Polymers

2024

Jump to: 2023, 2022, 2021

15 pages, 3144 KiB

Open AccessCommunication

Optimizing Ammonia Detection with a Polyaniline−Magnesia Nano Composite

by Sharanabasava V. Ganachari, Fatheali A. Shilar, Veerabhadragouda B. Patil, T. M. Yunus Khan, C. Ahamed Saleel and Mohammed Azam Ali

Polymers 2024, 16(20), 2892; https://doi.org/10.3390/polym16202892 - 14 Oct 2024

Viewed by 976

Abstract

Polyaniline−magnesia (PANI/MgO) composites with a fibrous nanostructure were synthesized via in situ oxidative polymerization, enabling uniform MgO integration into the polyaniline matrix. These composites were characterized using FTIR spectroscopy to analyze intermolecular bonding, XRD to assess crystallographic structure and phase purity, and SEM [...] Read more.

Polyaniline−magnesia (PANI/MgO) composites with a fibrous nanostructure were synthesized via in situ oxidative polymerization, enabling uniform MgO integration into the polyaniline matrix. These composites were characterized using FTIR spectroscopy to analyze intermolecular bonding, XRD to assess crystallographic structure and phase purity, and SEM to examine surface morphology and topological features. The resulting PANI/MgO nanofibers were utilized to develop ammonia (NH₃) gas-sensing probes with evaluations conducted at room temperature. The study addresses the critical challenge of achieving high sensitivity and selectivity in ammonia detection at low concentrations, which is a problem that persists in many existing sensor technologies. The nanofibers demonstrated high selectivity and optimal sensitivity for ammonia detection, which was attributed to the synergistic effects between the polyaniline and MgO that enhance gas adsorption. Furthermore, the study revealed that the MgO content critically influences both the morphology and the sensing performance, with higher MgO concentrations improving sensor response. This work underscores the potential of PANI/MgO composites as efficient and selective ammonia sensors, highlighting the importance of MgO content in optimizing material properties for gas-sensing applications. Full article

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2023

Jump to: 2024, 2022, 2021

36 pages, 2112 KiB

Open AccessReview

Use of Bio-Epoxies and Their Effect on the Performance of Polymer Composites: A Critical Review

by Monica Capretti, Valentina Giammaria, Carlo Santulli, Simonetta Boria and Giulia Del Bianco

Polymers 2023, 15(24), 4733; https://doi.org/10.3390/polym15244733 - 18 Dec 2023

Cited by 9 | Viewed by 3200

Abstract

This study comprehensively examines recent developments in bio-epoxy resins and their applications in composites. Despite the reliability of traditional epoxy systems, the increasing demand for sustainability has driven researchers and industries to explore new bio-based alternatives. Additionally, natural fibers have the potential to [...] Read more.

This study comprehensively examines recent developments in bio-epoxy resins and their applications in composites. Despite the reliability of traditional epoxy systems, the increasing demand for sustainability has driven researchers and industries to explore new bio-based alternatives. Additionally, natural fibers have the potential to serve as environmentally friendly substitutes for synthetic ones, contributing to the production of lightweight and biodegradable composites. Enhancing the mechanical properties of these bio-composites also involves improving the compatibility between the matrix and fibers. The use of bio-epoxy resins facilitates better adhesion of natural composite constituents, addressing sustainability and environmental concerns. The principles and methods proposed for both available commercial and especially non-commercial bio-epoxy solutions are investigated, with a focus on promising renewable sources like wood, food waste, and vegetable oils. Bio-epoxy systems with a minimum bio-content of 20% are analyzed from a thermomechanical perspective. This review also discusses the effect of incorporating synthetic and natural fibers into bio-epoxy resins both on their own and in hybrid form. A comparative analysis is conducted against traditional epoxy-based references, with the aim of emphasizing viable alternatives. The focus is on addressing their benefits and challenges in applications fields such as aviation and the automotive industry. Full article

