Reinforcement of natural fiber yarns by cellulose nanomaterials: A multi-scale study

Abstract

Cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC) were used to improve the mechanical properties of tapes and yarns produced from natural fibers as a new application of cellulose nanomaterials in textile-based composite products. Hemp and flax slivers were used as natural fibers for the production of yarns and tapes. CNC, unground CNF and two different ground CNF suspensions were used as the reinforcement agents. Fiber strands from each natural fiber were soaked in the cellulose nanomaterial suspension and then were processed into tapes or yarns. Individual hemp and flax fibers where also soaked in the same suspensions and dried. SEM microscopy of the surfaces and cross-sections of the yarns and tapes showed that cellulose nanomaterial suspensions affected the morphology of the natural fiber yarns and tapes by filling gaps and adhering the fibers together. Results of studies on tensile properties of single fibers showed improvement in initial modulus and strength of flax fibers after soaking in nanocellulose suspensions especially when CNF was used. Such consistent results were not however seen for hemp single fibers. Yarns and tapes produced by soaking fiber strands in different nanocellulose suspensions had considerably higher tensile properties in terms of strength and initial modulus than controls. Furthermore, it was shown that mixing cellulose nanomaterial suspensions with natural fibers improved the dewatering/drying process, a necessary step should cellulose nanomaterials be used in composite applications.