Polymers

Research

15 pages, 3374 KiB

Open AccessArticle

Dynamic Stability Analysis in Hybrid Nanocomposite Polymer Beams Reinforced by Carbon Fibers and Carbon Nanotubes

by Behrooz Keshtegar, Reza Kolahchi, Arameh Eyvazian and Nguyen-Thoi Trung

Polymers 2021, 13(1), 106; https://doi.org/10.3390/polym13010106 - 29 Dec 2020

Cited by 10 | Viewed by 2074

The objective of this innovative research is assessment of dynamic stability for a hybrid nanocomposite polymer beam. The considered beam formed by multiphase nanocomposite, including polymer–carbon nanotubes (CNTs)–carbon fibers (CFs). Hence, as to compute the effective material characteristics related to multiphase nanocomposite layers, [...] Read more.

The objective of this innovative research is assessment of dynamic stability for a hybrid nanocomposite polymer beam. The considered beam formed by multiphase nanocomposite, including polymer–carbon nanotubes (CNTs)–carbon fibers (CFs). Hence, as to compute the effective material characteristics related to multiphase nanocomposite layers, the Halpin–Tsai model, as well as micromechanics equations are employed. To model the structure realistically, exponential shear deformation beam theory (ESDBT) is applied and using energy methods, governing equations are achieved. Moreover, differential quadrature method (DQM) as well as Bolotin procedures are used for solving the obtained governing equations and the dynamic instability region (DIR) relative to the beam is determined. To extend this novel research, various parameters pinpointing the influences of CNT volume fraction, CFs volume percent, boundary edges as well as the structure’s geometric variables on the dynamic behavior of the beam are presented. The results were validated with the theoretical and experimental results of other published papers. The outcomes reveal that increment of volume fraction of CNT is able to shift DIR to more amounts of frequency. Further, rise of carbon fibers volume percent leads to increase the excitation frequency of this structure. Full article

(This article belongs to the Special Issue Carbonaceous Fillers-Reinforced Polymer Matrix Composite for Multi-Functional Applications)

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21 pages, 6028 KiB

Open AccessArticle

Investigation on Mode I Fracture Toughness of Woven Carbon Fiber-Reinforced Polymer Composites Incorporating Nanomaterials

by Gia Toai Truong, Hai Van Tran and Kyoung-Kyu Choi

Polymers 2020, 12(11), 2512; https://doi.org/10.3390/polym12112512 - 28 Oct 2020

Cited by 6 | Viewed by 2535

Abstract

This study experimentally investigated the effects of nanomaterials and interface fiber angle on the mode I fracture toughness of woven carbon fiber-reinforced polymer (CFRP) composites. Three different types of nanomaterials were used: COOH-functionalized short multi-walled carbon nanotubes (S-MWCNT-COOH), multi-walled carbon nanotubes (MWCNTs), and [...] Read more.

This study experimentally investigated the effects of nanomaterials and interface fiber angle on the mode I fracture toughness of woven carbon fiber-reinforced polymer (CFRP) composites. Three different types of nanomaterials were used: COOH-functionalized short multi-walled carbon nanotubes (S-MWCNT-COOH), multi-walled carbon nanotubes (MWCNTs), and graphene nanoplatelets (GnPs). Double cantilever beam specimens were composed of 12 woven carbon fiber fabrics with/without 1 wt% nanomaterials, and were manufactured using the hand lay-up method. Furthermore, two different stacking sequence series were used; the first series comprised only on-axis carbon-fiber fabrics (0° or 90°), and the second series comprised both on- and off-axis carbon-fiber fabrics (0° or 90° and ±45°). The test results showed that adding S-MWCNT-COOH, MWCNTs, and GnPs significantly increased the mode I fracture toughness of the CFRP composites for both the stacking sequence series. Moreover, the specimens that used only on-axis carbon fiber fabrics exhibited higher fracture toughness values than those of the specimens that used on- and off-axis carbon fiber fabrics together. In addition, an empirical model was established to predict the fracture toughness of the CFRP composites with nanomaterials by using on- and off-axis carbon fiber fabrics together, and the prediction results showed a good agreement with the experimental results. Full article

(This article belongs to the Special Issue Carbonaceous Fillers-Reinforced Polymer Matrix Composite for Multi-Functional Applications)

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17 pages, 9956 KiB

Open AccessArticle

Fabrication and Characterization of Carbon-Fiber-Reinforced Polymer–FeSi Composites with Enhanced Magnetic Properties

by Alexandre Tugirumubano, Sun Ho Go, Hee Jae Shin, Lee Ku Kwac and Hong Gun Kim

Polymers 2020, 12(10), 2325; https://doi.org/10.3390/polym12102325 - 11 Oct 2020

Cited by 8 | Viewed by 3122

Abstract

In this work, we aimed to manufacture and characterize carbon-fiber–polymer–metal-particles magnetic composites with a sandwichlike structure. The composites were manufactured by stacking the plain woven carbon fiber prepregs (or carbon-fiber-reinforced polymers (CFRP)) and layers of the FeSi particles. The layer of FeSi particles [...] Read more.

