Polymers

24 pages, 2307 KiB

Open AccessArticle

Anisotropy and Mechanical Properties of Nanoclay Filled, Medium-Density Rigid Polyurethane Foams Produced in a Sealed Mold, from Renewable Resources

by Ilze Beverte, Ugis Cabulis, Janis Andersons, Mikelis Kirpluks, Vilis Skruls and Peteris Cabulis

Polymers 2023, 15(11), 2582; https://doi.org/10.3390/polym15112582 - 05 Jun 2023

Cited by 2 | Viewed by 1258

Abstract

Medium-density rigid polyurethane (PU) foams are often produced in sealed molds; therefore, the processes inside the mold and structure of the produced foam blocks need to be understood. The structural and mechanical anisotropy is shown to be the third variable along with (1) [...] Read more.

Medium-density rigid polyurethane (PU) foams are often produced in sealed molds; therefore, the processes inside the mold and structure of the produced foam blocks need to be understood. The structural and mechanical anisotropy is shown to be the third variable along with (1) concentration of the nanoclay filler and (2) density, to determine the mechanical properties of the filled PU foam composites produced in a sealed mold. The varying anisotropy of the specimens hinders the accurate evaluation of the filling effect. The methodology for the estimation of the anisotropy characteristics of specimens from different locations within the nanoclay filled PU foam blocks is elaborated. A criterion, based on analysis of Poisson’s ratios, is formulated for the selection of specimens with similar anisotropy characteristics. The shear and bulk moduli are estimated theoretically, dependent on the filler’s concentration, using the experimentally determined constants. Full article

(This article belongs to the Special Issue Polymeric Porous Materials: Synthesis, Characterization and Application)

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15 pages, 5218 KiB

Open AccessArticle

Electrical and Mechanical Characterisation of Poly(ethylene)oxide-Polysulfone Blend for Composite Structural Lithium Batteries

by Francesco Gucci, Marzio Grasso, Stefano Russo, Glenn J. T. Leighton, Christopher Shaw and James Brighton

Polymers 2023, 15(11), 2581; https://doi.org/10.3390/polym15112581 - 05 Jun 2023

Viewed by 1627

Abstract

In this work, a blend of PEO, polysulfone (PSF), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) was prepared at different PEO–PSf weight ratios (70-30, 80-20, and 90-10) and ethylene oxide to lithium (EO/Li) ratios (16/1, 20/1, 30/1, and 50/1). The samples were characterised using FT-IR, DSC, [...] Read more.

In this work, a blend of PEO, polysulfone (PSF), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) was prepared at different PEO–PSf weight ratios (70-30, 80-20, and 90-10) and ethylene oxide to lithium (EO/Li) ratios (16/1, 20/1, 30/1, and 50/1). The samples were characterised using FT-IR, DSC, and XRD. Young’s modulus and tensile strength were evaluated at room temperature with micro-tensile testing. The ionic conductivity was measured between 5 °C and 45 °C through electrochemical impedance spectroscopy (EIS). The samples with a ratio of PEO and PSf equal to 70-30 and EO/Li ratio equal to 16/1 have the highest conductivity (1.91 × 10⁻⁴ S/cm) at 25 °C, while the PEO–PSf 80-20 EO/Li = 50/1 have the highest averaged Young’s modulus of about 1.5 GPa at 25 °C. The configuration with a good balance between electrical and mechanical properties is the PEO–PSf 70-30 EO/Li = 30/1, which has a conductivity of 1.17 × 10⁻⁴ S/cm and a Young’s modulus of 800 MPa, both measured at 25 °C. It was also found that increasing the EO/Li ratio to 16/1 dramatically affects the mechanical properties of the samples with them showing extreme embrittlement. Full article

(This article belongs to the Special Issue Polymer Electrolyte: Recent Progress and Applications)

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13 pages, 5694 KiB

Open AccessArticle

Effect of Recycled Polyvinyl Butyral (rPVB) Addition on the Tribological Performance of Glass–Fiber Reinforced Polyamide (PAGF) during Reciprocating Sliding Wear Conditions

by Isabel Ariadna Carmona-Cervantes, Iván Campos-Silva, Ulises Figueroa-López and Andrea Guevara-Morales

Polymers 2023, 15(11), 2580; https://doi.org/10.3390/polym15112580 - 05 Jun 2023

Cited by 1 | Viewed by 1106

Abstract

Plastic recycling in the automotive industry is a priority. In this study, the effect of adding recycled polyvinyl butyral (rPVB) from automotive windshields on the coefficient of friction (CoF) and specific wear rate (k) of a glass–fiber reinforced polyamide (PAGF) is [...] Read more.

Plastic recycling in the automotive industry is a priority. In this study, the effect of adding recycled polyvinyl butyral (rPVB) from automotive windshields on the coefficient of friction (CoF) and specific wear rate (k) of a glass–fiber reinforced polyamide (PAGF) is investigated. It was found that, at 15 and 20 wt.% of rPVB, it acts as a solid lubricant, reducing CoF and k up to 27% and 70%, respectively. Microscopical analysis of the wear tracks showed that rPVB spreads over the worn tracks, forming a lubricant layer, which protects the fibers from damage. However, at lower rPVB content, fiber damage cannot be prevented as the protective lubricant layer is not formed. Full article

(This article belongs to the Special Issue Advances in Tribology of Polymer Composites)

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17 pages, 39250 KiB

Open AccessArticle

Polyacrylonitrile Fibers with a Gradient Silica Distribution as Precursors of Carbon-Silicon-Carbide Fibers

by Lydia A. Varfolomeeva, Ivan Yu. Skvortsov, Ivan S. Levin, Georgiy A. Shandryuk, Timofey D. Patsaev and Valery G. Kulichikhin

Polymers 2023, 15(11), 2579; https://doi.org/10.3390/polym15112579 - 05 Jun 2023

Viewed by 1389

Abstract

This study presents preparing and characterization of polyacrylonitrile (PAN) fibers containing various content of tetraethoxysilane (TEOS) incorporated via mutual spinning solution or emulsion using wet and mechanotropic spinning methods. It was shown that the presence of TEOS in dopes does not affect their [...] Read more.

This study presents preparing and characterization of polyacrylonitrile (PAN) fibers containing various content of tetraethoxysilane (TEOS) incorporated via mutual spinning solution or emulsion using wet and mechanotropic spinning methods. It was shown that the presence of TEOS in dopes does not affect their rheological properties. The coagulation kinetics of complex PAN solution was investigated by optical methods on the solution drop. It was shown that during the interdiffusion process phase separation occurs and TEOS droplets form and move in the middle of the dope’s drop. Mechanotropic spinning induces the TEOS droplets to move to the fiber periphery. The morphology and structure of the fibers obtained were investigated by scanning and transmission electron microscopy, as well as X-ray diffraction methods. It was shown that during fiber spinning stages the transformation of the TEOS drops into solid silica particles takes place as a result of hydrolytic polycondensation. This process can be characterized as the sol-gel synthesis. The formation of nano-sized (3–30 nm) silica particles proceeds without particles aggregation, but in a mode of the distribution gradient along the fiber cross-section leading to the accumulation of the silica particles either in the fiber center (wet spinning) or in the fiber periphery (mechanotropic spinning). The prepared composite fibers were carbonized and according to XRD analysis of carbon fibers, the clear peaks corresponding to SiC were observed. These findings indicate the useful role of TEOS as a precursor agent for both, silica in PAN fibers and silicon carbide in carbon fibers that has potential applications in some advanced materials with high thermal properties. Full article

(This article belongs to the Special Issue Structural Rheology of Polymer Melts, Solutions and Compositions on Their Base II)

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18 pages, 5050 KiB

Open AccessArticle

Proposal and Numerical Analysis of Organic/Sb₂Se₃ All-Thin-Film Tandem Solar Cell

by Tarek I. Alanazi, Abdulaziz Alanazi, Ezzeddine Touti, Ahmed M. Agwa, Habib Kraiem, Mohana Alanazi, Abdulrahman M. Alanazi and Mona El Sabbagh

Polymers 2023, 15(11), 2578; https://doi.org/10.3390/polym15112578 - 05 Jun 2023

Cited by 2 | Viewed by 1318

Abstract

The low bandgap antimony selenide (Sb₂Se₃) and wide bandgap organic solar cell (OSC) can be considered suitable bottom and top subcells for use in tandem solar cells. Some properties of these complementary candidates are their non-toxicity and cost-affordability. In [...] Read more.

