Study On Modification Of Whey Protein Adhesive With Phenol Formaldehyde Oligomer

Whey is a by-product from cheese processing, which has not been utilized extensively. Thus the value-added applications of whey and whey protein effectively are obtaining more and more attentions. This paper is going to develop a water resistant and environmentally safe adhesive for plywood manufacture using whey protein via the modifications of phenol formaldehyde oligomer.In order to improve the bond property of whey protein adhesive, whey protein was originally subjected to thermal denaturation for unfolding the compact globular structure and the optimal denaturing conditions were obtained based on the viscosity tracing and bond evaluation. Thereafter, the synthetic method of phenol formaldehyde oligomer for modifying whey protein adhesive was optimized by means of chemical analysis, differential scanning calorimetry as well as high performance liquid chromatography. The effects of formulations of formaldehyde scavenger and polyvinyl alcohol on the pot life, bond strength, water resistance and environmental safety of phenol formaldehyde oligomer-modified whey protein adhesive were investigated, by which the post treatment of phenol formaldehyde oligomer was optimized. Finally, the modified whey protein adhesive was evaluated by plywood evaluation, Fourier transform infrared spectroscopy and scanning electron microscope, respectively.According to the standards of ASTM D906-98and JIS K6806-2003, the modified whey protein adhesive had a dry-state bond strength of2.29MPa and a28h dry-boiling-dry wet strength of1.98MPa which were much higher than that of unmodified adhesive, indicating that the modified whey protein adhesive has good potential for structural applications. The formaldehyde emission of optimized adhesive determined according to JIS A1460:2001standard was0.149mg/L that is lower than the required value of F☆☆☆☆grade. And the residual phenol was not detectable in cured adhesive by high performance liquid chromatography.This study provides a new application of whey protein with higher added value by preparing a water-resistant and environmental safe plywood adhesive for structural use.