Graphene-Embedded Hybrid Network Structure to Render Olefin Block Copolymer Foams with High Compression Performance

Abstract

Graphene has abundant interactions with polymers by adhering to macromolecular chain segments, facilitating heterogeneous crystal nucleation and adsorbing free radicals. Hence, a hierarchical network structure using graphene as the anchor could be formed in an olefin block copolymer (OBC)/low-density polyethylene (LDPE) blend together with cross-linking points and entanglement points. Then, a nanocomposite foam was fabricated by supercritical CO2 foaming. In this work, a graphene-embedded hybrid network structure was designed to effectively control OBC/LDPE foaming. The strategy is as follows: (1) Macromolecular free radicals triggered by peroxide were adsorbed on the surface of graphene to form a dentritic-on-plate structure. (2) Both OBC and LDPE molecular chain segments were adhered to graphene to form a hybrid physical network. (3) Long-branched chains of LDPE formed entanglement points with both molecular chains whose segments adhered to graphene and macromolecular free radicals adsorbed on graphene. Finally, an optimized graphene content of 0.5 wt % in the obtained nanocomposite foam would maximize its compression stability (hysteresis loss of 53%) with a high resilience of 60%.

Novel covalent adaptable networks (CANs) of ethylene/1-octene copolymers (EOCs) made by free-radical processing: comparison of structure–property relationships of EOC CANs with EOC thermosets

“…14,15 These strong, physical cross-links provide EOCs with elasticity and strength, and EOCs are desirable as low-cost impact modifiers and tougheners in thermoplastic elastomers, foams, and shape memory polymers for applications like footwear, cushioning, and catheters. [16][17][18][19][20][21][22][23] EOCs are common components in blends with other polymers such as polypropylene (PP), [24][25][26][27][28] ethylene propylene diene monomer (EPDM) rubber, [29][30][31][32] ethylene-vinyl acetate copolymer (EVA), [33][34][35] and polydimethylsiloxane (PDMS). 36,37 Like PE, EOCs and their blends may be vulcanized or covalently crosslinked using radical initiators such as peroxides to enhance properties like elasticity and temperature resistance.…”

Ultrahigh Electromagnetic Wave Transmitting Polyphenylene Sulfide Microcellular Foams Based on Molecular Structure Design for 5G Communication

“…It is noticed from Figure a,b that G ′ and G ′ ′ have a similar trend of increasing with ω. After cross-linking, both G ′ and G ′ ′ increase significantly at the low-frequency region but present little difference at the high-frequency region. − The full spectra of the G ′ curve almost appear as a platform, indicating that the thermal oxidation treatment forms long branches and cross-linking points in PPS macromolecular chains. Owing to the three-dimensional (3D) cross-linking network, cross-linked PPS shows a “gel-like” or “solid-like” response. − In Figure c, tan δ shows a downward trend for untreated PPS, indicating that the system has a high contribution to viscosity and a low contribution to elasticity.…”

Supercritical CO2Foaming of Lightweight Polyolefin Elastomer/trans-Polyoctylene Rubber Composite Foams with Extra-Soft and Anti-Shrinkage Performance

“…Obviously, the maximum torque and cure time were decreased with rising TOR content due to its low molecular weight character, illustrating that the addition of TOR could help to optimize the processing properties of POE/TOR composites. In addition, rheological measurement was the most commonly used test method to analyze the melt viscoelasticity of elastomers, which was very sensitive to molecular movements and cross-linking structures . The storage modulus was an important parameter to characterize melt elasticity.…”

“…In addition, rheological measurement was the most commonly used test method to analyze the melt viscoelasticity of elastomers, which was very sensitive to molecular movements and cross-linking structures. 31 The storage modulus was an important parameter to characterize melt elasticity. Figure 2b−d shows the changes in the complex viscosity (ω), storage modulus (G′), and loss modulus (G″) versus angular frequency for the samples.…”