Editorial

3 pages, 168 KiB

Open AccessEditorial

Synthesis, Characterization and Application of Hybrid Composites

by Ignazio Blanco

Appl. Sci. 2020, 10(16), 5456; https://doi.org/10.3390/app10165456 - 07 Aug 2020

Cited by 1 | Viewed by 1338

In the last century, polymers have dominated the materials market, and in the later part of the 20th century, the possibility to further improve their properties and expand their applications was explored by combining polymers with reinforcing elements [...] Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

Research

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20 pages, 2319 KiB

Open AccessArticle

Layer-by-Layer Deposition of Copper and Phosphorus Compounds to Develop Flame-Retardant Polyamide 6/Montmorillonite Hybrid Composites

by Tomasz M. Majka, Monika Witek, Paulina Radzik, Karolina Komisarz, Agnieszka Mitoraj and Krzysztof Pielichowski

Appl. Sci. 2020, 10(14), 5007; https://doi.org/10.3390/app10145007 - 21 Jul 2020

Cited by 7 | Viewed by 2607

Abstract

Nowadays, increasing attention is devoted to the search for polymeric composite materials that are characterized by reduced flammability. In this work, the layer-by-layer (LbL) technique was applied to form multilayered protective coatings for polyamide 6/montmorillonite (PA6/MMT) hybrid nanocomposites. This time, the double layers [...] Read more.

Nowadays, increasing attention is devoted to the search for polymeric composite materials that are characterized by reduced flammability. In this work, the layer-by-layer (LbL) technique was applied to form multilayered protective coatings for polyamide 6/montmorillonite (PA6/MMT) hybrid nanocomposites. This time, the double layers LbL deposition was used in order to improve the thermal properties or flammability of PA6 materials. Our goal was to check how five, 10, and 15 triple-layer deposition onto the surface of PA6 and PA6/MMT composites influenced these relevant properties. For this reason, disodium H-phosphonate, sodium montmorillonite, and iodo-bis(triphenylphosphino)copper were used for polyelectrolyte solution preparation. It was found that the LbL method could be successfully used to improve the flammability characteristics of polyamide 6-based composites. Nevertheless, the deposition of the copper complex should be combined with other flame retardants—preferentially containing phosphorus—which enable synergistic effects to occur. Moreover, microscopic observations confirmed that the surfaces on which the formation of interwoven fibrous crystal structures was observed had a tendency to protect the entire material against the destructive effects of heat, contributing, among other things, to reduce the maximum point of heat release rate (PHRR). Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

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12 pages, 5093 KiB

Open AccessArticle

Study of Interfacial Adhesion between Nickel-Titanium Shape Memory Alloy and a Polymer Matrix by Laser Surface Pattern

by Sneha Samal, Ondřej Tyc, Luděk Heller, Petr Šittner, Monika Malik, Pankaj Poddar, Michelina Catauro and Ignazio Blanco

Appl. Sci. 2020, 10(6), 2172; https://doi.org/10.3390/app10062172 - 23 Mar 2020

Cited by 20 | Viewed by 3747

Abstract

The aim of this article is to investigate the interfacial adhesion of Ni-Ti shape memory alloy with a polymer matrix of Poly (methyl methacrylate) (PMMA). The surface pattern on Ni-Ti plates was channeled by a solid state laser machine. The laser machine allows [...] Read more.

The aim of this article is to investigate the interfacial adhesion of Ni-Ti shape memory alloy with a polymer matrix of Poly (methyl methacrylate) (PMMA). The surface pattern on Ni-Ti plates was channeled by a solid state laser machine. The laser machine allows for creating channels on the Ni-Ti surface for infiltration of the PMMA matrix, which could be attached as an intra-surface locking pattern to the Ni-Ti surface. The influence of the PMMA matrix on the surface of the NiTi plate was evaluated by thermomechanical analysis (TMA) and dynamic mechanical analysis (DMA). The surface characterization was carried out by an optical microscope on the PMMA/NiTi composite after mechanical testing. During mechanical testing, the polymer displays the multiple cracks in the longitudinal direction that result in slipping and fracture. TMA and DMA analyses were performed on the Ni-Ti- and PMMA-coated Ni-Ti ribbon to observe elasticity and the storage modulus for both samples. Better adhesion than 80 % was observed in the Ni-Ti surface, in the laser surface pattern, in comparison to the free plain surface. However, the polymer acts as mechanical backing that caused a reduction in the shape-memory properties of the composite material. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

