Special Issue "Polymer-CNT Nanocomposites"

A special issue of Polymers (ISSN 2073-4360).

Deadline for manuscript submissions: closed (31 December 2018).

Special Issue Editor

Prof. Dr. Bodo Fiedler
E-Mail Website
Guest Editor
Institute of Polymer and Composites, Hamburg University of Technology (TUHH), Denickestrasse 15, D-21073 Hamburg, Germany
Interests: GFRP; CFRP; fibre metal laminate; fatigue; durability; sensor; SHM; CNT
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Special Issue Information

Dear Colleagues,

Nanotechnology has emerged as one of the most promising tools for creating high-performance and multifunctional materials for various industrial applications. This Special Issue focuses on polymer nanocomposites (PNC) built from carbon nanotubes (CNT) embedded in thermosets or thermoplastic matrices.

Most probably, Radushkevich and Lukyanovich discovered carbon nanotubes in 1952 [1]. The report of Iijima in 1991 [2] boosted the science on CNTs because of the outstanding properties of this one-dimensional carbon nanoparticles. The mechanical and physical properties of polymers are enhanced by introducing single-wall CNTs (SWCNTs) and multi-wall CNTs (MWCNTs). The research on PNCs demonstrates that synthesis and processing techniques must be developed in parallel with scientific knowledge. CNTs have a high aspect ratio and modulus. They are mechanically stable, holding an extremely high stiffness, and are electrically and thermally conductive. The high specific surface area of nanosized CNTs leads to exceptional interactions with polymers in the solid and liquid states. Therefore, new dispersion techniques had to be developed. New synthesis methods for CNTs aimed to improve the quality and quantity of CNTs.

Nowadays, CNTs are available at industrial scale and quality. There are manifold industrial applications of PNCs, which, as outlined here, depend highly on the quality of available CNTs and manufacturing techniques for composites. However, beside the problem of standardisation, more efforts are required to close the gap along the industrial value chain between materials producers and product manufacturers.

Simultaneously, the elucidation of the fundamental mechanisms of electrical conduction and mechanical reinforcement with regard to strength, ductility, modulus, and fracture toughness of PNCs, in combination with industrial manufacturing methods to scale up the production, motivates further research and development:

  • Improved electrical conductivities at very low weight fractions, e.g., antistatic transparent coatings
  • Sensor materials, e.g.. for strain and temperature
  • Improvement of mechanical properties – simultaneous increase of stiffness, strength, and fracture toughness
  • Functional CNTs, e.g., by doping (p-,n- semiconductor) for thermal electric generators
  • Literature
  1. Radushkevich, L.V., Lukyanovich, V.M., 1952. O strukture ugleroda, obrazujucegosja pri termiceskom razlozenii okisi ugleroda na zeleznom kontakte. Zhurnal Fizicheskoi Khimii 26, 88–95.
  2. Iijima, S., 1991. Helical microtubules of graphitic carbon. Nature 354 (6348), 56–58. doi:10.1038/354056a0.
Prof. Dr. Bodo Fiedler
Guest Editor

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Keywords

  • Electrical properties of Polymer–CNT Nanocomposites
  • Mechanical properties of Polymer–CNT Nanocomposites
  • Low filler content–high filler content
  • Dispersion techniques also in combination with the addition of functional groups
  • Hybrid composites à combination with fibers or other reinforcing elements.
  • Sensors

Published Papers (15 papers)

