Study on Modified Soybean Meal Adhesive for Pressing Straw Board

Using the modified soybean meal adhesive to press straw board can effectively alleviate the shortage of wood resources. The effects of sizing amount, hot pressing time and hot pressing temperature on the main physical and mechanical properties of the straw board pressed with different formulations of modified soybean meal adhesive were investigated by orthogonal experiment, and the static bending strength and internal bonding strength of straw board were tested. The viscosity of soybean paste adhesive modified by vinyl acetate emulsions was determined by rotating viscometer. The results showed that the viscosity of modified soybean meal adhesive was in the range of 3000–8000 mPa∙s. When the sizing amount is 30%, the static bending strength and internal bonding strength of the rice straw particleboard are 14.23 MPa and 0.43 MPa respectively when the size of rice straw particleboard is in the range of 1.0–20 mm. The strength of the rice straw particleboard meets the requirements of GB/T 21723—2008. The contact angle was measured by measuring angle method. After sizing, the contact angle of straw decreased significantly, which indicated weakened hydrophobicity of the straw. The wettability of rice straw increased significantly after sizing, which indicated that rice straw shavings could bonding effectively with each other.