Thermomechanical and electrical properties of PDMS/MWCNT composite films crosslinked by electron beam irradiation

Electron beam (EB)-crosslinked flexible polydimethylsiloxane (PDMS) composite films containing 1.0–3.0 wt% pristine MWCNT were manufactured, and their structures, thermomechanical, and electrical properties were systematically investigated for applications as electric heating materials. The crosslinking extent of PDMS/MWCNT composite films was found to increase with the EB irradiation dose of 200–600 kGy, irrespective of the MWCNT content. Raman spectra showed that I D/I G values (0.97–1.02) for the EB-crosslinked composite films were lower than those of pristine and EB-irradiated MWCNTs (1.07–1.17), demonstrating the possibility of the chemical interaction between MWCNT and PDMS in the composite films. Dynamic mechanical thermal data revealed that the EB-crosslinked composite films possessed flexible features in a wide range of temperatures, although the storage moduli increased slightly with the increment of the MWCNT content. The electrical resistivity and electric heating behavior of the composite films, which were thermally stable up to ~200 °C, were strongly dependent on the MWCNT content as well as applied voltage. For instance, the composite film with 2.0 wt% MWCNT achieved a steady-state maximum temperature of ~150 °C at a relatively low voltage of 35 V and it also maintained stable and reproducible electric heating performance under stepwise cyclic voltage changes for a long period of time.