Fourier Transform Infrared Spectra (fourier + transform_infrared_spectrum)

Distribution by Scientific Domains

Selected Abstracts

Preparation of bimodal porous copolymer containing ,-cyclodextrin and its inclusion adsorption behavior

Zhao-Yang Sun
Abstract A novel insoluble bimodal porous polymer containing ,-cyclodextrin (,-CD) was prepared to adsorb aromatic amine compound. The process involved copolymerization of styrene and methyl methacrylate with a maleic acid derivative of ,-CD, subsequently, above formed copolymer was foamed by supercritical CO2. The chemical properties and physical structure of obtained copolymer was analyzed using Fourier transform infrared spectra, Thermal gravimetric analysis, X-ray diffraction, scanning electron microscope, and N2 adsorption techniques. The inclusion adsorption of aromatic amine compounds on ,-CD copolymer was carried out in a batch system. The quantities of aromatic amine compounds adsorbed on ,-CD copolymer reached equilibrium within 60 min. The adsorption kinetic could be fitted to a pseudo-second-order kinetic equation, and the linear correlation coefficients varied from 0.9828 to 0.9935. With the influence of molecular structure and hydrophobicity of the aromatic amine compound, the sequence of quantity of aromatic amine compounds adsorbed on ,-CD copolymer is p -toluidine > aniline > benzidine > o -toluidine. The adsorption equilibrium data of aromatic amine compound adsorbed on ,-CD copolymer were fitted to Freundlich and Langmuir models, respectively. The linear correlation coefficients of Langmuir model varied from 0.9516 to 0.9940, and the linear correlation coefficients of Freundlich varied from 0.9752 to 0.9976. It is concluded that Freundlich model fits better than Langmuir model, because the adsorption of aromatic amine compound on ,-CD copolymer is a chemical process. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Evaluation of the potential of polymeric carriers based on chitosan- grafted -polyacrylonitrile in the formulation of drug delivery systems

A. A. Sarhan
Abstract Graft copolymerization of chitosan with acrylonitrile (AN) was carried out by free radical polymerization using KMnO4 and oxalic acid as a combined redox initiator system. Graft copolymerization was confirmed by Fourier transform infrared spectra (FTIR), proton nuclear magnetic resonance spectra (1H-NMR), thermal gravimetric analysis (TGA) measurements, and wide angle X-ray diffraction (WAXD). In addition, further modification of the cyano groups of the grafted copolymers was performed by partial hydrolysis into carboxylic function groups with various extents. The extent of hydrolysis was monitored using FTIR spectroscopy. The potential of the hydrolyzed and unhydrolyzed grafted copolymers as polymeric carriers for drug delivery systems was extensively studied by preparation of tablets incorporated with methyl orange (MO) as a drug model. In vitro drug release was carried out in simulated gastric and intestinal conditions. The effects of grafting percentage (GP) and the extent of hydrolysis on the release kinetics were evaluated. Release continued up to 24 h for both hydrolyzed and unhydrolysed chitosan- g -PAN copolymers. The nature of drug transport through the polymer matrices was studied by comparing with power law or Kormeyer-Peppas equation. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Preparation of novel polyindene/polyoxymethylene blends and investigation of their properties

Tenzile Zilhan Cabuk
Abstract In this study, the conducting homopolymer of indene was synthesized by a chemical polymerization method in a nonaqueous medium, and polyindene (PIn)/polyoxymethylene (POM) blends were prepared. The physical, chemical, thermal, and spectral properties of the synthesized homopolymer and their blends were investigated. The conductivities of PIn and the PIn/POM blends were measured with a four-probe technique. The conductivity of PIn was determined as 1.16 10,5 S/cm, whereas the conductivities of the PIn/POM blends were determined to be in the range 3.16 10,6 to 9.8 10,6 S/cm. From Gouy scale magnetic susceptibility measurements, we found that PIn and the PIn/POM blends had polaron natures. The amount of Fe (milligrams per gram) in the PIn and PIn/POM structures were determined by inductively coupled plasma,optic emission spectrometry. Fourier transform infrared spectra were taken to analyze the structural properties of PIn and the PIn/POM blends. The thermal properties of PIn and PIn/POM blends were investigated with thermogravimetric analysis and differential scanning calorimetry analyses, and we found that they showed adequate thermal stability. According to the initial decomposition temperature among the blends, the blend including 16% PIn had the highest decomposition temperature with 244C. The morphological structures of the PIn, POM, and blends were clarified with scanning electron microscopy. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Investigation of the electropolymerization of o -toluidine and p -phenylenediamine and their electrocopolymerization by in situ ultraviolet,visible spectroelectrochemistry

