The Experts below are selected from a list of 2475 Experts worldwide ranked by ideXlab platform
Quanlin Zhao - One of the best experts on this subject based on the ideXlab platform.
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correlation between uv condensation and xe Artificial Weathering tests on ethylene propylene diene monomer rubber
Journal of Failure Analysis and Prevention, 2011Co-Authors: Quanlin Zhao, Xiaogang Li, Zhengfang YeAbstract:Artificial Weathering tests on ethylene–propylene–diene monomer (EPDM) rubber were conducted in a fluorescent UV/condensation Weathering equipment (E-UV environment) and a xenon lamp light exposure and Weathering equipment (E-Xe environment) for different time periods. The correlation between E-UV and E-Xe environment was investigated by using crosslink density as criteria. Thermal gravimetric analysis (TGA) was used to evaluate the thermal stability of EPDM. The fracture morphology was monitored by scanning electron microscope (SEM). The results showed that the correlation between E-UV and E-Xe environments can be expressed as: \( t_{\text{Xe}} = - 7.4818 + 1.1837t_{{{\text{Xe}}{-}{\text{UV}}}} , \) where the correlation coefficient R is 0.9856. The thermal stability of EPDM did not deteriorate dramatically on exposure to the two Artificial Weathering environments. An oxidation layer was formed after 90 days of exposure.
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Correlation Between UV/Condensation and Xe Artificial Weathering Tests on Ethylene–Propylene–Diene Monomer Rubber
Journal of Failure Analysis and Prevention, 2011Co-Authors: Quanlin Zhao, Xiaogang Li, Zhengfang YeAbstract:Artificial Weathering tests on ethylene–propylene–diene monomer (EPDM) rubber were conducted in a fluorescent UV/condensation Weathering equipment (E-UV environment) and a xenon lamp light exposure and Weathering equipment (E-Xe environment) for different time periods. The correlation between E-UV and E-Xe environment was investigated by using crosslink density as criteria. Thermal gravimetric analysis (TGA) was used to evaluate the thermal stability of EPDM. The fracture morphology was monitored by scanning electron microscope (SEM). The results showed that the correlation between E-UV and E-Xe environments can be expressed as: \( t_{\text{Xe}} = - 7.4818 + 1.1837t_{{{\text{Xe}}{-}{\text{UV}}}} , \) where the correlation coefficient R is 0.9856. The thermal stability of EPDM did not deteriorate dramatically on exposure to the two Artificial Weathering environments. An oxidation layer was formed after 90 days of exposure.
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surface degradation of unsaturated polyester resin in xe Artificial Weathering environment
Materials & Design, 2010Co-Authors: Quanlin Zhao, Xiaogang Li, Zhengfang YeAbstract:Unsaturated polyester (UP) resin samples were exposed to Artificial Weathering environment produced by a xenon lamp light exposure and Weathering equipment for different time intervals. The change of appearance, optical property, chemical structure and surface microstructure before and after exposure in this environment was monitored by spectrophotometer, gloss meter, Specular Reflection Fourier Transform Infrared (SR-FTIR) spectroscopy and three-dimensional digital microscope. The results showed that the surface of UP resin turned darker and yellower in the whole Weathering stage. Gloss decreased with increasing aging time due to the increase of surface roughness. SR-FTIR results showed that ester bonds in polymeric chains broke in the aging process. With increasing aging time, small voids can be observed on UP surface and expanded gradually to cracks.
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effect of Artificial Weathering on surface properties of unsaturated polyester up resin
Materials Chemistry and Physics, 2010Co-Authors: Xiaogang Li, Quanlin ZhaoAbstract:Unsaturated polyester resin samples were exposed to Artificial Weathering environment for different time intervals. The change of appearance, morphology, chemical structure and contact angle on unsaturated polyester resin surface before and after exposure in this environment was monitored by spectrophotometer, gloss meter, microscope, Specula Reflection Fourier Transform Infrared (SR-FTIR) spectroscopy and optical contact angle measuring device. The results showed that the surface of unsaturated polyester resin turned darker and yellower in the first stage and then remained nearly unchanged during further ageing. Gloss reached maximum when the sample was aged for 12 days and then decreased. With increasing aging time, small cracks appeared and developed on the unsaturated polyester resin surface. Hydroxyl and carbonyl groups produced in aging process increased the wettability of unsaturated polyester resin surface.
