Fourier Transform Infrared Spectroscopy (fourier + transform_infrared_spectroscopy)

Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Kinds of Fourier Transform Infrared Spectroscopy

  • reflectance fourier transform infrared spectroscopy
  • total reflectance fourier transform infrared spectroscopy

  • Terms modified by Fourier Transform Infrared Spectroscopy

  • fourier transform infrared spectroscopy analysis

  • Selected Abstracts


    JOURNAL OF PHYCOLOGY, Issue 2 2001
    Colette Sacksteder
    No abstract is available for this article. [source]


    JOURNAL OF PHYCOLOGY, Issue 2 2001
    Mario Giordano
    Fourier Transform Infrared (FT-IR) spectroscopy was used to study carbon allocation patterns in response to changes in nitrogen availability in the diatom Chaetoceros muellerii Lemmerman. The results of the FT-IR measurements were compared with those obtained with traditional chemical methods. The data obtained with both FT-IR and chemical methods showed that nitrogen starvation led to the disappearance of the differences in cell constituents and growth rates existing between cells cultured at either high [NO3,] or high [NH4+]. Irrespective of the nitrogen source supplied before nitrogen starvation, a diversion of carbon away from protein, chlorophyll, and carbohydrates into lipids was observed. Under these conditions, cells that had previously received nitrogen as nitrate appeared to allocate a larger amount of mobilized carbon into lipids than cells that had been cultured in the presence of ammonia. All these changes were reversed by resupplying the cultures with nitrogen. The rate of protein accumulation in the N-replete cells was slower than the rate of decrease under nitrogen starvation. This study demonstrates that the relative proportions of the major macromolecules contained in microalgal cells and their changes in response to external stimuli can be determined rapidly, simultaneously, and inexpensively using FT-IR. The technique proved to be equally reliable to and less labor intensive than more traditional chemical methods. [source]

    Synthesis, Solution Structure and Biological Activity of Val-Val-Pro-Gln,a Bioactive Elastin Peptide

    Caterina Spezzacatena
    Abstract Val-Val-Pro-Gln (valyl-valyl-prolyl-glutamine) is a small but highly conserved sequence present in all elastins. We describe its synthesis by mixed anhydride solution chemistry as an alternative to solid-phase peptide synthesis (SPPS). The molecular structure of the tetrapeptide in solution was investigated by classical spectroscopy, such as circular dichroism (CD), nuclear magnetic resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The biological activity of Val-Val-Pro-Gln was evaluated by a bromodeoxyuridine (BrdU) incorporation assay with normal human dermal fibroblasts. This small peptide may play a critical role in control of matrix metabolism through its release from the elastin polypeptide chain during periods of tissue breakdown and remodelling. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

    Long-term effects of crop rotation and fertilization on soil organic matter composition

    M. Kaiser
    Summary Long-term effects of crop rotation and fertilization are mostly observed with respect to the amount of soil organic matter (SOM) and measured in terms of soil organic carbon (SOC). In this paper, we analyze the SOM composition of samples from long-term agricultural field experiments at sandy and clayey sites that include complex crop rotations and farm-yard manure applications. The organic matter (OM) composition of the soil samples, OM(Soil), and that of sequentially extracted water, OM(W), and sodium pyrophosphate, OM(PY), soluble fractions was analyzed using Fourier Transform Infrared Spectroscopy (FTIR). The fraction OM(PY) represented between 13 and 34% of SOC, about 10 times that of OM(W). Site specific differences in OM(Soil) composition were larger than those between crop rotations and fertilizer applications. The smaller C=O group content in FTIR spectra of OM(W) compared with OM(PY) suggests that analysis of the more stable OM(PY) fraction is preferable over OM(W) or OM(Soil) for identifying long-term effects, the OM(Soil) and OM(W) fractions and the content of CH groups being less indicative. Farm-yard manure application leads to a more similar content of C=O groups in OM(PY) between crop rotations and fertilizer plots at both sites. Short-term effects from soil tillage or potato harvesting on composition of OM require further studies. [source]

    Preparation and Characterization of Styrene Butadiene Rubber Based Nanocomposites and Study of their Mechanical Properties

    S. Sadhu
    Nanocomposites were prepared from styrene butadiene rubber (SBR) having different styrene contents and octadecyl amine modified Na-montmorillonite clay (OC). The modified and the unmodified clays were characterized with the help of X-ray diffraction technique (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM). All these nanocomposites were then subjected to tensile testing. The modified clay-rubber nanocomposites showed improved tensile strength (55% increase) and elongation at break (76% increase) compared to those of the gum vulcanizates. [source]

