Polymers

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4 pages, 215 KiB

Open AccessEditorial

Polymer Composite Analysis and Characterization

by Francesc X. Espinach and Quim Tarrés

Polymers 2023, 15(8), 1812; https://doi.org/10.3390/polym15081812 - 7 Apr 2023

Viewed by 3419

Abstract

In the original article [...] Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

Research

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19 pages, 3972 KiB

Open AccessArticle

Effect of the Surface Functionalization of Graphene and MWCNT on the Thermodynamic, Mechanical and Electrical Properties of the Graphene/MWCNT-PVDF Nanocomposites

by Mamdouh A. Al-Harthi and Manwar Hussain

Polymers 2022, 14(15), 2976; https://doi.org/10.3390/polym14152976 - 22 Jul 2022

Cited by 13 | Viewed by 2040

Abstract

The nanocomposites of poly(vinylidene fluoride) (PVDF) with pristine graphene nanoflakes (GNF) and a multi-wall carbon nanotube (MWCNT) were prepared by the solution casting method. Additionally, the GNF and MWCNT were functionalized by acid treatment, and nanocomposites of the acid-treated MWCNT/GNF and PVDF were [...] Read more.

The nanocomposites of poly(vinylidene fluoride) (PVDF) with pristine graphene nanoflakes (GNF) and a multi-wall carbon nanotube (MWCNT) were prepared by the solution casting method. Additionally, the GNF and MWCNT were functionalized by acid treatment, and nanocomposites of the acid-treated MWCNT/GNF and PVDF were prepared in the same method. The effect of the acid treatment of MWCNT and GNF on the mechanical, thermal and thermo-oxidative stability and the thermal conductivity of the MWCNT/GNF-PVDF nanocomposites was evaluated, and the results were compared with the untreated MWCNT/GNF-PVDF nanocomposites. In both cases, the amount of GNF and MWCNT was varied to observe and compare their thermal and mechanical properties. The functionalization of the GNF or MWCNT resulted in the change in the crystallization and melting behavior of the nanocomposites, as confirmed by the differential scanning calorimetry analysis. The addition of the functionalized GNF/MWCNT led to the improved thermal stability of the PVDF nanocomposites compared to that of the non-functionalized GNF/MWCNT-PVDF nanocomposites. The thermal and electrical conductivity of the functionalized and non-functionalized GNF/MWCNT-PVDF composites were also measured and compared. The functional groups, crystal structure, microstructure and morphology of the nanocomposites were characterized by Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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13 pages, 4010 KiB

Open AccessArticle

Morphology-Controlled Synthesis of Polyphosphazene-Based Micro- and Nano-Materials and Their Application as Flame Retardants

by Yuanzhao Zhu, Wei Wu, Tong Xu, Hong Xu, Yi Zhong, Linping Zhang, Yimeng Ma, Xiaofeng Sui, Bijia Wang, Xueling Feng and Zhiping Mao

Polymers 2022, 14(10), 2072; https://doi.org/10.3390/polym14102072 - 19 May 2022

Cited by 6 | Viewed by 2268

Abstract

Common flame retardants, such as halogen-based materials, are being phased-out owing to their harmful environmental and health effects. We prepared poly-(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) microspheres, nanotubes, capsicum-like nanotubes, and branched nanotubes as flame retardants. An increase in reaction temperature changed the morphology from nanotubes to [...] Read more.

Common flame retardants, such as halogen-based materials, are being phased-out owing to their harmful environmental and health effects. We prepared poly-(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) microspheres, nanotubes, capsicum-like nanotubes, and branched nanotubes as flame retardants. An increase in reaction temperature changed the morphology from nanotubes to microspheres. A PZS shape had a positive effect on the flame retardancy of polyethylene terephthalate (PET). The PZS with a capsicum-like nanotube morphology had the best flame retardancy, and the PET limiting oxygen index increased from 25.2% to 34.4%. The flame retardancy capability was followed by PZS microspheres (33.1%), branched nanotubes (32.8%), and nanotubes (32.5%). The capsicum-like nanotubes promote the formation of highly dense and continuous carbon layers, and they release a non-combustible gas (CO₂). This study confirms polyphosphazene-based flame retardants as viable and environmentally-friendly alternatives to common flame retardants. It also presents a novel and facile design and synthesis of morphology-controlled nanomaterials with enhanced flame retardant properties. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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16 pages, 11452 KiB

