Microalgae-based biocomposites are gaining traction as ecofriendly and cost-effective alternatives to conventional petroleum-based plastics. However, achieving a homogeneous dispersion of microalgae within a biocomposite matrix remains a challenge. In this study, we investigated the effect of the size of dried microalgae (Chlorella sp.) on the quality of biocomposites. Ball milling, a mechanical grinding process, was used to control the size of the pretreated dried microalgae. Our results demonstrate that the microalgae size strongly depends on the total weight of the stainless-steel balls, rather than the number of balls used in the milling process. Poly(ethylene-vinyl acetate) (EVA), with functional groups resembling those of Chlorella sp., was incorporated into the ball-milled microalgae to produce homogeneous biocomposites. Smaller Chlorella sp. particles improved the ratio of microalgae and the mechanical properties of the biocomposites. Dried Chlorella sp. particles up to 161.43 μm, which were 72.84% smaller than the untreated microalgae, were obtained after 6 h of ball milling using 3/8-inch balls. This enabled the production of biocomposites with 60 wt.% microalgae and 61.02% of the tensile strength of pure EVA, comparable to traditional polymers. Our findings suggest that controlling the microalgae size through ball milling can improve the quality of microalgae-based biocomposites.
Keywords: ball milling; biocomposites; microalgae; tensile strength.