Property 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, four different nanotubular fillers 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 halloysite and carbon nanotubes. Morphological characterization in SEM and STEM/TEM showed dispersion in the polypropylene matrix. According to TGA and DSC measurements thermal behavior 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. 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. Finally, the oxygen transmission rate increased for all samples showing high barrier properties only for samples containing natural and functionalized halloysite nanotubes.

Chemical Modification of Halloysite Nanotubes for the Preparation of Nanocomposites on Non Polar Matrix

“…An important case of gas permeability reduction using HNTs in a polymer matrix was developed by Monsiváis-Barrón, achieving a 66% reduction in oxygen permeability with polypropylene, with only a 3% weight load of halloysites [5]. The previous work had been one of the reasons that inspired this work to similarly achieve a significant reduction in the permeability of CO 2 in a PET matrix.…”