Rheological behaviour of fibre, particle and strand mats

The rheological behaviour of fibre, particle and strand mats is important d uring pre- and hotpressing of wood-based panels. The relaxation, creep and regeneration behaviour of mats (without resin) with densities varying from 300 to 1100 kg/m(3) was determined at temperatures of 20, 80 and 140 degree sC and moisture contents of 0 and 14%. The temperature and moisture distrib ution of the mat was homogenous. During the relaxation test the stress redu ction is higher at lower temperature and moisture contents compared to high er temperature and moisture contents. A complete stress reduction is not po ssible at any combination of temperature and moisture during a relaxation t est lasting 2 minutes. The creeping of the mats is enhanced with increasing temperature and moisture content. The rise in stress after a sudden reduct ion of the mat density decreases with increasing temperature.