Next Issue
Volume 14, July-1
Previous Issue
Volume 14, June-1
 
 

Polymers, Volume 14, Issue 12 (June-2 2022) – 210 articles

Cover Story (view full-size image): In this study, the structure and properties of hydrogels, three-dimensional hydrophilic water-insoluble polymer networks, were studied by means of SAXS, PXRD, AFM, and SEM methods. We characterized the influence of MWCNTs on a κ-carrageenan–gelatin hydrogel structure. We show that the integration of polysaccharide and protein in composite hydrogel leads to suppression of their individual structural features and homogenization of two macromolecular components into a single supramolecular structure. Introduction of CNTs to hydrogel does not change the type of supramolecular structure and common structural tendencies, observed for the dispersion and gel states of the studied system. Carbon nanotubes embedded to hydrogel act as a supplementary template for a polymer net, providing additional mechanical strengthening to hydrogel. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Select all
Export citation of selected articles as:
15 pages, 10336 KiB  
Article
Strain Optimization of Tensioned Web through Computational Fluid Dynamics in the Roll-to-Roll Drying Process
by Minho Jo, Jaehyun Noh, Gyoujin Cho, Taik-min Lee, Bukuk Oh, Sanghoon Nam and Changwoo Lee
Polymers 2022, 14(12), 2515; https://doi.org/10.3390/polym14122515 - 20 Jun 2022
Cited by 4 | Viewed by 2279
Abstract
Unpredictable web temperature distributions in the dryer and strain deviations in the cross-machine (CMD) and machine (MD) directions could hamper the manufacture of smooth functional layers on polymer-based webs through the roll-to-roll (R2R) continuous process system. However, research on this topic is limited. [...] Read more.
Unpredictable web temperature distributions in the dryer and strain deviations in the cross-machine (CMD) and machine (MD) directions could hamper the manufacture of smooth functional layers on polymer-based webs through the roll-to-roll (R2R) continuous process system. However, research on this topic is limited. In this study, we developed a structural analysis model using the temperature distribution of the web as a boundary condition to analyze the drying mechanism of the dryer used in an R2R system. Based on the results of this model, we then applied structural modifications to the flow channel and hole density of the aluminum plate of the dryer. The model successfully predicted the temperature and strain distributions of the web inside the dryer in the CMD and MD by forming a tension according to the speed difference of the driven rolls at both ends of the span. Our structural improvements significantly reduced the temperature deviation of the moving web inside the dryer by up to 74% and decreased the strain deviation by up to 46%. The findings can help prevent web unevenness during the drying process of the R2R system, which is essential to minimize the formation of defects on functional layers built over polymer-based webs. Full article
(This article belongs to the Special Issue Theoretical Calculation and Simulation of Polymer)
Show Figures

Figure 1

12 pages, 2942 KiB  
Article
A Study on Preparation and Property Evaluations of Composites Consisting of TPU/Triclosan Membranes and Tencel®/LMPET Nonwoven Fabrics
by Bing-Chiuan Shiu, Po-Wen Hsu, Jian-Hong Lin, Ling-Fang Chien, Jia-Horng Lin and Ching-Wen Lou
Polymers 2022, 14(12), 2514; https://doi.org/10.3390/polym14122514 - 20 Jun 2022
Cited by 4 | Viewed by 2245
Abstract
This study investigated eco-friendly antibacterial medical protective clothing via the nonwoven process and characteristic evaluations. Firstly, Tencel® fibers and low melting point polyester (LMPET) fibers (re-sliced and granulated from recycled PET bottles) were mixed at different ratios and then needle punched at [...] Read more.
This study investigated eco-friendly antibacterial medical protective clothing via the nonwoven process and characteristic evaluations. Firstly, Tencel® fibers and low melting point polyester (LMPET) fibers (re-sliced and granulated from recycled PET bottles) were mixed at different ratios and then needle punched at diverse needle rolling depths. The influences of manufacturing parameters on the Tencel®/LMPET nonwoven fabrics were examined in terms of mechanical properties, water vapor transmission rate, and stiffness. Next, Tencel®/LMPET nonwoven fabrics were combined with thermoplastic polyurethane (TPU)/Triclosan antibacterial membranes that contained different contents of triclosan using melt processing technology. The resulting Tencel®/LMPET/TPU/Triclosan composites were characterized via different measurements; an optimal bursting strength of 86.86 N, an optimal horizontal tensile strength of 41.90 N, and an optimal stiffness along the MD and CD of 8.60 cm were recorded. Furthermore, the Tencel®/LMPET/TPU/Triclosan composites exhibited a distinct inhibition zone in the antibacterial measurement, and the hydrostatic pressure met the requirements of the EN 14126:2003 and GB 19082-200 disposable medical protective gear test standards. Full article
(This article belongs to the Special Issue Recent Development in Textiles and Fibers)
Show Figures

Graphical abstract

20 pages, 3852 KiB  
Article
Simplified Rules for Serviceability Control of FRPRC Elements
by Tomislav Kišiček, Tvrtko Renić, Ivan Hafner and Mislav Stepinac
Polymers 2022, 14(12), 2513; https://doi.org/10.3390/polym14122513 - 20 Jun 2022
Cited by 2 | Viewed by 1433
Abstract
Serviceability limit states are very important in the design of reinforced concrete elements but they are complex to calculate. Simplified serviceability calculations are provided in EN 1992-1-1 (2013) for steel reinforced elements. The crack widths are assumed to be acceptable if the bar [...] Read more.
Serviceability limit states are very important in the design of reinforced concrete elements but they are complex to calculate. Simplified serviceability calculations are provided in EN 1992-1-1 (2013) for steel reinforced elements. The crack widths are assumed to be acceptable if the bar diameters or bar spacings are not too large, while deflections are acceptable if the slenderness is not too large. In recent decades, FRP bars have become an adequate replacement for steel bars, especially in aggressive environments. The calculation procedures for FRP-reinforced concrete elements (FRPRC) were developed from calculation methods for steel reinforced elements. The first part of this paper demonstrates the procedures and parametric investigation for calculating the maximum bar diameter and bar spacing for the purpose of controlling the crack width, focusing on calculations for the maximum bar diameter for which cracks widths are acceptable. The second part of the paper demonstrates the procedures and parametric calculations for the slenderness limits for concrete elements reinforced with FRP bars in order to satisfy the usual deflection limits. Due to the different modulus of elasticity values of FRP and steel, the tables used for steel cannot be used for concrete beams reinforced with FRP bars. Therefore, new tables and diagrams are proposed in the paper. The new tables and diagrams for the maximum allowable bar diameters for the different modulus of elasticity values of FRP can be useful for the rapid control of the crack width in FRPRC elements. They are conservative compared to the exact calculations because some assumptions taken in the calculations are different to those taken in the exact calculation procedure for the crack width. The results of parametric calculations for the slenderness limits for FRPRC elements are provided in the form of a diagram for different concrete classes. Satisfying the slenderness from these curves will result in a smaller deflection than that allowed for each parameter related to that class of concrete. Full article
(This article belongs to the Special Issue Development in Fiber-Reinforced Polymer Composites)
Show Figures

