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FTIR Spectra (ftir + spectrum)
Selected AbstractsVibrational, optical and microhardness studies of trimethoprim DL -malateCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2009S. Franklin Abstract Trimethoprim malate, an organic crystal, has been synthesized using slow evaporation method from its aqueous solution. Structural, optical and the mechanical properties of the grown crystal have been investigated by various characterization techniques which include FTIR spectra, single crystal XRD, UV-Vis spectra and Vickers microhardness testing. The structure of the compound predicted by analysing the recorded FTIR spectrum compliments the structure determined using single crystal X-ray diffraction. Single crystal X-ray diffraction study reveals that the crystals are monoclinic [P21/c, a=12.9850 Å, b=9.3038 Å, c=15.6815 Å and ,=111.065°]. The UV-Vis spectrum exhibits maximum transparency (98%) for a wide range suggesting the suitability of the title compound for optical applications. The optical constants have been calculated and illustrated graphically. Microhardness tests have been performed on the cystal under study and the Vicker hardness number has been calculated. The work hardening coefficient is found to be 2.85 which suggest that the crystal belongs to the family of soft materials. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Long-term effects of crop rotation and fertilization on soil organic matter compositionEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2007M. 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] Thermal aging of a blend of high-performance fibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Carlos Arrieta Abstract The focus of this work is the study of the thermal aging of high-performance fibers used in the making of fire protective garments. Accelerated thermal aging tests were carried out on fabric samples made up of a blend of Kevlar® (poly p -phenylene terephthalamide) and PBI (poly benzimidazole) staple fibers, as well as on yarns pulled from this fabric, by means of exposure to elevated temperatures, comprised between 190°C and 320°C. All samples underwent loss of breaking force retention. The material thermal life, defined as the time required for the fibers to attain a 50% reduction of the original breaking force, ranged between a dozen of days at the lowest exposure temperature, to less than an hour at the highest. Breaking force data were fitted using the Arrhenius model following two different approaches, namely the extrapolated thermal life value and the shift factors yielded by the time-temperature superposition (TTS). The Arrhenius model seemed to describe appropriately the overall aging process, as inferred from the excellent fit obtained when using both approaches, although activation energies provided from both approaches are different. To follow the chemical evolution of the material with thermal aging, Fourier-transform infrared (FTIR) analyses were conducted. The qualitative analysis of the FTIR spectra showed little evidence of chemical changes between the aged and the nonaged samples, indicating either that the aging process carries on without significant modification of the chemical structure of the fibers, or that FTIR is not an appropriate method to spot such a modification. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Comparison of specific interactions in P4VP/PSCA and PS4VP/PSCA blends and complexesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Naima Bouslah Abstract The compatibilization of an immiscible polymer system polystyrene/poly(4-vinylpyridine) has been induced by the introduction of carboxylic acid groups within the polystyrene chains. Poly(styrene- co -cinnamic acid), PSCA, copolymers were used to prepare blends and complexes with poly(4-vinylpyridine), P4VP, and in a second time with poly(styrene- co -4-vinylpyridine), PS4VP, copolymer in order to reduce the density of the interacting groups. The miscibility of the systems has been ascertained by DSC, which revealed that both blends and complexes exhibit a single glass transition temperature indicating their single phase nature. The Tgs of the complexes of PS4VP with PSCA15, containing 15 mol % of cinnamic acid content, were higher than those of the corresponding blends indicating that stronger interpolymer interactions were developed in the complexes. Furthermore, the application of the Kwei equation suggested that P4VP interacts more strongly with PSCA15 than does PS4VP. FTIR spectra revealed the development of hydrogen bonding within the PS4VP/PSCA system and both hydrogen bonding and ionic interaction in the P4VP/PSCA blends whereas the same interactions were expected in both systems. This observation confirmed the stronger ability of P4VP to interact with PSCA