Pyrolysis properties of lignin separated from four different kinds of wood （fir, larch, poplar, and eucalyptus） compared with commercial lignin were investigated using a thermogravimetric analyzer coupled to a...Pyrolysis properties of lignin separated from four different kinds of wood （fir, larch, poplar, and eucalyptus） compared with commercial lignin were investigated using a thermogravimetric analyzer coupled to a Fourier-transform infrared spectrometer（TG-FTIR）. Kinetic parameters of lignin thermal cracking reaction, such as activation energy and pre-exponential factor, were calculated using a three-dimensional diffusion model. The carbon residue rate and activation energy of softwood lignin were higher than those of hardwood lignin, showing that the decomposition of the former is relatively more dif？cult than that of the latter during pyrolysis. The distinct characteristic peaks of small-molecule gases and oxygenated chemicals such as ethers, phenols, acids, aldehydes, and alcohols were observed near the maximum weight loss rate by analyzing the 3D IR spectrum of the gas phase products. The formation routes of the main gaseous products were discussed, and the following order of releasing amounts was noted： CO2〉CH4〉H2O〉CO. It is believed that these results will provide valuable information for the thermo-chemical conversion process of lignin from the point of view of feedstock.展开更多
Lignin was extracted from peat by Sosa Method. In order to increase its chemical activity, it is necessary to make a structural modification by hydroxymethylation so it can be used in preparation of synthetic wood. De...Lignin was extracted from peat by Sosa Method. In order to increase its chemical activity, it is necessary to make a structural modification by hydroxymethylation so it can be used in preparation of synthetic wood. Depolymerization was made by two methods： （1） reaction oflignin with NaOH 2%; （2） exposition oflignin to UV beam for 6, 12, 24, 36, 48 and 60 hours. The best depolimerization result was with exposition of lignin to UV by 12 hours since phenylpropanoic structure with higher number of free positions （unoccupied carbons） in C3 and C5 of its aromatic ring was obtained. It is known by Mannich Reaction and determination of phenolic OH by UV analysis. Later, its reactivity was increased by hydroxymethylation process by means of reaction of depolymerizated product with formaldehyde and later with glyoxal since it is less toxic. The modified product was mixed with six different kinds of resins （phenol-formaldehyde, urea-formaldehyde, melamine-formaldehyde, Glyoxal-formaldehyde, urea-formaldehyde and melamine-formaldehyde） to obtain a better mechanical characteristic as a synthetic wood. The best result was the one with melamine-formaldehyde. Finally, this product was mixed with testa rice so final product showed a great hardness and a shinny and smooth appearance.展开更多
We investigated the role of GA3, uniconazole-P and IAA on tension wood formation, in particular the vessel features, in Fraxinu smandshurica seedlings. Ninety seedlings were used and treated with applications of GA3 a...We investigated the role of GA3, uniconazole-P and IAA on tension wood formation, in particular the vessel features, in Fraxinu smandshurica seedlings. Ninety seedlings were used and treated with applications of GA3 and/or IAA to the apical bud of the stem using a micropipette. Applications of GA3 or GA3 plus IAA with uniconazole-P strongly increased cell number of tension wood in comparison to that of no-uniconazole-P-applied, indicated that GA3 is more efficient than IAA on xylem cell production. Wood quality was also regulated by relative concentration ratio of GA3 to lAA, because of the vessel elements differentiation, density and size were controlled by GA3 and/or IAA on the different levels. These results suggested that the relative concentration ratio of GA3 to IAA and interactions of them are essential in regulating both wood quality and wood quantity, and tension wood formation in this species.展开更多
文摘Pyrolysis properties of lignin separated from four different kinds of wood （fir, larch, poplar, and eucalyptus） compared with commercial lignin were investigated using a thermogravimetric analyzer coupled to a Fourier-transform infrared spectrometer（TG-FTIR）. Kinetic parameters of lignin thermal cracking reaction, such as activation energy and pre-exponential factor, were calculated using a three-dimensional diffusion model. The carbon residue rate and activation energy of softwood lignin were higher than those of hardwood lignin, showing that the decomposition of the former is relatively more dif？cult than that of the latter during pyrolysis. The distinct characteristic peaks of small-molecule gases and oxygenated chemicals such as ethers, phenols, acids, aldehydes, and alcohols were observed near the maximum weight loss rate by analyzing the 3D IR spectrum of the gas phase products. The formation routes of the main gaseous products were discussed, and the following order of releasing amounts was noted： CO2〉CH4〉H2O〉CO. It is believed that these results will provide valuable information for the thermo-chemical conversion process of lignin from the point of view of feedstock.
文摘Lignin was extracted from peat by Sosa Method. In order to increase its chemical activity, it is necessary to make a structural modification by hydroxymethylation so it can be used in preparation of synthetic wood. Depolymerization was made by two methods： （1） reaction oflignin with NaOH 2%; （2） exposition oflignin to UV beam for 6, 12, 24, 36, 48 and 60 hours. The best depolimerization result was with exposition of lignin to UV by 12 hours since phenylpropanoic structure with higher number of free positions （unoccupied carbons） in C3 and C5 of its aromatic ring was obtained. It is known by Mannich Reaction and determination of phenolic OH by UV analysis. Later, its reactivity was increased by hydroxymethylation process by means of reaction of depolymerizated product with formaldehyde and later with glyoxal since it is less toxic. The modified product was mixed with six different kinds of resins （phenol-formaldehyde, urea-formaldehyde, melamine-formaldehyde, Glyoxal-formaldehyde, urea-formaldehyde and melamine-formaldehyde） to obtain a better mechanical characteristic as a synthetic wood. The best result was the one with melamine-formaldehyde. Finally, this product was mixed with testa rice so final product showed a great hardness and a shinny and smooth appearance.
文摘We investigated the role of GA3, uniconazole-P and IAA on tension wood formation, in particular the vessel features, in Fraxinu smandshurica seedlings. Ninety seedlings were used and treated with applications of GA3 and/or IAA to the apical bud of the stem using a micropipette. Applications of GA3 or GA3 plus IAA with uniconazole-P strongly increased cell number of tension wood in comparison to that of no-uniconazole-P-applied, indicated that GA3 is more efficient than IAA on xylem cell production. Wood quality was also regulated by relative concentration ratio of GA3 to lAA, because of the vessel elements differentiation, density and size were controlled by GA3 and/or IAA on the different levels. These results suggested that the relative concentration ratio of GA3 to IAA and interactions of them are essential in regulating both wood quality and wood quantity, and tension wood formation in this species.