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Research

Open AccessArticle
Photo Actuation Performance of Nanotube Sheet Incorporated Azobenzene Crosslinked Liquid Crystalline Polymer Nanocomposite
Polymers 2019, 11(4), 735; https://doi.org/10.3390/polym11040735 - 23 Apr 2019
Abstract
Crosslinked liquid crystalline polymers (CLCPs) containing azobenzene (AZO-CLCPs) are a type of promising material due to their significance in the design of light-driven smart actuators. Developing AZO-CLCP composites by incorporating AZO-CLCPs with other materials is an effective way of enhancing their practicability. Herein, [...] Read more.
Crosslinked liquid crystalline polymers (CLCPs) containing azobenzene (AZO-CLCPs) are a type of promising material due to their significance in the design of light-driven smart actuators. Developing AZO-CLCP composites by incorporating AZO-CLCPs with other materials is an effective way of enhancing their practicability. Herein, we report an AZO-CLCP/CNT nanocomposite prepared by the in situ polymerization of diacrylates containing azobenzene chromophores on carbon nanotube (CNT) sheets. The liquid crystal phase structure of CLCP matrix was evidenced by the two-dimensional X-ray scattering. The prepared pure AZO-CLCP films and AZO-CLCP/CNT nanocomposite films demonstrated strong reversible photo-triggered deformation under the irradiation of UV light at 366 nm of wavelength, as a result of photo-induced isomerization of azobenzene moieties in the polymer network. But compared to pure AZO-CLCP films, the AZO-CLCP/CNT nanocomposite films could much more rapidly return to their initial shapes after the UV light irradiation was removed due to the elasticity effect of CNT sheets. The deformation behavior of AZO-CLCP/CNT nanocomposite films under the light irradiation was also different from that of the pure AZO-CLCP films due to the interfacial interaction between a polymer network and CNT sheet. Furthermore, incorporation of a CNT sheet remarkably increased the mechanical strength and robustness of the material. We also used this AZO-CLCP/CNT nanocomposite as a microvalve membrane actuator, which can be controlled by light, for a conceptual device of a microfluidic system. The results showed that this AZO-CLCP/CNT nanocomposite may have great potential in smart actuator applications for biological engineering, medical treatment, environment detection and microelectromechanical systems (MEMS), etc. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
Boosting the Adhesivity of π-Conjugated Polymers by Embedding Platinum Acetylides towards High-Performance Thermoelectric Composites
Polymers 2019, 11(4), 593; https://doi.org/10.3390/polym11040593 - 01 Apr 2019
Abstract
Single-walled carbon nanotubes (SWCNTs) incorporated with π-conjugated polymers, have proven to be an effective approach in the production of advanced thermoelectric composites. However, the studied polymers are mainly limited to scanty conventional conductive polymers, and their performances still remain to be improved. Herein, [...] Read more.
Single-walled carbon nanotubes (SWCNTs) incorporated with π-conjugated polymers, have proven to be an effective approach in the production of advanced thermoelectric composites. However, the studied polymers are mainly limited to scanty conventional conductive polymers, and their performances still remain to be improved. Herein, a new planar moiety of platinum acetylide in the π-conjugated system is introduced to enhance the intermolecular interaction with the SWCNTs via π–π and d–π interactions, which is crucial in regulating the thermoelectric performances of SWCNT-based composites. As expected, SWCNT composites based on the platinum acetylides embedded polymers displayed a higher power factor (130.7 ± 3.8 μW·m−1·K−2) at ambient temperature than those without platinum acetylides (59.5 ± 0.7 μW·m−1·K−2) under the same conditions. Moreover, the strong interactions between the platinum acetylide-based polymers and the SWCNTs are confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
The Effect of Multilevel Carbon Reinforcements on the Fire Performance, Conductivity, and Mechanical Properties of Epoxy Composites
Polymers 2019, 11(2), 303; https://doi.org/10.3390/polym11020303 - 12 Feb 2019
Cited by 1
Abstract
We studied the effect of a multilevel presence of carbon-based reinforcements—a combination of conventional load-bearing unidirectional carbon fiber (CF) with multiwalled carbon nanotubes (CNT) and conductive CNT-containing nonwoven carbon nanofabric (CNF(CNT))—on the fire performance, thermal conductivity, and mechanical properties of reference and flame-retarded [...] Read more.
