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Polymers, Volume 15, Issue 1 (January-1 2023) – 249 articles

Cover Story (view full-size image): Biopolymer scaffolds with a tailored biochemical composition and biophysical characteristics are in high demand for tissue regeneration. In this study, the electrospinning technique was applied to generate silk fibroin-CNT composite fibers, which are mechanically strong, well aligned, biocompatible, and electrically conductive. The fibers effectively mediated the electrical stimulation of fibroblasts from patients of pelvic organ prolapse for improved collagen synthesis. The developed material and method offer a simple, direct, and effective way to remedy the dysfunctional fibroblasts of patients for the personalized cell therapeutic treatment of diseases and health conditions associated with collagen disorder. View this paper
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15 pages, 3328 KiB  
Article
Changes in the Electrophysical Parameters of Nanomodified Elastomers Caused by Electric Current’s Passage
by Alexandr V. Shchegolkov, Aleksei V. Shchegolkov, Natalia V. Zemtsova, Yaroslav M. Stanishevskiy and Alexandre A. Vetcher
Polymers 2023, 15(1), 249; https://doi.org/10.3390/polym15010249 - 03 Jan 2023
Cited by 2 | Viewed by 1881
Abstract
The development of reliable and effective functional materials that can be used in various technological fields and environmental conditions is one of the goals of modern nanotechnology. Heating elements’ manufacturing requires understanding the laws of heat transfer under conditions of different supply voltages, [...] Read more.
The development of reliable and effective functional materials that can be used in various technological fields and environmental conditions is one of the goals of modern nanotechnology. Heating elements’ manufacturing requires understanding the laws of heat transfer under conditions of different supply voltages, as this expands the possibilities of such materials’ application. Elastomers based on silicon-organic compounds and polyurethane modified with multi-walled carbon nanotubes (MWCNTs) were studied at various concentrations of Ni/MgO or Co-Mo/MgO and voltages (220, 250, and 300 V). It was found that an increase in voltage from 220 to 300 V leads to an initial increase in specific power on one-third followed by a subsequent decrease in a specific power when switched on again to 220 V (for −40 °C) of up to ~44%. In turn, for a polyurethane matrix, an increase in voltage to 300 V leads to an initial peak power value of ~15% and a decrease in power when switched on again by 220 V (for −40 °C) to ~36% (Ni/MgO -MWCNT). The conducted studies have shown that the use of a polyurethane matrix reduces power degradation (associated with voltage surges above 220 V) by 2.59% for Ni/MgO–based MWCNT and by 10.42% for Co-Mo/MgO. This is due to the better heat resistance of polyurethane and the structural features of the polymer and the MWCNT. The current studies allow us to take the next step in the development of functional materials for electric heating and demonstrate the safety of using heaters at a higher voltage of up to 300 V, which does not lead to their ignition, but only causes changes in electrophysical parameters. Full article
(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)
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13 pages, 2689 KiB  
Article
Controllable Preparation of Superparamagnetic Fe3O4@La(OH)3 Inorganic Polymer for Rapid Adsorption and Separation of Phosphate
by Yao Lu, Xuna Jin, Xiang Li, Minpeng Liu, Baolei Liu, Xiaodan Zeng, Jie Chen, Zhigang Liu, Shihua Yu and Yucheng Xu
Polymers 2023, 15(1), 248; https://doi.org/10.3390/polym15010248 - 03 Jan 2023
Cited by 2 | Viewed by 1737
Abstract
Superparamagnetic Fe3O4 particles have been synthesized by solvothermal method, and a layer of dense silica sol polymer is coated on the surface prepared by sol-gel technique; then La(OH)3 covered the surface of silica sol polymer in an irregular shape [...] Read more.
Superparamagnetic Fe3O4 particles have been synthesized by solvothermal method, and a layer of dense silica sol polymer is coated on the surface prepared by sol-gel technique; then La(OH)3 covered the surface of silica sol polymer in an irregular shape by controlled in situ growth technology. These magnetic materials are characterized by TEM, FT-IR, XRD, SEM, EDS and VSM; the results show that La(OH)3 nanoparticles have successfully modified on Fe3O4 surface. The prepared Fe3O4@La(OH)3 inorganic polymer has been used as adsorbent to remove phosphate efficiently. The effects of solution pH, adsorbent dosage and co-existing ions on phosphate removal are investigated. Moreover, the adsorption kinetic equation and isothermal model are used to describe the adsorption performance of Fe3O4@La(OH)3. It was observed that Fe3O4@La(OH)3 exhibits a fast equilibrium time of 20 min, high phosphate removal rate (>95.7%), high sorption capacity of 63.72 mgP/g, excellent selectivity for phosphate in the presence of competing ions, under the conditions of phosphate concentration 30 mgP/L, pH = 7, adsorbent dose 0.6 g/L and room temperature. The phosphate adsorption process by Fe3O4@La(OH)3 is best described by the pseudo-second-order equation and Langmuir isotherm model. Furthermore, the real samples and reusability experiment indicate that Fe3O4@La(OH)3 could be regenerated after desorption, and 92.78% phosphate removing remained after five cycles. Therefore, La(OH)3 nanoparticles deposited on the surface of monodisperse Fe3O4 microspheres have been synthesized for the first time by a controlled in-situ growth method. Experiments have proved that Fe3O4@La(OH)3 particles with fast separability, large adsorption capacity and easy reusability can be used as a promising material in the treatment of phosphate wastewater or organic pollutants containing phosphoric acid functional group. Full article
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15 pages, 5827 KiB  
Article
Quantitative Measurements of DP in Cellulose Paper Based on Terahertz Spectroscopy
by Qiyu Chen, Lijun Yang, Hua Yu, Yuxin He, Hong Liu and Xuan Wang
Polymers 2023, 15(1), 247; https://doi.org/10.3390/polym15010247 - 03 Jan 2023
Cited by 3 | Viewed by 1788
Abstract
The power transformer is vital to the reliability of the power grid which is most commonly insulated with Kraft paper and immersed in mineral oil, among which the aged state of the paper is mainly correlated to the operating life of the transformer. [...] Read more.
The power transformer is vital to the reliability of the power grid which is most commonly insulated with Kraft paper and immersed in mineral oil, among which the aged state of the paper is mainly correlated to the operating life of the transformer. Degree of polymerization (DP) is a direct parameter to assess the aged condition of insulating paper, but existing DP measurement by viscosity methods are destructive and complicated. In this paper, terahertz time-domain spectroscopy (THz-TDS) was introduced to reach rapid, non-destructive detection of the DP of insulating paper. The absorption spectra of insulating paper show that characteristic peak regions at 1.8 and 2.23 THz both exhibit a log-linear quantitative relationship with DP, and their universalities are confirmed by conducting the above relationship on different types of insulating paper. Fourier transform infrared spectroscopy (FTIR) analysis and molecular dynamics modeling further revealed that 1.8 and 2.23 THz were favorably associated with the growth of water–cellulose hydrogen bond strength and amorphous cellulose, respectively. This paper demonstrates the viability of applying THz-TDS to the non-destructive detection of DP in insulating paper and assigned the vibration modes of the characteristic absorption peaks. Full article
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14 pages, 2485 KiB  
Article
Piezo-Enhanced Photocatalytic Activity of the Electrospun Fibrous Magnetic PVDF/BiFeO3 Membrane
by Farid Orudzhev, Dinara Sobola, Shikhgasan Ramazanov, Klára Částková, Nikola Papež, Daud A. Selimov, Magomed Abdurakhmanov, Abdulatip Shuaibov, Alina Rabadanova, Rashid Gulakhmedov and Vladimír Holcman
Polymers 2023, 15(1), 246; https://doi.org/10.3390/polym15010246 - 03 Jan 2023
Cited by 12 | Viewed by 3212
Abstract
Creating stimulus-sensitive smart catalysts capable of decomposing organic dyes with high efficiency is a critical task in ecology. Combining the advantages of photoactive piezoelectric nanomaterials and ferroelectric polymers can effectively solve this problem by collecting mechanical vibrations and light energy. Using the electrospinning [...] Read more.
