Effect of process conditions on the properties of castor oil maleate and styrene copolymer produced by bulk polymerization

This work evaluated the influence of process conditions on the chemical characteristics and yield of polymers based on castor oil. Castor oil maleate and styrene copolymers (MACO-Sty) were produced by bulk polymerization using benzoyl peroxide (BPO) and cobalt naphthenate as free radical initiators and reaction accelerators, respectively. The effects of temperature (100 to 140 °C), molar ratio between styrene and castor oil maleate (2:1 to 4:1), BPO concentration (0.10 to 0.20 wt%), and cobalt naphthenate concentration (0.10 to 0.20 wt%) were evaluated on the number average molecular weight (Mn), weight average molecular weight (Mw), dispersity (Đ), molar fraction of styrene in the copolymer, reaction yield, and viscosity of the copolymer. A wide range of molecular weights (Mw from 15,809 to 38,656) could be produced, with dispersity ranging from 2.0 to 4.8, and high yields into copolymers (> 80%). The physical characteristics ranged from resins of low viscosity (1.583 Pa s) to solid polymers.