The low bandgap antimony selenide (Sb₂Se₃) and wide bandgap organic solar cell (OSC) can be considered suitable bottom and top subcells for use in tandem solar cells. Some properties of these complementary candidates are their non-toxicity and cost-affordability. In this current simulation study, a two-terminal organic/Sb₂Se₃ thin-film tandem is proposed and designed through TCAD device simulations. To validate the device simulator platform, two solar cells were selected for tandem design, and their experimental data were chosen for calibrating the models and parameters utilized in the simulations. The initial OSC has an active blend layer, whose optical bandgap is 1.72 eV, while the initial Sb₂Se₃ cell has a bandgap energy of 1.23 eV. The structures of the initial standalone top and bottom cells are ITO/PEDOT:PSS/DR3TSBDT:PC₇₁BM/PFN/Al, and FTO/CdS/Sb₂Se₃/Spiro-OMeTAD/Au, while the recorded efficiencies of these individual cells are about 9.45% and 7.89%, respectively. The selected OSC employs polymer-based carrier transport layers, specifically PEDOT:PSS, an inherently conductive polymer, as an HTL, and PFN, a semiconducting polymer, as an ETL. The simulation is performed on the connected initial cells for two cases. The first case is for inverted (p-i-n)/(p-i-n) cells and the second is for the conventional (n-i-p)/(n-i-p) configuration. Both tandems are investigated in terms of the most important layer materials and parameters. After designing the current matching condition, the tandem PCEs are boosted to 21.52% and 19.14% for the inverted and conventional tandem cells, respectively. All TCAD device simulations are made by employing the Atlas device simulator given an illumination of AM1.5G (100 mW/cm²). This present study can offer design principles and valuable suggestions for eco-friendly solar cells made entirely of thin films, which can achieve flexibility for prospective use in wearable electronics. Full article

(This article belongs to the Special Issue Polymers for Electronics and Energy Devices)

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12 pages, 7267 KiB

Open AccessArticle

Improving Surface Wear Resistance of Polyimide by Inserting KH550 Grafted GO

by Chen Liu, Jingfu Song, Gai Zhao and Qingjun Ding

Polymers 2023, 15(11), 2577; https://doi.org/10.3390/polym15112577 - 04 Jun 2023

Viewed by 1332

Abstract

To improve the wear resistance of polyimide (PI), surface modification was developed. In this study, the tribological properties of graphene (GN), graphene oxide (GO), and KH550-grafted graphene oxide (K5-GO) modified PI were evaluated by molecular dynamics (MD) at the atomic level. The findings [...] Read more.

To improve the wear resistance of polyimide (PI), surface modification was developed. In this study, the tribological properties of graphene (GN), graphene oxide (GO), and KH550-grafted graphene oxide (K5-GO) modified PI were evaluated by molecular dynamics (MD) at the atomic level. The findings indicated that the addition of nanomaterials can significantly enhance the friction performance of PI. The friction coefficient of PI composites decreased from 0.253 to 0.232, 0.136, and 0.079 after coating GN, GO and K5-GO, respectively. Among them, the K5-GO/PI exhibited the best surface wear resistance. Importantly, the mechanism behind the modification of PI was thoroughly revealed by observing the wear state, analyzing the changes of interfacial interactions, interfacial temperature, and relative concentration. Full article

(This article belongs to the Special Issue Advances in Tribology of Polymer Composites)

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3 pages, 193 KiB

Open AccessEditorial

Special Issue “State-of-the-Art Polymer Science and Technology in Japan (2021, 2022)”

by Shin-ichi Yusa and Naozumi Teramoto

Polymers 2023, 15(11), 2576; https://doi.org/10.3390/polym15112576 - 04 Jun 2023

Viewed by 990

Abstract

It has been 100 years since the first article on polymerization was published by Hermann Staudinger [...] Full article

(This article belongs to the Section Polymer Chemistry)

16 pages, 6380 KiB

Open AccessArticle

Effect of Functionalized Polyethylene Wax on the Melt Processing and Properties of Highly Filled Magnesium Hydroxide/Linear Low-Density Polyethylene Composites

by Rujie Li, Shiai Xu, Jiajun Xu, Tongtong Pan, Beibei Sun and Li Dang

Polymers 2023, 15(11), 2575; https://doi.org/10.3390/polym15112575 - 04 Jun 2023

Cited by 3 | Viewed by 1420

Abstract

The poor processing and rheological properties of highly filled composites caused by the high loading of fillers can be improved with the use of maleic anhydride grafted polyethylene wax (PEWM) as compatibilizer and lubricant. In this study, two PEWMs with different molecular weights [...] Read more.

The poor processing and rheological properties of highly filled composites caused by the high loading of fillers can be improved with the use of maleic anhydride grafted polyethylene wax (PEWM) as compatibilizer and lubricant. In this study, two PEWMs with different molecular weights were synthesized by melt grafting, and their compositions and grafting degrees were characterized by Fourier transform infrared (FTIR) spectroscopy and acid-base titration. Subsequently, magnesium hydroxide (MH)/linear low-density polyethylene (LLDPE) composites with 60 wt% of MH were prepared using polyethylene wax (PEW) and PEWM, respectively. The equilibrium torque and melt flow index tests indicate that the processability and fluidity of MH/MAPP/LLDPE composites are significantly improved with the addition of PEWM. The addition of PEWM with a lower molecular weight leads to a substantial reduction in viscosity. The mechanical properties are also increased. The limiting oxygen index (LOI) test and cone calorimeter test (CCT) show that both PEW and PEWM have adverse effects on flame retardancy. This study provides a strategy to simultaneously improve the processability and mechanical properties of highly filled composites. Full article

(This article belongs to the Section Polymer Applications)

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19 pages, 5680 KiB

Open AccessArticle

Synthesis and Properties of the Novel High-Performance Hydroxyl-Terminated Liquid Fluoroelastomer

by Donghan Li, Chen Yang, Ping Li, Lu Yu, Shufa Zhao, Long Li, Hailan Kang, Feng Yang and Qinghong Fang

Polymers 2023, 15(11), 2574; https://doi.org/10.3390/polym15112574 - 04 Jun 2023

Viewed by 1477

Abstract

Functional liquid fluoroelastomers are in high demand in new energy fields. And these materials have potential applications in high-performance sealing materials and as electrode materials. In this study, a novel high-performance hydroxyl-terminated liquid fluoroelastomer (t-HTLF) with a high fluorine content, temperature resistance, and [...] Read more.