Creating stimulus-sensitive smart catalysts capable of decomposing organic dyes with high efficiency is a critical task in ecology. Combining the advantages of photoactive piezoelectric nanomaterials and ferroelectric polymers can effectively solve this problem by collecting mechanical vibrations and light energy. Using the electrospinning method, we synthesized hybrid polymer-inorganic nanocomposite fiber membranes based on polyvinylidene fluoride (PVDF) and bismuth ferrite (BFO). The samples were studied by scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), total transmittance and diffuse reflectance, X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), vibrating-sample magnetometer (VSM), and piezopotential measurements. It has been demonstrated that the addition of BFO leads to an increase in the proportion of the polar phase from 86.5% to 96.1% due to the surface ion–dipole interaction. It is shown that the composite exhibits anisotropy of magnetic properties depending on the orientation of the magnetic field. The results of piezo-photocatalytic experiments showed that under the combined action of ultrasonic treatment and irradiation with both visible and UV light, the reaction rate increased in comparison with photolysis, sonolysis, and piezocatalysis. Moreover, for PVDF/BFO, which does not exhibit photocatalytic activity, under the combined action of light and ultrasound, the reaction rate increases by about 3× under UV irradiation and by about 6× under visible light irradiation. This behavior is explained by the piezoelectric potential and the narrowing of the band gap of the composite due to mechanical stress caused by the ultrasound. Full article
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15 pages, 8987 KiB  
Article
The Effect of Powder and Emulsion Binders on the Tribological Properties of Particulate Filled Glass Fiber Reinforced Polymer Composites
by Wojciech Zurowski, Jaroslaw Zepchlo, Robert Cep, Lenka Cepova, Miroslaw Rucki, Zbigniew Krzysiak, Jacek Caban and Waldemar Samociuk
Polymers 2023, 15(1), 245; https://doi.org/10.3390/polym15010245 - 03 Jan 2023
Cited by 2 | Viewed by 1587
Abstract
Investigations into polymer composites are mainly focused on properties dependent on glass fiber reinforcement and particulate fillers. In the present study, the effect of the binder was examined. The specimens were produced with two types of epoxy resin, with similar numbers of glass [...] Read more.
Investigations into polymer composites are mainly focused on properties dependent on glass fiber reinforcement and particulate fillers. In the present study, the effect of the binder was examined. The specimens were produced with two types of epoxy resin, with similar numbers of glass mat layers and similar proportions of quartz powder added. However, one group was fabricated with an emulsion binder in the glass mats and another group with a powder binder. Attention was concentrated on the tribological properties of the as-prepared composites, though their strength was examined as well. The hardness of the Sikafloor matrix was found to be much more sensitive to the applied binder than that of the MC-DUR matrix. No direct correlation between the microhardness and the specific wear rate was observed and increasing the particulate filler proportion did not cause a direct increase of the specific wear rate. In particular, the highest specific wear rate, around 350 J/g, was reached for both matrices with a 1% quartz addition when the emulsion binder was applied, while in the case of the powder binder it was with 6% quartz with the MC-DUR matrix, and there was no quartz addition with the Sikafloor matrix. The highest microhardness, HV0.5 = 25, in turn, was reached for the mats with the emulsion binder in the Sikafloor matrix with an addition of 10% quartz powder, while the highest friction coefficient was exhibited in the composite with the MC-DUR matrix, when 1% of the quartz powder and the emulsion binder were applied. Full article
(This article belongs to the Special Issue Advances in the Mechanical Behavior of Polymeric Materials)
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18 pages, 2678 KiB  
Article
Dosimetric Characterization of DSF/NaOH/IA-PAE/R. spp. Phantom Material for Radiation Therapy
by Damilola Oluwafemi Samson, Ahmad Shukri, Nurul Ab. Aziz Hashikin, Siti Hajar Zuber, Mohd Zahri Abdul Aziz, Rokiah Hashim, Mohd Fahmi Mohd Yusof, Nor Ain Rabaiee and Sylvester Jande Gemanam
Polymers 2023, 15(1), 244; https://doi.org/10.3390/polym15010244 - 03 Jan 2023
Viewed by 1563
Abstract
Background: Different compositions of DSF/NaOH/IA-PAE/R. spp. composite particleboard phantoms were constructed. Methods: Photon attenuation characteristics were ascertained using gamma rays from 137Cs and 60Co. Absorbed doses at the location of an ionization chamber and Gafchromic EBT3 radiochromic films were calculated [...] Read more.
Background: Different compositions of DSF/NaOH/IA-PAE/R. spp. composite particleboard phantoms were constructed. Methods: Photon attenuation characteristics were ascertained using gamma rays from 137Cs and 60Co. Absorbed doses at the location of an ionization chamber and Gafchromic EBT3 radiochromic films were calculated for high-energy photons (6 and 10 MV) and electrons (6, 9, 12, and 15 MeV). Results: The calculated TPR20,10 values indicate that the percentage discrepancy for 6 and 10 MV was in the range of 0.29–0.72% and 0.26–0.65%. It was also found that the relative difference in the dmax to water and solid water phantoms was between 1.08–1.28% and 5.42–6.70%. The discrepancies in the determination of PDD curves with 6, 9, 12, and 15 MeV, and those of water and solid water phantoms, ranged from 2.40–4.84%. Comparable results were found using the EBT3 films with variations of 2.0–7.0% for 6 and 10 MV photons. Likewise, the discrepancies for 6, 9, 12, and 15 MeV electrons were within an acceptable range of 2.0–4.5%. Conclusions: On the basis of these findings, the DSF/NaOH/IA-PAE/R. spp. particleboard phantoms with 15 wt% IA-PAE addition level can be effectively used as alternative tissue-equivalent phantom material for radiation therapy applications. Full article
(This article belongs to the Special Issue Polymers Synthesis and Characterization)
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17 pages, 2469 KiB  
Article
Interpenetration Networked Polyimide–Epoxy Copolymer under Kinetic and Thermodynamic Control for Anticorrosion Coating
by Dong-Sen Chen, Chun-Hua Chen, Wha-Tzong Whang and Chun-Wei Su
Polymers 2023, 15(1), 243; https://doi.org/10.3390/polym15010243 - 03 Jan 2023
Cited by 1 | Viewed by 1422
Abstract
Epoxy (EP) was copolymerized with polyamic acid (PAA, precursor of polyimide (PI)) with termanil monomers of (1) 4,4′-Oxydianiline (ODA) and (2) pyromellitic dianhydride (PMDA) individually to form (PI-O-EP) and (PI-P-EP) copolymers. The FTIR spectrum of PI-O-EP copolymerization intermediates shows that some amide-EP linkages [...] Read more.
