The effects of silane-grafted silica nanoparticle (SNP) as inorganic low-profile additives (ILPA) on the volume shrinkage characteristics for low-shrink vinyl ester resins (VER) during the cure at 120oC were investigated. The SNPs with diameters of 15 nm and 30 nm were synthesized by size-controllable hydrolysis of elemental silicon, and ?-methacryloxy propyl trimethoxy silane (MPS) bearing one unsaturated C=C double bond at one end was employed for the surface treatment of the SNP. The number of silane coupling agents grafted on the silica surface and the final conversion of silanol groups at the SNP for the surface-treatment reaction have been characterized by Fourier transform infrared spectroscopy (FTIR). Depending on the diameter (15 and 30 nm) and the content of MPS-silica (1 to 15 wt%) added, the MPS-silica could lead to a reduction of cyclization reaction for VER resins during the cure, and the microgel structure during the cure would be less compact, and, in turn, be favorable for the decrease of intrinsic polymerization shrinkage after the cure. It was found that with the adjustment of self-synthesized VER molecular weight to prevent the phase separation of the Styrene(St)/VER/MPS-silica ternary system prior to cure, adding a higher content of nano-scale MPS-silica as an ILPA in the VER resin may result in a lower volume shrinkage after cure, and adding 15% of either 15 nm or 30 nm diameter of MPS-silica can even lead to a volume expansion of about 1%. Also, adding a smaller diameter of nano-scale MPS-silica can cause a lower volume shrinkage after the cure.

Effects of silane-grafted silica nanoparticle on the volume shrinkage in the cure of vinyl ester resins

246th National Meeting (2013)

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