Thermal, mechanical and biodegradation properties of pure, epoxidized and methoxylated castor oil based polyurethane

Abstract

A series of biodegradable polyurethane (BIOU) elastomers were obtained by chain extension of polyurethane (PU) prepolymer with the addition of castor oil (CAO), epoxidized CAO (ECAO) or methoxylated CAO (MCAO). The BIOU elastomers obtained were characterised by Fourier transform infrared, scanning electron microscopy, differential scanning calorimetry and tensile tester. The melting peak of BIOU became undetectable with an increase in the content of the chain extender regardless of its type. Some BIOU films, including BIOU-CAO16wt%, BIOU-ECAO16wt% and BIOU-MAO16wt%, showed elastomeric properties with higher tensile strength than pure PU. However the elongation at break and hardness of samples decreased with CAO, ECAO and MCAO content. The biodegradation was also measured by the modified Sturm test method of the BIOU films in a cultured medium with Pseudomonas aeruginosa E7 and Lysobacter soli LW1-1 strains at 37°C. As the increasing three types of chain-extenders the degree and rate of biodegradation of BIOU increased as compared with pure PU. But even then the biodegradability of BIOU by both the strains did not exceed 26% during the modified Sturm test for 31 days.