Figure 1

13 pages, 3754 KiB  
Article
Sandwich-Structured Flexible PVA/CS@MWCNTs Composite Films with High Thermal Conductivity and Excellent Electrical Insulation
by Fanghua Luo, Chen Ma, Yuhui Tang, Lintao Zhou, Youpeng Ding and Guohua Chen
Polymers 2022, 14(12), 2512; https://doi.org/10.3390/polym14122512 - 20 Jun 2022
Cited by 7 | Viewed by 1860
Abstract
High thermal conductivity polymer matrix composites have become an urgent need for the thermal management of modern electronic devices. However, increasing the thermal conductivity of polymer-based composites typically results in loss of lightweight, flexibility and electrical insulation. Herein, the polyvinyl alcohol (PVA)/PVA-chitosan-adsorbed multi-walled [...] Read more.
High thermal conductivity polymer matrix composites have become an urgent need for the thermal management of modern electronic devices. However, increasing the thermal conductivity of polymer-based composites typically results in loss of lightweight, flexibility and electrical insulation. Herein, the polyvinyl alcohol (PVA)/PVA-chitosan-adsorbed multi-walled carbon nanotubes/PVA (PVA/CS@MWCNTs) composite films with a sandwich structure were designed and fabricated by a self-construction strategy inspired by the surface film formation of milk. The obtained film simultaneously possesses high thermal conductivity, electrical insulation, and excellent flexibility. In this particular structure, the uniform intermediate layer of PVA-CS@MWCNTs contributed to improving the thermal conductivity of composite films, and the PVA distributed on both sides of the sandwich structure maintains the electrical insulation of the films (superior electrical resistivity above 1012 Ω·cm). It has been demonstrated that the fillers could be arranged in a horizontal direction during the scraping process. Thus, the obtained composite film exhibited high in-plane thermal conductivity of 5.312 W·m−1·K−1 at fairly low MWCNTs loading of 5 wt%, which increased by about 1190% compared with pure PVA (0.412 W·m−1·K−1). This work effectively realizes the combination of high thermal conductivity and excellent electrical insulation, which could greatly expand the application of polymer-based composite films in the area of thermal management. Full article
(This article belongs to the Special Issue High Performance Polymer Membranes)
Show Figures

Graphical abstract

28 pages, 9330 KiB  
Article
Laser-Assisted Melt Electrospinning of Poly(L-lactide-co-ε-caprolactone): Analyses on Processing Behavior and Characteristics of Prepared Fibers
by Zongzi Hou, Haruki Kobayashi, Katsufumi Tanaka, Wataru Takarada, Takeshi Kikutani and Midori Takasaki
Polymers 2022, 14(12), 2511; https://doi.org/10.3390/polym14122511 - 20 Jun 2022
Cited by 3 | Viewed by 1742
Abstract
The laser-assisted melt electrospinning (LES) method was utilized for the preparation of poly(L-lactide-co-ε-caprolactone) (PLCL) fibers. During the process, a carbon dioxide laser was irradiated, and voltage was applied to the raw fiber of PLCL. In situ observation of fiber formation behavior revealed that [...] Read more.
The laser-assisted melt electrospinning (LES) method was utilized for the preparation of poly(L-lactide-co-ε-caprolactone) (PLCL) fibers. During the process, a carbon dioxide laser was irradiated, and voltage was applied to the raw fiber of PLCL. In situ observation of fiber formation behavior revealed that only a single jet was formed from the swelling region under the conditions of low laser power and applied voltage and feeding rate, whereas multiple jets and shots were produced with increases in these parameters. The formation of multiple jets resulted in the preparation of thinner fibers, and under the optimum condition, an average fiber diameter of 0.77 μm and its coefficient of variation of 17% was achieved without the formation of shots. The estimation of tension and stress profiles in the spin-line was also carried out based on the result of in situ observation and the consideration that the forces originated from surface tension, electricity, air friction, and inertia. The higher peak values of tension and stress appearing near the apex of the swelling region corresponded to the formation of thinner fibers for the condition of single-jet ejection. Analyses of the molecular orientation and crystallization of as-spun fibers revealed the formation of a wide variation of higher order structure depending on the spinning conditions. Full article
(This article belongs to the Section Polymer Fibers)
Show Figures

Graphical abstract

19 pages, 39023 KiB  
Review
A Review of Polymeric Micelles and Their Applications
by Suguna Perumal, Raji Atchudan and Wonmok Lee
Polymers 2022, 14(12), 2510; https://doi.org/10.3390/polym14122510 - 20 Jun 2022
Cited by 80 | Viewed by 10970
Abstract
Self-assembly of amphiphilic polymers with hydrophilic and hydrophobic units results in micelles (polymeric nanoparticles), where polymer concentrations are above critical micelle concentrations (CMCs). Recently, micelles with metal nanoparticles (MNPs) have been utilized in many bio-applications because of their excellent biocompatibility, pharmacokinetics, adhesion to [...] Read more.
Self-assembly of amphiphilic polymers with hydrophilic and hydrophobic units results in micelles (polymeric nanoparticles), where polymer concentrations are above critical micelle concentrations (CMCs). Recently, micelles with metal nanoparticles (MNPs) have been utilized in many bio-applications because of their excellent biocompatibility, pharmacokinetics, adhesion to biosurfaces, targetability, and longevity. The size of the micelles is in the range of 10 to 100 nm, and different shapes of micelles have been developed for applications. Micelles have been focused recently on bio-applications because of their unique properties, size, shape, and biocompatibility, which enhance drug loading and target release in a controlled manner. This review focused on how CMC has been calculated using various techniques. Further, micelle importance is explained briefly, different types and shapes of micelles are discussed, and further extensions for the application of micelles are addressed. In the summary and outlook, points that need focus in future research on micelles are discussed. This will help researchers in the development of micelles for different applications. Full article
Show Figures

Graphical abstract

22 pages, 7087 KiB  
Article
Assessment of Artificial Intelligence Strategies to Estimate the Strength of Geopolymer Composites and Influence of Input Parameters
by Kaffayatullah Khan, Waqas Ahmad, Muhammad Nasir Amin, Ayaz Ahmad, Sohaib Nazar and Majdi Adel Al-Faiad
Polymers 2022, 14(12), 2509; https://doi.org/10.3390/polym14122509 - 20 Jun 2022
Cited by 24 | Viewed by 2240
Abstract
Geopolymers might be the superlative alternative to conventional cement because it is produced from aluminosilicate-rich waste sources to eliminate the issues associated with its manufacture and use. Geopolymer composites (GPCs) are gaining popularity, and their research is expanding. However, casting, curing, and testing [...] Read more.
Geopolymers might be the superlative alternative to conventional cement because it is produced from aluminosilicate-rich waste sources to eliminate the issues associated with its manufacture and use. Geopolymer composites (GPCs) are gaining popularity, and their research is expanding. However, casting, curing, and testing specimens requires significant effort, price, and time. For research to be efficient, it is essential to apply novel approaches to the said objective. In this study, compressive strength (CS) of GPCs was anticipated using machine learning (ML) approaches, i.e., one single method (support vector machine (SVM)) and two ensembled algorithms (gradient boosting (GB) and extreme gradient boosting (XGB)). All models’ validity and comparability were tested using the coefficient of determination (R2), statistical tests, and k-fold analysis. In addition, a model-independent post hoc approach known as SHapley Additive exPlanations (SHAP) was employed to investigate the impact of input factors on the CS of GPCs. In predicting the CS of GPCs, it was observed that ensembled ML strategies performed better than the single ML technique. The R2 for the SVM, GB, and XGB models were 0.98, 0.97, and 0.93, respectively. The lowered error values of the models, including mean absolute and root mean square errors, further verified the enhanced precision of the ensembled ML approaches. The SHAP analysis revealed a stronger positive correlation between GGBS and GPC′s CS. The effects of NaOH molarity, NaOH, and Na2SiO3 were also observed as more positive. Fly ash and gravel size: 10/20 mm have both beneficial and negative impacts on the GPC′s CS. Raising the concentration of these ingredients enhances the CS, whereas increasing the concentration of GPC reduces it. Gravel size: 4/10 mm has less favorable and more negative effects. ML techniques will benefit the construction sector by offering rapid and cost-efficient solutions for assessing material characteristics. Full article
Show Figures

