Showing papers by "Lina Zhang published in 2004"
TL;DR: The results indicate that the strong interactions between fillers and between the filler and SPI matrix play an important role in reinforcing the composites without interfering with their biodegradability.
329 citations
TL;DR: New environment-friendly beads prepared by a simple produce process for removal and recovery of heavy metals are developed based on mainly complexation adsorption model as well as a affinity of hydroxyl groups of the materials on metals.
302 citations
TL;DR: In this paper, regenerated cellulose fibers have been successfully spun from the cellulose dope in NaOH/urea aqueous solution, which could rapidly dissolve cellulose.
Abstract: Novel regenerated cellulose fibers have been successfully spun from the cellulose dope in NaOH/urea aqueous solution, which could rapidly dissolve cellulose. The fibers possess circular cross-sections as well as relatively high molecular weight, and a crystallinity index with cellulose II family crystal structure, leading to good mechanical properties. This technology is simple, cheap, and environmentally friendly, promising to substitute for viscose rayon production having hazardous byproducts.
191 citations
TL;DR: It was shown that good water solubility, relatively high chain stiffness, and moderate molecular mass of the derivatives in aqueous solution contribute beneficial to enhancement of antitumor activity.
149 citations
TL;DR: Six polysaccharides were extracted sequentially from the fresh sclerotium of Poria cocos cultivated in China using 0.9% NaCl aqueous solution, and the results indicated that the poly Saccharides PCS1, PCS2, and PCS3-I were heteropolysaccharide containing D-glucose, D-galactose, d-mannose,D-fucOSE, and D-xylose.
127 citations
TL;DR: In this article, the sclerotia (S) and mycelia (M) of Pleurotus tuber regium were extracted by hot water (h) and ultrasonication (s) to yield four water-soluble polysaccharides coded as Sh, Mh, Ss and Ms.
110 citations
TL;DR: The dissolution and regeneration of the cellulose in the NaOH/thiourea aqueous solutions were a physical process and a sol-gel transition rather than a chemical reaction, leading to the smoothness and luster of the fibers.
Abstract: Cellulose was dissolved rapidly in a NaOH/ thiourea aqueous solution (95:45 in wt-%) to prepare a transparent cellulose solution, which was employed, for the first time, to spin a new class of regenerated cellulose fibers by wet spinning The structure and mechanical properties of the resulting cellulose fibers were characterized, and compared with those of commercially available viscose rayon, cuprammonium rayon and Lyocell fibers The results from wide angle X-ray diffraction and CP/MAS 13 C NMR indicated that the novel cellulose fibers have a structure typical for a family II cellulose and possessed relatively high degrees of crystallinity Scanning electron microscopy (SEM) and optical microscopy images revealed that the cross-section of the fibers is circular, similar to natural silk The new fibers have higher molecular weights and better mechanical properties than those of viscose rayon This low-cost technology is simple, different from the polluting viscose process The dissolution and regeneration of the cellulose in the NaOH/ thiourea aqueous solutions were a physical process and a sol-gel transition rather than a chemical reaction, leading to the smoothness and luster of the fibers This work provides a potential application in the field of functional fiber manufacturing
103 citations
TL;DR: In this paper, the results from Fourier transfer infrared spectroscopy, wide angle X-ray diffraction, scanning electron microscopy (SEM) revealed that the regenerated cellulose (RC) membranes possess homogeneous porous structure on the surface and relatively dense microporous structure in the inner.
102 citations
TL;DR: In this paper, the results indicated that cellulose molecules exist as semiflexible chains in the aqueous solution and were more extended than in cadoxen, which agreed with the Yamakawa-Fujii theory of the wormlike chain.
Abstract: Cellulose was dissolved in 6 wt % NaOH/4 wt % urea aqueous solution, which was proven by a 13C NMR spectrum to be a direct solvent of cellulose rather than a derivative aqueous solution system Dilute solution behavior of cellulose in a NaOH/urea aqueous solution system was examined by laser light scattering and viscometry The Mark–Houwink equation for cellulose in 6 wt % NaOH/4 wt % urea aqueous solution at 25 °C was [η] = 245 × 10−2 weight-average molecular weight (Mw)0815 (mL g−1) in the Mw region from 32 × 104 to 129 × 104 The persistence length (q), molar mass per unit contour length (ML), and characteristic ratio (C∞) of cellulose in the dilute solution were 60 nm, 350 nm−1, and 209, respectively, which agreed with the Yamakawa–Fujii theory of the wormlike chain The results indicated that the cellulose molecules exist as semiflexible chains in the aqueous solution and were more extended than in cadoxen This work provided a novel, simple, and nonpollution solvent system that can be used to investigate the dilute solution properties and molecular weight of cellulose © 2003 Wiley Periodicals, Inc J Polym Sci Part B: Polym Phys 42: 347–353, 2004
101 citations
TL;DR: Although TM8s were inactive in inhibiting the viral replication in cell cultures, the S-TM8 fractions with the defined M(w) range had potent anti-viral activity againstHSV-1 and HSV-2 as shown by the CPE assay and the PRA results suggested that S- TM8 fractions seemed to exert their anti-Viral effect by binding to the viral particles, preventing the latter from infecting the host cells.
