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Green Composites: Preparation, Properties, and Applications

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (31 May 2019) | Viewed by 42113

Special Issue Editor

Special Issue Information

Dear Colleagues,

Petrochemical-based plastics and synthetic thermoset composites have been increasingly used in all sectors, from home-products and toys to automotive/aerospace, to the medical and agro-food packaging industry, and so on. This is because of their large availability at relatively low costs and because of their good mechanical and thermal properties. However, an increased use of synthetic polymers has led to serious ecological problems due to their total non-biodegradability. Furthermore, recycling these materials is not always possible and most of the time is not economically convenient. Therefore, several thousands of tons of goods, made of plastic materials, are land-filled, every year increasing the problem of municipal waste disposal. The growing environmental awareness and the decline in oil resources leads to the adoption of eco-friendly solutions and is disconnected from the use of petroleum and its derivatives. Green composites from renewable resources are being increasingly studied because of their potential to provide benefits to companies, natural environments, and end-customers. Although the complete replacement of oil-based polymers and composites with ecofriendly materials is impossible to achieve, the use of green composites, in which an increasing percentage of synthetic material is replaced by natural ones, or in which eco-compatible reinforcements are used, should be the future.

Prof. Dr. Ignazio Blanco
Guest Editor

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Keywords

  • green-composites
  • natural fibers
  • biopolymers
  • lignin-based composites
  • PLA, PEG
  • bio-based composites

Published Papers (9 papers)

