Surface modification of microcrystalline cellulose using rice bran oil: a bio-based approach to achieve water repellency

摘要

A bio-based approach for surface modification of microcrystalline cellulose (MCC) with hydrophobic property was achieved by chemical transesterification using rice bran oil (RBO) as a cheap and environmentally benign raw material. The pretreated MCC (UMCC) was uniformly distributed in a homogeneous mixture of RBO/ethanol emulsion. Surface acylation was enabled by solvent evaporation followed by heating. Acylation of UMCC (AUMCC) was analyzed by C-13 NMR, FTIR and acid-base titrations. Average acylation by titration method for AUMCC with 2 mL RBO at 110 degrees C for 30, 60, and 90 min was found to be 11.05, 13.26 and 15.39%, respectively. The stoichiometric and mass yield of AUMCC was found to be 80.9 and 70% respectively. C-13 solid-state NMR study proved the modification of UMCC. Percentage acylation by solid-state NMR was found to be 13.94% which is slightly lower than the average acylation by titration method i.e. 15.39%. The solubility of AUMCC in common organic solvents was examined and found to be soluble in pyridine and benzene solvent. The water contact angle of AUMCC reached 92.2 degrees, while the surface energy decreasing to 35.56 mN/m, and water uptake of 0.9 mL/mg was achieved. The thermal stability and crystallinity of AUMCC decreased with treatment time. The functionalization of these AUMCC can be useful in the preparation of composites.