Effect of the Nanoparticle Functionalization on the Cavitation and Crazing Process in the Polymer Nanocomposites

The nanoparticle(NP)functionalization is an effective method for enhancing their compatibility with polymer which can influence the fracture property of the polymer nanocomposites(PNCs).This work aims to further understand the cavitation and crazing process,hoping to uncover the fracture mechanism on the molecular level.By adopting a coarse-grained molecular dynamics simulation,the fracture energy of PNCs first increases and then decreases with increasing the NP functionalization degree a while it shows a continuous increase with increasing the interaction εpA between polymer and modified beads.The bond orientation degree is first characterized which is referred to as the elongation.Meanwhile,the stress by polymer chains is gradually reduced with increasing the a or the εpA while that by NPs is enhanced.Furthermore,the percentage of stress by polymer chains first increases and then decreases with increasing the strain while that by NPs shows a contrast trend.Moreover,the number of voids is quantified which first increases and then decreases with increasing the strain which reflects their nucleation and coalescence process.The voids prefer to generate from the polymer-NP interface to the polymer matrix with increasing a or εpA.As a result,the number of voids first increases and then decreases with increasing a while it continuously declines with the epA.In summary,our work provides a clear understanding on how the NP functionalization influences the cavitation and crazing process during the fracture process.