Synthesis and characterization of poly(ethylene terephthalate-co-1,4-cyclohexanedimethylene terephtlatate)-block-poly(tetramethylene oxide) copolymers

Abstract

A series of poly(ethylene terephthalate-co-1,4-cyclohexanedimethanol terephthalate)-block-poly(tetramethylene oxide) (PETG-block-PTMO) copolymers were synthesized by means of a polycondensation process and characterized using ¹H nuclear magnetic resonance (H NMR) and Fourier transform infrared spectroscopy (FTIR), that confirm the successful synthesis of the material. Differential scanning calorimetry (DSC), small – and wide-angle X-ray diffraction (SAXS and WAXS), and thermogravimetric analysis (TGA) were used in order to evaluate the influence of the block copolymers' composition and microstructure on the phase transition temperatures, thermal properties, as well as the thermooxidative and thermal stability of the PETG-block-PTMO copolymers, respectively. The mechanical properties were investigated by tensile testing and dynamic mechanical measurements (DMTA). We found that along with an increase in PTMO weight fraction, both number-average molecular weights and intrinsic visocisities increase. Moreover, an increase in the flexible segments content in PETG-block-PTMO resulted in shifting the values of glass transition temperatures toward lower ones, which was confirmed by DSC and DMTA analyses, thus affirming the miscibility of both phases. At the same time, along with an increase of PTMO flexible segments amount in the PETG-block-PTMO copolymers, the values of Young's modulus, tensile strength at yield and weight losses in lower temperatures range, i.e. 280–390 °C, decrease.