DEGRADATION OF STARCH MODIFIED POLYETHYLENE BAGS IN A COMPOST FIELD-STUDY

The degradation of commercially available leaf bags made of polyethylene compounded with ECOSTAR PLUS(R), a starch based additive, was determined after exposure to a passive composting environment during the summer of 1990. The bags were filled with partially composted leaves and yard waste. Half of the bags were buried inside and half on the surface of the pile. One bag from each group plus a control was removed at 14, 28, 42 and 49 days of exposure. The tensile properties, FTIR and UV-vis spectra, differential scanning calorimetry and light microscopy determinations were performed on these samples. The surface bags showed oxidation, loss of starch, lower melting point and embrittleness after 14 days. The buried bags had lower melting points at 14 days and showed oxidation at 28 and 49 days. These results indicate that exposure to daylight had a marked effect in the degradation of the surface bags while the degradation of buried bags may involve other processes.