【作者】 朱能波；

【导师】 陈平；

【作者基本信息】 大连理工大学 ， 高分子材料， 2010， 硕士

【摘要】 双马来酰亚胺(BMI)具有易加工性,优异的耐化学腐蚀性,高强高模和耐高温性等优异的综合性能。但是BMI树脂不溶于普通溶剂中,高熔点及固化后性脆等缺点限制了其应用。由于含有1,3,4-噁二唑结构的聚合物具有高的玻璃化转变温度,优异的耐热氧化性,电性能和力学性能等。因此,在BMI中引入1,3,4-噁二唑基团来提高聚合物的性能得到了广泛的关注。环氧树脂是热固性树脂基体最主要的组成部分,是各工业领域中不可缺少的基础材料；但同时也存在着固化后交联密度高、质脆、耐温等级不够高和耐冲击性差等缺点。BMI与环氧树脂有良好的相容性,尤其是BMI经扩链以后两酰亚胺环之间的距离增加,这样不仅可提高BMI/EP/二元胺体系的热机械性能,还可起到增韧作用。因此本文合成了一种新型的含噁二唑结构的双马来酰亚胺(Mioxd),并用其对环氧树脂(DGEBA)进行改性,最大限度发挥BMI/EP/二元胺共混体系的高强高模耐高温等一系列优异的性能,以满足现今对于轻质、高强、耐高温、高韧性材料的需要。本论文首先通过设计,合成了一种新型的含噁二唑结构的Mioxd单体。采用FT-IR、NMR等手段验证了合成的]Mioxd单体与设计的结构相符合；通过设计正交实验优化了合成工艺,提高了产率。接着通过DSC、TGA等分析手段研究了合成的Imoxd单体的表观活化能与耐热性,结果表明Mioxd单体与传统的BMI单体有着相类似的表观活化能；而且具有较高的耐热性,说明1,3,4-噁二唑结构的引入提高了材料的耐热性能。然后用Mioxd单体对DGEDA/DDS (4,4’—二氨基二苯砜)固化体系进行改性,通过DSC研究了体系的固化动力学,确定了体系的固化工艺。结果表明,随着体系中Mioxd比例的增加,体系的固化放热峰向低温区移动,总反应热减小,利于材料的成型加工。通过对固化后的体系进行DSC与FT-IR分析,结果表明所选用的固化工艺是合理的。最后通过TGA、冲击性能测试、热变形温度(HDT)测试、弯曲性能测试、DMA、吸水率和SEM等方法考察Mioxd含量对改性体系热机械性能的影响,研究了树脂体系的结构与性能间的关系。结果表明Mioxd的加入能够降低体系的交联密度,当Mioxd的加入量为15%时体系的抗冲击强度和弯曲模量分别比未加入Mioxd体系提高36.5%和13.1%；DMA结果表明由于Mioxd中含有耐热性好的噁二唑和酰亚胺刚性结构环使得材料强度和玻璃化转变温度都随着Mioxd的含量的增加而增加；SEM结果表明改性后材料断裂面的形态逐渐呈现韧性断裂特征。更多还原

【Abstract】 Bismaleimides (BMI) possess an advantageous combination of properties, such as favorable processability, excellent chemical resistance, outstanding thermal stability, unexpectedly high strength and high modulus. However, some essential disadvantages of these known BMIs are that they are sparingly soluble and difficult to melt, and the cured networks thereof are brittle. The introduction of 1,3,4-Oxadiazole moiety into the macromolecular chains of high-performance polymer materials has been the focus of considerable interest during the past several decades. This is owing to the polymers based on 1,3,4-Oxadiazoles exhibit good hydrolytic stability, high glass transition temperatures, excellent heat resistance in oxidative atmosphere, low dielectric constants and tough mechanical properties. Epoxy resins are considered to be the most important class of thermosetting polymers and extensively used in structural adhesives and fiber-reinforced composites. However, the inherent brittleness, limited impact strength and high level of moisture absorption restrict their utility for high-performance applications. BMI and epoxy resin has good compatibility, especially when the BMI with extended chains toughen epoxy resin, the toughness of epoxy resin will be dramatically increased owing to the distance between the two maleimide rings those can decrease the cross-link desity and the thermo and mechanical properties of modified systems will be improved. Thus, in this paper, a novel bismaleimide monomer containing 1,3,4-oxadiazole (Mioxd))were designed, synthesized and blended with EP/DDS to enhance the BMI/epoxy/diamine curing system of heat resistance, high strength and high modulus excellent performance to meet today for the lightweight, high strength, high temperature, high toughness material needs.First of all, in this thesis, a novel bismaleimide monomer (Mioxd) containing 1,3,4-oxadiazole moiety were designed and synthesized. The structure of Mioxd was carefully characterized by FT-IR and NMR. Optimize synthesis technique by orthogonal test to improve synthetic yield. Subsequently the apparent activation energy and heat resistance of Mioxd were studied by DSC and TGA. The results show that Mioxd monomer has apparent activation energy comparable with the traditional BMI and has good high heat resistance with a fairly wide thermal decomposition process, indicating 1,3,4-oxadiazole structure contributes to the heat-resistant material.The DGEDA/DDS (4,4’-diaminodiphenyl sulfone) systems were further modified by Mioxd and the curing kinetics and procedure of Mioxd/DGEBA/DDS were carefully studied by DSC and FT-IR. DSC results show that the curing exothermic peak moved to the low temperature region and the total reaction heat decreases of the co-curing resin systems decreased with the increase of Mioxd content, which is benefit to material molding. The cured systems were investgated by FT-IR and DSC. The results indicate that the system can be completely cured.Finally, the effect of Mioxd content on the thermo and mechanical properties of copolymer were investigatied by a combination of methods such as TGA, impact strength, HDT, flexural test, DMA, water absorption and SEM. Compared with neat epoxy system, the impact strength and flexural modulus of 15 wt % modified system reach the maximum value of 2.57kJ/m2 and 2.41 GPa, increasing by 36.5% and 13.1%, respectively. In addition, DMA results show that the strength and Tg of blends increasing as the content of Mioxd increasing. Furthermore, SEM results indicate that fracture surface of modified system presents ductile fracture features with the increasing of Mioxd content.更多还原