Graphene Oxide In Polymer Matrix Research Articles

Enhanced mechanical property, chemical resistance and abrasion durability of waterborne polyurethane based coating by incorporating highly dispersed polyacrylic acid modified graphene oxide

The incorporation of graphene oxide (GO) into waterborne polyurethane (WPU) coating shows great potential in enhancing the performance of WPU coating. But homogeneous dispersion of GO in polymer matrix is still a challenge for the application of GO. In this paper, the polyacrylic acid modified graphene oxide (PAA-nGO) with high dispersion stability in a wide range of pH (4–11) was prepared via two step amidation reaction. Significantly, PAA-nGO can be uniformly dispersed in WPU as bifunctional additive to prepare WPU/PAA-nGO coatings with enhanced mechanical property, chemical resistance and abrasion durability. The as-prepared WPU/PAA-nGO coating exhibited improved tensile strength (18.12 MPa) and tear strength (38.07 kN/m), which were 56.1% and 51.5% higher than those of pure WPU coating, respectively. Interestingly, WPU/PAA-nGO coating showed improved chemical resistance. Notably, abrasion durability of WPU/PAA-nGO coating was significantly enhanced, and the mass loss rate was decreased by 77.1%. Overall, this work provided a potential strategy for improving the mechanical property, chemical resistance and abrasion durability of WPU based coatings by introducing PAA-nGO with well dispersion and high stable in a wide pH range.

Wideband (8–18 GHz) microwave absorption dominated electromagnetic interference (EMI) shielding composite using copper aluminum ferrite and reduced graphene oxide in polymer matrix

The development of an efficient radar absorbing material (RAM) is a need of the day due to rapid growth in satellite, electronic, and telecommunication industries (especially, in the GHz frequency region). Herein, an easy fabrication technique is presented to design a lightweight and flexible absorption dominated electromagnetic interference shielding material by dispersion of magnetic nanoparticles of a CuAl2Fe10O19 (CFA) decorated reduced graphene oxide (RGO) filler into the polyvinylidene fluoride (PVDF) matrix. This has been done by a simple chemical reduction method in the presence of hydrazine. It was observed that the synergetic effect of all filler contents along with multiple relaxation mechanisms due to the interface of RGO, CFA, and PVDF leads to strong absorption rather than reflection. This makes the composite an excellent candidate for RAM in the X band as well as in the Ku band. To develop a material for absorption in wideband frequencies is challenging, especially if the intended absorption is above 60 dB. In the present work, shielding efficiency (SE) of ∼60 dB in the X band and ∼50 dB in the Ku band has been achieved with more than 90% SE due to absorption. The effect of an individual filler content in wave attenuation has been analyzed from the point of view of absorption coefficient, complex permittivity and permeability, and attenuation constant.

Thermal, Mechanical Properties and Rheological Behavior of Poly(Propylene Carbonate)/Poly(Ethylene Glycol)/Graphene Oxide Nanocomposites

Graphene oxide (GO) is an efficient nanofiller for polymers and a good dispersion of GO in polymer matrix is most important to enhance properties. Poly(propylene carbonate) (PPC)/GO nanocomposite was prepared by a method with solution blending and melt mixing for improvement of GO dispersion. First, GO was prepared using an improved Hummers method. In the solution blending, GO was well dispersed in water and another low molecular weight polymer, poly(ethylene glycol) (PEG), was also dispersed in water, as a dispersion medium for next melt mixing of PPC and GO. Then PPC and PEG/GO was melt-mixed in a HAAKE mixer. The dispersion of GO in PPC matrix and effect of GO content on properties of PPC/PEG/GO nanocomposites was investigated. Results show that tensile strength of nanocomposites with the content of 0.5 wt% GO increased from 17.51 MPa (pure PPC) to 21.61 MPa and elongation at break can be kept high. The complex viscosity, storage and loss modulus is the highest for nanocomposites with the content of 0.5 wt% GO. This illustrated that a lower content of GO can improve the properties of PPC, owing to the good dispersion of GO in PPC matrix. Based on dispersion of GO and chemical structure of PPC, PEG, and GO, the reinforcement mechanism of GO in PPC was analyzed.

The structure of graphene oxide in polymer matrix and its effect on reinforcement degree of nanocomposite

The methodics of characterization of 2D-nanofiller tactoids structure in polymer matrix of nanocomposite was proposed, which shown that the indicated tactoids are fractal objects with dimension of 1.75-2.16. This variation of tactoids structural state is due to interfacial interactions. It has been shown within the framework of reinforcement percolation theory, that structure of tactoids is single factor, defining reinforcement efficiency is characterized by its ability to create interfacial regions.

