Disintegration polyester resin

To cite a practical example, 20% by mass of 12/mi diameter glass fibre coated with silver (70 nm thick) mixed in a thermosetting polyester resin gave a composite conductivity of 2.5 x 104fi-lm 1. From Equation (8.37) the calculated value is 5.3 x 104fl-lm-1, which compares reasonably well with the experiment, if one takes into account that some disintegration of the fibre is inevitable in the mixing process. 

The ether groups, the benzene rings, and, when present, the aliphatic hydroxyls in the cured epoxy system are virtually invulnerable to caustic attack and extremely resistant to acids. In the case of the phenolic resin, the sodium phenolate formed is readily soluble and when present will cause the ultimate disintegration of the resin chain. In the case of the polyester, the ester linkage is hydrolyzed back to the original alcohol and salt of the carboxyl group. The chemical inertness of the cured epoxy system is enhanced by the dense, closely packed structure of the resinous mass, which is extremely resistant to solvent action. 

Concrete flooring in the brine area is liable to disintegration by brine, and it is protected by coating with materials such as magnesium or zinc fluosilicate, epoxy or silicone penetrating sealers, and drying oils. Concrete surfaces exposed to mechanical wear are treated with 3- to 6-mm thick epoxy surfacing materials. Sumps and trenches employ reinforced polyester or epoxy resin systems. 

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