In this work, we aimed to manufacture and characterize carbon-fiber–polymer–metal-particles magnetic composites with a sandwichlike structure. The composites were manufactured by stacking the plain woven carbon fiber prepregs (or carbon-fiber-reinforced polymers (CFRP)) and layers of the FeSi particles. The layer of FeSi particles were formed by evenly distributing the FeSi powder on the surface of carbon fiber prepreg sheet. The composites were found to have better magnetic properties when the magnetic field were applied in in-plane (0°) rather than in through-thickness (90°), and the highest saturation magnetization of 149.71 A.m²/kg was achieved. The best inductance and permeability of 12.2 μH and 13.08 were achieved. The composites obviously exhibited mechanical strength that was good but lower than that of CFRP composite. The lowest tensile strength and lowest flexural strength were 306.98 MPa and 855.53 MPa, which correspond to 39.58% and 59.83% of the tensile strength and flexural strength of CFRP (four layers), respectively. Full article

(This article belongs to the Special Issue Carbonaceous Fillers-Reinforced Polymer Matrix Composite for Multi-Functional Applications)

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15 pages, 4866 KiB

Open AccessArticle

Enhanced Surface Energetics of CNT-Grafted Carbon Fibers for Superior Electrical and Mechanical Properties in CFRPs

by Arash Badakhsh, Kay-Hyeok An and Byung-Joo Kim

Polymers 2020, 12(6), 1432; https://doi.org/10.3390/polym12061432 - 26 Jun 2020

Cited by 22 | Viewed by 4114

Abstract

Surface enhancement of components is vital for achieving superior properties in a composite system. In this study, carbon nanotubes (CNTs) were grown on carbon fiber (CF) substrates to improve the surface area and, in turn, increase the adhesion between epoxy-resin and CFs. Nickel [...] Read more.

Surface enhancement of components is vital for achieving superior properties in a composite system. In this study, carbon nanotubes (CNTs) were grown on carbon fiber (CF) substrates to improve the surface area and, in turn, increase the adhesion between epoxy-resin and CFs. Nickel (Ni) was used as the catalyst in CNT growth, and was coated on CF sheets via the electroplating method. Surface energetics of CNT-grown CFs and their work of adhesion with epoxy resin were measured. SEM and TEM were used to analyze the morphology of the samples. After the optimization of surface energetics by catalyst weight ratio (15 wt.% Ni), CF-reinforced plastic (CFRP) samples were prepared using the hand lay-up method. To validate the effect of chemical vapor deposition (CVD)-grown CNTs on CFRP properties, samples were also prepared where CNT powder was added to epoxy prior to reinforcement with Ni-coated CFs. CFRP specimens were tested to determine their electrical resistivity, flexural strength, and ductility index. The electrical resistivity of CNT-grown CFRP was found to be about 9 and 2.3 times lower than those of as-received CFRP and CNT-added Ni-CFRP, respectively. Flexural strength of CNT-grown Ni-CFRP was enhanced by 52.9% of that of as-received CFRP. Interestingly, the ductility index in CNT-grown Ni-CFRP was 40% lower than that of CNT-added Ni-CFRP. This was attributed to the tip-growth formation of CNTs and the breakage of Ni coating. Full article

(This article belongs to the Special Issue Carbonaceous Fillers-Reinforced Polymer Matrix Composite for Multi-Functional Applications)

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14 pages, 4483 KiB

Open AccessArticle

Synergistic Effects of Hybrid Carbonaceous Fillers of Carbon Fibers and Reduced Graphene Oxides on Enhanced Heat-Dissipation Capability of Polymer Composites

by Yun Seon Lee, Jaesang Yu, Sang Eun Shim and Cheol-Min Yang

Polymers 2020, 12(4), 909; https://doi.org/10.3390/polym12040909 - 14 Apr 2020

Cited by 6 | Viewed by 2931

Abstract

In this study, we investigated the synergistic effects of thermally conductive hybrid carbonaceous fillers of mesophase pitch-based carbon fibers (MPCFs) and reduced graphene oxides (rGOs) on the thermal conductivity of polymer matrix composites. Micro-sized MPCFs with different lengths (50 μm, 200 μm, and [...] Read more.

