Polymers

8 pages, 845 KiB

Open AccessCommunication

Small-Angle X-ray Scattering Analysis on the Estimation of Interaction Parameter of Poly(n-butyl acrylate)-b-poly(methyl methacrylate)

by Sang-In Lee, Min-Guk Seo, June Huh and Hyun-jong Paik

Polymers 2022, 14(24), 5567; https://doi.org/10.3390/polym14245567 - 19 Dec 2022

Cited by 3 | Viewed by 2147

Abstract

The temperature dependence of the Flory–Huggins interaction parameter

χ

for poly(n-butyl acrylate)-b-poly(methyl methacrylate) (PBA-b-PMMA) was quantified from small-angle X-ray scattering (SAXS) analysis using random phase approximation (RPA) theory. It was found from the

χ

estimation ( [...] Read more.

The temperature dependence of the Flory–Huggins interaction parameter

χ

for poly(n-butyl acrylate)-b-poly(methyl methacrylate) (PBA-b-PMMA) was quantified from small-angle X-ray scattering (SAXS) analysis using random phase approximation (RPA) theory. It was found from the

χ

estimation (

χ = 0.0103 + 14.76 / T

) that the enthalpic contribution,

χ_{H}

, a measure for temperature susceptibility of

χ

, is 1.7–4.5 folds smaller for PBA-b-PMMA than for the conventional styrene-diene-based block copolymers, which have been widely used for thermoplastic elastomers. This finding suggests that these fully acrylic components can be a desirable chemical pair for constituting terpolymers applied for thermally stable and mechanically resilient elastomers. Full article

(This article belongs to the Special Issue Advances and Applications of Block Copolymers)

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12 pages, 1941 KiB

Open AccessArticle

The Influence of Ply Stacking Sequence on Mechanical Properties of Carbon/Epoxy Composite Laminates

by Raphael Olabanji Ogunleye, Sona Rusnakova, Milan Zaludek and Samuel Emebu

Polymers 2022, 14(24), 5566; https://doi.org/10.3390/polym14245566 - 19 Dec 2022

Cited by 14 | Viewed by 3395

Abstract

In this work, the effect of ply stacking sequence of carbon/epoxy laminates subjected to flexural, tensile and impact loading was investigated. Five laminates with different stacking configurations were produced using the hand-laying-up technique. This includes a unidirectional laminate, cross-ply laminates, and quasi-isotropic laminates. [...] Read more.

In this work, the effect of ply stacking sequence of carbon/epoxy laminates subjected to flexural, tensile and impact loading was investigated. Five laminates with different stacking configurations were produced using the hand-laying-up technique. This includes a unidirectional laminate, cross-ply laminates, and quasi-isotropic laminates. Following the autoclave curing process, the responses of the composites to bending, tension and impact force were determined according to ASTM standards, and their corresponding strength, stiffness as well as impact energy were evaluated. Likewise, the flexural failure mode associated with each laminate was characterised using an optical microscope. The unidirectional laminates have higher flexural and tensile strength compared to the cross-ply and quasi-isotropic laminates. Moreover, as a result of material symmetry, the flexural and tensile modulus of symmetric cross-ply laminate improved by 59.5% and 3.97% compared to the unsymmetric counterpart. Furthermore, the quasi-isotropic laminates with absorption energy of 116.2 kJ/m² and 115.12 kJ/m², respectively have higher impact resistance compared to other samples. Full article

(This article belongs to the Special Issue Advanced Polymer Composites: Structure-Property-Processing Relationships)

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17 pages, 3533 KiB

Open AccessArticle

Is Graphene Always Effective in Reinforcing Composites? The Case of Highly Graphene-Modified Thermoplastic Nanofibers and Their Unfortunate Application in CFRP Laminates

by Emanuele Maccaferri, Laura Mazzocchetti, Tiziana Benelli, Jacopo Ortolani, Tommaso Maria Brugo, Andrea Zucchelli and Loris Giorgini

Polymers 2022, 14(24), 5565; https://doi.org/10.3390/polym14245565 - 19 Dec 2022

Cited by 5 | Viewed by 2474

Abstract

Graphene (G) can effectively enhance polymers’ and polymer composites’ electric, thermal, and mechanical properties. Nanofibrous mats have been demonstrated to significantly increase the interlaminar fracture toughness of composite laminates, hindering delamination and, consequently, making such materials safer and more sustainable thanks to increased [...] Read more.

Graphene (G) can effectively enhance polymers’ and polymer composites’ electric, thermal, and mechanical properties. Nanofibrous mats have been demonstrated to significantly increase the interlaminar fracture toughness of composite laminates, hindering delamination and, consequently, making such materials safer and more sustainable thanks to increased service life. In the present paper, poly(ethylene oxide) (PEO), polycaprolactone (PCL), and Nylon 66 nanofibers, plain or reinforced with G, were integrated into epoxy-matrix Carbon Fiber Reinforced Polymers (CFRPs) to evaluate the effect of polymers and polymers + G on the laminate mechanical properties. The main aim of this work is to compare the reinforcing action of the different nanofibers (polyether, polyester, and polyamide) and to disclose the effect of G addition. The polymers were chosen considering their thermal properties and, consequently, their mechanism of action against delamination. PEO and PCL, displaying a low melting temperature, melt, and mix during the curing cycle, act via matrix toughening; in this context, they are also used as tools to deploy G specifically in the interlaminar region when melting and mixing with epoxy resin. The high extent of modification stems from an attempt to deploy it in the interlaminar layer, thus diluting further in the resin. In contrast, Nylon 66 does not melt and maintain the nanostructure, allowing laminate toughening via nanofiber bridging. The flexural properties of the nanomodifed CFRPs were determined via a three-point bending (3PB) test, while delamination behavior in Mode I and Mode II was carried out using Double Cantilever Beam (DCB) and End-Notched Flexture (ENF) tests, respectively. The lack of a positive contribution of G in this context is an interesting point to raise in the field of nanoreinforced CFRP. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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21 pages, 7863 KiB

Open AccessArticle

Study on Curing Deformation of Composite Thin Shells Prepared by M-CRTM with Adjustable Injection Gap

by Ce Zhang, Ying Sun, Jing Xu, Xiaoping Shi and Guoli Zhang

Polymers 2022, 14(24), 5564; https://doi.org/10.3390/polym14245564 - 19 Dec 2022

Cited by 5 | Viewed by 1916

Abstract

A composite thin shell with a high fiber volume fraction prepared by resin transfer molding (RTM) may have void defects, which create deformations in the final curing and lead to the final product being unable to meet the actual assembly requirements. Taking a [...] Read more.

