| 摘要 |
PURPOSE: To provide a method for simply and easily improving the modules of elasticity of a biodegradable resin, in order to apply the resin as a casing, etc., of electronic equipment because most of electrical appliances are discarded as incombustible refuses when disposal and then the use of a biodegradable resin is proposed, but inferior in heat resistance. CONSTITUTION: For example, a molded product of polylactic acid is subjected to aging at a temperature not lower than the glass transition temperature of the polyactic acid +15°C and humidifying conditions of >= 60% relative humidity. Thereby, the modulus of elasticity can be improved to, e.g. 107 Pa to 109 Pa in a short time. The molded product without causing the deformation even in aging tests, e.g. at 80°C and 80 RH% for 100 h can be obtained by improving the modulus of elasticity.
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