Guirong Zhang
Abstract Under the conditions of potentiostatic electrolysis, the electropolymerization of o -toluidine (OT) and para -phenylenediamine (PPDA) and the electrocopolymerization between OT and PPDA on an indium tin oxide (ITO) conductive glass electrode at potentials of 0.7, 0.8, and 0.9 V were studied in detail by in situ ultraviolet,visible (UV,vis) spectrometry in 0.5 mol/L sulfuric acid media. It was shown that both OT and PPDA could be electropolymerized on the ITO electrode, which depended on the applied electrolysis potential and the concentration of the monomer. Furthermore, in situ UV,vis spectra indicated that the electrocopolymerization between OT and PPDA could happen. The presence of PPDA not only promoted polymerization but also accelerated polymerization, which was attributed to the formation of an intermediate result from the coupling of PPDA and the toluidine monomer cation radical. PPDA could be incorporated into the copolymer to make the copolymer have a phenazine or phenazine-like cyclic structure, which was proven by the reflectance Fourier transform infrared spectra of the polymer and copolymer. The scanning electron microscopy morphology images of the polymers obtained showed that, in addition to accelerating polymerization, PPDA also could change the method of nucleation for the polymer to make the copolymer possess a fibrous surface morphology. The diameter of the fibroid copolymer was about 100 nm, and the length of that reached about 1000 nm. In the article, a newer concerned mechanism of copolymerization was proposed. 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Pervaporation characteristics and structure of poly(vinyl alcohol)/poly(ethylene glycol)/tetraethoxysilane hybrid membranes

Li Yi Ye
Abstract Poly(vinyl alcohol) (PVA) blended with poly(ethylene glycol) (PEG) was crosslinked with tetraethoxysilane (TEOS) to prepare organic,inorganic PVA/PEG/TEOS hybrid membranes. The membranes were then used for the dehydration of ethanol by pervaporation (PV). The physicochemical structure of the hybrid membranes was studied with Fourier transform infrared spectra (FT-IR), wide-angle X-ray diffraction WXRD, and scanning electron microscopy (SEM). PVA and PEG were crosslinked with TEOS, and the crosslinking density increased with increases in the TEOS content, annealing temperature, and time. The water permselectivity of the hybrid membranes increased with increasing annealing temperature or time; however, the permeation fluxes decreased at the same time. SEM pictures showed that phase separation took place in the hybrid membranes when the TEOS content was greater than 15 wt %. The water permselectivity increased with the addition of TEOS and reached the maximum at 10 wt % TEOS. The water permselectivity decreased, whereas the permeation flux increased, with an increase in the feed water content or feed temperature. The hybrid membrane that was annealed at 130C for 12 h exhibited high permselectivity with a separation factor of 300 and a permeation flux of 0.046 kg m,2 h,1 in PV of 15 wt % water in ethanol. 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

Preparation and characterization of novel biphasic calcium phosphate powders (,-TCP/HA) derived from carbonated amorphous calcium phosphates

Yanbao Li
Abstract Novel biphasic calcium phosphate (BCP) powders composed of ,-tricalcium phosphate (,-TCP) and hydroxyapatite (HA) were prepared by thermal decomposition of carbonated amorphous calcium phosphates (CACP). At first, the CACP precipitates were synthesized by adding ammonium carbonate in the presence of poly(ethylene glycol) at pH 10 with an initial Ca/P molar ratio of 1.60 at 5C. The Ca/P molar ratios of the CACP precursors are between 1.50 and 1.67 investigated by ICP. Then BCP (,-TCP/HA) powders were obtained after heating the CACP precursors at relatively low temperature (800C) for 3 h. ,-TCP/HA powders were characterized by X-ray diffractometry, Fourier transform infrared spectra, transmission electron microscopy/scanning electron microscopy, and sedimentation experiment. The results show that ,-TCP and HA phases form in one powder, ,-TCP/HA powders are sphere with the diameter of 300 nm to less than 100 nm varied with their chemical compositions and the ratio of ,-TCP and HA in the powders can be adjusted by the adding amount of carbonates. The possible formation process of biphasic ,-TCP/HA powders was proposed. 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source]

