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21 pages, 6372 KiB

Open AccessArticle

Thermal Degradation Mechanism and Decomposition Kinetic Studies of Poly(Ethylene Succinate)/Hemp Fiber Composites

by Iouliana Chrysafi, Nina Maria Ainali, Eleftheria Xanthopoulou, Alexandra Zamboulis and Dimitrios N. Bikiaris

J. Compos. Sci. 2023, 7(6), 216; https://doi.org/10.3390/jcs7060216 - 25 May 2023

Cited by 6 | Viewed by 1851

Abstract

The continuous depletion of natural resources coupled with plastics pollution, has prompted the scientific community to explore alternative biobased and/or biodegradable polymers. Poly(ethylene succinate) (PESu) is a promising substitute due to its high processability and controllable biodegradation rate. Meanwhile, hemp possesses interesting properties [...] Read more.

The continuous depletion of natural resources coupled with plastics pollution, has prompted the scientific community to explore alternative biobased and/or biodegradable polymers. Poly(ethylene succinate) (PESu) is a promising substitute due to its high processability and controllable biodegradation rate. Meanwhile, hemp possesses interesting properties such as being lightweight, exhibiting excellent long-term mechanical stability, and having low carbon emissions, making it an ideal option for wood replacement. Thus, PESu/hemp fiber composites (with and without compatibilizer) were prepared novel sustainable materials with improved properties. The present study aims to investigate the thermal degradation of PESu/hemp fiber composites. More specifically, thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass spectrometry (Py–GC/MS) were employed to examine the degradation mechanism and identify decomposition products. The isoconversional methods of Vyazovkin and Friedman, as well as the model free methods, provided comparable results. Samples without compatibilizer were characterized by a two-step Cn autocatalytic mechanism, while those with compatibilizer showed a triple Cn mechanism. The main thermal degradation pathway of the composites was the β-hydrogen scission of the polymeric backbone. In conclusion, this study provides information about the thermal behavior of PESu/hemp fiber composites useful for their application as alternative “wood plastic composites (WPCs)”. Full article

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

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13 pages, 23894 KiB

Open AccessArticle

Physical and Chemical Foam Injection Moulding of Natural-Fibre-Reinforced Polypropylene—Assessment of Weight-Reduction Potential and Mechanical Properties

by Matthias Mihalic, Claudia Pretschuh, Thomas Lummerstorfer and Christoph Unterweger

J. Compos. Sci. 2023, 7(4), 144; https://doi.org/10.3390/jcs7040144 - 6 Apr 2023

Cited by 2 | Viewed by 1928

Abstract

Reducing weight not only consumes fewer resources for manufacturing but also requires less energy for transportation, thus preserving resources and reducing CO₂ emissions. The latter part is of utmost importance in mobility applications. For example, in the automotive industry, the large-scale production [...] Read more.

Reducing weight not only consumes fewer resources for manufacturing but also requires less energy for transportation, thus preserving resources and reducing CO₂ emissions. The latter part is of utmost importance in mobility applications. For example, in the automotive industry, the large-scale production of lightweight structural parts is becoming a main issue. An effective method to meet these requirements is foam injection moulding. In this study, physical (MuCell technology) and chemical foam injection moulding was used to produce plates made from wood-fibre- and cellulose-fibre-reinforced polypropylene, respectively. For both technologies, the used core-back method enabled precise mould opening during injection and thus allowed for variation in the plate thickness and density. The simpler short-shot technology, used only for the chemical foaming trials with differing shot volumes, provided plates with constant thicknesses. The foam structure and finally the mechanical properties of the plates depended on the filler type, the foaming method and the density. The latter was directly linked to either the plate thickness or the shot volume. Physical foaming appeared to be slightly more effective regarding the achievable density reduction (up to 37% reduction), but the physically foamed parts had worse mechanical properties at equal density than their chemically foamed counterparts. Besides the comparison of different foaming methods, this study provides the tensile, flexural and impact properties of natural-fibre-reinforced polypropylene composites over a wide density range, thus offering a good basis for evaluating weight-saving potential for various applications. Full article

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

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19 pages, 4682 KiB

Open AccessArticle

Improved Fly Ash Based Structural Foam Concrete with Polypropylene Fiber

by Alexey N. Beskopylny, Evgenii M. Shcherban’, Sergey A. Stel’makh, Levon R. Mailyan, Besarion Meskhi, Valery Varavka, Andrei Chernil’nik and Anastasia Pogrebnyak

J. Compos. Sci. 2023, 7(2), 76; https://doi.org/10.3390/jcs7020076 - 12 Feb 2023

Cited by 11 | Viewed by 2293

Abstract

The direction of construction science that is associated with the development of the theory and practice of creating a new generation of foam concrete is particularly interesting and relevant. The development of improved structural foam concrete using polypropylene fiber and industrial waste, namely [...] Read more.

The direction of construction science that is associated with the development of the theory and practice of creating a new generation of foam concrete is particularly interesting and relevant. The development of improved structural foam concrete using polypropylene fiber and industrial waste, namely fly ash (FA), is prompted by the existing environmental threat posed by FA; this threat is a result of the operation of the fuel energy industry, as well as the possibility of using foam concrete not only as thermal insulation, but as the main material for load-bearing structures that have a certain level of responsibility. The aim of this work was to create and optimize the recipe technological parameters to produce non-autoclaved fiber foam concrete (FFC) using FA as a component. The study used standardized methods for assessing the properties of FFC, and the method of optical microscopy to analyze the structural characteristics of the material. It has been revealed that the replacement of cement with FA in an amount of 10% to 40% helps to reduce the dry density (DD) of FFC. The lowest DD was recorded for samples with 40% FA. The best results for the compressive strength (CS) and flexural strength (FS) were recorded for FFC samples with 10% FA instead of cement. The increase in CS was 12%, and the increase in FS was 23%. The best thermal insulation properties of FFC, and in terms of resistance to freezing and thawing, were recorded in samples with a 10% replacement of cement with FA. The maximum decrease in thermal conductivity was 14%. Full article

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

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20 pages, 16137 KiB

Open AccessArticle

Assessment of the Potential of Waste Copper Chromium and Arsenic (CCA)-Treated Timber Fibre Reinforced Polypropylene Composites for Construction

by Jacob Nelson, Kim L. Pickering and Mohammad D. H. Beg

J. Compos. Sci. 2023, 7(2), 48; https://doi.org/10.3390/jcs7020048 - 25 Jan 2023

Cited by 2 | Viewed by 1968

Abstract

This paper investigates the potential of recycling waste copper chromium and arsenic (CCA)-treated timber for use as a reinforcement material in wood–plastic composites (WPCs) produced for use in construction, including an assessment of mechanical properties and the leaching of heavy metals. Wood flour [...] Read more.

