The properties of wood can be improved through steam-heat treatment.There are many studies about mechanical properties of steam-heat treated wood,but very few studies are on the aspects of chemical modifications.In th...The properties of wood can be improved through steam-heat treatment.There are many studies about mechanical properties of steam-heat treated wood,but very few studies are on the aspects of chemical modifications.In this study,FT-IR spectra combined with SD-IR spectra,correlation coefficients and 2DIR spectra are employed to analyze the chemical modifications of teak[Tectona grandis L.F.） wood during steam-heat treatment under treatment temperatures from 120 ℃ to 220 ℃ at intervals of 20 ℃.Acetic acid,which is produced during steam-heat treatment,acts as a catalyst of condensation and degradation reactions of wood components.The changes of wood components are more and more intense with increasing the treatment temperature.The sensitivity of wood samples to thermal perturbation rises initially with increasing treatment temperature before falling back.The steam-heat treated wood under180℃ is the most sensitive.展开更多
Two-dimensional FT-IR correlation spectroscopy was used to reveal the structural changes of isotactic polypropylene（iPP） mesophase during the heating process.The co-relationship among the regular helical bands of iP...Two-dimensional FT-IR correlation spectroscopy was used to reveal the structural changes of isotactic polypropylene（iPP） mesophase during the heating process.The co-relationship among the regular helical bands of iPP was discussed according to synchronous spectrum.The results show that the segments with different length-helixes were found to undergo a disordered process in the temperature range of 25-60 ℃.展开更多
A novel compound, （4,4＇-Hbpy）3[NaMo8O26]（4,4＇-bpy）2（H2O）4 1 （bpy=bipydine）, was synthesized by the hydrothermal method. Single-crystal X-ray diffraction shows that compound 1 belongs to the monoclinic system...A novel compound, （4,4＇-Hbpy）3[NaMo8O26]（4,4＇-bpy）2（H2O）4 1 （bpy=bipydine）, was synthesized by the hydrothermal method. Single-crystal X-ray diffraction shows that compound 1 belongs to the monoclinic system, space group C2/m with a=19.1921（5）, b=18.6931（6）, c=9.3821（3） A° β=104.8020（11）°, V=3254.22（17）A°^3 C50H51Mo8N10NaO30, Mr=2062.52, Z=2, F（000）=2016, μ=1.591 mm^-1 and Dc=2.105 g/cm^3. The final R=0.0283 and wR=0.0912 for 3118 observed reflections （I〉20（I））. Compound 1 contains the β-[Mo8O26]^4-anion, sodium ion, 4,4＇-bpy and lattice crystalline water molecules. The β-[MosO26] units link the sodium ion to form a chain structure. The infinitechains of [Na（Mo8O26）]^3- blocks are surrounded by protonized 4,4＇-bpy cations, 4,4＇-bpy and lattice crystalline water molecules. The 2D-IR correlation spectroscopy study indicates that the stretching vibrations of Mo=O occur more preferentially due to the thermal effect. The TGA analysis shows that compound 1 has high thermal stability.展开更多
基金This work is by the National Natural Science Foundation of China(No.22203006,No.21927901,No.92261206,No.21627805,No.12174012,No.21673004,No.21821004,No.21674001,and No.21790363)Ministry of Science and Technology of China(a special talent program)and the Beijing City.
基金sponsored by the National Natural Science Foundation of China(No.31270591)Province-Academy Cooperation Project of Zhejiang Province and Chinese Academy of Forestry(No.2013SY01)
文摘The properties of wood can be improved through steam-heat treatment.There are many studies about mechanical properties of steam-heat treated wood,but very few studies are on the aspects of chemical modifications.In this study,FT-IR spectra combined with SD-IR spectra,correlation coefficients and 2DIR spectra are employed to analyze the chemical modifications of teak[Tectona grandis L.F.） wood during steam-heat treatment under treatment temperatures from 120 ℃ to 220 ℃ at intervals of 20 ℃.Acetic acid,which is produced during steam-heat treatment,acts as a catalyst of condensation and degradation reactions of wood components.The changes of wood components are more and more intense with increasing the treatment temperature.The sensitivity of wood samples to thermal perturbation rises initially with increasing treatment temperature before falling back.The steam-heat treated wood under180℃ is the most sensitive.
基金financially supported by the National Natural Science Foundation of China(No.51373003)
文摘Two-dimensional FT-IR correlation spectroscopy was used to reveal the structural changes of isotactic polypropylene（iPP） mesophase during the heating process.The co-relationship among the regular helical bands of iPP was discussed according to synchronous spectrum.The results show that the segments with different length-helixes were found to undergo a disordered process in the temperature range of 25-60 ℃.
基金This work was supported by the Foundation of Education Committee of Fujian Province (K02028, JB04049), the State Key Laboratory of Structural Chemistry, and Science and Technology Foundation of Fuzhou University
文摘A novel compound, （4,4＇-Hbpy）3[NaMo8O26]（4,4＇-bpy）2（H2O）4 1 （bpy=bipydine）, was synthesized by the hydrothermal method. Single-crystal X-ray diffraction shows that compound 1 belongs to the monoclinic system, space group C2/m with a=19.1921（5）, b=18.6931（6）, c=9.3821（3） A° β=104.8020（11）°, V=3254.22（17）A°^3 C50H51Mo8N10NaO30, Mr=2062.52, Z=2, F（000）=2016, μ=1.591 mm^-1 and Dc=2.105 g/cm^3. The final R=0.0283 and wR=0.0912 for 3118 observed reflections （I〉20（I））. Compound 1 contains the β-[Mo8O26]^4-anion, sodium ion, 4,4＇-bpy and lattice crystalline water molecules. The β-[MosO26] units link the sodium ion to form a chain structure. The infinitechains of [Na（Mo8O26）]^3- blocks are surrounded by protonized 4,4＇-bpy cations, 4,4＇-bpy and lattice crystalline water molecules. The 2D-IR correlation spectroscopy study indicates that the stretching vibrations of Mo=O occur more preferentially due to the thermal effect. The TGA analysis shows that compound 1 has high thermal stability.
