Lightweight Sheet Molding Compound (SMC) Composites Containing Cellulose Nanocrystals

Abstract

Lightweight composites with high strength and stiffness have been identified as a key cross-cutting technology by automotive industry, considering that a 10% reduction in the vehicle weight can result in 6-8 % increase in fuel efficiency. In this study, a scalable technique was introduced to make lightweight hybrid sheet molding compound (SMC) composites for automotive applications by replacing the heavier components, i.e. glass fibers (GF), with a small amount of cellulose nanocrystals (CNC) with no penalty on mechanical performance. We report that incorporation of 1 and 1.5 wt% CNC in the epoxy matrix of short GF/epoxy SMC composites allows removing 10 wt% glass fibers (GF), producing 7.5% lighter composites with no compromise in tensile and flexural properties. The addition of 1 wt% CNC in 25GF/CNC-epoxy SMC composites resulted in increases of 15% in elastic modulus, 11% in flexural modulus and 14% in flexural strength, reaching the corresponding properties of 35GF/epoxy SMC composites. The results of this study will enlighten the path toward high volume production of lightweight SMC composites with a better performance in automotive composite production.