Journal of Composites Science

Research

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15 pages, 4784 KiB

Open AccessArticle

Degradation and Breakdown of Polymer/Graphene Composites under Strong Electric Field

by Yangming Kou, Xiang Cheng and Christopher W. Macosko

J. Compos. Sci. 2022, 6(5), 139; https://doi.org/10.3390/jcs6050139 - 10 May 2022

Cited by 3 | Viewed by 3277

Abstract

In this work, we study the effect of strong electric fields on a polymer/graphene composite and the resulting morphology upon its dielectric breakdown. Our model system was produced by compounding up to 0.25 wt % graphene nanoplatelets (GNP) into poly(ethylene-co-vinyl acetate) [...] Read more.

In this work, we study the effect of strong electric fields on a polymer/graphene composite and the resulting morphology upon its dielectric breakdown. Our model system was produced by compounding up to 0.25 wt % graphene nanoplatelets (GNP) into poly(ethylene-co-vinyl acetate) (EVA), which is a soft polymer with low melt viscosity. A strong electric field of up to 400 V_rms/mm was applied to the EVA/GNP composite in the melt. The sample’s resistance over the electric field application was simultaneously measured. Despite the low GNP loading, which was below the theoretical percolation threshold, the electric conductivity of the composite during electric field application dramatically increased to >10⁻⁶ S/cm over 5 min of electric field application before reaching the current limit of the experimental apparatus. Conductivity growth follows the same scaling relationship of the theoretical model that predicts the rotation and translation time of GNPs in a polymer melt as a function of electric field strength. Since no significant GNP alignment in the composite was observed under transmission electron microscopy (TEM), we hypothesized that the increase in electrical conductivity was due to local electrical treeing of the polymer matrix, which eventually leads to dielectric breakdown of the composite. Electrical treeing is likely initiated by local GNP agglomerates and propagated through conductive channels formed during progressive dielectric breakdown. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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16 pages, 4877 KiB

Open AccessArticle

Mitigating Early Phase Separation of Aliphatic Random Ionomers by the Hydrophobic H-Bond Acceptor Addition

by David Julius, Chunliu Fang, Liang Hong and Jim Yang Lee

J. Compos. Sci. 2022, 6(3), 73; https://doi.org/10.3390/jcs6030073 - 25 Feb 2022

Viewed by 2382

Abstract

This study reports a new phenomenon whereby the ionic content of a random ionomer was increased by the introduction of a hydrophobic modifier. In the current study, the ionomer synthesized from the solution polymerization of the three vinyl monomers, which are polar hydrophobic [...] Read more.

This study reports a new phenomenon whereby the ionic content of a random ionomer was increased by the introduction of a hydrophobic modifier. In the current study, the ionomer synthesized from the solution polymerization of the three vinyl monomers, which are polar hydrophobic monomers acrylonitrile (AN), glycidyl methacrylate (GMA), and ionic monomer potassium 3-sulfopropyl methacrylate (SPM), encountered an early phase separation problem when the ionic content exceeded a certain threshold value. However, the addition of a strongly hydrophobic monomer, 2,2,3,3-tetrafluoropropyl methacrylate (TFPM), during the copolymerization is able to restrain this phase separation trend, consequently allowing 50% more of SPM units to be incorporated and uniformly distributed in the ionomer and achieving a random copolymer chain. The ionic clustering of the SPM units, which is the cause for the phase separation, was reduced as a result. The resulting random ionomer was demonstrated to be a superior proton conducting material over its ternary originator. This is due to the fact that TFPM possesses acidic protons, which brings about an association of TFPM with SPM and GMA via hydrogen bonding. This study could impact the synthesis of random ionomers by free radical polymerization since monitoring ionic content and improving ionic unit distribution in ionomers are issues encountered in several industries (e.g., the healthcare industry). Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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25 pages, 14889 KiB

Open AccessArticle

The Use of Agricultural Waste in the Modification of Poly(lactic acid)-Based Composites Intended for 3D Printing Applications. The Use of Toughened Blend Systems to Improve Mechanical Properties

by Jacek Andrzejewski, Karolina Grad, Wojciech Wiśniewski and Joanna Szulc

J. Compos. Sci. 2021, 5(10), 253; https://doi.org/10.3390/jcs5100253 - 22 Sep 2021

Cited by 13 | Viewed by 2815

Abstract

The presented research focused on improving the mechanical properties of PLA-based composites reinforced with buckwheat husks (BH) particles. The research work was carried out in two stages. Firstly, the blend was prepared with the addition of polybutylene adipate terephthalate (PBAT) and thermoplastic starch [...] Read more.

