Electro-mechanical studies of multi-functional glass fiber/epoxy reinforced composites.

An experimental study is performed to investigate the electro-mechanical response of three-dimensionally conductive multi-functional glass fiber/epoxy laminated composites under quasi-static tensile loading. To generate a threedimensional conductive network within the composites, multi-wall carbon nanotubes are embedded within the epoxy matrix and carbon fibers are reinforced between the glass fiber laminates using an electro-flocking technique. A combination of shear mixing and ultrasonication is employed to disperse carbon nanotubes inside the epoxy matrix. A vacuum infusion process is used to fabricate the laminated composites of two different carbon fiber lengths (150 mm and 350 mm) and four different carbon fiber densities (500, 1000, 1500, 2000 fibers/mm2). A four circumferential probe technique is employed to measure the in-situ electrical resistance of composites under tensile load. Although composites of both carbon fiber lengths showed significant decrease of sheet resistance under no mechanical load conditions, composites of 350 mm long carbon fibers showed the lowest resistivity of 10 X/sq. Unlike the resistance values, composites of 350 mm carbon fibers showed a significant decrease in Young's modulus compared to 150 mm counterparts. For the electro-mechanical response, composites containing carbon fibers of 150 mm long demonstrated a maximum value of percentage change in resistance. These results were then compared to both 350 mm and no added carbon fibers under quasi-static tensile loading. [ABSTRACT FROM AUTHOR]