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degradation characterization of ethylene propylene diene monomer epdm rubber in Artificial Weathering environment
Journal of Failure Analysis and Prevention, 2010Co-Authors: Quanlin Zhao, Xiaogang Li, Jianwen Hu, Zhengfang YeAbstract:Ethylene-propylene-diene monomer containing 5-ethylidene-2-norbornene as diene was exposed to Artificial Weathering environment produced by a xenon lamp light exposure and Weathering equipment for different periods of time. The changes of surface color and mechanical properties were monitored by spectrophotometer, computer-controlled tensile testing and hardness measurements. Crosslink density of ethylene-propylene-diene monomer specimens was measured by the solvent swell method. The results showed that the surface of ethylene-propylene-diene monomer became yellower due to the form of carbonyl group. The degradation process proceeded predominantly via cross-linking. With increase in crosslink density, the tensile strength increased and the elongation at fracture decreased.
Xiaogang Li - One of the best experts on this subject based on the ideXlab platform.
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correlation between uv condensation and xe Artificial Weathering tests on ethylene propylene diene monomer rubber
Journal of Failure Analysis and Prevention, 2011Co-Authors: Quanlin Zhao, Xiaogang Li, Zhengfang YeAbstract:Artificial Weathering tests on ethylene–propylene–diene monomer (EPDM) rubber were conducted in a fluorescent UV/condensation Weathering equipment (E-UV environment) and a xenon lamp light exposure and Weathering equipment (E-Xe environment) for different time periods. The correlation between E-UV and E-Xe environment was investigated by using crosslink density as criteria. Thermal gravimetric analysis (TGA) was used to evaluate the thermal stability of EPDM. The fracture morphology was monitored by scanning electron microscope (SEM). The results showed that the correlation between E-UV and E-Xe environments can be expressed as: \( t_{\text{Xe}} = - 7.4818 + 1.1837t_{{{\text{Xe}}{-}{\text{UV}}}} , \) where the correlation coefficient R is 0.9856. The thermal stability of EPDM did not deteriorate dramatically on exposure to the two Artificial Weathering environments. An oxidation layer was formed after 90 days of exposure.
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Correlation Between UV/Condensation and Xe Artificial Weathering Tests on Ethylene–Propylene–Diene Monomer Rubber
Journal of Failure Analysis and Prevention, 2011Co-Authors: Quanlin Zhao, Xiaogang Li, Zhengfang YeAbstract:Artificial Weathering tests on ethylene–propylene–diene monomer (EPDM) rubber were conducted in a fluorescent UV/condensation Weathering equipment (E-UV environment) and a xenon lamp light exposure and Weathering equipment (E-Xe environment) for different time periods. The correlation between E-UV and E-Xe environment was investigated by using crosslink density as criteria. Thermal gravimetric analysis (TGA) was used to evaluate the thermal stability of EPDM. The fracture morphology was monitored by scanning electron microscope (SEM). The results showed that the correlation between E-UV and E-Xe environments can be expressed as: \( t_{\text{Xe}} = - 7.4818 + 1.1837t_{{{\text{Xe}}{-}{\text{UV}}}} , \) where the correlation coefficient R is 0.9856. The thermal stability of EPDM did not deteriorate dramatically on exposure to the two Artificial Weathering environments. An oxidation layer was formed after 90 days of exposure.
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surface degradation of unsaturated polyester resin in xe Artificial Weathering environment
Materials & Design, 2010Co-Authors: Quanlin Zhao, Xiaogang Li, Zhengfang YeAbstract:Unsaturated polyester (UP) resin samples were exposed to Artificial Weathering environment produced by a xenon lamp light exposure and Weathering equipment for different time intervals. The change of appearance, optical property, chemical structure and surface microstructure before and after exposure in this environment was monitored by spectrophotometer, gloss meter, Specular Reflection Fourier Transform Infrared (SR-FTIR) spectroscopy and three-dimensional digital microscope. The results showed that the surface of UP resin turned darker and yellower in the whole Weathering stage. Gloss decreased with increasing aging time due to the increase of surface roughness. SR-FTIR results showed that ester bonds in polymeric chains broke in the aging process. With increasing aging time, small voids can be observed on UP surface and expanded gradually to cracks.
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effect of Artificial Weathering on surface properties of unsaturated polyester up resin
Materials Chemistry and Physics, 2010Co-Authors: Xiaogang Li, Quanlin ZhaoAbstract:Unsaturated polyester resin samples were exposed to Artificial Weathering environment for different time intervals. The change of appearance, morphology, chemical structure and contact angle on unsaturated polyester resin surface before and after exposure in this environment was monitored by spectrophotometer, gloss meter, microscope, Specula Reflection Fourier Transform Infrared (SR-FTIR) spectroscopy and optical contact angle measuring device. The results showed that the surface of unsaturated polyester resin turned darker and yellower in the first stage and then remained nearly unchanged during further ageing. Gloss reached maximum when the sample was aged for 12 days and then decreased. With increasing aging time, small cracks appeared and developed on the unsaturated polyester resin surface. Hydroxyl and carbonyl groups produced in aging process increased the wettability of unsaturated polyester resin surface.
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degradation characterization of ethylene propylene diene monomer epdm rubber in Artificial Weathering environment
Journal of Failure Analysis and Prevention, 2010Co-Authors: Quanlin Zhao, Xiaogang Li, Jianwen Hu, Zhengfang YeAbstract:Ethylene-propylene-diene monomer containing 5-ethylidene-2-norbornene as diene was exposed to Artificial Weathering environment produced by a xenon lamp light exposure and Weathering equipment for different periods of time. The changes of surface color and mechanical properties were monitored by spectrophotometer, computer-controlled tensile testing and hardness measurements. Crosslink density of ethylene-propylene-diene monomer specimens was measured by the solvent swell method. The results showed that the surface of ethylene-propylene-diene monomer became yellower due to the form of carbonyl group. The degradation process proceeded predominantly via cross-linking. With increase in crosslink density, the tensile strength increased and the elongation at fracture decreased.
Xianai Huang - One of the best experts on this subject based on the ideXlab platform.
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Comparison of Weathering behavior of heat-treated jack pine during different Artificial Weathering conditions
2020Co-Authors: Duygu Kocaefe, Xianai Huang, Yasar S KocaefeAbstract:Heat treatment improves the dimensional stability (reduced hygroscopicity and wettabilty) of wood and its resistance to fungi, and results in darker color. However, wood loses its color when exposed to Weathering (sunlight, rain etc.). In this study, the surface degradation and color loss of het-treated wood taking place during Weathering were investigated under different conditions. Jack pine (Pinus banksiana) samples, heat-treated at 210°C, were exposed to Artificial Weathering with and without water spray for different times. Before and after exposure, their color and wettability by water were determined. Structural changes and chemical modifications at exposed surfaces were also investigated using florescent microscopy, SEM, FTIR spectroscopy, and XPS. The results revealed that the photo-degradation of lignin play important roles in color change and wetting behavior of heat-treated wood surfaces during Weathering. Heat-treated wood was degraded more during Weathering if exposed to water spray.
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Study of the degradation of heat-treated jack pine under different Artificial Weathering conditions
2020Co-Authors: Duygu Kocaefe, Xianai Huang, Yasar S KocaefeAbstract:Heat-treated wood is a natural product heat-treated at high temperatures in the range of 180 to 240°C. Heat treatment modifies wood both chemically and physically. However, heat-treated wood is susceptible to Weathering degradation. It is of considerable importance to investigate the influence of Weathering on the degradation processes of heat-treated wood under different conditions. Jack pine (Pinus banksiana) heat-treated at different temperature were exposed to Artificial Weathering with and without water spray for different periods in order to understand the effect of Weathering factors on degradation processes. Before and after Weathering, their color and wettability by water were determined. Structural changes and chemical modifications at exposed surfaces were also investigated using florescent microscopy imaging, SEM, FTIR spectroscopy, and XPS. The results revealed that heat-treated wood was degraded more during Weathering with water spray than without water spray.
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quantitative characterization of chemical degradation of heat treated wood surfaces during Artificial Weathering using xps
Surface and Interface Analysis, 2013Co-Authors: Duygu Kocaefe, Xianai Huang, Yasar S Kocaefe, Yaman BolukAbstract:The X-ray photoelectron spectroscopy (XPS) study of three heat-treated North American wood species (jack pine, birch and aspen) was carried out to evaluate chemical modifications occurring on the wood surface during Artificial Weathering for different times. The results suggest that the Weathering reduces lignin content (aromatic rings) at the surface of heat-treated wood, consequently, the carbohydrates content increases. This results in surfaces richer in cellulose and poorer in lignin. Heat-treated wood surfaces become acidic due to Weathering, and the acidity increases as the Weathering time increases. Three possible reasons are given to account for the increase of acidity during Weathering. The lignin content increases, whereas the hemicelluloses content decrease due to heat treatment. Heat-treated woods have lower acidity to basicity ratios than the corresponding untreated woods for all three species because of the decrease in carboxylic acid functions mainly present in hemicelluloses. The wood composition changes induced by Weathering are more significant compared to those induced by heat treatment at wood surface. Exposure to higher temperatures causes more degradation of hemicelluloses, and this characteristic is maintained during Weathering. However, the wood direction has more effect on chemical composition modification during Weathering compared to that of heat treatment temperature. The heat-treated jack pine is affected most by Weathering followed by heat-treated aspen and birch. This is related to differences in content and structure of lignin of softwood and hardwood. The use of XPS technique has proved to be a reliable method for wood surface studies. Copyright © 2012 John Wiley & Sons, Ltd.
