Materials

12 pages, 2650 KiB

Open AccessArticle

Effect of Tow Size and Interface Interaction on Interfacial Shear Strength Determined by Iosipescu (V-Notch) Testing in Epoxy Resin

by Filip Stojceveski, Andreas Hendlmeier, James D. Randall, Chantelle L. Arnold, Melissa K. Stanfield, Daniel J. Eyckens, Richard Alexander and Luke C. Henderson

Materials 2018, 11(9), 1786; https://doi.org/10.3390/ma11091786 - 19 Sep 2018

Cited by 6 | Viewed by 5128

Abstract

Testing methodologies to accurately quantify interfacial shear strength (IFSS) are essential in order to understand fiber-matrix adhesion. While testing methods at a microscale (single filament fragmentation test—SFFT) and macroscale (Short Beam Shear—SBS) are wide spread, each have their own shortcomings. The Iosipescu (V-notch) [...] Read more.

Testing methodologies to accurately quantify interfacial shear strength (IFSS) are essential in order to understand fiber-matrix adhesion. While testing methods at a microscale (single filament fragmentation test—SFFT) and macroscale (Short Beam Shear—SBS) are wide spread, each have their own shortcomings. The Iosipescu (V-notch) tow test offers a mesoscale bridge between the microscale and macroscale whilst providing simple, accurate results with minimal time investment. However, the lack of investigations exploring testing variables has limited the application of Iosipescu testing to only a handful of studies. This paper assesses the effect of carbon fiber tow size within the Iosipescu tow test for epoxy resin. Tow sizes of 3, 6, and 9 k are eminently suitable, while more caution must be shown when examining 12, and 15 k tows. In this work, tows at 18 and 24 k demonstrated failure modes not derived from interfacial failure, but poor fiber wetting. A catalogue of common fracture geometries is discussed as a function of performance for the benefit of future researchers. Finally, a comparison of commercial (T300), amine (T300-Amine), and ethyl ester (T300-Ester) surface modified carbon fibers was conducted. The outcomes of this study showed that the Iosipescu tow test is inherently less sensitive in distinguishing between similar IFSS but provides a more ‘real world’ image of the carbon fiber-epoxy interface in a composite material. Full article

(This article belongs to the Special Issue Polymer Composites and Interfaces)

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12 pages, 2491 KiB

Open AccessArticle

The Effects of Using Aluminum Oxide Nanoparticles as Heat Transfer Fillers on Morphology and Thermal Performances of Form-Stable Phase Change Fibrous Membranes Based on Capric–Palmitic–Stearic Acid Ternary Eutectic/Polyacrylonitrile Composite

by Huizhen Ke and Yonggui Li

Materials 2018, 11(9), 1785; https://doi.org/10.3390/ma11091785 - 19 Sep 2018

Cited by 10 | Viewed by 4358

Abstract

In this paper, innovative capric–palmitic–stearic acid ternary eutectic/polyacrylonitrile/aluminum oxide (CA–PA–SA/PAN/Al₂O₃) form-stable phase change composite fibrous membranes (PCCFMs) with different mass ratios of Al₂O₃ nanoparticles were prepared for thermal energy storage. The influences of Al₂O [...] Read more.

In this paper, innovative capric–palmitic–stearic acid ternary eutectic/polyacrylonitrile/aluminum oxide (CA–PA–SA/PAN/Al₂O₃) form-stable phase change composite fibrous membranes (PCCFMs) with different mass ratios of Al₂O₃ nanoparticles were prepared for thermal energy storage. The influences of Al₂O₃ nanoparticles on morphology and thermal performances of the form-stable PCCFMs were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and measurement of melting and freezing times, respectively. The results showed that there was no apparent leakage trace from the SEM observation. The DSC analysis indicated that the addition of Al₂O₃ nanoparticles had no significant effect on phase transition temperatures and enthalpies of the CA–PA–SA/PAN/Al₂O₃ form-stable PCCFMs. The melting peak temperatures and melting enthalpies of form-stable PCCFMs were about 25 °C and 131–139 kJ/kg, respectively. The melting and freezing times of the CA–PA–SA/PAN/Al₂O₃10 form-stable PCCFMs were shortened by approximately 21% and 23%, respectively, compared with those of the CA–PA–SA/PAN form-stable PCCFMs due to the addition of Al₂O₃ nanoparticles acting as heat transfer fillers. Full article

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8 pages, 3226 KiB

Open AccessArticle

Fabrication of Porous Al₂O₃ Ceramics with Submicron-Sized Pores Using a Water-Based Gelcasting Method

by Zhihong Yang, Nan Chen and Xiaomei Qin

Materials 2018, 11(9), 1784; https://doi.org/10.3390/ma11091784 - 19 Sep 2018

Cited by 14 | Viewed by 6087

Abstract

The gelcasting method is usually employed to fabricate relatively dense ceramics. In this work, however, porous Al₂O₃ ceramics with submicron-sized pores were fabricated using the water-based gelcasting method by keeping the Al₂O₃ content at low levels. By [...] Read more.

The gelcasting method is usually employed to fabricate relatively dense ceramics. In this work, however, porous Al₂O₃ ceramics with submicron-sized pores were fabricated using the water-based gelcasting method by keeping the Al₂O₃ content at low levels. By controlling the water content in the ceramic slurries and the sintering temperature of the green samples, the volume fractions and the size characteristics of the pores in the porous Al₂O₃ can be readily obtained. For the porous Al₂O₃ ceramics prepared with 30 vol.% Al₂O₃ content in the slurries, their open porosities were from 38.3% to 47.2%, while their median pore sizes varied from 299.8 nm to 371.9 nm. When there was more Al₂O₃ content in the slurries (40 vol.% Al₂O₃), the porous Al₂O₃ ceramics had open porosities from 37.0% to 46.5%, and median pore sizes from 355.4 nm to 363.1 nm. It was found that a higher sintering temperature and Al₂O₃ content in the slurries increased the mechanical strength of the porous Al₂O₃ ceramics. Full article

(This article belongs to the Special Issue Microstructure-mechanical Properties Relationship for Porous Materials)

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13 pages, 4355 KiB

Open AccessArticle

Synthesis and Exploration of the Lubricating Behavior of Nanoparticulated Mo₁₅S₁₉ in Linseed Oil

by Ignacio A. Fernández-Coppel, Pablo Martín-Ramos, Jesús Martín-Gil, Ramón Pamies, Manuel Avella and María Dolores Avilés

Materials 2018, 11(9), 1783; https://doi.org/10.3390/ma11091783 - 19 Sep 2018

Cited by 4 | Viewed by 3877

Abstract

Molybdenum chalcogenides present interesting properties beyond their superconducting critical temperatures and upper critical magnetic fields, making them suitable for potential applications in tribology, batteries, catalysis, or thermopower. In this study, Mo₁₅S₁₉ nanoparticles with an average diameter of 10 nm were [...] Read more.

