By Liz White, ERJ staff
Boulder City, Nevada-Amerityre Corp. says that independent tests show that in heat ageing and ozone performance, its polyurethane tyre compounds, â€œhave outperformed comparable rubber compounds.â€ Such tests offer an intitial prediction of a tyre's potential for long term durability.
The developer of polyurethane tyres said that the US National Highway Traffic Safety Administration (NHTSA) has been studying the effects of ozone exposure and tyre heat build up and aging on tyre performance.
According to Amerityre, NHTSA intends to propose an oven-ageing test for FMVSS 139, the safety standard relating to highway-use tyres, to take effect July 2007.
Amerityre says these results â€œare significant in that they demonstrate that its polyurethane compounds show minimal changes in physical properties as a result of extended exposure to heat and ozone.
The 70 Shore A PU material had a hardness increase of 0-2 percent after 70h at 100Â°C, while hardness of comparable rubber compounds increased from 12-20 percent. In 50pphm ozone, the PU had no cracking after 144h, while the rubber compounds had initial cracking after 30h.
Use of Amerityre's polyurethane materials, â€œcan be expected to produce a tyre with better and more consistent performance,â€ according to Richard Steinke, Amerityre's president and ceo.