Open AccessArticle

UV-LED Curable Acrylic Films Containing Phosphate Glass Powder: Effect of the Filler Loading on the Thermal, Optical, Mechanical and Flame Retardant Properties

by Diego Pugliese and Giulio Malucelli

Polymers 2022, 14(9), 1899; https://doi.org/10.3390/polym14091899 - 6 May 2022

Cited by 3 | Viewed by 2100

Abstract

In this work, we thoroughly investigate the effects of the incorporation of a phosphate glass micrometric powder on the morphology, as well as on the thermal, optical, mechanical and flame retardant properties of UV-LED curable acrylic films. To this aim, the filler loading [...] Read more.

In this work, we thoroughly investigate the effects of the incorporation of a phosphate glass micrometric powder on the morphology, as well as on the thermal, optical, mechanical and flame retardant properties of UV-LED curable acrylic films. To this aim, the filler loading was changed within 10 and 50 wt.%. UV-LED initiated curing was selected as a fast and reliable system, as the standard UV-curing process was not suitable because of the presence of the glass powder that decreased the quantum efficiency during the UV exposure, hence preventing the transformation of the liquid system into a solid network. The glass powder slightly increased the glass transition temperature of the acrylic network, hence showing a limited effect on the chain segments mobility; besides, increasing filler loadings were responsible for a progressive decrease of the transparency of films, irrespective of a marginal effect on their refractive index. Conversely, the presence of increasing amounts of phosphate glass improved the thermal and thermo-oxidative stability of the cured products. Besides, phosphate glass was capable of remarkably enhancing the flame retardance of the acrylic network at 50 wt.% loading, which achieved self-extinction in vertical flame spread tests (and was V-0 rated). This formulation, as assessed by forced-combustion tests, also displayed a remarkable decrease of peak of Heat Release Rate and Total Heat Release (by 44 and 33%, respectively) and of Total Smoke Release and Specific Extinction Area (by 53 and 56%, respectively). Further, the filler promoted an increase of the stiffness and surface hardness of the films, at the expense of a decrease in ductility. All these findings may justify the potential use of these composite films as flame retardant coatings for different flammable substrates. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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10 pages, 2228 KiB

Open AccessArticle

Thermal Stability and Flammability Studies of MXene–Organic Hybrid Polystyrene Nanocomposites

by Zhuoran Zhang, Huaixuan Cao, Yufeng Quan, Rong Ma, Emily B. Pentzer, Micah J. Green and Qingsheng Wang

Polymers 2022, 14(6), 1213; https://doi.org/10.3390/polym14061213 - 17 Mar 2022

Cited by 24 | Viewed by 3639

Abstract

Polystyrene (PS) is widely used in the plastics industry, but the application range of PS is limited due to its inherently high flammability. A variety of two-dimensional (2D) nanomaterials have been reported to impart excellent flame retardancy to polymeric materials. In this study, [...] Read more.

Polystyrene (PS) is widely used in the plastics industry, but the application range of PS is limited due to its inherently high flammability. A variety of two-dimensional (2D) nanomaterials have been reported to impart excellent flame retardancy to polymeric materials. In this study, a 2D nanomaterial MXene–organic hybrid (O-Ti₃C₂) was applied to PS as a nanofiller. Firstly, the MXene nanosheets were prepared by acid etching, intercalation, and delamination of bulk MAX (Ti₃AlC₂) material. These exfoliated MXene nanosheets were then functionalized using a cationic surfactant to improve the dispersibility in DMF. Even with a small loading of functionalized O-Ti₃C₂ (e.g., 2 wt%), the resulting PS nanocomposite (PS/O-Ti₃C₂) showed good thermal stability and lower flammability evidenced by thermogravimetric analysis (TGA) and pyrolysis-combustion flow calorimetry (PCFC). The peak heat release rate (pHRR) was significantly reduced by 32% compared to the neat PS sample. In addition, we observed that the temperature at pHRR (T_pHRR) shifted to a higher temperature by 22 °C. By comparing the TGA and PCFC results between the PS/MAX and different weight ratios of PS/O-Ti₃C₂ nanocomposites, the thermal stability and 2D thermal- and mass-transfer barrier effect of MXene–organic hybrid nanosheets were revealed to play essential roles in delaying the polymer degradation. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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14 pages, 4348 KiB

