Strahlenchemische Veränderungen an Polyvinylchlorid bei Einwirkung von Kobalt-60-Gammastrahlung
The role of air oxygen in the radiochemical changes of polyvinyl chloride was investigated. A polyvinyl chloride emulsion polymeride with a K value of 60 to 65 was used as a sample. It was radiated in the form of powder, films, and massive cylinders in high vacuum and in air. The total viscosity of the powders undergoes, after irradiation in vacuum, a slight deterioration at doses up to 5 x 10/sup 6/ r but at higher doses a lattice-like polymerization occurs. In irradiation in air the color of the sample does not vary, but in vacuum a brown color occurs. The behavior of massive cylinders is quite different from that of powders after irradiation. There is no variation in the total viscosity after irradiation in air and vacuum. Decomposition was observed up to doses of 5 x 10/sup 5/ r, then an increasing lattice-life polymerization and insolubility occurred. A red color is observed after doses of 3 x 10/sup 5/ r and it deepens with increasing irradiation doses. Film irradiated in air was not colored, but coloration occurred in vacuum irradiation. (J.S.R.)
Irradiation of Polymers by High-Energy Electrons
THE interaction of high-energy radiation with various forms of matter has been shown to produce a variety of chemical effects, depending upon the system. These effects fall into various classes, among which are oxidation and reduction, polymerization and depolymerization. Recently, Charlesby and Little have reported the cross-linking of polymers by high-energy radiation1–3.
The structure of electricity demand in the Brazilian household sector
Abstract The present structure of residential electricity demand is analysed by electricity consumption classes and end-uses. Nearly 70% of households consume less than 150 kWh/month and are responsible for 35% of total residential demand. Other determinants of electricity-use, such as income and place of residence, are also discussed. It is found that electricity demand is increasing faster than income as the country reaches appliances saturation in upper consumption levels. Water heating and refrigeration account for the major part of residential consumption. Residential conservation efforts have started introducing more efficient lighting equipment and refrigerators, but further work will have to be done to speed up the diffusion of efficient technology at costs that can be paid by consumers.