Extensional flow properties of externally plasticized cellulose acetate: Influence of plasticizer content

Abstract

Elongational flow properties of polymer melts are very important for numerous polymer processing technologies such as blown film extrusion or foam extrusion. Rheotens tests were conducted to investigate the influence of plasticizer content on elongational flow properties of cellulose acetate (CA). Triethyl citrate (TEC) was used as plasticizer. Melt strength decreaseswhereas melt extensibility increases with increasing plasticizer content. Melt strength was further studied as a function of zero shear viscosity. Thetypical draw resonance of the Rheotens curve shifts to higher drawdown velocity and the amplitude of the draw resonance decreases with increasing TEC content. With respect to foam extrusion, not only are melt strength and melt extensibility important but the elongational behavior at low strain ratesand the area under the Rheotens curve are also significant. Therefore, elongational viscosity as well as specific energy input were calculated and investigated with respect to plasticizer content. Preliminary foam extrusion tests of externally plasticized CA using chemical blowing agents confirm theresults from rheological characterization. © 2013 by the authors; licensee MDPI, Basel, Switzerland.