Journal of Composites Science

Research

14 pages, 4750 KiB

Open AccessArticle

Temperature Self-Compensated Strain Sensors based on MWCNT-Graphene Hybrid Nanocomposite

by Rajarajan Ramalingame, Jose Roberto Bautista-Quijano, Danrlei de Farias Alves and Olfa Kanoun

J. Compos. Sci. 2019, 3(4), 96; https://doi.org/10.3390/jcs3040096 - 7 Nov 2019

Cited by 17 | Viewed by 3751

Sensors based on carbon nanomaterials are gaining importance due to their tunable properties and their potentially outstanding sensing performance. Despite their advantages, carbon-based nanomaterial sensors are prone to cross-sensitivities with environmental factors like temperature. Thus, to reduce the temperature influence on the sensing [...] Read more.

Sensors based on carbon nanomaterials are gaining importance due to their tunable properties and their potentially outstanding sensing performance. Despite their advantages, carbon-based nanomaterial sensors are prone to cross-sensitivities with environmental factors like temperature. Thus, to reduce the temperature influence on the sensing material, compensation and correction procedures are usually considered. These methods may require the use of additional sensors which can themselves be subject to residual errors. Hence, a more promising approach consists of synthesizing a material that is capable of self-compensating for the influence of temperature. In this study, a hybrid nanocomposite based on multi-walled carbon nanotubes (MWCNT) and graphene is proposed, which can compensate, by itself, for the influence of temperature on the material conductivity. The hybrid nanocomposite material uses the different temperature behavior of MWCNTs, which have a negative temperature coefficient, and graphene, which has a positive temperature coefficient. The influence of the material ratio and dispersion quality are investigated in this work. Material composition and dispersion quality are analyzed using Raman spectroscopy and scanning electron microscopy (SEM). A composition of 70% graphene and 30% MWCNT exhibits a nearly temperature-independent hybrid nanocomposite with a sensitivity of 0.022 Ω/°C, corresponding to a resistance change of ~1.2 Ω for a temperature range of 25 to 80 °C. Additionally, a simple investigation of the strain sensing behavior of the hybrid material is also presented. The hybrid nanocomposite-based, thin-film strain sensor exhibits good stability over 100 cycles and a significantly high gauge factor, i.e., 16.21. Full article

(This article belongs to the Special Issue Recent Advances in Graphene-based Nanocomposites)

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12 pages, 4011 KiB

Open AccessArticle

Evaluation of a Nanocomposite Based on Reduced Graphene Oxide and Gold Nanoparticles as an Electrochemical Platform for Detection of Sulfamethazine

by Martin Silva and Ivana Cesarino

J. Compos. Sci. 2019, 3(2), 59; https://doi.org/10.3390/jcs3020059 - 8 Jun 2019

Cited by 14 | Viewed by 3657

Abstract

A nanocomposite based on reduced graphene oxide (rGO) and gold nanoparticles (AuNPs) was synthesized by the microwave-assisted hydrothermal method and applied in the determination of sulfamethazine (SMZ) in swine effluent using a glassy carbon (GC) electrode. The rGO-AuNPs nanocomposite was characterized morphologically, electrochemically [...] Read more.

A nanocomposite based on reduced graphene oxide (rGO) and gold nanoparticles (AuNPs) was synthesized by the microwave-assisted hydrothermal method and applied in the determination of sulfamethazine (SMZ) in swine effluent using a glassy carbon (GC) electrode. The rGO-AuNPs nanocomposite was characterized morphologically, electrochemically and spectrochemically, showing that rGO was modified with the AuNPs. The GC/rGO-AuNPs electrode was optimized for the determination of SMZ, achieving detection limits of 0.1 μmol L⁻¹. The proposed sensor was successfully applied to the determination of SMZ in synthetic swine effluent samples. Full article

(This article belongs to the Special Issue Recent Advances in Graphene-based Nanocomposites)