Ionic liquids in the selective recovery of fat from composite foodstuffs

Huma Lateef
Abstract BACKGROUND: Ionic liquids (ILs) are able to dissolve a wide range of organic and inorganic molecules and have potential application in the separation and recovery of valuable components from wastes. The potential for ILs to separate sugar and fat from food waste is demonstrated using chocolate as a model system. RESULTS: The ILs 1-(2-cyanoethyl)-3-methylimidazolium bromide (cyanoMIMBr), 1-propyl-3-methylimidazolium bromide (propylMIMBr), 1-hexylpyridinium bromide (hexylPyrBr) and 1-butyl-3-methylimidazolium chloride (butylMIMCl) were synthesised by microwave technology and fully characterised by mass spectrometry, thermogravimetric differential scanning calorimetery, thin layer chromatography, nuclear magnetic resonance and Fourier transform infrared spectroscopy. The solubilities of the fat and carbohydrate components in the ILs are reported for the two main ingredients in chocolate. CyanoMIMBr and propylMIMBr selectively solubilise sugar leaving the fat insoluble. Both cyanoMIMBr and propylMIMBr have been used to successfully separate sugars and cocoa butter fat from white, milk and dark chocolate and the Fourier transform infrared spectra and thermogravimetric differential scanning calorimeter profiles of the extracted fat samples are in good agreement with reference material data. CONCLUSIONS: The ILs cyanoMIMBr and propylMIMBr are successful in the separation and recovery of fat from white, milk and dark chocolate, as confirmed by FTIR and TG-DSC data. Copyright 2009 Society of Chemical Industry [source]

Anionic grafting polymerization of propylene sulfide onto human hair in water

Hisatoyo Morinaga
Abstract Natural human hair was modified by the graft polymerization of propylene sulfide in an aqueous medium. The amount of the polymer grafted onto the reduced hair was 0.15,0.19 g on 1.0 g of hair. The grafted polymer was isolated by the hydrolysis of the hair in the polymer-grafted hair under basic conditions and was confirmed to be poly(propylene sulfide) by 1H NMR, 13C NMR, and Fourier transform infrared spectra. The number-average molecular weights of the isolated polymers from the grafted products were 10,000,12,000. 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3778,3786, 2006 [source]

Synthesis and characterization of carbon nanotube/polypyrrole core,shell nanocomposites via in situ inverse microemulsion

Yijun Yu
Abstract We demonstrate here a feasible approach to the preparation of multiwalled carbon nanotube (MWNT)/polypyrrole (PPy) core,shell nanowires by in situ inverse microemulsion. Transmission electron microscopy and scanning electron microscopy showed that the carbon nanotubes were uniformly coated with a PPy layer with a thickness of several to several tens of nanometers, depending on the MWNT content. Fourier transform infrared spectra suggested that there was strong interaction between the ,-bonded surface of the carbon nanotubes and the conjugated structure of the PPy shell layer. The thermal stability and electrical conductivity of the MWNT/PPy composites were examined with thermogravimetric analysis and a conventional four-probe method. In comparison with pure PPy, the decomposition temperature of the MWNT/PPy (1 wt % MWNT) composites increased from 305 to 335 C, and the electrical conductivity of the MWNT/PPy (1 wt % MWNT) composites increased by 1 order of magnitude. The current,voltage curves of the MWNT/PPy nanocomposites followed Ohm's law, reflecting the metallic character of the MWNT/PPy nanocomposites. The cyclic voltammetry measurements revealed that PPy/MWNT composites showed an enhancement in the specific charge capacity with respect to that of pure PPy. 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6105,6115, 2005 [source]

Synthesis of poly[(2-oxo-1,3-dioxolane-4-yl) methyl methacrylate- co -ethyl acrylate] by incorporation of carbon dioxide into epoxide polymer and the miscibility behavior of its blends with poly(methyl methacrylate) or poly(vinyl chloride)

