摘要
针对环氧树脂Vitrimer脆性大和强度低的缺点,采用羧酸封端的超支化聚合物Hyper C102来增强增韧戊二酸固化的双酚F环氧树脂(BPF).傅里叶红外线光谱(FTIR)测试和溶胀实验证明了环氧树脂Vitrimer中共价交联网络的形成.示差扫描量热法(DSC)和动态热机械性能分析(DMA)测试材料的酯交换速率和动态力学性能,发现Hyper C102改性的环氧树脂Vitrimer在高温下仍然可以发生高效率的酯交换反应,材料的模量可在30 min内松弛到初始模量的1/e.力学性能测试表明Hyper C102改性环氧树脂Vitrimer的拉伸强度和断裂能分别提高了136%和504%,并拥有着良好的自修复和可重复加工性能.因此,采用羧酸封端的超支化聚合物改性不仅可以保持环氧树脂Vitrimer的动态酯交换特性,还可以极大地改善其力学性能.
Unlike conventional thermoset epoxy resins,epoxy vitrimers with excellent malleability can be recycled,remolded and reshaped.However,most epoxy vitrimers usually shows high fragility and low mechanical properties,which significantly limits their practical applications.To address this issue,we used a carboxyl terminated hyperbranched polymer,Hyper C102,to simultaneously toughen and reinforce a class of vitrimers based on glutaric acid crosslinked bisphenol F epoxy resin(BPF),in which 1-methylimidazole was used as catalyst to endow the system with dynamic exchange properties.Fourier transform(FTIR)and swelling experiments confirmed the formation of covalent crosslinking network in the epoxy vitrimers.DSC and DMA were used to study the dynamic mechanical properties and the rate of transesterification reaction of the materials.The result shows that the crosslink density of the epoxy vitrimers decreases first and then increases with the increasing content of Hyper C102.Such phenomenon can be well explained by the cavitation theory.More intriguingly,the Hyper C102 modified epoxy vitrimers still show high efficiency of transesterification reaction at180°C.Their modulus can relax to 1/e of the initial modulus within 30 min,and to 10%of the initial modulus within 1 h.Meanwhile,the tensile strength and strain at break can be simultaneously improved upon the introduction of Hyper C102.Compared with Hyper0 which contains no hyperbranched polymer,the tensile strength and fracture energy of Hyper7.5 that contains 7.5 wt%Hyper C102 is improved by 136%(from 28 MPa to 66 MPa)and 504%(from 280 kJ/m3 to 1410 kJ/m3),respectively.Such significant and simultaneous improvement in both tensile strength and toughness has not been realized in previous studies.Moreover,the epoxy vitrimers manifest decent self-repairing and recyclable properties after mechanical damage.These results fully demonstrate that the addition of the carboxyl terminated hyperbranched polymer can not only maintain the dynamic transesterification,but also significantly improve the mechanical properties of epoxy vitrimers.
作者
黄鑫
刘汉超
樊正
王豪
黄光速
吴锦荣
Xin Huang;Han-chao Liu;Zheng Fan;Hao Wang;Guang-su Huang;Jin-rong Wu(State Key Laboratory of Polymer Materials Engineering,College of Polymer Science and Engineering,Sichuan University,Chengdu 610065)
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2019年第5期535-542,共8页
Acta Polymerica Sinica
基金
国家科技重大专项(项目号2016ZX05017-002)资助
作者简介
通讯联系人:黄光速,E-mail:guangsu-huang@hotmail.com;通讯联系人:吴锦荣,wujinrong@scu.edu.cn