Functional liquid fluoroelastomers are in high demand in new energy fields. And these materials have potential applications in high-performance sealing materials and as electrode materials. In this study, a novel high-performance hydroxyl-terminated liquid fluoroelastomer (t-HTLF) with a high fluorine content, temperature resistance, and curing efficiency was synthesised from a terpolymer of vinylidene fluoride (VDF), tetrafluoroethylene (TFE), and hexafluoropylene (HFP). A carboxyl-terminated liquid fluoroelastomer (t-CTLF) with controllable molar mass and end-group content was first prepared from a poly(VDF-ter-TFE-ter-HFP) terpolymer using a unique oxidative degradation method. Subsequently, an efficient “one-step” reduction of the carboxyl groups (COOH) in t-CTLF into hydroxyl groups (OH) was achieved via the functional-group conversion method using lithium aluminium hydride (LiAlH₄) as the reductant. Thus, t-HTLF with a controllable molar mass and end-group content and highly active end groups was synthesised. Owing to the efficient curing reaction between OH and isocyanate groups (NCO), the cured t-HTLF exhibits good surface properties, thermal properties, and chemical stability. The thermal decomposition temperature (T_d) of the cured t-HTLF reaches 334 °C, and it exhibits hydrophobicity. The oxidative degradation, reduction, and curing reaction mechanisms were also determined. The effects of solvent dosage, reaction temperature, reaction time, and ratio of the reductant to the COOH content on the carboxyl conversion were also systematically investigated. An efficient reduction system comprising LiAlH₄ can not only achieve an efficient conversion of the COOH groups in t-CTLF to OH groups but also the in situ hydrogenation and addition reactions of residual double bonds (C=C) groups in the chain, such that the thermal stability and terminal activity of the product are improved while maintaining a high fluorine content. Full article

(This article belongs to the Collection Polymers and Polymer Composites: Structure-Property Relationship)

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20 pages, 8128 KiB

Open AccessArticle

Organophosphorus Reinforced Poly(vinyl alcohol) Nanocomposites Doped with Silver-Loaded Zeolite L Nanoparticles as Sustainable Materials for Packaging Applications

by Tăchiță Vlad-Bubulac, Corneliu Hamciuc, Diana Serbezeanu, Dana Mihaela Suflet, Daniela Rusu, Gabriela Lisa, Ion Anghel, Dana-Maria Preda, Totka Todorova and Cristina Mihaela Rîmbu

Polymers 2023, 15(11), 2573; https://doi.org/10.3390/polym15112573 - 04 Jun 2023

Cited by 2 | Viewed by 1272

Abstract

The sustainable development of innovative eco-friendly multifunctional nanocomposites, possessing superior characteristics, is a noteworthy topic. Novel semi-interpenetrated nanocomposite films based on poly(vinyl alcohol) covalently and thermally crosslinked with oxalic acid (OA), reinforced with a novel organophosphorus flame retardant (PFR-4) derived from co-polycondensation in [...] Read more.

The sustainable development of innovative eco-friendly multifunctional nanocomposites, possessing superior characteristics, is a noteworthy topic. Novel semi-interpenetrated nanocomposite films based on poly(vinyl alcohol) covalently and thermally crosslinked with oxalic acid (OA), reinforced with a novel organophosphorus flame retardant (PFR-4) derived from co-polycondensation in solution reaction of equimolar amounts of co-monomers, namely, bis((6-oxido-6H-dibenz[c,e][1,2]oxaphosphorinyl)-(4-hydroxyaniline)-methylene)-1,4-phenylene, bisphenol S, and phenylphosphonic dichloride, in a molar ratio of 1:1:2, and additionally doped with silver-loaded zeolite L nanoparticles (ze-Ag), have been prepared by casting from solution technique. The morphology of the as prepared PVA-oxalic acid films and their semi-interpenetrated nanocomposites with PFR-4 and ze-Ag was investigated by scanning electron microscopy (SEM), while the homogeneous distribution of the organophosphorus compound and nanoparticles within the nanocomposite films has been introspected by means of energy dispersive X-ray spectroscopy (EDX). It was established that composites with a very low phosphorus content had noticeably improved flame retardancy. The peak of the heat release rate was reduced up to 55%, depending on the content of the flame-retardant additive and the doping ze-Ag nanoparticles introduced into the PVA/OA matrix. The ultimate tensile strength and elastic modulus increased significantly in the reinforced nanocomposites. Considerably increased antimicrobial activity was revealed in the case of the samples containing silver-loaded zeolite L nanoparticles. Full article

(This article belongs to the Special Issue Layered Materials-Polymer Based Fire Retardant Composites)

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13 pages, 6167 KiB

Open AccessArticle

3D-Printable PLA/Mg Composite Filaments for Potential Bone Tissue Engineering Applications

by Sumama Nuthana Kalva, Fawad Ali, Carlos A. Velasquez and Muammer Koç

Polymers 2023, 15(11), 2572; https://doi.org/10.3390/polym15112572 - 03 Jun 2023

Cited by 8 | Viewed by 1710

Abstract

Magnesium (Mg) is a promising material for bone tissue engineering applications due to it having similar mechanical properties to bones, biocompatibility, and biodegradability. The primary goal of this study is to investigate the potential of using solvent-casted polylactic acid (PLA) loaded Mg (WE43) [...] Read more.

Magnesium (Mg) is a promising material for bone tissue engineering applications due to it having similar mechanical properties to bones, biocompatibility, and biodegradability. The primary goal of this study is to investigate the potential of using solvent-casted polylactic acid (PLA) loaded Mg (WE43) composites as filament feedstock for fused deposition modeling (FDM) 3D Printing. Four PLA/Magnesium (WE43) compositions (5, 10, 15, 20 wt%) are synthesized and produced into filaments, then used to print test samples on an FDM 3D printer. Assessments are made on how Mg incorporation affected PLA’s thermal, physicochemical, and printability characteristics. The SEM study of the films shows that the Mg particles are uniformly distributed in all the compositions. The FTIR results indicate that the Mg particles blend well with the polymer matrix and there is no chemical reaction between the PLA and the Mg particles during the blending process. The thermal studies show that the addition of Mg leads to a small increase in the melting peak reaching a maximum of 172.8 °C for 20% Mg samples. However, there are no dramatic variations in the degree of crystallinity among the Mg-loaded samples. The filament cross-section images show that the distribution of Mg particles is uniform up to a concentration of 15% Mg. Beyond that, non-uniform distribution and an increase in pores in the vicinity of the Mg particles is shown to affect their printability. Overall, 5% and 10% Mg composite filaments were printable and have the potential to be used as composite biomaterials for 3D-printed bone implants. Full article

(This article belongs to the Special Issue New Development in Additive Manufacturing of Polymers)

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15 pages, 3521 KiB

Open AccessArticle

Stimulation of Chondrocyte and Bone Marrow Mesenchymal Stem Cell Chondrogenic Response by Polypyrrole and Polypyrrole/Gold Nanoparticles

by Ilona Uzieliene, Anton Popov, Viktorija Lisyte, Gabija Kugaudaite, Paulina Bialaglovyte, Raminta Vaiciuleviciute, Giedrius Kvederas, Eiva Bernotiene and Almira Ramanaviciene

Polymers 2023, 15(11), 2571; https://doi.org/10.3390/polym15112571 - 03 Jun 2023

Cited by 1 | Viewed by 1693

Abstract

Bone marrow mesenchymal stem cells (BMMSCs) possess a strong ability to differentiate into the chondrogenic lineage, which is important for cartilage regeneration. External stimuli, such as electrical stimulation (ES), are frequently studied for chondrogenic differentiation of BMMSCs; however, the application of conductive polymers [...] Read more.