Figure 1

16 pages, 7704 KiB  
Article
Epoxy Coatings Containing Modified Graphene for Electromagnetic Shielding
by Marius Gabriel Bontaș, Aurel Diacon, Ioan Călinescu, Mădălina Ioana Necolau, Adrian Dinescu, Gabriela Toader, Raluca Ginghină, Alexandru-Mădălin Vizitiu, Valentin Velicu, Petru Palade, Marcel Istrate and Edina Rusen
Polymers 2022, 14(12), 2508; https://doi.org/10.3390/polym14122508 - 20 Jun 2022
Cited by 6 | Viewed by 2758
Abstract
This study presents the functionalization and characterization of graphene and electromagnetic interference (EMI) attenuation capacity in epoxy-nanocomposites. The modification of graphene involved both small molecules and polymers for compatibilization with epoxy resin components to provide EMI shielding. The TGA and RAMAN analyses confirmed [...] Read more.
This study presents the functionalization and characterization of graphene and electromagnetic interference (EMI) attenuation capacity in epoxy-nanocomposites. The modification of graphene involved both small molecules and polymers for compatibilization with epoxy resin components to provide EMI shielding. The TGA and RAMAN analyses confirmed the synthesis of graphene with a different layer thickness of the graphene sheets. Graphene samples with different layer thicknesses (monolayer, few layers, and multilayer) were selected and further employed for epoxy coating formulation. The obtained nanocomposites were characterized in terms of EMI shielding effectiveness, SEM, micro-CT, magnetic properties, and stress-strain resistance. The EMI shielding effectiveness results indicated that the unmodified graphene and hexamethylene diamine (HMDA) modified graphene displayed the best EMI shielding properties at 11 GHz. However, the epoxy nanocomposites based on HMDA modified graphene displayed better flexibility with an identical EMI shielding effectiveness compared to the unmodified graphene despite the formation of aggregates. The improved flexibility of the epoxy nanocomposites and EMI shielding characteristics of HMDA functionalized graphene offers a practical solution for textile coatings with microwave absorbing (MA) capacity. Full article
Show Figures

Figure 1

13 pages, 1828 KiB  
Article
Highly Active Heterogeneous Double Metal Cyanide Catalysts for Ring-Opening Polymerization of Cyclic Monomers
by Chinh-Hoang Tran, Min-Woong Lee, Soo-Jeong Lee, Jin-Hyeok Choi, Eun-Gyeong Lee, Ha-Kyung Choi and Il Kim
Polymers 2022, 14(12), 2507; https://doi.org/10.3390/polym14122507 - 20 Jun 2022
Cited by 10 | Viewed by 2982
Abstract
A series of heterogeneous Zn-Co double metal cyanide (DMC) catalysts were investigated for ring-opening polymerization (ROP) of various cyclic monomers. Notably, inexpensive and commonly used organic solvents such as acetone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, nitromethane, and 1-methylpyrrolidin-2-one [...] Read more.
A series of heterogeneous Zn-Co double metal cyanide (DMC) catalysts were investigated for ring-opening polymerization (ROP) of various cyclic monomers. Notably, inexpensive and commonly used organic solvents such as acetone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, nitromethane, and 1-methylpyrrolidin-2-one were very effective complexing agents for the preparation of DMC catalysts, showing high catalytic activity for the ROP of propylene oxide, ε-caprolactone, and δ-valerolactone. The chemical structures and compositions of the resultant catalysts were determined using various techniques such as FT-IR, X-ray photoelectron spectroscopy, powder X-ray diffraction, and elemental analysis. α,ω-Hydroxyl-functionalized polyether and polyester polyols with high yields and tunable molecular weights were synthesized in the presence of various initiators to control functionality. Kinetic studies of the ROP of δ-valerolactone were also performed to confirm the reaction mechanism. Full article
(This article belongs to the Collection Design and Synthesis of Polymers)
Show Figures

Graphical abstract

30 pages, 9163 KiB  
Review
Recent Advances in Biochar Polymer Composites
by Mattia Bartoli, Rossella Arrigo, Giulio Malucelli, Alberto Tagliaferro and Donatella Duraccio
Polymers 2022, 14(12), 2506; https://doi.org/10.3390/polym14122506 - 20 Jun 2022
Cited by 36 | Viewed by 5090
Abstract
“Biochar” (BC) is the solid residue recovered from the thermal cracking of biomasses in an oxygen-poor atmosphere. Recently, BC has been increasingly explored as a sustainable, inexpensive, and viable alternative to traditional carbonaceous fillers for the development of polymer-based composites. In fact, BC [...] Read more.
“Biochar” (BC) is the solid residue recovered from the thermal cracking of biomasses in an oxygen-poor atmosphere. Recently, BC has been increasingly explored as a sustainable, inexpensive, and viable alternative to traditional carbonaceous fillers for the development of polymer-based composites. In fact, BC exhibits high thermal stability, high surface area, and electrical conductivity; moreover, its main properties can be properly tuned by controlling the conditions of the production process. Due to its intriguing characteristics, BC is currently in competition with high-performing fillers in the formulation of multi-functional polymer-based composites, inducing both high mechanical and electrical properties. Moreover, BC can be derived from a huge variety of biomass sources, including post-consumer agricultural wastes, hence providing an interesting opportunity toward a “zero waste” circular bioeconomy. This work aims at providing a comprehensive overview of the main achievements obtained by combining BC with several thermoplastic and thermosetting matrices. In particular, the effect of the introduction of BC on the overall performance of different polymer matrices will be critically reviewed, highlighting the influence of differently synthesized BC on the final performance and behavior of the resulting composites. Lastly, a comparative perspective on BC with other carbonaceous fillers will be also provided. Full article
(This article belongs to the Special Issue Polymer/Bio-Carbon Composites: From Manufacturing to Applications)
Show Figures

Graphical abstract

17 pages, 3813 KiB  
Article
Enhancing the UV-Light Barrier, Thermal Stability, Tensile Strength, and Antimicrobial Properties of Rice Starch–Gelatin Composite Films through the Incorporation of Zinc Oxide Nanoparticles
by Wantida Homthawornchoo, Pimonpan Kaewprachu, Suttiporn Pinijsuwan, Orapan Romruen and Saroat Rawdkuen
Polymers 2022, 14(12), 2505; https://doi.org/10.3390/polym14122505 - 20 Jun 2022
Cited by 13 | Viewed by 2244
Abstract
The effects of zinc oxide nanoparticles (ZnONPs) on the properties of rice starch–gelatin (RS–G) films were investigated. ZnONPs were synthesized by a green method utilizing Asiatic pennywort (Centella asiatica L.) extract. The ZnONPs were rod-shaped, with sizes ranging from 100–300 nm. An [...] Read more.
The effects of zinc oxide nanoparticles (ZnONPs) on the properties of rice starch–gelatin (RS–G) films were investigated. ZnONPs were synthesized by a green method utilizing Asiatic pennywort (Centella asiatica L.) extract. The ZnONPs were rod-shaped, with sizes ranging from 100–300 nm. An increase in the concentration of ZnONPs significantly (p < 0.05) increased the thickness (0.050–0.070 mm), tensile strength (3.49–4.63 MPa), water vapor permeability (5.52–7.45 × 10−11 g m/m2 s Pa), and thermal stability of the RS–G–ZnONPs nanocomposite films. On the other hand, elongation at break (92.20–37.68%) and film solubility (67.84–30.36%) were significantly lower (p < 0.05) than that of the control RS–G film (0% ZnONPs). Moreover, the addition of ZnONPs strongly affected the film appearance, color, transmission, and transparency. The ZnONPs had a profound effect on the UV-light barrier improvement of the RS–G film. The crystalline structure of the ZnONPs was observed in the fabricated nanocomposite films using X-ray diffraction analysis. Furthermore, the RS–G–ZnONPs nanocomposite films exhibited strong antimicrobial activity against all tested bacterial strains (Staphylococcus aureus TISTR 746, Bacillus cereus TISTR 687, Escherichia coli TISTR 527, Salmonella Typhimurium TISTR 1470) and antifungal activity toward Aspergillus niger. According to these findings, RS–G–ZnONPs nanocomposite film possesses a potential application as an active packaging: antimicrobial or UV protective. Full article
(This article belongs to the Special Issue Biopolymer-Based Films and Coatings for Packaging Applications)
Show Figures

