Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 28 for “"Isotactic polypropylene"”.
-
Polymer Crystallization: Micro- and Nano- Filler Effects on Isotactic Polypropylene
Isotactic polypropylene (iPP) is one of the commodities used in the largest quantity today. Its good mechanical properties and relatively low price result in continuous growth of pro-duction and expansion of its market. The continuously increasing application accelerates research on all related …
-
Relationships between micromorphology and impact properties of injection moulded isotactic polypropylene
… examination of the micromorphology of a range of isotactic polypropylene injection mouldings, paying particular attention to the outer layers which are difficult to characterise and to then relate the micromorphology revealed to the impact properties. Models which relate the mechanism of impact …
-
An investigation into thermally induced structural modifications in isotactic polypropylene and its blends with amorphous terpolymers
Isotactic polypropylene undergoes rearrangement of its ternary structure when rapidly quenched from the molten state. This is an important area since cooling from the molten state is a fundamental aspect of a typical industrial extrusion process.<br/><br/>Studies were carried out on a range of …
-
Production And Structure/Properties Of Nylon-6 Core / Isotactic Polypropylene Sheath Bicomponent Fibers Suitable For Use In Carpeting Applications
Bicomponent fibers consisting of nylon-6 and isotactic polypropylene were produced. In-situ, reactive compatibilization was achieved using a maleic anhydride functionalized polypropylene between the materials at the interface. The overall goal of the research was to produce a bicomponent fiber of …
-
Toughening mechanisms in polypropylene filled with rigid particles
… The mechanisms of deformation and fracture of isotactic polypropylene filled with CaCO3 particles were studied. In slow tension, addition of fillers increased the modulus and decreased the yield stress independent of filler type. An optimum size of particles was found to improve Izod impact …
-
Equilibrium Melting Temperature Determination of Semicrystalline Polymers through Nonlinear Hoffman-Weeks Extrapolation and Secondary Crystallization of Ethylene/Styrene Copolymers
… analysis is successfully applied to the cases of isotactic polypropylene and poly(ethylene oxide). The predicted initial lamellar thickness as a function of the crystallization temperature matches well with experimental results and/or literature values. Results based on the nonlinear HW analysis …
-
A study of miscibility, morphology, crystallization and melting behavior of isotactic poly(propylene) in blends of poly(propylene) and poly(1-butene)
… thesis, the miscibility behavior of blends of polypropylene (PP) and poly(l-butene) (PB1) will be reexamined. The driving force for this study is the fact that contradictory conclusions on this subject exist in the literature. In this thesis, the glass transition behavior, morphology, …
-
Single wall carbon nanotubes as viscosity modifiers in polypropylene matrix nanocomposites
… as low shear rate viscosity modifiers in the polypropylene matrix of nanocomposites. To create nanocomposites which did not demonstrate increased low shear rate viscosity when nanotubes were added into the polymer melt, this work focused on modifying the sidewall profile of the SWNTs and …
-
Crystallization behavior and morphological features of two LARC polyimides and local orientation studies of two semicrystalline model composites
… superstructure in poly(glycolide co-lactide) and isotactic polypropylene. An increase in orientation on an absolute basis as a function of position was successfully measured. Orientation function values were higher on an absolute basis for the transcrystalline superstructure. However, the sign of …
-
Molecular weight modulation in polyhydroxybutyrate fermentations
… It has material properties similar to isotactic polypropylene; it can be produced from renewable resources; it is biodegradable. Unfortunately, it is very brittle when compared to polypropylene. The physical property that most significantly affects elastic behavior is molecular weight. …
-
Computational modelling of interfacial failure behaviours in polymer–metal joints
… focuses on polymer–metal joints consisting of isotactic polypropylene (iPP), iPP grafted with maleic anhydride (iPPgMA), or iPP grafted with amine groups (iPPgNH₂) and hydroxylated γ-Al₂O₃, which is a model for an oxidised aluminium surface, and investigates the contributions of the stiffnesses …
-
Infrared Frequency Shifting in Thermally- and Mechanically-Stressed Polymers (Anharmonicity, Nonequilibrium, Ftir, Fourier, Transform, Spectrometer)
… or intrachain Gruneisen effect) in individual polypropylene chains accounts for the observed frequency shifting in samples of highly oriented, isotactic polypropylene. Each chain is modelled as a one-dimensional anharmonic system, whose wavefunctions and energies are obtained in the …
-
Effects of high pressure solidification on the tensile properties of polypropylene
… cooled from the melt. In this study, samples of isotactic polypropylene were solidified under pressures up to 40,000 psi. In addition to tensile properties, the resultant density, microstructure and DTA structure were examined. From all measurements, it was concluded that the degree of …
-
Processing of composite fibers based on polypropylene and a thermotropic liquid crystalline polymer
Isotactic polypropylene (PP) was reinforced with Vectra B950 (VB), a thermotropic liquid crystalline polymer (TLCP), in two novel fiber spinning processes. In one process, a single VB melt stream was surrounded by a sheath of PP in a manner comparable to a wire coating process just prior to melt …
-
Fourier-Transform Infrared Studies of Polypropylene During Mechanical and Thermal Deformations
… profile asymmetry are reported for various polypropylene samples as functions of uniaxial stress, (sigma), and temperature. Generally, it was found that stress- and temperature-induced frequency shift coefficients, (alpha)(,x) and (beta)(,x), depended on the stress rate (sigma), draw ratio …
-
The blending and permeability of polymers for packaging applications
In this study, commercially available isotactic polypropylene (PP) and nylon-6 (PA6) blends and laminates were prepared, to develop a material with optimal water vapour and oxygen barrier properties. The effect of compatibilizers on phase dispersion has been investigated using three commercial …
-
The effects of ionising radiation on polypropylene
… and the literature relating; to the effects on polypropylene is reviewed. Oxidative and free radical reactions are discussed with particular reference to post-irradiationeffects.Isotactic and atactic polypropylene were δ and electron irradiated to doses of up to 20 megarad. Irradiations …
-
Effect of intermediate solvents on poly(ether ether ketone)
… another semi-crystalline thermoplastic polymer, isotactic polypropylene. PEEK specimens were stressed in the inside of glass cones and immersed in a series of solvents. Differences among solvent uptakes of stressed and unstressed specimens were explained in terms of crazing and SINC. Microtensile …
Page 1 of 2