Influence of the Surfactant on the Hydrotalcite Dispersion in NBR/LDH Composites Produced by Coagulation

摘要

Dispersions of 10% wt hydrotalcite were prepared by mixing using an ultrasound probe and then incorporated into NBR latex for the purpose of evaluating the influence of the surfactant presence and dispersion stability of the hydrotalcite, both in water and in latex. The surfactant used was Pluronic F-127 and its influence was determined on the size of the agglomerates, the degree of sedimentation and the viscosity of water/LDH dispersions and latex/LDH suspensions. Preliminary results showed the efficiency of the surfactant in promoting dispersion of water/ LDH, presenting lower agglomerate diameter values and increased stability of the dispersion. For the latex/LDH suspension, the viscosity of the system containing surfactant was significantly greater due to a better dispersion of LDH. After coagulation, the systems were examined in detail using X-ray diffraction (XRD) and the results did not show differences in the degree of intercalation, but XRD pattern of LDH was not observed, indicating the breakdown of crystallinity and ordering of the clay crystallites. The ash content showed that the presence of surfactant was an important factor to optimize the incorporation of the clay during coagulation. The estimation of Payne effect from shear modulus indicated a better filler dispersion in NBR matrix when using Pluronic F-127, this behavior was also confirmed by FESEM micrographs.