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14 pages, 3559 KiB

Open AccessArticle

Preliminary Investigations and Support for the Mechanical and Dynamic Characteristics of a Natural Rubber Reinforcement in E-Glass/CNT/Epoxy Composite

by Selvaraj Anidha, Santhosh Mozhuguan Sekar, Elango Natarajan, Manickam Muthukkumar, Kalaimani Markandan, Chun Kit Ang and Gérald Franz

J. Compos. Sci. 2024, 8(4), 140; https://doi.org/10.3390/jcs8040140 - 10 Apr 2024

Cited by 2 | Viewed by 1267

Abstract

The present investigation reports the synthesis and mechanical properties of a hybrid polymer composite consisting of E-Glass fiber, epoxy and 2 wt.% carbon nanotubes (CNTs) with a varying percentage of natural rubber (NR). The prepared hybrid polymer composites were examined in terms of [...] Read more.

The present investigation reports the synthesis and mechanical properties of a hybrid polymer composite consisting of E-Glass fiber, epoxy and 2 wt.% carbon nanotubes (CNTs) with a varying percentage of natural rubber (NR). The prepared hybrid polymer composites were examined in terms of their surface morphology, thermal properties as well as mechanical properties. The findings from the present study indicate that natural rubber enhances the mechanical properties of the hybrid polymer composites and, in particular, 10 wt.% is the optimum percentage of NR that yields the highest strength of 88 MPa, while the strength is 52 MPa with 5 wt.% NR. In order to evaluate the damping properties, a dynamic mechanical analysis was carried out on the E-Glass/CNT with NR composites at various frequencies along with a thermogravimetric analysis. It was found that the composite reinforced with 10 wt.% natural rubber exhibited a higher glass transition temperature of 376.86 °C and storage modulus of 2468 MPa when compared to the other composites, which indicates the enhanced cross-linking density and higher polymer modulus of the composite. X-ray diffraction analysis was also conducted and the results are reported to improve the general understanding of crystalline phases. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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16 pages, 4638 KiB

Open AccessArticle

Comparative Thermoelectric Properties of Polypropylene Composites Melt-Processed Using Pyrograf^® III Carbon Nanofibers

by Antonio J. Paleo, Beate Krause, Ana R. Mendes, Carlos J. Tavares, Maria F. Cerqueira, Enrique Muñoz and Petra Pötschke

J. Compos. Sci. 2023, 7(4), 173; https://doi.org/10.3390/jcs7040173 - 20 Apr 2023

Cited by 7 | Viewed by 2093

Abstract

The electrical conductivity (σ) and Seebeck coefficient (S) at temperatures from 40 °C to 100 °C of melt-processed polypropylene (PP) composites filled with 5 wt.% of industrial-grade carbon nanofibers (CNFs) is investigated. Transmission Electron Microscopy (TEM) of the two Pyrograf^® III CNFs [...] Read more.

The electrical conductivity (σ) and Seebeck coefficient (S) at temperatures from 40 °C to 100 °C of melt-processed polypropylene (PP) composites filled with 5 wt.% of industrial-grade carbon nanofibers (CNFs) is investigated. Transmission Electron Microscopy (TEM) of the two Pyrograf^® III CNFs (PR 19 LHT XT and PR 24 LHT XT), used in the fabrication of the PP/CNF composites (PP/CNF 19 and PP/CNF 24), reveals that CNFs PR 24 LHT XT show smaller diameters than CNFs PR 19 LHT XT. In addition, this grade (PR 24 LHT XT) presents higher levels of graphitization as deduced by Raman spectroscopy. Despite these structural differences, both Pyrograf^® III grades present similar σ (T) and S (T) dependencies, whereby the S shows negative values (n-type character). However, the σ (T) and S (T) of their derivative PP/CNF19 and PP/CNF24 composites are not analogous. In particular, the PP/CNF24 composite shows higher σ at the same content of CNFs. Thus, with an additionally slightly more negative S value, the PP/CNF24 composites present a higher power factor (PF) and figure of merit (zT) than PP/CNF19 composites at 40 °C. Moreover, while the σ (T) and S (T) of CNFs PR 19 LHT XT clearly drive the σ (T) and S (T) of its corresponding PP/CNF19 composite, the S (T) of CNFs PR 24 LHT XT does not drive the S (T) observed in their corresponding PP/CNF24 composite. Thus, it is inferred in PP/CNF24 composites an unexpected electron donation (n-type doping) from the PP to the CNFs PR 24 LHT XT, which could be activated when PP/CNF24 composites are subjected to that increase in temperature from 40 °C to 100 °C. All these findings are supported by theoretical modeling of σ (T) and S (T) with the ultimate aim of understanding the role of this particular type of commercial CNFs on the thermoelectrical properties of their PP/CNF composites. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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17 pages, 15515 KiB

Open AccessArticle

From Flat Plates to Sinusoidal Structures: Influence of Geometry on the Energy Absorption Capability of Carbon/Epoxy Composites

by Mehmet Engül and Nuri Ersoy

J. Compos. Sci. 2023, 7(2), 56; https://doi.org/10.3390/jcs7020056 - 3 Feb 2023

Cited by 3 | Viewed by 1483

Abstract

Composite structures have excellent performance related to energy absorption during crush events. Among various factors, geometry has a significant influence on the specific energy absorption (SEA) performance of composites; however, the variation of crush-induced failure mechanisms for various geometric features and the way [...] Read more.

