Strengthening the interface between individual aramid fibers and polymer at room and elevated temperatures

Composites reinforced by aramid fibers may suffer poor interface interactions during mechanical loading due to the smooth and chemically inert surface of the fibers. Plasma treatment is usually employed to functionalize and roughen surface of the fibers, leading to strengthening of the interface between the fibers and polymer matrix. Unfortunately, once the composite is exposed to elevated temperatures, the interface shear strength (IFSS) will significantly decrease. To maintain the mechanical performance of the composite at elevated temperatures, a polymer-derived-ceramics (PDC) precursor additive is used to stabilize the interface of the fabricated composite. Testing has shown that the IFSS of composites reinforced by untreated fibers is 29.32 +/- 1.00 MPa and 26.10 +/- 5.23 MPa at 50 degrees C and 100 degrees C, respectively, which surpasses 23.46 +/- 2.32 MPa, the IFSS without PDC stabilization at room temperature. Further research into interactions between heat treatment and strengthening additives would help us fundamentally understand the interface of advanced composite materials, as well as provide theoretical guidance for designing the interface between reinforcement and matrix.