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LINDSTRAND, NILS, and KARL THUNELL. "From Plastic to Paper Mapping the real cost of plastics." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-224931.
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Owsiany, Dana Lynn 1969. "Sand stabilization using waste plastics." Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/291370.
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A study on the possible use of melted waste thermoplastics to stabilize soils, and produce plastic-soil structural composites is presented. Specifically, the effects of melted thermoplastics on the shear strength, and creep characteristics of sands are examined. An extensive experimental program was conducted to examine the strength and creep characteristics of different plastic-sand compositions. It was found that increasing plastic content in the sand results in stronger, and stiffer soils with negligible creep deformations for loads which are at least 50% of the strength of the composite. It is expected that injection of melted waste thermoplastics in sands can improve significantly the engineering characteristics of foundation, and slope stability of sands. Other potential applications include construction of structural elements, bricks, etc.
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Rodriguez, Veloz Oscar Alberto. "The development of laminar morphology in a co-rotating twin screw extruder." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0026/MQ50656.pdf.
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Ramírez, Domínguez Edgar C. "Optical sensing of thermoplastics solidification in an injection moulding machine." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0024/MQ50654.pdf.
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Hernández, Aguilar José Ramón. "Computational and experimental evaluation of two models for the simulation of thermoplastics injection molding." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ64224.pdf.
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Manero, Federico. "Cavity temperature measurement and control in thermoplastics injection moulding." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27241.
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Injection moulding is one of the most important manufacturing processes in the plastic industry. The temperature distribution of the polymer, while it is inside the mould cavity, influences the properties of the product. The measurement and control of these temperature profiles can enhance the economy of the process and the part quality.A method to measure melt temperature inside the mould cavity was developed. It consists of an insert, located in the movable plate, that can place thermocouples at different positions. The depth of the thermocouple tip is adjusted manually. These sensors offer an attractive way to perform the measurements because of their easy calibration procedure. The temperature measurements were influenced by the thermocouple tip geometry.
Data were collected at different locations and depths of the mould cavity and the temperature profiles were analyzed. The temperature distribution depended on the wall temperature and the temperature of the polymer as it enters the cavity. The effect of different flow rates was also studied and it demonstrated to affect the temperature profiles.
A control algorithm was developed to control the average of the peak temperatures at three locations in the cavity. The manipulated variable was the coolant temperature and the process disturbance was the front barrel temperature. The transfer functions of the controlled variable with respect to the manipulated and disturbance variables were identified and modeled.
Finally two controllers were designed, tuned, simulated and implemented on the machine. The first is a static feedforward - feedback controller, and the second is a dynamic feedforward - feedback controller. The feedback loop was designed using an internal model control (IMC) algorithm. The static feedforward - feedback controller was found to have a better performance.
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Capt, Ludovic. "Simultaneous biaxial stretching of isotactic polypropylene films in the partly molten state." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82839.
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This thesis presents a detailed study of the simultaneous biaxial stretching of isotactic polypropylene (iPP) films in the partly molten state. Four commercial grades of isotactic PP (PP1--PP4) were investigated. The first three resins differed principally in isotacticity levels, which were 94.8%, 98.6%, and 99.5%, and the fourth resin had molecular weight and isotacticity levels similar to those of PP2, but differed in crystallization behavior. The four iPP resins were extruded and cast under similar conditions. The severity of the cooling was varied for PP4. The cast films were stretched on the laboratory film stretcher, that simulates closely the stretching conditions encountered in the industrial tenter-frame stretching process. The morphology of the cast films and the final stretched films was characterized by differential scanning calorimetry and wide-angle X-ray diffraction. The reflection technique was used for the X-ray measurements. Finally, the mechanical and optical properties of the films were determined, and the results were correlated with the film morphology and orientation. The effects of drawing temperature, stretching ratio, strain rate, initial morphology, and chain tacticity on deformation behavior, stretched film morphology, and end-film properties were studied, and correlations were sought.Simultaneous equibiaxial stretching was found to be homogeneous for sufficiently high deformation rates ( 3&d2;H > 0.1 s-1). The stiffness and the thermal stability of the crystallites played an important role in deformation behavior. In fact, the biaxial yield stress showed linear dependence on the crystallite size. Upon simultaneous equibiaxial deformation, crystallinity and especially orientation increased, while crystallite size decreased. The isotacticity content was found to influence greatly the thermal stability of the initial morphology. Increasing isotacticity leads to an increase in DSC melting peak temperature of the initial morphology, overall stress of deformation, and in the final crystallinity, orientation, elastic modulus, and tensile strength of the end film. Finally, it was concluded that the crystalline phase, that melts during preheating prior to stretching forms a "structured melt" phase. The amount of structured melt is related to the tensile strength at break of the end film. Finally, it was showed that an optimal gloss is obtained, if the cast film is stretched about 15°C below its melting point.
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Samurkas, Tony. "Nonlinear viscoelastic behaviour of linear polyethylene : molecular weight effects and constitutive equation evaluations." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41766.
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The nonlinear viscoelastic properties of a series of blends of linear polyethylene were studied using the McGill sliding plate rheometer. A more reliable and sensitive shear stress transducer for this rheometer was designed, built and used in this work. The molecular weight dependence of a variety of nonlinear viscoelastic properties was investigated. It was determined that, as with steady state properties, the sensitivity of such properties to molecular weight diminishes with increasing shear rate. The behavior of these materials in large amplitude oscillatory shear (LAOS) was also studied. By using harmonic analysis, the frequency content of the nonlinear stress response to the sinusoidal strain was studied as a function of molecular weight, strain amplitude and frequency. The predictive abilities of the Wagner model in LAOS, exponential shear, start-up and cessation of steady shear and interrupted shear, at high shear rates were evaluated. Qualitative trends were well predicted by the model for a variety of sigmoidal and exponential damping function forms. For the first time, it has been shown that Wagner model predictions for molten thermoplastics are insensitive to the damping function form. The damping functions in simple shear and planar extension were obtained for a branched low density polyethylene (LDPE). Simple shear is similar to planar extension in a rotated reference frame and thus the two flows should have similar damping functions. It was found that the damping functions that fitted these two flows are, in fact, quite different. Thus we have shown that the contribution of kinematics cannot be simply described.
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Barreto, Marie de Chantal. "Crystallisation kinetics of high density polyethylene pre-sheared in the melt." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61763.
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Singh, Peter. "Molding behaviour and microstructure of injection molded short glass fiber reinforced polypropylene composites." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74240.
