Isotactic poly(propylene) (iPP) transcrystallites are obtained in in situ microfibrillar polyethylene terephthalate (PET)/iPP blends during a slit extrusion-hot stretching-quenching process. Based on morphological information from X-ray scattering and microscopy, three nucleation origins are proposed in microfibrillar reinforced blends under an elongational flow field: (a) the classical row nuclei model; (b) fiber nuclei; (c) nuclei induced by fiber assistant alignment. The last model provides a natural explanation for the case that transcrystallites only occur in some microfiber reinforced blends under flow rather than without the external field.
Macromol. Rapid Commun.

Li, Z.-M., Li, L.-B., Shen, K.-Z., Yang, W. S., Huang, R., & Yang, M.-B. (2004). Transcrystalline morphology of an in situ microfibrillar poly(ethylene terephthalate)/poly(propylene) blend fabricated through a slit extrusion hot stretching-quenching process. Macromol. Rapid Commun., 25, 553–558. doi:10.1002/marc.200300086