A diglycidal ether of bisphenol-A (DGEBA) epoxy resin matrix is modified by adding as received recycled milled carbon fibre (SMCF) in the proportion of 1, 2, 3, 5 and 10 wt. %. The epoxy – SMCF mixing was carried out using mechanical and ultrasonication methods. X-ray fluorescence (XRF) and X-ray photoelectron spectroscopy (XPS) study showed that as-received SMCF contained 96.7 % purity carbon and rest consisted of impurities. XPS further revealed that SMCF surface had low O/C ratio which

more »

... ted less amount of oxygen containing functional groups present on the surface of the SMCF, resulting in less active surface area available for chemical bonding with epoxy. Reaction of oxirane ring (C – O – C) on curing was monitored in presence of SMCF particles and it was confirmed that SMCF particles did not interact with epoxy curing reaction. The stress intensity factor (KIC) and fracture toughness (GICMat) of neat epoxy and SMCF modified epoxy matrix were studied using ASTM D5045 specimens. Reinforcement of 10 wt. % SMCF particles enhanced the KIC of neat epoxy from 0.78 MPam1/2 to 2.71 MPam1/2 whereas GICMat was increased from 0.26 kJ/m2 to 2.06 kJ/m2, which is believed to result from the combined effect of fibre stereology and the debonding/pull-out mechanisms observed under Scanning Electron Microscope (SEM) images of fracture surfaces. In addition, the flexural modulus of the 10 wt. % SMCF reinforced epoxy was 58 % higher than that of the neat epoxy. The dispersion and distribution study of SMCF particles in epoxy resin showed that SMCF particles did not cluster in epoxy matrix. Average mean free path between SMCF particles at notch tip of single edge notch bending sample was 600 μm for 1% SMCF which reduced to 110 μm for 10 % SMCF. Using the SMCF modified epoxy as matrix, carbon fibre reinforced polymer (CFRP) laminates were fabricated with 10 layers of unidirectional long carbon fibres (40 % by volume) reinforced in 5 and 10 wt. % SMCF modified epoxy. Fabricated CFRP laminates were tested under mode I delaminati [...]