Thermal degradation and rheological behaviour of EVA/montmorillonite nanocomposites

The study is focused on the co-polymer poly(ethylene-co-vinylacetate) (EVA) used in telecommunication cable manufacturing. Different modified fillosilicates and EVA polymer were mixed at 120 degreesC in a Brabender mixer AEW330 in order to obtain polymer layered silicate nanocomposites(PLSN). Exfoliated nanocomposites were obtained with montmorillonite exchanged with methyl tallow bis(2-hydroxyethyl) ammonium and fluorohectorite exchanged with octadecylammonium, whereas with montmorillonite exchanged with dimethyl dehydrogenated tallow ammonium and fluorohectorite exchanged with amino dodecanoic acid an intercalated nanocomposite and a microcomposite were obtained respectively. It has been demonstrated that a low silicate percentage (10%) nanodispersed in the polymer matrix is capable of dramatically reducing the influence of oxygen during thermooxidation, and to substantially increase the storage modulus of the material. The acid catalysis of acetic acid elimination observed heating EVA nanocomposites in nitrogen is more effective in the case of exfoliated morphologies. (C) 2002 Elsevier Science Ltd. All rights reserved.