Study on Anti-tracking Properties of Unsaturated Polyester Resin SMC

A method of thickening hydroxyl-terminated unsaturated polyester with polyurethane (PU) that comes from the reaction between diisocyanate compounds and polyglycol is introduced, and the effect of PU prepolymer on the anti-arc properties of the sheet molding compounds (SMC) is studied according to the standard of ASTM, the electric strength is tested in the transformer oil under 423K, 453K, 473K, 523K respectively. The anti-tracking properties of UP-SMC were developed when Al(OH)₃ and diisocyanate compounds were filled in UP-SMC. The microstructure of UP-SMC struck by electric arc was observed by means of SEM (Scanning Electron Microscopy). The results show that UP-SMC samples with no anti-tracking modification have some part of ablation and charring while the modified sample are with the low electric rot. The arc breakdown time would increase with the usage of PU. The SMC thickened by PU shows good aging resistance as well as anti-arc properties, it will be widely used on electrical parts and arc-deflecting cover of AC switch etc