Correlation of Morphology and Mechanical Properties of Novolac Phenolic Resin/Clay Nanocomposites Prepared via SolutionMixing Method

jahanmard, Parisa; shojaei, Akbar

Melt mixing method for preparing polymer nanocomposites is appreciated mostly due to the commercial availability of the equipments, However, this method often suffers from poor dispersion of nanoparticles. Alternatively, solution mixing method is so efficient to obtain uniform dispersion of nanoparticles within the polymeric matrix. More recently, researchers have investigated the dispersion state of organoclay in novolac phenolic resin, but the literature is so sparse concerning the mechanical performance of such nanocomposites prepared by solution mixing method. Therefore, the primary aim in this study was to take into consideration the role of nanoclay on the mechanical properties of novolac type phenolic resin nanocomposite produced by solution high shear solution method. To do this, two different types of clay based on sodium montmorillnote including unmodified Closite Na+ and organically modified clay (Closite 30B) both from Southern Clay were used. Methanol was used as a solvent and the mixing was performed at different conditions including simple mixing of constituents in the solvent, mechanical mixing by homogenizer followed by sonication. Both clays were added to the phenolic resin at various contents from 2.5 wt% up to 20 wt%. The dispersion state was investigated using XRD, SEM and TEM. The mechanical properties were determined using tensile, flexural and DMTA tests. The analysis showed that both clays lead to higher mechanical properties compared to neat novolac phenolic resin. However, the resin filled with Closite 30B was found to be much effective. The theoretical analysis based on the Halpin-Tsai model revealed that the dispersion as well as the polymer-filler interaction is much higher for the Closite 30B).