Laszlo Korecz - Academia.edu (original) (raw)
Papers by Laszlo Korecz
Abstract. We describe a simple way to produce large quantities of solid solutions of monomer CjgN... more Abstract. We describe a simple way to produce large quantities of solid solutions of monomer CjgN in pure QQ using an electric gas discharge tube. Typical concentrations are 10~5 to 10"4 CsgN with respect to Q0. The 14N and several 13C hyperfme constants were ...
Materials, 2018
In this study, relationships between preparation conditions, structure, and activity of Pt-contai... more In this study, relationships between preparation conditions, structure, and activity of Pt-containing TiO2 photocatalysts in photoinduced reforming of glycerol for H2 production were explored. Commercial Aerolyst® TiO2 (P25) and homemade TiO2 prepared by precipitation-aging method were used as semiconductors. Pt co-catalysts were prepared by incipient wetness impregnation from aqueous solution of Pt(NH3)4(NO3)2 and activated by calcination, high temperature hydrogen, or nitrogen treatments. The chemico-physical and structural properties were evaluated by XRD, 1H MAS NMR, ESR, XPS, TG-MS and TEM. The highest H2 evolution rate was observed over P25 based samples and the H2 treatment resulted in more active samples than the other co-catalyst formation methods. In all calcined samples, reduction of Pt occurred during the photocatalytic reaction. Platinum was more easily reducible in all of the P25 supported samples compared to those obtained from the more water-retentive homemade TiO2. ...
Studies in Surface Science and Catalysis, 2005
... One can raise the question, what is the Fe(III) spectrum deconvolution good for? First of all... more ... One can raise the question, what is the Fe(III) spectrum deconvolution good for? First of all toget a general picture how the spectrum is composed from the sub-spectra: how much Fe(llI) is sited in FW and EFW environments and what are the symmetries of these sites? ...
Journal of Molecular Structure: THEOCHEM, 1997
A theoretical study on the cyclization of electrophilic radicals was canied out. Transition state... more A theoretical study on the cyclization of electrophilic radicals was canied out. Transition state geometries were obtained by MNDO semiempirical calculations and the calculated properties (orbital energies, orbital coefficients, charge distributions and energy partition) were analysed. Observed regioselectivities can be rationalised on the basis of SOMO-HOMO and SOMO-LUMO orbital interactions. 0 1997 Elsevier Science B.V. TheR spectra for the reaction of lb miasmg from Ref. [2] were recorded in benzene in the presence of 2.6-dichloro-nitrosobenzene spin trap at three different temperatures (153, 58 and 65°C. respectively) and gave superimposed spectra. where two doublets of triplets appeared in each case. the intensity of which were changing in time. One of them having a nitrogen ( 12.8 G) and a large phosphorus coupling ( 18.5 G) can be assigned to the intermediate 4b. while the other triplet having a nitrogen ( 13.0 G) and a hydrogen splitting (7.2 G) may correspond to the six membered cyclic mtermediate (6b). Ol66-1280/97/$17.00 Copyright 0 1997 Elsevier Science B.V. All rights reserved P/I SO 166.1280(96)04870-l
Biochemical and Biophysical Research Communications, 1995
Production and the mechanism of the interactions of free radicals generated by stimulated macroph... more Production and the mechanism of the interactions of free radicals generated by stimulated macrophages in the presence of luminol and a free radical inhibitor was investigated to determine the possibility of using luminol-dependent chemiluminescence for studying photodynamic effects in biology. Earlier measurements have been revisited and additional experiments performed indicating that oxidation products of luminol neither inhibit the in vitro formation of radicals nor quench CL. Simulation based on the mechanism suggested revealed that the likely value for the rate constant of the primary step between luminol and superoxide anion radicals producing luminol radicals is 5؋10 2 -1؋10 3 M ؊1 s ؊1 . It has been established that the ratio of the concentration of radicals generated by the biological system to that formed by oxidation of luminol exceeds 10 3 ; that is, the contribution of the latter is negligible and the system is appropriate to measure quantitatively the effect of excited photosensitizers on free radicals.
