Synthesis and characterization of poly(butylene terephthalates) modified by hydroquinone bis(2-hydroxyethyl)ether

Abstract

A series of thermoplastic poly(butylene-co-hydroquinone bis(2-hydroxyethyl)ether terephthalates) (PBHT), with different molar ratios of hydroquinone bis(2-hydroxyethyl)ether (HQEE)/1,4-butanediol 9/91, 18/82 and 27/73, were synthesized via melt polycondensation. The compositions, thermodynamics and crystallization properties of the obtained copolyesters were characterized in detail by 1H NMR, differential scanning calorimeters (DSC), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). These results showed that the PBHTs were successfully synthesized, and the incorporation of the HQEE group significantly improved thermal properties of the polymers. However, HQEE did not change the crystal structure of PBT. The Tm values of the copolymers decreased (from 208 °C to 174 °C) with increasing content of HQEE segments, on the contrary, Tg values increased (from 37 °C to 43 °C). The temperatures for 5% weight loss did not decrease and appeared at a range of 373–377 °C.