The ASTM G21-15 standard, developed by the American Society for Testing and Materials (ASTM), describes a test method for determining the effect of molds on the properties of synthetic polymeric materials in the form of molded and fabricated products, tubes, rods, sheets, and film materials. Changes in optical, mechanical and electrical properties are determined by applicable ASTM methods.
The method described in the ASTM G21 standard is a qualitative test method that uses high concentrations of spores from five different fungal species to determine the resistance of synthetic polymeric materials to fungal growth.
Fungi are generally unable to break down the main resin component of the synthetic polymer for use as a source of carbon (sugar). However, many additives such as plasticizers, cellulose, lubricants, stabilizers and colorants added to impart desired properties are very susceptible to microbial growth.
As fungi settle by breaking down easily digestible components, the acids they produce as byproducts of growth make the resin a more useful food source. Like using lighter fluid to ignite coal, the additives act as a quick burst of energy that unlocks the power stored in the polymer resin.
The ASTM G21 standard was first published in 1990 to test the resistance of synthetic polymers to fungal attack.
Examples of polymers tested using ASTM G21 include, but are not limited to, compounds such as polyethylene and polypropylene, polyurethane, vinyl/polyvinyl chloride (PVC), thermoplastic polyurethane, thermoplastic, polyester, polycarbonate, and rubber. These can be in the form of films, sheets, molded materials, coatings, foams, tubes, pipes, discs, tiles, slabs, rods, and the like. Other materials such as paint, drywall, cardboard, fibers and adhesives can also be tested using the method described in the ASTM G21 standard.
During testing, samples are placed on an agar medium that does not contain carbon (no readily available energy source) but contains essential mineral salts necessary for the growth of fungi. Having a carbon-free environment forces the fungi to grow on the test sample and not on the surrounding agar surface.
Among the numerous test, measurement, analysis and evaluation studies it provides for businesses in various sectors, our organization also provides standard testing services for determining the resistance of synthetic polymeric materials to fungi, within the scope of ASTM G21-15 standard, with its trained and expert staff and advanced technological equipment.
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