We studied the effect of a multilevel presence of carbon-based reinforcements—a combination of conventional load-bearing unidirectional carbon fiber (CF) with multiwalled carbon nanotubes (CNT) and conductive CNT-containing nonwoven carbon nanofabric (CNF(CNT))—on the fire performance, thermal conductivity, and mechanical properties of reference and flame-retarded epoxy resin (EP) composites. The inclusion of carbon fibers and flame retardant reduced the peak heat release rate (pHRR) of the epoxy resins. The extent to which the nanoreinforcements reduced the pHRR depended on their influence on thermal conductivity. Specifically, high thermal conductivity is advantageous at the early stages of degradation, but after ignition it may lead to more intensive degradation and a higher pHRR; especially in the reference samples without flame retardant. The lowest pHRR (130 kW/m2) and self-extinguishing V-0 UL-94 rating was achieved in the flame-retarded composite containing all three levels of carbon reinforcement (EP + CNF(CNT) + CNT + CF FR). The plasticizing effect of the liquid flame retardant impaired both the tensile and flexural properties; however, it significantly enhanced the impact resistance of the epoxy resin and its composites. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessCommunication
Preparation and Thermoelectric Properties Study of Bipyridine-Containing Polyfluorene Derivative/SWCNT Composites
Polymers 2019, 11(2), 278; https://doi.org/10.3390/polym11020278 - 07 Feb 2019
Cited by 2
Abstract
Polymer/inorganic thermoelectric composites have witnessed rapid progress in recent years, but most of the studies have focused on the traditional conducting polymers. The limited structures of traditional conducting polymers restrain the development of organic thermoelectric composites. Herein, we report the preparation and thermoelectric [...] Read more.
Polymer/inorganic thermoelectric composites have witnessed rapid progress in recent years, but most of the studies have focused on the traditional conducting polymers. The limited structures of traditional conducting polymers restrain the development of organic thermoelectric composites. Herein, we report the preparation and thermoelectric properties of a series of composites films based on SWCNTs and bipyridine-containing polyfluorene derivatives. The value of the power factor around 12 μW m−1 K−2 was achieved for the composite F8bpy/SWCNTs with a mass ratio of 50/50, and the maximum value of 62.3 μW m−1 K−2 was obtained when the mass ratio reached 10/90. Moreover, taking advantage of the bipyridine unit could chelate various kinds of metal ions to form polymer complexes. The enhanced power factor of 87.3 μW m−1 K−2 was obtained for composite F8bpy-Ni/SWCNTs with a mass ratio of 50/50. Finally, the thermoelectric properties of the bipyridine-containing polyfluorene derivative/SWCNT composites were conveniently tuned by chelating with different metal ions. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
Carbon Nanoparticles’ Impact on Processability and Physical Properties of Epoxy Resins—A Comprehensive Study Covering Rheological, Electrical, Thermo-Mechanical, and Fracture Properties (Mode I and II)
Polymers 2019, 11(2), 231; https://doi.org/10.3390/polym11020231 - 01 Feb 2019
Cited by 1
Abstract
A trade-off between enhancement of physical properties of the final part and the processability during manufacturing always exists for the application of nanocarbon materials in thermoset-based composites. For different epoxy resins, this study elaborates the impact of nanocarbon particle type, functionalization, and filler [...] Read more.
A trade-off between enhancement of physical properties of the final part and the processability during manufacturing always exists for the application of nanocarbon materials in thermoset-based composites. For different epoxy resins, this study elaborates the impact of nanocarbon particle type, functionalization, and filler loading on the resulting properties, i.e., rheological, electrical, thermo-mechanical, as well as the fracture toughness in mode I and mode II loading. Therefore, a comprehensive set of carbon nanoparticles, consisting of carbon black (CB), single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), few layer graphene (FLG), and electrochemically expanded graphite (ExG), in purified or functionalized configuration was introduced in various epoxy resins, with different molecular weight distributions. A novel technique to introduce sharp cracks into single-edge notched bending (SENB) fracture toughness specimens led to true values. SWCNT show highest potential for increasing electrical properties without an increase in viscosity. Functionalized MWCNT and planar particles significantly increase the fracture toughness in mode I by a factor of two. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
