以普通酚醛树脂(PF)和戊二醛改性的酚醛树脂(PFG)作为大豆蛋白胶粘剂的改性剂。研究结果表明:PF和PFG都能显著提高大豆蛋白胶粘剂的胶合强度和耐水性能,后者具有较低的游离甲醛和游离苯酚,是一种相对环保的酚醛树脂,更适宜做大豆蛋白胶粘剂的改性剂。2者具有类似的主体结构,后者由于具有较高韧性使其改性的大豆蛋白胶粘剂具有较高的机械强度和耐水性,但改性后大豆蛋白胶粘剂的固化温度高于PF改性后的大豆蛋白胶粘剂的固化温度。模型化合物反应表明酚醛树脂改性大豆蛋白胶粘剂时,发生共缩聚反应的位点更可能发生在蛋白质的支链型氨基上。
The related reactions and their mechanism of model compounds of urea formaldehyde resin in alkaline environment were studied by electrospray ionization mass spectrometry (ESI-MS). The results indicate that the process of urea hydroxymethylation is reversible, and the formation of tetrahydroxymethyl-urea probably appeares under the alkaline condition. The formations of ether bond (-NRCH2OCH2NR) and bridge bond (-NRCH2NR-) are competitive reactions, and the mass charge ratio peaks of 215, 245 and 275 on the ESI-MS spectra mainly belong to the ether bonds, and the peaks of 227 and 257 correspond to the bridge bonds structure. The temperature has little effect on the distribution of the final structures.