Damage Behavior Of PI Film Under Coupling Effects Of Stress Filed And Charged Particle Irradiation

Polyimide film materials because of excellent comprehensive performance, hasbeen widely used in aerospace and other fields, and they have wide applicationbackground and irreplaceability. But the spacecraft in the process of the operationservice, will be irradiated by charged particles, stress field, such as the role ofenvironmental factors, these can cause damage to the material, make the materialperformance degradation. Because of the particularity of the spacecraft, the mat erialappeared after the damage is irreparable, so it is necessary to study the damage ofpolyimide materials.This paper studies protons, electrons these two charged particles irradiation andunder the condition of the interaction of these two charged particles and the stressfields, the paper researched combination mechanical properties of polyimidedamage and optical performance degradation. Then by EPR electron paramagneticresonance technology we research sample defect free radical formation and thedifferences of evolution mechanism of aging. Using XRD, IR and Raman spectrarevealed the sample structure and functional changes, and the sample surfacemorphology is studied through SEM and the change of the fracture surfacemorphology, reveal the macro mechanical properties, optical properties and theconnection between the micro defects, as well as the difference between sampledamage behaviors under different conditions.Studies have shown that Proton irradiation with electron irradiation onmechanical properties and optical properties of materials will be reduced, and theywill form the pyrolytic carbon free radicals. But the proton irradiation has moreinfluences on performance. This research further proves that the displacement ofirradiation damage is the chief reason for the free radicals produced in the sample.Proton irradiation samples which are after the tensile strength and elongation atbreak decreased obviously, and the fracture will behavior a certain change. Near thefracture strip crack appeared, but the trend of the decrease of the sample along withthe change of irradiation influence is not so big, this is mainly associated with theproduction of free radicals defects. After electron irradiation, the sample alsoperformance fell, but not as after proton irradiation falling, this suggests that theionization injury is not the main reason for the radical defects.Proton irradiation and stress field coupling are relative to irradiate the sample,mechanical properties and optical properties of the sample appear relatively rising.The tensile strength of the samples after the coupling effect is rising, and opticaltransmittance and elongation at break compare with the irradiated samples, the gaps with the original are smaller than the samples before, irradiation degradation effectunder the action of applied strain was diminished；Compared the two couplingspecimens under the action of free radicals content declined, with an array ofpreferred orientation of molecular chain, this is mainly in the process of applyingstrain, within the sample molecular chain can have from basic disorderly state toorderly arrangement, and the effect of strain causes a radical composite faster, toreduce the content of free radicals, and improve the mechanical properties andoptical properties of the sample。Electron irradiation and the tensile strength ofsamples after the coupling stress field has obvious rise, optical properties changedlittle, this is because the ionization less defects induced by free radicals, under theaction of strain, further accelerated the speed of composite, and the molecular chainof preferred orientation, which leads to higher tensile strength and elongation atbreak decreased.