Abstract Knowing the flow parameters of a polymer melt under steady state condition is required to assess the performance of the material in die and mold design. Often, however, this is not sufficient for a full understanding of the polymer processing behavior, and information on the linear and non-linear viscoelastic behavior is needed. In this paper, the non-linear viscoelastic behavior of a polymer under shear flow has been investigated by measuring the stress response when a cyclic oscillating shear rate in a capillary rheometer is applied. The time-dependent wall shear stress has been decomposed into in-phase viscous and elastic components. A model to interpret the experimental results is presented and applied to a well-characterized polystyrene and two polyethylenes with similar rheology but different molecular structure (HDPE and LLDPE). The relevant characteristics resulting from the model, such as the generalized elastic and viscous modulus under shear, are compared and discussed.

中文翻译：

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用于聚合物熔体的振荡剪切毛细管流变仪 (OSCAR)

摘要 了解稳态条件下聚合物熔体的流动参数是评估材料在模具设计中的性能所必需的。然而，这通常不足以全面了解聚合物加工行为，还需要有关线性和非线性粘弹性行为的信息。在本文中，通过测量在毛细管流变仪中应用循环振荡剪切速率时的应力响应，研究了聚合物在剪切流下的非线性粘弹性行为。随时间变化的壁面剪应力已分解为同相粘性和弹性分量。提出了一个解释实验结果的模型，并将其应用于表征良好的聚苯乙烯和两种具有相似流变性但分子结构不同的聚乙烯（HDPE 和 LLDPE）。