THE EFFECTS OF PLASTICIZERS ON CRYSTALLINITY, PERMEABILITY, AND MECHANICAL-PROPERTIES OF METHYLCELLULOSE FILMS

The effects of plasticizers (polyethylene glycols [PEG] 400, 1,450, 8,000 and 20,000, glycerol [G] and propylene glycol [PG]), 30% dry basis, on the physical properties of methylcellulose (MC) films were investigated. With the exception of PG, plasticizers with low molecular weights (G and PEG 400) caused the largest increase in the d101 spacing of the crystal lattice. All plasticizers significantly (alpha = 0.05) increased oxygen (O2P) and water vapor permeabilities (WVP) of the films as compared to that of unplasticized MC, with PEG 400 having the greatest effect on O2P and G having the greatest effect on WVP. With the exception of PG, all plasticizers decreased the tensile strength of MC films, with PEG 400 causing the largest decrease. With the exception of PG and PEG 400, all plasticizers increased percent elongation values of MC films, with PEG 1,450 having the greatest effect. Glycerol and PEG were the most effective plasticizers for MC. The higher molecular weight plasticizers do provide some plasticizing properties and may be more suitable for applications that require a lower permeability to water vapor than can be achieved with glycerol.