Pectin based cerium (IV) and thorium (IV) phosphates as novel hybrid fibrous ion exchangers synthesis,characterization and thermal behaviour

Summary Pectin based cerium (IV) and thorium (IV) phosphates have been synthesized as new phases of hybrid fibrous ion exchangers. Both materials were characterized using X-ray diffraction, infrared (IR) spectra, thermogravimetric analysis (TG), differntial thermogravimetry (DTG), differntial thermal analysis (DTA) and scanning electron microscopy (SEM), as well as the determination of their ion exchange capacity, elution and pH titration. The X-ray study reveals the amorphous nature of the materials, while SEM studies confirm the fibrous nature of the materials. The thermal studies of these materials indicate that both of them are highly stable on heating as they retain about 97% of their ion-exchange capacity (i.e.c.) on heating up to 100°C and about 81% on heating up to 200°C.     

Preparation and properties of water‐soluble chitosan and polyvinyl alcohol blend films as potential bone tissue engineering matrix

The blend film was prepared by casting solutions of water‐soluble hydroxyethyacryl‐chitosan (HEA‐CS) and polyvinyl alcohol (PVA) and cross‐linked by glutaraldehyde. The structure and properties of the blend films were estimated by wide‐angle X‐ray diffraction (WXRD), contact angle measurements with water, and scanning electron microscopy (SEM). The tensile properties of the blend films were investigated and the tensile strength (TS) and the elongation increased with the increased amount of PVA. The thermal stability (thermogravimetric (TG) and derivative thermogravimetric (DTG)) was evaluated and HEA‐CS was more thermally‐stable than that of PVA. The water swelling properties analysis indicated that HEA‐CS in the blends promoted the water absorption owing to its porous structure and the antimicrobial ability of the blend films was retained. Indirect cytotoxicity assessment of the blend films with human bone sarcoma cell (SW1353) indicated that the biomaterials were non‐toxic and did not release substances harmful to living cells. Copyright © 2009 John Wiley & Sons, Ltd.     

PREPARATION AND PHYSICAL PROPERTIES OF BLEND FILMS FROM SODIUM ALGINATE AND POLYACRYLAMIDE SOLUTIONS

Blend films of sodium alginate and polyacrylamide (PAAm) were prepared by mixing the aqueous solution of both samples at a different ratio. All blend films obtained are optically clear to the naked eye. The structure and physical properties of the films were studied by FT-infrared (FT-IR), wide angle X-ray diffraction (WAXD), differential thermal analysis (DTA), thermogravimetic analysis (TGA), scanning electron microscopy (SEM), and tensile strength test. The results showed that the occurrence of interactions between -COO^?, -OH groups of sodium alginate and -CONH₂ groups of PAAm in the blends through hydrogen formation. The blend films exhibited the higher thermal stability and improved mechanical properties in dry states. These properties had the maximum value around 20 wt% PAAm content in the blend film. The morphological transition of the blend films from sodium alginate-like to PAAm-like was observed by scanning electron microscopy.     

Cornstarch/Poly(vinyl alcohol) Biocomposite Blend Films: Mechanical Properties,Thermal Behavior,Fire Retardancy,and Antibacterial Activity

In the present study, biocomposite films of starch/poly(vinyl alcohol) (St/PVA) reinforced with delignified Grewia optiva fiber and methyl methacrylate (MMA) grafted fibers were prepared using citric acid as a plasticizer and glutaraldehyde as the cross-linker. The biocomposite films were subjected to evaluation of mechanical properties, biodegradability, and antibacterial properties. The biocomposite films were characterized by using Fourier transform-infrared (FT-IR) spectrophotometry, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA/DTA/DTG). SEM showed good adhesion between St/PVA blend matrix and fibers. The antimicrobial activity of biocomposite films against pathogenic bacteria such as Staphylococcus aureus and Escherichia coli was also explored. The results confirmed that the biocomposite films may be used for food packaging.     

