[en] The electron irradiation ground simulation test was conducted on the mechanical property of polyimide film, thermo gravimetric and X-ray Photoelectron Spectroscopy was used to analyze the evolution mechanism of polyimide film in different electron fluencies. It was found that the mechanical properties such as tensile force, tensile strength and rupture elongation of polyimide film increased firstly and then exponentially decreased. The corresponding initial decomposition temperature of the electron-radiated polyimide film lowered from 595 ℃ to 583 ℃ for weight-loss ratio of 10%. From XPS analysis, it can be found that there were ruptures and crosslinks of chemical bonds in the polyimide film. In early stage of electron irradiation, the rupture of C-N bond and the following crosslink increased the mechanical properties of polyimide film; however, along with the increase of electron irradiation, the ruptures of C = O and -N(CO) bonds, formation of C-N bond, as well as release of N were the main factors for the decrease of mechanical properties of polyimide films. (authors)

[en] Relationship between refractive index and packing density of coatings prepared by glancing angle deposition is analyzed and three expressions are given firstly. And then optical characteristics of the graded-index coating, which is deposited as the linear changing of packing density, are discussed from some aspects as positive or negative change, integral periods or have hale period, different periods etc, and more over, the influences of different refractive-index theories on the optical characteristics are compared. Finally, the preparation method, applications and some problem in preparation of the graded coating are discussed separately. (author)

[en] Polyimide (PI) films might be damaged under space high energy particle irradiation. In this paper, the mechanical properties and mechanism of polyimide film is studied with the ⁶⁰Co radiation source, the thermo-gravimetric analysis and the XPS analysis. Significant total dose effect is found in the mechanical properties of the PI film under gamma ray radiation. The tensile strength and rupture elongation of polyimide film increase first and then decrease exponentially with the increase of irradiation dose. The corresponding initial decomposition temperature of the gamma ray-radiated polyimide film changed from 570°C to 590°C for weight-loss ratio of 2%. From XPS analysis, it can be found that there were rupture and crosslink of chemical bond in polyimide film. In early stage of gamma ray radiation, the rupture of C-N bond and following crosslink is for the increase of mechanical properties of polyimide film, and as the increase of radiation, the rupture of C=O and −N(CO)bond, formation of C-N bond, release of N was for the decrease of mechanical properties of polyimide films. (paper)

[en] The mechanical property of polyimide film(PI) in electron, proton, near ultraviolet and far ultraviolet was studied by Φ800 combined space radiation test facility of Beijing Institute of Space Environment Engineering, the degradation of mechanical property of polyimide film was tested by Electronic tensile testing machine. The tensile strength and the rupture elongation of polyimide film decrease with the increase of electron or proton radiation, while tensile strength and the rupture elongation of polyimide film decrease firstly and then increase with near ultraviolet irradiation. (paper)

[en] Irradiation flux is an important parameter to the material irradiation damage investigation, for space material irradiation damage evaluation and the accelerated ground-based test, the irradiation flux effects cannot be ignored. In this paper, the polyimide was set as the research object, the irradiation flux effect and mechanism are investigated by the means of electron paramagnetic resonance test, and based on the free radical dynamic analysis, the dynamics mode of free radical population in vacumm can be established as a function of irradiation time (or proton irradiation flux). The results show that the free radical anneal process in vacuum follows the exponential mode, and the characteristic time constant τ_r_a_d_i_c_a_l_-_v_a_c_u_u_m is about 1.9 h. Furthermore, a simplified method is proposed with the investigation of the free radical behavior of the irradiated surface modification polyimide (TiO_2/PI), and the characteristic time constant τ_b_u_l_k is 1.9 h, which is almost the same to the value of τ_r_a_d_i_c_a_l_-_v_a_c_u_u_m.