Composite structures have excellent performance related to energy absorption during crush events. Among various factors, geometry has a significant influence on the specific energy absorption (SEA) performance of composites; however, the variation of crush-induced failure mechanisms for various geometric features and the way they affect energy absorption capability have not yet been fully clarified. Moving from simple to complex composite structures, a holistic study investigating the influence of geometry on the SEA is required. This paper presents experimental and numerical investigations of the crushing process for flat plates, semi-circle geometries, and sinusoidal structures with different diameters and numbers of curvatures. In a numerical analysis, a finite element (FE) model with the idea of an artificial plug-initiator was developed for the accurate and realistic crushing behavior of sinusoidal specimens. The results were discussed and compared in terms of the observed failure mechanisms. The sinusoidal structure with the highest energy absorption capability was identified. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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18 pages, 12841 KiB

Open AccessArticle

Effect of Annealing and Diameter on Tensile Property of Spinnable Carbon Nanotube and Unidirectional Carbon Nanotube Reinforced Epoxy Composite

by Naoki Tokumitsu, Yoshinobu Shimamura, Tomoyuki Fujii and Yoku Inoue

J. Compos. Sci. 2022, 6(12), 389; https://doi.org/10.3390/jcs6120389 - 14 Dec 2022

Cited by 3 | Viewed by 1866

Abstract

Carbon nanotubes (CNTs) are thought to have higher elastic modulus and strength than carbon fibers. The recent development of spinnable multi-walled carbon nanotubes (MWNTs) enables us to produce unidirectional MWNT reinforced polymer-based composites with a higher volume fraction of CNTs. The results of [...] Read more.

Carbon nanotubes (CNTs) are thought to have higher elastic modulus and strength than carbon fibers. The recent development of spinnable multi-walled carbon nanotubes (MWNTs) enables us to produce unidirectional MWNT reinforced polymer-based composites with a higher volume fraction of CNTs. The results of tensile tests of spinnable MWNTs in scanning electron microscopes show, however, that Young’s modulus and tensile strength of MWNTs are not as high as expected. Annealing and developing thinner spinnable MWNTs will be the solution to improving the tensile property. In this study, as-produced and annealed untwisted yarns composed of MWNTs with three different diameters were prepared, and the tensile properties of spinnable MWNTs were estimated from the tensile properties of the untwisted yarns to investigate the effect of annealing and diameter on the overall tensile property of MWNTs. Furthermore, tensile tests of unidirectional MWNT reinforced epoxy composites were conducted and the contribution of the tensile property of MWNTs to the bulk tensile property of the composite was discussed. As a result, it was found that MWNTs with thinner diameters had higher Young’s modulus and tensile strength and annealing improved Young’s modulus of MWNTs, in addition to that the bulk tensile property of unidirectional MWNT reinforced epoxy composites was primarily determined by the tensile property of MWNTs. The results support previous findings from a limited number of tensile tests in SEM/TEM, and also reveal the validity of estimating the tensile properties of individual CNTs by tensile testing of untwisted yarns. In addition, the discussion on composite materials suggests that the tensile property of composite materials can be enhanced by improving the tensile property of MWNTs. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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24 pages, 17144 KiB

Open AccessArticle

Stiffness Degradation under Cyclic Loading Using Three-Point Bending of Hybridised Carbon/Glass Fibres with a Polyamide 6,6 Nanofibre Interlayer

by Ashley Blythe, Bronwyn Fox, Mostafa Nikzad, Boris Eisenbart and Boon Xian Chai

J. Compos. Sci. 2022, 6(9), 270; https://doi.org/10.3390/jcs6090270 - 14 Sep 2022

Cited by 13 | Viewed by 2613

Abstract

The stiffness degradation of hybrid carbon/glass fibre composites are investigated under cyclic loading in three-point bending. The composites are compared to toughened composites interlayered with PA 6,6 nanofibre (veil) and a matrix toughened with 5% rubber particulate. With the incorporation of veil into [...] Read more.

The stiffness degradation of hybrid carbon/glass fibre composites are investigated under cyclic loading in three-point bending. The composites are compared to toughened composites interlayered with PA 6,6 nanofibre (veil) and a matrix toughened with 5% rubber particulate. With the incorporation of veil into the hybridised composite, the hybrid interface experienced extensive localised delamination, due to crack deflection, causing longitudinal cracking between the fibre and veil interface. It is observed that delamination was redirected and reduced by veil interlayering, due to crack bridging as the cracks propagated. The carbon fibre composites toughened by rubber particulate showed similar stiffness retention to carbon fibre after 1,000,000 cycles. The veil interlayering within carbon fibre improved the stiffness retention by 66.87% for the flexural modulus, compared to carbon fibre and rubber toughened carbon fibre laminates. In both glass and carbon fibre samples, the stiffness retention with veil showed a 10-fold increase in fatigue life, compared with untoughened controls. It is observed from the failure mechanics that veil acted as a randomly orientated fibre layer, rather than a matrix toughener. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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14 pages, 3167 KiB

