Fabrication and Mechanical Characterization of Basalt Fiber‐Reinforced Polyphenylene Sulfide Composite Sheets via Wet Dispersion Process

Basalt fiber (BF)‐reinforced polyphenylene sulfide (PPS) composite sheets were fabricated by a papermaking‐inspired wet‐dispersion and hot‐pressing process. The effects of BF content, initial fiber length, coupled BF dispersion concentration/wet‐felt stacking, and expansion ratio were evaluated in separate experimental series. Among the tested BF contents, the 50 wt% BF group showed the highest measured flexural strength, flexural modulus, and non‐notched impact strength, reaching 230.76 MPa, 19208.50 MPa, and 86.21 kJ/m 2 , respectively. In the fiber‐length series, the 9 mm BF group showed the highest measured values. In the coupled concentration–stacking series, the 1 g/L single‐wet‐felt condition showed the highest measured values, although concentration and wet‐felt number varied simultaneously and their effects could not be separated. These conditions were not combined and re‐tested as a single formulation. Assuming constant mass and unchanged in‐plane dimensions, the geometrically estimated relative‐density reduction reached 80% at an expansion ratio of 5. SEM observations revealed local fracture features, including fiber fracture, pull‐out, debonding, and local fiber–matrix contact. The results demonstrate the feasibility of wet‐dispersed BF/PPS composite sheets and clarify the effects of processing variables on mechanical response and expansion behavior.