Study On Preparation And Properties Of High Impact Polylactic Acid Composites

With the heavy consumption of petroleum resources and the increasingly serious problem of white pollution,bio-based polymer materials have attracted more and more attention,which derived from renewable resources and biodegradable polymer materials.Polylactic acid(PLA)is a biodegradable polymer material derived from renewable resource starch.Because of its well mechanical strength,processability,and biocompatibility,it has become the most promising biodegradable polymer material.However,due to its high brittleness,especially its poor impact resistance and poor heat resistance,which significantly limits the promotion and application of polylactic acid.This paper adopts reactive blending method to toughen and modify polylactic acid to prepare high-impact polylactic acid composite materials,and through SEM,FTIR,rotary rheometer,DSC,DMA and other characterization methods to analyze and study the structure and performance of polylactic acid composite materials,the main work is as follows.(1)Preparation and properties of PLA/PEBA composites.The bio-based thermoplastic elastomer poly(ether-block-amide)(PEBA)is used to toughen polylactic acid(PLA).In order to improve the interfacial adhesion of PLA and PEBA,PEBA was primarily grafted with the polar monomer glycidyl methacrylate(GMA),which can react with the end group of PLA(-OH,-COOH)to prepare the functionalized elastomer PEBA-GMA,and the effects of the ratio of different graft monomer components(GMA:NVP:DCP)on the mechanical properties of PLA/PEBA composites were studied.The results exhibit that as the ratio of graft monomer components rises,the impact strength of PLA/PEBA composites increases at the same time.When the ratio of graft monomer components is 5:5:0.5(GMA:NVP:DCP),the impact strength of PLA/PEBA-GMA(70/30,w/w)blend is as high as 88.6 k J/m~2,and the elongation at break is164.1%,which is about 30 times and 20 times that of pure PLA,respectively.The PLA/PEBA composites were characterized by SEM,FTIR,DSC,DMA and rotational rheometer,and found that the end groups of polylactic acid(-OH,-COOH)and the oxygen groups of PEBA-GMA during the blending process undergo a chemical reaction,which reinforce the interfacial bonding strength between the two phases,improves the interface compatibility between the PLA and the dispersed phase PEBA,and with the increase in the proportion of grafted monomer components,the interface performance of PLA/PEBA composite has been markedly upgrade,thus preparing a high impact polylactic acid composite material.(2)Preparation and properties of PLA/EBA-GMA composites.Polylactic acid is toughened with ethylene butyl acrylate glycidyl methacrylate graft copolymer(EBA-GMA).In order to improve the reactivity of the epoxy groups on the EBA-GMA with the end groups of polylactic acid,a catalyst(N,N-dimethyloctadecylamine)(DMSA)was added during the blending process.The effect of DMSA content on the properties of PLA/EBA-GMA composites was studied.The results show that a small amo unt of DMSA can greatly improve the impact toughness of PLA/EBA-GMA composites.By comparison,the mechanical properties of the PLA/EBA-GMA(80/20,w/w)blend system after the addition of the DMSA are better than the PLA/EBA-GMA(70/30,w/w)blend system.When the DMSA content is 0.1%,the elongation at break of PLA/EBA-GMA(80/20,w/w)blend can reach 53.7%,which is about 6 times that of pure PLA and when the DMSA content is 0.5%,the impact strength of PLA/EBA-GMA(80/20,w/w)blend is up to 87.8 k J/m~2,which is about 30 times that of pure PLA.The structure and properties of PLA/EBA-GMA composites were characterized by SEM,FTIR,DSC,DMA and rotational rheometer.The results show that with the increase of the DMSA content,the reactivity between the end groups of PLA and EBA-GMA is gradually enhanced,so that the interfacial adhesion between the polymers is greatly improved,therefor a high impact polylactic acid composite was prepared.