Phase changes in isotactic polypropylene measured by microhardness
نویسندگان
چکیده
منابع مشابه
Extensional-flow-induced crystallization of isotactic polypropylene
A filament stretching extensional rheometer with a custom-built oven was used to investigate the effect of uniaxial flow on the crystallization of polypropylene. Prior to stretching, samples were heated to a temperature well above the melt temperature to erase their thermal and mechanical histories and the Janeschitz-Kriegl protocol was applied. The samples were stretched at extension rates in ...
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Dispersions of isotactic polypropylene (PP) particles in polystyrene (PS) were produced by interfacially driven breakup of nanolayers in multilayered systems that were fabricated by means of layer-multiplying coextrusion. The droplet size was controlled by the individual PP layer thickness ranging from 12 to 200 nm. In addition, PP was melt blended with PS to produce PP droplets larger than tho...
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Bulk isotactic polypropylene in the a form was studied using density functional theory-based computations. The computed physical structure of this system is in excellent agreement with available experimental data. The electronic band structure, ionization potential, and electron affinity were also determined. The impact of various types of chemical imperfections (including double bond, hydroxyl...
متن کاملPrimary Crystal Nucleation and Growth Regime Transition in Isotactic Polypropylene
We studied nucleation and crystal growth in two polypropylene samples by analyzing the number of spherulites, their size, and shape for various treatments in a hot-stage microscope. The consistency of nucleation and growth data were tested by using overall crystallization experiments and the Jonhson–Mehl–Avrami–Kolmogorov Q1 equation. In isothermal conditions, for temperatures, TC, varying betw...
متن کاملMesoporous silica-supported zirconocene catalysts for highly isotactic polypropylene.
A new bis(indenyl)zirconocene bearing a pendant Si-Cl anchor has been grafted onto MCM-41, SBA-15, MCM-48 and a disordered mesoporous silica for the polymerisation of ethylene and propylene, producing polymers with very high molecular weights, low polydispersities and, in the case of polypropylene, higher levels of isotacticity than obtainable with analogous homogeneous systems.
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ژورنال
عنوان ژورنال: Journal of Materials Science Letters
سال: 1988
ISSN: 0261-8028,1573-4811
DOI: 10.1007/bf01730607