Improved fiber–matrix bonding of continuous aramid fiber reinforced acrylonitrile-styrene-acrylate polymer using in-situ impregnation material extrusion additive manufacturing technique

This study compares the fiber–matrix bonding of acrylonitrile-styrene-acrylate (ASA) terpolymer reinforced with standard-finish (A1) and adhesion-activated finish (A2) aramid fibers (Twaron®) manufactured using an in-situ additive manufacturing (AM) material extrusion technique. A2 fibers showed a slightly higher total surface energy (γ_s ∼ 49.45 mN/m) compared to A1 fibers (γ_s ∼ 44.20 mN/m) indicating potentially higher interfacial interaction of A2 fibers with polymer matrix. For single-line manufactured composites, the fiber–matrix bonding performance of the A2-ASA composite improved significantly on increasing the processing temperature from 240 °C to 300 °C resulting in an increase in ultimate tensile strength (UTS) from 694 MPa to 870 MPa. In contrast, A1-ASA composites showed a reduction in UTS from 674 MPa to 544 MPa over the same temperature. Improved mechanical performance of the composite reinforced with A2 fibers was also observed in the multi-layer manufactured composite, where UTS reached 450 MPa and a Young's modulus of 33 GPa, compared to 426 MPa and 15 GPa for the standard finish fibers. The flexural properties confirm the observed improvements in the mechanical properties of A2-ASA composite. The observation derived from the experimental results indicates that the properties of the fiber surface are crucial for enhancing the fiber–matrix bonding, particularly during the manufacturing process of continuous fiber-reinforced composites utilising material extrusion AM techniques. This ASA-aramid composite can be further exploited as a high-performance composite with improved weatherability for outdoor applications.