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Polymers, Volume 12, Issue 12 (December 2020) – 308 articles

Cover Story (view full-size image): Heterografted copolymers varied by ratio of PEG/PCL side chains are proposed as carriers designed for the delivery of substances applicable in cosmetology that include dermatological problems. The self-assembling copolymers formed micelles with the ability to encapsulate cosmetic substances, e.g., arbutin, vitamin C, 4-n-butylresorcinol. The nature of the loaded substance interacting with polymer matrix is crucial in kinetic release profiles. The permeation tests of the active substance released through a membrane acting as human skin in Franz chambers indicated a moderate diffusion into solution and remained in the membrane, which is satisfactory for most cosmetic applications. View this paper.
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8 pages, 2144 KiB  
Article
Two-Dimensional Piezoresistive Response and Measurement of Sensitivity Factor of Polymer-Matrix Carbon Fiber Mat
by Min Wu, Li Huang, Xiaoyu Zhang, Jianzhong Chen and Yong Lv
Polymers 2020, 12(12), 3072; https://doi.org/10.3390/polym12123072 - 21 Dec 2020
Cited by 1 | Viewed by 2267
Abstract
Based on the piezoresistive effect, the piezoresistive constitutive relation of a carbon fiber mat under orthogonal strain was deduced. Considering the Poisson effect, the piezoresistive responses and measurement of the sensitivity factor of a polymer-matrix carbon fiber mat under bidirectional strain were studied [...] Read more.
Based on the piezoresistive effect, the piezoresistive constitutive relation of a carbon fiber mat under orthogonal strain was deduced. Considering the Poisson effect, the piezoresistive responses and measurement of the sensitivity factor of a polymer-matrix carbon fiber mat under bidirectional strain were studied by a two-times uniaxial tension loading method in different directions, which was pasted in the center area of a cruciform aluminum substrate. The relations between the resistance change rate and the orthogonal strains were established, the reasonability of which was confirmed by comparison with the experimental results. The results show that the longitudinal piezoresistive sensitivity factor C11 is 21.55, and the lateral piezoresistive sensitivity factor C12 is 24.15. Using these factors, the resistance change rate of another polymer-matrix carbon mat was predicted, which was made by the same technique, and the error between the predicted and the experimental results was 1.3% in the longitudinal direction and 6.1% in the lateral direction. Full article
(This article belongs to the Special Issue Reinforced Polymer Composites II)
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18 pages, 4501 KiB  
Article
Study on the Anti-Biodegradation Property of Tunicate Cellulose
by Yanan Cheng, Ajoy Kanti Mondal, Shuai Wu, Dezhong Xu, Dengwen Ning, Yonghao Ni and Fang Huang
Polymers 2020, 12(12), 3071; https://doi.org/10.3390/polym12123071 - 21 Dec 2020
Cited by 15 | Viewed by 3382
Abstract
Tunicate is a kind of marine animal, and its outer sheath consists of almost pure Iβ crystalline cellulose. Due to its high aspect ratio, tunicate cellulose has excellent physical properties. It draws extensive attention in the construction of robust functional materials. However, [...] Read more.
Tunicate is a kind of marine animal, and its outer sheath consists of almost pure Iβ crystalline cellulose. Due to its high aspect ratio, tunicate cellulose has excellent physical properties. It draws extensive attention in the construction of robust functional materials. However, there is little research on its biological activity. In this study, cellulose enzymatic hydrolysis was conducted on tunicate cellulose. During the hydrolysis, the crystalline behaviors, i.e., crystallinity index (CrI), crystalline size and degree of polymerization (DP), were analyzed on the tunicate cellulose. As comparisons, similar hydrolyses were performed on cellulose samples with relatively low CrI, namely α-cellulose and amorphous cellulose. The results showed that the CrI of tunicate cellulose and α-cellulose was 93.9% and 70.9%, respectively; and after 96 h of hydrolysis, the crystallinity, crystalline size and DP remained constant on the tunicate cellulose, and the cellulose conversion rate was below 7.8%. While the crystalline structure of α-cellulose was significantly damaged and the cellulose conversion rate exceeded 83.8% at the end of 72 h hydrolysis, the amorphous cellulose was completely converted to glucose after 7 h hydrolysis, and the DP decreased about 27.9%. In addition, tunicate cellulose has high anti-mold abilities, owing to its highly crystalized Iβ lattice. It can be concluded that tunicate cellulose has significant resistance to enzymatic hydrolysis and could be potentially applied as anti-biodegradation materials. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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15 pages, 3181 KiB  
Article
Calcined Co(II)-Triethylenetetramine, Co(II)- Polyaniline-Thiourea as the Cathode Catalyst of Proton Exchanged Membrane Fuel Cell
by Wen-Yao Huang, Li-Cheng Jheng, Tar-Hwa Hsieh, Ko-Shan Ho, Yen-Zen Wang, Yi-Jhun Gao and Po-Hao Tseng
Polymers 2020, 12(12), 3070; https://doi.org/10.3390/polym12123070 - 21 Dec 2020
Cited by 9 | Viewed by 3094
Abstract
Triethylenetetramine (TETA) and thiourea complexed Cobalt(II) (Co(II)) ions are used as cathode catalysts for proton exchanged membrane fuel cells (PEMFCs) under the protection of polyaniline (PANI) which can become a conducting medium after calcination. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) [...] Read more.
Triethylenetetramine (TETA) and thiourea complexed Cobalt(II) (Co(II)) ions are used as cathode catalysts for proton exchanged membrane fuel cells (PEMFCs) under the protection of polyaniline (PANI) which can become a conducting medium after calcination. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra clearly reveal the presence of typical carbon nitride and sulfide bonds of the calcined Nitrogen (N)- or Sulfur (S)-doped co-catalysts. Clear (002) and (100) planes of carbon-related X-ray diffraction patterns are found for co-catalysts after calcination, related to the formation of a conducting medium after the calcination of PANI. An increasing intensity ratio of the D to G band of the Raman spectra reveal the doping of N and S elements. More porous surfaces of co-catalysts are found in scanning electronic microscopy (SEM) micropictures when prepared in the presence of both TETA and thiourea (CoNxSyC). Linear sweep voltammetry (LSV) curves show the highest reducing current to be 4 mAcm−2 at 1600 rpm for CoNxSyC, indicating the necessity for both N- and S-doping. The membrane electrode assemblies (MEA) prepared with the cathode made of CoNxSyC produces the highest maximum power density, close to 180 mW cm−2. Full article
(This article belongs to the Special Issue Functional and Conductive Polymer Thin Films II)
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18 pages, 5014 KiB  
Article
Robustness of Empirical Vibration Correlation Techniques for Predicting the Instability of Unstiffened Cylindrical Composite Shells in Axial Compression
by Eduards Skukis, Gints Jekabsons, Jānis Andersons, Olgerts Ozolins, Edgars Labans and Kaspars Kalnins
Polymers 2020, 12(12), 3069; https://doi.org/10.3390/polym12123069 - 21 Dec 2020
Cited by 5 | Viewed by 2763
Abstract
Thin-walled carbon fiber reinforced plastic (CFRP) shells are increasingly used in aerospace industry. Such shells are prone to the loss of stability under compressive loads. Furthermore, the instability onset of monocoque shells exhibits a pronounced imperfection sensitivity. The vibration correlation technique (VCT) is [...] Read more.