Bone marrow mesenchymal stem cells (BMMSCs) possess a strong ability to differentiate into the chondrogenic lineage, which is important for cartilage regeneration. External stimuli, such as electrical stimulation (ES), are frequently studied for chondrogenic differentiation of BMMSCs; however, the application of conductive polymers such as polypyrrole (Ppy), has never been used for stimulating BMMSCs chondrogenesis in vitro before. Thus, the aim of this study was to evaluate the chondrogenic potential of human BMMSCs after stimulation with Ppy nanoparticles (Ppy NPs) and compare them to cartilage-derived chondrocytes. In this study, we tested Ppy NPs without and with 13 nm gold NPs (Ppy/Au) for BMMSCs and chondrocyte proliferation, viability, and chondrogenic differentiation for 21 days, without the use of ES. The results demonstrated significantly higher amounts of cartilage oligomeric matrix protein (COMP) in BMMSCs stimulated with Ppy and Ppy/Au NPs, as compared to the control. The expression of chondrogenic genes (SOX9, ACAN, COL2A1) in BMMSCs and chondrocytes were upregulated by Ppy and Ppy/Au NPs, as compared to controls. Histological staining with safranin-O indicated higher extracellular matrix production in Ppy and Ppy/Au NPs stimulated samples, as compared to controls. In conclusion, Ppy and Ppy/Au NPs stimulate BMMSC chondrogenic differentiation; however, BMMSCs were more responsive to Ppy, while chondrocytes possessed a stronger chondrogenic response to Ppy/Au NPs. Full article

(This article belongs to the Special Issue Progress in the Formation of Polymer-Based Nanomaterials for New Applications)

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13 pages, 5099 KiB

Open AccessArticle

Zn(II)-Based Mixed-Ligand-Bearing Coordination Polymers as Multi-Responsive Fluorescent Sensors for Detecting Dichromate, Iodide, Nitenpyram, and Imidacloprid

by Dan Wang, Lin-Huan Du, Long Li, Yu-Meng Wei, Tao Wang, Jun Cheng, Bin Du, Yi Jia and Bao-Yi Yu

Polymers 2023, 15(11), 2570; https://doi.org/10.3390/polym15112570 - 02 Jun 2023

Cited by 2 | Viewed by 1147

Abstract

Coordination polymers (CPs) are organo-inorganic porous materials consisting of metal ions or clusters and organic linkers. These compounds have attracted attention for use in the fluorescence detection of pollutants. Here, two Zn-based mixed-ligand-bearing CPs, [Zn₂(DIN)₂(HBTC²⁻)₂] [...] Read more.

Coordination polymers (CPs) are organo-inorganic porous materials consisting of metal ions or clusters and organic linkers. These compounds have attracted attention for use in the fluorescence detection of pollutants. Here, two Zn-based mixed-ligand-bearing CPs, [Zn₂(DIN)₂(HBTC²⁻)₂] (CP-1) and [Zn(DIN)(HBTC²⁻)]·ACN·H₂O (CP-2) (DIN = 1,4-di(imidazole-1-yl)naphthalene, H₃BTC = 1,3,5-benzenetricarboxylic acid, and ACN = acetonitrile), were synthesized under solvothermal conditions. CP-1 and CP-2 were characterized by single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, and powder X-ray diffraction analysis. Solid-state fluorescence analysis revealed an emission peak at 350 nm upon excitation at 225 and 290 nm. Fluorescence sensing tests showed that CP-1 was highly efficient, sensitive, and selective for detecting Cr₂O₇²⁻ at 225 and 290 nm, whereas I⁻ was only detected well at an excitation of 225 nm. CP-1 detected pesticides differently at excitation wavelengths of 225 and 290 nm; the highest quenching rates were for nitenpyram at 225 nm and imidacloprid at 290 nm. The quenching process may occur via the inner filter effect and fluorescence resonance energy transfer. Full article

(This article belongs to the Section Polymer Applications)

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13 pages, 2123 KiB

Open AccessArticle

Characterization of Synthetic Polymer Coated with Biopolymer Layer with Natural Orange Peel Extract Aimed for Food Packaging

by Domagoj Gabrić, Mia Kurek, Mario Ščetar, Mladen Brnčić and Kata Galić

Polymers 2023, 15(11), 2569; https://doi.org/10.3390/polym15112569 - 02 Jun 2023

Cited by 1 | Viewed by 1625

Abstract

This research was aimed to make biolayer coatings enriched with orange peel essential oil (OPEO) on synthetic laminate, oriented poly(ethylene-terephthalate)/polypropylene (PET-O/PP). Coating materials were taken from biobased and renewable waste sources, and the developed formulation was targeted for food packaging. The developed materials [...] Read more.

This research was aimed to make biolayer coatings enriched with orange peel essential oil (OPEO) on synthetic laminate, oriented poly(ethylene-terephthalate)/polypropylene (PET-O/PP). Coating materials were taken from biobased and renewable waste sources, and the developed formulation was targeted for food packaging. The developed materials were characterized for their barrier (O₂, CO₂, and water vapour), optical (colour, opacity), surface (inventory of peaks by FTIR), and antimicrobial activity. Furthermore, the overall migration from a base layer (PET-O/PP) in an acetic acid (3% HAc) and ethanol aqueous solution (20% EtOH) were measured. The antimicrobial activity of chitosan (Chi)-coated films was assessed against Escherichia coli. Permeation of the uncoated samples (base layer, PET-O/PP) increased with the temperature increase (from 20 °C to 40 °C and 60 °C). Films with Chi-coatings were a better barrier to gases than the control (PET-O/PP) measured at 20 °C. The addition of 1% (w/v) OPEO to the Chi-coating layer showed a permeance decrease of 67% for CO₂ and 48% for O₂. The overall migrations from PET-O/PP in 3% HAc and 20% EtOH were 1.8 and 2.3 mg/dm², respectively. Analysis of spectral bands did not indicate any surface structural changes after exposure to food simulants. Water vapour transmission rate values were increased for Chi-coated samples compared to the control. The total colour difference showed a slight colour change for all coated samples (ΔE > 2). No significant changes in light transmission at 600 nm for samples containing 1% and 2% OLEO were observed. The addition of 4% (w/v) OPEO was not enough to obtain a bacteriostatic effect, so future research is needed. Full article

(This article belongs to the Special Issue Application of Polymer Materials in the Food Packaging)

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14 pages, 5995 KiB

Open AccessArticle

Stability Studies, Biodegradation Tests, and Mechanical Properties of Sodium Alginate and Gellan Gum Beads Containing Surfactant

by Natalia Stachowiak, Jolanta Kowalonek, Justyna Kozlowska and Aleksandra Burkowska-But

Polymers 2023, 15(11), 2568; https://doi.org/10.3390/polym15112568 - 02 Jun 2023

Cited by 1 | Viewed by 1890

Abstract

The excessive presence of single-use plastics is rapidly degrading our natural environment on a global scale due to their inherent resistance to decomposition. Wet wipes used for personal or household purposes contribute significantly to the accumulation of plastic waste. One potential solution to [...] Read more.

