Thermoplastic Composites Reinforced with Wool and Wood: Application in the Automotive Industry ^†

The present study concerns the synthesis of thermoplastic composites simultaneously reinforced with fibers of animal and vegetable origins. The ultimate objective has been to obtain two different components of the inner structure of an automobile, being these parts produced by injection molding from melt blended composites that were optimized to obtain specific formulations according to the structure and function of the target pieces.

The research started with the selection of raw materials that could lead to the replacement of conventional plastics as much as possible, in order to obtain environmentally sustainable solutions. The selection of industrial residues from textile and furniture industries enabled the use and recycling of wool and wood fibers that were supplied under diverse conditions. This conducted to the test of some preliminary treatments so that the fibers contents could be maximized in different polymeric matrices. The most promising results were obtained using Low and High Density Polyethylene. The addition of coupling agents based on Maleic Anhydride grafted Polyethylene was also tested.

The variables under study included the chemical composition of all individual components, the respective thermal behaviors with particular emphasis on the viscosity of the polymers and of the diverse composites, the size and structure of both type of fibers, and the mechanical properties of diverse combination ratios of polymers, wool, wood and coupling agents. The microstructure and surface properties of the composites were also evaluated. This study involved techniques as FTIR, SEM, DSC-TGA, torque rheometry, tensile testing, and contact angle measurements, among others.

After optimization of multiple parameters, two different formulations were synthesized by extrusion processing and the obtained granules were subsequently used for production of the proposed injection molded car parts: a locker for the glove compartment and the rolling support of the seat belts.