Effect of Nanoclay on the Mechanical Properties of PMMA/Clay Nanocomposite Foams

Abstract

In this study, the effects of nanoclay on the mechanical properties of poly(methylmethacrylate) (PMMA)/clay nanocomposite foams are investigated. Intercalated PMMA/clay nanocomposites have been prepared through a solvent co-precipitation method. PMMA/clay nanocomposites with only 0.5 wt% of well-dispersed montmorillonite nanoclay showed considerable improvement of mechanical properties; specifically in elastic modulus, tensile strength, and elongation at break. However, with an increased load of clay in the nanocomposite, the mechanical properties decreased due to the agglomeration of excessive nanoclay. Microcellular foams have been processed with PMMA/clay nanocomposite material using a subcritical gas foaming method. When a short foaming time is used, the increased amount of nanoclay induced a greater amount of heterogeneous nucleation during the foaming process and therefore decreased the density of the foam. In contrast, when a longer foaming time is used, foam density increased with a larger nanoclay load due to the higher diffusivity coefficient of CO2 blowing agent. Nanoclay, as a nucleation agent and reinforcement filler, changed the foaming behavior and mechanical properties of the PMMA microcellular foams. The microcellular foams made of PMMA/clay nanocomposite with 0.5 wt% exhibited an optimized mechanical response under tensile experiments. It is observed that the mechanical properties of nanocomposite foams are greatly related to the mechanical properties of unfoamed material and foam density. The nanoclay dispersion quality is a very important factor for the mechanical properties of both foamed and unfoamed polymer/clay nanocomposites.