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, obse rved (LLDPE). Three to five repetitions at three different temperature leve ls are observed. The Newtonian model of Rundqvist et al. (1996) for the imb edded disc retraction is modified to include elastic effects. The modified model is derived assuming uniaxial extension, starting with the lower conve cted Maxwell model. Both the original model and modified imbedded disc retr action model are used in data analysis. The mean values of interfacial tens ion at 190 degreesC, 200 degreesC, and 210 degreesC 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 interfacia l tension value during retraction for the given polymer pair is provided.