Lifang Liu

Enzymatic treatment of mechanochemical modified natural bamboo fibers

Natural bamboo fibers have attracted growing demands in textile industry due to benefit from their excellent properties and renewable and abundant resource; however, there are still limitations for their application in textile industry because of their poor quality. For this reason, enzymes treatments on mechanochemically modified natural bamboo fibers were conducted to extract noncellulosic matters from finer natural bamboo fibers in this paper. Four enzymes, pectin lyase, xylanase, laccase, and cellulase, were used to remove pectin, hemicellulose, lignin and to loosen the compact structure of fibers, respectively. Furthermore, the concentrations of four enzymes were optimized in terms of fiber chemical composition, weight loss, fineness, and tenacity to obtain high quality fibers. An obvious reduction in amount of noncellulosic substances and also a remarkable improvement in fineness in the modified fibers can be found from the experimental results. The optimum parameters are determined as: 0.6 % pectin lyase, 1.2 % cellulase, 0.3 % xylanase, and 1.2 % laccase; and the natural bamboo fiber thus obtained is 77.51 % in cellulose content, 2.81 tex in fineness, and 2.62 cN/dtex in tenacity.

Fabrication of cellulose nanocrystal from Carex meyeriana Kunth and its application in the adsorption of methylene blue

Cellulose nanocrystal (CNC) was extracted from Carex meyeriana Kunth (CMK) by a combination of TEMPO oxidation and mechanical homogenization method, and used to remove methylene blue (MB) from aqueous solution. After alkali-oxygen treatment, the aqueous biphasic system (polyethylene glycol/inorganic salt) was applied to further remove lignin from CMK. The characteriazation of CNC, and the effects of H2O2 dosage, CNC dosage, adsorption time, and initial MB concentration on the MB removal capacity of CNC were investigated. The results showed that the removal percentage of MB by CNC was raised with the increase of H2O2 and CNC dosage. The adsorption kinetics of prepared CNC followed the pseudo-second-order model, and the adsorption isotherms fitted well to the Langmuir model with a calculated maximum adsoption capacity of 217.4mg/g, which was higher than those of CNC extracted by acid hydrolysis method, indicating CNC extracted from CMK had promising potentials in the field of MB adsorption.

Optimal design of superfine polyamide fabric by electrostatic flocking technology

The use of superfine fibers as piles to produce flocked fabrics is underreported despite their excellent properties. Therefore, a superfine polyamide fiber was used for piles to produce flocked fabric in this study, and a full factorial design was employed with three design factors at three levels to optimize the process parameters in terms of flocking density. The flock density is found, experimentally, to increase with the decrease of flocking distance and the increase of field strength and flocking time. A ternary linear equation is also established in this study based upon the regression analysis on experimental results and verified by F-test showing that it has remarkable significance. Comparison with experimental values shows that the regression equation possesses high accuracy. The optimum parameters are empirically and experimentally determined as: flocking distance of 7 cm, field strength of 60 kV, and flocking time of 10 s.The use of superfine fibers as piles to produce flocked fabrics is underreported despite their excellent properties. Therefore, a superfine polyamide fiber was used for piles to produce flocked fabric in this study, and a full factorial design was employed with three design factors at three levels to optimize the process parameters in terms of flocking density. The flock density is found, experimentally, to increase with the decrease of flocking distance and the increase of field strength and flocking time. A ternary linear equation is also established in this study based upon the regression analysis on experimental results and verified by F-test showing that it has remarkable significance. Comparison with experimental values shows that the regression equation possesses high accuracy. The optimum parameters are empirically and experimentally determined as: flocking distance of 7 cm, field strength of 60 kV, and flocking time of 10 s.

Preparation and characterization of polysulfone membrane incorporating cellulose nanocrystals extracted from corn husks

Cellulose nanocrystals (CNCs) extracted from corn husks were used as additive to modify the hydrophilicity and anti-fouling properties of polysulfone (PSf) membrane. The PSf/CNCs blend membranes were prepared via an immersion phase inversion method. The influence of CNCs content on the morphology, structure, and performances of PSf membrane were carefully investigated by SEM, TG, DTG, DSC, break strength, elongation-at-break, Young modulus, contact angle and filtration experiment. The results showed that the isolated CNCs from corn husks were a promising additive for modifying the properties of PSf membrane. CNCs can improve mechanical property, thermal stability, hydrophilicity and anti-fouling performance of the pure PSf membrane. The PSf/CNCs blend membrane reached optimal properties at 2 wt% CNCs content, which was 2.76 and 1.57 times in pure water flux and FRR values respectively as compared to pure PSf membrane. Meanwhile, PSf-2 also can maintain a relatively high BSA rejection.

Study of the Tensile Properties of Jute / Cotton Blended Yarns Using Weibull Distributions

Jute fibre, a natural composite of cellulose, hemicellulose and lignin, occupies the second place to cotton in economic importance. Recently many attempts have been made to produce fine jute blended yarn with other textile fibres. In this paper, the two types of jute/cotton blended yarn whose jute and cotton fibres were respectively blended at the opening and drawing stages were spun by using the ring spinning technology. The tensile properties of both blended yarn at gauge lengths from 150 mm to 500 mm were investigated, and the evenness and imperfections for both blended yarn were also evaluated. The results show that the draw frame blended yarn was of better quality than the opener blended yarn. The breaking tenacities of both blended yarn increased with the decrease in the gauge length. The equations derived from two-parameter Weibull distribution and based on experimental strength at length of 300 mm can predict the breaking strength of both blended yarn accurately. The scale effect study indicates t...

Filtration Performance Of Two-Layered Nonwoven Geotextiles

Nonwoven geotextiles have been widely used for separation, filtration, reinforcement and drainage systems. The filtration and drainage functions are especially attractive in the construction of soil structures. In this paper, five two-layered nonwoven geotextiles with different needling density have been developed to study their filtration performance. The experimental results show that needling density has obvious effects on the filtration performance of nonwoven geotextiles. Regarding the five samples in this study, the one with needling density of 470 p/cm2 has the best filtration performance.

Net shape preparation and bending properties of tapered three-dimensional braided composites

The yarn-reduction technique and the yarn-addition technique were introduced to net shape prepare tapered three-dimensional braided composites. Considering that the processes of yarn reduction and yarn addition were mutually inverse, this paper mainly shed light on the former. Two types of yarn-reduction process, the column yarn-reduction process and row unit yarn-reduction process, were discussed in the architectures of preforms thus formed and bending behaviors of corresponding composites. Results show that the principle of these two techniques is that the braiding rules should not be disturbed after yarn reduction or yarn addition. Orientation degrees and lengths of some rearranged yarns are increased in the second step after yarn reduction, whereas the other rearranged yarns only reverse their orientation directions, then the yarn trajectories are the same as before yarn reduction in subsequent steps. Bending properties of the row unit yarn-reduction composites are slightly higher than those of the column yarn-reduction composites and significantly better than the cut composites. The primary failure mechanism of the yarn-reduction composites is yarn breakage, while the dominant failure mechanisms of the cut composites are matrix cracking and interfacial debonding.