The Mechanical Properties of Epoxy Composites Filled with Rubbery Copolymer Grafted SiO2

Jianing Gao, Junting Li, Brian C. Benicewicz, Su Zhao, Henrik Hillborg, Linda S. Schadler
2012 Polymers  
This study demonstrated a method for toughening a highly crosslinked anhydride cured DGEBA epoxy using rubbery block copolymer grafted SiO 2 nanoparticles. The particles were synthesized by a sequential reversible addition-fragmentation chain transfer (RAFT) polymerization. The inner rubbery block poly(n-hexyl methacrylate) (PHMA) had a glass transition temperature below room temperature. The outer block poly(glycidyl methacrylate) (PGMA) was matrix compatible. A rubbery interlayer thickness of
more » ... rlayer thickness of 100% and 200% of the particle core radius was achieved by grafting a 20 kg/mol and a 40 kg/mol PHMA at a graft density of 0.7 chains/nm 2 from the SiO 2 surface. The 20 kg/mol rubbery interlayer transferred load more efficiently to the SiO 2 cores than the 40 kg/mol rubbery interlayer and maintained the epoxy modulus up to a loading of 10 vol% of the rubbery interlayer. Both systems enabled cavitation or plastic dilatation. Improvement of the strain-to-break and the tensile toughness was found in both systems. We hypothesize that plastic void growth in the matrix is the primary mechanism causing the improvement of the ductility. OPEN ACCESS Polymers 2012, 4 188
doi:10.3390/polym4010187 fatcat:hqsbecbbh5bbfowg4tsuemx2ji