Influence of multi-walled carbon nanotubes on the ? form crystallization of syndiotactic polystyrene at low temperature

Syndiotactic polystyrene (sPS) samples were quenched at low temperature (0°C) in the presence of Multi-Walled Carbon Nanotubes (MWCNT) at different concentrations. The influence of carbon nanotubes on the structure and physical properties of sPS composites was investigated by SEM, X-ray diffractograms, DSC (Differential Scanning Calorimetry), and Dynamic Mechanical Analysis (DMA). A good dispersion of the carbon nanotubes in the sPS matrix was found, at least for the low MWCNT concentration, whereas opposite effects were noticed on Tg and elastic modulus, depending on concentration. The pristine sPS sample was almost amorphous at 0°C, whereas in the filled samples the crystallinity increased on increasing the MWCNT concentration, indicating a strong nucleation effect of the nanotubes. Interestingly, in spite of the low temperature, the ? crystallinity was induced and this crystalline form increases on increasing the carbon nanotube concentration, being dominant (68% of the total crystallinity) already at 3 wt% of MWCNT concentration.