Journal of the American Chemical Society, May 1, 2003
A series of isotropic EPR spectra recorded at various concentrations and pH (in the range 2-12) o... more A series of isotropic EPR spectra recorded at various concentrations and pH (in the range 2-12) on equilibrium systems containing copper(II) and diglycine, triglycine, or tetraglycine were analyzed. A purely mathematical method, matrix rank analysis gave the number of independent EPR-active species. Two-dimensional evaluation then resulted in the formation constants and magnetic parameters of 14 metal complexes (including microspecies) in each system. The independent paramagnetic species formed with each ligand are as follows: Cu(2+) (aqua complex), [CuLH](2+), [CuL](+), [CuLH(-1)], [CuLH(-2)](-), [CuL(2)H(2)](2+), [CuL(2)H](+), [CuL(2)], [CuL(2)H(-1)](-), and [CuL(2)H(-2)](2-). Moreover, for diglycine, the diamagnetic complex [Cu(2)L(2)H(-3)](-), and for triglycine and tetraglycine, the EPR-active species [CuLH(-3)](2-) were identified. Further, equilibria of two microspecies were demonstrated for [CuL(2)], [CuL(2)H(-1)](-), and [CuL(2)H(-2)](2-). The magnetic parameters allowed a detailed description of the coordination modes. The most important findings: (1) For the mono complexes, the in-plane sigma-bonds between copper(II) and the equatorial N donors are particularly strong when the same ligand forms several adjacent chelate rings with the participation of amino N, deprotonated peptide N(s), and the carboxylate group. (2) Structures with coupled chelate rings are likewise favored in the bis complexes. Different protonation states of the two ligands are observed in the major isomer of [CuL(2)] ((LH(-1) + LH) coordination), and in the isomers of [CuL(2)H(-2)](2-) ((LH(-2) + L) coordination) for triglycine and tetraglycine.
Inorg Chem Commun, 2006
The reaction of metallic copper, triphenylphosphine and 1,2-naphthoquinone leads to the copper(II... more The reaction of metallic copper, triphenylphosphine and 1,2-naphthoquinone leads to the copper(II) catecholate complex bis(4-triphenylphosphoniono)(naphthalene-1,2-dioxolato)copper(II), the first molecular structure of a Schönberg adduct coordinated to a metal ion.
![Research paper thumbnail of Production of C[sub 59]N:C[sub 60] solid solution](https://attachments.academia-assets.com/66639594/thumbnails/1.jpg)
](AIP Conference Proceedings, 2001
We describe a simple way to produce large quantities of solid solutions of monomer CjgN in pure Q... more We describe a simple way to produce large quantities of solid solutions of monomer CjgN in pure QQ using an electric gas discharge tube. Typical concentrations are 10~5 to 10" 4 CsgN with respect to Q 0 . The 14 N and several 13 C hyperfme constants were measured by ESR. These are a sensitive test for electronic structure calculations of the monomer. As the temperature is raised towards the sc to fee structural transition at 261 K, the ESR spectrum motionally narrows and the activation energy for reorientation is measured. The rotational dynamics of the CsgN monomer between 130 and 600 K parallels that of QQ in the bulk thus interactions between CsgN and C 60 are surprisingly weak.