Sung-Young Park
Abstract This study was related to the investigation of the chemical fixation of carbon dioxide to a copolymer bearing epoxide and the application of the cyclic carbonate group containing copolymer-to-polymer blends. In the synthesis of poly[(2-oxo-1,3-dioxolane-4-yl) methyl methacrylate- co -ethyl acrylate] [poly(DOMA- co -EA)] from poly(glycidyl methacrylate- co -ethyl acrylate) [poly(GMA- co -EA)] and CO2, quaternary ammonium salts showed good catalytic activity. The films of poly(DOMA- co -EA) with poly(methyl methacrylate) (PMMA) or poly(vinyl chloride) (PVC) blends were cast from N,N,-dimethylformamide solution. The miscibility of the blends of poly(DOMA- co -EA) with PMMA or PVC have been investigated both by DSC and visual inspection of the blends. The optical clarity test and DSC analysis showed that poly(DOMA- co -EA) containing blends were miscible over the whole composition range. The miscibility behaviors were discussed in terms of Fourier transform infrared spectra and interaction parameters based on the binary interaction model. 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1472,1480, 2001 [source]

Fourier transform Raman and Fourier transform infrared spectra of cross-linked polyurethaneurea films synthesized from solutions

Valentina 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]

Preparation, morphology, and adhesive and mechanical properties of ultrahigh-molecular-weight polyethylene/SiO2 nanocomposite fibers

Yi Zhang
A simple treatment approach has been performed to achieve enhanced surface properties of ultrahigh-molecular-weight polyethylene (UHMWPE) fibers by incorporation of nano-silicon dioxide (SiO2) in the presence of silane coupling agent during gel-spinning process. The SiO2 -treated UHMWPE (UHMWPE/SiO2) nanocomposite fibers with different nano-SiO2 compositions were characterized with Fourier transform infrared spectra, scanning electron microscopy, and wide-angle X-ray diffraction, and their interfacial adhesion and mechanical properties were also investigated. The nano-SiO2 can be trapped on the surface of the fibers to form rough surface for UHMWPE/SiO2 fibers, and diffused into the inner of fibers to induce the lower crystal sizes and higher crystallinity of polyethylene in UHMWPE/SiO2 fibers. The resulting UHMWPE/SiO2 fibers therefore exhibit a dramatic enhancement in the adhesive properties because of the combination of rougher surface compared with those of UHMWPE fiber and polar groups absorbed on the surface of fibers. The mechanical properties of UHMWPE/SiO2 nanocomposite fibers are enhanced simultaneously because of the influence of nano-SiO2 on the structure of UHMWPE crystalline regions and fibrils. POLYM. COMPOS., 2010. 2009 Society of Plastics Engineers [source]

Maleated polypropylene film and wood fiber handsheet laminates,

Sangyeob Lee
The grafting effect of maleic anhydride (MA) as an interfacial bonding agent and its influence on the tensile strength properties of thermomechanical pulp handsheet-isotactic polypropylene (iPP) film laminates was studied. For the MA treated with benzoyl peroxide (BPO) as an initiator, tensile strength properties increased 76% with PP film over untreated laminates. The optimal strength properties were obtained with a MA and BPO ratio of 2:1. A strong correlation was observed between the number of fibers in the web and tensile strength properties for both handsheet drying conditions. The R2 values were 0.95 for air-dry conditions and 0.94 from oven-dry conditions. Scanning electron microscopy images also showed the effectiveness of MA loading on the surface of thermomechanical pulp fibers due to increased fiber failure, which occurred without fiber being pulled out from the PP matrixes. Crystallinity and heat flow were determined using differential scanning calorimetry (DSC) and increased as expected as the ratio of MA and BPO increased from 0:0 to 2:1. These results were also in accordance with the morphological observations at the fracture surface, Fourier transform infrared spectra, and thermal analysis. POLYM. COMPOS., 2009. 2008 Society of Plastics Engineers [source]

Exploration of the morphological transition phenomenon of polyaniline from microspheres to nanotubes in acid-free aqueous 1-propanol solution in a single polymerization process