Epoxy (EP) was copolymerized with polyamic acid (PAA, precursor of polyimide (PI)) with termanil monomers of (1) 4,4′-Oxydianiline (ODA) and (2) pyromellitic dianhydride (PMDA) individually to form (PI-O-EP) and (PI-P-EP) copolymers. The FTIR spectrum of PI-O-EP copolymerization intermediates shows that some amide-EP linkages were formed at low temperature and were broken at higher temperature; in additoin, the released amide was available for subsequent imidization to form PI. The curing and imidization of the amide groups on PAA were determined by reaction temperature (kinetic vs. thermodynamic control). In PI-P-EP, the released amide group was very short-lived (fast imidization) and was not observed on FTIR spectra. Formation and breakage of the amide-EP linkages is the key step for EP homopolymerization and formation of the interpenetration network. PI contributed in improving thermal durability and mechanical strength without compromising EP’s adhesion strength. Microphase separations were minimal at PI content less than 10 wt%. The copolymerization reaction in this study followed the “kinetic vs. thermodynamic control” principle. The copolymer has high potential for application in the field of higher-temperature anticorrosion. Full article
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24 pages, 7953 KiB  
Review
Different Production Processes for Thermoplastic Composite Materials: Sustainability versus Mechanical Properties and Processes Parameter
by Marco Valente, Ilaria Rossitti and Matteo Sambucci
Polymers 2023, 15(1), 242; https://doi.org/10.3390/polym15010242 - 03 Jan 2023
Cited by 8 | Viewed by 6133
Abstract
Up to now, fiber-reinforced composites with thermoplastic matrix have seen limited fields of use in the structural scope due to their high viscosity in the molten state, which results in poor impregnability of the reinforcement, leading to mechanical properties of the finished product [...] Read more.
Up to now, fiber-reinforced composites with thermoplastic matrix have seen limited fields of use in the structural scope due to their high viscosity in the molten state, which results in poor impregnability of the reinforcement, leading to mechanical properties of the finished product that are not comparable to those of thermosets. Although the latter still dominate the various sectors of automotive, aerospace, transportation and construction, new applications involving the production of thermoplastic composites are growing rapidly, offering new approaches to the solution of this problem. The aim of this work is to study and evaluate the state of the art on the manufacturing processes of thermoplastic matrix composite, analyzing the parameters that come into play and that most influence the process and material performance. The advantages of film stacking and powder impregnation techniques are contrasted by the versatility of hybrid fabrics and, at the same time, parameters such as pressure and temperature must be carefully considered. A description of different thermoplastic composite processes such as powder impregnation, film stacking molding, hybrid woven fabric, hybrid yarn and products follows, which represent the current possibilities to move from a thermosetting matrix composite to a thermoplastic one, upon which the concept of sustainability is based. This article wants to present an overview of research that has been done in manufacturing thermoplastic reinforced composites and will serve as a baseline and aid for further research and development efforts. Full article
(This article belongs to the Special Issue Advanced Thermoplastic Polymers and Composites)
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15 pages, 7325 KiB  
Article
Pyrolysis Process of Mixed Microplastics Using TG-FTIR and TED-GC-MS
by Min-Hyun Cho, Yu-Jin Song, Chan-Joo Rhu and Byung-Rye Go
Polymers 2023, 15(1), 241; https://doi.org/10.3390/polym15010241 - 03 Jan 2023
Cited by 8 | Viewed by 2632
Abstract
Microplastics have become a ubiquitous contaminant in the environment. The present study focuses on the identification, characterization, and quantification techniques for tracking microplastics. Due to their unique compositional structure, unambiguous identification of individual polymers in various plastic samples, usually comprised of mixtures of [...] Read more.
Microplastics have become a ubiquitous contaminant in the environment. The present study focuses on the identification, characterization, and quantification techniques for tracking microplastics. Due to their unique compositional structure, unambiguous identification of individual polymers in various plastic samples, usually comprised of mixtures of individual polymers, remains a challenge. Therefore, there is limited research on the pyrolysis characterization of mixed samples. In this study, two analytical methods, TG-FTIR and TED-GC-MS combined with thermogravimetric analysis were used to evaluate the thermal-degradation process of individual and mixed samples of polypropylene (PP), polyethylene terephthalate (PET), and polyvinyl chloride (PVC). The primary interaction was the volatilization of terephthalic acid bound to chlorine molecules. The reduction of vinyl-ester functional groups and aromatic hydrocarbon intermediates related to olefin branching was confirmed. Char formation was increased, due to aromatic compounds from PET and PVC. All of the polymers used in the study may be underestimated in quantity, due to combined volatilizations during pyrolysis. TG-FTIR and TED-GC-MS showed forceful advantages in identifying mixed microplastics through different discrimination mechanisms. The study provides deep insight into pyrolysis behaviors and the interactions of mixed polymers, and the obtained results can help better comprehend the complex pyrolysis process. Full article
(This article belongs to the Special Issue Microplastics Degradation and Characterization)
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14 pages, 6515 KiB  
Article
On the Influence of Flame-Retardant Additives on UV-Curable Thermosetting Glass Fiber-Reinforced Composites
by Natalia Gutiérrez Pérez-de-Eulate, Patricia Ares Elejoste, Garazi Goenaga, Maitane Urrutxua, Francisco Javier Vallejo, Jesús Ballestero, Alexandra Allue and José Luis Gómez-Alonso
Polymers 2023, 15(1), 240; https://doi.org/10.3390/polym15010240 - 03 Jan 2023
Cited by 1 | Viewed by 2606
Abstract
One of the main advantages of fiber-reinforced polymer (FRP) composites is the ability to reduce their weight while they exhibit exceptional properties such as high strength, stiffness, and resistance to corrosion, and reduction in their lifetime maintenance when they are compared to the [...] Read more.
One of the main advantages of fiber-reinforced polymer (FRP) composites is the ability to reduce their weight while they exhibit exceptional properties such as high strength, stiffness, and resistance to corrosion, and reduction in their lifetime maintenance when they are compared to the metallic components. These features led fiber-reinforced polymer composites to have applications in the mechanical, construction, aerospace, automotive, medical, marine, and other manufacturing industries. However, the use of this type of material is not possible in all of these applications since, in certain sectors, the fire resistance property that the material must present is one of the key factors. For this reason, a thermosetting resin composed of ultraviolet (UV)-curable acrylic monomers has been used as a matrix, where transparent aluminum trihydrate (ATH) flame-retardant fillers were incorporated for manufacturing flame-retarded UV-curable composites. The composite parts were produced by using glass fiber-reinforced UV-curable prepregs. An exhaustive study of different types of ATH-based flame-retardant additives and the possible cooperation between them to improve the fire properties of the UV-curable composite was carried out. Additionally, the most suitable additive percentage to meet the railway sector requirements was also evaluated, as well as the evolution in the viscosity of the matrix and its processing capacity during the manufacture of the prepregs at 60 °C. The compatibility between the fillers and the matrix was assessed using a dielectric analysis (DEA). The fire properties of both the matrix and the final composite were established. Full article
(This article belongs to the Special Issue Polymeric Fibers in Textiles)
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9 pages, 1485 KiB  
Article
Influence of Spinning Method on Shape Memory Effect of Thermoplastic Polyurethane Yarns
by Lukas Benecke, Robert Tonndorf, Chokri Cherif and Dilbar Aibibu
Polymers 2023, 15(1), 239; https://doi.org/10.3390/polym15010239 - 03 Jan 2023
Cited by 2 | Viewed by 1572
Abstract
Shape memory polymers are gaining increasing attention, especially in the medical field, due to their ability to recover high deformations, low activation temperatures, and relatively high actuation stress. Furthermore, shape memory polymers can be applied as fiber-based solutions for the development of smart [...] Read more.
