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Abstract
Cassava starch was cyanoethylated to different degrees of substitution (DS) and then used in adhesive preparations. The adhesives were used in bonding wood substrates and the adhesive strength of the bonded substrates was evaluated using a tensometer. The effects of the DS, solids content, pH and moisture on adhesive strength were investigated. The adhesive strength increased with increasing DS; with respect to the percentage solids, it increased to a maximum and then decreased again; with pH, it showed a minimum at a neutral pH; while it decreased with length of exposure to saturated moisture conditions. The experimental data were subjected to regression analysis to find the best fitting models. The results showed that the adhesive strength varied polynomially with DS (R 2 = 0.97), pH (R 2 = 1.0), percentage solids content (R 2 = 0.94), and exponentially with the length of exposure to saturated moisture conditions (R 2 = 0.96). Cyanoethylation significantly enhanced the adhesive property of starch (p < 0.05) and the cyanoethyl starch adhesives were found effective for bonding wood. However, cyanoethyl starch adhesive is not suitable as structural adhesive in a high moisture environment. The performance of cyanoethyl starch adhesive was compared with two commercial adhesive pastes.