Preparation and structural properties of CHDA modified PBT
Using purified terephthalic acid(PTA),1,4-butanediol(BDO)and 1,4-cyclohexanedicarboxylic acid(CHDA)as raw materials,CHDA modified polybutylene terephthalate(PBT)copolyesters were obtained through direct esterification.The effect of CHDA content on the structure and properties of the modified PBT copolyesters was studied.The results showed that the condensation time of modified PBT copolyester was prolonged and the intrinsic viscosity increased with the increase of CHDA con-tent;the addition of CHDA had a significant impact on the melting point,melting crystallization peak temperature and crystallini-ty of modified PBT copolyester,and the melting point of modified PBT copolyester decreased to 190.68℃,the melting crystalli-zation peak temperature decreased to 140.49℃and the crystallinity decreased to 17.42%when the mass fraction of CHDA was 20%;the thermal stability of modified PBT copolyester was slightly lower than that of conventional PBT,and the thermal decom-position peak temperature of modified PBT copolyester dropped to 399.25℃when the mass fraction of CHDA was 20%;and the tensile strength and bending strength of modified PBT copolyester decreased,the elongation at break and impact strength in-creased with the increase of CHDA content,and the comprehensive performance of modified PBT copolyester was excellent,with a tensile strength of 40.65-44.11 MPa,elongation at break of 143.23%-218.85%,impact strength of 5.12-5.88 kJ/m2 and bending strength of 45.15-51.31 kJ/m2,when the mass fraction of CHDA was 5%-10%.
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