Composite modified starch-based adhesive with high adhesion and zero aldehyde

In this paper, a high adhesion and zero aldehyde starch-based adhesive was reported to replace the traditional urea-formaldehyde adhesive. The adhesive was prepared by polycondensation reaction of the aldehyde group of the oxidized starch and the amino group of urea. Then, konjac glucomannan (KGM), milk protein (MP) and Glycidyl methacrylate (GMA) were combined to modify the prepared adhesive. Thus, the issues of free formaldehyde emission of urea-formaldehyde adhesive and poor water resistance and adhesion of starch adhesive were fundamentally solved. Through a series of study of process conditions and tests, the adhesive had excellent comprehensive performance with the viscosity of 2200 mPa·s, the water resistance time of 50.0 d, the dry shear strength of 3.20 MPa and the wet shear strength of 1.81 MPa when the total mass of modifier was 17.7 (wt% U-OSt). The morphology, molecular structure, crystalline structure, elemental analysis, thermal conversion behaviours of the adhesive were characterized by Scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), Solid-state nuclear magnetic resonance (NMR), X-ray diffffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA).