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Search Results (548)

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Keywords = thermoplastic polyurethanes

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13 pages, 1623 KiB  
Article
Effect of Absolute Ethanol and Thermal Treatment on Shrinkage and Mechanical Properties of TPU Electrospun Nanofiber Membranes
by Lei Wang, Ming Kong, Shengchun Wang, Chunsheng Li and Min Yang
Coatings 2025, 15(8), 897; https://doi.org/10.3390/coatings15080897 (registering DOI) - 1 Aug 2025
Viewed by 149
Abstract
Thermoplastic polyurethane (TPU) electrospun fiber membranes possess unique micro-nano structures and excellent properties. Adjusting their wettability enables the directional transportation of lubricants. A conventional method for adjusting porosity and wettability involves inducing membrane shrinkage using absolute ethanol and heat treatment. However, the shrinkage [...] Read more.
Thermoplastic polyurethane (TPU) electrospun fiber membranes possess unique micro-nano structures and excellent properties. Adjusting their wettability enables the directional transportation of lubricants. A conventional method for adjusting porosity and wettability involves inducing membrane shrinkage using absolute ethanol and heat treatment. However, the shrinkage response and the corresponding changes in the tensile properties of TPU fiber membranes after induction remain unclear, limiting their applications. Thus, in this study, after being peeled off, the samples were first left to stand at room temperature (RT) for 24 h to release residual stress and stabilize their dimensions, and then treated with dehydrated ethanol at RT and high temperature, respectively, with their shrinkage behaviors observed and recorded. The results showed that TPU nanofiber membranes shrank significantly in absolute ethanol, and the degree of shrinkage was temperature-dependent. The shrinkage rates were 2% and 4% in dehydrated ethanol at room temperature and high temperature, respectively, and heating increased the shrinkage effect by 200%. These findings prove that absolute ethanol causes TPU fibers to shrink, and high temperatures further promote shrinkage. However, although the strong synergistic effect of heat and solvent accelerates shrinkage, it may induce internal structural defects, resulting in the deterioration of mechanical properties. The contraction response induced by anhydrous ethanol stimulation can be used to directionally adjust the local density and modulus of TPU nanofiber membranes, thereby changing the wettability. This approach provides new opportunities for applications in areas such as medium transportation and interface friction reduction in lubrication systems. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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14 pages, 2149 KiB  
Article
Three-Dimensional-Printed Thermoplastic Polyurethane (TPU) Graft and H-Button Stabilization System for Intra-Articular Cranial Cruciate Ligament Reconstruction: Cadaveric Study
by Menna Nahla, Yara Abouelela, Mohammed Amer, Marwa Ali, Abdelbary Prince, Ayman Tolba and Ayman Mostafa
Vet. Sci. 2025, 12(8), 725; https://doi.org/10.3390/vetsci12080725 - 31 Jul 2025
Viewed by 98
Abstract
Cranial cruciate ligament (CrCL) rupture is a common orthopedic disorder in dogs, leading to stifle joint instability and progressive osteoarthritis. This study aimed to develop and biomechanically evaluate a novel intra-articular reconstruction system designed to mimic the natural ligament and restore joint stability [...] Read more.
Cranial cruciate ligament (CrCL) rupture is a common orthopedic disorder in dogs, leading to stifle joint instability and progressive osteoarthritis. This study aimed to develop and biomechanically evaluate a novel intra-articular reconstruction system designed to mimic the natural ligament and restore joint stability following CrCL excision. The system consisted of a 3D-printed thermoplastic polyurethane (TPU) graft, cerclage wire, and H-button fixation. Fourteen pelvic limbs from mature mixed-breed cadaveric dogs were used. The inclination angle, dimensions, volume, tensile strength, and elongation of the native CrCL were measured. Seven CrCL-deficient stifles were reconstructed using the proposed system and tested biomechanically. The native CrCL showed a significantly higher tensile strength than the TPU graft; however, the TPU demonstrated a greater flexibility. The reconstruction system successfully stabilized the joint and provided repeatable fixation. Significant correlations were found between CrCL volume and both age and body weight. These findings support the mechanical suitability of the proposed system for ex vivo stifle stabilization and highlight the potential of 3D-printed TPU in ligament reconstruction. Further in vivo studies are recommended to assess long-term performance, including implant integration, tissue remodeling, and clinical outcomes. Full article
(This article belongs to the Section Veterinary Surgery)
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17 pages, 3023 KiB  
Article
Slip-Resistance Performance of Basketball Shoes Tread Patterns on Common Courts
by Pramod Yadav, Shubham Gupta, Dishant Sharma and Arnab Chanda
Appl. Mech. 2025, 6(3), 54; https://doi.org/10.3390/applmech6030054 - 24 Jul 2025
Viewed by 391
Abstract
Basketball requires intense movements like jumping and sudden changes in direction, increasing the risk of slips and falls due to poor shoe–court traction. Therefore, a significant demand is for good traction performance in basketball shoes, particularly in the heel region on different court [...] Read more.