81 citations
TL;DR: In this paper, a 1.5 M NaOH/0.65 M thiourea aqueous solution by coagulation with 5 wt % CaCl2 and then a 3 Wt % HCl aqueously solution for 2 min was successfully prepared from cellulose and tourmaline nanocrystals with mean diameters of 70 nm.
Abstract: Nanocomposite films were successfully prepared from cellulose and tourmaline nanocrystals with mean diameters of 70 nm in a 1.5 M NaOH/0.65 M thiourea aqueous solution by coagulation with 5 wt % CaCl2 and then a 3 wt % HCl aqueous solution for 2 min. The structure and properties of the composite films were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and tensile testing. The results indicated that the tourmaline nanocrystals were dispersed in a cellulose matrix, maintaining the original structure of the nanocrystals in the composite films. The loss peaks (tan δ) in the DMA spectra and the decomposition temperatures in the DSC curves of the composite films were significantly shifted toward low temperatures, suggesting that the nanocrystals broke the partial intermolecular hydrogen bonds of cellulose, and this led to a reduction in the thermal stability. However, the nanocomposite films exhibited a homogeneous structure and dispersion of the nanocrystals. When the tourmaline content was in the range of 4–8 wt %, the composite films possessed good tensile strength (92–107 MPa) and exhibited obvious antibacterial action against Staphylococcus aureus. This work provides a potential way of preparing functional composite films or fibers from cellulose and nanoinorganic particles with NaOH/thiourea aqueous solutions. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 367–373, 2004
TL;DR: In this article, the authors successfully synthesized cellulose derivatives with high yields from cellulose in 6 wt % NaOH/4 wt% urea aqueous solutions at 25 °C.
Abstract: We successfully synthesized hydroxypropylcellulose (HPC) and methylcellulose (MC) in high yields from cellulose in 6 wt % NaOH/4 wt % urea aqueous solutions at 25 °C. The cellulose derivatives were characterized with NMR, size exclusion chromatography/laser light scattering, gas chromatography (GC), ultraviolet, and solubility measurements in different solvents. According to the results of solution 13 C NMR and GC, the individual degree of substitution (DS; i.e., the average number of substituted hydroxyl groups in the monomer unit) at C-2 hydroxyl groups was slightly higher than the DS values at C-3 and C-6 hydroxyl groups for HPC and MC. In comparison with traditional systems, NaOH/urea aqueous solutions were proved to be a stable and more homogeneous reaction medium for preparing cellulose ether with a more uniform microstructure. The low limits for the average number of moles of the substituent groups per monomer unit and the DS value of water-soluble HPC were 1.03 and 0.85, respectively. MC (DS = 1.48) had good solubility in both water and organic solvents, and the precipitation point occurred at about 67 °C for a 2% (w/v) aqueous solution. In this way, we could provide a simple, pollution-free, and homogeneous aqueous solution system for synthesizing cellulose ethers.
TL;DR: A moderate range of molecular mass, relatively high chain stiffness and good water solubility of the sulfated derivatives are beneficial to the enhancement of their antitumor activities.
TL;DR: It is confirmed that the denatured lentinan molecule, which was dissolved in 0.15M NaOH to be disrupted into single coil chains, could be renatured as triple helical chain by dialyzing against abundant water in the regenerated cellulose tube at ambient temperature (15°C).
