Crystallization kinetics of polypropylene containing a sorbitol nucleating agent

• Published in: Polymer journal Vol. 45; no. 1; pp. 87 - 93
• Main Authors: KATSUNO, Satoshi, YOSHINAGA, Masahiro, KITADE, Shinichi, SANADA, Yusuke, AKIBA, Isamu, SAKURAI, Kazuo, MASUNAGA, Hiroyasu
• Format: Journal Article
• Language: English
• Published: Avenel, NJ Nature Publishing Group 01.01.2013
• Subjects: Applied sciences; Competition; Cooling; Crystallization; Exact sciences and technology; Exponents; Networks; Nucleation; Organic polymers; Physicochemistry of polymers; Polypropylenes; Properties and characterization; Sorbitol; Propylene polymer; polypropylene; Experimental study; Oxygen heterocycle; sorbitol; SAXS; Induction period; Melt crystallization; scattering; Isotactic polymer; Concentration effect; Bicyclic compound; crystallization; synchrotron X-ray; Kinetics; Nucleating agent; Isothermal crystallization
• ISSN: 0032-3896; 1349-0540
• DOI: 10.1038/pj.2012.199

We carried out an isothermal crystallization experiment on isotactic polypropylene (iPP) containing 0.2 and 3.0% of 1,3:2,4-bis(p-methylbenzylidene)sorbitol (PDTS) as a nucleation additive. Compared with neat iPP, the induction period before crystallization was markedly shortened, and thus the quench depth became shallower by ∼15 °C. Avrami analysis showed that the Avrami exponent was very sensitive to temperature; it decreased from 3.5-4 to 2 with a decrease in the crystallization temperature Tc (that is, an increase in the cooling depth) of only 4 °C, in contrast with iPP, where the exponent was 4 for all Tc . Small-angle X-ray scattering showed an upturn at low q only for iPP/PDTS, suggesting that the gel network made from PDTS was formed before iPP crystallization. This study shows that the iPP/PDTS crystallization kinetics and its temperature sensitivity were determined by the competition between two events: PDTS network growth and iPP crystallization.