The excessive presence of single-use plastics is rapidly degrading our natural environment on a global scale due to their inherent resistance to decomposition. Wet wipes used for personal or household purposes contribute significantly to the accumulation of plastic waste. One potential solution to address this problem involves developing eco-friendly materials that possess the ability to degrade naturally while retaining their washing capabilities. For this purpose, the beads from sodium alginate, gellan gum, and a mixture of these natural polymers containing surfactant were produced using the ionotropic gelation method. Stability studies of the beads by observing their appearance and diameter were performed after incubation in solutions of different pH values. The images showed that macroparticles were reduced in size in an acidic medium and swelled in solution of pH-neutral phosphate-buffered saline. Moreover, all the beads first swelled and then degraded in alkaline conditions. The beads based on gellan gum and combining both polymers were the least sensitive to pH changes. The compression tests revealed that the stiffness of all macroparticles decreased with the increasing pH of the solutions in which they were immersed. The studied beads were more rigid in an acidic solution than in alkaline conditions. The biodegradation of macroparticles was assessed using a respirometric method in soil and seawater. It is important to note that the macroparticles degraded more rapidly in soil than in seawater. Full article

(This article belongs to the Special Issue Polymer Microspheres—Current Developments and Future Challenges)

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19 pages, 6972 KiB

Open AccessArticle

Oil Media on Paper: Investigating the Interaction of Cold-Pressed Linseed Oil with Paper Supports with FTIR Analysis

by Penelope Banou, Stamatis Boyatzis, Konstantinos Choulis, Charis Theodorakopoulos and Athena Alexopoulou

Polymers 2023, 15(11), 2567; https://doi.org/10.3390/polym15112567 - 02 Jun 2023

Cited by 1 | Viewed by 1517

Abstract

Previous works of the authors have presented the changes in the optical, mechanical, and chemical properties of the oiled areas of the supports that occur upon ageing due to oil-binder absorption in works of art on paper and printed material. In this framework, [...] Read more.

Previous works of the authors have presented the changes in the optical, mechanical, and chemical properties of the oiled areas of the supports that occur upon ageing due to oil-binder absorption in works of art on paper and printed material. In this framework, transmittance FTIR analysis has indicated that the presence of linseed oil induces the conditions to promote the deterioration of the oil-impregnated areas of the paper supports. However, the analysis of oil-impregnated mock-ups did not provide detailed information about the input of linseed oil formulations and the different types of paper support on the chemical changes that occur upon ageing. This work presents the results of ATR-FTIR and reflectance FTIR, which were used for compensating the previous results, proving indications on the effect of different materials (linseed oil formulations, and cellulosic and lignocellulosic papers) on the development of chemical changes, thus, on the condition of the oiled areas upon ageing. Although linseed oil formulations have a determining effect on the condition of the oiled areas of the support, the paper pulp content appears to have an input to the chemical changes that occur in the system of paper–linseed oil upon ageing. The results presented are more focused on the oil-impregnated mock-ups with cold-pressed linseed oil since results have indicated that this causes more extended changes upon ageing. Full article

(This article belongs to the Special Issue Advances in Cellulose-Based Polymers and Composites)

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18 pages, 3471 KiB

Open AccessArticle

Elastocaloric Waste/Natural Rubber Materials with Various Crosslink Densities

by Nicolas Candau, Adele Zimny, Eduard Vives and Maria Lluïsa Maspoch

Polymers 2023, 15(11), 2566; https://doi.org/10.3390/polym15112566 - 02 Jun 2023

Cited by 1 | Viewed by 1410

Abstract

The characterization of the mechanical behavior of elastocaloric materials is essential to identify their viability in heating/cooling devices. Natural rubber (NR) is a promising elastocaloric (eC) polymer as it requires low external stress to induce a wide temperature span, ΔT. Nonetheless, solutions are [...] Read more.

The characterization of the mechanical behavior of elastocaloric materials is essential to identify their viability in heating/cooling devices. Natural rubber (NR) is a promising elastocaloric (eC) polymer as it requires low external stress to induce a wide temperature span, ΔT. Nonetheless, solutions are needed to further improve DT, especially when targeting cooling applications. To this aim, we designed NR-based materials and optimized the specimen thickness, the density of their chemical crosslinks, and the quantity of ground tire rubber (GTR) used as reinforcing fillers. The eC properties under a single and cyclic loading conditions of the resulting vulcanized rubber composites were investigated via the measure of the heat exchange at the specimen surface using infrared thermography. The highest eC performance was found with the specimen geometry with the lowest thickness (0.6 mm) and a GTR content of 30 wt.%. The maximum temperature span under single interrupted cycle and multiple continuous cycles were equal to 12 °C and 4 °C, respectively. These results were assumed to be related to more homogeneous curing in these materials and to a higher crosslink density and GTR content which both act as nucleating elements for the strain-induced crystallization at the origin of the eC effect. This investigation would be of interest for the design of eC rubber-based composites in eco-friendly heating/cooling devices. Full article

(This article belongs to the Special Issue Rubber Reinforced Polymer Composites)

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13 pages, 2927 KiB

Open AccessArticle

Catechol-Based Porous Organic Polymers for Effective Removal of Phenolic Pollutants from Water

by Xiaoxiao Zhao, Yiqiong Liu, Qimeng Zhu and Weitao Gong

Polymers 2023, 15(11), 2565; https://doi.org/10.3390/polym15112565 - 02 Jun 2023

Cited by 3 | Viewed by 1201

Abstract

Phenolic pollutants released from industrial activities seriously damage natural freshwater resources, and their elimination or reduction to safe levels is an urgent challenge. In this study, three catechol-based porous organic polymers, CCPOP, NTPOP, and MCPOP, were prepared using sustainable lignin biomass-derived monomers for [...] Read more.

Phenolic pollutants released from industrial activities seriously damage natural freshwater resources, and their elimination or reduction to safe levels is an urgent challenge. In this study, three catechol-based porous organic polymers, CCPOP, NTPOP, and MCPOP, were prepared using sustainable lignin biomass-derived monomers for the adsorption of phenolic contaminants in water. CCPOP, NTPOP, and MCPOP showed good adsorption performance for 2,4,6-trichlorophenol (TCP) with theoretical maximum adsorption capacities of 808.06 mg/g, 1195.30 mg/g, and 1076.85 mg/g, respectively. In addition, MCPOP maintained a stable adsorption performance after eight consecutive cycles. These results indicate that MCPOP is a potential material for the effective treatment of phenol pollutants in wastewater. Full article

(This article belongs to the Special Issue Porous Organic Polymer Materials: Synthesis, Characterization and Applications)

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19 pages, 3794 KiB

Open AccessReview

Metal and Polymer Based Composites Manufactured Using Additive Manufacturing—A Brief Review

by Sundarakannan Rajendran, Geetha Palani, Arunprasath Kanakaraj, Vigneshwaran Shanmugam, Arumugaprabu Veerasimman, Szymon Gądek, Kinga Korniejenko and Uthayakumar Marimuthu

Polymers 2023, 15(11), 2564; https://doi.org/10.3390/polym15112564 - 02 Jun 2023

Cited by 12 | Viewed by 2950

Abstract

This review examines the mechanical performance of metal- and polymer-based composites fabricated using additive manufacturing (AM) techniques. Composite materials have significantly influenced various industries due to their exceptional reliability and effectiveness. As technology advances, new types of composite reinforcements, such as novel chemical-based [...] Read more.

This review examines the mechanical performance of metal- and polymer-based composites fabricated using additive manufacturing (AM) techniques. Composite materials have significantly influenced various industries due to their exceptional reliability and effectiveness. As technology advances, new types of composite reinforcements, such as novel chemical-based and bio-based, and new fabrication techniques are utilized to develop high-performance composite materials. AM, a widely popular concept poised to shape the development of Industry 4.0, is also being utilized in the production of composite materials. Comparing AM-based manufacturing processes to traditional methods reveals significant variations in the performance of the resulting composites. The primary objective of this review is to offer a comprehensive understanding of metal- and polymer-based composites and their applications in diverse fields. Further on this review delves into the intricate details of metal- and polymer-based composites, shedding light on their mechanical performance and exploring the various industries and sectors where they find utility. Full article

(This article belongs to the Section Polymer Applications)

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16 pages, 4833 KiB

Open AccessArticle

Flame-Retardance Functionalization of Jute and Jute-Cotton Fabrics

by Most Setara Begum, Abdul Kader and Rimvydas Milašius

Polymers 2023, 15(11), 2563; https://doi.org/10.3390/polym15112563 - 02 Jun 2023

Cited by 2 | Viewed by 1514

Abstract

Jute is a ligno-cellulosic natural fiber that ranks second in terms of the volume of cellulosic fibers and is extensively utilized for technical textile applications. The goal of this study is to determine the flame-retardance (FR) properties of pure Jute and Jute-Cotton fabrics [...] Read more.

