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 pro perties of cellulose acetate phthalate films cast from an aqueous dispersio n 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 dif ferent 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 t ypes of plasticizer increasing the level of plasticizer led to an increase in percent elongation and a decrease ir? tensile strength and elastic modul us. Increasing plasticization time slightly influenced the mechanical prope rties of the fil,ns. The tensile strength and elastic modulus of triethyl c itrate plasticized films were found to be less sensitive to changes in curi ng conditions compared to the corresponding values obtained for diethyl pht halate and triacetin plasticized films. Raising the curing temperature decr eased percent elongation, producing more brittle Jib,ls and thus it was pre sumed that a high curing temperature (i.e. 80 degrees C) may not bf the ide al curing condition for cellulose acetate phthalate coated products.