SUMMARY A study of the isothermal crystallization behaviour and an analysis of the kinetic parameters of compatibilized blends of polyolefines (isotactic poly(propy1ene) (iPP) and high density polyethylene (HDPE)) with a semiflexible liquid crystalline polymer (LCP) SBH 1 : 1 : 2 of Eniricerche, Italy are presented in this work. The compatibilizers are ad hoc synthesized graft copolymers of the liquid crystalline polymer grafted to functionalized poly(propy1ene) (PPAA) or polyethylene (PEox) -PP-g-SBH and PE-g-SBH copolymers, respectively. It has been established that the LCP dispersed phase in the blends plays a role in nucleation for the polyolefine matrix crystallization. This effect is more pronounced in the poly(propy1ene) matrix than in the polyethylene matrix, due to the lower crystallization rate of the former. The addition of PP-g-SBH copolymers (2.5-10 wt.-%) to 90/10 and 80/20 iPP/SBH (w/w) blends provokes a drastic increase of the overall crystallization rate of the iPP matrix and of the degree of crystallinity. Contrarily, the addition of PEg-SBH copolymers (2.5-8 wt.-%) to 80/20 HDPE/SBH (w/w) blends almost does not change or only slightly decreases the PE overall crystallization rate. Moreover, the interpretation of the Avrami exponents indicates that the iPP crystallization mechanism in the compatibilized iPP/SBH blends remains unchanged only until a degree of conversion of 0.7 and changes above this value; the PE crystallization mechanism and the degree of crystallinity in the compatibilized HDPE/SBH blends do not alter. The results were interpreted in terms of some differences in the compatibilization mechanism and efficiency of both types of graft copolymers (PP-g-SBH and PE-g-SBH). The relationships between blend morphology and nucleation phenomena are discussed.

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