Effects of hollow glass microsphere density and surface modification on the mechanical and thermal properties of poly(methyl methacrylate) syntactic foams

Syntactic foams offer low density polymers for insulation and transportation applications with the advantage of having high mechanical properties. In this study, poly(methyl methacrylate) (PMMA) syntactic foams were produced with three different types of hollow glass microspheres (HGMs) as low, medium and high density. It was observed that the density of the syntactic foams was in inverse ratio to the strength properties of the syntactic foams. The lowest measured syntactic foam density was obtained with the addition of high density HGMs into the PMMA matrix without compromising the mechanical properties. Surface coating of HGMs allowed increase in the flexural strength and the impact strength of PMMA syntactic foam by 12% and 17%, respectively, when they were compared with their counterparts with the uncoated HGMs. Addition of HGMs with modified surfaces into PMMA matrix reduced the composite density by 10% with respect to the neat PMMA while had no significant effect on its thermal characteristics.