剪切速率对动态硫化PP/EPDM热塑性弹性体相态结构及性能的影响

采用动态硫化法,在双螺杆挤出机中制备以聚丙烯(PP)/三元乙丙橡胶(EPDM)为基体材料的热塑性弹性体,研究螺杆转速对PP/EPDM热塑性弹性体相态结构及性能的影响;采用差示扫描量热(DSC)仪分析了PP/EPDM热塑性弹性体的结晶性能,通过扫描电子显微镜(SEM)分析PP/EPDM热塑性弹性体的微观相态结构,并用万能试验机等对其力学性能进行测试。结果表明,随着螺杆转速的增加,PP/EPDM热塑性弹性体的结晶温度降低,凝胶含量、拉伸强度和断裂伸长率先增大后减小,压缩永久变形先减小后增大,而螺杆转速对硬度的影响不明显。当螺杆转速为180 r/min时,PP/EPDM热塑性弹性体的凝胶含量、拉伸强度和断裂伸长率均达到最大值,分别为56.8%,15.9 MPa和634%,压缩永久变形和硬度(邵A)均达到最小值,分别为68.8%,88。

Influences of Shear Rate on Phase Structure and Properties of Dynamic Vulcanized PP/EPDM Thermoplastic Elastomer

Using dynamic vulcanization method,thermoplastic elastomers with polypropylene (PP)/ethylene-propylene-diene monomer (EPDM) as the matrix was prepared in the twin screw extruder,and the effects of screw rotating speed on the phase struc-tures and properties were studied. The crystallization behaviors and microstructures of PP/EPDM thermoplastic elastomers were studied by DSC and SEM respectively. Also,mechanical properties of PP/EPDM thermoplastic elastomers were tested by a test machine. The results indicate that crystallization temperature reduces with the increasing of screw rotation speed. The gel content, tensile strength and elongation at break of PP/EPDM thermoplastic elastomer first increase and then decrease with the increase of screw rotation speed. The compression set first decreases and then increases with increase of screw rotation speed. But the effect of screw rotation speed on the hardness is not obvious. When the screw rotation speed is 180 r/min,gel content,tensile strength and elongation at break reach maximum at 56.8%,15.9 MPa and 634% respectively and the minimum compression set and hardness (Shore A) can be obtained at 68.8% and 88 respectively.