Abstract: Molecular morphologies and conformation transition of lentinan, a β-(13)-D-glucan from Lentinus edodes, were studied in aqueous NaOH solution by atomic force microscopy (AFM), viscometry, multiangle laser light scattering, and optical rotation measurements. The results revealed that lentinan exists as triple-helical chains and as single random-coil chains at NaOH concentration lower than 0.05M and higher than 0.08M, respectively. Moreover, the dramatic changes in weight-average molecular weight Mw, radius of gyration 〈s2〉1/2, intrinsic viscosity [η], as well as specific optical rotation at 589 nm [α]589 occurred in a narrow range of NaOH concentration between 0.05 and 0.08M NaOH, indicating that the helix–coil conformation transition of lentinan was carried out more easily than that of native schizophyllan and scleroglucan, and was irreversible. For the first time, we confirmed that the denatured lentinan molecule, which was dissolved in 0.15M NaOH to be disrupted into single coil chains, could be renatured as triple helical chain by dialyzing against abundant water in the regenerated cellulose tube at ambient temperature (15°C). In view of the AFM image, lentinan in aqueous solution exhibited the linear, circular, and branched species of triple helix compared with native linear schizophyllan or scleroglucan. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
TL;DR: In this paper, Bovine serum albumin (BSA) was encapsulated in the microspheres to test the release behavior of BSA from different pHs and with a pH-gradient condition.
Abstract: Microspheres were prepared from carboxymethylated chitosan (CM-chitosan) and alginate by emulsion phase separation. Their structure and morphology were characterized with IR spectroscopy and scanning electron microscopy. Bovine serum albumin (BSA) was encapsulated in the microspheres to test the release behavior. The swelling behavior, encapsulation efficiency, and release behavior of BSA from the microspheres at different pHs and with a pH-gradient condition were investigated. The BSA encapsulation efficiency was calculated to be 80%. The degree of swelling of the microspheres without BSA loaded at pH 7.2 was much higher than that at pH 1.0. The encapsulated BSA was quickly released in a Tris–HCl buffer (pH 7.2), whereas a small amount of BSA was released under acid conditions (pH 1.0) because of the strong electrostatic interaction between NH2 groups of CM-chitosan and COOH groups of alginic acid and a dense structure caused by a Ca2+ crosslinked bridge. For the simulation of the processing of the drug under the conditions of the intestine, the microspheres were tested in a pH-gradient medium, in which an acceleration of the release occurred at pH 7.4 after a lag time at a low pH (5.8–6.8). At pH 7.4, a large amount of BSA was released from the microspheres in a short time because of the rapid swelling of the microspheres. However, the release only depended on the diffusion of BSA at relatively low pHs, this resulted in a relatively low release. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 878–882, 2004
TL;DR: In this article, six hot alkali extracts (HAE-1 to HAE-6) of mushroom (1→3)-β-glucans from the sclerotia of Pleurotus tuber-regium having different molecular weight (Mw) ranging from 1×104 to 42×104 were carboxymethylated to give their corresponding water-soluble derivatives.
TL;DR: In this paper, the ability of cellulose/chitin beads to adsorb Pb2+ in an aqueous solution was measured with a fixed-bed column.
Abstract: Environmental friendly cellulose/chitin beads, having relatively high mechanical properties, were successfully prepared from a blend of cellulose and chitin in 6 wt % NaOH/5 wt % thiourea aqueous solution by coagulating with 5% H2SO4 aqueous solution. The ability of the beads to adsorb Pb2+ in an aqueous solution was measured with a fixed-bed column. The effects of important parameters, to design an adsorption column of the cellulose/chitin beads for fixed-bed columns, were investigated. The breakthrough curves for the adsorption behavior indicated that the column performance was improved with decreasing initial lead concentration, ionic strength, flow velocity or bead size, as well as increasing pH dependence and bed height. Column studies showed that constants, calculated from the experimental data, and the Bed Depth Service Time (BDST) model had a good correlation. The columns were easily regenerated by treating with 0.1 mol/L HCl aqueous solution after the adsorption of metals, providing a simple and economical method for removal and recovery of heavy metals. After four adsorption–desorption cycles, the efficiency of column for the removal of lead was not significantly reduced (not more than 5%). It is shown that heavy-metal biosorption processes in fixed-bed columns could give a broad range of potential industrial applications. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 684–691, 2004
TL;DR: In this article, a graft copolymerization and a moderate degree of crosslinking between kraft lignin (KL)/soy protein isolate (SPI) blends were investigated with wide-angle X-ray diffraction, differential scanning calorimetry, dynamical mechanical thermal analysis, scanning electron microscopy, and tensile and water absorption tests.