    Desorption kinetics of model polar stratospheric cloud films measured using Fourier Transform Infrared Spectroscopy and Temperature-Programmed Desorption

    Birgit G. Koehler
    This study combines Fourier transform infrared (FTIR) spectroscopy and temperature-programmed desorption to examine the evaporation kinetics of thin films of crystalline nitric acid hydrates, solid amorphous H2O/HNO3 mixtures, H2O,ice, ice coated with HCl, and solid HNO3. IR spectroscopy measured the thickness of each film as it evaporated, either at constant temperature or during a linear temperature ramp (temperature-programmed infrared, TPIR). Simultaneously, a mass spectrometer measured the rate of evaporation directly by monitoring the evolution of the molecules into the gas phase (temperature-programmed desorption, TPD). Both TPIR and TPD data provide a measurement of the desorption rate and yield the activation energy and preexponential factor for desorption. TPD measurements have the advantage of producing many data points but are subject to interference from experimental difficulties such as uneven heating from the edge of a sample and sample-support as well as pumping-speed limitations. TPIR experiments give clean but fewer data points. Evaporation occurred between 170 and 215 K for the various films. Ice evaporates with an activation energy of 12.9 1 kcal/mol and a preexponential factor of 1 10321.5 molec/cm2 s, in good agreement with the literature. The beta form of nitric acid trihydrate, ,,NAT, has an Edes of 15.6 2 kcal/mol with log A = 34.3 2.3; the alpha form of nitric acid trihydrate, ,,NAT, is around 17.7 3 kcal/mol with log A = 37.2 4. For nitric acid dihydrate, NAD, Edes is 17.3 2 kcal/mol with log A = 35.9 2.6; for nitric acid monohydrate, NAM, Edes is 13 3 kcal/mol with log A = 31.4 3. The ,,NAT converts to ,,NAT during evaporation, and the amorphous solid H2O/HNO3 mixtures crystallize during evaporation. The barrier to evaporation for pure nitric acid is 14.6 3 kcal/mol with log A = 34.4 3. 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 295,309, 2001 [source]

    Rapid Analysis of Glucose, Fructose, Sucrose, and Maltose in Honeys from Different Geographic Regions using Fourier Transform Infrared Spectroscopy and Multivariate Analysis

    Jun Wang
    ABSTRACT:, Quantitative analysis of glucose, fructose, sucrose, and maltose in different geographic origin honey samples in the world using the Fourier transform infrared (FTIR) spectroscopy and chemometrics such as partial least squares (PLS) and principal component regression was studied. The calibration series consisted of 45 standard mixtures, which were made up of glucose, fructose, sucrose, and maltose. There were distinct peak variations of all sugar mixtures in the spectral "fingerprint" region between 1500 and 800 cm,1. The calibration model was successfully validated using 7 synthetic blend sets of sugars. The PLS 2nd-derivative model showed the highest degree of prediction accuracy with a highest,R2 value of 0.999. Along with the canonical variate analysis, the calibration model further validated by high-performance liquid chromatography measurements for commercial honey samples demonstrates that FTIR can qualitatively and quantitatively determine the presence of glucose, fructose, sucrose, and maltose in multiple regional honey samples. [source]

    Stacking interaction study of trans -resveratrol (trans -3,5,4,-trihydroxystilbene) in solution by Nuclear Magnetic Resonance and Fourier Transform Infrared Spectroscopy

    Claudia Bonechi
    Abstract Interactions between aromatic rings or other unsaturated systems, including ,-stacking and face-to-edge complexes, are the origin of many phenomena in both organic and biological chemistry. It is well known that these interactions play an important role in the stabilization of the stereo-structure of DNA and the tertiary structure of many proteins. Trans -resveratrol (trans -3,5,4,-trihydroxystilbene, trans -RSV) is a phytoalexin found in Vitis sp. and in many other plants and food products and has received much attention because of its possible positive health benefits. In this work, the ,-stacking interaction of trans -RSV was studied by nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. In particular, the proton chemical shift dependence of the RSV concentration in the range 2 10,2 , 1 10,5M and temperature were analysed. Moreover, the dynamics of the supramolecular aggregates were studied by nuclear spin relaxation data. Copyright 2008 John Wiley & Sons, Ltd. [source]