copolymer. The viscosimetric study showed both positive and negative deviations of the reduced viscosity of the blends from the additivity law confirming the presence of specific interactions within the blend solutions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Novel jute yarns grafted with methyl methacrylateJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008M. Montazer Abstract This research work involves graft copolymerization of jute fibers with methyl methacrylate (MMA), initiated by cerric ions, and optimization of the grafting parameters as a function of different polymerization conditions. It was considered to produce a hydrophobic jute fiber with enhanced properties. To achieve this, the effects of monomer concentration and grafting percentage on FTIR spectra, mechanical properties, moisture regain, oil-adsorption capacity, and surface morphology were investigated, and optimum percentage of MMA with reasonable properties was suggested. The results indicated that cerric ions initiated graft copolymerization of MMA onto jute with 30% of weight of monomers at optimum conditions of acid concentration and temperature. The FTIR studies proposed grafting of MMA onto jute at hydroxyl groups. The results showed that mechanical properties and moisture regain (%) of samples decrease with increasing of graft percentage. The most remarkable features of this investigation include reducing oil-adsorption capacity with increasing of lipophilic monomer percentages after one limitation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Using anionic polymerizable surfactants in ultrasonically irradiated emulsion polymerization to prepare polymer nanoparticlesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Yuhui He Abstract An ionic polymerizable surfactant, sodium sulfopropyl-laurylmaleate (M12), was synthesized and used as an emulsifier, an initiator, and a comonomer in ultrasonically irradiated emulsion polymerization. FTIR spectra and gravimetric method results indicated that copolymers P(Styrene-M12) and P(Butylacrlate-M12) were prepared successfully by ultrasonically irradiated emulsion polymerization and the composition of M12 elevated with the increasing concentration of M12 added. TEM photographs of P(St-M12) showed that the nanoparticles with small diameters (20,45 nm) were prepared. With the increase of M12 concentration, the particle size became smaller and the size distribution became wider. The P(BA-M12) particles size was also small (<100 nm) but the size distribution was wide due to the high reactivity of BA. Because surfmer M12 was chemically bonded with the latex particles, the stability of the copolymer latex prepared by ultrasonically irradiated emulsion polymerization was much better than that of the homopolymer latex (PSt or PBA) prepared by the same way. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Characterization of liquefied wood residues from different liquefaction conditionsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Hui Pan Abstract The amount of wood residue is used as a measurement of the extent of wood liquefaction. Characterization of the residue from wood liquefaction provides a new approach to understand some fundamental aspects of the liquefaction reaction. Residues were characterized by wet chemical analyses, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The Klason lignin content of the residues decreased, while the holocellulose and ,-cellulose contents increased as the phenol to wood ratio (P/W) increased. A peak at 1735 cm,1, which was attributed to the ester carbonyl group in xylan, disappeared in the FTIR spectra of the residues from liquefied wood under a sealed reaction system, indicating significantly different effects of atmospheric versus sealed liquefaction. The crystallinity index of the residues was higher than that of the untreated wood particles and slightly increased with an increase in the P/W ratio. The SEM images of the residues showed that the fiber bundles were reduced to small-sized bundles or even single fibers as the P/W ratio increased from 1/1 to 3/1, which indicated that the lignin in the middle lamella had been dissolved prior to the cellulose during liquefaction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Effects of magnetic field and rare-earth ions on properties of polyaniline nanoparticlesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007Shuling Zhang Abstract The uniform polyaniline nanoparticles with the size of about 50 nm were electropolymerized using the method of constant potential of 0.8 V. The effects of rare-earth cations and magnetic field on the preparation and properties of polyaniline were investigated. It was found that the addition of rare-earth cations could enhance the effect of magnetic field on the properties of polyaniline. The resulting products were characterized by FTIR spectra, UV,vis spectra and scanning electron microscope (SEM); the conductivity and cyclic voltammetry (CV) were also investigated. The experimental results show that the magnetic field has an orientation effect on polyaniline chain and there exists the interaction between rare-earth cations and polyaniline chain because of the electrostatic interaction. The addition of rare-earth cations can increase electrical conductivity, moreover, the effect of NdCl3 and ErCl3 on properties of polyaniline is more remarkable than LaCl3 and SmCl3. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2286,2294, 2007 [source] Discrimination of cyanobacterial strains isolated from saline soils in Nakhon Ratchasima, Thailand using attenuated total reflectance FTIR spectroscopyJOURNAL OF BIOPHOTONICS, Issue 8-9 2010Somchanh Bounphanmy Abstract A method was developed whereby high quality FTIR spectra could be rapidly acquired from soil-borne filamentous cyanobacteria using ATR FTIR spectroscopy. Spectra of all strains displayed bands typical of those previously reported for microalgae and water-borne cyanobacteria, with each strain having a unique spectral profile. Most variation between strains occurred in the C,O stretching and the amide regions. Soft Independent Modelling by Class Analogy (SIMCA) was used to classify the strains with an accuracy of better than 93%, with best classification results using the spectral region from 1800,950 cm,1. Despite this spectral region undergoing substantial changes, particularly in amide and C,O stretching bands, as cultures progressed through the early-, mid- to late-exponential growth phases, classification accuracy was still good (,80%) with data from all growth phases combined. These results indicate that ATR/FTIR spectroscopy combined with chemometric classification methods constitute a rapid, reproducible, and potentially automated approach to classifying soil-borne filamentous cyanobacteria. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and characterization of a poly(GMA)-graft-poly(Z- L -lysine) graft copolymer with a rod-like structureJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2009You-Liang Tu Abstract This study applied the macromonomers and glycidyl methacrylate (GMA) to synthesize a series of the graft copolymers, poly(GMA)-graft-poly(Z- L -lysine), and investigated the conformation of the graft copolymer. The graft copolymers were synthesized with different GMA monomer ratios (28 to 89%) and different degrees of polymerization (DP) (8 to 15) of the poly(Z- L -lysine) side chain to analyze secondary structure relationships. Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and both wide angle and small angle X-ray scattering spectroscopy (WAXS, SAXS) were used to investigate the relationship between the microstructure and conformation of the graft copolymers and the different monomer ratios and side chain DP. In AFM images, n8-G89 (the graft copolymer containing 89% GMA units and the macromonomer DP is 8) showed tiny and uniform rod-like structures, and n14-G43 (the graft copolymer containing 43% GMA units and the macromonomer DP is 14) showed uniform rod-like structures. FTIR spectra of the graft copolymers showed that the variations of ,-helix and ,-sheet secondary structures in the graft copolymers relate to the monomer ratios of the graft copolymers. However, the X-ray scattering patterns indicated that the graft copolymer conformations were mainly dependent on the poly(Z- L -lysine) side chain length, and these results were completely in accordance with the AFM images. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4655,4669, 2009 [source] Polyrotaxanes based on polyethers and ,-cyclodextrinJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2009Saloua Chelli Abstract A polyrotaxane in which ,-cyclodextrins (,-CDs) are threaded onto a polyether chain was prepared by polycondensation of a ,-CD/bisphenol A (BPA) inclusion complex with aromatic dihalides. Two dihalides, with and without a side chain, were used. This polycondensation results in a polyrotaxane (or pseudopolyrotaxane for polymers without stoppers) with a 1:1 threading ratio when the side chain is present and 2:3 when there is none. The long side chain prevents dethreading of the macrocycles. The best yield and a good threading ratio were obtained when the polycondensation was performed by liquid,solid phase transfer catalysis without solvent (L/S PTC) using 2,5-bi(iodomethyl)-4-methoxy-(1-octyloxy)benzene as dihalide. The 1H NMR and FTIR spectra show that the products consist of ,-CD and polyether. The 2D NOESY NMR spectrum shows that the polyether chains are included in the ,-CD cavity. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4391,4399, 2009 [source] Examination of pigments on Thai manuscripts: the first identification of copper citrateJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2008Katherine Eremin Abstract Samples from Thai manuscripts dated to the 18th to 20th century were analyzed by Raman spectroscopy and Fourier-transform infrared spectroscopy (FTIR) to determine the pigments used. This suggested a change in palette from the 18th to 20th century, with use of imported pigments in the later manuscripts. In the 18th century, the main green used was an organic copper salt, which was replaced by emerald green and mixtures of Prussian blue with gamboge, chrome yellow and zinc yellow (zinc potassium chromate). Chrome yellow was used in addition to gamboge in one later 19th century manuscript. Similarly, indigo in the 18th century manuscripts was replaced by Prussian blue and then synthetic ultramarine in the 19th century manuscripts. Lead white was the main white pigment in all but one manuscript, which contained huntite, a magnesium calcium carbonate. Huntite also occurred in mixtures with other pigments in two other manuscripts. In all the works studied, red lead, vermilion and red earth were used for red, orange and pink shades and red earth in brown areas. The organic copper salt used in the 18th century gave good FTIR spectra but could not initially be matched with any published compound. X-ray diffraction (XRD) suggested this was a copper citrate phase, and examination of the literature showed that the FTIR spectra matched those published for a hydrated copper citrate. Raman spectra were obtained from this organic copper salt, which showed close agreement with those obtained from synthetic copper citrate. Copper citrate has not been identified previously as an artist's material, although its use has been postulated on the basis of historical texts. Minor copper formate and/or copper chloride were also identified by XRD and scanning electron microscopy (SEM) in some green samples containing copper citrate. Copyright © 2008 John Wiley & Sons, Ltd. [source] Fourier transform Raman and Fourier transform infrared spectra of cross-linked polyurethaneurea films synthesized from solutionsJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2002Valentina Romanova Cross-linked polyurethaneurea films based on polyoxytetramethylene glycol and polyoxypropylene glycol with toluene diisocyanate and 3,3,-dichloro-4,4,-diaminodiphenylmethane were synthesized in a solution where the solvent evaporates during the polymerization. FT-Raman and FTIR spectra were analysed and intermolecular force constants of hydrogen bonds were calculated. On the basis of the intensity of the Raman and IR spectral lines, which reflects hydrogen bond formation, the optimum structure of hydrogen bonds and the conformations of macromolecules of polyurethaneurea were observed for the solvent ethyl acetate. Copyright © 2002 John Wiley & Sons, Ltd. [source] Deposition of Carbonated Hydroxyapatite (CO3HAp) on Poly(Methylmethacrylate) Surfaces by Decomposition of Calcium,EDTA ChelateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2008Yusuf Yusufoglu Inspired from the nature, the development of organic,inorganic composites between polymers and hydroxyapatite (HAp) has been investigated extensively. In this study, bone-like apatite (carbonated hydroxyapatite, CO3HAp) was precipitated on poly(methylmethacrylate) (PMMA) films by the oxidative decomposition of Ca,EDTA (calcium,ethylenediamine tetraacetate) chelates. Corona-treated PMMA films were soaked in a Ca,EDTA,PO4,H2O2 solution and aged at 63°C and pH,9 for times ranging from 1 to 24 h. Apatite formed on PMMA films was characterized by X-ray diffraction, Fourier transform infrared (FTIR), Scanning electron microscope, energy-dipersive X-ray spectroscopy, and carbon analysis. The apatite was found to be CO3HAp with Ca/P atomic ratio ranging between 1.3 and 1.9. Elemental analyses indicated that the carbonate content of the apatite phase was around 6.5 wt% after 24 h of aging time. Lattice parameters were estimated using a Rietveld profile-analysis and found to be a=0.9438 nm and c=0.6901 nm. Furthermore, FTIR spectra indicated that the apatite deposited on PMMA was B-type CO3HAp, in which carbonate ions occupy the phosphate sites. In the first 3 h of aging, isolated rod-like HAp particles were observed. With time, the needle-like crystallites radiate from a nucleus to form double-spherulite shape particles. The crystallites grew into a continuous layer with a thickness of ,15 ,m after 24-h aging. The adhesive strength between the PMMA substrate and the apatite layer was determined to be around 1.7 MPa. [source] Tuning the Photoluminescence of Silsesquioxanes with Short Substituted Urea BridgesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 6 2008María L. Gómez Abstract The polycondensation of a precursor synthesized by the reaction of 