Figure 1

8 pages, 1993 KiB  
Communication
Gradient Porous Structured MnO2-Nonwoven Composite: A Binder-Free Polymeric Air Filter for Effective Room-Temperature Formaldehyde Removal
by Zijian Dai, Jianyong Yu and Yang Si
Polymers 2022, 14(12), 2504; https://doi.org/10.3390/polym14122504 - 20 Jun 2022
Cited by 4 | Viewed by 2109
Abstract
Recently, MnO2-coated polymeric filters have shown promising performance in room-temperature formaldehyde abatement. However, a commonly known concern of MnO2/polymer composites is either MnO2 crystal encapsulation or weak adhesion. This work reports a low-cost high-throughput and green strategy to [...] Read more.
Recently, MnO2-coated polymeric filters have shown promising performance in room-temperature formaldehyde abatement. However, a commonly known concern of MnO2/polymer composites is either MnO2 crystal encapsulation or weak adhesion. This work reports a low-cost high-throughput and green strategy to produce binder-free MnO2-nonwoven composite air filters. The production approach is energy saving and environmentally friendly, which combines MnO2 crystal coating on bicomponent polyolefin spunbond nonwovens and subsequent heat immobilizing of crystals, followed by the removal of weakly bonded MnO2. The binder-free MnO2-nonwoven composites show firm catalyst-fiber adhesion, a gradient porous structure, and excellent formaldehyde removal capability (94.5% ± 0.4%) at room temperature, and the reaction rate constant is 0.040 min−1. In contrast to the MnO2-nonwoven composites containing organic binders, the HCHO removal of binder-free filters increased by over 4%. This study proposes an alternative solution in producing catalyst/fabric composite filters for formaldehyde removal. Full article
(This article belongs to the Special Issue Progress in Polymer Membranes and Films)
Show Figures

Graphical abstract

21 pages, 8202 KiB  
Article
Anionic Dye Removal Using a Date Palm Seed-Derived Activated Carbon/Chitosan Polymer Microbead Biocomposite
by Hani Hussain Sait, Ahmed Hussain, Mohamed Bassyouni, Imtiaz Ali, Ramesh Kanthasamy, Bamidele Victor Ayodele and Yasser Elhenawy
Polymers 2022, 14(12), 2503; https://doi.org/10.3390/polym14122503 - 20 Jun 2022
Cited by 14 | Viewed by 2200
Abstract
The discharge of textile wastewater into aquatic streams is considered a major challenge due to its effect on the water ecosystem. Direct blue 78 (DB78) dye has a complex structure. Therefore, it is difficult to separate it from industrial wastewater. In this study, [...] Read more.
The discharge of textile wastewater into aquatic streams is considered a major challenge due to its effect on the water ecosystem. Direct blue 78 (DB78) dye has a complex structure. Therefore, it is difficult to separate it from industrial wastewater. In this study, carbon obtained from the pyrolysis of mixed palm seeds under different temperatures (400 °C and 1000 °C) was activated by a thermochemical method by using microwave radiation and an HCl solution in order to improve its adsorption characteristics. The generated activated carbon was used to synthesize a novel activated carbon/chitosan microbead (ACMB) for dye removal from textile wastewater. The obtained activated carbon (AC) was characterized by a physicochemical analysis that included, namely, particle size, zeta potential, SEM, EDX, and FTIR analyses. A series of batch experiments were conducted in terms of the ACMB dose, contact time, pH, and activated carbon/chitosan ratios in synthetic microbeads for enhancing the adsorption capacity. A remarkable improvement in the surface roughness was observed using SEM analysis. The particle surface was transformed from a slick surface with a minor-pore structure to a rough surface with major-pore structure. The zeta potential analysis indicated a higher improvement in the carbon surface charge, from −35 mv (before activation) to +20 mv (after activation). The adsorption tests showed that the dye-removal efficiency increased with the increasing adsorbent concentration. The maximum removal efficiencies were 97.8% and 98.4% using 3 and 4 g/L of AC400°C MB-0.3:1 and AC1000°C MB-0.3:1, respectively, with initial dye concentrations of 40 mg/L under acidic conditions (pH = 4–5), and an optimal mixing time of 50 min. The equilibrium studies for AC400°C MB-0.3:1 and AC1000°C MB-0.3:1 showed that the equilibrium data best fitted to the Langmuir isothermal model with R2 = 0.99. These results reveal that activated carbon/chitosan microbeads are an effective adsorbent for the removal of direct blue 78 dye and provide a new platform for dye removal. Full article
(This article belongs to the Special Issue Polymers for Energy and Environmental Applications)
Show Figures

Figure 1

23 pages, 5206 KiB  
Article
Thermomechanical and Fire Properties of Polyethylene-Composite-Filled Ammonium Polyphosphate and Inorganic Fillers: An Evaluation of Their Modification Efficiency
by Mateusz Barczewski, Aleksander Hejna, Kamila Sałasińska, Joanna Aniśko, Adam Piasecki, Katarzyna Skórczewska and Jacek Andrzejewski
Polymers 2022, 14(12), 2501; https://doi.org/10.3390/polym14122501 - 20 Jun 2022
Cited by 9 | Viewed by 2333
Abstract
The development of new polymer compositions characterized by a reduced environmental impact while lowering the price for applications in large-scale production requires the search for solutions based on the reduction in the polymer content in composites’ structure, as well as the use of [...] Read more.
The development of new polymer compositions characterized by a reduced environmental impact while lowering the price for applications in large-scale production requires the search for solutions based on the reduction in the polymer content in composites’ structure, as well as the use of fillers from sustainable sources. The study aimed to comprehensively evaluate introducing low-cost inorganic fillers, such as copper slag (CS), basalt powder (BP), and expanded vermiculite (VM), into the flame-retarded ammonium polyphosphate polyethylene composition (PE/APP). The addition of fillers (5–20 wt%) increased the stiffness and hardness of PE/APP, both at room and at elevated temperatures, which may increase the applicability range of the flame retardant polyethylene. The deterioration of composites’ tensile strength and impact strength induced by the presence of inorganic fillers compared to the unmodified polymer is described in detail. The addition of BP, CS, and VM with the simultaneous participation of APP with a total share of 40 wt% caused only a 3.1, 4.6, and 3 MPa decrease in the tensile strength compared to the reference value of 23 MPa found for PE. In turn, the cone calorimeter measurements allowed for the observation of a synergistic effect between APP and VM, reducing the peak heat rate release (pHRR) by 60% compared to unmodified PE. Incorporating fillers with a similar thermal stability but differing particle size distribution and shape led to additional information on their effectiveness in changing the properties of polyethylene. Critical examinations of changes in the mechanical and thermomechanical properties related to the structure analysis enabled the definition of the potential application perspectives analyzed in terms of burning behavior in a cone calorimetry test. Adding inorganic fillers derived from waste significantly reduces the flammability of composites with a matrix of thermoplastic polymers while increasing their sustainability and lowering their price without considerably reducing their mechanical properties, which allows for assigning developed materials as a replacement for flame-retarded polyethylene in large-scale non-loaded parts. Full article
(This article belongs to the Special Issue Progress in Polymer Composites for Different Applications)
Show Figures

Graphical abstract

10 pages, 4431 KiB  
Article
Development of an Antibacterial Dentin Adhesive
by Stephanie R. Lopes, Amanda G. N. Matuda, Raquel P. Campos, Ana Paula V. P. Mafetano, Ana Helena M. Barnabe, Gabriela S. Chagas, Daphne C. Barcellos, Li-Na Niu, Franklin R. Tay and Cesar R. Pucci
Polymers 2022, 14(12), 2502; https://doi.org/10.3390/polym14122502 - 19 Jun 2022
Cited by 5 | Viewed by 1671
Abstract
Nisin is a peptide that possesses potent antibacterial properties. This study evaluated the antibacterial activity of a nisin-doped adhesive against Streptococcus mutans, as well as its degree of conversion and microtensile bond strength (μTBS) to dentin. Nisin was added to the adhesive [...] Read more.
Nisin is a peptide that possesses potent antibacterial properties. This study evaluated the antibacterial activity of a nisin-doped adhesive against Streptococcus mutans, as well as its degree of conversion and microtensile bond strength (μTBS) to dentin. Nisin was added to the adhesive Adper Single Bond 2 (3M ESPE), resulting in four groups: Control Group (Single Bond 2); Group 1% (1 wt% nisin-incorporated), Group 3% (3 wt% nisin-incorporated) and Group 5% (5 wt% nisin-incorporated). Antibacterial activity against S. mutans was evaluated using colony-forming unit counts (CFU). The degree of conversion was tested using FTIR. Forty human teeth were restored for μTBS evaluation. Data were statistically analyzed with ANOVA and Tukey tests at α = 0.05. The nisin-doped adhesives, for all concentrations, exhibited a significant inhibition of the growth of S. mutans (p < 0.05); Incorporation of 5% and 3% nisin decreased the degree of conversion of the adhesive (p < 0.05). The μTBS (in MPa): Control Group—38.3 ± 2.3A, Group 1%—35.6 ± 2.1A, Group 3%—27.1 ± 1.6B and Group 5%—22.3 ± 1.0C. Nisin-doped adhesives exerted a bactericidal effect on S. mutans. The μTBS and degree of conversion of adhesive were not affected after incorporation of 1% nisin. Full article
(This article belongs to the Special Issue Advances and Applications of Adhesive Dentistry)
Show Figures