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Injection molded Short Glass Fiber Reinforced Thermoplastics (SFRTP) are widely used in industry because of advantages in material properties, availability, economics and ease of processing. The thermo-mechanical history experienced by the material during processing produces significantly anisotropic microstructural and consequently mechanical properties, varying not only spatially, but directionally.This work attempts to examine quantitatively various aspects of microstructure and the effect of processing conditions in SFRTP. The matrix phase properties, such as crystallinity, morphology and molecular orientation distribution, as well as the fiber phase microstructure such as concentration, length and orientation distributions have been analyzed quantitatively, and explained. Experimental techniques, including optical and electron microscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, thermo-gravimetric analysis, etc. have been used. The results indicate complex changes in microstructure from skin to core in the injection molded samples. Both matrix and fiber phase microstructures are affected by the basic thermal and flow processes that occur during the injection molding process. A first order model has been developed to predict fiber orientation distributions, which agree well with the experimental results.
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Okada, Yoshio 1928. "The thermal expansion coefficient of polypropylene and related composites /." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56778.
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The variability of thermal expansion coefficients during the molding of plastics causes the development of frozen thermal stresses in the molded parts. Also, the distribution of thermal expansion coefficients of the material in the molded part plays an important role in controlling shrinkage and warpage. In turn, the distribution of linear thermal expansion coefficients (LTECs) depends on the distributions of crystallinity and orientation in the part. In the case of fibre reinforced polymers, the distributions of fibre concentration and orientation are also important.In this project, a model has been proposed for estimating the LTEC of fibre reinforced plastics as a function of crystallinity, matrix orientation, and fibre concentration and orientation. Also, extensive data have been obtained regarding the LTEC of polypropylene with and without fibre reinforcement. Extruded pellets and injection molded parts were considered. Model predictions have been compared with experimental data.
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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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Rafizadeh, Mehdi. "Physically-based dynamic model for the control of cavity pressure in thermoplastics injection molding." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34433.
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The injection molding process, due to its versatility, cost effectiveness, and ability to produce precise complex articles is widely used in plastics processing. Mold cavity pressure is a good indicator of the processes taking place in the cavity and plays an important role in determining the quality of the molded articles. The dynamic modeling and control of cavity pressure, based on a physically-based approach, is studied in this research project. The work deals with the filling and packing phases.A lumped physically-based model was developed in order to study the behavior of the system. The model is derived from conservation laws and incorporates a physical understanding of the process. The whole system was divided into subsystems including the hydraulic system, ram-screw, barrel, and polymer delivery system. It was found necessary to account for polymer melt elasticity as well as non-Newtonian behavior of the polymer melt flow. Consideration of the growing solid skin in the polymer delivery system was found to be necessary.
The dynamics of the cavity pressure during the filling phase were investigated and found to be non-linear and time-varying in relation to the hydraulic servo-valve opening which is the manipulated variable. The dynamic behavior of the cavity pressure is approximated by piece-wise linearization of the non-linear governing equations to derive a transfer function using the physically-based model which is of fifth order. Adaptive PI, PID, and IMC controllers were designed and tested for the control of the cavity pressure. Various tuning techniques, along with changes in set-point, were used to determine conservative settings for the PI and PID controllers.
A similar approach was used to study the dynamics of the cavity pressure during the packing phase. A sixth order transfer function, with piece-wise linearization, was derived to approximate the non-linear and time-varying behavior of the cavity pressure during packing. The adaptive PI, PID, and IMC controllers were successfully applied into the packing phase. The transition of the filling-to-packing was selected to be detected by the derivative of the cavity pressure and adaptive controllers were successfully used for this phase.
Two commonly used injection molding grade thermoplastics, polyethylene and polystyrene, were used in experimental part of this work for model validation and controller testing.
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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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Nelson, Burke I. (Burke Irving). "Control of a polypropylene visbreaking process using an in-line process rheometer." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28499.
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An in-line process rheometer, employing a proven shear-stress transducer, was designed and built for polymer melts. The entire process stream runs through the rheometer, giving it a much faster response time than conventional side-stream models. The possibility of using the in-line rheometer for dynamic mechanical analysis was investigated and methods were developed to obtain the complex modulus over a wide range of frequencies with a single measurement. Measurement techniques for shear viscosity testing were also developed along with algorithms to compensate for the effects of process pressure and temperature.The rheometer was used as a viscosity sensor to provide feedback control for a polypropylene visbreaking process. A first order plus dead time model was used to model the process and the rheometer together, and typically had dead times of less than 60 s and a first order time constant of 15 s. Gain scheduling was incorporated into minimum variance and proportional-integral controllers to achieve closed-loop settling times of 200 s for viscosity setpoint changes and process disturbances.
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Heuzey, Marie-Claude. "Barriers to progress in the simulation of viscoelastic flows of molten plastics." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35547.
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Polymer melts exhibit some degree of viscoelasticity in most industrial forming operations, and elasticity is particularly important in flows involving an abrupt contraction or expansion in the flow direction. However, the incorporation of a viscoelastic constitutive equation into computer models for polymer processing poses many problems, and for this reason inelastic models have been used almost exclusively to represent rheological behavior for flow simulation in the plastics industry.In order to explore the limits of viscoelastic flow simulations, we used two nonlinear viscoelastic models (Leonov and Phan-Thien/Tanner) to simulate axisymmetric and planar contraction flows and extrudate swell. Their predictions were compared with those obtained using a strictly viscous model (Carreau-Yasuda) and with experimental results. The models are implemented in a modified Elastic Viscous Split Stress (EVSS) mixed finite element formulation. The viscoelastic constitutive equations are calculated using the Lesaint-Raviart method, and the divergence-free Stokes problem is solved applying Uzawa's algorithm. The decoupled iterative scheme is used as a preconditioner for the Generalized Minimal Residual (GMRES) method. Numerical instability was observed starting at quite low elasticity levels. For the converging flows, the predicted flow patterns were in fair agreement with experimental results, but there was a large discrepancy in the entrance pressure drop. In the case of extrudate swell, the agreement with observation was poor, and convergence was impossible except at the lowest flow rate.
After exploring the limits of simulations using viscoelastic models, we conclude that there are serious barriers to progress in the simulation of viscoelastic flows of industrial importance. The ultimate source of the problem is the melt elasticity, and traditional numerical methods and rheological models do not provide a suitable basis for simulating practical flows. A new approach is required, and we propose that a rule-based expert system be used.
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Heuzey, Marie-Claude. "The occurrence of flow marks during injection molding of linear polyethylene." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23745.
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Injection molding is a high rate production process for manufacturing plastic parts. There is often a conflict between good appearance and short cycle time. Injection molded parts can show several types of surface defect. It is believed that wall slip may be associated with some types of defect, because wall slip can modify the distributions of velocity, wall shear stress, pressure and heat flux. The work described here involves an experimental study of the occurrence of flow marks during injection molding of linear polyethylene, and the possible relationship between these defects and wall slip. It also involves the investigation of the feasibility of incorporating wall slip models in the 2.5D computer simulation of the injection molding process.
