Effect of functionalized process and CNTs aggregation on fracture mechanism and mechanical properties of polymer nanocomposite

There is no doubt about the importance of the mechanical properties of polymer nanocomposite reinforced by carbon nanotubes (CNTs) in terms of the exclusive characteristics of both polymer and CNTs. The mechanical performance of carbon nanotubes/polymer nanocomposite (CPNC) depends on several uncertainties such as CNTs' structural defects and covalent bonds created during functionalized process, CNTs' distribution, curvature, waviness, aggregation, and polymer net properties. To cover all of the mentioned effective parameters, a multiscale method is defined in which CNTs' structure and interfacial phase are studied in a nanoscale model and CNTs' distribution, curvature, and aggregation are studied in a microscale model. According to the neat polymer's properties, both increase and decrease in CNTPN's strength are possible by variations in CNTs curvature, waviness, distribution, and aggregation. Moreover, in CNTs' functionalization process, CNTPN's ultimate strength and material brittleness are increased and decreased, respectively. But, Young's modulus of nanocomposite is decreased according to the presence of CNT's structural defects created during the functionalization process. Additionally, the improving effect of functionalization process is significantly decreased by increasing the curvature of CNTs, and the functionalized CNTs polymer nanocomposite's (FCPNC) ultimate strength is close to the intact CNTs polymer nanocomposite's (ICPNC's) strength properties. CNTs' aggregation has also an adverse effect on Young's modulus and changes the fracture mechanism.