Melt-Mixed PP/MWCNT Composites: Influence of CNT Incorporation Strategy and Matrix Viscosity on Filler Dispersion and Electrical Resistivity
Polymers 2019, 11(2), 189; https://doi.org/10.3390/polym11020189 - 22 Jan 2019
Cited by 2
Abstract
Small-scale melt mixing was performed for composites based on polypropylene (PP) and 0.5–7.5 wt % multiwalled carbon nanotubes (MWCNT) to determine if masterbatch (MB) dilution is a more effective form of nanofiller dispersion than direct nanotube incorporation. The methods were compared using composites [...] Read more.
Small-scale melt mixing was performed for composites based on polypropylene (PP) and 0.5–7.5 wt % multiwalled carbon nanotubes (MWCNT) to determine if masterbatch (MB) dilution is a more effective form of nanofiller dispersion than direct nanotube incorporation. The methods were compared using composites of five different PP types, each filled with 2 wt % MWCNTs. After the determination of the specific mechanical energy (SME) input in the MB dilution process, the direct-incorporation mixing time was adjusted to achieve comparable SME values. Interestingly, the electrical resistivity of MB-prepared samples with 2 wt % MWCNTs was higher than that of those prepared using direct incorporation—despite their better dispersion—suggesting more pronounced MWCNT shortening in the two-step procedure. In summary, this study on PP suggests that the masterbatch approach is suitable for the dispersion of MWCNTs and holds advantages in nanotube dispersion, albeit at the cost of slightly increased electrical resistivity. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
In Situ Growth of a High-Performance All-Solid-State Electrode for Flexible Supercapacitors Based on a PANI/CNT/EVA Composite
Polymers 2019, 11(1), 178; https://doi.org/10.3390/polym11010178 - 21 Jan 2019
Cited by 1
Abstract
For the development of light, flexible, and wearable electronic devices, it is crucial to develop energy storage components combining high capacity and flexibility. Herein, an all-solid-state supercapacitor is prepared through an in situ growth method. The electrode contains polyaniline deposited on a carbon [...] Read more.
For the development of light, flexible, and wearable electronic devices, it is crucial to develop energy storage components combining high capacity and flexibility. Herein, an all-solid-state supercapacitor is prepared through an in situ growth method. The electrode contains polyaniline deposited on a carbon nanotube and a poly (ethylene-co-vinyl acetate) film. The hybrid electrode exhibits excellent mechanical and electrochemical performance. The optimized few-layer polyaniline wrapping layer provides a conductive network that effectively enhances the cycling stability, as 66.4% of the starting capacitance is maintained after 3000 charge/discharge cycles. Furthermore, the polyaniline (PANI)-50 displays the highest areal energy density of 83.6 mWh·cm−2, with an areal power density of 1000 mW·cm−2, and a high areal capacity of 620 mF cm−2. The assembled device delivers a high areal capacity (192.3 mF·cm−2) at the current density of 0.1 mA·cm−2, a high areal energy (26.7 mWh·cm−2) at the power density of 100 mW·cm−2, and shows no significant decrease in the performance with a bending angle of 180°. This unique flexible supercapacitor thus exhibits great potential for wearable electronics. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
Orientation and Dispersion Evolution of Carbon Nanotubes in Ultra High Molecular Weight Polyethylene Composites under Extensional-Shear Coupled Flow: A Dissipative Particle Dynamics Study
Polymers 2019, 11(1), 154; https://doi.org/10.3390/polym11010154 - 17 Jan 2019
Abstract
The property of carbon nanotubes (CNTs)-based composites are significantly dependent on the orientation and dispersion evolution of CNTs in the polymer matrix. In this work, the dissipative particle dynamics (DPD) simulations are employed to discover the orientation and dispersion evolution of CNTs in [...] Read more.