Open AccessArticle

The Influence of Fly Ash on the Foaming Behavior and Flame Retardancy of Polyurethane Grouting Materials

by Sitong Zhang, Wenying Liu, Kaijie Yang, Wenwen Yu, Fengbo Zhu and Qiang Zheng

Polymers 2022, 14(6), 1113; https://doi.org/10.3390/polym14061113 - 10 Mar 2022

Cited by 8 | Viewed by 2661

Abstract

Polyurethane (PU) grouting material has been widely utilized to control water inrush in mining fields. However, the application has been limited by its high cost and poor flame retardancy. Here, we use the fly ash (FA), a waste from coal of the iron-making [...] Read more.

Polyurethane (PU) grouting material has been widely utilized to control water inrush in mining fields. However, the application has been limited by its high cost and poor flame retardancy. Here, we use the fly ash (FA), a waste from coal of the iron-making industry and power plants, as a partial replacement of conventional filler in PU grouting materials to reduce the production cost and the environmental pollution of FA. The surface-modified FA-filled PU (PU/FA) composites were prepared by room-temperature curing. The effects of FA contents (φ) on the structure, foaming behavior, thermal stability, mechanical properties, hydrophobic properties, and flammability of PU grouting materials were examined. Results showed that the higher the φ, the more porous the PU/FA composites are, resulting in a lower density and lower mechanical properties. The relationship between the compression modulus E and the density ρ of the PU/FA composites was E ∝ ρ^1.3. In addition, the surface-modified FA improved the compatibility between the hard and soft segment of PU in the PU/FA composite, giving the composites enhanced thermal stability, high hydrophobicity, and flammability resistance. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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14 pages, 4739 KiB

Open AccessArticle

Wider Potential Windows of Cellulose Multiwall Carbon Nanotube Fibers Leading to Qualitative Multifunctional Changes in an Organic Electrolyte

by Rudolf Kiefer, Fred Elhi, Anna-Liisa Peikolainen and Tarmo Tamm

Polymers 2021, 13(24), 4439; https://doi.org/10.3390/polym13244439 - 17 Dec 2021

Cited by 4 | Viewed by 2137

Abstract

The trend across the whole of society is to focus on natural and/or biodegradable materials such as cellulose (Cell) over synthetic polymers. Among other usage scenarios, Cell can be combined with electroactive components such as multiwall carbon nanotubes (CNT) to form composites, such [...] Read more.

The trend across the whole of society is to focus on natural and/or biodegradable materials such as cellulose (Cell) over synthetic polymers. Among other usage scenarios, Cell can be combined with electroactive components such as multiwall carbon nanotubes (CNT) to form composites, such as Cell-CNT fibers, for applications in actuators, sensors, and energy storage devices. In this work, we aim to show that by changing the potential window, qualitative multifunctionality of the composites can be invoked, in both electromechanical response as well as energy storage capability. Cell-CNT fibers were investigated in different potential ranges (0.8 V to −0.3 V, 0.55 V to −0.8 V, 1 V to −0.8 V, and 1.5 V to −0.8 V), revealing the transfer from cation-active to anion-active as the potential window shifted towards more positive potentials. Moreover, increasing the driving frequency also shifts the mode from cation- to anion-active. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy were conducted to determine the ion species participating in charge compensation under different conditions. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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14 pages, 5436 KiB

Open AccessArticle

The Thermo-Oxidative Behavior of Cotton Coated with an Intumescent Flame Retardant Glycine-Derived Polyamidoamine: A Multi-Technique Study

by Claudia Forte, Jenny Alongi, Alessandro Beduini, Silvia Borsacchi, Lucia Calucci, Federico Carosio, Paolo Ferruti and Elisabetta Ranucci

Polymers 2021, 13(24), 4382; https://doi.org/10.3390/polym13244382 - 14 Dec 2021

Cited by 14 | Viewed by 2234

Abstract

Linear polyamidoamines (PAAs) derived from the polyaddition of natural α-amino acids and N,N′-methylene bis(acrylamide) are intumescent flame retardants for cotton. Among them, the glycine-derived M-GLY extinguished the flame in horizontal flame spread tests at 4% by weight add-on. This paper [...] Read more.

