Synthesis And Characterization Of A Bismaleimide Heat-resistant Emulsion Sizing Agent For Carbon Fibers

Aromatic polyimides are well known with outstanding mechanical properties and high temperature capabilities. They can be widely used in aerospace, microelectronics and other fields. Using polyimide-based carbon fiber composite to replace the traditional steel or alloy, can reduce vehicle weight which can greatly reduce costs. But the epoxy agent on the commercialization of carbon fiber surface easily decomposed at high temperatures, so that the interface phase and the composites have been destroyed. In general, the sizing agents have solvent type and emulsion type, in recent years, emulsion sizing agent become a trend in the field of sizing agents as people take more and more attention to safe, economic, health, etc. The aim of the dissertation is to find a kind of emulsion type sizing agent having both high heat resistance and good long-term stability of emulsion and dispersion.Since the bismaleimide (BMI) has a good temperature resistance, low viscosity, good solubility and a series of advantages, we expected to select a good temperature resistance, low viscosity bismaleimide as the good materials of the sizing agent. After its emulsion, we sized on carbon fibers to improving the infiltration of carbon fiber surface and chemical reactivity, and finally improving carbon fiber composite interlaminar shear strength.First, we used two kinds of diamine to prepare the bismaleimide. Using the thermal and rheological properties characterization, we proved that 4,4-bis (3-aminophenoxy) benzophenone maleimide (BMI-1) which have interbit carbonyl and ether containing had better heat resistance, lower melt viscosity and longer processing window, and was more suitable for sizing. In the third chapter, we emulsified BMI-1 to have the emulsion sizing agent 1. We also introduced two kinds of emulsion sizing agents:sizing agent 2 and sizing agent 3. We tested the particle size, dispersion, storage stability and film-forming of three kinds of emulsion sizing agents to ensure good qualities and uniformity of the carbon fiber sizing of the necessary conditions.After that, we used them to size on the CCF300 carbon fiber re-sizing, varies method such as SEM, XPS and DCA tests were used to indicate that the sizing agents had some influence for the chemical and physical properties on the carbon fiber surface which based on the increasing of the surface sizing and invasive activity. The carbon fiber surface sized by sizing agent 1 had the best overall performance, as the increased of O/C and N/C ratio.In the last chapter, we used LP-15 polyimide resin as the matrix, and composited it with different treatment methods treated CCF300 carbon fiber. The results of room temperature/high temperature shear strength between the lower (ILSS) show that magma contains carbon fiber composites at room and high temperature ILSS were the lowest, and composite materials sized by sizing agent 1 has the best screen performance at high temperatures. Finally, we proved the ILSS test results from the scanning electron microscopy (SEM).Next, we look forward to the composite thermal aging test, we can test the interlaminar shear strength of the composite after aging to further evaluate the emulsionsizing agent 1.