Fiber and Polymer Composites: Processing, Simulation, Properties and Applications

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Fibers".

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 68541

Special Issue Editors

Polymers Department, Nanocomposite Group, National Institute for Research and Development in Chemistry and Petrochemistry, ICECHIM, Bucharest, Romania
Interests: synthetic/natural nanofillers; synthetic/natural polymer (nano)composites; bio-based thermoplastics; melt processing; polymer masterbatches; automotive/packaging/biomedicine applications
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Guest Editor
National Institute for Research & Development in Chemistry and Petrochemistry-ICECHIM, 202 Spl. Independentei, 060021 Bucharest, Romania
Interests: polymer science; polymer processing; thermoplastics; composites and nanocomposites; bio-based thermoplastics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Polymer composites reinforced with fibers are a promising alternative to metal parts and the solution for light construction materials. Due to their exceptional properties (flexibility, functionality and formability in complicated design parts), fiber-reinforced polymer composites have found applications in many industrial fields (construction, automobile, aerospace), biomedicine, marine and others. The performance of the polymeric composite material mainly depends on the nature of the components, the degree of interaction between the components and the processing technology.

The purpose of this Special Issue is to highlight the latest original results in the development of composite materials based on synthetic and/or natural polymers and synthetic and/or natural fibers, with improved properties imposed by various applications.

Dr. Zina Vuluga
Dr. Mihai Cosmin Corobea
Guest Editors

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Keywords

  • synthetic and/or natural fibers
  • synthetic and/or natural polymers
  • polymer composites
  • processing technology
  • modelling, simulation and optimization
  • properties
  • applications

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Published Papers (23 papers)

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21 pages, 2765 KiB  
Article
Antibacterial Properties of Honey Nanocomposite Fibrous Meshes
by Rupy Kaur Matharu, Jubair Ahmed, Jegak Seo, Kersti Karu, Mitra Ashrafi Golshan, Mohan Edirisinghe and Lena Ciric
Polymers 2022, 14(23), 5155; https://doi.org/10.3390/polym14235155 - 27 Nov 2022
Cited by 2 | Viewed by 2047
Abstract
Natural substances are increasingly being developed for use in health-related applications. Honey has attracted significant interest, not only for its physical and chemical properties, but also for its antibacterial activity. For the first time, suspensions of Black Forest honeydew honey and manuka honey [...] Read more.
Natural substances are increasingly being developed for use in health-related applications. Honey has attracted significant interest, not only for its physical and chemical properties, but also for its antibacterial activity. For the first time, suspensions of Black Forest honeydew honey and manuka honey UMF 20+ were examined for their antibacterial properties against Escherichia coli and Staphylococcus epidermidis using flow cytometry. The inhibitory effect of honey on bacterial growth was evident at concentrations of 10, 20 and 30 v/v%. The minimum inhibitory effects of both honey types against each bacterium were also investigated and reported. Electrospray ionisation (ESI) mass spectrometry was performed on both Black Forest honeydew honey and manuka honey UMF 20+. Manuka honey had a gluconic concentration of 2519 mg/kg, whilst Black Forest honeydew honey had a concentration of 2195 mg/kg. Manuka honey demonstrated the strongest potency when compared to Black Forest honeydew honey; therefore, it was incorporated into nanofiber scaffolds using pressurised gyration and 10, 20 and 30 v/v% manuka honey-polycaprolactone solutions. Composite fibres were analysed for their morphology and topography using scanning electron microscopy. The average fibre diameter of the manuka honey-polycaprolactone scaffolds was found to range from 437 to 815 nm. The antibacterial activity of the 30 v/v% scaffolds was studied using S. epidermidis. Strong antibacterial activity was observed with a bacterial reduction rate of over 90%. The results show that honey composite fibres formed using pressurised gyration can be considered a natural therapeutic agent for various medicinal purposes, including wound-healing applications. Full article
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27 pages, 3819 KiB  
Article
Development of Multifunctional Nano-Graphene-Grafted Polyester to Enhance Thermal Insulation and Performance of Modified Polyesters
by Shih-Hsiung Chen, Naveed Ahmad and Chung-Feng Jeffrey Kuo
Polymers 2022, 14(18), 3821; https://doi.org/10.3390/polym14183821 - 13 Sep 2022
Cited by 4 | Viewed by 1602
Abstract
Nano-graphene materials have improved many thermal properties based on polymer systems. The additive polymers’ thermal insulation cannot be significantly increased for use as a reinforcement in multifunctional thermally insulating polymer foam. Herein, we present the development of far-infrared emissivity and antistatic properties using [...] Read more.
Nano-graphene materials have improved many thermal properties based on polymer systems. The additive polymers’ thermal insulation cannot be significantly increased for use as a reinforcement in multifunctional thermally insulating polymer foam. Herein, we present the development of far-infrared emissivity and antistatic properties using multifunctional nano-graphene polyester fibers. Nano-graphene far-infrared thermal insulation polyester was synthesized with 2% nano-graphene and dispersant polypropylene wax-maleic anhydride (PP wax-MA) using the Taguchi method combined with grey relational analysis (GRA) to improve the thermal properties and the performance of the polymer composite. The thermogravimetric analysis (TGA) shows that the pyrolysis temperature of spinning-grade polyester was increased when the nano-graphene powder was added to the polyester. The differential scanning calorimeter (DSC) analysis confirmed the modification of polyester by nano-graphene, showing the effect of the nucleating agent, which ultimately improved the performance of the polyester. The physical properties of the optimized polyester fibers were improved with a yarn count of 76.5 d, tensile strength of 3.3 g/d, and an elongation at break increased from 23.5% to 26.7% compared with unmodified polymer yarn. These far-infrared emission rates increased from 78% to 83%, whereas the far-infrared temperature increased from 4.0 °C to 22 °C, and the surface resistance increased to 108 Ω. The performance of the optimized modified polyester yarn is far better than single-polypropylene-grafted maleic anhydride yarn. The performance of optimized modified polyester yarn, further confirmed using grey correlation analysis (GRA), can improve the yarns’ mechanical properties and far-infrared functions. Our findings provide an alternative route for developing nano-graphene polyester fabrics suitable for the fabric industry. Full article
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23 pages, 15115 KiB  
Article
A Multiscale Study of CFRP Based on Asymptotic Homogenization with Application to Mechanical Analysis of Composite Pressure Vessels
by Nan Zhang, Shuai Gao, Meili Song, Yang Chen, Xiaodong Zhao, Jianguo Liang and Jun Feng
Polymers 2022, 14(14), 2817; https://doi.org/10.3390/polym14142817 - 11 Jul 2022
Cited by 12 | Viewed by 2539
Abstract
The application of composites is increasingly extensive due to their advanced properties while the analysis still remains complex on different scales. In this article, carbon fiber reinforced polymer (CFRP) is modeled via asymptotic homogenization employing a representative volume element (RVE) with periodic boundary [...] Read more.
