The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Manfred Schreiner - One of the best experts on this subject based on the ideXlab platform.
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Accelerated UV ageing studies of acrylic, alkyd, and Polyvinyl Acetate paints: Influence of inorganic pigments
Microchemical Journal, 2020Co-Authors: Valentina Pintus, Manfred SchreinerAbstract:Abstract The stability of two types of acrylic binding media, alkyd and Polyvinyl Acetate (PVAc), four widely used synthetic binders in modern and contemporary art, to UV light also including the UV-B range (315–280 nm, middle UV) for simulating sunlight outdoor conditions was studied and compared by double-shot and single-shot Py-GC/MS, FTIR-ATR, and colour measurements. Thermally assisted hydrolysis and methylation (THM-GC/MS) analyses were used for the alkyd. Additionally, the influence of inorganic pigments on the photo-oxidative stability of the binding media was also considered. For this purpose, the binders in their pure form as well as mixed with eight different inorganic pigments (titanium white—anatase and rutile, cadmium yellow, cadmium red, hydrated chromium oxide green, ultramarine blue, raw umber Cyprus, and ivory black) were exposed to the accelerating artificial UV ageing for different periods of time and analysed before and after UV exposure. After UV ageing, the double-shot Py-GC/MS detected the effect of photo-oxidative processes of the binders in a much more detailed way than by the single shot. For instance, photo-oxidation of the acrylics resulted in a production of oligomers even during the thermal desorption step of double-shot Py-GC/MS and in a decrease of the EA and nBA main monomers in the pyrolysis second step. Contrarily, the aged alkyd samples were mostly characterised by a decrease of unsaturated fatty acids and especially by the increase of free ortho-phtalic acid detected by double-shot Py-GC/MS and THM-GC/MS, which is also reflected in the FTIR-ATR results. On the other hand, an increase of free acetic acid was observed for the aged Polyvinyl Acetate by double-shot Py-GC/MS. Colour measurements recorded a greater sensitivity of the alkyd paints, shown by to the bigger shift of L*, a*, and b* coordinates and change of E* values. Of additional interest was the higher sensitivity to the UV light for synthetic binding media in combination with pigments.
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photochemical degradation study of Polyvinyl Acetate paints used in artworks by py gc ms
Journal of Analytical and Applied Pyrolysis, 2012Co-Authors: Valentina Pintus, Manfred SchreinerAbstract:Photochemical degradation of commercial Polyvinyl Acetate (PVAc) homopolymer and PVAc paints mixed with burnt umber, cobalt blue, cadmium red dark, nickel azo yellow and titanium white commonly used for artworks were studied by pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Py–GC/MS with single-shot technique was used for the characterization of the thermal degradation of PVAc at different temperatures, while the double-shot technique of Py–GC/MS was used to reveal the differences in the specimens before and after UV ageing, including the changes of detectable amounts of deacetylation product – acetic acid and plasticizers such as diethyl phthalate (DEP). Furthermore, the relative concentration of the pyrolysis products of the paint samples could be measured and compared in the second step of the double-shot Py–GC/MS, which are highly dependent on the presence of pigments and the ageing status of PVAc paints.
Enas A Alhashmi - One of the best experts on this subject based on the ideXlab platform.
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assessing the recycling potential of industrial wastewater to replace fresh water in concrete mixes application of Polyvinyl Acetate resin wastewater
Journal of Cleaner Production, 2011Co-Authors: Zainab Z Ismail, Enas A AlhashmiAbstract:Abstract This study presents the use of industrial wastewater released from Polyvinyl Acetate resin manufacturing plant to totally replace the fresh water in concrete composites. Seventy-two laboratory prepared concrete composites were tested to investigate the effect of using various PVAW/C ratios of 0.30, 0.35, 0.40, and 0.45 on the slump, compressive strength, flexural strength, and dry density of the concrete mixes. Results indicated a slight to moderate increase in compressive strength and hard density values compared to those of the control concrete made with fresh water at 7 and 28 day curing. On the contrary, a reduction in the slump values of the PVAW–concrete was observed compared to the slump of the control mixes. However, the slump values increased with increasing the PVAW/C ratios. On the other hand, the waste material leaching test revealed that none of the PVAW toxic constituents was detected. The findings of this work would form basic information for recycling PVAW in concrete mixes and indicate a potential alternative for diminution the adverse effects on the environment posed by the hazardous effluent of the Polyvinyl Acetate resin industry.
Valentina Pintus - One of the best experts on this subject based on the ideXlab platform.
