| The adhesive with heat resistance is widely utilized in many fields, such as in aerospace, auto industry and the electronics, one of which is the epoxy adhesive, which is often used as the matrix of the adhesive with heat resistance, for its cheap cost,high adhesive strength and excellent comprehensive performance. At present, how to synthesis the epoxy adhesive with heat-temperature resistance was the focus of researchers in domestic and foreign countries. However, the theory and method about how to resistant the high temperature for a long time and the mechanization of the adhesive with high-temperature resistance continued to be explored and perfected.This paper prepared a series of epoxy adhesive with heat resistance which used the bismaleimide modified the matrix of the epoxy (EP), added the inorganic filler, used the4,4'-diaminodiphenyl methane (DDM) as the curing agent. The optimal condition for the excellent heat resistance,the kinetics for the cured and decomposed process of the system,technology for the curing and the fracture surface morphology of the cured system were researched by the thermogravimetry (TG),the differential scanning calorimeter (DSC),the Fourier Transform Infrared Spectrum (FTIR) and the Scanning Electron Microscope (SEM).Adopting the TG, with the temperature of the system's decomposition, the system with excellent heat resistance was obtained by the condition:m (EP):m (BMI):m (DDM)=1:0.4:1, stirring30min with300r/min. Then the gelation time and the viscosity of EP/BMI were measured to confirm the temperature of50℃as the temperature of mixing EP with BMI. The kinetics for the cured process of the system was discussed by the DSC. The activation energy of the EP/DDM and the BMI/EP/DDM respectively were40.53kJ/mol and41.77kJ/mol according to the Kissinger Equation. The reaction series of the EP/DDM and the BMI/EP/DDM respectively were0.84and0.86according to the Grane Equation. The appropriate conditions for curing the EP/DDM and the BMI/EP/DDM respectively were127℃/2h+139℃/2h+150℃/2h and60℃/3h+88℃/2h+112℃/2h+121℃/2h according to the T-β. With the Soxhlet extraction method and the Fourier Transform Infrared Spectrum (FTIR), the degree of curing of the BMI/EP/DDM was87.2%, indicating the system was cured well.The TG was used to contrast the temperature of the unmodified system's decomposition with the modified system's. The kinetics for the decomposable process of the system was also discussed by the TG. The result showed that the decomposition temperature of the BMI/EP/DDM was higher than the EP/DDM's15.2℃. The activation energy of the EP/DDM and the BMI/EP/DDM with the different conversion rate was calculated. The result indicated that with the same conversion rate the activation energy and the decomposition temperature of the BMI/EP/DDM were higher than the system of the EP/DDM. In the initial stage of the decomposition, the activation energy increased with the increase of the conversion rate. However, the activation energy decreased with the increase of the conversion rate when the reaction approached to finish. It's supposed that the BMI contained the benzene ring which improved the heat-temperature resistance.The fracture surface morphology of the cured system was analyzed by Scanning Electron Microscope (SEM). The fracture of the EP/DDM was rough, whose cracks were much. The product of the EP/DDM was brittle. The BMI/EP/DDM's fracture was smooth and don't have much cracks. The mechanical property of the material was enhanced. It's supposed that the distance of the amino was shorten by adding the BMI which enhance the toughness.The inorganic filler was added in the system of the BMI/EP/DDM. The viscosity of the system to which Al2O3,SiO2,TiO2,Fe3O4was added was measured by the rotating viscometer so as to discuss the dispersibility of the inorganic filler. With the temperature of the system's decomposition, the decomposition temperature of the AI2O3system which added for mass fraction50%was332.2℃, which was higher than the BMI/EP/DDM's3.5℃; the decomposition temperature of the SiO2system which added for mass fraction40%was342.5℃, higher than13.8℃; the decomposition temperature of the TiO2system which added for mass fraction50%was334.8℃, higher than13.8℃and the decomposition temperature of the Fe3O4system which added for mass fraction40%was337.3℃, higher than13.8℃. At last, the fracture surface morphology of the cured system was analyzed by Scanning Electron Microscope (SEM). We can observe the phase separation. This is because the inorganic filler can't dissolve in the resin, while the disperse of the inorganic filler was preferable. The mechanical property of the material was enhanced. |
PDF Full Text Request