The application of composites is increasingly extensive due to their advanced properties while the analysis still remains complex on different scales. In this article, carbon fiber reinforced polymer (CFRP) is modeled via asymptotic homogenization employing a representative volume element (RVE) with periodic boundary conditions. A multiscale mechanical model of CFRP is established to bridge the microscopic model, mesoscopic model, and macroscopic model. According to asymptotic homogenization, the coefficients of the material constitutive equation are calculated with volume-averaged stress and strain. Using the homogenized materials properties of CFRP, the tensile experiments of composite layers with the layout of [(0/60/0/60)4] are carried out to validate asymptotic homogenization method. The results indicated that the asymptotic homogenization approach can be used to calculate the homogenized elastic moduli and Poisson’s ratio of the whole structure, where the numerical results are basically consistent with test data. The sequent homogenized CFRP laminate model is applied to the mechanical analysis of type III composite pressure vessels, whereby burst pressure is accurately predicted. This work might shed some light on multiscale analysis of composite pressure vessels. Full article
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23 pages, 6763 KiB  
Article
Quality Prediction and Abnormal Processing Parameter Identification in Polypropylene Fiber Melt Spinning Using Artificial Intelligence Machine Learning and Deep Learning Algorithms
by Amit Kumar Gope, Yu-Shu Liao and Chung-Feng Jeffrey Kuo
Polymers 2022, 14(13), 2739; https://doi.org/10.3390/polym14132739 - 4 Jul 2022
Cited by 4 | Viewed by 2420
Abstract
Melt spinning machines must be set up according to the process parameters that result in the best end product quality. In this study, artificial intelligence algorithms were employed to create a system that detects abnormal processing parameters and suggests strategies to improve quality. [...] Read more.
Melt spinning machines must be set up according to the process parameters that result in the best end product quality. In this study, artificial intelligence algorithms were employed to create a system that detects abnormal processing parameters and suggests strategies to improve quality. Polypropylene (PP) was selected as the experimental material, and the quality achieved by adjusting the melt spinning machine’s processing parameter settings was used as the basis for judgement. The processing parameters included screw temperature, gear pump temperature, die head temperature, screw speed, gear pump speed, and take-up speed as the six control factors. The four quality characteristics included fineness, breaking strength, elongation at break, and elastic energy modulus. In the first part of our study, we applied fast deep-learning characteristic grid calculations on a 440-item historical data set to train a deep learning neural network and determine methods for multi-quality optimization. In the second part, with the best processing parameters as a benchmark, and given abnormal quality data derived from processing parameter settings deviating from these optimal values, several machine learning and deep learning methods were compared in their ability to find the settings responsible for the abnormal data, which was randomly split into a 210-item training data set and a 210-item verification data set. The random forest method proved to be the best at identifying responsible parameter settings, with accuracy rates of single and double identification classifications together of 100%, for single factor classification of 98.3%, and for double factor classification of 96.0%, thereby confirming that the diagnostic method proposed in this study can effectively predict product abnormality and find the parameter settings responsible for product abnormality. Full article
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15 pages, 3800 KiB  
Article
Preparation of the Carbonized Zif−8@PAN Nanofiber Membrane for Cadmium Ion Adsorption
by Hui Sun, Jiangli Feng, Yaoyao Song, Lei Xu, Xiaogang Cui and Bin Yu
Polymers 2022, 14(13), 2523; https://doi.org/10.3390/polym14132523 - 21 Jun 2022
Cited by 9 | Viewed by 2107
Abstract
The zeolitic imidazolate framework (ZIF−8)@polyacrylonitrile (PAN) nanofiber membrane was prepared and carbonized for heavy metal cadmium ion (Cd2+) adsorption in aqueous medium. Zinc oxide (ZnO) was first sputtered onto the surface of the PAN electrospun nanofiber membrane to provide a metal [...] Read more.
The zeolitic imidazolate framework (ZIF−8)@polyacrylonitrile (PAN) nanofiber membrane was prepared and carbonized for heavy metal cadmium ion (Cd2+) adsorption in aqueous medium. Zinc oxide (ZnO) was first sputtered onto the surface of the PAN electrospun nanofiber membrane to provide a metal ion source. Then, the ZIF−8@PAN nanofiber membrane was prepared via in situ solvothermal reaction and carbonized in a tube furnace at 900 °C under a N2 atmosphere to enhance adsorption performance. The synthesized ZIF−8 particles with polyhedral structure were uniformly immobilized on the surface of the PAN electrospun nanofiber membrane. After being heated at 900 °C, the polygonal ZIF−8 shrank, and the carbonized ZIF−8@PAN nanofiber membrane was obtained. Compared with the nanofiber membrane without being carbonized, the adsorption capacity of the carbonized ZIF−8@PAN nanofiber membrane reached 102 mg L−1, and its Cd2+ adsorption efficiency could be more than 90% under the adsorption temperature of 35 °C and solution of pH = 7.5 conditions. According to the adsorption thermodynamics analysis, the Cd2+ adsorption process of the carbonized ZIF−8@PAN nanofiber membrane was spontaneous. The whole Cd2+ adsorption process was more suitably described by the pseudo second-order adsorption kinetics model, indicating that there exists a chemical adsorption mechanism besides physical adsorption. Full article
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24 pages, 5857 KiB  
Article
Parametric Design Studies of Mass-Related Global Warming Potential and Construction Costs of FRP-Reinforced Concrete Infrastructure
by Philipp Preinstorfer, Tobias Huber, Sara Reichenbach, Janet M. Lees and Benjamin Kromoser
Polymers 2022, 14(12), 2383; https://doi.org/10.3390/polym14122383 - 12 Jun 2022
Cited by 11 | Viewed by 2412
Abstract
Fibre-reinforced polymers (FRPs) are a promising corrosion-resistant alternative to steel reinforcement. FRPs are, however, generally costly and have a high energy demand during production. The question arises whether the high performance of FRPs and possible savings in concrete mass can counterbalance initial costs [...] Read more.
