Reactive extrusion of polypropylene: production of controlled-rheology polypropylene (CRPP) by peroxide-promoted degradation
Reactive extrusion of polypropylene: production of controlled-rheology polypropylene (CRPP) by peroxide-promoted degradation
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DOI：
10.1016/s0142-9418(03)00072-2
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发表时间：
2004-04-01
期刊：
影响因子：
5.1
通讯作者：
Ghasemi, I
中科院分区：
文献类型：
--
作者：
Azizi, H;Ghasemi, I
介绍了自由基致聚丙烯(PP)熔融相降解的实验研究结果。实验在同向旋转双螺杆挤出机中进行。采用引发剂过氧化二异丙苯(DCP)作为自由基生成剂。研究了引发剂浓度、温度(200℃和230℃)、螺杆转速(30 Rpm)对共混物熔体流动指数、力学性能、热性能和流变性能的影响。引发剂浓度是最显著的变量。熔体流动指数随引发剂浓度的增加而增大。反应温度和螺杆转速对挤出物的熔体流动指数无显著影响。这归因于挤出机中的最短停留时间足以完成所有降解反应。降解后的树脂比原始树脂具有更强的牛顿行为。粘度随过氧化氢浓度的增加而降低。在不同过氧化氢水平下，降解树脂的熔点保持相对恒定，但结晶度略有增加。当过氧化氢的质量分数为0.1%时，共混物的力学性能没有明显变化。超过0.1%重量时，断裂伸长率和冲击强度显著降低。(C)2003爱思唯尔有限公司。保留所有权利。
Results of experimental studies of free-radical-induced degradation of polypropylene (PP) in the melt phase are presented. Experiments were carried out in a co-rotating twin-screw extruder. The initiator, dicumyl peroxide (DCP) was used as a radical generator. Concentration of the peroxide was in the range 0.02-0.6 %wt. Melt flow index, mechanical, thermal and rheological properties were measured to see the effect of initiator concentration, temperature (200 and 230 degreesC) and screw rpm (30 and 70 rpm). Initiator concentration was the most significant variable. Melt flow index increased with initiator concentration. Reaction temperature and screw rpm had no significant effect on the melt flow index of extrudate. This was attributed to the minimum residence time in the extruder being sufficient for all degradation reactions to be completed. Degraded resins had more Newtonian behavior than the original resin. Viscosity reduced with peroxide concentration. Melting point of degraded resin remained relatively constant at different levels of peroxide but the crystalline fraction increased slightly. No significant change of the mechanical properties was seen up to 0.1 %wt of peroxide. Beyond 0.1 %wt elongation at break and impact strength reduced considerably. (C) 2003 Elsevier Ltd. All rights reserved.