The Effect of SWCNT and MWCNT on Properties and Crystalline Structure of Polyvinylidene Fluoride
Single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) were melt-blended with polyvinylidene fluoride (PVDF).FT-IR technique revealed that SWCNT has insignificant effect on the crystalline structure of PVDF and at 3wt% modification only 14% beta crystal is formed. This observation was accounted for by the chair structure of SWCNT. In MWCNT nancomposites it was found that at 3wt% modification 39% beta crystal is formed. Although equal in weight percentage, the number MWCNTs is less in the corresponding nanocomposites due to their multi-layer structure. This was attributed to the higher surface area and zigzag structure of the surface of MWCNT surface. This results in a typical crystal nucleation of polymer for nanotubes and promotion of beta phase formation. In agreement with FTIR measurements, the WXRD patterns of these nanocomposites did not show any significant difference compared to that of pure PVDF. In spite of smaller population of MWCNTs as compared with that of SWCNTs in nanocomposites, incorporation of MWCNTs, with the same weight percentage, augmented the rheological properties. This observation was attributed to stronger interactions between MWCNT's surface and PVDF segments.