Thermal Aging Mechanisms and Dielectric Properties of Epoxy Resin Impregnated Bamboo Paper Composites

This study investigates the thermal aging behavior of bamboo paper and wood paper and their epoxy resin impregnated composites. The results reveal that although both materials follow a common “degradation-reorganization” aging path, their mechanisms differ fundamentally due to inherent structures. Bamboo paper exhibits higher chemical reactivity arising from its greater hemicellulose and lignin content, leading to more extensive oxidative degradation, as evidenced by a 66% increase in carbonyl index versus 53% for wood paper, a faster decline in thermal decomposition temperature, and a higher char residue rate. Crystallinity analysis shows a non-monotonic evolution in both papers, with wood paper maintaining a consistently higher crystallinity index throughout aging. Dielectric measurements demonstrate that the epoxy resin impregnated bamboo paper composites develop a more reactive interface, producing broader interfacial polarization, higher relaxation strength and conductivity, and a more dynamic three-stage dielectric evolution, with parameters 30% to 50% higher than those of the epoxy resin impregnated wood paper composites. Havriliak-Negami model analysis reveals that the epoxy resin impregnated bamboo paper composites possess higher charge mobility and a wider trap energy distribution. Separate analysis of the shape parameters further identifies fundamentally different interfacial polarization evolution modes, with the bamboo composites exhibiting α1-dominated broadening of the relaxation time distribution and stable β1, whereas the wood composites display a β1-dominated decline. These findings demonstrate that wood paper undergoes structure-modulated aging with relatively stable progression, while bamboo paper follows chemically driven aging characterized by more complex degradation and interfacial restructuring.