Molybdenum chalcogenides present interesting properties beyond their superconducting critical temperatures and upper critical magnetic fields, making them suitable for potential applications in tribology, batteries, catalysis, or thermopower. In this study, Mo₁₅S₁₉ nanoparticles with an average diameter of 10 nm were synthesized via the reaction of ammonium molybdate with hydrochloric acid and elemental sulfur as reducers at 245 °C. The oxidation to MoO₃ in air was efficiently avoided by using linseed oil as a reaction medium and dispersant. Scanning electron microscopy (SEM) micrographs of the as-prepared samples revealed the presence of few-micron-size aggregates, while transmission electron microscopy (TEM) characterization evidenced that the samples were polynanocrystalline with a high degree of homogeneity in size (standard deviation of 2.7 nm). The absence of the first-order (00l) reflection in the X-ray diffraction pattern was also indicative of the absence of Mo₃S₄ stacking, suggesting that it was a non-layered material. A dispersion of the nanoparticles in linseed oil has been studied as a lubricant of steel–steel sliding contacts, showing the formation of a surface layer that reduces wear and mean friction coefficients with respect to the base oil. Full article

(This article belongs to the Special Issue Tribology of Materials and Analysis)

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12 pages, 7560 KiB

Open AccessArticle

Study of Almond Shell Characteristics

by Xuemin Li, Yinan Liu, Jianxiu Hao and Weihong Wang

Materials 2018, 11(9), 1782; https://doi.org/10.3390/ma11091782 - 19 Sep 2018

Cited by 114 | Viewed by 8627

Abstract

A large amount of almond shells are disposed of every year. The anatomical and chemical characteristics of almond shells are investigated in this paper in order to contribute to better utilization of these shells. The micromorphology, surface elements, thermal stability, crystallization, chemical composition, [...] Read more.

A large amount of almond shells are disposed of every year. The anatomical and chemical characteristics of almond shells are investigated in this paper in order to contribute to better utilization of these shells. The micromorphology, surface elements, thermal stability, crystallization, chemical composition, and relative properties of almond shells are analyzed. Under observation by microscope and electron microscope, the diameter of almond shells is 300–500 μm for large holes, and 40–60 μm for small holes present in the shell. X-ray photoelectron spectroscopy shows the elements of almond shells include C (72.27%), O (22.88%), N (3.87%), and Si (0.87%). The main chemical constituents of cellulose, hemicellulose and lignin in almond shells account for 38.48%, 28.82% and 29.54%, respectively. The alkaline extract content of almond shells is 14.03%, and benzene alcohol extraction is 8.00%. The benzene alcohol extractives of almond shells mainly contain 17 types of organic compound, including benzene ring, ethylene, carbon three bond, and other mufti-functional groups. Thermal stability analysis shows almond shells mainly lose weight at 260 °C and 335 °C. These characteristics indicate that almond shells have the capacity to be used in composites and absorption materials. Full article

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14 pages, 3460 KiB

Open AccessArticle

Assessment of Migration of Human MSCs through Fibrin Hydrogels as a Tool for Formulation Optimisation

by Nasseem Salam, Sotiria Toumpaniari, Piergiorgio Gentile, Ana Marina Ferreira, Kenneth Dalgarno and Simon Partridge

Materials 2018, 11(9), 1781; https://doi.org/10.3390/ma11091781 - 19 Sep 2018

Cited by 22 | Viewed by 6464

Abstract

Control of cell migration is fundamental to the performance of materials for cell delivery, as for cells to provide any therapeutic effect, they must migrate out from the delivery material. Here the influence of fibrinogen concentration on the migration of encapsulated human mesenchymal [...] Read more.

Control of cell migration is fundamental to the performance of materials for cell delivery, as for cells to provide any therapeutic effect, they must migrate out from the delivery material. Here the influence of fibrinogen concentration on the migration of encapsulated human mesenchymal stem cells (hMSCs) from a cell spheroid through fibrin hydrogels is tracked over time. Fibrin was chosen as a model material as it is routinely employed as a haemostatic agent and more recently has been applied as a localised delivery vehicle for potential therapeutic cell populations. The hydrogels consisted of 5 U/mL thrombin and between 5 and 50 mg/mL fibrinogen. Microstructural and viscoelastic properties of different compositions were evaluated using SEM and rheometry. Increasing the fibrinogen concentration resulted in a visibly denser matrix with smaller pores and higher stiffness. hMSCs dispersed within the fibrin gels maintained cell viability post-encapsulation, however, the migration of cells from an encapsulated spheroid revealed that denser fibrin matrices inhibit cell migration. This study provides the first quantitative study on the influence of fibrinogen concentration on 3D hMSC migration within fibrin gels, which can be used to guide material selection for scaffold design in tissue engineering and for the clinical application of fibrin sealants. Full article

(This article belongs to the Special Issue Scaffold Materials for Tissue Engineering)

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14 pages, 4264 KiB

Open AccessArticle

Large-Strain Hyperelastic Constitutive Model of Envelope Material under Biaxial Tension with Different Stress Ratios

by Zhipeng Qu, Wei He, Mingyun Lv and Houdi Xiao

Materials 2018, 11(9), 1780; https://doi.org/10.3390/ma11091780 - 19 Sep 2018

Cited by 7 | Viewed by 3945

Abstract

This paper reports the biaxial tensile mechanical properties of the envelope material through experimental and constitutive models. First, the biaxial tensile failure tests of the envelope material with different stress ratio in warp and weft directions are carried out. Then, based on fiber-reinforced [...] Read more.

This paper reports the biaxial tensile mechanical properties of the envelope material through experimental and constitutive models. First, the biaxial tensile failure tests of the envelope material with different stress ratio in warp and weft directions are carried out. Then, based on fiber-reinforced continuum mechanics theory, an anisotropic hyperelastic constitutive model on envelope material with different stress ratio is developed. A strain energy function that characterizes the anisotropic behavior of the envelope material is decomposed into three parts: fiber, matrix and fiber–fiber interaction. The fiber–matrix interaction is eliminated in this model. A new simple model for fiber–fiber interaction with different stress ratio is developed. Finally, the results show that the constitutive model has a good agreement with the experiment results. The results can be used to provide a reference for structural design of envelope material. Full article

(This article belongs to the Special Issue Damage Detection and Characterization of High Performance Composites)

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16 pages, 1974 KiB

Open AccessArticle

Photocatalytic Degradation of Diclofenac by Hydroxyapatite–TiO₂ Composite Material: Identification of Transformation Products and Assessment of Toxicity

by Sapia Murgolo, Irina S. Moreira, Clara Piccirillo, Paula M. L. Castro, Gianrocco Ventrella, Claudio Cocozza and Giuseppe Mascolo

Materials 2018, 11(9), 1779; https://doi.org/10.3390/ma11091779 - 19 Sep 2018

Cited by 52 | Viewed by 5521

Abstract

Diclofenac (DCF) is one of the most detected pharmaceuticals in environmental water matrices and is known to be recalcitrant to conventional wastewater treatment plants. In this study, degradation of DCF was performed in water by photolysis and photocatalysis using a new synthetized photocatalyst [...] Read more.

