Synthesis and Properties of Bio-based Adhesives Derived from Plant Oil Residues

Cottonseed oil residue (COR) is a by-product of cottonseed extracted by prepressing or direct solvent extraction. The protein content of COR can reach 50% and higher, but it has not been effectively utilized. In this study, bio-based adhesives were synthesized from COR, maleic anhydride, and urea. The obtained adhesives were then analyzed by Fourier transform infrared (FTIR) and Thermogravimetric (TG), and tested as wood composite panel binders. The results indicated that the optimal synthesis conditions of the modified COR adhesive were: the urea concentration was 2 mol/L, the maleic anhydride content was 6%, and the reaction temperature was 70°C. Infrared spectrum revealed a new characteristic peak appeared at 2216 cm-1, which indicated that the protein in cottonseed reacted with maleic anhydride to form a stable structure, which improved the water resistance of the adhesive. The TG curve of maleic anhydride/urea modified COR adhesive showed that the peak value of the adhesive shifted back in the second and third stages, which indicated that the modified adhesive had better thermal stability and improved water resistance than those of unmodified ones. The study results could provide a theoretical basis and scientific guidance for the appropriate processing method and application technology development of COR.