Crystallinity of isotactic polypropylene by DSC
Polimery 1994, No 10, 626
Polypropylenes manufactured by the Mazovian Refinery and Petrochemical Works, Płock, Poland, by the use of two generations of catalysts were compared in terms of crystallinity. The degree of crystallinity was determined by differential scanning calorimetry (DSC) for granulated polymers and then redetermined after their thermal histories had been standardized by melt crystallization of an analytical sample on controlled cooling in the DSC instrument. The following conclusions were drawn: the degree of crystallinity is inversely proportional to the viscosity average molecular weight of the polypropylenes examined, the polypropylenes obtained over the second generation catalyst are characterized by degrees of crystallinity higher than those obtained over the first generation catalyst, the measurement results are clearly more dispersed for granulated polypropylene than for the polymer with a standardized thermal history.
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