氧化木薯淀粉改性MUF树脂的性能与固化特征

Properties and curing characteristics of melamine-urea-formaldehyde resin modified with oxidized cassava starch

通过在三聚氰胺-尿素-甲醛树脂(MUF)合成反应的不同阶段添加氧化木薯淀粉,制备得到了不同系列树脂,分别为MUF0、MUF1和MUF2,并对其基本性能及粘接强度进行了测试和分析。为了进一步了解氧化木薯淀粉对MUF树脂固化反应的影响,借助差示扫描量热分析仪(DSC)对树脂在不同升温速率条件下的固化特征参数及固化行为进行了表征。结果表明,在合成反应不同阶段加入氧化木薯淀粉,可有效提升树脂的粘接性能并降低树脂中的游离甲醛含量,特别是在树脂合成反应的第3阶段进行添加,效果更为显著。利用Kissinger方程对不同树脂的固化动力学参数进行分析,得到了树脂固化反应的表观活化能E a,表观频率因子A和反应级数n,并建立了固化反应动力学模型。在本试验条件下,树脂经过氧化木薯淀粉改性后,虽然固化所需活化能有不同程度的提高,但可形成更高的粘接强度。

Various MUF resins , namely MUF0 , MUF1 and MUF2, were prepared by adding the oxidized cassava starch at the different stages of resin synthesis, and the basic properties and bonding strength of the resins were tested and analyzed. In order to learn the effects of oxidized cassava starch on resins curing performance, differential scanning calorimeter (DSC) was employed to obtain the character parameters of resins in the condition of different heating rates and explore the curing behavior. The results showed that the resins performance was improved by adding the oxidized cassava starch, the bonding properties was increased and the freee formaldehyde content in the resins decreased, especially the results were more excellent when the oxidized cassava starch was added at the third stage of resin synthesis. By using Kissinger equation, the curing kinetic parameters were analyzed,and the apparent activation energy Ea, apparent frequency factor A and reaction order n were obtained. The curing reaction kinetics model was established. In this work, the resin modified with oxidized cassava starch had higher bonding strength although its reaction activation energy was higher than that of the pure MUF resin.