Rheology of nanocomposites based on layered silicates and polyamide-12

Nanocomposites based on polyamide-12 (PA-12) and layered silicates are synthesized and analyzed with respect to their morphological and rheological properties. Transmission electron microscopy shows the fine dispersion of silicate layers in a PA-12 matrix. Different swelling agents for the clay (protonated aminododecanoic acid or water) are used. This allows the molar mass of PA-12 to be controlled during the preparation of the nanocomposites. When aminododecanoic acid is used as a swelling agent, the exfoliated silicate layers are chemically bonded to the matrix, whereas the use of water as a swelling agent leads to exfoliated silicate layers well dispersed in the polymer matrix without tethered polymer chains. The rheological behavior of the nanocomposites differs extremely from that of the pure PA-12 matrices. A qualitative description of the rheology of these nanocomposites is provided.