Preparation and properties of calcium silicate hydrate-poly(vinyl alcohol) nanocomposite materials

Summary A series of calcium silicate hydrate (C-S-H)-polymer nanocomposite (C-S-HPN) materials were prepared by incorporating poly(vinyl alcohol) (PVA) into the inorganic layers of C-S-H during precipitation of quasicrystalline C-S-H from aqueous solution. The as synthesized C-S-HPN materials were characterized by Fourier-transform infrared photoacoustic (FTIRPAS) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy/energy dispersed spectroscopy (SEM/EDS), thermogravimetric analysis (TG), differential thermogravimetry (DTG) and differential scanning calorimetry (DSC). The XRD peaks of C-S-HPN materials suggest the intermediate organizations presenting both intercalation of PVA and exfoliation of C-S-H. The SEM micrographs of C-S-H, PVA and C-S-HPN materials with different PVA contents exhibit the significant differences in their morphologies. Effects of the material compositions on the thermal stability of a series of C-S-HPN materials along with PVA and C-S-H were studied by TG, DTG and DSC. Three significant decomposition temperature ranges were observed in the TG curves of all C-S-HPN materials.     

壳聚糖-聚羟基丁酸酯共混膜的制备与性质

以乙酸为共溶剂,制备了壳聚糖-聚羟基丁酸酯(CTS-PHB)共混膜,利用红外光谱(FT-IR)、广角X粉末衍射(WAXD)、扫描电镜(SEM)及差热分析(DTA)表征了共混膜的化学组成、晶形、形貌和热稳定性能。研究表明:CTS和PHB可在体积百分数为62.5%的乙酸溶液中共混,形成表面光滑、不透明的膜,干态共混膜具备一定的力学强度。各比例的CTS-PHB共混膜有相同的热分解温度,共混膜的形貌特征随两组分质量配比变化,其中mPHB/mCTS=1/1的共混膜显示出良好的有序结构。     

Synthesis,characterization, thermal,electrical and magnetic properties of polyaniline composites with rare earth gadolinium coordination complex

Novel polyaniline/gadolinium (PANI/Gd) composites were successfully synthesized by “in‐situ” polymerization at the presence of rare earth Gd coordination complex and D‐tartaric acid (an a dopant). It is rarely to find the studies on related field to add rare earth Gd coordination complex as fillers. Fourier transform infrared (FTIR) spectra, X‐ray diffraction (XRD) and scanning electron microscope (SEM) were used to examine the structure and surface appearance characterization of materials. The thermal stability performance of composites was investigated by thermogravimetry and derivative thermogravimetry (TG‐DTG). Electrochemical performance was measured by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge test. The magnetic property was investigated by physical property measurement system (PPMS). The structure and surface appearance characterization and the magnetic properties jointly demonstrate the polymerization of rare earth Gd coordination complex and PANI–D‐tartrate (DTA) not only simple physical mixing but also chemical mixing. TG‐DTG analysis suggests that thermal stability of PANI/Gd composites is higher than that of PANI–DTA. Electrochemical performance tests and SEM indicate that the composite (PANI/Gd = 3.3:1,mass ratio) has the most regular morphology and best specific capacitance. The magnetization of the composite (PANI/Gd = 3.3:1,mass ratio)is evidently smaller compared with PANI–DTA and rare earth Gd coordination complex. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparation and Characterizations of TiO2/Organically Modified Silane Composite Materials Produced by the Sol-Gel Method

TiO₂/organically modified silane (ORMOSIL) composite materials produced by the sol-gel method were studied for optical waveguide applications. High optical quality waveguiding films on different substrates, including silicon, gallium arsenide, silica/silicon substrates, and microscope glass slides, were prepared from high titanium content (0.2 molar) ÿ-glycidoxypropyltrimethoxysilane at low temperature. Scanning electron microscopy (SEM), atomic force microscopy (AFM), differential thermal analysis (DTA), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) have been used to investigate the optical and structural properties of the composite films. The TGA/DTA results showed that the organic compounds in the film would tend to decompose in the temperature range from 200°C to 500°C. SEM and AFM results showed that a dense and porous-free composite material film could be obtained at the heat treatment temperature of 100°C. It was also shown that ORMOSIL is integrated in the glass, providing low shrinkage and high cracking resistance. The propagation loss properties of the composite films were also investigated. About 1.1 dB/cm propagation loss of the planar waveguide film was obtained at the wavelength of 633 nm.     