Diclofenac (DCF) is one of the most detected pharmaceuticals in environmental water matrices and is known to be recalcitrant to conventional wastewater treatment plants. In this study, degradation of DCF was performed in water by photolysis and photocatalysis using a new synthetized photocatalyst based on hydroxyapatite and TiO₂ (HApTi). A degradation of 95% of the target compound was achieved in 24 h by a photocatalytic treatment employing the HApTi catalyst in comparison to only 60% removal by the photolytic process. The investigation of photo-transformation products was performed by means of UPLC-QTOF/MS/MS, and for 14 detected compounds in samples collected during treatment with HApTi, the chemical structure was proposed. The determination of transformation product (TP) toxicity was performed by using different assays: Daphnia magna acute toxicity test, Toxi-ChromoTest, and Lactuca sativa and Solanum lycopersicum germination inhibition test. Overall, the toxicity of the samples obtained from the photocatalytic experiment with HApTi decreased at the end of the treatment, showing the potential applicability of the catalyst for the removal of diclofenac and the detoxification of water matrices. Full article

(This article belongs to the Special Issue Application of Photoactive Nanomaterials in Degradation of Pollutants)

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15 pages, 14580 KiB

Open AccessArticle

Stress Ratio and Notch Effects on the Very High Cycle Fatigue Properties of a Near-Alpha Titanium Alloy

by Kun Yang, Bin Zhong, Qi Huang, Chao He, Zhi-Yong Huang, Qingyuan Wang and Yong-Jie Liu

Materials 2018, 11(9), 1778; https://doi.org/10.3390/ma11091778 - 19 Sep 2018

Cited by 17 | Viewed by 4957

Abstract

Ultrasonic fatigue tests up to 10¹⁰ cycles were performed on a turbine engine titanium alloy (Ti-8Al-1Mo-1V) at the stress ratio (R) of −1 with smooth specimens and at R = −1, 0.1 and 0.5 with notched specimens. As a result, [...] Read more.

Ultrasonic fatigue tests up to 10¹⁰ cycles were performed on a turbine engine titanium alloy (Ti-8Al-1Mo-1V) at the stress ratio (R) of −1 with smooth specimens and at R = −1, 0.1 and 0.5 with notched specimens. As a result, with increase of fatigue life, the source of reduced fatigue life caused by multi-point surface crack initiation changes from crack propagation stage to crack initiation stage in the high cycle fatigue regime. Notch effect further promotes the degeneration of high cycle and very high cycle fatigue strength at R > −1. The bilinear model, extended from the Goodman method, can better estimate the mean stress sensitivity of this titanium alloy. The fatigue mean stress sensitivity and fatigue-creep mean stress sensitivity of this material increased with the increase of fatigue life. The new model, based on the Murakami model, can provide more appropriate predictions for notch fatigue strength. Full article

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11 pages, 5188 KiB

Open AccessArticle

Effect of Al Element on the Microstructure and Properties of Cu-Ni-Fe-Mn Alloys

by Ran Yang, Jiuba Wen, Yanjun Zhou, Kexing Song and Zhengcheng Song

Materials 2018, 11(9), 1777; https://doi.org/10.3390/ma11091777 - 19 Sep 2018

Cited by 16 | Viewed by 4530

Abstract

The effects of aluminum on the mechanical properties and corrosion behavior in artificial seawater of Cu-Ni-Fe-Mn alloys were investigated. Cu-7Ni-xAl-1Fe-1Mn samples, consisting of 0, 1, 3, 5, and 7 wt % aluminum along with the same contents of other alloying elements [...] Read more.

The effects of aluminum on the mechanical properties and corrosion behavior in artificial seawater of Cu-Ni-Fe-Mn alloys were investigated. Cu-7Ni-xAl-1Fe-1Mn samples, consisting of 0, 1, 3, 5, and 7 wt % aluminum along with the same contents of other alloying elements (Ni, Fe, and Mn), were prepared. The microstructure of Cu-7Ni-xAl-1Fe-1Mn alloy was analyzed by Transmission Electron Microscopy (TEM), and its corrosion property was tested by an electrochemical system. The results show that the mechanical and corrosion properties of Cu-7Ni-xAl-1Fe-1Mn alloy have an obvious change with the aluminum content. The tensile strength has a peak value of 395 MPa by adding 3 wt % aluminum in the alloy. Moreover, the corrosion rate in artificial seawater of Cu-7Ni-3Al-1Fe-1Mn alloy is 0.0215 mm/a which exhibits a better corrosion resistance than the commercially used UNS C70600. It is confirmed that the second-phase transformation of Cu-7Ni-xAl-1Fe-1Mn alloy follows the sequence of

α

solid solution → Ni₃Al → Ni₃Al + NiAl → Ni₃Al + NiAl₃. The electrochemical impedance spectroscopy (EIS) shows that the adding element aluminum in the Cupronickel can improve the corrosion resistance of Cu-7Ni-xAl-1Fe-1Mn alloy. Full article

(This article belongs to the Section Advanced Materials Characterization)

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11 pages, 6150 KiB

Open AccessArticle

A Semimetal-Like Molybdenum Carbide Quantum Dots Photoacoustic Imaging and Photothermal Agent with High Photothermal Conversion Efficiency

by Wenhao Dai, Haifeng Dong and Xueji Zhang

Materials 2018, 11(9), 1776; https://doi.org/10.3390/ma11091776 - 19 Sep 2018

Cited by 39 | Viewed by 5823

Abstract

Theranostic platforms integrating imaging diagnostic and therapeutic interventions into a single nanoplatform have attracted considerable attention for cancer-individualized therapies. However, their uncertain stability, complex pharmacokinetics, and intrinsic toxicology of multiple components hinder their practical application in clinical research. In this paper, stable and [...] Read more.

Theranostic platforms integrating imaging diagnostic and therapeutic interventions into a single nanoplatform have attracted considerable attention for cancer-individualized therapies. However, their uncertain stability, complex pharmacokinetics, and intrinsic toxicology of multiple components hinder their practical application in clinical research. In this paper, stable and high-concentration molybdenum carbide quantum dots (Mo₂C QDs) with a diameter of approximately 6 nm and a topographic height of about 1.5 nm were synthesized using a facile sonication-assisted liquid-phase exfoliation approach. The prepared Mo₂C QDs exhibited a strong near-infrared (NIR) absorbance with a high molar extinction coefficient of 4.424 Lg⁻¹cm⁻¹ at 808 nm, a high photothermal conversion efficiency of 42.9%, and showed excellent performance on photoacoustic imaging. The Mo₂C QDs had high stability and highly biocompatibility, with low cytotoxicity. Under NIR irradiation, a remarkable in vitro and in vivo therapeutic effect was obtained. Such a stable and biocompatible all-in-one theranostic nanoagent generated by facile synthesis that combines promising imaging guidance and effective tumor ablation properties may hold great potential for theranostic nanomedicine. Full article

(This article belongs to the Special Issue Photothermal Therapy of Nanomaterials)

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10 pages, 7609 KiB

Open AccessArticle

Accelerated Curing and Enhanced Material Properties of Conductive Polymer Nanocomposites by Joule Heating

by Sung-Hwan Jang, Donghak Kim and Yong-Lae Park

Materials 2018, 11(9), 1775; https://doi.org/10.3390/ma11091775 - 19 Sep 2018

Cited by 21 | Viewed by 6011

Abstract

Joule heating is useful for fast and reliable manufacturing of conductive composite materials. In this study, we investigated the influence of Joule heating on curing conditions and material properties of polymer-based conductive composite materials consisting of carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS). We [...] Read more.