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9 pages, 3246 KiB

Open AccessArticle

Production and Mechanical Characterization of Graphene Micro-Ribbons

by Maria Giovanna Pastore Carbone, Georgia Tsoukleri, Anastasios C. Manikas, Eleni Makarona, Christos Tsamis and Costas Galiotis

J. Compos. Sci. 2019, 3(2), 42; https://doi.org/10.3390/jcs3020042 - 16 Apr 2019

Cited by 5 | Viewed by 3385

Abstract

Patterning of graphene into micro- and nano-ribbons allows for tunability in emerging fields such as flexible electronic and optoelectronic devices, and is gaining interest for the production of more efficient reinforcement for composite materials. In this work we fabricate micro-ribbons from graphene synthesized [...] Read more.

Patterning of graphene into micro- and nano-ribbons allows for tunability in emerging fields such as flexible electronic and optoelectronic devices, and is gaining interest for the production of more efficient reinforcement for composite materials. In this work we fabricate micro-ribbons from graphene synthesized via chemical vapor deposition (CVD) by combining ultraviolet (UV) photolithography and dry etching oxygen plasma treatments. We used Raman spectral imaging to confirm the effectiveness of the patterning procedure, which is suitable for large-area patterning of graphene on wafer-scale, and confirms that the quality of graphene remains unaltered. The produced micro-ribbons were finally transferred and embedded into a polymeric matrix and the mechanical response was investigated by in-situ mechanical investigation combining Raman spectroscopy and tensile/compressive tests. Full article

(This article belongs to the Special Issue Recent Advances in Graphene-based Nanocomposites)

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11 pages, 1953 KiB

Open AccessArticle

Nucleation of the β-polymorph in Composites of Poly(propylene) and Graphene Nanoplatelets

by Valentina Guerra, Chaoying Wan and Tony McNally

J. Compos. Sci. 2019, 3(2), 38; https://doi.org/10.3390/jcs3020038 - 8 Apr 2019

Cited by 11 | Viewed by 4592

Abstract

The effects of graphene nanoplatelets (GNPs) on the nucleation of the β-polymorph of polypropylene (PP) were studied when melt-mixed at loadings of 0.1–5 wt % using a laboratory scale twin-screw (conical) extruder and a twin-screw (parallel) extruder with L/D = 40. At low [...] Read more.

The effects of graphene nanoplatelets (GNPs) on the nucleation of the β-polymorph of polypropylene (PP) were studied when melt-mixed at loadings of 0.1–5 wt % using a laboratory scale twin-screw (conical) extruder and a twin-screw (parallel) extruder with L/D = 40. At low GNP loadings (i.e., ≤0.3 wt %), the mixing efficiency of the extruder used correlated with the β-nucleating activity of GNPs for PP. GNP agglomeration at low loadings (<0.5 wt %) resulted in an increase in the β-phase fraction (K_β) of PP, as determined from X-ray diffraction measurements, up to 37% at 0.1 wt % GNPs for composites prepared using a laboratory scale twin-screw (conical) extruder. The level of GNP dispersion and distribution was better when the composites were prepared using a 16-mm twin-screw (parallel) extruder, giving a K_β increase of 24% upon addition of 0.1 wt % GNPs to PP. For GNP loadings >0.5 wt %, the level of GNP dispersion in PP did not influence the growth of β-crystals, where K_β reached a value of 24%, regardless of the type of extruder used. From differential scanning calorimetry (DSC) measurements, the addition of GNPs to PP increased the crystallization temperature (T_c) of PP by 14 °C and 10 °C for the laboratory scale extruder and 16-mm extruder, respectively, confirming the nucleation of PP by GNPs. The degree of crystallinity (X_c%) of PP increased slightly at low GNP additions (≤0.3 wt %), but then decreased with increasing GNP content. Full article

(This article belongs to the Special Issue Recent Advances in Graphene-based Nanocomposites)

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10 pages, 2033 KiB

Open AccessArticle

Preparation of Piezo-Resistive Materials by Combination of PP, SEBS and Graphene

by Helga Seyler, Marián A. Gómez-Fatou and Horacio J. Salavagione

J. Compos. Sci. 2019, 3(2), 37; https://doi.org/10.3390/jcs3020037 - 3 Apr 2019

Cited by 2 | Viewed by 3362

Abstract

The use of polyolefins in structural components requires the simultaneous improvement of stiffness and toughness of the matrix, whilst in the case of sensing components during operation, additional functions are needed such as electrical conductivity. However, providing various desired properties without impairing those [...] Read more.

