Abstract
Degradation of biodegradable poly L-lactic acid was studied with alkaline hydrolysis and hot water. In the alkaline hydolysis, the sample shows a remarkable weight loss and at the same time the shape is changed with time. Koch curve was applied as a model of surface boundary for the degraded material. In the degradation with hot water, cracking and fragmentation occurs preferentially in the initial stage of weight loss. The change in shape of the degraded PLLA was analyzed by measuring box counting dimension and comparing the dimension with fractal image. The spider tree model of fractal figure is useful for cracking of PLLA. The overall cracks has a dimension of about 1.5. At the dimension of 1.7, the cracks form network and samples are pulverized. In conclusion, this treatment is useful for plastic garbage of PLLA.
