Optimization of biodegradable starch adhesives using response surface methodology

Sago and yucca commercial starches were used in order to evaluate their best possible response adhesive properties. The application of response surface methodology in the optimization of properties was used. A central composite design to evaluate the effect of four independent variables (starch percentage, NaOH percentage, temperature and cooking time) with respect to one response variable (peel strength) was also used. The properties of sago and yucca starches were compared with the properties of corn starch as reference. DSC showed that sago and yucca starches possess similar gelatinization temperatures when compared to corn starch (68.4 °C, 65.7 °C and 69.7 °C, respectively). Adhesion tests indicated that sago and yucca starches presented maximum peel strengths of 125 N/m and 115 N/m, respectively. In this work, the coefficient of determination R2 remained between 0.84 and 0.90; consequently, the quality and effectiveness of the statistical models are considered adequate. These results suggested that sago and yucca starches have potential to be competitive in the global starch market for adhesive applications.