A composite thin shell with a high fiber volume fraction prepared by resin transfer molding (RTM) may have void defects, which create deformations in the final curing and lead to the final product being unable to meet the actual assembly requirements. Taking a helmet shell as an example, a multi-directional compression RTM (M-CRTM) method with an adjustable injection gap is proposed according to the shape of the thin shell. This method can increase the injection gap to reduce the fiber volume fraction during the injection process, making it easier for the resin to penetrate the reinforcement and for air bubbles to exit the mold. X-ray CT detection shows that the porosity of the helmet shell prepared by the newly developed technology is 36.6% lower than that of the RTM-molded sample. The void’s distribution is more uniform, and its size is decreased, as is the number of voids, especially large voids. The results show that the maximum curing deformation of the M-CRTM-molded helmet shell is reduced by 13.7% compared to the RTM molded sample. This paper then further studies the deformation types of the shell and analyzes the causes of such results, which plays an important role in promoting the application of composite thin shells. Full article

(This article belongs to the Special Issue Polymer-Based Three-Dimensional (3D) Textile Composites)

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24 pages, 6368 KiB

Open AccessArticle

Fabrication of Curcumin Diethyl γ-Aminobutyrate-Loaded Chitosan-Coated Magnetic Nanocarriers for Improvement of Cytotoxicity against Breast Cancer Cells

by Supakarn Hansapaiboon, Bryan Paul Bulatao, Feuangthit Niyamissara Sorasitthiyanukarn, Pongsakorn Jantaratana, Nonthaneth Nalinratana, Opa Vajragupta, Pranee Rojsitthisak and Pornchai Rojsitthisak

Polymers 2022, 14(24), 5563; https://doi.org/10.3390/polym14245563 - 19 Dec 2022

Cited by 9 | Viewed by 2120

Abstract

This study shows the effectiveness of magnetic-guide targeting in the delivery of curcumin diethyl γ-aminobutyrate (CUR-2GE), a prodrug of curcumin (CUR) previously synthesized to overcome unfavorable physicochemical properties of CUR. In this study, chitosan (Ch)-coated iron oxide nanoparticles (Ch-IONPs) were fabricated and optimized [...] Read more.

This study shows the effectiveness of magnetic-guide targeting in the delivery of curcumin diethyl γ-aminobutyrate (CUR-2GE), a prodrug of curcumin (CUR) previously synthesized to overcome unfavorable physicochemical properties of CUR. In this study, chitosan (Ch)-coated iron oxide nanoparticles (Ch-IONPs) were fabricated and optimized using Box–Behnken design-based response surface methodology for delivery of CUR-2GE. Ch was used as a coating material on the nanoparticle surface to avoid aggregation. The optimized condition for preparing Ch-IONPs consisted of using 4 mg Ch fabricated at pH 11 under a reaction temperature of 85 °C. The optimized Ch-IONPs were successfully loaded with CUR-2GE with sufficient loading capacity (1.72 ± 0.01%) and encapsulation efficiency (94.9 ± 0.8%). The obtained CUR-2GE-loaded Ch-IONPs (CUR-2GE-Ch-IONPs) exhibited desirable characteristics including a particle size of less than 50 nm based on TEM images, superparamagnetic property, highly crystalline IONP core, sufficient stability, and sustained-release profile. In the presence of permanent magnets, CUR-2GE-Ch-IONPs significantly increased cellular uptake and cytotoxicity toward MDA-MB-231 with a 12-fold increase in potency compared to free CUR-2GE, indicating the potential of magnetic-field assisted delivery of CUR-2GE-Ch-IONPs for the treatment of triple-negative breast cancer. Full article

(This article belongs to the Special Issue Functional Polymers for Drug Delivery System)

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17 pages, 6597 KiB

Open AccessArticle

An Experimental Investigation into Mechanical and Thermal Properties of Hybrid Woven Rattan/Glass-Fiber-Reinforced Epoxy Composites

by Agustinus Purna Irawan, Paula Tjatoerwidya Anggarina, Didi Widya Utama, Najid Najid, Mohd Zulkfly Abdullah, Januar Parlaungan Siregar, Tezara Cionita, Deni Fajar Fitriyana, Jamiluddin Jaafar, Agung Efriyo Hadi and Teuku Rihayat

Polymers 2022, 14(24), 5562; https://doi.org/10.3390/polym14245562 - 19 Dec 2022

Cited by 14 | Viewed by 3251

Abstract

The investigation of hybrid, woven, natural fiber-reinforced polymer composites as a substitute reinforcement for fiber polymer composites has recently caught the interest of academics, industry, and researchers. Woven, natural fiber composites have been implemented in many different applications, including parts for automobiles, household [...] Read more.

The investigation of hybrid, woven, natural fiber-reinforced polymer composites as a substitute reinforcement for fiber polymer composites has recently caught the interest of academics, industry, and researchers. Woven, natural fiber composites have been implemented in many different applications, including parts for automobiles, household items, flooring, aerospace, and ballistic materials. Therefore, this research seeks to establish the thermal and mechanical characteristics of composites made from rattan strips (RS) and glass fiber (GF)-reinforced epoxy resin (ER). Other than that, the impact of layering configurations with respect to the thermal and mechanical characteristics of the RS and GF will be determined. Hand lay-up and a hydraulic press machine produce hybrid, woven RS and GF laminates. The hybrid composite’s mechanical properties will be investigated using impact, tensile, and flexural tests. The hybrid woven of the GF/RS/RS/RS/GF composite sequence demonstrated the highest mechanical properties in comparison to other sequences. The increase from one to three layers of RS in the core layer of GF hybrid composites enhanced the flexural, impact, and tensile properties. In addition, the hybridization of rattan and GF is more thermally stable, as recorded by the high decomposition temperature. As a finding of the research, the woven RS and GF hybrid is a potential material for automotive applications such as car bumpers, for example. Full article

(This article belongs to the Special Issue Advanced Epoxy-Based Materials III)

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10 pages, 1934 KiB

Open AccessArticle

Prediction of the Viscoelastic Properties of a Cetyl Pyridinium Chloride/Sodium Salicylate Micellar Solution: (II) Prediction of the Step Rate Experiments

by Shuxin Huang

Polymers 2022, 14(24), 5561; https://doi.org/10.3390/polym14245561 - 19 Dec 2022

Viewed by 1170

Abstract

The reliable viscoelastic characterization and prediction of micellar solution is still required in industrial applications of the solution, e.g., in surfactant flooding and pharmaceuticals. Based on the recent theoretical characterization of the viscoelastic properties of a cetyl pyridinium chloride/sodium salicylate (CPyCl/NaSal) wormlike micellar [...] Read more.

The reliable viscoelastic characterization and prediction of micellar solution is still required in industrial applications of the solution, e.g., in surfactant flooding and pharmaceuticals. Based on the recent theoretical characterization of the viscoelastic properties of a cetyl pyridinium chloride/sodium salicylate (CPyCl/NaSal) wormlike micellar solution with a structuralized constitutive model in the work published in 2022, the present work predicted five groups of transient shear viscoelasticities of the solution experimentally obtained in 2010, which include the first normal stress difference (N₁) versus time curve in the start-up experiment, the shear stress (τ₁₂) in the start-up experiment, τ₁₂ in the long-term start-up experiment, the stress relaxation upon cessation of steady shear flow, and the transient N₁/τ₁₂ in the step strain experiment. The study findings clearly show an improvement in the predictions of the viscoelastic properties of the micellar solution compared with those predicted previously. For example, the experimental N₁/τ₁₂ is 9 at the strain of 9 in the step strain experiment, and the corresponding previous and present predictions are 2.47 and 8.45, respectively. Full article

(This article belongs to the Section Polymer Physics and Theory)

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10 pages, 1223 KiB

Open AccessArticle

Fractional Coupling of Primary and Johari–Goldstein Relaxations in a Model Polymer

by Carlo Andrea Massa, Francesco Puosi and Dino Leporini

Polymers 2022, 14(24), 5560; https://doi.org/10.3390/polym14245560 - 19 Dec 2022

Cited by 2 | Viewed by 1206

Abstract

A polymer model exhibiting heterogeneous Johari–Goldstein (JG) secondary relaxation is studied by extensive molecular-dynamics simulations of states with different temperature and pressure. Time–temperature–pressure superposition of the primary (segmental) relaxation is evidenced. The time scales of the primary and the JG relaxations are found [...] Read more.

