Following an evaluatory study of colored cable sheaths versus black cable sheaths the following three results were obtained. (1) The kind of polyethylene used influences the ultraviolet degradation performance of the sheath. Linear low density polyethylene with long side-chain has suitable characteristics for cable sheath polyethylene. (2) The combined use of ultraviolet absorbant and HALS (an ultraviolet stabilizer) results in a significant improvement in weatherability of the sheath. (3) A practical alternative weatherability compound to carbon black has been fabricated and used in the manufacture of cable line sheaths.
The fungal contamination on the surface of the PC tank was studied. The predominant fungi were species of Cladosporium cladosporioides, Penicillium funiculosum, Trichoderma viride, Fusariam moniliforme, Aureobasidium pullulans, Aspergillus, niger and Rhisopus nigricans. The designation of new paintig material not suscepible for fungus growth when coating on the surface of PC tank for long period of time was studied.