A theory-based model on the effect of volume fraction to the viscosity of silica filled epoxy composites was investigated. This model was used to compare to the experimental data.
The experimental results were closed to the theoretical results. There were no correlation between different particles sizes for 75, 150, and 300J.Lm of silica with viscosity of epoxy
composites; this may be due to the wider range of particle sizes resulted from particle agglomeration breaks up into small particle. The viscosity results for treated silica are similar with untreated silica, this maybe because the treatment has not improved the surface area of the filler due to the wider range of particles. Study on the mechanical properties such as flexural strength and modulus with scanning electron microscopy results were done. The pure epoxy exhibited the highest flexural strength than epoxy composites filled at 5 and 10 vol. %, this is because the porosity influences on the durability of samples for different particle sizes. Silica filled epoxy composite at 5 vol.% for particle size of 75J.Lm exhibited higher flexural strength than the epoxy composite filled at 10 vol.% because the later had more porosity. Flexural modulus results for epoxy composites filled with 75J.Lm increased with the volume fraction, this is because the particle size distribution of 75J..Lm is a bit narrower than 150 and 300J..Lm particles. Viscosity is dependent on the volume fraction. The viscosity increased with the volume fraction, because of the relatively high correlation, 0.774. Viscosity decreased with the increasing of the speed, this indicated that all the epoxy composites behaved non-Newtonian
behavior.
