Study On Preparation And Characterization Of Waterborne Epoxy Dispersant System And Aligned Short Carbon Fibers Mats

With carbon fiber reinforced polymer matrix composites(CFRP)widely applied in aerospace,aviation and other fields,the amount of related waste has reached a nonnegligible degree.The recycle and reuse of carbon fiber has become a urgent problem considering environmental protection and economic.The recycling technology of carbon fiber has becoming more mature and the volume of recycling carbon fiber will be more amazing,so how to reuse recycling carbon fiber with more efficient and environmental method is becoming a research focus from the researchers at home and abroad in the future.The waterborne epoxy emulsion and related waterborne agent have been prepared and characterized in this paper.And suspension of recycling carbon fiber is prepared with preceding waterborne epoxy as dispersion medium.The preparation and characterization of aligned short carbon fibers mats have been realized with home-made lab orientation device in flow-field method.In addition,curing kinetics of waterborne epoxy dispersion system has been studied.The main contents are as follows:1.The etherification product of epoxy resin(EP)modified by polyethylene glycol(PEG)was prepared.And the etherification product was used to prepare water-based epoxy emulsion as a polymer emulsifier.The hydrochloric acid-acetone method was used to monitor the changes of the epoxy value in the graft reaction.The infrared spectrum(FTIR)and gel permeation chromatography(GPC)have been used to characterize the structure of etherification product.Nano particle meter and scanning electron microscope(SEM)have been used to characterize and observe thesize and morphology of the emulsion particle.The results showed that the catalyst was potassium persulfate(K2S2O8),the reaction temperature was 120 and the reaction time was 6h.The emulsification results of the modified PEG-4000 were the best.The emulsifying process were that the content of the emulsifier was 15%,the content of the polymer emulsifier was 50%,and the emulsion time was controlled at about 30min.The emulsion particles were at about 270nm through particle size test and SEM photo analysis,and the storage stability was good under normal temperature and high temperature(50 ?).2.The water-borne curing agent of diamine diphenyl sulfone(DDS)modified by PEG was prepared.The FTIR and GPC have been used to characterize the structure of modified products.Perchloric acid no aqueous titration was used to titrate the total amine value of modified products.The differential scanning calorimeter(DSC)and thermo-gravimetric analysis(TG)have been used to analysis the curing exothermic and characterize the thermal stability performance of the modified curing agent.The results showed that the graft modification of DDS was carried out by PEG-4000,boron trifluoride ether was used as catalyst for the synthesis of modified curing agent.The dosage was 0.5%and the reaction temperature was 50?.The amine value of DDS were respectively 114.59 and 203.22 before and after the modification.The curing exothermic temperature of the modified curing agent was gradually decreased and the decrease was more than 100 degrees.The curing exothermic peak of DDS was 237.62? while modified by PEG-4000 was at 102.80?.The thermal decomposition temperatures of DDS respectively modified by PEG-1000,PEG-2000,PEG-4000 were respectively 254?,324 ? and 382?.3.The non-isothermal DSC method and n-level model in the only model were adopted to study the effect of PEG on the the curing mechanism and activation energy of EP/DDS system.The results showed that compared with EP/DDS system,the activation energy of curing reaction resin system was reduced.The PEG flexible polyether segment grafting in the DDS reduced the activation energy and improved the curing process.4.The aligned short carbon fibers mats based on waterborne epoxy dispersion system were prepared.Rotational rheometer was used to characterize the viscosity of the chopped carbon fiber slurry.Digital photographs and SEM photos were used to observe the orientation and apparent morphology of fibers in the mats.The second order tensor analysis was used to quantify the fiber orientation degree of aligned mats.The TG was used to characterize the fiber content of aligned mats.The results showed that the viscosity of the waterborne epoxy system was 1500mPa s when 10%of the deionized water was added to the dispersive system to control viscosity and the effect of fiber dispersion was the best.The orientation degree and fiber content of fiber in the aligned mats were increased with the number of layers of fibers mats increasing.The aligned mats with 80%of the fibers aligned within the range of ±15°in the direction of the flow field orientation had been prepared.