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Banana fiber-reinforced biodegradable soy protein
composites
Kumar Rakesh, Choudhary Veena, Varma Ik, Mishra Saroj
Front. Chem. China. 2008, 3 (3): 243-250.
https://doi.org/10.1007/s11458-008-0069-1
Banana fiber, a waste product of banana cultivation, has been used to prepare banana fiber reinforced soy protein composites. Alkali modified banana fibers were characterized in terms of density, denier and crystallinity index. Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were also performed on the fibers. Soy protein composites were prepared by incorporating different volume fractions of alkali-treated and untreated fibers into soy protein isolate (SPI) with different amounts of glycerol (25%–50%) as plasticizer. Composites thus prepared were characterized in terms of mechanical properties, SEM and water resistance. The results indicate that at 0.3 volume fraction, tensile strength and modulus of alkali treated fiber reinforced soy protein composites increased to 82% and 963%, respectively, compared to soy protein film without fibers. Water resistance of the composites increased significantly with the addition of glutaraldehyde which acts as crosslinking agent. Biodegradability of the composites has also been tested in the contaminated environment and the composites were found to be 100% biodegradable.
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Synthesis of 1,2-bis[2-methyl-5(3,4-difluorophenyl)-3-thienyl]perfluorocyclopentene
LIU Taiqi, YANG Liyan, YU Jianxiang
Front. Chem. China. 2008, 3 (3): 251-253.
https://doi.org/10.1007/s11458-008-0062-8
2-Methylthiophene (1) was treated at 0°C with liquid bromine to form 3,5-dibromo-2-methylthiophene (2) which reacted with tributyl borate to give 2-methyl-3-bromo-5-boronate thiophene (3) at -78°C. Treatment of 3 with 3,4-difluorobrombenzene gave 2-methyl-3-bromo-5-(3,4-difluorophenyl)thiophene (4). Finally, a novel photochromic dithienylethene compound, 1,2-bis[2-methyl-5(3,4-difluorophenyl)-3-thienyl]perfluorocyclopentene (DT-1), was synthesized by the reaction of 4 with perfluorocyclopentene at -78°C. The compound (DT-1) was characterized by IR, NMR, MS, elemental analysis and its photochromic behavior was also discussed.
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Thermodynamic analysis of fluorescence enhancement
and Quenching theory equations
YANG Manman, XI Xiaoli, YANG Pin
Front. Chem. China. 2008, 3 (3): 254-261.
https://doi.org/10.1007/s11458-008-0065-5
The action of the three kinds of new third generation cephalosporin-class drugs, cefepime hydrochroride, cefpiramide and ceftizoxime with HSA and BSA was studied at different temperatures through the fluorescence method. First, the binding constants were calculated by using fluorescence quenching and enhancement theoretical equations. Their thermodynamic functions were also calculated. Because the KA corresponding to the different theoretical equations are not completely the same, the thermodynamic parameters calculated are also different. In this paper, the differences among these thermodynamic data obtained from the different theoretical equations were analyzed and the results show that the thermodynamic data deduced from fluorescence enhancement are more reasonable. Thus, we propose that even when the fluorescence quenching action of the acceptor-substrate is studied, more realistic data can be obtained by using the fluorescence enhancement equation.
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Synthesis, characterization and photosensitivity
of tetrakis--(2-methyl-8-quinolinoxy)
metallophthalocyanines
XUE Jinping, LIU Hong, CHEN Naisheng, HUANG Jinling, FAN Changan, HONG Huming
Front. Chem. China. 2008, 3 (3): 267-274.
https://doi.org/10.1007/s11458-008-0058-4
Four amphipathic cobalt(II), nickel(II), copper(II), and zinc(II) coordination compounds of tetrakis-?-(2-methyl-8-quinolinoxy)phthalocyanine are synthesized using “DBU catalytic method”. The titled complexes are characterized by elemental analysis, mass spectra, UV-Vis, and IR spectra. In addition, the rates of photogenerated singlet oxygen and the rate constants of photodynamic oxidation of amino-acid substrate by the complexes are measured under the optical excitation at 670 nm, and the relations between their structures and their photosensitivities are discussed.