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16 pages, 6252 KiB

Open AccessArticle

Enhanced Proliferation and Differentiation of Human Mesenchymal Stem Cell-laden Recycled Fish Gelatin/Strontium Substitution Calcium Silicate 3D Scaffolds

by Chun-Ta Yu, Fu-Ming Wang, Yen-Ting Liu, Alvin Kai-Xing Lee, Tsung-Li Lin and Yi-Wen Chen

Appl. Sci. 2020, 10(6), 2168; https://doi.org/10.3390/app10062168 - 22 Mar 2020

Cited by 10 | Viewed by 2994

Abstract

Cell-encapsulated bioscaffold is a promising and novel method to allow fabrication of live functional organs for tissue engineering and regenerative medicine. However, traditional fabrication methods of 3D scaffolds and cell-laden hydrogels still face many difficulties and challenges. This study uses a newer 3D [...] Read more.

Cell-encapsulated bioscaffold is a promising and novel method to allow fabrication of live functional organs for tissue engineering and regenerative medicine. However, traditional fabrication methods of 3D scaffolds and cell-laden hydrogels still face many difficulties and challenges. This study uses a newer 3D fabrication technique and the concept of recycling of an unutilized resource to fabricate a novel scaffold for bone tissue engineering. In this study, fish-extracted gelatin was incorporated with bioactive ceramic for bone tissue engineering, and with this we successfully fabricated a novel fish gelatin methacrylate (FG) polymer hydrogel mixed with strontium-doped calcium silicate powder (FGSr) 3D scaffold via photo-crosslinking. Our results indicated that the tensile strength of FGSr was almost 2.5-fold higher as compared to FG thus making it a better candidate for future clinical applications. The in-vitro assays illustrated that the FGSr scaffolds showed good biocompatibility with human Wharton jelly-derived mesenchymal stem cells (WJMSC), as well as enhancing the osteogenesis differentiation of WJMSC. The WJMSC-laden FGSr 3D scaffolds expressed a higher degree of alkaline phosphatase activity than those on cell-laden FG 3D scaffolds and this result was further proven with the subsequent calcium deposition results. Therefore, these results showed that 3D-printed cell-laden FGSr scaffolds had enhanced mechanical property and osteogenic-related behavior that made for a more suitable candidate for future clinical applications. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

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12 pages, 3856 KiB

Open AccessFeature PaperArticle

Anti-Frothing Effect of Poultry Feathers in Bio-Based, Polycondensation-Type Thermoset Composites

by Markus Brenner, Crisan Popescu and Oliver Weichold

Appl. Sci. 2020, 10(6), 2150; https://doi.org/10.3390/app10062150 - 21 Mar 2020

Cited by 8 | Viewed by 2514

Abstract

The formation of polycondensation-type thermoset resins from natural reactants such as citric and glutaric acid, as well as 1,3-propanediol and glycerol, was studied. Monitoring the mass loss by thermogravimetric analysis (TGA) allowed the rate constants of the esterification to be calculated, which were [...] Read more.

The formation of polycondensation-type thermoset resins from natural reactants such as citric and glutaric acid, as well as 1,3-propanediol and glycerol, was studied. Monitoring the mass loss by thermogravimetric analysis (TGA) allowed the rate constants of the esterification to be calculated, which were in the order of 7·10⁻⁵ s⁻¹ for glutaric acid and approximately twice as high for citric acid. However, the combination citric acid/glycerol was previously reported to froth up at high conversions, giving rise to foams, which makes the preparation of compact engineering composites challenging. In light of this, we observed that shredded poultry feathers not only increased the conversion and the reaction rate of the combination citric acid/glycerol, but increasing the amount of feathers continuously decreased the number of visible bubbles. The addition of 20 wt% of feathers completely prevented the previously reported frothing and gave rise to compact materials that were macroscopically free of defects. Besides this, the addition of feathers also improved the fire-retardant properties. The tensile properties of the first specimens are still rather low (σ = 11.6 N/mm², E = 750 N/mm²), but the addition of poultry feathers opens a new path for green thermoset resins. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

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11 pages, 3875 KiB

Open AccessFeature PaperArticle

FT-IR Characterization of Antimicrobial Hybrid Materials through Sol-Gel Synthesis

by Michelina Catauro, Simona Piccolella and Cristina Leonelli

Appl. Sci. 2020, 10(3), 1180; https://doi.org/10.3390/app10031180 - 10 Feb 2020

Cited by 9 | Viewed by 2896

Abstract

Silica/polycaprolactone and titania/polycaprolactone hybrid organic/inorganic amorphous composites were prepared via a sol-gel method starting from a multi-element solution containing tetramethyl orthosilicate (TMOS) or titanium butoxide (TBT), polycaprolactone (PCL), water and methylethylketone (MEK). The molecular structure of the crosslinked network was based on the [...] Read more.

