Behavior of Spin Probe TEMPO in Composites Based on Polypropylene with Different Content of Single-Wall Carbon Nanotubes

Mobility of a spin probe, 2,2,6,6-tetramethylpiperidine-1-oxyl, in the nanocomposites of isotactic polypropylene with single-wall carbon nanotubes has been studied. The nanotubes content has been varied from 1.2 to 38.5 wt %. The sample of pure polypropylene and these with content of nanotubes below 8% performed similar rotational mobility of the spin probe within the examined temperature range (from 105 to 405 K). This fact has evidenced the spin probes localization in the bulk of the polymer chains, not in direct contact with the carrier. The sample with the highest doping degree (38.5% of nanotubes) has demonstrated the spin probes agglomeration and their reduced rotational mobility, likely related to larger volume fraction of the interfacial areas of the polymer in the vicinity of the nanotubes. It can be concluded that the mobility of the polymer near the nanotubes is significantly reduced.