Fibre-reinforced polymers (FRPs) are a promising corrosion-resistant alternative to steel reinforcement. FRPs are, however, generally costly and have a high energy demand during production. The question arises whether the high performance of FRPs and possible savings in concrete mass can counterbalance initial costs and environmental impact. In this paper, a parametric design study that considers a broad range of concrete infrastructure, namely a rail platform barrier, a retaining wall and a bridge, is conducted to assess the mass-related global warming potential and material costs. Design equations are parametrised to derive optimum reinforced concrete cross-sectional designs that fulfil the stated requirements for the serviceability limit state and ultimate limit state. Conventional steel reinforcement, glass and carbon FRP reinforcement options are evaluated. It is observed that the cross-sectional design has a significant influence on the environmental impact and cost, with local extrema for both categories determinable when the respective values become a minimum. When comparing the cradle-to-gate impact of the different materials, the fibre-reinforced polymer-reinforced structures are found to provide roughly equivalent or, in some cases, slightly more sustainable solutions than steel-reinforced structures in terms of the global warming potential, but the material costs are higher. In general, the size of the structure determines the cost competitiveness and sustainability of the FRP-reinforced concrete options with the rail platform barrier application showing the greatest potential. Full article
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16 pages, 4623 KiB  
Article
Tablet Formulations of Polymeric Electrospun Fibers for the Controlled Release of Drugs with pH-Dependent Solubility
by Valeria Friuli, Silvia Pisani, Bice Conti, Giovanna Bruni and Lauretta Maggi
Polymers 2022, 14(10), 2127; https://doi.org/10.3390/polym14102127 - 23 May 2022
Cited by 9 | Viewed by 2116
Abstract
A challenge in the pharmaceutical sector is the development of controlled release dosage forms for oral administration of poorly soluble drugs, in particular, drugs characterized by pH-dependent solubility through the gastrointestinal tract, which itself shows wide variability in terms of environmental pHs. The [...] Read more.
A challenge in the pharmaceutical sector is the development of controlled release dosage forms for oral administration of poorly soluble drugs, in particular, drugs characterized by pH-dependent solubility through the gastrointestinal tract, which itself shows wide variability in terms of environmental pHs. The best approach is to increase the dissolution rate of the drugs at the different pHs and only then modify its release behavior from the pharmaceutical form. This work aims to demonstrate the ability of properly designed polymeric nanofibers in enhancing the release rate of model drugs with different pH-dependent solubility in the different physiological pHs of the gastrointestinal tract. Polymeric nanofibers loaded with meloxicam and carvedilol were prepared using the electrospinning technique and were then included in properly designed tablet formulations to obtain fast or sustained release dosage forms. The nanofibers and the tablets were characterized for their morphological, physico-chemical and dissolution properties. The tablets are able to deliver the dose according to the expected release behavior, and zero-order, first-order, Higuchi, Korsmeyer–Peppas and Hixon–Crowell kinetics models were used to analyze the prevailing release mechanism of the tablets. This study shows that the electrospun fibers can be advantageously included in oral dosage forms to improve their release performances. Full article
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13 pages, 4243 KiB  
Article
Performance of Multilayer Composite Hollow Membrane in Separation of CO2 from CH4 in Mixed Gas Conditions
by Shahidah Zakariya, Yin Fong Yeong, Norwahyu Jusoh and Lian See Tan
Polymers 2022, 14(7), 1480; https://doi.org/10.3390/polym14071480 - 5 Apr 2022
Cited by 3 | Viewed by 2109
Abstract
Composite membranes comprising NH2-MIL-125(Ti)/PEBAX coated on PDMS/PSf were prepared in this work, and their gas separation performance for high CO2 feed gas was investigated under various operating circumstances, such as pressure and CO2 concentration, in mixed gas conditions. The [...] Read more.
Composite membranes comprising NH2-MIL-125(Ti)/PEBAX coated on PDMS/PSf were prepared in this work, and their gas separation performance for high CO2 feed gas was investigated under various operating circumstances, such as pressure and CO2 concentration, in mixed gas conditions. The functional groups and morphology of the prepared membranes were characterized by Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). CO2 concentration and feed gas pressure were demonstrated to have a considerable impact on the CO2 and CH4 permeance, as well as the CO2/CH4 mixed gas selectivity of the resultant membrane. As CO2 concentration was raised from 14.5 vol % to 70 vol %, a trade-off between permeance and selectivity was found, as CO2 permeance increased by 136% and CO2/CH4 selectivity reduced by 42.17%. The membrane produced in this work exhibited pressure durability up to 9 bar and adequate gas separation performance at feed gas conditions consisting of high CO2 content. Full article
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15 pages, 4468 KiB  
Article
Effects of Freeze–Thaw Cycles on Strength and Wave Velocity of Lime-Stabilized Basalt Fiber-Reinforced Loess
by Wensong Wang, Guansen Cao, Ye Li, Yuxi Zhou, Ting Lu, Binbin Zheng and Weile Geng
Polymers 2022, 14(7), 1465; https://doi.org/10.3390/polym14071465 - 4 Apr 2022
Cited by 13 | Viewed by 1881
Abstract
Basalt fiber is a new environmentally-friendly material with excellent potential for soil reinforcement in geotechnical engineering construction. This study explores the effects of freeze–thaw cycles on the unconfined compressive strength (UCS) and P-wave velocity (Vp) of lime-stabilized basalt fiber-reinforced loess. [...] Read more.