Graphical abstract

18 pages, 5378 KiB  
Article
Effects of Thermochromic Fluorane Microcapsules and Self-Repairing Waterborne Acrylic Microcapsules on the Properties of Water-Based Coatings on Basswood Surface
by Pan Pan, Xiaoxing Yan and Lin Wang
Polymers 2022, 14(12), 2500; https://doi.org/10.3390/polym14122500 - 19 Jun 2022
Cited by 10 | Viewed by 1637
Abstract
The effect of the addition of fluorane microcapsules and urea formaldehyde resin (UF) waterborne acrylic resin microcapsules on the comprehensive properties of the water film on the surface of basswood was studied. Three-factor and two-level orthogonal experiments were carried out with “fluorane microcapsule [...] Read more.
The effect of the addition of fluorane microcapsules and urea formaldehyde resin (UF) waterborne acrylic resin microcapsules on the comprehensive properties of the water film on the surface of basswood was studied. Three-factor and two-level orthogonal experiments were carried out with “fluorane microcapsule content”, “aqueous acrylic resin microcapsule content” and the “fluorane microcapsule addition method” to prepare a self-repairing thermochromic coating. The optical, mechanical, microstructure and self-repairing properties of the film were optimized by independent experiments on the maximum influence factors of the fluorane microcapsule content. It was concluded that the topcoat with 15% fluorane microcapsules and primer added with 15% water acrylic resin microcapsules had better comprehensive properties. The temperature range was 30–32 °C, the color difference at 32 °C was 72.6 ± 2.0, the 60° gloss was 3.3%, the adhesion was 0 grade, the hardness was 4 H, the impact resistance was 15.0 ± 0.8 kg∙cm, the elongation at break was 17.2% and the gap width was reduced by 3.5 ± 0.1 μm after the film was repaired. The repair rate reached 62.5%. By using microcapsule embedding technology, the repair agent and discoloration agent are embedded in the matrix. The waterborne acrylic resin microcapsules can effectively inhibit crack formation in the coating, and the fluorane microcapsules can achieve the thermochromic property of the coating. This study provides a new research idea for the self-repairing thermochromic dual function of a water-based coating. Full article
(This article belongs to the Special Issue High Proformance Wood Coating)
Show Figures

Figure 1

10 pages, 3099 KiB  
Article
Fabrication of Rechargeable Photoactive Silk Fibroin/Polyvinyl Alcohol Blend Nanofibrous Membranes for Killing Bacteria
by Shixiong Yi, Jiaxue Wu, Ying Zhou, Xiaomeng Wang, Yunfei Pu and Boli Ran
Polymers 2022, 14(12), 2499; https://doi.org/10.3390/polym14122499 - 19 Jun 2022
Cited by 1 | Viewed by 1679
Abstract
Antibacterial materials that prevent bacterial infections and mitigate bacterial virulence have attracted great scientific interest. In recent decades, bactericidal polymers have been presented as promising candidates to combat bacterial pathogens. However, the preparation of such materials has proven to be extremely challenging. Herein, [...] Read more.
Antibacterial materials that prevent bacterial infections and mitigate bacterial virulence have attracted great scientific interest. In recent decades, bactericidal polymers have been presented as promising candidates to combat bacterial pathogens. However, the preparation of such materials has proven to be extremely challenging. Herein, photoactive silk fibroin/polyvinyl alcohol blended nanofibrous membranes grafted with 3,3’,4,4’-benzophenone tetracarboxylic dianhydride (G-SF/PVA BNM) were fabricated by an electrospinning technique. The premise of this work is that the G-SF/PVA BNM can store photoactive activity under light irradiation and release reactive oxygen species for killing bacteria under dark conditions. The results showed that the resultant G-SF/PVA BNM exhibited the integrated properties of an ultrathin fiber diameter (298 nm), good mechanical properties, robust photoactive activity and photo-store capacity, and great photoinduced antibacterial activity against E. coli and S. aureus (99.999% bacterial reduction with 120 min). The successful construction of blended nanofibrous membranes gives a new possibility to the design of highly efficient antibacterial materials for public health protection. Full article
(This article belongs to the Special Issue Functional Biopolymers from Natural Resources)
Show Figures

Figure 1

16 pages, 3041 KiB  
Article
Functionalized Electrospun Scaffold–Human-Muscle-Derived Stem Cell Construct Promotes In Vivo Neocartilage Formation
by Lina Jankauskaite, Mantas Malinauskas, Lauryna Aukstikalne, Lauryna Dabasinskaite, Augustinas Rimkunas, Tomas Mickevicius, Alius Pockevičius, Edvinas Krugly, Dainius Martuzevicius, Darius Ciuzas, Odeta Baniukaitiene and Arvydas Usas
Polymers 2022, 14(12), 2498; https://doi.org/10.3390/polym14122498 - 19 Jun 2022
Cited by 6 | Viewed by 2327
Abstract
Polycaprolactone (PCL) is a non-cytotoxic, completely biodegradable biomaterial, ideal for cartilage tissue engineering. Despite drawbacks such as low hydrophilicity and lack of functional groups necessary for incorporating growth factors, it provides a proper environment for different cells, including stem cells. In our study, [...] Read more.
Polycaprolactone (PCL) is a non-cytotoxic, completely biodegradable biomaterial, ideal for cartilage tissue engineering. Despite drawbacks such as low hydrophilicity and lack of functional groups necessary for incorporating growth factors, it provides a proper environment for different cells, including stem cells. In our study, we aimed to improve properties of scaffolds for better cell adherence and cartilage regeneration. Thus, electrospun PCL–scaffolds were functionalized with ozone and loaded with TGF-β3. Together, human-muscle-derived stem cells (hMDSCs) were isolated and assessed for their phenotype and potential to differentiate into specific lineages. Then, hMDSCs were seeded on ozonated (O) and non-ozonated (“naïve” (NO)) scaffolds with or without protein and submitted for in vitro and in vivo experiments. In vitro studies showed that hMDSC and control cells (human chondrocyte) could be tracked for at least 14 days. We observed better proliferation of hMDSCs in O scaffolds compared to NO scaffolds from day 7 to day 28. Protein analysis revealed slightly higher expression of type II collagen (Coll2) on O scaffolds compared to NO on days 21 and 28. We detected more pronounced formation of glycosaminoglycans in the O scaffolds containing TGF-β3 and hMDSC compared to NO and scaffolds without TGF-β3 in in vivo animal experiments. Coll2-positive extracellular matrix was observed within O and NO scaffolds containing TGF-β3 and hMDSC for up to 8 weeks after implantation. These findings suggest that ozone-treated, TGF-β3-loaded scaffold with hMDSC is a promising tool in neocartilage formation. Full article
(This article belongs to the Special Issue Applications of Electrospun Nanofibers)
Show Figures

