Effect of nucleating agent addition on crystallization of isotactic polypropylene

✍ Scribed by Y. Feng; X. Jin; J. N. Hay

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 193 KB
• Volume: 69
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19980906)69:10<2089::aid-app20>3.0.co;2-w

✦ Synopsis

The isothermal and nonisothermal crystallization kinetics of nonnucleated and nucleated isotactic polypropylene ( iPP ) were investigated by DSC and a polarized light microscope with a hot stage. Dibenzylidene sorbitol ( DBS ) was used as a nucleating agent. It was found that the crystallization rate increased with the addition of DBS. The influence of DBS on fold surface energy, s e , was examined by the Hoffman and Lauritzen nucleation theory. It showed that s e decreased with the addition of DBS, suggesting that DBS is an effective nucleating agent for iPP. Ozawa's theory was used to study the nonisothermal crystallization. It was found that the crystallization temperature for the nucleated iPP was higher than that for nonnucleated iPP. The addition of DBS reduced the Ozawa exponent, suggesting a change in spherulite morphology. The cooling crystallization function has a negative exponent on the crystallization temperature.