Preparation of thermally reduced graphene oxide and the influence of its reduction temperature on the thermal, mechanical, flame retardant performances of PS nanocomposites
Introduction
Polystyrene (PS) is a widely used general plastics for numerous applications in our daily life. For many applications, particularly transportation and electrical appliances, it is very necessary to use flame retardants to reduce the flammability of PS. Among various flame retardants, halogenated compounds are good flame retardant additives for PS. However, they suffer some serious disadvantages, such as evolution of toxic gases and corrosive smoke. For environmental concerns, the introduction of halogen-free flame retardants, such as phosphorus, nitrogen, silicon, intumescent flame retardant as well as inorganic fillers, has been an effective way of improving their flame retardancy [1], [2], [3], [4], [5].
Recently, various kinds of nanoparticles have been investigated as flame retardants differing in both their chemical compositions and morphologies. Compared with micron-sized additives, nanomaterials offer several advantages, especially with respect to significantly reducing heat release rate at quite low loadings, usually less than 5 wt%. In sharp contrast, the contents of inorganic fillers such as Mg(OH)2 or Al(OH)3 are much higher and vary between 40 wt% and 65 wt% [1]. Currently, carbon nanofillers, including carbon nanotube, graphene or graphene oxide, have begun to be explored for enhancement of the flame-retardant properties of various polymer systems.
Graphene, a single-atom-thick two-dimensional carbon layer, comprised of sp2 hybridized carbon, has aroused considerable interest in developing a variety of novel composites due to its high surface area, electrical conductivity, high flexibility, and mechanical strength and exhibits great promise for potential applications in the fields of nanoelectronics, sensors, batteries, super-capacitors, hydrogen storage, and nanocomposites. The addition of graphene, even at a very low concentration level (usually less than 5%), into a polymeric matrix can significantly improve polymer properties such as mechanical, thermal, and flame retardancy. For example, incorporating graphene alone into polypropylene [6], epoxy [7], [8],waterborne polyurethane [9] matrix exhibited improved flame retardant and mechanical properties. Noticeable reduction in flammability and improvement in thermal stability of the polymer nanocomposites are achieved with the addition of graphene and other flame retardants, such as intumescent flame retardants [10], [11], metal hydroxides [12], layered double hydroxide [13], [14], montmollronite [15], and melamine polyphosphate [16], [17]. It is a novel strategy to prepare functionalized graphene oxide (FGO) grafted with other flame retardants. The prepared polymer/grafted FGO nanocomposites showed excellent flame retardance even at low additive concentrations [18], [19], [20], [21], [22], [23], [24], [25]. In our previous work, the comparison of different oxidation degrees of GOs with graphene on both flame retardancy and dynamic viscoelastic properties of the PS composites have been investigated. We found that the decreasing content of oxygen groups of GOs or graphene is benefit for the improvement of the flame retardancy and thermal stability [26]. Considered that different reduction temperature might cause the change of both chemical compositions and morphologies of GO, it is of significance to investigate the reduction degree of GO on the flame retardancy of polymer composites.
In this work, TGOs with different reduction temperatures have been prepared. PS/TGO nanocomposites have also been prepared by melt blending. The structure, morphology, dynamic mechanical properties, thermal stability, and flame retardancy of the nanocomposites were investigated.
Section snippets
Materials
GO was synthesized from natural graphite (1000 mesh) that was kindly supplied Shandong Pingdu Graphite Company (Qingdao, China). Concentrated sulfuric acid (H2SO4) (A.R.), concentrated hydrochloride acid (HCl) (A.R.) and potassium permanganate (KMnO4) (A.R.) were purchased from Nanjing Chemical Reagent Company (Nanjing, China). Sodium nitrate (A.R., NaNO3) and H2O2 (A.R., 30%) was purchased from Shanghai Renyu Chemicals Company. All these commercial chemicals were used as received without
Structure and morphology
FTIR was used to confirm the structure of GO, TGO and PS/TGO nanocomposites. Fig.1 shows the FTIR spectra of GO, TGO2, TGO5 and TGO8, respectively. In the FTIR spectrum of GO, peak at about 3410 cm−1 is assigned to the stretching vibration of COH. Peak at 1731 cm−1 is assigned to the CO stretching vibration; the absorption bands at 1624, 1052 and 1224 cm−1 are assigned to the stretching vibration of C, CO and COH, respectively [28]. After thermal reduction, the intensity of these peaks decreased
Conclusions
Different reduction degrees of TGO were prepared at different thermally reduced structure. PS/TGO nanocomposites were prepared by melt blending method. The results from FTIR, Raman, XRD, XPS and SEM showed that TGO2, TGO5 and TGO8 provided different structure and morphology. The increase of the thermally reduction temperature is benefit for the removal of the oxygen groups form GO layers, and thus lead to an expanded disordered structure. DMA showed that both the storage modulus and Tg of
Acknowledgement
This work is supported by Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents (2015RCJJ002) and Jiangsu Province Science Foundation for Youths (BK20140841).