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structural analysis of heat treated birch betule papyrifera surface during Artificial Weathering
Applied Surface Science, 2013Co-Authors: Xianai Huang, Duygu Kocaefe, Yasar S Kocaefe, Yaman Boluk, Cornelia KrauseAbstract:Abstract Effect of Artificial Weathering on the surface structural changes of birch (Betule papyrifera) wood, heat-treated to different temperatures, was studied using the fluorescence microscopy and the scanning electron microscopy (SEM). Changes in the chemical structure of wood components were analyzed by FTIR in order to understand the mechanism of degradation taking place due to heat treatment and Artificial Weathering. The results are compared with those of the untreated (kiln-dried) birch. The SEM analysis results show that the effect of Weathering on the cell wall of the untreated birch surface is more than that of heat-treated samples. The FTIR spectroscopy results indicate that lignin is the most sensitive component of heat-treated birch to the Weathering degradation process. Elimination of the amorphous and highly crystallised cellulose is observed for both heat-treated and untreated wood during Weathering. It is also observed that heat treatment increases the lignin and crystallised cellulose contents, which to some extent protects heat-treated birch against degradation due to Weathering.
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a spectrocolorimetric and chemical study on color modification of heat treated wood during Artificial Weathering
Applied Surface Science, 2012Co-Authors: Xianai Huang, Duygu Kocaefe, Yasar S Kocaefe, Yaman Boluk, Andre PichetteAbstract:Abstract Effect of Artificial Weathering on the wood surface color modifications of three North American species (jack pine, aspen, and birch) heat-treated under different temperatures was studied by spectrocolorimetric colormeter (datacolor, CHECK TM). Data was analyzed using the reflectance spectra (400–700 nm) as well as the CIE- L * a * b * system and Δ E . Kubelka–Munk (K–M) spectra of samples were recorded as a function of Artificial Weathering time to obtain the absorption maxima of the chromophore woods formed during Artificial Weathering. The results were compared with those of the respective untreated (Kiln-dried) species. Analysis of chemical components shows that the lignin percent of jack pine, aspen, and birch increased after heat treatment (28.66–35.9%, 20.27–26.41%, and 19.04–22.71% respectively) which might be due to smaller influence of heat treatment on lignin content than hemicelluloses. This improves the resistance of heat-treated wood to photo-degradation. This is also supported by the smaller change observed in K–M spectra and total color parameters in CIE- L * a * b * system of heat-treated wood samples compared to those of untreated wood when weathered for72 h. However, the lignin percent of heat-treated woods reduce to maximum 2.5% after Artificial Weathering of 1512 h. This suggests that the Weathering degrades most lignin matrix; consequently, both the colors of heat-treated woods and untreated woods are lighter and very similar after a long period of Artificial Weathering.
Andre Pichette - One of the best experts on this subject based on the ideXlab platform.
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a spectrocolorimetric and chemical study on color modification of heat treated wood during Artificial Weathering
Applied Surface Science, 2012Co-Authors: Xianai Huang, Duygu Kocaefe, Yasar S Kocaefe, Yaman Boluk, Andre PichetteAbstract:Abstract Effect of Artificial Weathering on the wood surface color modifications of three North American species (jack pine, aspen, and birch) heat-treated under different temperatures was studied by spectrocolorimetric colormeter (datacolor, CHECK TM). Data was analyzed using the reflectance spectra (400–700 nm) as well as the CIE- L * a * b * system and Δ E . Kubelka–Munk (K–M) spectra of samples were recorded as a function of Artificial Weathering time to obtain the absorption maxima of the chromophore woods formed during Artificial Weathering. The results were compared with those of the respective untreated (Kiln-dried) species. Analysis of chemical components shows that the lignin percent of jack pine, aspen, and birch increased after heat treatment (28.66–35.9%, 20.27–26.41%, and 19.04–22.71% respectively) which might be due to smaller influence of heat treatment on lignin content than hemicelluloses. This improves the resistance of heat-treated wood to photo-degradation. This is also supported by the smaller change observed in K–M spectra and total color parameters in CIE- L * a * b * system of heat-treated wood samples compared to those of untreated wood when weathered for72 h. However, the lignin percent of heat-treated woods reduce to maximum 2.5% after Artificial Weathering of 1512 h. This suggests that the Weathering degrades most lignin matrix; consequently, both the colors of heat-treated woods and untreated woods are lighter and very similar after a long period of Artificial Weathering.