Open AccessArticle

Development of Improved Flexural and Impact Performance of Kevlar/Carbon/Glass Fibers Reinforced Polymer Hybrid Composites

by Sonali Rout, Ramesh Kumar Nayak, Suresh Chandra Patnaik and Hamed Yazdani Nezhad

J. Compos. Sci. 2022, 6(9), 245; https://doi.org/10.3390/jcs6090245 - 24 Aug 2022

Cited by 18 | Viewed by 4195

Abstract

The present investigation focuses on developing cost-effective Carbon/Glass/Kevlar fiber-reinforced polymer hybrid composite laminates for achieving its synergistic effect on flexural and impact performance. It investigates the effect of stacking sequence induced by the use of different fiber types (Kevlar = K, glass = [...] Read more.

The present investigation focuses on developing cost-effective Carbon/Glass/Kevlar fiber-reinforced polymer hybrid composite laminates for achieving its synergistic effect on flexural and impact performance. It investigates the effect of stacking sequence induced by the use of different fiber types (Kevlar = K, glass = G, and carbon = C) on the flexural and impact performance of the composites. Five hybrid composites (labelled as A = [G₂K₃G₂], B = [KG₂CG₂K], C = [CKGCGKC], D = [CGKCKGC], E = [CK₂CK₂C]) and three plain (i.e., non-hybrid) composites (F = [K]₇, G = [G]₇, H = [C]₇) have been fabricated through manual pre-preg lay-up manufacturing techniques. The flexural strength and modulus, hardness, and Izod impact strength have been evaluated for the fabricated composites and compared. The results showed that the D-type hybrid composite achieves the maximum positive hybrid effect as compared to other hybrid composites, possesses a hardness of 59 BHN, a flexural strength of 380 MPa, and modulus of 36 GPa, and impact strength of 80 KJ/m². The fracture surfaces of the hybrid composite specimen have been analysed using scanning electron microscopy, and compared against the properties achieved for enabling correlations. Furthermore, the cost-efficiency of the hybridization in terms of flexural strength/cost, modulus/cost, and impact strength/cost ratio were evaluated for potential engineering and design applications. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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10 pages, 3448 KiB

Open AccessArticle

Effect of Functionalization with Potassium Atoms on the Electronic Properties of a 3D Glass-like Nanomaterial Reinforced with Carbon Nanotubes: In Silico Study

by Alexander A. Petrunin, Michael M. Slepchenkov and Olga E. Glukhova

J. Compos. Sci. 2022, 6(7), 186; https://doi.org/10.3390/jcs6070186 - 24 Jun 2022

Cited by 2 | Viewed by 1796

Abstract

In this paper, using the self-consistent charge density-functional tight-binding (SCC DFTB) method, we perform an in silico study of the effect of functionalization by potassium atoms on the electronic properties of a new configuration of the glass-like carbon (GLC) reinforced with (4,4) and [...] Read more.

In this paper, using the self-consistent charge density-functional tight-binding (SCC DFTB) method, we perform an in silico study of the effect of functionalization by potassium atoms on the electronic properties of a new configuration of the glass-like carbon (GLC) reinforced with (4,4) and (6,5) single-walled carbon nanotubes (SWCNTs). The method of classical molecular dynamics was used to obtain energetically stable GLC configurations with different mass fractions of potassium. It is found that with an increase in the mass fraction of SWCNTs, the elasticity of GLC increases. It is shown that when the GLC structure reinforced with SWCNTs is filled with potassium, the number of available electronic states at the Fermi level increases compared to GLC without nanotubes, which significantly improves the emission and electrophysical characteristics of the carbon nanomaterial. For most structures, at a potassium/carbon mass ratio of 1:100 (0.01), an increase in the Fermi energy is observed, and, hence, a decrease in the work function. The maximum decrease in the work function by ~0.3 eV was achieved at a mass ratio of potassium/carbon of 1:4.5 (0.23) for GLC reinforced with (6,5) SWCNTs. It is revealed that, at a mass ratio of potassium/carbon of 1:28.5 (0.035), the quantum capacitance of GLC reinforced with (4,4) and (6,5) SWCNTs increases by ~9.4% (1752.63 F/g) and 24.1% (2092.04 F/g), respectively, as compared to GLC without nanotubes (1587.93 F/g). Based on the results obtained, the prospects for the application of the proposed GLC configuration in emission electronics devices are predicted. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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18 pages, 5598 KiB

Open AccessArticle

Mechanical, Thermal and Electrical Properties of Epoxy Nanocomposites with Amine-Functionalized Reduced Graphene Oxide via Plasma Treatment

by Annika C. Ackermann, Michael Fischer, Alexander Wick, Stefan Carosella, Bronwyn L. Fox and Peter Middendorf

J. Compos. Sci. 2022, 6(6), 153; https://doi.org/10.3390/jcs6060153 - 24 May 2022

Cited by 10 | Viewed by 2890

Abstract

A suitable functionalization of graphene and its derivatives can further enhance the material properties of nanocomposites. In contrast to chemical functionalization methods that have been extensively researched, functionalization by plasma treatment is relatively unexplored. In this work, we compare the mechanical, thermal and [...] Read more.

