新型酚醛树脂改性大豆蛋白基胶黏剂的研究

摘要

Soy-based adhesive (S) was prepared by use of defatted soy flour as feedstock,and new phenol formaldehyde resins were synthesized by using common formaldehyde and high concentration formaldehyde ( PF1 , PF2 ) as crosslinker agent. S and PF1 ,or PF2 were then directly blended to form the modified S. The structure and the performance of these adhesives were subsequently characterized by differential scanning calorimetry ( DSC) ,infrared spectrum ( FT-IR) ,dynamic thermal mechanical properties ( DMA) and nuclear magnetic resonance ( 13C NMR) ,respectively. It was found that with the same molar ratio,plywood of S crosslined by PF2 showed better bonding performance and strength stability. Their dry and wet strengths increased by nearly 4. 3% and 11. 6% compared with those crosslined by PF1 ,respectively. Dynamic DSC analysis showed that PF2 was easy to react with S by decreasing the activation energy of adhesives system. 13 C NMR showed that the hydroxymethyl content PF2 system was 88. 73%,which was significantly higher than the 80. 91% of PF1 . FT-IR analysis confirmed that the phenol formaldehyde resin reacted with amino of S, and PF2 showed much more efficient than PF1 . The DMA results showed that PF2 could improve the mechanical performance and thermal stability of the final product,reduce the onset curing temperature and curing temperature,and accelerate the curing reaction rate of modified S.%以脱脂大豆粉为原料制备大豆蛋白基胶黏剂(豆胶,S),以普通甲醛制备的酚醛树脂( PF1)和高浓度甲醛制备的酚醛树脂( PF2)为交联剂,使用前将两者直接混合得酚醛树脂改性豆胶(PF1/S、PF2/S)。利用差示扫描量热(DSC)、红外光谱(FT-IR)、动态热机械性能(DMA)和核磁共振碳谱(13C NMR)分析对产品性能进行了测试与表征。结果表明：等物质的量之比条件下,高浓度甲醛较之普通甲醛制备的酚醛树脂改性豆胶胶合板干、湿剪切强度分别提高4.3%和11.6%,并且强度稳定性好；动态DSC分析表明,PF2可以降低豆胶体系的固化温度和活化能,与豆胶的交联反应较容易；13C NMR分析表明,PF2体系羟甲基达88.73%,明显高于PF1的80.91%；FT-IR分析证实酚醛树脂与豆胶中的氨基发生反应,并且PF2反应效率更高；DMA分析表明,PF2/S能够改善胶合产品的力学性能和热稳定性,降低豆胶的固化反应起始温度,提高固化反应速率。