High Strength Xylan/chitosan Biobased films prepared in the Presence of Ethanol.

CARLA N. SCHNELL; MARÍA V. GALVÁN; YAMIL N. SOLIER; MARÍA C. INALBON; MIGUEL A. ZANUTTINI; PAULINA MOCCHIUTTI

San Pablo

Encuentro; II EPNAT Encontro de Polímeros Naturais; 2020

CINDEFI; Facultad de Ciencias Exactas UNLP; CONICET

Xylan (Xyl), a natural polymer present in lignocellulosic biomass, was alkaline extracted (150 %NaOH/ wood) from Australian poplar wood and used to prepare films in combination with anothernatural polymer, chitosan (Ch). Films were prepared from colloidal suspensions of polyelectrolytecomplexes (PECs) of Xyl and Ch (60/40 Xyl/Ch mass ratio) by the casting/solvent evaporationtechnique. The effects of different amounts of ethanol (0; 10; 25; 35 and 40% v/v) on the colloidalsuspensions behavior as well as on unwashed and washed films mechanical properties, swellingand water vapor permeability (WVP) were studied. Dynamic light scattering results showed that theparticle sizes of PECs decreased (from 1009 to 594 nm) and the opposite effect occurred with thezeta potential values (from +27 to +68 mV) when ethanol content was increased. All films showedhigher stress-strain at break results than the ones reported in the literature using the samepolyelectrolytes. Particularly, the stress at break of unwashed films increased from 22 to 34 MPawhen they were prepared with 0 and 35% (v/v) ethanol, respectively, while the strain at break wassimilar (31%) for all films. When films were washed, the stress at break was increased even more(from 45 to 75 MPa when 35% (v/v) ethanol was used). The deformation was similar for all washedfilms (approx. 5%). Besides, the best wet tensile-strain properties were obtained (5.1 MPa- 55%)when 35% (v/v) of ethanol was used. Not significance difference was observed in WVP values, butthe swelling capacity slightly increase (11%) due to the presence of ethanol. Results suggest thatthe presence of ethanol favorably modified the interaction between polyelectrolytes. On the otherhand, results show that it is not necessary to remove the residual ethanol used for Xyl precipitationand purification for preparing the films.