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The Mechanical Properties of Epoxy Composites Filled with Rubbery Copolymer Grafted SiO2
Department of Materials Science & Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
ABB Corporate Research, Forskargränd 7, 72226 Västerås, Sweden
* Author to whom correspondence should be addressed.
Received: 17 December 2011; in revised form: 5 January 2012 / Accepted: 6 January 2012 / Published: 16 January 2012
Abstract: This study demonstrated a method for toughening a highly crosslinked anhydride cured DGEBA epoxy using rubbery block copolymer grafted SiO2 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 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/nm2 from the SiO2 surface. The 20 kg/mol rubbery interlayer transferred load more efficiently to the SiO2 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.
Keywords: toughened epoxy; rubbery interlayer; nanocomposites; RAFT polymerization
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MDPI and ACS Style
Gao, J.; Li, J.; Benicewicz, B.C.; Zhao, S.; Hillborg, H.; Schadler, L.S. The Mechanical Properties of Epoxy Composites Filled with Rubbery Copolymer Grafted SiO2. Polymers 2012, 4, 187-210.
Gao J, Li J, Benicewicz BC, Zhao S, Hillborg H, Schadler LS. The Mechanical Properties of Epoxy Composites Filled with Rubbery Copolymer Grafted SiO2. Polymers. 2012; 4(1):187-210.
Gao, Jianing; Li, Junting; Benicewicz, Brian C.; Zhao, Su; Hillborg, Henrik; Schadler, Linda S. 2012. "The Mechanical Properties of Epoxy Composites Filled with Rubbery Copolymer Grafted SiO2." Polymers 4, no. 1: 187-210.