Preparation and Characterization of Blend Films of Poly(Vinyl Alcohol) and Sodium Alginate

Blend films of poly(vinyl alcohol) (PVA) and sodium alginate (NaAlg) were prepared by casting from aqueous solutions. This blend films were characterized by tensile strength test, Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The miscibility in the blends of PVA and NaAlg was established on the basis of the thermal analysis results. DSC showed that the blends possessed single, composition‐dependent glass transition temperatures (T_gs), indicating that the blends are miscible. FT‐IR studies indicate that there is the intermolecular hydrogen bonding interactions, i.e. –OH…^?OOC– in PVA/NaAlg blends. The blend films also exhibited the higher thermal stability and their mechanical properties improved compared to those of homopolymers.     

海藻酸钠/水性聚氨酯共混膜的结构表征和性能测试

本文将海藻酸钠与聚酯型水性聚氨酯共混制膜，并通过红外光谱（FTIR）、X射线衍射（XRD）、扫描电镜（SEM）、紫外光谱（UV）、力学性能测试对共混膜的结构和性能进行了表征与测试。结果表明，共混膜中两种分子间存在着强烈的相互作用和良好的相容性，与纯海藻酸钠膜相比共混膜有较高的抗水性和断裂伸长率。     

Properties of poly(lactic acid-co-glycolic acid) film modified by blending with polyurethane

A number of poly(lactic acid-co-glycolic acid)/polyurethane (PLGA/PU) blend films with various PU mole contents were prepared by casting the polymer blend solution in chloroform. The surface morphologies of the PLGA/PU blend films were studied by scanning electron microscopy (SEM). The thermal, mechanical and chemical properties of the PLGA/PU blend films were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile tests and surface contact angle tests. The results revealed that the introduction of PU could markedly modify the properties of PLGA films.     

Breakthrough in the preparation of irradiated sodium alginate/polyethylene oxide blend films using methacrylate monomer

The present work is an attempt to prepare biodegradable films of sodium alginate (SA)/polyethylene oxide (PEO) blend tailored by methacrylate (MA) and γ irradiation following casting method. The effects of SA/PEO composition, glycerol as a plasticizer, methacrylate as a monomer, and radiation dose were investigated and it was found that the mechanical properties of the films strongly depend on the film-forming parameters. The incorporation of glycerol in the blend is crucial as it creates a suitable environment for monomer addition and points out that tensile strength of the films decreased, while the elongation at break increased. Moreover, it was found that the tensile properties were improved by the application of γ radiation as well as monomer treatment. The mechanical properties of the blend films integrated with MA monomer were higher than that without monomer at the analogous conditions. The structural and morphological features of the films were examined by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively.     

Morphology and mechanical properties of ultra-high molecular weight polyethylene-poly(tetrafluoroethylene) blend films

This paper deals with the morphology and mechanical properties of blend films for polytetrafluoroethylene (PTFE) and ultra-high molecular weight polyethylene (UHMWPE) prepared by kneading techniques. This experiment was carried out for blend films, prepared with different compositions of PTFE and UHMWPE to improve thermal properties of PE. In spite of the incompatibility of the two polymers, the blend film with the PTFE/UHMWPE composition =75/25 was maintained under the measurement of complex modulus at temperature higher than 300°C. This indicates that the UHMWPE chains dispersed in PTFE fibrous texture were not separated by the melting flow of UHMWPE at 300°C. To check the origin of this interesting phenomenon, the morphology of the blend films was investigated by using scanning electron microscopy, X-ray diffraction, and¹³C nuclear magnetic resonance.     

SYNTHESIS OF POLY(METHYL METHACRYLATE)-SILICA NANO-COMPOSITES. II. POLY[METHYL METHACRYLATE-block-(METHYL METHACRYLATE-co-2-HYDROXYETHYL METHACRYLATE)]

ABSTRACT

One kind of poly(methyl methacrylate [MMA]-block-2-hydroxyethyl methacrylate [HEMA]) block copolymer and two kinds of poly[MMA1-block-(MMA-co-HEMA)] block-random copolymers were synthesized by atom transfer radical polymerization. Then, poly(methyl methacrylate) [PMMA]-silica nano composites were synthesized by blending perhydropolysilazane (PHPS: NN-110) and block or block-random copolymers in 1,4-dioxane and casting the blend solutions. All composite films were transparent. Silica and organic domains were microphase separated in the composites. The effects of PHEMA content and blend ratio of PHPS to hydroxyl group on the microphase separation were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The thermal properties of the composites were investigated by differential scanning calorimetry (DSC) and thermal gravitic analysis (TGA).     

