THE EFFECT OF LONG-TERM TREATMENT AT 100-DEGREES-C-150-DEGREES-C ON STRUCTURE, CHEMICAL-COMPOSITION AND COMPRESSION BEHAVIOR OF CORK

The effects of heating of cork in air at 100-degrees-C and 150-degrees -C for up to 42 days have been studied. Dimensional and mass changes i nduced by heat treatment were measured and the chemical composition wa s analysed. The thermal degradation of cork is small for short periods of treatment but increases with time and temperature. Cork looses aft er 42 days of treatment 6.8 % of its mass at 100-degrees-C and 19.9 % at 150-degrees-C. Cork extractives and polysaccharides were found to b e the most temperature labile components. The cellular structure, obse rved by scanning electron microscopy, did not change with treatment in these conditions. Compression curves of untreated and heat treated co rk samples were obtained, which show an increase of compression streng th upon heating for short exposure periods and a decrease for longer o nes. The changes observed in the compression behaviour of cork treated at 100-degrees-C and 150-degrees-C were related to the chemical compo sition changes induced by heat treatment.