Propertiy Relationship in Organosilanes and Nanotubes filled Polypropylene Hybrid Composites

Polypropylene composites with different filler contents were prepared by creating a masterbatch containing 3% wt. filler with polypropylene (PP). Three compounds with different silanols groups were synthetized in different media trough a sol-gel process where the acetic acid, formic acid and ammonium hydroxide were the different catalysts used to develop such process. Besides, three different nanotubular structures were also used to analyze their behavior and compare it with the impact caused by the silanols groups. These nanotubes comprises: unmodified halloysite (HNT) and carbon nanotubes (CNT) as well as functionalized carbon nanotubes (CNTF). Morphological characterization in SEM and STEM/TEM show the dispersion in the PP matrix. According to TGA measurements CNTF is the composite with better thermal properties when all samples are compared. DSC measurements show the presence of two main peaks for all samples were temperatures of melting and crystallization remain similar for all the composites. Mechanical test in tension demonstrate that modulus of the composites increases for all samples but with major impact for PP containing silanols groups synthetized in formic acid and the lowest improvement was achieved for sample containing the silanols groups synthetized in base media. The oxygen transmission rate increased for all samples with exception of samples containing HNT. Finally, rheological measurements show a significantly increment in viscosity for samples containing unmodified and modified carbon nanotubes. No difference was found for samples containing silanols groups and HNT when compared to neat PP.