Shape memory polymers are gaining increasing attention, especially in the medical field, due to their ability to recover high deformations, low activation temperatures, and relatively high actuation stress. Furthermore, shape memory polymers can be applied as fiber-based solutions for the development of smart devices used in many fields, e.g., industry 4.0, medicine, and skill learning. These kind of applications require sensors, actors, and conductive structures. Textile structures address these applications by meeting requirements such as being flexible, adaptable, and wearable. In this work, the influence of spinning methods and parameters on the effect of shape memory polymer yarns was investigated, comparing melt and wet spinning. It is shown that the spinning method can significantly influence the strain fixation and generated stress during the activation of the shape memory effect. Furthermore, for wet spinning, the draw ratio could affect the stress conversion, influencing its efficiency. Therefore, the selection of the spinning process is essential for the setting of application-specific shape-changing properties. Full article
(This article belongs to the Section Polymer Fibers)
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10 pages, 2213 KiB  
Article
The Effect of Transparent Conducting Oxide Films on WO3-Based Electrochromic Devices with Conducting Polymer Electrolytes
by Benedict Wen-Cheun Au, Kah-Yoong Chan, Gregory Soon How Thien, Mian-En Yeoh, Mohd Zainizan Sahdan and Hanabe Chowdappa Ananda Murthy
Polymers 2023, 15(1), 238; https://doi.org/10.3390/polym15010238 - 03 Jan 2023
Cited by 1 | Viewed by 1702
Abstract
Over the past few decades, electrochromism has been a prominent topic in energy-saving applications, which is based on the mechanism of altering the optical transmittance of EC materials under the effect of a small applied voltage. Thus, tungsten oxide (WO3) is [...] Read more.
Over the past few decades, electrochromism has been a prominent topic in energy-saving applications, which is based on the mechanism of altering the optical transmittance of EC materials under the effect of a small applied voltage. Thus, tungsten oxide (WO3) is a significant chemical compound typically applied in electrochromic devices (ECDs) as it is responsible for the optical transmittance variation. In this work, the WO3 films were produced through a sol–gel spin-coating method. The effect of various transparent conducting oxides (TCOs, which are indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO) glass substrates, and aluminum-doped zinc oxide (AZO)) was investigated in the construction of ECDs. Based on a conducting polymer polypyrene carbonate electrolyte, ITO and aluminum-doped zinc oxide (AZO)-coated glasses were also examined as counter electrodes. The electrode combination employing FTO and ITO as the TCO and counter electrode, respectively, exhibited the most significant coloration efficiency of 72.53 cm2/C. It had coloring and bleaching transmittance of 14% and 56%, respectively, with a large optical modulation of 42%. In addition to that, ECDs with the AZO counter electrode have the advantage of lower intercalation charges compared to ITO and FTO. Hence, this research offers a new avenue for understanding the role of common TCO and counter electrodes in the development of WO3-based ECDs with conducting polymer electrolytes. Full article
(This article belongs to the Special Issue Advances in Polyelectrolytes)
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15 pages, 2792 KiB  
Article
Degradation of Diazo Congo Red Dye by Using Synthesized Poly-Ferric-Silicate-Sulphate through Co-Polymerization Process
by Nor Fauziah Zainudin, Sung Ting Sam, Yee Shian Wong, Hanafi Ismail, Saparu Walli, Kazuki Inoue, Go Kawamura and Wai Kian Tan
Polymers 2023, 15(1), 237; https://doi.org/10.3390/polym15010237 - 03 Jan 2023
Cited by 7 | Viewed by 1614
Abstract
The ability of poly-ferric-silicate-sulphate (PFSS) synthesized via a co-polymerization process has been applied for the removal of diazo Congo red dye. A novel degradation pathway of diazo Congo red dye by using PFSS is proposed based on LC–MS analysis. Diazo Congo red dye [...] Read more.
The ability of poly-ferric-silicate-sulphate (PFSS) synthesized via a co-polymerization process has been applied for the removal of diazo Congo red dye. A novel degradation pathway of diazo Congo red dye by using PFSS is proposed based on LC–MS analysis. Diazo Congo red dye was successfully removed using synthesized PFSS at lower coagulant dosages and a wider pH range, i.e., 9 mg/L from pH 5 to 7, 11 mg/L at pH 9, and 50 mg/L at pH 11. The azo bond cleavage was verified by the UV–Vis spectra of diazo Congo red-loaded PFSS and FTIR spectra which showed disappearance of the peak at 1584 cm−1 for –N=N– stretching vibrations. The synchronized results of UV–Vis spectra, FTIR, and the LC–MS analysis in this study confirmed the significance of the Si and Fe bond in PFSS towards the degradation of diazo Congo red dye. The successfully synthesized PFSS coagulant was characterized by FTIR, SEM, TEM, and HRTEM analysis. From this analysis, it was proven that PFSS is a polycrystalline material which is favorable for the coagulation–flocculation process. Based on all these findings, it was established that synthesized PFSS can be employed as a highly efficient polymeric coagulant for the removal of dye from wastewater. Full article
(This article belongs to the Special Issue Application of Polymers for Removing Environmental Pollutants)
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10 pages, 1731 KiB  
Article
The Influence on Fracture Resistance of Different Composite Resins and Prefabricated Posts to Restore Endodontically Treated Teeth
by Saulo Pamato, Weber Adad Ricci, Milton Carlos Kuga, Eliane Cristina Gulin de Oliveira, João Carlos Silos Moraes, Marcus Vinicius Reis Só, Tamara Carolina Trevisan, Newton Fahl Júnior and Jefferson Ricardo Pereira
Polymers 2023, 15(1), 236; https://doi.org/10.3390/polym15010236 - 03 Jan 2023
Cited by 4 | Viewed by 1754
Abstract
Recent formulations of resin-based composites have incorporated different combinations of materials. However, the mechanical and bonding behavior of these materials with intraradicular posts are unclear. This study aimed to evaluate the effect of light-cure and dual-cure resin composite posts on the fracture resistance [...] Read more.
Recent formulations of resin-based composites have incorporated different combinations of materials. However, the mechanical and bonding behavior of these materials with intraradicular posts are unclear. This study aimed to evaluate the effect of light-cure and dual-cure resin composite posts on the fracture resistance of endodontically-treated teeth. Materials and Methods: Ninety extracted human upper canines were selected and randomly divided into nine groups (n=10): (G1) endodontically treated teeth without endodontic posts; (G2) glass-fiber post cemented with glass-ionomer cement; (G3) endodontic post by dual-cure composite resin (Rebilda DC); (G4) endodontic post by dual-cure composite resin (Cosmecore); (G5) endodontic post by dual-cure composite resin (Bis-Core); (G6) endodontic post by light-cure composite resin; (G7) glass-fiber post customized with flowable composite resin; (G8) glass-fiber post cemented with light-cure composite resin; (G9) glass-fiber post cemented with self-adhesive resin cement. After the post insertion, all specimens were subjected to mechanical (250,000 cycles) and thermocycling (6000 cycles, 5 °C/55 °C) and immediate loading at 45 degrees in a universal testing machine until fracture. The data were analyzed by one-way ANOVA and multiple comparisons using the Fisher LSD Method (p < 0 05). Results: The mean failure loads (±SD) for the groups ranged from 100.7 ± 22.6 N to 221.9 ± 48.9 N. The G1 group (without endodontic posts) had a higher fracture strength than all experimental groups (p < 0.001). Conclusions: Within the limitations, the light- and dual-cure post technique did not present lower fracture resistance values as compared to the conventional glass-fiber post. Full article
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14 pages, 3746 KiB  
Article
The Synergistic Effect of Polystyrene/Modified Boron Nitride Composites for Enhanced Mechanical, Thermal and Conductive Properties
by Shafi Ur Rehman, Sana Javaid, Muhammad Shahid, Nasir Mahmood Ahmad, Badar Rashid, Caroline R. Szczepanski and Asim Shahzad
Polymers 2023, 15(1), 235; https://doi.org/10.3390/polym15010235 - 02 Jan 2023
Cited by 2 | Viewed by 1789
Abstract
Thermal conductivity (TC) and thermal stability are the basic requirements and highly desirable properties in thermal management, heat storage and heat transfer applications. This work is regarding the fabrication of polystyrene/boron nitride composites and melt extruded to produce good thermal stability, increased thermal [...] Read more.