Structure and properties of blend membranes prepared from cellulose and alginate in NaOH/urea aqueous solution

Regenerated cellulose (RC)/alginic acid (AL) blend membranes were satisfactorily prepared from 6 wt % NaOH/4 wt % urea aqueous solution by coagulating with 5 wt % CaCl₂ aqueous solution, and then treated with 3 wt % HCl. Morphology, crystallinity, mechanical properties, and thermal stability of the membranes were investigated by scanning electron microscopy (SEM), IR and UV spectroscopes, X‐ray diffraction, tensile tests, and thermogravimetric analysis (TGA). The RC/AL blends were miscible in all weight ratios of cellulose to alginate. The membranes have homogeneous mesh structures, and the mesh sizes of the blend membranes (200–2000 nm) significantly increased with increasing alginate content. The crystalline state of the AL membrane prepared from 6 wt % NaOH/4 wt % urea aqueous solution was broken completely, and the crystallinity of the blend membranes decreased with an increase of AL. Comparing with AL membranes, the tensile strength and breaking elongation of the blend membranes were obviously improved in dry and wet states. Therefore, the RC/AL blends offer a promising way of alginate as separate and functional materials used in the wet state. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 451–458, 2001     

Cellulose acetate blends with acrylonitrile/N-phenyl maleimide copolymers morphological and thermal properties

Cellulose acetate (CA) was blended in different compositions with various acrylonitrile-N-halo phenyl maleimide (AN-XPhM) copolymers to improve the thermal and mechanical properties of cellulose acetate. The structure, morphology, thermal stability, and crystallinity of the blend films were characterized by infrared spectroscopy, scanning electron micrographs, thermogravimetry/differential thermal analysis, differential scanning calorimetry, and X-ray diffraction. The results revealed that the thermal stability was improved by the increase in AN-XPhM content, irrespective of the type of the N-halo phenyl maleimide. The CA/AN-4BrPhM blend films possessed the highest thermal stability compared to the other CA/AN-XPhM blend films. Blending CA with AN-4BrPhM yielded the most homogeneous blend films, irrespective of the composition ratio. The mechanical properties of various compositions of the CA/AN-4BrPhM blend films were also discussed.     

Thermal and photochemical stability of poly(vinyl alcohol)/modified lignin blends

A kraft lignin derivative (KLD) obtained by reaction with p-aminobenzoic acid/phthalic anhydride was blended with poly(vinyl alcohol) (PVA) by solution casting from DMSO. PVA and PVA/KLD films were exposed to ultraviolet radiation (24, 48, and 96 h) and analyzed by thermogravimetry (TG), differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (¹H NMR) spectroscopy, and scanning electron microscopy (SEM). PVA films show a loss of thermal stability due to irradiation. PVA/KLD reveals greater thermal stability than PVA and an increase in thermal stability after irradiation. These results suggest that the incorporation of KLD into PVA provides a gain in thermal and photochemical stability. FTIR, ¹H NMR, DSC, and TG results obtained for the blends suggest that intermolecular interactions between PVA and KLD chains are present. SEM micrographs revealed blend miscibility for a KLD blend content of up to 15 wt%, as observed at magnification of 1000 times.     

Preparation and Properties of Alginate/Water‐Soluble Chitin Blend Fibers

Water‐soluble chitin (half‐deacetylated chitin) was prepared from chitosan by N‐acetylation with acetic anhydride. Alginate/water‐soluble chitin blend fibers were prepared by spinning their mixture solution through a viscose‐type spinneret into a coagulating bath containing aqueous CaCl₂ and ethanol. The structure and properties of the blend fibers were studied with the aids of infrared spectra (IR), X‐ray diffraction (XRD) and scanning electron microscopy (SEM). structure analysis indicated good miscibility existed between alginate and water‐soluble chitin, due to the strong interaction from the intermolecular hydrogen bonds and electrostatic interactions. Best values for the dry tensile strength and breaking elongation were obtained when the water‐soluble chitin content was 30 wt%. The wet tensile strength and breaking elongation decreased with the increase of water‐soluble chitin content. The introduction of water‐soluble chitin in the blend fiber can improve the water‐retention properties of the blend fiber compared to pure alginate fiber. The fibers treated with aqueous solution of silver nitrate have good antibacterial activity to Staphylococcus aureus.     

