All-cellulose composites based on wet-spun cellulose fibers reinforced with cellulose nanocrystals and halloysite nanoclay

Abstract The aim of the study was to develop biobased and lightweight composites with unidirectional cellulose fibers without a matrix polymer, so called all-cellulose composites with excellent mechanical properties. Continuous cellulose fibers are currently gaining interest for composite applications and if these fibers can be welded together without using a polymer resin it would result in an environmental friendly composite material. The regenerated fibers were prepared using wet spinning of DMAc/LiCl dissolved cellulose where cellulose nanocrystals (CNC) and halloysite nanotubes (HNT) were used as reinforcements. The loading of the nanomaterials into the dissolved cellulose was between 2 to 20 %. The preliminary results showed that the addition of both CNC and HNT improved the mechanical properties of the regenerated cellulose fibers. It was also seen that low concentration of the nanomaterials was more effective reinforcement than high concentration. Also, the HNT showed slightly better improvement compared to the CNC). The spun nanocomposite fibers were directly wound to a roll after the wet spinning, compression molded to composite sheet and dried. The all-cellulose composites mechanical properties as well as microstructure including nanomaterials orientation in the spun fibers were studied and composites mechanical properties are compared with theoretical models