【作者】 孙鹤；

【导师】 刘宇艳； 谭惠丰；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2014， 博士

【摘要】 随着热固性形状记忆环氧材料在空间结构技术中应用范围的不断扩大，减少功能器件占用空间以缩小发射体积来降低成本的理念得到广泛的关注，而空间展开结构的应用为解决此问题提供了有效的途径。由于空间展开结构采用的形状记忆材料普遍存在形状记忆双向可逆性、受温度影响大、耐热性和力学强度不能满足某些应用等缺点，本课题提出了一种空间形状记忆展开结构刚化技术，称为“二阶段固化技术”，可较好的解决温度对材料形状记忆性能的不良影响，并提高材料的力学和耐热性能。本文对其可行性、材料制备条件、等温和非等温条件下的固化反应动力学、形状记忆性能、动态力学性能、拉伸强度、微观形貌、耐热性能以及材料的储存期和稳定性进行了研究和探讨，并建立了可以描述体系两个相对独立反应过程的动力学方程。本文首先根据课题需要从种类繁多的固化剂中选取了合适的常温和潜伏型固化剂，采用非等温DSC的方法和凝胶时间的测定对二阶段固化技术的可行性进行分析，证明“二阶段固化技术”确实可行。通过不同升温速率下的非等温DSC测试确定了最优固化工艺，制备了不同理论固化度体系，并应用红外测试对体系的特征基团和固化度进行表征和分析。然后，本文采用非等温DSC模型拟合法中的n级反应模型和自催化反应模型对一阶段固化和其对比体系以及二阶段固化和其对比体系进行固化动力学研究，应用非模型拟合法的FR，FWO和KAS法对以上四个体系的固化过程进行考察以推测其反应机理，探讨潜伏型固化剂的加入对一阶段固化的影响，以及在一阶段固化后的体系引发二阶段固化对其固化过程的影响，实验结果证明，潜伏性固化剂的加入对一阶段固化几乎没有明显影响，在进行一阶段固化的过程中未引发二阶段固化反应，而对于在已经形成一定网络结构中引发的二阶段固化反应，由于一阶段反应后体系生成大量羟基，因此对二阶段固化有促进作用。同时，建立了可以描述四个体系化学反应的动力学方程。而后，采用等温DSC模型拟合法对以上四个体系进行等温条件下的固化过程研究，考察其反应机理，探讨两个阶段固化反应的相互影响，建立了可以描述反应过程的固化动力学方程，并应用FWO法对其相应体系进行等温条件下时间与转化率关系的预测，将预测结果与等温测试结果相对比以验证预测的准确性，实验结果证明，预测效果良好。最后，对材料进行动态力学性能测试以确定其玻璃化转变温度(Tg)和储能模量(Er)，以Tg为参考温度进行形状记忆性能测试，包括回复率、回复时间、固定率和折叠-展开循环次数，实验结果证明经过一阶段固化后的材料具有良好形状记忆性能。通过动力学方程和预测曲线建立一阶段固化体系中转化率与Tg的经验方程，探讨材料成型条件的灵活性和稳定性。应用电子万能材料试验机对材料进行拉伸强度测试，其断口经过喷金处理做SEM测试，以表征其拉伸强度和断裂机理。通过不同的折叠-展开次数和不同时间的静置储存，考察材料的稳定性和储存期，实验结果证明经过一阶段固化后所制备的材料在常温下可保持98%以上的形状固定率至少12个月，并且在此时间内二阶段固化不会被引发。更多还原

【Abstract】 With more application of thermoset epoxy resin shape memory composites in space structure technology, the challenge of using smaller launch volume to reduce cost is geting more attention. Application of space deployable structure provides an effective way to solve this problem. Shape memory materials for space deployable structure have some disadvantages, including two-way shape memory reversibility, poor thermal stability, low heat resistant and mechanical strength. Hence, we design a new two stage curing method to improve the properties of composites. The feasibility of two stage curing method, the material preparation conditions, isothermal and non-isothermal curing kinetics, shape memory property, dynamic mechanical properties, tensile strength, microstructure, heat resistant, the storage life and stability of thermoset epoxy resin composites have been studied. At the same time, the kinetic equations of various systems have been established.Firstly, the appropriate room temperature and latent curing agents have been selected among a wide variety of curing agents. The non-isothermal differential scanning calorimetry (DSC) and gel time tests are used to investigate the feasibility of two stage curing method, the results prove that the two different curing stages can implement successfully. The optimal curing processes have been confirmed by non-isothermal DSC method with different heating rates, and various theory curing degree systems have been prepared. The characteristics groups and theory curing degree are studied by fourier transform infrared spectroscopy (FTIR) tests.Secondly, the n-order and autocatalytic reaction models under non-isothermal condition are used to fit the experimental results of two different curing stages, and the kinetic equations are established. On the other hand, the reaction mechanisms of two different reaction processes are discussed by three FR，FWO and KAS non-model fitting methods. The results show that the addition of latent curing agent hardly influence the first curing stage, and during this curing period, the latent curing agent is not triggered by carefully controlling the curing conditions. For the second curing stage, plenty of hydroxyl (-OH) are generated during the first curing stage, and these–OH promote the second curing stage effectively. Then, the model fitting method under isothermal condition is used to study thereaction processes, reaction mechanisms and the interplay between two different curing stages. The kinetic equations are established. The relationships between reaction time and conversion in various systems are successfully predicted by the FWO method. Lastly, the dynamic mechanical analysis (DMA) tests are utilized to determine the glass transition temperature (Tg) and storage modulus (Er). The fold-deploy shape memory tests are used to evaluate the shape-memory performance of thermoset epoxy resin composites, including shape memory response rate, response time, fixed rate and fold-deploy cycles times. The results show that the composites, after first stage curing, possess good shape memory property. The empirical equations between Tg and conversion are established by combining dynamic equations and predicted curves, showing the credible kinetic equation can guide the desired of the practical reactive process. The tensile tests and scanning electron microscope (SEM) characterization are used to evaluate tensile strength and fracture morphology respectively. Moreover, the storage life and stability of thermoset epoxy resin materials after first curing stage are evaluated by the fold-deploy cycles and standing storage tests. The results show that these composites can store for at least12months at room temperature. Moreover, the shape memory fixed rate can be kept above98%, and the second curing stage is not triggered.更多还原