Evaluation of properties and specific energy consumption of spinifex-derived lignocellulose fibers produced using different mechanical processes

Abstract: The increasing global demand for sustainable materials has drawn academic and industrial attention towards lignocellulosic resources. One emerging non-wood source is Australian spinifex arid grass. Exploration of this unique resource is particularly important due to its abundance, extreme drought-tolerance, renewability, and low cost. In this study, mild-alkali treated spinifex grass was subjected to twin-screw extrusion (TSE), high-energy ball milling (HEBM), and high-pressure homogenization (HPH) in order to fibrillate the material into cellulose microfibers (MFC) and nanofibers (CNF). Transmission electron microscopy images confirmed that at least a substantive proportion of CNF is produced by all processes. The overall network density in the confocal laser scanning microscopy images correlated with the normalized light transmittance of the handsheets. The normalized transmittance data suggested that HPH and HEBM produce a high proportion of CNF, as the handsheets made from the material obtained by those methods exhibited translucency. The opacity and relatively low mechanical properties of the handsheets made from the TSE processed fibers suggested a high proportion of MFC present in the treated pulp. However, TSE was found to be the lowest-energy consuming process, making it an attractive fibrillation process. Graphic abstract: [Figure not available: see fulltext.].