Polymethyl Methacrylate/Polypropylene Blends Loaded with Graphene and Clay: Morphology, Mechanical Properties and Thermal Stability

Abstract

In the research described here immiscible polymer blends based on amorphous poly(methyl methacrylate) (PMMA) and semi-crystalline polypropylene (PP) were produced via a melt-mixing method. The effects of the addition of graphene and clay nanoparticles on the compatibility and properties of the blends were investigated. Scanning electron microscopy results showed that the neat blends at all compositions were severely phase separated and a droplet-in-matrix morphology was attained. Introduction of graphene and clay caused the compatibility of the blends to be highly enhanced and, thus, a finer and more uniform morphology was obtained for the nanocomposites. Based on the morphology results, it was found that graphene had more affinity toward the PP phase and clay was more compatible with PMMA. This hypothesis was further proved via mechanical analysis and thermogravimetric analysis (TGA) results. The toughness of the neat blends was increased upon increasing the PP content; however, it was reduced for all the nanocomposites relative to the blend of the same polymer composition. The thermal stability of the blend at a composition of 70/30 PMMA/PP was improved via addition of clay and graphene. The first stage of degradation (PMMA) was shifted to higher temperatures once clay was added to the system while the second stage of degradation (PP) was impeded upon addition of graphene.