Basalt fiber is a new environmentally-friendly material with excellent potential for soil reinforcement in geotechnical engineering construction. This study explores the effects of freeze–thaw cycles on the unconfined compressive strength (UCS) and P-wave velocity (Vp) of lime-stabilized basalt fiber-reinforced loess. Reinforced loess samples with different proportions of basalt fiber and lime were subjected to 0, 1, 5, and 10 freeze–thaw cycles, and their UCS and Vp were subsequently measured. The test results showed that the addition of basalt fiber and lime to loess could enhance strength and improve resistance against freeze–thaw damage, and the freeze–thaw damage of reinforced loess decreases with the increase of basalt fiber content and length. A relationship between UCS and Vp of the reinforced samples was obtained for the same number of freeze–thaw cycles, and this relationship exhibited linear characteristics. The fitting results indicate that the Vp can be used to estimate the UCS after freeze–thaw damage. The research results not only have important practical significance in the application of basalt fiber in geotechnical engineering but also provide a reference for the non-destructive testing of the strength of loess after freeze–thaw cycles. Full article
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19 pages, 3140 KiB  
Article
RSM Modeling and Optimization of CO2 Separation from High CO2 Feed Concentration over Functionalized Membrane
by Nadia Hartini Suhaimi, Yin Fong Yeong, Norwahyu Jusoh, Thiam Leng Chew, Mohammad Azmi Bustam and Muhammad Mubashir
Polymers 2022, 14(7), 1371; https://doi.org/10.3390/polym14071371 - 28 Mar 2022
Cited by 3 | Viewed by 1696
Abstract
The challenges in developing high CO2 gas fields are governed by several factors such as reservoir condition, feed gas composition, operational pressure and temperature, and selection of appropriate technologies for bulk CO2 separation. Thus, in this work, we report an optimization [...] Read more.
The challenges in developing high CO2 gas fields are governed by several factors such as reservoir condition, feed gas composition, operational pressure and temperature, and selection of appropriate technologies for bulk CO2 separation. Thus, in this work, we report an optimization study on the separation of CO2 from CH4 at high CO2 feed concentration over a functionalized mixed matrix membrane using a statistical tool, response surface methodology (RSM) statistical coupled with central composite design (CCD). The functionalized mixed matrix membrane containing NH2-MIL-125 (Ti) and 6FDA-durene, fabricated in our previous study, was used to perform the separation performance under three operational parameters, namely, feed pressure, temperature, and CO2 feed concentration, ranging from 3.5–12.5 bar, 30.0–50.0 °C and 15–70 mol%, respectively. The CO2 permeability and CO2/CH4 separation factor obtained from the experimental work were varied from 293.2–794.4 Barrer and 5.3–13.0, respectively. In addition, the optimum operational parameters were found at a feed pressure of 12.5 bar, a temperature of 34.7 °C, and a CO2 feed concentration of 70 mol%, which yielded the highest CO2 permeability of 609.3 Barrer and a CO2/CH4 separation factor of 11.6. The average errors between the experimental data and data predicted by the model for CO2 permeability and CO2/CH4 separation factor were 5.1% and 3.3%, respectively, confirming the validity of the proposed model. Overall, the findings of this work provide insights into the future utilization of NH2-MIL-125 (Ti)/6FDA-based mixed matrix membranes in real natural gas purification applications. Full article
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10 pages, 37227 KiB  
Article
Polymeric Composite Reinforced with PET Fiber Waste for Application in Civil Construction as a Cladding Element
by Daniel Araujo, Joyce Azevedo, Pollyana Cardoso, Benjamin Lazarus, Matheus Morreira, Lorrane Silva and Josiane Barbosa
Polymers 2022, 14(7), 1293; https://doi.org/10.3390/polym14071293 - 23 Mar 2022
Cited by 3 | Viewed by 1982
Abstract
The construction industry contributes enormously to the high levels of carbon dioxide on the planet. For this reason, the sector has been investing in the development of new products that reduce the environmental impact. This study developed a fibrous polymeric composite using industrial [...] Read more.
The construction industry contributes enormously to the high levels of carbon dioxide on the planet. For this reason, the sector has been investing in the development of new products that reduce the environmental impact. This study developed a fibrous polymeric composite using industrial residues of polyethylene terephthalate (PET) fibers for application in civil construction as a cladding element. The thermal and morphological characterization of the fiber was performed using Thermogravimetry (TG) and Scanning Electron Microscopy (SEM). Composites with 1, 3, and 5% PET fibers were obtained. Mechanical, morphological properties, chemical resistance, the effect of ultraviolet radiation and water absorption of the composites were evaluated. The results were compared to parameters established by the Brazilian standard NBR 15.575-3. Fibers had a smooth surface but with small surface defects, diameter between 20 and 30 µm and thermal stability up to 325.44 °C. The addition of 5% PET fibers resulted in an increase of more than 300% in the impact resistance of the composites, but with a reduction in the flexural strength. The mechanical and chemical resistance results met the parameters established by the standard used in the study. The degradation chamber test indicated that PET fibers suffered more from exposure to ultraviolet radiation than the polymeric matrix. Full article
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11 pages, 27109 KiB  
Article
Thermal Aging Effects on the Mechanical Behavior of Glass-Fiber-Reinforced Polyphenylene Sulfide Composites
by Jiangang Deng, You Song, Zhuolin Xu, Yu Nie and Zhenbo Lan
Polymers 2022, 14(7), 1275; https://doi.org/10.3390/polym14071275 - 22 Mar 2022
Cited by 10 | Viewed by 2773
Abstract
In this article, the thermal aging behavior of polyphenylene sulfide (PPS) composites, reinforced by 20% glass fibers (GFs), in thermal aging temperatures ranging from 85 to 145 °C was studied. Tensile and bending properties and color changes in the thermally aged samples were [...] Read more.