The presented research focused on improving the mechanical properties of PLA-based composites reinforced with buckwheat husks (BH) particles. The research work was carried out in two stages. Firstly, the blend was prepared with the addition of polybutylene adipate terephthalate (PBAT) and thermoplastic starch (TPS), manufactured by injection molding technique, then the selected materials were prepared with the addition of BH filler, and the samples were prepared using the fused deposition modeling method (FDM). All samples were subjected to the assessment of material properties. Thermal and thermomechanical properties were evaluated using differential scanning calorimetry analysis (DSC) and dynamic thermal mechanical analysis (DMTA). Mechanical characteristic was evaluated using static tensile and flexural measurements and Charpy impact resistance tests. The research was supplemented with scanning electron microscopy analysis (SEM). It was found that the addition of PBAT and TPS greatly improves impact strength and elongation, especially with the addition of reactive compatibilizer. As expected, TPS, PBAT, and BH reduced the stiffness of the composites during DMTA testing. The presence of BH particles in the polymer matrix was observed to improve the crystallization behavior of PLA. The optimal content of BH filler in the composite was found to be 10%, which allowed to preserve good mechanical properties. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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14 pages, 1845 KiB

Open AccessArticle

Benzoxazine Copolymers with Mono- and Difunctional Epoxy Active Diluents with Enhanced Tackiness and Reduced Viscosity

by Natalia V. Bornosuz, Roman F. Korotkov, Vyacheslav V. Shutov, Igor S. Sirotin and Irina Yu. Gorbunova

J. Compos. Sci. 2021, 5(9), 250; https://doi.org/10.3390/jcs5090250 - 18 Sep 2021

Cited by 8 | Viewed by 2311

Abstract

The influence of epoxy active diluents, 1,4-butanediol diglycidyl ether (BD) and furfuryl glycidyl ether (FUR), in the mixtures with benzoxazine monomer based on bisphenol A, formaldehyde and m-toluidine (BA-mt), on the properties of a matrix was disclosed in this work. Resins were modified [...] Read more.

The influence of epoxy active diluents, 1,4-butanediol diglycidyl ether (BD) and furfuryl glycidyl ether (FUR), in the mixtures with benzoxazine monomer based on bisphenol A, formaldehyde and m-toluidine (BA-mt), on the properties of a matrix was disclosed in this work. Resins were modified to achieve good tackiness at room temperature and reduced viscosity. The influence of mono- and difunctional modifiers on the process of curing was studied by way of differential scanning calorimetry and oscillatory rheology. The addition of BD and FUR shifted the curing peak to higher temperatures and significantly reduced viscosity. Preferable tackiness at ambient temperature was achieved with 10 phr of epoxy components in mixtures. However, cured blends with difunctional epoxy BD had an advantage over monofunctional FUR in enhanced tensile strength with remaining glass transition temperature at the level of neat benzoxazine (217 °C). Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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11 pages, 2252 KiB

Open AccessArticle

Conducting-Polymer Nanocomposites as Synergistic Supports That Accelerate Electro-Catalysis: PEDOT/Nano Co₃O₄/rGO as a Photo Catalyst of Oxygen Production from Water

by Mohammed Alsultan, Anwer M. Ameen, Amar Al-keisy and Gerhard F. Swiegers

J. Compos. Sci. 2021, 5(9), 245; https://doi.org/10.3390/jcs5090245 - 12 Sep 2021

Cited by 7 | Viewed by 2202

Abstract

This work describes how conducting polymer nanocomposites can be employed as synergistic supports that significantly accelerate the rate of electro-catalysis. The nanocomposite PEDOT/nano-Co₃O₄/rGO is discussed as an example in this respect, which is specific for photo electro-catalytic oxygen (O [...] Read more.