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14 pages, 7863 KiB

Open AccessArticle

MWCNT-Coated Glass Fabric/Phenol Composite Heating Panel Fabricated by Resin Infusion Process

by Seongpil Choi, Juyeop Park, Donghoon Kang and Sang-Eui Lee

Polymers 2023, 15(16), 3353; https://doi.org/10.3390/polym15163353 - 10 Aug 2023

Cited by 1 | Viewed by 1568

Abstract

MWCNTs (multiwalled carbon nanotubes) were applied to fiber-reinforced composite materials with phenolic resin having flame retardance for the composite heating panels of railroad vehicles. Instead of dispersing MWCNTs in the matrix, the surface of a pristine plain-weave glass fiber fabric was coated with [...] Read more.

MWCNTs (multiwalled carbon nanotubes) were applied to fiber-reinforced composite materials with phenolic resin having flame retardance for the composite heating panels of railroad vehicles. Instead of dispersing MWCNTs in the matrix, the surface of a pristine plain-weave glass fiber fabric was coated with MWCNTs through a series of dip-coating and drying processes, followed by the resin infusion of the phenolic resin to make the composite heating panel. Before and after the resin infusion process, low percolation thresholds of 0.00216 wt%_MWCNT (weight percent of MWCNTs) and 0.001 wt%_MWCNT, respectively, were achieved, as were very high electrical conductivities of 47.5 S/m at 0.210 wt%_MWCNT and 26.7 S/m at 0.116 wt%, respectively. The low threshold and high conductivity can be attributed to the formation of electrical pathways directly onto the glass fabrics. It was confirmed that mechanical properties such as modulus, strength, and maximum strain were at the same level as those of the pristine glass fabric composite. The heating performance with temperature uniformity, as well as the electrical and mechanical properties, indicates that the resin-infused glass fabric composite having MWCNTs directly coated onto the fabric surface can be a solution for lightweight structural composite heating panels for railway vehicles. Full article

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11 pages, 3865 KiB

Open AccessArticle

Preparation and Characterization of Low CTE Poly(ethersulfone) Using Lignin Nano Composites as Flexible Substrates

by Jieun Jeong, Soochan Kim, Sangsoo Yun, Xin Yang and Young Jun Kim

Polymers 2023, 15(14), 3113; https://doi.org/10.3390/polym15143113 - 21 Jul 2023

Cited by 3 | Viewed by 1589

Abstract

Polyethersulfone (PES) has outstanding thermal and dimensional stability. It is considered an engineering thermoplastic. However, its high coefficient of thermal expansion (CTE) hinders its use in automobiles, microelectronics, and flexible display areas. To overcome its high coefficient of thermal expansion (CTE), recent studies [...] Read more.

Polyethersulfone (PES) has outstanding thermal and dimensional stability. It is considered an engineering thermoplastic. However, its high coefficient of thermal expansion (CTE) hinders its use in automobiles, microelectronics, and flexible display areas. To overcome its high coefficient of thermal expansion (CTE), recent studies have focused on reducing its high CTE and improving its mechanical properties by adding nano-sized fillers or materials. The addition of nanofiller or nanofibrils to the PES matrix often has a positive effect on its mechanical and thermal properties, making it a flexible display substrate. To obtain ideal flexible substrates, we prepared polyethersulfone with lignin nanocomposite films to reduce CTE and improve the mechanical and thermal properties of PES by varying the relative ratio of PES in the lignin nanocomposite. In this study, lignin as a biodegradable nanofiller was found to show high thermal, oxidative, and hydrolytic stability with favorable mechanical properties. PES/lignin nanocomposite films were prepared by solution casting according to the content of lignin (0 to 5 wt.%). PES/lignin composite films were subjected to mechanical, thermo-mechanical, optical, and surface analyses. The results showed enhanced thermomechanical and optical properties of PES, with the potential benefits of lignin filler materials realized for the development of thermoplastic polymer blends. Full article

