Fabrication, Characterization, and Properties of Poly (Ethylene-Co-Vinyl Acetate) Composite Thin Films Doped with Piezoelectric Nanofillers

Ethylene vinyl acetate (EVA) is a copolymer comprehending the semi-crystalline
polyethylene and amorphous vinyl acetate phases, which potentially allow the fabrication of tunable
materials. This paper aims at describing the fabrication and characterization of nanocomposite thin
films made of polyethylene vinyl acetate, at different polymer concentration and vinyl acetate content,
doped with piezoelectric nanomaterials, namely zinc oxide and barium titanate. These membranes are
prepared by solvent casting, achieving a thickness in the order of 100–200 micrometers. The nanocomposites
are characterized in terms of morphological, mechanical, and chemical properties. Analysis of the
nanocomposites shows the nanofillers to be homogeneously dispersed in EVA matrix at dierent vinyl
acetate content. Their influence is also noted in the mechanical behavior of thin films, which elastic
modulus ranged from about 2 to 25 MPa, while keeping an elongation break from 600% to 1500%
and tensile strength from 2 up to 13 MPa. At the same time, doped nanocomposite materials
increase their crystallinity degree than the bare ones. The radiopacity provided by the addition of
the dopant agents is proven. Finally, the direct piezoelectricity of nanocomposites membranes is
demonstrated, showing higher voltage outputs (up to 2.5 V) for stiffer doped matrices. These results
show the potentialities provided by the addition of piezoelectric nanomaterials towards mechanical
reinforcement of EVA-based matrices while introducing radiopaque properties and responsiveness to
mechanical stimuli.