    Mechanical and tribological characterization of CNx films deposited by d.c. magnetron sputtering

    L. Ipaz
    Abstract Carbon nitride (CNx) thin films were deposited onto silicon and steel substrates at 400 C from a carbon target by d.c. magnetron sputtering system. The composition, structural, and mechanical properties of deposited films were investigated as a function of argon/nitrogen concentration and sputtering power, by means of Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy (RS), and nanoindentation. The EDS and Elastic Forward Analisys Analysis (EFA) showed that the nitrogen concentration in the CNx deposited films varied between 16% and 28% at depending on nitrogen concentrations in argon/nitrogen gas mixture, and deposition power. FTIR analysis indicated the presence of 2266 and 2278 cm,1 stretching peaks associated with CN triple bonds of nitriles and isocyanides, 1640 cm,1 and 1545 cm,1 associated with the C=C and C=N bonds. The thickness of the CNx deposited films varied between 0.4 and 0.8 m at different sputtering powers. The hardness and Young's modulus were investigated by depth sensing nanoindentation method. The obtained hardness and Young's modulus increased from 4 to 17 GPa, and from 50 to 170 GPa, respectively; when the nitrogen content in the deposited films diminished between 28 and 12%. On the other hand, the friction and wear tests were done using a pin-on-disc tribometer. The friction tests showed values of 0.05 and 0.4 in dry air and humid atmosphere; respectively. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Improvement of the interfacial compatibility between sugar cane bagasse fibers and polystyrene for composites

    POLYMER COMPOSITES, Issue 2 2004
    Edgar Garca-Hernndez
    Sugar cane bagasse fibers were modified by surface treatments using either physical or chemical methods in order to improve their adhesion to polystyrene matrices. The surface treatment methods used were alkaline treatment, treatment with silane coupling agents, physical coating with polystyrene and grafting of polystyrene with and without crosslinker. Fiber modifications were monitored by Fourier Transform Infrared Spectroscopy (FTIR), Differential Thermal Analysis coupled with Thermogravimetric Analysis (DTA-TGA) and Scanning Electron Microscopy (SEM). On the other hand, the improvement of the adhesion between sugar cane modified fibers and polystyrene was assessed by micromechanical pull-out and by macromechanical Iosipescu tests. It was found, from Interfacial Shear Strength values (IFSS), that substantial improvements in fiber-matrix compatibility were achieved. According to micro- and macromechanical test results, the IFSS increased for all treated fibers as compared to non-treated fibers. Particularly, both the coating the fibers or grafting with polystyrene using crosslinker resulted in substantial adhesion improvement to the polystyrene matrix in comparison with the non-treated fibers and fibers treated by alkaline and silane methods only. Polym. Compos. 25:134,145, 2004. 2004 Society of Plastics Engineers. [source]

    Comparative study of continuous-power and pulsed-power microwave curing of epoxy resins

    Bao Fu
    Three epoxy reaction systems, diglycidyl ether of bisphenol A (DGEBA) with curing agents meta phenylene diamine (mPDA), diaminodiphenyl methane (DDM), and diaminodiphenyl sulfone (DDS), were cured with both pulsed-power and continuous-power microwave curing systems. Isothermal curing was conducted at three different temperatures for each reaction system with both pulsed-power and continuous-power microwave curing systems. Extent of cure was measured with Fourier Transform Infrared Spectroscopy (FTIR). The temperature characteristics, incident and reflected power patterns, and the reaction rates were compared between the two curing approaches. The incident power and reflected power of both curing processes were observed to reveal reaction status. Continuous-power microwave curing produced noticeably higher reaction rates than pulsed-power microwave curing. [source]

    Biocatalytic hydrogels by template polymerization

    H. El-Sherif
    Abstract Novel ionizable hydrogels were prepared from poly(acrylic acid) and dimethylaminoethyl methacrylate monomer employing template polymerization technique as an alternative to traditional physical and chemical crosslinking. The mode of interaction, as proved by Fourier Transform Infrared Spectroscopy (FTIR), was multiple H-bonding between the tertiary amino group of the monomer and the carboxylic groups of the polymer. The hydrogels represented suitable matrices for enzyme immobilization. The effect of varying the polymer,monomer molar ratio on the swelling kinetics and parameters was investigated. The dynamic swelling isotherm exhibited a Fickian mode of penetrant sorption and a plateau that increases with the amino group content. A polymer complex of molar ratio (polymer:monomer) 0.5:0.8 had a weight swelling ratio of 10 and 7 at pHs 3 and 8, respectively. The proven pH sensitivity together with the amphoteric character of these hydrogels make them good candidates for another bioapplication such as oral delivery systems of therapeutic peptides and proteins. The structural integrity of the hydrogels was proved by their swelling reversibility. , -Galactosidase, as an acidic model enzyme, was immobilized covalently on the synthesized hydrogels. The maximum enzyme velocity (Vmax) was enhanced to 19,mol/min/mg, for polycomplex of molar ratio 0.5:0.8, compared with 3.2,mol/min/mg for the free enzyme. Copyright 2008 John Wiley & Sons, Ltd. [source]

