轻度磺化聚苯乙烯与聚苯乙烯共混物的流变性能表征

Rheological Characterization of Lightly Sulfonated Polystyrene Ionomers and Its Blends with Precursor Polystyrene

采用 DSR-2 0 0动态应力流变仪研究了磺化度为 0 .98% (摩尔分数 )的轻度磺化聚苯乙烯 (SPS)离聚物及其锌盐 (Zn SPS)与聚苯乙烯 (PS)的共混物 (PS/SPS,PS/Zn SPS)的流变性能 .由于离聚物中离子聚集的物理交联作用 ,使其流变性能与 PS相比有明显差别 .动态频率实验结果表明 ,所有样品均可采用时温等效处理 .另外 ,在与分子链运动相关的低频区 ,由于离子聚集的作用使得离聚物的模量远大于 PS的模量 .离聚物在稳态剪切作用下 ,由于离子聚集的破坏而表现出明显的屈服现象 ,并能用 Utracki的屈服应力公式表征其屈服应力和零切粘度 .此外 ,离聚物的屈服现象还与温度相关 .由于动态和稳态实验分别测试离子聚集存在和破坏的不同材料状态 ,因此对离聚物无法应用 Cox-Merz规则 .动态和稳态实验结果均表明 ,PS/SPS和 PS/Zn SPS的性能与组成的变化规律不同 。

The rheological properties of 0 98%(molar frac`tion) lightly sulfonated polystyrene ionomer(SPS), zinc neutralized SPS(ZnSPS) and their blends with precursor polystyrene(PS) are reported. It is found that the rheological properties of ionomers and their blends are quite different with PS, due to the ionic aggregates acting as physical cross links in ionomers. Using linear viscoelasticity data, the time temperature superposition can be conducted to all samples. Differences are also found in the low frequency region of linear viscoelasticity data. Correlated with the relaxation of polymer chains, the moduli of ionomers are higher than those of PS due to the effect of ionic aggregates. In the steady shear test, typical yield phenomena can be found in the apparent viscosity curves of ionomers, which are also resulted from the ionic aggregates. Utrackis formula for yield stress fits the apparent viscosity data properly and the yield stress and zero shear viscosity of ionomers are obtained. It is also found that the yield phenomena of ionomers are disappeared above certain temperature. The Cox Merz rule is invalid for ionomers, due to the complex viscosity and apparent viscosity characterizes at different state of ionomer fluid, with ionic aggregates and breakdown of ionic aggregates, respectively. Finally, the different relationship between blends composition and rheological properties indicate that different ionic aggregate structure or ionic association exists in the PS/SPS and PS/ZnSPS blends.