This paper investigates the potential of recycling waste copper chromium and arsenic (CCA)-treated timber for use as a reinforcement material in wood–plastic composites (WPCs) produced for use in construction, including an assessment of mechanical properties and the leaching of heavy metals. Wood flour was obtained through mechanical grinding, and fibres were obtained through alkaline digestion followed by bleaching. Composites produced with 40 wt.% bleached fibres showed increased tensile strength from 18.5 MPa for the polypropylene used as the matrix to 27.6 MPa. Likewise, the Young’s modulus was increased from 0.84 to 2.33 GPa. The treatment of fibres was found to reduce arsenic concentration by up to 99.9%. Furthermore, the arsenic in the leachate from composites was found to decrease from 41.29 to 0.07 ppb when comparing CCA-treated wood flour composites to bleached fibre composites. The composites’ material properties indicate that the use of end-of-life CCA-treated timber could be used to produce a composite material that could be used in New Zealand’s building sector to meet the requirements of semi-structural applications. Full article

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

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13 pages, 3372 KiB

Open AccessArticle

Dielectric Spectroscopy of Melt-Mixed Polypropylene and Pyrolytically Stripped Carbon Nanofiber Composites

by Zineb Samir, Antonio J. Paleo, Najoia Aribou, Yassine Nioua, Jaime Oliveira da Silva, Maria F. Cerqueira, Joaquim Agostinho Moreira and Mohammed E. Achour

J. Compos. Sci. 2022, 6(12), 368; https://doi.org/10.3390/jcs6120368 - 5 Dec 2022

Cited by 3 | Viewed by 2085

Abstract

In this work, pyrolytically stripped carbon nanofiber (CNF) polypropylene (PP) composites were synthesized following a scalable melt-mixing method, and the effects of CNF weight concentrations on the electrical conductivity, dielectric permittivity, electrical modulus and electrical impedance of PP/CNF composites were studied. Quite unexpectedly, [...] Read more.

In this work, pyrolytically stripped carbon nanofiber (CNF) polypropylene (PP) composites were synthesized following a scalable melt-mixing method, and the effects of CNF weight concentrations on the electrical conductivity, dielectric permittivity, electrical modulus and electrical impedance of PP/CNF composites were studied. Quite unexpectedly, the electrical conductivity of PP/CNF composites improved only slightly as the incorporation of CNFs was raised, yielding a maximum of ~10⁻¹⁰ S m⁻¹ for PP/CNF 5 wt. % composites. The increase corresponded to a gradual improvement of the dielectric constant up to a maximum of ~9 for PP/CNF 5 wt. % composites at 1 MHz, which was attributed to the raise of interface polarization effect. Moreover, the Cole–Cole model was used to analyze the effects of CNF concentrations on the dielectric relaxation of PP/CNF composites, from which was deduced that the incorporation of CNFs increases their dielectric strength and relaxation times. The analysis gathered here aims to provide a better insight into the enhanced dielectric properties observed in low-conducting polymer composites filled with CNFs. Full article

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

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19 pages, 4734 KiB

Open AccessArticle

Titica Vine Fiber (Heteropsis flexuosa): A Hidden Amazon Fiber with Potential Applications as Reinforcement in Polymer Matrix Composites

by Juliana dos Santos Carneiro da Cunha, Lucio Fabio Cassiano Nascimento, Fernanda Santos da Luz, Fabio da Costa Garcia Filho, Michelle Souza Oliveira and Sergio Neves Monteiro

J. Compos. Sci. 2022, 6(9), 251; https://doi.org/10.3390/jcs6090251 - 27 Aug 2022

Cited by 9 | Viewed by 2236

Abstract

The titica vine fiber (TVF) (Heteropsis flexuosa) is a natural lignocellulose fiber (NLF) from the Amazon rainforest that was, for the first time, investigated in terms of its basic properties such as dimensions, porosity, and density as well as its chemical [...] Read more.

The titica vine fiber (TVF) (Heteropsis flexuosa) is a natural lignocellulose fiber (NLF) from the Amazon rainforest that was, for the first time, investigated in terms of its basic properties such as dimensions, porosity, and density as well as its chemical composition, moisture content, crystallinity, and microfibrillar angle. In this study, the apparent density of TVF was determined as one of the lowest-ever reported for NLFs). Using both the geometric method and Archimedes’ principle, density values in the range of 0.5–0.6 g/cm³ were obtained. The moisture content was measured as around 11%, which is in accordance with the commonly reported values for NLFs. The TVF exhibited a high porosity, approximately 70%, which was confirmed by SEM images, where a highly porous morphological structure associated with the presence of many voids and lumens was observed. The crystallinity index and microfibrillar angle were determined as 78% and 7.95°, respectively, which are of interest for a stiff NLF. A preliminary assessment on the mechanical properties of the TVFs revealed a tensile strength, Young’s modulus, and elongation of 26 MPa, 1 GPa, and 7.4%, respectively. Furthermore, the fiber presented a critical length of 7.62 mm in epoxy matrix and an interfacial shear strength of 0.97 MPa. These results suggest the TVFs might favors applications where lighter materials with intermediate properties are required. Full article

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

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21 pages, 9705 KiB

Open AccessArticle

Static and Fatigue Debond Resistance between the Composite Facesheet and Al Cores under Mode-1 in Sandwich Beams

by Vignesh Selvam, Vijay Shankar Sridharan and Sridhar Idapalapati

J. Compos. Sci. 2022, 6(2), 51; https://doi.org/10.3390/jcs6020051 - 7 Feb 2022

Viewed by 2893

Abstract

The debonding toughness between unidirectional glass fiber reinforced polymer face sheets and cellularic cores of sandwich structures is experimentally measured under static and fatigue loading conditions. The effect of various core geometries, such as regular honeycomb and closed-cell foams of two relative densities [...] Read more.