ABSTRACT Kollektív jelenségeket vizsgáltunk szilárdtestekben multifrekvenciás elektron spin rezon... more ABSTRACT Kollektív jelenségeket vizsgáltunk szilárdtestekben multifrekvenciás elektron spin rezonancia spektroszkópiai módszerrel. - Szupravezetők és rokon mágnesesen rendezett anyagok A ma már "klasszikusnak" számító CuO2 alapú perovszkit szupravezetőkben munkánk a az antiferromágnesség és szupravezető állapotú rendszerek határán levő anyagokra irányult. Részletesen vizsgáltuk az elektromos töltés és mágneses spinsűrüség térbeli eloszlását. - Manganit perovszkitok mágnesesen rendezett és töltésrendezett állapotai Három, szerkezetében különböző rendszert vizsgáltunk, melyeknél a legérdekesebb kérdés az elméletileg jósolt inhomogén töltéseloszlás kísérleti kimutatása volt. - Elektron delokalizáció fullerén és szénalapú nanoszerkezetekben Részletesen vizsgáltuk a C59N-nel dópolt C60 rendszert, amely a fullerén félvezetők modellje lehet. Látszólagos egyszerűsége ellenére különleges mágneses és elektromos tulajdonságokat találtunk, melyeket értelmeztünk. A szén alapú nanocsövekbe fullerén spinjelzőt töltöttünk, ami lehetűvé teszi elektromos tulajdonságainak tanulmányozását. A munkát számos külföldi laboratóriummal együttműködve végeztük. Az ESR vizsgálatokat a BME-n fejlesztett, multifrekvenciás és az MTA-KKI 2004-ben felállított Bruker típusú 9 GHz-s ESR spektrométerén végeztük. Eredményeinket neves folyóiratokban közöltük. Megszerveztük a nagyfrekvenciás ESR spektroszkópia SENTINEL Európai Hálózatának zárókonferenciáját Budapesten. | We investigated collective phenomena in solids by multifrequency electron spin resonance spectroscopy. - Superconductors and parent magnetically ordered materials In the now 'classic' CuO2 based perovskite superconductors we focused on systems on the borderline of antiferromagnetism and superconductivity. We investigated in detail the spatial distribution of magnetic spin density and charge density. - Magnetic and charge ordered states in manganite perovskites We investigated three structurally different systems for which the experimental verification of the theoretically predicted inhomogeneous charge distribution is the most interesting problem. - Electron delocalization in fullerene-based and carbon-based nanostructures We investigated in detail the C59N doped C60 system that may be regarded as a model system for fullerene semiconductors. In spite of its apparent simplicity it shows special electronic and magnetic features that were explained. We filled the carbon nanotubes with fullerene spin labels that enable the study of its electric properties. The work was accomplished in collaboration with several foreign laboratories. The ESR studies were performed on the multifrequency spectrometer built at the BUTE and the Bruker spectrometer at the Chemical Research Institute of the HAS. Results were published in well-known journals. We organized the closing conference of the SENTINEL European Network for high frequency ESR spectroscopy.
Physical Review B, 1999
The anisotropy of the static homogeneous magnetic spin susceptibility of the antiferromagnetic Cu... more The anisotropy of the static homogeneous magnetic spin susceptibility of the antiferromagnetic CuO 2 bilayers and the crystal-field parameters are measured in Gd-doped YBa 2 Cu 3 O 6ϩx ͑small x͒ single crystals using Gd 3ϩ ESR at 9, 75, 150, and 225 GHz. We show that the easy magnetization direction is along ͓100͔ and that there is a magnetostriction leading to an orthorhombic lattice distortion. We observe an antiferromagnetic domain structure corresponding to the two equivalent orthorhombic distortions of the tetragonal lattice which depends on magnetic fields of the order of 1 T. The domain structure is unchanged between 10 and 150 K and is independent of thermal and magnetic history. We discuss two models: ͑i͒ charged domain walls, ͑ii͒ magnetization pinned to a small number of defective oxygen-rich Cu͑1͒ layers.
Journal of the Chemical Society, Perkin Transactions 2, 1993
ABSTRACT
Journal of the Chemical Society, Dalton Transactions, 1992
Transition-metal co-ordination equilibria of 2 (RS)-D-galactothiazolidine-4 (R)-carboxylic acid w... more Transition-metal co-ordination equilibria of 2 (RS)-D-galactothiazolidine-4 (R)-carboxylic acid were studied by potentiometric titrations in the range pH 1.58.5. In most cases,(1, 1, 1),(1, 2, 0) and (1, 2, 0) parent complexes M p L q H r were formed, but in the cases of ...
