新型双酚S衍生四官能度环氧树脂的制备及固化性能

Preparation and curing properties of new tetrafunctional epoxy resin derivedfrom bisphenol S

四官能度环氧树脂因其交联密度高而具有良好的耐温性和优异的力学性能,其中AG-80是综合性能较佳的高性能复合材料基体树脂。但是,结构特点导致AG-80存在韧性差、黏度高、储存不稳定以及交联程度受限等问题,在一定程度上限制了AG-80的使用工艺和固化性能的发挥。为了解决这些问题,本文设计并采用两步法合成了一种新型的四官能度环氧树脂——双酚S四官能度缩水甘油醚(SEP)。通过红外、核磁、质谱等确定了SEP的结构,采用差示扫描量热仪、热机械分析仪、动态热机械分析仪、热重分析仪等分析了SEP的固化行为及固化物的性能。研究结果表明:(1)与AG-80相比,SEP环氧树脂在25℃下的黏度更低,为52.56 Pa·s,这表明SEP环氧树脂具有更好的加工流动性。采用甲基六氢苯酐为固化剂时,SEP的固化温度比AG-80环氧树脂低,且储存更加稳定。(2)对比研究了SEP和AG-80改性双酚A环氧树脂(E-51)的性能,当SEP的质量分数为30%(SEP-30)时,其拉伸强度达到85.77 MPa,冲击强度达到18.74 kJ/m^(2);而AG-80在相同固化温度下的拉伸强度为68.25 MPa,冲击强度为12.61 kJ/m^(2),表明SEP体系的拉伸强度和冲击强度均比AG-80体系的高。通过SEM断面形貌进一步确定,SEP共混体系具有比AG-80体系更好的力学性能。(3)所有SEP共混体系的Td5比AG-80体系的高。800℃下的SEP体系的残碳率最高达到16.9%,而AG-80体系在800℃下的残碳率最高达到9.9%,表明SEP具有比AG-80更好的热稳定性。(4)与AG-80环氧树脂相比,SEP环氧树脂表现出更好的力学性能和耐热性能,为同时实现增强、增韧提供了可能,并使其有望在航空航天等高温领域得到较大的应用。

Tetrafunctional epoxy resin has good temperature resistance and excellent mechanical properties because of its high crosslinking density,among which AG-80 is the matrix resin of high-performance composite material with good comprehensive performance.However,the structural characteristics of AG-80 lead to problems such as poor toughness,high viscosity,unstable storage,and limited degree of crosslinking,which to a certain extent limits the use process and curing performance of AG-80.In order to solve these problems,a new type of tetrafunctional epoxy resin—bisphenol S tetrafunctional glycidyl ether(SEP)was designed and synthesized by two-step method in this paper.The structure of SEP was determined by infrared,nuclear magnetism resonance,mass spectrometry,and the curing behavior of SEP and the properties of cured product were analyzed by differential scanning calorimeter,thermo mechanical analyzer,dynamic thermo mechanical analyzer,thermogravimetric analyzer,etc.The research results showed that:(1)Compared with AG-80,the viscosity of SEP epoxy resin was lower at 25℃,as 52.56 Pa·s,indicating that SEP epoxy resin had better processing flowability.When methyl hexahydrophthalic anhydride was used as the curing agent,the curing temperature of SEP was lower than that of AG-80 epoxy resin,and storage was more stable.(2)A comparative study was conducted on the properties of SEP and AG-80 modified bisphenol A epoxy resin(E-51).When the mass fraction of SEP was 30%(SEP-30),its tensile strength reached 85.77 MPa and impact strength reached 18.74 kJ/m^(2).The tensile strength and impact strength of AG-80 at the same curing temperature were 68.25 MPa and 12.61 kJ/m^(2),respectively,indicating that the tensile strength and impact strength of SEP system were higher than those of AG-80 system.Through SEM cross-sectional morphology,it was further determined that the SEP blending system had better mechanical properties than the AG-80 system.(3)The Td5 of all SEP blending systems was higher than that of AG-80 system.The maximum carbon residue rate of SEP system at 800℃was 16.9%,while the maximum carbon residue rate of AG-80 system at 800℃was 9.9%,indicating that SEP had better thermal stability than AG-80.(4)Compared with AG-80 epoxy resin,SEP epoxy resin exhibited better mechanical and heat resistance properties,which provided the possibility of achieving reinforcement and toughening simultaneously,and had the potential to be widely used in high-temperature fields such as aerospace.