2 research outputs found
Poly(hydroxyalkanoate) Elastomers and Their Graphene Nanocomposites
Medium-chain-length polyÂ(hydroxyalkanoate)Âs
(PHA<sub>mcl</sub>)
are biodegradable and renewable biopolymers with elastomeric qualities.
Here we report on the preparation and characterization of composite
materials using thermally reduced graphene (TRG) nanoparticles as
filler with three PHA<sub>mcl</sub> polymers. The matrices vary with
respect to chain packing length, capacity for noncovalent bonding
with the TRG surface, and the presence of covalent cross-linking.
Results show that the addition of up to 2.5 vol % TRG to PHA<sub>mcl</sub> increases the melting temperature by 1–3 °C, the modulus
by 200–590%, and the electrical conductivity by >7 orders
of
magnitude. Additionally, we use rheology and microscopy to characterize
the composites. We discuss our results in light of polymer entanglement
theory and the effects of polymer structure, filler loading volume,
and the role of graphene-polymer interfacial forces. We extend our
discussion by comparing the modulus enhancements of PHA<sub>mcl</sub> composites to those reported in other studies in which layered carbon
nanofillers are combined with structurally related biopolyesters including:
polylactide, polylactide-<i>co</i>-polyglycolide, polycaprolactone,
and two other PHA copolymers
Influence of Functionalized Graphene Sheets on Modulus and Glass Transition of PMMA
Influence of Functionalized Graphene Sheets on Modulus
and Glass Transition of PMM