RSC Advances
·
2016
·Vol. 6
·期 100
·97912-97920
·
IF 3.289
Chuanting Liu,Ziqiang Shao,Jianquan Wang,Chengyi Lu,Zhenhua Wang
A novel eco-friendly polyvinyl alcohol/cellulose nanofiber–Li+ (PVA/CNF–Li) composite separator was prepared for lithium-ion batteries. In this membrane by a non-solvent induced phase separation (NIPS) wet-process, CNF–Li originating from wood pulp was successfully prepared and characterized by FT-IR and TEM. The composite separators showed excellent porosity of over 60%, and better ionic conductivity (∼1.1 mS cm−1) as well as remarkable electrolyte uptake approaching 2.3. CNF–Li combined the excellent properties of both nanofibers and ion-conductive polymers such as CMC–Li. The introduction of CNF–Li in the separator increased the thermal dimensional stability and mechanical performance. Simultaneously, CNF–Li as a constituent in the membrane increased the contents of Li+, opening a way for Li+ transportation to improve batteries' Li+ diffusion efficiency and specific capacity. The battery with a 2 wt% CNF–Li separator retained 93% of the initial reversible capacity after 50 cycles, which was much higher than that of the commercial polypropylene (PP) separator with a value of 80%. The PVA/CNF–Li composite membrane produced via a relatively low cost and eco-friendly method can serve as a potential alternative of commercial PP separators applied in high-performance lithium-ion batteries.
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Materials
·
2017
·Vol. 10
·期 6
·572
·
IF 2.654
Chao Li,Qingde Li,Xiaohui Ni,Guoxiang Liu,Wanli Cheng,Guangping Han
A modified coaxial electrospinning process was used to prepare composite nanofibrous mats from a poly(methyl methacrylate) (PMMA) solution with the addition of different cellulose nanocrystals (CNCs) as the sheath fluid and polyacrylonitrile (PAN) solution as the core fluid. This study investigated the conductivity of the as-spun solutions that increased significantly with increasing CNCs addition, which favors forming uniform fibers. This study discussed the effect of different CNCs addition on the morphology, thermal behavior, and the multilevel structure of the coaxial electrospun PMMA + CNCs/PAN composite nanofibers. A morphology analysis of the nanofibrous mats clearly demonstrated that the CNCs facilitated the production of the composite nanofibers with a core-shell structure. The diameter of the composite nanofibers decreased and the uniformity increased with increasing CNCs concentrations in the shell fluid. The composite nanofibrous mats had the maximum thermal decomposition temperature that was substantially higher than electrospun pure PMMA, PAN, as well as the core-shell PMMA/PAN nanocomposite. The BET (Brunauer, Emmett and Teller) formula results showed that the specific surface area of the CNCs reinforced core-shell composite significantly increased with increasing CNCs content. The specific surface area of the composite with 20% CNCs loading rose to 9.62 m2/g from 3.76 m2/g for the control. A dense porous structure was formed on the surface of the electrospun core-shell fibers.Keywords:cellulose nanocrystals;coaxial electrospinning;core-shell structural nanofibers;thermal properties;fiber morphology
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PubMed
高影响因子
ENERGY & FUELS
·
2016
·
IF 2.835
Shurong Wang,Haizhou Lin,Li Zhang,Gongxin Dai,Yuan Zhao,Xiaoliu Wang,Bin Ru
Cellulose and hemicellulose were isolated directly from softwood Pinus armandii Franch by the alkali method for pyrolysis mechanism study. Structural characterization based on FTIR, 1H NMR, and 13C NMR showed that the hemicellulose was mainly composed of galactoglucomannan and arabinoxylan with abundant branches, while the cellulose was mainly composed of β-1,4-glucan with a few residual hemicellulose fragments. Pyrolysis of extracted cellulose showed high char yield due to the lower crystallinity. Hemicellulose pyrolysis showed a shoulder peak at low temperature and high char yield because of its abundant branches. A double-Gaussian distributed activation energy model was introduced for pyrolysis kinetics analysis. The devolatilization process for both cellulose and hemicellulose was dominated by a parallel decomposition reaction pathway. The distributions of their pyrolysis products were analyzed by Py-GC/MS. It is suggested that the utilization of isolated sample as model compound could give a better understanding of the biomass pyrolysis mechanism.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2017
·
IF 3.671
Weijuan Huang,Yingfei Zhan,Xiaowen Shi,Jiajia Chen,Hongbing Deng,Yumin Du
Electrospinning is a facile method to fabricate nanofibers, in terms of their high specific surface area and porous structure. Electrospun nanofibrous mats are excellent candidates for immobilization of enzymes . In this study, a simple route based on electrospinning and layer-by-layer (LBL) self-assembly processes has been developed to prepared naringinase/alginate multilayer coated electrospun cellulose acetate nanofibers. The content of immobilized naringinase could be tuned by adjusting the number of multilayers. XPS results indicated that naringinase was successfully immobilized on cellulose acetate nanofibers. SEM images showed the nanofibers maintain their sharp but became rougher after multilayer coating. Besides, the surface area of electrospun cellulose acetate nanofibers decreased and mesopores reduced. The major bitter components of grapefruit juice are naringin and limonin, naringin could be slightly removed by hydrolysis with naringinase and limonin might be removed by adsorption with cellulose acetate nanofibers.
