环氧/酸酐/DMPA体系固化动力学与溶解性研究
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摘要
在环氧/酸酐固化体系中引入4-二甲氨基吡啶(DMPA)作为酯交换反应催化剂和固化反应促进剂,以制备具有动态交联网络的环氧树脂。用差示扫描量热仪(DSC)对环氧/酸酐/DMPA体系的固化行为进行了研究,考察了催化剂的含量和固化剂比例对环氧/酸酐/DMPA体系固化行为的影响和固化动力学。通过乙二醇溶解实验,研究交联网络中的可交换键。结果表明反应体系中有高温和低温两种固化机理发生反应,催化剂和固化剂含量较少时,固化反应温度高,固化反应中含较多环氧自聚反应,不利于酯交换反应,溶解效果差;反之,固化反应温度向低温移动,利于酯键的形成,样品的溶解速度就越快。当环氧/酸酐为1:1.5,催化剂用量为3%时,具有较好的溶解性能。
In the epoxy/anhydride system,4-dimethylamino pyridine(DMPA)was introduced as a catalyst for the transesterification reaction and the curing reaction to preparing epoxy network with dynamic cross-linking bonds.The curing behavior of epoxy/anhydride/DMPA system was investigated by differential scanning calorimeter(DSC).The influence of the catalyst and the proportion of curing agent on the curing behavior of epoxy/anhydride/DMPA system and the curing kinetics were studied.The exchangeable bonds in the cross linked networks were studied by dissolution experiments in ethylene glycol.The results show that there are two curing mechanisms which occur at different temperatures.As the dose of DMPA and THPA is small,a curing reaction at high temperature yield less ester bonds,which are not conducive to the transesterification reaction and show poor dissolution;on the other hand,the curing reaction shifts to low temperature for more ester bond and a better dissolution.The formula for a better solubility performance may be 1:1.5 of the epoxy/anhydride ratio with 3% DMPA.
In the epoxy/anhydride system,4-dimethylamino pyridine(DMPA)was introduced as a catalyst for the transesterification reaction and the curing reaction to preparing epoxy network with dynamic cross-linking bonds.The curing behavior of epoxy/anhydride/DMPA system was investigated by differential scanning calorimeter(DSC).The influence of the catalyst and the proportion of curing agent on the curing behavior of epoxy/anhydride/DMPA system and the curing kinetics were studied.The exchangeable bonds in the cross linked networks were studied by dissolution experiments in ethylene glycol.The results show that there are two curing mechanisms which occur at different temperatures.As the dose of DMPA and THPA is small,a curing reaction at high temperature yield less ester bonds,which are not conducive to the transesterification reaction and show poor dissolution;on the other hand,the curing reaction shifts to low temperature for more ester bond and a better dissolution.The formula for a better solubility performance may be 1:1.5 of the epoxy/anhydride ratio with 3% DMPA.
引文
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[2]Zheng P,McCarthy T J,A surprise from 1954:siloxane equilibration is a simple,robust,and obvious polymer self-healing mechanism[J].J Am Chem Soc,2012,134(4):2024!2027.
[3]Capelot M.,Unterlass M.M.,Tournilhac F.,et al.Catalytic Control of the Vitrimer Glass Transition[J].ACS Macro Lett,2012,1:789-792.
[4]Capelot M,Montarnal D,Tournilhac F,et al.Metal-catalyzed transesterification for healing and assembling of thermosets[J].J Am Chem Soc,2012,134(18):7664!7667.
[5]Denissen W.,Johan M.W.,Filip E.,Vitrimers:permanent organic networks with glass-like fluidity[J].Chem Sci,2016,7:30-38.
[6]Lu Y X,Guan Z,Olefin metathesis for effective polymer healing via dynamic exchange of strong carbon-carbon double bonds[J].J Am Chem Soc,2012,134(34):14226!14231.
[7]Obadia M M,Mudraboyina B P,Serghei A,et al.Reprocessing and Recycling of Highly Cross-Linked Ion-Conducting Networks through Transalkylation Exchanges of C-N Bonds[J].J Am Chem Soc,2015,137(18):6078-6083.
[8]Smallenburg F,Leibler L,Sciortino F.Patchy particle model for vitrimers[J].Phys Rev Lett,2013,111(18):188002-188100.
[9]Zhou D W,Lu M G,Liang L Y,et al.Curing behavior of Azo-containing twin liquid crystalline epoxy resins with anhydride[J],Poly Eng&Sci,2012,52(6):1375-1382.