COMPOSITE INTERFACES
·
2014
·
IF 0.701
Lian-zhen Ren,Peng-gang Ren,Xiao-liang Zhang,Zhen-feng Sun,Yuan Zhang
Regenerated cellulose (RCE)/poly(vinyl alcohol) (PVA) composite hydrogels were successfully prepared via physical repeated freezing and thawing method. The structure and properties of the RCE/PVA composite hydrogel were investigated by Fourier transform infrared spectrum, scanning electron microscopy, mechanical and swelling tests. The results revealed that a novel compact dual-network structure was formed between the cross-linked cellulose network and PVA matrix, which can strongly enhance the mechanical properties of the composite hydrogels as expected. Compared with neat PVA hydrogels, a 611% increase in tensile strength of RCE/PVA composite hydrogel from 0.09 to 0.64 MPa and 643% improvement in compressive strength from 0.07 to 0.52 MPa were achieved with the addition of 4 wt% of cellulose. The presence of cellulose is also beneficial to the elasticity of PVA hydrogels. With the incorporation of RCE, the composite hydrogels perform better shape recovery after compression test. Moreover, the addition of RCE has improved the swelling, water-absorbing, and water-retaining properties of the PVA hydrogels significantly.
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DESALINATION
·
2014
·
IF 3.96
Ling-Ling Shao,Quan-Fu An,Yan-Li Ji,Qiang Zhao,Xue-San Wang,Bao-Ku Zhu,Cong-Jie Gao
Sulfated carboxymethyl cellulose (SCMC) with tailored amount of sulfate groups was synthesized, and their composite nanofiltration membranes (SNFMs) were prepared by solution casting onto polysulfone (PSF) supporting membrane and crosslinking by glutaradehyde (GA). Chemical structure and composition of SCMCs and SNFMs were characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. SNFM surfaces were examined by field emission scanning electron microscopy , water contact angle and streaming potential measurement. The effects of the chemical composition on the hydrophilicity , the surface charge and the nanofiltration performance of SNFMs were determined. It is found that the incorporation of sulfate groups improves the water permeability of SNFMs while retaining their salt rejection. For the feed mixture of aqueous Na 2 SO 4 (1.0 g L − 1 , pH = 6.5), the optimum water flux is 39.6 L m − 2 h − 1 , which is 2.2 times of the pristine SNFM-0. For the xylenol orange (XO) dye solution (0.1 g L − 1 , pH = 4.0), the flux of SNFM-3 (30.0 L m − 2 h − 1 ) is also higher than that of SNFM-0 (11.1 L m − 2 h − 1 ). In addition, SNFM-3 exhibits good separation performance and chemical stability in treating saline anionic dye aqueous solution (MYB/NaCl) in acidic conditions.
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JOURNAL OF CARBOHYDRATE CHEMISTRY
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2014
·
IF 1.183
Hongxia Liu,Xiaojian Li,Shiqi Wang,Shaojun Huang,Chun Wei,Jian Lv
Microcrystalline cellulose extracted from sisal fibers (SFMCC) and octa-aminopropyl polyhedral oligomeric silsesquioxane (POSS-NH2) were used to fabricate POSS/SFMCC hybrids through a simple cross-linking process with epichlorohydrin as the cross-linking agent. The chemical structure and morphology of hybrids are characterized with FTIR spectra, X-ray diffraction, and SEM. The results present that POSS-NH2 has been grafted onto the surface of SFMCC. The thermal property of hybrids has been improved with a 19°C higher maximum thermal decomposition temperature than SFMCC, as measured by TGA and DSC. The residual mass of hybrids and SFMCC were 15.6 wt% and 4.4wt% at 700°C, respectively.
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CELLULOSE
·
2015
·Vol. 22
·期 4
·2341-2348
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IF 3.573
Rao Xianmeng,Kuga Shigenori,Wu Min,Huang Yong
Ball mill-assisted surface-fluorination of cellulose nanofiber was studied for two solvents with different polarity as dispersion/reaction medium. Milling cellulose in neat toluene gave irregular-shaped decrystallized cellulose particles; addition of pentafluorobenzoyl chloride (PFBC) to the system gave partially fluorinated cellulose as thin flakes with smooth surfaces, which maintained original crystallinity. Milling in neat dimethyl formamide (DMF) caused partial dispersion of nanofibers without decrystallization; milling in PFBC/DMF gave more enhanced dispersion of surface-fluorinated nanofibers. Both fluorinated materials were hydrophobic, with water contact angles of 103°–113°. Bulk degree of esterification was 0.20 for toluene and 0.57 for DMF systems. These results show characteristic influences of solvent species in reactive ball milling of cellulose in terms of fibrillation and surface esterification of nanofibers.