In this study, we investigated the synergistic effects of thermally conductive hybrid carbonaceous fillers of mesophase pitch-based carbon fibers (MPCFs) and reduced graphene oxides (rGOs) on the thermal conductivity of polymer matrix composites. Micro-sized MPCFs with different lengths (50 μm, 200 μm, and 6 mm) and nano-sized rGOs were used as the thermally conductive fillers used for the preparation of the heat-dissipation polymer composites. For all MPCF fillers with a different length, the thermal conductivity values of the MPCF/epoxy composites were proportional to the MPCF length and loading amount (0–50 wt%) of MPCFs. For an MPCF:rGO weight ratio of 49:1 (total loading amount of 50 wt%), the thermal conductivity values of MPCF-rGO/epoxy composites loaded with MPCFs of 50 μm, 200 μm, and 6 mm increased from 5.56 to 7.98 W/mK (approximately 44% increase), from 7.36 to 9.80 W/mK (approximately 33% increase), and from 11.53 to 12.58 W/mK (approximately 9% increase) compared to the MPCF/epoxy composites, respectively, indicating the synergistic effect on the thermal conductivity enhancement. The rGOs in the MPCF-rGO/epoxy composites acted as thermal bridges between neighboring MPCFs, resulting in the formation of effective heat transfer pathways. In contrast, the MPCF-rGO/epoxy composites with MPCF:rGO weight ratios of 48:2 and 47:3 decreased the synergistic effect more significantly compared to rGO content of 1 wt%, which is associated with the agglomeration of rGO nanoparticles. The synergistic effect was inversely proportional to the MPCF length. A theoretical approach, the modified Mori-Tanaka model, was used to estimate the thermal conductivity values of the MPCF-rGO/epoxy composites, which were in agreement with the experimentally measured values for MPCF-rGO/epoxy composites loaded with short MPCF lengths of 50 and 200 μm. Full article

(This article belongs to the Special Issue Carbonaceous Fillers-Reinforced Polymer Matrix Composite for Multi-Functional Applications)

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17 pages, 2607 KiB

Open AccessEditor’s ChoiceArticle

Impact of Current and Temperature on Extremely Low Loading Epoxy-CNT Conductive Composites

by Brian Earp, Jonathan Phillips, Dragoslav Grbovic, Stephen Vidmar, Matthew Porter and Claudia C. Luhrs

Polymers 2020, 12(4), 867; https://doi.org/10.3390/polym12040867 - 10 Apr 2020

Cited by 8 | Viewed by 2437

Abstract

Carbon nanotube (CNT) conductive composites have attracted significant attention for their potential use in applications such as electrostatic dissipation and/or electromagnetic interference shielding. The focus of this work is to evaluate resistivity trends of extremely low loading (<0.1 wt%) epoxy-CNT composites that lack [...] Read more.

Carbon nanotube (CNT) conductive composites have attracted significant attention for their potential use in applications such as electrostatic dissipation and/or electromagnetic interference shielding. The focus of this work is to evaluate resistivity trends of extremely low loading (<0.1 wt%) epoxy-CNT composites that lack a connected CNT network, but still present electrical conductivity values appropriate for those uses. The impact of current, temperature, and cycle life on electrical properties are here identified and tied to possible performance limits. At extremely low loadings, the CNT content is not sufficient to form a completely interconnected grid, thus, electrons must travel through insulating media. While still in the semi-conductor range, resistivity values are observed to decrease with increasing direct current and demonstrate a non-ohmic behavior. CNT epoxy composites were subjected to elevated currents and/or temperatures over diverse periods of time to examine impacts on resistivity. Microstructural analyses of composite samples were conducted to observe signs of damage for specimens taken to extreme temperatures/currents. An understanding of the electrical conductivity characteristics of extremely low loading epoxy-CNT composites and their failure mechanisms will aid in understanding risks associated with their use in challenging environments that may include high temperatures, high currents, and/or high frequencies. Full article

(This article belongs to the Special Issue Carbonaceous Fillers-Reinforced Polymer Matrix Composite for Multi-Functional Applications)

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12 pages, 2483 KiB

Open AccessArticle

Calculation of the Electrical Conductivity of Polymer Nanocomposites Assuming the Interphase Layer Surrounding Carbon Nanotubes

by Yasser Zare and Kyong Yop Rhee

Polymers 2020, 12(2), 404; https://doi.org/10.3390/polym12020404 - 11 Feb 2020

Cited by 26 | Viewed by 3153

Abstract

The interphase layer surrounding nanoparticles can reflect the tunneling effect as the main mechanism of charge transferring in polymer/carbon nanotube (CNT) nanocomposites (PCNT). In this paper, the percolation threshold, effective volume fraction of CNT, and the portion of percolated filler after percolation are [...] Read more.