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Ferguson, Sean Michael. "Plastics Without Petroleum History and Politics of 'Green' Plastics in the United States." Thesis, Rensselaer Polytechnic Institute, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3557924.
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Among the new technologies heralded as part of the emerging bioeconomy are plastics made from plant material, known as bioplastics. This dissertation examines the political and historical underpinnings of the bioplastics that are now being offered as an alternative to petrochemicals in the United States. As a case study of "green" technological development, bioplastics challenge dominant conceptions of innovation for sustainability. The bioplastics being developed and marketed today are the outcome of interventions in commodity crop prices, incubation of research on biomass during periods of fossil fuel dominance, and the commercialization of publicly funded research. Their origins can be traced at least as far back as the 1920s, when advocates of "chemurgy" encouraged the federal government to create research centers to discover new industrial uses of agricultural crops.
Research in science and technology studies (STS) indicates that social structures shape perceptions of problems, condition viable solutions, and limit the diversity of stakeholders and ideas present in the social construction of technology. This study examines these processes in the history and current debates about bioplastics. The dissertation asks who has influenced the social construction of bioplastics and why bioplastics have become part of a larger bioeconomic vision now. Theoretical insights are drawn from the sociological theory of the treadmill of production, which argues that environmental problems cannot be solved in a capitalist system in which the federal government, private industries, and organized labor continuously seek the expansion of production and consumption at the expense of environmental sustainability. Major players in the chemical and biotechnology industries have pursued bioplastics as a means of continuing economic growth and consumption of goods, even as petroleum becomes costly and environmentalists voice objections to petrochemicals. There are many critiques of bioplastics and their impacts at every stage of bioplastics, from sourcing feedstocks from food crops to disrupting existing recycling and composting systems. Nevertheless, the bioplastics currently on the market were not designed to resolve these environmental concerns. Increasingly, however, activists are using non-governmental institutions, particularly the development of voluntary standards, to shape the industry and technology. The study examines the extent to which such reforms might lead to the production of more sustainable alternatives to petrochemicals.
Ultimately, this dissertation presents the history and politics surrounding the field of bioplastics in order to highlight how things "might have been otherwise" and what changes in society could be useful for producing more sustainable technologies.
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Buys, Alexander George. "Performance evaluation of aluminium alloy 7075 for use in tool design for the plastic industry." Thesis, Cape Peninsula University of Technology, 2009. http://hdl.handle.net/20.500.11838/1246.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2009.The objective of this project was to measure the performance of high-strength aluminium alloys as injection mould material compared against conventionally used tool steel.
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Li, Tao. "New compatibilizing agents for blends of linear low-density polyethylene and polystyrene as model systems of the post-consumer plastic waste stream." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1061478646.
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Lee, Oi Wun. "Experimental study of post-shear crystallization of polypropylene melts." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0004/MQ44020.pdf.
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Wood-Adams, Paula. "The effect of long chain branching on the rheological behavior of polyethylenes synthesized using constrained geometry and metallocene catalysts." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0027/NQ50282.pdf.
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Capt, Ludovic. "The pressure-volume-temperature behavior and the effect of pressure on crystallization kinetics of polyethylene resins." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0026/MQ50594.pdf.
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Alam, Kevin. "Surface and interfacial tension measurements of polymer melts with pendant drop apparatus, effect of structural and material properties on the surface tension of LLDPE : an improved experimental method." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0020/MQ55015.pdf.
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Aasrum, Pål Einar. "A numerical and experimental investigation of glass fibre reinforced epoxy pipes /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0016/MQ55014.pdf.
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Uribe, Calderón Jorge Alonso. "Clay modification for the production of polystyrene nanocomposites by melt processing." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18809.
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Natural Montmorillonite was modified with thermally stable phosphonium surfactants to produce new organoclays for the production of polymer nanocomposites. The organoclays were characterized to determine thermal stability, basal spacing, and the surface energy at room temperature and at the processing temperature. Polystyrene (PS)/organoclay nanocomposites were prepared by melt compounding, using three different PS resins. Experimental data were obtained to elucidate the influences of temperature and molecular weight and structure of the surfactant on the surface energy of the organoclays. The phosphonium-based organoclays exhibited better thermal stability than commercially available ammonium-based organoclays. The basal spacing was similar to that found in commercially available organoclays. Transmission electron microscopy (TEM) showed that the degree of dispersion of the various organoclays in nanocomposites was related to the Hamaker constant of the organoclay at the processing temperature. Significant improvement in the degree of dispersion was realized, when blends of polystyrene with a styrene- maleic anhydride (SMA) copolymer were used. It appeared that delamination in the SMA systems was achieved directly without undergoing an intermediate intercalated structure. The influence of organoclay concentration on flexural modulus of PS- organoclay nanocomposites was determined, using the Halpin-Tsai and Hui-Shai models. The predictions were in good agreement with experimental results. The modulus of PS nanocomposites correlated well with the work adhesion at room temperature, in agreement with the equation of Shang. Barrier properties showed reasonable agreement with the predictions of models reported in literature. However, the values of aspect ratios predicted by the models were quite different from those observed experimentally. The permeability of nanocomposites to oxygen correlated with both the Hamaker constant A131 at the processing temperatureDe la montmorillonite naturelle a été modifiée avec des surfactants de phosphonium qui sont thermiquement stables pour objectif de produire de nouvelles organoargiles pour la production de nanocomposites polymériques. Les organoargiles ont été caractérisées pour déterminer la stabilité thermique, l'espacement basal et l'énergie superficielle à température ambiante et à la température de préparation. Des nanocomposites de polystyrène (PS) et organoargile ont été préparés en fondant le PS, avec trois différentes résines de PS. On a évalué l'influence de la température, de la masse molaire et de la structure des surfactants sur l'énergie superficielle des organoargiles. Les organoargiles préparées avec des surfactants de phosphonium ont démontré une meilleure stabilité thermique que les organoargiles commerciales préparées avec des surfactants d'ammonium. L'espacement basal a été similaire à celui des organoargiles commerciales. La microscopie électronique en transmission a démontré que le degré de dispersion des organoargiles dans les nanocomposites est en relation avec la constante de Hamaker de l'organoargile à la température de préparation. Le degré de dispersion de l'argile a été amélioré quand un mélange de polystyrène avec un copolymère de styrène et d'anhydride maléique (SAM) a été employé. Apparemment, la delamination dans les systèmes de SAM a été réussie directement sans avoir une structure intercalée intermédiaire. On a déterminé l'influence de la concentration d'argile sur les propriétés mécaniques des nanocomposites de PS en utilisant les modèles de Halpin-Tsai et Hui-Shai. Les prédictions ont été en accord avec les résultats expérimentaux. Les modules des nanocomposites de PS sont bien corrélés avec le travail d'adhésion à la température ambiante, selon l'équation de Shang. Les propriétés de barrière ont été mesurées et sont en accord avec les prédictions des$
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Reimers, Michael Jan. "Sliding plate rheometer studies of concentrated polystyrene solutions." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40431.
