Influence of mercerization on the dynamic mechanical properties of bamboo, a natural lignocellulosic composite

Bamboo fibers that have been treated in NaOH solutions of varying concentrations were subjected to differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) studies, respectively. The moisture desorption peak (and the enthalpy values associated with it) was moved to higher values as the alkali concentration increased up to 15% and shifted to lower values beyond that temperature. A broad exotherm was observed in all of the DSC curves for alkali treatments up to 15%. Beyond that concentration, two comparatively smaller exothermic peaks appeared for the 20% and 50% alkali- treated samples. DMTA study of bamboo strip samples reveals that the room-temperature value for the storage modulus (E') of the untreated bamboo strips is increased by similar to 400% in the case of 15% alkali-treated samples, and the rate of decrease in the modulus over the temperature range of 140-180 degrees C is also maximum for those samples. The untreated bamboo samples show a primary loss modulus (E'') peak at 111.8 degrees C, which is shifted to higher temperatures for alkali- treated samples. The damping parameter (tan delta) is also maximum for untreated samples.