Morphology Development and Melt Linear Viscoelastic Properties of (PA6/PP/PS) Ternary Blend Systems

The morphology development and melt linear viscoelastic properties of PA6/PP/PS (70/15/15) ternary blends were studied. An attempt was also made to predict the morphology development of these blends using the dynamic interfacial tension of the blend components evaluated from the Palierne's viscoelastic model in conjunction with spreading coefficient approach. The blend samples were prepared by melt blending in an internal mixer at temperature of 260°C and rotor speed of 60 rpm. The ternary blend samples exhibited a pronounced low-frequency nonterminal storage modulus whose values were much greater than those predicted for elastic response of the binary blend samples. This was attributed to strong elastic resistance of a core-shell composite droplet formed in the ternary blend samples that was evidenced by the SEM micrographs of these samples. The results predicted based on spreading coefficient concept also suggested a core-shell type morphology in which PP core was encapsulated by PS shell as a composite minor phase dispersed in PA6 matrix. It was demonstrated that there is a close relationship between melt viscoelastic properties and morphology of ternary blends.