A fundamental examination of the interactions between thermo-mechanical pulp and water in the presence of alkenyl succinic anhydride

This dissertation presents a rigorous examination of interactions between water, both as a liquid as well as a vapor, and thermo-mechanical pulp (TMP) sized with alkenyl succinic anhydride (ASA). Kraft fiber sized with ASA was used as a comparison standard. Differences in sizing response between the two fiber types were establish using three separate techniques (water drop, single fiber contact angle and FibroDAT), with TMP exhibiting greater sizing at all ASA dosages, as measured by each test individually. Removal of fines from the TMP was found to decrease the sizing at all ASA dosages, but all sizing values remained greater than those of kraft. Solvent extractions were performed, using both acetone and chloroform, and it was found that TMP sized to a much greater degree after extraction, while extraction did not change the sizing response of kraft. Surface analysis by electron spectroscopy for chemical analysis (ESCA) showed an increase in alcohol/carboxyl groups in TMP after extraction and a decrease in hydrocarbon species. ESCA results also showed that both fiber types have approximately equal amounts of potential ASA-bond sites, suggesting that their sizing response should be more similar. Pyrolysis GC/FID was used to measure the amount of ASA retained in sized handsheets of TMP and kraft. It was found that TMP retains a greater percentage of applied ASA in all cases but that refining increased the retention in kraft. Water vapor adsorption tests were performed on both fiber types and it was found that TMP has a larger water accessible surface area than kraft. Water vapor adsorption also showed that TMP tends to have a lower solid surface energy (Wa) than kraft as well as an increase in W a for TMP after extraction, paralleling ESCA. It is concluded that the observed differences in sizing response of TMP are as a result of several factors inherent to TMP. Specifically, these factors are: retention of ASA, fiber fibrillation, fines content, solid surface energy and differences in surface reactive groups.