Silica/polycaprolactone and titania/polycaprolactone hybrid organic/inorganic amorphous composites were prepared via a sol-gel method starting from a multi-element solution containing tetramethyl orthosilicate (TMOS) or titanium butoxide (TBT), polycaprolactone (PCL), water and methylethylketone (MEK). The molecular structure of the crosslinked network was based on the presence of the hydrogen bonds between organic/inorganic elements as confirmed by Fourier Transform Infra-Red (FT-IR) analysis. In particular, the structure of crosslinked network was realized by hydrogen bonds between the X-OH (X = Si or Ti) group (H donator) in the sol-gel intermediate species and ester groups (H-acceptors) in the repeating units of the polymer. The morphology of the hybrid materials; pore size distribution, elemental homogeneity and surface features, was studied by scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and by atomic force microscopy (AFM). The bioactivity of the synthesized hybrid materials was confirmed by observing the formation of a layer of hydroxyapatite (HAP) on the surface of the samples soaked in a simulated body fluid. The antimicrobial behavior of synthetized hybrids was also assessed against Escherichia coli bacteria. In conclusion, the prepared hybrid materials are proposed for use as future bone implants. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

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15 pages, 4204 KiB

Open AccessFeature PaperArticle

Thermo-Mechanical Properties of PLA/Short Flax Fiber Biocomposites

by Laura Aliotta, Vito Gigante, Maria-Beatrice Coltelli, Patrizia Cinelli, Andrea Lazzeri and Maurizia Seggiani

Appl. Sci. 2019, 9(18), 3797; https://doi.org/10.3390/app9183797 - 11 Sep 2019

Cited by 63 | Viewed by 4265

Abstract

In this work, biocomposites based on poly(lactic acid) (PLA) and short flax fibers (10–40 wt.%) were produced by extrusion and characterized in terms of thermal, mechanical, morphological, and thermo-mechanical properties. Analytical models were adopted to predict the tensile properties (stress at break and [...] Read more.

In this work, biocomposites based on poly(lactic acid) (PLA) and short flax fibers (10–40 wt.%) were produced by extrusion and characterized in terms of thermal, mechanical, morphological, and thermo-mechanical properties. Analytical models were adopted to predict the tensile properties (stress at break and elastic modulus) of the composites, and to assess the matrix/fiber interface adhesion. The resulting composites were easily processable by extrusion and injection molding up to 40 wt.% of flax fibers. It was observed that despite any superficial treatment of fibers, the matrix/fiber adhesion was found to be sufficiently strong to ensure an efficient load transfer between the two components obtaining composites with good mechanical properties. The best mechanical performance, in terms of break stress (66 MPa), was obtained with 20 wt.% of flax fibers. The flax fiber acted also as nucleating agent for PLA, leading to an increment of the composite stiffness and, at 40 wt.% of flax fibers, improving the elastic modulus decay near the PLA glass transition temperature. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

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15 pages, 4828 KiB

Open AccessCommunication

Shape Memory Effect in Micro-Sized Shape Memory Polymer Composite Chains

by Xin Lan, Weimin Huang and Jinsong Leng

Appl. Sci. 2019, 9(14), 2919; https://doi.org/10.3390/app9142919 - 22 Jul 2019

Cited by 7 | Viewed by 3366

Abstract

Since the shape memory effect (SME) has been confirmed in micron and submicron sized polyurethane (PU) shape memory polymer (SMP), it might be used in novel micro/nano devices even for surgery/operation inside a single cell. In this study, micron sized protrusive PU SMP [...] Read more.

