Recyclability of a layered silicate–thermoplastic olefin elastomer nanocomposite

A multiple-pass study was undertaken with a layered silicate–thermoplastic olefin elastomer (TPO) nanocomposite to study the impact of processing history on the properties of the material. A set of 10 passes were completed through a co-rotating intermeshing twin-screw extruder with samples collected to monitor changes in the composite. The microstructure of the nanocomposite was characterized using TEM, XRD, FT-IR, steady and complex shear rheology, and mechanical testing. With progressive passes through the extruder, the TPO nanocomposite experienced both delamination of the organoclay as well as thermo-oxidative degradation. The onset and extent of degradation were found to be unaffected by the presence of the organoclay species in the polymer, though, inclusion of a maleated compatibilizer led to increased chain scission. The generated carbonyl groups along the polymer chain as a result of oxidation were speculated to have a significant effect on the developing percolating network of clay within the material and on the final rheological properties of the composite. Despite the occurrence of degradation in the nanocomposite during recycling, its rheological and mechanical properties remained significantly higher than those of the unfilled resin.