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A number of concentrated high molecular weight narrow distribution polystyrene solutions were investigated using a sliding plate rheometer. An in-depth study of the wall slip of these solutions had to be conducted to determine the range of conditions where this phenomenon occurred. It was found that the critical stress for the onset of slip depends on the surface of the substrate. Step strain experiments allowed the determination of the ratio of the second to the first normal stress difference, which was found to have values of up to $-$2. Gradients in the normal stress differences are believed to be the cause of an observed secondary flow. Large amplitude oscillatory shear experiments were carried out over a wide range of frequency and strain rate amplitude making it possible to construct response surfaces. All three solutions revealed a linear plateau that extended to higher strain rate amplitudes as the frequency increased. It was also found that the loss modulus has a maximum at the onset of nonlinear behavior. The higher harmonics describe the solutions' nonlinearity, and it was found that their qualitative behavior mirrors that of the first harmonic. The effect of molecular weight was assessed for the tricresylphosphate solutions. It was found that the principal harmonic exhibits the expected behavior; as the molecular weight increases, the elasticity of the solution increases. The higher harmonics followed no clear trend.The Doi-Edwards theory and Wagner model were compared to experimental data for all solutions, and both models fell short in quantitative predictions, the Doi-Edwards theory being worse due to its relaxation spectrum. Optical measurements on the tricresylphosphate solutions allowed the determination of the third normal stress difference in LAOS. It was found that the magnitude was independent of molecular weight. However, the "higher" harmonics were found to be dependent on molecular weight. As molecular weight increases, they extend to higher frequencies.
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Demarquette, Nicole Raymonde. "Interfacial tension in polymer blends : measurements and analysis." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41574.
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Interfacial tension is one of the most important parameters that influence the morphology of polymer blends. However, few data are available regarding interfacial tension between polymers due to experimental difficulties.Two devices, one based on the pendant drop method and another based on the spinning drop method, were constructed in this work to conduct an experimental study of interfacial tension between polymers. With both instruments, it was possible to view the drop in real time and to calculate the interfacial tension on-line. The following aspects were considered: special syringe design, the necking and capillary effects, in the pendant drop method, and sealing of the rotating tubes and density measurement in the spinning drop method. The two devices were shown to be reliable and complementary. A method to infer interfacial tension from transient measurements was suggested.
Interfacial tension was measured for different polymer pairs. The effects of temperature, molecular weight, bimodal blending and molecular weight distribution were evaluated. The effect of adding compatibilizers was also studied. Surface analysis of the interfaces was performed using E.S.CA. to explain the experimental results.
The experimental results were compared with the predictions of lattice theories and the square gradient theory. A strategy to evaluate the Flory-Huggins interaction parameter between polymers was developed. When this strategy was employed, theoretical predictions and experimental data showed good agreement for the influence of temperature and molecular weight on interfacial tension. However, the theory could not predict the effect of polydispersity on interfacial tension.
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Hatzikiriakos, Savvas Georgios. "Wall slip of linear polyethylenes and its role in melt fracture." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70285.
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Experiments were performed in a sliding plate rheometer and in capillaries and slits with several polymer melts, particularly polyethylenes, to determine the conditions for the onset of slip and melt fracture. In the sliding plate rheometer various shear tests were used to determine the relationship between the slip velocity and wall shear stress, and based on the experimental observations both steady state and dynamic slip models are proposed that are consistent with experimental observations. In the capillary flow studies the dependence of the slip velocity on wall shear stress, pressure, temperature and molecular parameters of molten polyethylenes was studied and the results were used to formulate a general slip velocity model. Because the slip velocity depends on pressure and thus varies with position in capillary flow, the Mooney procedure in determining the slip velocity is not appropriate. A modified Mooney technique is proposed to analyse the capillary data in cases where the slip velocity is a function of both wall shear stress and pressure. Using the slip velocity model, the steady state and unsteady state equation of motion was solved in capillary flow, and the calculated results were found to agree with the experimental results to a satisfactory degree. The oscillating flow regime was studied in detail, and the slip flow model was found to predict several features of this flow regime very well. Finally, the effect of interface conditions (surface coatings and metal of construction of slits) on both wall slip and melt fracture was studied.
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Koran, François. "Anomalous wall slip behavior of linear low density polyethylenes." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26394.
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It is becoming generally accepted that wall slip, the loss of adhesion of a polymer to a solid substrate, occurs when the shear stress exceeds a critical value. Wall slip probably plays a much more important role in plastics processing than has been previously thought. For example, the extrudate distortion called sharkskin is thought to involve slip. Recent experiments have shown that this phenomenon is highly material dependant. The surface chemistry of both the molten polymer and the bounding surface interface play important roles in both the occurrence and magnitude of wall slip. The initial objectives of the research were to study slip in further detail, concentrating on the effects of the molecular weight and molecular weight distribution of the polymer. The effects of surface properties were also to be investigated. The research was performed using a sliding plate rheometer. Erratic stress signals were observed when the shear stress exceeded a critical level, and there was strong evidence that these were related to a highly complex type of slip. Thus, a steady slip velocity, which could be simply related to the shear stress, could not be determined. It was concluded that wall slip is, in general, a chaotic process with a strong dependence on initial conditions, sample history, and boundary conditions. Further research is suggested to elucidate this phenomenon.
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Huang, Gang 1971. "Phase diagram for liquid crystalline polymerpolycarbonate blends." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33973.
Full textAbstract:
Blends containing a thermotropic liquid crystalline polymer and an engineering thermoplastic polymer have recently received considerable attention, because liquid crystalline polymers display low melt viscosity, excellent chemical resistance, thermal stability and mechanical performance. A novel mechanism to form binary polymer blends is through phase separation by spinodal decomposition in the unstable region of the phase diagram. The overall objective of this work is to investigate the effects of thermally induced phase separation by spinodal decomposition on the morphology development of liquid crystalline polymer/polycarbonate blends and to obtain a thermodynamic binary phase diagram. The blends were obtained using a twin-screw extruder at various processing melt temperatures. To study miscibility of the blends and the resulting morphology, techniques such as differential scanning calorimetry and scanning electron microscopy were used. The liquid crystalline polymer/polycarbonate blend undergoes phase separation during thermally induced spinodal decomposition exhibiting a miscibility window reminiscent of a lower critical solution temperature. The blend is found to be miscible, when blend Tg slightly decreases. On the other hand, the blend is found to be immiscible as blend Tg increases. A thermodynamic two-phase transition curve phase diagram was obtained using an innovative practical experimental technique in conjunction with twin screw extrusion and scanning electron microscopy.
