The melt rheological properties and compatibilization effects of an immiscible PP and N6 blends were investigated. Dynamic melt rheological data ( G', G", $η^*$) of PP, N6, and their blends were measured to determine the melt properties. The experimental data were used to predict the interfacial properties from an emulsion theory. To study the effects of reactive compatibilization, the same amount of compatibilizer were added with different blending method (such as single step, reactive two step, and non-reactive two step). Mechanical and thermal properties of compatibilized blends were investigated for the various blending methods. In addition, the morphological analysis was also performed using a scanning electron microscopy.
The melt rheological properties of PP, N6, and their blends show a strong dependence on the composition, frequency of oscillatory shear, compatibilizer contents and blending method. PP and N6 show homogeneous rheological properties. On the other hand, compatibilized blends (with single step) have higher elastic properties than non-compatibilized blends. The predicted values of the interfacial tension by the Oldroyd's emulsion theory decrease as the compatibilizer contents increase. This indicates clearly that the addition of compatibilizer reduces the interfacial energy and enhances the interaction of polymer-polymer interface. Compatibilized blends with PP-g-MAH exhibit very enhanced mechanical properties and finely dispersed morphology. For the practical applications of PP-N6 blends, the melt annealing and water absorption tests were carried out. These tests confirm that the added compatibilizer yields enhanced phase stability and water resistance in spite of strong hydrophilicity of N6. In particular, the reactive two step blends show better water resistance than other type blends.
