用红外光谱法研究麦秸各层面的化学组成

本文以麦秸为例 ,用红外OMNI采样器研究了麦秸各层面红外光谱的差异 ,并进一步研究了麦草表面在不同的处理条件下 ,表面化学成分的变化规律。实验结果表明 :麦秸表面聚积着大量的SiO2 (～ 1 0 70cm- 1 ～ 80 0cm- 1 ) ,麦秸表皮层脂类物质含量高 (νCO =1 733cm- 1 )。麦秸表面的羟基 (～ 330 0cm- 1 )物质很少。麦秸的中层和内层主要是木素 ( 1 731 ,1 65 0 ,1 5 95 ,1 5 0 5 1 ,1 45 5 ,1 42 5 ,1 2 34,1 0 39和 835cm- 1 )和纤维素类物质 ( 335 0 ,2 935 ,2 85 0 ,1 65 0 ,1 45 5 ,1 430 ,1 367,1 31 7,1 1 60 ,1 0 34和 891cm- 1 )。木素的含量由外向里逐渐减少。麦秸表面的SiO2 是人造板制造中麦草不易粘接的主要原因。用热水处理后 ,表面仅有部分简单的碳水化合物和少量脂类物质溶出 ,而用NaOH处理麦草 ,可使表面的脂类物质和SiO2 溶出 ,便于人造板加工。

FTIR Studies on the Chemical Composition of Wheat Straw in Different Layers

The differences of chemical composition in various layers of wheat straw were studied by infrared spectroscopy with OMNI sampler. The dependence of surface chemical composition of wheat straw on the processing methods was also studied. The results show that there is large amount of SiO2(-1,070 cm-1, -800 cm-1) in the surface of wheat straw. The out layer contains large amount of non-aromatic esters(nu c-o = 1,733 cm-1). There is few OH-containing (-3,300 cm-1) on the surface. The lignin(1,731, 1,650, 1,595, 1,505, 1,455, 1,425, 1,234, 1,039 and 835 cm-1) and cellulose(3,350, 2,935, 2,850, 1,650, 1,455, 1,430, 1,367, 1,317, 1,160, 1,034 and 891 cm-1) are the main species in the middle and inner layers of wheat straw. The large amount of surface SiO2 is mainly responsible for the poor adhesive property in the manufacture of the man-made board. Only a small amount of hydrocarbon and non-aromatic esters is dissolved out when treating the wheat straw with hot water, however, the aqueous NaOH treatment may make esters and SiO2 dissolved out, and then the processing of the man-made board becomes praticable.