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RSC Advances
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2015
·Vol. 5
·期 18
·13878-13885
·
IF 3.84
Dong Yang,Xinwen Peng,Linxin Zhong,Xuefei Cao,Wei Chen,Sha Wang,Chuanfu Liu,Runcang Sun
Cellulose nanocrystals (CNCs) pre-grafted with polymerizable groups have been used as nano crosslinking joints and nano reinforcements to synthesize highly-elastic hydrogels. However, the polymerizable CNCs usually have dispersion problems during hydrogel fabrication because of the hydrophobicity of the grafted polymerizable groups. In this study, TEMPO oxidation was successfully utilized to overcome this problem by introducing more hydrophilic groups on the CNCs surface, facilitating their homogeneous distribution in aqueous solution and hydrogels. Furthermore, AC and UC gels crosslinked by CNCs that were pre-grafted with acryloyl chloride (AC) and 10-undecylenoyl chloride (UC) on their surfaces were fabricated for finding out a more effective way to synthesize stronger nanocomposite hydrogels. The results showed that UC gels showed both higher tensile strength and higher elongation than the corresponding AC gels. It was shown that UC gels, which had longer grafted carbon chain lengths on CNC surfaces, possessed a better energy dissipation capacity under stretching than AC gels. The water swelling ratios of UC gels (13.0–36.7 g g−1) were also much higher than those of the corresponding AC gels (11.2–21.0 g g−1) as a result of larger spaces to hold water in the hydrogel network. This work gives an insight into the influence of carbon chain length on the properties of CNC crosslinked nanocomposite hydrogels, and provides an effective way to fabricate nanocomposite hydrogels with higher mechanical strength.
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RSC Advances
·
2014
·Vol. 4
·期 86
·45753-45759
·
IF 3.708
Haiyan Wang,Yutong Gong,Yong Wang
Carbon aerogels have attracted considerable attention in fundamental investigation and potential applications in a myriad of fields. We present a novel approach for the synthesis of cellulose-based carbon aerogels by dissolution, gelation, regeneration, freeze-drying and carbonization of cellulose. The carbon aerogels obtained here possess the characteristics of high surface area (500 m2 g−1), hydrophobicity, and fire-resistance. In addition, the carbon aerogels show excellent adsorption capacity and selectivity for removal of oils, organic solvents, a variety of dyes, and heavy ions, so they could be used as promising adsorbents for sewage treatment. Especially for malachite green and Cu(II), the adsorption capacities can reach up to 1947 mg g−1 and 801 mg g−1, respectively, which far surpass other aerogels previous reported.
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APPLIED CATALYSIS A-GENERAL
·
2015
·
IF 3.942
Gang Xu,Aiqin Wang,Jifeng Pang,Mingyuan Zheng,Jianzhong Yin,Tao Zhang
Cellulose is the most abundant biomass in nature, and its catalytic conversion to commodity chemical ethylene glycol represents an important advance towards sustainable chemistry. In previous work, we have shown that tungstic acid plays a key role in selective C–C cleavage to form glycolaldehyde and then ethylene glycol. To further enhance the efficiency of tungstic acid, a series of additives were investigated in this work. Among various acid additives, H 2 SO 4 stands out as the most remarkable additive; ethylene glycol yield was enhanced from 32.6% to 52.6% at a H 2 SO 4 /H 2 WO 4 molar ratio of 0.03 and a H 2 WO 4 /cellulose weight ratio of 0.05, that is, an extremely dilute acid concentration. Weakly acidic sulfates (e.g., CuSO 4 and FeSO 4 ) have also been demonstrated to be highly efficient additives to improve the catalytic efficiency of tungstic acid, through promoting the hydrolysis of cellulose.
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POLYMERS FOR ADVANCED TECHNOLOGIES
·
2015
·Vol. 26
·期 11
·1351-1355
·
IF 1.757
Deming Zeng,Jian Lv,Chun Wei,Chuanbai Yu
Sisal is a natural material and a potential additive to reinforce composites. In this paper, sisal fiber cellulose microcrystalline (SFCM) was obtained from sisal fiber, and SFCM/unsaturated polyester (SFCM/UPR) in-situ resins were prepared via in-situ polymerization. Moreover, SFCM/UPR composites were produced with methods of rolling and molding. Effect of SFCM on dynamic mechanical properties of composites was studied. It is demonstrated that SFCM could significantly improve the dynamic mechanical properties of composites; the effect is closely related with the amount of SFCM, its dispersion in UPR matrix, and interfacial interaction. When the content of SFCM was 3 wt%, at 50°C, the storage modulus of SFCM/UPR composite was 33.22% higher than that of pure UPR. In addition, the glass transition temperature (T g ) was shifted to a higher temperature by 7.5°C, and loss modulus was decreased by 16.24%. The equilibrium value of relaxation modulus at 120 min was 30.52% higher than that of pure UPR composite. Besides, the equilibrium value of creep strain at 120 min was decreased by 41.61% compared with pure UPR composite. Copyright © 2015 John Wiley & Sons, Ltd.
