Comparative studies of castor and hydrogenated castor oil urethane/PMMA semi and full interpenetrating polymer networks

Semi and full interpenetrating polymer networks (IPNs) of castor oil and hydrogenated castor oil urethane and poly(methyl methacrylate) were synthesized by the sequential mode of synthesis. These IPNs were characterized for their physicomechanical properties, swelling properties, and thermal behavior. The glass transition temperatures (T(g)s) were determined by differential scanning calorimetry (DSC). The variation in the blend ratio resulted in drastic changes in the % elongation at break, whereas, nominal changes were observed in the tensile strength values, Interestingly, the semi-IPNs exhibited higher tensile strength and density but lower elongation than the corresponding full IPNs. From glass transition temperature measurements it was observed that full-IPNs showed single T-g value, whereas, semi (IPNs exhibited two T-g values corresponding to their respective homopolymers. In the case of swelling behavior, the castor oil urethane and PMMA IPNs offered relatively more solvent resistance than hydrogenated castor oil /PMMA.