The debonding toughness between unidirectional glass fiber reinforced polymer face sheets and cellularic cores of sandwich structures is experimentally measured under static and fatigue loading conditions. The effect of various core geometries, such as regular honeycomb and closed-cell foams of two relative densities on the adhesive interfacial toughness is explored using the single cantilever beam (SCB) testing method. The steady-state crack growth measurements are used to plot the Paris curves. The uniformity of adhesive filleting and the crack path was found to affect the interfacial toughness. The static Mode-1 interfacial toughness of high-density foam cores was witnessed to be maximal, followed by low-density honeycomb, high-density honeycomb, and low-density foam core. Similarly, the fatigue behavior of the low-density honeycomb core has the lowest crack growth rates compared to the other samples, primarily due to uniform adhesive filleting. Full article

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

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16 pages, 3679 KiB

Open AccessCommunication

Cure Kinetics of Samarium-Doped Fe₃O₄/Epoxy Nanocomposites

by Maryam Jouyandeh, Mohammad Reza Ganjali, Mehdi Mehrpooya, Otman Abida, Karam Jabbour, Navid Rabiee, Sajjad Habibzadeh, Amin Hamed Mashahdzadeh, Alberto García-Peñas, Florian J. Stadler and Mohammad Reza Saeb

J. Compos. Sci. 2022, 6(1), 29; https://doi.org/10.3390/jcs6010029 - 17 Jan 2022

Cited by 7 | Viewed by 2850

Abstract

To answer the question “How does lanthanide doping in iron oxide affect cure kinetics of epoxy-based nanocomposites?”, we synthesized samarium (Sm)-doped Fe₃O₄ nanoparticles electrochemically and characterized it using Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), field emission scanning electron [...] Read more.

To answer the question “How does lanthanide doping in iron oxide affect cure kinetics of epoxy-based nanocomposites?”, we synthesized samarium (Sm)-doped Fe₃O₄ nanoparticles electrochemically and characterized it using Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-Ray analysis (EDX), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy analyses (XPS). The magnetic particles were uniformly dispersed in epoxy resin to increase the curability of the epoxy/amine system. The effect of the lanthanide dopant on the curing reaction of epoxy with amine was explored by analyzing differential scanning calorimetry (DSC) experimental data based on a model-free methodology. It was found that Sm³⁺ in the structure of Fe₃O₄ crystal participates in cross-linking epoxy by catalyzing the reaction between epoxide rings and amine groups of curing agents. In addition, the etherification reaction of active OH groups on the surface of nanoparticles reacts with epoxy rings, which prolong the reaction time at the late stage of reaction where diffusion is the dominant mechanism. Full article

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

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19 pages, 37307 KiB

Open AccessArticle

Reducing the Weakening Effect in Fibre-Reinforced Polymers Caused by Integrated Film Sensors

by Alexander Kyriazis, Julia Feder, Korbinian Rager, Chresten von der Heide, Andreas Dietzel and Michael Sinapius

J. Compos. Sci. 2021, 5(10), 256; https://doi.org/10.3390/jcs5100256 - 28 Sep 2021

Cited by 2 | Viewed by 1979

Abstract

Integrating foil sensors into fibre-reinforced plastics offers the advantage of making manufacturing measurable with spatial resolution and thus simplifies quality control. One challenge here is the possible negative influence of the integrated sensors on the mechanical behaviour of the structure. This article shows [...] Read more.

Integrating foil sensors into fibre-reinforced plastics offers the advantage of making manufacturing measurable with spatial resolution and thus simplifies quality control. One challenge here is the possible negative influence of the integrated sensors on the mechanical behaviour of the structure. This article shows how the different parts of a film sensor influence important mechanical strength parameters of fibre composites. A comparison of two thermoplastic carrier films shows that by choosing polyetherimide (PEI) instead of polyimide (PI), a considerably more advantageous failure behaviour of the composite is achieved. While integrated PI films reduce the interlaminar shear strength by 68%, no impairment is noticeable due to PEI films. For the critical energy release rate, PEI-based film sensors even lead to a significant increase, while a significant deterioration of 85% can be observed for PI-based sensors. However, not only the film substrate plays a decisive role for the interlaminar shear strength, but also the sensor structures themselves. In this article, sensor structures made of gold were investigated. The decisive parameter for the impairment seems to be the area share of gold structures in the sensor. For a sensor pattern made of gold lines with an area filling of 50%, a reduction of the interlaminar shear strength of up to 25% was observed depending on the angle between the shear stress and the gold lines. No impairment was observed for sensor structures with less gold area. The results show that PEI substrates can be a superior alternative for sensor integration into fibre composites and suggest that there is a trade-off between sensitivity and degradation of mechanical properties when designing interdigital sensors. Full article

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

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12 pages, 5368 KiB

Open AccessArticle

Fibre-Reinforced Geopolymer Composites Micro-Nanochemistry by SEM-EDS Simulations

by Daniele Moro, Gianfranco Ulian and Giovanni Valdrè

J. Compos. Sci. 2021, 5(8), 214; https://doi.org/10.3390/jcs5080214 - 12 Aug 2021

Cited by 2 | Viewed by 2082

Abstract

The focus of the present study is on fibre-reinforced geopolymer composites, whose optimization and application necessarily need a detailed chemical characterization at the micro-nanoscale. In this regard, many geopolymer composites presenting micro and nanometric architectures pose a challenge for scanning electron microscopy with [...] Read more.