Thin-walled carbon fiber reinforced plastic (CFRP) shells are increasingly used in aerospace industry. Such shells are prone to the loss of stability under compressive loads. Furthermore, the instability onset of monocoque shells exhibits a pronounced imperfection sensitivity. The vibration correlation technique (VCT) is being developed as a nondestructive test method for evaluation of the buckling load of the shells. In this study, accuracy and robustness of an existing and a modified VCT method are evaluated. With this aim, more than 20 thin-walled unstiffened CFRP shells have been produced and tested. The results obtained suggest that the vibration response under loads exceeding 0.25 of the linear buckling load needs to be characterized for a successful application of the VCT. Then the largest unconservative discrepancy of prediction by the modified VCT method amounted to ca. 22% of the critical load. Applying loads exceeding 0.9 of the buckling load reduced the average relative discrepancy to 6.4%. Full article
(This article belongs to the Special Issue Fiber-Reinforced Composites: Innovative Solutions and Advanced Analysis Methods)
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13 pages, 1886 KiB  
Article
Structural and Dynamical Characteristics of Short-Chain Branched Ring Polymer Melts at Interface under Shear Flow
by Seung Heum Jeong, Soowon Cho, Tae Yong Ha, Eun Jung Roh and Chunggi Baig
Polymers 2020, 12(12), 3068; https://doi.org/10.3390/polym12123068 - 21 Dec 2020
Cited by 9 | Viewed by 2768
Abstract
We present a detailed analysis of the interfacial chain structure and dynamics of confined polymer melt systems under shear over a wide range of flow strengths using atomistic nonequilibrium molecular dynamics simulations, paying particular attention to the rheological influence of the closed-loop ring [...] Read more.
We present a detailed analysis of the interfacial chain structure and dynamics of confined polymer melt systems under shear over a wide range of flow strengths using atomistic nonequilibrium molecular dynamics simulations, paying particular attention to the rheological influence of the closed-loop ring geometry and short-chain branching. We analyzed the interfacial slip, characteristic molecular mechanisms, and deformed chain conformations in response to the applied flow for linear, ring, short-chain branched (SCB) linear, and SCB ring polyethylene melts. The ring topology generally enlarges the interfacial chain dimension along the neutral direction, enhancing the dynamic friction of interfacial chains moving against the wall in the flow direction. This leads to a relatively smaller degree of slip (ds) for the ring-shaped polymers compared with their linear analogues. Furthermore, short-chain branching generally resulted in more compact and less deformed chain structures via the intrinsically fast random motions of the short branches. The short branches tend to be oriented more perpendicular (i.e., aligned in the neutral direction) than parallel to the backbone, which is mostly aligned in the flow direction, thereby enhancing the dynamic wall friction of the moving interfacial chains toward the flow direction. These features afford a relatively lower ds and less variation in ds in the weak-to-intermediate flow regimes. Accordingly, the interfacial SCB ring system displayed the lowest ds among the studied polymer systems throughout these regimes owing to the synergetic effects of ring geometry and short-chain branching. On the contrary, the structural disturbance exerted by the highly mobile short branches promotes the detachment of interfacial chains from the wall at strong flow fields, which results in steeper increasing behavior of the interfacial slip for the SCB polymers in the strong flow regime compared to the pure linear and ring polymers. Full article
(This article belongs to the Special Issue Theory of Polymers at Interfaces)
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30 pages, 5422 KiB  
Review
Insight into the Structure and Dynamics of Polymers by Neutron Scattering Combined with Atomistic Molecular Dynamics Simulations
by Arantxa Arbe, Fernando Alvarez and Juan Colmenero
Polymers 2020, 12(12), 3067; https://doi.org/10.3390/polym12123067 - 21 Dec 2020
Cited by 18 | Viewed by 4116
Abstract
Combining neutron scattering and fully atomistic molecular dynamics simulations allows unraveling structural and dynamical features of polymer melts at different length scales, mainly in the intermolecular and monomeric range. Here we present the methodology developed by us and the results of its application [...] Read more.
Combining neutron scattering and fully atomistic molecular dynamics simulations allows unraveling structural and dynamical features of polymer melts at different length scales, mainly in the intermolecular and monomeric range. Here we present the methodology developed by us and the results of its application during the last years in a variety of polymers. This methodology is based on two pillars: (i) both techniques cover approximately the same length and time scales and (ii) the classical van Hove formalism allows easily calculating the magnitudes measured by neutron scattering from the simulated atomic trajectories. By direct comparison with experimental results, the simulated cell is validated. Thereafter, the information of the simulations can be exploited, calculating magnitudes that are experimentally inaccessible or extending the parameters range beyond the experimental capabilities. We show how detailed microscopic insight on structural features and dynamical processes of various kinds has been gained in polymeric systems with different degrees of complexity, and how intriguing questions as the collective behavior at intermediate length scales have been faced. Full article
(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))
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18 pages, 3199 KiB  
Article
New Functionalized Polymeric Sensor Based NiO/MgO Nanocomposite for Potentiometric Determination of Doxorubicin Hydrochloride in Commercial Injections and Human Plasma
by Nawal A. Alarfaj and Maha F. El-Tohamy
Polymers 2020, 12(12), 3066; https://doi.org/10.3390/polym12123066 - 21 Dec 2020
Cited by 18 | Viewed by 3049
Abstract
The ultra-functional potential of nickel oxide (NiO) and magnesium oxide (MgO) nanoparticles (NPs), provides for extensive attention in the use of these metal oxides as a remarkable and electroactive nanocomposite in potentiometric and sensing investigations. This work proposed a new strategy for quantifying [...] Read more.
The ultra-functional potential of nickel oxide (NiO) and magnesium oxide (MgO) nanoparticles (NPs), provides for extensive attention in the use of these metal oxides as a remarkable and electroactive nanocomposite in potentiometric and sensing investigations. This work proposed a new strategy for quantifying doxorubicin hydrochloride (DOX) in pharmaceuticals and human plasma by preparing a NiO/MgO core-shell nanocomposite modified coated wire membrane sensor. Doxorubicin hydrochloride was incorporated with phosphomolybdic acid (PMA) to produce doxorubicin hydrochloride phosphomolybdate (DOX-PM) as an electroactive material in the presence of polymeric high molecular weight poly vinyl chloride (PVC) and solvent mediator o-nitrophenyloctyl ether (o-NPOE). The modified sensor exhibited ultra sensitivity and high selectivity for the detection and quantification of doxorubicin hydrochloride with a linear relationship in the range of 1.0 × 10−11–1.0 × 10−2 mol L−1. The equation of regression was estimated to be EmV = (57.86 ± 0.8) log [DOX] + 723.19. However, the conventional type DOX-PM showed a potential response over a concentration range of 1.0 × 10−6–1.0 × 10−2 mol L−1 and a regression equation of EmV = (52.92 ± 0.5) log [DOX] + 453.42. The suggested sensors were successfully used in the determination of doxorubicin hydrochloride in commercial injections and human plasma. Full article
(This article belongs to the Special Issue High-Performance Polymeric Sensors )
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14 pages, 8947 KiB  
Article
Chitosan–Hydroxyapatite Composite Layers Generated in Radio Frequency Magnetron Sputtering Discharge: From Plasma to Structural and Morphological Analysis of Layers
by Dragana Biliana Dreghici, Bogdan Butoi, Daniela Predoi, Simona Liliana Iconaru, Ovidiu Stoican and Andreea Groza
Polymers 2020, 12(12), 3065; https://doi.org/10.3390/polym12123065 - 21 Dec 2020
Cited by 18 | Viewed by 3388
Abstract
Chitosan–hydroxyapatite composite layers were deposited on Si substrates in radio frequency magnetron sputtering discharges. The plasma parameters calculated from the current–voltage radio frequency-compensated Langmuir probe characteristics indicate a huge difference between the electron temperature in the plasma and at the sample holder. These [...] Read more.