A suitable functionalization of graphene and its derivatives can further enhance the material properties of nanocomposites. In contrast to chemical functionalization methods that have been extensively researched, functionalization by plasma treatment is relatively unexplored. In this work, we compare the mechanical, thermal and electrical characteristics of an epoxy matrix incorporating loadings from 0.00 to 1.50 wt% of non-functionalized (rGO) and amine-functionalized reduced graphene oxide (frGO) for which the functionalization is realized by plasma processing. No significant difference between the rGO- and frGO-including nanocomposites was observed with respect to the stiffness, strength, specific heat capacity, coefficient of thermal expansion and electrical conductivity. Yet, the composites with 1.50 wt% frGO (rGO) exhibited a thermal conductivity that was 27% (20%) higher than the neat polymer due to the enhanced interface, which enabled a better transfer of heat. In addition, a considerable increase in the specific heat capacity and thermal conductivity was established with rising temperatures. This information will facilitate the choice of materials depending on the loading and functionalization of graphene materials for composite applications with an epoxy matrix. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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25 pages, 9375 KiB

Open AccessArticle

Study of Graphene Epoxy/Nanoplatelets Thin Films Subjected to Aging in Corrosive Environments

by Stefano Bellucci

J. Compos. Sci. 2022, 6(2), 39; https://doi.org/10.3390/jcs6020039 - 22 Jan 2022

Cited by 3 | Viewed by 2629

Abstract

The corrosion of metallic devices and degradation of plastic materials are a cause of great concern for companies and countries’ economies; it is necessary to contrast these phenomena by studying innovative methodologies and techniques. A simple solution lies in the realization of materials [...] Read more.

The corrosion of metallic devices and degradation of plastic materials are a cause of great concern for companies and countries’ economies; it is necessary to contrast these phenomena by studying innovative methodologies and techniques. A simple solution lies in the realization of materials that can resist corrosive environments and be used as coatings to prevent, or at least delay, deterioration. The purpose of this work was to study the behavior of an epoxy resin, in thin film form, exposed to corrosive chemicals. In particular, the samples were subjected to aging of 31 days in dilute sulfuric acid (H₂SO₄) and in an aqueous solution of potassium chloride (KCl). Subsequently, thin films of Epoxy/graphene nanoplatelets (GNP) composite material have been subjected to the same conditions: it was investigated how these samples respond to the corrosive environment. We found that the addition of carbonaceous nanofillers prolongs in time the ability of the material to resist the attack of chemical agents. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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11 pages, 2565 KiB

Open AccessArticle

Flexible and High Thermal Conductivity Composites Based on Graphite Nanoplates Paper Impregnated with Polydimethylsiloxane

by Daniele Battegazzore, Erica Fadda and Alberto Fina

J. Compos. Sci. 2021, 5(12), 309; https://doi.org/10.3390/jcs5120309 - 25 Nov 2021

Cited by 3 | Viewed by 2506

Abstract

This paper deals with the design, preparation, and characterization of conductive and flexible nanopapers based on graphite nanoplates (GNP) and polydimethylsiloxane (PDMS). Highly porous GNP nanopapers were first prepared by filtration from a GNP suspension in a solvent. Subsequently, PDMS impregnation was carried [...] Read more.

This paper deals with the design, preparation, and characterization of conductive and flexible nanopapers based on graphite nanoplates (GNP) and polydimethylsiloxane (PDMS). Highly porous GNP nanopapers were first prepared by filtration from a GNP suspension in a solvent. Subsequently, PDMS impregnation was carried out to obtain a composite material. By varying the concentration of the polymer solution and the deposition time, PDMS/GNP nanopapers were produced with a wide range of PDMS contents, porosities, and densities. Thermal diffusivity of the composite films (both in-plane and cross-plane) were measured and correlated with the structure of the nanopapers. Selected formulations were investigated in detail for their physical, thermal, and mechanical properties, exhibiting high flexibility and resistance to more than 50 repeated bendings, stiffness of up to 1.3 MPa, and thermal conductivity of up to 25 W/m∙K. Based on the properties obtained, the materials presented in this paper may find applications in modern lightweight and flexible electronic devices. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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13 pages, 4742 KiB

Open AccessArticle

Toughening and Healing of CFRPs by Electrospun Diels–Alder Based Polymers Modified with Carbon Nano-Fillers

by Athanasios Kotrotsos, Constantinos Rouvalis, Anna Geitona and Vassilis Kostopoulos

J. Compos. Sci. 2021, 5(9), 242; https://doi.org/10.3390/jcs5090242 - 10 Sep 2021

Cited by 7 | Viewed by 2255

Abstract

In the present investigation, thermo-reversible bonds formed between maleimide and furan groups (Diels–Alder (DA)-based bis-maleimides (BMI)) have been generated to enable high-performance unidirectional (UD) carbon fiber-reinforced plastics (CFRPs) with self-healing (SH) functionality. The incorporation of the SH agent (SHA) was performed locally, only [...] Read more.