Abstract: Methylene diphenyl diisocyanate (MDI) was used to compatibilize kraft lignin (KL)/soy protein isolate (SPI) blends. The structure and properties of the resultant composite materials were investigated with wide-angle X- ray diffraction, differential scanning calorimetry, dynamical mechanical thermal analysis, scanning electron microscopy, and tensile and water absorption tests. The results indicated that graft copolymerization and a moderate degree of crosslinking between KL and SPI occurred in the composites because of the compatibilization of MDI, which favored the strengthening of the materials. Interestingly, the addition of 2 parts of MDI caused a simultaneous enhancement of the modulus, strength, and elongation of KL/SPI blends. The structure with grafting and moderate crosslinks reduced the water absorption of the materials. However, the excess crosslinks hindered the interaction between KL and SPI, resulting in a reduction of the mechanical properties. Scan- ning electron microscopy showed that the domains of the graft copolymer and crosslinking enrichment existed in the blends. When the MDI content was relatively low, these domains became concentric points of stress, enhancing the mechanical properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 624 - 629, 2004
TL;DR: In this article, a mixture of cellulose and soy protein isolate (SPI) was used to obtain microporous membranes, and the properties of these membranes were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), flow rate method, and tensile testing.
TL;DR: In this paper, two kinds of aqueous dispersions were prepared from waterborne polyurethane and its prepolymer by mixing (M) and grafting (G) with 10 wt % casein, respectively.
Abstract: Two kinds of aqueous dispersions were prepared from waterborne polyurethane (WPU) and its prepolymer by mixing (M) and grafting (G) with 10 wt % casein, respectively. The resulting dispersions were characterized by using a rotary viscometer and a particle size distribution meter, indicating that the viscosity, Z average size, and polydispersity of the dispersions increased with an increase of the casein content, and the average particle size of the M dispersions (ca. 30−50 nm) was much lower than that of the G dispersions (ca. 50−150 nm). Polyurethane/casein composite sheets were prepared from the dispersions M and G, coded as sheets M and G, respectively. The structure and properties of the sheets were characterized by using infrared spectroscopy, scanning electron microscopy, ultraviolet spectrophotometry, dynamic mechanical analysis, and tensile testing. The results revealed that the sheets M and G all exhibited a certain degree of miscibility, and their tensile strength was much higher than that of th...
TL;DR: In this article, two series of semi-interpenetrating polymer network (semi-IPN) films from cross-linked waterborne polyurethane (WPU) and carboxymethylchitin (CMCH) in the aqueous solution on the glass and Teflon as the hydrophilic and hydrophobic substrates, respectively, by casting method.
TL;DR: In this article, a series of blend membranes from cellulose and soy protein isolate (SPI) in NaOH/thiourea aqueous solution by coagulating with 5 wt % H2SO4 was successfully prepared.
Abstract: We have successfully prepared a series of blend membranes from cellulose and soy protein isolate (SPI) in NaOH/thiourea aqueous solution by coagulating with 5 wt % H2SO4 aqueous solution. The structure and properties of the membranes were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectrometry, dynamic mechanical thermal analysis, scanning electron microscopy (SEM), transmission electron microscopy, and tensile testing. The effects of SPI content (WSPI) on the structure and properties of the blend membranes were investigated. The results revealed that SPI and cellulose are miscible in a good or a certain extent when the SPI content is less than 40 wt %. The pore structure and properties of the blend membranes were significantly improved by incorporation of SPI into cellulose. With an increase in WSPI from 10 to 50 wt %, the apparent size of the pore (2re) measured by SEM for the blend membranes increased from 115 nm to 2.43 μm, and the pore size (2rf) measured by the flow rate method increased from 43 to 59 nm. The tensile strength (σb) and thermal stability of the blend membranes with lower than 40 wt % of WSPI are higher than that of the pure cellulose membrane, owing to the strong interaction between SPI and cellulose. The values of tensile strength and elongation at break for the blend membranes with 10 wt % of WSPI reached 136 MPa and 12%, respectively. The blend membranes containing protein can be used in water because of keeping σ of 10 to 37 MPa. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 748–757, 2004
TL;DR: In this paper, a series of novel water-resistant cellulose films by coating castor oil-based polyurethane (PU)/benzyl konjac glucomannan (B-KGM) semi-interpenetrating polymer networks (semi-IPN) was presented.
TL;DR: In this article, a mixture of polyurethane and casein was blended at 90°C for 30 min, and then crosslinked by adding 1 − 10 wt % ethanedial to prepare a series of sheets.