Chitosan–hydroxyapatite composite layers were deposited on Si substrates in radio frequency magnetron sputtering discharges. The plasma parameters calculated from the current–voltage radio frequency-compensated Langmuir probe characteristics indicate a huge difference between the electron temperature in the plasma and at the sample holder. These findings aid in the understanding of the coagulation pattern of hydroxyapatite–chitosan macromolecules on the substrate surface. An increase in the sizes of the spherical-shape grain-like structures formed on the coating surface with the plasma electron number density was observed. The link between the chemical composition of the chitosan–hydroxyapatite composite film and the species sputtered from the target or produced by excitation/ionization mechanisms in the plasma was determined on the basis of X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and residual gas mass spectrometry analysis. Full article
(This article belongs to the Special Issue Advances in Polymer Based Composite Coatings)
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13 pages, 5249 KiB  
Article
Effect of Microcapsule Content on Diels-Alder Room Temperature Self-Healing Thermosets
by Sadella C. Santos, John J. La Scala and Giuseppe R. Palmese
Polymers 2020, 12(12), 3064; https://doi.org/10.3390/polym12123064 - 21 Dec 2020
Cited by 3 | Viewed by 2114
Abstract
A furan functionalized epoxy-amine thermoset with an embedded microcapsule healing system that utilizes reversible Diels-Alder healing chemistry was used to investigate the influence of microcapsule loading on healing efficiency. A urea-formaldehyde encapsulation technique was used to create capsules with an average diameter of [...] Read more.
A furan functionalized epoxy-amine thermoset with an embedded microcapsule healing system that utilizes reversible Diels-Alder healing chemistry was used to investigate the influence of microcapsule loading on healing efficiency. A urea-formaldehyde encapsulation technique was used to create capsules with an average diameter of 150 µm that were filled with a reactive solution of bismaleimide in phenyl acetate. It was found that optimum healing of the thermoset occurred at 10 wt% microcapsule content for the compositions investigated. The diffusion of solvent through the crack interface and within fractured samples was investigated using analytical diffusion models. The decrease in healing efficiency at higher microcapsule loading was attributed partially to solvent-induced plasticization at the interface. The diffusion analysis also showed that the 10% optimum microcapsule concentration occurs for systems with the same interfacial solvent concentration. This suggests that additional physical and chemical phenomena are also responsible for the observed optimum. Such phenomena could include a reduction in surface area available for healing and the saturation of interfacial furan moieties by reaction with increasing amounts of maleimide. Both would result from increased microcapsule loading. Full article
(This article belongs to the Special Issue Recent Advances in Self-Healing Polymers)
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10 pages, 1700 KiB  
Article
Poly(d,l-lactide-co-glycolide) (PLGA) Nanoparticles Loaded with Proteolipid Protein (PLP)—Exploring a New Administration Route
by Alexandre Ferreira Lima, Isabel R. Amado and Liliana R. Pires
Polymers 2020, 12(12), 3063; https://doi.org/10.3390/polym12123063 - 21 Dec 2020
Cited by 23 | Viewed by 3247
Abstract
The administration of specific antigens is being explored as a mean to re-establish immunological tolerance, namely in the context of multiple sclerosis (MS). PLP139-151 is a peptide of the myelin’s most abundant protein, proteolipid protein (PLP), which has been identified as a potent [...] Read more.
The administration of specific antigens is being explored as a mean to re-establish immunological tolerance, namely in the context of multiple sclerosis (MS). PLP139-151 is a peptide of the myelin’s most abundant protein, proteolipid protein (PLP), which has been identified as a potent tolerogenic molecule in MS. This work explored the encapsulation of the peptide into poly(lactide-co-glycolide) nanoparticles and its subsequent incorporation into polymeric microneedle patches to achieve efficient delivery of the nanoparticles and the peptide into the skin, a highly immune-active organ. Different poly(d,l-lactide-co-glycolide) (PLGA) formulations were tested and found to be stable and to sustain a freeze-drying process. The presence of trehalose in the nanoparticle suspension limited the increase in nanoparticle size after freeze-drying. It was shown that rhodamine can be loaded in PLGA nanoparticles and these into poly(vinyl alcohol)–poly(vinyl pyrrolidone) microneedles, yielding fluorescently labelled structures. The incorporation of PLP into the PLGA nanoparticles resulted in nanoparticles in a size range of 200 µm and an encapsulation efficiency above 20%. The release of PLP from the nanoparticles occurred in the first hours after incubation in physiological media. When loading the nanoparticles into microneedle patches, structures were obtained with 550 µm height and 180 µm diameter. The release of PLP was detected in PLP–PLGA.H20 nanoparticles when in physiological media. Overall, the results show that this strategy can be explored to integrate a new antigen-specific therapy in the context of multiple sclerosis, providing minimally invasive administration of PLP-loaded nanoparticles into the skin. Full article
(This article belongs to the Special Issue Polymeric Carriers for Biomedical and Nanomedicine Application)
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12 pages, 3004 KiB  
Article
Optimization of Preparation Conditions for Side-Emitting Polymer Optical Fibers Using Response Surface Methodology
by Xianjin Hu, Kun Yang and Cheng Zhang
Polymers 2020, 12(12), 3062; https://doi.org/10.3390/polym12123062 - 21 Dec 2020
Cited by 3 | Viewed by 1934
Abstract
Polymer optical fibers (POFs) were used for preparing side-emitting polymer optical fibers (SPOFs), which were processed with acetone and n-hexane combined in selected proportions by a solvent treatment method. The effects of the volume ratio of acetone to n-hexane and treatment time on [...] Read more.
Polymer optical fibers (POFs) were used for preparing side-emitting polymer optical fibers (SPOFs), which were processed with acetone and n-hexane combined in selected proportions by a solvent treatment method. The effects of the volume ratio of acetone to n-hexane and treatment time on response variable factors were investigated. The center composite design (CCD) based response surface methodology (RSM), a quadratic model, and a two-factor interaction model were developed to relate the preparation variables of illumination intensity, breaking strength, and rigidity. According to analysis of variance (ANOVA), the factors affecting the optimization of each response factor were determined. The predicted values after process optimization were found to be highly similar to the experimental values. The optimal conditions for the preparation of SPOF were as follows: the volume ratio of acetone to hexane was 1.703, and the treatment time was 2.716 s. The three response variables of SPOF prepared under the optimal conditions were: illumination intensity 19.339 mV, breaking strength 5.707 N, and rigidity 572.013 N·mm2. Full article
(This article belongs to the Section Polymer Physics and Theory)
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26 pages, 4045 KiB  
Review
Biopolymer Coatings for Biomedical Applications
by A. Joseph Nathanael and Tae Hwan Oh
Polymers 2020, 12(12), 3061; https://doi.org/10.3390/polym12123061 - 21 Dec 2020
Cited by 91 | Viewed by 9399
Abstract
Biopolymer coatings exhibit outstanding potential in various biomedical applications, due to their flexible functionalization. In this review, we have discussed the latest developments in biopolymer coatings on various substrates and nanoparticles for improved tissue engineering and drug delivery applications, and summarized the latest [...] Read more.
