Structural analysis of water sorption for nanocomposites of poly(vinyl chloride)/carbon nanotubes

It is known that in the case of nanocomposites PVC/multi-walled carbon nanotubes having very small contents of nanosatellites we may observe extreme dependence of some properties (strength, thermal stability, water absorption, melt viscosity) on the content of nanotubes. Moreover, the extremum of the above properties are achieved with the same content of nanotubes (~ 0,001-0,002 mass. %). Secondly, after reaching an extremum, the process is always followed by the deterioration of the properties of nanocomposites. The first aspect assumes that when a specific filler is implemented, some extremum of the structural characteristics that determines the extreme properties, changes. The second aspect implies that the extremum point corresponds to the beginning of aggregation of carbon nanotubes, since it is known that the process usually leads to deterioration of properties of polymer nanocomposites. The dependence of water sorption on nanofiller content for nanocomposites of poly(vinyl chloride)/carbon nanotubes, having extreme character, has been studied. It has been shown that minimum water sorption is connected with change of nanofiller structure in polymer matrix. Thus, the results obtained in the present work showed that the extremum properties as a function of the content of nanosatellites for nanocomposites of multi-walled carbon nanotubes in specific for this anisotropic nanosatellites form - the formation of a “closed” annular structures. In turn, the change in the structure of nanosatellites determines the change in the structure of the polymer matrix, which contributed to the variation of nanocomposite properties. This effect results in loosening of polymer matrix structure that is direct cause of large values of water sorption.