Abstract
Effects of sunshine duration and precipitation on the degradation of poly (L-Lactic acid) (PLA) have been investigated by applying multiple regression analysis. The analysis showed that the tensile strength of PLA exposed to outdoor can be described by kW and k'U, where k and k' are rate constants of hydrolysis and photodecomposition, respectively, and W is precipitation, U is sunshine duration. The contribution of k'U to the degradation of PLA was 1.5 times of kW. Hydrolysis and photodecomposition tests for PLA were also carried out in laboratory. The activation energy of hydrolysis and photodecomposition were 81.1kJ/mol and 66.9kJ/mol, respectively. These results suggested that the degradation caused by solar radiation was prominent than that by precipitation.