Journal of Thermal Analysis and Calorimetry, Aug 1, 2011
Surface oxyfluorination had been carried out on polypropylene non-woven fabric (PP NWF) samples o... more Surface oxyfluorination had been carried out on polypropylene non-woven fabric (PP NWF) samples of different morphologies and pore sizes. The modified surfaces were characterised by Attenuated Total Reflectance Fourier Transform InfraRed (ATR-FTIR)-spectroscopy, FTIR imaging microscopy, X-Ray Photoelectron Spectroscopy (XPS), Electron Spin Resonance (ESR) spectroscopy, Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), dynamic rheometry and Thermo-Gravimetry (TG). ATR-FTIR and XPS techniques revealed the presence of -CF, -CF 2 , -CHF and -C(O)F groups. The formed -C(O)F groups mostly got hydrolysed to -COOH groups. The C=O groups of alpha-haloester, and the C=C stretching of the formed -CF=C(OH)-groups could also be detected. Longlived radicals could be detected on the functionalised surfaces as middle-chain peroxy radicals by ESR spectroscopy. SEM micrographs showed slight roughening of the oxyfluorinated surfaces. Oxyfluorination had no significant effect on the crystalline structure and phase composition of the PP NWF samples supported by DSC and XRD measurements. The molecular mass of the samples were unaffected by the oxyfluorination treatment as proved by oscillating rheometry. The surface modification, however, significantly affected the thermal decomposition but not affected the thermo-oxidative decomposition of PP NWFs. Different morphologies and pore sizes of PP NWF samples resulted in reproducibility of the findings, although did not substantially affect surface functionalisation.
Journal of Magnetic Resonance (1969)
Journal of the Chemical Society, Chemical Communications, 1994
ABSTRACT
Studies in Surface Science and Catalysis, 2005
... One can raise the question, what is the Fe(III) spectrum deconvolution good for? First of all... more ... One can raise the question, what is the Fe(III) spectrum deconvolution good for? First of all toget a general picture how the spectrum is composed from the sub-spectra: how much Fe(llI) is sited in FW and EFW environments and what are the symmetries of these sites? ...
Abstract. We describe a simple way to produce large quantities of solid solutions of monomer CjgN... more Abstract. We describe a simple way to produce large quantities of solid solutions of monomer CjgN in pure QQ using an electric gas discharge tube. Typical concentrations are 10~5 to 10"4 CsgN with respect to Q0. The 14N and several 13C hyperfme constants were ...
Materials, 2018
In this study, relationships between preparation conditions, structure, and activity of Pt-contai... more In this study, relationships between preparation conditions, structure, and activity of Pt-containing TiO2 photocatalysts in photoinduced reforming of glycerol for H2 production were explored. Commercial Aerolyst® TiO2 (P25) and homemade TiO2 prepared by precipitation-aging method were used as semiconductors. Pt co-catalysts were prepared by incipient wetness impregnation from aqueous solution of Pt(NH3)4(NO3)2 and activated by calcination, high temperature hydrogen, or nitrogen treatments. The chemico-physical and structural properties were evaluated by XRD, 1H MAS NMR, ESR, XPS, TG-MS and TEM. The highest H2 evolution rate was observed over P25 based samples and the H2 treatment resulted in more active samples than the other co-catalyst formation methods. In all calcined samples, reduction of Pt occurred during the photocatalytic reaction. Platinum was more easily reducible in all of the P25 supported samples compared to those obtained from the more water-retentive homemade TiO2. ...
Studies in Surface Science and Catalysis, 2005
... One can raise the question, what is the Fe(III) spectrum deconvolution good for? First of all... more ... One can raise the question, what is the Fe(III) spectrum deconvolution good for? First of all toget a general picture how the spectrum is composed from the sub-spectra: how much Fe(llI) is sited in FW and EFW environments and what are the symmetries of these sites? ...
