Major Manufacturers Testing Ekoprena

Two years ago Sumitomo Rubber subsidiary Dunlop Falken Tyres Ltd releases the Enasave 97, a tyre containing only three per cent petroleum derived materials. The substance enabling this close to total freedom from synthetic rubber in the Ensave 97 is Ekoprena, an epoxidised natural rubber. Significant development work on compounds based upon this rubber has been undertaken by TARRC, the UK based laboratory operated by the Malaysian Rubber Board. TARRC’s consultancy arm, Rubber Consultants, recently attended Tire Technology Expo in Germany and reported on the latest Ekoprena developments.

“There has been an awful lot of interest from all major manufacturers. We have supplied quantities for testing,” stated Rubber Consultants’ Gail Reader. At present Sumitomo is the only tyre manufacturer commercially producing tyres containing Ekoprena; the Japanese manufacturer first used the substance in the Enasave ES801, a 70 per cent petroleum free tyre released in 2006. The rubber used in this tyre and in the Enasave 97 is the silica-filled Ekoprena 25, a 25 mole per cent epoxidised natural rubber.

Ms Reader explains that epoxidation – that is, a reaction that yields an epoxy compound – increases chemical polarity. In the case of Ekoprena it enables high interaction with silica, which leads to lower rolling resistance in the tyre. Furthermore, epoxidation increases the rubber’s glass transition temperature, a quality that contributes to high wet grip.

Incidentally, another tyre related field in which Rubber Consultants is engaged is the testing for aromatic oils. “Rubber Consultants (TARRC’s consultancy unit) is now UKAS accredited to ISO17025 to conduct testing to BS ISO21461:2006,” Reader elaborates. Our testing determines aromaticity of oil in vulcanised rubber compounds. As you know, high aromatic oils are now banned in tyres in accordance with EU Directive 2005/69/EC, 16th November 2005.  From 1 January 2010 rubber products are not allowed to contain these aromatic oils which contain polyaromatic hydrocarbons (PAHs) or polynuclear aromatics (PNAs). These tests are carried out at Rubber Consultants’ upgraded NMR (nuclear magnetic resonance) facility. “The fact that NMR is the recommended test means TARRC is one of the few laboratories worldwide to offer this service, which carries ISO17025 accreditation,” Reader comments.