In this article, the thermal aging behavior of polyphenylene sulfide (PPS) composites, reinforced by 20% glass fibers (GFs), in thermal aging temperatures ranging from 85 to 145 °C was studied. Tensile and bending properties and color changes in the thermally aged samples were investigated. The results showed that thermal aging at this temperature range resulted in the degradation of mechanical properties. Both the tensile and flexural strength of the GF/PPS composites were significantly reduced after thermal aging at 145 °C. Decreased strength and brittle fracture were observed because thermal aging at high temperatures resulted in the deterioration of the interfaces between the GFs and PPS matrix. The degradation of the mechanical properties of the composite samples can be reflected by the color change, which means that the mechanical properties of the GF/PPS composite samples under thermal aging are predictable using color change analysis. Full article
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15 pages, 3387 KiB  
Article
Analytical Model for Bond Behavior Prediction of CFRP-Concrete Joints with End Anchorage
by Kun Dong, Caiqun Zhong, Peng Li and Derun Du
Polymers 2021, 13(21), 3684; https://doi.org/10.3390/polym13213684 - 26 Oct 2021
Cited by 3 | Viewed by 1534
Abstract
Use of the end anchorages can significantly control the debonding of CFRP-to-concrete bond interface, and improve the bearing capacity of CFRP strengthened concrete member. An analytical model was presented in this paper to predict the bond behavior and debonding process of CFRP-concrete bonded [...] Read more.
Use of the end anchorages can significantly control the debonding of CFRP-to-concrete bond interface, and improve the bearing capacity of CFRP strengthened concrete member. An analytical model was presented in this paper to predict the bond behavior and debonding process of CFRP-concrete bonded joint with end anchorage. The calculation formulas of bond failure load and effective bond length for anchored CFRP-concrete joint are derived from the proposed analytical model. According to these models and formulas, the influence of different bond lengths on the mechanical behaviors during the debonding process was analyzed. Results show the load-slip curves of end anchored CFRP-concrete joints could be divided into three branches: elastic stage, stable stage, and enhancement stage. As the bond length increases, the plateau length in stable stage increases. Besides, the bond failure load decreased firstly to a lower limit and then increased with the increase of bond length. The effective bond length of CFRP-concrete joint with end anchorage was longer than that of the external bonded joint, and the value of effective bond length for end anchored joint shall be at least 7.2/AB, where the parameters A and B were related to the interfacial properties of bonded joint. Furthermore, a single shear test was carried out on the end anchored CFRP-concrete bonded joint with different bond lengths, to verify the consistency of the proposed model and formulas. The analytical result of load-slip response at the load end, as well as the strain distribution of CFRP material and the bond failure load, was compared with the experimental result. The comparisons showed that the analytical results had a good agreement with the experimental results. Full article
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24 pages, 7372 KiB  
Article
The Effect of SEBS/Halloysite Masterbatch Obtained in Different Extrusion Conditions on the Properties of Hybrid Polypropylene/Glass Fiber Composites for Auto Parts
by Zina Vuluga, Catalina-Gabriela Sanporean, Denis Mihaela Panaitescu, George Mihail Teodorescu, Mihai Cosmin Corobea, Cristian Andi Nicolae, Augusta Raluca Gabor and Valentin Raditoiu
Polymers 2021, 13(20), 3560; https://doi.org/10.3390/polym13203560 - 15 Oct 2021
Cited by 4 | Viewed by 1867
Abstract
Masterbatches from a linear poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) and halloysite nanotubes (HNT-QM) were obtained in different conditions of temperature and shear using two co-rotating twin-screw extruders. The influence of screw configuration and melt processing conditions on the morpho-structural, thermal and mechanical properties of masterbatches at [...] Read more.
Masterbatches from a linear poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) and halloysite nanotubes (HNT-QM) were obtained in different conditions of temperature and shear using two co-rotating twin-screw extruders. The influence of screw configuration and melt processing conditions on the morpho-structural, thermal and mechanical properties of masterbatches at macro and nanoscale was studied. A good dispersion of halloysite nanotubes and better thermal stability and tensile and nanomechanical properties were obtained at a lower temperature profile and higher screw speed. The effect of masterbatches, the best and worst alternatives, on the properties of a polypropylene (PP)–glass fiber (GF) composite was also evaluated. Double hardness, tensile strength and modulus and four times higher impact strength were obtained for PP/GF composites containing masterbatches compared to pristine PP. However, the masterbatch with the best properties led further to enhanced mechanical properties of the PP/GF composite. A clear difference between the effects of the two masterbatches was obtained by nanoindentation and nanoscratch tests. These analyses proved to be useful for the design of polymer composites for automotive parts, such as bumpers or door panels. This study demonstrated that setting-up the correct processing conditions is very important to obtain the desired properties for automotive applications. Full article
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24 pages, 11684 KiB  
Article
Novel Carbon Fibre Composite Centrifugal Impeller Design, Numerical Analysis, Manufacturing and Experimental Evaluations
by Radu Mihalache, Ionut Sebastian Vintila, Marius Deaconu, Mihail Sima, Ion Malael, Alexandru Tudorache and Dragos Mihai
Polymers 2021, 13(19), 3432; https://doi.org/10.3390/polym13193432 - 7 Oct 2021
Cited by 2 | Viewed by 3933
Abstract
This paper presents an experimental investigation on using high strength-to-weight composite materials to reduce the mass of a centrifugal compressor impeller by 600%. By reducing the blades number from 17 to 7 and by doubling their thickness, the compression ratio and efficiency were [...] Read more.