    Comparison of Spiculogenesis in in Vitro ADCP-primmorph and Explants Culture of Marine Sponge Hymeniacidon perleve with 3-TMOSPU Supplementation

    Xupeng Cao
    This study aims to test the feasibility of introducing functional chemical groups into biogenic silica spicules by examining the effect of supplementing a silican coupler [3-(trimethoxysilyl)propyl]urea (3-TMOSPU) as silica source in the cultures of archaeocytes-dominant-cell-population (ADCP) primmorphs and explants of the marine sponge Hymeniacidon perleve. Analysis by Fourier Transform Infrared Spectroscopy (FT-IR) confirmed that the organic group in 3-TMOSPU was introduced into silica spicules. By comparing ADCP-primmorph cultures when supplemented with Na2SiO3, 3-TMOSPU supplementation showed no notable effect on the primmorphs development and cell locomotion behaviors. A decline in silicatein expression quantified by real-time RT-PCR was, however, observed during spiculogenesis. The decline was slower for the 3-TMOSPU group whereas significantly fewer spicules were formed. When sponge papillae explants were cultured, 3-TMOSPU supplementation had no negative effect on sponge growth but inhibited the growth biofouling of the diatom Nitzschia closterium. By monitoring the detectable Si concentration, it seemed that 3-TMOSPU was converted by the sponge and its conversion was related to spiculogenesis. Analysis of spicule dimensional changes indicated that the inhibition of spiculogenesis by 3-TMOSPU supplementation was less in ADCP-primmorphs culture due to lower 3-TMOSPU/detectable Si ratio in the media. [source]

    Preparation and sorption studies of ,-cyclodextrin/epichlorohydrin copolymers

    Dawn Y. Pratt
    Abstract ,-Cyclodextrin (,-CD) copolymer materials were synthesized by reacting different mole ratios (1 : 15, 1 : 25 and 1 : 35) of ,-CD with epichlorohydrin (EP). The products were characterized using N2 porosimetry, Fourier Transform Infrared spectroscopy, 13C CP-MAS NMR spectroscopy, thermogravimetry analysis, elemental (C and H) analysis, and scanning electron microscopy. The sorption properties in aqueous solution were studied using p-nitrophenol (PNP) with UV,Vis spectrophotometry. Sorption isotherms were obtained at pH 4.6 and three temperatures (22, 35, and 45C) and at pH 10.3 at 22C. The isotherms were analyzed using the BET isotherm model and the sorption parameters provided estimates of the surface area, sorption capacity, and isosteric heats of sorption for each polymeric material. The estimated surface areas are as follows: 58.2, 52.1, and 90.1 m2/g at pH 4.6. At pH 10.3, the estimated surface areas are 44.2, 40.5, and 58.5 m2/g, respectively. The removal efficiency of PNP by the polymeric materials ranged between 4.5 and 58% for the conditions investigated whereas the isosteric heats ranged between ,24.5 and ,13.6 kJ/mol. Removal efficiencies were concluded to strongly depend on the sorption conditions such as pH, temperature, and the relative amounts of sorbent and dye in aqueous solution. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    A bi-order kinetic model for poly(methyl methacrylate) decomposition in HNO3 using microwave irradiation

    AICHE JOURNAL, Issue 8 2009
    Chun-Chih Lin
    Abstract In this study, a novel bi-order model combined with zero- and first-order kinetics was proposed for the decomposition of PMMA (MW = 120,000 g/mol) in concentrated HNO3 by microwave irradiation. To develop and validate this model, Fourier Transform Infrared spectroscopy, scanning electron microscopy, fractional-life method, the gravimetric analysis and Newton's method were utilized. Rate constants, activation energies, the pre-exponential factors and the weight fractions (,) via main-chain scission for the decomposition at 423,453 K were derived from this model. The zero-order reaction was observed dominant at 423,443 K, while the first-order reaction dominated at 453 K and 473 K. The digestion efficiency increased as HNO3 was increased to >3 mL at 423 K,443 K. At 473 K, the digestion was almost 100% when HNO3 volume was >3 mL. The estimated , values increased with HNO3 volume at 423 and 443 K, but varied insignificantly at 453 and 473 K. 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

