Abstract
A thermosetting resin system, based on bismaleimide (BMI), has been developed via copolymerization of 4,4′-diaminodiphenylsulfone with a newly synthesized graphene oxide modified using epoxy silane (ES-GO). The effect of ES-GO on the thermomechanical and mechanical properties of cured modified resin was studied. To evaluate the efficiency of the modified BMI systems, the composite samples using glass fiber cloth were molded and tested. Thermogravimetric analysis indicates that the cured sample systems displays a high char yield at lower concentrations of ES-GO (≤0.5 wt.%), suggesting an improved thermal stability. Using dynamic mechanical analysis, a marked increase in glass transition temperature (Tg) with increasing ES-GO content was observed. Analysis of mechanical properties reveals a possible effect of ES-GO as a toughener. The results also showed that the addition of 0.3 wt.% ES-GO maximizes the toughness of the modified resin systems, which was further confirmed by the result of analysis of fracture surfaces. At the same time, a molded composite with ES-GO showed improved mechanical properties and retention rate at 150 °C as compared to that made with neat resin.
Highlights
Bismaleimide (BMI) resins are widely applied in high-tech fields due to their high thermal stability, great mechanical properties and good moisture, radiation and corrosion resistance after curing [1,2,3,4,5,6]
The C–OH content of ES-Graphene oxide (GO) showed a significant decrease compared with GO, which can be attributed to epoxy silane reaction with the hydroxyl groups on the surface of graphene oxide after hydrolysis resulting in a decrease in C–OH content
The observation results of the fracture surface of the resin system are consistent with the change trend of mechanical properties, which proves that epoxy silane modified graphene oxide (ES-GO) can improve the toughness of the BMI system to a certain extent
Summary
Bismaleimide (BMI) resins are widely applied in high-tech fields due to their high thermal stability, great mechanical properties and good moisture, radiation and corrosion resistance after curing [1,2,3,4,5,6]. Due to the large number of oxygen functional groups, GO can be used as a new class of modifiers for resin matrixes, resulting in the observation of new properties or in a considerable improvement of them, leading to modification of structure-properties relations, which otherwise wouldn’t be detected [33,34,35]. As we know, the location of GO will become a stress concentration point during the deformation of the resin matrix, which causes the resin matrix around it to be yield, and absorbing a large amount of deformation work, so as to achieve the purpose of toughening [36,37]; in addition, a large number of active functional groups can be introduced into the surface of GO via modifying, which can be both physically or chemically cross-linked with the polymer chain. The effects of ES-GO content on thermal stability and the mechanical properties of the modified BMI system were studied, and a complementary study of glass-fiber-reinforced composites based on modified resins was performed and is described in some detail
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