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Uncommon nonlinear rheological phenomenology in uniaxial extension of polystyrene solutions and melts
Soft Matter ( IF 2.9 ) Pub Date : 2020-03-31 , DOI: 10.1039/d0sm00085j Ruchao Yuan 1, 2, 3, 4, 5 , Jianning Liu 1, 2, 3, 4 , Yangyang Wang 4, 6, 7, 8 , Shi-Qing Wang 1, 2, 3, 4
Soft Matter ( IF 2.9 ) Pub Date : 2020-03-31 , DOI: 10.1039/d0sm00085j Ruchao Yuan 1, 2, 3, 4, 5 , Jianning Liu 1, 2, 3, 4 , Yangyang Wang 4, 6, 7, 8 , Shi-Qing Wang 1, 2, 3, 4
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This study examines nonlinear rheological responses to uniaxial extension of two entangled polystyrene (PS) solutions and two PS melts. Several unusual characteristics are revealed. The pair of the PS solutions have the same number of entanglements per chain (because of the same concentration) but well separated effective glass transition temperatures Tg. When examined at a common effective rate of extension (e.g., the same Rouse–Weissenberg number WiR) and at a comparable distance from their respective Tg, the solution A with lower Tg, examined at a lower temperature, shows stronger stress responses when WiR > 1. At the same test temperature and a common WiR, the solution A is still found to display a stronger stress response than the solution B that is made of the same fraction of parent PS in a second solvent also made of oligomeric PS of higher molecular weight. Finally, there are two features intrinsic to each of the four PS samples. First, at the same WiR they show reduced stress level at a lower temperature. Second, at sufficiently high applied Hencky rates, they show limiting rate behavior, i.e., undergoing the same melt rupture independent of the applied rate. These remarkable rheological responses indicate major theoretical difficulties facing the subject of nonlinear extensional rheology of entangled polymers.
中文翻译：
聚苯乙烯溶液和熔体单轴延伸中的非常规非线性流变现象
这项研究检查了两个纠缠的聚苯乙烯（PS）溶液和两个PS熔体对单轴延伸的非线性流变响应。揭示了几个不寻常的特征。一对PS溶液的每条链具有相同数量的缠结（因为浓度相同），但有效玻璃化转变温度T g相隔甚远。当以共同的有效延伸率（例如相同的Rouse–Weissenberg数Wi R）和距其各自的T g相当的距离进行检查时，在较低温度下检查的具有较低T g的溶液A表现出更强的应力响应当Wi R> 1.在相同的测试温度和相同的Wi R下，仍然发现溶液A的应力响应要比由相同比例的母体PS在第二种溶剂（也是由低聚物PS制成）中制成的溶液B表现出更强的应力响应。较高的分子量。最后，四个PS样本中的每一个都有两个固有的特征。首先，在相同的Wi R下，它们在较低的温度下应力水平降低。第二，在足够高的施加的Hencky速率下，它们显示出极限速率行为，即，独立于所施加的速率经历相同的熔体破裂。这些显着的流变响应表明缠结聚合物的非线性延伸流变学面临的主要理论困难。
更新日期：2020-04-24
中文翻译：
聚苯乙烯溶液和熔体单轴延伸中的非常规非线性流变现象
这项研究检查了两个纠缠的聚苯乙烯（PS）溶液和两个PS熔体对单轴延伸的非线性流变响应。揭示了几个不寻常的特征。一对PS溶液的每条链具有相同数量的缠结（因为浓度相同），但有效玻璃化转变温度T g相隔甚远。当以共同的有效延伸率（例如相同的Rouse–Weissenberg数Wi R）和距其各自的T g相当的距离进行检查时，在较低温度下检查的具有较低T g的溶液A表现出更强的应力响应当Wi R> 1.在相同的测试温度和相同的Wi R下，仍然发现溶液A的应力响应要比由相同比例的母体PS在第二种溶剂（也是由低聚物PS制成）中制成的溶液B表现出更强的应力响应。较高的分子量。最后，四个PS样本中的每一个都有两个固有的特征。首先，在相同的Wi R下，它们在较低的温度下应力水平降低。第二，在足够高的施加的Hencky速率下，它们显示出极限速率行为，即，独立于所施加的速率经历相同的熔体破裂。这些显着的流变响应表明缠结聚合物的非线性延伸流变学面临的主要理论困难。
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