The use of polyolefins in structural components requires the simultaneous improvement of stiffness and toughness of the matrix, whilst in the case of sensing components during operation, additional functions are needed such as electrical conductivity. However, providing various desired properties without impairing those intrinsic to the materials can be somewhat challenging. In this study we report the preparation of an isotactic polypropylene (iPP)/styrene–ethylene–butylene–styrene triblock copolymer (SEBS)/graphene system that combines enhanced mechanical properties with electrical conductivity. Blends were prepared by solution mixing (SoM) and solution/solid state mixing (SoM/SSM) formulation routes prior to melt processing. The nanocomposites were characterized by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) and the electrical and mechanical properties were evaluated. The materials prepared via the SoM/SSM route displayed good electrical conductivity while retaining the mechanical properties of iPP, making them attractive materials for low cost and high throughput structural components with sensing capacity. Full article

(This article belongs to the Special Issue Recent Advances in Graphene-based Nanocomposites)

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14 pages, 3778 KiB

Open AccessArticle

Composite Films of Waterborne Polyurethane and Few-Layer Graphene—Enhancing Barrier, Mechanical, and Electrical Properties

by Eunice Cunha and Maria C. Paiva

J. Compos. Sci. 2019, 3(2), 35; https://doi.org/10.3390/jcs3020035 - 3 Apr 2019

Cited by 11 | Viewed by 3492

Abstract

Graphene has excellent mechanical, thermal, and electrical properties. Graphene can serve as potential reinforcement in polymer-based nanocomposites. In order to achieve this goal, graphene has to be distributed homogeneously and dispersed throughout the polymer matrix, establishing a strong interface with the polymer. Solution [...] Read more.

Graphene has excellent mechanical, thermal, and electrical properties. Graphene can serve as potential reinforcement in polymer-based nanocomposites. In order to achieve this goal, graphene has to be distributed homogeneously and dispersed throughout the polymer matrix, establishing a strong interface with the polymer. Solution mixing is an interesting method for the preparation of homogeneous nanocomposites, in particular when using environmentally friendly solvents such as water. The major difficulty met in the production of graphene/polymer composites concerns the preparation and stabilization of graphene in aqueous suspension. In the present work three different graphite-based materials, with different crystallinity and purity grades, were exfoliated in aqueous solution of an amphiphilic pyrene derivative, forming few-layer graphene (FLG). The FLG prepared was dispersed in waterborne polyurethane (WPU) to produce composite films. The composite films were produced by solvent casting and spray coating, forming free-standing films that were characterized in terms of its distribution of FLG through the composite, its permeability to water vapor, its electrical resistivity, and its mechanical properties. The studies demonstrated the influence of different factors on the composite film properties such as the use of graphite vs. FLG, the FLG lateral dimensions, and the FLG composition and composite preparation method. Full article

(This article belongs to the Special Issue Recent Advances in Graphene-based Nanocomposites)

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8 pages, 3567 KiB

Open AccessArticle

Preparation and Mechanical Properties of Graphene/Carbon Fiber-Reinforced Hierarchical Polymer Composites

by Jose M. Vázquez-Moreno, Ruben Sánchez-Hidalgo, Estela Sanz-Horcajo, Jaime Viña, Raquel Verdejo and Miguel A. López-Manchado

J. Compos. Sci. 2019, 3(1), 30; https://doi.org/10.3390/jcs3010030 - 25 Mar 2019

Cited by 41 | Viewed by 6121

Abstract

Conventional carbon fiber-reinforced plastics (CFRP) have extensively been used as structural elements in a myriad of sectors due to their superior mechanical properties, low weight and ease of processing. However, the relatively weak compression and interlaminar properties of these composites limit their applications. [...] Read more.