Biopolymer coatings exhibit outstanding potential in various biomedical applications, due to their flexible functionalization. In this review, we have discussed the latest developments in biopolymer coatings on various substrates and nanoparticles for improved tissue engineering and drug delivery applications, and summarized the latest research advancements. Polymer coatings are used to modify surface properties to satisfy certain requirements or include additional functionalities for different biomedical applications. Additionally, polymer coatings with different inorganic ions may facilitate different functionalities, such as cell proliferation, tissue growth, repair, and delivery of biomolecules, such as growth factors, active molecules, antimicrobial agents, and drugs. This review primarily focuses on specific polymers for coating applications and different polymer coatings for increased functionalization. We aim to provide broad overview of latest developments in the various kind of biopolymer coatings for biomedical applications, in order to highlight the most important results in the literatures, and to offer a potential outline for impending progress and perspective. Some key polymer coatings were discussed in detail. Further, the use of polymer coatings on nanomaterials for biomedical applications has also been discussed, and the latest research results have been reported. Full article
(This article belongs to the Special Issue Polymer-Based Biocompatible System)
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15 pages, 4698 KiB  
Article
A Preliminary Study of the Influence of Graphene Nanoplatelet Specific Surface Area on the Interlaminar Fracture Properties of Carbon Fiber/Epoxy Composites
by Konstantina Zafeiropoulou, Christina Kostagiannakopoulou, George Sotiriadis and Vassilis Kostopoulos
Polymers 2020, 12(12), 3060; https://doi.org/10.3390/polym12123060 - 21 Dec 2020
Cited by 10 | Viewed by 2688
Abstract
Graphene nanoplatelets (GNPs) are of particular interest to the field of nano-reinforced composites since they possess superior mechanical, fracture, thermal, and barrier properties. Due to their geometrical characteristics, high aspect ratio (AR)/specific surface area (SSA) and their planar structure, GNPs are considered as [...] Read more.
Graphene nanoplatelets (GNPs) are of particular interest to the field of nano-reinforced composites since they possess superior mechanical, fracture, thermal, and barrier properties. Due to their geometrical characteristics, high aspect ratio (AR)/specific surface area (SSA) and their planar structure, GNPs are considered as high-potential nanosized fillers for improving performance of composites. The present study investigates the effect of SSA of GNPs on fracture properties of carbon fiber reinforced polymers (CFRPs). For this reason, two nano-doped CFRPs were produced by using two types of GNPs (C300 and C500) with different SSAs, 300 and 500 m2/g, respectively. Both types of GNPs, at the same content of 0.5 wt%, were added into the epoxy matrix of composites by applying a three-roll milling technique. The nanomodified matrix was used for the manufacturing of prepregs, while the final composite laminates were fabricated through the vacuum-bag method. Mode I and II interlaminar fracture tests were carried out to determine the interlaminar fracture toughness GIC and GIIC of the composites, respectively. According to the results, the toughening effect of C500 GNPs was the strongest, resulting in increases of 25% in GIC and 33% in GIIC compared with the corresponding unmodified composites. The activation of the absorption mechanisms of C500 contributed to this outcome, which was confirmed by the scanning electron microscopy (SEM) analyses conducted in the fracture surfaces of specimens. On the other hand, C300 GNPs, due to disability to be dispersed uniformly into the epoxy matrix, did not influence the fracture properties of CFRPs, indicating that probably there is a threshold in SSA which is necessary to achieve for improving the fracture properties of CFRPs. Full article
(This article belongs to the Collection Reinforced Polymer Composites)
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13 pages, 2085 KiB  
Article
Effects of Bromination-Dehydrobromination on the Microstructure of Isotropic Pitch Precursors for Carbon Fibers
by Dingcheng Liang, Deqian Liu, Shuai Yang, Changyu Lu, Qiang Xie and Jinchang Liu
Polymers 2020, 12(12), 3059; https://doi.org/10.3390/polym12123059 - 20 Dec 2020
Cited by 14 | Viewed by 2763
Abstract
In this work, isotropic pitch precursors are synthesized by the bromination-debromination method with ethylene bottom oil (EO) as the raw material and bromine as the initiator for pitch formation and condensation reactions. The aggregation structure, molecular weight distribution, and molecular structure of isotropic [...] Read more.
In this work, isotropic pitch precursors are synthesized by the bromination-debromination method with ethylene bottom oil (EO) as the raw material and bromine as the initiator for pitch formation and condensation reactions. The aggregation structure, molecular weight distribution, and molecular structure of isotropic pitch precursors are characterized by thermal mechanical analyzer (TMA), MALDI TOF-MS, and 13C NMR, respectively, for revealing the mechanism of synthesis of isotropic pitch precursors. The results show that at low bromine concentrations, polycyclic aromatic hydrocarbons (PAHs) were mainly ordered in cross-linked structures by bromination-debromination through substitution reactions of side chains. The condensed reactivity can be improved by the effect of bromine, meaning that condensation reaction was aggravated by the method of bromination-dehydrobromination. In the presence of excess bromine, the cross-linked stereo structure of PAHs changed to the planar structure of condensed PAHs, which was not conducive to the subsequent spinning and preparation of carbon fibers. Full article
(This article belongs to the Section Polymer Physics and Theory)
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14 pages, 2651 KiB  
Article
The Investigation of the Silica-Reinforced Rubber Polymers with the Methoxy Type Silane Coupling Agents
by Sang Yoon Lee, Jung Soo Kim, Seung Ho Lim, Seong Hyun Jang, Dong Hyun Kim, No-Hyung Park, Jae Woong Jung and Jun Choi
Polymers 2020, 12(12), 3058; https://doi.org/10.3390/polym12123058 - 20 Dec 2020
Cited by 35 | Viewed by 5518
Abstract
The methoxy-type silane coupling agents were synthesized via the modification of the hydrolyzable group and characterized to investigate the change in properties of silica/rubber composites based on the different silane coupling agent structures and the masterbatch fabrication methods. The prepared methoxy-type silane coupling [...] Read more.