Basketball requires intense movements like jumping and sudden changes in direction, increasing the risk of slips and falls due to poor shoe–court traction. Therefore, a significant demand is for good traction performance in basketball shoes, particularly in the heel region on different court surfaces, to prevent slipping. This study examined the traction performance of fifteen common basketball shoe designs that were considered and developed using thermoplastic polyurethane to assess the available coefficient of friction (ACOF) on popular floorings (hardwood, synthetic, and polyurethane) under dry and wet conditions using a robotic slip tester. Results indicate that the hardwood flooring provided better traction, followed by the synthetic flooring, while the polyurethane flooring showed reduced friction. The study also examined the traction with apparent contact areas. Shoes with herringbone and circular tread patterns demonstrated the highest traction on all flooring in dry conditions. This research is anticipated to help basketball shoemakers choose safer shoes for player safety and performance, providing a foundation for future research on shoe flooring interaction in basketball. Full article
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24 pages, 5801 KiB  
Article
A Study on the Performance of Gel-Based Polyurethane Prepolymer/Ceramic Fiber Composite-Modified Asphalt
by Tengteng Guo, Xu Guo, Yuanzhao Chen, Chenze Fang, Jingyu Yang, Zhenxia Li, Jiajie Feng, Hao Huang, Zhi Li, Haijun Chen and Jiachen Wang
Gels 2025, 11(7), 558; https://doi.org/10.3390/gels11070558 - 20 Jul 2025
Viewed by 249
Abstract
In order to solve various problems in traditional roads and extend their service life, new road materials have become a research hotspot. Polyurethane prepolymers (PUPs) and ceramic fibers (CFs), as materials with unique properties, were chosen due to their synergistic effect: PUPs provide [...] Read more.
In order to solve various problems in traditional roads and extend their service life, new road materials have become a research hotspot. Polyurethane prepolymers (PUPs) and ceramic fibers (CFs), as materials with unique properties, were chosen due to their synergistic effect: PUPs provide elasticity and gel-like behavior, while CFs contribute to structural stability and high-temperature resistance, making them ideal for enhancing asphalt performance. PUPs, a thermoplastic and elastic polyurethane gel material, not only enhance the flexibility and adhesion properties of asphalt but also significantly improve the structural stability of composite materials when synergistically combined with CF. Using response surface methodology, an optimized preparation scheme for PUP/CF composite-modified asphalt was investigated. Through aging tests, dynamic shear rate (DSR) testing, bending rate (BBR) testing, microstructure scanning (MSCR), scanning electron microscopy (SEM), atomic force microscopy (AFM), and infrared spectroscopy (IR), the aging performance, rheological properties, permanent deformation resistance, microstructure, and modification mechanism of PUP/CF composite-modified asphalt were investigated. The results indicate that the optimal preparation scheme is a PUP content of 7.4%, a CF content of 2.1%, and a shear time of 40 min. The addition of the PUP and CF significantly enhances the asphalt’s aging resistance, and compared with single-CF-modified asphalt and base asphalt, the PUP/CF composite-modified asphalt exhibits superior high- and low-temperature rheological properties, demonstrating stronger strain recovery capability. The PUP forms a gel network structure in the material, effectively filling the gaps between CF and asphalt, enhancing interfacial bonding strength, and making the overall performance more stable. AFM microscopic morphology shows that PUP/CF composite-modified asphalt has more “honeycomb structures” than matrix asphalt and CF-modified asphalt, forming more structural asphalt and enhancing overall structural stability. This study indicates that the synergistic effect of PUP gel and CF significantly improves the macro and micro properties of asphalt. The PUP forms a three-dimensional elastic gel network in asphalt, improving adhesion and deformation resistance. Using response surface methodology, the optimal formulation (7.4% PUP, 2.1% CF) improves penetration (↓41.5%), softening point (↑6.7 °C), and ductility (↑9%), demonstrating the relevance of gel-based composites for asphalt modification. Full article
(This article belongs to the Special Issue Synthesis, Properties, and Applications of Novel Polymer-Based Gels)
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19 pages, 3482 KiB  
Article
Enhancing the Energy Absorption Performance of 3D-Printed CF/TPU Composite Materials by Introducing a “Rigid–Elastic” Structure Through Multi-Scale Synergies
by Xuanyu Zhou, He Ouyang, Yuan Zhang, Ziqiang Zhu, Zhen Wang, Zirui Cheng, Yubing Hu and Yanan Zhang
Polymers 2025, 17(13), 1880; https://doi.org/10.3390/polym17131880 - 6 Jul 2025
Viewed by 608
Abstract