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17 pages, 8243 KiB

Open AccessArticle

Modification of 3D Printable Polymer Filaments for Radiation Shielding Applications

by Antonio Jreije, Swaroop Kumar Mutyala, Benas Gabrielis Urbonavičius, Aušrinė Šablinskaitė, Neringa Keršienė, Judita Puišo, Živilė Rutkūnienė and Diana Adlienė

Polymers 2023, 15(7), 1700; https://doi.org/10.3390/polym15071700 - 29 Mar 2023

Cited by 8 | Viewed by 2551

Abstract

There is a growing need to develop lead-free shielding materials that are safe, low weight, durable, environmentally friendly, chemically and mechanically stable and customizable for specific applications. Fused deposition modeling (FDM), an additive manufacturing technique based on the extrusion of a thermoplastic filament [...] Read more.

There is a growing need to develop lead-free shielding materials that are safe, low weight, durable, environmentally friendly, chemically and mechanically stable and customizable for specific applications. Fused deposition modeling (FDM), an additive manufacturing technique based on the extrusion of a thermoplastic filament into a 3D printed object one layer at a time, could be employed well in applications involving ionizing radiation due to its relatively low cost, design flexibility and high manufacturing precision. This study aimed at developing 3D printing composites that contain Titanium dioxide as a filler agent for shielding in a medical radiation environment. First, the effect of low-dose ionizing radiation (up to 15 Gy) on the mechanical properties of common 3D printing polymers, ABS, ULTRAT, PLA, NYLON, ASA and PETG, was investigated. Since ABS experienced the lowest variation in its ultimate tensile strength (±5%) and Young’s modulus (−5%/+11%), it was chosen as a matrix for a new extruded 3D filament containing TiO₂ at 1 wt.%, 3 wt.%, and 5 wt.%. With the incorporation of TiO₂ at different filler contents, the UTS of the ABS composites varied between 24.1 MPa and 28.4 MPa, with the highest value recorded for 3 wt.% TiO₂. Young’s modulus values were dependent on both the TiO₂ concentration and on the irradiation dose. In addition, the ABS/TiO₂ composites with a higher filler content (3 wt.% and 5 wt.%) maintained their attenuation ability even after exposure to a radiation dose of 100 Gy as opposed to pure ABS, which exhibited a ~2.5% reduction in its mass attenuation coefficient after exposure to the same dose of radiation. The pilot investigation performed demonstrated that the newly developed ABS/TiO₂ composite containing 5 wt.% of filler can be successfully employed to shield electronic devices operating in a radiotherapy room. Full article

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11 pages, 3186 KiB

Open AccessArticle

Poly(methyl methacrylate) as Healing Agent for Carbon Fibre Reinforced Epoxy Composites

by Mónica Peñas-Caballero, Enrico Chemello, Antonio Mattia Grande, Marianella Hernández Santana, Raquel Verdejo and Miguel A. Lopez-Manchado

Polymers 2023, 15(5), 1114; https://doi.org/10.3390/polym15051114 - 23 Feb 2023

Cited by 5 | Viewed by 2296

Abstract

Self-healing materials offer a potential solution to the problem of damage to fibre-reinforced plastics (FRPs) by allowing for the in-service repair of composite materials at a lower cost, in less time, and with improved mechanical properties compared to traditional repair methods. This study [...] Read more.

Self-healing materials offer a potential solution to the problem of damage to fibre-reinforced plastics (FRPs) by allowing for the in-service repair of composite materials at a lower cost, in less time, and with improved mechanical properties compared to traditional repair methods. This study investigates for the first time the use of poly(methyl methacrylate) (PMMA) as a self-healing agent in FRPs and evaluates its effectiveness both when blended with the matrix and when applied as a coating to carbon fibres. The self-healing properties of the material are evaluated using double cantilever beam (DCB) tests for up to three healing cycles. The blending strategy does not impart a healing capacity to the FRP due to its discrete and confined morphology; meanwhile, coating the fibres with the PMMA results in healing efficiencies of up to 53% in terms of fracture toughness recovery. This efficiency remains constant, with a slight decrease over three subsequent healing cycles. It has been demonstrated that spray coating is a simple and scalable method of incorporating a thermoplastic agent into an FRP. This study also compares the healing efficiency of specimens with and without a transesterification catalyst and finds that the catalyst does not increase the healing efficiency, but it does improve the interlaminar properties of the material. Full article

