Use of xylan in polyelectrolyte complexes formulation: a study on adsorption behaviour of xylan/poly(allylamine hydrochloride) onto high quality unbleached fibers

MARÍA S. PERESÍN; MARÍA V. GALVÁN; PAULINA MOCCHIUTTI; MIGUEL A. ZANUTTINI; TEKLA TAMMELIN

Dallas, Texas

Simposio; 247 th American Chemical Society National Meeting & Exposition; 2014

ACS, American Chemical Society

Adsorption of polyelectrolyte complexes (PECs) onto cellulosic fibers is a well studied strategy used to enhance mechanical properties of paper sheets. Traditional PECs formulations include synthetic components, such as poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH). This work investigates the use of xylan in the formulation of PECs, as an abundant and natural alternative for obtaining papers and boards from high quality unbleached fibers with enhanced mechanical properties. Adsorption behaviour of PECs formed by poly(allylamine hydrochloride) (PAH) and 4-O-methylglucuronoxylan (Xyl) onto unbleached softwood fibers was studied as a function of charge ratios (q-/q+: 0.3; 0.5 and 0.8), and ionic strengths (1 mM and 10 mM NaCl), while maintaining a constant pH (7.5). Size and zeta potential measurements of the PECs were determined by using a Zetasizer equipment, and the charge densities by using the polyelectrolyte titration method. The charge densities obtained experimentally were lower than expected when complexes were obtained. Additionally, morphology and structures of the adsorbed PECs layers were investigated using Atomic Force Microscopy. The majority of the PECs were spherical, while some bigger aggregates were also found. Adsorption of PECs on model surfaces was studied by using Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) and Surface Plasmon Resonance (SPR). As indicated by QCM-D results, adsorbed layers were viscoelastic and higher adsorption was observed with increased electrolyte concentration. Highest adsorption value was found at charge ratio 0.5 and 10 mM NaCl. SPR results revealed that a significant portion of the adsorbed layer corresponds to coupled water on the PECs structure.