Effects of thermoplastic poly(ether-ester) elastomer and bentonite on properties of recycled poly(ethylene terephthalate)

The synergistic effects of thermoplastic poly(ether-ester) elastomer (TPEE) and bentonite nanoclay on mechanical, morphological, thermal, and dynamic mechanical properties of recycled poly(ethylene terephthalate) (R-PET) were investigated. The efficiency of TPEE as impact modifier for the R-PET was evidenced by a significant increase in the impact strength and elongation at break with increasing TPEE contents (from 10 to 30 wt%), while the tensile strength and Young’s modulus exhibited an opposite trend. The 70/30 (wt%/wt%) R-PET/TPEE blend was selected as an optimum formulation for further blending with a very low loading of bentonite (1−5 parts per hundred of resin, phr) using the same processing techniques (extruding and injection molding). X-ray diffraction and transmission electron microscopy revealed that the 1 phr bentonite nanocomposite exhibited an exfoliated structure with the highest improvement in the mechanical properties compared with other nanocomposites and the unfilled blend. Meanwhile, the nanocomposites with 2, 3, and 5 phr bentonite formed tactoid or agglomerated bentonite morphology. Differential scanning calorimetry, thermogravimetric and dynamic mechanical analyses demonstrated a noticeable increase in the crystallization temperature, a comparable thermal stability, and a slight increase in the glass transition temperature, respectively, of all nanocomposites when compared with those of the neat R-PET. Graphical Abstract