Thermoformed Polypropylene Composite Reinforced with Cotton Fabric

摘要

The use of natural fibers as reinforcement in composites has received much attention due mainly to environmental issues and because of their interesting properties. The development of new methods for production of thermoplastic composites with natural fibers is of great interest for several sectors in industry. In this work, composites of polypropylene and raw cotton fabric are fabricated by hot pressing alternating layers of polypropylene films and cotton fabric to produce a long fiber oriented composite material. Five combinations with different number of reinforcement and matrix layers are prepared, leading to composites with more than 50% of fiber in volume. Characterization of the composites showed a great enhancement on mechanical properties (85% on elastic modulus and 90% on tensile strength) with a density decrease of around 15%. The braided nature of the cotton fiber provided good adhesion to the matrix through mechanical anchoring, as is observed by SEM. This enabled increased thermal stability and an increase in the storage modulus determined by DMA in the rubbery plateau. The good mechanical properties were explained by the mechanical anchorage of fiber matrix, since PP resin is forced to flow through the fibers of the raw cotton fabric. The resultant material is more resistant, lighter, and stiffer composed of approximately 50% of materials derived from renewable sources.