Polyarylate / Polyester Blend Fiber Thermal Performance Study

In this paper, the thermal behaviors of (p-hydroxybennzoate/2-hydroxy-6-naphthoic acid) copolyester (P(HBA/HNA) ), polyethylene terephthalate (PET), and ACPET (P(HBA/HNA) and PET blend) fibers were studied by means of differential scanning calorimetry (DSC), thermal gravimetric (TG) analysis, dynamic mechanic analysis (DMA) and wide-angle X-ray diffraction(WAXD). The behaviors of the annealed fibers were also studied. The study of this paper was very important for the application and further study of the fibers.The melting behaviors and non-isothermal crystallization of PET, P(HBA/HNA) and ACPET fibers were characterized by using DSC respectively and compared with each other. There are double peaks, in both heating and cooling DSC curves of ACPET fibers. The melting point and crystallization temperature of ACPET fibers are lower than those of PET fibers.The melting peak of ACPET is high and sharp at the side of lower temperature, while the melting peak of ACPET is low and wide at the side of higher temperature. When PET fiber was heated, the improvement of PET crystalline construction is inhibited by the existence of P(HBA/HNA)in the blend fibers and the crystallites of ACPET are smaller than those of PET. This may be the main reason of the lower melting point. The melting peak at the side of higher temperature may be caused by the melting of bigger crystals of PET.Based on Jeziorny model, non-isothermal crystallization data of three fibers were analyzed. The Avrami exponent n of PET vary from 2.8 to 4.17 and the Avrami exponent n of P(HBA/HNA) vary from 2.12 to 3.43. The method of resolving the overlapping peaks was used to investigated the non-isothermal crystallization data of ACPET. The separated peaks were fitted and then the parameters non-isothermal crystallization kinetics data were calculated by Jeziorny model. The Avrami exponent n of ACPET was vary from 1.2 to 3.0, which was lower than that of PET. This showed that the crystallization of PET in ACPET was confined by component of P(HBA/HNA).When annealed below melting temperature, the crystallization structure and dimension stability of PET were improved as the annealing temperature increasing.The crystal structure was more perfect and the dimension stability of P(HBA/HNA) were also improved as the annealing temperature increasing. And the crystallization and dimension stability of ACPET were mainly influenced by component of PET.There were diffraction peaks on the WAXD figures of P(HBA/HNA) and ACPET, when 2θ~ 200. And the peak of ACPET was bigger than that of P(HBA/HNA).The Friedman method, ASTM E698 method and Kissinger method were used to analyze the thermal degradation kinetics of PET, P(HBA/HNA) and ACPET fibers. The results obtained by the three methods are similar. And it has been found that the activation energy for the decomposition of P(HBA/HNA) fibers was higher than that of the other two,which shows that P(HBA/HNA) fibers has the best thermal stabilities.The results of DMA showed that the dimension stability and rigidity of P(HBA/HNA) were better than those of PET and ACPET.