3-(anilinepropyl)trimethoxysilane with 3-(isocyanatopropyl)triethoxysilane led to a silsesquioxane bearing a substituted urea group in the short organic bridge. The self-assembly of organic bridges, analyzed by SAXS and FTIR spectra, could be controlled by varying the conditions of the synthesis. Depending on the size of organic clusters, the silsesquioxane exhibited photoluminescence either in the green or red regions of the spectra, or an emission that could be tuned in the whole visible region by the excitation wavelength. [source] A Novel N -Succinylchitosan- graft -Polyacrylamide/Attapulgite Composite Hydrogel Prepared through Inverse Suspension PolymerizationMACROMOLECULAR MATERIALS & ENGINEERING, Issue 8 2007Ping Li Abstract A novel N -succinylchitosan- graft -polyacrylamide/attapulgite composite hydrogel was prepared by using N -succinylchitosan, acrylamide and attapulgite through inverse suspension polymerization. The result from FTIR spectra showed that OH of attapulgite, OH and NHCO of N -succinylchitosan participated in graft polymerization with acrylamide. The introduced attapulgite could enhance thermal stability of the hydrogel. Scanning electron microscopy observation indicates that the composite hydrogel has a microporous surface. The volume ratio of heptane to water, weight ratio of acrylamide to N -succinylchitosan and attapulgite content have great influence on swelling ability of the composite hydrogel. The composite hydrogel shows higher swelling rate and pH-sensitivity compared to that of without attapulgite. [source] Electrospinning of Collagen Nanofiber Scaffolds from Benign SolventsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 7 2009Bin Dong Abstract Nanofiber scaffolds of collagen have been fabricated via electrospinning using benign solvent systems as a replacement for 1,1,1,3,3,3 hexafluoro-2-propanol. Simple binary mixtures of phosphate-buffered saline and ethanol have been found to be highly effective for electrospinning. FTIR spectra suggest that the triple helical structure of collagen was conserved after dissolution and electrospinning. Crosslinking of the electrospun collagen scaffolds was achieved with standard methods. [source] Improvement in crystalline perfection, piezo-electric property and optical transparency of in-situ poled Fe,LiNbO3 single crystals by post growth annealing and polingPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2005G. C. Budakoti Abstract Crystalline perfection, piezoelectric response and optical transparency of in-situ poled Fe,LiNbO3 single crystals was studied. Very low angle grain boundaries and the variations in the piezoelectric charge constant d33 were observed in the as-grown crystals. Grain boundaries were successfully removed at higher annealing temperatures but the d33 value was decreased. Low crystalline perfection and d33 were observed after poling the annealed specimen. These parameters were improved by low temperature annealing followed by very slow cooling. FTIR spectra revealed that OH, and CO32, ionic defects were present in the as-grown crystals. The OH, ion concentration was reduced, CO32, ions were removed and optical quality was improved after annealing at higher temperatures. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Plasma Polymerization of HMDSO with an Atmospheric Pressure Plasma Jet for Corrosion Protection of Aluminum and Low-Adhesion SurfacesPLASMA PROCESSES AND POLYMERS, Issue 10 2009Uwe Lommatzsch Abstract Thin functional films were deposited on aluminum with an atmospheric pressure plasma jet using hexamethyldisiloxane (HMDSO) as precursor. A high dynamic deposition rate on the order of 450,nm,·,m,·,min,1 was achieved. Composition and structure of the thin films show a strong dependence on the downstream location of the precursor injection. A 4,mm downstream shift of the precursor injection increases the carbon content in the thin film by a factor of 2.5, as indicated by XPS analysis and alters the degree of cross-linking according to the FTIR spectra. The coating with the low carbon content (17 at.-%) provides corrosion resistance for aluminum 2024 unclad exposed for 96,h to a neutral salt spray test. The coating with the high carbon content reduces the adhesion of an epoxy resin to the surface and may be used as a release coating. [source] Study on superabsorbent composite XXV.POLYMER COMPOSITES, Issue 4 2010Synthesis, characterization, swelling behaviors of poly(acrylic acid- co - N -acryloylmorpholine)/attapulgite superabsorbent composites In this work, a novel poly(acrylic acid- co - N -acryloylmorpholine)/attapulgite superabsorbent composite was prepared by graft copolymerization among acrylic acid, N -acryloylmorpholine and attapulgite in aqueous solution, using N,N, -methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The result from FTIR spectra showed that OH of attapulgite participated in graft copolymerization with acrylic acid and N -acryloylmorpholine. Proper monomer ratio and atapulgite content could form a loose surface, and improve reswelling ability and initial swelling rate. The buffer action of the COOH and COO, groups in the superabsorbent composite keeps the water absorbency a rough constant in the pH range of 4.4,9.6. Both polarity and structure of an organic solvent are responsible for the phase transition point of the superabsorbent composite. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] Compatibilizing effect of ethylene,propylene,diene grafted maleic anhydride terpolymer on the blend of polyamide 66 and thermal liquid crystalline polymerPOLYMER COMPOSITES, Issue 6 2006Qunfeng Yue Polyamide 66,thermal liquid crystalline polymer (PA66/TLCP) composites containing 10 wt% TLCP was compatibilized by ethylene,propylene,diene-grafted maleic anhydride terpolymer (MAH- g -EPDM). The blending was performed on a twin-screw extrusion, followed by an injection molding. The rheological, dynamic mechanical analysis (DMA), thermal, mechanical properties, as well as the morphology and FTIR spectra, of the blends were investigated and discussed. Rheological, DMA, and FTIR spectra results showed that MAH- g -EPDM is an effective compatibilizer for PA66/TLCP blends. The mechanical test indicated that the tensile strength, tensile elongation, and the bending strength of the blends were improved with the increase of the content of MAH- g -EPDM, which implied that the blends probably have a great frictional shear force, resulting from strong adhesion at the interface between the matrix and the dispersion phase; while the bending modulus was weakened with the increase of MAH- g -EPDM content, which is attributed to the development of the crystalline phase of PA66 hampered by adding MAH- g -EPDM. POLYM. COMPOS., 27:608,613, 2006. © 2006 Society of Plastics Engineers [source] Structure, electrical and optical properties of (PVA/LiAsF6) polymer composite electrolyte filmsPOLYMER ENGINEERING & SCIENCE, Issue 5 2010Madhu Mohan Varishetty In this work, Li+ ion conducting polymer composite electrolyte films (PECs) were prepared based on poly (vinyl alcohol) (PVA), lithium hexafluoro arsenate (LiAsF6), and ceramic filler TiO2 using solution cast technique. The XRD and FTIR spectra were used to determine the complexation of the PVA polymer with LiAsF6 salt. The ionic conductivities of the (PVA + LiAsF6) and (PVA + LiAsF6 + TiO2) films have been determined by the A.C. impedance measurements in the temperature range 320,440 K. The maximum conductivity was found to be 5.10 × 10,4 S cm,1 for PVA:LiAsF6 (75:25) + 5 wt% TiO2 polymer composite film at 320 K. The calculation of Li+ ion transference number was carried out by the combination of A.C. impedance and D.C. polarization methods and is found to be 0.52 for PVA:LiAsF6 (75:25) + 5 wt% TiO2 film. Optical properties such as direct energy gap, indirect energy gap, and optical absorption edge values were investigated in pure PVA and salt complexed PVA films from their optical absorption spectra in the wavelength range of 200,600 nm. The absorption edge was found at 5.76 eV for undoped film, while it is observed at 4.87 and 4.70 eV for 20 and 25 wt% LiAsF6 doped films, respectively. The direct band gaps for these undoped and salt doped PVA films were found to be 5.40, 5.12, and 4.87 eV, respectively, whereas the indirect band gaps were determined as 4.75, 4.45, and 4.30 eV. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers [source] Ultraviolet-induced crosslinking of poly(vinyl alcohol) evaluated by principal component analysis of FTIR spectraPOLYMER INTERNATIONAL, Issue 10 2001R Miranda, Teresa M Abstract The crosslinking of poly(vinyl alcohol) (PVA) films under ultraviolet irradiation for between 1 and 4,h was studied in air at 25,°C in the presence of sodium benzoate by Fourier-transform infrared spectroscopy (FTIR) using the attenuated total reflectance technique (ATR). Principal component analysis (PCA) is a mathematical procedure that allows treatment of the entire infrared spectrum and is very appropriate for analysing the chemical modifications initiated by sodium benzoate which occur in PVA upon UV irradiation. By PCA it was possible to clarify the mechanism of crosslinking of PVA. From this FTIR,PCA study, it is suggested that a free radical arising from the photolysis of sensitizer would abstract a tertiary hydrogen atom from the polymer chain to yield a polymeric radical. This radical reacts with OH groups, leading to the formation of ether bonds between the polymeric chains and hence to crosslinking and insolubilization of the PVA. © 2001 Society of Chemical Industry [source] Neuro-fuzzy structural classification of proteins for improved protein secondary