Poly(vinyl alcohol)/polyelectrolyte complex blend membrane for pervaporation dehydration of isopropanol

Poly(vinyl alcohol) (PVA) was blended with soluble polyelectrolyte complex (PEC) made from poly(diallyldimethylammonium chloride) (PDDA) and sodium carboxymethyl cellulose (CMCNa). Crystallinity, thermal transition, and thermal stability of the PVA/PEC blends were characterized by using wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermal gravity analysis (TGA), respectively. Surface morphology, cross-section and phase structure of the blend membranes were examined by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Surface hydrophilicity and swelling behavior of the blend membranes were examined by water contact angle (CA) and swelling tests. Blend membranes were subjected to isopropanol dehydration, and effects of blend composition, feed composition and feed temperature on pervaporation performance are discussed in terms of phase structures of blend membranes. A performance of J = 1.35 kg/m² h, α = 1002, was obtained for blend membrane containing 50 wt% PEC in dehydrating 10 wt% water–isopropanol at 70 °C.     

Morphology and thermal properties of conductive polyaniline/polyamide composite films

Polyaniline (PANI) in an emeraldine‐base form, synthesized by chemical oxidation polymerization, was doped with camphor sulfonic acid (CSA). The conducting complex (PANI–CSA) and a matrix, polyamide‐66, polyamide‐11, or polyamide‐1010, were dissolved in a mixed solvent, and the blend solution was dropped onto glass and dried for the preparation of PANI/polyamide composite films. The conductivity of the films ranged from 10^?7 to 10⁰ S/cm when the weight fraction of PANI–CSA in the matrices changed from 0.01 to 0.09, and the percolation threshold was about 2 wt %. The morphology of the composite films before and after etching was studied with scanning electron microscopy, and the thermal properties of the composite films were monitored with differential scanning calorimetry. The results indicated that the morphology of the blend systems was in a globular form. The addition of PANI–CSA to the films resulted in a decrease in the melting temperature of the composite films and also affected the crystallinity of the blend systems. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2531–2538, 2002     

UV curable epoxy acrylate-clay nanocomposites

UV curable epoxy acrylates were reinforced with two different organically modified montmorillonites (MMTs) and an unmodified MMT. Conversion and rate of polymerization was monitored by real time infrared spectroscopy (RTIR) and photo-DSC. Microstructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and optical clarity. Optical clarity of the films containing clay was quite good as only a slight decrease was observed. Physical properties of the reinforced films were examined by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), hardness and tensile testing. Enhancements in glass transition temperature (T_g), thermal stability and mechanical properties were observed. The films reinforced with the unmodified MMT exhibit the most significant enhancements in properties.     

Preparation of Anatase Hollow TiO2 Spheres and Their Photocatalytic Activity in the Photodegradation of Chlorpyrifos

Hollow anatase titania (TiO₂) spheres were synthesized using fructose and tetrabutyl titanate (Ti(OC₄H₉)₄, TBT) as the precursors via the conventional hard template method. The morphological, structural and thermal properties of the products were characterized using scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG‐DTA), Brunauer? Emmett? Teller (BET) surface area analysis and diffuse reflectance ultraviolet visible (DR UV? Vis) spectroscopy. XRD revealed that the hollow TiO₂ prepared was in the anatase phase and the BET surface area measured was about 22 m² g^?1. The photocatalytic activity of the synthesized hollow anatase TiO₂ in the photodecomposition of chlorpyrifos was 18.67 % higher than that obtained using commercial TiO₂.     

Surfactant effect on electrochemical-induced synthesis of α-Ni(OH)2

Nickel hydroxide films were electrosynthesized in the presence of different diluted surfactant solutions by galvanostatic electroprecipitation. Lamellar α-Ni(OH)₂ films are obtained using cationic surfactant cetyltrimethylammonium bromide (CTAB), anionic surfactant sodium dodecyl sulfate (SDS), and also neutral surfactant Tween® 80. The films were structurally and morphologically characterized by X-ray diffraction, thermal gravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy, and electrochemically by cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). The results evidenced that SDS remains intercalated between the lamellae of α-Ni(OH)₂. Albeit the presence of CTAB and Tween® 80, it was noticed in FTIR spectra that the surfactants did not intercalate. The morphology was affected by the presence of different surfactants. All studied surfactants displaced the oxidation potential (E _O) of Ni²⁺/Ni³⁺ process to less positive values. Also, the presence of surfactants improved the electrode charge efficiency and the charge response for the same number of moles of nickel ions deposited. The ratio of the charge and frequency change is 4.4 times bigger for films deposited with SDS when compared with pure α-Ni(OH)₂ films.     

