高温对结构加固用环氧黏结剂力学性能的影响

采用带高低温箱的电液伺服测试系统及动态力学分析仪,在不同温度下针对4种环氧黏结剂进行准静态拉伸及动态力学性能试验,研究了环氧黏结剂静动态力学性能的温度影响规律及其耐高温性能评价方法.结果表明:黏结剂的应力-应变曲线形态随温度变化显著,呈现出4种演化形态;随着温度的升高,黏结剂的强度及抗变形能力降低,储量模量在玻璃转变区间范围内发生2~3个数量级的退化;4种黏结剂的玻璃转化温度及热变形温度均呈现Araldite 2014>Calle1>Sika30>Araldite 420的规律;采用柔性链段和核/壳结构聚合物增韧改性的Calle1黏结剂在55~70℃下的强度与应变能最高;黏结剂在切线法玻璃转化温度附近仍具有51%以上的模量剩余比,由C法得到的热变形温度与切线法玻璃转化温度较为接近,采用上述2种方法确定黏结剂最高工作温度偏安全.

Effects of High Temperatures on Mechanical Properties of EpoxyAdhesives for Structural Strengthening

Quasi static tensile tests for four types of epoxy adhesive were conducted in the electro-hydraulic servo test system with environmental chamber,and dynamic mechanic performances were tested by dynamic thermal mechanical analyzer.The thermal effects on the static and dynamic mechanical properties of epoxy adhesives were studied,and the evaluation methods for the high temperature resistance were discussed.The results show that the stress-strain curve of the adhesives changes significantly under different temperatures and exhibits four morphological shapes.With the temperature increase,the strength of the adhesive and deformation resistance ability falls sharply,and the storage modulus degrades by 23 orders of magnitude in the glass transition interval.The glass transition temperatures and thermal deformation temperatures exhibit the same relationship:Araldite 2014>Calle1>Sika 30>Araldite 420.The strength and strain energy of the adhesive Calle1 toughened by flexible segment and core/shell structure polymers are the highest at 5570℃.The glass transition temperature obtained by the tangential method has a residual modulus ratio of more than 51%.The thermal deformation temperatures obtained by method C are close to that of the tangential method,and the maximum working temperatures of the adhesive obtained by the two methods are safer.