Blendas de poli(tereftalato de etileno) e poliamida 66 modificadas com sepiolita
Abstract
Blends of recycled bottle-grade polyethylene terephthalate and virgin polyamide
66 (PET/PA66) with different compositions (75/25, 50/50, 25/75) unfilled and filled
with 5 phr of sepiolite clay (Sep) were investigated. These blends were prepared
in a twin-screw extruder and injection molded as standard specimens.
Transmission electron microscopy (TEM) revealed that PET/PA66 blends with
compositions of 75/25 and 25/75 showed matrix-droplet morphology, while the
blend with a 50/50 composition showed double emulsion morphology. Sepiolite
showed good dispersion and distribution in neat PA66 as well as in the PA66
phase of the PET/PA66 50/50 blend. Temperature-modulated differential
scanning calorimetry (MDSC) showed that the overall melting enthalpies of
molded PET/PA66 blends follow an additive behavior compared to the neat
polymers, with PA66 crystallizing to a greater extent than PET. The addition of
sepiolite decreases the melting enthalpy of neat PA66, with little effect on the
overall melting enthalpy of the blends. The mechanical behavior of PET/PA66
blends in the tensile test is greatly influenced by the blend composition and
sepiolite addition. Blends with PET as matrix and those with double emulsion
morphology show brittle fracture while PA66 as matrix leads to ductile behavior.
The addition of sepiolite increased the strength and decreased the ductility of the
blends. Notched Izod impact strength data follow a similar trend, the blends with
PET as matrix showing lower values. In general, this study demonstrated that
sepiolite-based PET/PA66 blend nanocomposites are a sound strategy for the
enhancement of the mechanical properties of recycled bottle-grade PET.