Abstract
In order to evaluate the durability of paint layers exposed to simultaneous action of climatic and electrical stresses, the influence of 50 Hz electrical field and of aging by thermal cycling on the resistance to the action of molds of some painting materials was evaluated by specific microbiological determinations. Comparative measurements were carried out on initial paint samples and samples aged by applying of 1000 successive thermal cycles (between –38oC and 85oC, with the duration of a cycle of 90 min), exposed to Czapek-Dox culture media (with and without sucrose), inoculated with a salt solution containing approximately 106 mold spores (of 10 different species), and incubated at 30±2oC and RH 90±5%. It was found that for the samples exposed to a controlled field of 5V/cm and 50Hz the resistance to the action of molds is almost two times less than in the absence of the disruptive electric field. Also, it was noticed that the field of 5V/cm and 50Hz stimulates the growth of Aspergillus niger, but completely inhibit those of Trichoderma viride and Aspergillus flavus.
Keywords: painting materials; epoxy resins; polyurethane resins; thermal aging; molds; biodeterioration