Nonisothermal melt-crystallization kinetics of syndiotactic polypropylene compounded with various nucleating agents

Nonisothermal melt-crystallization behavior of syndiotactic polypropylene (sPP) compounded with 5% by weight (wt %) of some inorganic fillers [i.e., kaolin, talcum, marl, titanium dioxide (TiO2), and silicon dioxide (SiO2)] and 1 wt % of some organic fillers, which are some sorbital derivatives (i.e., DBS, MDBS, and DMDBS) was investigated and reported for the first time. It was found that the ability of these fillers to nucleate sPP decreased in the following sequence: DBS > talcum > MDBS > SiO2 similar to kaolin similar to DMDBS > marl > TiO2 with DBS being able to shift the crystallization exotherm by similar to18degreesC on average, while TiO2 was able to shift the crystallization exotherm by only similar to6degreesC on average, from that of neat sPP. The Avrami analysis revealed that the Avrami exponent for sPP compounds varied between 2.9 and 4.3, with the values for neat sPP varying between 3.1 and 6.8. Lastly, the Ziabicki's crystallizability of sPP compounds was greater than that of neat sPP, suggesting an increase in the crystallization ability of sPP as a result of the presence of these fillers. (C) 2004 Wiley Periodicals, Inc.