METHODOLOGY PROPOSED FOR THE EVALUATION OF THE DEGRADABILITY OF PLASTICS THROUGH COMPOSTING

The changes in the regulations regarding solid waste management in Mexico City during 2009 and 2010 promoted the use of oxo-biodegradable plastic bags. These kind of materials can be biodegraded after oxidation by temperature, UV radiation, friction or a combination of them. The standard ASTM method (5338) to asses biodegradability of plastics requires the use of mature compost, in closed reactors with a constant flow of air and a temperature of 58 degrees C. This work assessed the feasibility of testing degradability of oxo-biodegradable plastic films in a controlled composted process, which uses organic waste and local environmental conditions. The system, built in 200 L reactors, showed the feasibility to compost oxo-biodegradable plastics. After 45 days the films showed degradation, assessed by fragmentation, a decrease in elongation at breaking and and increase in the carbonyl index. This method is an alternative to evaluate degradability of these kind of materials, which can help to accomplish the requirements of the regulations developed in Mexico City.