Propertiy Relationship in Organosilanes and Nanotubes filled Polypropylene Hybrid Composites

Abstract

Polypropylene composites with different filler contents were prepared by creating a masterbatch containing 3% wt. filler. A variety of silanol groups were used to synthetized three compounds in different media trough a sol-gel process with acetic acid, formic acid and ammonium hydroxide as catalysts. Besides, three different nanotubular structures were also used to analyze their behavior and compare it with the effect caused by the silanol groups. These tubular structures comprise: unmodified halloysite, carbon nanotubes and functionalized carbon nanotubes. Morphological characterization in SEM and STEM/TEM showed dispersion in the polypropylene matrix. According to TGA measurements, polypropylene filled with functionalized carbon nanotubes is the composite exhibiting better thermal properties. DSC measurements show the presence of two main peaks for temperatures of melting and crystallization which remain similar for all the composites. Mechanical test in tension demonstrate that modulus of the composites increases for all samples with a major impact for materials containing silanol groups synthetized in formic acid. The oxygen transmission rate increased for all samples with exception of samples containing halloysite. Finally, rheological measurements show a significantly increment in viscosity for samples containing unmodified and modified carbon nanotubes. No difference was found for samples containing silanol groups and halloysite when compared to neat polypropylene.