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Sentmanat, Martin Lamar. "The effect of pressure on the wall slip of linear polyethylene." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39998.
Full textAbstract:
Experiments were performed on a slit die rheometer to determine the effect of pressure on the wall slip of linear polyethylene. A novel shear stress transducer was developed to measure local wall shear stress at several locations along the die. It was found that above the critical shear stress for the onset of slip, the shear stress distribution along the die was nonuniform. Furthermore, it was discovered that the local wall shear stress near the exit of the die was greater than the nominal, or length-averaged, shear stress within the die as calculated from the pressure drop. Teflon$ sp circler$ wall coatings were used to promote slip by lowering the critical shear stress for the onset of slip. Relative local slip velocities were calculated and found to be a function of pressure and wall shear stress.A new semi-empirical model for the pressure dependence of slip was developed based on the effect of pressure on the work of adhesion and the work needed for flow. The new model indicates that pressure can both suppress and promote slip depending on the level of stress involved. At low pressures, and for a given shear stress, slip is markedly suppressed due to the increase in the work of adhesion. As pressure increases, however, the work needed for flow overcomes the work of adhesion, and slip dramatically increases. However, at higher pressure, the effect of pressure on slip becomes weaker. Numerical simulation results with the new model predict the existence of a local maximum in the shear stress distribution along the die for flow with slip.
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Kalali, Kiana. "Quantitative parameters to evaluate mixing in a single screw extruder." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103764.
Full textAbstract:
Mixing is crucial in most polymer processing operations towards obtaining high-quality products (e.g. tubing, tire treads and wire coverings). Material type, screw design, and processing conditions all affect mixing profoundly. Different types of mixing elements have been developed to improve mixing in the single screw extruder; however, the selection of these mixing elements is not trivial. In this work, our purpose is to provide quantitative tools to select the best mixing element. Residence time distribution (RTD) and image analysis were used to compare mixing in three different mixing elements: single flight, Maddox, and Saxton. Residence time distributions were used to indirectly grasp an insight about the strain distribution inside the extruder. Experimental RTD data were derived from silica tracer studies and compared to various mixer models. A model based on a plug flow mixer in series with two continuous stirred tanks best fit the experimental data in all three different mixing elements. For the image analysis method the degree of mixing was determined. Mixtures of polyethylene resins with carbon black were extruded and sliced. Subsequently, sliced samples were scanned to provide images showing the distribution of the carbon black in the resin. The RTD experiments showed that the mean residence time is highest in the Saxton mixer and the lowest in the single flight element. Also, the RTD was broadest in the Saxton mixer and narrowest in the single flight mixer. This means that the polymer in the Saxton mixer experiences the widest range of strains and gets mixed more thoroughly. These results were confirmed by image analysis, which showed that polymers mixed in the Saxton mixer were more homogenously mixed compared to the two other mixing elements.Les phénomènes de mélange dans les extrudeuses monovis ont été étudiés en détail depuis de nombreuses années. Le défi principal est le choix des éléments de mélange les mieux appropriés pour une tâche de mélange donnée. A ce jour, les fabricants d'équipements de mise en oeuvre des matières plastiques s'appuient fortement sur des données expérimentales et leur expérience pour opérer ce choix. Dans ce travail, notre objectif est de développer des critères d'évaluation quantitatifs pour différents éléments de mélange dans les extrudeuses monovis. A cet effet, nous comparons l'effat de mélange dans trois éléments de mélange différents (à savoir une zone de vis à filet simple, une zone de mélange à filet barrière de type Maddock, et une troisième zone à picots de type Saxton) en utilisant la distribution du temps de séjour et l'analyse d'images. Pour la distribution du temps de séjour, une matière de traçage est injectée dans la machine, et sa concentration dans l'extrudat déterminée par la pesée du résidu solide des échantillons. Pour l'évaluation optique du mélange, des images de copeaux d'échantillons étaient analysées au moyen d'un logiciel Matlab. Donc, les différents éléments de mélange sont caractérisés, pour les matières utilisées dans cettte étude (des polyoléfines), par la distribution du temps de séjour et la qualité de mélange obtenue par analyse d'image. Mis ensemble, nos résultats confirment que la qualité de mélange obtenue est directement liée à la distribution du temps de séjour; le meilleur résultat est obtenu avec le mélangeur de type Saxton. Les deux paramètres peuvent être utilisés non seulement pour l'évaluation, mais aussi la prédiction de l'effet de mélange dans d'autres conditions et configurations.
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Tang, Zuojian 1967. "Surface morphology of polyethylene blown films." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31072.
Full textAbstract:
The properties of blown polyethylene (PE) films depend on various factors, including crystallinity, morphology, and orientation, in addition to chemical composition. It has been shown that the optical properties are strongly influenced by surface morphology. In this project, we use non-contact atomic force microscopy (AFM) and polarized light microscopy (PLM) to visualize surface and bulk morphology. Various techniques, such as surface and line roughness, surface and line fractal dimension, pair-correlation function and nearest neighbor distance distribution function, are employed to quantify the description of morphology and to compare the morphological characteristics of a number of polyolefin films of commercial interest. A comprehensive quantitative analysis of surface topography has been performed. The co-monomer of the PE resins was found to play a significant role in the formation and the orientation of spherulite-like domains. The film cross-section microstructure has been evaluated qualitatively by using both AFM and PLM. However, quantitative analysis of bulk morphology cannot be obtained due to knife effects.
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Torres, Enrique J. "Extensional flow and rupture of molten polyethylenes." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33997.
Full textAbstract:
It is well known that the rheological characterization of a polymer melt requires measurement not only of the shear flow properties but also of the extensional flow properties. In the past, extensional flow measurements were not routinely performed because of the difficulties involved in extensional experiments. However, recent innovations have made it easier to study polymers under extensional flow and obtain reliable data. The objective of this research was to characterize polymers with respect to their extensional behavior and failure mechanism. Specifically, long-chain branched polyethylenes produced using constrained geometry catalysts were studied. The research was performed using a Munstedt rheometer, and data obtained by others using a RME rheometer and a capillary rheometer were also utilized. In uniaxial extension, strain softening behavior as well as strain hardening was observed. The polymers exhibiting strain hardening did so at strain rates from 0.005 to 2.5s -1 with an increase in stress hardening as the strain rate decreased. The results suggest the existence of a correlation between tensile stress at necking and number of branch points per molecule multiplied by the weight average molecular weight of the innerbackbone segments. It was concluded that the number of branch points per molecule in a long-chain branched polyethylene governs the level of strain hardening. Unexpectedly, it was found that necking in extensional flow correlates with gross melt fracture in entrance flow. Rupture in extensional flow was found to be chaotic in nature and could not be correlated with gross melt fracture.