This work describes how conducting polymer nanocomposites can be employed as synergistic supports that significantly accelerate the rate of electro-catalysis. The nanocomposite PEDOT/nano-Co₃O₄/rGO is discussed as an example in this respect, which is specific for photo electro-catalytic oxygen (O₂) generation from water using light (PEDOT = poly (3,4-ethylenedioxythiophene); rGO = reduced graphene oxide). We show that the conducting polymer PEDOT and the conductive additive rGO may be used to notably amplify the rate of O₂-generation from water by the nano catalyst, Co₃O₄. A composite film containing the precise molar ratio 7.18 (C; PEDOT):1 (Co):5.18 (C; rGO) exhibited high photocatalytic activity (pH 12) for the oxygen evolution reaction (OER) at 0.80 V (vs. Ag/AgCl), with a current density of 1000 ± 50 μA/cm² (including a photocurrent of 500 μA/cm²), achieved after >42 h of operation under illumination with a light of intensity 0.25 sun. By comparison, the best industrial catalyst, Pt, yielded a much lower 150 μA/cm² under the same conditions. Oxygen gas was the sole product of the reaction. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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18 pages, 6297 KiB

Open AccessArticle

Improvement of Performance Profile of Acrylic Based Polyester Bio-Composites by Bast/Basalt Fibers Hybridization for Automotive Applications

by Anjum Saleem, Luisa Medina and Mikael Skrifvars

J. Compos. Sci. 2021, 5(4), 100; https://doi.org/10.3390/jcs5040100 - 4 Apr 2021

Cited by 4 | Viewed by 2820

Abstract

New technologies in the automotive industry require lightweight, environment-friendly, and mechanically strong materials. Bast fibers such as kenaf, flax, and hemp reinforced polymers are frequently used composites in semi-structural applications in industry. However, the low mechanical properties of bast fibers limit the applications [...] Read more.

New technologies in the automotive industry require lightweight, environment-friendly, and mechanically strong materials. Bast fibers such as kenaf, flax, and hemp reinforced polymers are frequently used composites in semi-structural applications in industry. However, the low mechanical properties of bast fibers limit the applications of these composites in structural applications. The work presented here aims to enhance the mechanical property profile of bast fiber reinforced acrylic-based polyester resin composites by hybridization with basalt fibers. The hybridization was studied in three resin forms, solution, dispersion, and a mixture of solution and dispersion resin forms. The composites were prepared by established processing methods such as carding, resin impregnation, and compression molding. The composites were characterized for their mechanical (tensile, flexural, and Charpy impact strength), thermal, and morphological properties. The mechanical performance of hybrid bast/basalt fiber composites was significantly improved compared to their respective bast fiber composites. For hybrid composites, the specific flexural modulus and strength were on an average about 21 and 19% higher, specific tensile modulus and strength about 31 and 16% higher, respectively, and the specific impact energy was 13% higher than bast fiber reinforced composites. The statistical significance of the results was analyzed using one-way analysis of variance. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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10 pages, 4195 KiB

Open AccessArticle

The Influence of Pressure-Induced-Flow Processing on the Morphology, Thermal and Mechanical Properties of Polypropylene Blends

by Pengfei Li, Yanpei Fei, Shilun Ruan, Jianjiang Yang, Feng Chen and Yangfu Jin

J. Compos. Sci. 2021, 5(3), 64; https://doi.org/10.3390/jcs5030064 - 24 Feb 2021

Cited by 4 | Viewed by 2501

Abstract

The pressure-induced-flow (PIF) processing can effectively prepare high-performance polymer materials. This paper studies the influence of pressure-induced-flow processing on the morphology, thermodynamic and mechanical properties of polypropylene (PP)/polyamide 6 (PA6) blends, PP/polyolefin elastomer (POE) blends and PP/thermoplastic urethane (TPU) blends. The results show [...] Read more.

