Preparation And Properties Of Self-Emulsifying Epoxy Resin As Agents For Carbon Fiber

Carbon fiber composite materials are increasingly used in industrial and civil fields.Synthetic fiber filaments have an important influence on the comprehensive properties of composite materials.The development of sizing agents will better repair the surface of the fiber body and improve carbon fiber.The mechanical properties of the body have a promoting effect.The film forming agent is an important part of the sizing agent,and the performance of the emulsion has an important effect on the stability and heat resistance of the sizing agent.There are two sections in this master thesis as shown following??Preparation of Self-emulsifying Epoxy Resin type of Sizing AgentIn this paper,polyethylene glycol(PEG)grafted epoxy resin was used to modify epoxy resin.Epoxy resin was used as hydrophobic group,polyethylene glycol as hydrophilic group and boron trifluoride diethyl etherate as a catalyst to prepare the film-forming agent of sizing agent.The epoxy resin type of sizing agent was prepared at various reaction conditions such as reaction temperature and reaction time and mole ratio of starting materials.The infrared spectrum analysis of the prepared sizing agent is carried out by using infrared spectrum analyzer.It is proved that the molecular structure of the film forming agent contains hydrophilic polyethylene glycol and hydrophobic bisphenol epoxy groups.The film forming agent is added with distilled water to obtain emulsion through self-emulsifying,and some additives such as antioxidant agent and surfactant agent are added to the emulsion,and the mixture is stirred at 500 r/min for 5 minutes and then was stood for 30 days.The storage stability was tested by static storage for the first time.No stratification was observed.The emulsion was centrifuged at the speed of 1000r/min for 30 minutes and no precipitation occurred.The emulsion did not break down,indicating that the emulsion of sizing agent synthesized by this method had good stability.??Preparation of an amphiphilic self-emulsifying epoxy resin type of sizing agentsA method for synthesizing a self-emulsifying amphiphilic epoxy resin type of sizing agents is described.The epoxy resin reacted with a hydrophilic group-containing polyetheramine and a hydrophobic group-containing primary amine(octadecylamine)or dibasic secondary amine(piperazine)is used,the optimal reaction conditions were determined by multiple sets of parallel experiments and the best reaction condition was reached: the reaction time was 3 hours,and the reaction temperature was 110 °C.Under this reaction conditions,the film-forming agent of a sizing agent having hydrophilic and lipophilic properties is obtained by blending two substances and reacted at different ratios.The contact angle test of the sized carbon fiber was carried out using a dynamic contact angle tester.The test results showed that the contact angle was changed with the formulation of the hydrophilic-lipophilic ratio,which matched the designed concept.Under the optimal reaction conditions,the epoxy resin type of sizing agent for carbon fiber with molecular weight of 5000,10000,20000,30000 was designed and tested.The characterization results showed that the sizing agent with molecular weight of 5000 has stable molecular structure and excellent mechanical properties.The ratio of the flexible and rigid segments of the epoxy resin produces a sizing agent with a different ratio of rigid segments.The results of the test show that the particle size of the emulsion increases as the proportion of the rigid segments,but does not have a large effect on the thermal properties of the emulsion.By using cryo-SEM,it can be seen that the epoxy resin type of sizing agent prepared by the method has small particle size with uniform distribution and good stability,and it can be stored for 3 months by static storage.The centrifugal stability test indicated that the emulsion of sizing agent has good storage stability.After the sizing agent is used in by the carbon fiber,the surface defects of the sized carbon fiber are obviously reduced,and the mechanical properties of the fiber are obviously increased by the analysis of the monofilament fracture test results.