Jute is a ligno-cellulosic natural fiber that ranks second in terms of the volume of cellulosic fibers and is extensively utilized for technical textile applications. The goal of this study is to determine the flame-retardance (FR) properties of pure Jute and Jute-Cotton fabrics treated with Pyrovatex CP New at concentrations of 90% (owf), M:L: 1:7. Both fabrics exhibited a substantial improvement in flame-retardancy. After the ignition period, the recorded flame spread time in both FR treated fabrics was zero seconds; whereas for untreated Jute and Jute-Cotton fabrics, the flame spread time was measured 21 s and 28 s, respectively, to burn their entire length (15 cm). Within these flame-spread times, the length of the char was 2.1 cm and 2.57 cm in the Jute and Jute-Cotton fabrics, respectively. After FR finishing, on both fabrics in the warp and weft directions, the physico-mechanical properties significantly decreased. The deposition of flame-retardant finishes on the fabric surface was determined by Scanning Electron Microscope (SEM) images. According to Fourier Transform Infra-Red Spectroscopy (FTIR) analysis, the flame-retardant chemical had no effect on the inherent properties of the fibers. Thermogravimetric analysis (TGA) analysis revealed that FR treated fabrics had early degradation, resulting in the formation of more char than in the untreated samples. After FR treatment, both fabrics showed a significant improvement in residual mass (more than 50%). Although the formaldehyde content observed in the FR treated samples was significantly greater, it was still within the permitted limit formaldehyde content in textiles intended for outerwear and not worn next to the skin. The results of this investigation demonstrate the potential use of Pyrovatex CP New in jute-based materials. Full article

(This article belongs to the Special Issue Green Flame-Retardant Polymer Material)

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13 pages, 7824 KiB

Open AccessArticle

Thiol-Surface-Engineered Cellulose Nanocrystals in Favor of Copper Ion Uptake

by Trung Dang-Bao, Thi-My-Chau Nguyen, Gia-Han Hoang, Hoa-Hung Lam, Hong-Phuong Phan and Thi-Kieu-Anh Tran

Polymers 2023, 15(11), 2562; https://doi.org/10.3390/polym15112562 - 02 Jun 2023

Cited by 3 | Viewed by 1251

Abstract

Cellulose, the most abundant natural polymer on earth, has recently gained attention for a large spectrum of applications. At a nanoscale, nanocelluloses (mainly involving cellulose nanocrystals or cellulose nanofibrils) possess many predominant features, such as highly thermal and mechanical stability, renewability, biodegradability and [...] Read more.

Cellulose, the most abundant natural polymer on earth, has recently gained attention for a large spectrum of applications. At a nanoscale, nanocelluloses (mainly involving cellulose nanocrystals or cellulose nanofibrils) possess many predominant features, such as highly thermal and mechanical stability, renewability, biodegradability and non-toxicity. More importantly, the surface modification of such nanocelluloses can be efficiently obtained based on the native surface hydroxyl groups, acting as metal ions chelators. Taking into account this fact, in the present work, the sequential process involving chemical hydrolysis of cellulose and autocatalytic esterification using thioglycolic acid was performed to obtain thiol-functionalized cellulose nanocrystals. The change in chemical compositions was attributed to thiol-functionalized groups and explored via the degree of substitution using a back titration method, X-ray powder diffraction, Fourier-transform infrared spectroscopy and thermogravimetric analysis. Cellulose nanocrystals were spherical in shape and ca. 50 nm in diameter as observed via transmission electron microscopy. The adsorption behavior of such a nanomaterial toward divalent copper ions from an aqueous solution was also assessed via isotherm and kinetic studies, elucidating a chemisorption mechanism (ion exchange, metal chelation and electrostatic force) and processing its operational parameters. In contrast to an inactive configure of unmodified cellulose, the maximum adsorption capacity of thiol-functionalized cellulose nanocrystals toward divalent copper ions from an aqueous solution was 4.244 mg g⁻¹ at a pH of 5 and at room temperature. Full article

(This article belongs to the Special Issue Advances in Cellulose-Based Polymers and Composites)

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24 pages, 4925 KiB

Open AccessArticle

Development of BioPolyurethane Coatings from Biomass-Derived Alkylphenol Polyols—A Green Alternative

by Tiago A. R. Silva, Ana C. Marques, Rui G. dos Santos, Rana A. Shakoor, Maryna Taryba and Maria Fátima Montemor

Polymers 2023, 15(11), 2561; https://doi.org/10.3390/polym15112561 - 02 Jun 2023

Cited by 1 | Viewed by 1853

Abstract

Bio-based polyols were obtained from the thermochemical liquefaction of two biomass feedstocks, pinewood and Stipa tenacissima, with conversion rates varying between 71.9 and 79.3 wt.%, and comprehensively characterized. They exhibit phenolic and aliphatic moieties displaying hydroxyl (OH) functional groups, as confirmed by [...] Read more.

Bio-based polyols were obtained from the thermochemical liquefaction of two biomass feedstocks, pinewood and Stipa tenacissima, with conversion rates varying between 71.9 and 79.3 wt.%, and comprehensively characterized. They exhibit phenolic and aliphatic moieties displaying hydroxyl (OH) functional groups, as confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and nuclear magnetic resonance spectroscopy (NMR) analysis. The biopolyols obtained were successfully employed as a green raw material to produce bio-based polyurethane (BioPU) coatings on carbon steel substrates, using, as an isocyanate source, a commercial bio-based polyisocyanate—Desmodur^® Eco N7300. The BioPU coatings were analyzed in terms of chemical structure, the extent of the reaction of the isocyanate species, thermal stability, hydrophobicity, and adhesion strength. They show moderate thermal stability at temperatures up to 100 °C, and a mild hydrophobicity, displaying contact angles between 68° and 86°. The adhesion tests reveal similar pull-off strength values (ca. 2.2 MPa) for the BioPU either prepared with pinewood and Stipa-derived biopolyols (BPUI and BPUII). Electrochemical impedance spectroscopy (EIS) measurements were carried out on the coated substrates for 60 days in 0.05 M NaCl solution. Good corrosion protection properties were achieved for the coatings, with particular emphasis on the coating prepared with the pinewood-derived polyol, which exhibited a low-frequency impedance modulus normalized for the coating thickness of 6.1 × 10¹⁰ Ω cm at the end of the 60 days test, three times higher than for coatings prepared with Stipa-derived biopolyols. The produced BioPU formulations show great potential for application as coatings, and for further modification with bio-based fillers and corrosion inhibitors. Full article

(This article belongs to the Special Issue Overcoming Challenges through Sustainable Polyurethane Based Strategies)

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15 pages, 7185 KiB

Open AccessArticle

Evaluating the Effect of Iron(III) in the Preparation of a Conductive Porous Composite Using a Biomass Waste-Based Starch Template

by Laria Rodríguez-Quesada, Karla Ramírez-Sánchez, Sebastián León-Carvajal, Giovanni Sáenz-Arce, Fabián Vásquez-Sancho, Esteban Avendaño-Soto, Juan José Montero-Rodríguez and Ricardo Starbird-Perez

Polymers 2023, 15(11), 2560; https://doi.org/10.3390/polym15112560 - 02 Jun 2023

Viewed by 1285

Abstract

In this work, the effect of iron(III) in the preparation of a conductive porous composite using a biomass waste-based starch template was evaluated. Biopolymers are obtained from natural sources, for instance, starch from potato waste, and its conversion into value-added products is highly [...] Read more.

