Study On Toughening Modification Of Recycled Poly (Ethylene Terephthalate) Blends

In the present study,high-toughen and low-cost recycled poly(ethylene terephthalate)(R-PET)engineering plastics was prepared by R-PET blended with linear low densitypolyethylene(LLDPE),compabilitied with glycidyl methacrylate grafted poly(ethylene-octene)(mPOE)or maleic anhydride-grafted poly(styreneethylene/butyldiene-styrene)(SEBS-g-MA)via reactive extrusion.It was successful to solve technical problems in preparing R-PET blends.(1)The effect of compatibilization and toughening on morphological structure,thermal and mechanical properties of the R-PET/LLDPE blends modified respectively by SEBS or SEBS-g-MA has been studied.The theoretical analysis of the formation mechanism of the morphology of blends was also illustrated.The results showed that the dispersed phase of the R-PET/LLDPE blend with SEBS or SEBS-g-MA compatibilizer could form core-shell particles,and PET-g-SEBS-g-MA graft copolymers in R-PET/LLDPE/SEBS-g-MA blends can play good toughening effect,the particles size is smaller,its distribution is more uniform.The ’Harkin’s spreading coefficient can be used to analyze and explain the mechanism of the formation of core-shell particles in the blends.DSC results show that LLDPE particles can act as nucleation in the R-PET/LLDPE blend.The crystallization temperature of R-PET/LLDPE/SEBS-g-MA blends was lower than that of R-PET/LLDPE blends,dispersed phase particles of the blends smaller and more uniform,the R-PET nucleating effect is more obvious.The results of mechanical properties show that the notched impact strength and elongation at break of the blends are higher than that of the R-PET/LLDPE blends,while the flexural strength,flexural modulus and tensile strength of the blends are unchanged with the addition of SEBS and SEBS-g-MA.(2)The effect of mPOE content on morphology and properties of R-PET/ LLDPE /m POE blends was investigated and critical compatibilizer concentration was calculated in theory.The results showed that dispersed phase particle size and interparticle distance reduced with increasing mPOE content,but keep constant above the critical compatibilizer concentration about 5wt%.While the critical compatibilizer concentration calculated in theory was about 1.9 wt%.The notched charpy impact strength of blends was improved greatly with increasing mPOE content.