Electrical properties of heat‐treated polylactic acid

Abstract

Abstract Polylactic acid (PLA), a biodegradable plastic, has excellent electrical insulation properties at temperatures ranging from room temperature to around 70 °C. At temperatures higher than 70 °C, however, the insulation performance of PLA deteriorates due to its poor heat resistance. In this study, PLA was heat‐treated at 100 °C to endow it with greater heat resistance, and the effects of this heat treatment on the electrical properties of PLA were investigated. Before being subjected to heat treatment, the crystallinity ( x c ) of PLA was about 6%. After the heat treatment was begun, x c increased in proportion to the heat treatment time, such that measurements revealed that x c had increased to about 42% by 15 minutes after the start of the heat treatment. The temperature dependence of the insulation breakdown strength ( E B ) of heat‐treated PLA was investigated, and it was found that E B of heat‐treated PLA (PLA‐A) decreases at a more moderate rate at temperatures above 60 °C. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(1): 1–8, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21272