé à une concentration plus élevée (ca. 2 wt.% et au-dessus). La surface spécifique de la poudre du NCC produite en utilisant le séchage par atomisation ou lyophilisation a progressé de plus de 30 fois. Les nanocomposites contenant du polypropylène séché par pulvérisation du NCC, et lyophilisés à froid du NCC (NCCSFD) ont été préparé dans un malaxeur discontinu interne. La microscopie en lumière polarisée (PLM) et la microscopie électronique à balayage (SEM) ont montré une meilleure dispersion des particules de NCCSFD. Les résultats de l'analyse mécanique dynamique (DMA) des tests de traction ont démontré une amélioration considérable de modules de résistance à la traction des échantillons contenant des particules de NCCSFD. Des mesures rhéologiques, y compris les tests de viscoélasticité linéaire et non linéaire, ont été effectuées sur des prélèvements des PP/NCC. De petits tests oscillatoires d'amplitude (SAOS) ont montré un impact considérable d'incorporation de NCCSFD sur les caractéristiques rhéologiques des échantillons de PP. Des résultats réguliers de cisaille ont révélé une forte fluidification par cisaillement et une limite d'élasticité pour les échantillons de PP contenant des particules de NCCSFD. La magnitude de la limite de stress et le degré de rhéofluidification a augmenté avec la concentration de NCCSFD. Les effets de la structure du NCC (sous forme de bande et la structure en mousse sphérique) sur les propriétés rhéologiques ont été examinés.
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Francois, heude Alexandre. "Kinetic modeling of the polypropylene photothermal oxidation." Phd thesis, Ecole nationale supérieure d'arts et métiers - ENSAM, 2014. http://pastel.archives-ouvertes.fr/pastel-01069008.
Full textAbstract:
Developing numerical tools for polymer lifetime prediction constitutes a promising opportunity for shortening the duration of material certification procedures in the automotive industry without decreasing their reliability. This PhD thesis aims at modeling the photothermal oxidation of isotactic polypropylene (iPP), which is responsible for the alteration of both its mechanical and aspect properties. The adopted approach consists in coupling the kinetics of photo- and thermo-oxidation reactions with physical phenomena, such as oxygen transport and UV-light attenuation in the material thickness, in order to describe all the physico-chemical changes. Upper-scale properties, from which will be defined the end-of-life criteria, will be calculated afterwards by applying the suitable structure-property relationships. The main challenge was to extend the pre-existing kinetic model of thermal ageing to photothermal ageing by taking into account initiation reactions of photolysis. Heavy campaigns of ageing and characterization tests made on a reference iPP, as well as an exhaustive capitalization of literature data of other iPPs, have allowed elaborating a kinetic model of photothermal oxidation and to generalize it to the whole iPP family in large domains of oxygen partial pressure (from 0.2 to 50 bars), temperature (from 40 to 230°C) and UV-light exposure (variable intensities and light sources) describing both natural and accelerated ageing conditions. The experimental validation of the model has allowed substantiating the kinetic approach and showing its limitations, as well as highlighting some numerical issues. The model has been designed in order to be an upgradable numerical tool which will allow, at term, optimizing the representativeness of the ageing testing devices and the performance of commercial iPP formulations. All these theoretical and numerical developments are prone to be applied to the photothermal degradation of other types of polymer substrates, but also in other application fields of the macromolecular photochemistry such as UV-photopolymerization.Keywords: Polypropylene, photothermal oxidation, oxygen diffusion control, screen effect, kinetic modeling, lifetime prediction.
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Ohno, Sadatoshi. "Stress transfer in polypropylene fibre reinforced cement." Thesis, University of Surrey, 1990. http://epubs.surrey.ac.uk/849/.
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Badr, Atef Samir M. "Performance of advanced polypropylene fibre reinforced concrete." Thesis, University of Leeds, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437106.
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Lin, Yong. "Toughening mechanism of polypropylene/calcium carbonate nanocomposites /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CBME%202009%20LIN.
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Kobbe, Ryan Gregory. "Creep behavior of a wood-polypropylene composite." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Summer2005/r%5Fkobbe%5F062905.pdf.
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McConville, Eileen. "Investigation of the thermoforming of polypropylene packaging." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675461.