Thermal conductivity (TC) and thermal stability are the basic requirements and highly desirable properties in thermal management, heat storage and heat transfer applications. This work is regarding the fabrication of polystyrene/boron nitride composites and melt extruded to produce good thermal stability, increased thermal conductivity and enhanced mechanical properties. Our strategy is potentially applicable to produce thermally conductive composites of low cost over large scale. Boron nitride powder is bath sonicated in 10% NH3 solution to avoid its agglomeration and tendency toward entanglement in a polymer matrix. An approximately 67.43% increase in thermal conductivity and 69.37% increase in tensile strength as well as 56 multiple increases in thermal stability of the optimum samples were achieved. The developed polymeric composites are potentially applicable in the electronic industry, especially in electronic devices used for 5G, heat sink and several other aviation applications. Full article
(This article belongs to the Special Issue Polymer-Based Hybrid Composites II)
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19 pages, 9897 KiB  
Article
Elasto-Plastic Mechanical Modeling of Fused Deposition 3D Printing Materials
by Francesco Bandinelli, Lorenzo Peroni and Alberto Morena
Polymers 2023, 15(1), 234; https://doi.org/10.3390/polym15010234 - 02 Jan 2023
Cited by 11 | Viewed by 1853
Abstract
Fused deposition modeling (FDM) is one of the most common 3D printing technologies and is becoming a well-established production method. Short fiber-reinforced polymers represent a new class of printing materials that enhance the mechanical properties of final components, thus informing an interesting subject [...] Read more.
Fused deposition modeling (FDM) is one of the most common 3D printing technologies and is becoming a well-established production method. Short fiber-reinforced polymers represent a new class of printing materials that enhance the mechanical properties of final components, thus informing an interesting subject of analysis for this study. FDM-printed parts are characterized by a strong anisotropy, so their behavior should be analyzed accordingly. The authors proposed a modeling strategy based on a transversely isotropic behavior hypothesis, representing material behaviors associated with an elasticity matrix in relation to the elastic field and a combination of Hill’s yield criterion and Voce’s isotropic hardening law for the plastic field. Material properties of materials were experimentally identified through tensile tests on dog bone specimens printed with different orientations in space. The numerical model was then calibrated using the finite element software LS-DYNA and the optimization software LS-OPT. An agreement between numerical and experimental results showed the robustness of the modeling strategy proposed to describe the stress behaviors of printed materials until a maximum load is reached, while strain behaviors have yet to be correctly defined due to the difficulties associated with evaluating an equivalent deformation. Full article
(This article belongs to the Special Issue Plastics II)
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16 pages, 2899 KiB  
Article
Predicting Characteristics of Dissimilar Laser Welded Polymeric Joints Using a Multi-Layer Perceptrons Model Coupled with Archimedes Optimizer
by Essam B. Moustafa and Ammar Elsheikh
Polymers 2023, 15(1), 233; https://doi.org/10.3390/polym15010233 - 02 Jan 2023
Cited by 66 | Viewed by 2954
Abstract
This study investigates the application of a coupled multi-layer perceptrons (MLP) model with Archimedes optimizer (AO) to predict characteristics of dissimilar lap joints made of polymethyl methacrylate (PMMA) and polycarbonate (PC). The joints were welded using the laser transmission welding (LTW) technique equipped [...] Read more.
This study investigates the application of a coupled multi-layer perceptrons (MLP) model with Archimedes optimizer (AO) to predict characteristics of dissimilar lap joints made of polymethyl methacrylate (PMMA) and polycarbonate (PC). The joints were welded using the laser transmission welding (LTW) technique equipped with a beam wobbling feature. The inputs of the models were laser power, welding speed, pulse frequency, wobble frequency, and wobble width; whereas, the outputs were seam width and shear strength of the joint. The Archimedes optimizer was employed to obtain the optimal internal parameters of the multi-layer perceptrons. In addition to the Archimedes optimizer, the conventional gradient descent technique, as well as the particle swarm optimizer (PSO), was employed as internal optimizers of the multi-layer perceptrons model. The prediction accuracy of the three models was compared using different error measures. The AO-MLP outperformed the other two models. The computed root mean square errors of the MLP, PSO-MLP, and AO-MLP models are (39.798, 19.909, and 2.283) and (0.153, 0.084, and 0.0321) for shear strength and seam width, respectively. Full article
(This article belongs to the Special Issue Processing of Polymeric Materials)
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18 pages, 4028 KiB  
Article
Palladium Nanoparticles on Chitosan-Coated Superparamagnetic Manganese Ferrite: A Biocompatible Heterogeneous Catalyst for Nitroarene Reduction and Allyl Carbamate Deprotection
by Mona Ebadi, Nurul Asikin-Mijan, Mohd Suzeren Md. Jamil, Anwar Iqbal, Emad Yousif, Ahmad Rifqi Md Zain, Tengku Hasnan Tengku Aziz and Muhammad Rahimi Yusop
Polymers 2023, 15(1), 232; https://doi.org/10.3390/polym15010232 - 01 Jan 2023
Cited by 3 | Viewed by 2565
Abstract
Although metallic nanocatalysts such as palladium nanoparticles (Pd NPs) are known to possess higher catalytic activity due to their large surface-to-volume ratio, however, in nanosize greatly reducing their activity due to aggregation. To overcome this challenge, superparamagnetic chitosan-coated manganese ferrite was successfully prepared [...] Read more.
Although metallic nanocatalysts such as palladium nanoparticles (Pd NPs) are known to possess higher catalytic activity due to their large surface-to-volume ratio, however, in nanosize greatly reducing their activity due to aggregation. To overcome this challenge, superparamagnetic chitosan-coated manganese ferrite was successfully prepared and used as a support for the immobilization of palladium nanoparticles to overcome the above-mentioned challenge. The Pd-Chit@MnFe2O4 catalyst exhibited high catalytic activity in 4-nitrophenol and 4-nitroaniline reductions, with respective turnover frequencies of 357.1 min−1 and 571.4 min−1, respectively. The catalyst can also be recovered easily by magnetic separation after each reaction. Additionally, the Pd-Chit@MnFe2O4 catalyst performed well in the reductive deprotection of allyl carbamate. Coating the catalyst with chitosan reduced the Pd leaching and its cytotoxicity. Therefore, the catalytic activity of Pd-Chit@MnFe2O4 was proven to be unrestricted in biology conditions. Full article
(This article belongs to the Special Issue Coatings Using Chitosan and Its Derivatives)
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13 pages, 3166 KiB  
Article
Dielectric Characteristics of Crosslinked Polyethylene Modified by Grafting Polar-Group Molecules
by Jun-Guo Gao, Li-Wei Liu and Wei-Feng Sun
Polymers 2023, 15(1), 231; https://doi.org/10.3390/polym15010231 - 01 Jan 2023
Cited by 3 | Viewed by 2206
Abstract
Polar group-modified crosslinked polyethylene (XLPE) materials are developed with a peroxide thermochemical method of individually grafting chloroacetic acid allyl ester (CAAE) and maleic anhydride (MAH) to polyethylene molecular-chains, which are dedicated to ameliorating dielectric characteristics through charge-trapping mechanism. By free radical addition reactions, [...] Read more.