The property of carbon nanotubes (CNTs)-based composites are significantly dependent on the orientation and dispersion evolution of CNTs in the polymer matrix. In this work, the dissipative particle dynamics (DPD) simulations are employed to discover the orientation and dispersion evolution of CNTs in ultra–high molecular weight polyethylene (UHMWPE) under extensional–shear coupled flow conditions for the first time. In this paper, we investigate the roles of the increasing extensional-shear coupled rate in morphology of CNTs/UHMWPE composites by varying CNTs concentration and observe that the system under consideration lies in the same evolution morphologies. When comparing our results for various morphologies, we notice that the orientation is affected more significantly by changing the extensional-shear coupled rates. A good alignment appears with an increase of extensional-shear coupled rates, which transform it into ordered morphology. In addition, a higher extensional-shear coupled rate does not necessarily contribute to better dispersion even though CNTs concentration varies, as shown by the mean square displacement (MSD) and the relative concentration distribution functions of CNTs in CNTs/UHMWPE composites. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
The Influence of the Blend Ratio in PA6/PA66/MWCNT Blend Composites on the Electrical and Thermal Properties
Polymers 2019, 11(1), 122; https://doi.org/10.3390/polym11010122 - 11 Jan 2019
Cited by 2
Abstract
It is known that the percolation threshold of polyamide 6 (PA6)/multiwalled carbon nanotube (MWCNT) composites is higher than that of PA66/MWCNT composites under the same mixing conditions and melt viscosity. A series of blends of PA6 and PA66 containing 1 wt % MWCNTs [...] Read more.
It is known that the percolation threshold of polyamide 6 (PA6)/multiwalled carbon nanotube (MWCNT) composites is higher than that of PA66/MWCNT composites under the same mixing conditions and melt viscosity. A series of blends of PA6 and PA66 containing 1 wt % MWCNTs have been prepared to investigate this phenomenon. At contents up to 20 wt % PA66, the blends were not electrically conductive. The electrical resistivity dropped to 109 Ohm∙cm for PA66/PA6 30/70 blends. The resistivity was 105 Ohm∙cm at higher PA66 contents. Differential scanning calorimetry was used to investigate the thermal behavior of blends. The glass transition temperature was almost constant for all blend compositions, indicating that the amorphous phases are miscible. The MWCNT addition influenced the crystallization of PA66 much more than the PA6 crystallization. A heterogeneous crystallization of the polyamide in PA66/PA6 blends took place, and the MWCNTs were mainly localized in the earlier crystallizing PA66 phase. Thus, the formation of the nanotube network and thus the electrical volume resistivity of the PA6/PA66 blends with 1 wt % MWCNTs is significantly influenced by the crystallization behavior. In PA66/PA6 blends up to 60 wt %, the more expensive PA66 can be replaced by the cheaper PA6 while retaining its electrical properties. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
Synergetic Toughening Effect of Carbon Nanotubes and β-Nucleating Agents on the Polypropylene Random Copolymer/Styrene-Ethylene-Butylene- Styrene Block Copolymer Blends
Polymers 2019, 11(1), 29; https://doi.org/10.3390/polym11010029 - 26 Dec 2018
Cited by 2
Abstract
Polypropylene random co-polymer (PPR)/styrene-ethylene-butylene-styrene (SBS) block copolymer blends with high toughness and favorable tensile properties were successfully obtained by blending with traces of multi-wall carbon nanotubes (MWCNTs) and β-nucleating agents (β-NAs). β-NAs can effectively induce the ductile β-form crystal in the PPR matrix. [...] Read more.
Polypropylene random co-polymer (PPR)/styrene-ethylene-butylene-styrene (SBS) block copolymer blends with high toughness and favorable tensile properties were successfully obtained by blending with traces of multi-wall carbon nanotubes (MWCNTs) and β-nucleating agents (β-NAs). β-NAs can effectively induce the ductile β-form crystal in the PPR matrix. Although the addition of MWCNTs was reported to be only benefit for the tensile strength of PPR and relatively disadvantageous for the toughness, the obviously synergistic toughening effect in PPR/SBS blends was found when MWCNTs and β-NAs coexisted. The notched izod impact strength of PPR/30 wt % SBS blend with MWCNTs and β-NAs increased from 11.3 to 58.9 kJ/m2; more than 5-fold increment compared with pure PPR. Meanwhile, the tensile strength retention of this PPR blend is still above 72.2%. The micro-morphology indicated that the MWCNTs can act as bridges between SBS particle and PPR matrix, effectively transferring the stress and absorbing impact energy among SBS particles. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