The methoxy-type silane coupling agents were synthesized via the modification of the hydrolyzable group and characterized to investigate the change in properties of silica/rubber composites based on the different silane coupling agent structures and the masterbatch fabrication methods. The prepared methoxy-type silane coupling agents exhibited higher reactivity towards hydrolysis compared to the conventional ethoxy-type one which led to the superior silanization to the silica filler surface modified for the reinforcement of styrene-butadiene rubber. The silica/rubber composites based on these methoxy-type silane coupling agents had the characteristics of more developed vulcanization and mechanical properties when fabricated as masterbatch products for tread materials of automobile tire surfaces. In particular, the dimethoxy-type silane coupling agent showed more enhanced rubber composite properties than the trimethoxy-type one, and the environmentally friendly wet masterbatch fabrication process was successfully optimized. The reactivity of the synthesized silane coupling agents toward hydrolysis was investigated by FITR spectroscopic analysis, and the mechanical properties of the prepared silica-reinforced rubber polymers were characterized using a moving die rheometer and a universal testing machine. Full article
(This article belongs to the Special Issue Polymer-SiO₂ Composites)
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15 pages, 3371 KiB  
Article
Personalised 3D Printed Fast-Dissolving Tablets for Managing Hypertensive Crisis: In-Vitro/In-Vivo Studies
by Amjad Hussain, Faisal Mahmood, Muhammad Sohail Arshad, Nasir Abbas, Nadia Qamar, Jahanzeb Mudassir, Samia Farhaj, Jorabar Singh Nirwan and Muhammad Usman Ghori
Polymers 2020, 12(12), 3057; https://doi.org/10.3390/polym12123057 - 20 Dec 2020
Cited by 19 | Viewed by 3809
Abstract
Hypertensive crisis (HC) is an emergency health condition which requires an effective management strategy. Over the years, various researchers have developed captopril based fast-dissolving formulations to manage HC; however, primarily, the question of personalisation remains unaddressed. Moreover, commercially these formulations are available as [...] Read more.
Hypertensive crisis (HC) is an emergency health condition which requires an effective management strategy. Over the years, various researchers have developed captopril based fast-dissolving formulations to manage HC; however, primarily, the question of personalisation remains unaddressed. Moreover, commercially these formulations are available as in fixed-dose combinations or strengths, so the titration of dose according to patient’s prerequisite is challenging to achieve. The recent emergence of 3D printing technologies has given pharmaceutical scientists a way forward to develop personalised medicines keeping in view patients individual needs. The current project, therefore, is aimed at addressing the limitations as mentioned above by developing fast-dissolving captopril tablets using 3D printing approach. Captopril unloaded (F1) and loaded (F2-F4) filaments were successfully produced with an acceptable drug loading and mechanical properties. Various captopril formulations (F2–F4) were successfully printed using fused deposition modelling technique. The results revealed that the formulations (F2 and F3) containing superdisintegrant had a faster extent of dissolution and in-vivo findings were endorsing these results. The present study has successfully exhibited the utilisation of additive manufacturing approach to mend the gap of personalisation and manufacturing fast-dissolving captopril 3D printed tablets. The procedure adopted in the present study may be used for the development of fused deposition modelling (FDM) based fast-dissolving 3D printed tablets. Full article
(This article belongs to the Special Issue Exploitation of Polymer Structure and Mechanics in Developing Medicines)
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16 pages, 5849 KiB  
Article
The Study of Physico-Mechanical Properties of Polylactide Composites with Different Level of Infill Produced by the FDM Method
by Anna Gaweł and Stanisław Kuciel
Polymers 2020, 12(12), 3056; https://doi.org/10.3390/polym12123056 - 20 Dec 2020
Cited by 15 | Viewed by 2652
Abstract
The aim of this study was to evaluate the changes in physical-mechanical properties of the samples manufactured by 3D printing technology with the addition of varying degrees of polylactide (PLA) infill (50, 70, 85 and 100%). Half of the samples were soaked in [...] Read more.
The aim of this study was to evaluate the changes in physical-mechanical properties of the samples manufactured by 3D printing technology with the addition of varying degrees of polylactide (PLA) infill (50, 70, 85 and 100%). Half of the samples were soaked in physiological saline. The material used for the study was neat PLA, which was examined in terms of hydrolytic degradation, crystallization, mechanical strength, variability of properties at elevated temperatures, and dissipation of mechanical energy depending on the performed treatment. A significant impact of the amount of infill on changeable mechanical properties, such as hydrolytic degradation and crystallization was observed. The FDM printing method allows for waste–free production of light weight unit products with constant specyfic strength. Full article
(This article belongs to the Special Issue 3D and 4D Printing of (Bio)Materials II)
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23 pages, 4723 KiB  
Review
Advancements in the Blood–Brain Barrier Penetrating Nanoplatforms for Brain Related Disease Diagnostics and Therapeutic Applications
by Suresh Thangudu, Fong-Yu Cheng and Chia-Hao Su
Polymers 2020, 12(12), 3055; https://doi.org/10.3390/polym12123055 - 20 Dec 2020
Cited by 46 | Viewed by 8464
Abstract
Noninvasive treatments to treat the brain-related disorders have been paying more significant attention and it is an emerging topic. However, overcoming the blood brain barrier (BBB) is a key obstacle to most of the therapeutic drugs to enter into the brain tissue, which [...] Read more.
Noninvasive treatments to treat the brain-related disorders have been paying more significant attention and it is an emerging topic. However, overcoming the blood brain barrier (BBB) is a key obstacle to most of the therapeutic drugs to enter into the brain tissue, which significantly results in lower accumulation of therapeutic drugs in the brain. Thus, administering the large quantity/doses of drugs raises more concerns of adverse side effects. Nanoparticle (NP)-mediated drug delivery systems are seen as potential means of enhancing drug transport across the BBB and to targeted brain tissue. These systems offer more accumulation of therapeutic drugs at the tumor site and prolong circulation time in the blood. In this review, we summarize the current knowledge and advancements on various nanoplatforms (NF) and discusses the use of nanoparticles for successful cross of BBB to treat the brain-related disorders such as brain tumors, Alzheimer’s disease, Parkinson’s disease, and stroke. Full article
(This article belongs to the Special Issue Intelligent Polymeric Delivery System for Biomedical Applications)
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21 pages, 2735 KiB  
Article
Adenine as Epoxy Resin Hardener for Sustainable Composites Production with Recycled Carbon Fibers and Cellulosic Fibers
by Stefano Merighi, Laura Mazzocchetti, Tiziana Benelli and Loris Giorgini
Polymers 2020, 12(12), 3054; https://doi.org/10.3390/polym12123054 - 20 Dec 2020
Cited by 4 | Viewed by 3397
Abstract
In this work, Adenine is proposed, for the first time, as a cross-linker for epoxy resins. Adenine is an amino-substituted purine with heterocyclic aromatic structure showing both proton donors, and hydrogen bonding ability. DSC studies show that adenine is able to positively cross-link [...] Read more.
In this work, Adenine is proposed, for the first time, as a cross-linker for epoxy resins. Adenine is an amino-substituted purine with heterocyclic aromatic structure showing both proton donors, and hydrogen bonding ability. DSC studies show that adenine is able to positively cross-link a biobased DGEBA-like commercial epoxy precursor with good thermal performance and a reaction mechanism based on a 1H NMR investigation has been proposed. The use of such a formulation to produce composite with recycled short carbon fibers (and virgin ones for the sake of comparison), as well as jute and linen natural fibers as sustainable reinforcements, leads to materials with high compaction and fiber content. The curing cycle was optimized for both carbon fiber and natural fiber reinforced materials, with the aim to achieve the better final properties. All composites produced display good thermal and mechanical properties with glass transition in the range of HT resins (Tg > 150 °C, E’ =26 GPa) for the carbon fiber-based composites. The natural fiber-based composites display slightly lower performance that is nonetheless good compared with standard composite performance (Tg about 115–120 °C, E’ = 7–9 GPa). The present results thus pave the way to the application of adenine as hardener system for composites production. Full article
(This article belongs to the Special Issue Polymers from Renewable Sources and Their Mechanical Reinforcement)
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17 pages, 8313 KiB  
Article
Crystallization and Thermal Behaviors of Poly(ethylene terephthalate)/Bisphenols Complexes through Melt Post-Polycondensation
by Shichang Chen, Shangdong Xie, Shanshan Guang, Jianna Bao, Xianming Zhang and Wenxing Chen
Polymers 2020, 12(12), 3053; https://doi.org/10.3390/polym12123053 - 19 Dec 2020
Cited by 17 | Viewed by 4554
Abstract
Three kinds of modified poly(ethylene terephthalate) (PET) were prepared by solution blending combined with melt post-polycondensation, using 4,4′-thiodiphenol (TDP), 4,4′-oxydiphenol (ODP) and hydroquinone (HQ) as the bisphenols, respectively. The effects of TDP, ODP and HQ on melt post-polycondensation process and crystallization kinetics, melting [...] Read more.