A polymer model exhibiting heterogeneous Johari–Goldstein (JG) secondary relaxation is studied by extensive molecular-dynamics simulations of states with different temperature and pressure. Time–temperature–pressure superposition of the primary (segmental) relaxation is evidenced. The time scales of the primary and the JG relaxations are found to be highly correlated according to a power law. The finding agrees with key predictions of the Coupling Model (CM) accounting for the decay in a correlation function due to the relaxation and diffusion of interacting systems. Nonetheless, the exponent of the power law, even if it is found in the range predicted by CM (

0 < ξ < 1

), deviates from the expected one. It is suggested that the deviation could depend on the particular relaxation process involved in the correlation function and the heterogeneity of the JG process. Full article

(This article belongs to the Special Issue Molecular Dynamics Simulations of Polymers)

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12 pages, 2333 KiB

Open AccessArticle

Preparation of Bacterial Cellulose/Ketjen Black-TiO₂ Composite Separator and Its Application in Lithium-Sulfur Batteries

by Ming Yan, Chuanshan Zhao and Xia Li

Polymers 2022, 14(24), 5559; https://doi.org/10.3390/polym14245559 - 19 Dec 2022

Cited by 2 | Viewed by 2431

Abstract

Lithium-sulfur batteries (LSBs) have attracted extensive attention due to their high energy density and low cost. The separator is a key component of LSBs. An excellent LSBs separator requires not only good electrolyte wettability, but also high thermal stability, good tensile mechanical properties, [...] Read more.

Lithium-sulfur batteries (LSBs) have attracted extensive attention due to their high energy density and low cost. The separator is a key component of LSBs. An excellent LSBs separator requires not only good electrolyte wettability, but also high thermal stability, good tensile mechanical properties, green environmental protection potential and enough inhibition of shuttle effect. In this paper, composite separator Bacterial cellulose/Ketjen black-TiO₂ (BKT) was prepared by coating the green and environmentally friendly bacterial cellulose (BC) substrate with KB-TiO₂ material. BKT not only demonstrates higher electrolyte wettability, but also displays thermal stability and tensile resistance to enhance the safety of the battery. The high ratio of TiO₂ and KB on the BKT surface provides chemical and physical adsorption of lithium polysulfides (LiPSs), thereby inhibiting the shuttle effect and increasing the cycle life of LSBs. The secondary current collector formed by TiO₂ and KB can also reactivate the adsorbed LiPSs, further improving the capacity retention rate of the battery. Therefore, the LSBs assembled with the BKT separator exhibited an initial discharge capacity of 1180 mAh × g⁻¹ at a high current density of 0.5 C, and maintained a specific discharge capacity of 653 mAh × g⁻¹ after 100 cycles was achieved. Even at 2.0 mg × cm⁻² sulfur areal density and 0.1 C current density, the BKT separator based battery still has an initial discharge specific capacity of 1274 mAh × g⁻¹. In conclusion, BKT is a promising lithium-sulfur battery separator material. sulfur areal densities. Full article

(This article belongs to the Special Issue Synthesis and Application of Cellulose-Based Composites)

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18 pages, 3181 KiB

Open AccessArticle

The Impact of Isocyanate Index and Filler Functionalities on the Performance of Flexible Foamed Polyurethane/Ground Tire Rubber Composites

by Adam Olszewski, Paulina Kosmela, Adam Piasecki, Mateusz Barczewski and Aleksander Hejna

Polymers 2022, 14(24), 5558; https://doi.org/10.3390/polym14245558 - 19 Dec 2022

Cited by 6 | Viewed by 2932

Abstract

The structure and performance of polyurethane (PU) foams are strongly driven by the stoichiometry of the polyaddition reaction, quantitatively described by the isocyanate index. It determines the balance between isocyanate and hydroxyl groups in the reacting system and is affected by the introduction [...] Read more.

The structure and performance of polyurethane (PU) foams are strongly driven by the stoichiometry of the polyaddition reaction, quantitatively described by the isocyanate index. It determines the balance between isocyanate and hydroxyl groups in the reacting system and is affected by the introduction of additional functionalities originated, e.g., from applied fillers. Nevertheless, this issue is hardly taken into account in research works. Herein, the structure and performance of PU/ground tire rubber (GTR) composites differing in their isocyanate index (from 0.8 to 1.2) and prepared with and without considering the GTR functionalities in formulation development were investigated. Incorporating GTR into the PU matrix led to a reduction in average cell diameter (from 2 to 30% depending on the isocyanate index) compared to unfilled foams. However, formulation adjustments did not show a significant impact on cellular structure. The only decrease in open cell content was noted, from 10% for the 0.9 index to 40% for 1.2. Such changes were related to the increasing strength of the PU cellular structure able to maintain inside the increasing amount of carbon dioxide. On the other hand, considering hydroxyl values of GTR noticeably affected the thermomechanical performance of composites. The shift of glass transition temperature (T_g), even by 10 °C for 1.2 isocyanate index, enhanced the performance of materials, which was expressed in an 8–62% drop in the composite performance factor, pointing to the enhanced reinforcing effect resulting from filler incorporation. The stiffening of foams, related to the variations in PU segmental structure, also caused minor changes in the course of thermal degradation of PU/GTR composites due to the inferior thermal stability of hard segments. The obtained results provide important insights into the development of formulations of PU composites filled with materials containing reactive functional groups able to disrupt the stoichiometric balance of the polyaddition reaction. Full article

(This article belongs to the Special Issue Polymers and Nanotechnology for Industry 4.0)

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13 pages, 3795 KiB

Open AccessArticle

Evaluation of Lapatinib-Loaded Microfibers Prepared by Centrifugal Spinning

by Enikő Bitay, Attila Levente Gergely, József Kántor and Zoltán-István Szabó

Polymers 2022, 14(24), 5557; https://doi.org/10.3390/polym14245557 - 19 Dec 2022

Cited by 5 | Viewed by 2209

Abstract

Lapatinib (Lap) is a lypophilic drug frequently used in cancer treatment; however, due to its limited solubility and permeability, achieving therapeutic dose through oral administration proves to be a challenge. There are various methods for enhancing the solubility of Lap and other similar [...] Read more.