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Boudreault, Mélanie. "Determination of zero-shear viscosity of molten polymers." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20496.
Full textAbstract:
Measuring the zero-shear viscosity of a molten polymer is not at all straightforward. Available rheometers are unable to operate at shear rates low enough to measure this important property, especially for polymers that have a very broad molecular weight distribution or a high degree of long chain branching. A new falling ball viscometer, the Magnetoviscometer (MVM), has recently been developed in Austria for the measurement of melt viscosity at very low shear rates. The primary objective of the research was to evaluate this instrument as a tool for the routine measurement of the zero-shear viscosity. Another objective was to develop a reliable and convenient method to prepare samples. Experiments performed near the maximum allowable stresses for various resins are in good agreement with dynamic data obtained using a rotational rheometer. The MVM allows for the measurement of viscosity in a range of shear rates not accessible to most rheometers.
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Brues, Michael J. (Michael Jason). "Thermolysis of mixtures of polyethylene and polystyrene." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22642.
Full textAbstract:
The thermolysis of mixtures of polyethylene and polystyrene was investigated. Overall liquid production for the mixture was above the values predicted from individual polymer reactions. No detrimental effects on the styrene production were evident, as over 50% of the initial polystyrene charge was converted to styrene for polystyrene and for mixtures. There were, however, some differences in the secondary products. No incorporation of one polymer onto another was observed, either in the liquid or the residue.Different reaction conditions were examined. It was determined that using a single reaction temperature (445$ sp circ$C) was as effective at separating the aromatic and aliphatic products as using two different reaction temperatures.
Polystyrene was found to catalyze the thermolysis of polyethylene. Conventional catalysts (Mordenite and FCC zeolite) affected the overall production and product distributions for mixtures and polyethylene, while only changing the product distribution for polystyrene. Hydrogen in the purge gas only slightly decreased the ratio of 1-alkenes to n-alkanes.
Recycled plastics yielded results similar to virgin polymers, although overall liquid production was decreased (probably due to the additives present in the plastics).
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Brunet, Louis 1969. "The response of a pultruded fiberglass tube to lateral loading /." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27991.
Full textAbstract:
This is an investigation of the response of a double fixed-ended pultruded fiberglass tube subjected to large lateral displacements, in both quasi-static and dynamic conditions. The experiments yield a two-mode response of the tubing to loading. The first mode, referred to as the local mode, is dominated by crushing of the cross-section. The second mode, referred to as the global mode, consists of beam flexure and shear components. An analytical model, based on deformed geometry, has been developed to predict the response of the tubing under quasi-static loading conditions. Model results compare well with experiments and minimal computation time is required. Dynamic tests demonstrate a significant rate dependency, which is more pronounced in the globally-dominated portion of the behavior. The model has been used to demonstrate that steel tubing, commonly used as beams or energy absorbers, may successfully be replaced by fiberglass tubing produced by pultrusion or filament winding.
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Park, Hee Eon 1972. "Effect of pressure on the rheological properties of three polyethylenes." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31066.
Full textAbstract:
The effect of pressure on the viscosity of polyethylenes was studied using a newly developed high-pressure, sliding-plate rheometer. The rheometer subjects the sample to a homogeneous pressure and temperature at levels up to 70 MPa and 225°C. Simple shear is generated in the sample, and the resulting shear stress is measured locally in the center of the sample by means of a shear stress transducer. Viscosity curves were generated at four pressures from 0.1 to 70 MPa, and it was found that the pressure data could be shifted onto the ambient pressure curves by means of a pressure shift factor. The viscosity increases exponentially with pressure. Long chain branching increases the pressure sensitivity, but the polydispersity has little effect.The effect of pressure on the creep behavior of polyethylenes was also studied. It was observed that pressure decreases the creep compliance. Careful tuning the controller is required to obtain reliable data when operating the rheometer in the creep mode.
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Khougaz, Karine. "Characterization of polystyrene based diblock copolymer micelles." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40163.
Full textAbstract:
The micellization of polystyrene based block copolymers was investigated in aqueous and in organic media. Micelles formed from polystyrene-b-poly(sodium acrylate) (PS-b-PANa) in sodium chloride solutions were investigated by static light scattering (SLS). The aggregation numbers (N$ rm sb{agg})$ were influenced by low salt concentrations ($<$0.10 M) and they were essentially independent of the soluble block lengths. The core radii ($ rm sb{e}$ agreed well with previous solid state results on similar samples studied by small-angle X-ray scattering (SAXS). It was thus concluded that no supermicellar aggregates were present and that the cores were solvent free.A method to evaluate the critical micelle concentrations (cmc's) of block copolymer micelles by SLS was developed to account for the effects of polydispersity on the cmc. It was found that for block copolymers which have a significant dependence of the cmc on the insoluble block length and which are polydisperse only the present approach was able to evaluate the cmc.
The micellization of PS-b-PANa and PS-b-poly(acrylic acid) (PS-b-PAA) block copolymers were investigated in organic solvents. The cmc's were found to range from $1 times10 sp{-7} { rm to} 5 times10 sp{-9}$ M for insoluble block lengths ranging from 2.6 to 18 units. The N$ rm sb{agg}$ and R$ rm sb{e}$ values for four PS-b-PANa series in tetrahydrofuran, were found to be a function of the length of both blocks. The effect of the degree of neutralization of the PAA block on micellization was probed by SLS and SAXS; micelle formation was found to commence at 5% neutralization. The distribution of water between toluene and the polar cores of block ionomer and sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles was investigated by proton chemical shift measurements as a function of temperature. The amount of water solubilized and the thermodynamic parameters of transfer were found to be a function of the core nature.
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Radiotis, Theodore. "Studies of the molecular dynamics, transport properties, and thermal degradation of PVC." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40231.
Full textAbstract:
This thesis concentrates on three main areas of research in the field of poly(vinyl chloride), PVC: (1) microstructure determination and local chain motions of PVC in a plasticized system, (2) permeability of PVC and plasticized PVC to gases, and (3) computer modeling of the thermal degradation of PVC.A quantitative carbon-13 NMR spectrum of PVC in 1,1,2,2-tetrachloroethane-d$ sb2$ (TCE-d$ sb2$) was recorded. Theoretical predictions using Bernoullian statistics permitted the reassignment of several resonances. Carbon-13 spin-lattice relaxation times and NOE values were measured as a function of temperature at two magnetic fields for PVC in two solvents, di-butyl phthalate (DBP) and TCE-d$ sb2$. The difference found in the simulation parameters, from the Dejean-Laupretre-Monnerie model, for PVC in the two solvents were rationalized by assuming a specific interaction between DBP and the CHCl group of PVC and to the relative solvent quality.
