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Polymers
Volume 14
Issue 6
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Polymers, Volume 14, Issue 6 (March-2 2022) – 203 articles

Cover Story (view full-size image): In this study, polyacrylonitrile nanofiber membranes were cleaned with various chemical agents in order to reduce membrane fouling. Clearly, determining the optimal concentration of cleaning agents is advantageous because high concentrations of cleaning agents are unfavorable in terms of cost and nanofibrous membrane integrity. The results showed that low concentrations for individual citric acid (acidic) cleaning and sodium hydroxide (alkaline) cleaning improved flux recovery, whereas increasing the concentrations decreased flux recovery. For both chemical agents, the optimal concentration was 1 wt.%. This work is a priority for future investigations of the chemical cleaning of membranes prepared by nanofiber webs. View this paper.
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16 pages, 10037 KiB  
Article
A Density-Dependent Modified Doraivelu Model for the Cold Compaction of Poly (Ether Ketone Ketone) Powders
by Fan Xu, Huixiong Wang, Xuelian Wu, Zihao Ye and Hong Liu
Polymers 2022, 14(6), 1270; https://doi.org/10.3390/polym14061270 - 21 Mar 2022
Cited by 2 | Viewed by 1663
Abstract
The cold compaction of poly (ether ketone ketone) (PEKK) powder was studied by experiments and simulations based on the modified Doraivelu model. Although this model can successfully predict the compaction behavior of metal powders, discussion of the prediction of polymer powders is lacking. [...] Read more.
The cold compaction of poly (ether ketone ketone) (PEKK) powder was studied by experiments and simulations based on the modified Doraivelu model. Although this model can successfully predict the compaction behavior of metal powders, discussion of the prediction of polymer powders is lacking. Based on the mechanical theory of metal plasticity, the modified Doraivelu model was established by introducing the material parameters m and n. The modified model can predict the compaction density of PEKK powder during cold compaction. A sub-increment method for this constitutive model was then established and implemented into a finite-element model by using the user-defined material subroutine UMAT in ABAQUS/Standard. Consequently, the material parameters of the modified Doraivelu model were identified by an inverse method using the experimental data and simulation results. It was found that when m = 0, n = 4, and the initial relative density was 0.4485, the simulation results were the closest to the experimental ones. Full article
(This article belongs to the Section Polymer Physics and Theory)
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34 pages, 111731 KiB  
Review
Progress in Aromatic Polyimide Films for Electronic Applications: Preparation, Structure and Properties
by Ziyu Wu, Jianjun He, Haixia Yang and Shiyong Yang
Polymers 2022, 14(6), 1269; https://doi.org/10.3390/polym14061269 - 21 Mar 2022
Cited by 43 | Viewed by 7688
Abstract
Aromatic polyimides have excellent thermal stability, mechanical strength and toughness, high electric insulating properties, low dielectric constants and dissipation factors, and high radiation and wear resistance, among other properties, and can be processed into a variety of materials, including films, fibers, carbon fiber [...] Read more.
Aromatic polyimides have excellent thermal stability, mechanical strength and toughness, high electric insulating properties, low dielectric constants and dissipation factors, and high radiation and wear resistance, among other properties, and can be processed into a variety of materials, including films, fibers, carbon fiber composites, engineering plastics, foams, porous membranes, coatings, etc. Aromatic polyimide materials have found widespread use in a variety of high-tech domains, including electric insulating, microelectronics and optoelectronics, aerospace and aviation industries, and so on, due to their superior combination characteristics and variable processability. In recent years, there have been many publications on aromatic polyimide materials, including several books available to readers. In this review, the representative progress in aromatic polyimide films for electronic applications, especially in our laboratory, will be described. Full article
(This article belongs to the Special Issue Advanced Polyimides and Other High Performance Polymers)
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19 pages, 5475 KiB  
Article
UV-Cured Chitosan and Gelatin Hydrogels for the Removal of As(V) and Pb(II) from Water
by Camilla Noè, Michael Zanon, Amaya Arencibia, María-José López-Muñoz, Nieves Fernández de Paz, Paola Calza and Marco Sangermano
Polymers 2022, 14(6), 1268; https://doi.org/10.3390/polym14061268 - 21 Mar 2022
Cited by 17 | Viewed by 3482
Abstract
In this study, new photocurable biobased hydrogels deriving from chitosan and gelatin are designed and tested as sorbents for As(V) and Pb(II) removal from water. Those renewable materials were modified by a simple methacrylation reaction in order to make them light processable. The [...] Read more.
In this study, new photocurable biobased hydrogels deriving from chitosan and gelatin are designed and tested as sorbents for As(V) and Pb(II) removal from water. Those renewable materials were modified by a simple methacrylation reaction in order to make them light processable. The success of the reaction was evaluated by both 1H-NMR and FTIR spectroscopy. The reactivity of those formulations was subsequently investigated by a real-time photorheology test. The obtained hydrogels showed high swelling capability reaching up to 1200% in the case of methacrylated gelatin (GelMA). Subsequently, the Z-potential of the methacrylated chitosan (MCH) and GelMA was measured to correlate their electrostatic surface characteristics with their adsorption properties for As(V) and Pb(II). The pH of the solutions proved to have a huge influence on the As(V) and Pb(II) adsorption capacity of the obtained hydrogels. Furthermore, the effect of As(V) and Pb(II) initial concentration and contact time on the adsorption capability of MCH and GelMA were investigated and discussed. The MCH and GelMA hydrogels demonstrated to be promising sorbents for the removal of heavy metals from polluted waters. Full article
(This article belongs to the Collection Hydrogels)
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27 pages, 52615 KiB  
Review
Atomic Force Microscopy (AFM) on Biopolymers and Hydrogels for Biotechnological Applications—Possibilities and Limits
by Jnanada Joshi, Sarah Vanessa Homburg and Andrea Ehrmann
Polymers 2022, 14(6), 1267; https://doi.org/10.3390/polym14061267 - 21 Mar 2022
Cited by 30 | Viewed by 8747
Abstract
Atomic force microscopy (AFM) is one of the microscopic techniques with the highest lateral resolution. It can usually be applied in air or even in liquids, enabling the investigation of a broader range of samples than scanning electron microscopy (SEM), which is mostly [...] Read more.
Atomic force microscopy (AFM) is one of the microscopic techniques with the highest lateral resolution. It can usually be applied in air or even in liquids, enabling the investigation of a broader range of samples than scanning electron microscopy (SEM), which is mostly performed in vacuum. Since it works by following the sample surface based on the force between the scanning tip and the sample, interactions have to be taken into account, making the AFM of irregular samples complicated, but on the other hand it allows measurements of more physical parameters than pure topography. This is especially important for biopolymers and hydrogels used in tissue engineering and other biotechnological applications, where elastic properties, surface charges and other parameters influence mammalian cell adhesion and growth as well as many other effects. This review gives an overview of AFM modes relevant for the investigations of biopolymers and hydrogels and shows several examples of recent applications, focusing on the polysaccharides chitosan, alginate, carrageenan and different hydrogels, but depicting also a broader spectrum of materials on which different AFM measurements are reported in the literature. Full article
(This article belongs to the Special Issue Bio-Based Polymers for Biomedical Applications)
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18 pages, 6967 KiB  
Article
Adaptive Mechanism for Designing a Personalized Cranial Implant and Its 3D Printing Using PEEK
by Syed Hammad Mian, Khaja Moiduddin, Sherif Mohammed Elseufy and Hisham Alkhalefah
Polymers 2022, 14(6), 1266; https://doi.org/10.3390/polym14061266 - 21 Mar 2022
Cited by 15 | Viewed by 4320
Abstract
The rehabilitation of the skull’s bones is a difficult process that poses a challenge to the surgical team. Due to the range of design methods and the availability of materials, the main concerns are the implant design and material selection. Mirror-image reconstruction is [...] Read more.
