Preparation of CFRP with modified MWCNT to improve the mechanical properties and torsional fatigue of epoxy/polybenzoxazine copolymer

This study proposes a novel method for preparing a high-performance laminated nanocomposite that simultaneously offers low weight, high strength, long material life, high weatherability, and high environmental friendliness. 4,4-Methylene diphenyl diisocyanate (MDI) was grafted onto multiwall carbon nanotube (MWCNT) surfaces, and hot-compression exhaust method was used to prepare nanocomposites and carbon-fiber-reinforced polymer (CFRP) composites, to improve the dispersivity of MWCNTs in the matrix while reducing interlaminar defects in CFRP, and thereby, enhance the mechanical strength and torsional fatigue life of the material. The experimental results showed 11% increase in storage modulus, with the glass transition temperature increasing from 102 °C to 158 °C. The drop-weight impact test and C-scan results indicated that the hot-compression exhaust method effectively constricted the expansion caused by delamination and damage through denser and tighter bonding between laminates of prepreg cloth. The torsional fatigue strength was also enhanced, with the average fatigue life increased more than 20 times.