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changes in wettability of heat treated wood due to Artificial Weathering
Wood Science and Technology, 2012Co-Authors: Xianai Huang, Duygu Kocaefe, Yasar S Kocaefe, Yaman Boluk, Andre PichetteAbstract:Effect of Artificial Weathering on the wettability of three heat-treated North American wood species (jack pine, aspen, and birch) is studied from the point of view of the structural and chemical changes taking place on the wood surface. Weathering increases wettability of all three heat-treated woods by water. Changes in wettability during Artificial Weathering differ according to heat treatment procedure and wood species and are likely due to combination of structural and chemical changes of the surfaces. Scanning electron microscopic analysis indicates that cracks form due to degradation taking place during Weathering. As a result, water has easier entry into the cell wall, which consequently increases wettability. IR spectra suggest that the OH/CH2 ratio for heat-treated specimens is inversely proportional to the contact angle regardless of the type of wood species. The presence of cellulose-rich layer on wood surface and increasing amount of amorphous cellulose transformed from crystallized cellulose due to Weathering result in increase in hydroxyl; consequently, it increases heat-treated wood wettability.
Jianwen Hu - One of the best experts on this subject based on the ideXlab platform.
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degradation characterization of ethylene propylene diene monomer epdm rubber in Artificial Weathering environment
Journal of Failure Analysis and Prevention, 2010Co-Authors: Quanlin Zhao, Xiaogang Li, Jianwen Hu, Zhengfang YeAbstract:Ethylene-propylene-diene monomer containing 5-ethylidene-2-norbornene as diene was exposed to Artificial Weathering environment produced by a xenon lamp light exposure and Weathering equipment for different periods of time. The changes of surface color and mechanical properties were monitored by spectrophotometer, computer-controlled tensile testing and hardness measurements. Crosslink density of ethylene-propylene-diene monomer specimens was measured by the solvent swell method. The results showed that the surface of ethylene-propylene-diene monomer became yellower due to the form of carbonyl group. The degradation process proceeded predominantly via cross-linking. With increase in crosslink density, the tensile strength increased and the elongation at fracture decreased.
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ageing behavior of acrylic polyurethane varnish coating in Artificial Weathering environments
Progress in Organic Coatings, 2009Co-Authors: Quanlin Zhao, Xiaogang Li, Jianwen HuAbstract:Acrylic polyurethane varnish coatings were exposed in two Artificial Weathering environments produced by a fluorescent UV/condensation Weathering device and a xenon lamp exposure and Weathering equipment for different time periods. The ageing behavior of the coating was evaluated by using film thickness gauge, glossmeter, spectrophotometer, scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and electrochemical impedance spectroscopy (EIS). The results showed that the Xenotest protocol had a significant effect on the thickness loss and gloss. However, the yellow index measurements and low frequency impedance showed that greater degradation was caused by the UV exposure protocol. These findings were supported by the results obtained from FTIR analysis. In the two Artificial Weathering environments, the low frequency impedance modulus of intact coatings decreased exponentially with increase of ageing time, and correlated with the changes of other properties of ageing coatings, which can be used to predict coatings lifetime.
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uv aging characterization of epoxy varnish coated steel upon exposure to Artificial Weathering environment
Materials & Design, 2009Co-Authors: Jianwen Hu, Xiaogang Li, Quanlin ZhaoAbstract:Abstract Epoxy varnish coating was exposed to Artificial Weathering environment produced by fluorescent UV/condensation Weathering equipment for different time periods. The degradation process of epoxy varnish coating was studied by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and adhesion test. The results showed that the electrochemical behavior of aged coating was closely related to the formation and development of blisters on the surface due to coating degradation. The coating resistance, R p , decreased to a lower value after 28 days of exposure, which indicated significant deterioration of barrier properties. Small blisters were observed on coating surface after 21 days of exposure. With increasing aging time, blisters grow up and subsequently broke. The mechanism of blisters formation and subsequent breakage were suggested. The soluble degradation products penetrate into the coating along with water to form osmotic cells leading to the form of blisters on the coating surface under the alternating wet and UV irradiation condition. The spread of degradation areas caused the growth and development of blisters. With the loss of coating material and embrittlement, cracks appear on the surface and the blisters break, which may result in the significant deterioration of bulk properties of the coatings.