Linear polyamidoamines (PAAs) derived from the polyaddition of natural α-amino acids and N,N′-methylene bis(acrylamide) are intumescent flame retardants for cotton. Among them, the glycine-derived M-GLY extinguished the flame in horizontal flame spread tests at 4% by weight add-on. This paper reports on an extensive study aimed at understanding the molecular-level transformations of M-GLY-treated cotton upon heating in air at 300 °C, 350 °C and 420 °C. Thermogravimetric analysis (TGA) identified different thermal-oxidative decomposition stages and, coupled to Fourier transform infrared spectroscopy, allowed the volatile species released upon heating to be determined, revealing differences in the decomposition pattern of treated and untreated cotton. XPS analysis of the char residues of M-GLY-treated cotton revealed the formation of aromatic nanographitic char at lower temperature with respect to untreated cotton. Raman spectroscopy of the char residues provided indications on the degree of graphitization of treated and untreated cotton at the three reference temperatures. Solid state ¹³C nuclear magnetic resonance spectroscopy (NMR) provided information on the char structure as a function of the treatment temperature, clearly indicating that M-GLY favors the carbonization of cotton with the formation of more highly condensed aromatic structures. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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17 pages, 5464 KiB

Open AccessArticle

Preparation and Finite Element Analysis of Fly Ash/HDPE Composites for Large Diameter Bellows

by Angxuan Wu, Lan Jia, Wenwen Yu, Fengbo Zhu, Fuyong Liu, Yanqin Wang, Guoyun Lu, Shuhao Qin, Dongyang Gao, Hua Wang, Xiaogang Wu and Qiang Zheng

Polymers 2021, 13(23), 4204; https://doi.org/10.3390/polym13234204 - 30 Nov 2021

Cited by 4 | Viewed by 2582

Abstract

In recent years, buried bellows have often had safety accidents such as pipeline bursts and ground subsidence due to the lack of adequate mechanical properties and other quality problems. In order to improve the mechanical properties of bellows, fly ash (FA) was used [...] Read more.

In recent years, buried bellows have often had safety accidents such as pipeline bursts and ground subsidence due to the lack of adequate mechanical properties and other quality problems. In order to improve the mechanical properties of bellows, fly ash (FA) was used as a reinforced filler in high density polyethylene (HDPE) to develop composites. The FA was surface treated with a silane coupling agent and HDPE-g-maleic anhydride was used as compatibilizer. Dumbbell-shaped samples were prepared via extrusion blending and injection molding. The cross-section morphology, thermal stability and mechanical properties of the composites were studied. It was observed that when 10% modified FA and 5% compatibilizer were added to HDPE, the tensile yield strength and tensile breaking strength of the composites were nearly 30.2% and 40.4% higher than those of pure HDPE, respectively, and the Young’s modulus could reach 1451.07 MPa. In addition, the ring stiffness of the bellows was analyzed using finite element analysis. Compared with a same-diameter bellows fabricated from common commercially available materials, the ring stiffness increased by nearly 23%. The preparation method of FA/HDPE is simple, efficient, and low-cost. It is of great significance for the popularization of high-performance bellows and the high value-added utilization of FA. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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14 pages, 12863 KiB

Open AccessArticle

Effective Young’s Modulus Estimation of Natural Fibers through Micromechanical Models: The Case of Henequen Fibers Reinforced-PP Composites

by Ferran Serra-Parareda, Fabiola Vilaseca, Roberto Aguado, Francesc X. Espinach, Quim Tarrés and Marc Delgado-Aguilar

Polymers 2021, 13(22), 3947; https://doi.org/10.3390/polym13223947 - 15 Nov 2021

Cited by 14 | Viewed by 2891

Abstract

In this study, Young’s modulus of henequen fibers was estimated through micromechanical modeling of polypropylene (PP)-based composites, and further corroborated through a single filament tensile test after applying a correction method. PP and henequen strands, chopped to 1 mm length, were mixed in [...] Read more.