Journal of Molecular Structure: THEOCHEM, 1997
A theoretical study on the cyclization of electrophilic radicals was canied out. Transition state... more A theoretical study on the cyclization of electrophilic radicals was canied out. Transition state geometries were obtained by MNDO semiempirical calculations and the calculated properties (orbital energies, orbital coefficients, charge distributions and energy partition) were analysed. Observed regioselectivities can be rationalised on the basis of SOMO-HOMO and SOMO-LUMO orbital interactions. 0 1997 Elsevier Science B.V. TheR spectra for the reaction of lb miasmg from Ref. [2] were recorded in benzene in the presence of 2.6-dichloro-nitrosobenzene spin trap at three different temperatures (153, 58 and 65°C. respectively) and gave superimposed spectra. where two doublets of triplets appeared in each case. the intensity of which were changing in time. One of them having a nitrogen ( 12.8 G) and a large phosphorus coupling ( 18.5 G) can be assigned to the intermediate 4b. while the other triplet having a nitrogen ( 13.0 G) and a hydrogen splitting (7.2 G) may correspond to the six membered cyclic mtermediate (6b). Ol66-1280/97/$17.00 Copyright 0 1997 Elsevier Science B.V. All rights reserved P/I SO 166.1280(96)04870-l
Biochemical and Biophysical Research Communications, 1995
Production and the mechanism of the interactions of free radicals generated by stimulated macroph... more Production and the mechanism of the interactions of free radicals generated by stimulated macrophages in the presence of luminol and a free radical inhibitor was investigated to determine the possibility of using luminol-dependent chemiluminescence for studying photodynamic effects in biology. Earlier measurements have been revisited and additional experiments performed indicating that oxidation products of luminol neither inhibit the in vitro formation of radicals nor quench CL. Simulation based on the mechanism suggested revealed that the likely value for the rate constant of the primary step between luminol and superoxide anion radicals producing luminol radicals is 5؋10 2 -1؋10 3 M ؊1 s ؊1 . It has been established that the ratio of the concentration of radicals generated by the biological system to that formed by oxidation of luminol exceeds 10 3 ; that is, the contribution of the latter is negligible and the system is appropriate to measure quantitatively the effect of excited photosensitizers on free radicals.
Journal of the American Chemical Society, May 1, 2003
A series of isotropic EPR spectra recorded at various concentrations and pH (in the range 2-12) o... more A series of isotropic EPR spectra recorded at various concentrations and pH (in the range 2-12) on equilibrium systems containing copper(II) and diglycine, triglycine, or tetraglycine were analyzed. A purely mathematical method, matrix rank analysis gave the number of independent EPR-active species. Two-dimensional evaluation then resulted in the formation constants and magnetic parameters of 14 metal complexes (including microspecies) in each system. The independent paramagnetic species formed with each ligand are as follows: Cu(2+) (aqua complex), [CuLH](2+), [CuL](+), [CuLH(-1)], [CuLH(-2)](-), [CuL(2)H(2)](2+), [CuL(2)H](+), [CuL(2)], [CuL(2)H(-1)](-), and [CuL(2)H(-2)](2-). Moreover, for diglycine, the diamagnetic complex [Cu(2)L(2)H(-3)](-), and for triglycine and tetraglycine, the EPR-active species [CuLH(-3)](2-) were identified. Further, equilibria of two microspecies were demonstrated for [CuL(2)], [CuL(2)H(-1)](-), and [CuL(2)H(-2)](2-). The magnetic parameters allowed a detailed description of the coordination modes. The most important findings: (1) For the mono complexes, the in-plane sigma-bonds between copper(II) and the equatorial N donors are particularly strong when the same ligand forms several adjacent chelate rings with the participation of amino N, deprotonated peptide N(s), and the carboxylate group. (2) Structures with coupled chelate rings are likewise favored in the bis complexes. Different protonation states of the two ligands are observed in the major isomer of [CuL(2)] ((LH(-1) + LH) coordination), and in the isomers of [CuL(2)H(-2)](2-) ((LH(-2) + L) coordination) for triglycine and tetraglycine.
