有机蒙脱土改性脲醛树脂胶黏剂的制备及结构表征

Preparation and Structure Characterization of UF Resins Modified with Organic Montmorillonite

采用"碱-酸-碱"合成工艺,在各阶段将OMMT(有机蒙脱土)投入反应体系,制备有机蒙脱土改性脲醛树脂胶黏剂,测试胶黏剂的各项性能,用XRD(X射线衍射仪)、FTIR(傅里叶变换红外光谱)、SEM(扫描电镜)、TG(热重分析)对改性胶黏剂结构进行表征.实验结果表明,随着OMMT的加入,胶黏剂的游离甲醛含量降低,胶合强度增加.第一阶段投入OMMT,降醛效果明显,第二阶段投入OMMT,补强效果明显.SEM图显示,改性胶黏剂中被剥离成片层状的OMMT因受基体的包覆或挤压,呈现出蜷曲的形状;XRD图谱显示,OMMT/UF胶黏剂的结晶度低于UF胶黏剂的结晶度,有机蒙脱土的加入,破坏了脲醛树脂中羰基和氨基的规整性排列;FTIR图谱表明,改性脲醛树脂胶黏剂中存在大量游离的尿素,胶黏剂的游离甲醛含量低;TG分析得出,改性胶黏剂的TG曲线移向高温方向,材料的热分解温度提高.

The organic montmorillonite （OMMT） modified urea-formaldehyde （UF） resin adhesives were prepared by base-acid-base synthetical technology and adding OMMT to the different stage of the synthesis. The technical characteristics of adhesives were tested. The structure of the sample was characterized by X-ray diffraction, infrared spectroscope and scanning electron microscope. The thermal property was measured by thermogravimetric analysis. The results indicated that with the addition of OMMT,the free formaldehyde content in adhesives decreased and the bonding strength increased. And the OMMT added had obviously decreasing aldehyde effect at the first stage and obviously reinforcing effect at the second stage. The SEM results indicated that the sheet structure of the OMMT in the modified adhesive showed a curled shape due to the matrix covered or squeezed. The XRD results indicated that the crystallinity of OMMT/UF adhesives was lower than that of UF adhesives,which suggested that the arrangement regularity of the carbonyl and amino groups in UF resin adhesives was destroyed because of the introduction of the OMMT. The FTIR results indicated that there were a lot of free urea and low content of free formaldehyde in the modified UF resin adhesive. The TG results indicated that the TG curve of the modified resin adhesive moved to higher temperatures, and the thermal decomposition temperature increased.