Thermal decomposition of ammonium copper chromate: effect of the addition of barium

The influence of the addition of barium (as barium chromate) to ammonium copper chromate on its thermal decomposition has been investigated by TG, DTG and DTA in the temperature range 303–1273 K. The solid products formed in the decomposition at different temperatures were characterised by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and also by measuring their specific surface area. The addition of BaCrO₄ at different concentrations (0–19.8%) was found not to change the general trend in the decomposition of ammonium copper chromate (which occurs in four distinct steps), except small changes in the temperature corresponding to DTG and DTA peaks. However, the sintering (or crystal growth) of the solid product is largely reduced by the presence of BaCrO₄.     

Thermal behaviour of CODA azoic dye liquid crystal and nanostructuring by drop cast and spin coating techniques

This study comes to complete the initial investigation of the liquid crystalline properties of 4-[(4-chlorobenzyl)oxy]-3,4′-dichloroazobenzene (CODA). Here, the thermal analysis of CODA dye was performed in air flow and nitrogen flow atmospheres by means of simultaneous thermogravimetry TG, derivative thermogravimetry DTG, differential thermal analysis DTA and differential scanning calorimetry DSC; differences between the two steps of the thermal degradation of CODA related to the two experimental atmospheres were observed. Drops cast and spin coating techniques were used for nanostructuring CODA on platinum (Pt) substrates; the deposited materials were characterised by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Exotic crystalline nanowires of CODA were obtained as function of used deposition technique, while the deposition time decisively influenced their features. The present results advocate for employing these materials as template matrices for producing high-aspect-ratio inorganic nanomaterials (i.e. Au) in the form of nanotubes, nanowires, nanorods or nanoparticles with enhanced functional properties.     

Studies on thermal decomposition of electrochemically oxidized glass-like carbon

Glass-like carbon (GC) tiles were electrochemically oxidized in 1 mol·dm^?3 H₂SO₄ solution at a potential of 2.3 V/SCE. The surfaces of the oxidized samples were examined by scanning electron microscopy (SEM). The solid oxidation products were studied by derivatographic (TG, DTG and DTA) and elemental analyses. The solid products of electrochemical oxidation of GC, with the general formula C₈O_4.2H_2.3 were thermolabile and revealed properties similar to those of graphite oxide. They are hydrophylic and their thermal decomposition proceeds in three steps: (i) evaporation of-chemisorbed water (320–400 K), (ii) exothermic decomposition of graphite oxide (370–430 K), and (iii) gradual decomposition of the oxidation products (>430 K).     

Li doped and undoped ZnO nanocrystalline thin films: a comparative study of structural and optical properties

Thin films of ZnO were grown by the sol–gel method using spin-coating technique on (0001) sapphire substrates. The effect of doping after annealing on the structural and optical properties has been investigated by means of X-ray diffraction (XRD), cathodoluminescence (CL) spectrum, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The films that were dried at 623 K and then post annealed at 873 K showed (0002) as the predominant orientation. Two emission bands have been observed from CL spectrum. Lithium doped film shows shift in the near band edge UltraViolet emission peak and suppressed defect level emission peak in the visible range. SEM analysis of the films exhibits many spherical shaped nanoparticles. Roughness of the films determined using atomic force microscopy.      