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Research

13 pages, 10741 KiB  
Article
Effects of Filler Distribution on Magnetorheological Silicon-Based Composites
by Sneha Samal, Marcela Škodová and Ignazio Blanco
Materials 2019, 12(18), 3017; https://doi.org/10.3390/ma12183017 - 18 Sep 2019
Cited by 32 | Viewed by 2926
Abstract
The smart materials subclass of magnetorheological elastomer (MRE) composites is presented in this work, which aimed to investigate the influence of filler distribution on surface morphology. Iron particles with sizes ranging from 20 to 150 µm were incorporated into the elastomer matrix and [...] Read more.
The smart materials subclass of magnetorheological elastomer (MRE) composites is presented in this work, which aimed to investigate the influence of filler distribution on surface morphology. Iron particles with sizes ranging from 20 to 150 µm were incorporated into the elastomer matrix and a 30% volume fraction (V%) was chosen as the optimal quantity for the filler amount in the elastomer composite. The surface morphology of MRE composites was examined by 3D micro-computed tomography (µCT) and scanning electron microscopy (SEM) techniques. Isotropic and anisotropic distributions of the iron particles were estimated in the magnetorheological elastomer composites. The filler particle distribution at various heights of the MRE composites was examined. The isotropic distribution of filler particles was observed without any influence from the magnetic field during sample preparation. The anisotropic arrangement of iron fillers within the MRE composites was observed in the presence of a magnetic field during fabrication. It was shown that the linear arrangement of the iron particle chain induced magnetization within the composite. Simulation analysis was also performed to predict the particle distribution of magnetization in the MREs and make a comparison with the experimental observations. Full article
(This article belongs to the Special Issue Green Composites: Preparation, Properties, and Applications)
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12 pages, 2480 KiB  
Article
VOC Emissions from Spruce Strands and Hemp Shive: In Search for a Low Emission Raw Material for Bio-Based Construction Materials
by Tereza Adamová, Jaromír Hradecký and Marek Prajer
Materials 2019, 12(12), 2026; https://doi.org/10.3390/ma12122026 - 24 Jun 2019
Cited by 20 | Viewed by 3657
Abstract
Volatile organic compounds (VOCs) reduce indoor air quality. They are associated with negative effects on human health and wellbeing. In terms of legislation requirements and consumer pressure, VOCs from engineered wood materials are reduced due to use of water based additives and adhesives [...] Read more.
Volatile organic compounds (VOCs) reduce indoor air quality. They are associated with negative effects on human health and wellbeing. In terms of legislation requirements and consumer pressure, VOCs from engineered wood materials are reduced due to use of water based additives and adhesives in their formulation. Therefore, the main source of VOCs remains the raw material—the wood itself. Alternatives to wood strands, annual plant materials, are tested nowadays due to their advantages: The short cycle; the raw material is sourced naturally and can be produced more sustainably; and faster sequestering atmospheric carbon. The aim of this work was to investigate volatile organic compounds emitted from untreated and chemically treated hemp shive and compare the emission characteristics to soft wood strands. Simple, yet effective chemical treatments, like tartaric acid, citric acid and sodium bicarbonate were used in order to reduce VOC emissions. Gas chromatography-mass spectrometry (GC-MS) combined with headspace solid-phase microextraction (HS-SPME) was used to analyse the volatile compounds emissions. Specific VOCs like acetic acid; Benzaldehyde; hexanal, α-, β-pinenes; limonene and camphene were monitored before and after the treatments. Non-target screening was performed to identify the most responsible compound for differentiation of samples according to their treatments. Comparing untreated samples, spruce strands showed highest amounts of total VOCs, while untreated hemp shive showed the lowest. Further, due to the chemical modification of hemp woody core components, such as hemicelluloses, lignin, and extractives, the key VOCs showed significant changes leading to an increase in the amount of total emissions. Full article
(This article belongs to the Special Issue Green Composites: Preparation, Properties, and Applications)
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11 pages, 2423 KiB  
Article
Drug Release of Hybrid Materials Containing Fe(II)Citrate Synthesized by Sol-Gel Technique
by Michelina Catauro, Elisabetta Tranquillo, Federico Barrino, Ignazio Blanco, Francesco Dal Poggetto and Daniele Naviglio
Materials 2018, 11(11), 2270; https://doi.org/10.3390/ma11112270 - 14 Nov 2018
Cited by 37 | Viewed by 3939
Abstract
The use of oral iron integration is commonly recommended for the treatment of iron deficiency, nevertheless the diagnosis and treatment of this disease could clearly be improved. The aim of this work was the synthesis of therapeutic systems, iron (II) based, by sol-gel [...] Read more.
The use of oral iron integration is commonly recommended for the treatment of iron deficiency, nevertheless the diagnosis and treatment of this disease could clearly be improved. The aim of this work was the synthesis of therapeutic systems, iron (II) based, by sol-gel method. In an SiO2 matrix, we embedded different weight percentages of polyethylene glycol (PEG6, 12, 24 wt%) and ferrous citrate (Fe(II)C5, 10, 15 wt%) for drug delivery applications. Fourier Transform Infrared (FTIR) spectroscopy was used to study the interactions among different components in the hybrid materials. Release kinetics in a simulated body fluid (SBF) were investigated and the amount of Fe2+ released was detected by Ultraviolet–Visible spectroscopy (UV-VIS) after reaction with ortho-phenantroline. Furthermore, the biological characterization was carried out. The bioactivity of the synthesized hybrid materials was evaluated by the formation of a layer of hydroxyapatite on the surface of samples soaked in SBF using FTIR spectroscopy. Finally, also, the potential antibacterial properties of the different materials against two different bacteria, E. coli and P. aeruginosa, were investigated. Full article
(This article belongs to the Special Issue Green Composites: Preparation, Properties, and Applications)
