Al2O3/环氧树脂-氰酸酯复合材料反应动力学及力学性能

以双酚A型环氧树脂(E51)和双酚A型氰酸酯(BCE)为原料,研究E51改性BCE共固化反应机制。同时,以E51-BCE为基体树脂,溶胶-凝胶法(Sol-Gel)自制Al2O3为增强体,制备Al2O3改性E51-BCE (Al2O3/E51-BCE)复合材料。通过非等温DSC确定了E51-BCE体系的固化工艺及固化反应动力学,并根据Kissinger法和Ozawa法求得体系的表观活化能分别为66.13 kJ/mol和69.46 kJ/mol。利用红外光谱跟踪固化体系在起始固化温度为160℃、 180℃时的反应历程,结果表明:起始固化温度在160℃时,以E51与BCE直接反应为主;起始固化温度在180℃时, BCE反应活性提高,以BCE自聚反应为主,生成三嗪环的速率加快,少量的BCE直接与E51反应生成恶唑啉结构。对Sol-Gel法自制Al2O3进行FTIR和TEM表征,结果表明:Al2O3为短纤维状的晶体,表面含有少量羟基。SEM结果显示:Al2O3为分散相,与基体间界面模糊, Al2O3/E51-BCE复合材料的脆断面裂纹不规则,为典型的韧性断裂;当Al2O3掺杂量为3wt%时, Al2O3在基体中分散均匀, Al2O3/E51-BCE复合材料的冲击强度和弯曲模量分别为24.2 kJ/m2和2.54 GPa,比基体树脂的冲击强度和弯曲模量分别提高53.65%和22.12%,力学性能得到明显改善。

Reaction kinetics and mechanical properties of Al2O3/epoxy-cyanate ester composites

The bisphenol A epoxy resin (E51) and bisphenol A cyanate (BCE) were used as the raw materials to study the co-curing reaction kinetics mechanism. At the same time, E51-BCE was used as the matrix resin, and Al₂O₃ obtained with Sol-Gel method as reinforcement to prepare the Al₂O₃/E51-BCE composites. The solidification process and curing kinetics of the system were determined by non-isothermal DSC, and the apparent activation energy of the system are 66.13 kJ/mol and 69.46 kJ/mol according to the Kissinger and Ozawa equation, respectively. Infrared spectroscopy was used to track the reaction route of the system at the initial curing temperature of 160℃ and 180℃. The results reveal that E51 reacts directly with BCE when the curing temperature starts at 160℃. The BCE's reactivity will be improved when the curing temperature is 180℃, BCE is mainly consumed in the self-polymerization reaction, and the formation rate of the triazine ring is accelerated. A little part of BCE directly reacts with E51 to form an oxazoline structure. The FTIR and TEM results of Al₂O₃ show that the structure of Al₂O₃ is a short fiber-like crystal with a little amount of hydroxyl groups on its surface. The SEM patterns of the Al₂O₃/E51-BCE composites indicate that Al₂O₃ presents as disperse phase in matrix, the interface between Al₂O₃ and matrix is fuzzy and the failure cracks are irregularity, thus it is typical ductile fracture. 3wt% Al₂O₃ is uniformly dispersed in matrix, and the impact strength and bending modulus of Al₂O₃/E51-BCE composites is 24.2 kJ/m2 and 2.54 GPa, respectively, which are increased by 53.65% and 22.12% compared with E51-BCE matrix resin. The mechanical properties of Al₂O₃/E51-BCE composites are improved obviously.