The permeability coefficients, P, of PVC films to oxygen were measured as a function of temperature and plasticizer type and concentration. The plasticizers used were di-(2-ethylhexyl) phthalate (DOP), tri-butyl phosphate (TBP), and a binary mixture of the two with a concentration of $ rm Phi sb{DOP}$ = 0.6). The effect of plasticizer type on the permeation coefficients of oxygen followed the trend: P(TBP) $>$ P($ rm Phi sb{DOP}$ = 0.6) $>$ P(DOP). Arrhenius plots of the permeability coefficients showed that the unplasticized and plasticized PVC films of low concentration of plasticizer ($ rm Phi sb{plas} < 0.2$) displayed a discrete change in the slope, in the vicinity of the glass transition temperature, that reflected changes in the activation energy for permeation. In addition, the permeation and diffusion coefficients of oxygen and hydrogen chloride gases in an unplasticized PVC film were measured as a function of temperature. The results suggest that the increase in segmental mobility of the polymer chains above the T$ rm sb{g}$ increases the diffusivity as well as the zone of activation for diffusion leading to the increase in segmental mobility of the polymer chains above the T$ rm sb{g}$ increases the diffusivity as well as the zone of activation for diffusion leading to the increase in both energy and entropy of activation.
A computer program has been written which simulates, according to Bernoullian statistics, the relative handedness of successive monomer units during polymerization and calculates the probabilities of configurational sequences before and after a specified degradation mechanism. At levels of degradation that are accessible to experimental verification by solution NMR ($<$2%), the changes in isotacticity that are predicted by these simulations are at (or under) the limits of experimental error. Furthermore, the simulations indicate that for the degradation to result in double bond lengths that correspond to experimentally determined values requires that the dehydrochlorination also include some atactic and syndiotactic sequences which, in turn, reduces the changes in P$ rm sb{mm}$. (Abstract shortened by UMI.)
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Simard, Yan. "Thermolysis of polystyrene." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=68051.
Full textAbstract:
Styrene was recovered from polystyrene (molecular weight of 138 000) by thermolysis in a nitrogen atmosphere at temperatures between 368$ sp circ$C and 407$ sp circ$C. The results were independent of the initial weight of polystyrene which was varied between 30 and 480 grams. Up to 70% of the polystyrene was converted to styrene. The styrene yield increased with temperature. At higher temperatures, the residue left in the reactor consisted mainly of styrene monomer, dimer and trimer (MW of 190). The maximum rate constant of volatile production was found to fit a first order model. The activation energy obtained was 166.5 kJ/mol, which is in accordance with literature values.
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Bates, Philip J. "Improving long-fibre compounding via a novel thermoplastic pultrusion process." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59584.
Full textAbstract:
A pultrusion process using staggered cylindrical pins in a molten polymer reservoir is one method of pre-compounding long glass fibre-reinforced thermoplastic materials. This material, if well impregnated with resin, will maintain much of its aspect ratio during subsequent moulding. The longer fiber length translates into improved mechanical properties versus conventional extrusion compounded material. This research studies the effect of a novel pin shape and configuration on the wetting of glass roving during thermoplastic pultrusion compounding.Experimental pultrusion studies using polypropylene indicate that alternating concave (collecting) and convex (spreading) contoured pins promote superior resin impregnation compared to conventional cylindrically shaped pins. A mathematical model describes the necessary convex pin contour and was used to fabricate the convex pins employed in the research. Pins thus designed promote uniform filament spreading across the wide convex contour which in turn favours good resin impregnation.
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Arghyris, Laurent. "Modification of the impact properties of blends of polypropylene and poly(ethylene-vinyl alcohol)." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60574.
Full textAbstract:
The purpose of this research project has been to evaluate the feasibility of improving the impact properties of polypropylene (PP)/ethylene vinyl alcohol copolymer (EVOH) laminar blends by the incorporation of a rubber phase. The impact modifier was poly (ethylene-propylene) rubber (EPR). The study was conducted initially with a batch mixer, and then continued with an extruder. Furthermore, it was decided to evaluate the improvement in impact toughness of the blends upon addition of a polyethylene (PE) phase.The batch mixing studies showed that it is possible to bring the impact properties of maleated PP (MAPP)-based blends to the range of those exhibited by MAPP, by incorporation of both EPR and PE. The sequence of addition of EPR and PE is very important. The products obtained exhibited good adhesion at the interface between the dispersed phase and the matrix. The presence of EPR and PE did not affect the final oxygen permeabilities of the blends.
The extrusion studies showed that the morphology of the blends, and therefore their final properties, depend on the method of compounding. Different MAPP resins were used as the major phase. The best impact properties were found in the case of addition of the EPR-PE phase in a twin screw extruder. The oxygen permeabilities were disappointing, and appeared to be only slightly influence by compositional or processing parameters. One possible explanation is that moisture might have contaminated the EVOH phase, inhibiting its effectiveness as an oxygen barrier.
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Wood-Adams, Paula. "Determination of molecular weight distribution from rheological measurements." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22683.
Full textAbstract:
An important characteristic of a polymer is its molecular weight distribution (MWD). The MWD affects both the processing and solid state performance properties of polymeric materials. Currently the analytical method for evaluating MWD involves the use of gel permeation chromatography (GPC). This is a labor and time intensive procedure, with the accuracy of the results depending strongly on the skill and experience of the equipment operator. Furthermore, GPC is not sensitive to small amounts of high molecular weight material that can have an important effect on processing and product properties. Thus GPC is far from ideal as a tool for industrial quality control. It is known that the rheological properties depend on the MWD, and it has been proposed that complex viscosity data be used to infer the MWD for commercial polymers. There has been some degree of controversy as to whether this is feasible, but recent results of Shaw, Tuminello and their coworkers indicate that for linear polymers this is, in theory, possible. However limitations in the accessible range of frequency, as well as inevitable experimental errors pose serious barriers to the use of such a procedure. We have investigated the severity of these baniers and have shown that within certain, reasonable constraints complex viscosity data can be used to infer a realistic MWD and that this procedure could be used for routine quality control in a production facility.
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Marentette, Joanne M. (Joanne Marie). "The crystallization of poly(ethylene oxide) in blends with neat and plasticized poly(vinyl chloride)." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29082.
