Crystallization and Thermal Behaviors of Poly(ethylene terephthalate)/Bisphenols Complexes through Melt Post-Polycondensation.

Shichang Chen,Shangdong Xie,Wenxing Chen,Jianna Bao,Shanshan Guang,Xianming Zhang

doi:10.3390/polym12123053

Abstract

Three kinds of modified poly(ethylene terephthalate) (PET) were prepared by solution blending combined with melt post-polycondensation, using 4,4′-thiodiphenol (TDP), 4,4′-oxydiphenol (ODP) and hydroquinone (HQ) as the bisphenols, respectively. The effects of TDP, ODP and HQ on melt post-polycondensation process and crystallization kinetics, melting behaviors, crystallinity and thermal stability of PET/bisphenols complexes were investigated in detail. Excellent chain growth of PET could be achieved by addition of 1 wt% bisphenols, but intrinsic viscosity of modified PET decreased with further bisphenols content. Intermolecular hydrogen bonding between carbonyl groups of PET and hydroxyl groups of bisphenols were verified by Fourier transform infrared spectroscopy. Compare to pure PET, both the crystallization rate and melting temperatures of PET/bisphenols complexes were reduced obviously, suggesting an impeded crystallization and reduced lamellar thickness. Moreover, the structural difference between TDP, ODP and HQ played an important role on crystallization kinetics. It was proposed that the crystallization rate of TDP modified PET was reduced significantly due to the larger amount of rigid benzene ring and larger polarity than that of PET with ODP or HQ. X-ray diffraction results showed that the crystalline structure of PET did not change from the incorporation of bisphenols, but crystallinity of PET decreased with increasing bisphenols content. Thermal stability of modified PET declined slightly, which was hardly affected by the molecular structure of bisphenols.

Highlights

Poly(ethylene terephthalate) (PET) is one of the most widely used linear semicrystalline thermoplastic polyester in many industrial and everyday applications because of its good mechanical and thermal properties, non-toxicity, processing low energy requirements and high chemical resistance [1,2,3]
The main aim of this work is to evaluate the effect of a small amount of bisphenols on the intrinsic viscosity, crystallization kinetics, melting behavior, thermal property and crystallinity of PET
To investigate the growth ability of PET molecular chains by melt post-polycondensation in the presence of bisphenol compounds, the bisphenols/PET complexes have been tablet pressing into fixed thickness in advance, which will cause the intrinsic viscosity (IV) of PET to be slightly lower than the original

Summary

Introduction

Poly(ethylene terephthalate) (PET) is one of the most widely used linear semicrystalline thermoplastic polyester in many industrial and everyday applications because of its good mechanical and thermal properties, non-toxicity, processing low energy requirements and high chemical resistance [1,2,3]. The crystallization and its degree of crystallinity play an important role on applications, which would highly affect physical and mechanical properties [5,6,7,8,9,10,11,12]. Tremendous effort has been ongoing to develop PET production methods by incorporation other polymers and adjusted crystallization kinetics of PET were characterized. It was found that in PET/PLA blends, the degree of crystallinity of PET was reduced by blending with polylactic acid (PLA) [13]

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