Full textAbstract:
Packaging is one of the major fields for plastic materials, with extruded polypropylene (PP) sheet widely used in the production of thin gauge tubs and containers for the food and beverage industry using the thermoforming process. In an increasingly competitive market understanding the fundamental material properties and the effect of thermoforming process settings can help a company deliver material and efficiency savings allowing them to reduce production, manufacturing and development costs. The main aim of this work was to advance the practical understanding of the processing of PP for packaging applications, by linking the fundamental material behaviour to the industrial thin gauge thermoforming process. During this work investigations were carried out into the basic properties of commercial grades of PP and the affect of blending on material and end container properties. The effect of extrusion and thermoforming process conditions on end container properties were also investigated along with large strain mechanical stretching using lab equipment capable of replicating the industrial process settings. Investigations into both the affect of extrusion settings and thermoforming settings have shown that the PP material grade selected can have a greater effect than changes in process settings; with changes in settings having a different degree of effect on the different PP material grades. Therefore it is important for a thermoformer not just to consider the material type but the material grade or percentage blend during product development. This work has also highlighted the fact that complex blends can be created everyday in the industrial thin gauge thermoforming process and these blends will greatly affect t,he behaviour of the material during processing, and the end container properties. Overall the work demonstrates how susceptible PP is to changes in blends and processing conditions and will be particularly relevant to the developing recycled materials area.
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Ebbens, Stephen James. "Chemical and electrical modification of polypropylene surfaces." Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4326/.
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Although many multi-component polymer systems are well characterised, the surface properties of polymers mixed with low surface energy additives have received little attention. In addition, the new branches of scanning probe microscopy that enable high resolution mapping and modification of surface charge distributions have been infrequently applied to polymer surfaces. The surface segregation of a fluorochemical additive directly from a polypropylene host matrix has been investigated by AFM and other surface analysis techniques. The level of surface enrichment was found to be governed by the temperature and duration of annealing. Further investigation revealed that the speed and extent of surface enrichment of the additive increases with polymer molecular weight. The effect of additive structure on surface segregation has also reported. A method of depositing charge onto polypropylene substrates from a high potential scanning AFM tip was developed. The relation between AFM tip- voltage and the level of charge deposited on the substrate suggested that a localised corona discharge was generated. AFM scanning parameters were found to effect the deposition of charge. The charging behavior of fluorochemical doped polypropylene surfaces was investigated on macroscopic scales using a scanning electrometer probe, and on microscopic scales using EFM. Fluorochemical domains at the surface have been found to preferentially accumulate both positive and negative charge. Surface charge distributions were found to become more uniform during annealing. Sub-micron particle capture by charged surfaces was investigated using EFM. In addition, spatially confined amine beads were deposited onto a patch of localised charge and subsequently functionalised to produce a metallic gold coating.
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Kwan, Isabella. "Cellulose and polypropylene filament for 3D printing." Thesis, KTH, Skolan för kemivetenskap (CHE), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-195829.
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Additive manufacturing has become a very popular and well mentioned technique in recent years. The technique, where 3 dimensional (3D) printing is included, creates opportunities to develop new designs and processing systems. As a research institute within the forest based processes and products, Innventia AB has an idea of combining 3D printing with cellulose. The addition of cellulose will increase the proportion of renewable raw material contributing to more sustainable products. However, when cellulose is added the composition of the filaments changes. The main aim for the project is to devise methodologies to improve properties of composite filaments used for 3D printing. Filament in 3D printing refers to a thread-like object made of different materials, such as PLA and ABS, that is used for printing processes. A literature study was combined with an extensive experimental study including extrusion, 3D printing and a new technique that was tested including 3D scanning for comparing the printed models with each other. The extruding material consisted of polypropylene and cellulose at different ratios, and filaments were produced for 3D printing. The important parameters for extruding the material in question was recorded. Because the commingled material (PPC) was in limited amount, UPM Formi granulates, consisting of the same substances, was used first in both the extrusion and printing process. Pure polypropylene filaments were also created in order to strengthen the fact that polypropylene is dimensional unstable and by the addition of cellulose, the dimensional instability will decrease. After producing filaments, simple 3D models were designed and printed using a 3D printing machine from Ultimaker. Before starting to print, the 