Association of coconut wax and nanolignin for eco-friendly packaging coating: study of barrier, surface, and mechanical properties

Abstract Plastic packaging causes damage to ecosystems, especially marine ones, due to the accumulation and difficulty of environmental degradation. Alternatively, biopolymers are promising due to their biodegradability and increased safety. Coconut wax is valued for its clean burn, low toxicity, and for being a sustainable alternative to other waxes, such as paraffin. Nanolignin (NL) is a nanometric material obtained from lignin, the second most abundant renewable natural biopolymer on the planet after cellulose. The effects of coconut wax-based coatings containing different proportions of nanolignin on the properties of Kraft paper were investigated. Emulsions with 0.5 %, 1.0 %, 1.5 %, 2.0 %, and 2.5 % NL were applied in two layers on the paper. The samples of coated papers were evaluated by microstructure, wettability, water vapor barrier, and mechanical properties. Peaks associated with saturated fatty acids were observed in the 3,100 cm −1 and 2,800 cm −1 bands. Only the coating with 0.5 % NL obtained cohesive layers, and the other emulsions penetrated the paper. The emulsions with 2.0 % and 2.5 % NL showed the lowest water absorption (∼28 g/m 2 ) and wettability (∼0.03°/s). On average, compared to the control, the coatings reduced tensile strength by up to ∼38 % and Young’s modulus by up to ∼43 %. Compared to the control, the water vapor permeability of the coated papers was lower (450–800 g/m 2 day). The results highlight the potential of coconut wax associated with lignin valorization for paper coating, considering the industrial requirements for moisture-sensitive products.