Wheat straw fibre is prepared by a thermomechanical (TM) refining system. This study investigated the effects of refining steam pressure (4, 6, 8 and 10 bar) and refiner speed (2500 and 3000 rpm) on the morphology and thermal properties of the resulting fibres. After TM refining, the fibres exhibited more surface irregularities and heterogeneities as well as decreased fibre length. The fine content decreased with increasing steam pressure, but the aspect ratio increased. The findings show that higher steam pressure (8 bar) results in more effective wheat straw refining. Refining lowers the pH. Thermogravimetric analysis showed that TM refining does not influence the thermal properties of wheat straw fibres. Weight loss has to be taken into account upon exposure to temperatures around 170°C. The silica content of the fibres was significantly reduced through refining.
©2008 by Walter de Gruyter Berlin New York