Development of milled carbon fibre-based GFRP composites and their effect on microwave and structural properties

Objective of this study was to fabricate the microwave absorbing structures (MAS) with structural properties in X and Ku bands. Glass fibre reinforced plastic (GFRP) epoxy composites have excellent specific stiffness and strength to weight ratio. Milled carbon fibres (MCF) have been added as filler to bring functionality in GFRP composites, which causes dielectric loss. MAS were fabricated with variable wt% (2.5-7.5%) of MCF in glass epoxy composite system. The electromagnetic properties were measured in X and Ku bands using free space measurement system. Mechanical properties such as tensile strength, flexural strength and interlaminar shear strength of fabricated composites have been evaluated as per the relevant ASTM standards. The results show that the matching frequency of the microwave absorber shifts towards lower side of frequency band by increasing thickness, and reflection loss decreases with increase in MCF wt%.