The rehabilitation of the skull’s bones is a difficult process that poses a challenge to the surgical team. Due to the range of design methods and the availability of materials, the main concerns are the implant design and material selection. Mirror-image reconstruction is one of the widely used implant reconstruction techniques, but it is not a feasible option in asymmetrical regions. The ideal design approach and material should result in an implant outcome that is compact, easy to fit, resilient, and provides the perfect aesthetic and functional outcomes irrespective of the location. The design technique for the making of the personalized implant must be easy to use and independent of the defect’s position on the skull. As a result, this article proposes a hybrid system that incorporates computer tomography acquisition, an adaptive design (or modeling) scheme, computational analysis, and accuracy assessment. The newly developed hybrid approach aims to obtain ideal cranial implants that are unique to each patient and defect. Polyetheretherketone (PEEK) is chosen to fabricate the implant because it is a viable alternative to titanium implants for personalized implants, and because it is simpler to use, lighter, and sturdy enough to shield the brain. The aesthetic result or the fitting accuracy is adequate, with a maximum deviation of 0.59 mm in the outside direction. The results of the biomechanical analysis demonstrate that the maximum Von Mises stress (8.15 MPa), Von Mises strain (0.002), and deformation (0.18 mm) are all extremely low, and the factor of safety is reasonably high, highlighting the implant’s load resistance potential and safety under high loading. Moreover, the time it takes to develop an implant model for any cranial defect using the proposed modeling scheme is very fast, at around one hour. This study illustrates that the utilized 3D reconstruction method and PEEK material would minimize time-consuming alterations while also improving the implant’s fit, stability, and strength. Full article
(This article belongs to the Special Issue Polymer Materials in Additive Manufacturing: Modelling and Simulation)
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18 pages, 4434 KiB  
Article
In Vivo Evaluation of Gamma-Irradiated and Heparin-Immobilized Small-Diameter Polycaprolactone Vascular Grafts with VEGF in Aged Rats
by Se-Eun Kim, Sung-In Jeong, Kyung-Mi Shim, Kwangsik Jang, Jong-Seok Park, Youn-Mook Lim and Seong-Soo Kang
Polymers 2022, 14(6), 1265; https://doi.org/10.3390/polym14061265 - 21 Mar 2022
Cited by 3 | Viewed by 2384
Abstract
The effectiveness of small-diameter vascular grafts depends on their antithrombogenic properties and ability to undergo accelerated endothelialization. The extreme hydrophobic nature of poly(ε-caprolactone) (PCL) hinders vascular tissue integration, limiting its use in medical implants. To enhance the antithrombogenicity of PCL as a biomaterial, [...] Read more.
The effectiveness of small-diameter vascular grafts depends on their antithrombogenic properties and ability to undergo accelerated endothelialization. The extreme hydrophobic nature of poly(ε-caprolactone) (PCL) hinders vascular tissue integration, limiting its use in medical implants. To enhance the antithrombogenicity of PCL as a biomaterial, we grafted 2-aminoethyl methacrylate (AEMA) hydrochloride onto the PCL surface using gamma irradiation; developed a biodegradable heparin-immobilized PCL nanofibrous scaffold using gamma irradiation and N-(3-dimethylaminopropyl)-N′-ethyl carbodiimide hydrochloride/N-hydroxysuccinimide reaction chemistry; and incorporated vascular endothelial growth factor (VEGF) into the scaffold to promote vascular endothelial cell proliferation and prevent thrombosis on the vascular grafts. We assessed the physicochemical properties of PCL, heparin-AEMA-PCL (H-PCL), and VEGF-loaded heparin-AEMA-PCL (VH-PCL) vascular grafts using scanning electron microscopy, attenuated total reflection–Fourier transform infrared spectroscopy, toluidine blue O staining, and fibrinogen adsorption and surface wettability measurement. In addition, we implanted the vascular grafts into 24-month-old Sprague Dawley rats and evaluated them for 3 months. The H-PCL and VH-PCL vascular grafts improved the recovery of blood vessel function by promoting the proliferation of endothelial cells and preventing thrombosis in clinical and histological evaluation, indicating their potential to serve as functional vascular grafts in vascular tissue engineering. Full article
(This article belongs to the Special Issue Biomaterials in Medical Applications)
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23 pages, 377 KiB  
Article
Solvability of the Non-Linearly Viscous Polymer Solutions Motion Model
by Andrey Zvyagin
Polymers 2022, 14(6), 1264; https://doi.org/10.3390/polym14061264 - 21 Mar 2022
Cited by 4 | Viewed by 1265
Abstract
In this paper we consider the initial–boundary value problem describing the motion of weakly concentrated aqueous polymer solutions. The model involves the regularized Jaumann’s derivative in the rheological relation. Also this model is considered with non-linear viscosity. On the basis of the topological [...] Read more.
In this paper we consider the initial–boundary value problem describing the motion of weakly concentrated aqueous polymer solutions. The model involves the regularized Jaumann’s derivative in the rheological relation. Also this model is considered with non-linear viscosity. On the basis of the topological approximation approach to the study of hydrodynamics problems the existence of weak solutions is proved. Also we consider an optimal feedback control problem for this initial–boundary value problem. The existence of an optimal solution minimizing a given performance functional is proved. Full article
(This article belongs to the Special Issue Mechanical Performance and Modelling of Polymeric Materials)
20 pages, 3882 KiB  
Article
Expandable Graphite, Aluminum Diethylphospinate and Melamine Polyphosphate as Flame Retarding System in Glass Fiber-Reinforced PA6
by Florian Tomiak, Angelina Schoeffel, Klaus Rathberger and Dietmar Drummer
Polymers 2022, 14(6), 1263; https://doi.org/10.3390/polym14061263 - 21 Mar 2022
Cited by 12 | Viewed by 2367
Abstract
A flame retardant system based on expandable graphite (EG), aluminum diethylphosphinate (AlPI) and melamine polyphosphate (MPP) was investigated in glass fiber- (GF) reinforced polyamide 6 (PA6). Burning characteristics were evaluated via cone calorimeter, limiting oxygen index (LOI) and UL-94 tests. Thermogravimetric analysis (TGA) [...] Read more.
