MICRORHEOLOGICAL STUDY OF RECYCLED POLYPROPYLENETHE WITH MONTMORILLONITE CLAY AND MALEIC ANHYDRIDE
polymer nanocomposite; linear viscoelasticity; recycled polypropylene; montmorillonite clay; maleic anhydride
The aim of this work is to investigate the effect of incorporating organophilic montmorillonite clay (OMMT) and polypropylene grafted with maleic anhydride (PP-g-MAH) on the linear viscoelastic rheological behavior of recycled polypropylene (rPP) from mineral water bottles. The polymer nanocomposites were plasticized and homogenized in a twin-screw co-rotational extruder with d = 16 mm and l/d = 40, varying in 1, 3 and 5 wt% of OMMT and using 3 wt% of PP-g-MAH. After mixing, type I specimens were injection molded, according to ASTM D638. To analyze the microrheological behavior, measurements of fluidity index (MFI), parallel plate rheometry and scanning transmission electron microscopy (STEM) were performed. For the mechanical properties, uniaxial tensile and Shore D hardness tests were carried out. To obtain the physical properties of the material, the X-ray diffractogram (XRD) was used. The MFI proved that the addition of OMMT and PP-g-MAH promoted significant modifications in the rPP, being possible to evidence the decrease in the fluidity index proportional to the increase of the clay concentration in the mixture, consequently, an increase in the viscosity. The rheological data obtained at low frequencies in the region of linear viscoelasticity, revealed significant changes in the rheological behavior of the polymer composites when compared to the rPP. XRD showed signs of OMMT exfoliation in the polymeric matrix. Using STEM, the interaction of clay and PP-g-MAH in the rPP matrix was observed. Tensile and Shore D hardness test showed improvements in mechanical properties.