The pressure-induced-flow (PIF) processing can effectively prepare high-performance polymer materials. This paper studies the influence of pressure-induced-flow processing on the morphology, thermodynamic and mechanical properties of polypropylene (PP)/polyamide 6 (PA6) blends, PP/polyolefin elastomer (POE) blends and PP/thermoplastic urethane (TPU) blends. The results show that pressure-induced-flow processing can significantly improve the thermodynamic and mechanical properties of the blends by regulating internal structure. Research shows that the pressure-induced-flow processing can increase the strength and the toughness of the blends, particularly in PP/TPU blends. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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12 pages, 4035 KiB

Open AccessArticle

Study of the Preparation and Properties of TPS/PBSA/PLA Biodegradable Composites

by Yuxuan Wang, Yuke Zhong, Qifeng Shi and Sen Guo

J. Compos. Sci. 2021, 5(2), 48; https://doi.org/10.3390/jcs5020048 - 4 Feb 2021

Cited by 8 | Viewed by 3004

Abstract

Thermoplastic starch/butyl glycol ester copolymer/polylactic acid (TPS/PBSA/PLA) biodegradable composites were prepared by melt-mixing. The structure, microstructure, mechanical properties and heat resistance of the TPS/PBSA/PLA composites were studied by Fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), tensile test and thermogravimetry tests, respectively. The [...] Read more.

Thermoplastic starch/butyl glycol ester copolymer/polylactic acid (TPS/PBSA/PLA) biodegradable composites were prepared by melt-mixing. The structure, microstructure, mechanical properties and heat resistance of the TPS/PBSA/PLA composites were studied by Fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), tensile test and thermogravimetry tests, respectively. The results showed that PBSA or PLA could bind to TPS by hydrogen bonding. SEM analysis showed that the composite represents an excellent dispersion and satisfied two-phase compatibility when the PLA, TPS and PBSA blended by a mass ration of 10, 30, and 60. The mechanical properties and the heat resistance of TPS/PBSA/PLA composite were improved by adding PLA with content less than 10%, according to the testing results. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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13 pages, 10535 KiB

Open AccessArticle

Development of A Nano-Apatite Based Composite Sealer for Endodontic Root Canal Filling

by Angelica Bertacci, Daniele Moro, Gianfranco Ulian and Giovanni Valdrè

J. Compos. Sci. 2021, 5(1), 30; https://doi.org/10.3390/jcs5010030 - 16 Jan 2021

Cited by 4 | Viewed by 2104

Abstract

Recently, endodontic sealers based on injectable bioactive materials were proposed to improve the filling of anatomical irregularities during root canal obturation. In this context, this preliminary work investigated the possibility of realizing a new calcium phosphate-based composite sealer for root canal filling with [...] Read more.

Recently, endodontic sealers based on injectable bioactive materials were proposed to improve the filling of anatomical irregularities during root canal obturation. In this context, this preliminary work investigated the possibility of realizing a new calcium phosphate-based composite sealer for root canal filling with an optimized composition on setting kinetics and dentin tubules occlusion. Several calcium phosphate/liquid phase mixtures were initially evaluated for their workability, finding two suitable formulations. Both of them contained 66 wt.% of a nano-apatite-based cement (solid powdered phase). The liquid phase (34 wt.%) comprised 13.6% propanediol and 20.4% PEG 1000 (formulation 1), and formulation 2 comprised 27.2% glycerin and 6.8% PEG 200 (formulation 2). Then, these formulations were tested by means of permeability measurements and observation by scanning electron microscopy of treated model dentin samples. Both formulations succeeded in occluding dentinal tubules: the first one was able to create a full-bodied layer on dentin surface and, moreover, to resist, at least to a large extent, against citric acid attack. The second one showed a lower effectiveness after citric acid exposure. The composite compound that better satisfied the overall required characteristics of use, workability and sealing capacity was formulation 1. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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12 pages, 6809 KiB

Open AccessArticle

Performance Analysis of Embedded Mechanoluminescence-Perovskite Self-Powered Pressure Sensor for Structural Health Monitoring

by Lucas Braga Carani, Vincent Obiozo Eze, Chetanna Iwuagwu and Okenwa Izeji Okoli

J. Compos. Sci. 2020, 4(4), 190; https://doi.org/10.3390/jcs4040190 - 18 Dec 2020

Cited by 11 | Viewed by 3270

Abstract

Recent developments in sensing technologies have triggered a lot of research interest in exploring novel self-powered, inexpensive, compact and flexible pressure sensors with the potential for structural health monitoring (SHM) applications. Herein, we assessed the performance of an embedded mechanoluminescent (ML) and perovskite [...] Read more.

