The influence of carbon nanotubes on the PVC glass transition temperature

The suspension poly(vinyl chloride) with the K number 70 (PVC S-70) compound was applied as a matrix of the nanocomposite, and the multi-wall carbon nanotubes (MWCNT) in the concentration range between 0.01 wt.% and 0.05 wt.% as a nanofiller. The Tg determination was realized by means of DMTA, dielectric losses measurements and DSC measurements. In all cases the PVC matrix revealed lower Tg comparing with corresponding composites with CNTs, and a clear relationship between the frequency, CNT contain and the Tg was found. With an increase of the charging frequency an increase of Tg of about 3 °C by DMTA measurements, realized by frequencies f = 1 Hz and f = 10 Hz, and of 9 °C by f = 1000 Hz, was noted. Independent on the frequency a maximum of the Tg increase was observed by the CNT concentration of about 0.01–0.02 wt.%.Within investigated MWCNT concentration the lowest impact of MWCNT on the Tg value were observed by the DSC measurements. This is probably due to quite different response of the nanotubes distribution on the temperature dependent PVC chain mobility.