Regulating the Function of Nanocomposite Made from Hydroxypropyl Methyl Cellulose with Bacterial Cellulose Nanocrystal

Hydroxypropyl methyl cellulose(HPMC)-based hybrid nanocomposites reinforced with bacterial cellulose nanocrystals(BCNC) were prepared and characterized.The HPMC nanocomposites exhibited good thermal stability,with a thermogravimetric peak temperature of around 346℃.The addition of BCNC did not significantly affect the thermal degradation temperature or improve the transparency of HPMC nanocomposites.However,the addition of BCNC favorably affected the light scattering properties of the nanocomposites and enhanced mechanical properties such as tensile stress and Young's modulus from 65 MPa and 1.5 GPa up to 139 MPa and 3.2 GPa,respectively.The oxygen permeability of the HPMC nanocomposites also increased with increase in the amount of BCNC added.

Effect of Enzyme-assisted Refining on the Properties of Bleached Softwood Pulp

Enzymatic pretreatment of pulp is demonstrated to be potentially effective for decreasing the energy consumption in the refining process.Herein,a neutral cellulase was utilized for the pretreatment of bleached softwood pulp in order to improve the refining performance.Cellulase pretreatment effectively improved the drainability of the pulp and could thus reduce the energy consumption in the refining process.The beating degree of the pulp was significantly improved at 6000 PFI revolutions,at which a maximum increase of 70% could be obtained.The water retention value(WRV) of the pulp increased by 17% after treatment with cellulase at a dosage of 5 IU/g,and the fibers could be easily torn apart after enzymatic treatment.To achieve the same beating degree,the refining time could be shortened by 80% when the pulp was treated with cellulase.Using a low dosage of cellulase,the freeness of the pulp increased rapidly without deterioration of the mechanical properties.

Effect of Acetic Acid Prehydrolysis on Unbleached Bamboo Pulp Production

Bamboo was used as raw material for unbleached pulp production.An acetic acid prehydrolysis process was employed before the pulping process.The effect of acetic acid prehydrolysis on pulp properties was investigated.The results showed that some components,such as hemicellulose and extractives,were degraded or dissolved in the prehydrolysis process prior to kraft pulping.SEM images of the substrate after treatment indicated that the parenchyma cell wall was thinner,and the size of pores between fiber bundle cell walls was larger.The pulping results showed that acetic acid prehydrolysis could improve the pulp quality and make the pulp easier to bleach.The brightness of the pulp reached 59.6%ISO with a single oxygen delignification step.The acetic acid prehydrolysis decreased pulp viscosity and fiber length,but not significantly.The amount of parenchyma cells in the pulp was reduced,which was beneficial for papermaking and improving mechanical strength of paper.This procedure has good potential for unbleached pulp production.