Inorg Chem Commun, 2006
The reaction of metallic copper, triphenylphosphine and 1,2-naphthoquinone leads to the copper(II... more The reaction of metallic copper, triphenylphosphine and 1,2-naphthoquinone leads to the copper(II) catecholate complex bis(4-triphenylphosphoniono)(naphthalene-1,2-dioxolato)copper(II), the first molecular structure of a Schönberg adduct coordinated to a metal ion.
AIP Conference Proceedings, 2001
We describe a simple way to produce large quantities of solid solutions of monomer CjgN in pure Q... more We describe a simple way to produce large quantities of solid solutions of monomer CjgN in pure QQ using an electric gas discharge tube. Typical concentrations are 10~5 to 10" 4 CsgN with respect to Q 0 . The 14 N and several 13 C hyperfme constants were measured by ESR. These are a sensitive test for electronic structure calculations of the monomer. As the temperature is raised towards the sc to fee structural transition at 261 K, the ESR spectrum motionally narrows and the activation energy for reorientation is measured. The rotational dynamics of the CsgN monomer between 130 and 600 K parallels that of QQ in the bulk thus interactions between CsgN and C 60 are surprisingly weak.
ABSTRACT Kollektív jelenségeket vizsgáltunk szilárdtestekben multifrekvenciás elektron spin rezon... more ABSTRACT Kollektív jelenségeket vizsgáltunk szilárdtestekben multifrekvenciás elektron spin rezonancia spektroszkópiai módszerrel. - Szupravezetők és rokon mágnesesen rendezett anyagok A ma már "klasszikusnak" számító CuO2 alapú perovszkit szupravezetőkben munkánk a az antiferromágnesség és szupravezető állapotú rendszerek határán levő anyagokra irányult. Részletesen vizsgáltuk az elektromos töltés és mágneses spinsűrüség térbeli eloszlását. - Manganit perovszkitok mágnesesen rendezett és töltésrendezett állapotai Három, szerkezetében különböző rendszert vizsgáltunk, melyeknél a legérdekesebb kérdés az elméletileg jósolt inhomogén töltéseloszlás kísérleti kimutatása volt. - Elektron delokalizáció fullerén és szénalapú nanoszerkezetekben Részletesen vizsgáltuk a C59N-nel dópolt C60 rendszert, amely a fullerén félvezetők modellje lehet. Látszólagos egyszerűsége ellenére különleges mágneses és elektromos tulajdonságokat találtunk, melyeket értelmeztünk. A szén alapú nanocsövekbe fullerén spinjelzőt töltöttünk, ami lehetűvé teszi elektromos tulajdonságainak tanulmányozását. A munkát számos külföldi laboratóriummal együttműködve végeztük. Az ESR vizsgálatokat a BME-n fejlesztett, multifrekvenciás és az MTA-KKI 2004-ben felállított Bruker típusú 9 GHz-s ESR spektrométerén végeztük. Eredményeinket neves folyóiratokban közöltük. Megszerveztük a nagyfrekvenciás ESR spektroszkópia SENTINEL Európai Hálózatának zárókonferenciáját Budapesten. | We investigated collective phenomena in solids by multifrequency electron spin resonance spectroscopy. - Superconductors and parent magnetically ordered materials In the now 'classic' CuO2 based perovskite superconductors we focused on systems on the borderline of antiferromagnetism and superconductivity. We investigated in detail the spatial distribution of magnetic spin density and charge density. - Magnetic and charge ordered states in manganite perovskites We investigated three structurally different systems for which the experimental verification of the theoretically predicted inhomogeneous charge distribution is the most interesting problem. - Electron delocalization in fullerene-based and carbon-based nanostructures We investigated in detail the C59N doped C60 system that may be regarded as a model system for fullerene semiconductors. In spite of its apparent simplicity it shows special electronic and magnetic features that were explained. We filled the carbon nanotubes with fullerene spin labels that enable the study of its electric properties. The work was accomplished in collaboration with several foreign laboratories. The ESR studies were performed on the multifrequency spectrometer built at the BUTE and the Bruker spectrometer at the Chemical Research Institute of the HAS. Results were published in well-known journals. We organized the closing conference of the SENTINEL European Network for high frequency ESR spectroscopy.
