Multidimensional Investigation of ILSS and Compressive Strength of CF-Reinforced Epoxy Composites

Interlaminar shear strength (ILSS) and compressive strength are critical performance indicators for carbon fiber (CF) reinforced epoxy resin composites (CF/EP) in engineering applications. In this study, methyl tetrahydrophthalic anhydride (MTHPA) and tris(dimethylaminomethyl)phenol (DMP-30) are used as the curing agent and catalyst, respectively, while amino-terminated liquid nitrile rubber (ATBN) is served as the toughening agent. In parallel, an interpenetrating polymer network (IPN) derived from NCO-terminated oligomers is introduced to synergistically enhance ILSS, compressive strength, and flexural strength. DMP-30 regulates the curing mechanism of epoxy resin by controlling the reaction between hydroxyl and epoxy groups, thereby tuning the crosslinking density in the EP/MTHPA/DMP-30 matrix. ATBN improves the toughness of epoxy resin through a chemical reaction between its amino groups and the epoxy matrix. Furthermore, NCO-terminated oligomers are incorporated into the ATBN-toughened EP/MTHPA/DMP-30 matrix, forming an IPN-modified composite via selective reaction between NCO groups and hydroxyl groups in the matrix. As a result of this multi-dimensional optimization strategy, the composites achieved a maximum ILSS of 101.72 MPa, representing a 47.29% improvement, and a maximum compressive strength of 808.12 MPa, corresponding to a 71.84% increase. Highlights ATBN/EP and NCO-oligomer were synthesized for enhanced performance. ILSS improved by 47.29% and compressive strength by 71.84% via toughening. Toughness of CF/EP composites is vital for aerospace structural applications. Crosslink density directly influences compressive strength in CF/EP systems. Multidimensional toughness mechanisms enhance mechanical properties of CF/EP composites.