Effect Of Gamma Ray Irradiation On Mechanical Properties Of Polyurea Materials

This article aims to explore the influence of ?-ray irradiation on the quasi-static and dynamic compression mechanical properties of polyurea.Modified MDI(component A)and Versalink P1000(component B)are selected to prepare a new type of polyurea material.,Set the irradiation dose rate to be 1KGy/h,2KGy/h,3KGy/h,and the cumulative dose respectively 20 KGy,60KGy,100 KGy,150KGy,220 KGy,300KGy gamma ray irradiation conditions,using infrared spectrometer The performance of the synthesized polyurea was characterized,and the compression mechanical performance test(0.01s-1-4200s-1)of the compression specimen before and after the irradiation was carried out by a universal testing machine(0.01s-1-4200s-1),and the scanning electron microscope was used.The microstructure morphology of polyurea was observed,and the deformation behavior of polyurea under different strain rates and different irradiation conditions and the law of the influence of irradiation on the mechanical properties of the new polyurea were studied.The microstructure of polyurea before and after irradiation was studied by Fourier Infrared Spectrometer.The analysis showed that: the synthetic polyurea in this study has no obvious isocyanate absorption peak near 2262cm-1,at 3352.59cm-1,1713.43cm-1,1541.04cm-1,1097.76cm-1 has the secondary amine group NH bond in polyurea,C=O bond in urea bond,C—N bond and C—O—C bond stretching vibration absorption peaks,indicating that polyurea has been synthesized.After gamma-ray irradiation,there is no new absorption peak or the disappearance of some peaks.There is no peak shift compared with the unirradiated curve.Under the set gamma-ray irradiation dose rate and cumulative dose The molecular structure of the polyurea sample did not change much,and there was no major damage.The microscopic morphology of polyurea was observed by scanning electron microscopy images.The results showed that the soft and hard segments of the polyurea before and after irradiation had significant microphase separation structures due to the thermodynamic incompatibility.The hard segments are dispersed in the continuous soft matrix phase.After irradiation,more and more small white micro-regions appear as the irradiation time increases,which is caused by the embrittlement of the soft segment.The law is consistent with the appearance change of the irradiation test results.Under the same radiation dose rate,as the cumulative dose increases,the color of the compressed specimen changes from light yellow to dark red.When the same cumulative dose is reached,the color of the compressed specimen gradually increases as the dose rate increases.From dark to light,it is observed from the cold brittle section of liquid nitrogen that the color change is smaller the closer to the center of the test piece,and the color change is greater the closer to the outer surface of the test piece.Through quasi-static compression and dynamic compression experiments,the stress-strain curves of unirradiated polyurea at different strain rates are obtained.The results show that the true stress-true strain curve of polyurea elastomer has significant strain rate sensitivity,and the strain is 0.1 The stress increases from 4.626 MPa at 0.01 s-1 to 15.209 MPa at 4200 s-1.The compressive strength increases with the increase of strain rate,and it has significant strain rate sensitivity.Through quasi-static compression and dynamic compression experiments,the stress-strain curves of polyurea under different strain rates when the cumulative radiation dose is 220 KGy at three dose rates are obtained.The results show that when the dose rate of 2KGy/h and 3KGy/h reaches 220 KGy under different strain rates,the elastic modulus and the stress in the high elasticity stage and the densification stage are stronger than that of the non-irradiated polyurea,and 2KGy/h Time is the best;1KGy/h is the worst and is lower than unirradiated polyurea.The 2KGy/h radiation dose rate with the best compressive stress was selected to analyze the influence of cumulative dose on the compressive mechanical properties of polyurea.The study showed that the elastic modulus and high elasticity stage and densification stage under low strain rate when the cumulative dose reaches 300 KGy The stress is the best,and the elastic modulus at 0.01 s-1 is 11% higher than that of unirradiated;at high strain rate,the stress corresponding to 0.1 strain after irradiation is greater than that under unirradiated conditions,and the It reached the maximum at 150 KGy,and increased from 15.209 MPa without irradiation to 24.733 MPa at 4200 s-1,an increase of 38%.?-ray irradiation can improve the compressive mechanical properties of the new polyurea.Under the working conditions of this study,the 2KGy/h dose rate can reach the 150 KGy cumulative dose to maximize the compressive mechanical strength of the polyurea.