High-temperature X-ray diffraction studies on polyamide6/clay nanocomposites upon annealing

Summary The influence of nanodispersed clay on the α crystalline structure of polyamide 6 (PA6) was examined in-situ with X-ray diffraction (XRD) between room temperature and melting. In pure PA6 upon annealing the α crystalline phase was substituted by an unstable pseudohexagonal phase at 150°C, then it transformed into a new stable crystalline structure - high temperature α′ phase above the transition temperature. However, in PA6/clay nanocomposite (PA6CN), the α phase did not present crystalline phase transition on heating. The increase in the annealing temperature only led to continuous intensity variation. The different behaviors were caused by the confined spaces formed by silicate layers, which constrained the mobility of the polymer chains in-between. Received: 4 April 2002 / Revised version: 12 May 2002 / Accepted: 12 May 2002