Surface charge dependence on load in amorphous stereocomplex poly(lactic acid) electrets processed with microwave heating

This paper reported the process of causing piezoelectricity to amorphous stereocomplex poly (lactic acid) using microwaves. From finite element analysis results of microwave irradiation from the constructed resonator to the film, it was found that microwave with an electric field strength of 7 MV m−1 was applied to the film at the incident power of 200 W. The microwave instantaneously heated the film, and at the same time, a DC voltage was applied to the film to inject an electric charge into the film and create an electret. Since the macro and micro piezoelectricity were confirmed and the trapped charge was retained permanently, poly (lactic acid) electret was caused by the process. The feature of the microwave irradiation process is instantaneous heating and cooling. It is considered that the feature contributed to the film that retained the trapped charge state at each temperature from the glass transition temperature to the crystallization temperature.