Distributions of nuclear magnetic resonance(NMR)relaxation times provide detailed information about the water in wood.This study documents the water dynamics analysis of T_(2)and T_(1)distributions for saturated delig...Distributions of nuclear magnetic resonance(NMR)relaxation times provide detailed information about the water in wood.This study documents the water dynamics analysis of T_(2)and T_(1)distributions for saturated delignified sapwood(DSW),delignified heartwood(DHW)and lignocellulose(LC)samples at different temperatures.Results indicate that below the freezing point of bulk water,free water freezes,causing its signal to disappear from the distribution.Then,the low temperature distributions of the unfrozen bound water contain more information about its components,with DSW,DHW and LC containing two distinct states of bound water(OH bound water(B-water)and more freely bound water(C-water)).Furthermore,it was observed that within the temperature range of−3°C to−60°C,B-water in DSW,DHW and LC maintained a higher unfrozen water content(UWC)value than C-water,and the T_(1)/T_(2)ratios for B-water were consistently higher than that for C-water,indicating that B-water has a greater antifreeze capacity.T_(2)and T_(1)distributions offer different kinds of information about water components,and all peaks within the distribution have been assigned.展开更多
Heat treatment is applied towood to improve various properties of thematerial.Thepresent study focuses on the colour changes of wood veneer samples due to heat treatment.Native wood species fromJapan and Europe,such a...Heat treatment is applied towood to improve various properties of thematerial.Thepresent study focuses on the colour changes of wood veneer samples due to heat treatment.Native wood species fromJapan and Europe,such as Japanese oak(Quercus mongolica var.crispula),field maple(Acer campestre)and Scots pine(Pinus sylvestris)were used in the experiments.A laboratory-type oven was used to apply the heat at a temperature of 190○C,in the presence of oxygen,for different periods,gradually increasing from 5 to 40 min.The CIELab system(a colour space defined by the International Commission on Illumination)and Near Infrared Spectroscopy(NIR)were employed to evaluate the colour modifications on the samples.As expected,the heat treatment affected the colour of the samples.The lightness index decreased across the three wood species during the treatment.The chroma coordinates changed for pine and maple,while little change occurred in Japanese oak.The overall total colour differences reached their maximum at the final 40-min interval for all wood types.Based on the NIR evaluation,it was found that drastic thermal denaturation of cellulose was unlikely to occur,and the changes in the intermolecular interaction of water affected the colour of the specimens.The data and information of this study could be useful for industrial applications where the veneer of such species is desired.Such heat-treated veneers can be considered as value-added products in furniture manufacturing as well as restoration of furniture units where such veneer is used as an overlay.展开更多
基金supported by Natural Science Foundation of Inner Mongolia Autonomous Region of China (2023MS03027)the National Natural Science Foundation of China (31860185 and 31160141)
文摘Distributions of nuclear magnetic resonance(NMR)relaxation times provide detailed information about the water in wood.This study documents the water dynamics analysis of T_(2)and T_(1)distributions for saturated delignified sapwood(DSW),delignified heartwood(DHW)and lignocellulose(LC)samples at different temperatures.Results indicate that below the freezing point of bulk water,free water freezes,causing its signal to disappear from the distribution.Then,the low temperature distributions of the unfrozen bound water contain more information about its components,with DSW,DHW and LC containing two distinct states of bound water(OH bound water(B-water)and more freely bound water(C-water)).Furthermore,it was observed that within the temperature range of−3°C to−60°C,B-water in DSW,DHW and LC maintained a higher unfrozen water content(UWC)value than C-water,and the T_(1)/T_(2)ratios for B-water were consistently higher than that for C-water,indicating that B-water has a greater antifreeze capacity.T_(2)and T_(1)distributions offer different kinds of information about water components,and all peaks within the distribution have been assigned.
文摘Heat treatment is applied towood to improve various properties of thematerial.Thepresent study focuses on the colour changes of wood veneer samples due to heat treatment.Native wood species fromJapan and Europe,such as Japanese oak(Quercus mongolica var.crispula),field maple(Acer campestre)and Scots pine(Pinus sylvestris)were used in the experiments.A laboratory-type oven was used to apply the heat at a temperature of 190○C,in the presence of oxygen,for different periods,gradually increasing from 5 to 40 min.The CIELab system(a colour space defined by the International Commission on Illumination)and Near Infrared Spectroscopy(NIR)were employed to evaluate the colour modifications on the samples.As expected,the heat treatment affected the colour of the samples.The lightness index decreased across the three wood species during the treatment.The chroma coordinates changed for pine and maple,while little change occurred in Japanese oak.The overall total colour differences reached their maximum at the final 40-min interval for all wood types.Based on the NIR evaluation,it was found that drastic thermal denaturation of cellulose was unlikely to occur,and the changes in the intermolecular interaction of water affected the colour of the specimens.The data and information of this study could be useful for industrial applications where the veneer of such species is desired.Such heat-treated veneers can be considered as value-added products in furniture manufacturing as well as restoration of furniture units where such veneer is used as an overlay.
