Modificação das propriedades da poliamida 12 pela incorporação de carbonato de cálcio nanoparticulado

Polyamide 12 (PA12) was modified by incorporating calcium carbonate nanoparticles (NPCC) to analyze the effect of the filler content on the mechanical and thermal properties of the final nanocomposites. Compositions containing 0.1, 0.2, 0.5, 1, 5 and 10 wt% of Socal 312 and 10 wt% of Socal U1S2 were analyzed. Furthermore, extruded and non-extruded PA12 were compared. NPCC was characterized through BET analysis (Brunauer, Emmett and Teller), which confirmed that Socal 312 had a specific surface area superior to Socal U1S2. Scanning electron microscopy revealed a tendency of the particles to agglomerate at 1 wt% NPCC and higher. However, all samples showed good distribution of the filler throughout the matrix. Differential Scanning Calorimetry (DSC) analyses did not show differences in the melting temperature of the compositions. Crystallization temperature tends to increase as the amount of filler in the matrix increases. Crystallinity degree showed differences only when comparing extruded and non-extruded PA12, the same occurs with Socal 312 in relation to Socal U1S2 containing 10 wt% of filler. Thermogravimetric analysis (TGA) showed that for contents from 0.5 wt% NPCC, increasing NPCC content reduces the thermal stability of the material. Muffle calcination tests confirmed the residues content obtained with TGA at 5 wt% NPCC higher, and evidenced good distribution of the filler along the specimen. Tensile and flexural strength and tensile and flexural modulus started increasing at 1 wt% NPCC and HDT started increasing at 0.2 wt% NPCC, showing the reinforcing effect of nanofiller and the increase in stiffness of the materials. Impact strength at 23 °C decreased at 0.5 wt% NPCC. Impact strength at -40 °C reduced only with addition of 10 wt% NPCC. Strain at break, toughness and impact strength at 23 °C showed reduction in extruded PA12 when compared to non-extruded PA12, possibly because extrusion favors the increase in crystallinity, as verified in the DSC analysis. Socal U1S2 also showed differences in relation to Socal 312 in strain at break, flexural modulus and HDT, probably due to its lower specific surface area in relation to Socal 312. Therefore, the incorporation of 1 wt% NPCC in PA12, already allows to obtain a nanocomposite with greater mechanical strength compared to neat PA12, which can be a feasible alternative for applications where an increase in mechanical properties is desired