A STUDY ON THE CRYSTALLIZATION BEHAVIOR OF POLYPROPYLENE, POLYETHYLENE AND THEIR BLENDS BY DYNAMIC-MECHANICAL AND THERMAL METHODS

Studies on the crystallization of polymers are usually carried out by dilatometry, differential scanning calorimetry (d.s.c.) and optical mi croscopy. These methods have been widely used in the analysis of cryst allization kinetics using the Avrami equation. Direct determination of nucleation rate and density is only possible by the optical microscop e technique. We have employed a new technique for studying the crystal lization behaviour of polymers by using a dynamic mechanical method. T his method is capable of detecting the onset of nucleation. Semiquanti tative data on the nucleation density and the initial crystallization rate may also be deduced by this method. Results from the dynamic mech anical method are cross-compared with d.s.c. and optical microscope da ta for polypropylene, polyethylene and their blends, and are shown to be mutually consistent.