Polymers from renewable resources. IX. Interpenetrating polymer networks based on castor oil polyurethane poly(hydroxyethyl methacrylate): Synthesis, chemical, thermal, and mechanical properties

Abstract

A number of polyurethanes were synthesized by reacting castor oil with hexamethylene diisocyanate, varying the NCO/OH ratio. The polyurethanes were reacted with 2-hydroxyethyl methacrylate ( HEMA) to prepare the interpenetrating polymer networks (IPNs) using benzoyl peroxide as the initiator and ethylene glycol dimethacrylate (EGDM) as the crosslinker. The IPNs are partly soluble in some of the solvents and are less resistant to alkali, but more resistant to acid. The solvent absorption is more pronounced in benzene than in toluene. A novel computerized LOTUS package was used to calculate the kinetic parameters. All the IPNs decomposed with 2-4% weight in the temperature range of to 200°C; 10% weight loss occurs at 300°C and 40% weight loss occurs at 400°C. There is a rapid weight loss from 10 to 90% in the temperature range of 400-500°C. From the kinetic data, it is clear that the degradation process of the IPNs is slower in the temperature range 300-400°C and faster in the temperature range of 440-560°C.