In the present investigation, thermo-reversible bonds formed between maleimide and furan groups (Diels–Alder (DA)-based bis-maleimides (BMI)) have been generated to enable high-performance unidirectional (UD) carbon fiber-reinforced plastics (CFRPs) with self-healing (SH) functionality. The incorporation of the SH agent (SHA) was performed locally, only in areas of interest, with the solution electrospinning process (SEP) technique. More precisely, reference and modified CFRPs with (a) pure SHA, (b) SHA modified with multi-walled carbon nano-tubes (MWCNTs) and (c) SHA modified with graphene nano-platelets (GNPs) were fabricated and further tested under Mode I loading conditions. According to experimental results, it was shown that the interlaminar fracture toughness properties of modified CFRPs were considerably enhanced, with GNP-modified ones to exhibit the best toughening performance. After the first fracture and the activation of the healing process, C-scan inspections revealed, macroscopically, a healing efficiency (H.E.) of 100%; however, after repeating the tests, a low recovery of mechanical properties was achieved. Finally, optical microscopy (OM) examinations not only showed that the epoxy matrix at the interface was partly infiltrated by the DA resin, but it also revealed the presence of pulled-out fibers at the fractured surfaces, indicating extended fiber bridging between crack flanks due to the presence of the SHA. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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22 pages, 3770 KiB

Open AccessArticle

Mechanical Properties of a Biocomposite Based on Carbon Nanotube and Graphene Nanoplatelet Reinforced Polymers: Analytical and Numerical Study

by Marwane Rouway, Mourad Nachtane, Mostapha Tarfaoui, Nabil Chakhchaoui, Lhaj El Hachemi Omari, Fouzia Fraija and Omar Cherkaoui

J. Compos. Sci. 2021, 5(9), 234; https://doi.org/10.3390/jcs5090234 - 3 Sep 2021

Cited by 19 | Viewed by 3552

Abstract

Biocomposites based on thermoplastic polymers and natural fibers have recently been used in wind turbine blades, to replace non-biodegradable materials. In addition, carbon nanofillers, including carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), are being implemented to enhance the mechanical performance of composites. In [...] Read more.

Biocomposites based on thermoplastic polymers and natural fibers have recently been used in wind turbine blades, to replace non-biodegradable materials. In addition, carbon nanofillers, including carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), are being implemented to enhance the mechanical performance of composites. In this work, the Mori–Tanaka approach is used for homogenization of a polymer matrix reinforced by CNT and GNP nanofillers for the first homogenization, and then, for the second homogenization, the effective matrix was used with alfa and E-glass isotropic fibers. The objective is to study the influence of the volume fraction

V_{f}

and aspect ratio AR of nanofillers on the elastic properties of the composite. The inclusions are considered in a unidirectional and random orientation by using a computational method by Digimat-MF/FE and analytical approaches by Chamis, Hashin–Rosen and Halpin–Tsai. The results show that CNT- and GNP-reinforced nanocomposites have better performance than those without reinforcement. Additionally, by increasing the volume fraction and aspect ratio of nanofillers, Young’s modulus

E

increases and Poisson’s ratio

ν

decreases. In addition, the composites have enhanced mechanical characteristics in the longitudinal orientation for CNT- reinforced polymer and in the transversal orientation for GNP-reinforced polymer. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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11 pages, 2569 KiB

Open AccessArticle

Thermal/Electrical Properties and Texture of Carbon Black PC Polymer Composites near the Electrical Percolation Threshold

by Valentina Brunella, Beatrice Gaia Rossatto, Chiara Mastropasqua, Federico Cesano and Domenica Scarano

J. Compos. Sci. 2021, 5(8), 212; https://doi.org/10.3390/jcs5080212 - 11 Aug 2021

Cited by 11 | Viewed by 3627

Abstract

Polycarbonate (PC), a thermoplastic polymer with excellent properties, is used in many advanced technological applications. When PC is blended with other polymers or additives, new properties, such as electrical properties, can be available. In this study, carbon black (CB) was melt-compounded with PC [...] Read more.

Polycarbonate (PC), a thermoplastic polymer with excellent properties, is used in many advanced technological applications. When PC is blended with other polymers or additives, new properties, such as electrical properties, can be available. In this study, carbon black (CB) was melt-compounded with PC to produce polymer compounds with compositions (10–16 wt.% of CB), which are close to or above the electrical percolation threshold (13.5–14 wt.% of CB). Effects due to nanofiller dispersion/aggregation in the polymer matrix, together with phase composition, glass transition temperature, morphology and textural properties, were studied by using thermal analysis methods (thermogravimetry and differential scanning calorimetry) and scanning electron microscopy. The DC electrical properties of these materials were also investigated by means of electrical conductivity measurements and correlated with the “structure” of the CB, to better explain the behaviour of the composites close to the percolation threshold. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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13 pages, 7598 KiB

Open AccessArticle

Effect of Filler Morphology on the Electrical and Thermal Conductivity of PP/Carbon-Based Nanocomposites

by Marta Zaccone, Alberto Frache, Luigi Torre, Ilaria Armentano and Marco Monti

J. Compos. Sci. 2021, 5(8), 196; https://doi.org/10.3390/jcs5080196 - 23 Jul 2021

Cited by 6 | Viewed by 2468

Abstract

In this paper, we studied the effect of different carbon-based nanostructures on the electrical and mechanical properties of polypropylene (PP) nanocomposites. Multi-walled carbon nanotubes (MWCNT), expanded graphite (EG), and two different carbon black nanoparticles (CB) have been dispersed at several weight contents in [...] Read more.

