Fourier Transform Infrared Spectrometry (fourier + transform_infrared_spectrometry)

Distribution by Scientific Domains

Selected Abstracts

Synthesis and characterization of polyurethane/polybenzoxazine-based interpenetrating polymer networks (IPNs)

Yanjun Cui
Abstract Sequential interpenetrating polymer networks (IPNs), based on polyurethane and polybenzoxazine, were synthesized. Fourier Transform infrared spectrometry was employed to monitor the formation kinetics, which indicated that only physical bonding existed in the resulting IPNs. Morphological investigations revealed a lightly phase separation behaviour in all of the IPNs studied. 2003 Society of Chemical Industry [source]

In situ generated hydroxyl-terminated polybutadiene nanoparticles in polyimide films

Anand Kumar Gupta
Abstract Polyimide (PI) has been extensively investigated as matrices for blends in the search for novel materials for microelectronics and engineering application. The processing of the PI with hydroxyl-terminated polybutadiene (HTPB) offers a considerable advantage to develop a material having good mechanical and thermal stability. Taking this into account, the HTPB was blended with polyamic acid, which is precursor to PI to form PI + HTPB films. A number of properties were evaluated for PI + HTPB films with ultra low concentrations of HTPB. The films prepared with ultra low concentration (10,3,1 wt%) showed unusual synergism, which is attributed to the presence of in situ generated micro/nanostructures derived from HTPB. The microhardness study was used to elucidate the actual mechanical performance due to structure formation of HTPB in a nanometer regime within PI matrix. Atomic force microscopy analysis confirmed the dispersion of HTPB at nano regime within PI matrix. The enhanced thermal stability as determined by thermogravimetric analyzer and Fourier transform infrared spectrometry was attributed to the presence of micro/nanoparticle of HTPB within the PI matrix. The water absorption isotherms were measured and their abnormal behavior was correlated with micro-/nano-sized particles in the PI/HTPB film. 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:48,59, 2009; Published online in Wiley InterScience ( DOI 10.1002/adv.20144 [source]

Ceric ammonium sulfate/sodium disulfite initiated grafting of acrylamide on to Cassia reticulata seed gum

Vandana Singh
Abstract Ceric ammonium sulfate/sodium disulfite redox system was evaluated for the poly(acrylamide) (PAM) grafting on to Cassia reticulata (CR) seed gum. Grafting conditions were optimized and the maximum %Grafting (%G) and %Efficiency (%E) achieved were 152 and 97.2%, respectively, using [disulfite] 0.005M; [ceric ammonium sulfate] 0.026M; [acrylamide] 0.11M; [gum] 0.125 g/25mL at 40 0.2C. Representative CR-grafted gum (CRPAM) was characterized by Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Under identical conditions, the redox initiator could result 142.6 %G and 91.2 %E on to guar gum (GG). Various physical properties of the CR gum/grafted CR gum, such as viscosity, water retention, and saline retention, were studied and compared with GG/grafted GG to find out the potential industrial use of CR gum and PAM- grafted -CR gum. 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Characterization and use of acid-activated montmorillonite-illite type of clay for lead(II) removal

AICHE JOURNAL, Issue 9 2010
John U. Kennedy Oubagaranadin
Abstract The natural local deposits of montmorillonite-illite type of clay (MIC) were susceptible for acid activation. Raw clay was taken for experimentation, disintegrated on acid activation with sulfuric acid, which showed a particle size distribution. The montmorillonite and illite phases in the raw clay disappeared on acid activation and the activated clay, MIC(AA), showed with sodium-aluminum-silicate and beidellite phases apart from quartz (low) phase. The raw and acid-activated clays were characterized using X-ray powder diffractometry, X-ray fluorescence, Fourier transform infrared spectrometry, and energy dispersive X-ray, and their adsorption capacities were compared. When tested for adsorption of Pb(II) in aqueous solutions, the acid-activated clay showed about 50% increased adsorption than raw clay. Sips adsorption isotherm and pseudo-second-order kinetic models were found to be best for the batch adsorption data. Kinetic studies showed the existence of film diffusion and intraparticle diffusion. A two-stage batch adsorber was designed for the removal of Pb(II) from aqueous solutions. 2010 American Institute of Chemical Engineers AIChE J, 2010 [source]

Cefuroxime axetil solid dispersions prepared using solution enhanced dispersion by supercritical fluids