In this work, the effect of iron(III) in the preparation of a conductive porous composite using a biomass waste-based starch template was evaluated. Biopolymers are obtained from natural sources, for instance, starch from potato waste, and its conversion into value-added products is highly significant in a circular economy. The biomass starch-based conductive cryogel was polymerized via chemical oxidation of 3,4-ethylenedioxythiophene (EDOT) using iron(III) p-toluenesulfonate as a strategy to functionalize porous biopolymers. Thermal, spectrophotometric, physical, and chemical properties of the starch template, starch/iron(III), and the conductive polymer composites were evaluated. The impedance data of the conductive polymer deposited onto the starch template confirmed that at a longer soaking time, the electrical performance of the composite was improved, slightly modifying its microstructure. The functionalization of porous cryogels and aerogels using polysaccharides as raw materials is of great interest for applications in electronic, environmental, and biological fields. Full article

(This article belongs to the Special Issue Fabrication and Application of Biopolymer-Based Advanced Functional Materials)

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23 pages, 4468 KiB

Open AccessArticle

Argon Plasma Jet-Treated Poly (Vinyl Alcohol)/Chitosan and PEG 400 Plus Mangifera indica Leaf Extract for Electrospun Nanofiber Membranes: In Vitro Study

by Pongphun Sukum, Winita Punyodom, Somsak Dangtip, Pipath Poramapijitwat, Donraporn Daranarong, Thannaphat Jenvoraphot, Mudtorlep Nisoa, Chakkrapong Kuensaen and Dheerawan Boonyawan

Polymers 2023, 15(11), 2559; https://doi.org/10.3390/polym15112559 - 02 Jun 2023

Cited by 3 | Viewed by 2333

Abstract

The wound-healing process can be disrupted at any stage due to various internal and external factors. The inflammatory stage of the process plays a vital role in determining the outcome of the wound. Prolonged inflammation due to bacterial infection can lead to tissue [...] Read more.

The wound-healing process can be disrupted at any stage due to various internal and external factors. The inflammatory stage of the process plays a vital role in determining the outcome of the wound. Prolonged inflammation due to bacterial infection can lead to tissue damage, slow healing, and complications. Wound dressings made using materials such as poly (vinyl alcohol) (PVA), chitosan (CS), and poly (ethylene glycol) (PEG) with Mangifera extract (ME) added can help reduce infection and inflammation, creating a conducive environment for faster healing. However, creating the electrospun membrane is challenging due to balancing various forces such as rheological behavior, conductivity, and surface tension. To improve the electrospinnability of the polymer solution, an atmospheric pressure plasma jet can induce chemistry in the solution and increase the polarity of the solvent. Thus, this research aims to investigate the effect of plasma treatment on PVA, CS, and PEG polymer solutions and fabricate ME wound dressing via electrospinning. The results indicated that increasing plasma treatment time increased the viscosity of the polymer solution, from 269 mPa∙to 331 mPa∙s after 60 min, and led to an increase in conductivity from 298 mS/cm to 330 mS/cm and an increase in nanofiber diameter from 90 ± 40 nm to 109 ± 49 nm. Incorporating 1% mangiferin extract into an electrospun nanofiber membrane has been found to increase the inhibition rates of Escherichia coli and Staphylococcus aureus by 29.2% and 61.2%, respectively. Additionally, the fiber diameter decreases when compared with the electrospun nanofiber membrane without ME. Our findings demonstrate that electrospun nanofiber membrane with ME has anti-infective properties and can promote faster wound healing. Full article

(This article belongs to the Special Issue Polymeric Membranes: Fabrication, Characterization, and Applications)

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18 pages, 2427 KiB

Open AccessArticle

Pore Structure Tuning of Poly-EGDMA Biomedical Material by Varying the O-Quinone Photoinitiator

by Vladimir V. Yudin, Margarita P. Shurygina, Marfa N. Egorikhina, Diana Ya. Aleynik, Daria D. Linkova, Irina N. Charykova, Roman S. Kovylin and Sergey A. Chesnokov

Polymers 2023, 15(11), 2558; https://doi.org/10.3390/polym15112558 - 02 Jun 2023

Cited by 3 | Viewed by 1189

Abstract

Porous polymer monoliths with thicknesses of 2 and 4 mm were obtained via polymerization of ethylene glycol dimethacrylate (EGDMA) under the influence visible-light irradiation in the presence of a 70 wt% 1-butanol porogenic agent and o-quinone photoinitiators. The o-quinones used were: 3,5-di-tret-butyl-benzoquinone-1,2 (35Q), [...] Read more.

Porous polymer monoliths with thicknesses of 2 and 4 mm were obtained via polymerization of ethylene glycol dimethacrylate (EGDMA) under the influence visible-light irradiation in the presence of a 70 wt% 1-butanol porogenic agent and o-quinone photoinitiators. The o-quinones used were: 3,5-di-tret-butyl-benzoquinone-1,2 (35Q), 3,6-di-tret-butyl-benzoquinone-1,2 (36Q), camphorquinone (CQ), and 9,10-phenanthrenequinone (PQ). Porous monoliths were also synthesized from the same mixture but using 2,2′-azo-bis(iso-butyronitrile) (AIBN) at 100 °C instead o-quinones. According to the results of scanning electron microscopy, all the resulting samples were conglomerates of spherical, polymeric particles with pores between them. Use of mercury porometry showed that the interconnected pore systems of all the polymers were open. The average pore size, D_mod, in such polymers strongly depended on both the nature of the initiator and the method of initiation of polymerization. For polymers obtained in the presence of AIBN, the D_mod value was as low as 0.8 μm. For polymers obtained via photoinitiation in the presence of 36Q, 35Q, CQ, and PQ, the D_mod values were significantly greater, i.e., 9.9, 6.4, 3.6, and 3.7 μm, respectively. The compressive strength and Young’s modulus of the porous monoliths increased symbatically in the series PQ < CQ < 36Q < 35Q < AIBN with decreasing proportions of large pores (over 12 μm) in their polymer structures. The photopolymerization rate of the EGDMA and 1-butanol, 30:70 wt% mixture was maximal for PQ and minimal for 35Q. All polymers tested were non-cytotoxic. Based on the data from MTT testing, it can be noted that the polymers obtained via photoinitiation were characterized by their positive effect on the proliferative activity of human dermal fibroblasts. This makes them promising osteoplastic materials for clinical trials. Full article

(This article belongs to the Special Issue Polymeric Porous Materials and Derivatives for Advanced Applications)

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10 pages, 1091 KiB

Open AccessArticle

Development of a Water Transmission Rate (WTR) Measurement System for Implantable Barrier Coatings

by Sébastien Buchwalder, Cléo Nicolier, Mario Hersberger, Florian Bourgeois, Andreas Hogg and Jürgen Burger

Polymers 2023, 15(11), 2557; https://doi.org/10.3390/polym15112557 - 01 Jun 2023

Cited by 1 | Viewed by 1437

Abstract

While water vapor transmission rate (WVTR) measurement is standardly used to assess material permeability, a system able to quantify liquid water transmission rate (WTR) measurement is highly desirable for implantable thin film barrier coatings. Indeed, since implantable devices are in contact or immersed [...] Read more.