Three kinds of modified poly(ethylene terephthalate) (PET) were prepared by solution blending combined with melt post-polycondensation, using 4,4′-thiodiphenol (TDP), 4,4′-oxydiphenol (ODP) and hydroquinone (HQ) as the bisphenols, respectively. The effects of TDP, ODP and HQ on melt post-polycondensation process and crystallization kinetics, melting behaviors, crystallinity and thermal stability of PET/bisphenols complexes were investigated in detail. Excellent chain growth of PET could be achieved by addition of 1 wt% bisphenols, but intrinsic viscosity of modified PET decreased with further bisphenols content. Intermolecular hydrogen bonding between carbonyl groups of PET and hydroxyl groups of bisphenols were verified by Fourier transform infrared spectroscopy. Compare to pure PET, both the crystallization rate and melting temperatures of PET/bisphenols complexes were reduced obviously, suggesting an impeded crystallization and reduced lamellar thickness. Moreover, the structural difference between TDP, ODP and HQ played an important role on crystallization kinetics. It was proposed that the crystallization rate of TDP modified PET was reduced significantly due to the larger amount of rigid benzene ring and larger polarity than that of PET with ODP or HQ. X-ray diffraction results showed that the crystalline structure of PET did not change from the incorporation of bisphenols, but crystallinity of PET decreased with increasing bisphenols content. Thermal stability of modified PET declined slightly, which was hardly affected by the molecular structure of bisphenols. Full article
(This article belongs to the Special Issue Process–Structure–Properties in Polymer Additive Manufacturing)
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18 pages, 8166 KiB  
Article
The Bonding Mechanism of the Micro-Interface of Polymer Coated Steel
by Jiyang Liu, Qingdong Zhang, Boyang Zhang and Mingyang Yu
Polymers 2020, 12(12), 3052; https://doi.org/10.3390/polym12123052 - 19 Dec 2020
Cited by 11 | Viewed by 8237
Abstract
As food and beverages require more and more green and safe packaging products, the emergence of polymer coated steel (PCS) has been promoted. PCS is a layered composite strip made of metal and polymer. To probe the bonding mechanism of PCS micro-interface, the [...] Read more.
As food and beverages require more and more green and safe packaging products, the emergence of polymer coated steel (PCS) has been promoted. PCS is a layered composite strip made of metal and polymer. To probe the bonding mechanism of PCS micro-interface, the substrate tin-free steel (TFS) was physically characterized by SEM and XPS, and cladding polyethylene terephthalate (PET) was simulated by first-principles methods of quantum mechanics (QM). We used COMPASS force field for molecular dynamics (MD) simulation. XPS pointed out that the element composition of TFS surface coating is Cr(OH)3, Cr2O3 and CrO3. The calculation results of MD and QM indicate that the chromium oxide and PET molecules compound in the form of acid-base interaction. The binding energies of Cr2O3 (110), (200), and (211) with PET molecules are −13.07 eV, −2.74 eV, and −2.37 eV, respectively. We established a Cr2O3 (200) model with different hydroxyl concentrations. It is proposed that the oxygen atom in C=O in the PET molecule combines with –OH on the surface of TFS to form a hydrogen bond. The binding energy of the PCS interface increases with the increase of the surface hydroxyl concentration of the TFS. It provides theoretical guidance and reference significance for the research on the bonding mechanism of PCS. Full article
(This article belongs to the Section Polymer Applications)
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10 pages, 1924 KiB  
Review
Modified Fish Gelatin as an Alternative to Mammalian Gelatin in Modern Food Technologies
by Svetlana R. Derkach, Nikolay G. Voron’ko, Yuliya A. Kuchina and Daria S. Kolotova
Polymers 2020, 12(12), 3051; https://doi.org/10.3390/polym12123051 - 19 Dec 2020
Cited by 82 | Viewed by 6758
Abstract
This review considers the main properties of fish gelatin that determine its use in food technologies. A comparative analysis of the amino acid composition of gelatin from cold-water and warm-water fish species, in comparison with gelatin from mammals, which is traditionally used in [...] Read more.
This review considers the main properties of fish gelatin that determine its use in food technologies. A comparative analysis of the amino acid composition of gelatin from cold-water and warm-water fish species, in comparison with gelatin from mammals, which is traditionally used in the food industry, is presented. Fish gelatin is characterized by a reduced content of proline and hydroxyproline which are responsible for the formation of collagen-like triple helices. For this reason, fish gelatin gels are less durable and have lower gelation and melting temperatures than mammalian gelatin. These properties impose significant restrictions on the use of fish gelatin in the technology of gelled food as an alternative to porcine and bovine gelatin. This problem can be solved by modifying the functional characteristics of fish gelatin by adding natural ionic polysaccharides, which, under certain conditions, are capable of forming polyelectrolyte complexes with gelatin, creating additional nodes in the spatial network of the gel. Full article
(This article belongs to the Special Issue Biopolymers for Medicinal, Macromolecules, and Food Applications)
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21 pages, 2919 KiB  
Article
The Effect of Halloysite Nanotubes on the Fire Retardancy Properties of Partially Biobased Polyamide 610
by David Marset, Celia Dolza, Eduardo Fages, Eloi Gonga, Oscar Gutiérrez, Jaume Gomez-Caturla, Juan Ivorra-Martinez, Lourdes Sanchez-Nacher and Luis Quiles-Carrillo
Polymers 2020, 12(12), 3050; https://doi.org/10.3390/polym12123050 - 19 Dec 2020
Cited by 16 | Viewed by 3083
Abstract
The main objective of the work reported here was the analysis and evaluation of halloysite nanotubes (HNTs) as natural flame retardancy filler in partially biobased polyamide 610 (PA610), with 63% of carbon from natural sources. HNTs are naturally occurring clays with a nanotube-like [...] Read more.
The main objective of the work reported here was the analysis and evaluation of halloysite nanotubes (HNTs) as natural flame retardancy filler in partially biobased polyamide 610 (PA610), with 63% of carbon from natural sources. HNTs are naturally occurring clays with a nanotube-like shape. PA610 compounds containing 10%, 20%, and 30% HNT were obtained in a twin-screw co-rotating extruder. The resulting blends were injection molded to create standard samples for fire testing. The incorporation of the HNTs in the PA610 matrix leads to a reduction both in the optical density and a significant reduction in the number of toxic gases emitted during combustion. This improvement in fire properties is relevant in applications where fire safety is required. With regard to calorimetric cone results, the incorporation of 30% HNTs achieved a significant reduction in terms of the peak values obtained of the heat released rate (HRR), changing from 743 kW/m2 to about 580 kW/m2 and directly modifying the shape of the characteristic curve. This improvement in the heat released has produced a delay in the mass transfer of the volatile decomposition products, which are entrapped inside the HNTs’ lumen, making it difficult for the sample to burn. However, in relation to the ignition time of the samples (TTI), the incorporation of HNTs reduces the ignition start time about 20 s. The results indicate that it is possible to obtain polymer formulations with a high renewable content such as PA610, and a natural occurring inorganic filler in the form of a nanotube, i.e., HNTs, with good flame retardancy properties in terms of toxicity, optical density and UL94 test. Full article
(This article belongs to the Special Issue Biopolymers from Natural Resources)
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22 pages, 4508 KiB  
Article
A Highly Efficient Ag Nanoparticle-Immobilized Alginate-g-Polyacrylonitrile Hybrid Photocatalyst for the Degradation of Nitrophenols
by Imran Hasan, Charu Shekhar, Walaa Alharbi, Maymonah Abu Khanjer, Rais Ahmad Khan and Ali Alsalme
Polymers 2020, 12(12), 3049; https://doi.org/10.3390/polym12123049 - 19 Dec 2020
Cited by 16 | Viewed by 2353
Abstract
Herein, we report PAN-g-Alg@Ag-based nanocatalysts synthesis via in situ oxidative free-radical polymerization of acrylonitrile (AN) using Alg@Ag nanoparticles (Alg@Ag NPs). Various analytical techniques, including FTIR, XRD, SEM, TEM, UV–Vis, and DSC, were employed to determine bonding interactions and chemical characteristics of the nanocatalyst. [...] Read more.
Herein, we report PAN-g-Alg@Ag-based nanocatalysts synthesis via in situ oxidative free-radical polymerization of acrylonitrile (AN) using Alg@Ag nanoparticles (Alg@Ag NPs). Various analytical techniques, including FTIR, XRD, SEM, TEM, UV–Vis, and DSC, were employed to determine bonding interactions and chemical characteristics of the nanocatalyst. The optimized response surface methodology coupled central composite design (RSM–CCD) reaction conditions were a 35-min irradiation time in a 70-mg L−1 2,4-dinitrophenol (DNP) solution at pH of 4.68. Here, DNP degradation was 99.46% at a desirability of 1.00. The pseudo-first-order rate constant (K1) values were 0.047, 0.050, 0.054, 0.056, 0.059, and 0.064 min−1 with associated half-life (t1/2) values of 14.74, 13.86, 12.84, 12.38, 11.74, 10.82, and 10.04 min that corresponded to DNP concentrations of 10, 20, 30, 40, 50, 60, and 70 mg L−1, respectively, in the presence of PAN-g-Alg@Ag (0.03 g). The results indicate that the reaction followed the pseudo-first-order kinetic model with an R2 value of 0.99. The combined absorption properties of PAN and Alg@Ag NPs on copolymerization on the surface contributed more charge density to surface plasmon resonance (SPR) in a way to degrade more and more molecules of DNP together with preventing the recombination of electron and hole pairs within the photocatalytic process. Full article
(This article belongs to the Section Polymer Chemistry)
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16 pages, 4963 KiB  
Article
Structural Optimization through Biomimetic-Inspired Material-Specific Application of Plant-Based Natural Fiber-Reinforced Polymer Composites (NFRP) for Future Sustainable Lightweight Architecture
by Timo Sippach, Hanaa Dahy, Kai Uhlig, Benjamin Grisin, Stefan Carosella and Peter Middendorf
Polymers 2020, 12(12), 3048; https://doi.org/10.3390/polym12123048 - 19 Dec 2020
Cited by 24 | Viewed by 5177
Abstract
Under normal conditions, the cross-sections of reinforced concrete in classic skeleton construction systems are often only partially loaded. This contributes to non-sustainable construction solutions due to an excess of material use. Novel cross-disciplinary workflows linking architects, engineers, material scientists and manufacturers could offer [...] Read more.
Under normal conditions, the cross-sections of reinforced concrete in classic skeleton construction systems are often only partially loaded. This contributes to non-sustainable construction solutions due to an excess of material use. Novel cross-disciplinary workflows linking architects, engineers, material scientists and manufacturers could offer alternative means for more sustainable architectural applications with extra lightweight solutions. Through material-specific use of plant-based Natural Fiber-Reinforced Polymer Composites (NFRP), also named Biocomposites, a high-performance lightweight structure with topology optimized cross-sections has been here developed. The closed life cycle of NFRPs promotes sustainability in construction through energy recovery of the quickly generative biomass-based materials. The cooperative design resulted in a development that were verified through a 1:10 demonstrator, whose fibrous morphology was defined by biomimetically-inspired orthotropic tectonics, generated with by the fiber path optimization software tools, namely EdoStructure and EdoPath in combination with the appliance of the digital additive manufacturing technique: Tailored Fiber Placement (TFP). Full article
(This article belongs to the Special Issue Functional Polymer Composites)
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13 pages, 3341 KiB  
Article
Electrical Conductivity Based Ammonia Sensing Properties of Polypyrrole/MoS2 Nanocomposite
by Sharique Ahmad, Imran Khan, Ahmad Husain, Anish Khan and Abdullah M. Asiri
Polymers 2020, 12(12), 3047; https://doi.org/10.3390/polym12123047 - 18 Dec 2020
Cited by 84 | Viewed by 4376
Abstract
Polypyrrole (PPy) and Polypyrrole/MoS2 (PPy/MoS2) nanocomposites were successfully prepared, characterized and studied for ammonia sensing properties. The as-prepared PPy and PPy/MoS2 nanocomposites were confirmed by FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), SEM (scanning electron microscopy) and TEM [...] Read more.
Polypyrrole (PPy) and Polypyrrole/MoS2 (PPy/MoS2) nanocomposites were successfully prepared, characterized and studied for ammonia sensing properties. The as-prepared PPy and PPy/MoS2 nanocomposites were confirmed by FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), SEM (scanning electron microscopy) and TEM (transmission electron microscopy) techniques. The ammonia sensing properties of PPy and PPy/MoS2 nanocomposites were studied in terms of change in DC electrical conductivity on exposure to ammonia vapors followed by ambient air at room temperature. It was observed that the incorporation of MoS2 in PPy showed high sensitivity, significant stability and excellent reversibility. The enhanced sensing properties of PPy/MoS2 nanocomposites could be attributed to comparatively high surface area, appropriate sensing channels and efficiently available active sites. The sensing mechanism is explained on the basis of simple acid-base chemistry of polypyrrole. Full article
(This article belongs to the Special Issue Conducting Polymer-Based Hybrid Nanomaterials)
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21 pages, 5281 KiB  
Article
New Insight into the Mechanism of Drug Release from Poly(d,l-lactide) Film by Electron Paramagnetic Resonance
by Natalia A. Chumakova, Elena N. Golubeva, Sergei V. Kuzin, Tatiana A. Ivanova, Igor A. Grigoriev, Sergey V. Kostjuk and Mikhail Ya. Melnikov
Polymers 2020, 12(12), 3046; https://doi.org/10.3390/polym12123046 - 18 Dec 2020
Cited by 10 | Viewed by 2988
Abstract
A novel approach based on convolution of the electron paramagnetic resonance (EPR) spectra was used for quantitative study of the release kinetics of paramagnetic dopants from poly(d,l-lactide) films. A non-monotonic dependence of the release rate on time was reliably [...] Read more.