    Detecting amine vapours with thermally carbonized porous silicon gas sensor

    Mikko Bjrkqvist
    Abstract A capacitive type porous silicon based gas sensor for detecting amine vapours has been developed. The sensor is highly sensitive, e.g., to methylamine and trimethylamine vapours, and its electrical parameters recover totally after exposure to studied gases. Thermal carbonization of porous silicon under acetylene atmosphere was carried out to produce stable and attractive surface to amine vapours. The sensor response to studied amine vapours can be separated from its response to humidity changes since their electrical responses act reversely. In addition to the vapours of methylamine/water and trimethylamine/water solutions, the sensor was also used to detect different amines, which are generated during spoilage of raw shrimps and Baltic herring fillets at room temperature. Fourier Transform Infrared spectroscopy was used to detect the amine vapours and other volatile compounds simultaneously with sensor measurements. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Synthesis and characterization of styrene butadiene rubber,Bentonite clay nanocomposites

    Sugata Chakraborty
    In the present study, naturally occurring unfractionated bentonite clay was used to prepare styrene butadiene rubber/bentonite clay nanocomposite by latex stage blending. The bentonite clay was organo-modified by in situ resol formation by the reaction of resorcinol and formaldehyde. The latex clay mixture was co-coagulated with acid. The resulting clay masterbatch was compounded and evaluated by Fourier Transform Infrared spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDS), Scanning Electron Microscopy, Thermogravimetric analysis, and Differential Scanning Calorimetry. XRD showed that the interplanar distance of the in situ resol-modified bentonite clay increased from 1.23 to 1.41 nm for the unmodified bentonite. TEM analysis indicated partial exfoliation and/or intercalation. EDS (Si and Al mapping) of the clay revealed the nature of the dispersion in the nanocomposites vis--vis the conventional styrene-butadiene rubber (SBR)/bentonite clay composite. Thermogravimetric analysis was used to compare the decomposition trends of the SBR/clay nanocomposites with the SBR/clay composite. The glass transition temperature of SBR/clay nanocomposites increased as compared with that of neat SBR. Substantial improvement in most of the other mechanical properties was also observed in case of the nanocomposites. POLYM. ENG. SCI., 2009. 2009 Society of Plastics Engineers [source]

    Synthesis, structural and thermal studies of tetrathioureacopper(I) chloride crystals

    M. Dhandapani
    Abstract Tetrathioureacopper(I) chloride, hereafter abbreviated as TCC, was synthesised and single crystals were obtained from saturated aqueous solution by slow evaporation (solution growth) method at room temperature. The crystals obtained are bright, colourless and transparent having well defined external faces. The grown crystals were characterized through elemental analysis, single crystal X-ray diffraction study, thermal analysis, electron spin resonance spectroscopy and Fourier Transform infrared spectroscopy. The elemental analysis confirms the stoichiometry of the compound. The single crystal diffraction studies indicate that TCC crystallises in the tetragonal lattice and the unit cell parameters are a = b = 13.4082 , c = 13.8074 , V = 2482.29 3, , = , = , = 90. Space group and the number of molecules per unit cell (Z) are found to be P41212 and 8 respectively. The TG curve of the sample shows a prolonged decomposition from 210 to 628.3 C, from which the decomposition pattern has been formulated. The endothermic peaks in the DTA curve indicate melting and decomposition of the compound at 165.2 and 633.8 C respectively. An exothermic peak in high temperature DSC indicates a phase transition in the compound at 274.8 C. Thermal anomalies observed in the low temperature DSC at ,163.3, ,152.0, ,141.5, ,108.3, 1.0 and 12.1 C in the heating run and ,157.1 and ,153.9 C in the cooling run reveal first order phase transitions in the crystal. The peaks observed at ,146.2 C in both the heating and cooling runs suggest occurrence of a second order phase transition in this compound. The IR spectroscopic data were used to assign the characteristic vibrational frequencies of various groups present in the compound. The ESR study confirms that the copper is in the +1 oxidation state in the complex. ( 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    A simple method to obtain a swollen PVA gel crosslinked by hydrogen bonds

