Poly(1

4-cyclohexanedimethanol terephthalate) modified by synergistic copolymerization of bio-based isosorbide (ISB) and isophthalic acid (IPA)

which is called PICTA in this study

was prepared by direct esterification process. The effect of ISB unit content on the properties of PICTA copolyester was studied when the IPA unit content was 15 mol%

in order to develop an amorphous high heat-resistant copolyester. The molecular structure

thermal properties

crystalline properties and thermal degradation properties of PICTA copolyester were investigated using nuclear magnetic resonance hydrogen spectroscopy (

1

H-NMR)

differential scanning calorimeter (DSC)

X-ray diffractometer (XRD) and thermogravimetric analyzer (TGA). The results showed that the glass transition temperature of PICTA copolyester increases linearly by about 0.8 ℃ for every 1 mol% increase in the unit content of ISB. When the proportion of ISB copolymerization increased to 25.4 mol%

the PICTA copolyester samples annealed at 180 ℃ for 10 h tended to be in an amorphous state

which indicated that the introduction of ISB copolymerization units could significantly inhibit the crystallization capability of PICTA copolyesters. In addition

the results of TGA study showed that the PICTA copolyester had good thermal stability and the initial thermal decomposition temperature was higher than 405 ℃

but the presence of ISB copolymerization units did not change the thermal decomposition mechanism of the copolyester.