Conventional carbon fiber-reinforced plastics (CFRP) have extensively been used as structural elements in a myriad of sectors due to their superior mechanical properties, low weight and ease of processing. However, the relatively weak compression and interlaminar properties of these composites limit their applications. Interest is, therefore, growing in the development of hierarchical or multiscale composites, in which, a nanoscale filler reinforcement is utilized to alleviate the existing limitations associated with the matrix-dominated properties. In this work, the fabrication and characterization of hierarchical composites are analyzed through the inclusion of graphene to conventional CFRP by vacuum-assisted resin infusion molding. Full article

(This article belongs to the Special Issue Recent Advances in Graphene-based Nanocomposites)

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11 pages, 3583 KiB

Open AccessArticle

Wear Behavior of Copper–Graphite Composites Processed by Field-Assisted Hot Pressing

by Qian Liu, Miguel Castillo-Rodríguez, Antonio Julio Galisteo, Roberto Guzmán de Villoria and José Manuel Torralba

J. Compos. Sci. 2019, 3(1), 29; https://doi.org/10.3390/jcs3010029 - 25 Mar 2019

Cited by 20 | Viewed by 3836

Abstract

Copper–graphite composites with 0–4 wt % graphite were fabricated by field-assisted hot pressing with the aim of studying the effect of graphite content on microhardness and tribological properties. Experimental results reveal that hardness decreases with the graphite content. Wear testing was carried out [...] Read more.

Copper–graphite composites with 0–4 wt % graphite were fabricated by field-assisted hot pressing with the aim of studying the effect of graphite content on microhardness and tribological properties. Experimental results reveal that hardness decreases with the graphite content. Wear testing was carried out using a ball-on-disc tribometer with a normal load of 8 N at a constant sliding velocity of 0.16 m/s. The friction coefficient of composites decreases significantly from 0.92 to 0.29 with the increase in graphite content, resulting in a friction coefficient for the 4 wt % graphite composite that is 68.5% lower than pure copper. The wear rate first increases when the graphite content is 1 wt %; it then decreases as the graphite content is further increased until a certain critical threshold concentration of graphite, which seems to be around 3 wt %. Plastic deformation in conjunction with some oxidative wear is the wear mechanism observed in pure copper, while abrasive wear is the main wear mechanism in copper–graphite composites. Full article

(This article belongs to the Special Issue Recent Advances in Graphene-based Nanocomposites)

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8 pages, 2083 KiB

Open AccessArticle

Atomic Structure and Mechanical Properties of Twisted Bilayer Graphene

by Shaolong Zheng, Qiang Cao, Sheng Liu and Qing Peng

J. Compos. Sci. 2019, 3(1), 2; https://doi.org/10.3390/jcs3010002 - 23 Dec 2018

Cited by 42 | Viewed by 5563

Abstract

We studied the atomic structure and mechanical properties of twisted bilayer graphene with a different twist angle using molecular dynamic simulations. The two layers are corrugated after energy minimization. We found two different modes of corrugation. The mechanical properties are tested both in-plane [...] Read more.

We studied the atomic structure and mechanical properties of twisted bilayer graphene with a different twist angle using molecular dynamic simulations. The two layers are corrugated after energy minimization. We found two different modes of corrugation. The mechanical properties are tested both in-plane and perpendicular to the plane. The in-plane properties are dominated by the orientation of graphene. The perpendicular properties depend on the twist angle, as the larger the twist angle, the higher the intrinsic strength. Full article

(This article belongs to the Special Issue Recent Advances in Graphene-based Nanocomposites)

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