Polar group-modified crosslinked polyethylene (XLPE) materials are developed with a peroxide thermochemical method of individually grafting chloroacetic acid allyl ester (CAAE) and maleic anhydride (MAH) to polyethylene molecular-chains, which are dedicated to ameliorating dielectric characteristics through charge-trapping mechanism. By free radical addition reactions, the CAAE and MAH molecules are successfully grafted to polyethylene molecular chains of XLPE in crosslinking process, as verified by infrared spectroscopy molecular characterizations. Dielectric spectra, electric conductance, and dielectric breakdown strength are tested to evaluate the improved dielectric performances. Charge trap characteristics are investigated by analyzing thermal stimulation depolarization currents in combination with first-principles electronic-structure calculations to reveal the polar-group introduced mechanisms of contributing dipole dielectric polarization, impeding electric conduction, and promoting electrical breakdown field. The grafted polar-group molecules, especially for MAH, can introduce deep-level charge traps in XLPE materials to effectively restrict charge injections and hinder charge carrier transports, which accounts for the significant improvements in electric resistance and dielectric breakdown strength. Full article
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15 pages, 6912 KiB  
Article
Macro-Size Regenerated Cellulose Fibre Embedded with Graphene Oxide with Antibacterial Properties
by Nyak Syazwani Nyak Mazlan, Kushairi Mohd Salleh, Mohamad Khalid Khairunnisa-Atiqah, Abdul Hair Ainul Hafiza, Marhaini Mostapha, Amanda V. Ellis and Sarani Zakaria
Polymers 2023, 15(1), 230; https://doi.org/10.3390/polym15010230 - 01 Jan 2023
Cited by 2 | Viewed by 1658
Abstract
Macro-size regenerated cellulose fibres (RCFs) with embedded graphene oxide (GO) were fabricated by dissolving cellulose in a pre-cooled sodium hydroxide (NaOH)/urea solution and regenerated in sulphuric acid (H2SO4) coagulant. Initially, GO was found to disperse well in the cellulose [...] Read more.
Macro-size regenerated cellulose fibres (RCFs) with embedded graphene oxide (GO) were fabricated by dissolving cellulose in a pre-cooled sodium hydroxide (NaOH)/urea solution and regenerated in sulphuric acid (H2SO4) coagulant. Initially, GO was found to disperse well in the cellulose solution due to intercalation with the cellulose; however, this cellulose–GO intercalation was disturbed during the regeneration process, causing agglomeration of GO in the RCF mixture. Agglomerated GO was confirmed at a higher GO content under a Dino-Lite microscope. The crystallinity index (CrI) and thermal properties of the RCFs increased with increasing GO loadings, up to 2 wt.%, and reduced thereafter. Cellulose–GO intercalation was observed at lower GO concentrations, which enhanced the crystallinity and thermal properties of the RCF–GO composite. It was shown that the GO exhibited antibacterial properties in the RCF–GO composite, with the highest bacterial inhibition against E. coli and S. aureus. Full article
(This article belongs to the Special Issue Cellulose Fiber Polymer Composites)
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15 pages, 3089 KiB  
Article
Synthesis and Characterization of Benzene- and Triazine-Based Azo-Bridged Porous Organic Polymers
by Barbara Panić, Tea Frey, Mladen Borovina, Kristijan Konopka, Miro Sambolec, Ivan Kodrin and Ivana Biljan
Polymers 2023, 15(1), 229; https://doi.org/10.3390/polym15010229 - 01 Jan 2023
Cited by 7 | Viewed by 2121
Abstract
Porous organic polymers incorporating nitrogen-rich functionalities have recently emerged as promising materials for efficient and highly selective CO2 capture and separation. Herein, we report synthesis and characterization of new two-dimensional (2D) benzene- and triazine-based azo-bridged porous organic polymers. Different synthetic approaches towards [...] Read more.
Porous organic polymers incorporating nitrogen-rich functionalities have recently emerged as promising materials for efficient and highly selective CO2 capture and separation. Herein, we report synthesis and characterization of new two-dimensional (2D) benzene- and triazine-based azo-bridged porous organic polymers. Different synthetic approaches towards the porous azo-bridged polymers were tested, including reductive homocoupling of aromatic nitro monomers, oxidative homocoupling of aromatic amino monomers and heterocoupling of aromatic nitro monomers and a series of aromatic diamines of different lengths and rigidity. IR spectroscopy, 13C CP/MAS NMR spectroscopy, powder X-ray diffraction, elemental analysis, thermogravimetric analysis, nitrogen adsorption–desorption experiments and computational study were used to characterize structures and properties of the resulting polymers. The synthesized azo-bridged polymers are all amorphous solids of good thermal stability, exhibiting various surface areas (up to 351 m2 g−1). The obtained results indicated that the synthetic methods and building units have a pronounced effect on the porosity of the final materials. Reductive and oxidative homocoupling of aromatic nitro and amino building units, respectively, lead to 2D azo-bridged polymers of substantially higher porosity when compared to those produced by heterocoupling reactions. Periodic DFT calculations and Grand-canonical Monte Carlo (GCMC) simulations suggested that, within the used approximations, linear linkers of different lengths do not significantly affect CO2 adsorption properties of model azo-bridged polymers. Full article
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16 pages, 5408 KiB  
Article
Hierarchical Macroporous PolyDCPD Composites from Surface-Modified Calcite-Stabilized High Internal Phase Emulsions
by Ali Eslek, Hatice Hande Mert, Meltem Sözbir, Mohamed Alaasar and Emine Hilal Mert
Polymers 2023, 15(1), 228; https://doi.org/10.3390/polym15010228 - 01 Jan 2023
Viewed by 1772
Abstract
High Internal Phase Emulsions (HIPEs) of dicyclopentadiene (DCPD) were prepared using mixtures of surface-modified calcite (mCalcite) and a non-ionic surfactant. Twelve different emulsion formulations were created using an experimental design methodology. Three distinctive levels of the internal phase ratio, the amount [...] Read more.
High Internal Phase Emulsions (HIPEs) of dicyclopentadiene (DCPD) were prepared using mixtures of surface-modified calcite (mCalcite) and a non-ionic surfactant. Twelve different emulsion formulations were created using an experimental design methodology. Three distinctive levels of the internal phase ratio, the amount of mCalcite loading, and the surfactant were used to prepare the HIPEs. Accordingly, macroporous polyDCPD composites were synthesized by performing ring-opening metathesis polymerization (ROMP) on the HIPEs. The variations in the morphological and physical properties of the composites were investigated in terms of experimental parameters. In the end, five different model equations were derived with a confidence level of 95%. The main and binary interaction effects of the experimental parameters on the responses, such as the average cavity size, interconnecting pore size, specific surface area, foam density, and compression modulus, were demonstrated. The synergistic interaction between the amount of surfactant, the amount of mCalcite loading, and the internal phase ratio appeared to have a dominant role in the average cavity diameter. The solo effect of the internal phase ratio on the interconnecting pore size, foam density, and compression modulus was confirmed. In addition, it was demonstrated that the specific surface area of the composites was mainly changed depending on the amount of mCalcite loading. Full article
(This article belongs to the Section Polymer Analysis and Characterization)
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18 pages, 8285 KiB  
Article
Lightweight and High Impact Toughness PP/PET/POE Composite Foams Fabricated by In Situ Nanofibrillation and Microcellular Injection Molding
by Junwei Sun, Qian Li, Yufan Jiang, Jing Jiang, Lian Yang, Caiyi Jia, Feng Chen and Xiaofeng Wang
Polymers 2023, 15(1), 227; https://doi.org/10.3390/polym15010227 - 01 Jan 2023
Cited by 5 | Viewed by 2186
Abstract
Polypropylene (PP) has become the most promising and candidate material for fabricating lightweight products. Microcellular injection molding (MIM) is a cost-effective technology for manufacturing porous plastic products. However, it is still challenging to fabricate high-performance PP microcellular components. Herein, we reported an efficient [...] Read more.