Thermoplastic polyurethane (TPU) combines elastomeric and thermoplastic properties but suffers from insufficient rigidity and strength for structural applications. Herein, we developed novel carbon fiber-reinforced TPU (CF/TPU) composites filaments and utilize melt extrusion for 3D printing to maintain elasticity, while achieving enhanced stiffness and [...] Read more.
Thermoplastic polyurethane (TPU) combines elastomeric and thermoplastic properties but suffers from insufficient rigidity and strength for structural applications. Herein, we developed novel carbon fiber-reinforced TPU (CF/TPU) composites filaments and utilize melt extrusion for 3D printing to maintain elasticity, while achieving enhanced stiffness and strength through multi scale-the control of fiber content and optimization of printing parameters, reaching a rigid–elastic balance. A systematic evaluation of CF content (0–25%) and printing parameters revealed optimal performance to be at 220–230 °C and 40 mm/s for ensuring proper flow to wet fibers without polymer degradation. Compared with TPU, 20% CF/TPU exhibited 63.65%, 105.51%, and 93.69% improvements in tensile, compressive, and impact strength, respectively, alongside 70.88% and 72.92% enhancements in compression and impact energy absorption. This work establishes a fundamental framework for developing rigid–elastic hybrid materials with tailored energy absorption capabilities through rational material design and optimized additive manufacturing processes. Full article
(This article belongs to the Special Issue Research on Additive Manufacturing of Polymer Composites)
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24 pages, 462 KiB  
Review
In Vitro Flexural Testing of Clear Aligner Materials: A Scoping Review of Methods, Results, and Clinical Relevance
by Gavin Nugent, Alvaro Munoz, Chris Louca and Alessandro Vichi
Appl. Sci. 2025, 15(13), 7516; https://doi.org/10.3390/app15137516 - 4 Jul 2025
Viewed by 347
Abstract
Background: Clear aligner therapy (CAT) has become increasingly popular for treating mild to moderate malocclusions. However, discrepancies between predicted and achieved tooth movement remain a concern, partly due to the limited understanding of aligner material behavior under clinical conditions. Since these materials must [...] Read more.
Background: Clear aligner therapy (CAT) has become increasingly popular for treating mild to moderate malocclusions. However, discrepancies between predicted and achieved tooth movement remain a concern, partly due to the limited understanding of aligner material behavior under clinical conditions. Since these materials must deliver controlled and sustained forces, their flexural properties are critical for treatment efficacy. Objective: To identify and analyze in vitro studies investigating the flexural properties of thermoplastic clear aligner materials, summarize their testing methodologies, and examine the factors that may influence their clinical performance. Methods: A scoping review was conducted following the PRISMA-ScR guidelines. Three electronic databases (PubMed, Scopus, and Web of Science) were systematically searched. Studies were screened based on predefined eligibility criteria, and data extraction included testing methods, materials, and clinically relevant variables. Risk of bias was assessed using the QUIN tool. Results: Seventeen studies published between 2008 and 2024 were included. All studies used three-point bending to assess mechanical properties. Common influencing factors included thermoforming, liquid absorption, temperature changes, loading conditions, and material thickness. Most studies reported that these factors negatively affected force delivery. The most frequently tested material was Duran (PET-G). Polyurethane-based materials, such as Zendura, showed comparatively better stress relaxation properties. Conclusions: Thermoforming, intraoral temperature changes, liquid exposure, and prolonged or repeated loading can compromise the mechanical properties and force delivery capacity of aligner materials. Standardized testing methods and further investigation of newer materials are essential to enhance the predictability and performance of clear aligner therapy. Full article
(This article belongs to the Special Issue New Materials and Techniques in Restorative Dentistry)
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20 pages, 4516 KiB  
Article
Stability of TPU/PP Blends Exposed to UV Radiation for Industrial Applications
by Carlos Vargas-Isaza, Jose A. Tamayo, Libia M. Baena, Juan Felipe Santa Marin and Adrian José Benitez-Lozano
Polymers 2025, 17(13), 1842; https://doi.org/10.3390/polym17131842 - 30 Jun 2025
Viewed by 350
Abstract
Thermoplastic polyurethanes (TPUs) have found diverse applications across different industries, which expose the material to various environmental conditions. Among these, UV radiation stands out as one of the most aggressive, leading to significant degradation in polymers. Considering this, this study explores the use [...] Read more.
