| Silicone pressure sensitive adhesive (PSA) has good heat resistance, chemical resistance, insulation and adhesion of the surface too difficult to stick; it is widely used in electric machines and appliances, automotive, aerospace, medical and some other fields. In recent years, with the continuous progress of science and technology, researchers tried to modify silicone PSA by various methods, in order to adapt to the new requirements of silicone PSA in all fields. Appearance of nanomaterials, provides a new direction for polymer-modified work. Although the information about nanomaterials modified silicone pressure sensitive adhesive is so less, we can reference the research results of nano-materials modified other polymers. We hope it can improve the thermal or electrical properties that using nanomaterials modified silicone PSA.This article used commercially available silicone PSA for the substrate, with the modified agent of nano silicon dioxide (SiO2) and montmorillonite (MMT), which respectively treated by silane coupling agents and octadecyl quaternary ammonium salts, BPO as curing agent, prepared nano-SiO2/MMT modified silicone PSA with solution blending methods, under the action of ultrasonic oscillations. The microstructure of nano-particles dispersed in solvents of methylbenzene and alcohol was observed by Scanning Electronic Microscope (SEM). Thermal properties of modified silicone PSA were measured by thermal weight loss method. A kind of three-layer soft insulation material was made by glass cloth, mica paper, PI film and the modified adhesive. We studied the influences of amount of nano-SiO2and MMT on electrical properties of the soft insulation material, through testing the breakdown voltage and volume resistivity of composite materials. The study results showed that, the dispersion of nanoparticles after surface treatment in solution of methylbenzene and alcohol was improved. Adding nano-SiO2/MMT into silicone PSA, obviously improved the apparent decomposition temperature (Td) of silicone PSA. When total doping content was1wt%, quality ratio of SiO2/MMT was1:2, Td of silicone PSA reached the maximize561℃, which is64℃higher than before modification. The breakdown strength test showed that adding nano-SiO2/MMT made the breakdown strength of composites decline, but the breakdown strength value is still far higher than that of electric field which is required to insulation material liner insulation and insulation wrapped; The volume resistivity test of composite materials showed that can make the volume resistivity increases by controlling doped quantity and proportion of the two kinds of nano material. The lowest volume resistivity of this test is8.87×1012Q·m. Although it is slightly lower than the volume resistivity12×1012Ω·m of unmodified silicone pressure sensitive adhesive, it still meet the requirements for insulating materials in application field. |
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