【作者】 洪晓斌；

【导师】 谢凯；

【作者基本信息】 国防科学技术大学 ， 材料科学与工程， 2009， 博士

【摘要】 本文以在粘度上具有明显特点的低粘度双酚F环氧树脂为基础树脂,针对提高树脂固化物的韧性、耐热性及进一步降低树脂基体工艺过程的粘度等应用需求,进行了新型有机硅改性剂的分子结构设计、合成及改性效果研究,确定了对环氧树脂具有增韧、增强效果,可保持改性固化物较高耐热性的新型低粘度有机硅改性剂的分子结构和制备工艺;研究了新型有机硅改性双酚F环氧树脂的改性效果和改性机理。针对未来复合材料VARTM成型技术对树脂基体的低粘度及降低固化温度等特殊工艺要求,进行了双酚F环氧树脂的共聚、共混改性,以及固化体系配方优选和固化体系化学流变行为研究;采用双阿仑尼乌斯模型预估了树脂基体应用于复合材料VARTM成型工艺的低粘度工作窗口和适宜的工艺条件。论文研究的主要结果及结论如下:1.对三种有机硅改性剂(端环氧基聚二甲基硅氧烷,3,3,-二羟基二苯氧基硅烷及3,3,,3,,-三羟基三苯氧基硅烷三缩水甘油醚)的溶度参数进行了估算。计算结果表明:三种改性剂的溶度参数计算值均高于常用改性剂二甲基硅橡胶的溶度参数,与环氧树脂溶度参数接近,有利于改善与环氧树脂的相容性。三种有机硅在极性力、色散力、氢键力及溶度参数上存在一定的差别,其中含环氧基的三官能度有机硅与环氧树脂的溶度参数最为接近;2.用Hyperchem7.0软件semi-empirical-AM1及Molecular Dynamics算法对含刚性基团的二羟基二苯氧基硅烷合成反应途径进行了优选。计算结果表明,以对苯二酚或间苯二酚与二乙氧基硅烷进行反应制备二羟基二苯氧基硅烷,在热力学上是有利的;3. 3,3,,3,, -三羟基三苯氧基硅烷的合成工艺条件为:间苯二酚与三乙氧基硅烷摩尔比为3.1:1,110℃反应5 h,升温至140℃反应2 h,再于150℃反应1h。其环氧化产物3,3,,3,,-三羟基三苯氧基硅烷三缩水甘油醚的合成工艺条件为:环氧氯丙烷用量为合成三羟基三苯氧基硅烷所需间苯二酚用量的10倍(摩尔比),催化剂为苄基三甲基氯化铵,用量为间苯二酚用量的1.8 %(摩尔比),90℃醚化5~6小时,闭环反应温度为65℃,加碱时间间隔为25min,碱过量2%。产物的环氧值为0.594~0.65mol/100g,粘度为900～1050 mPa·s(25℃);4.脂肪族二官能度端环氧基聚二甲基硅氧烷及含酚羟基的二官能度有机烷氧基硅烷均可提高改性固化物的力学性能,但固化物的玻璃化温度出现不同幅度的降低。3,3,,3,,-三羟基三苯氧基硅烷三缩水甘油醚可使改性固化物的拉伸强度、弯曲强度分别提高10.4%及53.6%,线性热膨胀系数降低18.8%,抗开裂指数提高52.2%,同时保持固化物较高的玻璃化温度,提高耐酸性。该改性剂也可用于双酚A环氧树脂及AG80环氧树脂的改性,使树脂固化物的综合性能有较大幅度的提高,是一种理想的环氧树脂新型改性剂;5.新型有机硅改性剂3,3,,3,,-三羟基三苯氧基硅烷三缩水甘油醚改性环氧树脂具有与普通聚硅氧烷不同的改性机理;其影响环氧树脂固化反应的速率和固化特征,使分子链活动性提高,进而对固化交联网络的结构及固化物的性能产生重要影响;6.新型有机硅改性双酚F环氧树脂、共聚改性双酚F环氧树脂以及采用新型稀释剂CHD共混等方法均可使双酚F环氧树脂的粘度大幅度降低。新型有机硅改性及共聚改性均可同时提高固化物的力学性能和耐热性;含10%CHD的树脂固化物拉伸强度及弯曲强度下降约10%;但CHD含量由10%增至30%,树脂粘度降低幅度较大而固化物性能继续降低的幅度不大;7. TEA固化双酚F环氧树脂室温下具有较长的适用期。TEA含量为20%时,采用60℃固化8h的固化制度,固化物的拉伸强度和弯曲强度分别达78.5MPa和106.0MPa,Tg达111.9℃。TEA固化双酚F环氧树脂可解决较低温度固化与保持树脂较宽低粘度工作窗口的矛盾,以及低温固化与提高固化物耐热性的矛盾;8.以双阿仑尼乌斯化学流变模型模拟TEA固化双酚F环氧树脂体系40~90℃条件下反应过程的化学流变行为结果表明,在所选取的温度范围内,流变行为计算值在一定时间范围内与实测值吻合;9. BPF环氧树脂/TEA体系按照40℃注射,80℃固化的工艺制度,低粘度工作时间达6h以上,由该体系的固化反应特点所决定的化学流变行为基本可满足低温VARTM成型工艺的要求。更多还原

