In this review, recent progress in the mechanical, thermal and interfacial properties of graphene/CNT multiphase polymer composites is examined. Progress in the mechanical and thermal properties of CNT (1D) and graphene (2D) nanostructure materials is also reviewed and compared. Furthermore, this review highlights the improvements in the mechanical, thermal and interfacial properties of two- and three-phase composites, owing to the addition of graphene/CNT. In particular, analysis of several notable papers on hybrid composites (graphene/CNT) provides an intensive review of synergetic effects on the overall properties of the corresponding composites. This holistic review describes an improved interface between fibers and a nanofiller-reinforced matrix. Although the presence of nanofillers even at low loadings confers an overall improvement in composite properties, the exact ratios of individual fillers and combined forms remain to be discussed in depth. Finally, potential applications, current challenges and future perspectives for use of these multiphase composites are discussed with regard to their extraordinary capabilities and promising developments in graphene/CNT family-based composite materials.

Carbon nanotube- and graphene-reinforced multiphase polymeric composites: review on their properties and applications

This paper reports the use of multiwalled carbon nanotubes (MWCNT) to reinforce and toughen gel-spun ultra high molecular weight polyethylene (UHMWPE) fibers. By adding 5 wt% MWCNT, ultra strong fibers with tensile strengths of 4.2 GPa and strain at break of ∼5% can be produced. In comparison with the pure UHMWPE fiber at the same draw ratios, these values represent increases of 18.8% in tensile strength and 15.4% in ductility. In addition, a 44.2% increase in energy to fracture has also been observed. The mechanism of reinforcement has been studied using a combination of high resolution scanning electron microscopy (SEM) and micro-Raman spectroscopy. Carbon nanotube alignment along the tensile draw direction has been observed at high elongation ratios. Such alignment induces strong interfacial load transfer both at small and large strains to enhance the stiffness and tensile strength of the composite fiber. Consequently, the mechanical properties of the composite fiber follow closely with the rule of mixtures. Our work also reveals potential for positive deviation from rule of mixtures if the CNT alignment can be further optimized.

Ultra-strong gel-spun UHMWPE fibers reinforced using multiwalled carbon nanotubes

Recent developments in nanofiltration membranes based on nanomaterials

Graphene-related materials (GRMs) have been identified as excellent nano-reinforcements for carbon fibre reinforced polymers (CFRPs) with regard to a wide range of engineering applications. GRMs are easily produced from their chief source, graphite, which is relatively affordable and abundantly available around the globe. The outstanding properties of GRMs, such as their large surface area, high mechanical strength and low manufacturing cost bring them to be distinguished nano-reinforcements for CFRPs to form multi-functional and multiscale composites. In this paper, the importance of using GRMs to enhance the properties of CFRPs is highlighted. Different synthesis methods for depositing GRMs onto the surface of carbon fibre and their effectiveness of improving the properties of host materials are reviewed and discussed. At this stage, more works are still needed to understand the basic stress transfer mechanism of GRM-coated CF composites. Their property enhancement at cryogenic environment are crucial for new aircraft and space engineering development.

Surface modification of carbon fibre using graphene–related materials for multifunctional composites

Ongoing progress on novel nanocomposite membranes for the separation of heavy metals from contaminated water.

Preparation of poly(vinyl alcohol)-grafted graphene oxide/poly(vinyl alcohol) nanocomposites via in-situ low-temperature emulsion polymerization and their thermal and mechanical characterization

Here, a high breaking strength and high initial modulus fibers comprised of polyvinyl alcohol (PVA) and graphene oxide (GO) were fabricated via simple method of solution blending and wet-spinning. The structure and properties of these fibers were studied in details using two-dimensional X-ray diffractions, differential scanning calorimetry, one-dimensional X-ray diffractions, scanning electron microscopy, transmission electron microscopy, dynamic mechanical analysis and tensile test. Compared with pure PVA fiber, a 43 % improvement of breaking strength and an 81 % improvement of initial modulus were achieved by addition of 0.1 wt% of GO, and the results indicated that crystallization and orientation of GO/PVA composite fibers were both increased. GO could not only promote PVA chains ordered arrangement for increasing crystallization, but also act as a template for polymer amorphous orientation via the interactions between PVA and GO in the process of hot drawing and heat setting, which were responsible for the significant improvement in the mechanical properties of GO/PVA composite fibers.

