Flexural and shear properties of CFRP laminates reinforced with functionalized multiwalled CNTs

Abstract This study focuses on mechanical characterization of carbon fiber reinforced polymer (CFRP) laminates reinforced with non-treated and treated multiwalled carbon nanotubes (CNTs) using nitric acid. The CNTs were treated using nitric acid to obtain carboxylic functional group. The epoxy resins are mixed with 0.3%wt of multiwalled CNTs at a constant mixing speed of 2000 rpm and mixing times varied from 24 to 96 h. Laminates reinforced with treated multiwalled CNTs show an increase in the flexural strength by 17.4 and 15.3% at mixing times of 24 and 96 h as compared to control laminates. The test results indicated that laminates reinforced with treated multiwalled CNTs have improved interlaminar shear failure stress which is 14 and 7% higher at mixing times of 24 and 96 h as compared to control specimen. Improvement in behavior was achieved for functionalized CNTs based laminates which prevents agglomeration. Longer mixing time (96 h) is not beneficial for enhancing the mechanical properties due to the break-up of small aggregates by overcoming the effect of van der Waals forces. Graphical Abstract