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2022

Jump to: 2024, 2023, 2021

17 pages, 3357 KiB

Open AccessArticle

Effect of the Addition of Nano-Silica and Poly(ε-caprolactone) on the Mechanical and Thermal Properties of Poly(lactic acid) Blends and Possible Application in Embossing Process

by Sanja Mahović Poljaček, Dino Priselac, Tamara Tomašegović, Urška Stanković Elesini, Mirjam Leskovšek and Mirela Leskovac

Polymers 2022, 14(22), 4861; https://doi.org/10.3390/polym14224861 - 11 Nov 2022

Cited by 13 | Viewed by 2293

Abstract

In this study, the mechanical and thermal properties of poly(lactic acid) (PLA) blends with an addition of poly(ε–caprolactone) (PCL) and fumed silica (SiO₂) were evaluated to research the possibility of their use as relief printing plates for embossing processes. PCL and [...] Read more.

In this study, the mechanical and thermal properties of poly(lactic acid) (PLA) blends with an addition of poly(ε–caprolactone) (PCL) and fumed silica (SiO₂) were evaluated to research the possibility of their use as relief printing plates for embossing processes. PCL and nano-silica were added to the PLA matrix at different concentrations. Morphological, thermal and mechanical analyses were performed to determine the properties and possible functional characteristics of the studied blends. SEM micrographs showed that unmodified PLA/PCL blends exhibit a morphology typical of incompatible blends with clearly visible spherical domains of dispersed PCL in PLA. In particular, the results of the hardness tests showed that the selected blends have the optimal hardness (between 65 SH D and 75 SH D) for use in the embossing process. The tensile tests showed that the addition of nano-silica to neat PLA and to the PLA/PCL blends 50/50 and 60/40 improved the mechanical properties of the blends, especially stiffness and toughness. The DMA results showed that the addition of smaller amounts of SiO₂ can contribute to an increase in storage modulus, which is due to good dispersion and distribution of SiO₂ in the matrix. DSC analysis showed that the addition of PCL to PLA polymer increased the thermal stability of PLA and that the addition of nano-silica increased the degree of crystallinity of PLA. The TGA results showed that the addition of nano-silica improved the thermal degradation behavior of the studied blends, especially for blends modified with 3 wt% nano-silica. The results show that it is possible to optimize the mechanical and thermal properties of the blends with the aim of using them in the embossing process. Full article

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17 pages, 6867 KiB

Open AccessArticle

Silsesquioxane-Doped Electrospun Nanofibrillar Membranes for Separation Systems

by Miłosz Frydrych, Bogna Sztorch, Dariusz Brząkalski, Rafał Kozera, Roksana Konieczna, Tomasz Osiecki and Robert E. Przekop

Polymers 2022, 14(17), 3569; https://doi.org/10.3390/polym14173569 - 30 Aug 2022

Cited by 2 | Viewed by 1696

Abstract

In this study, a series of cage siloxanes (CS), e.g., three polyhedral oligomeric silsesquioxanes (SSQs) and one spherosilicate (SS) derivative, were applied as functional additives for the preparation of poly(lactic acid)-based (PLA) nanofibrillar membranes with an electrospinning technique utilizing an efficient spinning wire [...] Read more.