Seoung Wook Jun
Cefuroxime axetil (CA) solid dispersions with HPMC 2910/PVP K-30 were prepared using solution enhanced dispersion by supercritical fluids (SEDS) in an effort to increase the dissolution rate of poorly water-soluble drugs. Their physicochemical properties in solid state were characterized by differential scanning calorimeter (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared spectrometry (FT-IR) and scanning electron microscopy. No endothermic and characteristic diffraction peaks corresponding to CA were observed for the solid dispersions in DSC and PXRD. FTIR analysis demonstrated the presence of intermolecular hydrogen bonds between CA and HPMC 2910/PVP K-30 in solid dispersions, resulting in the formation of amorphous or non-crystalline CA. Dissolution studies indicated that the dissolution rates were remarkably increased in solid dispersions compared with those in the physical mixture and drug alone. In conclusion, an amorphous or non-crystalline CA solid dispersion prepared using SEDS could be very useful for the formulation of solid dosage forms. [source]

The Role of Oxidation in the Migration Mechanism of Layered Silicate in Poly(propylene) Nanocomposites

Mauro Zammarano
Abstract Summary: Evidence of clay migration from the core to the surface of poly(propylene)/montmorillonite nanocomposites is provided. A three- to fivefold increase in the clay concentration of the surface is obtained during isothermal heating in oxidative atmosphere. The mechanism of migration is investigated by means of attenuated total reflectance Fourier transform infrared spectrometry. It is shown that oxygen plays a fundamental role in the migration mechanism. ,Si versus c for the annealed samples. [source]

The effect of nitrogen incorporation on surface properties of silicon oxynitride films

Jongin Hong
Abstract In order to investigate the surface heterogeneity of silicon oxynitride films, we observed the nanoscale variation of the surface potential by Kelvin probe force microscopy (KFM), the molecular bonding characteristics by Fourier transform infrared spectrometry (FTIR), and the wetting behavior by contact angle measurement. Nitrogen incorporation into silicon oxynitride films influenced the decrease in the surface potential and the polar component of the surface free energy. We present the first correlation between the nanoscale measurement of the surface potential and the macroscopic measurement of the surface free energy in silicon oxynitride films grown by a standard plasma-enhanced chemical vapor deposition (PECVD) technique. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Interfacial interactions and performance of polyamide 6/modified attapulgite clay nanocomposites

Bingli Pan
Attapulgite (AT) clay was firstly treated with sodium polyacrylate (PAS), then polyamide 6 (PA6)/AT nanocomposites were prepared by simple melt compounding. Transmission electron microscope (TEM) and Fourier transform infrared spectrometry (FT-IR) of treated AT confirm the success of purifying and surface modification of the original AT by PAS. X-ray diffraction spectra for the nanocomposites show that the microstructure of AT in PA6 matrix is almost unchanged. It indicates that a strong interfacial adhesion exists between AT and PA6 matrix through analyzing fracture surfaces of the nanocomposites, the variation of glass transition temperature (Tg) obtained by dynamic mechanical analysis, and interfacial interaction factors; field emission scanning electron microscopy on the fracture surfaces of the nanocomposites shows that a uniform dispersion of AT is obtained. The above two aspects conform to the improvement of mechanical and thermal properties of the nanocomposites. POLYM. COMPOS., 2009. 2008 Society of Plastics Engineers [source]

Synthesis and thermal properties of ester-type crosslinked epoxy resins derived from lignosulfonate and glycerol

Tuan Noor Maznee Tuan Ismail
Abstract Among various biomass-based components, both lignin and glycerol are important, since they are abundantly produced as by-products in industrial processes. Accordingly, in the present study, new types of crosslinked epoxy resins were synthesized from lignin and glycerol. Polymers derived from two types of lignin-based crosslinked epoxy resins were prepared through two-step reactions, ester-carboxylic acid derivative preparation followed by crosslinked epoxy resin preparation, in order to establish a crosslinked epoxy resin system in which glycerol units were included. The resins obtained were labeled as follows: series 1, lignosulfonate-glycerol polyacid (Ser1LSGLYPA); and series 2, glycerol diglycidyl ether (Ser2GLYDGE). The functional groups of the resins were analyzed using Fourier transform infrared spectrometry. The thermal properties of the resins were analyzed using differential scanning calorimetry and thermogravimetry. The glass transition temperature of the crosslinked epoxy resins increased with increasing LSGLYPA and GLYDGE contents for Ser1LSGLYPA and Ser2GLYDGE, respectively. The thermal degradation temperature for Ser1LSGLYPA and Ser2GLYDGE did not show significant change, suggesting that the crosslinked epoxy resins were thermally stable. The mass residue at 500 C was not affected by the changes of LSGLYPA and GLYDGE contents. Copyright 2009 Society of Chemical Industry [source]

Interfacial polymerization of morphologically modified polyaniline: from hollow microspheres to nanowires