Polypropylene (PP) has become the most promising and candidate material for fabricating lightweight products. Microcellular injection molding (MIM) is a cost-effective technology for manufacturing porous plastic products. However, it is still challenging to fabricate high-performance PP microcellular components. Herein, we reported an efficient strategy to produce lightweight and high impact toughness foamed PP/polyethylene terephthalate (PET)/polyolefin-based elastomer (POE) components by combining in situ fibrillation (INF) and MIM technologies. First, the INF composite was prepared by integrating twin-screw compounding with melt spinning. SEM analysis showed PET nanofibrils with a diameter of 258 nm were achieved and distributed uniformly in the PP due to the POE’s inducing elaboration effect. Rheological and DSC analysis demonstrated PET nanofibrils pronouncedly improved PP’s viscoelasticity and crystal nucleation rate, respectively. Compared with PP foam, INF composite foam showed more stretched cells in the skin layer and refined spherical cells in the core layer. Due to the synergistic toughening effect of PET nanofibrils and POE elastic particles, the impact strength of INF composite foams was 295.3% higher than that of PP foam and 191.2% higher than that of melt-blended PP/PET foam. The results gathered in this study reveal potential applications for PP based INF composite foams in the manufacturing of lightweight automotive products with enhanced impact properties. Full article
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13 pages, 4342 KiB  
Article
Evaluation of Effective Crosslinking Density for Pseudo-Semi Interpenetrating Polymer Networks Based on Polyether Glycols Mixture by Dynamic Mechanical Analysis
by Yajin Li, Bingbing Sun, Yunfei Liu, Zhengzhong Zhang, Yupeng Shen, Haiyang Wang, Xiaojun Liu and Wuxi Xie
Polymers 2023, 15(1), 226; https://doi.org/10.3390/polym15010226 - 01 Jan 2023
Cited by 2 | Viewed by 1621
Abstract
Pseudo-semi interpenetrating polymer networks (pseudo-semi IPNs) are a special example of topological isomerism in macromolecules, which have attracted significant attention in recent years with a high potential in a variety of engineering applications of polymeric materials. In this article, pseudo-semi IPNs were synthetized [...] Read more.
Pseudo-semi interpenetrating polymer networks (pseudo-semi IPNs) are a special example of topological isomerism in macromolecules, which have attracted significant attention in recent years with a high potential in a variety of engineering applications of polymeric materials. In this article, pseudo-semi IPNs were synthetized by sequential polymerization of thermoplastic polymers (TPEs) in the presence of thermosetting elastomer (TSEs) with contents of 10, 20, 30, 40 and 50 wt.% in a vacuum oven at 60 °C for about 72 h. In addition, this article describes a method for researching the elastic modulus, effective crosslinking density and physical crosslinking density of TSEs and pseudo-semi IPNs. The inherent interactions and entanglements of pseudo-semi IPNs were discussed by analyzing the changes in elastic modulus and effective crosslinking density at different temperatures. The results show that after the TPE was added to the TSE matrix as a plastic-reinforced material, the ductility increased from 89.6% to 491%, the effective crosslinking density was increased by 100% at high temperatures and the strength of the material matrix was significantly improved. Two physical events take place in our pseudo-semi IPNs as result of energy dissipation and polymeric chains mobility. Full article
(This article belongs to the Section Polymer Networks)
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15 pages, 724 KiB  
Review
Recent Developments in Molecular Characterization, Bioactivity, and Application of Arabinoxylans from Different Sources
by Jinxin Pang, Yi Zhang, Xiaoyang Tong, Yaoguang Zhong, Fanjun Kong, Dan Li, Xifan Liu and Yongjin Qiao
Polymers 2023, 15(1), 225; https://doi.org/10.3390/polym15010225 - 01 Jan 2023
Cited by 8 | Viewed by 2047
Abstract
Arabinoxylan (AX) is a polysaccharide composed of arabinose, xylose, and a small number of other carbohydrates. AX comes from a wide range of sources, and its physicochemical properties and physiological functions are closely related to its molecular characterization, such as branched chains, relative [...] Read more.
Arabinoxylan (AX) is a polysaccharide composed of arabinose, xylose, and a small number of other carbohydrates. AX comes from a wide range of sources, and its physicochemical properties and physiological functions are closely related to its molecular characterization, such as branched chains, relative molecular masses, and substituents. In addition, AX also has antioxidant, hypoglycemic, antitumor, and proliferative abilities for intestinal probiotic flora, among other biological activities. AXs of various origins have different molecular characterizations in terms of molecular weight, degree of branching, and structure, with varying structures leading to diverse effects of the biological activity of AX. Therefore, this report describes the physical properties, biological activities, and applications of AX in diverse plants, aiming to provide a theoretical basis for future research on AX as well as provide more options for crop breeding. Full article
(This article belongs to the Section Biomacromolecules, Biobased and Biodegradable Polymers)
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19 pages, 6083 KiB  
Article
Thermal Degradation and Carbonization Mechanism of Fe-Based Metal-Organic Frameworks onto Flame-Retardant Polyethylene Terephthalate
by Tianyi Ma, Wenqing Wang and Rui Wang
Polymers 2023, 15(1), 224; https://doi.org/10.3390/polym15010224 - 01 Jan 2023
Cited by 2 | Viewed by 2110
Abstract
Currently, the metal-organic framework (MOF) is a promising candidate for flame−retardant polymers. In this study, a Fe−based MOF, MIL-88B(Fe), was introduced to polyethylene terephthalate (PET) and 3−hydroxyphenylphosphinyl-propanoic acid copolymer (P−PET) to reduce the fire hazard involved in using PET. The limiting oxygen indexes [...] Read more.
Currently, the metal-organic framework (MOF) is a promising candidate for flame−retardant polymers. In this study, a Fe−based MOF, MIL-88B(Fe), was introduced to polyethylene terephthalate (PET) and 3−hydroxyphenylphosphinyl-propanoic acid copolymer (P−PET) to reduce the fire hazard involved in using PET. The limiting oxygen indexes (LOIs) of MIL−PET and MIL−P−PET improved by 27% and 30%, respectively. The UL−94 level achieved for MIL−P−PET was V−0 rating. The thermal degradation and carbonization mechanisms of MIL−PET and MIL−P−PET were systematically investigated through thermogravimetric analysis coupled with a Fourier transform infrared spectroscopy (TG−IR), pyrolysis-gas chromatography−mass spectrometry (Py−GC−MS), x−ray photoelectron spectroscopy (XPS), and Raman spectrum combined with quantum chemical molecular dynamics simulation. With the addition of MIL−88B(Fe), high graphitization and a hard flammability char residual were generated. Compared with neat PET, the ferric ions efficiently catalyzed the homolytic cleavage and dehydrogenation of PET to produce a large amount of CO2 and terephthalic acid for MIL−PET in gas phase. Rough and hierarchical char residual with ferric oxide was also generated when temperatures exceeded 600 °C. However, the carbonization process was inhibited due to the coordinated complex between phosphorus and ferric ions in MIL−P−PET, invaliding the decarboxylation and generating more benzoic acid and its precursor, which led to heavy smoke. Full article
(This article belongs to the Special Issue Flame-Retardant Polymer Composites)
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19 pages, 9960 KiB  
Article
PCL/Collagen/UA Composite Biomedical Dressing with Ordered Microfiberous Structure Fabricated by a 3D Near-Field Electrospinning Process
by Zhirui Mai, Qilong Liu, Yongshuang Bian, Peng Wang, Xuewei Fu, Dongsong Lin, Nianzi Kong, Yuqing Huang, Zijun Zeng, Dingfan Li, Wenxu Zheng, Yuanjun Xia and Wuyi Zhou
Polymers 2023, 15(1), 223; https://doi.org/10.3390/polym15010223 - 31 Dec 2022
Cited by 5 | Viewed by 1928
Abstract
In this work, a functionalized polycaprolactone (PCL) composite fiber combining calf-type I collagen (CO) and natural drug usnic acid (UA) was prepared, in which UA was used as an antibacterial agent. Through 3D near-field electrospinning, the mixed solution was prepared into PCL/CO/UA composite [...] Read more.