In this study, a series of cage siloxanes (CS), e.g., three polyhedral oligomeric silsesquioxanes (SSQs) and one spherosilicate (SS) derivative, were applied as functional additives for the preparation of poly(lactic acid)-based (PLA) nanofibrillar membranes with an electrospinning technique utilizing an efficient spinning wire electrode setup. The impact of the additives’ structure, chemistry, and electrospinning parameters on the obtained materials’ morphology (scanning electron microscopy) and physicochemical (thermogravimetry, differential scanning calorimetry, contact angle analysis, air flow analysis) properties is discussed. It is presented that applying organosilicon additives may extend the already tuneable properties of the membranes produced by electrospinning performed under different conditions and that they enable to obtain nanofibres of smaller diameter, which in turn increases the membrane porosity. Furthermore, the solvent-assisted electrospinning method allowed for unparalleled mixing of the PLA matrix with the CS additives, as no traces of free additives were visible on the membranes by scanning electron microscopy (SEM) imaging. The resulting membranes can be utilized as filter materials. Full article

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18 pages, 6423 KiB

Open AccessArticle

Performance Evaluation of CNT Reinforcement on Electroless Plating on Solid Free-Form-Fabricated PETG Specimens for Prosthetic Limb Application

by Palaiam Siddikali and P. S. Rama Sreekanth

Polymers 2022, 14(16), 3366; https://doi.org/10.3390/polym14163366 - 18 Aug 2022

Cited by 6 | Viewed by 2098

Abstract

The utility of polymers in the present decade is consistently increasing, giving scope to many applications from automobiles to prosthetics. Polymers used for solid free-form fabrication (SFFF), also known as 3D printing, comprise a quick fabrication process adopted by many industries to increase [...] Read more.

The utility of polymers in the present decade is consistently increasing, giving scope to many applications from automobiles to prosthetics. Polymers used for solid free-form fabrication (SFFF), also known as 3D printing, comprise a quick fabrication process adopted by many industries to increase productivity and decrease the run time to cope with the market demands. In this research work, pure polyethylene terephthalate glycol (PETG) and multi-walled carbon nanotube (MWCNT)-PETG with an electroless metal layer coating and without a coating are discussed. The effect of the electroless metal layer coating on the reinforced PETG-MWCNT results in improved mechanical, tribological, and other surface properties. Pure PETG was incorporated with MWCNT nanofillers at 0.3 wt.% and extruded as a filament through a twin screw extruder with a 1.75 mm diameter and printed on ASTM standards. Tensile testing was performed on all four types of un-coated pure PETG, PETG-MWCNT, and metal-layer-coated PETG and PETG-MWCNT with a coating thickness of 26, 32, 54, and 88 μm. Dynamic mechanical analysis (DMA) showed that the coated PETG-MWCNT had the highest storage and loss modulus. The heat deflection temperature was improved to 88 °C for the coated PETG-MWCNT. The wear volume against the sliding distance at a load of 40, 50, and 60 N showed that the coefficient of friction decreased with an increase in the load. The scratch test results revealed the lowest penetration depth and lowest friction coefficient for the coated PETG-MWCNT sample. The water contact angle test showed that a greater coating thickness makes the sample surface more hydrophobic, and the microhardness test indicated that the indentation hardness value for the PETG-MWCNT was 92 HV. The study revealed that the metal-layer-coated PETG-MWCNT had better performance compared to the other specimens due to a good metal layer bonding on the PETG substrate. It was concluded that adding MWCNTs to a metal layer electroless coating improved the surface and mechanical properties of the PETG, and this may be suitable for many applications. Full article

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33 pages, 6791 KiB

Open AccessReview

On the Use of Dolomite as a Mineral Filler and Co-Filler in the Field of Polymer Composites: A Review

by Asfa Amalia Ahmad Fauzi, Azlin Fazlina Osman, Awad A. Alrashdi, Zaleha Mustafa and Khairul Anwar Abdul Halim

Polymers 2022, 14(14), 2843; https://doi.org/10.3390/polym14142843 - 13 Jul 2022

Cited by 27 | Viewed by 5343

Abstract

Polymers are being used in many applications all around the world. However, there are some drawbacks in the properties of polymers that could hamper their usage in certain applications. Therefore, a new material polymer composite was introduced. A polymer composite is a polymer-based [...] Read more.

