Interpenetrating polymer networks based on castor oil, XVIII

Castor oil—a renewable resource—is abundantly grown in tropical countries. It is a triglyceride of glycerol and ricinoleic acid containing hydroxyl functionality. These hydroxyls were reacted with 4,4′‐diphenyl methane diisocyanate to form prepolyurethanes with different NCO/OH ratios. The prepolyurethane was swollen in ethyl methacrylate monomer containing 1% ethylene glycol dimethacrylate as crosslinker by radical polymerization initiated with benzoyl peroxide. The polyurethane/poly(ethyl methacrylate) interpenetrating polymer networks (IPNs) PU/PEMA were obtained as tough films by casting into glass molds. These IPNs were characterized by their resistance to chemical reagents, optical properties (% transmittance), thermogravimetric analysis and mechanical properties, dynamic storage modulus (ϵ′), loss modulus (ϵ″), and loss tangent (tan δ) by dynamic mechanothermal analysis, morphology by scanning electron microscopy, and dielectric properties (σ, ϵ′, ϵ″ and tan δ) at different temperatures.