利用强碱性降解大豆蛋白制备木材胶粘剂及其表征

Preparation and Characterization of Wood Adhesives with Strong Alkali-Degraded Soybean Proteins

采用凝胶渗透色谱(GPC)和差示扫描量热(DSC)分析等手段结合胶合板压制,对在90℃和9%(质量分数,下同)氢氧化钠存在下降解大豆蛋白及其与乙二醛、UF树脂和MF树脂共混制得的复合胶粘剂进行表征,结果表明,降解使大豆蛋白的大分子肽链断裂,高级结构破坏,得到在分子量在282～3404之间、适于制备木材胶粘剂的低黏度产物;随着降解时间延长,产物中大分子量组分含量和黏度逐渐降低,但甲醛反应性能力明显增加;DSC测试表明降解大豆蛋白能够与乙二醛、脲醛(UF)树脂、三聚氰胺-甲醛(MF)树脂等发生交联固化反应;由降解大豆蛋白制备的各种复合胶满足室内普通胶要求,而只有含MF树脂的复合胶可达到耐水胶要求。

The techniques of gel permeation in chromatography（GPC） and differential scanning calorimetry （DSC） and plywood evaluation were employed to characterize the degraded soybean proteins （DSP）（treated in the presence of 9% sodium hydroxide at 90 ℃ for 2 hours～3.5 hours） and the wood adhesives by blending DSP with glyoxal,urea-formaldehyde （UF） resin or melamine-formaldehyde （MF） resin.The results indicates that the strong-alkali degradation destroyes completely the advance structures of protein and results in the chain cleavages of the larger-molecular polypeptide,thus a low-viscosity DSP solution is obtained,this sdution is suitable for preparing wood adhesive with molecular weight ranged from 282 to 3404.DSC analysis confirms that the DSP can be crosslinked by glyoxal,UF resin or MF resin.All blends of DSP with glyoxal,UF resin or MF resin can be used as non-water-resistant adhesive,but only the DSP/MF blends can be used as water-resistant adhesive.