高模量高Tg可降解环氧树脂的合成及性能研究

Synthesis and properties of high modulus, high Tg degradable epoxy thermosets

通过季戊四醇将对羟基苯甲醛偶合得到含螺旋缩醛的二酚,进而与环氧氯丙烷反应两步法制备了一种含有螺环缩醛结构的环氧树脂DGDB,采用核磁共振氢谱、碳谱以及红外光谱分析对树脂的化学结构进行了详细表征。以4,4’-二氨基二苯基甲烷(DDM)作为固化剂对其进行了固化。实验结果表明,DGDB-DDM固化物的T_g达215℃,杨氏模量达2062MPa,拉伸强度达91.5MPa,均明显高于商用双酚A环氧-DDM固化物(T_g为174℃,杨氏模量为1893MPa,拉伸强度为76.4MPa)。DGDB-DDM固化物与双酚A环氧-DDM固化物的断裂伸长率相当。DGDB-DDM固化物在热重分析实验中表现出相对双酚A环氧-DDM固化物较低的初始降解温度但仍高于330℃,同时DGDB-DDM固化物在700℃下残炭率(空气氛围下23.7%,氮气氛围下45.1%)远高于双酚A环氧-DDM固化物的残炭率(空气氛围下0%,氮气氛围下18.6%)。在保证其各项性能优异的同时,缩醛结构的引入赋予DGDB固化物优异的降解性能,在温和的酸性水/有机溶剂溶液中可完全降解成小分子或低聚物而溶于溶液中。改变温度、酸种类和浓度、有机溶剂种类都可以调节其降解速率,降解速率随温度、酸强度和有机溶剂对材料溶胀能力的提升而变快。

In this paper,an epoxy resin with a spirocyclic acetal structure(DGDB)was synthesized by a two-step method of coupling of p-hydroxybenzaldehyde to achieve diphenol with spirocyclic acetal structure and further reacting with epichlorohydrin to get DGDB.Its chemical structure was characterized in detail by 1H-NMR,13C-NMR and FT-IR.The cured DGDB by 4,4’-diaminodiphenyl methane(DDM)showed Tg of 215℃,Young’s modulus of 2062MPa and tensile strength of 91.5MPa,much higher than the DDM cured commercial bisphenol A epoxy with Tg of174℃,Young’s modulus of 1893 MPa and tensile strength of 76.4MPa,and showed similar elongation at break to the cured bisphenol A epoxy.The cured DGDB showed slightly lower good thermal stability with initial degradation temperature Td5%but it was still above 330℃,and interestingly,it exhibited much higher carbon residue at 700℃(23.7%under air atmosphere and 45.1%under nitrogen atomosphere)than the cured bisphenol A epoxy(0%under air atmosphere and 18.6%under nitrogen atomosphere).Besides,the introduction of the acetal structure imparted excellent degradability to the cured DGDB.The cured DGDB could be completely degraded into small molecules and oligomers and dissolved in mild acidic solutions(organic solvents-water component solvents).The degradation rate of the cured DGDB could be tuned via changing degradation conditions of temperature,acid type and concentration as well as the organic solvent type,and increased with the increase of degradation temperature,acidity as well as the swelling degree of the cured DGDB in organic solvents.