Reactive Processing of Polypropylene-Clay Nanocomposites with Silanes

摘要

It is well known that both surfactant and functionalized polypropylene must be added for dispersing nanoclay in polypropylene. The interaction between the oxygen atoms on the clay surface and the polymeric compatibilizer must be stronger than the interaction between the clay surface and the surfactant in order to obtain delamination of the silicates. In addition, using a surfactant with greater thermal stability during the compounding process yields a better quality of dispersion. Even after the nanolayers are dispersed in the polymer melt, the morphology obtained is not thermodynamically stable and will coarsen upon annealing or during extrusion, molding and thermoforming. Restacking of the platelets will lead to deterioration in properties such as barrier to vapors and flame retardance of the nanocomposite. Interfacial interactions and the thermal stability of the surfactant in the galleries can be enhanced by changing the head group structure -using a primary ammonium ion surfactant (R-NH_3~+) instead of a quaternary ammonium ion surfactant and to a lesser extent by increasing the number of long alkyl tails in the quaternary ammonium ion.