In-Situ Microfibrillar PET/iPP Blend via a Slit Die Extrusion, Hot Stretching and Quenching Process: Influences of PET Concentration on Morphology and Crystallization of iPP at a Fixed Hot Stretching Ratio

• Published in: Journal of macromolecular science. Physics Vol. 44; no. 2; pp. 203 - 216
• Main Authors: Li, Zhong-Ming, Lu, A., Lu, Z.-Y., Shen, K.-Z., Li, L.-B., Yang, M.-B.
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 16-03-2005
• Subjects: crystal structure; crystallization; in-situ microfibrillar blend; morphology
• ISSN: 0022-2348; 1525-609X
• DOI: 10.1081/MB-200049793

In-situ microfibrillar poly(ethylene terephthalate) (PET)/isotactic polypropylene (iPP) was fabricated via a slit die extrusion, hot stretching, and quenching process. Morphological observation shows that well-defined microfibrils were generated in-situ. The microfibrils become larger with the increase of PET concentration. The presence of PET microfibrils shows significant nucleation ability for crystallization of iPP. Higher concentration of PET microfibril corresponds to faster crystallization of the iPP matrix, while the variation of PET concentration has little influence on the onset and maximum crystallization temperatures of iPP matrix during cooling from melt. Optical microscopy observation reveals that transcrystallites form in the microfibrillar blend, in which the PET microfibrils play as the center row nuclei. In the as-stretched microfibrillar blends, small-angle X-ray scattering measurements show that the long period of lamellar crystals of iPP is not affected by the presence of PET micofibers. Wide-angle x-ray scattering reveals that the β phase of iPP is obtained in the as-stretched microfibrillar composites, whose concentration decreases with the increase of PET microfibril concentration. This suggests that PET microfibrils do not promote the occurrence of the β phase.