ABS composites with cellulose fibers: Towards fiber-matrix adhesion without surface modification

•Cellulose fibers (CF) adhere to the ABS matrix.•30 wt.% of CF promotes 20% of mechanical properties improvement in ABS composites.•The inclusion of 30 wt.% of CF reduces 20 wt.% of the oil-based polymer in composites.•Fiber-matrix adhesion derives from interface reactions occurring during extrusion.•Chemical treatment/modification procedures are not used. Aiming for a cost-effective and environmentally friendly material, we propose the replacement of glass fiber/poly(acrylonitrile-co-butadiene-co-styrene) (ABS) composites by composites with cellulosic reinforcing agents. Industrial production of these composites is hindered by high cost and/or fiber surface modification methods. We report that 30% in weight (wt. %) of pristine cellulose fibers (CF) are highly adherent to an ABS matrix, as verified by microscopy. This provides an overall enhancement of 20% in tensile and flexural mechanical properties. Fiber/matrix adhesion derives from the oxidation of polybutadiene (PB) segments during extrusion, which generates epoxide groups that react with hydroxyls from CF to form ether bonds. We used additives for testing improvement of fiber/matrix adhesion. The addition of XIBOND™ 160 (maleic anhydride grafted polystyrene) reduces fiber/matrix adhesion due to the competition between the grafting of cellulose fibers onto PS segments of the additive and PB domains of ABS. Lignin catalyzes the epoxide reaction with hydroxyls, which leads to improvements in flexural mechanical properties. Overall, ca. 20 wt. % of ABS can be effectively saved by adding 30 wt. % of CF, with improvement of mechanical properties. The density of the composites is 1.3 g cm−3, similar to glass fiber/ABS composite densities. Therefore, CF is effective as a reinforcing filler for ABS, reducing cost and improving mechanical properties. [Display omitted]