Lapatinib (Lap) is a lypophilic drug frequently used in cancer treatment; however, due to its limited solubility and permeability, achieving therapeutic dose through oral administration proves to be a challenge. There are various methods for enhancing the solubility of Lap and other similar drugs, one being the preparation of amorphous solid dispersions (ASD). In this study, a Lap-loaded polyvinylpyrrolidone (PVP) fiber mat was created with centrifugal spinning from a PVP/Lap solution in dimethyl formamide and ethanol. The production rate was 12.2 g/h dry fibers, and the fibers had an average thickness of 2.55 ± 0.92 μm. In the differential scanning calorimetry (DSC) thermogram of the fiber mat, the melting peak of the crystalline Lap was not visible, suggesting that Lap was in an amorphous state. A dissolution study was carried out in 0.2 M phosphate buffer saline solution at 37 °C. UV spectrophotometry data indicated that in the sample containing the fiber mat, the Lap concentration was 332 μg/mL (66%) in 10 min, decreasing to 227 μg/mL by 45 min. Meanwhile the crystalline Lap formed a 30–40 μg/mL (6–8%) solution in 5 min, maintaining that concentration. We conclude that centrifugal spinning can be an effective and easy method to produce ASDs. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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13 pages, 4122 KiB

Open AccessArticle

The Solution Properties of Polymethacrylate Molecular Brushes with Oligo(ethylene glycol) and Oligo(propylene glycol) Side Chains

by Maria Simonova, Alexander Simagin, Denis Kamorin, Sergey Orekhov, Alexander Filippov and Oleg Kazantsev

Polymers 2022, 14(24), 5556; https://doi.org/10.3390/polym14245556 - 19 Dec 2022

Cited by 3 | Viewed by 2036

Abstract

The properties of polymer brushes based on three macromonomers were investigated in aqueous and organic solutions. Methacrylic monomers with different compositions of the oligo(oxyalkylene) substituents and arrangements of the oligo(ethylene glycol) and oligo(propylene glycol) blocks were used for the synthesis of polymers. There [...] Read more.

The properties of polymer brushes based on three macromonomers were investigated in aqueous and organic solutions. Methacrylic monomers with different compositions of the oligo(oxyalkylene) substituents and arrangements of the oligo(ethylene glycol) and oligo(propylene glycol) blocks were used for the synthesis of polymers. There were methoxy [oligo(ethylene glycol)_10.3-block-oligo(propylene glycol)_4.7] methacrylate, methoxy [oligo(propylene glycol)_8.3-block-oligo(ethylene glycol)_6.6] methacrylate, and methoxy oligo(propylene glycol)_4.2 methacrylate. Molecular brushes were investigated by the methods of molecular hydrodynamics and optics in dilute solutions in acetonitrile, chloroform, and water. The peculiarities of behavior of poly[oligo(oxyalkylene) methacrylates] in aqueous solutions and water-toluene systems have been found; in particular, the solubility of the polymers in water and organic solvents, the polymers equilibrium distribution between the phases, and the surface activity in the water-toluene system have been established. The thermo-responsibility in aqueous solutions and values of a critical concentration of micelle formation were shown. Depending on the arrangement of blocks in the side chains of molecular brushes, they are characterized by different intramolecular density. Full article

(This article belongs to the Special Issue Challenges and Trends in Polymer Composites)

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16 pages, 4119 KiB

Open AccessArticle

Effect of Rheological Properties of Polymer Solution on Polymer Flooding Characteristics

by Farhood Navaie, Ehsan Esmaeilnezhad and Hyoung-Jin Choi

Polymers 2022, 14(24), 5555; https://doi.org/10.3390/polym14245555 - 19 Dec 2022

Cited by 13 | Viewed by 4518

Abstract

Polymer flooding is an appropriate enhanced oil recovery (EOR) process that can increase macroscopic sweep efficiency. We examined two polymeric superpushers at different salinities (10,000 and 42,000 ppm of NaCl and 18,000 ppm of CaCl₂) and temperatures (30 to 75 °C) [...] Read more.

Polymer flooding is an appropriate enhanced oil recovery (EOR) process that can increase macroscopic sweep efficiency. We examined two polymeric superpushers at different salinities (10,000 and 42,000 ppm of NaCl and 18,000 ppm of CaCl₂) and temperatures (30 to 75 °C) as polymer-flooding agents for the EOR process. Rheological and thixotropic tests were attempted to find shear viscosity change when the polymer solutions were introduced under different salinity and temperatures, followed by describing the rheological behavior with the two most common rheological models used for polymer solutions, and then a quadratic model with Design-Expert to detect the effective parameters. Core flooding tests were conducted afterward to determine the final proposed fluid. An increase in the concentration of monovalent ions and the addition of divalent ions adversely affected both types of polymers used, which was similar to the effects of a temperature increase. The Flopaam 3630S at 1000 ppm has more stability under harsh conditions and enables 22% and 38% oil recovery in carbonate and sandstone core rocks, respectively. Consequently, Flopaam 3630S can be the perfect polymer agent for different chemical flooding procedures in high-salinity oil reservoirs. Full article

(This article belongs to the Special Issue Polymer Applications for Enhanced Oil Recovery: Challenges and Opportunities)

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17 pages, 11149 KiB

Open AccessArticle

Use of Green Fs Lasers to Generate a Superhydrophobic Behavior in the Surface of Wind Turbine Blades

by Joaquín Rivera-Sahún, Luis Porta-Velilla, Germán F. de la Fuente and Luis A. Angurel

Polymers 2022, 14(24), 5554; https://doi.org/10.3390/polym14245554 - 19 Dec 2022

Cited by 2 | Viewed by 1761

Abstract

Ice generation on the surface of wind generator blades can affect the performance of the generator in several aspects. It can deteriorate sensor performance, reduce efficiency, and cause mechanical failures. One of the alternatives to minimize these effects is to include passive solutions [...] Read more.

Ice generation on the surface of wind generator blades can affect the performance of the generator in several aspects. It can deteriorate sensor performance, reduce efficiency, and cause mechanical failures. One of the alternatives to minimize these effects is to include passive solutions based on the modification of the blade surfaces, and in particular to generate superhydrophobic behavior. Ultra-short laser systems enable improved micromachining of polymer surfaces by reducing the heat affected zone (HAZ) and improving the quality of the final surface topography. In this study, a green fs laser is used to micromachine different patterns on the surface of materials with the same structure that can be found in turbine blades. Convenient optimization of surface topography via fs laser micromachining enables the transformation of an initially hydrophilic surface into a superhydrophobic one. Thus, an initial surface finish with a contact angle ca. 69° is transformed via laser treatment into one with contact angle values above 170°. In addition, it is observed that the performance of the surface is maintained or even improved with time. These results open the possibility of using lasers to control turbine blade surface microstructure while avoiding the use of additional chemical coatings. This can be used as a complementary passive treatment to avoid ice formation in these large structures. Full article

(This article belongs to the Special Issue Applications of Lasers in Polymer Science)

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17 pages, 856 KiB

Open AccessReview

An Insight into Enamel Resin Infiltrants with Experimental Compositions

by Claudia Mazzitelli, Uros Josic, Tatjana Maravic, Edoardo Mancuso, Cecilia Goracci, Milena Cadenaro, Annalisa Mazzoni and Lorenzo Breschi

Polymers 2022, 14(24), 5553; https://doi.org/10.3390/polym14245553 - 19 Dec 2022

Cited by 6 | Viewed by 3157

Abstract

Resin infiltration is a conservative treatment of initial enamel carious lesions. Only one infiltrant material is available on the market (Icon, DMG), and research is now investigating new chemical compositions so as to further exploit the benefits of the resin infiltration technique. A [...] Read more.

