Submitted to: Polymers and the Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 2, 2004
Publication Date: April 1, 2004
Citation: Shogren, R.L., Petrovic, Z., Liu, Z., Erhan, S.Z. 2004. Biodegradation behavior of some vegetable oil-based polymers [abstract]. Polymers and the Environment. 12(3):492351:173-178. Interpretive Summary: Many new vegetable oil-based plastics have been developed recently but there is little information available on the potential of these to biodegrade in soil or other environments. It was found that films made from cured soybean, linseed and tung oils did biodegrade in soil, with tung oil being the slower of the three. Resins made from modified (epoxidized) soybean oil and amine hardeners were resistant to biodegradation while those hardened with organic acids did biodegrade. Polyurethane plastics made from soy oil-based polyols were not biodegradable in soil. Thus, many of the soybean oil-based resins would be suitable for durable applications such as appliances or vehicle parts where resistance to biodegradation would be desirable. This information would be useful to industrial processors of soybeans, companies which make and use plastics and other academic and government researchers.
Technical Abstract: The potential biodegradability of several vegetable oil-based polymers was assessed by respirometry in soil for 60-100 days at temperatures of 30-58 degrees C. Films of soybean oil and linseed oil which were oxidatively polymerized (Co catalyst) on a kraft paper support were 90-100% mineralized to CO2 after 70 days at 30 degrees C. Mineralization of polymerized tung oil to CO2 was much slower than soy or linseed oils. Mineralization of epoxy resins made from epoxidized soybean oil (ESO) and aliphatic dicarboxylic acids was rapid while mineralization of similar resins made with a triacid (citric) was slower. There was no significant degradation of polyamine/ESO resins after 100 days to 58 degrees C. Mineralization of the available carbon in vegetable oil polyurethanes and cationically polymerized ESO was less than 7.5% after 70 days at 30 degrees C and 25 days at 55 degrees C compared to 100% for soybean oil. From these results, it appears that triglycerides highly cross-linked with non-degradable linkages are not biodegradable to a significant extent while triglycerides cross-linked with hydrolysable bonds such as esters remain biodegradable.