Since the shape memory effect (SME) has been confirmed in micron and submicron sized polyurethane (PU) shape memory polymer (SMP), it might be used in novel micro/nano devices even for surgery/operation inside a single cell. In this study, micron sized protrusive PU SMP composite chains are fabricated via mixing ferromagnetic nickel micro powders with PU SMP/dimethylformamide solution and then cured under a low magnetic field. Depending on the amount of nickel content, vertical protrusive chains with a diameter from 10 to 250 µm and height from 200 to 1500 µm are obtained. The SME in these chains is investigated to confirm the SME in SMP composites at microscale. An array of such protrusive chains may be utilized to obtain re-configurable surface patterns in a simple manner for applications, such as remarkable change in wetting and friction ability. Finally, its potential applications for micro electro mechanical systems (MEMS) and biomedical device are proposed. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

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9 pages, 3518 KiB

Open AccessArticle

Composite Films of Polydimethylsiloxane and Micro-Graphite with Tunable Optical Transmittance

by Qi Wang, Bin Sheng, He Wu, Yuanshen Huang, Dawei Zhang and Songlin Zhuang

Appl. Sci. 2019, 9(12), 2402; https://doi.org/10.3390/app9122402 - 13 Jun 2019

Cited by 10 | Viewed by 3191

Abstract

In this paper we introduce a polydimethylsiloxane (PDMS) composite fabricated using a simple production process and demonstrate the optical transmittance properties of this composite in the 300–1000 nm wavelength region. We control the material’s transmittance by varying the microcrystalline graphite powder concentration or [...] Read more.

In this paper we introduce a polydimethylsiloxane (PDMS) composite fabricated using a simple production process and demonstrate the optical transmittance properties of this composite in the 300–1000 nm wavelength region. We control the material’s transmittance by varying the microcrystalline graphite powder concentration or the composite film’s thickness. In addition, we tailor the specimens into various trapezoidal shapes and load these specimens by mechanically stretching them in the direction perpendicular to both their base lines and their top lines. The advantage of this method is that a wide range of transmittance properties can be obtained for a given specimen. Furthermore, samples with different trapezoidal shapes have different transmittance tuning capabilities. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

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15 pages, 4450 KiB

Open AccessArticle

Synthesis and Catalytic Activity of Activated Carbon Supported Sulfonated Cobalt Phthalocyanine in the Preparation of Dimethyl Disulfide

by Zhiliang Cheng, Mingxing Dai, Xuejun Quan, Shuo Li, Daomin Zheng, Yaling Liu and Rujie Yao

Appl. Sci. 2019, 9(1), 124; https://doi.org/10.3390/app9010124 - 31 Dec 2018

Cited by 8 | Viewed by 4736

Abstract

The Merox process was widely applied in the fine chemical industry to convert mercaptans into disulfides by oxidation with oxygen, including dimethyl disulfide (DMDS). In this paper, a new activated carbon (AC)-supported sulfonated cobalt phthalocyanine (AC-CoPcS) catalyst was prepared through the chemical linkage [...] Read more.

The Merox process was widely applied in the fine chemical industry to convert mercaptans into disulfides by oxidation with oxygen, including dimethyl disulfide (DMDS). In this paper, a new activated carbon (AC)-supported sulfonated cobalt phthalocyanine (AC-CoPcS) catalyst was prepared through the chemical linkage of ethylenediamine between them. UV−VIS, FT-IR, BET, and XPS were used to characterize the structure of the new catalyst. Then AC-CoPcS was applied to catalyze sodium methylmercaptide (SMM) oxidation for the preparation of DMDS. The effect of process parameters, such as reaction time, catalyst dosage, reaction temperature, and oxygen pressure on SMM conversion per pass (CPP_SMM), yield (Yield_DMDS), and purity of the DMDS (Purity_DMDS) product were investigated to evaluate the catalytic performance of AC-CoPcS. The new supported catalyst exhibits better catalytic performance than the commercial one and can be properly reused four times to obtain CPP_SMM and Yield_DMDS higher than 90% and 70%. Under the optimum experimental conditions, the CPP_SMM and Yield_DMDS could reach as high as 98.7% and 86.8%, respectively, and the purity of the DMDS product is as high as 99.8%. This new supported catalyst exhibits good industrial application prospects. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

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Review

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19 pages, 8723 KiB

Open AccessFeature PaperReview

Magneto-Rheological Elastomer Composites. A Review

by Sneha Samal, Marcela Škodová, Lorenzo Abate and Ignazio Blanco

Appl. Sci. 2020, 10(14), 4899; https://doi.org/10.3390/app10144899 - 17 Jul 2020

Cited by 37 | Viewed by 4080

Abstract

Magneto-rheological elastomer (MRE) composites belong to the category of smart materials whose mechanical properties can be governed by an external magnetic field. This behavior makes MRE composites largely used in the areas of vibration dampers and absorbers in mechanical systems. MRE composites are [...] Read more.

