The aim of this work was to develop an effective approach to improve the graphite dispersion and, consequently, the electrical conductivity of nanocomposites based on polycaprolactone (PCL) and graphite nanoplates (GNP). With this aim, a polymeric additive was designed to be compatible with the polymer matrix and capable of interacting with the graphite layers. Indeed, the compound consists of a low molecular mass PCL ending with a pyrene group (Pyr-PCL). The exploitation of such a molecule is expected to promote from one side specific interactions of the pyrene terminal group with the surface of graphite layers and from the other to guarantee the compatibility with PCL, having a chain with the same nature as the matrix. The features of the nanocomposites prepared by directly blending PCL with GNP were compared with those of the same systems also containing the additive. Moreover, a neat mixture, based on PCL and PCL-Pyr, was prepared and characterized. The specific interactions between the ad hoc synthesized compound and graphite were verified by UV measurements, while SEM characterization demonstrated a finer dispersion of GNP in the samples containing Pyr-PCL. GNP nucleating effect, proved by the increase in the crystallization temperature, was observed in all the samples containing the nanofiller. Moreover, a significant improvement of the electrical conductivity was found in the systems based on the pyrenyl terminated PCL. This peculiar and interesting phenomenon was related to the optimized nanofiller dispersion and to the ameliorated compatibility with the polymer matrix.
A covalent adaptable
network based on the thermoreversible cross-linking
of an ethylene–propylene rubber through Diels–Alder
(DA) reaction was prepared for the first time through melt blending
as an environmental-friendly alternative to traditional synthesis
in organic solvents. Functionalization of the rubber with furan groups
was performed in a melt blender and subsequently mixed with different
amounts of bismaleimide in a microextruder. Cross-linking was confirmed
by FT-IR spectroscopy and insolubility at room temperature, while
its thermoreversible character was confirmed by a solubility test
at 110 °C and by remolding via hot-pressing. Mechanical and thermomechanical
properties of the obtained rubbers showed potential to compete with
conventionally cross-linked elastomers, with stiffness in the range
1–1.7 MPa and strain at break in the range 200–500%,
while allowing recycling via a simple melt processing step. Nanocomposites
based on the thermoreversible rubber were prepared with reduced graphene
oxide (rGO), showing significantly increasing stiffness up to ca.
8 MPa, ∼2-fold increased strength, and thermal conductivity
up to ∼0.5 W/(m K). Results in this paper may open for industrially
viable and sustainable applications of thermoreversible elastomers.
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