structure predictionPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 8 2003Joachim A. Hering Abstract Fourier transform infrared (FTIR) spectroscopy is a very flexible technique for characterization of protein secondary structure. Measurements can be carried out rapidly in a number of different environments based on only small quantities of proteins. For this technique to become more widely used for protein secondary structure characterization, however, further developments in methods to accurately quantify protein secondary structure are necessary. Here we propose a structural classification of proteins (SCOP) class specialized neural networks architecture combining an adaptive neuro-fuzzy inference system (ANFIS) with SCOP class specialized backpropagation neural networks for improved protein secondary structure prediction. Our study shows that proteins can be accurately classified into two main classes "all alpha proteins" and "all beta proteins" merely based on the amide I band maximum position of their FTIR spectra. ANFIS is employed to perform the classification task to demonstrate the potential of this architecture with moderately complex problems. Based on studies using a reference set of 17 proteins and an evaluation set of 4 proteins, improved predictions were achieved compared to a conventional neural network approach, where structure specialized neural networks are trained based on protein spectra of both "all alpha" and "all beta" proteins. The standard errors of prediction (SEPs) in % structure were improved by 4.05% for helix structure, by 5.91% for sheet structure, by 2.68% for turn structure, and by 2.15% for bend structure. For other structure, an increase of SEP by 2.43% was observed. Those results were confirmed by a "leave-one-out" run with the combined set of 21 FTIR spectra of proteins. [source] Ammonia chemical ionization tandem mass spectrometry in structural determination of alkaloids.RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2001Chemical ionization tandem mass spectrometry (CI-MS/MS) of alkaloids with ammonia reagent gas and collision-activated dissociation as well as EI-MS/MS were applied to the tetraponerine alkaloids in extracts from six pseudomyrmecine ants of the genus Tetraponera. The MS/MS techniques along with gas chromatography Fourier transform infrared (GC/FTIR) spectra allowed identification in two extracts of seven of the eight known tetraponerines. The EI-MS/MS fragmentations proved diagnostic for the ring system and the CI-MS/MS patterns for the C-8 or C-9 substitution, while the Bohlmann bands in FTIR spectra were diagnostic for the C-8 or C-9 configurations. An Indian ant (T. allaborans) had T,2, T,4 and T,8, while a Chinese ant (T. binghami) had T,5, T,6, T,7 and T,8. Four other ants, T. rufonigra (India), T. penzigi (Africa), T. clypeata (Africa) and T. sp. cf. emeryi (Africa), had no tetraponerines. Copyright © 2001 John Wiley & Sons, Ltd. [source] EFFECTS OF DIFFERENT SAMPLE PREPARATION METHODS ON STABLE CARBON AND OXYGEN ISOTOPE VALUES OF BONE APATITE: A COMPARISON OF TWO TREATMENT PROTOCOLS*ARCHAEOMETRY, Issue 1 2010C. J. YODER Researchers have long debated the appropriateness of stable isotope analysis of bone apatite to reconstruct the diets of ancient animals. The debate has centred, in part, on diagenesis of bone mineral from interaction with the burial environment. A number of acetic acid treatments are used to remove diagenetic carbonates from samples; however, less is known on how different protocols alter stable isotope values. We compare two common acetic acid solution treatments (0.1 M versus 1.0 M-buffered) to examine the effects on carbon and oxygen isotope values and Fourier transform infrared spectroscopy (FTIR) spectra in human bone from different burial contexts. Results indicate that both treatments have a similar effect on isotope values and FTIR spectra in bone apatite. [source] Interpretation of the Thermogravimetric Curves of Ancient Pozzolanic ConcretesARCHAEOMETRY, Issue 4 2001F. Branda Pozzolanic concretes submitted to thermogravimetric (TG) analysis show a continuous weight loss starting from about 400 °C. In order to reconcile these observations with those from other analytical methods, it is necessary to attribute this weight loss to CO2 removal. It has been proposed, in the literature, that silicates and CaCO3 react at lower temperatures, producing calcium silicates and CO2. In this paper, the FTIR spectra collected on samples submitted to TG analysis, stopped at conveniently selected temperatures, provide direct evidence that the continuous weight loss recorded with thermogravimetric analysis of the pozzolanic concrete in the temperature range 400,900 °C is to be attributed to the reaction between the silicates and calcite, with the formation of CO2 and of a silicate that is richer