- Graphene‐Based Composites Combining Both Excellent Terahertz Shielding and Stealth Performance
- How are composite materials made?
- Graphene composites (Part 1)
- High Performance Graphene Oxide Based Rubber Composites
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- What are composite materials?
- Graphene-based composite materials
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Rubbers, generally acknowledged as strategic materials, can be tailored by adding fillers to meet the demands in versatile industry applications. Carbon black CB as a carbon nano-material has been widely used in rubber reinforcement for over years.
Nowadays, CB faces severe challenges because it is derived from crude oil and generates excessive wastes and greenhouse gas emissions.
Graphene‐Based Composites Combining Both Excellent Terahertz Shielding and Stealth Performance
In order to tackle this global issue, new oil-independent fillers have received increasing attentions for replacement of CB. Recently, graphene oxide 1 , 2 , 3 , 4 , 5 , 6 GO has emerged as a new layered carbon material with nano size effects and unique physical properties 7 , 8 , 9 , implying that GO is a potential material for replacing CB for reinforcement of rubbers.
Furthermore, graphite as the precursor of GO is oil-independent and naturally abundant. For successful application of GO in rubber industries especially tire industry, two criterions should be fulfilled: i commodity rubbers are selected as a matrix, such as styrene-butadiene rubber SBR and natural rubber, because these two kinds of rubbers account for over 60 per cent of the total rubber market in the world and are mainly reinforced by CB; ii the fabrication method is large scale and environment-friendly.
How are composite materials made?
However, most current studies for GO based rubber composites are limited in specific rubber matrices and focused on electric, thermal and some other functional properties 10 , 11 , 12 , In fact, in rubber industry, the static and dynamic mechanical properties of rubber composites are more concerned.
However, conventional mechanical blending method cannot uniformly disperse the GO sheets in the rubber matrix see Supplementary Information S Solution mixing 12 , 13 , 14 , 15 has been demonstrated to be an effective way to obtain the desired dispersion, but the removal of organic solvents poses persistent problems such as added cost and potential environmental pollution for the practical implementation of the method.
By adjusting the flocculation process, VPR not only plays a key role in the prevention of aggregation of GO sheets during co-coagulation but also acts as an interface-bridge between GO and SBR. In addition, our preparation method is water-mediated, green, and large scale, which is appropriate for preparing various GO-based rubber composites since GO sheets can form well-dispersed aqueous colloid in water 16 , 17 , 18 and most rubbers can exist in latex form.
A cryo-TEM image shows that colloidal particles with different sizes are individually dispersed in the mixture.
However, no aggregates of GO sheets is observed, indicating that GO sheets may be isolated by rubber colloidal particles within the mixture dispersion Fig.
In the schematic representation a , SBR and VPR colloidal particles are presented as red and green balls respectively. In the schematic representation c , the released VPR molecules are represented as green random coil.
Ball-and-stick illustration of a model structure of the interaction between VPR and GO sheets is shown in g. Yellow, red and gray are used to represent N, O and H atoms, respectively. In the schematic representation e , the demulsified SBR molecules are represented as red random coil.
By adjusting pH value of mixture to 4. It is supposed that the majority of the remained colloidal particles could be SBR but not VPR, which is verified by our zeta potential analysis Fig.
At pH 4. In addition, the electrostatic repulsion between negative charged SBR colloidal particles ensured the VPR-modified GO sheets be separated uniformly in the mixture instead of aggregation Fig. When the pH approaches 2. This result suggests that the electrostatic repulsion between the GO sheets is weaker than that between the GO sheets and SBR colloidal particles.
No GO aggregates are observed on the cross-section of the composite see Fig. At a GO loading of 0.
The structures of the GO sheets dispersed in the rubber matrix include both individual GO sheets Fig. The three peaks at 1. The weak and broad peak at 7.
