Silica Microparticles in PMMA

1. Structure Property Relationships In Interface-Coupled Nanocomposites I Chemisorption-Unaggregated Physisorption-Unaggregated Physisorption-Aggregated monomer 25 C monomer Filler Suspension Aggregated 24 h Silica Microparticles in PMMA Guru Ragan, Tingtai Guo, James E. Mark and Dale W. Schaefer University of Cincinnati UNICAT: Jan Ilavsky and Pete Jemian Chemisorption Physisorption Dispersed Aggregated Prepared from Silica Suspension Prepared from Dry Silica Powder Reactive Moiety Suspen- sion Randomly Dispersed Polymer Matrix– Poly(methyl acrylate) [PMA] • 3-(Trimethoxysilyl)propyl methacrylate (TPM) J. M. Jethmalani and Warren T. Ford, Chem. Mat. 8, 2138 (19960 3-Chloropropyltrimethoxysilane (CP) UNICAT USAX Results Mechanical Properties Filler content 35 wt% Chemical Physical aggregated dispersed UNFILLED Conclusion Mechanical Properties Results • PMA / CP – silica composites showed a moderate increase, not significant, and the • extensibilities are essentially those of the unfilled elastomer. As expected, the physical • interactions between the CP groups and the PMA matrix were much weaker than the • covalent bonds that strengthen the PMA / TPM – silica composites. • This is, of course, consistent with the view that these deactivated filler particles have no • reinforcing capacity and merely contribute to the void content of the material. • The properties are not improved if there is only poor or occasional bonding of the • elastomer to the filler. In the absence of such bonding, Pre aggregation does not improve • the properties. • Mechanical properties increased dramatically • good dispersions of reinforcing filler particles without completely • eliminating their aggregation into larger structures • the methacrylate groups of the TPM being chemically bonded to • the polymer matrix. PMA / TPM – silica Moderate increase in properties, not significant - the extensibilities are essentially those of the unfilled elastomer - the physical interactions between the CP groups and the PMA matrix were much weaker PMA / CP – silica Acknowledgements The UNICAT facility at the Advanced Photon Source (APS) is supported by the Univ of Illinois at Urbana-Champaign, Materials Research Laboratory (U.S. DOE, the State of Illinois-IBHE-HECA, and the NSF), the Oak Ridge National Laboratory (U.S. DOE under contract with UT-Battelle LLC), the National Institute of Standards and Technology (U.S. Department of Commerce) and UOP LLC. The APS is supported by the U.S. DOE, Basic Energy Sciences, Office of Science under contract No. W-31-109-ENG-38.