THERMO-RESPONSIVE BEHAVIOUR OF CELLULOSIC MATERIALS

Thermo-responsive hydrated macro-, micro- and submicro-reticular systems, particularly polymers forming hydrogels or similar networks, have attracted extensive interest as they comprise biomaterials, smart or intelligent materials. Phase transition temperature (low or upper critical solution temperature) of the thermo-responsive hydrated reticular systems, which exhibit a unique hydration-dehydration change, is a typical characteristic. The macro-reticular systems with weak bonding are represented by papermaking pulp slurries composed of cellulosic or ligno-cellulosic fibres. During wet pulp beating, it was found that the characteristic decrease of the pulp drainability with increasing the input of beating energy abruptly enhanced if the temperature of the beating pulp slurry was higher than 40 degrees C. Similar observations have been made during pulp slurry drainage at higher temperatures. The drainability of pulp slurries not only improves at temperatures higher than 40 degrees C, but also it tends to be higher than that obtained when decreasing water viscosity only.