    Emiko Otsuka
    Abstract A simple method to obtain a physically crosslinked poly(vinyl alcohol) (PVA) hydrogel is reported. In this technique, the PVA solution in pure water was simply cast at room temperature without using any additional chemical. The gelation proceeded during the dehydration after casting the PVA solution into a mold. After the completion of gelation, the swelling ratio of the gel in its equilibrium was measured whenever the solvent water was repeatedly exchanged. The weight gradually decreased due to the elution of non-crosslinked polymers into the solvent, and became constant after sufficient water exchange. The measurements using a Fourier Transform infrared spectroscopy and an X-ray diffraction suggested that the crosslinks due to hydrogen bonds and microcrystals were formed during the dehydration process of the PVA solution. We concluded that the sample obtained by the present method is a physically crosslinked polymer network, insoluble in water, i.e., a swollen gel in water. 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]

    Investigation of drug,porous adsorbent interactions in drug mixtures with selected porous adsorbents

    Shadi Madieh
    Abstract The adsorption of drugs onto porous substrates may prove to be a convenient method by which to enhance the dissolution rate of certain poorly water-soluble drugs in body fluids. The purpose of this research is to provide a better understanding of the type of interactions occurring between drugs and certain pharmaceutically acceptable porous adsorbents that leads to enhanced drug dissolution rates. The interactions between ibuprofen (acidic drug), acetaminophen (acidic drug), dipyridamole (basic drug), and the porous adsorbents used (calcium silicate and silica gel) were investigated using differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier Transform infrared spectroscopy (FTIR). DSC and PXRD results indicated a significant loss of crystallinity of both ibuprofen and acetaminophen but not dipyridamole. In the case of ibuprofen, FTIR results indicated the ionization of the carboxylic group based on the shift in the FTIR carboxylic band. Dissolution of ibuprofen from its mixtures with porous adsorbents was found to be significantly higher compared to the neat drug, whereas dipyridamole dissolution from its mixtures with porous adsorbents was not significantly different from that of the neat drug. 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 851,863, 2007 [source]

    Microencapsulation of a functional dye and its UV crosslinking controlled releasing behavior

    Gangqiang Li
    Abstract A new family of microcapsules containing photopolymerizable tripropylene glycol diacrylate (TPGDA) was synthesized by using interfacial polymerization. The release behavior of encapsulated dye could be controlled easily by changing the crosslink density of network formed from TPGDA. The chemical structure and properties of microcapsules were characterized by Fourier Transform infrared spectroscopy, scanning electron microscope, differential scanning calorimetry, optical microscope, wide angle X-ray diffraction and UV-visible spectrophotometer. The results demonstrate that the higher agitation rate results in a smaller particle size with a narrow size distribution. When core/shell ratio is low, the surface of the microcapsules becomes smooth. Additionally, it was found that UV radiation time is most effective factor to change the CC double bond conversion ratio. After microcapsules were synthesized, the release speed could be changed according to requirement by exposing them to UV light for minutes. 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3630,3639, 2009 [source]

    Covalent addition of diethyltoluenediamines onto carbon nanotubes for composite application

    POLYMER COMPOSITES, Issue 8 2009
    Shiren Wang
    Diethyltoluenediamines (DETDA) was grafted to single-walled carbon nanotubes (SWNTs) through diazonium-based addition for improving dispersion and interfacial bonding in SWNT/epoxy nanocomposites. Characterization results of Fourier Transformed Infrared spectroscopy and Raman spectroscopy validated covalent bonding between DETDA and carbon nanotubes. The degree of functionalization was about 4% based on thermo-gravimetric analysis. Interfacial bonding strength was computed in the presence of chemical bonding and the computation results indicated that the interfacial shear strength in the presence of functionalized carbon nanotubes was significantly enhanced. The experimental test revealed that the tensile strength of nanocomposites was enhanced about 23% and Young's modulus about 25%, with 0.5 wt% loading of functionalized-nanotubes. These considerable improvements further verified the load-transfer enhancement in the functionalized-SWNTs/epoxy nanocomposites. POLYM. COMPOS., 2009. 2008 Society of Plastics Engineers [source]

    Separation and recovery of cellulose and lignin using ionic liquids: a process for recovery from paper-based waste