Physical Review B, 1999
The anisotropy of the static homogeneous magnetic spin susceptibility of the antiferromagnetic Cu... more The anisotropy of the static homogeneous magnetic spin susceptibility of the antiferromagnetic CuO 2 bilayers and the crystal-field parameters are measured in Gd-doped YBa 2 Cu 3 O 6ϩx ͑small x͒ single crystals using Gd 3ϩ ESR at 9, 75, 150, and 225 GHz. We show that the easy magnetization direction is along ͓100͔ and that there is a magnetostriction leading to an orthorhombic lattice distortion. We observe an antiferromagnetic domain structure corresponding to the two equivalent orthorhombic distortions of the tetragonal lattice which depends on magnetic fields of the order of 1 T. The domain structure is unchanged between 10 and 150 K and is independent of thermal and magnetic history. We discuss two models: ͑i͒ charged domain walls, ͑ii͒ magnetization pinned to a small number of defective oxygen-rich Cu͑1͒ layers.
Journal of the Chemical Society, Perkin Transactions 2, 1993
ABSTRACT
Journal of the Chemical Society, Dalton Transactions, 1992
Transition-metal co-ordination equilibria of 2 (RS)-D-galactothiazolidine-4 (R)-carboxylic acid w... more Transition-metal co-ordination equilibria of 2 (RS)-D-galactothiazolidine-4 (R)-carboxylic acid were studied by potentiometric titrations in the range pH 1.58.5. In most cases,(1, 1, 1),(1, 2, 0) and (1, 2, 0) parent complexes M p L q H r were formed, but in the cases of ...
Journal of Thermal Analysis and Calorimetry, Aug 1, 2011
Surface oxyfluorination had been carried out on polypropylene non-woven fabric (PP NWF) samples o... more Surface oxyfluorination had been carried out on polypropylene non-woven fabric (PP NWF) samples of different morphologies and pore sizes. The modified surfaces were characterised by Attenuated Total Reflectance Fourier Transform InfraRed (ATR-FTIR)-spectroscopy, FTIR imaging microscopy, X-Ray Photoelectron Spectroscopy (XPS), Electron Spin Resonance (ESR) spectroscopy, Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), dynamic rheometry and Thermo-Gravimetry (TG). ATR-FTIR and XPS techniques revealed the presence of -CF, -CF 2 , -CHF and -C(O)F groups. The formed -C(O)F groups mostly got hydrolysed to -COOH groups. The C=O groups of alpha-haloester, and the C=C stretching of the formed -CF=C(OH)-groups could also be detected. Longlived radicals could be detected on the functionalised surfaces as middle-chain peroxy radicals by ESR spectroscopy. SEM micrographs showed slight roughening of the oxyfluorinated surfaces. Oxyfluorination had no significant effect on the crystalline structure and phase composition of the PP NWF samples supported by DSC and XRD measurements. The molecular mass of the samples were unaffected by the oxyfluorination treatment as proved by oscillating rheometry. The surface modification, however, significantly affected the thermal decomposition but not affected the thermo-oxidative decomposition of PP NWFs. Different morphologies and pore sizes of PP NWF samples resulted in reproducibility of the findings, although did not substantially affect surface functionalisation.
Journal of Magnetic Resonance (1969)
Journal of the Chemical Society, Chemical Communications, 1994
ABSTRACT
Studies in Surface Science and Catalysis, 2005
... One can raise the question, what is the Fe(III) spectrum deconvolution good for? First of all... more ... One can raise the question, what is the Fe(III) spectrum deconvolution good for? First of all toget a general picture how the spectrum is composed from the sub-spectra: how much Fe(llI) is sited in FW and EFW environments and what are the symmetries of these sites? ...