Xu Jie, Yang Jiayao, Liu Xiaohuan, Wang Hengxu, Zhang Jingjie, Fu Shenyuan
Zhejiang Provincial Collaborative Innovation Center for Bamboo Resources and High-efficiency Utilization, 666 Wusu Street, Hangzhou 311300, People's Republic of China.
School of Engineering, and Key Laboratory of Wood Science and Technology of Zhejiang Province, Zhejiang A&F University, 666 Wusu Street, Hangzhou 311300, People's Republic of China.
R Soc Open Sci. 2018 Aug 15;5(8):180566. doi: 10.1098/rsos.180566. eCollection 2018 Aug.
At present, the disadvantage of powder epoxy adhesive is the limited application area. In order to widen the application range of powder epoxy adhesive from heat-resistant substrates (such as metals) to heat-sensitive substrates (such as plastic products, cardboard and wood), it is necessary to decrease the curing temperature. In this article, a series of fast-curing powder epoxy adhesives were prepared by the melt blending method with bisphenol A epoxy resin (E-20), hexamethylenetetramine (HMTA) as a curing agent and 2-methylimidazole (2-MI) as an accelerant. The structure and properties of the E-20/HMTA/2-MI systems were characterized by Fourier transform infrared, thermogravimetric analysis, dynamic mechanical analyser and differential scanning calorimetry (DSC). 2-MI added into the E-20/HMTA systems can simultaneously enhance toughness, tensile strength, glass transition temperature () and thermal stability in comparison with the E-20/HMTA systems. The best mechanical properties were obtained at 100/8/0.6 weight ratio of the E-20/HMTA/2-MI systems. DSC experiments revealed that the exothermic peak of the E-20/HMTA/2-MI system was about 55°C lower than that of the E-20/HMTA system. The activation energy of the cure reaction was determined by both Kissinger's and Ozawa's methods at any heating rates. The activation energy and pre-exponential factor were about 100.3 kJ mol and 3.57 × 10 s, respectively. According to the KAS method, the curing time of the E-20/HMTA/2-MI systems was predicted by evaluating the relationship between temperature and curing time.
目前，粉末环氧胶粘剂的缺点是应用领域有限。为了将粉末环氧胶粘剂的应用范围从耐热基材（如金属）拓宽至热敏基材（如塑料制品、纸板和木材），有必要降低固化温度。在本文中，通过熔融共混法，以双酚A环氧树脂（E-20）、六亚甲基四胺（HMTA）作为固化剂以及2-甲基咪唑（2-MI）作为促进剂，制备了一系列快速固化粉末环氧胶粘剂。采用傅里叶变换红外光谱、热重分析、动态热机械分析仪和差示扫描量热法（DSC）对E-20/HMTA/2-MI体系的结构和性能进行了表征。与E-20/HMTA体系相比，向E-20/HMTA体系中添加2-MI可同时提高韧性、拉伸强度、玻璃化转变温度（）和热稳定性。E-20/HMTA/2-MI体系在100/8/0.6重量比时获得了最佳机械性能。DSC实验表明，E-20/HMTA/2-MI体系的放热峰比E-20/HMTA体系的放热峰低约55°C。在任何加热速率下，均通过基辛格法和小泽法测定了固化反应的活化能。活化能和指前因子分别约为100.3 kJ/mol和3.57×10 s。根据KAS方法，通过评估温度与固化时间之间的关系，预测了E-20/HMTA/2-MI体系的固化时间。