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高影响因子
CELLULOSE
·
2016
·Vol. 23
·期 2
·1375-1382
·
IF 3.195
Li Qing,Chen Wenshuai,Li Yanna,Guo Xiaoyu,Song Shan,Wang Qingwen,Liu Yixing,Li Jian,Yu Haipeng,Zeng Jie
This article describes the comparative study of the structure, mechanical and thermomechanical properties of cellulose nanopapers with different thicknesses. Cellulose nanopapers were fabricated by vacuum-filtering cellulose nanofiber (CNF) suspensions. The surfaces of the nanopapers consisted of long and entangled CNFs (10–30 nm in width) and their aggregates, while cross-sections exhibited parallel aligned lamellar structures. The nanopaper thickness can be tailored by controlling the amounts of CNF suspensions used for filtration. Owing to the packing density of CNFs, nanopapers with different thicknesses had similar densities of ~1.50 g cm −3 . The thin nanopapers were transparent and flexible. With increasing thickness, the Young’s modulus of the nanopapers slightly decreased, while the ultimate strain and work of fracture increased. The thicker nanopapers displayed higher storage and loss modulus. The nanopapers still kept advantageous mechanical properties even at high temperatures around 260 °C because of the high thermal stability of CNFs and their strong entangled web-like structures.
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高影响因子
CARBOHYDRATE POLYMERS
·
2016
·
IF 4.219
Dawei Hua,Zhongche Liu,Fang Wang,Buhong Gao,Fei Chen,Qilu Zhang,Ranhua Xiong,Jingquan Han,Sangram Keshari Samal,Stefaan C. De Smedt,Chaobo Huang
In this study we present the use of co-axial electrospinning to produce core-shell composite micro-/nano- fibers of polyurethane (PU) and cellulose acetate phthalate (CAP). The designed fibers possess enhanced mechanical properties with a tensile strength of 13.27 ± 2.32 MPa, which is a clear improvement over the existing CAP fibers that suffer from a poor mechanical strength (0.2 ± 0.03 MPa). The CAP imparts pH responsiveness to the core-shell structure giving the fibers potential for “semen sensitive” (intravaginal) drug delivery.
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高影响因子
ACS Sustainable Chemistry & Engineering
·
2016
·
IF 5.267
Yao Tan,Yongzhuang Liu,Wenshuai Chen,Yixing Liu,Qingwen Wang,Jian Li,Haipeng Yu
Cellulose nanocrystal has been widely used as a reinforcement filler in waterborne coatings, but the application of cellulose nanofiber (CNF) as a filler is difficult because of inhomogeneous dispersion. Herein, a facile and effective strategy to improve the dispersion of CNFs in the polymer matrix by mixing with γ-aminopropyltriethoxysilane (APS) is presented. The APS dosages 0.08–0.48 wt % to 0.3 wt % CNFs were investigated, and the dosage 0.16% was found to achieve a superior stability of CNFs in the aqueous solution. The APS(0.16%)-modified CNFs were then incorporated and demonstrated distributing uniformly in the waterborne acrylic coating. The as-prepared coatings retain high light transmittance around 90%, and display improved mechanical properties. The composite coatings show a maximum 500% improvement in Young’s modulus, two-level improvement in hardness, and 35% reduction in abrasion loss as compared with those of neat coating. These results reveal that APS modification induces the homogeneous dispersion of CNFs in aqueous solution, and turns the CNF into an ideal reinforced filler for waterborne coatings.
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GREEN CHEMISTRY
·
2016
·Vol. 19
·期 3
·682-691
·
IF 8.506
Naixu Li,Yu Zheng,Lingfei Wei,Hongcheng Teng,Jiancheng Zhou
Although the conversion of cellulose to polyols is currently well-developed, the production of the considerably valuable ethylene glycol (EG) is still challenging. Reactions have long relied on the design of suitable catalysts to obtain a high selectivity and yield of EG. Herein, using well-shaped rectangular tungsten trioxide nanosheets as the substrate, we investigated the catalytic performances of various metal supported catalysts for the convertion of cellulose to EG. Results show that Ru/WO3 is more favorable for EG production, with the highest EG yield of 76.3% over the 1% Ru/WO3 nanosheet catalyst. Our characterizations and activity tests suggest that the embedding of Ru nanoparticles onto the WO3 nanosheets produces more W5+ active sites under the same reduction conditions (NaBH4 or H2), which act as Lewis base sites to promote the glucose retro-aldol condensation reaction. Moreover, the Ru/WO3 catalyst holds a portion of Ru in the form of amorphous RuOxδ+ phases, which could further increase the H+ released into an aqueous solution for cellulose hydrogenolysis. A possible catalytic mechanism for this hydrogenolysis process is accordingly proposed.
