Nanofillers Regulated Fracture Behavior Of Elastomer-based Composites:Insights From Molecular Dynamics Simulation

Elastomer-based composites have been widely used in the national economic production and become the key research direction of materials science due to its excellent comprehensive properties,and nanofillers is the key to improve the properties of elastomer matrix materials.However,it is often seen that the elastomer material fails due to fracture in industrial and engineering applications.Therefore,it is very crucial to understand the fracture mechanism of the elastomer-based composites on the molecular level.Focused on the topic of fracture behavior of elastomer-based composites and started from the relationship between microstructure and macro fracture behavior,this work adopts the method of molecular dynamics simulation,and the research is carried out in the following two aspects:(1)The effect of the nano filler shape and size on the fracture behavior of elastomer-based compositesThe effect of the shape and size of nanofillers on it has been investigated in details by adopting a coarse-grained molecular dynamics simulation.The results showed that the rod filler system has better fracture performance than the sheet filler and sphere filler system.By calculating the stress contribution of matrix chains and nanofillers,the stress borne by matrix chains gradually decreases with the increase of nanofiller size for sphere fillers and sheet fillers while it is nearly same for rod fillers;however,the stress borne by sphere filler is gradually reduced with the nanofiller size while it borne by rod fillers and sheet fillers rises.In addition,the voids prefer to nucleate in the matrix because of the strong interfacial interaction.This work could provide some further understanding how the nanofiller shape affects the fracture properties of elastomer-based composites.(2)The effect of the nanoparticle(NP)functionalization degree ? and interaction ?pA on the fracture behavior of elastomer-based compositesThe nanoparticle(NP)functionalization is an effective method to improve the dispersion of nanoparticles in polymer and enhance the fracture property.By adopting a coarse-grained molecular dynamics simulation,we found that the optimal fracture performance was achieved with the medium NP functionalization degree ? and high interaction ?pA.Meanwhile,the percentage of stress by polymer chains is gradually reduced with increasing the NP functionalization degree ? and interaction ?pA while it by NPs is enhanced,and the voids prefer to generate from the polymer-NP interface to the polymer matrix.our work provides a clear understanding how the NP functionalization influences the cavitation and crazing process during the fracture process.