The focus of the present study is on fibre-reinforced geopolymer composites, whose optimization and application necessarily need a detailed chemical characterization at the micro-nanoscale. In this regard, many geopolymer composites presenting micro and nanometric architectures pose a challenge for scanning electron microscopy with energy dispersive X-ray microanalysis (SEM-EDS) quantification, because of several potential sources of errors. For this reason, the present work reports a SEM-EDS Monte Carlo approach to carefully investigate the complex physical phenomena related to the cited quantification errors. The model used for this theoretical analysis is a simplified fibre-reinforced geopolymer with basalt-derived glass fibres immersed in a potassium-poly(sialate-siloxo) matrix. The simulated SEM-EDS spectra showed a strong influence on the measured X-ray intensity of (i) the sample nano-to-micro architecture, (ii) the electron beam probing energy and (iii) the electron probe-sample-EDS detector relative position. The results showed that, compared to a bulk material, the X-ray intensity for a nano-micrometric sized specimen may give rise to potential underestimation and/or overestimation of the elemental composition of the sample. The proposed Monte Carlo approach indicated the optimal instrumental setup depending on the sample and on the specific SEM-EDS equipment here considered. Full article

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

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7 pages, 1856 KiB

Open AccessArticle

Fabrication of h-MoO₃ Nanorods and the Properties of the MoO₃/WEP Composite Coatings Research

by Ying Zhou, Cuihuan Song, Zhixiang Chen and Qixin Zhou

J. Compos. Sci. 2021, 5(8), 207; https://doi.org/10.3390/jcs5080207 - 4 Aug 2021

Cited by 3 | Viewed by 2320

Abstract

In this study, we prepared a novel coating composed of hexagonal molybdenum oxide (h-MoO₃) nanofiller and waterborne epoxy resin (WEP) to provide corrosion protection. We optimized the h-MoO₃ nanorod synthesis methodology first by changing different parameters (pH, temperature, etc.). Furthermore, [...] Read more.

In this study, we prepared a novel coating composed of hexagonal molybdenum oxide (h-MoO₃) nanofiller and waterborne epoxy resin (WEP) to provide corrosion protection. We optimized the h-MoO₃ nanorod synthesis methodology first by changing different parameters (pH, temperature, etc.). Furthermore, the as-prepared h-MoO₃ rods were characterized using a scanning electron microscope (SEM) and X-ray diffraction (XRD). Finally, the electrochemical impedance spectroscopy (EIS) test results verified that the anticorrosive performance of the composite coatings was improved by incorporation of low content of MoO₃ nanofiller (0.5 wt.%) compared to pure WEP sample. This developed composite will provide a new insight for the design and fabrication of one-dimensional (1D) nanomaterial (e.g., nanorod) reinforced epoxy coating and other polymeric coating processes. Full article

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

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12 pages, 2828 KiB

Open AccessArticle

Electromagnetic Shielding Effectiveness of Glass Fiber/Epoxy Laminated Composites with Multi-Scale Reinforcements

by Nilufar Yesmin and Vijaya Chalivendra

J. Compos. Sci. 2021, 5(8), 204; https://doi.org/10.3390/jcs5080204 - 3 Aug 2021

Cited by 16 | Viewed by 3317

Abstract

In this study, an experimental investigation has been performed to understand the electromagnetic interference-shielding effectiveness (EMI-SE) of glass fiber/epoxy laminated composites embedded with carbon nanotubes (CNTs) and Fe₃O₄ nanoparticles, reinforced with micro carbon fibers along the thickness direction. Micro carbon [...] Read more.

In this study, an experimental investigation has been performed to understand the electromagnetic interference-shielding effectiveness (EMI-SE) of glass fiber/epoxy laminated composites embedded with carbon nanotubes (CNTs) and Fe₃O₄ nanoparticles, reinforced with micro carbon fibers along the thickness direction. Micro carbon fibers were reinforced along the thickness direction between the laminates using an electro-flocking process and a vacuum infusion process used to fabricate the composites. The EMI-SE of the composites was measured in the X-band frequency range (8–12 GHz). The effect of carbon fibers of three different lengths (80 µm, 150 µm, and 350 µm) with two different fiber densities (1000 and 2000 fibers/mm²) and two different amounts of Fe₃O₄ nanoparticles (0.5 and 1 wt.%) on total SE, absorption, and reflection was investigated. Due to the synergetic effect of Fe₃O₄ nanoparticles, CNTs, and carbon fibers, the final EMI shielding of the composites was mainly dominated by the absorption process. The absorption was more pronounced in the composites of longer carbon fibers with improved electrical conductivity. The presence of Fe₃O₄ nanoparticles also enhanced total SE values with improved magnetic permeability. The composite with micro carbon fibers of 350 µm length and 2000 fibers/mm² density with 1 wt.% of Fe₃O₄ nanoparticles showed the maximum value of total SE. Full article

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

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14 pages, 4574 KiB

Open AccessArticle

Engineering Properties of Hybrid Fibre Reinforced Ternary Blend Geopolymer Concrete

by V. Sathish Kumar, N. Ganesan and P. V. Indira

J. Compos. Sci. 2021, 5(8), 203; https://doi.org/10.3390/jcs5080203 - 3 Aug 2021

Cited by 19 | Viewed by 2934

Abstract

The primary aim of this research is to find an alternative for Portland cement using inorganic geopolymers. This study investigated the effect of steel and polypropylene fibres hybridisation on ternary blend geopolymer concrete (TGPC) engineering properties using fly ash, ground granulated blast furnace [...] Read more.

The primary aim of this research is to find an alternative for Portland cement using inorganic geopolymers. This study investigated the effect of steel and polypropylene fibres hybridisation on ternary blend geopolymer concrete (TGPC) engineering properties using fly ash, ground granulated blast furnace slag (GGBS) and metakaolin as the source materials. The properties like compressive strength, splitting tensile strength, flexural strength and modulus of elasticity of ternary blend geopolymer concrete. The standard tests were conducted on TGPC with steel fibres, polypropylene fibres and a combination of steel and polypropylene fibres in hybrid form. A total number of 45 specimens were tested and compared to determine each property. The grade of concrete considered was M55. The variables studied were the volume fraction of fibres, viz. steel fibres (0%, 0.5% and 1%) and polypropylene fibres (0%, 0.1%, 0.15%, 0.2% and 0.25%). The experimental results reveal that the addition of fibres in a hybrid form enhances the mechanical properties of TGPC. The increase in the compressive strength was nominal, and a significant improvement was observed in splitting tensile strength, flexural strength, and modulus of elasticity. Also, an attempt to obtain the relation between the different engineering properties was made with different volume fractions of fibre. Full article

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

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11 pages, 4432 KiB

Open AccessArticle

Influence of Rigid Brazilian Natural Fiber Arrangements in Polymer Composites: Energy Absorption and Ballistic Efficiency

by Fabio C. Garcia Filho, Fernanda S. Luz, Michelle S. Oliveira, Wendell B. A. Bezerra, Josiane D. V. Barbosa and Sergio N. Monteiro

J. Compos. Sci. 2021, 5(8), 201; https://doi.org/10.3390/jcs5080201 - 1 Aug 2021

Cited by 8 | Viewed by 2748

Abstract

Since the mid-2000s, several studies were carried out regarding the development of ballistic resistant materials based on polymeric matrix composites reinforced with natural lignocellulosic fibers (NLFs). The results reported so far are promising and are often comparable to commonly used materials such as [...] Read more.

