Recycled Jeans/Denim Cotton Fibre as a Bio-based Material for Paperboard Handsheets: Laboratory Evaluation

Abstract

Fabric fibres have been used in paper production for more than 2,000 years. With industrialisation, wood-based fibres largely replaced textile fibres in paper products and packaging grades. Environmental concerns about plastic bags have renewed interest in paper-based and bio-based alternatives. Renewed interest in natural fibre materials for paper and board applications requires evaluation of sustainable fibre sources within current industrial processes. In this study, jeans/denim fibre (JDF) was produced from collected 100% cotton jeans trousers cut into 1.0 inch x 1.0 inch (25.4 mm x 25.4 mm) pieces before refining. Handsheets were prepared using JDF and old corrugated container (OCC) fibres. Handsheets with a target basis weight of 70 g/m² were produced from blends ranging from 100% OCC to 100% JDF in 10% increments and evaluated for mechanical, surface and optical properties. The handsheets showed opacity values close to 100% and changed from brown to blue as OCC content decreased and JDF content increased. Higher OCC content was associated with greater air resistance, indicating a more compact sheet structure. Handsheets containing 100% to 40% OCC generally showed higher strength performance, including short compression strength index, burst index, tear index, zero-span strength and tensile strength. JDF contents above 50% reduced mechanical properties. The results indicate that JDF may be suitable as a partial fibre component in paperboard handsheets, but high JDF fractions reduce mechanical integrity. Further laboratory and pilot-scale research is required to optimise fibre processing, sheet formation and strength development before industrial paperboard application.