Microfibrillar composites (MFC) were prepared from the blends of polypropylene (PP) and poly (ethylene terephthalate) (PET) at a fixed weight ratio of 85/15. The blending of the mixture was carried out in a single screw extruder, followed by continuous drawing at a stretch (draw) ratio 5. The stretched blends were converted into MFC by injection moulding. Scanning electron microscopy (SEM) studies showed that the extruded blends were isotropic, but both phases possessed highly oriented fibrils in the stretched blends, which were generated insitu during drawing. The PET fibrils were found to be randomly distributed in the PP matrix after injection moulding. The non isothermal crystallization behaviour of the as extruded blend, stretched blend and MFC was compared. The analysis of the crystallization temperature and time characteristics revealed that the PET fibrils in the stretched blend had a greater nucleating effect for the crystallization of PP than the spherical PET particles in the as extruded blend and short PET fibrils in the MFC.
Dr. Jayanarayanan K., Bhagawan, S. S., Thomas, S., and Joseph, K., “Morphology development and non isothermal crystallization behaviour of drawn blends and microfibrillar composites from PP and PET”, Polymer Bulletin, vol. 60, pp. 525–532, 2008.