Research On Recycling Process Of CF/EP Composites Under Supercritical Water/Alcohol Mixture

Carbon fiber reinforced polymer(CFRP)with a series of good performances,such as strong corrosion resistance,high modulus,thermal stability,high strength and impact resistance,is widely used in aerospace,automotive and other fields.The wasted CFRP can not only cause environmental pollution,but also cause serious waste of resources,if it is treated as conventional waste.So the recycling and reuse of CFRP,which is the main measure for the green development of high-performance composite materials,fits the desire of the strategy of resource conservation and sustainable development.Carbon fiber /epoxy resin(CF / EP)composite is the most common application in CFRP.The article mainly investigated the recycling method and process of CF/EP composites based on theoretical and experimental researches.The main research contents are as follows:(1)Degrading CF/EP composites by water,alcohol and water/alcohol mixture under the same parameters was studied.Results showed that the degradation of CF/EP composites was more efficient under the water/alcohol mixture.The degradation rates of CF/EP composite under the different kinds of supercritical water/alcohol(i.e.,methanol,ethanol,n-propanol,n-butanol)was analyzed.The influence of the epoxy resin solubility was investigated from aspects of Hildebrand parameter,dielectric coefficient and dipole moment,and the selection mechanism of supercritical mixture suitably used for degradation of CF/EP composites was established.(2)Degradation experiments of CF/EP composites were conducted under the supercritical water/ n-butanol mixture,in order to research influence of process parameters on the degradation reaction,which includes additive concentration,temperature,holding time and mixture ratio of water/ n-butanol.According to the degradation experiments of CF/EP composites recycled by supercritical water/ n-butanol mixture under different holding temperatures and holding times,correlation coefficient can be obtained by the Levenberg-Marquardt and universal global optimization algorithm,combining with principle of correlation coefficient approximation.In the end,catalytic degradation kinetics equation of CF/EP composites in supercritical water/ n-butanol mixture was proposed.(3)The recycled solid phase product was characterized,and the surface morphology and mechanical properties of recycled carbon fibers were analyzed by SEM and single filament tensile tests.And in order to improve the recycling efficiency of CF/EP composites,the existing supercritical recovery device has been improved,and the prototype system for recycling waste CF / EP composite material is preliminarily designed.