A study on the crystallization behavior and mechanical properties of poly(ethylene terephthalate) induced by chemical degradation nucleation

Abstract

In order to overcome the low crystallization rate of poly(ethylene terephthalate) (PET), bicyclo[2.2.1]heptane-2,3-dicarboxylic acid disodium salt (HPN-68L), a highly active organic nucleating agent for polypropylene, was selected to replace the special nucleating agent of PET to improve PET crystallization due to its carboxylate anion structure, which usually shows a high induced nucleation ability for PET. The crystallization and properties of the composites were systematically investigated. It was found that HPN-68L had a significant nucleation effect on PET. The crystallization temperature and the nucleation efficiency of PET was increased by approximately 14 °C and 68.4%, respectively at a very low content of 0.6 wt% HPN-68L. Moreover, the half-time of crystallization and isothermal crystallization activation energy decreased upon the addition of HPN-68L. The long period of PET decreased and the number of spherulites increased after adding HPN-68L, while the crystal form of PET did not change. In addition, the nucleation mechanism of HPN-68L induced PET crystallization was studied and a chemical degradation nucleation mechanism was proposed. The flexural strength and modulus of PET were improved, whereas the impact strength decreased to a certain extent upon the addition of HPN-68L.