Effects of glass-fiber content and coolant temperature on temperature and crystallinity profiles of PP melt during cooling

This investigation studied the temperature gradients and degree of crystall inity of polypropylene melt across a circular duct during the cooling proce ss, where the coolant used was chilled water. The effects of glass-fiber co ntent, varying from 0 to 44 wt %, and coolant temperature, varying from 5 t o 20 degreesC, were our main interest. The results suggested that the rate of cooling of the polymer of each position across the duct was not signific antly affected by the temperature of the coolant and glass-fiber contents, although the rate of cooling was influenced by the size of the duct, The cr ystallization temperature and degree of crystallinity of the polymer increa sed with increasing glass fiber contents and the coolant temperature. These phenomena were associated with the heat transfer between the coolant and t he polymer, crystallization temperature, exothermic crystallization process , and thermal properties of the polymer. (C) 2001 John Wiley & Sons, Inc.