Polyamides montmorillonite organically modified clay

Polymer clay nanocomposites have, for some time now, been the subject of extensive research into improving the properties of various matrices and clay types. It has been shown repeatedly that with the addition of organically modified clay to a polymer matrix, either in-situ (1) or by melt compounding (2), exfoliation of the clay platelets leads to vast improvements in fire retardation (2), gas barrier (4) and mechanical properties (5, 6) of nanocomposite materials, without significant increases in density or brittleness (7). There have been some studies on the effect of clay modification and melt processing conditions on the exfoliation in these nanocomposites as well as various studies focusing on their crystallisation behaviour (7-10). Polyamide-6 (PA-6)/montmorillonite (MMT) nanocomposites are the most widely studied polymer/clay system, however a systematic study relating the structure of the clay modification cation to the properties of the composite has yet to be reported. 

Reactive extrusion provides an alternative approach to melt compounding, for the preparation of polyamide-6 nanocomposites [117]. In this study, a co-rotating twin-screw extruder was used to anionically polymerise e-caprolactam in the presence of organically modified montmorillonite clay. Hence, intercalcation and delamination occur concurrently with polymer formation. 

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