Electromechanical deformation and failure of multilayered films

Abstract

Layer thickness was found to have a significant effect on the irreversible electromechanical deformation and the failure mechanism in polycarbonate (PC)/ poly (vinylidene fluoride) (PVDF) multilayered films when subjected to an electrical impulse in a DC needle-plane configuration. Three distinct regions of behavior were observed. Region I comprised thick layer systems that exhibited only irreversible center deformation. The improvement to failure resistance compared to the monolithic films was attributed to the interphase between the two components. Region II films with an intermediate layer thickness showed both an irreversible center deformation and a treeing mechanism which were observed to simultaneously occur. The surface treeing mechanism, similar to the lightning treeing phenomena in nature, occurs only at impact rates. The tree morphology showed large amounts of plowing, indicating that this damage mechanism can dissipate a large amount of energy prior to electromechanical fracture of the film. Region III films comprise ultrathin layers in the nanoscale and showed no treeing. The unique interphase region between these ultrathin layers was estimated to be at least ten percent of the overall layered structure. These films behaved similar to monolithic materials with improved electromechanical failure characteristics. This work complements the enhanced dielectric performance of multilayer films observed in earlier investigations.

Water-processable cellulosic nanocomposites as green dielectric films for high-energy storage

“…Interestingly, the laminated composite film demonstrated maintained losses at 100 Hz yet a higher dielectric constant (~5). Consistent with other layered film structures reported in the literature, this is likely due to the interfacial regions between layers acting as barriers capable of slowing or even stopping the propagation of charges between layers [34,35]. The laminated films stored in a vacuum chamber also demonstrate maintained frequency dependent properties when measured over a five-day period (Figure S2), indicating dielectric stability in the moisture-free surrounding environment, as the case of being encapsulated by packing materials in embedded capacitor technologies [36,37].…”

“…It is evident from the graph that while the addition of PVDF does enhance the breakdown strength across all oxidation times, the laminated film structure yields the highest measured breakdown strength, with a 147% increase compared to its single layer composite counterpart, exceeding that of both CNF and PVDF alone. This significant improvement is likely due to a combination of the high breakdown strength of PVA and the interfacial regions between layers acting as barriers for space charge, similarly to the interfacial regions surrounding the PVDF nanofillers, reducing the likelihood for electrical breakdown [34,35]. Polarization-electric field (P-E) loops were measured to assess the linearity and hysteresis of both pristine and composite films made with 5 minute oxidized CNFs.…”

Analysis of fracture damage mechanical properties of particle reinforced polymer composite film based on micro-macro finite element method

“…Generally, PVDF displayed superior mechanical properties. Zhang et al [16] have analyzed the irreversible electromechanical deformation and failure mechanism of polycarbonate/PVDF multilayered composites under electrical impulse. The results show that both irreversible center deformation and treeing mechanism were simultaneously occur on the intermediate layer.…”