几种聚醚胺改性蒙脱土对环氧树脂固化过程的影响

首先制备了五种聚醚胺改性蒙脱土(MMT), 并将这五种聚醚胺改性蒙脱土加入到双酚A 型环氧树脂E51 和聚醚胺D400体系中, 采用差示扫描量热法(DSC)考察了五种聚醚胺改性MMT对环氧树脂升温固化进程的影响. 随后, 优选一种EP/MMT 混合体系即EP/D400-T500-MMT 混合体系, 系统地研究了该体系与纯环氧树脂体系在130, 140, 150 及160 ℃等几个温度下的等温固化过程, 考察了等温固化时间对固化度和固化度变化速率的影响以及固化度与固化度变化速率之间的关系, 并利用Kamal 模型进行拟合计算了固化动力学参数. 研究结果表明, 与纯环氧树脂相比, 几种聚醚胺改性MMT 的固化放热峰均向高温迁移, 同时聚醚胺D400 协同插层MMT 降低了高分子量聚醚胺插层MMT 所导致的环氧树脂DSC 曲线的畸变情况; EP/D400-T500-MMT 混合体系和纯环氧体系的等温固化反应过程符合Kamal 模型;在相同的固化温度下, EP/D400-T5000-MMT 混合体系的反应速率常数k₁ 和k₂ 值以及反应级数m 均比纯EP 体系小, 而反应级数n 以及总反应级数m+n 值比纯EP 体系大, 表明两种聚醚胺协同插层的改性蒙脱土D400-T5000-MMT 的加入降低了环氧体系固化反应速率. 另外, EP/D400-T5000-MMT 混合体系的活化能E_a1 和E_a2 与纯EP 体系的相比也略有升高.

Effect of Montmorillonite Modified by Poly(oxypropylene) Amines on Curing Process of Epoxy Nanocomposites

Five kinds of Montmorillonite(MMT) modified by poly(oxypropylene)(POP) amines were prepared.Each of these modified MMT(O-MMT) was added into epoxy(EP) E51 and hardener POP amine D400 to yield an EP/MMT mixture.Differential scanning calorimetry(DSC) was used to investigate effect of these five MMTs modified by POP amines on epoxy curing process at a heating rate of 10 ℃/min.Then isothermal curing kinetics of neat epoxy and an EP/D400-T5000-MMT mixture was studied by DSC at different temperatures(130,140,150 and 160 ℃).Kamal model was used to calculate the kinetics parameters of the isothermal curing of these two EP systems.The results show that the cure process of EP was found to be influenced by the presence of MMT modified with POP amines.Compared with that of neat EP,exothermic peak of DSC curve of EP/O-MMT shifted to higher temperature,while co-intercalation of POP amine D400 weakened the effect of POP amine D2000 and T5000 on EP curing.At the same isothermal curing temperature,two curing rate constants,k1 and k2,and curing reaction order m of the EP/D400-T5000-MMT mixture were smaller than that of neat EP system,but curing reaction order n and the overall reaction order m+n of the EP/D400-T5000-MMT mixture were larger than that of neat EP system.Thus means that D400-T5000-MMT decreases the rate of epoxy curing reaction.In addition,compared with that of neat EP system,the curing reaction activation energy of EP/D400-T5000-MMT mixture increased slightly.