Recent developments in sensing technologies have triggered a lot of research interest in exploring novel self-powered, inexpensive, compact and flexible pressure sensors with the potential for structural health monitoring (SHM) applications. Herein, we assessed the performance of an embedded mechanoluminescent (ML) and perovskite pressure sensor that integrates the physical principles of mechanoluminescence and perovskite materials. For a continuous in-situ SHM, it is crucial to evaluate the capabilities of the sensing device when embedded into a composite structure. An experimental study of how the sensor is affected by the embedment process into a glass fiber-reinforced composite has been conducted. A series of devices with and without ML were embedded within a composite laminate, and the signal responses were collected under different conditions. We also demonstrated a successful encapsulation process in order for the device to withstand the composite manufacturing conditions. The results show that the sensor exhibits distinct signals when subjected to different load conditions and can be used for the in-situ SHM of advanced composite structures. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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15 pages, 2765 KiB

Open AccessArticle

Steel-Reinforced Polymers and Steel-Reinforced Composite Mortars for Structural Applications—An Overview

by Rafał Krzywoń

J. Compos. Sci. 2020, 4(3), 142; https://doi.org/10.3390/jcs4030142 - 20 Sep 2020

Cited by 3 | Viewed by 3333

Abstract

Bonding of external reinforcement is currently the simplest, fastest, and most popular method of strengthening concrete and masonry structures. Glass and carbon organic fibers are the dominant materials used, but alternatives also include high-strength steel wires. The mechanical properties of such steel are [...] Read more.

Bonding of external reinforcement is currently the simplest, fastest, and most popular method of strengthening concrete and masonry structures. Glass and carbon organic fibers are the dominant materials used, but alternatives also include high-strength steel wires. The mechanical properties of such steel are comparable to those of carbon fiber. Due to their good compatibility with mortars, steel wires are particularly well suited to the revitalization of historic buildings. The manuscript provides an overview of research and experience in the use of steel-reinforced polymers (SRPs) and steel-reinforced composite mortars (SRCMs, also called steel-reinforced grout (SRG)) for structural strengthening. The examples described are for concrete beams, slabs and columns, walls, and masonry arches. The results of laboratory tests are discussed. The summary presents the advantages and disadvantages of composites based on ultra-high-strength steels compared with more popular carbon fiber composites. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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15 pages, 6062 KiB

Open AccessArticle

Studies on Mechanical, Thermal and Morphological Properties of Betel Nut Husk Nano Cellulose Reinforced Biodegradable Polymer Composites

by Tanvir Sultana, Shahin Sultana, Husna Parvin Nur and Md Wahab Khan

J. Compos. Sci. 2020, 4(3), 83; https://doi.org/10.3390/jcs4030083 - 27 Jun 2020

Cited by 41 | Viewed by 5472

Abstract

Nanocellulose has recently gained a significant level of attention from academic and industrial researchers due to its non-toxic, biocompatible, bio-degradable, low-cost, and easy availability that connects many applications. In this research, cellulose extracted from betel nut husk fiber (BNHF) was converted to nanocellulose [...] Read more.

Nanocellulose has recently gained a significant level of attention from academic and industrial researchers due to its non-toxic, biocompatible, bio-degradable, low-cost, and easy availability that connects many applications. In this research, cellulose extracted from betel nut husk fiber (BNHF) was converted to nanocellulose by chemical technique to examine their potential for use as reinforcement in bio-composite applications. The cellulose isolated from BNHF was subjected to acid hydrolysis using 62% sulfuric acid under ultrasonic treatment to convert cellulose into nanocellulose. The particle size of nanocellulose was determined by particle size analyzer. The morphology, structure and thermal properties of nanocellulose were also determined by scanning electron microscope (SEM) and Fourier-transform infrared (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetric (DSC) analysis. The bio-composites of nanocellulose–polyvinyl alcohol (PVA) and cellulose–PVA were prepared with different weight percentages (1–5%) of nanocellulose and cellulose via casting methods. The tensile, thermal and morphological properties were characterized for all composites. Enhancement in the tensile, thermal, and morphological properties was found in the nanocellulose–PVA biocomposites. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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11 pages, 4776 KiB

Open AccessArticle

Preparation and Characterization of an Electrospun PLA-Cyclodextrins Composite for Simultaneous High-Efficiency PM and VOC Removal

by Silvia Palmieri, Mattia Pierpaoli, Luca Riderelli, Sheng Qi and Maria Letizia Ruello

J. Compos. Sci. 2020, 4(2), 79; https://doi.org/10.3390/jcs4020079 - 23 Jun 2020

Cited by 19 | Viewed by 3515

Abstract

Electrospinning is known to be a facile and effective technique to fabricate fibers of a controlled diameter-distribution. Among a multitude of polymers available for the purpose, the attention should be addressed to the environmentally compatible ones, with a special focus on sustainability. Polylactic [...] Read more.