This paper presents an experimental investigation on using high strength-to-weight composite materials to reduce the mass of a centrifugal compressor impeller by 600%. By reducing the blades number from 17 to 7 and by doubling their thickness, the compression ratio and efficiency were maintained close to the reference metallic impeller. Using autoclave technology, seven composite blades were manufactured individually and assembled to form the impeller. After manufacturing, small deviations were found at the blade’s tip. As these deviations were found to be symmetrical, impeller balancing was successfully performed removing a total of 45 g of mass, followed by an experimental test on a dedicated test bench. Experimental testing identified the resonant frequencies of the composite centrifugal impeller at 13.43 Hz 805 rot/min and at 77 Hz with a 0.1 mm/s amplitude at 4400 rot/min, highlighting feasibility and the advantage of a composite compressor impeller design with application in centrifugal compressors and rotating machine assemblies and sub-assemblies. As there are numerous numerical investigations performed on the strength analysis and on the lay-up orientations mechanical behaviour for polymer composite materials with respect to the design of centrifugal impellers, no experimental evaluations in relevant working conditions have been performed to date. As the paper contains relevant experimental data on the subject, the outcome of the paper may aid the oil and gas or aviation industries. Full article
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10 pages, 2743 KiB  
Article
Interfacial Compatibility on the Crystal Transformation of Isotactic Poly (1-Butene)/Herb Residue Composite
by Bo Wang, Shuangdan Mao, Fuhua Lin, Mi Zhang, Yuying Zhao, Xiuhong Zheng, Hui Wang and Jun Luo
Polymers 2021, 13(10), 1654; https://doi.org/10.3390/polym13101654 - 19 May 2021
Cited by 13 | Viewed by 1991
Abstract
Isotactic poly (1-butene) (iPB) has excellent properties which are recognized as a green and energy saving product. However, the most stable and valuable crystal form I had a spontaneous transformation that took as long as seven days to complete. As a special solid [...] Read more.
Isotactic poly (1-butene) (iPB) has excellent properties which are recognized as a green and energy saving product. However, the most stable and valuable crystal form I had a spontaneous transformation that took as long as seven days to complete. As a special solid waste, the herb residue (HR) is rich in cellulose which has great potential to accelerate the crystal transformation of the iPB. However, the polarity of HR results in the interface compatibility with non-polar iPB. In this study, the HR was modified by silane coupling agent (KH570) to obtain KHR and the iPB/HR composite was prepared. The FTIR spectrum was indicated that the organic functional groups of KH570 successfully graft onto the surface of HR and the water contact angle test was indicated that the hydrophilicity of the KHR was greatly decreased. The complete crystal transformation time is 7 days for iPB, 6 days for iPB+5% HR but only 3 days for iPB+5% KHR. The addition of the HR and KHR improve the thermal stability of the composite and this beneficial effect is more obvious for KHR. After annealing for 5 days, the physical properties value include tensile strength, flexural strength, and HDT of iPB+5% HR reach that of pure iPB after annealing for 7 days, but only 3 days for iPB+5% KHR. The TG analysis and SEM photographs give clear evidence that the beneficial effect of KH570 modified HR on improving the interface compatibility with iPB. Full article
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36 pages, 47446 KiB  
Article
Optimal Design of a Fiber-Reinforced Plastic Composite Sandwich Structure for the Base Plate of Aircraft Pallets In Order to Reduce Weight
by Alaa Al-Fatlawi, Károly Jármai and György Kovács
Polymers 2021, 13(5), 834; https://doi.org/10.3390/polym13050834 - 9 Mar 2021
Cited by 17 | Viewed by 10489
Abstract
The application of fiber-reinforced plastic (FRP) composite materials instead of metals, due to the low density of FRP materials, results in weight savings in the base plates of aircraft pallets. Lower weight leads to lower fuel consumption of the aircraft and thereby less [...] Read more.
The application of fiber-reinforced plastic (FRP) composite materials instead of metals, due to the low density of FRP materials, results in weight savings in the base plates of aircraft pallets. Lower weight leads to lower fuel consumption of the aircraft and thereby less environmental damage. The study aimed to investigate replacing the currently used aluminum base plates of aircraft pallets with composite sandwich plates to reduce the weight of the pallets, thereby the weight of the unit loads transported by aircraft. The newly constructed sandwich base plate consists of an aluminum honeycomb core and FRP composite face-sheets. First, we made experimental tests and numerical calculations for the investigated FRP sandwich panel to validate the applicability of the calculation method. Next, the mechanical properties of 40 different layer-combinations of 4 different FRP face-sheet materials (phenolic woven glass fiber; epoxy woven glass fiber; epoxy woven carbon fiber; and hybrid layers) were investigated using the Digimat-HC modeling program in order to find the appropriate face-sheet construction. Face-sheets were built up in 1, 2, 4, 6 or 8 layers with sets of fiber orientations including cross-ply (0°, 90°) and/or angle-ply (±45°). The weight optimization method was elaborated considering 9 design constraints: stiffness, deflection, skin stress, core shear stress, facing stress, overall buckling, shear crimping, skin wrinkling, and intracell buckling. A case study for the base plate of an aircraft pallet was introduced to validate the optimization procedure carried out using the Matlab (Interior Point Algorithm) and Excel Solver (Generalized Reduced Gradient Nonlinear Algorithm) programs. In the case study, the weight of the optimal structure (epoxy woven carbon fiber face-sheets) was 27 kg, which provides weight savings of 66% compared to the standard aluminum pallet. The article’s main added value is the elaboration and implementation of an optimization method that results in significant weight savings and thus lower fuel consumption of aircraft. Full article
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15 pages, 3952 KiB  
Article
The Adhesion of Plasma Nanocoatings Controls the Shear Properties of GF/Polyester Composite
by Tomas Plichta, Veronika Sirjovova, Milan Zvonek, Gerhard Kalinka and Vladimir Cech
Polymers 2021, 13(4), 593; https://doi.org/10.3390/polym13040593 - 16 Feb 2021
Cited by 9 | Viewed by 1923
Abstract
High-performance fibre-reinforced polymer composites are important construction materials based not only on the specific properties of the reinforcing fibres and the flexible polymer matrix but also on the compatible properties of the composite interphase. First, oxygen-free (a-CSi:H) and oxygen-binding (a-CSiO:H) plasma nanocoatings of [...] Read more.
