X-RAY PHOTOELECTRON-SPECTROSCOPY OF CHEMITHERMOMECHANICAL PULP GRAFTED WITH POLYACRYLONITRILE

X-ray photoelectron spectroscopy has been used in order to follow the chemical changes of chemithermomechanical pulp (CTMP) fiber surfaces as the polyacrylonitrile (PAN) grafting level increases, from 0 to 45%. The peak synthesis reveals that C1s peaks of the ungrafted and grafted CTMP samples are made up of three components - C1, C2 and C3 - while the C1s peak of the pure polyacrylonitrile is made up of only two C1 and C2 components and the N1s peaks are made up of two N1 and N2 components for both the CTMP grafted samples and the pure PAN. The binding energies of the C1s components C1 and C2 of the grafted and non-extracted samples as well as those for the grafted and extracted samples are almost equal to those of the C1s peak of the pure polyacrylonitrile within +/- 0.2 eV. The surface chemical modification of the CTMP fibers as a result of grafting is very well illustrated with diagrams representing the atomic oxygen and nitrogen fractions versus the grafting level. Indeed, an increase of nitrogen (f(N)) and a decrease of oxygen (f(O)) fractions is observed after polyacrylonitrile grafting, demonstrating a very good correlation between the fiber's surface chemistry composition and the level of the grafting. A linear relationship between the nitrogen fraction of the grafted fibers vs. the percentage of grafting is observed in the case of the soxhlet extracted grafted samples but not for the grafted non-extracted samples, an indication of the effectiveness of the soxhlet extraction.