Structural characterization of konjak powder-chitosan-PVA blending adhesive

Abstract: The use of formaldehyde-based adhesives might contaminate the environment and cause damage in health of workers and consumers. Therefore, the development of non-toxic adhesives from renewable biomass has aroused significant interest. In order to broaden the application of Konjak powder and develop environment-friendly wood adhesive, the author investigated the mechanism of adhesion and the feasibility of industrialization more deeply on the basis of the article "Properties and bonding mechanism of konjak powder - chitosan-PVA blending adhesive," which affirmed bonding strength of the adhesive. (1) Microstructure on intermolecular interactions of the blending adhesive and the interface adhesion of poplar veneer were investigated by using Fourier Transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) was used to investigate the changes of functional groups in the microscopic structure of Konjac Glucomannan (KGM) / Chitosan (CA) / Polyvinyl alcohol (PVA) three pure substances and the blending adhesive. The results showed that: There was a strong interaction of hydrogen bonds between the three kinds of polymers. The active group of the adhesive interacted with the hydroxyl groups on the cellulose and hemicellulose of poplar veneer. Therefore, it was showed that there was a strong role between the adhesive and the interface. (2) Film structure was observed by Atomic force microscopy (AFM) to reveal the bonding mechanism of the adhesive. The result showed that: The interface between adhesive and poplar veneer wall, and the surface of adhesive film was dense. The molecular chain of binary blends laminating adhesives presented an appearance of a spiral chain structure. These sugar chains on the gap of the double helix structure were free and movable, and could maintain large amounts of water to cause binary blends laminating adhesives dissolve in water easily. This was the main reason for the poor water resistance of binary blends laminating adhesives. Ternary blends laminating adhesive film has a flat, smooth surface morphology, therefore, it was showed that blending the three kinds of polymer materials acheived good compatibility. Adding PVA improves the structure of the double helix and improves the water resistance performance significantly. (3) Based on the cost estimates and compared with commercially available adhesives, the feasibility of using this adhesive in industrial production was analyzed. The feasibility analysis showed that this adhesive had the characteristics of the industrial production, and the production process was similar to the one of the white latex. Therefore, this adhesive was able to adapt to the production equipment of the white latex. These conclusions provide an important theoretical basis for accelerating the process of development of wood adhesives, and establishing and improving the preparation process and hot conditions of the adhesive. The ternary blends adhesive had excellent water resistance. It had the development and application prospects in the field of biological materials and the processing of agricultural products. The aim of study on wood properties of interface and adhesive was to deepen the understanding of the mechanism of wood adhesive. This paper had a more realistic guiding significance for studying adhesion properties, and provided the ideal raw material for development to the direction of high-grade of the wood industry. This adhesive was a new generation of environmentally friendly high-quality products.