A novel approach based on convolution of the electron paramagnetic resonance (EPR) spectra was used for quantitative study of the release kinetics of paramagnetic dopants from poly(d,l-lactide) films. A non-monotonic dependence of the release rate on time was reliably recorded. The release regularities were compared with the dynamics of polymer structure changes determined by EPR, SEM, and optic microscopy. The data obtained allow for the conclusion that the main factor governing dopant release is the formation of pores connected with the surface. In contrast, the contribution of the dopant diffusion through the polymer matrix is negligible. The dopant release can be divided into two phases: release through surface pores, which are partially closed with time, and release through pores initially formed inside the polymer matrix due to autocatalytic hydrolysis of the polymer and gradually connected to the surface of the sample. For some time, these processes co-occur. The mathematical model of the release kinetics based on pore formation is presented, describing the kinetics of release of various dopants from the polymer films of different thicknesses. Full article
(This article belongs to the Special Issue Bioactive Polymer Scaffolds and Thin Films for Biomedical Applications: State-of-the-Art and Challenges)
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12 pages, 2685 KiB  
Article
The Potential of Polyethylene Terephthalate Glycol as Biomaterial for Bone Tissue Engineering
by Mohamed H. Hassan, Abdalla M. Omar, Evangelos Daskalakis, Yanhao Hou, Boyang Huang, Ilya Strashnov, Bruce D. Grieve and Paulo Bártolo
Polymers 2020, 12(12), 3045; https://doi.org/10.3390/polym12123045 - 18 Dec 2020
Cited by 45 | Viewed by 4990
Abstract
The search for materials with improved mechanical and biological properties is a major challenge in tissue engineering. This paper investigates, for the first time, the use of Polyethylene Terephthalate Glycol (PETG), a glycol-modified class of Polyethylene Terephthalate (PET), as a potential material for [...] Read more.
The search for materials with improved mechanical and biological properties is a major challenge in tissue engineering. This paper investigates, for the first time, the use of Polyethylene Terephthalate Glycol (PETG), a glycol-modified class of Polyethylene Terephthalate (PET), as a potential material for the fabrication of bone scaffolds. PETG scaffolds with a 0/90 lay-dawn pattern and different pore sizes (300, 350 and 450 µm) were produced using a filament-based extrusion additive manufacturing system and mechanically and biologically characterized. The performance of PETG scaffolds with 300 µm of pore size was compared with polycaprolactone (PCL). Results show that PETG scaffolds present significantly higher mechanical properties than PCL scaffolds, providing a biomechanical environment that promotes high cell attachment and proliferation. Full article
(This article belongs to the Special Issue 3D Bioprinting and Medical Applications)
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13 pages, 2811 KiB  
Article
Polyethylene Glycol 35 (PEG35) Modulates Exosomal Uptake and Function
by Ana Ferrero-Andrés, Daniel Closa, Joan Roselló-Catafau and Emma Folch-Puy
Polymers 2020, 12(12), 3044; https://doi.org/10.3390/polym12123044 - 18 Dec 2020
Cited by 6 | Viewed by 2678
Abstract
Polyethylene glycols (PEGs) are neutral polymers widely used in biomedical applications due to its hydrophilicity and biocompatibility. Exosomes are small vesicles secreted by nearly all cell types and play an important role in normal and pathological conditions. The purpose of this study was [...] Read more.
Polyethylene glycols (PEGs) are neutral polymers widely used in biomedical applications due to its hydrophilicity and biocompatibility. Exosomes are small vesicles secreted by nearly all cell types and play an important role in normal and pathological conditions. The purpose of this study was to evaluate the role of a 35-kDa molecular weight PEG (PEG35) on the modulation of exosome-mediated inflammation. Human macrophage-like cells THP-1, epithelial BICR-18, and CAPAN-2 cells were exposed to PEG35 prior to incubation with exosomes of different cellular origins. Exosome internalization was evaluated by confocal microscopy and flow cytometry. In another set of experiments, macrophages were treated with increasing concentrations of PEG35 prior to exposure with the appropriate stimuli: lipopolysaccharide, BICR-18-derived exosomes, or exosomes from acute pancreatitis-induced rats. Nuclear Factor Kappa B (NFκB) and Signal transducer and activator of transcription 3 (STAT3) activation and the expression levels of pro-inflammatory Interleukin 1β (IL1β) were determined. PEG35 administration significantly enhanced the internalization of exosomes in both macrophages and epithelial cells. Further, PEG35 ameliorated the inflammatory response induced by acute pancreatitis-derived exosomes by reducing the expression of IL1β and p65 nuclear translocation. Our results revealed that PEG35 promotes the cellular uptake of exosomes and modulates the pro-inflammatory effect of acute pancreatitis-derived vesicles through inhibition of NFκB, thus emphasizing the potential value of PEG35 as an anti-inflammatory agent for biomedical purposes. Full article
(This article belongs to the Section Polymer Applications)
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13 pages, 3689 KiB  
Article
Dope-Dyeing of Polyvinyl Alcohol (PVA) Nanofibres with Remazol Yellow FG
by Fatirah Fadil, Farah Atiqah Adli, Nor Dalila Nor Affandi, Ahmad Mukifza Harun and Mohammad Khursheed Alam
Polymers 2020, 12(12), 3043; https://doi.org/10.3390/polym12123043 - 18 Dec 2020
Cited by 15 | Viewed by 3864
Abstract
The lack of aesthetic properties of electrospun nanofibres in terms of colour appearance is the drive in this preliminary study. This research is conducted to study the dyeing behaviour and colorimetric properties of electrospun nanofibres blended with Remazol Yellow FG reactive dye using [...] Read more.
The lack of aesthetic properties of electrospun nanofibres in terms of colour appearance is the drive in this preliminary study. This research is conducted to study the dyeing behaviour and colorimetric properties of electrospun nanofibres blended with Remazol Yellow FG reactive dye using dope-dyeing method via electrospinning process. This paper reports the colorimetric properties of dyed poly vinyl alcohol (PVA) nanofibres within the range of 2.5 wt.% to 12.5 wt.% dye content. The electrospinning parameters were fixed at the electrospinning distance of 10 cm, constant feed rate of 0.5 mL/h and applied voltage of 15 kV. The resulting impregnated dye of 10 wt.% exhibits acceptable colour difference of dyed PVA nanofibres, with a mean fibre diameter of 177.1 ± 11.5 nm. The SEM micrographs show the effect of dye content on morphology and fibre diameter upon the increment of dye used. Further increase of dye content adversely affects the jet stability during the electrospinning, resulting in macroscopic dropping phenomenon. The presence of all prominent peaks of Remazol dye in the PVA nanofibers was supported with FTIR analysis. The addition of dye into the nanofibres has resulted in the enhancement of thermal stability of the PVA as demonstrated by TGA analysis. Full article
(This article belongs to the Special Issue Polymeric Synthetic Fibres)
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