Synthesis and thermal behaviour of layered silicate-EVA nanocomposites

Extrusion moulding of both polymer-layered silicate nanocomposites and micr ocomposites based on the copolymer poly (ethylene-co-vinylacetate) with eit her 12 wt.% (EVA 12) or 19 wt.% (EVA 19) vinyl acetate content is described in this paper. The silicates were a synthetic fluorohectorite, rendered or ,organophilic by means of cation exchange of intergallery sodium cations fo r octadecylammonium or ammoniumdododecanoic acid, and a montmorillonite, re ndered organophilic with octadecylammonium. The materials thus obtained wer e characterised by wide angle X-ray diffraction and transmission electron m icroscopy. It was established that dispersion of the organic phase depends on both the silicate type and silicate modification. At these vinylacetate contents dispersion was achieved without requiring additional compatibilise r. The thermal behaviour of the composites was examined on a thermobalance in nitrogen and in air. In the nanocomposites acceleration of EVA deacylati on and slower thermal degradation were observed, while protection against t hermo-oxidation and delayed weight loss were evident in air. (C) 2001 Elsev ier Science Ltd. All rights reserved.