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Accelerated UV ageing studies of acrylic, alkyd, and Polyvinyl Acetate paints: Influence of inorganic pigments
Microchemical Journal, 2020Co-Authors: Valentina Pintus, Manfred SchreinerAbstract:Abstract The stability of two types of acrylic binding media, alkyd and Polyvinyl Acetate (PVAc), four widely used synthetic binders in modern and contemporary art, to UV light also including the UV-B range (315–280 nm, middle UV) for simulating sunlight outdoor conditions was studied and compared by double-shot and single-shot Py-GC/MS, FTIR-ATR, and colour measurements. Thermally assisted hydrolysis and methylation (THM-GC/MS) analyses were used for the alkyd. Additionally, the influence of inorganic pigments on the photo-oxidative stability of the binding media was also considered. For this purpose, the binders in their pure form as well as mixed with eight different inorganic pigments (titanium white—anatase and rutile, cadmium yellow, cadmium red, hydrated chromium oxide green, ultramarine blue, raw umber Cyprus, and ivory black) were exposed to the accelerating artificial UV ageing for different periods of time and analysed before and after UV exposure. After UV ageing, the double-shot Py-GC/MS detected the effect of photo-oxidative processes of the binders in a much more detailed way than by the single shot. For instance, photo-oxidation of the acrylics resulted in a production of oligomers even during the thermal desorption step of double-shot Py-GC/MS and in a decrease of the EA and nBA main monomers in the pyrolysis second step. Contrarily, the aged alkyd samples were mostly characterised by a decrease of unsaturated fatty acids and especially by the increase of free ortho-phtalic acid detected by double-shot Py-GC/MS and THM-GC/MS, which is also reflected in the FTIR-ATR results. On the other hand, an increase of free acetic acid was observed for the aged Polyvinyl Acetate by double-shot Py-GC/MS. Colour measurements recorded a greater sensitivity of the alkyd paints, shown by to the bigger shift of L*, a*, and b* coordinates and change of E* values. Of additional interest was the higher sensitivity to the UV light for synthetic binding media in combination with pigments.
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photochemical degradation study of Polyvinyl Acetate paints used in artworks by py gc ms
Journal of Analytical and Applied Pyrolysis, 2012Co-Authors: Valentina Pintus, Manfred SchreinerAbstract:Photochemical degradation of commercial Polyvinyl Acetate (PVAc) homopolymer and PVAc paints mixed with burnt umber, cobalt blue, cadmium red dark, nickel azo yellow and titanium white commonly used for artworks were studied by pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Py–GC/MS with single-shot technique was used for the characterization of the thermal degradation of PVAc at different temperatures, while the double-shot technique of Py–GC/MS was used to reveal the differences in the specimens before and after UV ageing, including the changes of detectable amounts of deacetylation product – acetic acid and plasticizers such as diethyl phthalate (DEP). Furthermore, the relative concentration of the pyrolysis products of the paint samples could be measured and compared in the second step of the double-shot Py–GC/MS, which are highly dependent on the presence of pigments and the ageing status of PVAc paints.
Jirri Malek - One of the best experts on this subject based on the ideXlab platform.
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structural relaxation of Polyvinyl Acetate pvac
Polymer, 2008Co-Authors: Roman Svoboda, Pavla Pustkova, Jirri MalekAbstract:Abstract Structural relaxation of Polyvinyl Acetate (PVAc) was studied by mercury dilatometry and differential scanning calorimetry. Tool–Narayanaswamy–Moynihan (TNM) and Adam–Gibbs–Scherer (AGS) models were used to fit numerous experimental data. Single set of volume and enthalpy relaxation parameters describing all performed experiments was found for each model. Comparison of volume and enthalpy relaxation was made on the basis of TNM parameter values. The famous volume relaxation measurements made by Kovacs [Fortschr Hochpolym Forsch 1963;3:394–507] were successfully fitted using the same set of parameters. Furthermore, several non-fitting methods of TNM parameters' estimation (including, e.g., peak-shift method or inflectional analysis) were applied to our data and their critical comparison is outlined. For most methods a good agreement with curve-fitting results was achieved.
Xiao Yu Wu - One of the best experts on this subject based on the ideXlab platform.
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development of controlled release amorphous solid dispersions crasd using Polyvinyl Acetate based release retarding materials effect of dosage form design
European Journal of Pharmaceutical Sciences, 2018Co-Authors: Jamie Anne Lugtupe, Alireza Ghaffari, Kuan Chen, Anil Kane, Xiao Yu WuAbstract:Abstract The amorphous solid dispersion (ASD) technique has been employed to formulate poorly-soluble drugs, however, development of solid dosage forms with ASD is challenging due to the high propensity of amorphous drug to precipitate upon dissolution. Thus this work aimed to explore the potential of controlled release amorphous solid dispersion (CRASD) systems using Polyvinyl Acetate (PVAc) as a release-retarding excipient to mitigate the drug precipitation during dissolution of poorly water-soluble drugs. A number of solid oral CRASD dosage forms in different shapes and structures were prepared to contain spray-dried SD powders of a model BCS Class II drug, celecoxib (CEL), Polyvinylpyrrolidone (PVP) and Polyvinyl Acetate (PVAc) which was incorporated in varying ways. In vitro dissolution tests were performed to investigate the effect of dosage form design on the dissolution/recrystallization profiles. The results indicated that despite nearly identical formulation compositions, the dissolution/recrystallization profiles could be tailored by changing the dosage form design. Matrix-form granules demonstrated greatest improvement of solubility appropriate for rapid drug release, while membrane-coated beads appeared to have the greatest potential for sustained release and thereby the least possibility of precipitation during dissolution. These results suggest that appropriate dosage form design of CRASD systems is of potential to reduce the problem of precipitation during dissolution of poorly soluble drugs.
