Silica Microparticles in PMMA

1
Structure Property Relationships In
Interface-Coupled Nanocomposites I
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
Randomly Dispersed
Suspen- sion
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.