Effect Of Compatibilizer On Properties Of Polystyrene Resin/Poly (Lactic Acid)alloy

With the development of science and technology,polymer materials is widely used in agriculture,industry,energy,aerospace and information fields.However,most of the polymer material is difficult to degradate which is harmful to the environment.Poly(lactic acid)(PLA)has attracted more and more attention because of its biodegradable properties.As a general plastic,Polystyrene resin is widely used in daily consumer goods.Preparation of Polystyrene resin/PLA alloys will not only reduce environmental pollution,but also extend the application of PLA.In this paper,a series of poly(styrene–ran–methyl acrylate)(PSMA)with different ratio of monomers was synthesized by surfactant–free emulsion polymerization.And the effects of initiator amount and reaction temperature on the monomer conversion and the gel fraction were investigated.The results show that the monomer conversion rate increases with the increase of the temperature and the the initiator amount,but the gel fraction of the emulsion increases simultaneously and the emulsion becomes unstable.The results of gel permeation chromatography(GPC)show that the number average molecular weight of the PSMA is 60 000~70 000.The Fourier transform infrared(FTIR)spectroscopy shows that PSMA have both characteristic peaks of polystyrene and poly(methyl acrylate),and the strength of the characteristic peaks of the poly(methyl acrylate)gradually increased with the increase of the amount of methyl acrylate,which indicates that PSMA was confirmed by copolymerization of styrene and methyl acrylate.Then,PSMA modyfied polystyrene(PS)/PLA alloy was prepared by melt blending.The microstructures,rheological behavior and mechanical behavior of PS/PLA alloy were characterized by optical microscope with heating stage,scanning electron microscopy(SEM),rotational rheometry and universal tensile tester,respectively.The results show that PSMA can effectively reduce the aggregation of the dispersed phase in the PS/PLA alloy under annealing.And the dispersion of PLA phase and PS phase was more uniform under shear,which leads to the refinement of the dispersed phase particles.Further more,the interaction between PS and PLA was increased by PSMA,and the mechanical properties of PS/PLA alloy was improved.Compared with the PSMA composed of more methyl acrylate,the PSMA composed of less methyl acrylate had less compatible effect on PS/PLA alloy.In order to improve the toughness of PLA,PSMA modified high impact polystyrene(HIPS)/PLA alloy was prepared by melt blending.The rheological behavior test showed serious interfacial slip between HIPS phase and PLA phase in the HIPS/PLA alloy without PSMA because of the poor compatibility between PLA and HIPS.And the compatibility of HIPS and PLA was effectively improved by PSMA,and HIPS/PLA alloy showed less interface slip at high shear rate.Differential scanning calorimetry(DSC)showed that HIPS had little effect on the crystallinity of PLAnon–isothermal crystallization.However,after adding PSMA,the interaction between HIPS and PLA was increased,which inhibited the growth of PLA,resulting in PLA crystallinity decreased in HIPS/PLA alloy.The addition of PSMA can improve the interfacial bonding of HIPS/PLA alloy.And mechanical properties of HIPS/PLA alloy was improved greatly by PSMA.Futhermore,HIPS can effectively improve the toughness of PLA,adding 0.5 wt% PSMA compatibilizer,the impact strength of HIPS/PLA alloy can be increased by 92.4%.