Resin infiltration is a conservative treatment of initial enamel carious lesions. Only one infiltrant material is available on the market (Icon, DMG), and research is now investigating new chemical compositions so as to further exploit the benefits of the resin infiltration technique. A literature search of the articles testing the effects of different formulations on mechanical properties, resin penetration ability, remineralizing, and antibacterial activities was conducted. Of 238 articles, 29 resulted in being eligible for the literature review. The formulations investigated were all different and consisted in the inclusion of hydrophobic monomers (i.e., BisEMA, UDMA), solvents (ethanol, HEMA), alternative etchants (PAM) or molecules with antibacterial or bioactivity features (i.e., AgNP, YbF_3, MTZ, chitosan, DMAMM, HAp, MC-IL, NACP, PUA, CHX) and microfilled resins. Information on the long-term performances of the tested experimental materials were scarce. The combination of TEGDMA with hydrophobic monomers and the inclusion of a solvent alternative to ethanol reinforced mechanical properties of the materials. Hybrid-glass materials demonstrated an enhanced remineralization capacity. Techniques such as tunnelization increased the penetration depth and preserved the recourse to less-conservative treatments. Combining the min-invasive infiltrant approach with remineralizing and bacteriostatic properties would be beneficial for therapeutic and economical aspects, according to the principles of minimally invasive dentistry. Full article

(This article belongs to the Special Issue Polymers Strategies in Dental Therapy)

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29 pages, 15922 KiB

Open AccessArticle

A New Stress-Based Formulation for Modeling Notched Fiber-Reinforced Laminates

by Xian Liu, Linxin Wang, Quantian Luo, Zhonghao Bai, Qing Li and Jian Hu

Polymers 2022, 14(24), 5552; https://doi.org/10.3390/polym14245552 - 19 Dec 2022

Cited by 1 | Viewed by 1857

Abstract

Laminated plates are often modeled with infinite dimensions in terms of the so-called Whitney–Nuismer (WN) stress criteria, which form a theoretical basis for predicting the residual properties of open-hole structures. Based upon the WN stress criteria, this study derived a new formulation involving [...] Read more.

Laminated plates are often modeled with infinite dimensions in terms of the so-called Whitney–Nuismer (WN) stress criteria, which form a theoretical basis for predicting the residual properties of open-hole structures. Based upon the WN stress criteria, this study derived a new formulation involving finite width; the effects of notch shape and size on the applicability of new formulae and the tensile properties of carbon-fiber-reinforced plastic (CFRP) laminates were investigated via experimental and theoretical analyses. The specimens were prepared by using laminates reinforced by plain woven carbon fiber fabrics and machined with or without an open circular hole or a straight notch. Standard tensile tests were performed and measured using the digital image correlation (DIC) technique, aiming to characterize the full-field surface strain. Continuum damage mechanics (CDMs)-based finite element models were developed to predict the stress concentration factors and failure processes of notched specimens. The characteristic distances in the stress criterion models were calibrated using the experimental results of un-notched and notched specimens, such that the failure of carbon fiber laminates with or without straight notches could be analytically predicted. The experimental results demonstrated well the effectiveness of the present formulations. The new formula provides an effective approach to implementing a finite-width stress criterion for evaluating the tensile properties of notched fiber-reinforced laminates. In addition, the notch size has a great effect on strength prediction while the fiber direction has a great influence on the fracture mode. Full article

(This article belongs to the Special Issue Advances in Research and Preparation of High-Performance Polymer Fibers)

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21 pages, 2653 KiB

Open AccessReview

Chemical Structures, Properties, and Applications of Selected Crude Oil-Based and Bio-Based Polymers

by Piotr Koczoń, Bartłomiej Bartyzel, Anna Iuliano, Dorota Klensporf-Pawlik, Dorota Kowalska, Ewa Majewska, Katarzyna Tarnowska, Bartłomiej Zieniuk and Eliza Gruczyńska-Sękowska

Polymers 2022, 14(24), 5551; https://doi.org/10.3390/polym14245551 - 19 Dec 2022

Cited by 7 | Viewed by 4855

Abstract

The growing perspective of running out of crude oil followed by increasing prices for all crude oil-based materials, e.g., crude oil-based polymers, which have a huge number of practical applications but are usually neither biodegradable nor environmentally friendly, has resulted in searching for [...] Read more.

The growing perspective of running out of crude oil followed by increasing prices for all crude oil-based materials, e.g., crude oil-based polymers, which have a huge number of practical applications but are usually neither biodegradable nor environmentally friendly, has resulted in searching for their substitutes—namely, bio-based polymers. Currently, both these types of polymers are used in practice worldwide. Owing to the advantages and disadvantages occurring among plastics with different origin, in this current review data on selected popular crude oil-based and bio-based polymers has been collected in order to compare their practical applications resulting from their composition, chemical structure, and related physical and chemical properties. The main goal is to compare polymers in pairs, which have the same or similar practical applications, regardless of different origin and composition. It has been proven that many crude oil-based polymers can be effectively replaced by bio-based polymers without significant loss of properties that ensure practical applications. Additionally, biopolymers have higher potential than crude oil-based polymers in many modern applications. It is concluded that the future of polymers will belong to bio-based rather than crude oil-based polymers. Full article

(This article belongs to the Special Issue Development of Bio-Based Materials: Synthesis, Characterization, and Applications II)

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13 pages, 2821 KiB

Open AccessArticle

Glutaraldehyde Crosslinked High Content of Amylose/Polyvinyl Alcohol Blend Films with Potent Tensile Strength and Young’s Modulus

by Xinqing Wang, Zhenhua Huang, Zhaoyang Niu, Fangping Chen and Changsheng Liu

Polymers 2022, 14(24), 5550; https://doi.org/10.3390/polym14245550 - 19 Dec 2022

Cited by 9 | Viewed by 3590

Abstract

In recent years, with the development of green environmental protection, starch film has become of interest due to the wide availability of sources, low price, and biodegradability. Amylose/polyvinyl alcohol (PVA) blend films crosslinked with different amounts of glutaraldehyde (GLU) were prepared by a [...] Read more.

In recent years, with the development of green environmental protection, starch film has become of interest due to the wide availability of sources, low price, and biodegradability. Amylose/polyvinyl alcohol (PVA) blend films crosslinked with different amounts of glutaraldehyde (GLU) were prepared by a solution casting method. The cross-linking degree, water sorption, tensile property, crystallization and section morphology of the films were examined. With the increase in glutaraldehyde concentration, the cross-linking degree of the blend film was improved. The wide-angle X-ray scattering (WAXS) result indicated that cross-linking hindered the crystallization of film. The section morphology of films was examined by scanning electron microscope (SEM). The results showed that the cross-linking degree of amylose film improved while the crystallinity decreased with the increase in glutaraldehyde content. Cross-linking had no obvious effect on the water sorption property of the blend films. The cross-linking modification significantly enhanced the tensile strength and Young’s modulus, while it reduced the elongation at break of the blend films. It was found that the film with 0.5 wt % glutaraldehyde possessed the best performance: the tensile strength increased by 115%, while the elongation at break decreased by 18% even at high relative humidity (RH) of 90% compared to non-crosslinked films. The developed amylose/PVA blend films have promising application prospects as agricultural mulch films and packaging materials. Full article

(This article belongs to the Special Issue Properties, Structure and Environmental Impact of Organic and Inorganic Polymer Composites)

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23 pages, 2491 KiB

Open AccessReview

Biocomposite Materials Based on Poly(3-hydroxybutyrate) and Chitosan: A Review

by Yuliya Zhuikova, Vsevolod Zhuikov and Valery Varlamov

Polymers 2022, 14(24), 5549; https://doi.org/10.3390/polym14245549 - 18 Dec 2022

Cited by 11 | Viewed by 3837

Abstract

One of the important directions in the development of modern medical devices is the search and creation of new materials, both synthetic and natural, which can be more effective in their properties than previously used materials. Traditional materials such as metals, ceramics, and [...] Read more.

