Microbiological growth testing of polymeric materials: an evaluation of new methods

Biofilms growing on high voltage insulators made of silicone rubber cause changes in appearance and properties of the silicone material. This study presents the design and building of microenvironment chambers simulating outdoor environment and the use of these for long-term studies of the development of mixed biofilms on silicone rubber materials. Results from the microenvironment chambers are compared to standard test procedures used in combination with new methods to evaluate the effect of two common flame retardants, ATH and zinc borate, on the development of a biofilm. Algae, bacteria and fungi isolated from silicone rubber insulators collected from Tanzania, Sri Lanka and Sweden, respectively, were used in the tests performed. Results show that zinc borate has a protective effect against all the microorganisms tested.