High-performance fibre-reinforced polymer composites are important construction materials based not only on the specific properties of the reinforcing fibres and the flexible polymer matrix but also on the compatible properties of the composite interphase. First, oxygen-free (a-CSi:H) and oxygen-binding (a-CSiO:H) plasma nanocoatings of different mechanical and tribological properties were deposited on planar silicon dioxide substrates that closely mimic E-glass. The nanoscratch test was used to characterize the nanocoating adhesion expressed in terms of critical normal load and work of adhesion. Next, the same nanocoatings were deposited on E-glass fibres, which were used as reinforcements in the polyester composite to affect its interphase properties. The shear properties of the polymer composite were characterized by macro- and micromechanical tests, namely a short beam shear test to determine the short-beam strength and a single fibre push-out test to determine the interfacial shear strength. The results of the polymer composites showed a strong correlation between the short-beam strength and the interfacial shear strength, proving that both tests are sensitive to changes in fibre-matrix adhesion due to different surface modifications of glass fibres (GF). Finally, a strong correlation between the shear properties of the GF/polyester composite and the adhesion of the plasma nanocoating expressed through the work of adhesion was demonstrated. Thus, increasing the work of adhesion of plasma nanocoatings from 0.8 to 1.5 mJ·m−2 increased the short-beam strength from 23.1 to 45.2 MPa. The results confirmed that the work of adhesion is a more suitable parameter in characterising the level of nanocoating adhesion in comparison with the critical normal load. Full article
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18 pages, 8161 KiB  
Article
Enhancing Mechanical Properties of Polymer 3D Printed Parts
by Catalin Gheorghe Amza, Aurelian Zapciu, George Constantin, Florin Baciu and Mihai Ion Vasile
Polymers 2021, 13(4), 562; https://doi.org/10.3390/polym13040562 - 13 Feb 2021
Cited by 41 | Viewed by 4714
Abstract
Parts made from thermoplastic polymers fabricated through 3D printing have reduced mechanical properties compared to those fabricated through injection molding. This paper analyzes a post-processing heat treatment aimed at enhancing mechanical properties of 3D printed parts, in order to reduce the difference mentioned [...] Read more.
Parts made from thermoplastic polymers fabricated through 3D printing have reduced mechanical properties compared to those fabricated through injection molding. This paper analyzes a post-processing heat treatment aimed at enhancing mechanical properties of 3D printed parts, in order to reduce the difference mentioned above and thus increase their applicability in functional applications. Polyethylene Terephthalate Glycol (PETG) polymer is used to 3D print test parts with 100% infill. After printing, samples are packed in sodium chloride powder and then heat treated at a temperature of 220 °C for 5 to 15 min. During heat treatment, the powder acts as support, preventing deformation of the parts. Results of destructive testing experiments show a significant increase in tensile and compressive strength following heat treatment. Treated parts 3D printed in vertical orientation, usually the weakest, display 143% higher tensile strength compared to a control group, surpassing the tensile strength of untreated parts printed in horizontal orientation—usually the strongest. Furthermore, compressive strength increases by 50% following heat treatment compared to control group. SEM analysis reveals improved internal structure after heat treatment. These results show that the investigated heat treatment increases mechanical characteristics of 3D printed PETG parts, without the downside of severe part deformation, thus reducing the performance gap between 3D printing and injection molding when using common polymers. Full article
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11 pages, 2933 KiB  
Article
Electrical Double Percolation of Polybutadiene/Polyethylene Glycol Blends Loaded with Conducting Polymer Nanofibers
by Jun Morita, Takanori Goto, Shinji Kanehashi and Takeshi Shimomura
Polymers 2020, 12(11), 2658; https://doi.org/10.3390/polym12112658 - 11 Nov 2020
Cited by 6 | Viewed by 2220
Abstract
The critical phenomena of double percolation on polybutadiene (PB)/polyethylene glycol (PEG) blends loaded with poly-3-hexylthiophene (P3HT) nanofibers is investigated. P3HT nanofibers are selectively localized in the PB phase of the PB/PEG blend, as observed by scanning force microscopy (SFM). Moreover, double percolation is [...] Read more.
The critical phenomena of double percolation on polybutadiene (PB)/polyethylene glycol (PEG) blends loaded with poly-3-hexylthiophene (P3HT) nanofibers is investigated. P3HT nanofibers are selectively localized in the PB phase of the PB/PEG blend, as observed by scanning force microscopy (SFM). Moreover, double percolation is observed, i.e., the percolation of the PB phase in PB/PEG blends and that of the P3HT nanofibers in the PB phase. The percolation threshold (φcI) and critical exponent (tI) of the percolation of the PB phase in PB/PEG blends are estimated to be 0.57 and 1.3, respectively, indicating that the percolation exhibits two-dimensional properties. For the percolation of P3HT nanofibers in the PB phase, the percolation threshold (φcII) and critical exponent (tII) are estimated to be 0.02 and 1.7, respectively. In this case, the percolation exhibits properties in between two and three dimensions. In addition, we investigated the dimensionality with respect to the carrier transport in the P3HT nanofiber network. From the temperature dependence of the field-effect mobility estimated by field-effect transistor (FET) measurements, the carrier transport was explained by a three-dimensional variable range hopping (VRH) model. Full article
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20 pages, 6438 KiB  
Article
Preparation and Characterization of Semi-Flexible Substrates from Natural Fiber/Nickel Oxide/Polycaprolactone Composite for Microstrip Patch Antenna Circuitries for Microwave Applications
by Ahmad Fahad Ahmad, Sidek Ab Aziz, Yazid Yaakob, Ammar Abd Ali and Nour Attallah Issa
Polymers 2020, 12(10), 2400; https://doi.org/10.3390/polym12102400 - 19 Oct 2020
Cited by 2 | Viewed by 2356
Abstract
The study intended to utilizing waste organic fiber for low-cost semi-flexible substrate fabrication to develop microstrip patch antennas for low band communication applications. All the semi-flexible substrates (12.2 wt. % OPEFF/87.8 wt. % PCL, 12.2 wt. % NiO/87.8 wt. % PCL, and 25 [...] Read more.