In this paper, we studied the effect of different carbon-based nanostructures on the electrical and mechanical properties of polypropylene (PP) nanocomposites. Multi-walled carbon nanotubes (MWCNT), expanded graphite (EG), and two different carbon black nanoparticles (CB) have been dispersed at several weight contents in the polymer matrix through a melt extrusion process. The produced nanocomposites have been used to obtain samples for the characterization by injection molding. The dispersion of the nanoparticles in the matrix has been evaluated by scanning electron microscopy (SEM) analysis. The electrical characterization has been performed both in DC and in AC configuration. The mechanical properties have been evaluated with both tensile test and impact strength (Izod). The thermal conductivity has been also evaluated. As a result, MWCNTs are the nanoadditive with the lowest electrical percolation threshold. This allows MWCNT nanocomposite to drastically change the electrical behavior without a significant embrittlement observed with the other nanoadditives. However, CB with the lowest surface area allows the highest conductivity, even though at a high particle content. EG has a limited effect on electrical properties, but it is the only one with a significant effect on thermal conductivity. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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12 pages, 3707 KiB

Open AccessArticle

Innovative Carbon-Doped Composite Pavements with Sensing Capability and Low Environmental Impact for Multifunctional Infrastructures

by Hasan Borke Birgin, Antonella D’Alessandro, Simon Laflamme and Filippo Ubertini

J. Compos. Sci. 2021, 5(7), 192; https://doi.org/10.3390/jcs5070192 - 20 Jul 2021

Cited by 11 | Viewed by 3139

Abstract

Recently, smart composites that serve as multi-functional materials have gained popularity for structural and infrastructural applications yielding condition assessment capabilities. An emerging application is the monitoring and prediction of the fatigue of road infrastructure, where these systems may benefit from the ability to [...] Read more.

Recently, smart composites that serve as multi-functional materials have gained popularity for structural and infrastructural applications yielding condition assessment capabilities. An emerging application is the monitoring and prediction of the fatigue of road infrastructure, where these systems may benefit from the ability to detect and estimate vehicle loads via weigh-in-motion (WIM) sensing without interrupting the traffic flow. However, off-the-shelf applications of WIM can be improved in terms of cost and durability, both on the hardware and software sides. This study proposes a novel multi-functional pavement material that can be utilized as a pavement embedded weigh-in-motion system. The material consists of a composite fabricated using an eco-friendly synthetic binder material called EVIzero, doped with carbon microfiber inclusions. The composite material is piezoresistive and, therefore, has strain-sensing capabilities. Compared to other existing strain-sensing structural materials, it is not affected by polarization and exhibits a more rapid response time. The study evaluates the monitoring capabilities of the novel composite according to the needs of a WIM system. A tailored data acquisition setup with distributed line electrodes is developed for the detection of moving loads. The aim of the paper is to demonstrate the sensing capabilities of the newly proposed composite pavement material and the suitability of the proposed monitoring system for traffic detection and WIM. Results demonstrate that the material is promising in terms of sensing and ready to be implemented in the field for further validation in the real world. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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32 pages, 1514 KiB

Open AccessArticle

An Assessment of Thick Nanocomposite Plates’ Behavior under the Influence of Carbon Nanotubes Agglomeration

by Débora S. Craveiro and Maria A. R. Loja

J. Compos. Sci. 2021, 5(2), 41; https://doi.org/10.3390/jcs5020041 - 1 Feb 2021

Cited by 5 | Viewed by 2772

Abstract

The influence assessment of carbon nanotubes (CNTs) agglomeration on CNT-reinforced composite (CNTRC) thick plates’ behavior is the main aim of the present work. CNTs are known to agglomerate into clusters even for relatively low volume fractions, which imposes the need to characterize the [...] Read more.

The influence assessment of carbon nanotubes (CNTs) agglomeration on CNT-reinforced composite (CNTRC) thick plates’ behavior is the main aim of the present work. CNTs are known to agglomerate into clusters even for relatively low volume fractions, which imposes the need to characterize the effects this may introduce in structures behavior, also knowing that recent works have concluded that neglecting agglomeration phenomenon may lead to an overestimation of the mechanical properties of nanocomposites. Hence, it matters to understand how the arising of these clusters may affect the static and free vibrational behaviors of low side-to-thickness nanocomposite plates. To this purpose, the nanocomposite plate properties’ estimation is performed by using the two-parameter model of agglomeration based on the Eshelby–Mori–Tanaka approach, while for behavioral analyses one considers a Higher-order Shear Deformation Theory (HSDT) based on the displacement field of Kant, implemented through the finite element method. The analyses developed consider a set of parametric studies involving the assessment of the influence of side-to-side ratios, side-to-thickness ratios, boundary conditions, and CNTs’ distributions along the thickness. The results obtained allow concluding that the transverse deflections and fundamental frequencies of these structures are significantly influenced by the CNTs’ agglomeration. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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18 pages, 6040 KiB

