Study On The Ester-amide Exchange Reaction Of The PET/PA6 Blend And Its Control

DSC, SEM and X-ray diffraction methods, etc. are adopted to study the influence of the ester-amide exchange reaction of PET/PA6 blends on the melting points of components, the crystallinity and the morphology of the components. The result indicated that the block copolymer produced from the ester-amide exchange reaction which would occur when PET and PA6 mixed with each other at the melting state can enhance the interfacial adhesion, lead to the inhomogeneity of the product properties. Therefore, it is necessary to control the ester-amide exchange reactions of the PET/PA6 blends. This article concentrated on the control of the ester-amide exchange reaction by both using the inhibitors and introducting graft copolymer.Using the inhibitor The inhibitors of PS-g-MAH, Nan+2PnO3n+1, KH2PO4, P-(OC6H5)3, P-(OC2H5)3, C12H25SO3Na and FeSO4·7H2O are used to control the ester-amide exchange reaction of PET/PA6 blend, and finally the PS-g-MAH and the Nan+2PnO3n+1 are the better inhibitors , which would not undermine. In addition, the PS-g-MAH and the effect of Nan+2PnO3n+1 on the crystallinity, the morphology as well as the thermal decomposition performance of the blend have been studied. The result indicated that the inhibitors could enhance the interfacial adhesion in certain degree, but could also deduce the crystallinity as well as the thermostability.Introducing graft copolymer The PA6-g-PS and the PET-g-PS copolymer were produced at thepresence of the dicumylperoxide (DCP). The influence of the ratios of the feeding, the content of initiator, the reaction time and the reaction temperature on the grafting efficiency were discussed. The Molau experiment, FTIR, 1H-NMR, X-ray diffraction were used to prove these two kinds of products were both the graft copolymers. PET, PA6 including PA6-g-PS and PET-g-PS respectively were mixed with each other. And we inspected the ester-amide exchange reaction of the blend by studying the change of the melting point and by using FTIR and X-ray diffraction. The result showed that the graft copolymer could suppress ester-amide exchange reaction at the early stage of blending. In addition, the influence of the ratios of components and the blending time on the ester-amide exchange reaction, the crystallinity, thermostability and the morphology were not obvious; the introduction of the graft copolymers enhanced the interfacial adhesion obviously; with lengthening the blending time, the degree of the ester-amide exchange reaction increased, while the crystallinity as well as the thermostability reduced. Finally, the kinetics of nonisothermal crystallization of pure PET/PA6, the PET/PA6s containing inhibitor of Nan+2PnO3n+1 and graft copolymer respectively were studied. The result indicated that under the condition of experiment, the crystallization speed increased and the peak temperature of crystallization moved to lower temperature with the increasing of the cooling rate; Under the same cooling rate, the more the ester-amide exchange reaction, the lower the crystallization temperature, the slower the crystallization speed.