Thermoplastic polyurethanes (TPUs) have found diverse applications across different industries, which expose the material to various environmental conditions. Among these, UV radiation stands out as one of the most aggressive, leading to significant degradation in polymers. Considering this, this study explores the use of commercial additives, such as polyethylene masterbatches (MB), and their effectiveness as inhibitors of UV radiation-induced degradation. In addition, it investigates the possibility of blending high-performance polymers, such as TPU, with commodity polymers, such as polypropylenes. The prepared blends were evaluated via thermogravimetric analysis, infrared and electron microscopy, hardness and tensile strength assessments, and scanning electron microscopy before and after 320 h of exposure to accelerated aging. The findings suggest that the adequate incorporation of additives in blends can help to reduce the harmful effects caused by UV radiation on the polymeric materials. Full article
(This article belongs to the Section Polymer Applications)
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20 pages, 871 KiB  
Systematic Review
Organic and Synthetic Substitutes in Tracheal Reconstruction: A Scoping Review (2015–2025)
by Ana Caroline dos Santos, Guilherme Machado Holzlsauer, João Paulo Ruiz Lucio de Lima Parra, Raí André Querino Candelária, Thamires Santos da Silva, Rodrigo da Silva Nunes Barreto and Maria Angelica Miglino
Bioengineering 2025, 12(7), 704; https://doi.org/10.3390/bioengineering12070704 - 27 Jun 2025
Viewed by 519
Abstract
Tracheal defects have been the focus of research since the 19th century, but reconstructing this complex structure remains challenging. Identifying a safe, effective tracheal substitute is a key goal of surgery. This integrative review explores current tracheal substitutes and tissue engineering techniques. Data [...] Read more.
Tracheal defects have been the focus of research since the 19th century, but reconstructing this complex structure remains challenging. Identifying a safe, effective tracheal substitute is a key goal of surgery. This integrative review explores current tracheal substitutes and tissue engineering techniques. Data were collected from June 2024 to March 2025 from electronically available databases. Articles published between 2015 and 2025 were selected using the individualized protocol for each database. After screening 190 articles, 82 were excluded, and 108 were reviewed, with 100 meeting the final inclusion criteria. Recent substitutes include three-dimensional synthetic grafts made from polycaprolactone and copolyamide with thermoplastic elastomer, thermoplastic polyurethane and polylactic acid. Additionally, models using decellularized and recellularized tracheal matrix scaffolds and bioprinting techniques are being developed. Comparative studies of synthetic grafts and tracheal scaffolds, as well as cell self-aggregation methods to create tracheal analogues, are discussed. Advances in hybrid approaches combining synthetic polymers with extracellular matrix components aim to improve biocompatibility and functional integration. The importance of selecting appropriate preclinical animal models, such as goats, is also highlighted for translational relevance. Further research is required to refine protocols, overcome challenges related to vascularization and immune response, and ensure the development of clinically viable, long-lasting tracheal substitutes. Full article
(This article belongs to the Special Issue Engineering Biodegradable-Implant Materials, 2nd Edition)
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13 pages, 2181 KiB  
Article
Mechanical Properties of Dual-Layer Electrospun Fiber Mats
by Ioana Caloian, Jocelyn Trapp, Bhalaji Yadav Kantepalle, Patrick Latimer, Timothy J. Lawton and Christina Tang
Polymers 2025, 17(13), 1777; https://doi.org/10.3390/polym17131777 - 26 Jun 2025
Viewed by 371
Abstract
Electrospinning with sequential layer deposition has been reported for various applications such as tissue scaffolds, shape memory materials, and separations. However, the effect of layering on the mechanical properties is not fully understood. In this work, layered structures of thermoplastic polyurethane (TPU) and [...] Read more.