Jinbo Li
Abstract BACKGROUND: Polyaniline (PANI) has attracted much attention in many fields due to its chemical and physical properties, and different nanostructures of PANI changing from one-dimensional to three-dimensional have been obtained. By changing the concentration of cetyltrimethylammonium bromide (CTAB), the morphology of hydrochloric acid-doped polyaniline could be changed from one-dimensional nanoneedles or nanowires with a network structure (50,100 nm in diameter) to three-dimensional hollow microspheres (ca 400 nm in outer diameter) via combining interfacial polymerization and self-assembly process. RESULTS These different nanostructures of PANI were proved using scanning electron and transmission electron microscopies. A plausible mechanism of the formation of the changeable nanostructures of PANI may be different from that of interfacial polymerization without surfactant or a traditional homogenous reaction system using CTAB as surfactant. CONCLUSION The results obtained from Fourier transform infrared spectrometry, X-ray diffraction and the four-probe method showed that the molecular structure of PANI does not change with increasing CTAB concentration, but crystallinity and conductivity of PANI increase with surfactant concentration. Copyright 2007 Society of Chemical Industry [source]

Effect of conjugated linoleic acid grafting on the hemocompatibility of polyacrylonitrile membrane

Fu-Chen Kung
Abstract Polyacrylonitrile (PAN) membrane was hydrolyzed with NaOH(aq) and grafted with conjugated linoleic acid (CLA) via esterification with 1,3-propanediol. The resulting CLA grafted PAN membranes were characterized using Fourier transform infrared spectrometry (FT-IR) and X-ray photoelectronic spectroscopy (XPS). The effects of CLA grafting on the blood coagulation, platelet aggregation, and oxidative stress were evaluated using human blood. The complete blood count (CBC) and coagulation time (CT) was evaluated in vitro for hemocompatibility. After CLA grafting, the proliferation of human umbilical vein endothelial cells (HUVECs) on the membranes were improved. In addition, the production of reactive oxygen species (ROS) was measured by the chemiluminescence (CL) method to evaluate the oxidative stress. The results showed that the CLA-grafted PAN membrane could keep the CBC values more stable than unmodified PAN membrane. The CLA-grafted PAN membranes also showed longer CT. CLA-grafted PAN membrane could keep the CL counts of hydrogen peroxide and superoxide values more stable than unmodified PAN membrane. These results suggest that a CLA-grafted PAN membrane could offer protection for patients against oxidative stress and would be helpful for reducing the dosage of anticoagulant during hemodialysis. Copyright 2006 John Wiley & Sons, Ltd. [source]

Fungal biodegradation of hard coal by a newly reported isolate, Neosartorya fischeri

Eric E. Igbinigie
Abstract Cynodon dactylon (Bermuda grass) has been observed to grow sporadically on the surface of coal dumps in the Witbank coal mining area of South Africa. Root zone investigation indicated that a number of fungal species may be actively involved in the biodegradation of hard coal, thus enabling the survival of the plant, through mutualistic interaction, in this extreme environment. In an extensive screening program of over two thousand samples, the Deuteromycete, Neosartorya fischeri, was isolated and identified. The biodegradation of coal by N. fischeri was tested in flask studies and in a perfusion fixed-bed bioreactor used to simulate the coal dump environment. The performance of N. fischeri was compared to Phanaerochaete chrysosporium and Trametes (Polyporus) versicolor, previously described in coal biodegradation studies. Fourier transform infrared spectrometry and pyrolysis gas chromatography mass spectrometry of the biodegradation product indicated oxidation of the coal surface and nitration of the condensed aromatic structures of the coal macromolecule as possible reaction mechanisms in N. fischeri coal biodegradation. This is a first report of N. fischeri -mediated coal biodegradation and, in addition to possible applications in coal biotechnology, the findings may enable development of sustainable technologies in coal mine rehabilitation. [source]

Morphology Investigation of Electrolessly Deposited Ag Film on Ag-Activated p-Type Silicon(111) Wafer

Hao Tong
Abstract A method of electroless silver deposition on silver activated p-type silicon(111) wafer was proposed. The silver seed layer was deposited firstly on the wafer in the solution of 0.005 mol/L AgNO3+0.06 mol/L HF. Then the silver film was electrolessly deposited on the seed layer in the electroless bath of AgNO3+NH3+acetic acid+NH2NH2 (pH 10.2). The morphology of the seed layer and the silver films prepared under the condition of the different bath composition was compared by atomic force microscopy. The reflectance of the silver films with different thickness was characterized by Fourier transform infrared spectrometry. The experimental results indicate that the seed layer possesses excellent catalytic activity toward electroless silver deposition and rotating of the silicon wafer during the electroless silver deposition could lead to formation of the smoother silver film. [source]