A flame retardant system based on expandable graphite (EG), aluminum diethylphosphinate (AlPI) and melamine polyphosphate (MPP) was investigated in glass fiber- (GF) reinforced polyamide 6 (PA6). Burning characteristics were evaluated via cone calorimeter, limiting oxygen index (LOI) and UL-94 tests. Thermogravimetric analysis (TGA) and coupled Fourier transform infrared spectroscopy (FTIR) was used to investigate the decomposition process as well as flame retardant modes of actions. Specifically, in the cone calorimeter tests, formulations containing EG showed excellent flame retardant properties for non-reinforced and reinforced PA6. The best performance was achieved for 25 wt.% glass fiber-reinforced PA6 containing solely 20 wt.% EG, corresponding to a measured pHRR of 134 kW/m2 and a total smoke production of 1.2 m2. Higher glass fiber contents of 45 wt.% (30 vol.%) revealed a lower char volume, which was attributed to both the limited space available for expansion and the sheer-induced reduction in particle size during processing. All of the reinforced PA6 formulations only achieved V2 classifications, but this was at low filling degrees (10 wt.%) for both net EG or EG/AlPi/MPP combinations. For GF-reinforced PA6 containing EG/AlPi/MPP mixtures, a synergistic effect was found to improve the oxygen index up to 30.6%. Full article
(This article belongs to the Special Issue Reinforced Polymer Composites III)
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34 pages, 12225 KiB  
Review
The Role of Structure in Polymer Rheology: Review
by Valery G. Kulichikhin and Alexander Ya. Malkin
Polymers 2022, 14(6), 1262; https://doi.org/10.3390/polym14061262 - 21 Mar 2022
Cited by 19 | Viewed by 5135
Abstract
The review is devoted to the analysis of the current state of understanding relationships among the deformation-induced structure transformations, observed rheological properties, and the occurrence of non-linear effects for polymer liquids (melts, solutions, and composites). Three levels of non-linearity are the base for [...] Read more.
The review is devoted to the analysis of the current state of understanding relationships among the deformation-induced structure transformations, observed rheological properties, and the occurrence of non-linear effects for polymer liquids (melts, solutions, and composites). Three levels of non-linearity are the base for consideration. The first one concerns changes in the relaxation spectra of viscoelastic liquids, which are responsible for weak non-linear phenomena. The second one refers to the strong non-linearity corresponding to such changes in the structure of a medium that leads to the emergence of a new relaxation state of a matter. Finally, the third one describes the deformation-induced changes in the phase state and/or the occurring of bifurcations and instability in flow and reflects the thermodynamic non-linear behavior. From a structure point of view, a common cause of the non-linear effects is the orientation of macromolecules and changes in intermolecular interaction, while a dominant factor in describing fluid dynamics of polymer liquids is their elasticity. The modern understanding of thixotropic effects, yielding viscoplastic materials, deformation-induced phase transition, and the experimental observations, demonstrating direct correlations between the structure and rheology of polymer liquids, are the main objects for discussion. All these topics are reviewed and discussed mainly on the basis of the latest five-year publications. Full article
(This article belongs to the Special Issue Structural Rheology of Polymer Melts, Solutions and Compositions on Their Base)
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12 pages, 1714 KiB  
Article
Self-Photopolymerizable Hydrogel–Ceramic Composites with Scavenger Properties
by Maria Canillas, Gabriel Goetten de Lima, Marcelo J. C. de Sá, Michael J. D. Nugent, Miguel A. Rodríguez and Declan M. Devine
Polymers 2022, 14(6), 1261; https://doi.org/10.3390/polym14061261 - 21 Mar 2022
Viewed by 1808
Abstract
The photocatalytic behaviours of semiconductive ceramic nanoparticles such as TiO2, ZnO, Fe2O3, and Fe3O4, have been extensively studied in photocatalysis and photopolymerization, due to their ability to produce radical species under ultraviolet–visible light, [...] Read more.
The photocatalytic behaviours of semiconductive ceramic nanoparticles such as TiO2, ZnO, Fe2O3, and Fe3O4, have been extensively studied in photocatalysis and photopolymerization, due to their ability to produce radical species under ultraviolet–visible light, and even in dark conditions. In addition, in the form of microparticles, TiO2 and its Magnéli phases are capable of neutralizing radical species, and a heterogeneous catalytic process has been suggested to explain this property, as it is well known as scavenging activity. Thus, in this study, we demonstrate that these ceramic powders, in the form of microparticles, could be used as photoinitiators in UV polymerization in order to synthesize a hydrogel matrix. Them, embedded ceramic powders could be able to neutralize radical species of physiological media once implanted. The hydrogel matrix would regulate the exchange of free radicals in any media, while the ceramic particles would neutralize the reactive species. Therefore, in this work, the scavenger activities of TiO2, ZnO, Fe2O3, and Fe3O4 microparticles, along with their photoinitiation yield, were evaluated. After photopolymerization, the gel fraction and swelling behaviour were evaluated for each hydrogel produced with different ceramic initiators. Gel fractions were higher than 60%, exhibiting variation in their scavenging activity. Therefore, we demonstrate that ceramic photoinitiators of TiO2, ZnO, Fe2O3, and Fe3O4 can be used to fabricate implantable devices with scavenger properties in order to neutralize radical species involved in inflammatory processes and degenerative diseases. Full article
(This article belongs to the Special Issue Recent Advances in UV Polymerization—New Polymeric Materials)
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19 pages, 4159 KiB  
Article
Jute Fiber-Reinforced Polymer Tube-Confined Sisal Fiber-Reinforced Recycled Aggregate Concrete Waste
by Chang Gao, Qiuni Fu, Liang Huang, Libo Yan and Guangming Gu
Polymers 2022, 14(6), 1260; https://doi.org/10.3390/polym14061260 - 21 Mar 2022
Cited by 13 | Viewed by 2608
Abstract
In this study, the compressive performance of sisal fiber-reinforced recycled aggregate concrete (SFRAC) composite, confined with jute fiber-reinforced polymer (JFRP) tube (the structure was termed as JFRP–SFRAC) was assessed. A total of 36 cylindrical specimens were tested under uniaxial compression. Three major experimental [...] Read more.
In this study, the compressive performance of sisal fiber-reinforced recycled aggregate concrete (SFRAC) composite, confined with jute fiber-reinforced polymer (JFRP) tube (the structure was termed as JFRP–SFRAC) was assessed. A total of 36 cylindrical specimens were tested under uniaxial compression. Three major experimental variables were investigated: (1) the compressive strength of concrete core (i.e., 25.0 MPa and 32.5 MPa), (2) jute fiber orientation angle with respect to the hoop direction of a JFRP tube (i.e., β = 0°, 30° and 45°), and (3) the reinforcement of sisal fiber (i.e., 0% and 0.3% by mass of cement). This study revealed that the prefabricated JFRP tube resulted in a significant enhancement of the compressive strength and deformation ability of RAC and SFRAC. The enhancements in strength and ultimate strain of the composite columns were more pronounced for concrete with a higher strength. The strength and ultimate strain of JFRP-confined specimens decreased with an increase in fiber orientation angle β from 0° to 45°. The sisal fiber reinforcement effectively improved the integrity of the RAC and reduced the propagation of cracks in RAC. The stress–strain behaviors of JFRP–RAC and JFRP–SFRAC were predicted by the Lam and Teng’s model with the revised ultimate condition equations. Full article
(This article belongs to the Special Issue Polymers (or Adhesives) and Polymer Composites for Construction Application)
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33 pages, 10560 KiB  
Review
Polyacrylic Acid Nanoplatforms: Antimicrobial, Tissue Engineering, and Cancer Theranostic Applications
by Hassan Arkaban, Mahmood Barani, Majid Reza Akbarizadeh, Narendra Pal Singh Chauhan, Sapana Jadoun, Maryam Dehghani Soltani and Payam Zarrintaj
Polymers 2022, 14(6), 1259; https://doi.org/10.3390/polym14061259 - 21 Mar 2022
Cited by 90 | Viewed by 11231
Abstract
Polyacrylic acid (PAA) is a non-toxic, biocompatible, and biodegradable polymer that gained lots of interest in recent years. PAA nano-derivatives can be obtained by chemical modification of carboxyl groups with superior chemical properties in comparison to unmodified PAA. For example, nano-particles produced from [...] Read more.