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RSC Advances
·
2016
·Vol. 6
·期 93
·90126-90131
·
IF 3.289
Yaqin You,Haoran Zhang,Yingliang Liu,Bingfu Lei
A novel fluorescent phosphor consisting of cellulose and carbon dots (CDs) has been successfully prepared for temperature sensing by the inverse microemulsion method for the first time. Cellulose is dissolved in N-methylmorpholine-N-oxide at high temperature, which can destroy the hydrogen bonds among the cellulose molecules and activate hydroxyls. At the same time, some of the hydroxyl groups are gradually oxidized to carboxyl in this process, which effectively reacts with the CDs, whose surface is functionalized by lots of amide groups. The result from Fourier-transform infrared spectroscopy confirms that there is strong interaction between cellulose and the CDs due to the formation of carbon–nitrogen bonds through dehydration–condensation reactions. In addition, the composite phosphor retains the inherent properties of individual CDs and emits 450 nm blue light, however an interesting excitation dependent phenomenon is observed. Finally, the temperature dependent fluorescent properties of the cellulose/CDs phosphors have been investigated from 200 to 420 K. After liner fitting, the correlation coefficient is calculated to be about 0.99, thus this novel phosphor is expected to be applied in temperature sensing.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2016
·
IF 3.138
Jiao Lu,Ru-Na Jin,Chao Liu,Yan-Fei Wang,Xiao-kun Ouyang
A novel magnetic carboxylated cellulose nanocrystal composite (CCN-Fe 3 O 4 ) was prepared as an adsorbent for the adsorption of Pb(II) from aqueous solution. The new adsorbent was characterized by transmission electron microscopy, vibrating sample magnetometry, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Batch experiments were carried out to investigate the effects of contact time, adsorbent dose, pH, and temperature on adsorption capacity. Pb(II) adsorption onto CCN-Fe 3 O 4 reached equilibrium in 240 min, and the maximum adsorption capacity of Pb(II) was 63.78 mg g −1 at 298.2 K. The equilibrium data fitted the Langmuir isotherm model better than the Freundlich isotherm model, and they were well explained in terms of pseudo-second-order kinetics. Thermodynamics studies indicated that the adsorption of Pb(II) onto CCN-Fe 3 O 4 was spontaneous and endothermic in nature. The adsorbent could also be regenerated with acid treatment and successfully reapplied.
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高影响因子
Waste and Biomass Valorization
·
2016
·Vol. 8
·期 4
·1303-1311
·
IF 0.915
Wei W. Q.,Wu S. B.
Conversion of eucalyptus cellulose into 5-hydroxymethylfurfural (5-HMF) by using Lewis acid catalyst in biphasic system was investigated in this study. The results show that the tetrahydrofuran/water biphasic system was more conducive to convert the eucalyptus cellulose into 5-HMF comparing to the single aqueous system. InCl 3 , a water-compatible Lewis acid, has the best catalytic effect. The highest yield of 5-HMF from eucalyptus cellulose is up to 45.05 mol%, which is a slight higher than that from microcrystalline cellulose. It can be ascribed to the lower crystallinity of isolated eucalyptus cellulose. The optimum conditions for catalytic conversion of eucalyptus cellulose into 5-HMF are at 200 °C for 2 h with 10 % InCl 3 dosage. Additionally, the effect of recycling the whole biphasic system which contains InCl 3 , NaCl, H 2 O and THF indicated that the 5-HMF yield was gradually decreased as the cycle times increased, the possible reason could be due to the loss of partial InCl 3 catalyst during the separation and distillation process.
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RSC Advances
·
2016
·Vol. 6
·期 81
·77499-77506
·
IF 3.289
Kai Zhang,Shubin Wu,He Yang,Huimin Yin,Gang Li
As promising and environmentally friendly catalysts, tungsten-containing heteropoly acids combined with supported noble metals were used for one-pot hydrothermal conversion of cellulose into polyols in the presence of pressurized hydrogen. The microcrystalline cellulose was completely converted over a mixed catalyst consisting of a low concentration of phosphotungstic acid (PTA) (0.03 wt%) and Ru/activated carbon (Ru/AC) via an one-pot hydrothermal reaction, with an ethylene glycol (EG) yield of up to 53.1% under optimal conditions. The catalytic activity of the mixed catalyst gradually decreased with increasing reaction runs, which could be mainly ascribed to the aggregation of Ru/AC particles, and to the coverage of the active sites of Ru due to the deposition of organic materials. Cellobiose was used as a model feedstock for a comparative study on the reaction pathways of the conversion of cellulose, and the results revealed that catalytic conversion of cellobiose consisted of at least three important parallel reactions under the present hydrothermal conditions, which were also most likely involved during the catalytic conversion of cellulose for EG production. Effective control of these reactions would be helpful to further maximize the EG yield during the catalytic conversion of cellulose.
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危险品化学品经营许可证（带存储）