【Abstract】 On the basis of BPF epoxy, which has obviously advantage on viscosity, novel organo-silane modifiers were designed and synthesized for improving toughness, thermal resistance and furthermore decreasing viscosity. And their modification results were studied. A kind of novel modifier with low viscosity was obtained and its synthesis technique was determined. It can increase the toughness and strength of the cured epoxy resin, while the thermal resistance remaining. The modification mechanism of the novel silane was studied. Considering the requirements of vacuum assisted molding technique, for the resin having low viscosity and being cured at relatively low temperature, modification of BPF epoxy by copolymerization and blending was studied also, and formular of the cured system was optimized. Rheological behavior of the matrix during the curing process was studied. A rheological model based on Dual-Arrhenius Equation was used to simulate rheological behavior of the matrix. The processing window of the resin and the optimum processing condition can be well determined by the established model. The main results of this paper are as follows:1. Calculation results of the solubility parameter and the force function between molecules of the designed epoxy-group terminated two functional aliphatic polysiloxane, dihydroxyldiphenoxydimethyl silane and 3,3 , ,3 ,, --trihydroxyltriphenoxymethyl silane triglycidyl ether showed that the solubility parameter of all these novel modifiers are higher than that of poly(dimethyl siloxane) and thus can improve their compatibility with the epoxy. These three modifiers are different in polarity, dispersion force, hydrogen bond and solubility parameter. The solubility parameter of 3,3,,3,,-trihydroxyltriphenoxymethylmethyl silane triglycidyl ether is the most similar to that of epoxy resin.2. Semi-empirica-M1 and Molecular Dynamics in HyperChem 7.0 were used to optimize synthesis reaction of 3,3,-dihydroxyldiphenoxydimethyl silane. It was shown that synthesis of 3,3,-dihydroxyldiphenoxydimethyl silane by dimethydiethoxyalkoxy silane and dihydroxybenzene was of advantage according to thermodynamic calculation results.3. The preferred synthesis condition of 3,3,,3,,- trihydroxyltriphenoxy methyl silane was as follows: The mixture of 1,4-dihydroxybenzene and methytriethoxyalkoxy silane reacted at 100℃for 9h, and then 120℃for 6h followed by 140℃2h under N2 condition, during which by-producer alcohol was moved from the reaction system continuously. In order to increase producing ratio of the target molecule, product of the substitution reaction can be directly used in the followed epoxide procedure, during which the excessive reactant can be changed into epoxy resin also. The mole ratio of ECH to the substitution product was nearly 10:1. Externalization temperature was 90℃, reacting for 5~6h. Closed loop reaction temperature was 60℃, the total amount of alkali added 2% greater than the theoretical one. Alkali was added evenly in nine times in 1.5h . Then the excessive ECH was distilled and the second closed loop reaction was undertaken in tulent solvent at 80℃for 1h. Epoxy value of the distilled product synthesized was 0.594~0.650mol/100g,the viscosity of which being 900~1050 mPa·s at 25℃.4. Epoxy-group terminated two functional aliphatic polysilane and dihydroxyldiphenoxydimethyl silane modifier can improve the mechanical properties of the epoxy resin, but Tg temperature decreased somewhat. 3,3,,3,,-trihydroxyltriphenoxy methyl silane triglycidyl ether can improve the tensile strength and flexural strength of the cured epoxy resin by 10.4% and 53.6% ,respectively. The thermal expansion coefficient below Tg reduced about 18.8%, the internal stress index decreased about 22.8% and the crack resistance index increased about 52.2%. Meanwhile, Tg temperature of the cured epoxy hardly decreased.5. The mechanism of novel organo-silane 3,3,,3,,-trihydroxyltriphenoxy methyl silane triglycidyl ether modified epoxy resin was different from that of normal polysilaxene modified epoxy. It has influence on the crosslinking reaction speed and character of the curing process, increasing the motion ability of polymer chain, which resulting an important influence on the structure and properties of the cured epoxy resin.6. The viscosity of BPF epoxy greatly decreased when modified by novel organo-silane, copolymerization or blending with novel diluent CHD. Mechanical properties and thermal resistance of the cured epoxy modified either by copolymerization with resorcinol or by novel organo-silane were improved. The viscosity of BPF epoxy changed from 3550mPa·s to 1300mPa·s when 10% weight content of CHD was added ,the mechanical properties of the cured epoxy decreasing by 10%. When the content of CHD increased up to 30%, there is only slightly additional decreasing in mechanical properties, but the viscosity of the modifiied epoxy resin decreased greatly.7. TEA cured BPF epoxy had a long pot temper life. When cured by 20% TEA at 60℃for 8h, the tensile strength and flexural strength of the cured epoxy were 78.5MPa and 106.0MPa respectively.The Tg temperature was 106.0℃. TEA cured epoxy resin could resolve the inconsistency between low-temperature-curing and prolonging the pot life, and the inconsistency between low-temperature-curing and high thermal endurance of the cured epoxy.8. A rheological model based on Dual-Arrhenius Equation was used to simulate rheological behavior of TEA cured BPF epoxy resin in curing temperature range of 40~90℃. It was shown that in the studied temperature range the simulated rheological behavior was well accordant with the experimental results in a certain time range.9. TEA cured BPF epoxy resin has long time low viscosity window under the processing schedule of rejecting at 40℃and curing at 80℃. The rheological behavior under this condition, which was determined by the reaction characteristic, can meet the requirements of Vacubm Assisted Resin Transfer Molding.更多还原