Graphene oxide reinforced poly(vinyl alcohol) composite fibers via template-oriented crystallization

A kind of flame-retardant polyacrylonitrile fiber was prepared successfully by the modification with diethylenetriamine and zinc ions (Zn2+). The chemical, aggregation and morphological structures of the aminated fibers were studied by Fourier transform infrared (FTIR) spectra, X-ray diffraction and scanning electron microscope (SEM). Meanwhile, mechanical and adsorption properties were investigated by a tensile tester and atomic absorption spectrometry. The flame retardancy of the modified fibers was significantly improved after modification. And the thermal degradation behaviors and flame retardancy mechanisms were studied in detail. The microscale combustion calorimeter and TG-FTIR results showed that the modified fibers decomposed less combustible gases and more non-combustible gases comparing the original fibers. And thermogravimetric analysis and SEM tests revealed that Zn2+ would stabilize the main chains and promote formation of compact char layers. And differential scanning calorimetry tests indicated that Zn2+ would inhibit the cyclization exothermic process. Results showed that the combination of gas phase and condensed phase mechanisms optimized the flame retardancy performance.

Preparation, flame retardancy and thermal degradation behaviors of polyacrylonitrile fibers modified with diethylenetriamine and zinc ions

Poly(vinyl alcohol)-grafted Graphene oxide (PVA-g-GO) as novel nanofillers were used to reinforce poly(vinyl alcohol) (PVA) composite fibers via simple wet spinning to promote homogeneous dispersion of reinforcing nanofillers as well as strengthen interfacial adhesion between nanofillers and matrix. Then the impact of these PVA chains grafted above GO sheets on the compatibility and dispersion of PVA-g-GO sheets in PVA fiber, the interfacial adhesion between nanofillers and matrix and the structure as well as property of PVA-g-GO/PVA fibers were studied systematically via characterizing morphology, aggregation structure and mechanical property of these composite fibers. These results showed that not only well dispersion and compatibility of PVA-g-GO sheets in composite fibers could be achieved, but also obvious enhancement in interfacial adhesion between nanofillers and matrix. Meanwhile, significant reinforcement in tensile strength and initial modulus of these composite fibers could also be obtained. Compared with neat PVA drawn fiber, tensile strength and initial modulus of these composite drawn fibers could increase by 39% and 69% with addition of 0.60 wt% of PVA-g-GO sheets, respectively. On the one hand, crystallization and orientation degree of these composite fibers could be improved because of the template-oriented effect of PVA-g-GO sheets during hot drawing. On the other hand, efficient load transfer between matrix and nanofillers in composite drawn fibers could be achieved easily because of the strong interfacial adhesion between nanofillers and matrix. These were also two main reasons for the obvious improvement in tensile strength and initial modulus of composite drawn fibers.

Enhanced tensile strength and initial modulus of poly(vinyl alcohol)/graphene oxide composite fibers via blending poly(vinyl alcohol) with poly(vinyl alcohol)-grafted graphene oxide

Xiangsen Zhao

Papers

Preparation of poly(vinyl alcohol)-grafted graphene oxide/poly(vinyl alcohol) nanocomposites via in-situ low-temperature emulsion polymerization and their thermal and mechanical characterization

Graphene oxide reinforced poly(vinyl alcohol) composite fibers via template-oriented crystallization

Preparation, flame retardancy and thermal degradation behaviors of polyacrylonitrile fibers modified with diethylenetriamine and zinc ions

Enhanced tensile strength and initial modulus of poly(vinyl alcohol)/graphene oxide composite fibers via blending poly(vinyl alcohol) with poly(vinyl alcohol)-grafted graphene oxide