Effect of polyacrylic acid‐polypropylene‐polyacrylic acid triblock copolymers with different acid content on mechanical properties of carbon fiber/polypropylene composites

Abstract The use of polyacrylic acid‐polypropylene‐polyacrylic acid triblock copolymers (PAA‐iPP‐PAA, abbreviated as iPP‐PAA) with different acrylic acid contents (9, 19.5, 29 wt%) as compatibilizers for carbon fiber (CF)/polypropylene (PP) composites and their effect on the tensile properties of the composites were investigated. The addition of iPP‐PAA improved the tensile properties of the CF/PP composites. This enhancement in mechanical properties was considered to be due to the hydrogen bonding network between iPP‐PAAs, which improved the mechanical properties of the matrix resin itself, and to hydrogen bonding between carbon fiber surface and iPP‐PAAs, which improved the interfacial adhesion. A higher acrylic acid content of iPP‐PAA resulted in better interfacial properties; however, excessive acrylic acid content adversely affected the crystallinity and tensile properties of the composite, which suggests that there is an optimum acrylic acid content for the iPP‐PAA. The results indicated that iPP‐PAA is an effective compatibilizer in CF/PP composites, and the iPP‐PAA with the best performance had an acrylic acid content of 19.5%. Highlights PAA‐PP‐PAA copolymers used as compatibilizers for CF/PP composites. Acrylic acid content of PAA‐PP‐PAA varied as 9%, 19.5%, and 29%. Tensile properties of CF/PP composites enhanced by iPP‐PAA addition. Hydrogen bonding improved mechanical properties of matrix resin and CF‐resin adhesion. Optimum acrylic acid content for CF/PP composite was 19.5%.