The modified imbedded disc retraction method for measurement of interfacial tension in polymer melts

The imbedded disc retraction method is used to estimate interfacial tension in LLDPE/PS system with PS as the imbedded disc. Shape evolution of a disc of one material (PS) imbedded into the matrix of another material is observed (LLDPE). Three to five repetitions at three different temperature levels are observed. The Newtonian model of Rundqvist et al. (1996) for the imbedded disc retraction is modified to include elastic effects. The modified model is derived assuming uniaxial extension, starting with the lower convected Maxwell model. Both the original model and modified imbedded disc retraction model are used in data analysis. The mean values of interfacial tension at 190 °C, 200 °C, and 210 °C are 6.8 ± 0.7 mN/m, 3.9 ± 0.3 mN/m, and 3.7 ± 0.2 mN/m, respectively. A method of estimating whether elastic effects will significantly affect the estimated interfacial tension value during retraction for the given polymer pair is provided. Received: 6 August 1999 Accepted: 2 January 2001