The interphase layer surrounding nanoparticles can reflect the tunneling effect as the main mechanism of charge transferring in polymer/carbon nanotube (CNT) nanocomposites (PCNT). In this paper, the percolation threshold, effective volume fraction of CNT, and the portion of percolated filler after percolation are expressed by interphase and CNT waviness. Moreover, the developed terms are used to suggest the influences of CNT dimensions, interphase thickness, and waviness on the electrical conductivity of PCNT by conventional and developed models. Thin and long CNT, thick interphase, and low waviness obtain a high fraction of percolated CNT. However, the highest level of effective filler fraction is only calculated by the thinnest CNT and the thickest interphase. Furthermore, both models show that the thinnest and the longest CNT as well as the thickest interphase and the least CNT waviness cause the highest conductivity in PCNT, because they positively contribute to the formation and properties of the conductive network. Full article

(This article belongs to the Special Issue Carbonaceous Fillers-Reinforced Polymer Matrix Composite for Multi-Functional Applications)

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13 pages, 3841 KiB

Open AccessArticle

Study on the Effects of the Interphase Region on the Network Properties in Polymer Carbon Nanotube Nanocomposites

by Yasser Zare and Kyong Yop Rhee

Polymers 2020, 12(1), 182; https://doi.org/10.3390/polym12010182 - 10 Jan 2020

Cited by 22 | Viewed by 2818

Abstract

The interphase region around nanoparticles changes the percolation threshold of long and thin nanoparticles, such as carbon nanotubes (CNT) in polymer nanocomposites. In this paper, the effects of the interphase region on the percolation threshold of nanoparticles and the network fraction are studied. [...] Read more.

The interphase region around nanoparticles changes the percolation threshold of long and thin nanoparticles, such as carbon nanotubes (CNT) in polymer nanocomposites. In this paper, the effects of the interphase region on the percolation threshold of nanoparticles and the network fraction are studied. New percolation threshold (φ_P) is defined by the role of the interphase in the excluded volume of nanoparticles (V_ex). Moreover, the influences of filler and interphase size on the percolation volume fraction, the fraction of nanoparticles in the network as well as the volume fraction and relative density of the filler network are investigated. The least ranges of “φ_P” are obtained by thin and long CNT. Similarly, a thick interphase increases the “V_ex” parameter, which causes a positive role in the percolation occurrence. Also, thin CNT and a thick interphase cause the high fraction of the filler network in the nanocomposites. Full article

(This article belongs to the Special Issue Carbonaceous Fillers-Reinforced Polymer Matrix Composite for Multi-Functional Applications)

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15 pages, 7358 KiB

Open AccessArticle

Effective Heat Transfer Pathways of Thermally Conductive Networks Formed by One-Dimensional Carbon Materials with Different Sizes

by Yun Seon Lee, Seung-Yong Lee, Keun Soo Kim, Suguru Noda, Sang Eun Shim and Cheol-Min Yang

Polymers 2019, 11(10), 1661; https://doi.org/10.3390/polym11101661 - 11 Oct 2019

Cited by 12 | Viewed by 2779

Abstract

We investigated the heat transfer behavior of thermally conductive networks with one-dimensional carbon materials to design effective heat transfer pathways for hybrid filler systems of polymer matrix composites. Nano-sized few-walled carbon nanotubes (FWCNTs) and micro-sized mesophase pitch-based carbon fibers (MPCFs) were used as [...] Read more.

We investigated the heat transfer behavior of thermally conductive networks with one-dimensional carbon materials to design effective heat transfer pathways for hybrid filler systems of polymer matrix composites. Nano-sized few-walled carbon nanotubes (FWCNTs) and micro-sized mesophase pitch-based carbon fibers (MPCFs) were used as the thermally conductive materials. The bulk density and thermal conductivity of the FWCNT films increased proportionally with the ultrasonication time due to the enhanced dispersibility of the FWCNTs in an ethanol solvent. The ultrasonication-induced densification of the FWCNT films led to the effective formation of filler-to-filler connections, resulting in improved thermal conductivity. The thermal conductivity of the FWCNT-MPCF hybrid films was proportional to the MPCF content (maximum thermal conductivity at an MPCF content of 60 wt %), indicating the synergistic effect on the thermal conductivity enhancement. Moreover, the MPCF-to-MPCF heat transfer pathways in the FWCNT-MPCF hybrid films were the most effective in achieving high thermal conductivity due to the smaller interfacial area and shorter heat transfer pathway of the MPCFs. The FWCNTs could act as thermal bridges between neighboring MPCFs for effective heat transfer. Furthermore, the incorporation of Ag nanoparticles of approximately 300 nm into the FWCNT-MPCF hybrid film dramatically enhanced the thermal conductivity, which was closely related to a decreased thermal interfacial resistance at the intersection points between the materials. Epoxy-based composites loaded with the FWCNTs, MPCFs, FWCNT-MPCF hybrids, and FWCNT-MPCF-Ag hybrid fillers were also fabricated. A similar trend in thermal conductivity was observed in the polymer matrix composite with carbon-based hybrid films. Full article

(This article belongs to the Special Issue Carbonaceous Fillers-Reinforced Polymer Matrix Composite for Multi-Functional Applications)

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