Bidirectional and Stretchable Piezoresistive Sensors Enabled by Multimaterial 3D Printing of Carbon Nanotube/Thermoplastic Polyurethane Nanocomposites
Polymers 2019, 11(1), 11; https://doi.org/10.3390/polym11010011 - 21 Dec 2018
Cited by 7
Abstract
Fabricating complex sensor platforms is still a challenge because conventional sensors are discrete, directional, and often not integrated within the system at the material level. Here, we report a facile method to fabricate bidirectional strain sensors through the integration of multiwalled carbon nanotubes [...] Read more.
Fabricating complex sensor platforms is still a challenge because conventional sensors are discrete, directional, and often not integrated within the system at the material level. Here, we report a facile method to fabricate bidirectional strain sensors through the integration of multiwalled carbon nanotubes (MWCNT) and multimaterial additive manufacturing. Thermoplastic polyurethane (TPU)/MWCNT filaments were first made using a two-step extrusion process. TPU as the platform and TPU/MWCNT as the conducting traces were then 3D printed in tandem using multimaterial fused filament fabrication to generate uniaxial and biaxial sensors with several conductive pattern designs. The sensors were subjected to a series of cyclic strain loads. The results revealed excellent piezoresistive responses with cyclic repeatability in both the axial and transverse directions and in response to strains as high as 50%. It was shown that the directional sensitivity could be tailored by the type of pattern design. A wearable glove, with built-in sensors, capable of measuring finger flexure was also successfully demonstrated where the sensors are an integral part of the system. These sensors have potential applications in wearable electronics, soft robotics, and prosthetics, where complex design, multi-directionality, embedding, and customizability are demanded. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
Hybrid Materials Based on l,d-Poly(lactic acid) and Single-Walled Carbon Nanotubes as Flexible Substrate for Organic Devices
Polymers 2018, 10(11), 1271; https://doi.org/10.3390/polym10111271 - 15 Nov 2018
Abstract
We report on the application of l,d-poly(lactic acid) (l,d-PLA) with dispersed Single-Walled Carbon Nanotubes (SWCN) as a flexible translucent electrode for organic devices. We used commercially available nanotubes in various weight ratios from 0 to 8% dispersed in chloroform polymeric [...] Read more.
We report on the application of l,d-poly(lactic acid) (l,d-PLA) with dispersed Single-Walled Carbon Nanotubes (SWCN) as a flexible translucent electrode for organic devices. We used commercially available nanotubes in various weight ratios from 0 to 8% dispersed in chloroform polymeric solution by ultrasonication and were drop cast. The created hybrid materials were investigated by differential scanning calorimetry to determine the influence of SWCN content on the thermal behavior, while polarizing optical microscope was used to find the effect of mechanical deformations on the textures. Drop-cast films were studied by optical transmittance, conductivity, dielectric properties and by thermal imaging under applied potential. Thermal imaging provided evidence of visible voltage-activated conduction. Simple mechanical deformation such as bending with stretching at edge to ca. 90 and elongation test were performed. Moreover, interactions between l,d-poly(lactic acid) and SWCN were investigated by FT-IR and NMR spectroscopy. Finally, we can conclude that the thermographic examination of created films permits fast, simple and inexpensive localization of defects on the surface of l,d-PLA:SWCN film, together with the electrical properties of the films. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
Remarkable Improvement in the Mechanical Properties of Epoxy Composites Achieved by a Small Amount of Modified Helical Carbon Nanotubes
Polymers 2018, 10(10), 1103; https://doi.org/10.3390/polym10101103 - 05 Oct 2018
Cited by 4
Abstract
Helical carbon nanotubes (HCNTs) were functionalized to fabricate HCNT/epoxy composites. Acid oxidation and a silane coupling agent, glycidoxypropyltrimethoxysilane (KH560), were used to modify the HCNTs. Remarkably, the flexural strength and the flexural strain were enhanced by 72.0% and 325.0%, respectively, compared to pure [...] Read more.
