Nanostructural Complex in ABS/TPU Immiscible Mixtures

Abstract

The effects of modified organoclays on mechanical, rheological and mechanical-dynamical properties of acrylonitrile-butadiene-styrene/ thermoplastic polyurethane (ABS/TPU) were studied. ABS/TPU mixtures with 95/5, 75/25 and 50/50 wt.% were reinforced with 5 wt.% Cloisite 10A and 15A. The nanocomposites of the studied mixtures were prepared with an internal mixer at 210 °C following intercalation in the melting process. The intercalation/exfoliation of the silicate layers in the nanocomposites was confirmed by x-ray diffractometry (XRD). The results of thermomechanical-dynamical analysis demonstrated that ABS/TPU mixtures were incompatible. These results also revealed that organoclays have poor molecular interaction with TPU, in such a way that they are homogeneously dispersed in the styrene-acrylonitrile (SAN) of the ABS according to the polarity of the acrylonitrile. Through the viscoelastic analysis, it appeared that the organoclay particles embedded in the ABS/ TPU blend induced the formation of discontinuous nanostructured microdomains. These microdomains were formed by the intercalation/exfoliation of the organoclay particles with SAN, being surrounded by a TPU phase similarly to a core-shell configuration. Studies of the mechanical properties of the mixtures showed that low concentrations of TPU produced higher values of the respective Young's modulus, while higher concentrations of TPU led to practically no changes in the modulus either with or without the presence of organoclays. This was attributed to the molecular sliding of the nanostructured microdomains between the TPU polymeric chains.