| At present,in response to the difficulty in recycling fiber-reinforced epoxy resin-based thermoset composite materials,governments and industry organizations have successively issued a number of relevant documents to guide and encourage the composite materials industry and scientific research units to carry out research on recycling and reuse of composite materials..The use of degradable epoxy resin matrix is an important research direction of recycling,but the performance of degradable epoxy resin matrix composites and the performance stability under corrosive environment are of great significance to promote its popularization and application.In this paper,the degradable epoxy resin matrix composites are studied from the following five aspects:(1)The curing curve of the degradable epoxy resin system was tested by DSC at different heating rates.The curing process parameters of the resin system were obtained by extrapolation combined with the glass transition temperature of the cured product and the infrared spectrum of the cured product.The preparation of the castable was guided by the curing process parameters,and the mechanical properties of the castable body of the degradable epoxy resin system were studied.The unidirectional prepreg system of the degradable epoxy resin was prepared and the mechanical properties of the laminate were tested.The results show that The material system has good conventional mechanical properties and interface properties.(2)Research on environmental corrosion performance:Based on the interlaminar shear and bending properties,the properties of degradable epoxy resin matrix composites under water immersion,oil immersion,damp heat and salt spray environment were studied.The results show that the wet heat has the greatest influence on the performance of the composite system.The interlaminar shear performance of the 28d wet heat treatment is reduced by 14%,the bending strength is reduced by 6%,but the residual strength shear strength is still 67MPa and the bending strength is 1354MPa.It can be seen that the degradable epoxy resin composite material has good resistance to 28 days of continuous corrosion of water immersion,oil immersion,damp heat and salt spray.The hydrothermal performance of the degradable resin casting body and its composite laminate was studied by dynamic thermomechanical instrument.The results show that the resin casting body and the composite material under the same conditions have the same glass transition temperature and glass transition temperature,from high to low,it is dry sample,dried and wet sample after boiling;boiled to reduce the glass transition temperature and dynamic storage modulus of degradable epoxy resin based castable and composite;after boiling Drying,the glass transition temperature and storage modulus of the sample recovered,but could not be restored to the uncooked level.It can be seen that the water molecules have a destructive effect on the chemical bond it the cured epoxy resin.Continuous boiling at higher temperatures for a long period of time can cause irreversible damage to the material system,and should be avoided during the use of the material.The degradable composites were tested at room temperature for 2 years,and the interlaminar shear and bending properties were tested at different temperatures.The results showed that the interlaminar shear and flexural strength of the T700SC fiber reinforced biodegradable resin-based composite system decrease with the increase of temperature and the decrease is not large when it was between-15? and 75?,indicating that the material properties are better in the range of-15 ?-75 ?In order to study the effects of long-term exposure of the material system in acid rain or lye,the samples were immersed in hydrochloric acid of pH=2 and ammonia water of pH=13 for 2 years at room temperature,and the interfacial properties were studied.The results show that after immersion in hydrochloric acid for 2 years,the interlaminar shear strength of the sample decreased to 65.9MPa,which decreased by 13.3%.The shear strength of the sample decreased by 55.9MPa and decreased by 26.4%after immersion in ammonia water.Studies have shown that degradable epoxy resin matrix composites have good resistance to acids,especially acid rain,at room temperature,but long-term exposure to alkaline environments should be avoided.At this point,it can be preliminarily judged that the degradable resin-based composite material can meet the performance requirements of the material system for research and development of sports equipment and carbon fiber bicycles under the conditions of long-term high temperature and high humidity and lye immersion.(3)The competitive sports rings and carbon fiber composite bicycle frame were developed based on the degradable epoxy resin matrix composite prepreg,and the performance test was carried out according to the corresponding standards.Tests show that the ring of the degradable epoxy resin matrix composite design and the composite bicycle frame meet the requirements of the International Sports Federation and ISO4210 bicycle performance standards.Practice has proved that the degradable epoxy resin matrix composite material meets the development and application performance requirements of competitive sporting goods.(4)In this paper,a precision balance sensor is used to design and develop a test method for measuring the tensile properties of carbon fiber monofilament by controlling the height of the liquid surface,and named it the Archimedes balance method.The tensile properties of Toray T700SC fiber monofilament were tested by a test device made by the Archimedes balance method.The results show that the test method has good accuracy and stability.The degradation and recovery carbon fiber of the carbon fiber bicycle was tested by the Archimedes balance method.The results showed that the tensile strength of the T700SC monofilament fiber was 3,984MPa,the strength retention rate was 80.4%,and the tensile modulus of the monofilament was 199.7GPa,the retension rate is 87.3%.It can be seen that the carbon fiber degraded and recovered by the degradable epoxy resin-based composite material still has good mechanical properties.(5)The mechanical properties of recycled fiber reinforced epoxy laminates were explored.When the fiber content was about 40%,the longitudinal and transverse tensile strengths of the recycled fiber reinforced epoxy resin sheets were 355 MPa and 249 MPa,respectively.In this paper,the recycled fiber reinforced epoxy resin system material was used in the sub-bearing parts of the competitive sports equipment Vault.The overall performance of the vault has passed the performance test of the International Gymnastics Federation's vaulting performance.The vaulting baffle designed and manufactured using recycled fiber has reached the expected design requirements.In summary,the degradable epoxy resin matrix composite material has excellent comprehensive performance and good environmental corrosion resistance,and the resin degradation is thorough and effective,and the mechanical property retension rate of the recovered fiber mechanical property is high,and has good application value. |
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