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.