Lightweight polyester composites via nanoreinforced syntactic foams

Syntactic foams and their reinforcement with cellulose nanocrystals (CNC) in a thermosetting polyester resin (PR) matrix were studied in order to provide a pathway for lightweight composites for automotive applications with enhanced performance including thermomechanical properties and water uptake. A novel method for coating hollow glass spheres (HGS) with CNC was developed. Various combinations of functionalized CNC and surface modified HGS were studied to determine interactions between the two materials. Surface analysis techniques indicated that CNC were successfully deposited onto the HGS surface and remained at the surface after compounding with PR. Dynamic mechanical analysis of composites samples indicated a 30% increase in high temperature storage modulus between CNC coated HGS samples and uncoated HGS samples. Shifts in tan(delta) peak intensity and beta-relaxation temperature also indicated an increase in interphase volume around CNC coated HGS as compared to uncoated HGS samples. Coating HGS with CNC reduced the maximum water adsorption by as much as 40% indicating the potential for this material system in high moisture environments.