Figure 1

29 pages, 8586 KiB  
Article
Performance-Based Evaluation of Healing Efficiency on Mechanical Properties of Self-Healing Cementitious Materials Incorporated with PMMA/Epoxy Microcapsule
by Jun Ren, Birunxuan Liu, Hao Li, Ji Zhang, Haiyan Zhu, Meilin Xiao, Guojian Liu and Shuqiong Luo
Polymers 2022, 14(12), 2497; https://doi.org/10.3390/polym14122497 - 19 Jun 2022
Cited by 3 | Viewed by 1968
Abstract
In this study, based upon the investigation of its effect on workability and the mechanical property of cementitious materials, the Box–Behnken design was adopted to establish models describing self-healing performance on mechanical properties of cementitious materials with polymethylmethacrylate (PMMA)/epoxy microcapsule in terms of [...] Read more.
In this study, based upon the investigation of its effect on workability and the mechanical property of cementitious materials, the Box–Behnken design was adopted to establish models describing self-healing performance on mechanical properties of cementitious materials with polymethylmethacrylate (PMMA)/epoxy microcapsule in terms of healing rate of peak strength (Y1), the recovery rate of peak strength (Y2), the healing rate of Young’s modulus (Y3), the recovery rate of Young’s modulus (Y4), the healing rate of peak strain (Y5), and recovery rate of peak strain (Y6). This was performed under the influence of the four factors, including microcapsule size (X1), microcapsule content (X2), pre-loading (X3), and curing age (X4). The results showed the four factors significantly affect the healing rate and recovery rate of the peak strength, Young’s modulus, and peak strain, except the healing rate on peak strain. Moreover, the interaction between the factors showed some influence as well. The numerically optimised values of X1, X2, X3, and X4 are 203 nm, 5.59%, 43.56%, and 21 days, respectively, and the self-healing cementitious materials with desirable mechanical characteristics (Y1 63.67%, Y2 145.22%, Y3 40.34%, Y4 132.22%, Y5 27.66%, and Y6 133.84%) with the highest desirability of 0.9050 were obtained. Moreover, the porosity of the specimen confirmed the healing performance of PMMA/epoxy microcapsules in cementitious materials. Full article
(This article belongs to the Special Issue Functional Self-Healing Materials)
Show Figures

Graphical abstract

20 pages, 4212 KiB  
Review
Hydrophobic Recovery of Plasma-Hydrophilized Polyethylene Terephthalate Polymers
by Gregor Primc and Miran Mozetič
Polymers 2022, 14(12), 2496; https://doi.org/10.3390/polym14122496 - 19 Jun 2022
Cited by 14 | Viewed by 2211
Abstract
Oxygen plasma is widely used for enhancing the wettability of numerous polymers, including polyethylene terephthalate (PET). The treatment with plasma containing oxygen will cause surface functionalization with polar functional groups, which will, in turn, improve the wettability. However, the exact mechanisms leading to [...] Read more.
Oxygen plasma is widely used for enhancing the wettability of numerous polymers, including polyethylene terephthalate (PET). The treatment with plasma containing oxygen will cause surface functionalization with polar functional groups, which will, in turn, improve the wettability. However, the exact mechanisms leading to the hydrophilic or even super-hydrophilic surface finish are still insufficiently explored. The wettability obtained by plasma treatment is not permanent, since the hydrophobic recovery is usually reported. The mechanisms of hydrophobic recovery are reviewed and explained. Methods for suppressing this effect are disclosed and explained. The recommended treatment which assures stable hydrophilicity of PET samples is the treatment with energetic ions and/or vacuum ultraviolet radiation (VUV). The influence of various plasma species on the formation of the highly hydrophilic surface finish and stability of adequate wettability of PET materials is discussed. Full article
(This article belongs to the Special Issue Polymer Surface Modification and Adhesive Characteristics)
Show Figures

Figure 1

12 pages, 1120 KiB  
Article
Experimental Investigation of the Different Polyacrylamide Dosages on Soil Water Movement under Brackish Water Infiltration
by Jihong Zhang, Quanjiu Wang, Weiyi Mu, Kai Wei, Yi Guo and Yan Sun
Polymers 2022, 14(12), 2495; https://doi.org/10.3390/polym14122495 - 19 Jun 2022
Cited by 8 | Viewed by 1619
Abstract
The use of soil conditioners in conjunction with brackish water irrigation is critical for the efficient development and use of brackish water as well as the enhancement of the structure of saline soil and stimulating crop growth. This study investigated the effects of [...] Read more.
The use of soil conditioners in conjunction with brackish water irrigation is critical for the efficient development and use of brackish water as well as the enhancement of the structure of saline soil and stimulating crop growth. This study investigated the effects of different polyacrylamide (PAM) dosages (0, 0.02%, 0.04%, and 0.06%) on the water flow properties of sandy loam during brackish water infiltration using one-dimensional vertical and horizontal soil column infiltration experiments. The results showed that: (1) PAM could lower the soil infiltration rate and increase soil water retention performance under brackish water infiltration conditions. (2) PAM had a significant effect on the parameters of the Philip and Kostiakov infiltration models. The soil sorption rate S and the empirical coefficient λ were the smallest, and the empirical index β was the largest when the PAM dosage was 0.04%. (3) PAM dosage displayed a quadratic polynomial connection with the soil saturated water content and the saturated hydraulic conductivity. The soil saturated water content was highest when the PAM dosage was 0.04%, the intake suction hd of the Brooks-Corey model increased by 15.30%, and the soil water holding capacity was greatly improved. (4) Soil treated with PAM could absorb more water under the same soil water suction, whereas the soil unsaturated hydraulic conductivity and its growth rate decreased. The soil saturated diffusion rate Ds, as well as the soil water diffusion threshold, rose. Finally, the 0.04% PAM dosage could improve soil hydrodynamic characteristics under brackish water infiltration, which is beneficial for the efficient utilization of brackish water. Full article
Show Figures

Figure 1

13 pages, 5327 KiB  
Article
Effect of Polyhydroxyalkanoate (PHA) Concentration on Polymeric Scaffolds Based on Blends of Poly-L-Lactic Acid (PLLA) and PHA Prepared via Thermally Induced Phase Separation (TIPS)
by Francesco Lopresti, Antonio Liga, Elisa Capuana, Davide Gulfi, Claudio Zanca, Rosalinda Inguanta, Valerio Brucato, Vincenzo La Carrubba and Francesco Carfì Pavia
Polymers 2022, 14(12), 2494; https://doi.org/10.3390/polym14122494 - 19 Jun 2022
Cited by 5 | Viewed by 2332
Abstract
Hybrid porous scaffolds composed of both natural and synthetic biopolymers have demonstrated significant improvements in the tissue engineering field. This study investigates for the first time the fabrication route and characterization of poly-L-lactic acid scaffolds blended with polyhydroxyalkanoate up to 30 wt%. The [...] Read more.
Hybrid porous scaffolds composed of both natural and synthetic biopolymers have demonstrated significant improvements in the tissue engineering field. This study investigates for the first time the fabrication route and characterization of poly-L-lactic acid scaffolds blended with polyhydroxyalkanoate up to 30 wt%. The hybrid scaffolds were prepared by a thermally induced phase separation method starting from ternary solutions. The microstructure of the hybrid porous structures was analyzed by scanning electron microscopy and related to the blend composition. The porosity and the wettability of the scaffolds were evaluated through gravimetric and water contact angle measurements, respectively. The scaffolds were also characterized in terms of the surface chemical properties via Fourier transform infrared spectroscopy in attenuated total reflectance. The mechanical properties were analyzed through tensile tests, while the crystallinity of the PLLA/PHA scaffolds was investigated by differential scanning calorimetry and X-ray diffraction. Full article
Show Figures

