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.)
Änderung einiger Eigenschaften des Polyvinylchlorids durch ionisierende Strahlung
Various polyvinyl chlorides were exposed to x and gamma radiation from 1O/sup 2/ io 1O/sup 6/ r in air. One series of samples was irradiated in vacuum. The viscosity of dissolved samples, the dieleciric properties, and the breakdown voltage of the irradiated polymers were determined. (J. S. R.)
Finite Difference Modeling on the Temperature Field of Substrate in Friction Surfacing
Friction surfacing is an advanced process of great potential, especially in the field of repair and reclamation of worn and damaged components. As a kind of thermal processing technology, the temperature profile and changes of the substrate in friction surfacing are important factors to get coatings of high quality. In this paper, the temperature field of the substrate during the process is simulated by finite difference method. The results are consistent with experiments, reappearing the temperature change of the substrate during friction surfacing, allowing further study on figuration and quality of coatings.