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Synthesis, crystal structure and magnetic properties
of bimetallic complex of NiCo(TTHA)?12HO
YANG Chun, XU Gongfeng, WANG Qinglun, LIAO Daizheng, LIU Bin
Front. Chem. China. 2008, 3 (3): 294-297.
https://doi.org/10.1007/s11458-008-0066-4
The bimetallic complex of Ni2Co(TTHA)12H2O (TTHA = triethylene tetraminehexaacetic acid) was synthesized and characterized structurally and magnetically. The title complex crystallizes in the triclinic space group P + with a = 0.7316(2), b = 0.8624(2), c = 1.5041(4) nm; ? = 73.38(2), ? = 83.97(2), ? = 70.50(2)°. The crystal structure is built up of [Ni2(TTHA)(H2O)2]2-, Co(H2O)62+ and water molecules. The variable magnetic measurement shows that there is strong antiferromagnetic interaction between two Ni(II) ions in [Ni2(TTHA)(H2O)2]2- with JNi-Ni = -141.64 cm-1, gNi = 2.21 and that the constant of spin-orbit coupling of Co(II) ion is -134.8 cm-1.
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Synthesis and characterization of three-arm star-shaped
polyethylene glycols with 1,1,1-trihydroxmethylpropane as cores
ZHOU Yongfeng, YAN Deyue, HUANG Wei, WANG Kangcheng
Front. Chem. China. 2008, 3 (3): 298-303.
https://doi.org/10.1007/s11458-008-0050-z
A small molecule core (TMP-SK3) with three terminal carboxyl groups was synthesized successfully by the reaction of 1,1,1-trihydroxymethylpropane with the excessive sebacic acid diacetic anhydride (SK). Then, the core molecule was used as a coupling agent to condensate with polyethylene glycols (PEG) of different molecular weights or polyethylene glycol monomethyl ether (PEGm) in the presence of stannous octoate as catalyst and diphenyl ether as an azeotropic agent to remove water. Thus, the three-arm star-shaped PEGs was obtained successfully and characterized by 1H-NMR, DSC, GPC and XRD etc.. DSC measurements indicate that the crystallizing and the melting temperatures of the three-arm star-shaped PEGs were different from those of the corresponding linear PEG because the existence of TMP-SK3 altered its crystallizing velocity and perfect degree of crystallization.
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Synthesis, crystal structure, and thermal properties
of -di(diethoxythiophosphoryl)-1,4-phenylenediamine
REN Yuanlin, CHENG Bowen, ZHANG Jinshu, ZANG Hongjun, KANG Weimin, DING Changkun
Front. Chem. China. 2008, 3 (3): 304-308.
https://doi.org/10.1007/s11458-008-0046-8
The title compound N,N′-di(diethoxythiophosphoryl)-1,4-phenyl- enediamine was synthesized by the reaction of diethoxythiophosphoryl chloride with p-phenylenediamine and characterized by elemental analysis, IR, and 1H NMR spectra. Its crystal structure was determined by X-ray diffraction analysis and the thermal property was studied by TG analysis. The relative molecular weight of the title compound is 412.42. The crystal structure belongs to the orthorhombic, Pbca space group, with a = 0.86936(16) nm, b = 1.2787(2) nm, c = 1.8897(3) nm, ? = 90°, V = 2.1006(7) nm3, Z = 8, Dc = 1.304 g/cm3, ?(Mo K?) = 0.425 mm-1, F(000) = 872, S = 1.052, the final R = 0.0628 and wR = 0.1860 for 1852 observed reflections with I > 2?(I). The X-ray diffraction analysis demonstrates that the crystal structure is centrosymmetric. The weak N–H...S intramolecular hydrogen bonds were observed to link the molecules into sheets. The TG analysis shows that the title compound has good thermal stability and char forming capability and its fire retardation for polyacrylonitrile reveals that the compound is an excellent intumescent fire retardant.
