Data of RSOS-202227. Wet shear strength, Apparent viscosity, Solid content，SEM, FTIR and TGA results of  the PPI, arachin and conarachin-based adhesives.

To lay theoretical basis for the preparation of peanut protein-based adhesives and promote the sustainable development of adhesive industry, properties of peanut protein isolate (PPI), arachin and conarachin-based adhesives modified by urea and epichlorohydrin (ECH) were investigated under different urea concentrations.

When the urea concentration was 2 mol/L, the wet shear strength of the PPI-based adhesive was 1.24 MPa with the best water resistance. With the increase of urea concentration from 0 to 4 mol/L, the apparent viscosity of the PPI-based adhesive increased from 3.87 Pa·s to 136.80 Pa·s and the solid content increased from 18.11% to 31.11%. Compared with conarachin-based adhesive, the properties of arachin-based adhesive were improved more obviously during the combined modification.

Scanning electron microscopy images illustrated that when the urea concentration was 2 mol/L, the surface of the PPI-based adhesive was more compact and smoother, which was beneficial to the improvement of water resistance and related to the structure changes of arachin and conarachin components. Fourier-transform infrared spectroscopy results indicated that different urea concentrations caused the change of ester and ether bonds in the PPI-based adhesive, which was mainly related to arachin component. Thermogravimetry results suggested that when the urea concentration was 2 mol/L, the decomposition temperature of protein skeleton in the PPI-based adhesive reached a maximum of 314 °C exhibiting the highest thermal stability. The improvement of the thermal stability of conarachin was greater than that of arachin during the combined modification.

I0-I4: 20 g PPI and 100 mL urea solution (0, 1, 2, 3, 4 mol/L) were added into the reaction vessel (condensation tube, thermometer, magnetic rotor) respectively, and stirred at 50 °C for 1 h. Then, 6 wt% ECH (according to the total adhesive mass) was introduced and the resulting slurry was stirred at 50 °C for 1 h. After cooling, the modified PPI-based adhesive I0, I1, I2, I3 and I4 were prepared respectively.

A0-A4: 20 g arachin and 100 mL urea solution (0, 1, 2, 3, 4 mol/L) were added into the reaction vessel (condensation tube, thermometer, magnetic rotor) respectively, and stirred at 50 °C for 1 h. Then, 6 wt% ECH (according to the total adhesive mass) was introduced and the resulting slurry was stirred at 50 °C for 1 h. After cooling, the modified arachin-based adhesives A0, A1, A2, A3 and A4 were prepared.

C0-C4: 20 g conarachin and 100 mL urea solution (0, 1, 2, 3, 4 mol/L) were added into the reaction vessel (condensation tube, thermometer, magnetic rotor) respectively, and stirred at 50 °C for 1 h. Then, 6 wt% ECH (according to the total adhesive mass) was introduced and the resulting slurry was stirred at 50 °C for 1 h. After cooling, the modified conarachin-based adhesives C0, C1, C2, C3 and C4 were prepared respectively.