Electrospinning is known to be a facile and effective technique to fabricate fibers of a controlled diameter-distribution. Among a multitude of polymers available for the purpose, the attention should be addressed to the environmentally compatible ones, with a special focus on sustainability. Polylactic acid (PLA) is a widespread, non-toxic polymer, originating from renewable sources and it can degrade into innocuous products. While the production of fibrous membranes is attractive for airborne particles filtration applications, their impact on the removal of gaseous compounds is generally neglected. In this study, electrospun PLA-based nanofibers were functionalized with cyclodextrins, because of their characteristic hydrophobic central cavity and a hydrophilic outer surface, in order to provide adsorptive properties to the composite. The aim of this work is to investigate a hybrid composite, from renewable sources, for the combined filtration of particulate matter (PM) and adsorption of volatile organic compounds (VOCs). Results show how their inclusion into the polymer strongly affects the fiber morphology, while their attachment onto the fiber surface only positively affects the filtration efficiency. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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Review

Jump to: Research

27 pages, 5137 KiB

Open AccessReview

Current Concepts for Cutting Metal-Based and Polymer-Based Composite Materials

by Tomasz Trzepieciński, Sherwan Mohammed Najm and Hirpa G. Lemu

J. Compos. Sci. 2022, 6(5), 150; https://doi.org/10.3390/jcs6050150 - 19 May 2022

Cited by 11 | Viewed by 4233

Abstract

Due to the variety of properties of the composites produced, determining the choice of the appropriate cutting technique is demanding. Therefore, it is necessary to know the problems associated with cutting operations, i.e., mechanical cutting (blanking), plasma cutting plasma, water jet cutting, abrasive [...] Read more.

Due to the variety of properties of the composites produced, determining the choice of the appropriate cutting technique is demanding. Therefore, it is necessary to know the problems associated with cutting operations, i.e., mechanical cutting (blanking), plasma cutting plasma, water jet cutting, abrasive water jet cutting, laser cutting and electrical discharge machining (EDM). The criterion for choosing the right cutting technique for a specific application depends not only on the expected cutting speed and material thickness, but it is also related to the physico-mechanical properties of the material being processed. In other words, the large variety of composite properties necessitates an individual approach determining the possibility of cutting a composite material with a specific method. This paper presents the achievements gained over the last ten years in the field of non-conventional cutting of metal-based and polymer-based composite materials. The greatest attention is paid to the methods of electrical discharge machining and ultrasonic cutting. The methods of high-energy cutting and water jet cutting are also considered and discussed. Although it is well-known that plasma cutting is not widely used in cutting composites, the authors also took into account this type of cutting treatment. The volume of each chapter depends on the dissemination of a given metal-based and polymer-based composite material cutting technique. For each cutting technique, the paper presents the phenomena that have a direct impact on the quality of the resulting surface and on the formation of the most important defects encountered. Finally, the identified current knowledge gaps are discussed. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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28 pages, 5755 KiB

Open AccessReview

Thermoplastic Composite Materials Approach for More Circular Components: From Monomer to In Situ Polymerization, a Review

by Marco Valente, Ilaria Rossitti, Ilario Biblioteca and Matteo Sambucci

J. Compos. Sci. 2022, 6(5), 132; https://doi.org/10.3390/jcs6050132 - 29 Apr 2022

Cited by 12 | Viewed by 4415

Abstract

To move toward eco-sustainable and circular composites, one of the most effective solutions is to create thermoplastic composites. The strong commitment of world organizations in the field of safeguarding the planet has directed the research of these materials toward production processes with a [...] Read more.

