An energy‐based strategy to predict the thickness and content of randomly oriented nanolayers aggregates/agglomerates in thermoplastic polymer nanocomposites: Experimental and analytical approaches

Abstract

In this study, the formation of clay nanolayer clusters inside the high‐density polyethylene (HDPE) matrix was evaluated using a specific strategy based on energy equilibrium in the melt mixing stage. Furthermore, the formed interphase region around nanoparticle domains was precisely evaluated considering the molecular structure of the matrix and linear variation of the physical/mechanical characteristics. The obtained results were used in a developed analytical model to predict the tensile modulus of the nanocomposite system containing randomly oriented nanoparticle domains. The domains consisted of exfoliated, intercalated, or aggregated/agglomerated nanolayers placed in different excluded volumes as the components of an equivalent box model. Different comparative studies were performed using the obtained data from different tests, applied to the prepared HDPE/clay nanocomposite samples, and other data from the literature. It was found that the confrontation between the exerted dispersion energy, by the mixer, and interparticle cohesion energy defined the thickness and physical/mechanical characteristics of the final aggregates/agglomerates in a nanocomposite. Though, the size and content of aggregates/agglomerates increased with the content of initially added nanoparticles. Consequently, the random orientation of each nanoparticle domain and formation of the polymer/particle interphase were proved to have determinative impacts on the mechanical properties of the system.