The Study On PB-g-MSG Toughen Polylactic Acid

Polylactic acid(PLA)is a kind of degradable,environmental-friendly polymer material.It has been used widely because of its excellent processing and degradability.However,low toughness and poor impact strength of PLA limited its application in some degree,therefore,toughening is necessary in order to enhance the impact toughness.In the present research,the reactive PB-g-MSG toughening particles with different core-shell ratios were synthesized by seed emulsion polymerization method.PB-g-MSG particles were used to toughen PLA.In addition,epoxy resin and organic montmorillonite(OMMT)were used in the blends to obtain the PLA blends with rigid-tough balance.The toughening efficiency and mechanisms of the blends were investigated in detail.(1)The influence of PB-g-MSG particles core-shell ratio on the toughening behavior of PLA were researched.The results indicated that the impact strength increased with the improvement of core-shell ratio and PB-g-MSG particles content.In case of low core-shell ratio,cavitation of PB was difficult to take place due to the low PB content and high internal grafting,therefore,toughening efficiency was not prominent.On the other hand,when the core-shell ratio was too high,toughening efficiency decreased slightly due to the aggregation of PB-g-MSG particles.The impact strength and yield strength of 640J/m and 24 MPa could reach for the PLA blend when the core-shell ratio of toughening agent was 70/30 and the content was 30%.(2)The influence of epoxy resin with different epoxy values on the properties of PLA/PB-g-MSG blends was investigated.When the epoxy value of epoxy resin was too low,chain extension and crosslinking was less obvious and led to low enhancement of the performance of PLA blend.On the other hand,epoxy resin with high epoxy value made excessive crosslinking of PLA and could not improve the toughening efficiency of PB-g-MSG particles.Epoxy resin with appropriate epoxy value could both lead to chain extension and improve the toughening efficiency of PB-g-MSG.In the present research,epoxy resin with medium epoxy value enhanced the performance of PLA/PB-g-MSG blends.The results showed that the impact strength and yield strength of 650J/m and 30 MPa were achieved respectively when 3% EPM and 30% PB-g-MSG were used.(3)Influence of OMMT on performance of PLA/PB-g-MSG blends was characterized.The maximum impact strength of 650J/m and yield strength of 30 MPa were achieved when 4% OMMT was added in the blend.Low addition did not achieve a goal of reinforcement,on the contrary,high addition of OMMT led to aggregation of OMMT in PLA matrix which decreased the impact strength of PLA and lose the effect of reinforcement.(4)Both incase of adding toughening agent or reinforcing agent,the toughening mechanism of blends mainly follow to cavitation of PB rubber particles and shear-yield of matrix.