Study On Pmma Modified Oxide And Its Reinforcement Of Ethyl Cyanoacrylate Adhesive

Ethyl cyanoacrylate（ECA）adhesive,due to its high transparency,fast curing speed and single component,has received more and more attention in the field of polymer.However,ECA has poor mechanical properties,stability,and viscosity,which limits its further application in other fields.In recent years,silica（SiO₂）nanomaterials are used as inorganic nanomaterials with excellent strength,good chemical resistance and environmental friendliness for adhesive reinforcement and toughening.However,the hydroxyl groups of SiO₂ are prone to agglomeration and can trigger the premature polymerization of ECA.In view of this,this thesis will focus on the modification of SiO₂ nanomaterials and their reinforcement and toughening of adhesives by introducing different structural nanomaterials to compound with SiO₂ and pre-disperse SiO₂from the perspective of improving SiO₂ dispersion and mechanical properties of adhesives.Polymethyl methacrylate（PMMA）is used to modify the surface of the composite material to prevent the premature polymerization of ECA,and at the same time achieve high dispersion of SiO₂ and excellent mechanical properties of the adhesive.The main research contents of the thesis are as follows:（1）PMMA-SiO₂ nanocomposites were prepared by generating PMMA on the surface of SiO₂ nanoparticles.When 5%PMMA-SiO₂（PMMA∶SiO₂=3∶1）nanocomposite is added to ECA,the adhesive has the best tensile shear strength of 17.6 MPa and tensile strength of 8.5 MPa,which are significantly improved compared to 13.7 MPa and 1.5 MPa of pure ECA adhesive.At the same time,the curing time of the adhesive is increased by 12 hours,and the thermal decomposition temperature is increased by 35°C.SiO₂ can be used to disperse stress by preventing cracking,while the formation of hydrogen bonds with ECA can increase the crosslink density and improve the mechanical properties of the adhesive.PMMA can also be interspersed in the adhesive network to increase the cross-link density and improve the thermal and mechanical properties.The addition of PMMA-SiO₂ proves the feasibility of inorganic filler reinforced ECA adhesives and establishes the basis for nanocomposites reinforced adhesives.（2）Al₂O₃（w）nanowires were prepared by structural design,and Al₂O₃（w）-SiO₂（Aw S）nanocomposites were prepared by in situ growth of SiO₂ on the surface of Al₂O₃ hydroxyl groups.PMMA-Aw S nanocomposites were prepared by modification of Aw S with PMMA.When 5%PMMA-Aw S（PMMA∶Aw S=1∶1）nanocomposite is added in ECA,which Aw S contains 9%Al₂O₃,the tensile strength of ECA adhesives can reach 26.2 MPa and tensile shear strength can reach 19.3MPa.The curing time of the adhesive is increased by 12 hours,and the thermal decomposition temperature is increased by 40°C.Under the joint action of Al₂O₃（w）and PMMA,the dispersion of SiO₂ is excellent,and the effect of stress dispersion is better.The cross-linking density is significantly increased,which enhances the heat resistance of the adhesive.Al₂O₃（w）provides a new direction for force transmission,and the tensile shear strength of the adhesive is the best compared with other adhesives.（3）Carboxylate CNTs were prepared by chemically modifying carbon nanotubes（CNTs）,and CNTs-SiO₂（Ct S）nanocomposites were prepared by in situ growth of SiO₂ on the surface of CNTs.PMMA-Ct S nanocomposites were prepared by modification of Ct S with PMMA.When6%PMMA-Ct S（PMMA∶Ct S=2∶1）nanocomposite is added in ECA,which Ct S contains 6%CNTs,the tensile strength of ECA adhesives can reach 29.3 MPa and tensile shear strength can reach 17.6 MPa.The curing time of the adhesive is increased by 12 hours,and the thermal decomposition temperature is increased by 40°C.Under the joint action of CNTs and PMMA,the dispersion of SiO₂ is excellent,and the effect of stress dispersion is better.At the same time,CNTs provides a new direction for force transmission,and the tensile shear strength of the adhesive is the best compared with other adhesives.CNTs can increase the cross-linking density of the adhesive and improve the heat resistance.