Efeito da modificação superficial com descarga de corona em filmes de nanofibra de pinus e eucalipto

Abstract

Investigations have shown that corona treatment is promising for quality improvement of fabrics and composites. There are no reports on its effectiveness for surface modification of nanofibril films for printing and packaging purposes. This investigation aimed to evaluate the film properties with the evolution of corona discharge exposition on eucalyptus and pinusnanofibril films. Cellulose nanofibrilswere produced from commercial bleached cellulose pulps of both species through 30 passages in a SuperMasscolloider Grinder. Films were formed by casting method. The corona discharge treatment was applied for 10, 30, 60 and 300 s, at a distance of 3 cm. Furthermore, the duration of the surface modification was evaluated after 6, 24, 48, 72 and 96 h. Corona discharge promoted formation of hydroxyl, carbonyl and other functional groups by the breakage of C-C bonds and subsequent reaction with oxygen. The best corona treatment time was 30 s, for which maximum water vapor permeability of 13.1 g.mm/KPa.day.m² and 14.2 g.mm/KPa.day.m² was found for the eucalyptus and pinus films, respectively. In addition, maximum water absorption (of around 35%) was observed for films of both species treated for 30 s. The tensile strength increased by increasing corona treatment exposition. Pinusnanofibril films showed better performance than eucalyptus nanofibril films due to higher crystalline index and nanofibril dimensions. Through the analysis of contact angle and surface energy, it was verified that printing of corona treated nanofibril films should be carried out up to 24 h where the films still exhibit the effect of the treatment.