Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE Effect of graphene nanoplatelets and zirconia on the thermomechanical properties of the composite.

ABSTRACT
This study aimed to evaluate the effects of graphene nanoplatelets (GNP) and zirconium oxide (ZrO2) as fillers in polypropylene (PP) composites. Different concentrations of GNP (0.01, 0.10, and 0.50 wt.%) and ZrO2 (0.50, 1.00, 2.50 wt.%) were evaluated. Composites were characterized by morphological analysis by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), tensile and flexural tests. TGA showed that ZrO2 improved the thermal stability of PP, increasing T5% from 410.5°C (neat PP) to 452.0°C, and T50% from 452.9°C to 479.1°C when modified with 2.5 wt.% of ZrO2. GNP promoted an increase in crystallinity up to 10.6% compared to neat PP, while ZrO2 increased by up to 16.2%. Mechanical tests showed that tensile and flexural strength did not have significant variations. DMTA results showed that the incorporation of nanoparticles increased stiffness by reducing molecular segmental mobility and enhanced the viscoelastic stability of PP across the entire temperature range. Through SEM/EDS microscopy, it was possible to observe the presence of Zr in the composites containing ZrO2 and O in the composites reinforced with GNP.