Polymers are being used in many applications all around the world. However, there are some drawbacks in the properties of polymers that could hamper their usage in certain applications. Therefore, a new material polymer composite was introduced. A polymer composite is a polymer-based material with the addition of a filler. Many researchers have reported the improvement in the properties of a polymer when a filler was introduced. This helps minimize the disadvantages of using a polymer. As a result, polymer composite products can be used in many industries, such as automobile, aerospace, biomedical, and packaging. Fillers derived from natural minerals, such as dolomite, are among the best reinforcement materials for polymeric materials because they are plentiful and low cost, have high rigidity and hardness, and even have tailorable surface chemistry. The use of dolomite as a filler in a polymer composite system has gained increasing attention in recent years after researchers successfully proved that it is capable of improving the mechanical, physical, and thermal properties of various polymeric materials. However, chemical or physical treatment/modification of raw dolomite is needed in order to prepare it as an efficient reinforcing filler. This procedure helps to improve the performance of the resultant polymer composites. This article reviews the usage of dolomite as a filler in a variety of polymeric materials and how it improved the performance of the polymer composite materials. It also highlights several methods that have been used for the purpose dolomite’s treatment/modification. Furthermore, the role of dolomite as a co-filler or a hybrid filler in a polymer composite system is also discussed, revealing the great potential and prospect of this mineral filler in the field of polymer composites for advanced applications. Full article

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10 pages, 4401 KiB

Open AccessArticle

Tuning HAuCl₄/Sodium Citrate Stoichiometry to Fabricate Chitosan-Au Nanocomposites

by Luis R. Torres-Ferrer, José M. López-Romero, Juan Mendez-Nonell, Maria J. Rivas-Arreola, Marisa Moreno-Ríos, Erika O. Ávila-Dávila, Evgeny Prokhorov, Yuriy Kovalenko, Diana G. Zárate-Triviño, Javier R. Revilla-Vazquez, Marco A. Meraz-Rios and Gabriel Luna-Barcenas

Polymers 2022, 14(4), 788; https://doi.org/10.3390/polym14040788 - 17 Feb 2022

Cited by 7 | Viewed by 2901

Abstract

Nanocomposite engineering of biosensors, biomaterials, and flexible electronics demand a highly tunable synthesis of precursor materials to achieve enhanced or desired properties. However, this process remains limited due to the need for proper synthesis-property strategies. Herein, we report on the ability to synthesize [...] Read more.

Nanocomposite engineering of biosensors, biomaterials, and flexible electronics demand a highly tunable synthesis of precursor materials to achieve enhanced or desired properties. However, this process remains limited due to the need for proper synthesis-property strategies. Herein, we report on the ability to synthesize chitosan-gold nanocomposite thin films (CS/AuNP) with tunable properties by chemically reducing HAuCl₄ in chitosan solutions and different HAuCl₄/sodium citrate molar relationships. The structure, electrical, and relaxation properties of nanocomposites have been investigated as a function of HAuCl₄/sodium citrate molar relation. It was shown that gold particle size, conductivity, Vogel temperature (glass transition), and water content strongly depend upon HAuCl₄/sodium citrate relationships. Two relaxation processes have been observed in nanocomposites; the α-relaxation process, related to a glass transition in wet CS/AuNP films, and the σ-relaxation related to the local diffusion process of ions in a disordered system. The ability to fine-tune both α- and σ-relaxations may be exploited in the proper design of functional materials for biosensors, biomaterials, and flexible electronics applications. Full article

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2021

Jump to: 2024, 2023, 2022

23 pages, 1227 KiB

Open AccessReview

Matrix and Filler Recycling of Carbon and Glass Fiber-Reinforced Polymer Composites: A Review

by Roberto Scaffaro, Alberto Di Bartolo and Nadka Tz. Dintcheva

Polymers 2021, 13(21), 3817; https://doi.org/10.3390/polym13213817 - 4 Nov 2021

Cited by 35 | Viewed by 6481

Abstract

Fiber-reinforced polymers (FRPs) are low-density, high-performance composite materials, which find important applications in the automotive, aerospace, and energy industry, to only cite a few. With the increasing concerns about sustainability and environment risks, the problem of the recycling of such complex composite systems [...] Read more.

