Electrically induced mechanical stress was produced on a monolithic polycarbonate (PC) film when subjected to an instantaneous direct current voltage using a needle‐plane electrode setup. Three different experimental methods were used to investigate the electrically induced mechanical deformation on the glassy PC film, namely, morphological observation, energy loss analysis, and dielectric hysteresis study. It was found that the PC film exhibited elastic behavior at the nominal electric field below 200 MV m−1, showing no indentation on the film surface. When the nominal field was above 200 MV m−1, a spherical indentation was created. The depth and diameter of the deformation increased in response to the applied electric field. Subsequent thermal annealing of the deformed film revealed a recoverable “delayed elastic” and an unrecoverable “plastic” deformation. A three‐stage electrically induced mechanical deformation mechanism was proposed based on the experimental results, including a correlation between the energy loss and the deformed volume. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.
In our previous study, electrically induced mechanical stress was produced on monolithic polycarbonate (PC) films under a DC voltage using a needle‐plane electrode setup. This study investigated other materials with various structures and dielectric constants, in order to further understand the deformation mechanism. It was found that the elastic behavior occurred at electric fields intensities below that initiating measurable surface deformation. The amorphous materials, PS, and the semi‐crystalline materials, HDPE and PP, having dielectric constants all around 2.5, exhibited a similar observable deformation onset electric field at 200 MV/m. While PVDF, having a dielectric constant of 10.0–12.0, showed an onset at only 30 MV/m. The data was also compared to our previous study on PC. The depth and diameter of the deformation for all materials increased relative to the applied electric field up to film breakdown. Thermal annealing of the deformed films revealed a recoverable “delayed elastic” component and an irreversible “plastic” component. A three‐stage electrically induced mechanical deformation mechanism was proposed for amorphous materials, while a two‐stage mechanism was proposed for the semi‐crystalline materials. The difference on the energy loss versus deformed volume for amorphous and semi‐crystalline polymers was also determined and discussed.
more » « less- PAR ID:
- 10456708
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Applied Polymer Science
- Volume:
- 137
- Issue:
- 40
- ISSN:
- 0021-8995
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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