Abstract:
The objectives of this research were to study the effects of various treatments to Nata pulp on the physical properties of the Nata films. Three following treatments were used : 1) purification with 2% (weight by volume) sodiumhydroxide at 100℃ for 1 hr, 2) sulfuric acid treatment (at 1.25-5% by volume and 100℃ for 30 min) after purification, and 3) steam treatment (at 586 kPa for 1-5 hr) after purification. The method used for film casting was modified from ISO 5269/2 (1980.) The physical properties of films casted from unpurified/purified Nata long-fiber pulp mixture at various long-fiber contents were also studied. The results showed that the films of unpurified Nata pulp had apparent density of 912.33 kg/m³, Youngs modulus of 8040.34 MN/m², elongation of 2.33%, tensile index of 56.31 kN.m/kg, tear index of 1.98 N.m²/kg, burst index of 4.25 MN/kg, and brightness of 41.53%. The purification of Nata pulp resulted in the increasing of burst index (34%) and brightness (24%) of films. The sulfuric acid treatment at 1.25-5% by volume decreased by Youngs modulus, elongation, tensile index, tear index, and burst index of films by 37, 46, 45, 58 and 57%, respectively. The steam treatment up to 5 hours did not affect the mechanical properties of films, while the apparent density of the films was increased, but the brightness of the films was decreased. For the films of unpurified/purified Nata - long-fiber pulp mixture, tear index, brightness, water vapour permeability, and oxygen gas permeability were increased, while Youngs modulus was decreased as long-fiber pulp content increased. The values of elongation and burst index of either Nata pulp film or long-fiber pulp film were higher than those of mixed pulp films. Tensile index of purified Nata pulp film was higher than that of long-fiber pulp film, which was higher than that of the mixed pulp films.