| The content of lignin is lower than that of cellulose in botanic field, it is natural organic macromolecule and covers 15% to 36% of the botanic body. It is three-dimensional network macromolecule with c-c bond and ether bond and its basic structural unit is phenyl propane structure unit, so Lignin macromolecular structure is very complicate. It can be the same energy materials and chemical materials as petroleum because of its phenyl characteristic, aliphatic characteristic in side-chain and a variety of functional groups. Lignin is the byproduct in papermaking industry, its valid utilization can decrease environmental pollution and it is good to treat pulping waste liquor. On the other hand, it can develop and utilize regenerative resources, solving resources waste problem.It is studied that lignin substituting some expensive chemical materials synthesizes macromolecular materials, developing valid utilization of lignin. it has profound social and economic meaning.Firstly, it is studied that the chemical structures and thermal properties of wheat straw Soda-AQ alkaline lignin and oxygen alkaline lignin by IR spectrum, UV spectrum, 'H-NMR , 13C-NMR, DSC and TGA. Wheat straw lignin is guaicyl-syringyl lignin, and it has a little p-hydroxyphenyl unit. Wheat straw Soda-AQ alkaline lignin has more phenolic hydroxyl, so it is advantageous to synthesize lignin-based phenol formaldehyde resin (LPF). Wheat straw oxygen alkaline lignin has more alcohol hydroxyl, so it is advantageous to synthesize lignin-based polyurethane (LPU). The glass transition temperature difference between the two lignins is not significant, thefastest weight loss temperatures of purified lignins are higher than crude lignins.The lignin-based phenol formaldehyde resin(LPF) is synthesized with commercial lignin (wheat straw Soda-AQ alkaline lignin) substituting expensive phenol and the effects of lignin in LPF resin on resin properties and its application in plywood industry are studied. The properties of LPF adhesives prepared with Commercial alkaline lignin, purified commercial alkaline lignin, modified commercial alkaline lignin, wheat straw oxygen alkaline lignin and commercial masson pine KP lignin, are worse than those of phenol formaldehyde resin adhesive, but they can meet Grade one plywood production requirements. The better condition is the ratio of lignin substituting phenol is under 40% and phenol to formaldehyde ratio is about 1:1.5, and it is good to environmental protection. The glass transition temperature of LPF increases with adding lignin in LPF resin, but it is not significant. The effect of adding lignin on hot press solidifying is not significant, but the fastest weight loss temperature of LPF decreases, increasing LPF thermal instability. Synthesizing LPF with lignin substituting phenol can decrease the resin cost, its economic effectiveness is obvious.The effects of the adhesive prepared with PF resin and hydroxymethylate lignin on adhesive properties are studied. The best application conditions are the pressure is 14kg/cm2, the dosage is 240g/cm2(double side), hot pressuring time is 4 min, temperature is 150@.The bond quality can reach the GB requirements, meeting Grade one plywood production.The effects of the adhesive prepared with urea formaldehyde (UF) resin and hydroxymethylate lignin on adhesive properties are studied.The good quality lignin-based UF can be prepared with wheat straw Soda-AQ lignin, wheat straw oxygen alkaline lignin, masson pine KP lignin which are modified through hydroxymethylate reaction. Under 30% modified lignin content, the adhesive bond quality reach the GB requirements, meeting Grade two plywood production.The lignin-based polyether polyurethane(PU) is synthesized with wheat straw oxygen alkaline lignin and modified wheat straw oxygen alkaline lignin, its properties are increased through adding plasticizer (DBF). It is discovered that its glass transition temperature and young's modulus are very high, the tensile strength is slightly high, the tensile stretch is low,...
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