Polyacrylic acid (PAA) is a non-toxic, biocompatible, and biodegradable polymer that gained lots of interest in recent years. PAA nano-derivatives can be obtained by chemical modification of carboxyl groups with superior chemical properties in comparison to unmodified PAA. For example, nano-particles produced from PAA derivatives can be used to deliver drugs due to their stability and biocompatibility. PAA and its nanoconjugates could also be regarded as stimuli-responsive platforms that make them ideal for drug delivery and antimicrobial applications. These properties make PAA a good candidate for conventional and novel drug carrier systems. Here, we started with synthesis approaches, structure characteristics, and other architectures of PAA nanoplatforms. Then, different conjugations of PAA/nanostructures and their potential in various fields of nanomedicine such as antimicrobial, anticancer, imaging, biosensor, and tissue engineering were discussed. Finally, biocompatibility and challenges of PAA nanoplatforms were highlighted. This review will provide fundamental knowledge and current information connected to the PAA nanoplatforms and their applications in biological fields for a broad audience of researchers, engineers, and newcomers. In this light, PAA nanoplatforms could have great potential for the research and development of new nano vaccines and nano drugs in the future. Full article
(This article belongs to the Topic Synthesis, Characterization and Performance of Materials for a Sustainable Future)
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19 pages, 1148 KiB  
Review
Milk Whey Hydrolysates as High Value-Added Natural Polymers: Functional Properties and Applications
by Arely León-López, Xóchitl Alejandra Pérez-Marroquín, Ana Guadalupe Estrada-Fernández, Gieraldin Campos-Lozada, Alejandro Morales-Peñaloza, Rafael G. Campos-Montiel and Gabriel Aguirre-Álvarez
Polymers 2022, 14(6), 1258; https://doi.org/10.3390/polym14061258 - 21 Mar 2022
Cited by 13 | Viewed by 3986
Abstract
There are two types of milk whey obtained from cheese manufacture: sweet and acid. It retains around 55% of the nutrients of the milk. Milk whey is considered as a waste, creating a critical pollution problem, because 9 L of whey are produced [...] Read more.
There are two types of milk whey obtained from cheese manufacture: sweet and acid. It retains around 55% of the nutrients of the milk. Milk whey is considered as a waste, creating a critical pollution problem, because 9 L of whey are produced from every 10 L of milk. Some treatments such as hydrolysis by chemical, fermentation process, enzymatic action, and green technologies (ultrasound and thermal treatment) are successful in obtaining peptides from protein whey. Milk whey peptides possess excellent functional properties such as antihypertensive, antiviral, anticancer, immunity, and antioxidant, with benefits in the cardiovascular, digestive, endocrine, immune, and nervous system. This review presents an update of the applications of milk whey hydrolysates as a high value-added peptide based on their functional properties. Full article
(This article belongs to the Special Issue Advances in Natural Polymers: Extraction Methods and Applications)
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18 pages, 2674 KiB  
Review
Infrared Linear Dichroism for the Analysis of Molecular Orientation in Polymers and in Polymer Composites
by Liliane Bokobza
Polymers 2022, 14(6), 1257; https://doi.org/10.3390/polym14061257 - 21 Mar 2022
Cited by 7 | Viewed by 3146
Abstract
The mechanical properties of polymeric materials are strongly affected by molecular orientation occurring under processing conditions. Infrared dichroism is particularly well suited for characterizing polymer chain orientation at a molecular level. The usefulness of this technique has been demonstrated through various applications in [...] Read more.
The mechanical properties of polymeric materials are strongly affected by molecular orientation occurring under processing conditions. Infrared dichroism is particularly well suited for characterizing polymer chain orientation at a molecular level. The usefulness of this technique has been demonstrated through various applications in homopolymers, semi-crystalline polymers, copolymers, polymer blends, as well as in polymer composites. Determination of molecular orientation can be carried out in the mid- and near-infrared ranges and very small dichroic effects can be detected with the use of a photoelastic modulator. Chain orientation in polymer composites is seen to increase with the filler content in the case of a strong interface between the two phases, making possible a quantification of the degree of bonding between the host polymeric matrix and the incorporated inclusions. Full article
(This article belongs to the Collection Multi-Scale Polymer Processing)
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10 pages, 2133 KiB  
Article
New Advanced Liquid Crystalline Materials Bearing Bis-Azomethine as Central Spacer
by Fowzia S. Alamro, Hoda A. Ahmed, Noha S. Bedowr, Muna S. Khushaim and Mohamed A. El-atawy
Polymers 2022, 14(6), 1256; https://doi.org/10.3390/polym14061256 - 21 Mar 2022
Cited by 12 | Viewed by 1941
Abstract
In this study, a homologous series of novel liquid crystalline compounds bearing the bis-azomethine central linkage (–CH=N-N=CH–), namely ((1E,1′E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(4,1-phenylene) dialkanoate (In), was synthesized, and the mesophase and thermal properties were investigated theoretically and experimentally. The molecular structures of the prepared [...] Read more.
In this study, a homologous series of novel liquid crystalline compounds bearing the bis-azomethine central linkage (–CH=N-N=CH–), namely ((1E,1′E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(4,1-phenylene) dialkanoate (In), was synthesized, and the mesophase and thermal properties were investigated theoretically and experimentally. The molecular structures of the prepared compounds were determined using elemental analysis, NMR, and FT-IR spectroscopy. The mesophase transitions were detected by differential scanning calorimetry (DSC), and the mesophases were identified using polarized optical microscopy (POM). The results indicated that the derivative with the shortest length (I5) was purely nematogenic, while the other homologues (I9 and I15) possessed SmC mesophases. The optimal geometrical structures of the investigated group were derived theoretically. The estimated results demonstrated that all homologues were mesomorphic, and their type depended on the length of the terminal chains. Computations based on density functional theory (DFT) were used to explain the experimental data. The calculated dipole moment, polarizability, thermal energy, and molecular electrostatic potential all showed that it was possible to predict the mesophase type and stability, which varied according to the size of the molecule. Full article
(This article belongs to the Section Polymer Applications)
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23 pages, 6284 KiB  
Article
Determination of Mechanical Properties of Epoxy Composite Materials Reinforced with Silicate Nanofillers Using Digital Image Correlation (DIC)
by Aleksandra Jelić, Milica Sekulić, Milan Travica, Jelena Gržetić, Vukašin Ugrinović, Aleksandar D. Marinković, Aleksandra Božić, Marina Stamenović and Slaviša Putić
Polymers 2022, 14(6), 1255; https://doi.org/10.3390/polym14061255 - 21 Mar 2022
Cited by 8 | Viewed by 2882
Abstract
In this study, silicate nanofillers; dicalcium silicate, magnesium silicate, tricalcium silicate, and wollastonite; were synthesized using four different methods and incorporated into the epoxy resin to improve its mechanical properties. Characterization of the newly synthesized nanofillers was performed using Fourier-transformation infrared (FTIR) spectroscopy, [...] Read more.