One of the important directions in the development of modern medical devices is the search and creation of new materials, both synthetic and natural, which can be more effective in their properties than previously used materials. Traditional materials such as metals, ceramics, and synthetic polymers used in medicine have certain drawbacks, such as insufficient biocompatibility and the emergence of an immune response from the body. Natural biopolymers have found applications in various fields of biology and medicine because they demonstrate a wide range of biological activity, biodegradability, and accessibility. This review first described the properties of the two most promising biopolymers belonging to the classes of polyhydroxyalkanoates and polysaccharides—polyhydroxybutyrate and chitosan. However, homopolymers also have some disadvantages, overcome which becomes possible by creating polymer composites. The article presents the existing methods of creating a composite of two polymers: copolymerization, electrospinning, and different ways of mixing, with a description of the properties of the resulting compositions. The development of polymer composites is a promising field of material sciences, which allows, based on the combination of existing substances, to develop of materials with significantly improved properties or to modify of the properties of each of their constituent components. Full article

(This article belongs to the Special Issue Natural-Based Biodegradable Polymeric Materials)

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17 pages, 5743 KiB

Open AccessArticle

Melt Temperature Estimation by Machine Learning Model Based on Energy Flow in Injection Molding

by Joohyeong Jeon, Byungohk Rhee and Jinsu Gim

Polymers 2022, 14(24), 5548; https://doi.org/10.3390/polym14245548 - 18 Dec 2022

Cited by 5 | Viewed by 3439

Abstract

Highly reliable and accurate melt temperature measurements in the barrel are necessary for stable injection molding. Conventional sheath-type thermocouples are insufficiently responsive for measuring melt temperatures during molding. Herein, machine learning models were built to predict the melt temperature after plasticizing. To supply [...] Read more.

Highly reliable and accurate melt temperature measurements in the barrel are necessary for stable injection molding. Conventional sheath-type thermocouples are insufficiently responsive for measuring melt temperatures during molding. Herein, machine learning models were built to predict the melt temperature after plasticizing. To supply reliably labeled melt temperatures to the models, an optimized temperature sensor was developed. Based on measured high-quality temperature data, three machine learning models were built. The first model accepted process setting parameters as inputs and was built for comparisons with previous models. The second model accepted additional measured process parameters related to material energy flow during plasticizing. Finally, the third model included the specific heat and part weights reflecting the material energy, in addition to the features of the second model. Thus, the third model outperformed the others, and its loss decreased by more than 70%. Meanwhile, the coefficient of determination increased by about 0.5 more than those of the first model. To reduce the dataset size for new materials, a transfer learning model was built using the third model, which showed a high prediction performance and reliability with a smaller dataset. Additionally, the reliability of the input features to the machine learning models were evaluated by shapley additive explanations (SHAP) analysis. Full article

(This article belongs to the Special Issue Advances in Polymers Processing and Injection Molding)

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13 pages, 4877 KiB

Open AccessArticle

Injectable Nanomedicine–Hydrogel for NIR Light Photothermal–Chemo Combination Therapy of Tumor

by Dashan Qi, Haowei Zhu, Yingjie Kong and Qingming Shen

Polymers 2022, 14(24), 5547; https://doi.org/10.3390/polym14245547 - 18 Dec 2022

Cited by 10 | Viewed by 2054

Abstract

Traditional hydrogels have drawbacks such as surgical implantation, large wound surfaces, and uncontrollable drug release during tumor treatment. In this paper, targeted nanomedicine has been combined with injectable hydrogel for photothermal–chemotherapy combination therapy. First, targeted nanomedicine (ICG—MTX) was fabricated by combining near-infrared (NIR) [...] Read more.

Traditional hydrogels have drawbacks such as surgical implantation, large wound surfaces, and uncontrollable drug release during tumor treatment. In this paper, targeted nanomedicine has been combined with injectable hydrogel for photothermal–chemotherapy combination therapy. First, targeted nanomedicine (ICG—MTX) was fabricated by combining near-infrared (NIR) photothermal reagents (ICG) and chemotherapy drugs (MTX). The ICG—MTX was then mixed with the hydrogel precursor and radical initiator to obtain an injectable hydrogel precursor solution. Under the irradiation of NIR light, the precursor solution could release alkyl radicals, which promote the transition of the precursor solution from a liquid to a colloidal state. As a result, the nanomedicine could effectively remain at the site of the tumor and continue to be released from the hydrogel. Due to the targeted nature of MTX, the released ICG—MTX could target tumor cells and improve the accuracy of photothermal–chemo combination therapy. The results indicated that the injectable nanomedicine–hydrogel system has a favorable therapeutic effect on tumors. Full article

(This article belongs to the Special Issue Responsive Biomaterials for Applications in Disease Diagnosis and Drug Delivery)

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17 pages, 4523 KiB

Open AccessArticle

Efficient Cationization of Cotton for Salt-Free Dyeing by Adjusting Fiber Crystallinity through Alcohol-Water-NaOH Pretreatment

by Aini Wu, Wei Ma, Zhiyu Yang and Shufen Zhang

Polymers 2022, 14(24), 5546; https://doi.org/10.3390/polym14245546 - 18 Dec 2022

Cited by 8 | Viewed by 3467

Abstract

Cationization of cotton is considered to be an effective way to realize salt-free dyeing of reactive dyes. However, applying cotton modified with glycidyltrimethylammonium chloride (GTA) suffers from large consumption of the cationic reagent. One of the reasons is that high crystallinity of cotton [...] Read more.

Cationization of cotton is considered to be an effective way to realize salt-free dyeing of reactive dyes. However, applying cotton modified with glycidyltrimethylammonium chloride (GTA) suffers from large consumption of the cationic reagent. One of the reasons is that high crystallinity of cotton fibers hinders the penetration of the reagents into the cellulose interior and limits the reaction between them. This paper designed to use alcohol-water-NaOH system to pretreat the fibers before cationization. With this method, crystallinity of the cotton fibers is decreased and more reactive –OH is exposed, resulting in much higher fiber-reagent reactivity and increased GTA utilization. Influence of alcohol type, alcohol-to-water ratio, and quantity of NaOH on fiber crystallinity and GTA dosage for cationization are all examined. It is found that for achieving 96.0% fixation of C.I. Reactive Black 5 in the absence of salt, GTA dosage can be reduced by half when the fibers are pretreated by alcohol-water-NaOH. Compared with ethanol, n-propanol and isopropanol, tert-butyl alcohol incorporated system shows better performance in increasing fiber reactivity due to their weaker ability to dissolve ions. In this study, XRD and FT-IR are used to demonstrate changes in crystallinity of the fibers after pretreatment. The alteration in micromorphology and hydrophilicity of the pretreated fibers is observed by SEM and water contact angle test, respectively. Furthermore, the alcohol-water-NaOH system can be recycled to show very good repeatability. Notably, all dyed samples pretreated with the system present high color saturation and satisfactory color fastness, especially that the wet rub fastness reaches 4–5 grade, which is one grade higher than that obtained from the conventional dyeing with salt. The above findings prove that alcohol-water-NaOH pretreatment is effective in enhancing reactivity of the cotton fibers and penetrability of the agent, and it shows promising prospects in real application. Full article

(This article belongs to the Special Issue Functionalised Fibers and Multifunctional Fabrics)

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13 pages, 8840 KiB

Open AccessArticle

Experimental Study on the Bending and Shear Behaviors of Chinese Paulownia Wood at Elevated Temperatures

by Lingfeng Zhang, Biao Xu, Zhongjie Fang, Chen Li, Xijun Kong, Qianyi Li and Kai Guo

Polymers 2022, 14(24), 5545; https://doi.org/10.3390/polym14245545 - 18 Dec 2022

Cited by 3 | Viewed by 1663

Abstract

Chinese Paulownia wood has been extensively used in the construction of timber buildings and lightweight sandwich structures. However, the bending and shear behaviors at elevated temperatures were not well understood. A total of 162 specimens were tested to investigate the bending, tangential shear, [...] Read more.

