New procedure to increase the accuracy of interfacial tension measurements obtained by breaking thread method

The breaking thread method has been widely used to measure interfacial tension between molten polymers. However, various factors can introduce errors in the breaking thread measurements and is very difficult to obtain accurate values of interfacial tension. In this work a new procedure to enhance the accuracy of the breaking thread method is proposed. It consists of using Tomotikaʹs original theory and Tjahjadiʹs et al. numerical simulation of the evaluation of a breaking thread simultaneously to identify fibers with residual stresses. These fibers should not be considered for breaking thread experiment. Also, a new experimental procedure for polymer pairs that cannot normally be tested using breaking thread method is presented. Using these two new procedures the interfacial tension between polypropylene and polystyrene and between polypropylene and polycarbonate was evaluated for temperatures ranging from 200 to 240 °C. It was shown that the accuracy of the method was increased by 28% when compared to the result obtained using one of the both theories, Tomotika or Tjahjadi et al, independently. The results of interfacial tension between polypropylene and polystyrene and between polypropylene and polycarbonate corroborated the results obtained using other methods.