In this study, silicate nanofillers; dicalcium silicate, magnesium silicate, tricalcium silicate, and wollastonite; were synthesized using four different methods and incorporated into the epoxy resin to improve its mechanical properties. Characterization of the newly synthesized nanofillers was performed using Fourier-transformation infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The purpose of this study was to analyze newly developed composite materials reinforced with silicate nanoparticles utilizing tensile testing and a full-field non-contact 3D Digital Image Correlation (DIC) method. Analysis of deformation and displacement fields gives precise material behavior during testing. Testing results allowed a more reliable assessment of the structural integrity of epoxy composite materials reinforced using different silicate nanofillers. It was concluded that the addition of 3% of dicalcium silicate, magnesium silicate, tricalcium silicate, and wollastonite lead to the increasement of tensile strength up to 31.5%, 29.0%, 27.5%, and 23.5% in comparison with neat epoxy, respectively. In order to offer more trustworthy information about the viscoelastic behavior of neat epoxy and composites, a dynamic mechanical analysis (DMA) was also performed and rheological measurements of uncured epoxy matrix and epoxy suspensions were obtained. Full article
(This article belongs to the Special Issue Epoxy Resins and Composites)
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14 pages, 3485 KiB  
Article
Polylactide-Grafted Metal-Alginate Aerogels
by Grigorios Raptopoulos, Ioannis Choinopoulos, Filippos Kontoes-Georgoudakis and Patrina Paraskevopoulou
Polymers 2022, 14(6), 1254; https://doi.org/10.3390/polym14061254 - 21 Mar 2022
Cited by 3 | Viewed by 2132
Abstract
Τhis work describes the synthesis of PLA-grafted M-alginate (g-M-alginate; M: Ca2+, Co2+, Ni2+, Cu2+) aerogels. DL-lactide (LA) was attached on the surface of preformed M-alginate beads and was polymerized, using stannous octoate as catalyst [...] Read more.
Τhis work describes the synthesis of PLA-grafted M-alginate (g-M-alginate; M: Ca2+, Co2+, Ni2+, Cu2+) aerogels. DL-lactide (LA) was attached on the surface of preformed M-alginate beads and was polymerized, using stannous octoate as catalyst and the –OH groups of the alginate backbone as initiators/points of attachment. The material properties of g-M-alginate aerogels were not affected much by grafting, because the linear PLA chains grew on the M-alginate framework like a brush and did not bridge their points of attachment as in polyurea-crosslinked M-alginate aerogels. Thus, all g-M-alginate aerogels retained the fibrous morphology of their parent M-alginate aerogels, and they were lightweight (bulk densities up to 0.24 g cm−3), macroporous/mesoporous materials with high porosities (up to 96% v/v). The BET surface areas were in the range of 154–542 m2 g−1, depending on the metal, the nature of the alginate framework and the PLA content. The latter was found at about 15% w/w for Ca- and Ni-based materials and at about 29% w/w for Co- and Cu-based materials. Overall, we have demonstrated a new methodology for the functionalization of alginate aerogels that opens the way to the synthesis of polylactide-crosslinked alginate aerogels with the use of multifunctional monomers. Full article
(This article belongs to the Special Issue Synthesis and Characterisation of Aerogels: Fundamentals and Applications)
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11 pages, 1814 KiB  
Article
Modification of Hot-Melt Adhesives Based on Metallocene Poly(ethylene-propylene) Copolymer for High Adhesion to Polar Surfaces
by Igor Novák, Jozef Preto, Vladimír Vanko, Jozef Rychlý, Juraj Pavlinec and Ivan Chodák
Polymers 2022, 14(6), 1253; https://doi.org/10.3390/polym14061253 - 20 Mar 2022
Cited by 1 | Viewed by 2484
Abstract
A procedure is described of grafting the acrylic acid onto an oxygen/ozone-activated metallocene poly(ethylene-co-propylene). Consequently, the grafted copolymer is applied as a component in a metallocene polyolefin-based hot-melt adhesive composition with increased adhesion. The surface properties and adhesion strength of the prepared hot-melt [...] Read more.
A procedure is described of grafting the acrylic acid onto an oxygen/ozone-activated metallocene poly(ethylene-co-propylene). Consequently, the grafted copolymer is applied as a component in a metallocene polyolefin-based hot-melt adhesive composition with increased adhesion. The surface properties and adhesion strength of the prepared hot-melt adhesive (HMA) were determined and used to account for the effect of grafting. The application of grafted polyolefin as one of the components of the HMA mixture provides significant increase in adhesive strength, and it also results in increased compatibility and negligible effects on the technological parameters of the final composition. The obtained results may have significant impact for the practical application of prepared HMA for book bonding. Full article
(This article belongs to the Special Issue Multiphase Systems with Polymeric Matrices: Polymer Blends and Composites)
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13 pages, 2918 KiB  
Article
Characteristic and Synthesis of High-Temperature Resistant Liquid Crystal Epoxy Resin Containing Boron Nitride Composite
by Li-Chuan Wu, Yi-Wen Huang, Yao-Ming Yeh and Chih-Hung Lin
Polymers 2022, 14(6), 1252; https://doi.org/10.3390/polym14061252 - 20 Mar 2022
Cited by 6 | Viewed by 2348
Abstract
Five liquid crystal epoxy resins and composites containing flat boron nitride (f-BN) and spherical boron nitride (s-BN) were successfully synthesized. The chemical structures, crystal diffraction, and thermal conductivity of the liquid crystal (LC) epoxy composites were measured using Nuclear Magnetic Resonance (NMR), Differential [...] Read more.
Five liquid crystal epoxy resins and composites containing flat boron nitride (f-BN) and spherical boron nitride (s-BN) were successfully synthesized. The chemical structures, crystal diffraction, and thermal conductivity of the liquid crystal (LC) epoxy composites were measured using Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimetry (DSC), X-ray, and Discovery Xenon Flash. In this study, the molecular arrangement of five LC epoxy resins and the thermal conductivity of their composites were carefully discussed. Several different amounts of flat boron nitride and spherical boron nitride were added to the five LC epoxy resins. The influence of nano-scale ceramic materials, f-BN, and s-BN, on the thermal conductivity of the LC epoxy resins, was studied. It is worth noting that the thermal conductivity of the spherical boron nitride composite demonstrated a better result than that of the flat boron nitride composite. In simpler terms, the thermal conductivity of the composites is closely related to the molecular arrangement of the LC resin and the amount of BN added. The results demonstrate that the SBPDAE/s-BN (60%) composite shows the highest thermal conductivity of 9.36 W/mK in the vertical direction. These data prove that the LC alignment of the matrix will greatly enhance the thermal conductivity of the composites. Full article
(This article belongs to the Special Issue Advances in Polymer Composites)
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17 pages, 7572 KiB  
Article
Fabrication and Property Characterization of Long-Glass-Fiber-Reinforced Polypropylene Composites Processed Using a Three-Barrel Injection Molding Machine
by Guan-Yan Liou, Chi-Wei Su, Po-Wei Huang, Sheng-Jye Hwang, Chao-Tsai Huang and Hsin-Shu Peng
Polymers 2022, 14(6), 1251; https://doi.org/10.3390/polym14061251 - 20 Mar 2022
Cited by 4 | Viewed by 2558
Abstract
Processing equipment and parameters will highly influence the properties of long-fiber-reinforced injection-molded thermoplastic composites, leading to different fiber lengths and orientations. Thus, maintaining fiber length during the injection molding process is always a big challenge for engineers. This study uses long-glass-fiber-reinforced polypropylene with [...] Read more.