Yu-Fong Huang
Abstract Polyaniline micro- or nanostructures have been widely investigated due to their unique physical and chemical properties. Although several studies have reported the synthesis of polyaniline microspheres and nanotubes, their mechanisms of formation remain controversial. This study reports our observation of the morphological transition of polyaniline from microspheres to nanotubes in a single polymerization process and also tries to propose their mechanisms of formation. The polymerization of aniline monomer in acid-free aqueous 1-propanol solutions (1 and 2 mol L,1) produces polyaniline microspheres and nanotubes at different reaction stages through a morphology transition process with treatment using ultrasound. In the initial reaction stage, Fourier transform infrared spectra indicate that the aniline monomers form phenazine-like units, producing polyaniline microspheres with an outside diameter of 1,2 m. The hydrogen bonds between 1-propanol and polyaniline serve as the driving force for the polyaniline chains to build microspheres. As the reaction continues, observation indicates the microspheres decompose and reform one-dimensional nanotubes. In this stage, a structure consisting of a head of phenazine-like units and a tail of acid-doping para -linked aniline units develops. The protonation of the para -linked aniline units provides the driving force for the formation of nanotubes through a self-curling process. We report here the unique morphology transition of polyaniline from microspheres to nanotubes in a single polymerization process. The results indicate that the structural change of polyaniline leads to this morphological change. The mechanisms of formation of the microspheres and nanotubes in a polymerization process are also well explained. Copyright 2010 Society of Chemical Industry [source]

Improved compatibility of EVOH/LDPE blends by ,-ray irradiation

Haihong Li
Abstract The change of compatibility of poly(ethylene- co -vinyl alcohol) (EVOH)/LDPE blends induced by,-ray radiation was studied. Gel extraction experiment results show that the gel fraction of blends increases linearly with the content of LDPE and reaches a maximum at 100 kGy, because neat EVOH is difficult to cross-link by irradiation. A comparison of theoretical and experimental gel contents indicates that some EVOH molecular chains enter the LDPE gel network. The peak at 3363 cm,1 on the Fourier transform infrared spectrum of pure blend gel is assigned to typical stretching of an OH bond, which indicates that a "graft" reaction occurs in the interface between EVOH and LDPE phases during the irradiation process. Mechanical property measurement results support such a structural change. The tensile strength of cross-linked blends increases with absorbed dose first, reaches a maximum value at 150 kGy, and then decreases with dose. A similar trend can also be observed in bending tests. 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:192,198, 2009; Published online in Wiley InterScience ( DOI 10.1002/adv.20160 [source]

A study of the novel intumescent flame-retarded PP/EPDM copolymer blends

Shun Zhou
Abstract Flammability of polypropylene/ethylene,propylene-diene copolymer (PP/EPDM) filled with melamine phosphate (MP) and pentaerythritol phosphate (PEPA) was studied by limiting oxygen index (LOI), UL 94, and cone calorimetry. The thermal degradation of the composites was investigated using thermogravimetric analysis (TG) and real-time Fourier transform infrared spectrum (RT-FTIR), and the mechanical properties of the materials were also studied. It had been found that the PP/EPDM/PEPA/MP composites (PEPM series) showed better flame retardancy than that of the PP/EPDM composites containing MP or PEPA. TG and RT-FTIR studies indicated that the interaction occurs among MP, PEPA, and PP/EPDM. The incorporation of the flame retardants deteriorated the mechanical properties of the materials. 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Synthesis of new superhydrophobic nanosilica and investigation of their performance in reinforcement of polysiloxane

XianLi Fang
We reported a new facile method to synthesize superhydrophobic nanosilica using glycidoxypropyltrimethoxysilane and dodecylamine as treatment agents. Also, we systemically investigate their performance in reinforcement of poly(dimethylsiloxane) (PDMS) rubber. Fourier transform infrared spectrum, contact angle (CA) and thermogravimetric analysis (TGA) measurements were used to characterize the modified nanosilica. Results show that the inherent hydrophilicity of parent nanosilica surface can be greatly altered through this modification method. The CA of as-prepared superhydrophobic nanosilica can reach 160.2. The properties of as-prepared modified nanosilica-filled PDMS composites were systemically investigated by dynamic rheological test, scanning electron microscopy, TGA, dynamic mechanical analysis. These as-prepared superhydrophobic nanosilica exhibit uniform dispersion in the PDMS matrix, and their composites also show good mechanical properties and distinct advantage on thermal stability compared with those of the pure silica-filled PDMS composites. Also described is the probable mechanism for the reinforcement of as-prepared superhydrophobic nanosilica-filled PDMS. POLYM. COMPOS., 31:1628,1636, 2010. 2009 Society of Plastics Engineers [source]