    Huma Lateef
    Abstract BACKGROUND: The production of paper makes use of cellulose and lignin as a raw material, and almost all cellulose and lignin production comes from raw wood materials, contributing to deforestation and resulting in potential environmental harm. It is therefore beneficial to develop technologies for cellulose and lignin recovery for re-use and sustainability of resources. RESULTS: Three imidazolium based ionic liquids (ILs), 1-(2-cyanoethyl)-3-methylimidazolium bromide (cyanoMIMBr), 1-propyl-3-methylimidazolium bromide (propylMIMBr) and 1-butyl-3-methylimidazolium chloride (butylMIMCl), were synthesised by microwave technology and fully characterised by mass spectrometry, thermogravimetric differential scanning calorimetry, thin layer chromatography, nuclear magnetic resonance and Fourier transform infrared spectroscopies. Cellulose and lignin were soluble in all three ILs with solubility being greatest in cyanoMIMBr. Regeneration of cellulose and lignin was achieved from saturated solutions of cellulose in IL and lignin in IL for all three ILs. The ILs propylMIMBr and butylMIMBr have been used for the first time in the separation and recovery of cellulose and lignin and regeneration of the IL from a mixture of cellulose and lignin in IL. FTIR analysis confirms successful recovery. CONCLUSIONS: This work demonstrates the ability of ILs to separate and recover cellulose and lignin from a mixed system. Copyright 2009 Society of Chemical Industry [source]

    Synthesis of rhombohedral strontium carbonate aggregates at the water/hexamethylene interface with cetyltrimethylammonium bromide

    Long Chen
    Abstract Unusual rhombohedral strontium carbonate (SrCO3) aggregates have been synthesized in situ from strontium nitrate by the slow release of carbon dioxide by alkaline hydrolysis of diethyl carbonate at the water/hexamethylene interface in the presence of cetyltrimethylammonium bromide (CTAB). Transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray powder diffractometry were used to characterize the products. The results indicate that rhombohedral SrCO3 aggregates are obtained with weaker crystallinity and sizes of several micrometers. The possible formation mechanism of the SrCO3 aggregates at the interface is discussed, which can be interpreted by particle-aggregation based non-classical crystallization laws. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Crystallization behaviors of carbon fiber reinforced BN-Si3N4 matrix composite

    Bin Li
    Abstract The crystallization behaviors of a new carbon fiber reinforced composite with a hybrid matrix comprising BN and Si3N4 prepared by precursor infiltration and pyrolysis were investigated by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The results show that the as-received composite is almost amorphous, and its main composition is BN and Si3N4. When heat treated at 1600C, the composite is crystallized and shows a much better crystal form. When heat treated at 2100C, Si3N4 in the matrix is decomposed, and BN exhibits a relatively complete crystallization. The existence of B4C and SiC is detected, which indicates the interfacial chemical reactions between nitride matrices and carbon fibers. The surface morphology of carbon fibers in the composite changed significantly when heated from 1600 to 2100C, which also proved the occurrence of interfacial chemical reactions. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Crystal growth of some urinary stone constituents: II.

    In-vitro crystallization of hippuric acid
    Abstract Hippuric acid [C6H5CONHCH2COOH], one of the organic chemical constituents of urinary stone is crystallized in silica gel under suitable pH conditions by double diffusion method. The grown crystals were characterized by density measurement, Fourier transform infrared spectroscopy, X-ray powder diffraction and thermogravimetric analysis. [source]

    Characterization of biochar from fast pyrolysis and gasification systems

    Catherine E. Brewer
    Abstract Thermochemical processing of biomass produces a solid product containing char (mostly carbon) and ash. This char can be combusted for heat and power, gasified, activated for adsorption applications, or applied to soils as a soil amendment and carbon sequestration agent. The most advantageous use of a given char depends on its physical and chemical characteristics, although the relationship of char properties to these applications is not well understood. Chars from fast pyrolysis and gasification of switchgrass and corn stover were characterized by proximate analysis, CHNS elemental analysis, Brunauer-Emmet-Teller (BET) surface area, particle density, higher heating value (HHV), scanning electron microscopy, X-ray fluorescence ash content analysis, Fourier transform infrared spectroscopy using a photo-acoustic detector (FTIR-PAS), and quantitative 13C nuclear magnetic resonance spectroscopy (NMR) using direct polarization and magic angle spinning. Chars from the same feedstocks produced under slow pyrolysis conditions, and a commercial hardwood charcoal, were also characterized. Switchgrass and corn stover chars were found to have high ash content (32,55 wt %), much of which was silica. BET surface areas were low (7,50 m2/g) and HHVs ranged from 13 to 21 kJ/kg. The aromaticities from NMR, ranging between 81 and 94%, appeared to increase with reaction time. A pronounced decrease in aromatic CH functionality between slow pyrolysis and gasification chars was observed in NMR and FTIR-PAS spectra. NMR estimates of fused aromatic ring cluster size showed fast and slow pyrolysis chars to be similar (,7,8 rings per cluster), while higher-temperature gasification char was much more condensed (,17 rings per cluster). 2009 American Institute of Chemical Engineers Environ Prog, 2009 [source]