Processing equipment and parameters will highly influence the properties of long-fiber-reinforced injection-molded thermoplastic composites, leading to different fiber lengths and orientations. Thus, maintaining fiber length during the injection molding process is always a big challenge for engineers. This study uses long-glass-fiber-reinforced polypropylene with 25 mm fiber length and a special-built novel injection molding machine with a three-barrel injection unit, including a plasticizing screw, an injection plunger, and a packing plunger, to fabricate injection molding parts while retaining long fiber length. This study also discusses the influence of process parameters, such as back pressure, screw speed, melt temperature, and different flow paths, on the properties of long-glass-fiber-reinforced composites. The experiment results show that a higher screw speed and back pressure will reduce the fiber length in the injection-molded parts. However, using appropriate parameter settings can maintain the fiber length to more than 10 mm. It was found that by increasing the back pressure, the cross direction of the fiber orientation can be increased by up to 15% and the air trap volume fraction can be decreased by up to 86%. Setting appropriate back pressure under a low screw speed will increase the tensile strength. Finally, it was found that the single-edge-gate path results in a higher tensile strength than that of the single-sprue-gate path due to the retainment of longer fiber length in the injection-molded part. Full article
(This article belongs to the Special Issue Advanced Thermoplastic Polymers and Composites)
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13 pages, 2718 KiB  
Article
Tung Oil Thermal Treatment Improves the Visual Effects of Moso Bamboo Materials
by Tong Tang, Benhua Fei, Wei Song, Na Su and Fengbo Sun
Polymers 2022, 14(6), 1250; https://doi.org/10.3390/polym14061250 - 20 Mar 2022
Cited by 4 | Viewed by 1968
Abstract
Color is one of the most important characteristics of a material’s appearance, which affects the additional value of bamboo and psychological feelings of users. Previous studies have shown that the dimensional stability, mildew resistance and durability of bamboo were improved after tung oil [...] Read more.
Color is one of the most important characteristics of a material’s appearance, which affects the additional value of bamboo and psychological feelings of users. Previous studies have shown that the dimensional stability, mildew resistance and durability of bamboo were improved after tung oil thermal treatment. In this study, the effects of tung oil thermal treatment on bamboo color at different temperatures and durations of time were investigated. The results show that the lightness (L*) of bamboo decreased as the tung oil temperature or duration of time increased. The red–green coordinates (a*) and color saturation (C*) of bamboo were gradually increased as the tung oil temperature rose from 23 °C to 160 °C, while the a* and C* were gradually decreased when the temperature continued to rise from 160 °C to 200 °C. There was no significant difference in the yellow–blue coordinates (b*) of bamboo when the duration was prolonged from 0.5 h to 3 h with tung oil thermal treatment at 140 °C. Eye movement data show that the popularity of bamboo furniture was significantly improved at 23–100 °C and slightly improved at 160–180 °C with tung oil treatment. Therefore, tung oil thermal treatment plays a positive role in improving visual effects and additional value of bamboo. Full article
(This article belongs to the Special Issue Eco Polymeric Materials and Natural Polymer)
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18 pages, 6602 KiB  
Article
Light-Activated Elongation/Shortening and Twisting of a Nematic Elastomer Balloon
by Lin Zhou, Yujie Wang and Kai Li
Polymers 2022, 14(6), 1249; https://doi.org/10.3390/polym14061249 - 20 Mar 2022
Cited by 1 | Viewed by 1801
Abstract
Nematic elastomer balloons with inflation-induced axial contraction and shear/torsion effect can be used as actuators for soft robots, artificial muscles, and biomedical instruments. The nematic elastomer can also generate drastic shape changes under illumination, and thus light can be utilized to activate the [...] Read more.
Nematic elastomer balloons with inflation-induced axial contraction and shear/torsion effect can be used as actuators for soft robots, artificial muscles, and biomedical instruments. The nematic elastomer can also generate drastic shape changes under illumination, and thus light can be utilized to activate the deformation of nematic elastomer balloons with huge advantages of being accurate, fast, untethered, and environmentally sustainable without chemical byproducts. To explore light-activated deformation behaviors of the balloon, a phenomenological relationship between light intensity and material parameters describing polymer backbone anisotropy is proposed from experiments, and a theoretical model of an optically-responsive nematic elastomer balloon is established based on the nematic elastomer theory. Various light-activated elongation/shortening and twisting behaviors in the cases of free-standing and axial-loading are presented and their mechanisms are elucidated. The light intensity and initial mesogen angle have great influences on the light-activated deformations including the radius, length, shearing angle and mesogen angle. Light can be easily controlled to trigger rich deformation processes, including elongation/shortening and torsion. The results of this paper are expected to promote the understanding of the light-activated deformation behaviors of the nematic elastomer balloon, and the applications in light-activated actuators and machines. Full article
(This article belongs to the Special Issue Behaviour Analysis of Polymeric Composite Material Structures)
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14 pages, 7827 KiB  
Article
Strength, Elastic Properties and Fiber–Matrix Interaction Mechanism in Geopolymer Composites
by Susana P. Arredondo, Ramón Corral, A. Valenciano, Carlos A. Rosas, Jose M. Gómez, Teresita J. Medina, Magnolia Soto and Jesús M. Bernal
Polymers 2022, 14(6), 1248; https://doi.org/10.3390/polym14061248 - 20 Mar 2022
Cited by 2 | Viewed by 1978
Abstract
The current geopolymers have limited mechanical strength against the effect of tension, which makes them susceptible to brittle failure. However, owing to their potential as a sustainable construction material, there is growing interest in improving the poor mechanical properties of geopolymers. This study [...] Read more.