Effect of nanoclay and barium sulfate nanoparticles on the thermal and morphological properties of polyvinylidene fluoride nanocomposites

The thermal, morphological and optical studies of BaSO₄ and MMT (nanoclay) embedded in PVDF were investigated. Nanocomposites samples of PVDF–BaSO₄–MMT were prepared by varying the loadings (1–4 mass%) in case of BaSO₄ and MMT nanomaterials, respectively. Polyvinylidene fluoride–barium sulfate-montmorillonite (PVDF–BaSO₄–MMT) nanocomposites were prepared by solvent-mixing technique. Nanoparticles were synthesized by in situ deposition technique with the help of nonionic polymeric surfactant, and the particle size of nanoparticles was recognized by scanning electron microscopy (SEM) analysis which confirms that the particle has diameter of 80–90 nm. As prepared, nanocomposites films (thickness, 25 μm) were characterized by Fourier transform infrared microscopy (FTIR), SEM and electron diffraction spectroscopy (EDS). FTIR shows that all the chemical constituents were present in the nanocomposites, whereas SEM analysis suggested that the nanofillers dispersed well in polymer matrix and EDS showed the elemental composition of nanocomposite samples. Thermal properties of nanocomposites were studied by using TG/DTA/DTG. TG/DTA studies showed decomposition temperature of pure PVDF is 473.5 °C. The decomposition temperature (T _d) of nanocomposites was increased by 93 °C in case of nanocomposites with addition of both BaSO₄ and MMT nanomaterials. The difference in the thermal degradation temperature was found to be 1.2% higher in case of addition of BaSO₄ nanoparticle as compared to nanoclay. The obtained transparent nanocomposite films were characterized by using UV–Vis spectrophotometer which shows that transparencies of nanocomposites are maintained in visible region, the intensity of absorption band in UV region is increased with the addition of BaSO₄ nanoparticles, while in case of addition of nanoclay the UV region does not show drastic changes. Addition of both nanoparticle and nanoclay shows higher absorption in comparison with the individual samples. But further, doubling the amount of nanoparticle and nanoclay shows decrease in UV absorption. Overall, the results of thermal studies show that the incorporation of BaSO₄ and MMT could significantly improve the thermal properties of nanocomposites.     

Preparation and Properties of Poly（vinyl alcohol）/Chitosan Blend Bio-nanocomposites Reinforced by Cellulose Nanocrystals

The aim of this paper is to report the effect of the addition of cellulose nanocrystals（CNCs） on the mechanical, thermal and barrier properties of poly（vinyl alcohol）/chitosan（PVA/Cs） bio-nanocomposites films prepared through the solvent casting process. The characterizations of PVA/Cs/CNCs films were carried out in terms of X-ray diffraction（XRD）, transmission electron microscopy（TEM）, scanning electron microscopy（SEM）, thermogravimetric analysis（TGA and DTG）, oxygen transmission rate（OTR）, and tensile tests. TEM and SEM results showed that at low loading levels, CNCs were dispersed homogenously in the PVA/Cs matrix. The tensile strength and modulus in films increased from 55.1 MPa to 98.4 MPa and from 395 MPa to 690 MPa respectively, when CNCs content went from 0 wt% to 1.0 wt%. The thermal stability and oxygen barrier properties of PVA/Cs matrix were best enhanced at 1.0 wt% of CNCs loading. The enhanced properties attained by incorporating CNCs can be beneficial in various applications.     

Synthesis,characterization, and properties of novel poly(ether urethanes)

Novel poly(ether urethanes) were synthesized by homo- and random copolymerization of the m- and p-hydroxyethoxy benzoyl azides. Polymerization proceeded by decomposition and rearrangement of the acid azide group to the isocyanate group, which immediately reacted intermolecularly with the hydroxyl group to produce polyurethanes. These polymers were characterized by infrared spectroscopy (IR), nuclear magnetic resonance spectroscopy (NMR), x-ray diffraction, scanning electron microscopy (SEM), viscosity, and solubility. The thermal stability of these polymers was also studied by TG and DTG (derivative TG).     

Li-birnessite型层状二氧化锰的合成及电化学性能

采用O2氧化法在碱性条件下氧化Mn2+,制备Li-birnessite型层状MnO2.X射线衍射、扫描电子显微镜、BET、热重等技术表征MnO2样品的性能.以放充电法测试Li-birnessite正极材料性能.结果表明,Li-birnessite结晶良好,层间距约为0.70 nm,呈球状或类球状.以Li-birnessite为正极材料的扣式电池在0.2 C(40 mA/g)条件下放电时容量高达203 mAh/g,且具有良好的倍率性能.     

