Gaiyun Li

An Efficient Method for Cellulose Nanofibrils Length Shearing via Environmentally Friendly Mixed Cellulase Pretreatment

Cellulose nanofibrils (CNFs) have potential applications in the development of innovative materials and enhancement of conventional materials properties. This paper focused on the mixed cellulase hydrolysis with major activity of exoglucanase and endoglucanase on the cellulose length shearing. By the cooperation of two-step production route, including (1) enzymatic pretreatment using cellulase from Trichoderma viride and (2) mechanical grinding twice, a shorter cellulose nanofiber was fabricated. The influence of enzymatic charge and hydrolysis time on cellulose fibers was analyzed by using scanning electron microscopy (SEM), Fourier Transform Infrared Spectrometer (FTIR), and X-ray diffractometer (XRD). SEM images revealed that the surface morphology change, effective diameter sharpening, and length shearing of cellulose fibers are as a result of cellulase hydrolysis. The XRD suggested that the cellulase acted on the amorphous regions more strongly than the crystalline domains during layer-by-layer hydrolysis. The enzymatic charge and hydrolysis time significantly affected the yields and hydrolysis products concentration. The enzymatic pretreatment assisted mechanical grinding could improve the uniformity of CNF and helped to obtain CNF with exact length according to the requirement for special applications.

Use of near-infrared spectroscopy for prediction of biomass and polypropylene in wood plastic composites

Abstract The ratio of biomass to plastic in wood plastic composites (WPCs) is very important for the development of WPCs. This paper investigates the feasibility of predicting the biomass and polypropylene (PP) contents in three WPC species (Chinese fir/PP, poplar/PP and bamboo/PP) using near-infrared (NIR) spectroscopy combined with partial least squares regression (PLS). Several spectra pretreatments were applied to improve the models. Compared to other methods, baseline correction data processing gave the optimal model. The results of external validation showed that the coefficient of determination (R2), root mean square error of prediction (RMSEP) and the ratio of the standard deviation in the validation set to the RMSEP (RPD) were 0.930, 1.944 and 3.578 for biomass and 0.930, 1.958 and 3.587 for PP, respectively. It is concluded that NIR in combination with PLS is capable of reliable quantification of biomass and PP in a diversity of PP-based WPCs.

Effect of high residual lignin on the properties of cellulose nanofibrils/films

This work focused on an eco-friendly and facile method to produce lignocellulose nanofibrils (LCNFs) by the one-step grinding of original poplar wood. An array of detailed characterizations were performed to elucidate the effect of the residual lignin (22.1, 14.1, 8.2, 2.0, 0.4 and 0.2%) on the properties of LCNFs and its films. The LCNFs were rather sensitive to ultraviolet absorption, low-viscosity and anti-degradation properties. Morphological observations suggested that lignin particles homogeneously attach to the surface of cellulose nanofibrils for higher-residual-lignin samples. The results of chemical structures analysis demonstrated an effect of residual lignin amounts on the CrI. Further, the LCNF nanofilms exhibited enhanced hydrophobicity and mechanical properties. Overall, LCNFs are a renewable material with low environmental impact, low cost and they are being manufactured at a largescale. They also offer potential for a wide range of applications, such as ultraviolet protection, anti-degradation, and valuable reinforcing composite materials.Graphical Abstract