The transient uniaxial elongational viscosity for binary blends composed of polypropylene (PP) and low-density polyethylene (LDPE) was evaluated. A strain hardening behavior is detected for the blends, although LDPE is a dispersed phase. This behavior is attributed to LDPE dispersion deformation; the LDPE forms rigid fibers because of strain hardening. Rheological properties are calculated numerically by the Phan–Thien Tanner model by assuming a symmetric geometry with a periodic structure. Based on the simulation, we propose an appropriate LDPE to modify the processability of PP, for which the strain hardening in the elongational viscosity is required. Transient elongational viscosity for polypropylene (PP)/low-density polyethylene (LDPE) blends was evaluated. Because deformed LDPE droplets act as rigid fibers due to its strain hardening, the blends show a strain hardening behavior. The growth curves are, however, affected by their viscosity ratio. These behaviors are calculated by the Phan–Thien Tanner model by assuming a symmetric geometry with a periodic structure. Based on the simulation, we propose an appropriate LDPE to modify the processability, at which the strain hardening in the elongational viscosity is required.

中文翻译：

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PP/LDPE共混物瞬态拉伸粘度的实验和数值研究

评估了由聚丙烯 (PP) 和低密度聚乙烯 (LDPE) 组成的二元共混物的瞬态单轴拉伸粘度。尽管 LDPE 是分散相，但检测到共混物的应变硬化行为。这种行为归因于 LDPE 分散变形；由于应变硬化，LDPE 形成刚性纤维。通过假设具有周期性结构的对称几何形状，流变特性由 Phan-Thien Tanner 模型进行数值计算。基于模拟，我们提出了一种合适的 LDPE 来改进 PP 的加工性能，为此需要在拉伸粘度中进行应变硬化。评估了聚丙烯 (PP)/低密度聚乙烯 (LDPE) 共混物的瞬态拉伸粘度。由于变形的 LDPE 液滴由于其应变硬化而充当刚性纤维，共混物表现出应变硬化行为。然而，增长曲线受其粘度比的影响。这些行为是由 Phan-Thien Tanner 模型通过假设具有周期性结构的对称几何形状来计算的。基于模拟，我们提出了一种合适的 LDPE 来修改加工性能，在该加工性能下需要拉伸粘度的应变硬化。