Since the mid-2000s, several studies were carried out regarding the development of ballistic resistant materials based on polymeric matrix composites reinforced with natural lignocellulosic fibers (NLFs). The results reported so far are promising and are often comparable to commonly used materials such as Kevlar^TM, especially when used as an intermediate layer in a multilayer armor system (MAS). However, the most suitable configuration for these polymer composites reinforced with NLFs when subjected to high strain rates still lacks investigation. This work aimed to evaluate four possible arrangements for epoxy matrix composite reinforced with a stiff Brazilian NLF, piassava fiber, regarding energy absorption, and ballistic efficiency. Performance was evaluated against the ballistic impact of high-energy 7.62 mm ammunition. Obtained results were statistically validated by means of analysis of variance (ANOVA) and Tukey’s honest test. Furthermore, the micromechanics associated with the failure of these composites were determined. Energy absorption of the same magnitude as Kevlar^TM and indentation depth below the limit predicted by NIJ standard were obtained for all conditions. Full article

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

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32 pages, 4822 KiB

Open AccessArticle

Stress-Function Variational Method for Accurate Free-Edge Interfacial Stress Analysis of Adhesively Bonded Single-Lap Joints and Single-Sided Joints

by Xiang-Fa Wu, Youhao Zhao and Oksana Zholobko

J. Compos. Sci. 2021, 5(8), 197; https://doi.org/10.3390/jcs5080197 - 23 Jul 2021

Viewed by 3625

Abstract

Large free-edge interfacial stresses induced in adhesively bonded joints (ABJs) are responsible for the commonly observed debonding failure in ABJs. Accurate and efficient stress analysis of ABJs is important to the design, structural optimization, and failure analysis of ABJs subjected to external mechanical [...] Read more.

Large free-edge interfacial stresses induced in adhesively bonded joints (ABJs) are responsible for the commonly observed debonding failure in ABJs. Accurate and efficient stress analysis of ABJs is important to the design, structural optimization, and failure analysis of ABJs subjected to external mechanical and thermomechanical loads. This paper generalizes the high-efficiency semi-analytic stress-function variational methods developed by the authors for accurate free-edge interfacial stress analysis of ABJs of various geometrical configurations. Numerical results of the interfacial stresses of two types of common ABJs, i.e., adhesively bonded single-lap joints and adhesively single-sided joints, are demonstrated by using the present method, which are further validated by finite element analysis (FEA). The numerical procedure formulated in this study indicates that the present semi-analytic stress-function variational method can be conveniently implemented for accurate free-edge interfacial stress analysis of various type of ABJs by only slightly modifying the force boundary conditions. This method is applicable for strength analysis and structural design of broad ABJs made of multi-materials such as composite laminates, smart materials, etc. Full article

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

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9 pages, 1831 KiB

Open AccessArticle

Urethane Diols through Non-Isocyanate Approach and Their Application in MF Coating

by Kuanchen Huang, Zichen Ling and Qixin Zhou

J. Compos. Sci. 2021, 5(7), 194; https://doi.org/10.3390/jcs5070194 - 20 Jul 2021

Cited by 3 | Viewed by 2506

Abstract

In this work, two urethane diols with different middle chain lengths were prepared by the non-isocyanate approach from 1,4-diaminobutane or 1,6-diaminohexane with ethylene cyclic carbonate at room temperature without the aid of a catalyst. Different weight percentages of hexa(methoxymethyl) melamine (HMMM) crosslinker was [...] Read more.

In this work, two urethane diols with different middle chain lengths were prepared by the non-isocyanate approach from 1,4-diaminobutane or 1,6-diaminohexane with ethylene cyclic carbonate at room temperature without the aid of a catalyst. Different weight percentages of hexa(methoxymethyl) melamine (HMMM) crosslinker was mixed with urethane diols then cured under elevated temperature to generate the melamine-formaldehyde (MF) coating films. Two different linear diols without urethane linkage were chosen to crosslink with HMMM as the control group. The mechanical properties of these MF coatings were investigated by tensile test, adhesion test, and conical mandrel bend test. It was found that coatings incorporated with urethane diols exhibited enhanced mechanical properties and flexibility. These properties were also influenced by the weight percentage of HMMM crosslinker. This study provided a facile non-isocyanate way to produce urethane diols and successfully applied them in MF coating. Full article

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

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18 pages, 5591 KiB

Open AccessArticle

Cohesive Zone Modeling of the Elastoplastic and Failure Behavior of Polymer Nanoclay Composites

by Uraching Chowdhury and Xiang-Fa Wu

J. Compos. Sci. 2021, 5(5), 131; https://doi.org/10.3390/jcs5050131 - 14 May 2021

Cited by 10 | Viewed by 3295

Abstract

Cohesive zone model (CZM) is commonly used to deal with the nonlinear zone ahead of crack tips in materials with elastoplastic deformation behavior. This model is capable of predicting the behavior of crack initiation and growth. In this paper, CZM-based finite element analysis [...] Read more.

