Title: Crazing of Nanocomposites with Polymer-Tethered Nanoparticles Show Chinese title

Title: 聚合物接枝纳米颗粒的纳米复合材料的银纹现象

Abstract: The crazing behavior of polymer nanocomposites formed by blending polymer grafted nanoparticles with an entangled polymer melt is studied by molecular dynamics simulations. We focus on the three key differences in the crazing behavior of a composite relative to the pure homopolymer matrix, namely, a lower yield stress, a smaller extension ratio and a grafted chain length dependent failure stress. The yield behavior is found to be mostly controlled by the local nanoparticle-grafted polymer interfacial energy, with the grafted polymer-polymer matrix interfacial structure being of little to no relevance. Increasing the attraction between nanoparticle core and the grafted polymer inhibits void nucleation and leads to a higher yield stress. In the craze growth regime, the presence of grafted chain sections of 100 monomers alters the mechanical response of composite samples, giving rise to smaller extension ratios and higher drawing stresses than for the homopolymer matrix. The dominant failure mechanism of composite samples depends strongly on the length of the grafted chains, with disentanglement being the dominant mechanism for short chains, while bond breaking is the failure mode for chain lengths greater than 10Ne, where Ne is the entanglement length. Show Chinese abstract

Abstract: 由接枝纳米颗粒与纠缠聚合物熔体混合形成的聚合物纳米复合材料的银纹行为通过分子动力学模拟进行研究。 我们关注复合材料相对于纯均聚物基体的银纹行为的三个关键差异，即较低的屈服应力、较小的伸长比以及接枝链长度相关的断裂应力。 发现屈服行为主要由局部纳米颗粒接枝聚合物界面能控制，而接枝聚合物-聚合物基体界面结构则几乎无关。 增加纳米颗粒核心与接枝聚合物之间的吸引力会抑制空洞成核并导致更高的屈服应力。 在银纹生长阶段，含有100个单体的接枝链段改变了复合样品的机械响应，使其伸长比更小且拉伸应力更高，相比于均聚物基体。 复合样品的主要断裂机制强烈依赖于接枝链的长度，对于短链而言，解缠绕是主要机制，而对于链长超过10Ne的链（其中Ne是纠缠长度），断裂是主要的失效模式。