液化双氰胺的制备与评价以及预浸料应用研究
发布时间：2018-11-21 21:26
【摘要】：环氧树脂预浸料,通常是树脂体系呈B阶段复合材料的中间材料。双氰胺是环氧树脂预浸料最为常用的潜伏性固化剂,但由于其化学结构极性高,在环氧树脂中的分散性和溶解性差,并可导致固化后所得到的环氧树脂组合物中分散状态恶化,从而影响预浸料及其复合材料的质量。为提高预浸料树脂体系中双氰胺与环氧树脂的相容性,通常需要对双氰胺进行液化改性。本文利用固化剂聚醚胺对双氰胺有较好溶解性的特点,将聚醚胺和双酚A环氧树脂的加成产物制备了液化改性双氰胺固化体系(L-DICY),并与纯双氰胺(DICY)和聚醚胺与双氰胺共混的固化体系(PEA/DICY)进行了比较。相对于DICY和PEA/DICY固化体系,L-DICY固化体系的总胺值和伯胺值均降低,相对于DICY固化体系,PEA/DICY和L-DICY固化体系的结晶性下降,熔点降低,L-DICY静置30天没有明显沉降,且5天内的质量没有明显变化,储存稳定性较好,L-DICY固化体系在环氧树脂分散性得到改善。应用三种固化体系制备了预浸料用树脂体系,研究了三种树脂体系的固化动力学和化学流变学。Kissinger-Akahira-Sunose(KAS)理论分析表明PEA/DICY固化体系活化能最低,L-DICY与DICY固化体系活化能相近,具有较低固化反应活性,有利于保持预浸料的储存期。利用Malek理论和SB(m, n)理论模拟了三种树脂体系在不同固化速率下的速率方程,PEA/DICY和L-DICY体系都较好的预测了实验数据。化学动态流变学分析表明L-DICY与DICY体系有较长的低粘度平台,预浸料加工窗口较宽,双Arrhenius模型模拟了三种树脂体系的等温粘度曲线,在固化前期的低粘度区域能较好地预测树脂体系的粘度。研究了上述三种树脂体系的力学性能、耐热性、透光率和双氰胺在固化树脂中的分散性。相比于DICY和PEA/DICY制备的树脂体系,L-DICY树脂体系的力学性能和玻璃化转变温度都没有明显降低,L-DICY树脂体系固化物的透光率最好,说明L-DICY在固化物中基本没有双氰胺颗粒残留,DICY固化物的微观图像中有未固化的双氰胺颗粒,而PEA/DICY和L-DICY体系中基本没有,说明提高分散性促进了固化反应的进行。应用上述三种树脂体系,采用热熔两步法工艺制备了预浸料,讨论了预浸料复合材料的力学性能和耐湿热性能,评价了双氰胺在复合材料表面的分散情况。相比于DICY和PEA/DICY制备的复合材料,L-DICY体系复合材料的力学性能没有明显下降。经过湿热处理后,L-DICY体系的力学性能下降幅度很小,DICY体系则降低明显,说明L-DICY体系有较好的耐湿热性。DICY体系复合材料板材微观图像中有未固化的双氰胺颗粒存在,而在PEA/DICY和L-DICY体系几乎没有颗粒残存,说明复合材料的耐湿热性与双氰胺在其中的残留有关。
[Abstract]:Epoxy resin prepreg, usually the intermediate material of a B-stage composite of resin systems. Dicyandiamide is the most commonly used latent curing agent for epoxy resin prepreg. However, because of its high polarity of chemical structure, the dispersivity and solubility of dicyandiamide in epoxy resin are poor. Thus, the quality of prepreg and its composites is affected. In order to improve the compatibility of dicyandiamide and epoxy resin in prepreg resin system, liquefaction modification of dicyandiamide is usually needed. The liquefaction modified dicyandiamide curing system (L-DICY) was prepared by using the addition product of polyether amine and bisphenol A epoxy resin. The results were compared with pure dicyandiamide (DICY) and polyether amine / dicyandiamide curing system (PEA/DICY). Compared with DICY and PEA/DICY curing system, the total amine value and primary amine value of L-DICY curing system decreased, compared with DICY curing system, the crystallinity and melting point of PEA/DICY and L-DICY curing system decreased. There was no obvious sedimentation of L-DICY in 30 days, and the quality of L-DICY was not changed in 5 days. The storage stability was good. The dispersion of L-DICY curing system in epoxy resin was improved. The prepreg resin system was prepared by using three curing systems. The curing kinetics and chemical rheology of the three resin systems were studied. The Kissinger-Akahira-Sunose (KAS) theory analysis showed that the activation energy of PEA/DICY curing system was the lowest. The activation energy of L-DICY and DICY curing system is similar, and the curing activity is low, which is helpful to keep the storage period of prepreg. The rate equations of three resin systems at different curing rates were simulated by using Malek theory and SB (m, n) theory. The experimental data of PEA/DICY and L-DICY systems were well predicted. The chemical dynamic rheological analysis showed that L-DICY and DICY system had a long low viscosity platform, and the processing window of prepreg was wider. The isothermal viscosity curves of three kinds of resin systems were simulated by double Arrhenius model. The viscosity of the resin system can be well predicted in the low viscosity region in the early curing period. The mechanical properties, heat resistance, transmittance and dispersion of dicyandiamide in cured resin were studied. Compared with the resin systems prepared by DICY and PEA/DICY, the mechanical properties and glass transition temperature of L-DICY resin system were not significantly decreased, and the light transmittance of cured compounds of L-DICY resin system was the best. The results show that there is no dicyandiamide particle residue in the solidification of L-DICY, and there are uncured dicyandiamide particles in the microcosmic image of DICY solidified compound, but not in PEA/DICY and L-DICY system, which indicates that the increase of dispersion promotes the curing reaction. The prepreg was prepared by hot-melt two-step process using the three resin systems mentioned above. The mechanical properties and hygrothermal resistance of prepreg composites were discussed and the dispersion of dicyandiamide on the surface of composites was evaluated. Compared with the composites prepared by DICY and PEA/DICY, the mechanical properties of L-DICY composites did not decrease obviously. After hydrothermal treatment, the mechanical properties of L-DICY system decreased slightly, while that of DICY system decreased obviously, which indicated that L-DICY system had better resistance to moisture and heat. There were uncured dicyandiamide particles in the microscopic images of DICY composite plate. However, there was almost no particle residue in PEA/DICY and L-DICY systems, indicating that the resistance to moisture and heat of the composites was related to the residue of dicyandiamide in the composites.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ226;TB33