The study intended to utilizing waste organic fiber for low-cost semi-flexible substrate fabrication to develop microstrip patch antennas for low band communication applications. All the semi-flexible substrates (12.2 wt. % OPEFF/87.8 wt. % PCL, 12.2 wt. % NiO/87.8 wt. % PCL, and 25 wt. % OPEFF/25 wt. % NiO/50 wt. % PCL) were fabricated by oil palm empty fruit fiber (OPEFF) mixed with nickel oxide (NiO) nanoparticles reinforced with polycaprolactone (PCL) as a matrix using a Thermo Haake blending machine. The morphology and crystalized structure of the substrates were tested using Fourier transform infrared (FTIR) spectrometry, X-ray diffraction (X-RD) technique, and scanning electron microscopy (SEM), respectively. The thermal stability behavior of the substrates was analyzed using thermogravimetric analysis (TGA) and differential thermogravimetric (DTG) thermogram. The dielectric properties were characterized by an open-ended coaxial probe (OEC) connected with Agilent N5230A PNA-L Network Analyzer included the 85070E2 dielectric software at frequency range of 8 to 12 GHz. The experimental results showed that NiO/OPEFF/PCL composites exhibit controllable permittivity dielectric constant εr(f) between 1.89 and 4.2 (Farad/meter, (F/m)), with loss factor εr(f) between 0.08 and 0.62 F/m, and loss tangent (tan δ) between 0.05 and 0.18. Return losses measurement of the three patch antennas OPEFF/PCL, NiO/PCL, and OPEFF/NiO/PCL are −11.93, −14.2 and −16.3 dB respectively. Finally, the commercial software package, Computer Simulation Technology Microwave Studio (CSTMWS), was used to investigate the antenna performance by simulate S-parameters based on the measured dielectric parameters. A negligible difference is found between the measured and simulated results. Finally, the results obtained encourage the possibility of using natural fibers and nickel oxide in preparation of the substrates utilize at microwave applications. Full article
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Review

Jump to: Research

22 pages, 8684 KiB  
Review
Development of Amine-Functionalized Metal-Organic Frameworks Hollow Fiber Mixed Matrix Membranes for CO2 and CH4 Separation: A Review
by Naveen Sunder, Yeong Yin Fong, Mohamad Azmi Bustam and Nadia Hartini Suhaimi
Polymers 2022, 14(7), 1408; https://doi.org/10.3390/polym14071408 - 30 Mar 2022
Cited by 12 | Viewed by 3023
Abstract
CO2 separation from raw natural gas can be achieved through the use of the promising membrane-based technology. Polymeric membranes are a known method for separating CO2 but suffer from trade-offs between its permeability and selectivity. Therefore, through the use of mixed [...] Read more.
CO2 separation from raw natural gas can be achieved through the use of the promising membrane-based technology. Polymeric membranes are a known method for separating CO2 but suffer from trade-offs between its permeability and selectivity. Therefore, through the use of mixed matrix membranes (MMMs) which utilizes inorganic or hybrid fillers such as metal-organic frameworks (MOFs) in polymeric matrix, the permeability and selectivity trade-off can be overcome and possibly surpass the Robeson Upper Bounds. In this study, various types of MOFs are explored in terms of its structure and properties such as thermal and chemical stability. Next, the use of amine and non-amine functionalized MOFs in MMMs development are compared in order to investigate the effects of amine functionalization on the membrane gas separation performance for flat sheet and hollow fiber configurations as reported in the literature. Moreover, the gas transport properties and various challenges faced by hollow fiber mixed matrix membranes (HFMMMs) are discussed. In addition, the utilization of amine functionalization MOF for mitigating the challenges faced is included. Finally, the future directions of amine-functionalized MOF HFMMMs are discussed for the fields of CO2 separation. Full article
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22 pages, 5094 KiB  
Review
Importance of Interfacial Adhesion Condition on Characterization of Plant-Fiber-Reinforced Polymer Composites: A Review
by Ching Hao Lee, Abdan Khalina and Seng Hua Lee
Polymers 2021, 13(3), 438; https://doi.org/10.3390/polym13030438 - 29 Jan 2021
Cited by 101 | Viewed by 6121
Abstract
Plant fibers have become a highly sought-after material in the recent days as a result of raising environmental awareness and the realization of harmful effects imposed by synthetic fibers. Natural plant fibers have been widely used as fillers in fabricating plant-fibers-reinforced polymer composites. [...] Read more.
Plant fibers have become a highly sought-after material in the recent days as a result of raising environmental awareness and the realization of harmful effects imposed by synthetic fibers. Natural plant fibers have been widely used as fillers in fabricating plant-fibers-reinforced polymer composites. However, owing to the completely opposite nature of the plant fibers and polymer matrix, treatment is often required to enhance the compatibility between these two materials. Interfacial adhesion mechanisms are among the most influential yet seldom discussed factors that affect the physical, mechanical, and thermal properties of the plant-fibers-reinforced polymer composites. Therefore, this review paper expounds the importance of interfacial adhesion condition on the properties of plant-fiber-reinforced polymer composites. The advantages and disadvantages of natural plant fibers are discussed. Four important interface mechanism, namely interdiffusion, electrostatic adhesion, chemical adhesion, and mechanical interlocking are highlighted. In addition, quantifying and analysis techniques of interfacial adhesion condition is demonstrated. Lastly, the importance of interfacial adhesion condition on the performances of the plant fiber polymer composites performances is discussed. It can be seen that the physical and thermal properties as well as flexural strength of the composites are highly dependent on the interfacial adhesion condition. Full article
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