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.

The offshore oil industry is constantly seeking new and more cost efficient solutions to every aspect of their operations. In the later years, use of polymeric composite materials has proven to reduce cost and enhance reliability in several areas of oil operations. Several independent efforts, notably in Europe and in the US have targeted development of both spoolable and segmented fibre reinforced polymer pipe systems. These composite pipe systems have been designed for high internal pressure applications, with additional loads being both static and dynamic. / In this research, the short-term, high strain, cyclic bending fatigue of spoolable glass-fibre reinforced epoxy pipes designed for high-pressure static chemical injection line service (SSI) was investigated. Bending and torsion fatigue loading may occur during pipe laying operations. Bending (static and fatigue) of composite pipe was simulated experimentally using a self-designed four-point bending jig on a 25 metric ton MTS hydraulic testing machine. Comparisons between experimental results, simple analytical and numerical static solutions were executed. Numerical solutions for static analysis were found using I-DEAS Master Series 5.0 finite element analysis software. The research effort also attempted to utilise a finite element software developed at McGill University to predict fatigue behaviour of the composite pipe. / Findings in this research effort assist understanding of short-term, high strain, fatigue behaviour of spoolable composite pipes designed for static high pressure operations, as well as indicate the validity of the finite-element analysis efforts executed in this research.

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.

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.

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.

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.

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.

The pendant drop apparatus is the most reliable and accurate method of measuring the interfacial tension of polymer melts. In spite of its widespread use, a detailed experimental procedure has yet to be published. This study examined all practical aspects of pendant drop experiments with viscous polymer melts and establishes procedures for material preparation, syringe diameter selection, experimental protocol, determination of equilibrium, and the most accurate measurement of interfacial tension. In addition, the effects of both drop volume and unstable drops on interfacial tension measurements are discussed. Comparing the surface tension and interfacial tension values for several polyethylene (PE) and polystyrene (PS) resins to literature data tested the effectiveness of the experimental procedure. / The values of surface tension of several experimental linear low-density polyethylene (LLDPE) resins were determined and related to the copolymer structural and material properties. It was determined that the surface tension of the LLDPE hexene copolymers is primarily a function of the chain branching density rather than number average molecular weight. This occurs because the properties of a branched end are believed to be similar to those of a chain end. Therefore, bulk polymer properties of a branched polymer should depend primarily on the concentration of branched ends. Studying the relationship between the surface tension and the free volume of the LLDPE copolymers corroborated the relationship between the surface tension and the branching density. The values of surface tension and surface tension temperature coefficients of the LLDPE copolymers were found to be similar to literature values of linear polyethylene of equal effective molecular weight. However, the findings are inconclusive due to inconsistencies in the literature data. Also, the effects of polydispersity were believed to have caused a significant surface tension reduction and increased the value of the surface tension temperature coefficient in one of the samples.

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.

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.