EVA copolymer based nanocomposites

Nanocomposites are a new class of polymer material with an ultrafine phase dispersion of the order of a few nanometers that shows very interesting properties often very different from those of conventional filled polymers. In this work the mechanical and optical properties of Poly-[ethylene-co-(vinyl acetate)] (EVA copolymer) based nanocomposites have been investigated to evaluate its possible use in several applications. For example, films for covering greenhouses made by EVA copolymer are appealing because of their interesting optical properties and for the so-called greenhouse effect. Mechanical properties, and the rigidity in particular are, on the contrary, quite low. Nanocomposites should avoid this shortcoming if optical properties and processability are not unfavorably effected. EVA copolymer based nanocomposites have been prepared by compounding polymer matrix and two different functionalized silicates (0-10 wt.-%) in molten state. X-Ray diffractograms show that the in the adopted experimental conditions no exfoliation of the filler is obtained, but an intercalated morphology is observed. Rheological behavior both in shear and in non-isothermal elongational flow is only slightly influenced by the presence of the filler. As for the mechanical properties, the elastic modulus strongly increases without any worsening of the elongation at break. The permeability in the UV region is not influenced by adding even relatively high contents of the silicates. the improved mechanical and optical properties and the unmodified processability suggest then the use of these new polymeric systems in many applications and in particular as films for covering greenhouses.