In this study, Young’s modulus of henequen fibers was estimated through micromechanical modeling of polypropylene (PP)-based composites, and further corroborated through a single filament tensile test after applying a correction method. PP and henequen strands, chopped to 1 mm length, were mixed in the presence of maleic anhydride grafted polypropylene (MAPP). A 4 wt.% of MAPP showed an effective enhancement of the interfacial adhesion. The composites were mold-injected into dog-bone specimens and tensile tested. The Young’s modulus of the composites increased steadily and linearly up to 50 wt.% of fiber content from 1.5 to 6.4 GPa, corresponding to a 327% increase. Certainly, henequen fibers showed a comparable stiffening capacity of PP composites than glass fibers. The intrinsic Young’s modulus of the fibers was predicted through well established models such as Hirsch or Tsai-Pagano, yielding average values of 30.5 and 34.6 GPa, respectively. The single filament test performed to henequen strands resulted in values between 16 and 27 GPa depending on the gauge length, although, after applying a correction method, a Young’s modulus of 33.3 GPa was obtained. Overall, the present work presents the great potential for henequen fibers as PP reinforcement. Moreover, relationships between micromechanics models and filament testing to estimate Young’s modulus of the fibers were explored. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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21 pages, 55505 KiB

Open AccessArticle

Comparative Characterization of Hot-Pressed Polyamide 11 and 12: Mechanical, Thermal and Durability Properties

by Mohsen Bahrami, Juana Abenojar and Miguel Angel Martínez

Polymers 2021, 13(20), 3553; https://doi.org/10.3390/polym13203553 - 15 Oct 2021

Cited by 33 | Viewed by 5692

Abstract

Chemically speaking, polyamide 11 (PA11) and polyamide 12 (PA12) have a similar backbone, differing only in one carbon. From an origin point of view, PA11 is considered a bioplastic polyamide composed from renewable resources, compared to oil-based PA12. Each of them has a [...] Read more.

Chemically speaking, polyamide 11 (PA11) and polyamide 12 (PA12) have a similar backbone, differing only in one carbon. From an origin point of view, PA11 is considered a bioplastic polyamide composed from renewable resources, compared to oil-based PA12. Each of them has a number of advantages over the other, which makes their selection a challenging issue. Depending on the target application, diverse assessments and comparisons are needed to fulfill this mission. The current study addresses this research gap to characterize and compare PA11 and PA12 manufactured by the hot press technique in terms of their mechanical, thermal and durability properties for the first time, demonstrating their potential for future works as matrices in composite materials. In this regard, different characterization techniques are applied to the hot-pressed polymer sheets, including X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The mechanical performance of the PA11 and PA12 sheets is compared based on tensile tests and shore hardness measurement. The durability behavior of these two polyamides is evaluated in water and relative humidity conditions at different aging times. The experimental results show the ductile behavior of PA12 with respect to the quasi-brittle PA11. Both have a relatively small water and moisture gain: 1.5 wt% and 0.8 wt%, respectively. The higher crystallinity of PA12 (2.1 times more than PA11) with γ-phase is one of the leading parameters to achieve better mechanical and durability properties. The FTIR spectra displayed slight acid hydrolysis. Accordingly, absorbed water or moisture does not cause plasticization; thus, neither hardness nor dimension changes. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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20 pages, 6397 KiB

Open AccessArticle

The Effect of Graphene Oxide and SEBS-g-MAH Compatibilizer on Mechanical and Thermal Properties of Acrylonitrile-Butadiene-Styrene/Talc Composite

by Fatin Najwa Joynal Abedin, Hamidah Abdul Hamid, Abbas F. M. Alkarkhi, Salem S. Abu Amr, Nor Afifah Khalil, Ahmad Naim Ahmad Yahaya, Md. Sohrab Hossain, Azman Hassan and Muzafar Zulkifli

Polymers 2021, 13(18), 3180; https://doi.org/10.3390/polym13183180 - 19 Sep 2021

Cited by 9 | Viewed by 2967

Abstract

In this study, acrylonitrile butadiene styrene (ABS)/talc/graphene oxide/SEBS-g-MAH (ABS/Talc/GO/SEBS-g-MAH) and acrylonitrile butadiene styrene/graphene oxide/SEBS-g-MAH (ABS/GO/SEBS-g-MAH) composites were isolated with varying graphene oxide (0.5 to 2.0 phr) as a filler and SEBS-g-MAH as a compatibilizer (4 to 8 phr), with an ABS:talc ratio of [...] Read more.

