茂金属聚乙烯弹性体和三元乙丙橡胶增韧聚丙烯的比较

Comparison of metallocene polyethylene elastomer and EPDM in toughening modification of PP

用茂金属聚乙烯弹性体mPE代替三元乙丙橡胶EPDM对聚丙烯PP增韧改性并进行了比较。结果表明,mPE共聚物中的辛烯质量分数越高,其对PP的增韧效果越好;随着共混物中弹性体质量分数的增加,共混物的拉伸强度和弹性模量降低,扯断伸长率增大。PP/mPE与PP/EPDM增韧体系相比,二者的拉伸强度差别不大,但PP/mPE的弹性模量和扯断伸长率稍低;与EPDM相比,mPE对PP具有较好的增韧效果,含有质量分数40%mPE的共混物试样在-30°C下的缺口冲击强度已超过纯PP的20倍,约是相同弹性体质量分数PP/EPDM的近9倍。另外,PP/mPE还具有较低的拉伸永久变形、压缩永久变形和蠕变变形。

A comparison of metallocene polyethylene elastomers (mPE) and ethylene-propylene ter-polymer (EPDM) was made in toughening modification of polypropylene(PP). The results showed that the toughening effectiveness of mPE increased with increasing the octene content in mPE copolymers. With the increase of elastomer content, the tensile strength and elastic modulus of the blends decreased, while the elongation at break increased. PP/mPE and PP/EPDM blends had the similar tensile strength, but the elongation at break and the elastic modulus of PP/mPE blends were somewhat lower. Compared with EPDM, mPE had a super toughening effect for PP. It was shown that at the elastomer mass fraction of 40%, the Charpy notched impact strength at-30 °C of PP/mPE blends was 20 times higher than that of neat PP and nearly 9 times as high as that of PP/EPDM blend with the same elastomer Content. PP/mPE blends also possessed lower tension set, compression set and creep strain.