Plastics – Evaluation of the action of microorganisms
This standard has 4 methods for determining the deterioration of plastics due to the action of fungi, bacteria, and soil microorganisms by visual examination, changes in mass, and/or changes in other physical properties.
Method A: Fungal Growth Test
Method A is suitable for the assessment of the inherent resistance of plastics to fungal attack in the absence of other organic matter. Test specimens are exposed to a mixed suspension of fungus spores in the presence of non-nutritive medium. The fungi can only use the test specimen as a food (nutritive) source. If the specimen contains no nutritive component, the fungi cannot thrive and there is no deterioration of the plastic.
Method B: Determination of Fungistatic Effects
Method B is performed when surface contamination is expected. Test specimens are exposed to a mixed suspension of fungus spores in the presence of a complete medium, i.e. with a carbon source. Even if the plastic does not contain any nutritive elements, the fungi can grow over the specimens and attack the material via their metabolic products.
Method C: Resistance to Bacteria
The action of bacteria on the test specimens is assessed using an incomplete medium. If there is no growth in the agar around the specimen, then the specimen does not contain any nutritive components.
Method D: Resistance to Microbially Active Soil
Method D is performed on plastics that are used in permanent contact with soil and exposed to high humidity. Test items are completely buried in soil. After incubation, items are examined visually and/or tested for physical properties such as surface gloss, impact resistance, and hardiness.
*MicroStar Lab does not perform these physical properties test. If they are required, MicroStar Lab can return them to the customer for testing or work with an outside lab.