Effect of Graphene Oxide-Modified CaAl-Layered Double Hydroxides on the Carbon Dioxide Permeation Properties of Fluoroelastomers

Abstract

This work aimed to investigate the CO2 gas barrier and mechanical properties of fluorine rubber nanocomposites filled with Ca/Al layered hydroxide (graphene oxide [GO]/LDH-Ca2Al) modified by GO. GO/LDH-Ca2Al nanocomposite fillers were prepared by depositing Ca/Al layered hydroxide (LDH-Ca2Al) into the surface of alkalized GO (Al-GO). The prepared GO/LDH-Ca2Al nanocomposite fillers and complexes were characterized by Fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) for structural and micromorphological characterization. The results showed that GO/LDH-Ca2Al was successfully prepared with strong interactions between Al-GO and LDH, and the compatibility of GO/LDH-Ca2Al nanocomposite fillers with the polymer was significantly improved compared with that of LDH-Ca2Al. Consequently, both the fracture strength (σb) and strain (εb) of GO/LDH-Ca2Al nanocomplexes remarkably increased, and they exhibited excellent mechanical properties. Differential scanning calorimetry and thermogravimetric analysis were used to characterize the thermal stability of GO/LDH-Ca2Al nanocomposite fillers, and GO/LDH-Ca2Al nanocomposite fillers have better thermal stability than LDH-Ca2Al. The reaction products (S-LDH-Ca2Al and S-GO-Ca2Al) of LDH-Ca2Al and GO/LDH-Ca2Al with CO2 were characterized using XRD and TGA, respectively, and the results show that LDH-Ca2Al reacts readily and chemically with CO2, resulting in a lower diffusion coefficient of CO2 in the LDH-Ca2Al nanocomplexes than that of the GO/LDH-Ca2Al nanocomplexes and leading to the destruction of the laminar structure of LDH-Ca2Al, while GO/LDH-Ca2Al has better CO2 resistance stability. GO/LDH-Ca2Al nanocomplexes exhibited a reduced content of hydroxyl groups with pro-CO2 nature exposed on the surface of LDH-Ca2Al, improving the interfacial interaction between the nanofillers and the rubber matrix and enhancing the dispersion of GO/LDH-Ca2Al in the polymers. Moreover, CO2 in the soluble GO/LDH-Ca2Al nanocomposites was significantly reduced, while the diffusion properties demonstrated weak temperature dependence on solubility. The mechanism of the CO2 gas barrier of polymers filled with GO/LDH-Ca2Al was proposed on the basis of the Arrhenius equation.

Effect of graphene oxide/layered double hydroxide modified by 7‐octenyltrimethoxysilane on the mechanical and gas barrier properties of fluoroelastomers

“…Selected area electron diffraction (SAED) in Figure 3E gives the crystal spacing of 1.66 Å and 2.47 Å for LDH at the (300) and (021) crystal planes, consistent with the XRD results (Figure 2A). The SAED results for GO agree with the previous results 4 . In GLDH versus SGLDH, the LDH was uniformly dispersed on the GO carriers (Figure 3G,H).…”

“…The SEM images (Figure 3A,B) show that LDH and GO exhibited an obvious lamellar structure 32,46–49 . As previously reported, the LDH planar transverse size is around 0.3–0.5 μm, 4 while the GO planar transverse dimension is around 100 μm (S3), confirming the possibility of LDH loading on GO. In Figure 3C,D, the GO surface in SGLDH is loaded with a larger number of lamellar layers of LDH compared with GLDH.…”

“…DMA is another excellent tool that quantitatively characterizes the strength of nanofiller‐polymer interfacial interactions, where the loss tangential correlation of the nanofiller with the polymer matrix satisfies the equation below 3,4,21,64 : where and , respectively, signify the tangents of the filled and unfilled polymer matrices, denotes the filler volume fraction, and refers to the interaction‐only variable capable of representing the intensity of the filler‐matrix interfacial interaction. A large value corresponds to a strong interfacial interaction between the filler and the polymer matrix 3 .…”

“…Rubber composites for oil and gas development, military, aerospace, and aviation applications are prepared by using nanofillers such as carbon black, montmorillonite, and graphene oxide, as well as kaolin and carbon nanotubes, 3 through which the mechanical performance of rubber composites is enhanced 4 . Multiple factors determine the influences of diverse modifying additives and fillers on the mechanical and physicochemical behaviors of polymer composites, including interactions at the filler‐polymer interface, 5–7 filler content, 8 and polymer cross‐linking density, 3 with the interaction factor strongly impacting the composite mechanical behavior.…”

“…However, as an inorganic polar substance, LDH has poor compatibility with organic macromolecules including natural rubber, nitrile butadiene rubber and FKM, resulting in its agglomeration in polymers and generation of weak phase interfaces 10,11 . In our previous work, GO/LDH‐Ca 2 Al nanolaminar fillers were fabricated by incorporating LDH onto an alkalized GO surface; the compatibility of these fillers with polymers and their thermal stability were superior to those of LDH 4 . This result was achieved mainly because GO also has a nearly monolayer layered architecture with a large surface area, 21 and its layer surfaces, which have negative charges and oxygen‐containing groups, are capable of facilitating hydrogen bonding and powerful electrostatic interactions with the positively charged LDH on the host layer surface.…”