Abstract: Waterborne polyurethane (WPU) and casein (1 : 1 by weight) were blended at 90°C for 30 min, and then were crosslinked by adding 1–10 wt % ethanedial to prepare a series of sheets. Their structure and properties were characterized by using infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, dynamic mechanical analysis, and tensile testing. The results indicated that crosslinked blend sheets exhibited a certain degree of miscibility, and exhibited much higher tensile strength and water resistivity than did the WPU, casein, and the uncrosslinked blend from WPU and casein. When the ethanedial content was 2 wt %, the tensile strength and elongation at break of crosslinked sheets achieved 19.5 MPa and 148% in the dry state, and 5.0 MPa and 175% in the wet state, respectively. A 2 wt % content of ethanedial plays an important role in the enhancement of mechanical properties, thermal stability, and water resistivity of the blends of WPU and casein as a result of intermolecular crosslinking. This work provided a new protein plastic with good water resistivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 332–338, 2004
Journal Article•
TL;DR: In this paper, a water insoluble β-(1→3)-D-glucan, sample PCS3-II, isolated from fresh sclerotium of Poria cocos was sulfated in dimethyl sulfoxide (Me 2 SO), carboxymethylated in NaOH, isopropanol solution, as well as methylated, hydroxyethylated and hydroxypropylated in the new solvent system, respectively.
Abstract: A new solvent of cellulose (1.5 mol/L NaOH/0.5 mol/L urea aqueous solution) was used as one of the homogeneous reaction media of polysaccharides for methylation, hydroxyethylation and hydroxypropylation. A water insolubleβ-(1→3)-D-glucan, sample PCS3-II, isolated from fresh sclerotium of Poria cocos was sulfated in dimethyl sulfoxide (Me 2 SO), carboxymethylated in NaOH, isopropanol solution, as well as methylated, hydroxyethylated and hydroxypropylated in the new solvent system, respectively, to obtain five water-soluble derivatives coded as S-PCS3-II, C-PCS3-II, M-PCS3-II, HE-PCS3-II and HP-PCS3-II. Their chemical structure and distribution of substitution were characterized by infrared spectroscopy (IR), elementary analysis (EA), 1 H-NMR, 1 3 C-NMR, 2D-COSY, 2D-TOCSY and 2D- 1 H-detected 1 H 1 3 C HMQC spectra. The results reveal that the relative reactivity of hydroxyl groups of the β-(1→3)-D-glucan is in the order C-6 > C-4 > C-2 on the whole. The substitution of the samples S-PCS3-II, C-PCS3-II and M-PCS3-II occurred mainly at C-6 position and secondly at C-4 and C-2 positions, and that of HE-PCS3-II occurred at C-6 and C-4 positions and of HP-PCS3-II almost completely occurred at C-6 position. The degrees of substitution (DS) obtained from 1 3 C-NMR range from 0.23 to 1.27. The water solubility of the derivatives is in the order S-PCS3-II > C-PCS3-II > M-PCS3-II > HE-PCS3-II > HP-PCS3-II. This work provides a novel and nonpolluting process for the methylation, hydroxyethylation and hydroxypropylation of β-(1→3)-D-glucan.
TL;DR: Investigations revealed the presence of an O-acetylated pentasaccharide repeating unit composed of mannose, glucose, xylose and glucuronic acid in Aeromonas gum.
TL;DR: A water-insoluble (1→3)-α-d -glucan (wc-PCM3-I) was isolated from the Poria cocos mycelia by extracting with 0.5 M NaOH aqueous solution at room temperature.
TL;DR: In this paper, a mixture of waterborne polyurethane (WPU) and carboxymethyl konjac glucomannan (CMKGM) with CMKGM content from 15 to 80 wt % in an aqueous system was used for composite materials.
Abstract: We prepared composite materials by blending waterborne polyurethane (WPU) and carboxymethyl konjac glucomannan (CMKGM) with CMKGM content from 15 to 80 wt % in an aqueous system. The structures and properties of the blend materials were characterized by FTIR, dynamic mechanical analysis, ultraviolet spectroscopy, scanning electron microscopy, wide-angle X-ray diffraction, thermogravimetric analysis, and tensile testing. The results indicated that the blend sheet with 80 wt % CMKGM exhibited good miscibility and higher tensile strength (89.1 MPa) than that of both WPU (3.2 MPa) and CMKGM (56.4 MPa) sheets. Moreover, with an increase of CMKGM content, the tensile strength, Young's modulus, and thermal stability increased significantly, attributed to intermolecular hydrogen bonding between CMKGM and WPU. Based on the experimental results, the blend materials have good, or a certain degree of, miscibility over the whole range of composition ratio of WPU to CMKGM. In addition, the blend materials exhibited organic solvent resistance. This work not only provided a simple method to prepare environmentally friendly materials, but also expanded the application of CMKGM. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 77–83, 2004