To move toward eco-sustainable and circular composites, one of the most effective solutions is to create thermoplastic composites. The strong commitment of world organizations in the field of safeguarding the planet has directed the research of these materials toward production processes with a lower environmental impact and a strong propensity to recycle the polymeric part. Under its chemical properties, Nylon 6 is the polymer that best satisfies this specific trade-off. The most common production processes that use a thermosetting matrix are described. Subsequently, the work aimed at investigating the use of thermoplastics in the same processes to obtain comparable performances with the materials that are currently used. Particular attention was given to the in situ anionic polymerization process of Nylon 6, starting from the ε-caprolactam monomer. The dependencies of the process parameters, such as temperature, time, pressure, humidity, and concentration of initiators and activators, were therefore investigated with reference to the vacuum infusion technique, currently optimized only to produce thermosetting matrix composites, but promising for the realization of thermoplastic matrix composite; this is the reason why we chose to focus our attention on the vacuum infusion. Finally, three production processes of the polymeric matrix and glass fiber composites were compared in terms of carbon footprint and cumulative energy demand (CED) through life-cycle assessment (LCA). Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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23 pages, 4241 KiB

Open AccessReview

Ultrasonic Anisotropy in Composites: Effects and Applications

by Igor Solodov, Yannick Bernhardt, Linus Littner and Marc Kreutzbruck

J. Compos. Sci. 2022, 6(3), 93; https://doi.org/10.3390/jcs6030093 - 16 Mar 2022

Cited by 5 | Viewed by 2868

Abstract

Stiffness anisotropy is a natural consequence of a fibrous structure of composite materials. The effect of anisotropy can be two-fold: it is highly desirable in some cases to assure a proper material response, while it might be even harmful for the applications based [...] Read more.

Stiffness anisotropy is a natural consequence of a fibrous structure of composite materials. The effect of anisotropy can be two-fold: it is highly desirable in some cases to assure a proper material response, while it might be even harmful for the applications based on “isotropic” composite materials. To provide a controllable flexibility in material architecture by corresponding fibre alignment, the methodologies for the precise non-destructive evaluation of elastic anisotropy and the fibre orientation are required. The tasks of monitoring the anisotropy and assessing the fibre fields in composites are analyzed by using the two types of ultrasonic waves suitable for regular plate-shaped composite profiles. In the plate wave approach, the effect of “dispersion of anisotropy” has been shown to make the wave velocity anisotropy to be a function of frequency. As a result, the in-plane velocity pattern measured at a certain frequency is affected by the difference in the wave structure, which activates different elasticity against the background of intrinsic material anisotropy. Phase velocity anisotropy and its frequency dependence provide a frequency variation of the beam steering angle for plate waves (dispersion of beam steering). In strongly anisotropic composite materials, the beam steering effect is shown to provide a strong focusing of ultrasonic energy (phonon focusing). For bulk shear waves, the orthotropic composite anisotropy causes the effect of acoustic birefringence. The birefringent acoustic field provides information on stiffness anisotropy which can be caused by internal stresses, texture, molecular or/and fibre orientation. On this basis, a simple experimental technique is developed and applied for mapping of fibre orientation in composite materials. Various modes of acoustic birefringence are analyzed and applied to assessing the fibre fields in injection moulding composites and to identify the fibre lay-ups in multiply materials. The birefringence pattern is also shown to be sensitive and applicable to characterizing impact- and mechanical stress-induced damage in composites. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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27 pages, 1106 KiB

Open AccessReview

Rubberized Geopolymer Composites: Value-Added Applications

by Ismail Luhar and Salmabanu Luhar

J. Compos. Sci. 2021, 5(12), 312; https://doi.org/10.3390/jcs5120312 - 27 Nov 2021

Cited by 11 | Viewed by 4225

Abstract

The discovery of an innovative class of inorganic polymers has brought forth a revolution in the history of construction technology. Now, no energy-intensive reactions at elevated temperatures are essential, as found in the case of contemporary cement production. In addition to their attributes [...] Read more.

