The Research Of Preparation,Structure And Properties Of Polyamide6/SBC Blends

Low impact strength in dry state and low temperature,high water absorption and poor dimensional stability are the main disadvantages of polyamide 6(PA6),which can be overcame by blending PA6 with another polymer.Such polymers as Polyolefin,ABS and PPO were usually used to be blended with PA6 at present.In this study,PA6/SBC blends were prepared via in situ anionic ring opening polymerization,reactive extrusion and melted blending,respectively.The structure and properties of PA6/SBC blends and PA6 microspheres obtained from PA6/SBC blends prepared by in situ anionic ring opening polymerization were then studied.Firstly,CL and SBC were used as raw materials to prepare PA6/SBC blends with PA6 separated phase/SBC continuous phase via in situ anionic ring opening polymerization of CL.After removing SBC continuous phase,PA6 microspheres were obtained.The effects of continuous phase composition,continuous phase content and anionic polymerization catalyst on the morphology of PA6/SBC blends,crystallinity of PA6 microspheres and thermal properties of PA6 microspheres were studied.If bi-isocyanate was used as catalyst of anionic ring opening polymerization of CL,PA6 continuous phase/SBC separated phase changed into PA6 separated phase/SBC continuous phase in PA6/SBC blends when the SBC content was 6 wt%.However,the phase inversion occured at 7 wt% of SBC content in PA6/SBC blends when tri-functional isocyanate was used as the catalyst.For PA6/PS in situ blends prepared using bi-functional isocyanate as catalyst,the phase inversion occured when the PS content was 15 wt%.The DSC results showed that the crystallinity,crystallization temperature and melting temperature of PA6 microspheres were all higher than those of pure PA6 resin.Then,the structure and properties of PA6/SBC blends prepared by reactive extrusion via in-situ polymerization of CL were studied.The results of scanning electron microscopy(SEM)showed that SBC phase was dispersed in PA6/SBC blends with an average diameter of 0.6～5.5 μm.X-ray diffraction(XRD)results showed that onlyγ-crystal could be found in the XRD-profile of PA6/SBC blends.DSC analysis illustrated that the crystallization temperature,melting temperature and crystallinity of PA6/SBC blends were all decreased with increasing SBC content.Compared to pure PA6,both the tensile strength and bending strength of PA6/SBC blends were lower.However,the impact strength of PA6/SBC blends was nearly two times of that pure PA6 when SBC content was 25 wt%.At last,SEBS-g-MA was used as compatibilizer to prepare PA6/SBC blends via melted blending.SEM photographs showed that the SBC dispersed phase size in PA6/SBC blends prepared via melted blending was slightly larger than that in PA6/SBC blends prepared via reactive extrusion.Meanwhile,the toughness of PA6/SBC blends prepared via melted blending was lower than that of PA6/SBC blends prepared via reactive extrusion with the same SBC content.