COMBINED EFFECTS OF GLYCEROL/SORBITOL PLASTICIZERS ON THE PROPERTIES OF CNF FILMS

PONCE DE LEÓN, AGUSTINA; EHMAN, NANCI; RODRÍGUEZ LUJÁN PATRICIA; FELISSIA, FERNANDO ESTEBAN; AREA, MARÍA CRISTINA

Congreso; XII Iberoamerican Congress on Pulp and Paper Research 2022 (CIADICYP); 2022

This study aimed to evaluate the effect of plasticizers on the properties of cellulose nanofibers (CNF) films. CNF was produced from ECF bleached commercial pulp by TEMPO-oxidation and mechanical fibrillation. The films were obtained by a solvent casting technique and dried at 50°C. The mixtures included the CNF suspension with glycerol/sorbitol (G/S): 0G/50S, 10G/40S, 20G/30S, 30G/20S, 40G/10S, and 50G/0S. Further, for evaluation of the effect of drying temperature, samples 50G/0S were dried at 25°C (air drying), and 60°C (oven-drying). The film characterization comprehended physical-mechanical properties, optical behavior, water absorption, water vapor barrier (WVP), and aerobic biodegradation in the soil (period: 25 days).The film thicknesses obtained were in the range of 23.0-65.0 μm. All films except those dried at 25°C showed air bubbles (Figure 1. a). The incremental drying temperature increased the diameters of air bubbles: 587-875 μm (50°C), and 627-1167 μm (60°C). The highest temperature developed more quantity of air bubbles. The transmittance at 600 nm values was reduced with the addition of plasticizers, obtaining decreases of about 26% in 50G/0S films, and 7% for 0G/50S. The plasticizers addition decreases the E modulus values in all cases showing that the elasticity increases with the addition of the polyols. The highest decrease was for the application of 50% w/w of glycerol with a reduction of 92.7% (E=0.36 GPa). The opposite effect occurs with sorbitol, where the E modulus values are higher as the sorbitol load increases (E= 0.87 GPa for 50% w/w sorbitol).The plasticizer addition influenced the barrier properties. The samples containing glycerol decreased their WVP as the percentage added increased until reaching a minimum with the load of 50% w/w glycerol (43.5 g/m2 day kPa). The sample with only 50% w/w sorbitol did not vary significantly from the control (WVP=201g/m2 day kPa). The water absorption decreased for plasticized films, the decrease being greater with increasing sorbitol load (up to 30.4% decrease for 0G/50S sample). The biodegradation of the films after 25 days reached values about 50% in weight loss. Although no significant difference was observed between samples, upper values were obtained for glycerol higher content films.