魔芋粉-壳聚糖-聚乙烯醇共混胶黏剂的结构表征

Structural characterization of konjak powder-chitosan-PVA blending adhesive

为了拓宽魔芋粉的应用领域,开发环境友好型木材胶黏剂,在前期研究基础上,笔者进一步探讨了胶黏剂的胶合机理和工业化的可行性:通过红外光谱(FTIR)对共混胶的分子间的相互作用以及胶接界面进行了微观结构分析;借助X-射线衍射(XRD)辅助探讨了葡甘聚糖(KGM)、壳聚糖(CA)、聚乙烯醇(PVA)3种纯物质和三元共混胶黏剂的微观结构中官能团的变化;同时利用原子力显微镜(AFM)直观的观察分析胶膜结构,揭示了三元共混胶黏剂的胶合机理;经过成本估算并与市售胶黏剂比较,对其应用于工业生产进行了可行性分析。结果表明:FTIR和XRD分析发现3种高分子之间存在着氢键等强烈的相互作用,并且发现胶黏剂中的活性基团与杨木中的纤维素和半纤维素上的羟基发生了作用,从而得到胶黏剂与界面之间也有强烈作用;AFM分析表明通过PVA的加入,明显改善了以前的双螺旋结构,因此也有效地提高了耐水性能;前景分析表明该胶具有易于形成工业化生产的特点,其制备工艺与白乳胶相似,能够适应白乳胶的生产设备。以上研究结果为探索生物质环保胶黏剂提供了参考。

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.