This study investigated the internal fibrillation of chemical pulps, with a focus on how the pores in once-dried chemical pulps are reopened during beating. A novel thermoporosimetry technique was used to measure the change in pore size distribution (PSD) and pore volume during drying and beating. This technique is based on the melting temperature depression of cyclohexane in a porous structure. The cyclohexane was introduced into the fibre cell wall thorough a solvent exchange procedure. Nitrogen sorption was used to determine the fibre surface area, and solute exclusion was used to measure the fibre saturation point (FSP). It was shown that the thermoporosimetry technique was able to detect the change in PSD and pore volume during drying and beating. The pore volume measured using thermoporosimetry correlated with the FSP, and it reflects the fibre swelling, though it is lower than the FSP due to the contraction of fibres in cyclohexane. It was also seen that even though the pore volume of previously dried pulps can be recovered by beating (i.e. the pulp can be reswollen), some pores are closed and are not reopened by normal levels of beating. In other words, beating does not completely reverse hornification.
|Number of pages||5|
|Publication status||Published - 2003|
|MoE publication type||A1 Journal article-refereed|