Processing and performance of nanophased braided carbon/epoxy composites

A systematic study has been carried out to investigate mechanical properties of 2D nanophased braided carbon/epoxy composites. SC-15 epoxy with three types of braided fabrics: +/-45 degrees, 0/+/-45 degrees, and 0/+/-60 degrees was used to fabricate composite laminates using vacuum assisted resin infusion molding (VARIM) process. Low-velocity impact (LVI), ultrasonic nondestructive evaluation (NDE) and 3-point bend flexure studies were carried out on biaxial and triaxial braided samples. Impact parameters like peak load and absorbed energy were calculated. All the LVI tested samples were then subjected to ultrasonic c-scan testing to determine the damage size. From the results it was seen that laminates sustained the impact load without any damage at 10J, a little damage at 20J and more damage at 30J. From the ultrasonic tests it was seen that the biaxial +/-45 degrees laminates had lowest damage. Flexural test showed the highest flexural strength and stiffness for triaxial 0 degrees/+/-45 degrees. An investigation was also carried out to improve the properties of the braided laminates by introducing Nanomer (R) I-28E nanoclay, a surface modified montmorillonite mineral, into SC-15 epoxy matrix. Different weight percentages of nanoclay were dispersed in SC-15 epoxy. Highest properties were obtained for samples with 1% by weight of nanoclay reinforcement. (C) 2009 Elsevier B.V. All rights reserved.