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CARBOHYDRATE POLYMERS
·
2014
·
IF 3.916
Qingyuan Niu,Kezheng Gao,Wenhui Wu
A cellulose nanofibril film is modified by chemical assembly of boronate-terminated conjugated polymer chains at its specific sites, C-6 carboxyl groups. The modified cellulose nanofibril film is used as a fluorescent sensor for nitroaromatic vapor. Thanks to the specific reactive sites, numerous loose cavities or pathways located in the film sensor's out-layer have been formed, and the fraction of easily accessible cavities of the novel fluorescent film sensor is up to 0.97, which could benefit the penetration and diffusion of analyte vapor. Therefore, the novel fluorescent film sensor exhibits high sensitivity toward nitroaromatic vapor with a fast response. The fluorescence quenching efficiency of the chemical-assembly film sensor is about 3 times larger than that of the spin-cast film sensor using the same conjugated polymer for 600 s exposure to DNT vapor. In addition, the novel fluorescent film sensor shows good reversibility.
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PubMed
高影响因子
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
·
2013
·
IF 3.187
Yueling Cao,Junwei Wang,Maoqing Kang,Yulei Zhu
Ni–WO 3 /SBA-15 catalysts were prepared by an impregnation way and applied to the hydrogenolysis of cellulose in aqueous solution. The effect of nickel and WO 3 loading, catalysts reduction temperature and time on cellulose conversion were investigated. Up to 70.7% ethylene glycol yield was obtained over 3%Ni–15%WO 3 /SBA-15 catalysts. Several physicochemical methods such as XRD, Raman spectroscopy, NH 3 -TPD, H 2 -TPR and XPS were used to determine the character of catalysts. Based on these studies, it was found that there was a strong electronic interaction between NiO and WO 3 , which not only promoted the reduction of WO 3 , but restrained the reduction of NiO. Together with the experimental results, it can be concluded that the WO 3− X , which may be the active species for the selective cleavage of C C bond, was formed after catalysts pretreatment process. Additionally, a possible catalytic mechanism was proposed.
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GREEN CHEMISTRY
·
2013
·Vol. 16
·期 4
·1854-1864
·
IF 6.828
Juan Yu,Yupeng Liu,Xiaohuan Liu,Chunpeng Wang,Jifu Wang,Fuxiang Chu,Chuanbing Tang
A class of sustainable and renewable cellulose–rosin copolymers were prepared by immobilizing rosin-derived polymer chains on the backbone of ethyl cellulose (EC) by “grafting from” atom transfer radical polymerization (ATRP). Four different rosin based polymers derived from dehydroabietic acid (DA), one of the major resin acids in natural rosin, were attached to 2-bromoisobutyryl-functionalized EC. Meanwhile, DA-grafted EC was prepared by the simple esterification reaction between DA and EC. Kinetic studies showed that the polymerization of all monomers was controlled. These grafted copolymers adopt a worm-like or rod-like structure in tetrahydrofuran, verified by light scattering experiments. These copolymers have a tunable glass transition temperature and higher thermal stability in contrast to EC. Surface morphology by AFM analysis indicated good film-forming property when rosin polymers were grafted from EC. Additionally, the introduction of DA and rosin polymers remarkably enhanced the hydrophobicity of EC. The static contact angles of all these modified copolymers are above 90°. XPS analysis revealed that the surface of these rosin-modified EC copolymers was dominated by a hydrocarbon-rich rosin moiety. The UV absorption of modified EC composites is indicative of their potential application in UV-absorbent coating materials.
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IRANIAN POLYMER JOURNAL
·
2015
·Vol. 24
·期 9
·747-758
·
IF 1.806
Gao Xin,Chen Keli,Zhang Heng,Yan Xuejing
A rapid microwave-assisted cationic synthesis of cellulosic polymer by grafting glycidyl trimethyl ammonium chloride (GTMAC) onto parenchyma cellulose (PC) from bagasse pith under low-power condition is reported. The effects of the microwave power, exposure time, GTMAC charge, water content, and aqueous-organic solvents by volume ratio were evaluated by determining cationization parameters such as yield, degree of substitution (DS), zeta potential, and charge density. The experimental results showed that the water-soluble and -insoluble fractions of cationic parenchyma cellulose (CPC) were obtained and their optimal DS were determined to be 0.72 and 0.63 at the microwave power of 100 W for 20 min, respectively. Surface cationization of PC resulted in an increase in zeta potential and charge density over the unmodified cellulose. In comparison with the original PC, the intrinsic viscosity of the cationic products decreased significantly. The presence of GTMAC on the surface of PC was confirmed by Fourier transform infrared spectroscopy. The crystallinity and surface structure of original cellulose and CPCs were also analyzed through X-ray diffraction and scanning electron microscopy, respectively. This work provided an efficient and economical feasibility to produce a cationic biopolymer from cellulose.
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