In situ microfibrillar blends and composites of polypropylene and poly (ethylene terephthalate): Morphology and thermal properties

Microfibrillar blends were prepared from polypropylene and poly (ethylene terephthalate) by extrusion followed by cold drawing. The draw ratio employed had a prominent effect on the aspect ratio of the microfibrils produced, as revealed by scanning electron microscopy. The subsequent isotropization step between the T(m) of the polymers created microfibrillar composites with randomly oriented short microfibrils of poly (ethylene terephthalate). The X ray diffraction patterns of the microfibrillar blends were different from those of corresponding composites although the polypropylene phase in both exhibited predominantly the presence of alpha crystallites. The crystallization of the polypropylene phase was affected by the orientation and diameter of the poly (ethylene terephthalate) microfibrils. The short microfibrils in the microfibrillar composites were not effectual in hastening the crystallization of polypropylene. The thermal decomposition studies revealed the capability of microfibrillar blends to delay the degradation better than the microfibrillar composites.