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 ...
متن کاملHigh-pressure crystallization of isotactic polypropylene droplets
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...
متن کاملA first principles investigation of isotactic polypropylene
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 کاملThe influence of chain defects on the crystallisation behaviour of isotactic polypropylene
The crystallization characteristics of the !-, "-and #-phases of isotactic polypropylene were studied for welldefined and fully characterized polymers with varying amounts of stereoand regio-defects. The specimens enabled us to study separately the influence of the type of chain defect and the concentration of defects on the parameters of interest. A combined defect fraction (CDF) was introduce...
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...
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ژورنال
عنوان ژورنال: KOBUNSHI RONBUNSHU
سال: 1998
ISSN: 0386-2186,1881-5685
DOI: 10.1295/koron.55.512