Green preparation of hollow mesoporous silica nanosphere inside-loaded gold nanoparticles and the catalytic activity

In this work, an active nano-catalyst with gold nanoparticles loaded in hollow mesoporous silica nanospheres (HMSNs/Au) was prepared by a one-pot sol-gel method, in which gold ions were loaded in hollow mesoporous silica spheres followed by sodium alginate reduction. The characterization of the HMSNs/Au were determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N₂ adsorption–desorption isotherms (BET). The high catalytic activity of HMSNs/Au, denoted as apparent turn-over frequency (TOF), was detected by UV-Vis spectrophotometer for the catalytic reduction of 4-nitrophenol (74.5 h^?1) and 2-nitrophenol (108.7 h^?1) in the presence of sodium borohydride solution due to the small gold nanoparticles size and overall exposure of active sites. It is expected that this ecofriendly approach to prepare inorganic composited nanoparticles as high active catalysts based on hollow mesoporous materials was a promising platform for loading noble metal nanoparticles.     

聚吡咯/海藻酸钠纳米球的制备及其应用于高性能超级电容器

用海藻酸钠作为结构导向剂,通过原位氧化聚合吡咯法制备了聚吡咯/海藻酸钠(PPy/SA)纳米球.聚吡咯/海藻酸钠纳米球的形貌和结构通过扫描电镜(SEM)、X射线衍射(XRD)和傅里叶变换红外(FTIR)光谱进行表征.材料的电化学性能通过循环伏安法和恒电流充放电方法进行测试.电化学测试表明,聚吡咯/海藻酸钠纳米球在1 mol L-1KCl电解液中,电流密度为1 A g-1时其比电容高达347 F g-1.与纯聚吡咯相比较,聚吡咯/海藻酸钠纳米球具有更优异的循环稳定性能.     

Preparation and characterization of poly(vinyl alcohol)/organo-modified cloisite Na+ with chiral L-leucine amino acid/TiO2 nanocomposites

Poly(vinyl alcohol)/organo-clay/TiO₂ nanocamposites films were prepared with 10 wt % of organo-nanoclay and various amount of TiO₂ nanoparticles. Cloisite Na⁺ has been modified via cation exchange reaction using ammonium salt of natural L-leucine amino acid as a cationic surfactant. After that poly(vinyl alcohol)/organo-nanoclay/TiO₂ nanocomposites were synthesized by dispersion of TiO₂ on the surfaces of organo-nanoclay in poly(vinyl alcohol) matrix by using ultrasonic energy. Three nanocomposites with different loading of TiO₂ were prepared and characterized by X-ray diffraction, fourier transform infrared spectroscopy, field emission type scanning electron microscope, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis and ultraviolet-visible transmission spectra. The results showed that the organo-nanoclay and TiO₂ were dispersed homogeneously in poly(vinyl alcohol) matrix and also showed improvement in their thermal properties compared with the pure poly(vinyl alcohol).     

Thermal characterization of bacterial cellulose–phosphate composite membranes

Cellulose–phosphate composite membranes have been prepared from bacterial cellulose membranes (BC) and sodium polyphosphate solution. The structure and thermal behavior of the new composites were evaluated by X-ray diffraction (XRD), ³¹P-nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetry (TG) and thermomechanical analysis (TMA). From XRD analyses the Iα and Iβ cellulose crystalline phases were identified together with crystalline sodium phosphate that covers the cellulose microfibrils as revealed by SEM. ³¹P NMR spectra show peaks assigned to Q⁰ and Q¹ phosphate structures to be compared to the Q² units that characterize the precursor polyphosphate. Glass transition temperature, T _g, obtained from TMA curves and thermal stability obtained from TG and DSC measurements, were observed to be dependent on the phosphate content.     

Properties of water-soluble carboxymethyl chitosan film modified by hydrophobic poly(propylene glycol)

A series of water-soluble carboxymethyl chitosan (CMCS)/poly(propylene glycol) (PPG) blend films with various CMCS/PPG mole ratios were prepared by the solution casting method. Morphology of the CMCS/PPG blend films was investigated by scanning electron microscopy (SEM). Thermal, mechanical, and chemical properties of the CMCS/PPG blend films were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile tests, and contact angle tests. It was found that the introduction of PPG can markedly affect the morphology and the properties of CMCS films.