Decrystallization of cellulose under the influence of elastomer-assisted mechanical and mechanochemical shear

摘要

Microcrystalline cellulose (MCC) was subjected to mechanical and mechanochemical shear in a rubber mixing milling. Nitrile rubber (NBR) and ethylene-propylene-diene monomer (EPDM) rubber were used to induce shear on cellulose during treatment. Solid-state interactions between N,N-dimethylacetamide/lithium chloride (DMAc/LiCl) and cellulose particles were facilitated during mechanochemical shear. Fourier transform infrared spectroscopy, X-ray diffraction analysis, thermogravimetric analysis, scanning electron microscopy and swelling studies were carried out on MCC, DMAc/LiCl-treated MCC, MCC subjected to mechanical shear and DMAc/LiCl-treated MCC subjected to mechanochemical shear. Crystallinity and swelling behaviour of the untreated and merely DMAc/LiCl-treated MCC samples, in the absence of any shear, were found to be similar. However, when MCC was subjected to mechanical shear assisted by NBR and DMAc/LiCl-treated MCC subjected to mechanochemical shear assisted by EPDM, the resultant MCC samples exhibited significant reduction in their crystalline index with increased swelling. When DMAc/LiCl-treated MCC was subjected to mechanochemical shear assisted by NBR and mechanical shear alone on MCC, assisted by EPDM, did not exhibit any appreciable change in the crystalline index and swelling behaviour of the resultant MCC samples. While NBR-assisted mechanical shear was found to reduce crystallinity in untreated MCC, crystallinity in DMAc/LiCl-treated MCC was found to be reduced significantly with EPDM rubber-assisted mechanochemical shear.