Figure 1

27 pages, 7812 KiB  
Article
Performance Optimization Approach of Polymer Modified Asphalt Mixtures with PET and PE Wastes: A Safety Study for Utilizing Eco-Friendly Circular Economy-Based SDGs Concepts
by Faizan Mushtaq, Zhian Huang, Syyed Adnan Raheel Shah, Yinghua Zhang, Yukun Gao, Marc Azab, Sajid Hussain and Muhammad Kashif Anwar
Polymers 2022, 14(12), 2493; https://doi.org/10.3390/polym14122493 - 19 Jun 2022
Cited by 5 | Viewed by 2960
Abstract
Eco-friendly waste utilization helps in the development of sustainable infrastructures. Recently, researchers have focused on the production of road infrastructures using the circular economy concept of human safety. The objective of this study is to investigate and explore the utilization of optimum polymer [...] Read more.
Eco-friendly waste utilization helps in the development of sustainable infrastructures. Recently, researchers have focused on the production of road infrastructures using the circular economy concept of human safety. The objective of this study is to investigate and explore the utilization of optimum polymer waste content for the development of polymer-modified asphalt mixtures using response surface methodology (RSM). RSM based on Box–Behnken design (BBD) was employed to optimize experimental design and included three factors: X1, polymer type; X2, polymer contents; and X3, testing day. The optimized responses determined by the RSM were as follows: MS of 42.98 kN, MF of 5.08 mm, and MQ of 8.66 kN/mm, indicating a favorable and consistent precision in comparison with experimental values. Moreover, the Marshall characteristics of samples prepared with PE were quite improved compared to PET. In conclusion, the incorporation of such polymer wastes in road construction is a sustainable and cost-effective way of improving their engineering properties. This study will help in the development of sustainable road infrastructures supporting human safety and environmentally friendly practices. Full article
(This article belongs to the Special Issue Polymers and the Circular Economy Model)
Show Figures

Figure 1

21 pages, 5056 KiB  
Article
Development of WO3–Nafion Based Membranes for Enabling Higher Water Retention at Low Humidity and Enhancing PEMFC Performance at Intermediate Temperature Operation
by Asmaa Selim, Gábor Pál Szijjártó, Loránd Románszki and András Tompos
Polymers 2022, 14(12), 2492; https://doi.org/10.3390/polym14122492 - 19 Jun 2022
Cited by 9 | Viewed by 2177
Abstract
The proton exchange membrane (PEM) represents a pivotal material and a key challenge in developing fuel cell science and hydrogen technology. Nafion is the most promising polymer which will lead to its commercialisation. Hybrid membranes of nanosized tungsten oxide (WO3) and [...] Read more.
The proton exchange membrane (PEM) represents a pivotal material and a key challenge in developing fuel cell science and hydrogen technology. Nafion is the most promising polymer which will lead to its commercialisation. Hybrid membranes of nanosized tungsten oxide (WO3) and Nafion were fabricated, characterised, and tested in a single cell. The incorporation of 10 wt% WO3 resulted in 21% higher water uptake, 11.7% lower swelling ratio, almost doubling the hydration degree, and 13% higher mechanical stability of the hybrid membrane compared to the Nafion XL. Compared to commercial Nafion XL, the rNF–WO-10 hybrid membrane showed an 8.8% and 20% increase in current density of the cell at 0.4 V operating at 80 and 95 °C with 1.89 and 2.29 A/cm2, respectively. The maximum power density has increased by 9% (0.76 W/cm2) and 19.9% (0.922 W/cm2) when operating at the same temperatures compared to the commercial Nafion XL membrane. Generally, considering the particular structure of Nafion XL, our Nafion-based membrane with 10 wt% WO3 (rNF–WO-10) is a suitable PEM with a comparable performance at different operating conditions. Full article
(This article belongs to the Special Issue Advance in New Energy Materials and Devices)
Show Figures

Graphical abstract

21 pages, 3415 KiB  
Article
Polymeric Microparticles: Synthesis, Characterization and In Vitro Evaluation for Pulmonary Delivery of Rifampicin
by Faiqa Falak Naz, Kifayat Ullah Shah, Zahid Rasul Niazi, Mansoor Zaman, Vuanghao Lim and Mulham Alfatama
Polymers 2022, 14(12), 2491; https://doi.org/10.3390/polym14122491 - 19 Jun 2022
Cited by 5 | Viewed by 2670
Abstract
Rifampicin, a potent broad-spectrum antibiotic, remains the backbone of anti-tubercular therapy. However, it can cause severe hepatotoxicity when given orally. To overcome the limitations of the current oral therapy, this study designed inhalable spray-dried, rifampicin-loaded microparticles using aloe vera powder as an immune [...] Read more.
Rifampicin, a potent broad-spectrum antibiotic, remains the backbone of anti-tubercular therapy. However, it can cause severe hepatotoxicity when given orally. To overcome the limitations of the current oral therapy, this study designed inhalable spray-dried, rifampicin-loaded microparticles using aloe vera powder as an immune modulator, with varying concentrations of alginate and L-leucine. The microparticles were assessed for their physicochemical properties, in vitro drug release and aerodynamic behavior. The spray-dried powders were 2 to 4 µm in size with a percentage yield of 45 to 65%. The particles were nearly spherical with the tendency of agglomeration as depicted from Carr’s index (37 to 65) and Hausner’s ratios (>1.50). The drug content ranged from 0.24 to 0.39 mg/mg, with an association efficiency of 39.28 to 96.15%. The dissolution data depicts that the in vitro release of rifampicin from microparticles was significantly retarded with a higher L-leucine concentration in comparison to those formulations containing a higher sodium alginate concentration due to its hydrophobic nature. The aerodynamic data depicts that 60 to 70% of the aerosol mass was emitted from an inhaler with MMAD values of 1.44 to 1.60 µm and FPF of 43.22 to 55.70%. The higher FPF values with retarded in vitro release could allow sufficient time for the phagocytosis of synthesized microparticles by alveolar macrophages, thereby leading to the eradication of M. tuberculosis from these cells. Full article
(This article belongs to the Special Issue Intelligent Polymeric Delivery System for Biomedical Applications)
Show Figures

Figure 1

19 pages, 5389 KiB  
Article
Effect of Activation Modes on the Property Characterization of Crumb Rubber Powder from Waste Tires and Performance Analysis of Activated Rubber-Modified Asphalt Binder
by Honggang Zhang, Yangpeng Zhang, Jie Chen, Wenchang Liu and Wensheng Wang
Polymers 2022, 14(12), 2490; https://doi.org/10.3390/polym14122490 - 19 Jun 2022
Cited by 8 | Viewed by 1961
Abstract
The rubber molecular chain in waste vulcanized tire rubber will be crosslinked to form a network structure that would be difficult to degrade in asphalt. Crumb rubber treated by desulfurization activation could form active groups on the surface by interrupting the crosslinking bond [...] Read more.
The rubber molecular chain in waste vulcanized tire rubber will be crosslinked to form a network structure that would be difficult to degrade in asphalt. Crumb rubber treated by desulfurization activation could form active groups on the surface by interrupting the crosslinking bond to improve the compatibility between crumb rubber powder and asphalt. To explore the influence of activation modes on crumb rubber powder and the corresponding rubber-modified asphalt binder, crumb rubber powder was firstly activated through three commonly used activation methods and asphalt binder samples modified by activated crumb rubber powder were also prepared. The basic properties of activated crumb rubber powder were characterized by infrared spectroscopy, and conventional tests were used to study the conventional physical properties of the asphalt binder. The infrared spectroscopy and elemental analysis showed that the crumb rubber powder was mainly composed of alkanes, alkenes, sulfonic acids, aromatics, and a little silica rubber and antioxidant zinc oxide, which is suitable for asphalt modification. The simple heat activation treatment method is not enough to greatly destroy the cross-linking structure of crumb rubber powder, but the “C=C” bond was destroyed more seriously. Under the action of adjuvants, the polysulfide cross-linking bond could be broken in crumb rubber powder. The heat treatment and chemical treatment could not achieve the purpose of reducing the viscosity and improving the compatibility of rubber asphalt binder through desulfurization activation. The mechanochemical treatment would help to improve the performance of crumb-rubber-powder-modified asphalt binder. The data correlation analysis based on the grey relational degree can provide a reference for the selection of activated crumb rubber powder for different application requirements in the asphalt modification procedure. Full article
(This article belongs to the Special Issue Advanced Polymers for Pavement Application)
Show Figures

