| 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.
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