References (39)
- et al.
Effects of zirconium silicate reinforcement on expandable graphite based intumescent fire retardant coating
Polym Degrad Stabil
(2014) - et al.
Flame retardancy through carbon nanomaterials: carbon black, multiwall nanotubes, expanded graphite, multi-layer graphene and graphene in polypropylene
Polym Degrad Stabal
(2013) - et al.
The effect of graphene presence in flame retarded epoxy resin matrix on the mechanical and flammability properties of glass fiber-reinforced composites
Composites Part A
(2013) - et al.
Effect of graphene nanosheets on morphology, thermal stability and flame retardancy of epoxy resin
Compos Sci Technol
(2014) - et al.
Combination effect of carbon nanotubes with graphene on intumescent flame-retardant polypropylene nanocomposites
Composites Part A
(2014) - et al.
Enhanced mechanical, thermal and flame retardant properties by combining graphene nanosheets and metal hydroxide nanorods for Acrylonitrile–Butadiene–Styrene copolymer composite
Composites Part A
(2014) - et al.
Co-precipitation synthesis of reduced graphene oxide/NiAl-layered double hydroxide hybrid and its application in flame retarding poly(methyl methacrylate)
Mater Res Bull
(2014) - et al.
Combination effects of graphene and layered double hydroxides on intumescent flame-retardant poly(methyl methacrylate) nanocomposites
Appl Clay Sci
(2014) - et al.
Combination of graphene and montmorillonite reduces the flammability of poly(vinyl alcohol) nanocomposites
Appl Clay Sci
(2013) - et al.
Comparative study on the synergistic effect of POSS and graphene with melamine phosphate on the flame retardance of poly(butylene succinate)
Thermochim Acta
(2012)
Effect of graphene nanosheets on morphology, thermal stability and flame retardancy of epoxy resin
Compos Sci Technol
Preparation and properties of novel epoxy/graphene oxide nanosheets (GON) composites functionalized with flame retardant containing phosphorus and silicon
Mater Chem Phys
The synthesis of a novel graphene-based inorganic–organic hybrid flame retardant and its application in epoxy resin
Composites Part B
Miscibility and interactions in polystyrene and sodium sulfonated polystyrene with poly(vinyl methyl ether) PVME blends. Part II. FTIR
Polymer
Synthesis and characterisation of hydrophilic and organophilic graphene nanosheets
Carbon
Characterization and catalytic performance of porous carbon prepared using in situ-formed aluminophosphate framework as template
J Colloid Interface Sci
Anisotropic thermal conductive properties of hot-pressed polystyrene/graphene composites in the through-plane and in-plane directions
Compos Sci Technol
Growing polystyrene chains from the surface of graphene layers via RAFT polymerization and the influence on their thermal properties
Composites Part A
Cited by (67)
UV-C driven reduction of nanographene oxide opens path for new applications in phototherapy
2024, Colloids and Surfaces B: BiointerfacesFacile preparation, pyrolysis and pilot production a bamboo scrimber with halogen-free, flame-resistance and low-smoke
2023, Industrial Crops and ProductsState of the art and current trends on layered inorganic-polymer nanocomposite coatings for anticorrosion and multi-functional applications
2022, Progress in Organic CoatingsCitation Excerpt :These materials with high thermal conductivity (2000 to 5000 W·m−1·K−1), heat dissipating capability [208] and impermeability to gases along with a high mechanical strength, make them ideal for high temperature applications. When GR-family products are introduced into polymer nanocomposites, they could be granted with interesting fire-retardant properties as increased thermal stability [209], smoke suppression [210], melt viscosity, antidripping properties [211] and char yield or residual mass [212], while limiting oxygen index value [213] and decreasing in the heat release rate [214]. Despite many advantages, it is also important to consider the total amount of filler, as a high loading of GR/GO/rGO into polymers can sometimes reduce their mechanical strength [215].
Graphene-based polymer composites for flame-retardant application
2022, Innovations in Graphene-Based Polymer CompositesFlame retardant nanofillers and its behavior in polymer nanocomposite
2022, Advanced Polymer Nanocomposites: Science, Technology and Applications