Abstract: With a promise that a 10% reduction in the vehicle weight can result in 6-8 % increase in fuel efficiency, lightweight polymer composites with high strength and stiffness have been identified as a key cross-cutting technology by automotive industry for better fuel efficiency and lower CO2 emission. One way for light- weighting is replacing the material with a lighter material with at least equal performance. Sheet molding compounds (SMC) are the precursor polymer composites in automotive applications. This study focuses on producing lighter SMC composites with two different approaches, i.e. i) replacing a part of heavier components of current SMC composites (e.g. glass fibers) with a small amount of cellulose nanomaterials and ii) using basalt fibers (BF) as an alternative to the traditionally used glass fibers (GF). For approach (i), we have recently reported that addition of 1 and 1.5 wt% cellulose nanocrystals (CNC) in 25 wt% GF/epoxy composites results in the same modulus and strength of 35 wt% GF/epoxy composites both made by SMC and compression molding. The hybrid CNC-containing composites has ~8% lower density and higher tensile strength and flexural properties. We have also investigated approach (ii) and have shown that GF can be replaced by BF in SMC manufacturing as BF provide higher or at least equal mechanical properties in terms of tensile and flexural properties, resulting in high performance SMC composites with reduced cost for automotive applications. Finally, we investigate light weighting of BF/epoxy SMC composites at higher fiber content (e.g. 60 wt%) by adding CNC and lowering the BF loading. The properties of lightweight hybrid BF/epoxy SMC composites are compared with those of lightweight GF SMC composites to provide a better understanding of the effect of fiber type in the composite performance.
Authors: Amir Asadi, Ferdinand Baaij, Robert J. Moon, and Kyriaki Kalaitzidou