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13 pages, 3179 KiB  
Article
Preparation of γ-Divinyl-3-Aminopropyltriethoxysilane Modified Lignin and Its Application in Flame Retardant Poly(lactic acid)
by Yan Song, Xu Zong, Nan Wang, Ning Yan, Xueying Shan and Jinchun Li
Materials 2018, 11(9), 1505; https://doi.org/10.3390/ma11091505 - 22 Aug 2018
Cited by 36 | Viewed by 4035
Abstract
Lignin can be a candidate as a charring agent applied in halogen-free flame retardant polymers, and incorporation of silicon and nitrogen elements in lignin can benefit to enhancing its thermal stability and charring ability. In the present work, wheat straw alkali lignin (Lig) [...] Read more.
Lignin can be a candidate as a charring agent applied in halogen-free flame retardant polymers, and incorporation of silicon and nitrogen elements in lignin can benefit to enhancing its thermal stability and charring ability. In the present work, wheat straw alkali lignin (Lig) was modified to incorporate silicon and nitrogen elements by γ-divinyl-3-aminopropyltriethoxysilane, and the modified lignin (CLig) was combined with ammonium polyphosphate (APP) as intumescent flame retardant to be applied in poly(Lactic acid) (PLA). The flame retardancy, combustion behavior and thermal stability of PLA composites were studied by the limited oxygen index (LOI), vertical burning testing (UL-94), cone calorimetry testing (CCT) and thermogravimetric analysis (TGA), respectively. The results showed a significant synergistic effect between CLig and APP in flame retarded PLA (PLA/APP/CLig) occured, and the PLA/APP/CLig had better flame retardancy. CCT data analysis revealed that CLig and APP largely reduced the peak heat release rate (PHRR) and total heat release rate (THR) of PLA, indicating their effectiveness in decreasing the combustion of PLA. TGA results exhibited that APP and CLig improved the thermal stability of PLA at high temperature. The analysis of morphology and structure of residual char indicated that a continuous, compact and intumescent char layer on the material surface formed during firing, and had higher graphitization degree. Mechanical properties data showed that PLA/APP/CLig had higher tensile strength as well as elongation at break. Full article
(This article belongs to the Special Issue Green Composites: Preparation, Properties, and Applications)
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13 pages, 3877 KiB  
Article
Polylactide (PLA) Filaments a Biobased Solution for Additive Manufacturing: Correlating Rheology and Thermomechanical Properties with Printing Quality
by Gianluca Cicala, Davide Giordano, Claudio Tosto, Giovanni Filippone, Antonino Recca and Ignazio Blanco
Materials 2018, 11(7), 1191; https://doi.org/10.3390/ma11071191 - 11 Jul 2018
Cited by 123 | Viewed by 7410
Abstract
Three commercial filaments for Fused Deposition Modeling (FDM) were selected to study the influence of polymer formulation on the printing quality and mechanical properties of FDM specimens. The three filaments were all based on polylactic acid (PLA) as the matrix, and they are [...] Read more.
Three commercial filaments for Fused Deposition Modeling (FDM) were selected to study the influence of polymer formulation on the printing quality and mechanical properties of FDM specimens. The three filaments were all based on polylactic acid (PLA) as the matrix, and they are sold as PLA filaments. The printing quality was tested by printing one complex shape with overhang features. The marked shear thinning behavior for two filaments was observed by rheology. The filaments were also studied by scanning electron microscopy and thermogravimetric analysis (TGA) to unveil their composition. The filaments with the best printing quality showed the presence of mineral fillers, which explained the melt behavior observed by rheology. The tensile testing confirmed that the filled PLA was the best-performing filament both in terms of printing quality and thermomechanical performance, with a p-value = 0.106 for the tensile modulus, and a p-value = 0.615 for the ultimate tensile strength. Full article
(This article belongs to the Special Issue Green Composites: Preparation, Properties, and Applications)
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13 pages, 5056 KiB  
Article
Effects of Organic Modification of Montmorillonite on the Properties of Hydroxypropyl Di-Starch Phosphate Films Prepared by Extrusion Blowing
by Yang Qin, Wentao Wang, Hui Zhang, Yangyong Dai, Hanxue Hou and Haizhou Dong
Materials 2018, 11(7), 1064; https://doi.org/10.3390/ma11071064 - 23 Jun 2018
Cited by 11 | Viewed by 3079
Abstract
The knowledge gained from starch-nanocomposite-film research has not been fully applied commercially because of the lack of appropriate industrial processing techniques for nanofillers and starch films. Three organically modified montmorillonites (OMMTs) were prepared using a semidry kneading method. The effects of the OMMTs [...] Read more.
The knowledge gained from starch-nanocomposite-film research has not been fully applied commercially because of the lack of appropriate industrial processing techniques for nanofillers and starch films. Three organically modified montmorillonites (OMMTs) were prepared using a semidry kneading method. The effects of the OMMTs on the structures and properties of starch nanocomposite films, prepared by extrusion blowing, were investigated. The X-ray diffraction (XRD) analysis results revealed that the OMMTs with various quaternary ammonium salts possessed differing layer structures and d-space values. The results of the XRD and Fourier-transform infrared spectroscopy (FT-IR) showed that the starch–OMMT interaction resulted in a structural change, namely the starch–OMMT films possessed a balanced exfoliated and intercalated nanostructure, while the starch–MMT film possessed an exfoliated nanostructure with non-intercalated montmorillonite (MMT). The results of the solid-state nuclear magnetic resonance (NMR) analysis suggested that the starch-OMMT nanocomposite possessed comparatively large quantities of single-helix structures and micro-ordered amorphous regions. The starch–OMMT films exhibited good tensile strength (TS) (maximum of 6.09 MPa) and water barrier properties (minimum of 3.48 × 10−10 g·m·m−2·s−1·Pa−1). This study indicates that the addition of OMMTs is a promising strategy to improve the properties of starch films. Full article
(This article belongs to the Special Issue Green Composites: Preparation, Properties, and Applications)
