【摘要】 为揭示淀粉复合变性前后羟基与水分子对异氰酸酯基反应几率的变化、淀粉基API木材胶粘剂贮存稳定性改善的本质及聚异氰酸酯对淀粉复合变性前后交联固化程度的影响,文中采用化学分析光电子能谱(ESCA)分析聚异氰酸酯(PMDI)与淀粉基试样反应产物的结构,考察淀粉含水率变化对产物结构的影响。结果表明,PMDI与淀粉基试样在130℃等温条件下反应30 min,随原料淀粉基试样含水率的提高,产物中的羰基含量降低,氨基甲酸酯与取代脲之比增高。经分析产物表面及内部羰基含量的差异,证明PMDI更易与复合变性淀粉反应,生成极性更强的氨基甲酸酯,利于木材的胶接。更多还原

【Abstract】 The storage stability and crosslink curing degree of modified starch based-API wood adhesive have been improved compared with conventional starch-based adhesive.To reveal its essence,ESCA was adopted to characterize structural properties of the products of PMDI reacted with starch-based samples for 30 min at constant temperature of 130 ℃.The effect of water content of the starch reactants on product structures was investigated.The results show that the content of carbonyl decreases and the ratio of carbamic ester to substantial-urea increases when there is an increase in water content of the starch reactants.By analyzing the difference of carbonyl contents between the surface and the interior of the product samples,it can be concluded that PMDI is easier to react with the modified starch into the interior and to form carbamic ester,which is convenient to bond wood material.更多还原