Beating waste into value: Energy demand and technology of packaging paper production using post-consumer textiles

The increasing volume of post-consumer textile waste creates the necessity to develop alternative recycling pathways, beyond fibre-to-fibre applications. In this study, cellulose-rich textile waste (predominantly cotton) was mechanically processed, and the associated energy input was quantified. Textile fibres were refined at different levels of specific beating energy (SBE), fibre characteristics were investigated, and the resulting suspension was blended with industrial paper stock. Paper handsheets were produced, and the key properties were analysed. This study demonstrates that increasing SBE enhances tensile strength, short-span compression strength (SCT), density, and elastic modulus, while bending stiffness is comparatively less affected despite the associated densification and reduction in sheet thickness. Under realistic assumptions, the cumulative energy demand required to achieve industrially relevant fibre properties through refining was recorded at 748 kWh·t −1 at comparable dewatering resistance (Schopper-Riegler). This energy demand is well comparable to that of typical virgin fibre feedstocks utilised in packaging paper, such as mechanical pulp. A modelling approach demonstrated that the tensile index of fibre blends can be accurately predicted from the tensile properties of the pure components using a simple rule of mixtures approach. Furthermore, the tensile index was shown to be a suitable predictor of SCT. By combining these predictive models with the established energy benchmarks, this study provides a robust, data-driven roadmap for the industrial integration of textile waste into packaging paper production.