Abstract
Four organically modified montmorillonite (OMMT) clays were prepared by exchanging Na+ ions in silicate layers with organic modifiers: 1-aminododecane, n-octadecylamine, trimethylstearyl ammonium chloride and tributylhexadecyle phosphonium bromide. OMMT clays were mixed with biodegradable polymers, polylactic acid (PLA) and polybutyrene succinate (PBS), by melt intercalation. In order to characterize the composites, the average number of regularly stacked silicate layers (N) and average interparticle distance (ξ) of OMMT were determined by transmission electron microscopy and X-ray diffraction, respectively. Dynamic viscoelastic measurements and differential scanning calorimetory were also carried out. The chemical interaction between polar groups of the organic modifier and matrix polymer played an important role in the intercalation process, and residual Na+ ion hindered delamination of the silicate layers. Modulus of the composites increased significantly when ξ was smaller than 80nm. OMMT behaved as a nucleating agent and enhanced the crystallization rate in PLA based nanocomposites.