Graphene composites (Part 1)
Most GO sheets were dispersed in the rubber matrix as individual sheets. However, owing to the strong electric attraction and nano-scaled effect between the GO sheets, the aggregation of GO sheets is kinetically favored during the co-coagulation process. It is worth pointing out that only sandwich structures see inset of Fig. The GO dispersion in composite and the interface interaction are the two main factors to determine the reinforcing efficiency of GO in the composite Symbols denote experimental values, and experimental errors were derived from measurements acquired from different regions of the same sample.
The excellent reinforcement by GO sheets can be attributed to two reasons. Therefore the GO provides nearly 1. Second, there is a glassy layer in the vicinity of the GO sheets as a result of the ionic interactions between the GO sheets and VPR, the chains of which can co-crosslink with the SBR chains.
The rubber chains in the glassy layer will slip along the GO sheets and form stretched and parallel-arraying straight chains 23 under external stresses. After the orientation of chains, the stresses can be uniformly shared by the oriented chains to avoid stress concentrations Meanwhile, the glassy layer also acts as a mediator to facilitate the stress transfer from the matrix to the GO sheets.
As shown in Fig. The experimental results demonstrated that the reinforcement efficiency of GO fillers is higher than that of CB, and this improvement comes with a low mass density of the composite.
Moreover, any eventual replacement of CB by GO will have epoch-making significance in the oil-dependent rubber industry.
This amount of CB will consume In contrast, GO, which is oil-independent, can be readily prepared from different types of graphite, all inexpensive. The fully-exfoliated GO and its good dispersion in rubber also makes it as a good candidate for gas-resistant materials. As the gas-permeability vs.
High Performance Graphene Oxide Based Rubber Composites
GO loading results presented in Fig. This percolation threshold is about 40 times lower than that reported for clay-based composites Dynamic mechanical properties were therefore investigated in this work since many engineering rubbers are operated under dynamic loading. The storage modulus reflecting the elastic response of a rubber, is a measure of the recoverable strain energy in the rubber.
In Fig. When the GO content is up to 0. In summary, the present work demonstrated that GO sheets can be facially integrated into a rubber matrix by a new, versatile, and extremely simple approach based on latex technology. In this approach, a specific rubber-GO interaction and well-dispersed GO sheets in rubber matrix were obtained with the assistance of VPR to maximize the reinforcing efficiency.
The results also verified that the resulting composite can be easily processed and exhibit excellent mechanical properties and gas barrier property. This work might lead to future scalable production of GO-based rubber composites, and provides a new insight into the fabrication of high performance rubber composites for future engineering applications. Graphite oxide was prepared from flake graphite Fig. S1a by a modified Hummers method Then a mild ultrasonic treatment of graphite oxide in water results in its exfoliation to form stable graphene oxide GO colloid.
What are composite materials?
Proper ratio of the GO colloid containing 0. S1b , SBR latex containing S1c , and VPR latex containing 5.
S1e was then co-coagulated by a 1.
The coagulated composites Fig. The permeation experiments with nitrogen were carried out with a gas permeability apparatus pressure difference method.
Graphene-based composite materials
National Center for Biotechnology Information , U. Sci Rep. Published online Aug Tung W. Author information Article notes Copyright and License information Disclaimer. Received May 14; Accepted Aug 8. All rights reserved. This work is licensed under a Creative Commons Attribution 3.
This article has been cited by other articles in PMC. Open in a separate window. Figure 1.
Figure 2. Figure 3. Discussion The GO dispersion in composite and the interface interaction are the two main factors to determine the reinforcing efficiency of GO in the composite Figure 4. Figure 5. Methods Preparation of composites Graphite oxide was prepared from flake graphite Fig.
Author Contributions Y. References Geim A. The rise of graphene. Nature Mater. The chemistry of graphene oxide. Production, properties and potential of graphene. Carbon 48 , — On the gelation of graphene oxide. Preparation and characterization of graphene oxide paper.
Graphene based composite materials pdf merge
Nature , — Chemistry and physics of a single atomic layer: strategies and challenges for functionalization of graphene and graphene-based materials.
Extraordinary Physical Properties of Functionalized Graphene. Small 8 , — Probing the mechanical properties of graphene using a corrugated elastic substrate.