Fiber-reinforced polymers (FRPs) are low-density, high-performance composite materials, which find important applications in the automotive, aerospace, and energy industry, to only cite a few. With the increasing concerns about sustainability and environment risks, the problem of the recycling of such complex composite systems has been emerging in politics, industry, and academia. The issue is exacerbated by the increased use of FRPs in the automotive industry and by the expected decommissioning of airplanes and wind turbines amounting to thousands of metric tons of composite materials. Currently, the recycling of FRPs downcycles the entire composite to some form of reinforcement material (typically for cements) or degrades the polymer matrix to recover the fibers. Following the principles of sustainability, the reuse and recycling of the whole composite—fiber and polymer—should be promoted. In this review paper, we report on recent research works that achieve the recycling of both the fiber and matrix phase of FRP composites, with the polymer being either directly recovered or converted to value-added monomers and oligomers. Full article

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30 pages, 7031 KiB

Open AccessArticle

Gamma Irradiation and the Radiation Shielding Characteristics: For the Lead Oxide Doped the Crosslinked Polystyrene-b-Polyethyleneglycol Block Copolymers and the Polystyrene-b-Polyethyleneglycol-Boron Nitride Nanocomposites

by Zehra Merve Cinan, Burcu Erol, Taylan Baskan, Saliha Mutlu, Sevil Savaskan Yilmaz and Ahmet Hakan Yilmaz

Polymers 2021, 13(19), 3246; https://doi.org/10.3390/polym13193246 - 24 Sep 2021

Cited by 24 | Viewed by 4197

Abstract

This work aimed to research the efficiency of gamma irradiation and shielding characteristics on the lead oxide (PbO) doped the crosslinked polystyrene-b-polyethyleneglycol (PS-b-PEG) block copolymers and polystyrene-b-polyethyleneglycol-boron nitride (PS-b-PEG-BN) nanocomposites materials. The crosslinked PS-b-PEG block copolymers and PS-b-PEG-BN nanocomposites mixed with different percentage [...] Read more.

This work aimed to research the efficiency of gamma irradiation and shielding characteristics on the lead oxide (PbO) doped the crosslinked polystyrene-b-polyethyleneglycol (PS-b-PEG) block copolymers and polystyrene-b-polyethyleneglycol-boron nitride (PS-b-PEG-BN) nanocomposites materials. The crosslinked PS-b-PEG block copolymers and PS-b-PEG-BN nanocomposites mixed with different percentage rates of PbO were used to research gamma-ray shielding characteristics. The synthesis of the copolymer was done by emulsion polymerization methods. The characterization and morphological analyses of irradiated samples were explored handling with the Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA), and Scanning Electron Microscope (SEM) methods. The gamma-rays that were emitted from the

E^{152} u

source were observed with a High Purity Germanium (HPGe) detector system and examined with a GammaVision computer program. Our samples, including the different percentage rates of the PS-b-PEG (1000, 1500, 10,000), BN, and PbO, were irradiated in various gamma-ray photon energy regions (from 121.78 keV to 1408.01 keV). Then, Linear-Mass Attenuation Coefficients (LACs-MACs), Half-Tenth Value Layer (HVL), Mean Free Path (MFP), and Radiation Protection Efficiency (RPE) values of the samples were calculated. Via crosschecking the acquired data from samples with and without PbO and BN, it was observed that, if the different percentage rates by weight nano-powder of PbO and BN are added in the polymer mixture, it can be used as a convenient shielding material against gamma rays. Full article

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15 pages, 1645 KiB

Open AccessEditor’s ChoiceReview

Current Strategies for the Production of Sustainable Biopolymer Composites

by Ehsan Bari, Asghar Sistani, Jeffrey J. Morrell, Antonio Pizzi, Mohammad Reza Akbari and Javier Ribera

Polymers 2021, 13(17), 2878; https://doi.org/10.3390/polym13172878 - 27 Aug 2021

Cited by 31 | Viewed by 5058

Abstract

Rapid global population growth has led to an exponential increase in the use of disposable materials with a short life span that accumulate in landfills. The use of non-biodegradable materials causes severe damage to the environment worldwide. Polymers derived from agricultural residues, wood, [...] Read more.