Joule heating is useful for fast and reliable manufacturing of conductive composite materials. In this study, we investigated the influence of Joule heating on curing conditions and material properties of polymer-based conductive composite materials consisting of carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS). We applied different voltages to the CNT nanocomposites to investigate their electrical stabilization, curing temperature, and curing time. The result showed that highly conductive CNT/PDMS composites were successfully cured by Joule heating with uniform and fast heat distribution. For a 7.0 wt % CNT/PDMS composite, a high curing temperature of around 100 °C was achieved at 20 V with rapid temperature increase. The conductive nanocomposite cured by Joule heating also revealed an enhancement in mechanical properties without changing the electrical conductivities. Therefore, CNT/PDMS composites cured by Joule heating are useful for expediting the manufacturing process for particulate conductive composites in the field of flexible and large-area sensors and electronics, where fast and uniform curing is critical to their performance. Full article

(This article belongs to the Section Advanced Composites)

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13 pages, 5798 KiB

Open AccessArticle

Design of SnO₂ Aggregate/Nanosheet Composite Structures Based on Function-Matching Strategy for Enhanced Dye-Sensitized Solar Cell Performance

by Dongting Wang, Shangheng Liu, Mingfa Shao, Jinghan Zhao, Yukun Gu, Qiuyi Li, Xianxi Zhang, Jinsheng Zhao and Yuzhen Fang

Materials 2018, 11(9), 1774; https://doi.org/10.3390/ma11091774 - 19 Sep 2018

Cited by 11 | Viewed by 3279

Abstract

Hierarchical SnO₂ nanocrystallites aggregates (NAs) were prepared with a simple room temperature–based aqueous solution method followed by simple freeze-drying treatment. The as-prepared SnO₂ NAs were subsequently combined with SnO₂ nanosheet–based structures from the viewpoint of a function-matching strategy, and under [...] Read more.

Hierarchical SnO₂ nanocrystallites aggregates (NAs) were prepared with a simple room temperature–based aqueous solution method followed by simple freeze-drying treatment. The as-prepared SnO₂ NAs were subsequently combined with SnO₂ nanosheet–based structures from the viewpoint of a function-matching strategy, and under an optimized condition, a power conversion efficiency (PCE) of 5.59% was obtained for the resultant hybrid photoanode, a remarkable 60% enhancement compared to that of dye-sensitized solar cells (DSCs) fabricated with bare SnO₂ NAs architecture. The significantly enhanced efficiency can be attributed to the combination of the desirable electron transport property obtained by the intentionally introduced SnO₂ nanosheets (NSs) and the effectively retained inherent characteristics of SnO₂ NAs, i.e., large surface area and strong light-scattering effect. This work provides a promising approach for the rapid development of highly efficient SnO₂ photoanode film-based DSCs with the properties of simplicity of operation and control over the photoanode composition. Full article

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10 pages, 3604 KiB

Open AccessArticle

Green Transforming Metallurgical Residue into Alkali-Activated Silicomanganese Slag-Based Cementitious Material as Photocatalyst

by Yao Jun Zhang, Pan Yang He, Hao Chen and Li Cai Liu

Materials 2018, 11(9), 1773; https://doi.org/10.3390/ma11091773 - 19 Sep 2018

Cited by 16 | Viewed by 3442

Abstract

Silicomanganese slag is a solid waste in metallurgical industry and can be transformed into an alkali-activated silicomanganese slag-based cementitious-material (ASSC) for the first time. The ASSC shows quite low electro-conductivity and can be raised dramatically by incorporated carbon black (CB) in the matrix [...] Read more.

Silicomanganese slag is a solid waste in metallurgical industry and can be transformed into an alkali-activated silicomanganese slag-based cementitious-material (ASSC) for the first time. The ASSC shows quite low electro-conductivity and can be raised dramatically by incorporated carbon black (CB) in the matrix of ASSC to create an electro-conductive alkali-activated silicomanganese slag-based cementitious-composite (EASSC), served as a low cost and environmentally-friendly photocatalyst for the removal of dye pollutant in the paper. The interrelationships of mechanical, optical, electroconductive, microstructural, and photocatalytic properties are evaluated. The network of CB plays a critical role in the electron transfers. The electrical conductivity of EASSC doped 4.5% CB drastically increases by 594.2 times compared to that of ASSC. The FESEM, XRD, and XPS results indicated that the EASSC with mean grain size about 50 nm is composed of amorphous calcium silicate hydrate (CSH), alabandite (α-MnS) and CB. The UV–vis DRS and PL exhibit that the absorption edges of electro-conductive alkali-activated silicomanganese slag-based cementitious-composite EASSC samples are gradually blue-shifted and the photoluminescence intensities progressively decrease with increasing CB content. The activities of photocatalytic degradation of basic violet 5BN dye are positive correlated to the electro-conductivities. The separation efficiency of photo-generated electron-hole pairs is enhanced due to the electron transfers from α-MnS to the network of CB. The photocatalytic degradation of dye pollutant belongs to the second order kinetics via a reaction mechanism of superoxide radical (•O₂⁻) intermediate. Full article

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13 pages, 1626 KiB

Open AccessArticle

Photosystem II Is More Sensitive than Photosystem I to Al³⁺ Induced Phytotoxicity

by Julietta Moustaka, Georgia Ouzounidou, Ilektra Sperdouli and Michael Moustakas

Materials 2018, 11(9), 1772; https://doi.org/10.3390/ma11091772 - 19 Sep 2018

Cited by 44 | Viewed by 4035

Abstract

Aluminium (Al) the most abundant metal in the earth’s crust is toxic in acid soils (pH < 5.5) mainly in the ionic form of Al³⁺ species. The ability of crops to overcome Al toxicity varies among crop species and cultivars. Here, we [...] Read more.