In this work, a functionalized polycaprolactone (PCL) composite fiber combining calf-type I collagen (CO) and natural drug usnic acid (UA) was prepared, in which UA was used as an antibacterial agent. Through 3D near-field electrospinning, the mixed solution was prepared into PCL/CO/UA composite fibers (PCUCF), which has a well-defined perfect arrangement structure. The influence of electrospinning process parameters on fiber diameter was investigated, the optimal electrospinning parameters were determined, and the electric field simulation was conducted to verify the optimal parameters. The addition of 20% collagen made the composite fiber have good hydrophilicity and water absorption property. In the presence of PCUCF, 1% UA content significantly inhibited the growth rate of Gram-positive and negative bacteria in the plate culture. The AC-PCUCF (after crosslinking PCUCF) prepared by crosslinking collagen with genipin showed stronger mechanical properties, water absorption property, thermal stability, and drug release performance. Cell proliferation experiments showed that PCUCF and AC-PCUCF had no cytotoxicity and could promote cell proliferation and adhesion. The results show that PCL/CO/UA composite fiber has potential application prospects in biomedical dressing. Full article
(This article belongs to the Special Issue Advances in Applications and Sustainability of Electrospinning)
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35 pages, 15696 KiB  
Review
Biodegradable Polymers in Triboelectric Nanogenerators
by Yajun Mi, Yin Lu, Yalin Shi, Zequan Zhao, Xueqing Wang, Jiajing Meng, Xia Cao and Ning Wang
Polymers 2023, 15(1), 222; https://doi.org/10.3390/polym15010222 - 31 Dec 2022
Cited by 26 | Viewed by 3611
Abstract
Triboelectric nanogenerators (TENGs) have attracted much attention because they not only efficiently harvest energy from the surrounding environment and living organisms but also serve as multifunctional sensors toward the detection of various chemical and physical stimuli. In particular, biodegradable TENG (BD-TENG) represents an [...] Read more.
Triboelectric nanogenerators (TENGs) have attracted much attention because they not only efficiently harvest energy from the surrounding environment and living organisms but also serve as multifunctional sensors toward the detection of various chemical and physical stimuli. In particular, biodegradable TENG (BD-TENG) represents an emerging type of self-powered device that can be degraded, either in physiological environments as an implantable power source without the necessity of second surgery for device retrieval, or in the ambient environment to minimize associated environmental pollution. Such TENGs or TNEG-based self-powered devices can find important applications in many scenarios, such as tissue regeneration, drug release, pacemakers, etc. In this review, the recent progress of TENGs developed on the basis of biodegradable polymers is comprehensively summarized. Material strategies and fabrication schemes of biodegradable and self-powered devices are thoroughly introduced according to the classification of plant-degradable polymer, animal-degradable polymer, and synthetic degradable polymer. Finally, current problems, challenges, and potential opportunities for the future development of BD-TENGs are discussed. We hope this work may provide new insights for modulating the design of BD-TNEGs that can be beneficial for both environmental protection and healthcare. Full article
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21 pages, 9497 KiB  
Article
Furanic Polymerization Causes the Change, Conservation and Recovery of Thermally-Treated Wood Hydrophobicity before and after Moist Conditions Exposure
by Bengang Zhang, Mathieu Petrissans, Anelie Petrissans, Antonio Pizzi and Baptiste Colin
Polymers 2023, 15(1), 221; https://doi.org/10.3390/polym15010221 - 31 Dec 2022
Cited by 1 | Viewed by 1232
Abstract
The Whilhelmy method of contact angle, wood thermal properties (TG/DTG), infrared spectroscopy, etc. was used to define the hydrophobicity of heat-treated beech and fir wood at increasing temperatures between 120 °C and 300 °C. By exposure to wet conditions during 1 week, the [...] Read more.
The Whilhelmy method of contact angle, wood thermal properties (TG/DTG), infrared spectroscopy, etc. was used to define the hydrophobicity of heat-treated beech and fir wood at increasing temperatures between 120 °C and 300 °C. By exposure to wet conditions during 1 week, the hydrophobic character obtained by the heat treatment remains constant heat-treated. Heat induced wood hydrophobation, was shown by CP MAS 13C NMR and MALDI ToF mass spectrometry to be mainly caused by furanic moieties produced from heat-induced hemicelluloses degradation. This is caused by the acid environment generated by the hydrolysis of the hemicelluloses acetyl groups. Furfural polymerizes to linear and branched oligomers and finally to water repellent, insoluble furanic resins. The water repellent, black colored, cross-linked polymerized furanic network is present throughout the heat-treated wood. Wood darkening as well as its water repellency due to increasing proportions of black colored furanic resins increase as a function of the increase with treating temperature, becoming particularly evident in the 200 to 300 °C treating temperature range. Full article
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26 pages, 12635 KiB  
Review
A Comprehensive Technical Review of the Friction Stir Welding of Metal-to-Polymer Hybrid Structures
by Ali A. Barakat, Basil M. Darras, Mohammad A. Nazzal and Aser Alaa Ahmed
Polymers 2023, 15(1), 220; https://doi.org/10.3390/polym15010220 - 31 Dec 2022
Cited by 8 | Viewed by 1876
Abstract
Metal–polymer hybrid structures are becoming desirable due to their wide range of applications in the automotive, aerospace, biomedical and construction industries. Properties such as a light weight, high specific strength, and design flexibility along with the low manufacturing costs of metal–polymer hybrid structures [...] Read more.
Metal–polymer hybrid structures are becoming desirable due to their wide range of applications in the automotive, aerospace, biomedical and construction industries. Properties such as a light weight, high specific strength, and design flexibility along with the low manufacturing costs of metal–polymer hybrid structures make them widely attractive in several applications. One of the main challenges that hinders the widespread utilization of metal–polymer hybrid structures is the challenging dissimilar joining of metals to polymers. Friction stir welding (FSW) shows a promising potential in overcoming most of the issues and limitations faced in the conventional joining methods of such structures. Several works in the literature have explored the FSW of different metal-to-polymer combinations. In some of the works, the joints are examined based on processing parameter optimization, microstructural characteristics, and mechanical performances. It is, therefore, important to summarize the findings of these works as a means of providing a reference to researchers to facilitate further research on the utilization of FSW in joining metals to polymers. Thus, this work aims to present a comprehensive technical review on the FSW technique for joining metals to polymers by reviewing the reported literature findings on the impact of materials, tools, process parameters, and defects on the strength and microstructure of the produced joints. In addition, this work reviews and presents the latest practices aiming to enhance the metal–polymer joint quality that have been reported in the literature. Full article
(This article belongs to the Section Polymer Processing and Engineering)
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