Cohesive zone model (CZM) is commonly used to deal with the nonlinear zone ahead of crack tips in materials with elastoplastic deformation behavior. This model is capable of predicting the behavior of crack initiation and growth. In this paper, CZM-based finite element analysis (FEA) is performed to examine the effects of processing parameters (i.e., the clay nanoparticle volume fraction and aspect ratio) in the mechanical behaviors of a polymeric matrix reinforced with aligned clay nanoparticles. The polymeric matrix is treated as an ideal elastoplastic solid with isotropic hardening behavior, whereas the clay nanoparticles are simplified as stiff, linearly elastic platelets. Representative volume elements (RVEs) of the resulting polymer nanoclay composites (PNCs) are adopted for FEA with the clay nanoparticle distributions to follow both stack and stagger configurations, respectively. In the study, four volume fractions (Vf = 2.5%, 5%, 7.5% and 10%) and four aspect ratios (ρ = 5, 7.5, 10, and 20) of the clay nanoparticles in the PNCs are considered. Detailed computational results show that either increasing volume fraction or aspect ratio of the clay nanoparticles enhances the effective tensile strength and stiffness of the PNCs. The progressive debonding process of the clay nanoparticles in the polymeric resin was predicted, and the debonding was initiated in the linearly elastic loading range. The numerical results also show that PNCs with stagger nanoparticle configuration demonstrate slightly higher values of the engineering stress than those based on the stack nanoparticle configuration at both varying volume fractions and aspect ratios of the clay nanoparticles. In addition, CZM-based FEA predicts a slightly lower stress field around the clay particles in PNCs than that without integration of CZM. The present computational studies are applicable for processing PNCs with controllable mechanical properties, especially the control of the key processing parameters of PNCs, i.e., the volume fraction and aspect ratio of the clay nanoparticles. Full article

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

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19 pages, 6325 KiB

Open AccessArticle

Comparative Study of the Reinforcement Type Effect on the Thermomechanical Properties and Burning of Epoxy-Based Composites

by Kamila Salasinska, Mateusz Barczewski, Joanna Aniśko, Aleksander Hejna and Maciej Celiński

J. Compos. Sci. 2021, 5(3), 89; https://doi.org/10.3390/jcs5030089 - 23 Mar 2021

Cited by 11 | Viewed by 2382

Abstract

Aramid (AF), glass (GF), carbon (CF), basalt (BF), and flax (FF) fibers in the form of fabrics were used to produce the composites by hand-lay up method. The use of fabrics of similar grammage for composites’ manufacturing allowed for a comprehensive comparison of [...] Read more.

Aramid (AF), glass (GF), carbon (CF), basalt (BF), and flax (FF) fibers in the form of fabrics were used to produce the composites by hand-lay up method. The use of fabrics of similar grammage for composites’ manufacturing allowed for a comprehensive comparison of the properties of the final products. The most important task was to prepare a complex setup of mechanical and thermomechanical properties, supplemented by fire behavior analysis, and discuss both characteristics in their application range. The mechanical properties were investigated using tensile and flexural tests, as well as impact strength measurement. The investigation was improved by assessing thermomechanical properties under dynamic deformation conditions (dynamic mechanical–thermal analysis (DMTA)). All products were subjected to a fire test carried out using a cone calorimeter (CC). Full article

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

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10 pages, 3674 KiB

Open AccessArticle

Numerical Investigation of Residual Stresses in Welded Thermoplastic CFRP Structures

by Lukas Nagel, Alexander Herwig, Carsten Schmidt and Peter Horst

J. Compos. Sci. 2021, 5(2), 45; https://doi.org/10.3390/jcs5020045 - 2 Feb 2021

Cited by 9 | Viewed by 3409

Abstract

Using thermoplastics as the matrix in carbon fiber-reinforced polymers (CFRP) offers the possibility to make use of welded joints, which results in weight savings compared to conventional joining methods using mechanical fasteners. In this paper, the resulting temperature distribution in the material due [...] Read more.

Using thermoplastics as the matrix in carbon fiber-reinforced polymers (CFRP) offers the possibility to make use of welded joints, which results in weight savings compared to conventional joining methods using mechanical fasteners. In this paper, the resulting temperature distribution in the material due to resistance welding is investigated by transient finite element (FE) simulations. To examine the effects on the component structure, a numerical modeling approach is created, which allows determining the residual stresses caused by the welding process. It is shown that the area of the structure, especially near the joining zone, is highly affected by the process, especially in terms of residual stresses. In particular, the stresses perpendicular to the fiber direction show failure relevant values up to a maximum of 221 MPa, which might lead to the formation of microcracks in the matrix. In turn, that is assumed to be critical in terms of the fatigue of welded composite structures. Thus, the suggested modeling approach provides residual stresses that can be used to determine their effects on the strength, structural stability, and fatigue of such composite structures. In a subsequent step, these findings could play an important role in the design process of thermoplastic composite structures. Full article

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

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21 pages, 5976 KiB

Open AccessArticle

Flexural Performance of FRP-Reinforced Geopolymer Concrete Beam

by Janeshka Goonewardena, Kazem Ghabraie and Mahbube Subhani

J. Compos. Sci. 2020, 4(4), 187; https://doi.org/10.3390/jcs4040187 - 15 Dec 2020

Cited by 14 | Viewed by 4381

Abstract

Fibre-reinforced polymer (FRP) rebar and geopolymer concrete (GPC) are relatively new construction materials that are now been increasingly used in the construction sectors. Both materials exhibit superior structural and durability properties that also make them a sustainable alternative solution. Due to the absence [...] Read more.

Fibre-reinforced polymer (FRP) rebar and geopolymer concrete (GPC) are relatively new construction materials that are now been increasingly used in the construction sectors. Both materials exhibit superior structural and durability properties that also make them a sustainable alternative solution. Due to the absence of any design standard for an FRP-reinforced GPC beam, it is important to validate the efficacy of available standards and literature related to other materials, e.g., FRP-reinforced conventional concrete or GPC alone. Four theories/design standards are considered for this comparison—ACI440.1R-15, CAN/CSA S806-12, parabolic stress block theory, and equivalent rectangular stress block theory for GPC under compression. The accuracy of these four approaches is also examined by studying the flexural performance of both the glass FRP (GFRP) and carbon FRP (CFRP). The FRP-reinforced beams are designed against the actual load they will be subjected to in a real-world scenario. It is concluded that parabolic stress block theory over-estimates the capacity, whereas CSA S806-12 yields the most accurate and conservative results. In addition, the flexural performance of the FRP-reinforced beams is evaluated in terms of ultimate, cracking, and service moment capacity, along with serviceable, ultimate, and residual deflection. Full article

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

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22 pages, 2990 KiB

Open AccessArticle

Experimental Study of the Probabilistic Fatigue Residual Strength of a Carbon Fiber-Reinforced Polymer Matrix Composite

by Xiang-Fa Wu and Oksana Zholobko

J. Compos. Sci. 2020, 4(4), 173; https://doi.org/10.3390/jcs4040173 - 21 Nov 2020

Cited by 9 | Viewed by 3622

Abstract

Degradation of the mechanical properties of fiber-reinforced polymer matrix composites (PMCs) subjected to cyclic loading is crucial to the long-term load-carrying capability of PMC structures in practice. This paper reports the experimental study of fatigue residual tensile strength and its probabilistic distribution in [...] Read more.