Full textAbstract:
The crystallization of poly(ethylene oxide) (PEO) in blends with amorphous poly(vinyl chloride) (PVC), in a mixture with the PVC-selective plasticizer tricresyl phosphate (TCP), and in ternary mixtures with both PVC and TCP has been investigated at several structural levels using the techniques of: (i) theoretical surface interfacial tension calculations, (ii) thermal analysis, (iii) polarized light microscopy, and (iv) polarized infrared microspectroscopy.The invariance of the glass transition temperature of the interlamellar, amorphous PEO suggests a relatively low degree of dispersion in PEO/PVC blends. A slight depression in the equilibrium melting temperature of PEO in blends of high PVC content was observed, and subsequent analysis of the data using the Flory-Huggins equation reveals that, at best, PEO and PVC exhibit limited miscibility in the melt. The melting temperature depression may be accentuated by the addition of TCP, but the depression observed in the ternary mixtures lies within the experimental uncertainty.
In general, the spherulites grown in the presence of additives are coarser and less birefringent than those grown in the pure melt, with the degree of coarseness increasing with increasing additive concentration. The interpretation of the crystallization kinetics of PEO using current nucleation theory clearly demonstrates that the crystallization of PEO in the temperature range of interest occurs within regime III. The slight kinetic discontinuity at $ sim$51$ sp circ$C that has been thought to arise from a regime II/III transition can be attributed to a transformation of the dominant crystal growth face from the (010) crystallographic face at lower temperatures to the (120) face at higher temperatures. The growth rates of PEO spherulites in PEO/PVC blends are not affected by the presence of PVC in the temperature range 49-55$ sp circ$C, even at concentrations as high as 50% PVC. However, the growth rates of spherulites in mixtures containing TCP are significantly depressed.
Dichroic infrared microspectroscopy was employed to investigate the variations in the crystalline structure at the sub-spherulitic level. The determination of the dichroic ratios and the selected peak ratios from the spectra of purely crystalline PEO (obtained by difference spectroscopy) reveals that PVC disturbs the orientation of the crystalline stems of PEO within the spherulites and causes an increase in the crystallization of PEO in the strained, planar zig-zag conformation. PEO, in turn, appears to induce a higher incidence of the planar zig-zag conformation in the PVC molecules. In the ternary mixtures, the plasticizing effect of TCP on PVC renders the PVC molecules more flexible and more mobile, thereby drastically reducing the shearing of the PEO and the resultant formation of the planar zig-zag conformation during crystallization. In effect, the crystallization kinetics and the basic crystalline structure of PEO can be controlled by selection of appropriate proportions of PVC and TCP, a result of major significance and practical importance to the field of polymer blends.
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Ye, Yufeng 1971. "The study of long time relaxation behavior of metallocene polyethylene /." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31081.
Full textAbstract:
The long time relaxation behavior of linear and long chain branched (LCB) metallocene polyethylene (mPE) is very important for understanding their flow properties. One linear and four LCB mPEs were studied in shear creep and recovery measurements. All the mPEs have similar molecular weight and molecular weight distribution but different levels of long chain branching. A technique was developed to eliminate the effect of non-ideal start-up at the beginning of creep experiment and the small residual stress that exists during the creep recovery period. It is found that the existence of long chain branching is responsible for the increasing of the zero shear viscosity, the steady state compliance and the longest relaxation time. The retardation and relaxation spectrums were calculated from the creep compliance. The dynamic compliance calculated using retardation spectrum is compared with that measured directly. Both are in very good agreement. These observations are compared with the molecular dynamics theory.
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Tavichai, Orasa. "Effect of shear on growth rates during polyethylene melt crystallization." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33996.
Full textAbstract:
During processing, polymers are exposed to complex thermal and deformation fields. Under these conditions, partially crystalline polymers undergo crystallization, which contributes significantly to their ultimate properties. While the thermal effects on polymer crystallization have been studied extensively, there is much less research carried out with regard to the effects of deformation and stress on crystallization kinetics. This is in part due to experimental difficulties in making appropriate measurements. In the present work, the Linkam Shearing Cell, in conjunction with a polarized light microscope, was used to study the effect of shear on the growth kinetics of various linear low-density polyethylene (LLDPE) resins. Simultaneously, an effort was made to evaluate the effect of shear on morphology. The experimental and analytical aspects of the work will be described, and preliminary results will be reported.The spherulitic growth rate increased under shear compared to that under quiescent conditions. The circular shape morphology of spherulites was obtained under the shear rate range of consideration (0--1 s-1). The effect of molecular structure in terms of co-monomer and branching content on spherulitic growth rate under quiescent and shear condition was observed. Moreover, the effect of temperature on growth rate under quiescent and shear (0.5 s-1) was studied. The modified Lauritzen-Hoffman equation was used to fit experimental data. The diffusion energy barrier under shear condition (0.5 s-1) was estimated and was found to be lower than the diffusion energy barrier under quiescent conditions.
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Bates, Philip J. "Melt impregnation of glass roving in a thermoplastic pultrusion compounding process." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41328.
Full textAbstract:
Long-fibre reinforced thermoplastics are one of the fastest growing segments in the composites industry. Thermoplastic pultrusion compounding is one of the techniques used to manufacture this injection mouldable material. The pultrusion compounding process used in this research consists of pulling a continuous glass roving over a series of staggered cylindrical pins immersed in a molten thermoplastic bath.This research reports on the effect of several key pultrusion compounding parameters (roving pulling speed, number and diameter of pins, melt temperature and initial roving tension) on the impregnation of nylon 6.6 melt into glass roving. The interlaminar shear strength of pultruded strands and compression moulded test bars, as well as optical microscopy, void fraction measurements and injection moulded specimen physical properties are used to quantify impregnation. Simple mathematical models have been developed to simulate the effect of processing parameters on melt impregnation. Good qualitative agreement between the model and experimental data is observed.
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Hozhabr, Sassan. "Enhancement of interfacial adhesion in polymer blends of polypropylene and poly (ethylene vinyl alcohol copolymer)." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60598.
Full textAbstract:
In the present study a blend system containing polypropylene (PP) and ethylene vinyl alcohol copolymer (EVOH) was considered. Maleic anhydride grafted polypropylene (MAH-g-PP) was used to improve adhesion at the interface. The preliminary work was conducted in a batch mixer and then extended to a single and a twin screw extruders.The results in the batch mixer demonstrated that blends containing high levels of MAH have well bonded morphology and impact strengths comparable to pure materials. Statistical analysis of the results showed that at processing temperature of 200$ sp circ$C and mixing time of 13 minutes, the highest impact strength and largest elongation at break were obtained.
In the extruder the morphological studies revealed the presence of a layered structure in the core region of the samples when a slit die was employed. The oxygen permeability of extruded samples with EVOH content higher than 20vol% resembled multi-layer systems.
Impact strength of extruded ribbons drastically improved by increasing the maleation level to 0.2wt% and precompounding the virgin resins in a twin screw extruder. Morphological observations however, revealed some disruption in the layered structure and consequently decline of oxygen barrier properties.