Figure 1

15 pages, 3643 KiB  
Article
Fabrication of Electrospun Xylan-g-PMMA/TiO2 Nanofibers and Photocatalytic Degradation of Methylene Blue
by Yangyang Xie, Xiao-Feng Sun, Wenbo Li, Junhui He, Ran Sun, Sihai Hu and Yaoguo Wu
Polymers 2022, 14(12), 2489; https://doi.org/10.3390/polym14122489 - 18 Jun 2022
Cited by 6 | Viewed by 1829
Abstract
Herein, xylan-g-PMMA was synthesized by grafting poly(methyl methacrylate) (PMMA) onto xylan and characterized by FT-IR and HSQC NMR spectroscopies, and the xylan-g-PMMA/TiO2 solution was used to electrospun nanofibers at the voltage of 15 Kv, which was the first time employing xylan to [...] Read more.
Herein, xylan-g-PMMA was synthesized by grafting poly(methyl methacrylate) (PMMA) onto xylan and characterized by FT-IR and HSQC NMR spectroscopies, and the xylan-g-PMMA/TiO2 solution was used to electrospun nanofibers at the voltage of 15 Kv, which was the first time employing xylan to electrospun nanofibers. Moreover, the electrospinning operating parameters were optimized by assessing the electrospinning process and the morphology of electrospun fibers, as follows: the mixed solvent of DMF and chloroform in a volume ratio of 5:1, an anhydroxylose unit (AXU)/MMA molar ratio lower than 1:2, the flow speed of 0.00565–0.02260 mL/min, and a receiving distance of 10–15 cm. Diameters of the electrospun fibers increased with increasing DMF content in the used solvent mixture, MMA dosage, and receiving distance. TiO2 nanoparticles were successfully dispersed in electrospun xylan-g-PMMA nanofibers and characterized by scanning electron microscopy, energy dispersive X-ray diffraction spectrum, and X-ray photoelectron spectroscopy, and their application for methylene blue (MB) degradation presented above 80% photocatalytic efficiency, showing the good potential in water treatment. Full article
(This article belongs to the Special Issue Biomass Polymers)
Show Figures

Figure 1

16 pages, 1938 KiB  
Article
Characterization, Antioxidant Activities, and Functional Properties of Mucilage Extracted from Corchorus olitorius L.
by Songmin Oh and Do-Yeong Kim
Polymers 2022, 14(12), 2488; https://doi.org/10.3390/polym14122488 - 18 Jun 2022
Cited by 11 | Viewed by 5036
Abstract
This study extracted the mucilage from Corchorus olitorius L. to observe its chemical and functional properties and suggest its possible applications in various fields. Corchorus olitorius L. mucilage was isolated by hot water extraction. FT-IR and HPAEC-PAD were used to describe the chemical [...] Read more.
This study extracted the mucilage from Corchorus olitorius L. to observe its chemical and functional properties and suggest its possible applications in various fields. Corchorus olitorius L. mucilage was isolated by hot water extraction. FT-IR and HPAEC-PAD were used to describe the chemical composition, and the functional properties and antioxidant activities of the mucilage were also examined. The mucilage was mainly composed of uronic acid (34.24%, w/w). The solubility was 79.48 ± 1.08% at 65 °C, the swelling index was 29.01 ± 2.54% at 25 °C, and the water-holding capacity and oil-binding capacity were 28.66 ± 1.48 and 8.423 ± 0.23 g/g, respectively. The mucilage viscosity increased from 4.38 to 154.97 cP in a concentration-dependent manner. Increasing the concentration decreased the emulsion activity and increased the emulsion stability, most likely because of the corresponding increase in surface tension and viscosity. Results from antioxidant assays confirmed that the in-vitro radical scavenging activity of the mucilage increased with concentration. This study shows that C. olitorius L. can be utilized as a new hydrocolloid source, with potential applications in fields ranging from foods to cosmetics and pharmaceuticals. Full article
(This article belongs to the Special Issue Polysaccharides: Structure, Properties, and Applications)
Show Figures

Figure 1

14 pages, 2464 KiB  
Article
Development of Intelligent Gelatin Films Incorporated with Sappan (Caesalpinia sappan L.) Heartwood Extract
by Orapan Romruen, Pimonpan Kaewprachu, Thomas Karbowiak and Saroat Rawdkuen
Polymers 2022, 14(12), 2487; https://doi.org/10.3390/polym14122487 - 18 Jun 2022
Cited by 6 | Viewed by 2476
Abstract
This study aimed to develop intelligent gelatin films incorporated with sappan (Caesalpinia sappan L.) heartwood extracts (SE) and characterize their properties. The intelligent gelatin film was prepared through a casting method from gelatin (3%, w/v), glycerol (25% w/ [...] Read more.
This study aimed to develop intelligent gelatin films incorporated with sappan (Caesalpinia sappan L.) heartwood extracts (SE) and characterize their properties. The intelligent gelatin film was prepared through a casting method from gelatin (3%, w/v), glycerol (25% w/w, based on gelatin weight), and SE at various concentrations (0, 0.25, 0.50, 0.75, and 1.00%, w/v). The thickness of the developed films ranged from 43 to 63 μm. The lightness and transparency of the films decreased with the increasing concentration of SE (p < 0.05). All concentrations of gelatin films incorporated with SE exhibited great pH sensitivity, as indicated by changes in film color at different pH levels (pH 1–12). Significant decreases in tensile strength were observed at 1.00% SE film (p < 0.05). The addition of SE reduced gelatin films’ solubility and water vapor permeability (p < 0.05). The chemical and physical interactions between gelatin and SE affected the absorption peaks in FTIR spectra. SE was affected by increased total phenolic content (TPC) and antioxidant activity of the gelatin film, and the 1.00% SE film showed the highest TPC (15.60 mg GAE/g db.) and antioxidant activity (DPPH: 782.71 μM Trolox/g db. and FRAP: 329.84 mM/g db.). The gelatin films combined with SE could inhibit S. aureus and E. coli, while the inhibition zone was not observed for E. coli; it only affected the film surface area. The result suggested that gelatin films incorporated with SE can be used as an intelligent film for pH indicators and prolong the shelf life of food due to their antioxidant and antimicrobial activities. Full article
(This article belongs to the Special Issue Biopolymer-Based Films and Coatings for Packaging Applications)
Show Figures

Figure 1

14 pages, 3496 KiB  
Article
Selective Removal of Iron, Lead, and Copper Metal Ions from Industrial Wastewater by a Novel Cross-Linked Carbazole-Piperazine Copolymer
by Majed Al Anazi, Ismail Abdulazeez and Othman Charles S. Al Hamouz
Polymers 2022, 14(12), 2486; https://doi.org/10.3390/polym14122486 - 18 Jun 2022
Cited by 3 | Viewed by 2072
Abstract
A novel cross-linked Copolymer (MXM) was synthesized by the polycondensation reaction of 3,6-Diaminocarbazole and piperazine with p-formaldehyde as a cross-linker. The Copolymer was fully characterized by solid 13C-NMR and FT-IR. The thermal stability of MXM was investigated by TGA [...] Read more.
A novel cross-linked Copolymer (MXM) was synthesized by the polycondensation reaction of 3,6-Diaminocarbazole and piperazine with p-formaldehyde as a cross-linker. The Copolymer was fully characterized by solid 13C-NMR and FT-IR. The thermal stability of MXM was investigated by TGA and showed that the Copolymer was stable up to 300 °C. The synthesized polyamine was tested for the removal of iron (Fe2+), lead (Pb2+), and copper (Cu2+) ions from aqueous and industrial wastewater solutions. The effect of pH, concentration and time on the adsorption of iron (Fe2+), lead (Pb2+), and copper (Cu2+) ions was investigated. The adsorption of the studied ions from aqueous solutions onto the MXM polymer occurs following the Freundlich isotherm and pseudo-second-order kinetic models. The intraparticle diffusion model showed that the adsorption mechanism is controlled by film diffusion. The regeneration of MXM showed practical reusability with a loss in capacity of 2–5% in the case of Fe2+ and Cu2+ ions. The molecular simulation investigations revealed similarities between experimental and theoretical calculations. Industrial wastewater treatment revealed the excellent capabilities and design of MXM to be a potential adsorbent for the removal of heavy metal ions. Full article
(This article belongs to the Special Issue Novel Wastewater Treatment Applications Using Polymeric Materials)
Show Figures

Graphical abstract

Previous Issue
Next Issue
Back to TopTop