Open AccessArticle

Mechanical, Thermal, and Morphological Properties of Graphene Nanoplatelet-Reinforced Polypropylene Nanocomposites: Effects of Nanofiller Thickness

by Harekrushna Sutar, Birupakshya Mishra, Pragyan Senapati, Rabiranjan Murmu and Dibyani Sahu

J. Compos. Sci. 2021, 5(1), 24; https://doi.org/10.3390/jcs5010024 - 14 Jan 2021

Cited by 46 | Viewed by 5157

Abstract

In this work, polypropylene (PP) and graphene nanoplatelet (GNPs) composites are routed through twin screw mixing and injection moulding. Two types of GNPs with a fixed size of 25 µm with surface areas ranging from 50–80 m²/g (H25, average thickness 15 [...] Read more.

In this work, polypropylene (PP) and graphene nanoplatelet (GNPs) composites are routed through twin screw mixing and injection moulding. Two types of GNPs with a fixed size of 25 µm with surface areas ranging from 50–80 m²/g (H25, average thickness 15 nm) and 120–150 m²/g (M25, average thickness 6–8 nm) were blended with PP at loading rates of 1, 2, 3, 4, and 5 weight%. Mechanical properties such as tensile, flexural, and impact strengths and Young’s modulus (Ε) are determined. The X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), field emission scanning electron microscopy (FESEM), and polarised light microscopy (PLM) techniques are used to understand the crystallisation, thermal, dynamic mechanical, and structural behaviour of the prepared composites. The improvement of mechanical strength is observed with GNP loading for both grades. Decreasing the GNP thickness decreases the impact strength and on the other hand improves the tensile and flexural strengths and Young’s modulus. Maximum tensile (≈33 MPa) and flexural (≈58.81 MPa) strength is found for the composite carrying 5 wt% M25. However, maximum impact strength (0.197 J) is found for PP-5 wt% H25. XRD analysis confirms GNPs have an induction effect on PP’s β phase crystal structure. The PP-GNP composite exhibits better thermal stability based on determining the T_D (degradation temperature), T₁₀ (temperature at 10% weight loss), T₅₀ (temperature at 50% weight loss), and T_R (temperature at residual weight). Enhancement in melt (Tm) and crystallisation temperatures (Tc) is are observed due to a heterogeneous nucleation effect. The FESEM analysis concludes that the GNP thickness has a significant effect on the degree of dispersion and agglomeration. The smaller the thickness, the better is the dispersion and the lower is the agglomeration. Overall, the use of thinner GNPs is more advantageous in improving the polymer properties. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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14 pages, 5624 KiB

Open AccessArticle

Mechanical and Electrical Properties of Injection-Molded MWCNT-Reinforced Polyamide 66 Hybrid Composites

by Ross Zameroski, Chadwick J. Kypta, Brian A. Young, Seyed Hamid Reza Sanei and Adam S. Hollinger

J. Compos. Sci. 2020, 4(4), 177; https://doi.org/10.3390/jcs4040177 - 25 Nov 2020

Cited by 5 | Viewed by 2855

Abstract

The addition of fillers or reinforcements has a direct influence on the mechanical and electrical properties of polymers. Such properties are a function of the morphology and the distribution of fillers in the polymer base. Each feature may have contrasting effects on mechanical [...] Read more.

The addition of fillers or reinforcements has a direct influence on the mechanical and electrical properties of polymers. Such properties are a function of the morphology and the distribution of fillers in the polymer base. Each feature may have contrasting effects on mechanical and electrical properties. In this study, chopped carbon fiber of different lengths and multiwalled carbon nanotubes (MWCNTs) were added to nylon 6,6. Specimens were manufactured by injection molding of a polyamide/MWCNT masterbatch with the addition of loose chopped carbon fiber. Tensile testing of dogbone specimens was conducted to obtain Young’s modulus, ultimate tensile strength, and elongation. Electrical conductivity testing was conducted on the same specimens prior to mechanical testing. To evaluate the morphology of fillers, scanning electron micrographs were evaluated. Micrographs show the presence of a skin layer close to the surface of the specimens. For this reason, core and surface conductivities were compared. The results show that while promising electrical properties can be achieved by the addition of fillers, the improvement in mechanical properties is minimal. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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15 pages, 2538 KiB

Open AccessArticle

Piezoresistive and mechanical Behavior of CNT based polyurethane foam

by Enea De Meo, Simone Agnelli, Antonino Veca, Valentia Brunella and Marco Zanetti

J. Compos. Sci. 2020, 4(3), 131; https://doi.org/10.3390/jcs4030131 - 6 Sep 2020

Cited by 7 | Viewed by 3994

Abstract

Carbon nanotubes (CNT) embedded into a polymeric foam demonstrate an enhancement in electrical and mechanical properties of the final nanocomposite. The enhanced material with new characteristics, e.g., piezoresistivity, can be substituted with the traditional metallic material to design sensors, switches, and knobs directly [...] Read more.