Aluminium (Al) the most abundant metal in the earth’s crust is toxic in acid soils (pH < 5.5) mainly in the ionic form of Al³⁺ species. The ability of crops to overcome Al toxicity varies among crop species and cultivars. Here, we report for a first time the simultaneous responses of photosystem II (PSII) and photosystem I (PSI) to Al³⁺ phytotoxicity. The responses of PSII and PSI in the durum wheat (Triticum turgidum L. cv. ‘Appulo E’) and the triticale (X Triticosecale Witmark cv. ‘Dada’) were evaluated by chlorophyll fluorescence quenching analysis and reflection spectroscopy respectively, under control (−Al, pH 6.5) and 148 μM Al (+Al, pH 4.5) conditions. During control growth conditions the high activity of PSII in ‘Appulo E’ led to a rather higher electron flow to PSI, which induced a higher PSI excitation pressure in ‘Appulo E’ than in ‘Dada’ that presented a lower PSII activity. However, under 148 μM Al the triticale ‘Dada’ presented a lower PSII and PSI excitation pressure than ‘Appulo E’. In conclusion, both photosystems of ‘Dada’ displayed a superior performance than ‘Appulo E’ under Al exposure, while in both cultivars PSII was more affected than PSI from Al³⁺ phytotoxicity. Full article

(This article belongs to the Special Issue The Role of Metal Ions in Biology, Biochemistry and Medicine)

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12 pages, 4736 KiB

Open AccessArticle

Broadband Microwave Absorbing Composites with a Multi-Scale Layered Structure Based on Reduced Graphene Oxide Film as the Frequency Selective Surface

by Fang Ye, Changqing Song, Qian Zhou, Xiaowei Yin, Meikang Han, Xinliang Li, Litong Zhang and Laifei Cheng

Materials 2018, 11(9), 1771; https://doi.org/10.3390/ma11091771 - 19 Sep 2018

Cited by 22 | Viewed by 5941

Abstract

A broadband microwave absorbing composite with a multi-scale layered structure is proposed, in which a reduced graphene oxide (RGO) film sandwiched between two layers of epoxy glass fiber laminates serves as the frequency selective surface (FSS). RGO films with the desired electrical properties [...] Read more.

A broadband microwave absorbing composite with a multi-scale layered structure is proposed, in which a reduced graphene oxide (RGO) film sandwiched between two layers of epoxy glass fiber laminates serves as the frequency selective surface (FSS). RGO films with the desired electrical properties were synthesized directly by hydrothermal reaction, vacuum filtration, and heat treatment without subsequent processing. With the novel layer-by-layer structure ranging from micro to macro scale, the optimized composite exhibits excellent microwave absorption performance with a total thickness of 3.2 mm. Its reflection coefficient (RC) is less than −10 dB in the entire X and Ku band, reaching a minimum value of −32 dB at 10.2 GHz and an average RC of −22.8 dB from 8 to 18 GHz. Enhanced microwave absorption of the composites is achieved through the optimization of layer thickness in the sandwich structure to promote destructive interference. Improved impedance matching by the introduction of FSS along with the polarization and conduction loss of layered graphene films also contribute to the increased absorption. Full article

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9 pages, 2868 KiB

Open AccessArticle

Cement Kiln By-Pass Dust: An Effective Alkaline Activator for Pozzolanic Materials

by Lukáš Kalina, Vlastimil Bílek, Jr., Tomáš Kiripolský, Radoslav Novotný and Jiří Másilko

Materials 2018, 11(9), 1770; https://doi.org/10.3390/ma11091770 - 19 Sep 2018

Cited by 22 | Viewed by 4721

Abstract

Cement kiln by-pass dust (CKD) is a fine-grained by-product of Portland clinker manufacturing. Its chemical composition is not suitable for returning back into feedstock and, therefore, it has to be discharged. Such an increasing waste production contributes to the high environmental impact of [...] Read more.

Cement kiln by-pass dust (CKD) is a fine-grained by-product of Portland clinker manufacturing. Its chemical composition is not suitable for returning back into feedstock and, therefore, it has to be discharged. Such an increasing waste production contributes to the high environmental impact of the cement industry. A possible solution for the ecological processing of CKD is its incorporation into alkali-activated blast furnace slag binders. Thanks to high alkaline content, CKD serves as an effective accelerator for latent hydraulic substances which positively affect their mechanical properties. It was found out that CKD in combination with sodium carbonate creates sodium hydroxide in situ which together with sodium water glass content increases the dissolution of blast furnace slag particles and subsequently binder phase formation resulting in better flexural and compressive strength development compared to the sample without it. At the same time, the addition of CKD compensates the autogenous shrinkage of alkali-activated materials reducing the risk of material cracking. On the other hand, this type of inorganic admixture accelerates the hydration process causing rapid loss of workability. Full article

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13 pages, 4421 KiB

Open AccessArticle

Phase Transformation and Morphology Evolution of Ti₅₀Cu₂₅Ni₂₀Sn₅ during Mechanical Milling

by Dora Janovszky, Ferenc Kristaly, Tamas Miko, Adam Racz, Maria Sveda, Anna Sycheva and Tomasz Koziel

Materials 2018, 11(9), 1769; https://doi.org/10.3390/ma11091769 - 18 Sep 2018

Cited by 5 | Viewed by 3189

Abstract

Nanocrystalline/amorphous powder was produced by ball milling of Ti₅₀Cu₂₅Ni₂₀Sn₅ (at.%) master alloy. Both laser diffraction particle size analyzer and scanning electron microscope (SEM) were used to monitor the changes in the particle size as well as [...] Read more.

Nanocrystalline/amorphous powder was produced by ball milling of Ti₅₀Cu₂₅Ni₂₀Sn₅ (at.%) master alloy. Both laser diffraction particle size analyzer and scanning electron microscope (SEM) were used to monitor the changes in the particle size as well as in the shape of particles as a function of milling time. During ball milling, the average particle size decreased with milling time from >320 µm to ~38 µm after 180 min of milling. The deformation-induced hardening and phase transformation caused the hardness value to increase from 506 to 779 HV. X-ray diffraction (XRD) analysis was used to observe the changes in the phases/amorphous content as a function of milling time. The amount of amorphous fraction increased continuously until 120 min milling (36 wt % amorphous content). The interval of crystallite size was between 1 and 10 nm after 180 min of milling with 25 wt % amorphous fractions. Cubic Cu(Ni,Cu)Ti₂ structure was transformed into the orthorhombic structure owing to the shear/stress, dislocations, and Cu substitution during the milling process. Full article

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19 pages, 2528 KiB

Open AccessReview

Recent Advances in Fluorescent Probes for Lipid Droplets

by Tkhe Kyong Fam, Andrey S. Klymchenko and Mayeul Collot

Materials 2018, 11(9), 1768; https://doi.org/10.3390/ma11091768 - 18 Sep 2018

Cited by 209 | Viewed by 15200

Abstract

Lipid droplets (LDs) are organelles that serve as the storage of intracellular neutral lipids. LDs regulate many physiological processes. They recently attracted attention after extensive studies showed their involvement in metabolic disorders and diseases such as obesity, diabetes, and cancer. Therefore, it is [...] Read more.

