LLDPE/Proton Exchanged Layered Niobate K4Nb6O17 Nanocomposites

Abstract

Abstract The potassium hexaniobate was synthesized by reacting, in stoichiometric proportions, Nb2O5 and K2CO3 at 1100°C and modified with octadecylamine from an acid-base reaction. Through X-ray diffraction, an interlayer space of 4.27 nm was observed in comparison with 0.79 nm of unmodified oxide; this was also shown by SEM microscopy. The hybrid nanofiller previously obtained was incorporated into LLDPE by melt intercalation (0 up to 10 wt.%) using a twin screw extruder and LLDPE-g-MAH as compatibilizer. From TGA results, all nanocomposites (LLDPE/LLDPE-g-MAH/lamellar oxide) have increased the onset degradation temperature, while the oxide lost during processing for LLDPE/LLDPE-g-MAH/lamellar oxide nanocomposites was higher for the highest content in comparison with LLDPE matrix. According to the Eyring equation, the activation volume of the samples could be calculated using the relationship between the yield strength and strain rate from tensile stress-strain curves. The activation volume decreased with increase of nanofiller concentration, suggesting a good adhesion between the layered oxide and the polymeric matrix for high concentration. This can be attributed to the restricted segmental motion near the nanofiller/polymeric interface, while a poor interaction between them was observed for low concentration. However, the Young's modulus showed a 50% improvement for low nanofiller concentration, especially in the case of 1 wt.% of nanofiller, which was also confirmed by modulus and toughness balance. Considering all the results, it has been revealed that the proton exchanged layered niobate can improve the thermal and mechanical properties of LLDPE/LLDPE-g-MAH/lamellar oxide nanocomposites.