Effect of functionalization on the elastic behavior of graphene nanoplatelet-PE nanocomposites with interface consideration using a multiscale approach

Abstract

The present paper is focused on developing and using a multiscale approach to investigate the effect of functionalization of graphene with carboxyl ([sbnd]COOH) group on the overall elastic properties of graphene nanoplatelet (GNP) -reinforced polyethylene nanocomposites, considering the interfacial effect. The current study involves three aspects. First, MD simulations are performed at the nanoscale to evaluate the elastic properties of pristine and functionalized graphene, polyethylene matrix, and the single-graphene-reinforced nanocomposites. Next, the obtained elastic properties of the graphene nanocomposites and its different constituents are used to characterize its interfacial region utilizing rule-of-mixtures in a nanoscale equivalent-continuum model. Third, a three-phase micromechanical model (i.e., PE matrix reinforced with two-phase reinforcement, containing pristine/functionalized GNPs and its interface) is used to scale up the properties of the nanocomposite. The results reveal that, although the functionalization of graphene degrades its elastic modulus, it improves the interfacial modulus of the resulting nanocomposite. Further, depending upon the aspect ratio of GNPs, functionalization may either result in enhanced elastic properties (except out-of-plane shear modulus) of GNP-nanocomposites in the interface-dominant region (i.e., aspect ratios in the range of 0.0015–1.0) or degrade these properties in the graphene-dominant region (i.e., aspect ratios lower than 0.0015). © 2019