Chinese Paulownia wood has been extensively used in the construction of timber buildings and lightweight sandwich structures. However, the bending and shear behaviors at elevated temperatures were not well understood. A total of 162 specimens were tested to investigate the bending, tangential shear, and radial shear performances of Chinese Paulownia wood under temperatures from 20 to 220 °C. It was found that the bending specimens exhibited ductile failure due to the progressive damage after reaching the peak load, while the tangential and radial shear specimens exhibited brittle shear failure along the shear plane. The elevated temperatures had limited effects on the failure modes. Under the same temperature, the retention rate of the modulus of elasticity is significantly higher than that of the modulus of rupture. Moreover, the bending strength, tangential shear strength, and radial shear strength generally and nonlinearly decreased with the increasing temperature. The EN 1995-1-2 design curve for the shear strength of wood at elevated temperatures is conservative for both the tangential and radial shear specimens. However, the design curve may not be adopted to estimate the tangential shear strength at temperatures higher than 220 °C. Full article

(This article belongs to the Special Issue Eco-Friendly Supramolecular Polymeric Materials)

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19 pages, 3063 KiB

Open AccessArticle

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV))/Bacterial Cellulose (BC) Biocomposites for Potential Use in Biomedical Applications

by Maria Râpă, Laura Mihaela Stefan, Ana-Maria Seciu-Grama, Alexandra Gaspar-Pintiliescu, Ecaterina Matei, Cătălin Zaharia, Paul Octavian Stănescu and Cristian Predescu

Polymers 2022, 14(24), 5544; https://doi.org/10.3390/polym14245544 - 18 Dec 2022

Cited by 5 | Viewed by 2703

Abstract

The aim of this study was to obtain biocomposites consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), bacterial cellulose (BC) and α-tocopherol by a melt processing technique for potential use in biomedical applications. The melt processing and roughness of biocomposites were evaluated and compared to [...] Read more.

The aim of this study was to obtain biocomposites consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), bacterial cellulose (BC) and α-tocopherol by a melt processing technique for potential use in biomedical applications. The melt processing and roughness of biocomposites were evaluated and compared to sample without BC. The degradation rate of PHBV/BC biocomposites was measured in phosphate buffer saline (PBS) by determining the mass variation and evidencing of thermal and structural changes by differential scanning calorimetry (DSC) and attenuated total reflectance-Fourier transformed infrared spectrometry (ATR-FTIR). The cell viability, cell morphology, cell cycle distribution and total collagen content were investigated on murine NCTC fibroblasts. Overall, the adding of BC to polyester matrix led to an adequate melt processing of biocomposites and increased surface roughness and cytocompatibility, allowing the cells to secrete the extracellular matrix (collagen) and stimulate cell proliferation. Results showed that the PHBV/BC biocomposites were favorable for long-term degradation and could be used for the design of medical devices with controlled degradability. Full article

(This article belongs to the Special Issue Polyester-Based Materials II)

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15 pages, 2783 KiB

Open AccessArticle

Starch Biocryogel for Removal of Methylene Blue by Batch Adsorption

by Tarawee Taweekarn, Worawit Wongniramaikul, Chanita Boonkanon, Chonthicha Phanrit, Wilasinee Sriprom, Wadcharawadee Limsakul, Wanchitra Towanlong, Chanadda Phawachalotorn and Aree Choodum

Polymers 2022, 14(24), 5543; https://doi.org/10.3390/polym14245543 - 18 Dec 2022

Cited by 15 | Viewed by 2331

Abstract

A green monolithic starch cryogel was prepared and applied for the removal of methylene blue (MB) using a batch system. The influence of various experimental parameters on MB adsorption was investigated. High removal efficiency (81.58 ± 0.59%) and adsorption capacity (34.84 mg g [...] Read more.

A green monolithic starch cryogel was prepared and applied for the removal of methylene blue (MB) using a batch system. The influence of various experimental parameters on MB adsorption was investigated. High removal efficiency (81.58 ± 0.59%) and adsorption capacity (34.84 mg g⁻¹) were achieved. The Langmuir model better fitted the experimental data (determination coefficient (R²) = 0.9838) than the Freundlich one (R² = 0.8542), while the kinetics of MB adsorption on the cryogel followed a pseudo-second-order model. The adsorption process was spontaneous and endothermic with an activation energy of 37.8 kJ mol⁻¹ that indicated physical adsorption. The starch cryogel was used for MB removal from a wastewater sample collected from a local Batik production community enterprise in Phuket, Thailand, and a removal efficiency of 75.6% was achieved, indicating that it has a high potential as a green adsorbent for MB removal. Full article

(This article belongs to the Special Issue Polymer-Based Multifunctional Materials for Water/Wastewater Remediation)

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11 pages, 6648 KiB

Open AccessArticle

Fabrication of Inorganic Coatings Incorporated with Functionalized Graphene Oxide Nanosheets for Improving Fire Retardancy of Wooden Substrates

by Tsung-Pin Tasi, Chien-Te Hsieh, Hsi-Chi Yang, Heng-Yu Huang, Min-Wei Wu and Yasser Ashraf Gandomi

Polymers 2022, 14(24), 5542; https://doi.org/10.3390/polym14245542 - 18 Dec 2022

Cited by 6 | Viewed by 2312

Abstract

Flame-retardant chemicals are frequently used within consumer products and can even be employed as a treatment on the surface of different types of materials (e.g., wood, steel, and textiles) to prevent fire or limit the rapid spread of flames. Functionalized graphene oxide (FGO) [...] Read more.

