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
Effects of Al(OH)_3 on the performances of silicone rubber
Effects of the particles size and amount of Al(OH) 3 on the leakage current,current pulse,tracking resistance,electrical corrosion,dielectric properties,tensile strength,average roughness of the surface ,and repetitiveness of the experimental data of leakage current as a function of time in cycle of cured silicone rubber were summarized.
The isolation of barium and calcium diketo-l-gulonates and the biological significance of 2:3-diketo-l-gulonic acid.
To explain their observation that dehydro-l-ascorbic acid mutarotates in aqueous solution, Herbert, Hirst, Percival, Reynolds & Smith (1933) postulated the formation of 2:3-diketo-l-gulonic acid as a result of the gradual opening of the lactone ring. Their subsequent work and that of others have fully sup-ported this theory, although Ghosh & Rakshit and Rosenfeld have suggested an alternative mechanism. An outstanding characteristic of mutarotated solutions is that they solutions by reduction with HI. In other the indication is that the ring closure effected in vitro does place in vivo. The use of mutarotated solutions in these biological experiments some of uncertainty and it was obviously to employ the pure substance which