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
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.
