Impact of Water Absorption and Gamma Irradiation on Electrical Equivalent Circuit Parameters of Carbon Fiber Reinforced Polymer Composites

The influence of environmental stress such as water absorption and gamma (γ) irradiation on carbon fiber-reinforced polymer (CFRP) composites is of critical importance for aerospace, automotive, and nuclear applications. In this work, electrical equivalent circuit modelling (ECM) is employed to assess the dielectric behaviour of CFRPs under controlled water immersion and irradiation up to 3000 kGy. The results reveal significant modifications in circuit parameters: the series resistance (Rs) increases from 2.8 Ω (dry laminate) to 9.6 Ω after 10 minutes of water absorption, while the parallel resistance (Rp) decreases from 306 kΩ to 29 kΩ after 1 hour, indicating the onset of bulk water diffusion. γ- irradiation produces contrasting effects; at 1000 kGy, Rs rises sharply to 142 Ω while Rp collapses to 93 Ω due to chain scission and free radical formation, whereas at 3000 kGy, capacitance increases to 2.4 nF and Rpimproves to 706.5 kΩ, signifying enhanced crosslinking.