Sustainable biodegradable denim waste composites for potential single-use packaging

Abstract

Every year a massive 2.16 million metric tons of denim jeans is globally wasted and mostly goes into landfill. Though denim is highly rich in cellulose, its valorisation has received little attention. A few attempts have previously shown prospects of denim in composites, though the ultimate products were non-compostable due to the nature of the chosen matrix. This research proposes a novel development of denim/cornstarch composite, maintaining 50/50 fractions, using different denim snippet size. A smoother denim/cornstarch composite morphology and higher tensile strength were observed when smaller denim snippets were used, whereas larger snippets produced voids and roughness and a higher hygroscopicity. Composite prepared from semi-gelatinised cornstarch showed a completely flexible structure similar to non-woven sheet. The chemical structure was observed identical in all of the composites and a good structural compatibility perceived. Individual peaks of both denim (1105 cm−1 and 1705 cm−1) and cornstarch (1081 cm−1) were confirmed in all composite samples, either gelatinised or semi-gelatinised cornstarch used. Overall, this work reveals an eco-friendly approach to utilise consumed denim waste, with insight on possible fine-tuning through alteration of denim snippet size and cornstarch gelatinisation. The mechanical and moisture properties of the composites also suggest their potential application in single-use packaging.