    Kinetics of toluene sorption and desorption in Ca- and Cu-montmorillonites investigated with Fourier transform infrared spectroscopy under two different levels of humidity

    Yang-Hsin Shih
    Abstract Clays in soils or groundwater aquifer materials play roles in the sorption of organic pollutants. The intrinsic sorption kinetics of toluene in dry and humid clay films was investigated by tracking the change of infrared absorbance. Under the humid condition, similar toluene-sorbed intensities were found in Ca- and Cu-montmorillonites. However, a higher intensity of sorbed toluene was found in the Cu-form than in the Ca-form under the dry condition, which indicates a stronger interaction occurring in dry Cu-montmorillonite. The general time scale of sorption of toluene on clays is around 100 s. In both forms of montmorillonite, some portion of toluene was desorbed at an extremely slow rate under the dry condition. Some newly identified peaks were persistent against desorption from montmorillonites, suggesting the existence of irreversibly sorbed species and the possibility of toluene transformation occurring in clay systems. [source]

    Synthesis and Monitoring of ,-Bi2Mo3O12 Catalyst Formation using Thermo-Raman Spectroscopy

    Anil Ghule
    Abstract Thermo-Raman spectroscopy was used to monitor the dehydration and phase transformations of Bi2Mo3O125H2O. The hydrated forms Bi2Mo3O125H2O, Bi2Mo3O124.75H2O, Bi2Mo3O123H2O, Bi2Mo3O122H2O, and anhydrous Bi2Mo3O12 were observed during dehydration in the wavelength range from 200 to 1400 cm,1. Representative Raman spectra of these compounds are reported for the first time. The thermo-Raman intensity thermogram showed a systematic dehydration in four steps, and the differential thermo-Raman intensity thermogram confirmed this. Thermogravimetry, differential thermogravimetry, and differential scanning calorimetry results were in harmony with the results of the thermo-Raman spectroscopy. Additionally, the dehydration resulting in formation of anhydrous Bi2Mo3O12 (amorphous Bi2Mo3O12 phase) and the final transformation into the ,-Bi2Mo3O12 phase was observed to be a dynamic thermal process. The slow, controlled heating rate produced ,-Bi2Mo3O12 catalyst with a particle size averaging 200 nm. The catalyst formed was further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, time of flight SIMS, transmission electron microscopy, and energy-dispersive X-ray analysis. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

    Construction of Polyethyleneimine-,-cyclodextrin/pDNA Multilayer Structure for Improved In Situ Gene Transfection,

    Yan Hu
    This study reports in situ gene delivery from gene-functionalized poly(D,L -lactic acid) (PDLLA, Mw of around 2.0,,105,g,mol,1) films, which were constructed via layer-by-layer (LbL) assembly technique with low molecular weight polyethylenimine-,-cyclodextrin (PEI-CD) conjugate and plasmid DNA (pDNA). PEI-CD was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR), respectively. The buildup of multilayered PEI-CD/pDNA pairs onto PDLLA films was monitored with contact angle measurements and UV,Vis spectrometer, respectively. A sustained release of pDNA from multilayered films was observed for 28,h. The mechanism of in situ gene delivery on PDLLA film was investigated in this study as well. Spherical PEI-CD/pDNA complexes were formed and released following the deconstruction of multilayered films, which was confirmed by transmission electron microscopy (TEM) and gel electrophoresis, respectively. Surface mediated in situ gene transfection was achieved when culturing hepatoma G2 (HepG2) and human embryonic kidney 293 (HEK293) onto PEI-CD/pDNA multilayered films. Furthermore, PEI-CD improved the gene transfection efficiency when compared with that of PEI. Such gene-functionalized biomaterial reported here has potential application in tissue engineering and implant technology. [source]