Helical carbon nanotubes (HCNTs) were functionalized to fabricate HCNT/epoxy composites. Acid oxidation and a silane coupling agent, glycidoxypropyltrimethoxysilane (KH560), were used to modify the HCNTs. Remarkably, the flexural strength and the flexural strain were enhanced by 72.0% and 325.0%, respectively, compared to pure epoxy after adding a small amount of the KH560 modified HCNTs (K-HCNTs). Simultaneously, the tensile strength and Young’s modulus of K-HCNTs/epoxy composites were 51.3% and 270.9% higher than those of pure epoxy. It is found that the presence of silane molecules improved the dispersion of HCNTs in epoxy and the interfacial interaction. Moreover, it has been found that the mechanically interlocking effect from the helical shape of HCNTs also contributes to the improved mechanical properties of epoxy composites, compared to their straight multi-walled carbon nanotube (MWCNT) counterparts. This work provides a low-cost and efficient approach to strengthen and toughen epoxy composites. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
Frequency or Amplitude?—Rheo-Electrical Characterization of Carbon Nanoparticle Filled Epoxy Systems
Polymers 2018, 10(9), 999; https://doi.org/10.3390/polym10090999 - 07 Sep 2018
Cited by 2
Abstract
Dispersion of carbon nanoparticles in epoxy resin is the key factor to adjust the resulting electrical and mechanical properties of the nanocomposite. A profound understanding of the driving forces of standard methods like ultrasonic and mechanical dispersion is necessary. To derive the impact [...] Read more.
Dispersion of carbon nanoparticles in epoxy resin is the key factor to adjust the resulting electrical and mechanical properties of the nanocomposite. A profound understanding of the driving forces of standard methods like ultrasonic and mechanical dispersion is necessary. To derive the impact of applied frequency and strain on the resulting dispersion of multi-walled carbon nanotube (MWCNT)-filled epoxy resin, this work addresses the strain and frequency dependency of oscillatory shear flow-induced network changes. Strain- and frequency-sweeps were performed for a wide parameter set with in-line measurement of electrical DC resistance to monitor changes in the MWCNT network. Changes in electrical resistance reveal destruction and formation of the MWCNT network. A fundamental novel finding is the governing dependency of changes in the electrical network on applied shear amplitude. The applied frequency barely induces network changes. Applied shear rates do not correlate with particular network states. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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Open AccessArticle
Novel Biobased Polyamide 410/Polyamide 6/CNT Nanocomposites
Polymers 2018, 10(9), 986; https://doi.org/10.3390/polym10090986 - 04 Sep 2018
Cited by 2
Abstract
Biobased polyamide 410 (PA410)/multiwall carbon nanotube (CNT) nanocomposites (NCs) were obtained by melt-mixing in a twin screw extruder a Polyamide 6 (PA6)-based masterbatch (with 15 wt % CNT content) with neat PA410. Directly mixed PA410/CNT NCs were also obtained for comparison purposes. Transmision [...] Read more.
Biobased polyamide 410 (PA410)/multiwall carbon nanotube (CNT) nanocomposites (NCs) were obtained by melt-mixing in a twin screw extruder a Polyamide 6 (PA6)-based masterbatch (with 15 wt % CNT content) with neat PA410. Directly mixed PA410/CNT NCs were also obtained for comparison purposes. Transmision Electronic Microscopy (TEM) observation and conductivity measurements demonstrated that a good dispersion of CNTs was obtained, which was probably induced by the full miscibility between PA410 and PA6 (in the concentration range employed here), as ascertained by Differential Scanning Calorimetry (DSC) tests. As a result, the PA410/PA6/CNT NCs showed superior mechanical behaviour (≈10% Young’s modulus increase with a 4 wt % CNT content) than the binary PA410/CNT NCs (≈5% Young’s modulus increase with a 6 wt % CNT content), as well as superior electrical behaviour, with maximum conductivity values of approximately three orders of magnitude higher than in the binary PA410/CNT system, and lower percolation threshold values (0.65 wt % CNT content vs. 3.98 wt % CNT). The good dispersion and enhanced mechanical and electrical properties of these novel biobased nanocomposites, broadens their potential applications, such as electrical and electronics (E&E) or automotive industries. Full article
(This article belongs to the Special Issue Polymer-CNT Nanocomposites)
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