强剪切分散混炼器对聚丙烯流变行为的影响

利用自行研制的多级磨盘式强剪切分散混炼器，研究了聚丙烯经过混炼器作用后的流变行为。通过测定混炼器不同转速下制得的聚丙烯试样的熔体流动速率值，结合GPC对其相对分子质量及相对分子质量分布的测试结果，表明聚丙烯经混炼器的强剪切作用后发生了显著的分子链断链现象，其中在5r／min的元件转速下，PP的MW、Mx和Mx＋1分别降低了33．4％、66％和83．7％，而其力学性能并无明显降低；因机械力断链而产生的活自由基，会引发进一步的降解和交联等高分子力化学反应。

Effect of Intensive Shear and Dispersion of Mixer on Rheological Behavior of Polypropylene

The rheological behavior of PP after intensive shear in a self-designed multi-mill mixer was studied.The measurement of melt index and GPC showed that the molecular weight of PP was de- creased by the scission of molecular chains during shear,the higher the rotating speed,the heavier the scission.However,when the rotating speed was 40 r/min,the (?)_(z 1) of the sample increased,which was considered as the result of the compromise between the chain scission and crosslinking and suggested a useful method for the controllable degradation of PP.Furthermore,mechanical properties of all the specimens after shearing in the mixer were not deteriorated seriously.