Obtenção e caracterização de nanocompósitos de resina epóxi/montmorilonita (MMT) aplicados em tinta em pó

Abstract

The objective of this dissertation is to present a study of the influence of the addition of nanoclays on thermal, morphological, physical and anticorrosive properties of powder coatings epoxy resin based. Polymeric nanocomposites applied of powder coatings with leveis of 2 and 4 % of orgianophilic montmorillonite (OMMT) (w/w) were obtained in the melt state in extruder twin-screw co-rotation at different processing speeds. The powder coatings were applied to carbon steel substrates by electrostatic spraying. The results show that the parameters used for curing (200 °C for 10 minutes) the coatings were satisfactory, exothermic peaks were not observed in thermograms of differential scanning calorimetry (DSC). Thermal analysis showed that the incorporation of OMMT resulted in increasing the temperature of degradation maximum for the samples before curinn, and little influence in coatings after curing, also reduces the reactivity (~H reaction) of powder coatings based epoxy with increasing processing speed (400 rpm). The morphological analysis of X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated the presence of predominantly exfoliated structures for the nanocomposites, with good dispersion of OMMT in the epoxy matrix. The incorporation of th~e leveis of 2 % of OMMT (w/w), for both processing speed, resulted in coatings with improved impact strength, endurance, flexibility and gloss. The coatings obtained with leveis of 4 % of OMMT (w/w) having better performance on the thermal proiPerties and corrosion resistance, as thermal analysis and exposure to salt spray, respectively. Measures of subcutaneous migration made after salt spray teslting indicated coatings with better barrier properties for samples with OMMT, with was corroborated by electrochemical impedance spectroscopy (EIS) results.