Concentration-dependent effects of Triton X-100 surface treatment on the mechanical and tribological performance of short carbon fiber–epoxy composites

Surfactant-assisted interfacial modification of short carbon fiber–epoxy composites is commonly evaluated for either mechanical or tribological performance, rarely both, though both originate at one fiber–matrix interface. This study treats chopped carbon fibers with aqueous Triton X-100 at 0, 1, 2, and 3 wt.%, evaluating tensile strength, compressive strength, coefficient of friction, and specific wear rate from one fabrication batch under a shared protocol. At 1 wt. % treatment, tensile strength increases 40.3% (82.67–116.00 MPa, p < .05) and compressive strength increases 40.4% (63.2–88.7 MPa, p < .05) relative to the untreated composite, with elastic modulus unchanged in both loading modes. Steady-state coefficient of friction decreases 35.6% (0.45–0.29, p < .05), and specific wear rate decreases 27.4% at 300 RPM and 64.3% at 200 RPM. This hierarchy holds across seven independently measured properties, indicating a shared interfacial variable governing both load transfer and sliding contact. Wear rate at 200 RPM deviates from Archard’s linear load dependence, consistent with load-induced third-body compaction. Surfactant coverage state, assessed gravimetrically, is consistent with near-saturation coverage at 1 wt.% but not confirmed as monolayer adsorption without direct spectroscopic characterization. The findings represent a correlated, concentration-dependent performance trend across two response classes in one material system, bounded by the absence of interfacial shear strength, surface-energy, and thermal-transition data.