Dispersion of Glycidyl POSS-modified Silica Nanoparticles in Epoxy

Hypothesis:

 Proper dispersion of silica nanoparticles in epoxy resin leads to promising improvements in mechanical and thermal properties of nanocomposite. A comparative study of dispersion between GPOSS-modified silica nanoparticles and neat silica nanoparticles shows a measure of GPOSS efficiency in dispersion of silica nanoparticles.

Nanoparticle dispersion was investigated through polymer cumulative behavior such as rheological parameters and viscosity measurement. Using the ultrasonic technique, a pre-dispersed compound containing 20 %wt silica nanoparticles and GPOSS was first prepared. The pre-dispersed compound was then diluted to a final percentage of silica nanoparticles of 2, 5 and 10 %wt. An atomic force microscope (AFM) was also used to further investigate the dispersion of silica nanoparticles in the pre-dispersed compound.

According to the rheometry test results, all samples with pre-dispersed compound showed lower viscosity than their corresponding counterparts. It seems that the GPOSS is able to lower the composition viscosity through minimizing interfacial interactions between silica nanoparticles as well as possible interactions between epoxy chains and silica nanoparticles. In comparison with the sample prepared without pre-dispersed compound, the viscosity of the composition containing 10% (wt) silica nanoparticles was drastically reduced, i.e. from 246000 cP to 39000 cP. AFM surface images of the pre-dispersed compound represent the presence of particles with a statistical accuracy of 95% in the range of 12 nm to 20 nm, proving that the silica nanoparticles are well dispersed in GPOSS. The interesting finding of this study was that a pre-dispersed compound of GPOSS and silica nanoparticles not only improves the dispersion of silica nanoparticles and hence the final mechanical properties, but also improves the easy use through reducing the viscosity of the epoxy-based composition.