Control of degradation rate of biodegradable polymers by corona discharge treatment

Effects of corona discharge treatment on the degradation rate of poly(L-lac tic acid) (PLA) and poly (epsilon -caprolactone) (PCL) have been investigat ed. The treatment introduced oxygen containing functional groups onto the s urfaces of PLA and PCL. The contact angles of these polymers decreased by c a. 30 degreesC, indicating an increase in hydrophilicity on the polymer sur faces. The composting degradation tests were carried out for both treated a nd untreated PLA and PCL. The treatment depressed the degradation of PLA, w hile it promoted the degradation of PCL. The affinity between microorganism s (general bacteria, actinomycetes, and fungi) and the polymer surfaces hav e also been estimated by a film-contacting method. The results showed that the treatment decreased the affinity for PLA; on the contrary, it increased the affinity for PCL.