Degradation of the mechanical properties of fiber-reinforced polymer matrix composites (PMCs) subjected to cyclic loading is crucial to the long-term load-carrying capability of PMC structures in practice. This paper reports the experimental study of fatigue residual tensile strength and its probabilistic distribution in a carbon fiber-reinforced PMC laminate made of unidirectional (UD) carbon-fiber/epoxy prepregs (Hexcel T2G190/F263) with the ply layup [0/±45/90]_S after certain cycles of cyclic loading. The residual tensile strengths of the PMC laminates after cyclic loading of 1 (quasistatic), 2000, and 10,000 cycles were determined. Statistical analysis of the experimental data shows that the fatigue residual tensile strength of the PMC laminate follows a two-parameter Weibull distribution model with the credibility ≥ 95%. With increasing fatigue cycles, the mean value of the fatigue residual strength of the PMC specimens decreased while its deviation increased. A free-edge stress model is further adopted to explain the fatigue failure initiation of the composite laminate. The present experimental study is valuable for understanding the fatigue durability of PMC laminates as well as reliable design and performance prediction of composite structures. Full article

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

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12 pages, 2291 KiB

Open AccessArticle

Mechanical Properties of a Unidirectional Basalt-Fiber/Epoxy Composite

by David Plappert, Georg C. Ganzenmüller, Michael May and Samuel Beisel

J. Compos. Sci. 2020, 4(3), 101; https://doi.org/10.3390/jcs4030101 - 29 Jul 2020

Cited by 41 | Viewed by 6714

Abstract

High-performance composites based on basalt fibers are becoming increasingly available. However, in comparison to traditional composites containing glass or carbon fibers, their mechanical properties are currently less well known. In particular, this is the case for laminates consisting of unidirectional plies of continuous [...] Read more.

High-performance composites based on basalt fibers are becoming increasingly available. However, in comparison to traditional composites containing glass or carbon fibers, their mechanical properties are currently less well known. In particular, this is the case for laminates consisting of unidirectional plies of continuous basalt fibers in an epoxy polymer matrix. Here, we report a full quasi-static characterization of the properties of such a material. To this end, we investigate tension, compression, and shear specimens, cut from quality autoclave-cured basalt composites. Our findings indicate that, in terms of strength and stiffness, unidirectional basalt fiber composites are comparable to, or better than epoxy composites made from E-glass fibers. At the same time, basalt fiber composites combine low manufacturing costs with good recycling properties and are therefore well suited to a number of engineering applications. Full article

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

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15 pages, 6959 KiB

Open AccessArticle

Miniaturised Rod-Shaped Polymer Structures with Wire or Fibre Reinforcement—Manufacturing and Testing

by Michael Kucher, Martin Dannemann, Ansgar Heide, Anja Winkler and Niels Modler

J. Compos. Sci. 2020, 4(3), 84; https://doi.org/10.3390/jcs4030084 - 27 Jun 2020

Cited by 1 | Viewed by 2716

Abstract

Rod-shaped polymer-based composite structures are applied to a wide range of applications in the process engineering, automotive, aviation, aerospace and marine industries. Therefore, the adequate knowledge of manufacturing methods is essential, covering the fabrication of small amounts of specimens as well as the [...] Read more.

Rod-shaped polymer-based composite structures are applied to a wide range of applications in the process engineering, automotive, aviation, aerospace and marine industries. Therefore, the adequate knowledge of manufacturing methods is essential, covering the fabrication of small amounts of specimens as well as the low-cost manufacturing of high quantities of solid rods using continuous manufacturing processes. To assess the different manufacturing methods and compare the resulting quality of the semi-finished products, the cross-sectional and bending properties of rod-shaped structures obtained from a thermoplastic micro-pultrusion process, conventional fibre reinforced epoxy resin-based solid rods and fibre reinforced thermoplastic polymers manufactured by means of an implemented shrink tube consolidation process, were statistically analysed. Using the statistical method one-way analysis of variance (ANOVA), the differences between groups were calculated. The statistical results show that the flexural moduli of carbon fibre reinforced polymers were statistically significantly higher than the modulus of all other investigated specimens (probability value ). The discontinuous shrink tube consolidation process resulted in specimens with a smooth outer contour and a high level of roundness. However, this process was recommended for the manufacturing of small amounts of specimens. In contrast, the pultrusion process allowed the manufacturing of high amounts of semi-finished products; however, it requires a more extensive process controlling and manufacturing equipment. Full article

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

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19 pages, 8594 KiB

Open AccessArticle

Characterization of Enhanced ITZ in Engineered Polypropylene Fibers for Bond Improvement

by Rishabh Bajaj, Boyu Wang and Rishi Gupta

J. Compos. Sci. 2020, 4(2), 53; https://doi.org/10.3390/jcs4020053 - 11 May 2020

Cited by 9 | Viewed by 3727

Abstract

The interfacial transition zone (ITZ) is well known to be a zone of high porosity and lesser strength and is the weak zone in the fiber-reinforced matrix. This study aims to evaluate the improvement in the bonding between engineered polypropylene fibers and the [...] Read more.