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Structure and properties of polymer modified
TiO pillared montmorillonite
WANG Chenjing, YU Jiang, XING Jianmin, LIU Huizhou
Front. Chem. China. 2008, 3 (3): 309-313.
https://doi.org/10.1007/s11458-008-0051-y
With the aim of improving the microstructures and properties of TiO2 pillared montmorillonite (MMT), a long-chain polymer (polyoxypropylenediamine, PPO-D 2000) was used as a template to synthesize composite pillared MMT. The materials were characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectrophotometer, Fourier Raman (FT-Raman) spectrophotometer, thermo-gravimeter/differential thermo-gravimeter (TG/DSC), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) methods. The results show that as compared to low-molecular weight surfactant, this polymer significantly expanded the interlayer spacing and thus more TiO2 could be intercalated into MMT. The specific surface area of polymer/TiO2 pillared MMT was increased by 13% with comparison to TiO2 pillared MMT and rose to 241.52 m2/g. Both the pore diameter and volume are doubled, and thus the pore structure is optimized markedly. The investigation on the photo-catalytic degradation of methyl orange in aqueous solution show that the modulation of polymer molecules raise the adsorption content of montmorillonite and improve the photo-catalytic activity. Therefore, this process provides a novel alternative to design and prepare the advanced eco-catalytic materials with high adsorption capacity and photo-catalytic activity.
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Swelling and drug releasing properties of poly(-isopropylacrylamide) thermo-sensitive copolymer
gels
PAN Chunyue, LONG Qingde, YU Dian, RAO Yanping, WU Nianqian, LI Xingcui
Front. Chem. China. 2008, 3 (3): 314-319.
https://doi.org/10.1007/s11458-008-0054-8
A series of N-isopropylacrylamide (NIPAAm) copolymer gels with different hydrophilicities were prepared from NIPAAm, hydrophilic acrylamide (AAm) and hydrophobic butyl methacrylate (BMA). The swelling and thermo-responsive properties of PNIPAAm P(NIPAm-co-BMA) and P(NIPAm-co-AAm) copolymer hydrogels were investigated. The drug loading and releasing behaviors for two kinds of model drug with different hydrophilicities were studied. The result shows that the copolymer gels present negative thermo-sensitivities. The lower critical solution temperature (LCST), equilibrium swelling degree and the initial swelling rate increase as the hydrophilicity of gels increases when the temperature is below the LCST. With increasing gel hydrophilicity the loading ratio for sodium salicylate increases, while for salicylic acid, the reverse is observed. The initial drug releasing rate of sodium salicylate and salicylic acid also increase with increasing gel hydrophilicity. The initial drug releasing rate of sodium salicylate is significantly higher than that of salicylic acid. For salicylic acid which is less hydrophilic, the equilibrium releasing ratio at high temperature is lower than that at low temperature while for sodium salicylate which is more hydrophilic, the equilibrium releasing ratio at high temperature is almost the same as that at low temperature. Equilibrium releasing ratios of the three gels are significantly different from each other for salicylic acid when the temperature is below LCST while the equilibrium releasing ratios of the three gels are all 100% for sodium salicylate.
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Synthesis of silica adsorbent and its selective
separation for flavone
ZHANG Yuqing, ZHANG Yahui, QIN Zhen, MA Zhenrong
Front. Chem. China. 2008, 3 (3): 320-324.
https://doi.org/10.1007/s11458-008-0052-x
One kind of built-in silica adsorbent, which has high adsorption selectivity to rutin, was synthesized using molecular imprinting technology by the following steps: synthesis of precursor from the reaction between water soluble rutin (as template molecule) and the functional monomer chloropropyltriethoxysilane, co-hydrolysis of the precursor and tetraethoxysilane (TEOS), sol-gel aging process, and removal of template molecules. The results of adsorption experiment show that this adsorbent has a high adsorption capacity for rutin, and good adsorption selectivity towards rutin even under the interference of a flavone with a similar structure. TEM photos suggest that nanocaves corresponding to rutin were formed inside the adsorbent while FTIR spectra indicate that new bond was generated during the recognition process.
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