in CaO. Therefore it is justifiable that the whole weight loss, in the temperature range 400,900 °C, should be taken into account in the calculation of the CaCO3 content of the concrete. Moreover, the described procedure,of recovering small samples (2 mg) from the sample-holder of the TG apparatus at various steps of the heating rate and comparing the FTIR spectra,can help in identifying the pozzolanic nature of a concrete that, in general, is not easily recognizable from the trend of the thermoanalytical curve. [source] Adsorption properties of microwave synthesized inorgano,organo montmorilloniteASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2010Miray Emreol Abstract The aim of this study is to determine the adsorption properties of microwave synthesized inorgano,organo montmorillonites. Microwave irradiation is preferred because of its low time and energy consumption properties, forming an advantage in industrial applications. In addition to the intercalation of Keggin and hexadecyltrimethylammonium (HDTMA+) cations, the aging process of pillaring solution was also carried out through the microwave irradiation. Both inorgano clays, namely the parents, and their inorgano,organo derivatives, were prepared by using the same amounts of aluminum by keeping the OH,/Al3+ and Al3+/clay ratios constant. The HDTMA+/clay ratio was changed in inorgano-organo clays (IOCs) during the preparation. The effects of these parameters on the surface properties and adsorption behaviors of the samples were investigated by conducting X-ray diffraction (XRD), Fourier transform infrared (FTIR) and simultaneous thermal analyses (STA), as well as batch adsorption experiments, in which phenol was used as a model pollutant. The results of XRD analyses reveal that the intercalation is successfully achieved. The existence of the Keggin and HDTMA+ cations was observed in FTIR spectra of the samples. Through the STA, it was determined that the existence of organic layer increases the dehydroxylation temperature and the thermal behavior of inorgano-organo montmorillonites strongly depends on the structure of the parent clay. An increase in the adsorption efficiencies with increasing HDTMA+/clay ratio was observed, except with the highest ratio. The behavior of this sample was explained by the formation of the second HDTMA+ layer leading to the hydrophilic surface formation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Theoretical and Experimental Study of the Adsorption of Neutral Glycine on Silica from the Gas PhaseCHEMPHYSCHEM, Issue 6 2005C. Lomenech Dr. Abstract The adsorption of neutral glycine onto amorphous silica was investigated both theoretically and experimentally. DFT calculations were performed at the BLYP-631++G** level using a cluster approach. Several possible configurations involving the formation of H bonds between glycine and one, two, or three silanol groups (SiOH) were considered. The most favorable bonding of glycine with one silanol group (45 kJ,mol,1) occurs through the COOH moiety, thus forming a cycle in which the CO group is an H-bond acceptor whereas the acidic OH group is an H-bond donor. With two or three silanol groups, additional H bonds are formed between the amine moiety and the silanol groups, which leads to an increased adsorption energy (70 and 80 kJ,mol,1for two and three silanol groups, respectively). Calculated ,CO, ,HNH, and ,HCHvalues are sensitive to the adsorption mode. A bathochromic shift of ,COas compared to the ,COof free glycine (calculated in the 1755,1790 cm,1range) is found for glycine in interaction with silanol(s). The more H bonds are formed between the COOH moiety and silanol groups, the higher the bathochromic shift. For ,HNH, no shift is found for glycine adsorbed on one and two silanol groups (where the amine is either not bound or an H-bond donor), whereas a bathochromic shift is calculated with three silanols when the amine moiety is an H-bond acceptor. Experimental FTIR spectra performed at room temperature for glycine adsorbed at 160,°C on Aerosil amorphous silica exhibit bands at 1371, 1423, 1630, and 1699 cm,1. The experimental/calculated frequencies have their best correspondence for glycine adsorbed on two silanol groups. It is important to note that the forms giving the best correspondence to experimental frequencies are the most stable ones. [source] Assembly synthesis of sheet-like calcite array and stable-vaterite by supported liquid membraneCHINESE JOURNAL OF CHEMISTRY, Issue 10 2004Dong-Mei Sun Abstract Sheet-like calcite array and stable vaterite were synthesized by bio-mimetic supported liquid membrane system under different reaction conditions. Both of the FTIR spectra of products showed narrower peak at 1418 cm,1 than that of bulk CaCO3, and that of vaterite has a split in this peak. [source] | |||||||||||||||||||