Rapid global population growth has led to an exponential increase in the use of disposable materials with a short life span that accumulate in landfills. The use of non-biodegradable materials causes severe damage to the environment worldwide. Polymers derived from agricultural residues, wood, or other fiber crops are fully biodegradable, creating the potential to be part of a sustainable circular economy. Ideally, natural fibers, such as the extremely strong fibers from hemp, can be combined with matrix materials such as the core or hurd from hemp or kenaf to produce a completely renewable biomaterial. However, these materials cannot always meet all of the performance attributes required, necessitating the creation of blends of petroleum-based and renewable material-based composites. This article reviews composites made from natural and biodegradable polymers, as well as the challenges encountered in their production and use. Full article

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27 pages, 35466 KiB

Open AccessReview

Antibacterial Activity of Polymer Nanocomposites Incorporating Graphene and Its Derivatives: A State of Art

by Ana M. Díez-Pascual and José A. Luceño-Sánchez

Polymers 2021, 13(13), 2105; https://doi.org/10.3390/polym13132105 - 26 Jun 2021

Cited by 53 | Viewed by 8109

Abstract

The incorporation of carbon-based nanostructures into polymer matrices is a relevant strategy for producing novel antimicrobial materials. By using nanofillers of different shapes and sizes, and polymers with different characteristics, novel antimicrobial nanocomposites with synergistic properties can be obtained. This article describes the [...] Read more.

The incorporation of carbon-based nanostructures into polymer matrices is a relevant strategy for producing novel antimicrobial materials. By using nanofillers of different shapes and sizes, and polymers with different characteristics, novel antimicrobial nanocomposites with synergistic properties can be obtained. This article describes the state of art in the field of antimicrobial polymeric nanocomposites reinforced with graphene and its derivatives such as graphene oxide and reduced graphene oxide. Taking into account the vast number of articles published, only some representative examples are provided. A classification of the different nanocomposites is carried out, dividing them into acrylic and methacrylic matrices, biodegradable synthetic polymers and natural polymers. The mechanisms of antimicrobial activity of graphene and its derivatives are also reviewed. Finally, some applications of these antimicrobial nanocomposites are discussed. We aim to enhance understanding in the field and promote further work on the development of polymer-based antimicrobial nanocomposites incorporating graphene-based nanomaterials. Full article

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22 pages, 50580 KiB

Open AccessReview

Preparation of Flame-Retardant Polyurethane and Its Applications in the Leather Industry

by Shaolin Lu, Yechang Feng, Peikun Zhang, Wei Hong, Yi Chen, Haojun Fan, Dingshan Yu and Xudong Chen

Polymers 2021, 13(11), 1730; https://doi.org/10.3390/polym13111730 - 25 May 2021

Cited by 42 | Viewed by 8900

Abstract

As a novel polymer, polyurethane (PU) has been widely applied in leather, synthetic leather, and textiles due to its excellent overall performance. Nevertheless, conventional PU is flammable and its combustion is accompanied by severe melting and dripping, which then generates hazardous fumes and [...] Read more.

As a novel polymer, polyurethane (PU) has been widely applied in leather, synthetic leather, and textiles due to its excellent overall performance. Nevertheless, conventional PU is flammable and its combustion is accompanied by severe melting and dripping, which then generates hazardous fumes and gases. This defect limits PU applications in various fields, including the leather industry. Hence, the development of environmentally friendly, flame-retardant PU is of great significance both theoretically and practically. Currently, phosphorus-nitrogen (P-N) reactive flame-retardant is a hot topic in the field of flame-retardant PU. Based on this, the preparation and flame-retardant mechanism of flame-retardant PU, as well as the current status of flame-retardant PU in the leather industry were reviewed. Full article

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2024

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