Lipid droplets (LDs) are organelles that serve as the storage of intracellular neutral lipids. LDs regulate many physiological processes. They recently attracted attention after extensive studies showed their involvement in metabolic disorders and diseases such as obesity, diabetes, and cancer. Therefore, it is of the highest importance to have reliable imaging tools. In this review, we focus on recent advances in the development of selective fluorescent probes for LDs. Their photophysical properties are described, and their advantages and drawbacks in fluorescence imaging are discussed. At last, we review the reported applications using these probes including two-photon excitation, in vivo and tissue imaging, as well as LDs tracking. Full article

(This article belongs to the Special Issue Fluorescent Sensors for Selective Detection)

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12 pages, 6054 KiB

Open AccessArticle

Experimental Investigation of Compression Properties of Composites with Printed Braiding Structure

by Zhengning Li, Ge Chen, Haichen Lyu and Frank Ko

Materials 2018, 11(9), 1767; https://doi.org/10.3390/ma11091767 - 18 Sep 2018

Cited by 12 | Viewed by 3579

Abstract

A kind of composite was designed and additive manufacturing (AM) technology was utilized in the braiding structure fabrication. The printed polylactic acid (PLA) braiding structures were integrated with two types of resins (Epon 828 resin and urethane dimethacrylate/triethylene glycol dimethacrylate (UDMA/TEDGMA) resin) used [...] Read more.

A kind of composite was designed and additive manufacturing (AM) technology was utilized in the braiding structure fabrication. The printed polylactic acid (PLA) braiding structures were integrated with two types of resins (Epon 828 resin and urethane dimethacrylate/triethylene glycol dimethacrylate (UDMA/TEDGMA) resin) used as the matrix to make composite specimens. The compression test of the composite specimens showed that the printed PLA braiding structures had the effect of varying the compression properties of pure resins: it decreased the compression properties of Epon 828 resin, but increased those of UDMA/TEGDMA resin. Observing scanning electron microscope (SEM) images, it was noted that the decreasing and increasing in the compression properties of the specimens were related to the bonding compactness between the printed braiding structure and resins. Our results may suggest a new methods for the fast manufacturing of AM-based composites, further research directions, and potential applications of this kind of composites. Full article

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11 pages, 2191 KiB

Open AccessArticle

On the Interactions and Synergism between Phases of Carbon–Phosphorus–Titanium Composites Synthetized from Cellulose for the Removal of the Orange-G Dye

by Hesham Hamad, Jesica Castelo-Quibén, Sergio Morales-Torres, Francisco Carrasco-Marín, Agustín F. Pérez-Cadenas and Francisco J. Maldonado-Hódar

Materials 2018, 11(9), 1766; https://doi.org/10.3390/ma11091766 - 18 Sep 2018

Cited by 31 | Viewed by 4151

Abstract

Carbon–phosphorus–titanium composites (CPT) were synthesized by Ti-impregnation and carbonization of cellulose. Microcrystalline cellulose used as carbon precursor was initially dissolved by phosphoric acid (H₃PO₄) to favor the Ti-dispersion and the simultaneous functionalization of the cellulose chains with phosphorus-containing groups, [...] Read more.

Carbon–phosphorus–titanium composites (CPT) were synthesized by Ti-impregnation and carbonization of cellulose. Microcrystalline cellulose used as carbon precursor was initially dissolved by phosphoric acid (H₃PO₄) to favor the Ti-dispersion and the simultaneous functionalization of the cellulose chains with phosphorus-containing groups, namely phosphates and polyphosphates. These groups interacted with the Ti-precursor during impregnation and determined the interface transformations during carbonization as a function of the Ti-content and carbonization temperature. Amorphous composites with high surface area and mesoporosity were obtained at low Ti-content (Ti:cellulose ratio = 1) and carbonization temperature (500 °C), while in composites with Ti:cellulose ratio = 12 and 800 °C, Ti-particles reacted with the cellulose groups leading to different Ti-crystalline polyphosphates and a marked loss of the porosity. The efficiency of composites in the removal of the Orange G dye in solution by adsorption and photocatalysis was discussed based on their physicochemical properties. These materials were more active than the benchmark TiO₂ material (Degussa P25), showing a clear synergism between phases. Full article

(This article belongs to the Special Issue Element-Doped Functional Carbon-based Materials)

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15 pages, 10675 KiB

Open AccessArticle

Effect of CO₂ Partial Pressure on the Corrosion Behavior of J55 Carbon Steel in 30% Crude Oil/Brine Mixture

by Haitao Bai, Yongqing Wang, Yun Ma, Qingbo Zhang and Ningsheng Zhang

Materials 2018, 11(9), 1765; https://doi.org/10.3390/ma11091765 - 18 Sep 2018

Cited by 39 | Viewed by 6641

Abstract

The influence of CO₂ partial pressure on the corrosion properties, including corrosion rate, morphology, chemical composition, and corrosion depth, of J55 carbon steel in 30% crude oil/brine at 65 °C was investigated. A corrosion mechanism was then proposed based on the understanding [...] Read more.

The influence of CO₂ partial pressure on the corrosion properties, including corrosion rate, morphology, chemical composition, and corrosion depth, of J55 carbon steel in 30% crude oil/brine at 65 °C was investigated. A corrosion mechanism was then proposed based on the understanding of the formation of localized corrosion. Results showed that localized corrosion occurred in 30% crude oil/brine with CO₂. The corrosion rate sharply increased as the CO₂ partial pressure (P

{co}_{2}

) was increased from 0 to 1.5 MPa, decreased from P

{co}_{2}

= 1.5 MPa to P

{co}_{2}

= 5.0 MPa, increased again at P

{co}_{2}

= 5.0 MPa, and then reached a constant value after P

{co}_{2}

= 9.0 MPa. The system pH initially decreased, rapidly increased, and then stabilized as CO₂ partial pressure was increased. In the initial period, the surface of J55 carbon steel in the CO₂/30% crude oil/brine mixtures showed intense corrosion. In conclusion, CO₂ partial pressure affects the protection performance of FeCO₃ by changing the formation of corrosion scale and further affecting the corrosion rate. Full article

(This article belongs to the Section Materials Chemistry)

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18 pages, 2762 KiB

Open AccessFeature PaperArticle

Natural and Modified Montmorillonite Clays as Catalysts for Synthesis of Biolubricants

by Francisco Murilo Tavares Luna, Juan Antonio Cecilia, Rosana Maria Alves Saboya, Deicy Barrera, Karim Sapag, Enrique Rodríguez-Castellón and Célio Loureiro Cavalcante

Materials 2018, 11(9), 1764; https://doi.org/10.3390/ma11091764 - 18 Sep 2018

Cited by 42 | Viewed by 4789

Abstract

In this study, natural and modified clays were evaluated as catalysts in an esterification reaction to obtain bio-based lubricants. The biolubricants are environmentally preferred to petroleum-based lubricants because they are biodegradable and non-toxic. Other advantages include very low volatility due to the high [...] Read more.