The discovery of an innovative class of inorganic polymers has brought forth a revolution in the history of construction technology. Now, no energy-intensive reactions at elevated temperatures are essential, as found in the case of contemporary cement production. In addition to their attributes of low energy and a mitigated carbon footprint, geopolymeric composites can incorporate diversely originated and profound wastes in their manufacturing. As of today, profoundly accessible landfills of rubber tyre waste negatively impact the environment, water, and soil, with many health hazards. Their nonbiodegradable complex chemical structure supports recycling, and toxic gases are emitted by burning them, leading to aesthetic issues. These, altogether, create great concern for well-thought-out disposal methods. One of the achievable solutions is processing this waste into alternative aggregates to thus generate increased economic value whilst reducing primary aggregate consumption through the incorporation of these vast automobile solid wastes in the manufacturing of geopolymer construction composites, e.g., binders, mortar, concrete, etc., produced through the process of geopolymerization as a replacement for natural aggregates, providing relief to the crisis of the degradation of restricted natural aggregate resources. Currently, tyre rubber is one of the most outstanding materials, extensively employed in scores of engineering applications. This manuscript presents a state-of-the-art review of value-added applications in the context of rubberized geopolymer building composites and a review of past investigations. More significantly, this paper reviews rubberized geopolymer composites for their value-added applications. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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46 pages, 23602 KiB

Open AccessEditor’s ChoiceReview

Recent Advances in Preparation, Mechanisms, and Applications of Thermally Conductive Polymer Composites: A Review

by Hao Zhang, Xiaowen Zhang, Zhou Fang, Yao Huang, Hong Xu, Ying Liu, Daming Wu, Jian Zhuang and Jingyao Sun

J. Compos. Sci. 2020, 4(4), 180; https://doi.org/10.3390/jcs4040180 - 29 Nov 2020

Cited by 72 | Viewed by 9942

Abstract

At present, the rapid accumulation of heat and the heat dissipation of electronic equipment and related components are important reasons that restrict the miniaturization, high integration, and high power of electronic equipment. It seriously affects the performance and life of electronic devices. Hence, [...] Read more.

At present, the rapid accumulation of heat and the heat dissipation of electronic equipment and related components are important reasons that restrict the miniaturization, high integration, and high power of electronic equipment. It seriously affects the performance and life of electronic devices. Hence, improving the thermal conductivity of polymer composites (TCPCs) is the key to solving this problem. Compared with manufacturing intrinsic thermally conductive polymer composites, the method of filling the polymer matrix with thermally conductive fillers can better-enhance the thermal conductivity (λ) of the composites. This review starts from the thermal conduction mechanism and describes the factors affecting the λ of polymer composites, including filler type, filler morphology and distribution, and the functional surface treatment of fillers. Next, we introduce the preparation methods of filled thermally conductive polymer composites with different filler types. In addition, some commonly used thermal-conductivity theoretical models have been introduced to better-analyze the thermophysical properties of polymer composites. We discuss the simulation of λ and the thermal conduction process of polymer composites based on molecular dynamics and finite element analysis methods. Meanwhile, we briefly introduce the application of polymer composites in thermal management. Finally, we outline the challenges and prospects of TCPCs. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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23 pages, 8734 KiB

Open AccessReview

Electrostatic Assembly Technique for Novel Composites Fabrication

by Hiroyuki Muto, Atsushi Yokoi and Wai Kian Tan

J. Compos. Sci. 2020, 4(4), 155; https://doi.org/10.3390/jcs4040155 - 20 Oct 2020

Cited by 21 | Viewed by 4256

Abstract

Electrostatic assembly is one of the bottom–up approaches used for multiscale composite fabrication. Since its discovery, this method has been actively used in molecular bioscience as well as materials design and fabrication for various applications. Despite the recent advances and controlled assembly reported [...] Read more.

Electrostatic assembly is one of the bottom–up approaches used for multiscale composite fabrication. Since its discovery, this method has been actively used in molecular bioscience as well as materials design and fabrication for various applications. Despite the recent advances and controlled assembly reported using electrostatic interaction, the method still possesses vast potentials for various materials design and fabrication. This review article is a timely revisit of the electrostatic assembly method with a brief introduction of the method followed by surveys of recent advances and applications of the composites fabricated. Emphasis is also given to the significant potential of this method for advanced materials and composite fabrication in line with sustainable development goals. Prospective outlook and future developments for micro-/nanocomposite materials fabrication for emerging applications such as energy-related fields and additive manufacturing are also mentioned. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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