In this study, acrylonitrile butadiene styrene (ABS)/talc/graphene oxide/SEBS-g-MAH (ABS/Talc/GO/SEBS-g-MAH) and acrylonitrile butadiene styrene/graphene oxide/SEBS-g-MAH (ABS/GO/SEBS-g-MAH) composites were isolated with varying graphene oxide (0.5 to 2.0 phr) as a filler and SEBS-g-MAH as a compatibilizer (4 to 8 phr), with an ABS:talc ratio of 90:10 by percentage. The influences of graphene oxide and SEBS-g-MAH loading in ABS/talc composites were determined on the mechanical and thermal properties of the composites. It was found that the incorporation of talc reduces the stiffness of composites. The analyses of mechanical and thermal properties of composites revealed that the inclusion of graphene oxide as a filler and SEBS-g-MAH as a compatibilizer in the ABS polymer matrix significantly improved the mechanical and thermal properties. ABS/talc was prepared through melt mixing to study the fusion characteristic. The mechanical properties showed an increase of 30%, 15%, and 90% in tensile strength (TS), flexural strength (FS), and flexural modulus (FM), respectively. The impact strength (IS) resulted in comparable properties to ABS, and it was better than the ABS/talc composite due to the influence of talc in the composite that stiffens and reduces the extensibility of plastic. The incorporation of GO and SEBS-g-MA also shows a relatively higher thermal stability in both composites with and without talc. The finding of the present study reveals that the graphene oxide and SEBS-g-MAH could be utilized as a filler and a compatibilizer in ABS/talc composites to enhance the thermo-mechanical stability because of the superior interfacial adhesion between the matrix and filler. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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11 pages, 3507 KiB

Open AccessArticle

Effect of Core Architecture on Charpy Impact and Compression Properties of Tufted Sandwich Structural Composites

by Chen Chen, Peng Wang and Xavier Legrand

Polymers 2021, 13(10), 1665; https://doi.org/10.3390/polym13101665 - 20 May 2021

Cited by 8 | Viewed by 2538

Abstract

This study presents a novel sandwich structure that replaces the polypropylene (PP) foam core with a carbon fiber non-woven material in the tufting process and the liquid resin infusion (LRI) process. An experimental investigation was conducted into the flatwise compression properties and Charpy [...] Read more.

This study presents a novel sandwich structure that replaces the polypropylene (PP) foam core with a carbon fiber non-woven material in the tufting process and the liquid resin infusion (LRI) process. An experimental investigation was conducted into the flatwise compression properties and Charpy impact resistance of sandwich composites. The obtained results validate an enhancement to the mechanical properties due to the non-woven core and tufting yarns. Compared to samples with a pure foam core and samples without tufting threads, the compressive strength increased by 45% and 86%, respectively. The sample with a non-woven layer and tufting yarns had the highest Charpy absorbed energy (23.85 Kj/m²), which is approximately 66% higher than the samples without a non-woven layer and 90% higher than the samples without tufting yarns. Due to the buckling of the resin cylinders in the Z-direction that occurred in all of the different sandwich samples during the compression test, the classical buckling theory was adopted to analyze the differences between the results. The specific properties of the weight gains are discussed in this paper. The results show that the core layers have a negative effect on impact resistance. Nevertheless, the addition of tufting yarns presents an obvious benefit to all of the specific properties. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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12 pages, 2871 KiB

Open AccessArticle

The Use of Laminates of Commercially Available Fabrics for Anti-Stab Body-Armor

by Nguyen Quang Khuyen, Phan Vu Duc Han, Ngoc Tuan Nguyen, Quoc Bao Le, Madis Harjo, Gholamreza Anbarjafari, Rudolf Kiefer and Tarmo Tamm

Polymers 2021, 13(7), 1077; https://doi.org/10.3390/polym13071077 - 29 Mar 2021

Cited by 11 | Viewed by 2849

Abstract

Modern personal protective armor has been generally based on the Kevlar fabrics, with the main goal to offer defense against bullets. In addition to the high cost and poor processability, Kevlar has the disadvantage of limited stab-proofing capability. On the other hand, a [...] Read more.

