Influence of plasticization and curing conditions on the mechanical properties of aqueous-based cellulose acetate phthalate films

The influence of plasticization and curing conditions on the mechanical properties of cellulose acetate phthalate films cast from an aqueous dispersion of Aquacoat CPD was investigated. Cellulose acetate phthalate dispersions containing diethyl phthalate, triethyl citrate or triacetin at four levels,were plasticized for either 1 or 24 h. The films were then dried using different curing conditions (40 degrees C for 24 and 48 h, 60 and 80 degrees C for 12 and 24 h). The mechanical properties of the films (tensile strength at break, percent elongation at break and elastic modulus) were evaluated. Results showed that triethyl citrate as a plasticizer yielded softer films with lower values of tensile strength and elastic modulus. For all three types of plasticizer increasing the level of plasticizer led to an increase in percent elongation and a decrease ir? tensile strength and elastic modulus. Increasing plasticization time slightly influenced the mechanical properties of the fil,ns. The tensile strength and elastic modulus of triethyl citrate plasticized films were found to be less sensitive to changes in curing conditions compared to the corresponding values obtained for diethyl phthalate and triacetin plasticized films. Raising the curing temperature decreased percent elongation, producing more brittle Jib,ls and thus it was presumed that a high curing temperature (i.e. 80 degrees C) may not bf the ideal curing condition for cellulose acetate phthalate coated products.