The current geopolymers have limited mechanical strength against the effect of tension, which makes them susceptible to brittle failure. However, owing to their potential as a sustainable construction material, there is growing interest in improving the poor mechanical properties of geopolymers. This study experimentally investigated crucial properties of polypropylene-fiber-reinforced fly ash-based geopolymer composites. The effects of polypropylene fibers (PPF) addition (0.5%, 1.0% and 1.5% by volume) on the mechanical properties of the geopolymer composites were investigated with respect to compressive and flexural strength, deformation behavior of Young’s and shear moduli, and resilience capacity. In addition, scanning electron microscopy was performed to establish the morphology of the geopolymeric matrix and the fiber–matrix interfacial interaction. The addition of PPF significantly increased the flexural strength: compared with the control, at 7 days it was 27% greater for the 0.5% PPF composite and 65% greater for the 1.0% PPF composite. By 14 days it was 31% and 61% greater, respectively. By contrast, the 1.5% PPF composite had lower strength parameters compared with the control because the fiber dispersion increased the porosity. Similar trends were seen for resilience. The SEM observations showed the dispersion of the fibers and helped elucidate the fiber–matrix interaction mechanism. Full article
(This article belongs to the Special Issue Geopolymer Composite)
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12 pages, 2531 KiB  
Article
Modification of Polydiallyldimethylammonium Chloride with Sodium Polystyrenesulfonate Dramatically Changes the Resistance of Polymer-Based Coatings towards Wash-Off from Both Hydrophilic and Hydrophobic Surfaces
by Vladislava A. Pigareva, Ivan N. Senchikhin, Anastasia V. Bolshakova and Andrey V. Sybachin
Polymers 2022, 14(6), 1247; https://doi.org/10.3390/polym14061247 - 19 Mar 2022
Cited by 11 | Viewed by 2156
Abstract
Polymer coatings based on polycations represent a perspective class of protective antimicrobial coatings. Polydiallyldimethylammonium chloride (PDADMAC) and its water-soluble complexes with sodium polystyrenesulfonate (PSS) were studied by means of dynamic light-scattering, laser microelectrophoresis and turbidimetry. It was shown that addition of six mol.% [...] Read more.
Polymer coatings based on polycations represent a perspective class of protective antimicrobial coatings. Polydiallyldimethylammonium chloride (PDADMAC) and its water-soluble complexes with sodium polystyrenesulfonate (PSS) were studied by means of dynamic light-scattering, laser microelectrophoresis and turbidimetry. It was shown that addition of six mol.% of polyanion to polycation results in formation of interpolyelectrolyte complex (IPEC) that was stable towards phase separation in water-salt media with a concentration of salts (NaCl, CaCl2, Na2SO4, MgSO4) up to 0.5 M. Most of the polyelectrolyte coatings are made by layer-by-layer deposition. The utilization of water-soluble IPEC for the direct deposition on the surface was studied. The coatings from the PDADMAC and the PSS/PDADMAC complex were formed on the surfaces of hydrophilic glass and hydrophobic polyvinylchloride. It was found that formation IPEC allows one to increase the stability of the coating towards wash-off with water in comparison to individual PDADMAC coating on both types of substrates. The visualization of the coatings was performed by atomic force microscopy and scanning electron microscopy. Full article
(This article belongs to the Special Issue Properties and Characterization of Polymers in Nanomaterials)
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19 pages, 992 KiB  
Article
Assessment of the Influence of Size and Concentration on the Ecotoxicity of Microplastics to Microalgae Scenedesmus sp., Bacterium Pseudomonas putida and Yeast Saccharomyces cerevisiae
by Martina Miloloža, Kristina Bule, Viktorija Prevarić, Matija Cvetnić, Šime Ukić, Tomislav Bolanča and Dajana Kučić Grgić
Polymers 2022, 14(6), 1246; https://doi.org/10.3390/polym14061246 - 19 Mar 2022
Cited by 12 | Viewed by 3227
Abstract
The harmful effects of microplastics are not yet fully revealed. This study tested harmful effects of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET) microplastics were tested. Growth inhibition tests were conducted using three microorganisms with different characteristics: [...] Read more.
The harmful effects of microplastics are not yet fully revealed. This study tested harmful effects of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET) microplastics were tested. Growth inhibition tests were conducted using three microorganisms with different characteristics: Scenedesmus sp., Pseudomonas putida, and Saccharomyces cerevisiae. The growth inhibition test with Scenedesmus sp. is relatively widely used, while the tests with Pseudomonas putida and Saccharomyces cerevisiae were, to our knowledge, applied to microplastics for the first time. The influence of concentration and size of microplastic particles, in the range of 50–1000 mg/L and 200–600 µm, was tested. Determined inhibitions on all three microorganisms confirmed the hazardous potential of the microplastics used. Modeling of the inhibition surface showed the increase in harmfulness with increasing concentration of the microplastics. Particle size showed no effect for Scenedesmus with PE, PP and PET, Pseudomonas putida with PS, and Saccharomyces cerevisiae with PP. In the remaining cases, higher inhibitions followed a decrease in particle size. The exception was Scenedesmus sp. with PS, where the lowest inhibitions were obtained at 400 µm. Finally, among the applied tests, the test with Saccharomyces cerevisiae proved to be the most sensitive to microplastics. Full article
(This article belongs to the Special Issue Microplastics Degradation and Characterization)
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22 pages, 1156 KiB  
Article
Modulating Role of Co-Solutes in Complexation between Bovine Serum Albumin and Sodium Polystyrene Sulfonate
by Matjaž Simončič and Miha Lukšič
Polymers 2022, 14(6), 1245; https://doi.org/10.3390/polym14061245 - 19 Mar 2022
Cited by 3 | Viewed by 1801
Abstract
The action of three types of co-solutes: (i) salts (NaCl, NaBr, NaI), (ii) polymer (polyethylene glycol; PEG-400, PEG-3000, PEG-20000), and (iii) sugars (sucrose, sucralose) on the complexation between bovine serum albumin (BSA) and sodium polystyrene sulfonate (NaPSS) was studied. Three critical pH [...] Read more.
The action of three types of co-solutes: (i) salts (NaCl, NaBr, NaI), (ii) polymer (polyethylene glycol; PEG-400, PEG-3000, PEG-20000), and (iii) sugars (sucrose, sucralose) on the complexation between bovine serum albumin (BSA) and sodium polystyrene sulfonate (NaPSS) was studied. Three critical pH parameters were extracted from the pH dependence of the solution’s turbidity: pHc corresponding to the formation of the soluble complexes, pHΦ corresponding to the formation of the insoluble complexes, and pHopt corresponding to the charge neutralization of the complexes. In the presence of salts, the formation of soluble and insoluble complexes as well as the charge neutralization of complexes was hindered, which is a consequence of the electrostatic screening of attractive interactions between BSA and NaPSS. Distinct anion-specific trends were observed in which the stabilizing effect of the salt increased in the order: NaCl < NaBr < NaI. The presence of PEG, regardless of its molecular weight, showed no measurable effect on the formation of soluble complexes. PEG-400 and PEG-3000 showed no effect on the formation of insoluble complexes, but PEG-20000 in high concentrations promoted their formation due to the molecular crowding effect. The presence of sugar molecules had little effect on BSA-NaPSS complexation. Sucralose showed a minor stabilizing effect with respect to the onset of complex formation, which was due to its propensity to the protein surface. This was confirmed by the fluorescence quenching assay (Stern-Volmer relationship) and all-atom MD simulations. This study highlights that when evaluating the modulatory effect of co-solutes on protein-polyelectrolyte interactions, (co-solute)-protein interactions and their subsequent impact on protein aggregation must also be considered. Full article
(This article belongs to the Section Polymer Applications)
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13 pages, 3155 KiB  
Article
Fast Pyrolysis Bio-Oil-Based Epoxy as an Adhesive in Oriented Strand Board Production
by Osei Asibe Asafu-Adjaye, Jason Street, Archana Bansode, Maria L. Auad, Maria Soledad Peresin, Sushil Adhikari, Terry Liles and Brian K. Via
Polymers 2022, 14(6), 1244; https://doi.org/10.3390/polym14061244 - 19 Mar 2022
Cited by 5 | Viewed by 2213
Abstract
The objectives of this study were to utilize bio-oil-based epoxy resin in oriented strand board (OSB) production and investigate the effect of bio-oil substitution in epoxy resin as an adhesive for OSB production. Bio-oil was produced by the fast pyrolysis (FP) process using [...] Read more.
