(Rubber News report)
Lake Geneva, Wisconsin – Trostel Ltd. has developed an ASTM-compliant antifungal EPDM rubber bellow compound that can replace rubber as a sealant in some applications, with washing machines at the top of the list.
Trostel said the compound was developed specifically to be used in situations where rubber is called on to operate in a high-humidity, high-ambient temperature environment, such as door seals on front-loading washing machines.
Basically, it's a change in the recipe for EPDM rubber, according to Greg Vassmer, chief technology officer.
As the popularity of front-loading washing machines increases, many customers have complained about mould and mildew developing on door seals.
“We set out to solve one of the important problems facing consumer appliances today – the creation of a safe, durable, fungus-resistant, injection-mouldable rubber,” Vassmer said.
He said the material has been tested and developed to the point that the company now can begin getting it specified into customers' products.
It can be used for any kind of appliance, Vassmer said, although it was initially developed as a way to handle the washing machine seal problem.
Trostel's scientists synthesized more than 20 iterations of the compound, completing extensive testing each time, before finding the right mix.
Once they finalised the antifungal compound, they put together four versions of recipes before determining the most effective one to survive functional and fungal tests.
The testing process for the new antifungal EPDM compound was extensive, said Vassmer. Tests included ASTM standard G21 – a US industry standard test for seals covering resistance of synthetic polymer materials to fungi – that requires the EPDM compound to be held at 28-30°C with 85 percent relative humidity for four weeks.
At the same time, the compound was exposed to aspergillus brasiliensis, penicillium funiculosum, chaetomium globosum, trichoderma virens and aureobasidium pullulans in a nutrient-rich environment, simulating the worst conditions for mould buildup inside a front-loading washing machine.
After four weeks of exposure, the new EPDM exhibited no fungal growth per ASTM international standards and demonstrated it prevents mould issues.