Dielectric Relaxation Spectroscopy of Chemically Reactive Polymer Blends

Dielectric Relaxation Spectroscopy of Chemically Reactive Polymer Blends 

The molecular dynamics of ternary polymer blends of PP/PA6/acrylonitrile butadiene styrene copolymer (ABS) in the presence of compatibilizers and multiwall carbon nanotubes (MWNTs) was investigated using DRS [69]. The relaxation time of the PA6 chains was found to have increased significantly when small amounts of compatibilizers (PP-g-MA) or styrene maleic anhydride (SMA) were added. The variation in relaxation time was found to depend heavily on the com-patibilizer efficiency. The variation in relaxation time for PA6 in the presence of 1 wt% MWNTs in the respective ternary blends also followed a similar trend however, the extent of mobility of the PA6 phase was influenced by the state of dispersion of MWNTs in the corresponding blends. 

The molecular dynamics of novel, high-dielectric-permittivity poly(vinylidene fluoride) (PVDF)/PP blends with a small amount of PP-g-MA compatibilizer was reported over a wide range of temperatures and frequencies, using DRS [71]. The results showed that the concentration of PVDF in the composites dominated the changes in dielectric properties, and that the use of PP-g-MA improved the interface interaction between PVDF and PP, resulting in an increased dielectric permittivity. 

The molecular dynamics of similar chemical structure blends of poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN) were investigated using the TSDC technique [74]. Transesterification reactions between the neat components developed during the melt-mixing process. When the a-relaxation processes of the reactive blends were analyzed into their elementary modes by means of relaxation map analysis, the activation energies of the a-relaxation process were found not to be significantly affected by the transesterification reaction. However, the polarizability of the blend was considerably decreased as the PEN content increased, due mainly to the increased stiffness of the polymer backbone. 

This should, in turn, lead to an increased knowledge of the behavior of this important class of polymeric materials and other similar blends. 

---