Carbon nanotubes (CNT) embedded into a polymeric foam demonstrate an enhancement in electrical and mechanical properties of the final nanocomposite. The enhanced material with new characteristics, e.g., piezoresistivity, can be substituted with the traditional metallic material to design sensors, switches, and knobs directly into a single multifunctional component. Research activities in this field are moving towards a mono-material fully integrated smarts components. In order to achieve this goal, a simple method is developed to produce piezoresistive polyurethane/CNT foams. The novelty consists in applying the dispersion of CNT considering industrial production constrains, in order to facilitate its introduction into a common industrial practice. Three kinds of PU-CNT foam have been prepared and tested: PU-CNT 1.5%, PU-CNT-COOH 1.0%, and PU-CNT-COOH 1.5%. Polyurethane with CNT-COOH showed an insulating-conductive transition phenomenon when the foam reaches the 80% of its compression strain with a Gauge factor (Gf) of about 30. Instead, PU-CNT showed conductivity only at 1.5% of filler concentration and a steady piezoresistive behavior with a Gf of 80. However, this samples did not show the insulating-conductive transition. Having improved the electromechanical properties of final nanocomposite polyurethane foam demonstrates that the proposed method can be applied differently for design sensors and switches. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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18 pages, 10509 KiB

Open AccessArticle

Effect of Carbon Nanotubes (CNT) Functionalization and Maleic Anhydride-Grafted Poly(trimethylene terephthalate) (PTT-g-MA) on the Preparation of Antistatic Packages of PTT/CNT Nanocomposites

by Natália Ferreira Braga, Henrique Morales Zaggo, Larissa Stieven Montagna and Fabio Roberto Passador

J. Compos. Sci. 2020, 4(2), 44; https://doi.org/10.3390/jcs4020044 - 24 Apr 2020

Cited by 21 | Viewed by 3630

Abstract

Electronic devices require the use of antistatic packing to prevent electrostatic discharge during their storage or transport. Poly (trimethylene terephthalate) (PTT) is a polyester with excellent properties and can be a good candidate for this application. To make this insulating polymer an extrinsic [...] Read more.

Electronic devices require the use of antistatic packing to prevent electrostatic discharge during their storage or transport. Poly (trimethylene terephthalate) (PTT) is a polyester with excellent properties and can be a good candidate for this application. To make this insulating polymer an extrinsic conductor, carbon nanotubes (CNT) can be added to reduce the electrical resistivity of the nanocomposites. In order to facilitate the CNT distribution on polymeric matrix, it was proposed a chemical functionalization using nitric acid for the creation of functional groups on its surface. Moreover, the PTT matrix was modified with a compatibilizer agent based on maleic anhydride grafted PTT (PTT-g-MA), to improve interfacial adhesion between the nanofiller and matrix. In this work, nanocomposites based on PTT/PTT-g-MA/CNT were prepared by extrusion process, with 0.5 wt% and 1.0 wt% of CNT and functionalized CNT. CNT was characterized by stability dispersion in water, Raman spectroscopy, FTIR and XPS analysis, which prove the success of functionalization. The nanocomposites were evaluated by thermal analysis, tensile tests, electrical conductivity, and morphological analysis. The CNT functionalization and the addition of PTT-g-MA increased the dispersion and distribution of CNT in the PTT matrix. The electrical properties show that this material can be used as an antistatic packaging. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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Review

Jump to: Research

23 pages, 3532 KiB

Open AccessEditor’s ChoiceReview

3D-Printed Carbon Fiber Reinforced Polymer Composites: A Systematic Review

by Seyed Hamid Reza Sanei and Diana Popescu

J. Compos. Sci. 2020, 4(3), 98; https://doi.org/10.3390/jcs4030098 - 24 Jul 2020

Cited by 137 | Viewed by 14269

Abstract

Fiber reinforced composites offer exceptional directional mechanical properties, and combining their advantages with the capability of 3D printing has resulted in many innovative research fronts. This review aims to summarize the methods and findings of research conducted on 3D-printed carbon fiber reinforced composites. [...] Read more.

Fiber reinforced composites offer exceptional directional mechanical properties, and combining their advantages with the capability of 3D printing has resulted in many innovative research fronts. This review aims to summarize the methods and findings of research conducted on 3D-printed carbon fiber reinforced composites. The review is focused on commercially available printers and filaments, as their results are reproducible and the findings can be applied to functional parts. As the process parameters can be readily changed in preparation of a 3D-printed part, it has been the focus of many studies. In addition to typical composite driving factors such as fiber orientation, fiber volume fraction and stacking sequence, printing parameters such as infill density, infill pattern, nozzle speed, layer thickness, built orientation, nozzle and bed temperatures have shown to influence mechanical properties. Due to the unique advantages of 3D printing, in addition to conventional unidirectional fiber orientation, concentric fiber rings have been used to optimize the mechanical performance of a part. This review surveys the literature in 3D printing of chopped and continuous carbon fiber composites to provide a reference for the state-of-the-art efforts, existing limitations and new research frontiers. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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