Interpenetrated spherulites of poly(butylene succinate) poly(vinylidene chloride-co-vinyl chloride) blends.: An optical microscopic study

Interpenetrated spherulites of poly(butylene succinate)/poly(vinylidene chloride-co-vinyl chloride) (PBSU/PVDCVC) blends were investigated by optical microscopy. The spherulites of PBSU and PVDCVC were negative and positive respectively, and birefringence of PVDCVC was small under crossed nicols. The spherulitic growth rate of PVDCVC showed complex dependence on the crystallization temperature T-c. Interpenetrated spherulites were formed under most of the experimental conditions, PBSU content 30%-60% and T-c 338 K-378 K. Optical microscopy revealed that the birefringent pattern of the area of a PVDCVC spherulite changed into that of a PBSU spherulite after penetration. This result indicates that the lamellae of PBSU grow along those of PVDCVC, and it is the evidence for the formation of interpenetrated spherulites. The microscopic observations implied that the density of lamellae in PVDCVC was sparse. The birefringent pattern of PBSU spherulites changed with experimental conditions. The blends with low PBSU content showed neither negative nor positive spherulite. This birefringence was also kept in the area of PVDCVC spherulites after penetration.