In this study, natural and modified clays were evaluated as catalysts in an esterification reaction to obtain bio-based lubricants. The biolubricants are environmentally preferred to petroleum-based lubricants because they are biodegradable and non-toxic. Other advantages include very low volatility due to the high molecular weight and excellent viscosity properties with temperature variations. Modifications in natural clay were performed intending to obtain materials with different textural properties that could improve the reaction under study. The modified clays were obtained in two ways: by pillarization using Al₁₃ Keggin polyoxocations or by acid treatments with H₂SO₄, HCl and HNO₃. All samples were evaluated for the esterification reaction of fatty acids from castor oil (FACO) using 2-ethyl-hexanol. During the reaction step, a zeolite-based adsorbent was used for water removal to increase the reaction equilibrium conversion. Gas chromatography and nuclear magnetic resonance were performed to ensure the formation of the products. The highest conversion of fatty acids to esters was obtained using pillared clays. Adding adsorbent in the reaction medium (10 g of 3A zeolite to 100 g of FACO), the conversion improved from 74–88 wt % after 6 h at 50 °C. Full article

(This article belongs to the Special Issue Advanced Porous Materials for Gas Adsorption and Environmental Catalysis)

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20 pages, 16040 KiB

Open AccessArticle

Selective Laser Melting Strategy for Fabrication of Thin Struts Usable in Lattice Structures

by Radek Vrána, Daniel Koutný, David Paloušek, Libor Pantělejev, Jan Jaroš, Tomáš Zikmund and Jozef Kaiser

Materials 2018, 11(9), 1763; https://doi.org/10.3390/ma11091763 - 18 Sep 2018

Cited by 33 | Viewed by 6450

Abstract

This paper deals with the selective laser melting (SLM) processing strategy for strut-lattice structure production which uses only contour lines and allows the porosity and roughness level to be managed based on combination of the input and linear energy parameters. To evaluate the [...] Read more.

This paper deals with the selective laser melting (SLM) processing strategy for strut-lattice structure production which uses only contour lines and allows the porosity and roughness level to be managed based on combination of the input and linear energy parameters. To evaluate the influence of a laser scanning strategy on material properties and surface roughness a set of experiments was performed. The single welds test was used to find the appropriate processing parameters to achieve continuous welds with known width. Strut samples were used to find a suitable value of weld overlapping and to clarify the influence of input and linear laser energy on the strut porosity and surface roughness. The samples of inclined hollow struts were used to compare the wall thickness with single welds width; the results showed about 25% wider welds in the case of a hollow strut. Using the proposed SLM strategy it is possible to reach a significantly lower porosity and surface roughness of the struts. The best results for struts with an inclination of 35.26° were achieved with 25% track overlapping, input energy in the range from 9 J to 10.5 J and linear energy E_lin from 0.25 to 0.4 J/mm; in particular, the relative density of 99.83% and the surface roughness on the side of the strut of Ra 14.6 μm in an as-built state was achieved. Full article

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29 pages, 11796 KiB

Open AccessReview

Graphene-Based Light Sensing: Fabrication, Characterisation, Physical Properties and Performance

by Adolfo De Sanctis, Jake D. Mehew, Monica F. Craciun and Saverio Russo

Materials 2018, 11(9), 1762; https://doi.org/10.3390/ma11091762 - 18 Sep 2018

Cited by 47 | Viewed by 9018

Abstract

Graphene and graphene-based materials exhibit exceptional optical and electrical properties with great promise for novel applications in light detection. However, several challenges prevent the full exploitation of these properties in commercial devices. Such challenges include the limited linear dynamic range (LDR) of graphene-based [...] Read more.

Graphene and graphene-based materials exhibit exceptional optical and electrical properties with great promise for novel applications in light detection. However, several challenges prevent the full exploitation of these properties in commercial devices. Such challenges include the limited linear dynamic range (LDR) of graphene-based photodetectors, the lack of efficient generation and extraction of photoexcited charges, the smearing of photoactive junctions due to hot-carriers effects, large-scale fabrication and ultimately the environmental stability of the constituent materials. In order to overcome the aforementioned limits, different approaches to tune the properties of graphene have been explored. A new class of graphene-based devices has emerged where chemical functionalisation, hybridisation with light-sensitising materials and the formation of heterostructures with other 2D materials have led to improved performance, stability or versatility. For example, intercalation of graphene with FeCl

_{3}

is highly stable in ambient conditions and can be used to define photo-active junctions characterized by an unprecedented LDR while graphene oxide (GO) is a very scalable and versatile material which supports the photodetection from UV to THz frequencies. Nanoparticles and quantum dots have been used to enhance the absorption of pristine graphene and to enable high gain thanks to the photogating effect. In the same way, hybrid detectors made from stacked sequences of graphene and layered transition-metal dichalcogenides enabled a class of devices with high gain and responsivity. In this work, we will review the performance and advances in functionalised graphene and hybrid photodetectors, with particular focus on the physical mechanisms governing the photoresponse, the performance and possible future paths of investigation. Full article

(This article belongs to the Special Issue Carbon Nanomaterials: Graphene, Nanoribbons and Quantum dots)

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11 pages, 2299 KiB

Open AccessArticle

Effects of Interfacial Passivation on the Electrical Performance, Stability, and Contact Properties of Solution Process Based ZnO Thin Film Transistors

by Liaojun Wan, Fuchao He, Yu Qin, Zhenhua Lin, Jie Su, Jingjing Chang and Yue Hao

Materials 2018, 11(9), 1761; https://doi.org/10.3390/ma11091761 - 18 Sep 2018

Cited by 20 | Viewed by 4275

Abstract

This paper reports low temperature solution processed ZnO thin film transistors (TFTs), and the effects of interfacial passivation of a 4-chlorobenzoic acid (PCBA) layer on device performance. It was found that the ZnO TFTs with PCBA interfacial modification layers exhibited a higher electron [...] Read more.

This paper reports low temperature solution processed ZnO thin film transistors (TFTs), and the effects of interfacial passivation of a 4-chlorobenzoic acid (PCBA) layer on device performance. It was found that the ZnO TFTs with PCBA interfacial modification layers exhibited a higher electron mobility of 4.50 cm² V⁻¹ s⁻¹ compared to the pristine ZnO TFTs with a charge carrier mobility of 2.70 cm² V⁻¹ s⁻¹. Moreover, the ZnO TFTs with interfacial modification layers could significantly improve device shelf-life stability and bias stress stability compared to the pristine ZnO TFTs. Most importantly, interfacial modification layers could also decrease the contact potential barrier between the source/drain electrodes and the ZnO films when using high work-function metals such as Ag and Au. These results indicate that high performance TFTs can be obtained with a low temperature solution process with interfacial modification layers, which strongly implies further potential for their applications. Full article

(This article belongs to the Special Issue Thin Film Fabrication and Surface Techniques)

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10 pages, 4002 KiB

Open AccessArticle

Acoustic Emissions in 3D Printed Parts under Mode I Delamination Test

by Claudia Barile, Caterina Casavola and Alberto Cazzato

Materials 2018, 11(9), 1760; https://doi.org/10.3390/ma11091760 - 18 Sep 2018

Cited by 14 | Viewed by 4671

Abstract

This paper applies an innovative approach based on the acoustic emission technique to monitor the delamination process of 3D parts. Fused deposition modelling (FDM) is currently one of the most widespread techniques for additive manufacturing of a solid object from a computer model. [...] Read more.

