Insights into the production and physicochemical properties of oxycellulose microcrystalline with coexisting crystalline forms.

Oxycellulose microcrystalline (Oxy-MCC) was prepared utilizing nonwood agro-industrial residue, rice husk (RH), via consecutive soda delignification and non-acidic catalytic oxidation. The resultant Oxy-MCC, with a 31 wt% yield, has granular microstructured particles with an average diameter of 41.66 ± 4.11 µm. The porous morphology has been observed in Oxy-MCC micrographs, using scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) and TGA/DTG thermal analysis indicated the presence of typical cellulose characteristics, while the presence of carbonyl spectral peak signalized the efficacy of D-RH oxidation process. The x-ray diffraction (XRD) confirmed the coexistence of cellulosic crystalline forms of cellulose I and cellulose II with 84.8% crystallinity index. Significant growth of crystallite size was observed from 1.7 nm (RH) to 9.4 nm (Oxy-MCC). The maximum decomposition temperature (Tmax) was found to be 324 °C, thus indicating good thermal stability. Oxy-MCC showed, overall, attractive thermal and physicochemical properties for oxycellulose nanocrystalline (Oxy-NCC) production.

Microfibrillated Cellulose Suspension and Its Electrorheology.

Microfibrillated cellulose (MFC) particles were synthesized by a low-pressure alkaline delignification process, and their shape and chemical structure were investigated by SEM and Fourier transformation infrared spectroscopy, respectively. As a novel electrorheological (ER) material, the MFC particulate sample was suspended in insulating oil to fabricate an ER fluid. Its rheological properties-steady shear stress, shear viscosity, yield stress, and dynamic moduli-under electric field strength were characterized by a rotational rheometer. The MFC-based ER fluid demonstrated typical ER characteristics, in which the shear stresses followed the Cho-Choi-Jhon model well under electric field strength. In addition, the solid-like behavior of the ER fluid was investigated with the Schwarzl equation. The elevated value of both dynamic and elastic yield stresses at applied electric field strengths was well described using a power law model (~E1.5). The reversible and quick response of the ER fluid was also illustrated through the on-off test.

Fabrication of phosphate microcrystalline rice husk based cellulose particles and their electrorheological response.

As a dry-based electrorheological (ER) material, phosphate microcrystalline cellulose (MCC), which exhibits ER properties under anhydrous conditions, was fabricated by the phosphorylation of MCC particles. The MCC particles were initially synthesized by the three step preparation of an alkali treatment, bleaching, and hydrolysis of cellulose particles from rice husk. The phosphate MCC was then synthesized via the phosphoric ester reaction of urea with phosphoric acid and MCC, and its chemical characteristics were examined by energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. The phosphate MCC particles were dispersed in silicone oil to produce an ER fluid (10vol%), and its chain structure was observed directly by optical microscopy. The rheological behavior of the ER fluid was tested using a rotational rheometer under a range of electric fields, showing a polarization mechanism with a slope of 2.0 for the yield stress as a function of the applied electric field strengths.