Improved fracture toughness in carbon fibre epoxy composite through novel pre-preg coating method using Epoxy Terminated Butadiene Nitrile rubber

• Dispersion of ETBN using organic solvent (THF) for the pre-preg coating was developed.
• Developed automatic draw down pre-preg coating technique to coat rubber on pre-preg.
• ETBN coated cured samples were studied for the quality and dispersion of the coating.
• Fracture behaviour of the cured pre-preg composite by conducting DCB and ENF tests.
• Morphology of fractured samples by SEM to understand ETBN toughening mechanism.

A novel pre-preg coating method was used to improve the interlaminar fracture toughness in carbon fibre epoxy composite laminates, using reactive liquid rubber. The Epoxy Terminated Butadiene Nitrile (ETBN) liquid rubber incorporated between pre-pregs using automatic draw bar coating technique. Experimental test results reveal that by adding ETBN in small quantities in the range of 15.55–22.66 g/m2, inter laminar critical energy release rates (GIC and GIIC) can be improved up to 140% in mode-I loadings and 32% in mode-II loadings respectively. It was confirmed that the effect of ETBN rubber concentration in carbon epoxy pre-preg system on interlaminar fracture toughness under mode-I and mode-II loadings, was discussed by on the bases of fractographic observations and mechanism considerations using SEM.