Mechanochemical preparation of surface-acetylated cellulose powder to enhance mechanical properties of cellulose-filler-reinforced NR vulcanizates

Wood fibers composed mainly of cellulose were subjected to mechanochemical reaction with acetic anhydride to prepare surface-acetylated cellulose powder (SACP) through pan-milling in solid-state at ambient temperature. Fourier transform infrared spectroscopy and contact angle measurements confirmed the realization of chemical modification on the powder surface. Curing characteristics indicated that natural rubber (NR) compounds filled with SACP possessed better processability and scorch safety. The mechanical properties of vulcanizates, namely tensile strength, tear strength and modulus at 100%, 200% and 300% elongation increased with SACP, but elongation at break and hardness were less as compared to those of pristine cellulose fibers filled ones. NR vulcanizate combined with 30 phr SACP exhibited the most prominent mechanical properties, with tensile strength up to 14.5 MPa, elongation at break of 930%. The better filler dispersion and increased filler-matrix interfacial adhesion were mainly responsible for the improvement of mechanical properties of SACP filled vulcanizates.