| Epoxy resin is one of the indispensable basic materials because of its good adhesive properties,electrical insulation properties,corrosion resistance and mechanical properties.But its poor temperature resistance,brittle fracture and poor toughness have limited its application in many high-tech fields.Toughened epoxy resin has been one of the research hotspots in the field of polymer science and engineering.As a representative thermoplastic,polyetheretherketone(PEEK)fiber,because it contains both ether and ketone bonds,has good physical properties,chemical resistance,and thermal properties.PEEK modified epoxy resin can be effective Improve the toughness and structural strength of epoxy resin.Graphene is a new type of two-dimensional carbon nanomaterial,which has excellent mechanical properties.Adding it to the modified resin matrix as a reinforcing material can further improve the comprehensive mechanical properties of the resin matrix.Aiming at the problem of poor toughness of epoxy resin,this paper uses bisphenol A epoxy resin E51 as the matrix and adopts GNP/PEEK composite modification method to study the toughening of epoxy resin.PEEK/E51 and GNP/PEEK/E51 modified resin systems were prepared.The non-isothermal DSC test was used to study the curing behavior of the modified resin.The temperature of the curing process was determined by extrapolation.By utilizing the methods of kissinger,pressure parameters such as surface activation energy ea of the fixation system were obtained.Using the transformation method of friedman et al.,the kinetic equation of the autocatalytic model was established.The activation energy of the PEEK/E51 system was studied with the non-model fitting method as the degree of curing increased.The infrared spectroscopy method was used to study the curing reaction mechanism of PEEK/E51 epoxy resin system.For PEEK/E51 epoxy resin system,the effect of PEEK content on the mechanical properties of modified resin was studied.When the PEEK content was 6%,the tensile strength,elongation at break,flexural strength,and compressive strength of the PEEK/E51 modified epoxy resin system reached 71.44 MPa,4.05%,129.87 MPa,and 124.11 MPa,respectively,compared to Pure epoxy improved by 33.66%,81.61%,33.83% and 10.05%.Using DMA research methods to study the molecular structure characteristics of PEEK/E51 modified epoxy resin system.The results show that the introduction of PEEK reduces the regularity of the resin matrix,enhances the molecular chain’s ability to move,improves the toughness of the epoxy resin,but reduces the glass transition temperature of the epoxy resin.The surface of the graphite oxide was pretreated with Tween 80 surfactant to prepare a uniform graphene dispersion,which was added as a nano-filler to the modified resin matrix to obtain a GNP/PEEK/E51 composite material.The effects of different GNPs contents on the tensile properties,bending properties,and compressive properties of GNP/PEEK composite toughened resin systems were studied using an electronic universal testing machine.When the GNPs content is 0.15%,the comprehensive mechanical properties of GNP/PEEK/E51 composites reach the best.The tensile strength,elongation at break,bending strength and compression strength were 80.43 MPa,4.31%,147.98 MPa and 130.96 MPa,respectively.The morphology of tensile fracture of PEEK/E51 and GNP/PEEK/E51 resin systems was observed by scanning electron microscope.The analysis found that PEEK toughening mainly relies on the pull-out bridging mechanism of PEEK particles and shear yield.The addition of GNPs further improved the fracture mechanism of the PEEK/epoxy resin cast body.The layered graphene structure formed a network structure in the resin matrix.Relying on the deflection of cracks and supplementing the defects of the resin matrix,the epoxy system was enhanced.tough. |
PDF Full Text Request