乙酰化半纤维素对涂料成膜的粘结性能的影响

Acetylated Hemicellulose as Binder in Coating Films

从云杉经热水抽提出的聚半乳糖葡萄糖甘露糖(GGM),通过不同程度乙酰化反应后获得乙酰基低取代度和高取代度的半纤维素,并用于涂料中作为连接料替代部分丁苯胶乳。以乙酰化的半纤维素(或者淀粉)、碳酸钙和丁苯胶乳制备的涂料涂布于基层上得到涂料膜。用力学性能测试和SEM观察对涂料膜的表面粘结性能进行了分析。结果表明添加GGM和乙酰化GGM提高了涂料膜的抗拉应力和杨氏模量,但是降低了其断裂伸长率。和淀粉相比,低乙酰度GGM提高膜的抗拉应力和杨氏模量更高,降低断裂伸长率更多。低乙酰度的GGM和GGM相比,低乙酰度的GGM提高了膜的抗拉应力和断裂伸长率。低乙酰度的GGM虽然相对分子质量不够高,但是在膜中仍表现出一定的粘结性能,在未来可能以其生物相容性部分取代丁苯胶乳获得使用。

Galactoglucomannans （GGMs） extracted from Norway spruce by hot water were acetylated to form the products in low and high acetylation and used as a co-binder in pigmented coatings for partly substituting synthetic polymer latex. Acetylated GGMs were mixed with calcium carbonate mineral pigment and styrene-butadiene latex as coating color, and the mixture was cast to films. The strength properties of the films were characterized with mechanical testing, and the microstructure of binding was observed by scanning electron microscopy. The addition of GGM and acetylated GGMs increased the tensile strength of films, but the strain at break dropped significantly. Compared to starch,the low acetylation GGM presented improved tensile strength and Young＇s modulus, as well as reduced strain at break. The low acetylation GGM resulted in higher tensile strength and strain at break than the native GGM. It is interesting that GGMs, despite their low molecular weight and low degree of polymerization, showed some binding abilities in pigmented coatings, which would be useful for partial substitution of styrene-butadiene latex binder.