Magneto-rheological elastomer (MRE) composites belong to the category of smart materials whose mechanical properties can be governed by an external magnetic field. This behavior makes MRE composites largely used in the areas of vibration dampers and absorbers in mechanical systems. MRE composites are conventionally constituted by an elastomeric matrix with embedded filler particles. The aim of this review is to present the most outstanding advances on the rheological performances of MRE composites. Their distribution, arrangement, wettability within an elastomer matrix, and their contribution towards the performance of mechanical response when subjected to a magnetic field are evaluated. Particular attention is devoted to the understanding of their internal micro-structures, filler–filler adhesion, filler–matrix adhesion, and viscoelastic behavior of the MRE composite under static (valve), compressive (squeeze), and dynamic (shear) mode. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

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16 pages, 821 KiB

Open AccessReview

A Short Review on the Effect of Surfactants on the Mechanico-Thermal Properties of Polymer Nanocomposites

by Ahmad Adlie Shamsuri and Siti Nurul Ain Md. Jamil

Appl. Sci. 2020, 10(14), 4867; https://doi.org/10.3390/app10144867 - 16 Jul 2020

Cited by 28 | Viewed by 3014

Abstract

The recent growth of nanotechnology consciousness has enhanced the attention of researchers on the utilization of polymer nanocomposites. Nanocomposite have widely been made by using synthetic, natural, biosynthetic, and synthetic biodegradable polymers with nanofillers. Nanofillers are normally modified with surfactants for increasing the [...] Read more.

The recent growth of nanotechnology consciousness has enhanced the attention of researchers on the utilization of polymer nanocomposites. Nanocomposite have widely been made by using synthetic, natural, biosynthetic, and synthetic biodegradable polymers with nanofillers. Nanofillers are normally modified with surfactants for increasing the mechanico-thermal properties of the nanocomposites. In this short review, two types of polymer nanocomposites modified by surfactants are classified, specifically surfactant-modified inorganic nanofiller/polymer nanocomposites and surfactant-modified organic nanofiller/polymer nanocomposites. Moreover, three types of surfactants, specifically non-ionic, anionic, and cationic surfactants that are frequently used to modify the nanofillers of polymer nanocomposites are also described. The effect of surfactants on mechanico-thermal properties of the nanocomposites is shortly reviewed. This review will capture the interest of polymer composite researchers and encourage the further enhancement of new theories in this research field. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

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17 pages, 46416 KiB

Open AccessReview

Recent Progress in Hybrid Solar Cells Based on Solution-Processed Organic and Semiconductor Nanocrystal: Perspectives on Device Design

by Sihang Xie, Xueqi Li, Yasi Jiang, Rourou Yang, Muyi Fu, Wanwan Li, Yiyang Pan, Donghuan Qin, Wei Xu and Lintao Hou

Appl. Sci. 2020, 10(12), 4285; https://doi.org/10.3390/app10124285 - 22 Jun 2020

Cited by 9 | Viewed by 4258

Abstract

Solution-processed hybrid solar cells have been well developed in the last twenty years due to the advantages of low cost, low material-consuming and simple fabricating technology. However, the performance, stability and film quality of hybrid solar cells need to be further improved for [...] Read more.

Solution-processed hybrid solar cells have been well developed in the last twenty years due to the advantages of low cost, low material-consuming and simple fabricating technology. However, the performance, stability and film quality of hybrid solar cells need to be further improved for future commercial application (with a lifetime up to 20 years and power conversion efficiency higher than 15%). By combining the merits of organic polymers and nanocrystals (NC), the reasonable design of interface engineering and device architecture, the performance coupled with stability of hybrid solar cells can be significantly improved. This review gives a brief conclusive introduction to the progress on solution-processed organic/inorganic semiconductor hybrid solar cells, including a summary of the development of hybrid solar cells in recent years, the strategy of hybrid solar cells with different structures and the incorporation of new organic hole transport materials with new insight into device processing for high efficiency. This paper also puts forward some suggestions and guidance for the future development of high-performance NC-based photovoltaics. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Hybrid Composites)

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