Characterization of biocomposite materials for the automotive industry and their application on a structural component

Today, the automotive industry increasingly turns to polymer-based plastic materials to reduce vehicle weight, lower costs, and enhance design flexibility. However, most of these materials are derived from petrochemical sources, and their resistance to natural degradation combined with the high environmental impact of their production and disposal processes has led to sustainability concerns. Widely used plastics such as polypropylene (PP), polyurethane (PU), and PVC are criticized for their low recycling rates and high carbon footprint, prompting the search for alternative materials in the sector. In response, international regulations, emission targets, and producer responsibility frameworks are pushing the industry toward environmentally friendly and sustainable materials. Biocomposites—made from recyclable and biodegradable polymer matrices reinforced with natural or bio-based fibers—are emerging as promising alternatives to conventional plastics. These materials are appealing not only for their ecological advantages but also for their potential to provide sufficient mechanical and thermal performance for specific engineering applications. This study aims to systematically investigate the mechanical and thermal properties of environmentally friendly biocomposite materials for automotive applications. Polypropylene (PP) was used as the matrix, and jute fibers (20%) were combined with varying proportions of glass fibers (5%, 10%, and 15%) to produce hybrid composites. In total, four different formulations were prepared: 20% jute (natural fiber only), 15% jute + 5% glass, 10% jute + 10% glass, and 5% jute + 15% glass. The samples were produced via extrusion and injection molding techniques. The materials were then subjected to a comprehensive characterization including mechanical (tensile, three-point bending, impact), thermal (DSC, TGA, HDT), and morphological (SEM) tests, many of which were conducted in accordance with ISO standards. The technical performance of each variant was evaluated in a multidimensional framework. In addition, a natural fiber-reinforced formulation was applied to real automotive components (side mirror housing and door sill) in a low-volume electric vehicle to assess manufacturability via plastic injection molding. The fully jute-reinforced variant showed advantages in terms of sustainability but exhibited the lowest performance in mechanical tests. With the addition of 5% glass fiber, improvements of 21% in tensile strength, 17% in flexural strength, and approximately 36% in impact resistance were achieved. The formulation with equal amounts of jute and glass fiber (10% each) provided a balanced performance, with a 33% increase in tensile strength and an 18 °C increase in HDT compared to the jute-only composite. The formulation with the highest glass fiber content (15%) demonstrated the highest overall performance, reaching 51 MPa in tensile strength and 103 °C in HDT. These hybrid biocomposites yielded comparable results to engineering plastics such as ABS XR401 and ASA 3421 U in terms of tensile and flexural strength as well as thermal deflection temperature. The findings strongly support the feasibility of using hybrid biocomposites in automotive applications, both from a performance and sustainability standpoint.