The objectives of this study were to utilize bio-oil-based epoxy resin in oriented strand board (OSB) production and investigate the effect of bio-oil substitution in epoxy resin as an adhesive for OSB production. Bio-oil was produced by the fast pyrolysis (FP) process using southern yellow pine (Pinus spp.). Bio-oil-based epoxy resin was synthesized by the modification of epoxy resin with FP bio-oil at various substitution levels. Acetone extraction using a Soxhlet process indicated a superior cured reaction of bio-oil and epoxy resin at 20% bio-oil substitution. FTIR spectra corroborated the Soxhlet extraction with the removal of the epoxide peak signature within the cross-linked polymer. Images from the scanning electron microscopy suggested bulk phase homogeneity. OSB panels were tested according to ASTM D1037-12. The modulus of rupture (MOR), modulus of elasticity (MOE), internal bond strength, and water resistance (thickness swell and water absorption) properties of the OSB panels were feasible at bio-oil substitution up to 30% in the epoxy resin system. Full article
(This article belongs to the Special Issue Bio-Based Polymer Composites)
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7 pages, 1550 KiB  
Communication
Treatment of Mode Coupling in Step-Index Multimode Microstructured Polymer Optical Fibers by the Langevin Equation
by Svetislav Savović, Linqing Li, Isidora Savović, Alexandar Djordjevich and Rui Min
Polymers 2022, 14(6), 1243; https://doi.org/10.3390/polym14061243 - 19 Mar 2022
Cited by 3 | Viewed by 1409
Abstract
By solving the Langevin equation, mode coupling in a multimode step-index microstructured polymer optical fibers (SI mPOF) with a solid core was investigated. The numerical integration of the Langevin equation was based on the computer-simulated Langevin force. The numerical solution of the Langevin [...] Read more.
By solving the Langevin equation, mode coupling in a multimode step-index microstructured polymer optical fibers (SI mPOF) with a solid core was investigated. The numerical integration of the Langevin equation was based on the computer-simulated Langevin force. The numerical solution of the Langevin equation corresponded to the previously reported theoretical data. We demonstrated that by solving the Langevin equation (stochastic differential equation), one can successfully treat a mode coupling in multimode SI mPOF as a stochastic process, since it is caused by its intrinsic random perturbations. Thus, the Langevin equation allowed for a stochastic mathematical description of mode coupling in SI mPOF. Regarding the efficiency and execution speed, the Langevin equation was more favorable than the power flow equation. Such knowledge is useful for the use of multimode SI mPOFs for potential sensing and communication applications. Full article
(This article belongs to the Special Issue Advances in Polymer Optical Fibers)
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13 pages, 11173 KiB  
Article
Tribological and Antibacterial Properties of Polyetheretherketone Composites with Black Phosphorus Nanosheets
by Xuhui Sun, Chengcheng Yu, Lin Zhang, Jingcao Cao, Emrullah Hakan Kaleli and Guoxin Xie
Polymers 2022, 14(6), 1242; https://doi.org/10.3390/polym14061242 - 19 Mar 2022
Cited by 12 | Viewed by 2268
Abstract
Over the past few decades, polyetheretherketone (PEEK) artificial bone joint materials faced problems of poor wear resistance and easy infection, which are not suitable for the growing demand of bone joints. The tribological behavior and wear mechanism of polyetheretherketone (PEEK)/polytetrafluoroethylene (PTFE) with black [...] Read more.
Over the past few decades, polyetheretherketone (PEEK) artificial bone joint materials faced problems of poor wear resistance and easy infection, which are not suitable for the growing demand of bone joints. The tribological behavior and wear mechanism of polyetheretherketone (PEEK)/polytetrafluoroethylene (PTFE) with black phosphorus (BP) nanosheets have been investigated under dry sliding friction. Compared with pure PEEK, the COF of PEEK/10 wt% PTFE/0.5 wt% BP was reduced by about 73% (from 0.369 to 0.097) and the wear rate decreased by approximately 95% (from 1.0 × 10−4 mm3/(N m) to 5.1 × 10−6 mm3/(N m)) owing to the lubrication of the BP transfer film. Moreover, BP can endow the PEEK composites with excellent biological wettability and antibacterial properties. The antibacterial rate of PEEK/PTFE/BP was assessed to be over 99.9%, which might help to solve the problem of PEEK implant inflammation. After comprehensive evaluation in this research, 0.5 wt% BP nanosheet-filled PEEK/PTFE material displayed the optimum lubrication and antibacterial properties, and thus could be considered as a potential candidate for its application in biomedical materials. Full article
(This article belongs to the Special Issue Advanced Polymers for Biomedical Applications)
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13 pages, 26305 KiB  
Article
Stabilizing Effect of Soluplus on Erlotinib Metastable Crystal Form in Microparticles and Amorphous Solid Dispersions
by Shuyu Jia, Shangqi Ning, Yuting Leng, Qiufang Jing, Zhongyu Xu and Fuzheng Ren
Polymers 2022, 14(6), 1241; https://doi.org/10.3390/polym14061241 - 19 Mar 2022
Cited by 8 | Viewed by 2158
Abstract
Microparticles (MPs) and amorphous solid dispersions (SDs) are effective methods to improve the dissolution of insoluble drugs. However, stability is a concern for these two high-energy systems, resulting from high surface area and amorphous polymorph, respectively. As an amphiphilic polymer, Soluplus (SOL) is [...] Read more.
Microparticles (MPs) and amorphous solid dispersions (SDs) are effective methods to improve the dissolution of insoluble drugs. However, stability is a concern for these two high-energy systems, resulting from high surface area and amorphous polymorph, respectively. As an amphiphilic polymer, Soluplus (SOL) is usually used as a carrier in SDs. In this study, erlotinib microparticles (ERL MPs) and erlotinib solid dispersions (ERL SDs) were prepared with SOL by bottom-up technology and solvent evaporation. The solid-state properties of ERL MPs and ERL SDs were characterized by Differential Scanning Calorimetry (DSC), Powder X-Ray Diffraction (PXRD) and Scanning Electron Microscopy (SEM). The ERL MPs existed in a metastable crystal form A while the ERL SDs existed in an amorphous state. Fourier transform infrared spectroscopy (FT-IR) showed that there was a hydrogen bond interaction between the N-H group of ERL and the carbonyl group of SOL in ERL MPs and SDs. The dissolution profiles of ERL SDs and ERL MPs were improved significantly. ERL MPs showed better stability than ERL SDs in accelerated stability test. The discrepant stabilizing effects of polymer SOL in two systems may provide effective ideas for solubilization of insoluble drugs and the stability of drugs after recrystallization. Full article
(This article belongs to the Special Issue Bioactive Polymer Composites and Their Clinical Applications)
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