Mechanical and Thermal Properties of Castor Oil-Based Polyurethane Adhesive: Effect of TiO2 Filler

Polyurethane (PU) production with the use of vegetable oils is greatly appreciated by researchers due to their low cost, easy availability, and nontoxic nature. The addition of TiO2 in castor oil-based PU adhesive led to a remarkable enhancement in its mechanical and chemical resistance, an increase in T-g value, and the adhesion. TGA analysis was done to study the thermal stability of prepared adhesive. The adhesive was also characterized by differential scanning calorimetry (DSC) and FT-IR spectroscopy. Influence of various factors such as the NCO/OH molar ratio, hydroxyl value of polyols, and the amount of filler on the properties of adhesive were studied in detail. The adhesive with a mole ratio of NCO/OH equaling to 1.2, filled with 3 wt% TiO2, was found to be much better than the commercial adhesive used for bonding wood, when tested for single lap shear strength in various environmental conditions.