Effect of Molecular Weight and Molecular Weight Distribution on Isothermal Crystallization Kinetics of Isotactic Polypropylene

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 ...

Rheological Method for Determining Molecular Weight and Molecular Weight Distribution

High-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...

Structure and molecular mobility of nascent isotactic polypropylene powders

The detailed structure and molecular mobility of nascent isotactic polypropylene (iPP) powder was investigated using differential scanning calorimetry, transmission electron microscopy (TEM) and nuclear magnetic resonance (NMR). The crystallinity of the nascent iPP powder is approximately 33%, which is much lower than that of melt-quenched or isothermally crystallized iPP. Peaks from the variab...

the effect of explicit teaching of metacognitive vocabulary learning strategies on recall and retention of idioms

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