Modern personal protective armor has been generally based on the Kevlar fabrics, with the main goal to offer defense against bullets. In addition to the high cost and poor processability, Kevlar has the disadvantage of limited stab-proofing capability. On the other hand, a large number of crimes involving deadly injures represent knife attacks. Our goal in this work was to investigate composites based on traditional commercially available fabrics of linen and silk, using different adhesives-polymers for forming laminates. The silk composites also contained different amounts of in-woven polyester. Three different water-based adhesives of polyurethane, urea formaldehyde and polyvinyl alcohol were considered. It was found, that besides the strength of the fabrics themselves, the adhesives polymers played a crucial role in the obtained performance of the laminates. The laminates were characterized in their mechanical properties, as well as with scanning electron microscopy and FTIR spectroscopy. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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16 pages, 4688 KiB

Open AccessArticle

Experimental and Numerical Analyses on the Buckling Characteristics of Woven Flax/Epoxy Laminated Composite Plate under Axial Compression

by Venkatachalam Gopalan, Vimalanand Suthenthiraveerappa, Jefferson Stanley David, Jeyanthi Subramanian, A. Raja Annamalai and Chun-Ping Jen

Polymers 2021, 13(7), 995; https://doi.org/10.3390/polym13070995 - 24 Mar 2021

Cited by 18 | Viewed by 2953

Abstract

The evolution of a sustainable green composite in various loadbearing structural applications tends to reduce pollution, which in turn enhances environmental sustainability. This work is an attempt to promote a sustainable green composite in buckling loadbearing structural applications. In order to use the [...] Read more.

The evolution of a sustainable green composite in various loadbearing structural applications tends to reduce pollution, which in turn enhances environmental sustainability. This work is an attempt to promote a sustainable green composite in buckling loadbearing structural applications. In order to use the green composite in various structural applications, the knowledge on its structural stability is a must. As the structural instability leads to the buckling of the composite structure when it is under an axial compressive load, the work on its buckling characteristics is important. In this work, the buckling characteristics of a woven flax/bio epoxy (WFBE) laminated composite plate are investigated experimentally and numerically when subjected to an axial compressive load. In order to accomplish the optimization study on the buckling characteristics of the composite plate among various structural criterions such as number of layers, the width of the plate and the ply orientation, the optimization tool “response surface methodology” (RSM) is used in this work. The validation of the developed finite element model in Analysis System (ANSYS) version 16 is carried out by comparing the critical buckling loads obtained from the experimental test and numerical simulation for three out of twenty samples. A comparison is then made between the numerical results obtained through ANSYS16 and the results generated using the regression equation. It is concluded that the buckling strength of the composite escalates with the number of layers, the change in width and the ply orientation. It is also noted that the weaving model of the fabric powers the buckling behavior of the composite. This work explores the feasibility of the use of the developed green composite in various buckling loadbearing structural applications. Due to the compromised buckling characteristics of the green composite with the synthetic composite, it has the capability of replacing many synthetic composites, which in turn enhances the sustainability of the environment. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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14 pages, 890 KiB

Open AccessArticle

Interface Strength and Fiber Content Influence on Corn Stover Fibers Reinforced Bio-Polyethylene Composites Stiffness

by Quim Tarrés, David Hernández-Díaz and Mònica Ardanuy

Polymers 2021, 13(5), 768; https://doi.org/10.3390/polym13050768 - 1 Mar 2021

Cited by 10 | Viewed by 2833

Abstract

Stiffness of material is a key parameter that allows the use of material for structural or semi-structural purposes. Besides, lightweight materials are increasingly calling the attention of the industry. Environmental impact is also increasing in its importance. Bio-based materials produced from renewable sources [...] Read more.