Flame-retardant chemicals are frequently used within consumer products and can even be employed as a treatment on the surface of different types of materials (e.g., wood, steel, and textiles) to prevent fire or limit the rapid spread of flames. Functionalized graphene oxide (FGO) nanosheets are a promising construction coating nanomaterial that can be blended with sodium metasilicate and gypsum to reduce the flammability of construction buildings. In this work, we designed and fabricated novel and halogen-free FGO sheets using the modified Hummers method; and subsequently functionalized them by pentaerythritol through a chemical impregnation process before dispersing them within the construction coating. Scanning electron microscopic images confirm that the FGO-filled coating was uniformly dispersed on the surface of wooden substrates. We identified that the FGO content is a critical factor affecting the fire retardancy. Thermogravimetric analysis of the FGO coating revealed that higher char residue can be obtained at 700 °C. Based on the differential scanning calorimetry, the exothermic peak contained a temperature delay in the presence of FGO sheets, primarily due to the formation of a thermal barrier. Such a significant improvement in the flame retardancy confirms that the FGO nanosheets are superior nanomaterials to be employed as a flame-retardant construction coating nanomaterial for improving thermal management within buildings. Full article

(This article belongs to the Special Issue Polymer Composites for Construction Application)

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16 pages, 7241 KiB

Open AccessArticle

Centrifugally Spun PVA/PVP Based B, N, F Doped Carbon Nanofiber Electrodes for Sodium Ion Batteries

by Meltem Yanilmaz, Elham Abdolrazzaghian, Lei Chen, Juran Kim and Jung Joong Kim

Polymers 2022, 14(24), 5541; https://doi.org/10.3390/polym14245541 - 18 Dec 2022

Cited by 9 | Viewed by 2732

Abstract

Owing to their high electrical conductivity, high surface area, low density, high thermal stability, and chemical stability, carbon nanofibers have been used in many fields, including energy storage, electromagnetic shielding, filtering, composites, sensors, and tissue engineering. Considering the environmental impact of petroleum-based polymers, [...] Read more.

Owing to their high electrical conductivity, high surface area, low density, high thermal stability, and chemical stability, carbon nanofibers have been used in many fields, including energy storage, electromagnetic shielding, filtering, composites, sensors, and tissue engineering. Considering the environmental impact of petroleum-based polymers, it is vital to fabricate carbon nanofibers from environmentally-friendly materials using fast and safe techniques. PVA/PVP nanofibers were fabricated via centrifugal spinning and the effects of variations in the PVP content on the morphology and thermal properties of PVA/PVP-blend nanofibers were studied using SEM and DSC analyses. Moreover, the effects of carbonization conditions, including stabilization time, stabilization temperature, carbonization time, and carbonization temperature on the morphology and carbon yield, were investigated. Centrifugally spun PVA/PVP-based carbon nanofiber electrodes with an average fiber diameter around 300 nm are reported here for the first time. Furthermore, centrifugally spun PVA/PVP-based B, N, F-doped carbon nanofibers were fabricated by combining centrifugal spinning and heat treatment. Through B, N, F doping, CNFs demonstrated a high reversible capacity of more than 150 mAh/g in 200 cycles with stable cycling performance. Full article

(This article belongs to the Special Issue Advances in Polymer Applied in Batteries and Capacitors)

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12 pages, 3789 KiB

Open AccessArticle

Structural Features of Eu³⁺ and Tb³⁺-Bipyridinedicarboxamide Complexes

by Anna S. Miroshnichenko, Konstantin V. Deriabin, Artem A. Rashevskii, Vitalii V. Suslonov, Alexander S. Novikov, Ivan S. Mukhin and Regina M. Islamova

Polymers 2022, 14(24), 5540; https://doi.org/10.3390/polym14245540 - 18 Dec 2022

Cited by 2 | Viewed by 1857

Abstract

Photoluminescent lanthanide complexes of Eu³⁺ and Tb³⁺ as central atoms and N⁶,N⁶’-diisopropyl-[2,2′-bipyridine]-6,6′-dicarboxamide as ligand were synthesized. The structure of these complexes was established by single-crystal X-ray diffraction, mass spectrometry, ¹H and ¹³C nuclear [...] Read more.

Photoluminescent lanthanide complexes of Eu³⁺ and Tb³⁺ as central atoms and N⁶,N⁶’-diisopropyl-[2,2′-bipyridine]-6,6′-dicarboxamide as ligand were synthesized. The structure of these complexes was established by single-crystal X-ray diffraction, mass spectrometry, ¹H and ¹³C nuclear magnetic resonance, ultraviolet-visible, infrared spectroscopy, and thermogravimetry. Bipyridinic ligands provide formation of coordinatively saturated complexes of lanthanide ions and strong photoluminescence (PL). The Eu³⁺- and Tb³⁺-complexes exhibit PL emission in the red and green regions observed at a 340 nm excitation. The quantum yield for the complexes was revealed to be 36.5 and 12.6% for Tb³⁺- and Eu³⁺-complexes, respectively. These lanthanide compounds could be employed as photoluminescent solid-state compounds and as emitting fillers in polymer (for example, polyethylene glycol) photoluminescent materials. Full article

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17 pages, 2843 KiB

Open AccessArticle

Modification of Commercial 3D Fused Deposition Modeling Printer for Extrusion Printing of Hydrogels

by Semyon I. Koltsov, Tatiana G. Statsenko and Sofia M. Morozova

Polymers 2022, 14(24), 5539; https://doi.org/10.3390/polym14245539 - 17 Dec 2022

Cited by 7 | Viewed by 3050

Abstract

In this paper, we report a simple modification of a commercially available printer with fused deposition modeling (FDM) technology for the implementation of extrusion printing of hydrogels. The main difference between an FDM printer and a gel-extrusion printer is their material propulsion system, [...] Read more.

In this paper, we report a simple modification of a commercially available printer with fused deposition modeling (FDM) technology for the implementation of extrusion printing of hydrogels. The main difference between an FDM printer and a gel-extrusion printer is their material propulsion system, which has to deal with ether a solid rod or liquid. By application of plastic 3D printing on an FDM printer, specific details, namely, the plunger system and parts of the gel supply system, were produced and combined with a modified printer. Two types of printing of polymer hydrogels were optimized: droplet and filament modes. The rheological ranges suitable for printing for each method were indicated, and the resolution of the samples obtained and the algorithms for creating g-code via Python scripts were given. We have shown the possibility of droplet printing of microspheres with a diameter of 100 microns and a distance between spheres of 200 microns, as well as filament printing of lines with a thickness of 300–2000 microns, which is appropriate accuracy in comparison with commercial printers. This method, in addition to scientific groups, will be especially promising for educational tasks (as a practical work for engineering students or for the introduction of 3D printing into school classes) and industrial groups, as a way to implement 3D extrusion printing of composite polymer hydrogels in a time- and cost-effective way. Full article

(This article belongs to the Special Issue 3D Printing of Functional Polymer Composites)

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26 pages, 5849 KiB

Open AccessReview

Recent Advances in Polymers for Potassium Ion Batteries

by Xingqun Zhu, Rai Nauman Ali, Ming Song, Yingtao Tang and Zhengwei Fan

Polymers 2022, 14(24), 5538; https://doi.org/10.3390/polym14245538 - 17 Dec 2022

Cited by 6 | Viewed by 3653

Abstract

Potassium-ion batteries (KIBs) are considered to be an effective alternative to lithium-ion batteries (LIBs) due to their abundant resources, low cost, and similar electrochemical properties of K⁺ to Li⁺, and they have a good application prospect in the field of [...] Read more.

Potassium-ion batteries (KIBs) are considered to be an effective alternative to lithium-ion batteries (LIBs) due to their abundant resources, low cost, and similar electrochemical properties of K⁺ to Li⁺, and they have a good application prospect in the field of large-scale energy storage batteries. Polymer materials play a very important role in the battery field, such as polymer electrode materials, polymer binders, and polymer electrolytes. Here in this review, we focus on the research progress of polymers in KIBs and systematically summarize the research status and achievements of polymer electrode materials, electrolytes, and binders in potassium ion batteries in recent years. Finally, based on the latest representative research of polymers in KIBs, some suggestions and prospects are put forward, which provide possible directions for future research. Full article

(This article belongs to the Special Issue Polymer Battery Materials)

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