화학공학소재연구정보센터
Polymer Engineering and Science, Vol.51, No.5, 931-939, 2011
The Effect of a Sodium Octacosanoate-Based Nucleating Agent on the Crystallization of Thermoplastic Polyurethanes
Sodium octacosanoate (NaC28-32) is commonly used as a nucleating agent in polyester and polyamide formulations. In this work, the effect of adding this agent to three chemically identical thermoplastic polyurethanes (TPUs), but with distinct molecular weights, was addressed, focusing on the study of the crystallization phenomenon. The modified Avrami and Avrami-Ozawa kinetic models were applied to the isothermal and non-isothermal crystallization processes, respectively, and both indicated faster crystallization when the nucleating agent was used, with an increase in temperature and rate of crystallization of the TPU. Such effect was partly attributed to the formation of a larger number of crystallization nuclei in comparison to the neat TPU. Besides, the nucleating effect was more pronounced for the TPU with the lowest molecular weight (30,000 Dalton). The Avrami and Avrami-Ozawa models indicated that the TPU crystallization process occurs with the development of two-dimensional lamellar aggregates, axialites, and that the incorporation of the nucleating agent does not alter this geometry. POLYM. ENG, SCI., 51:931-939, 2011. (C) 2011 Society of Plastics Engineers