中文摘要：

以麦草为研究对象,进行了常规烧碱-蒽醌法蒸煮。采用酶解-弱酸解两段法分别从原料和纸浆中分离出原料木素和纸浆残余木素;采用酸析法从黑液中分离出溶出木素试样,经弱酸解得到提纯的木素试样。通过凝胶渗透色谱（GPC）对所有的木素试样分别进行分子质量检测,得出各种木素的分子质量分布及变化,并对其进行了分析对比。结果表明,随着蒸煮的进行,麦草纸浆残余木素的平均分子质量先增大后减小,升温后期和保温初期是造成木素平均分子质量降低的主要阶段;黑液中溶出木素的平均分子质量则逐渐增大。

英文摘要：

The wheat straw was used as the raw material in this research.Conventional soda-anthraquinone cooking was carried out.Different lignin samples were isolated from the raw material and the pulps by using the two-stage method of enzyme-mild acidic hydrolysis solution.The acid-precipitating method was used to isolate the dissolved lignin from the black liquor and the crude lignin was purified by mild acidic hydrolysis.All of the lignin samples were tested by GPC,and the changes of molecular weight of the lignin were studied and compared.It was found that the residual lignin molecular weight increased at first and then decreased,while the dissolved lignin molecular weight increased with increasing cooking time.Furthermore,the residual lignin molecular weight was higher than the dissolved lignin in various stages of cooking,which illustrated that the lignin was dissolved in the form of debris.