Preparation of polymer/graphene oxide nanocomposites by a two-step strategy composed of in situ polymerization and melt processing

Pickering emulsion-templated polystyrene (PS)/graphene oxide (GO) composite microspheres were successfully prepared using surface-functionalized silica as the stabilizer. These preformed polymer/GO composite microspheres were then melt-blended into polymer matrix to prepare nanocomposite materials in a short minute using HAAKE torque rheometer. Transmission electron microscope (TEM) images of the nanocomposites demonstrate that GO is uniformly dispersed into PS matrix. A significant decrease of coefficient of thermal expansion (CTE) values from more than 150 to 50 ppm/K is realized with the introduction of well-dispersed GO nanosheets. The glass transition temperature (Tg) and the temperature of 5% weight loss (T0.05) are increased by 5 and 17 °C, respectively. Furthermore, the impact energy of the composite sample with a GO loading of 0.86% is 64% greater than that of pure PS, and is nearly twice as high as that of the composite which was prepared by direct melt-blending of surface-modified GO and commercial PS. The tensile strength and elongation at break of the composites are also obviously improved. The work provides an economic and convenient method which eliminates the dispersion problem of GO in polymer matrix to prepare GO-based nanocomposite materials for industrial application on a large scale.

Superior electromagnetic interference shielding effectiveness and electro-mechanical properties of EMA-IRGO nanocomposites through the in-situ reduction of GO from melt blended EMA-GO composites

Abstract Fabrication of high-performance electromagnetic interference shielding efficient polymer-graphene nanocomposite is very challenging approach against electromagnetic pollution. Present work emphasizes on the preparation of in-situ reduced graphene oxide (IRGO) through in-situ melt blending of ethylene methyl acrylate (EMA) and graphene oxide (GO) to achieve enhanced shielding efficiency (SE) with controlled electro-mechanical properties of the composites. It involves the reduction mechanism of graphene oxide (GO) within polymer matrices, where efficacy highly influenced by methodologies, polymer chemistry as well as the processing parameters. 5 wt% IRGO loaded nanocomposite showed most improved shielding effectiveness (∼30 dB) over the frequency range of 8.2–12.4 GHz whereas beyond this loading (7 wt%) the re-aggregation of the IRGO platelets cannot be ruled out due to high surface energy of the GO. High abundance of GO in polymer matrix can form better conducting pathways but due to lack of dispersion, the stress transfer during mechanical workout become inferior than other GO loaded composites. This hybrid nanocomposite fashioned 3D conductive network through segregated architecture in the matrix to commit lower conductive percolation with remarkable mechanical strength for its structural integrity. We believe this promising strategy of developing single step EMA-in-situ RGO (EIRGO) nanocomposites with enhanced shielding efficiency and amendable electro-mechanical properties can endorse large-scale production for techno-commercial applications.

Evaluation of dosimetric characteristics of graphene oxide/PVC nanocomposite for gamma radiation applications

Abstract Graphene oxide-polyvinyl chloride composite was prepared using tetrahydrofuran solvent-assisted dispersion of characterized nano flakes of graphene oxide in polymer matrix. Electrical percolation threshold of GO/PVC nanocomposite was determined via a finite element simulation method with a 2D model and compared with experimental results. A conductive cell with two silver coated walls was designed and fabricated for exploring dosimetric properties of the composite. Some characteristics of the new nanocomposite such as linearity of dose response, repeatability, sensitivity and angular dependence are investigated. According to 2D proposed method, obtained data associated to electrical conductivity of the GO/polymer composite for PVC matrix plotted in different GO weight percentages and had good compatibility (validity) with experimental data. The dose response is linear in the 17–51 mGy dose range and it can be introduced for gamma radiation dosimetry in diagnostic activities.

Facile preparation of poly(p-phenylene benzobisoxazole)/graphene composite films via one-pot in situ polymerization

Since being discovered, graphene shows promise as reinforcements in high-performance nanocomposites. In the present study, we describe a novel strategy to design and prepare poly(p-phenylene benzobisoxazole) (PBO)/graphene composite. Graphene oxide (GO) was first modified by 4, 6-diaminoresorcinol (DAR) to improve the reactivity, solubility, and dispersivity of GO in polymer matrix. Without separation and purification, GO-DAR was further incorporated with PBO through in situ polymerization, and PBO/GO composite films were obtained by thermoforming process. The structure and morphology of GO-DAR and PBO/GO films were characterized and the mechanical and thermal properties were investigated. The incorporation of GO improved the thermal stability of PBO. Mechanical property measurements revealed that the PBO/GO films exhibited a tensile strength (148 MPa) and Young's modulus (6.2 GPa) at a GO loading of 1.5 wt%, corresponding to 39.6% and 72.2% increase compared to the PBO film, respectively. The one-pot in situ procedure wraps GO with PBO chains, improves the dispersion and alignment of GO in PBO matrix, enhances PBO chain packing order, which are considered to be the main reasons for the performance improvement of PBO.