While water vapor transmission rate (WVTR) measurement is standardly used to assess material permeability, a system able to quantify liquid water transmission rate (WTR) measurement is highly desirable for implantable thin film barrier coatings. Indeed, since implantable devices are in contact or immersed in body fluids, liquid WTR was carried out to obtain a more realistic measurement of the barrier performance. Parylene is a well-established polymer which is often the material of choice for biomedical encapsulation applications due to its flexibility, biocompatibility, and attractive barrier properties. Four grades of parylene coatings were tested with a newly developed permeation measurement system based on a quadrupole mass spectrometer (QMS) detection method. Successful measurements of gas and water vapor and the water transmission rates of thin parylene films were performed and validated, comparing the results with a standardized method. In addition, the WTR results allowed for the extraction of an acceleration transmission rate factor from the vapor-to-liquid water measurement mode, which varies from 4 to 4.8 between WVTR and WTR. With a WTR of 72.5 µm g m⁻² day⁻¹, parylene C displayed the most effective barrier performance. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Membranes and Films II)

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11 pages, 1952 KiB

Open AccessArticle

Development of New Accelerated Aging Test for Comparison of the Quality of Different Insulating Papers Based on Cellulose

by Draginja Mihajlovic, Valentina Vasovic and Jelena Lukic

Polymers 2023, 15(11), 2556; https://doi.org/10.3390/polym15112556 - 01 Jun 2023

Viewed by 1113

Abstract

The aim of this study is to propose a test method for the determination of the quality of transformer paper insulation. For this purpose, the oil/cellulose insulation systems were exposed to various accelerated aging tests. The results of the aging experiments of normal [...] Read more.

The aim of this study is to propose a test method for the determination of the quality of transformer paper insulation. For this purpose, the oil/cellulose insulation systems were exposed to various accelerated aging tests. The results of the aging experiments of normal Kraft and thermally upgraded papers, two different types of transformer oil (mineral and natural ester), and copper are shown. Aging was carried out in various experiments at 150 °C, 160 °C, 170 °C, and 180 °C with dry (initial values ≤ 0.5%) and moistened cellulose insulation (initial values 3–3.5%). Following insulating oil and paper, degradation markers were measured: the degree of polymerization, tensile strength, furan derivates, methanol/ethanol, acidity, interfacial tension, and dissipation factor. It was found that the aging of cellulose insulation in cycles was 1.5–1.6 times faster in comparison to continuous aging, due to the more pronounced effect of hydrolytic mechanism in cyclic aging owing to the produced and absorbed water. Furthermore, it was observed that the high initial water content in cellulose increases the aging rate two to three times more than in the dry experimental setup. The proposed aging test in cycles can be used to achieve faster aging and to compare the quality of different insulating papers. Full article

(This article belongs to the Special Issue Advances in Cellulose-Based Polymers and Composites)

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16 pages, 4534 KiB

Open AccessArticle

Synthesis and Characterization of Poly(DL-lactide) Containing Fluorene Structures

by Chung-Fu Yu, Syang-Peng Rwei, Shung-Jim Yang, Wen-Chin Tsen and Li-Huei Lin

Polymers 2023, 15(11), 2555; https://doi.org/10.3390/polym15112555 - 01 Jun 2023

Viewed by 1405

Abstract

9,9-bis[4-(2-hydroxy-3-acryloyloxypropoxy)phenyl]fluorene (BPF) hydroxyl groups (-OH) were used as initiators in the ring-opening polymerization reaction with DL-lactide monomers at different molar ratios to synthesize a Poly(DL-lactide) polymer containing bisphenol fluorene structure and acrylate functional groups (DL-BPF). The polymer’s structure and molecular weight range were [...] Read more.

9,9-bis[4-(2-hydroxy-3-acryloyloxypropoxy)phenyl]fluorene (BPF) hydroxyl groups (-OH) were used as initiators in the ring-opening polymerization reaction with DL-lactide monomers at different molar ratios to synthesize a Poly(DL-lactide) polymer containing bisphenol fluorene structure and acrylate functional groups (DL-BPF). The polymer’s structure and molecular weight range were analyzed using NMR (¹H, ¹³C) and gel permeation chromatography. DL-BPF was then subjected to photocrosslinking using the photoinitiator Omnirad 1173, resulting in the formation of an optically transparent crosslinked polymer. Characterization of the crosslinked polymer involved analyzing its gel content, refractive index, thermal stability (via differential scanning thermometry (DSC) and thermogravimetric analysis (TGA)), as well as conducting cytotoxicity tests. The crosslinked copolymer exhibited a maximum refractive index of 1.5276, a maximum glass transition temperature of 61.1 °C, and cell survival rates higher than 83% in the cytotoxicity tests. Full article

(This article belongs to the Special Issue Advances in Polymerization and Kinetic Studies)

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14 pages, 16966 KiB

Open AccessArticle

Improving the Mechanical Properties of CCFRPLA by Enhancing the Interface Binding Energy and Strengthening the Anti-Separation Ability of a PLA Matrix

by Hongbin Li, Zhihua Li, Na Wang, Yubao Peng, Zhuang Jiang and Qiushuang Zhang

Polymers 2023, 15(11), 2554; https://doi.org/10.3390/polym15112554 - 01 Jun 2023

Cited by 3 | Viewed by 1096

Abstract

Additive manufacturing (AM) can produce almost any product shape through layered stacking. The usability of continuous fiber-reinforced polymers (CFRP) fabricated by AM, however, is restricted owing to the limitations of no reinforcing fibers in the lay-up direction and weak interface bonding between the [...] Read more.

Additive manufacturing (AM) can produce almost any product shape through layered stacking. The usability of continuous fiber-reinforced polymers (CFRP) fabricated by AM, however, is restricted owing to the limitations of no reinforcing fibers in the lay-up direction and weak interface bonding between the fibers and matrix. This study presents molecular dynamics in conjunction with experiments to explore how ultrasonic vibration enhances the performance of continuous carbon fiber-reinforced polylactic acid (CCFRPLA). Ultrasonic vibration improves the mobility of PLA matrix molecular chains by causing alternative fractures of chains, promoting crosslinking infiltration among polymer chains, and facilitating interactions between carbon fibers and the matrix. The increase in entanglement density and conformational changes enhanced the density of the PLA matrix and strengthened its anti-separation ability. In addition, ultrasonic vibration shortens the distance between the molecules of the fiber and matrix, improving the van der Waals force and thus promoting the interface binding energy between them, which ultimately achieves an overall improvement in the performance of CCFRPLA. The bending strength and interlaminar shear strength of the specimen treated with 20 W ultrasonic vibration reached 111.5 MPa and 10.16 MPa, respectively, 33.11% and 21.5% higher than those of the untreated specimen, consistent with the molecular dynamics simulations, and confirmed the effectiveness of ultrasonic vibration in improving the flexural and interlaminar properties of the CCFRPLA. Full article

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2 pages, 796 KiB

Open AccessCorrection

Correction: Savović et al. Power Flow in Multimode Graded-Index Microstructured Polymer Optical Fibers. Polymers 2023, 15, 1474

by Svetislav Savović, Ana Simović, Branko Drljača, Milan S. Kovačević, Ljubica Kuzmanović, Alexandar Djordjevich, Konstantinos Aidinis and Rui Min

Polymers 2023, 15(11), 2553; https://doi.org/10.3390/polym15112553 - 01 Jun 2023

Viewed by 2334

Abstract

The authors wish to make three changes to their published paper [...] Full article

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