In order to improve the solubility and meltability of polyimide (PI), a series of addition thermosetting fluorinated poly(imide-siloxane) copolymer resins (ABIS) were prepared from two kinds of synthesized trifluoromethyl-containing aromatic diamine monomers and 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA), besides, aminopropyl-terminated polydimethylsiloxane (APPS) was chosen as flexible segment, and 3-aminophenyl acetylene (APA) was used as reactive end-capping agent. The structure of ABISs were characterized by proton nuclear magnetic resonance spectroscopy (¹H NMR) and Fourier transformation infrared spectroscopy (FTIR). The solubility, rheological behavior of ABIS and the thermal stability of the cured ABIS were further studied. Moreover, ABIS films were prepared by solution filming, and their physical properties were studied. ABIS resin matrix composites (T300CF/ABIS) were prepared by hot pressing using T300 carbon cloth as reinforcement, and their mechanical properties were also tested. The results show that the introduction of siloxane segment and trifluoromethyl group can significantly increase the flowability and solubility of PI resin systems. The introduction of fluorinated diamine decreases the 5% weight loss temperature (T_d5) of the cured ABIS, but its T_d5 is still higher than 425℃. At the same time, the residual yield at 800℃ (Y_r800℃) of ABIS resins reach 26%. The tensile strength and elongation at break of ABIS films are as high as 15.8 MPa and 65.3%, respectively. In the frequency range of 40 Hz-10⁷ Hz, the dielectric constant (ε) and dielectric loss factor (tanδ) of the PI films are 3.21 and 0.01, respectively, which keep unchanged basically. The contact angle of water on the cured ABIS film is 94°. The flexural strength and interlaminar shear strength (ILSS) of T300CF/ABIS composites can be 137.6 MPa and 16.6 MPa, respectively. The synthesized ABIS resin has promising applications in microelectronic devices and flexible heat-protective composites.

A series of fluorinated polythioetherimide films were synthesized by copolymerization using 4,4′-diaminodiphenyl sulfide (SDA) and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) as diamine monomers, and 4,4′-biphenylene ether dianhydride (ODPA) as dianhydride monomer. The thermal, electrical, optical properties, and water absorption of the PI films were tested. The results show that the PI films have good thermal, dielectric properties and optical transparency. The glass transition temperature of the film is in the range of 240.7-251.6℃, the 5% and 10% heat loss temperature is above 480℃ and 514℃, respectively, and the residual carbon rate reaches 50% at 800℃. Under the frequency of 1 MHz, the dielectric constant of the PI films are 2.27-2.99, the dielectric loss factors are 0.004 7-0.005 6. The highest transmittance of the films reaches 88.75% in the range of visible light, and the water absorption rate is 0.95%-2.26%.

In order to investigate the improving mechanism of polysiloxane with different substituents on atomic oxygen (AO) erosion resistance of polyimide in space environments, reactive molecular dynamics (MD) simulations was used to analyze the AO erosion resistance of PI composited with polyhedral oligomeric silsesquioxane (POSS) with trifluoromethyl (-CF₃) group and methyl (-CH₃) group. The results show that both the composites exhibit strong AO erosion resistance by forming an SiO₂ layer that blocks AO propagation into the polymer matrix and and heat transfer. The PI/CF₃-POSS shows the best performance, and its normalized mass is 0.83 after 35 ps of AO exposure, while the nomalized mass of the PI/CH₃-POSS composite is 0.78.

In order to investigate the arc resistance of coating modified polyimide fabric, a waterborne polyurethane was used as matrix to prepare a barrier thermal insulating coating with SiO₂ aerogel and a reflective thermal insulating coating with TiO₂ filler, and then two coatings were applied on the polyimide fabric, respectively. The effect of filler addition amount and the matrix on the thermal protection performance and rupture performance of polyimide fabric under the effect of fault arc was studied. The results show that the thermal protection performance of the modified polyimide fabric increases with the increase of filler addition, the thermal protection performance of polyimide modified by thermal insulating coating with 6% of SiO₂ and 6% of TiO₂ increases by 34.79% and 21.78%, respectively. Waterborne polyurethane matrix has no effect on the thermal protection performance of polyimide fabrics, but it can make their rupture performances increase by 20%.

