时间扫描研究低剪切条件下PP／PS合金材料的静态流变特征

Investigations on the Static Rheologicai Behaviors of PP/PS Alloys by Time Sweep Method at Lower Shear Rates

选用典型的不相容体系聚丙烯／聚苯乙烯（PP／PS）合金材料为研究对象，采用时间扫描的方式讨论了合金在恒定温度和剪切速率条件下的静态流变特征，结果表明：PP和PS作为均相纯聚合物，在时间扫描过程中，其黏度均随时间呈线性下降趋势，该现象可归结为材料的热氧降解作用。对非相容PP／PS合金材料进行时间扫描发现，扫描过程中黏度先升高后下降，可分为前期和后期两个阶段，前期相结构在剪切力传递过程中导致合金材料的黏度相对较低，甚至低于连续相纯聚丙烯的黏度，具有明显的瞬态作用特征，时间扫描后期因相结构在稳定剪切条件下引起能量损耗而呈现较高的黏度，但因热氧作用整体趋于下降。

Time sweep investigation of the static rheologieal behaviors of polypropylene （PP）, polystyrene （PS） and their blends were carried out at low shear rates. The viscosity of neat PP and PS decreased linearly with time mainly due to thermal degradation. For the PP/PS alloy, the viscosity increased first and subsequently decreased. The first increase of the viscosity could be attributed to the interlock of the phase structure and the later decrease was for the same reason of the homopolymers.