Studies On Process Optimazation And Properties Of Soy Protein Nano-Adhesive

Nowadays, the "three-formaldehyde" adhesives faced with the problem more and more outstanding since resources shortage and the threat of serious environmental pollution to human beings is aggravating. The soybean adhesive is gaining increasing attention because of its reproducibility and pollution-free. However, chemical modified soybean adhesive could not meet the demands of the wood adhesive industry market because of lower adhesive strength, water resistance and antiseptic properties. This research is focus on enhancing the properties of soy protein based adhesive by adding uniform dispersed nano-particles which poccess small size and large specific surface area effects.In this research, soy protein isolated was used as raw materials, and the adhesive, water resistance and antiseptic property of soybean adhesive were enhanced by adding the uniform dispersed nano-particles and modifiers.Nano-TiO2, SiO2and Al2O3were studied, respectively. As a result the uniform dispersed nano-particles were obtained by ultrasonic and chemical modification. The optimal dispersion conditions of three different kinds of nano-particles were confirmed with the single factor and L9(34)-orthogonal experiments. The dispersion conditions, such as the type and dosage of dispersion agent, of nano-particles modified with complex chemicals, such as micromolecular electrolyte, surfactant or macromolecular polymer were researched.The dosage of the nano-particles which were dispersed under optimal ultrasonic and chemical conditions was confirmed by the single factor experiment in order to enhance the adhesive and water resistance properties. The results show that the optimal dosage was0.8%nano-Al2O3, which was dispersed under optimal ultrasound conditions (ultrasound power500w,40℃,5h, pH6); The adhesive strength reached13.4MPa, which was increased88.3%compared with the adhesive without nano-particles; the wet strength reached3.7MPa, which was increased70.3%compared with the adhesive without nano-particles. Scanning electron microscope experimental showed the molecular of soybean based nano-adhesive and wood bonded tightly to realize the enhancement effectively.The effect of nano-particles on antiseptic property showed the antiseptic property was enhanced by adding nano-TiO2, SiO2, or Al2O3, and the optimal antiseptic property was obtained by adding0.8%TiO2. However, the antiseptic effect of nano particles was not better than commercial chemical preservative MB29. So choosing0.8%MB29as the preservative of nano-Al2O3soy adhesive, and the antiseptic mechanism of the MB29was to destroy the cell structure and restrain the development of microorganism was confirmed.The mechanisms of the nano particles on the enhanced properties of soy adhesive were researched by infrared spectrum. The infrared spectrum result of the interaction between nano-particles and soybean protein is there is no effect of nano-particles which was dispersed by ultrasonic or chemical method on the secondary structure of soybean proteins.Nano-particles were bonded with soybean protein tightly to enhance the pHysical effect.The optimum nano-Al2O3soy adhesive obtained in the research significantly enhances the properties of soybean adhesive, and poccess a broad application prospects.