A Dynamic Mechanical and Dielectric Relaxation Study of PP-g-MAH/ Clay Nanocomposites

ABSTRACT

The relaxations in maleic anhydride grafted polypropylene (PPgMAH) and its nanocomposite based on organically modified layered silicates were investigated using dynamic mechanical thermal analysis and dielectric relaxation spectroscopy. The results of dynamic mechanical thermal analysis showed that the incorporation of clay in the polymer matrix resulted in two relaxations corresponding to the glass transition and a high temperature transition. In nanocomposites, the incorporation of clay resulted in reduction of the loss modulus peak area for the glass transition peak suggesting decreased content of mobile amorphous phase. An increase in the area of the high temperature transition was noted and associated with the presence of rigid amorphous phase. The dielectric measurements indicated presence of a relaxation at high frequency side for the PPgMAH whereas in nanocomposite two relaxations in the low frequency side were observed namely MWS relaxation or the interfacial polarization of the polymer and clay followed by α_RAP relaxation due to relaxation of rigid amorphous phase. The presence of rigid amorphous phase was attributed to the strong bonding between the MAH groups of PPgMAH and the clay surface.

Keywords: