Synergistic effects of organoclay Cloisite 15A on recycled polyethylene terephthalate

Abstract

In this work, composites of recycled polyethylene terephthalate (PET-r) and organoclay Cloisite 15A (C15A) were strategically obtained by the intercalation method in the molten state. The synergistic effect of C15A with the recycled PET matrix was evaluated using different concentrations of C15A (1, 3, 5, and 7% wt). The influence of the C15A organoclay concentrations on rheological and thermal properties was investigated and corroborated with morphological observations. Both X-ray diffraction results and scanning electron microscopy analysis revealed that the obtained PET-r composites present a high degree of intercalation. The relaxation times measured from nuclear magnetic resonance also confirmed the synergistic interaction between the clay lamellae and PET-r matrix. The compatibility of the C15A with the polyester matrix is verified for the higher clay additions (5–7% wt) from the improved rheological properties in comparison to the neat PET-r. The higher C15A content (7% wt) provided an increment of 7 °C in the glass transition temperature and better thermal stability with an 11 °C increase in the composite degradation temperature. These beneficial results are associated with the higher number of processing cycles during the recycling and molding steps, which favor the chain size breakage and, thus, the clay lamellae are better dispersed in the PET-r matrix.