The interfacial transition zone (ITZ) is well known to be a zone of high porosity and lesser strength and is the weak zone in the fiber-reinforced matrix. This study aims to evaluate the improvement in the bonding between engineered polypropylene fibers and the surrounding mortar matrix. The improvement was implemented by modifying the ITZ, which develops between the fibers and the cementitious matrix. Two commercially available repair materials have been used in this study, Mix M and Mix P. Mix M served as the base material for the prepared fibers, whereas Mix P is a fiber-reinforced repair mortar and provides a comparison. A total of six types of mixes have been investigated. The improved bonding is tested by coating the polypropylene fibers with supplementary cementitious materials (SCM) using an innovative patented concept. In this study, silica fume and metakaolin are used as the SCM because of their fine size and pozzolanic capacity. The study involves multiple items of investigation, including mechanical tests such as compressive strength, direct tensile strength, and three-point bending tests. Energy-dispersive X-ray spectroscopy (EDS) of the different mixes helped in evaluating and analyzing the ITZ between the fiber and matrix. Full article

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

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Review

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24 pages, 6253 KiB

Open AccessReview

An Overview of the Design of Chitosan-Based Fiber Composite Materials

by Chen Xue and Lee D. Wilson

J. Compos. Sci. 2021, 5(6), 160; https://doi.org/10.3390/jcs5060160 - 17 Jun 2021

Cited by 17 | Viewed by 3100

Abstract

Chitosan composite fibrous materials continue to generate significant interest for wastewater treatment, food packaging, and biomedical applications. This relates to the relatively high surface area and porosity of such fibrous chitosan materials that synergize with their unique physicochemical properties. Various methods are involved [...] Read more.

Chitosan composite fibrous materials continue to generate significant interest for wastewater treatment, food packaging, and biomedical applications. This relates to the relatively high surface area and porosity of such fibrous chitosan materials that synergize with their unique physicochemical properties. Various methods are involved in the preparation of chitosan composite fibrous materials, which include the modification of the biopolymer that serve to alter the solubility of chitosan, along with post-treatment of the composite materials to improve the water stability or to achieve tailored functional properties. Two promising methods to produce such composite fibrous materials involve freeze-drying and electrospinning. Future developments of such composite fibrous materials demands an understanding of the various modes of preparation and methods of structural characterization of such materials. This review contributes to an understanding of the structure–property relationships of composite fibrous materials that contain chitosan, along with an overview of recent advancements concerning their preparation. Full article

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

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13 pages, 1100 KiB

Open AccessReview

A Review on Mechanical Properties of Natural Fibre Reinforced Polymer Composites under Various Strain Rates

by Tan Ke Khieng, Sujan Debnath, Ernest Ting Chaw Liang, Mahmood Anwar, Alokesh Pramanik and Animesh Kumar Basak

J. Compos. Sci. 2021, 5(5), 130; https://doi.org/10.3390/jcs5050130 - 13 May 2021

Cited by 29 | Viewed by 5354

Abstract

With the lightning speed of technological evolution, the demand for high performance yet sustainable natural fibres reinforced polymer composites (NFPCs) are rising. Especially a mechanically competent NFPCs under various loading conditions are growing day by day. However, the polymers mechanical properties are strain-rate [...] Read more.

With the lightning speed of technological evolution, the demand for high performance yet sustainable natural fibres reinforced polymer composites (NFPCs) are rising. Especially a mechanically competent NFPCs under various loading conditions are growing day by day. However, the polymers mechanical properties are strain-rate dependent due to their viscoelastic nature. Especially for natural fibre reinforced polymer composites (NFPCs) which the involvement of filler has caused rather complex failure mechanisms under different strain rates. Moreover, some uneven micro-sized natural fibres such as bagasse, coir and wood were found often resulting in micro-cracks and voids formation in composites. This paper provides an overview of recent research on the mechanical properties of NFPCs under various loading conditions-different form (tensile, compression, bending) and different strain rates. The literature on characterisation techniques toward different strain rates, composite failure behaviours and current challenges are summarised which have led to the notion of future study trend. The strength of NFPCs is generally found grow proportionally with the strain rate up to a certain degree depending on the fibre-matrix stress-transfer efficiency. The failure modes such as embrittlement and fibre-matrix debonding were often encountered at higher strain rates. The natural filler properties, amount, sizes and polymer matrix types are found to be few key factors affecting the performances of composites under various strain rates whereby optimally adjust these factors could maximise the fibre-matrix stress-transfer efficiency and led to performance increases under various loading strain rates. Full article

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

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15 pages, 2187 KiB

Open AccessEditor’s ChoiceReview

Modeling Strategies of Finite Element Simulation of Reinforced Concrete Beams Strengthened with FRP: A Review

by M. Z. Naser, Rami Antoun Hawileh and Jamal Abdalla

J. Compos. Sci. 2021, 5(1), 19; https://doi.org/10.3390/jcs5010019 - 8 Jan 2021

Cited by 62 | Viewed by 9520

Abstract

Fiber-reinforced polymer (FRP) composites do not only possess superior mechanical properties, but can also be easy to tailor, install, and maintain. As such, FRPs offer novel and attractive solutions to facilitate strengthening and/or retrofitting of aging, weakened, and upgraded structures. Despite the availability [...] Read more.

Fiber-reinforced polymer (FRP) composites do not only possess superior mechanical properties, but can also be easy to tailor, install, and maintain. As such, FRPs offer novel and attractive solutions to facilitate strengthening and/or retrofitting of aging, weakened, and upgraded structures. Despite the availability of general code provisions, the design and analysis of FRP-strengthened concrete structures is both tedious and complex—especially in scenarios associated with unique loading conditions. As such, designers often leverage advanced finite element (FE) simulation as a mean to understand and predict the performance of FRP-strengthened structures. In order to narrow this knowledge gap, this paper details suitable strategy for developing and carrying out advanced FE simulations on FRP-strengthened concrete structures. The paper also covers techniques related to simulating adhesives (bonding agents), material constitutive properties and plasticity (cracking/crushing of concrete, yielding of steel reinforcement, and delamination of FRP laminates), as well as different material types of FRP (CFRP, GFRP, and their hybrid combinations), and FRP strengthening systems (sheets, plates, NSM, and rods) under various loading conditions including ambient, earthquake, and fire. The principles, thumb rules, and findings of this work can be of interest to researchers, practitioners, and students. Full article

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

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