Thermal oxygen aging properties of polypropylene enhanced by different lengths glass fiber
In order to study the effect of different lengths fiber on the thermo-oxygen aging properties of polypropylene(PP)composites,PP composites reinforced with long glass fiber(PP/LGF)were prepared by melt impregnation method.After continuous aging for 40 days at 120℃,the aging samples were observed and characterized by rotating rheometer and scanning electron micro-scope.The effects of different length composite glass fibers on the mechanical,crystalline and rheological properties of PP compos-ites under thermal oxygen aging were compared,and the mechanism of the effects of long and short fiber composite on the aging properties of PP were discussed.The results show that after 40 days of aging,the average tensile strength decrease by 2.39%,the bending strength increase by 0.79%,and the impact strength retention rate reach more than 87.0%.Before and after aging,the crys-tallinity of fiber composite samples is higher and increase to 49.12%after aging.After aging,the shear stress of PP composite samples decrease obviously.In addition,it was observed by SEM that the change of the interface morphology was not obvious before and after aging,but the samples with lower average length of glass fiber were better combined with PP matrix.The results show that under the trend of hardening and brittleness caused by thermal oxygen aging,the different length of fiber pairing has a better inhibition effect on this trend,and improves the stability of impact strength.The combination of different length of fibers can improve the crystallinity of PP composite and reduce the shear stress during aging.
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