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16 pages, 5056 KiB  
Article
Effect of Babassu Natural Filler on PBAT/PHB Biodegradable Blends: An Investigation of Thermal, Mechanical, and Morphological Behavior
by Vinicius C. Beber, Silvio De Barros, Mariana D. Banea, Markus Brede, Laura H. De Carvalho, Ron Hoffmann, Anna Raffaela M. Costa, Elieber B. Bezerra, Ingridy D. S. Silva, Katharina Haag, Katharina Koschek and Renate M. R. Wellen
Materials 2018, 11(5), 820; https://doi.org/10.3390/ma11050820 - 16 May 2018
Cited by 29 | Viewed by 4850
Abstract
Blending of biodegradable polymers in combination with low-price organic fillers has proven to be a suitable approach to produce cost-effective composites in order to address pollution issues and develop products with superior mechanical properties. In the present research work PBAT/PHB/Babassu composites with 25, [...] Read more.
Blending of biodegradable polymers in combination with low-price organic fillers has proven to be a suitable approach to produce cost-effective composites in order to address pollution issues and develop products with superior mechanical properties. In the present research work PBAT/PHB/Babassu composites with 25, 50, and 75% of each polymer and 20% of Babassu were produced by melting extrusion. Their thermal, mechanical, and morphological behavior was investigated by differential scanning calorimetry (DSC), tensile testing, and scanning electron microscopy (SEM). Blending PBAT with PHB inhibited the crystallization of both polymers whereas adding Babassu did not significantly change their melting behaviour. Incorporation of Babassu reduced the tensile strength of its respective blends between 4.8 and 32.3%, and elongation at break between 26.0 and 66.3%. PBAT as highly ductile and low crystalline polymer may be seen as a crystallization tool control for PHB as well as a plasticizer to PBAT/PHB blends and PBAT/PHB/Babassu composites. As PBAT content increases: (i) elongation at break increases and (ii) surface fracture becomes more refined indicating the presence of more energy dissipation mechanisms. As PBAT/PHB/Babassu composites are biodegradable, environmental friendly, and cost effective, products based on these compounds have a great potential since their mechanical properties such as ductility, stiffness, and tensile strength are still suitable for several applications even at lower temperatures (−40 °C). Full article
(This article belongs to the Special Issue Green Composites: Preparation, Properties, and Applications)
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14 pages, 14357 KiB  
Article
Injection Molding and Mechanical Properties of Bio-Based Polymer Nanocomposites
by Maria Chiara Mistretta, Luigi Botta, Marco Morreale, Sebastiano Rifici, Manuela Ceraulo and Francesco Paolo La Mantia
Materials 2018, 11(4), 613; https://doi.org/10.3390/ma11040613 - 17 Apr 2018
Cited by 15 | Viewed by 4540
Abstract
The use of biodegradable/bio-based polymers is of great importance in addressing several issues related to environmental protection, public health, and new, stricter legislation. Yet some applications require improved properties (such as barrier or mechanical properties), suggesting the use of nanosized fillers in order [...] Read more.
The use of biodegradable/bio-based polymers is of great importance in addressing several issues related to environmental protection, public health, and new, stricter legislation. Yet some applications require improved properties (such as barrier or mechanical properties), suggesting the use of nanosized fillers in order to obtain bio-based polymer nanocomposites. In this work, bionanocomposites based on two different biodegradable polymers (coming from the Bioflex and MaterBi families) and two different nanosized fillers (organo-modified clay and hydrophobic-coated precipitated calcium carbonate) were prepared and compared with traditional nanocomposites with high-density polyethylene (HDPE) as matrix. In particular, the injection molding processability, as well as the mechanical and rheological properties of the so-obtained bionanocomposites were investigated. It was found that the processability of the two biodegradable polymers and the related nanocomposites can be compared to that of the HDPE-based systems and that, in general, the bio-based systems can be taken into account as suitable alternatives. Full article
(This article belongs to the Special Issue Green Composites: Preparation, Properties, and Applications)
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14 pages, 4753 KiB  
Article
Innovative Chemical Process for Recycling Thermosets Cured with Recyclamines® by Converting Bio-Epoxy Composites in Reusable Thermoplastic—An LCA Study
by Angela D. La Rosa, Ignazio Blanco, Diosdado R. Banatao, Stefan J. Pastine, Anna Björklund and Gianluca Cicala
Materials 2018, 11(3), 353; https://doi.org/10.3390/ma11030353 - 28 Feb 2018
Cited by 51 | Viewed by 6586
Abstract
An innovative recycling process for thermoset polymer composites developed by Connora Technologies (Hayward, CA, USA) was studied. The process efficacy has already been tested, and it is currently working at the plant level. The main aspect investigated in the present paper was the [...] Read more.
An innovative recycling process for thermoset polymer composites developed by Connora Technologies (Hayward, CA, USA) was studied. The process efficacy has already been tested, and it is currently working at the plant level. The main aspect investigated in the present paper was the environmental impact by means of the Life Cycle Assessment (LCA) method. Because of the need to recycle and recover materials at their end of life, the Connora process creates a great innovation in the market of epoxy composites, as they are notoriously not recyclable. Connora Technologies developed a relatively gentle chemical recycling process that induces the conversion of thermosets into thermoplastics. The LCA demonstrated that low environmental burdens are associated with the process itself and, furthermore, impacts are avoided due to the recovery of the epoxy-composite constituents (fibres and matrix). A carbon fibre (CF) epoxy-composite panel was produced through Vacuum Resin Transfer Moulding (VRTM) and afterwards treated using the Connora recycling process. The LCA results of both the production and the recycling phases are reported. Full article
(This article belongs to the Special Issue Green Composites: Preparation, Properties, and Applications)
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