Silicothermic reduction process in magnesium production

In this paper there are presented the results of the characterization and thermal analysis of the slag from the magnesium plant ‘Bela Stena’, Serbia. The results of X-ray fluorescence analysis, scanning electron microscopy (SEM), optical microscopy (LOM) and X-ray diffraction (XRD) were used for chemical and mineralogical analysis of the solidified slag samples. Differential thermal analysis (DTA), thermo-gravimetric (TG) analysis and thermal microscopy results were used for determination of characteristic phase transformations. The solidified slag shows dicalcium silicate based structure. Magnesium is mostly present in the form of the following minerals: periclase, merwinite and melilite.     

Polyaniline/SiO2 Nanocomposite Catalyzed Efficient Synthesis of Quinoxaline Derivatives at Room Temperature

Polyaniline/SiO₂ nanocomposite material has been synthesized by using chemical oxidative method. Prepared catalytic material was characterized by means of transmission electron microscopy (TEM), thermal analysis (TG‐DTA), X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT‐IR). Solvent stability for the catalyst has been screened using UV‐Visible spectroscopy. Polyaniline/SiO₂ catalyzed route has found to be an efficient and rapid protocol for the synthesis of quinoxaline derivatives by cyclocondensation of 1,2‐diketones and o‐phenylenediamines at room temperature. This protocol has several advantages such as high yield, good thermal stability, simple work up procedure, non‐toxic, clean, and easy recovery and reusability of the catalytic system.     

Characterization of herbal medicine with different particle sizes using pyrolysis GC/MS, SEM, and thermal techniques

Analytical techniques have been used to characterize compounds from herbal medicine, its products and extracts. The objective of this study was to characterize a variety of particle sizes of Erythrina velutina Willd powder. The samples used in the study were named MUF01 (710 μm), MUF03 (180 μm) and MUF05 (75 μm). The techniques employed were scanning electron microscopy (SEM), thermal analysis such as thermogravimetry (TG) and differential thermal analysis (DTA) together with pyrolysis coupled to gas chromatography/mass spectrometry (Pyr-GC/MS). SEM enabled us to detect the existence of divergences from the expected results from the granulometry process. Thermal analytical techniques (TG and DTA) showed the thermal decomposition profile, corresponding to physical and chemical phenomena. The chromatographic data relative to the peak area of the compounds analyzed evidenced quantitative differences in the chemical compositions of the samples MUF01, MUF03, and MUF05 at 300, 450 and 600 °C. Neophytadiene 2,6,10-trimethyl, 14 and 3-eicosyne were identified by Pyr-GC/MS at 300, 450 and 600 °C, and it classified the samples according the peak area values, which were MUF05 > MUF03 > MUF01. SEM, DTA and TG confirmed this through particle size uniformity, heat flow, and mass loss, respectively.     

Improved surface properties of polyaniline films by blending with Pluronic polymers without the modification of the other characteristics

Films of conductive polyaniline and amphiphilic Pluronic (P105) copolymer blends were prepared by dissolving the two polymers in N-methylpyrrolidinone (NMP) followed by a slow solvent evaporation at 55 degrees C. The characteristics of both doped and undoped films were determined by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), water droplet contact angles, differential scanning calorimetry (DSC), thermal gravimetry analysis (TG), wide-angle X-ray diffraction (WAXD), and tensile strength measurements. The surface of the blends became more hydrophilic than that of the hydrophobic PANI film, but the other properties of the blends did not change appreciably for Pluronic content lower than 50 wt%. Compared to PANI films, the more hydrophilic surfaces decreased the amount of bovine serum albumin protein adsorbed. By preventing biofouling, the polyaniline-Pluronic blends can become more useful as biosensors than the polyaniline films.