Non-isothermal Crystallization Kinetics Analysis of Poly(trimethylene-co-butylene Terephthalate) Copolymers

Abstract

Poly(trimethylene-co-butylene terephthalate) (PTBT) copolymers containing PTT and PBT components were synthesized with various compositions in order to blend their advantageous properties together into one polymer system and to improve further their disadvantageous properties. The non-isothermal crystallization of the copolymers at various cooling rates was investigated by DSC. PTBT copolymers develop their crystallization later and show lower melting temperatures than the homopolymer corresponding to the richest component. The non-isothermal crystallization of PTBT copolymers is fitted better by the modified Avrami analysis than the Ozawa analysis. The combined Avrami and Ozawa model (Mo model) is also found to describe the experimental data fairly well. The estimated Avrami exponent n varies in the range of 3-4, indicating that the non-isothermal crystallization follows the homogeneous nucleation and two to three dimensional growth mechanism. The crystallization rate is accelerated by increasing cooling rate but retarded by PTT units in the polymer backbones as a minor component. In addition, the activation energy of non-isothermal crystallization was estimated by the Kissinger approach. PTT and PBT homopolymers have relatively lower activation energy of crystallization than PTBT copolymers and in the crystallization process lower activation energy leads to more rapid crystallization rate.

Keywords:

• activation energy
• copolymer
• non-isothermal crystallization behavior
• poly (butylene terephthalate) (PBT)
• poly (trimethylene terephthalate) (PTT)

Acknowledgments

The work was financially supported by the Scientific Research Foundation of Hubei Provincial Education Department (No. B200717003) and the Research Foundation of Wuhan University of Science and Engineering of Huibei provincial in China (No. 20073202).