Development of powdering method for cellulose nanofibers assisted by zinc oxide for compounding reinforced natural rubber composite

We have developed a unique powdering method for cellulose nanofibers (CNFs) that allows zinc oxide to function as a dusting powder for noodles at the nanoscale. A CNF slurry and zinc oxide as a rubber compounding ingredient were mixed and dried. The resultant CNF–zinc oxide mixture could be pulverized into a fine powder because submicron-order zinc oxide fine particles intercalated between the CNF fibers; that is, they suppressed the aggregation of the CNFs. The obtained CNF powder was almost uniformly dry-blended with solid natural rubber (NR) to obtain an NR/CNF mixture. The tensile strength of the NR/CNF composite prepared by vulcanizing the mixture with sulfur was improved compared with that of the NR (without CNF). In addition, the reinforcing effect of the composites improved with increasing length of the CNFs filled into the NR. [Display omitted] •We developed a new powdering method for cellulose nanofibers assisted by zinc oxide.•Zinc oxide intercalated between nanofibers to suppress the aggregation of nanofibers.•Cellulose nanofiber powder was uniformly dry-blended with solid natural rubber.•Tensile strength of composite was improved as compared with that of natural rubber.