本文编号：2348296
[Abstract]:Epoxy resin prepreg, usually the intermediate material of a B-stage composite of resin systems. Dicyandiamide is the most commonly used latent curing agent for epoxy resin prepreg. However, because of its high polarity of chemical structure, the dispersivity and solubility of dicyandiamide in epoxy resin are poor. Thus, the quality of prepreg and its composites is affected. In order to improve the compatibility of dicyandiamide and epoxy resin in prepreg resin system, liquefaction modification of dicyandiamide is usually needed. The liquefaction modified dicyandiamide curing system (L-DICY) was prepared by using the addition product of polyether amine and bisphenol A epoxy resin. The results were compared with pure dicyandiamide (DICY) and polyether amine / dicyandiamide curing system (PEA/DICY). Compared with DICY and PEA/DICY curing system, the total amine value and primary amine value of L-DICY curing system decreased, compared with DICY curing system, the crystallinity and melting point of PEA/DICY and L-DICY curing system decreased. There was no obvious sedimentation of L-DICY in 30 days, and the quality of L-DICY was not changed in 5 days. The storage stability was good. The dispersion of L-DICY curing system in epoxy resin was improved. The prepreg resin system was prepared by using three curing systems. The curing kinetics and chemical rheology of the three resin systems were studied. The Kissinger-Akahira-Sunose (KAS) theory analysis showed that the activation energy of PEA/DICY curing system was the lowest. The activation energy of L-DICY and DICY curing system is similar, and the curing activity is low, which is helpful to keep the storage period of prepreg. The rate equations of three resin systems at different curing rates were simulated by using Malek theory and SB (m, n) theory. The experimental data of PEA/DICY and L-DICY systems were well predicted. The chemical dynamic rheological analysis showed that L-DICY and DICY system had a long low viscosity platform, and the processing window of prepreg was wider. The isothermal viscosity curves of three kinds of resin systems were simulated by double Arrhenius model. The viscosity of the resin system can be well predicted in the low viscosity region in the early curing period. The mechanical properties, heat resistance, transmittance and dispersion of dicyandiamide in cured resin were studied. Compared with the resin systems prepared by DICY and PEA/DICY, the mechanical properties and glass transition temperature of L-DICY resin system were not significantly decreased, and the light transmittance of cured compounds of L-DICY resin system was the best. The results show that there is no dicyandiamide particle residue in the solidification of L-DICY, and there are uncured dicyandiamide particles in the microcosmic image of DICY solidified compound, but not in PEA/DICY and L-DICY system, which indicates that the increase of dispersion promotes the curing reaction. The prepreg was prepared by hot-melt two-step process using the three resin systems mentioned above. The mechanical properties and hygrothermal resistance of prepreg composites were discussed and the dispersion of dicyandiamide on the surface of composites was evaluated. Compared with the composites prepared by DICY and PEA/DICY, the mechanical properties of L-DICY composites did not decrease obviously. After hydrothermal treatment, the mechanical properties of L-DICY system decreased slightly, while that of DICY system decreased obviously, which indicated that L-DICY system had better resistance to moisture and heat. There were uncured dicyandiamide particles in the microscopic images of DICY composite plate. However, there was almost no particle residue in PEA/DICY and L-DICY systems, indicating that the resistance to moisture and heat of the composites was related to the residue of dicyandiamide in the composites.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ226;TB33
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