Stiffness of material is a key parameter that allows the use of material for structural or semi-structural purposes. Besides, lightweight materials are increasingly calling the attention of the industry. Environmental impact is also increasing in its importance. Bio-based materials produced from renewable sources can be good candidates for structural purposes combining lightweight and low environmental impact. Nonetheless, similar mechanical properties of commodities have to be reached with such materials. In this work, composite materials from corn stover fibers as a bio-polyethylene reinforcement were produced and tested. The effect of coupling agents to improve the fiber–matrix interface has been evaluated. It has been found that coupling agent content influenced the stiffness of the materials, increasing the Young’s modulus and the material processability. The best performance was achieved for a 6% of coupling agent, corresponding to 4.61 GPa for 50 w/w% of corn stover fibers. Micromechanics showed the impact of the semi-random orientation of the fibers and the lesser impact of its morphology. It was possible to determine a triangular packing of the composites as a hypothesis for future research. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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19 pages, 2818 KiB

Open AccessArticle

Stiffening Potential of Lignocellulosic Fibers in Fully Biobased Composites: The Case of Abaca Strands, Spruce TMP Fibers, Recycled Fibers from ONP, and Barley TMP Fibers

by Ferran Serra-Parareda, Fabiola Vilaseca, Francesc X. Espinach, Pere Mutjé, Marc Delgado-Aguilar and Quim Tarrés

Polymers 2021, 13(4), 619; https://doi.org/10.3390/polym13040619 - 18 Feb 2021

Cited by 13 | Viewed by 2539

Abstract

Biocomposites are composite materials where at least the matrix or the reinforcement phases are obtained from natural and renewable resources. Natural fibers for composite preparation can be obtained from annual plants, wood, recycled products, or agroforestry waste. The present work selected abaca strands, [...] Read more.

Biocomposites are composite materials where at least the matrix or the reinforcement phases are obtained from natural and renewable resources. Natural fibers for composite preparation can be obtained from annual plants, wood, recycled products, or agroforestry waste. The present work selected abaca strands, spruce fibers, recycled fibers from old newspaper, and barley fibers as raw materials to produce biocomposites, in combination with a biobased polyethylene. One very important feature in material science and for industrial applications is knowing how a material will deform under load, and this characteristic is represented by Young’s modulus. Therefore, in this work, the stiffness and deformation of the biocomposites were determined and evaluated using macromechanics and micromechanics analyses. Results were compared to those of conventional synthetic composites reinforced with glass fibers. From the micromechanics analysis, the intrinsic Young modulus of the reinforcements was obtained, as well as other micromechanics parameters such as the modulus efficiency and the length and orientation factors. Abaca strands accounted for the highest intrinsic modulus. One interesting outcome was that recycled fibers exhibited similar Young’s moduli to wood fibers. Finally, agroforestry waste demonstrated the lowest stiffening potential. The study explores the opportunity of using different natural fibers when specific properties or applications are desired. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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21 pages, 3082 KiB

Open AccessReview

Mechanical and Moisture Barrier Properties of Epoxy–Nanoclay and Hybrid Epoxy–Nanoclay Glass Fibre Composites: A Review

by Necar Merah, Farhan Ashraf and Mian M. Shaukat

Polymers 2022, 14(8), 1620; https://doi.org/10.3390/polym14081620 - 16 Apr 2022

Cited by 15 | Viewed by 3307

Abstract

Epoxy clay nanocomposites have been proven to have improved mechanical, thermal and physical properties over pristine matrix. Thus, the fields of application of epoxy–clay nanocomposites along with their hybrid glass/carbon fibre reinforced composites have grown tremendously during the last few decades. The present [...] Read more.

Epoxy clay nanocomposites have been proven to have improved mechanical, thermal and physical properties over pristine matrix. Thus, the fields of application of epoxy–clay nanocomposites along with their hybrid glass/carbon fibre reinforced composites have grown tremendously during the last few decades. The present review paper covers the research work performed on epoxy clay nanocomposites. It includes the influence of the processing techniques and parameters on the morphology of the nanocomposite, the methods of characterization and the effects of adding nanoclay on the mechanical and physical properties of composite. The improvements in the liquid barrier properties brought about by the addition of nanoclay platelets to epoxy resin are discussed. The variation of physical and mechanical properties with nanoclay type and content are reviewed along with the effects of moisture uptake on these properties. The advances in the development, characterization and applications of hybrid glass fibre reinforced epoxy–clay nanocomposites are discussed. Findings of the research work on the influence of nanoclay addition and exposure to water laden atmospheres on the behaviour of the hybrid glass fibre epoxy–nanoclay composites are presented. Finally, the potential health and environmental issues related to nanomaterials and their hybrid composites are reviewed. Full article

(This article belongs to the Special Issue Polymer Composite Analysis and Characterization)

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