Investigation of melt extensional deformation of ethylene‐vinyl acetate nanocomposites using small‐angle light scattering

Abstract

Ethylene-vinyl acetate copolymers with vinyl acetate (VA) contents of 9 wt% (EVA9) and 18 wt% (EVA18), and commercially modified montmorillonite clay were melt blended in a twin-screw extruder to produce nanocomposites with various silicate loadings (2.5, 5, and 7.5 wt%). EVA9 was melt compounded with Cloisite 1 15A (C15A) and EVA18 was melt compounded with Cloisite 1 30B (C30B). Wide-angle X-ray scattering and transmission electron microscopy have indicated that EVA9 nanocomposites were predominantly intercalated in morphology while EVA18 nanocomposites possessed mixed intercalated/exfoliated structures. Light scattering was conducted in conjunction with meltdrawing experiments to analyze structural evolution of the drawn filaments following its exit from the die of a single-screw extruder. The scattering patterns were processed using Guinier's approximation. The parameter used to characterize deformation was the radius of gyration of optical inhomogeneities in the direction of extension and orthogonal to it. The ratio of these radii of gyration gives the deformation ratio. It was found that increasing silicate content decreased the deformation ratio for all the filled EVA18 nanocomposites. EVA9 with 2.5 and 5 wt% fillers showed an increase in deformation compared with unfilled EVA9, but the 7.5 wt%filled material showed a decrease. These observations were attributed to the relatively strong polymer-filler interactions. POLYM. ENG. SCI.,

The Degradation Kinetics of EVA‐Clay Nanocomposites

“…Samples of EVA nanocomposites were available from materials produced in previously reported research . Three different EVA compositions were used with vinyl acetate (VA) contents of 9, 18 and 28 wt% (denoted EVA9, EVA18 and EVA28 respectively).…”

“…Wide‐angle X‐ray scattering (WAXS) and transmission electron microscopy (TEM) revealed the EVA9 nanocomposite were intercalated in nature but the EVA18 and EVA28 nanocomposires were a mixture of intercalated and defoliated morphologies. Details are reported in the previous literature …”