Degradation of silicone rubbers with different hardness in various aqueous solutions

Tan

J of Applied Polymer Sci

et al. 2019

Long‐term chemical and mechanical stability of gaskets in proton‐exchange membrane (PEM) fuel cells is critical to the sealing and normal operation of these fuel cells. In this study, the chemical and mechanical degradation of a silicone rubber was investigated. Two compression loads and two simulated environments were used. The weight change of sample was monitored. Optical microscopy was applied to observe the morphological changes on the specimen surface. Attenuated total reflection (ATR)–Fourier transform infrared (FTIR) spectroscopy and X‐ray photoelectron spectroscopy (XPS) were used to investigate the chemical changes on the surface of specimens after exposure to the simulated solutions and subjection to compression loads over time. A compression stress‐relaxation test was used to elucidate the stress‐relaxation property changes of the specimens after exposure to the simulated fuel‐cell environments and the compression loads. Optical microscopy showed that the surface morphology of the specimens changed from initially smooth to slightly rough followed by crack initiation and finally propagation. The ATR–FTIR and XPS results indicate that the surface chemistry of the specimens significantly changed via decrosslinking and chain scission after exposure to the simulated environments and compression loads over time. The compression stress‐relaxation test results indicate that the mechanical properties of the silicone rubber specimens changed significantly. We found that both the acid concentration of the test solution and the compression load significantly affected the degradation of the silicone rubber material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47855.

Section: Resultssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 81%

Chemical and mechanical degradation of silicone rubber under two compression loads in simulated proton‐exchange membrane fuel‐cell environments

Tan

J of Applied Polymer Sci

et al. 2019

International Journal of Smart and Nano Materials

“…known to cause degradation of silicone polymers [39]. From the thermal gravimetric analysis of the investigated elastomers (shown in Figure 2), it is obvious that in terms of energies involved in the electrical breakdown correspond to the energies from a solely thermal degradation process of more than 500°C.…”

Section: Breakdown Analysismentioning

confidence: 95%

Degradation patterns of silicone-based dielectric elastomers in electrical fields

Madsen

Skov

2017

Silicone elastomers have been heavily investigated as candidates for the flexible insulator material in dielectric elastomer transducers and are as such almost ideal candidates because of their inherent softness and compliance. However, silicone elastomers suffer from low dielectric permittivity. This shortcoming has been attempted optimized through different approaches during recent years. Material optimization with the sole purpose of increasing the dielectric permittivity may lead to the introduction of problematic phenomena such as premature electrical breakdown due to high leakage currents of the thin elastomer film. Within this work, electrical breakdown phenomena of various types of permittivity-enhanced silicone elastomers are investigated. Results showed that different types of polymer backbone chemistries lead to differences in electrical breakdown patterns, which were revealed through SEM imaging. This may pave the way towards a better understanding of electrical breakdown mechanisms of dielectric elastomers and potentially lead to materials with increased electrical breakdown strengths.

“…The formation of HCl would lead to an autodegradative process since a highly acidic environment is well-known to cause degradation of silicone polymers 31 . Within the current study it is not possible to couple the thermal behavior with the electrical breakdown process but as discussed previously the change in electrical breakdown behavior may also be a result of changed microscopic or even nanoscopic morphology.…”

Section: Breakdown Analysismentioning

confidence: 99%

Electrical breakdown phenomena of dielectric elastomers

Mateiu

Skov

2017

SPIE Proceedings

Silicone elastomers have been heavily investigated as candidates for dielectric elastomers and are as such almost ideal candidates with their inherent softness and compliance but they suffer from low dielectric permittivity. This shortcoming has been sought optimized by many means during recent years. However, optimization with respect to the dielectric permittivity solely may lead to other problematic phenomena such as premature electrical breakdown. In this work, we investigate the electrical breakdown phenomena of various types of permittivity-enhanced silicone elastomers. Two types of silicone elastomers are investigated and different types of breakdown are discussed. Furthermore the use of voltage stabilizers in silicone-based dielectric elastomers is investigated and discussed.