Byline: Liz White
How so you make polyurethane parts that are more renewable? This is a question that many PU businesses would like an asnswer to, and Sonderhoff Chemicals, based in Cologne, Germany, has been busy devising one route.
Sonderhoff claims its new approach, using natural fibre and polyurethane (PU/NF), gives a part with 67 percent ‘green’ content, of which 40 percent is flax fibre, and the rest is polyols derived from natural oils (NOPs).
Volker Welsch, who is head of development at Sonderhoff Chemicals, said natural fibres give low mechanical strength compared to glass fibre-reinforced thermoplastic polyamides or epoxy-fibreglass composites, but their additional advantage lies in their lightness.
Natural fibres have comparatively low density, which for flax fibres is about 1.45g/cm³or 37 percent lighter than fibreglass (2.3g/cm³).
Natural fibres leave no sharp edges when they break, unlike fibreglass and carbon fibres, which is important in vehicle crash performance, Welsch said, in a presentation at the 6-7 Oct 2011 meeting of the FSK, the German association for makers of foamed plastic and polyurethane, held in Wolfsburg, Germany.
In addition, energy costs for making natural fibres are significantly lower than for fibreglass. Since CO2 is bound in the fibres, this leads to a much better CO2-balance with natural fibres.
Sonderhoff worked with Reimer Modellbau as a process specialist with many years experience in processing natural…