Processing degradation of polyamide 6/montmorillonite clay nanocomposites and clay organic modifier

Under injection molding conditions, typical of industrial processing, in situ polymerized montmorillonite/polyamide 6 nanocomposites significantly degraded, producing a four-fold increase in epsilon-caprolactam (monomer) content and a significant reduction in number average molecular mass, as compared to the as-received nanocomposite. Degradation was believed to occur via peptide bond scission following attack by water that is most likely released from the polymer and the montmorillonite clay surface at the 300 degreesC (12.5 min) processing conditions. Under identical injection molding conditions, virgin polyamide 6 number average molecular mass did not decrease (within experimental uncertainty); however, a small increase in monomer content was observed. Characterization methods included solution C-13 nuclear magnetic resonance spectroscopy, infrared spectroscopy, gel-permeation chromatography, and thermal gravimetric analysis. (C) 2002 Elsevier Science Ltd. All rights reserved.