Tensile deformation behavior of bimodal polyethylene (PE) was investigated by employing coarse-grained (CG) molecular dynamics simulations based on a united atom model. The bimodal PE was modeled by blending two linear polyethylene chains with different molecular weights. The mechanical response and corresponding conformational behaviors of the polymer melt during stretching were recorded as a function of strain under both high and low strain rates. We find that the tensile toughness was enhanced in an additive fashion by increasing the fraction of polymers with high molecular weight in bimodal PE. During elongation, the polymer chain extends and orients itself along the loading direction. Surprisingly, varying the bimodal distribution and the strain rates, the disentanglement does not synergistically follow the tendency of chain expansion and ordering along the tensile direction as the strain is gradually raised, implying that multiple deformation modes might exist during the plastic flow process. The molecular origin of this unique development of the entanglement network in bimodal PE is discussed in detail.

通过使用基于联合原子模型的粗粒（CG）分子动力学模拟，研究了双峰聚乙烯（PE）的拉伸变形行为。通过混合两条分子量不同的线性聚乙烯链来模拟双峰PE。在高应变速率和低应变速率下，聚合物熔体在拉伸过程中的机械响应和相应的构象行为均作为应变的函数进行记录。我们发现，通过增加双峰PE中高分子量聚合物的比例，拉伸韧性以加成方式得以增强。在伸长过程中，聚合物链沿加载方向延伸并定向。令人惊讶的是，改变了双峰分布和应变率，当应变逐渐增加时，解开并不会协同遵循链扩展和沿拉伸方向有序的趋势，这意味着在塑性流动过程中可能存在多种变形模式。详细讨论了双峰PE中纠缠网络这种独特发展的分子起源。