This paper applies an innovative approach based on the acoustic emission technique to monitor the delamination process of 3D parts. Fused deposition modelling (FDM) is currently one of the most widespread techniques for additive manufacturing of a solid object from a computer model. Fundamentally, this process is based on a layer-by-layer deposition of a fused filament. The FDM technique has evolved to the point where it can now be proposed, not only as a prototyping technique, but also as one applicable to direct manufacturing. Nonetheless, a deeper comprehension of mechanical behavior and its dependence on process parameters must include the determination of material properties as a function of the service load. In this work, the effects of extrusion temperature on inter-layer cohesion are studied using a method employing a double cantilever beam (DCB). The ASTM D5528 standard was used to determine the delamination energy, G_I. In addition, the acoustic emission technique was employed to follow the delamination process during testing. Finally, a Charge-Coupled Device (CCD) camera and a calibrated grid was employed to evaluate crack propagation during testing. Full article

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14 pages, 2044 KiB

Open AccessArticle

Perovskite Thin Film Consisting with One-Dimensional Nanowires

by Xinli Li, Yongchao Chen, Lihua Li and Jinliang Huang

Materials 2018, 11(9), 1759; https://doi.org/10.3390/ma11091759 - 18 Sep 2018

Cited by 17 | Viewed by 5726

Abstract

Organic-inorganic hybrid perovskite solar cells had attracted extensive attention due to their high-power conversion efficiency and low cost. The morphology and structure of the light absorption layer are crucially important for the device performance. The one-dimensional or two dimensional nano-structure perovskite material exhibits [...] Read more.

Organic-inorganic hybrid perovskite solar cells had attracted extensive attention due to their high-power conversion efficiency and low cost. The morphology and structure of the light absorption layer are crucially important for the device performance. The one-dimensional or two dimensional nano-structure perovskite material exhibits better optical and electrical properties than three-dimensional bulk perovskite. In this article, the perovskite CH₃NH₃PbI₃ thin films with one-dimensional nanowires structure were prepared while using the solution method with N,N-Dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) mixed solvent under atmospheric environment. During the perovskite thin films growth, the DMSO solvent as a structure directing agent played a guiding role in the formation of nanowires. The effects of DMSO solvent added ratio on the perovskite thin film structure, morphology, optical properties, and the device performance were studied. By changing the ratio of DMSO solvent added can effectively adjust the orientation order and optical properties of the nanowires perovskite thin films. The results showed that the best ratio of DMSO solvent added in the mixed solvent was 10%. The high order orientation of the perovskite thin film with nanowires forest was obtained. It showed the high optical absorption and electrical properties. The perovskite absorption layer presents ordered and dispersed nanowires forest; the device power conversation efficiency is increased by 50% when compared with the perovskite layer presents disordered nanowires. Full article

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13 pages, 1276 KiB

Open AccessArticle

Enrichment and Purification of Aucubin from Eucommia ulmoides Ionic Liquid Extract Using Macroporous Resins

by Xinyu Yang, Mengxia Wei, Hao Tian, Tingting Liu and Lei Yang

Materials 2018, 11(9), 1758; https://doi.org/10.3390/ma11091758 - 18 Sep 2018

Cited by 15 | Viewed by 3998

Abstract

Aiming to address the shortcomings of high-concentration ethanol or methanol extraction solutions that need to be diluted and concentrated prior to use in conventional macroporous resin adsorption approaches, an efficient approach for enrichment and purification of aucubin from the ionic liquid extraction solution [...] Read more.

Aiming to address the shortcomings of high-concentration ethanol or methanol extraction solutions that need to be diluted and concentrated prior to use in conventional macroporous resin adsorption approaches, an efficient approach for enrichment and purification of aucubin from the ionic liquid extraction solution of samaras of Eucommia ulmoides was proposed. Among the nine kinds of macroporous resins investigated, the HPD850 resin was found to be the most suitable. Equilibrium adsorption tests were investigated and found to be better fitted by the Langmuir isotherm model. After the dynamic tests on a column packed with HPD850, the optimum operational conditions were as follows: for the absorption process, an initial aucubin concentration of 9.87 mg/L, a sample volume of 13 bed volumes (BV), and a flow rate of 2 BV/h; for the water washing process, 5 BV of deionized water and a flow rate of 3 BV/h; for the ethanol desorption process, a 10–80% ethanol volume fraction as the eluent, 2 BV for each ethanol volume fraction, and a flow rate of 3 BV/h. The 40–80% ethanol volume fraction eluent was collected and concentrated to produce the final products, resulting in an aucubin purity and recovery of 79.41% and 72.92%, respectively. Full article

(This article belongs to the Section Smart Materials)

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13 pages, 2525 KiB

Open AccessArticle

Thermoelectric Nanocomposite Foams Using Non-Conducting Polymers with Hybrid 1D and 2D Nanofillers

by Mohammadmehdi Aghelinejad and Siu Ning Leung

Materials 2018, 11(9), 1757; https://doi.org/10.3390/ma11091757 - 18 Sep 2018

Cited by 14 | Viewed by 4781

Abstract

A facile processing strategy to fabricate thermoelectric (TE) polymer nanocomposite foams with non-conducting polymers is reported in this study. Multilayered networks of graphene nanoplatelets (GnPs) and multi-walled carbon nanotubes (MWCNTs) are deposited on macroporous polyvinylidene fluoride (PVDF) foam templates using a layer-by-layer (LBL) [...] Read more.

A facile processing strategy to fabricate thermoelectric (TE) polymer nanocomposite foams with non-conducting polymers is reported in this study. Multilayered networks of graphene nanoplatelets (GnPs) and multi-walled carbon nanotubes (MWCNTs) are deposited on macroporous polyvinylidene fluoride (PVDF) foam templates using a layer-by-layer (LBL) assembly technique. The open cellular structures of foam templates provide a platform to form segregated 3D networks consisting of one-dimensional (1D) and/or two-dimensional (2D) carbon nanoparticles. Hybrid nanostructures of GnP and MWCNT networks synergistically enhance the material system’s electrical conductivity. Furthermore, the polymer foam substrates possess high porosity to provide ultra-low thermal conductivity without compromising the electrical conductivity of the TE nanocomposites. With an extremely low GnP loading (i.e., ~1.5 vol.%), the macroporous PVDF nanocomposites exhibit a thermoelectric figure-of-merit of ~10⁻³. To the best of our knowledge, this ZT value is the highest value reported for organic TE materials using non-conducting polymers and MWCNT/GnP nanofillers. The proposed technique represents an industrially viable approach to fabricate organic TE materials with enhanced energy conversion efficiencies. The current study demonstrates the potential to develop light-weight, low-cost, and flexible TE materials for green energy generation. Full article

(This article belongs to the Special Issue New Trends in Polymeric Foams)

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