3D model needed to be translated into layer-by-layer data with a software named Cura. Many parameters were vital during printing with pure polypropylene, UPM and PPC. These parameters were varied during the attempts and marked down for later studies. With the new technique, in which 3D scanning was included, the 3D printed models were compared with the original model in Cura in order to overlook the deformation and shape difference. The 3D scanner used was from Matter and Form. Photographs of the printed models, results from the 3D scanner, and screenshots on the model in Cura were meshed together, in different angles, using a free application named PicsArt. The result and conclusion obtained from all three parts of the experimental study was that polypropylene’s dimensional stability was improved after the addition of cellulose, and the 3D printed models’ deformation greatly decreased. However, the brittleness increased with the increased ratio of cellulose in the filaments and 3D models.Additiv tillverkning har på den senare tiden blivit en mycket populär och omtalad teknik. Tekniken, där tredimensionell (3D) utskrivning ingår, ger möjligheter att skapa ny design och framställningstekniker. Som ett forskningsinstitut inom massa- och pappersindustrin har Innventia AB en ny idé om att kombinera 3D-utskrivning med cellulosa. Detta för att höja andelen förnybar råvara som leder till mer hållbara produkter. Dock kommer filamentens sammansättning vid tillsättning av cellulosa att ändras. Det främsta syftet med detta projekt är att hitta metoder för att förbättra egenskaperna hos de kompositfilament som används för 3D-utskrifter. Filament inom 3D-utskrivning är det trådlika objektet gjort av olika material, såsom PLA och ABS, som används vid utskrivningsprocessen. En enkel litteraturstudie kombinerades med en experimentell studie. Det experimentella arbetet var i fokus i detta projekt som omfattade extrudering, 3D-utskrivning samt en ny teknik som prövades, där 3D-scanning ingick, för att jämföra de utskrivna modellerna med varandra. Extruderingsmaterialet bestod av polypropen och cellulosa av olika halter, och av detta material tillverkades filament för 3D-utskrivning. De viktiga parametrarna för extrudering med det önskade materialet antecknades. Eftersom mängden cominglat material (PPC) var begränsat, användes först UPM Formi granuler, som består av samma substanser som i PPC, i både extruderingen och utskrivningen. Filament av ren polypropen tillverkades också för att stärka det faktum att polypropen är dimensionellt instabil. Genom att tillsätta cellulosa minskades dimensionsinstabiliteten. Efter att filamenten hade tillverkats, designades enkla 3D-modeller för utskrivning med en 3D-utskrivare från Ultimaker. Innan utskrivningen kunde börja behövde 3D-modellen bli översatt till lager-på-lager-data med hjälp av en programvara vid namn Cura. Många parametrar är viktiga vid utskrivning med ren polypropen, UPM samt PPC. Temperatur och hastighet varierades för de olika försöken och antecknades för senare studier.Med den nya tekniken, där 3D-scanning ingår, jämfördes de utskrivna 3D-modellerna med originalmodellen i Cura för att se över deformationen och formskillnaden. Den 3D-scanner som användes kom från Matter and Form. Fotografier på de utskrivna modellerna, resultaten från 3D-scannern och bilder på modellerna i Cura sammanfogades i olika vinklar med hjälp av ett gratisprogram som heter PicsArt. Det resultat som erhölls och den slutsats som kunde dras utifrån alla tre delarna av den experimentella studien var att polypropens dimensionsinstabilitet minskades efter tillsatsen av cellulosa, och att de 3D-utskrivna modellernas deformation minskade kraftigt. Skörheten ökade ju högre halt cellulosa som filamenten och de utskrivna modellerna innehöll.
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Wilks, C. E. "Processing techologies for woven glass/polypropylene composites." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520625.
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ACHIMSKY, LAURENCE. "Etude cinetique de la thermooxydation du polypropylene." Paris 6, 1996. http://www.theses.fr/1996PA066004.
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L'oxydation thermique (dans l'air) d'un polypropylene isotactique non stabilise a ete etudiee dans l'intervalle de temperature 50-150c par differentes methodes de mesure telles que la spectrophotometrie ir, la gravimetrie, les titrages iodometriques les principales caracteristiques de la cinetique d'oxydation du pp dans le domaine de temperature etudie sont resumees comme suit: les courbes cinetiques presentent un etat stationnaire precede d'une periode d'induction. La vitesse de l'etat stationnaire est independante de la constante de vitesse d'amorcage. La duree de la periode d'induction est independante de l'origine de l'echantillon (dans le cas ou l'echantillon est raisonnablement propre et non oxyde). L'energie d'activation apparente et le coefficient preexponentiel de la periode d'induction sont proches de ceux de la demi-vie des hydroperoxydes determines par des experiences de thermolyse en atmosphere neutre. Les periodes d'induction de la formation des carbonyles et du gain de masse sont en rapport de 3/2. Toutes ces caracteristiques sont predites par un modele cinetique fonde sur un schema en boucle fermee dans lequel l'amorcage est provoque par la decomposition unimoleculaire des hydroperoxydes dans l'intervalle de temperature 80-150c. Les graphes d'arrhenius des periodes d'induction montre cependant une rupture de pente a 80c avec une diminution de l'energie d'activation apparente. Ce changement pourrait etre du au fait que l'amorcage par voie bimoleculaire devient competitif a basse temperature ; cependant certains aspects ne sont pas encore expliques. Les mesures de chromatographie d'exclusion sterique revelent l'existence predominante de coupures de chaine coexistant avec un phenomene de reticulation qui pourrait etre attribue aux radicaux p#. . La polymolecularite diminue, ce qui indique une oxydation probablement homogene a petite echelle