Enhancing in‐plane elasticity of carbon fiber reinforced thermoplastic multilayer films with polyrotaxane and nanocellulose composites

Abstract Sandwich films were prepared by inserting resin sheets between carbon fiber‐reinforced thermoplastic (CFRTP) sheets, and their tensile and bending strengths were evaluated. The CFRTP sheets used nylon 66, polyurethane, and polyphenylene sulfide as impregnating resins. The resin sheet used was polypropylene, a general‐purpose resin, combined with a composite material incorporating polyrotaxane and cellulose nanofibers as organic fillers. The sample containing both components showed a 134% improvement in Young's modulus compared to neat polypropylene. This study controlled the number of layers in the sandwich film and assessed the dependence of mechanical properties on layer count. The sandwich films demonstrated particularly good strength in the in‐plane direction, exhibiting excellent bending properties. Furthermore, using composite materials for the resins sandwiched between CFRTP sheets further enhanced mechanical properties. The film material, which can be prepared through simple press molding, is a lightweight material composed of light elements, and exhibits a Young's modulus in the gigapascal scale. CFRTP sheets using nylon 66 as the impregnating resin, the flexural modulus improved by approximately 5.8 times. Furthermore, by increasing the number of laminations, an additional improvement of 3.1 times was observed. This study also identified conditions for improving elongation properties. Highlights A new material was created using carbon fiber reinforced thermoplastics (CFRTP). Multilayered alternating films made of CFRTP and polymer composite were created. Corresponding multilayer films showed anisotropy in mechanical properties. Corresponding multilayer films exhibited excellent in‐plane elasticity. In‐plane elasticity showed a clear dependency on the number of layers.