Notes

It has been observed that semi-crystalline polymers with shorter relaxation time undergo fast crystallization and exhibit the morphology composed of ‘‘skin–core’’ kind of structure [9]. The skin is composed of frozen oriented polymer layer developed when molten thermoplastic comes into contact of mold walls. The skin thickness depends on the temperature of mold and melt, and on injection speed.

only significant molding parameter is the mold temperature with p value of 7.7%.
high mold temperature is favorable for the growth of both type crystallites
Because of high p value the melt temperature and injection speed are not of much statistical significance. at high melt temperature rate of crystal nucleation becomes prominent and spherulites growth is checked by nucleation of new crystal growth sites.
high melt temperature leads to formation of smaller crystallites of both types.
increase in injection speed is favorable for the growth a-crystallite size but has adverse effect on b-crystallite size. At higher injection speed the molten polymer is subjected to high shear rate inside the mold cavity that causes the transformation of thermodynamically less stable b-phase to more stable dense a-phase
crystallization of iPP during the injection molding is influenced by the elongation rate and shear inside the mold cavity.