连续纤维增强PCBT复合材料的制备及连接性能研究

发布时间：2018-05-17 23:40

本文选题：CBT低聚物 + GF/PCBT复合材料　；参考：《哈尔滨工程大学》2015年博士论文

【摘要】：热塑性复合材料与热固性复合材料相比,具有较好的韧性和抗冲击性能,成型周期短、制造成本低、可循环使用、废料可回收、产品可再熔融加工等优点,近年来受到了航空航天工业、船舶制造业、汽车制造业、建筑工业等的高度重视。但是热塑性塑料由于其分子结构的特点,在加热熔融状态下,较高的熔体黏度对树脂的流动产生了阻碍,影响了树脂对纤维的充分浸润,从而限制了热塑性复合材料在大尺寸构件和主承力结构中的应用。环状对苯二甲酸丁二醇酯(CBT)的出现改变了这一大难题,CBT是一种具有大环寡聚酯结构的新型树脂,在加热后熔体黏度极低。在适量催化剂和适当温度下,可开环聚合成高分子量的热塑性工程塑料聚环状对苯二甲酸丁二醇酯(PCBT),聚合过程中无反应热、无气体和挥发性有机化合物释放。本文基于CBT树脂的特点,通过原位聚合的方法,对连续纤维增强PCBT复合材料的液体成型制备方法和工艺参数进行了研究,并采用实验和有限元模拟相结合的方法对热塑性复合材料熔融连接件的结构进行设计,研究了接头的承载能力和失效模式。其具体工作如下:1.通过流变测试,分析CBT在聚合过程中熔体黏度的变化趋势,确定在液体成型过程中树脂对纤维的最佳浸润时间;通过差示扫描量热分析、热重分析和力学性能分析,确定CBT的聚合加工温度和催化剂的投放技术,为纤维增强PCBT复合材料的制备工艺提供基础性能参数。2.利用CBT低加工黏度的特性,使CBT在浸渍纤维过程中发生树脂的开环聚合反应,开发可适用于结构复杂的主承力构件生产的热塑性复合材料液体成型技术。以RTM和VARIM工艺为基础,成功制备了高纤维体积分数的GF/PCBT复合材料层合板,研究了催化剂含量和纤维体积分数对层合板力学性能和失效模式的影响。3.PCBT复合材料大型构件的制备要通过连接技术来实现,采用加热使复合材料待连接面内树脂基体发生局部熔融再冷却固结的新型熔融连接技术,制备了凸凹槽对接型GF/PCBT连接件。分别以连接界面层数和连接长度为变量,研究了复合材料接头的承载能力和破坏模式,从而对接头的结构进行设计。4.通过实验研究了 GF/PCBT复合材料的高温力学性能,在高温环境下,GF/PCBT层合板和接头的力学性能随着温度的升高而下降,在PCBT的玻璃化转化温度区域内,复合材料的力学性能下降迅速。在经历高温再冷却后,接头的力学性能几乎不受影响,加热过程的温度低于PCBT的维卡软化温度时,层合板的力学性能也基本为一个定值,高于PCBT软化温度时,由于这个类似于退火的处理使层合板力学强度有小幅度提升。5.使用扩展有限元对复合材料接头的渐近损伤过程进行模拟,采用基于能量的BK准则,选用内聚力单元仿真连接区域的界面失效过程,采用三维HASHIN准则,利用ABAQUS子程度USDFLD仿真纤维和基体的损伤破坏。数值模拟结果与实验结果对比分析,吻合度良好,证明此方法能为GF/PCBT熔融连接接头的结构优化设计提供有效的依据。
[Abstract]:Compared with thermosetting composites, thermoplastic composites have the advantages of good toughness and impact resistance, short molding cycle, low manufacturing cost, recyclable, recycled waste and product remelting. In recent years, it has been highly valued by aerospace industry, shipbuilding industry, automobile manufacturing industry, construction industry and so on. Due to its molecular structure, the high melt viscosity of plastic plastics hinders the flow of the resin in the heating and melting state, which affects the full infiltration of the resin to the fiber, thus limiting the application of the thermoplastic composites in the large size components and the main bearing structure. The appearance of cyclic butylene terephthalate (CBT) is changed. CBT is a new type of resin with large ring oligosaccharide structure. After heating, the viscosity of the melt is very low. Under appropriate catalyst and appropriate temperature, the ring can be polymerized into a high molecular weight thermoplastic polycyclic polybutylene terephthalate (PCBT). No reaction heat, no gas and volatile organic compounds are found in the polymerization process. In this paper, based on the characteristics of CBT resin, the preparation method and process parameters of continuous fiber reinforced PCBT composites were studied by in-situ polymerization. The structure of the melting joint of thermoplastic composites was designed by the method of experiment and finite element simulation, and the joint was studied. The concrete work is as follows: 1. through the rheological test, the change trend of the melt viscosity of CBT during the polymerization process was analyzed, and the optimum infiltration time of the resin to the fiber during the process of liquid forming was determined. The polymerization temperature and the mechanical properties of the CBT were determined by differential scanning calorimetry, thermo gravimetric analysis and force analysis, and the polymerization temperature and expediting of the polymerization were determined. The preparation technology of chemical agent provides the basic performance parameter.2. for the preparation process of fiber reinforced PCBT composites by using the properties of CBT low processing viscosity, so that the CBT can occur ring opening polymerization in the process of impregnating the fiber. The development of the thermoplastic composite liquid forming technology for the production of the complex structure of the main bearing component is applied to RTM and RTM. On the basis of VARIM process, GF/PCBT composite laminates with high fiber volume fraction were successfully prepared. The effects of catalyst content and fiber volume fraction on the mechanical properties and failure modes of laminates were studied. The preparation of large components of the composite material of.3.PCBT composite material should be realized by connecting technology. A new-type melting connection technology for the local melting and re cooling of the fat matrix has been prepared. The joint type GF/PCBT joints with convex grooves are prepared. The bearing capacity and failure modes of the joint are studied by connecting the number of interface layers and the length of the connection. The structure of the joint is designed by.4. and the GF/PCBT composite is studied by experiment. Under the high temperature environment, the mechanical properties of GF/PCBT laminates and joints decreased with the increase of temperature. The mechanical properties of the composites decreased rapidly in the glass transition temperature region of PCBT. The mechanical properties of the joints were almost unaffected by the high temperature recooling. The temperature of the heating process was lower than that of PCBT. When the softening temperature of VEKA is softened, the mechanical properties of the laminates are also basically a fixed value. When the softening temperature is higher than the PCBT softening temperature, the mechanical strength of the laminates is slightly enhanced by this annealing treatment..5. uses the extended finite element to simulate the asymptotic damage process of the composite joint, and uses the BK criterion based on energy to select the cohesion. The force unit simulate the interface failure process of the connection area, and use the three-dimensional HASHIN criterion to simulate the damage and damage of the fiber and the matrix using the ABAQUS sub degree USDFLD. The numerical simulation results are compared with the experimental results, and the coincidence degree is good. It is proved that this method can provide the effective basis for the structural optimization design of the fused joint joint of the GF/PCBT.
【学位授予单位】：哈尔滨工程大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB332

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