Studying the effect of modified cellulose nanofibers on the functional properties of poly (lactic acid) based biodegradable packaging

The aim of this research was the use of Cellulose nanofibers (CNF) to improvement the properties of Poly (lactic acid) (PLA) biopolymer in order to increasing its applicability in food packaging. In order to improving the compatibility and miscibility with PLA matrix, CNF were treated by oleic acid. The resultant modified nanofibers (MCNF) were subsequently introduced into a PLA polymeric matrix and the effect of nanofiller on barrier, mechanical and optical properties of the polymer was studied. The morphology of fracture surface evaluated by scanning electron microscopy confirmed the uniform dispersion of MCNF at low levels. However, higher levels of MCNF (12%wt) causes to decreasing the uniform dispersibility and agglomeration of nanofibers. By adding MCNF, water vapor permeability decreased from 9.05×10-5g/m.h.Pa for pure PLA film to 6.96×10-5 g/m.h.Pa for PLA film containing 8% MCNF. Also the oxygen and light transmittance barrier properties improved by addition of MCNF. At the MCNF content of 12wt%, the tensile strength and Young’s modulus of the nanocomposites increased by 2.5 and 2 folds than those of pure PLA films respectively. However, addition of MCNF, caused to decrease in lightness and brightness and increase in yellowness of PLA films.