Photosensitive polyimide (PSPI) is a kind of high-performance polyimide with special structures, which is widely used in semiconductor packaging, integrated circuits, optical display, and other fields due to its excellent heat resistance, mechanical properties, insulating properties, and lithographic processability. In this paper, the PSPI patents applied in China were taken as object, the overall situation of these patents, including changes in the number of patent applications, applicants, and their source countries was analyzed systematically. Especially, the patent applicants inside and outside China and the patent subject distribution since 2011 were discussed. The difference of patent technology and protection priorities of enterprise applicants inside and outside China was compared in detail. The patent technology characteristics and development trends of PSPI were explored.

Photosensitive polyimide (PSPI) is widely used in electronics, microelectronics, optical display, and other fields. Foreign companies attach great importance to the patent protection of PSPI material formulas and applications. In this paper, the PSPI patents applied by Toray Industries Inc. in China were taken into research, and the changes in the number of patent applications, legal status, technical subject distribution, and other key information were analyzed in detail. Through combining with Toray's representative PSPI products and their applications, the technical development, patent protection strategy, key points of patent technology of Toray were clarified. Based on the above analysis, the technology development trends and application direction of PSPI materials were explored and presented.

In order to study the influence of different interface pressure on the electric field distortion of the composite interface of crosslinked polyethylene/silicon rubber (XLPE/SR) insulation in the cold shrinkable cable intermediate joint, a simulation model of 35 kV cold shrinkable cable intermediate joint was established by the finite element simulation software. The electric-thermal-force field of the composite interface without defects and with metal impurities, circumferential scratches, and longitudinal scratches was simulated and calculated. The results show that the interface pressure has different effects on the joint deformation and electric field strength distortion under different conditions. The joint deformation with longitudinal scratch is more significant, and the field strength distribution at the defect is more obviously affected by the interface pressure. The field strength of the shielding tube is inversely proportional to the interface pressure, and the field strength of the stress cone in the joint with longitudinal scratches is directly proportional to the interface pressure. The overall field strength of the insulation composite interface except for the defects decreases with the increase of the interface pressure.

The insulation status of the cable intermediate joint plays an important role in the safe and stable operation of cable. In view of the immaturity of terahertz imaging technology and the limitation of finite element analysis method, an ultrasonic signal characterization method for typical internal defects of silicone rubber in cable accessories was proposed in this paper. At first, different types of typical defect in silicone rubber were designed by simulation. Then the time-domain characteristic quantity and correlation analysis were carried out on the reflected echoes received in the ultrasonic detection simulation, and the correlation coefficient between the time-domain waveform characteristic quantity and the size and angle of defects was obtained. Finally, an ultrasonic test platform was built on the basis of pulse echo method to carry out ultrasonic test on the flat silicone rubber samples with defects. The results show that the size and angle of the internal defects of silicone rubber have a good correlation with the amplitude peak of the first echo, and the detection results of crack defects are more affected by the angle than that of bubble defects, and the amplitude peaks of defects at different angles are significantly different. It is concluded that the ultrasonic signal can effectively characterize the typical internal defects of silicone rubber in cable accessories.

Metal particle pollutants inside gas-insulated metal enclosed switchgear (GIS) equipment can cause severe electric field distortion, leading to surface discharge of insulators. This paper proposed a method of dielectrically functionally gradient insulator for suppressing metal particles. The electric field distribution around the basin insulator and the motion characteristics of metal particles were simulated. The results show that metal particles released from the shell are affected by the axial electric field force and tend to move towards the insulator. The permittivity distribution of the laminated functionally gradient (ε_L-FGM) insulator decreases in the radial direction, which can homogenize the electric field distribution along the insulator surface and drive away the metal particles by reversing the electric force with the axial electric field. However, the ε_L-FGM insulator enhances the electric field on the surface of the shell, and the jump height of metal particle is 2.7 times higher than those around the uniform insulator. Compared with ε_L-FGM insulator, the ε_T-FGM insulator with a spatial permittivity gradient, which designed based on the topology optimization, reduces the jump height of metal particles and performs better effect in regulating the electric field and expelling the particles.

Silicone rubber composites are widely used in wire and cable, electronic packaging and other fields due to their excellent weather resistance, electrically insulating properties, high chemical stability and other advantages. In this paper, the research progress of filled thermal conductive and electrically insulating silicone rubber composites was reviewed from the aspects of thermal conductive mechanism, influencing factors of thermal conductivity, and strategies to improve the thermal conductivity of silicone rubber composites, and the research prospects of filled thermal conductive and electrically insulating silicone rubber composites were prospected.