Effect of tetraethoxysilane on the dimensional stability and static bending properties of nanocellulose, tannin, and activated carbon mixed with epoxy resin

Static bending strength and dimensional stability of epoxy composite is an important property for most of the structural applications. Types of filler used with addition of tetraethoxysilane (TEOS) in the epoxy system might improve the properties of the composite. In this research paper, two types of epoxy composites were prepared: the first batch involved epoxy resin mixed with three different fillers; nanocellulose, tannin, and activated carbon at three different doses; 5%, 10% and 15%, while the second batch was a reactive modification using 1%, 2% and 3% doses of (TEOS) as cross-linker agents at 10% dose of each filler. The dimensional stability and static bending properties of epoxy mixed with commercial nanocellulose, tannin, and laboratory-made activated carbon as fillers were investigated. We found that the nanocellulose, tannin, and activated carbon acted as hydrophobic buffer to slow the water absorption at the 10% dose. The thickness swelling was also significantly lower (P < 0.05) for the epoxy mixed with any fillers regardless of the dose. The modulus of rupture (MOR) was also significantly higher (P < 0.05) in epoxy mixed with the 10% dose of nanocellulose and tannin. Overall, the water absorption and thickness swelling were lowest in epoxy mixed with the 10% dose of nanocellulose. The use of the 3% dose of TEOS in epoxy mixed with a 10% dose of tannin gave the highest static bending. The TEOS was only suitable for epoxy mixed with tannin.