Melt compounding with graphene to develop functional, high-performance elastomers

Abstract

Rather than using graphene oxide, which is limited by a high defect concentration and cost due to oxidation and reduction, we adopted cost-effective, 3.56 nm thick graphene platelets (GnPs) of high structural integrity to melt compound with an elastomer-ethylene-propylene-diene monomer rubber (EPDM)-using an industrial facility. An elastomer is an amorphous, chemically crosslinked polymer generally having rather low modulus and fracture strength but high fracture strain in comparison with other materials; and upon removal of loading, it is able to return to its original geometry, immediately and completely. It was found that most GnPs dispersed uniformly in the elastomer matrix, although some did form clusters. A percolation threshold of electrical conductivity at 18 vol% GnPs was observed and the elastomer thermal conductivity increased by 417% at 45 vol% GnPs. The modulus and tensile strength increased by 710% and 404% at 26.7 vol% GnPs, respectively. The modulus improvement agrees well with the Guth and Halpin-Tsai models. The reinforcing effect of GnPs was compared with silicate layers and carbon nanotube. Our simple fabrication would prolong the service life of elastomeric products used in dynamic loading, thus reducing thermosetting waste in the environment.

Mechanical and Electrical Properties of Elastomer Nanocomposites Based on Different Carbon Nanomaterials

“…However, it should be mentioned that the filler contents used in these studies and expressed in vol% are high while nanofillers, if well dispersed, are expected to impart to the host matrix strong reinforcement at very low filler loading. Besides the impressive and unusual enhancement of the storage modulus of the EPDM/GnPs (12 vol%), the authors mention an increase in Tg by 2.2% for the 5.7 vol% GnPs and an increase of 4 °C at 10.5 vol% GnPs in SBR, attributed to a decrease in the mobility of elastomer chains attributed to good interfacial polymerfiller interaction [94,95]. Potts et al [26] have shown that for a 5 wt% reduced graphene oxide/NR nanocomposite, the storage modulus increases by a factor of 3.4 and 2 at −100 °C, but by factors of 19.5 and 4.7 at 25 °C by solution treatment and two-roll mill processing.…”

“…Nevertheless, it is also shown that Tg is not substantially shifted by the addition of either FGS or CB. Two papers of Araby et al [94,95] in which graphene platelets (GnPs) have been incorporated in EPDM [94] and in SBR [95] observe an increase in the storage modulus by 2536% and 159% at 12 vol % GnPs in EPDM and around 190% and 650% at 10.5 vol % in SBR in the glassy and rubbery regions, respectively. These improvements are attributed to a high level of interaction between matrix chains and GnPs.…”

Transport performance in novel elastomer nanocomposites: Mechanism, design and control

“…Araby et al observed that the electrical conductivities of EPDM/GnPs nanocomposites increased by 6 orders of magnitude after vulcanization, explained by the fact that the GnPs tended to aggregate and form a filler-filler network during vulcanization [84]. In PU/MWCNTs nanocomposites, the annealing of the nanocomposites induced the individually dispersed MWCNTs to form loosely packed aggregates that contributed to the formation of conductive pathways by acting as connections or junctions.…”

Fabrication of ZrO2-based nanocomposites for transuranic element-burning inert matrix fuel

“…The carbon fiber has outstanding mechanical and thermal properties, and it has been used as a reinforcement material for different materials including zirconia [15e18]. Graphite can also be a reinforcement material because it has a high stiffness and strength, in addition to its high thermal conductivity [19].…”