Electrospinning with sequential layer deposition has been reported for various applications such as tissue scaffolds, shape memory materials, and separations. However, the effect of layering on the mechanical properties is not fully understood. In this work, layered structures of thermoplastic polyurethane (TPU) and nylon were selected as a model system to investigate the effect of sequential layer deposition on mechanical properties. Evidence of the layered structure was indicated by scanning electron microscopy (SEM) and Fourier Transform Infrared spectroscopy (FTIR) experiments. Layering TPU with nylon resulted in a 60-fold increase in the Young’s modulus. The Young’s modulus of the layered structure was reasonably predicted by the Voigt rule of mixtures. Furthermore, the Young’s modulus changes without any statistically significant change in elongation at break compared to a single layer of nylon. Thus, the elongation at break was dictated by the stiffer material, despite being present at a lower volume fraction. Overall, electrospinning with sequential layer deposition electrospinning is an effective approach for tuning the mechanical properties and surface chemistry of electrospun materials independently, which may be of interest for applications in tissue engineering and separations. Full article
(This article belongs to the Section Polymer Applications)
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20 pages, 14795 KiB  
Article
Inkjet-Printed Conductive Patterns on Electrospun Substrates for the Modular Fabrication of Nonplanar Circuits
by Fabricio N. Molinari, Emanuel Bilbao and Leandro N. Monsalve
Appl. Nano 2025, 6(2), 10; https://doi.org/10.3390/applnano6020010 - 18 Jun 2025
Viewed by 444
Abstract
Placing printed conductive patterns onto nonplanar substrates is a challenging task. In this work, we tested a simple method for depositing inkjet-printed conductive patterns onto 3D-printed pieces with cavities and sharp edges. First, a silver nanoparticle ink was used to print conductive patterns [...] Read more.
Placing printed conductive patterns onto nonplanar substrates is a challenging task. In this work, we tested a simple method for depositing inkjet-printed conductive patterns onto 3D-printed pieces with cavities and sharp edges. First, a silver nanoparticle ink was used to print conductive patterns onto a flexible and porous substrate made of electrospun polycaprolactone (PCL). Then, the printed patterns were transferred to 3D-printed pieces made of polylactic acid (PLA) by temperature-promoted adhesion. Finally, the printed patterns were cured to render them conductive. The influence of the number of printed layers on their electrical and mechanical properties was evaluated. The printed patterns were also transferred to flexible substrates, such as thermoplastic polyurethane (TPU) and polyethylene terephthalate (PET) sheets, achieving conductivity after curing. Moreover, the printed patterns were effective for modular interconnection among successive transferred patterns, since it was possible to achieve electrical contact between them during the transfer process. Full article
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21 pages, 2648 KiB  
Article
Biodegradable Polyurethanes for Tissue Engineering: Influence of L-Lactide Content on Degradation and Mechanical Properties
by Alejandra Rubio Hernández-Sampelayo, Laura Diñeiro, Dulce María González-García, Enrique Martínez Campos, Rodrigo Navarro and Ángel Marcos-Fernández
Polymers 2025, 17(12), 1685; https://doi.org/10.3390/polym17121685 - 17 Jun 2025
Viewed by 400
Abstract
The influence of L-lactide content (between 15% and 43%) on the degradation of biodegradable polyurethanes (PUs) for tissue engineering was systematically addressed in this study. An ideal tissue scaffold should exhibit a mechanical response and degradability appropriate for the host tissue. To achieve [...] Read more.
The influence of L-lactide content (between 15% and 43%) on the degradation of biodegradable polyurethanes (PUs) for tissue engineering was systematically addressed in this study. An ideal tissue scaffold should exhibit a mechanical response and degradability appropriate for the host tissue. To achieve it, polyols containing ε-caprolactone and L-lactide moieties were used, with the random distribution of lactide units disrupting the regularity, and hence the crystallinity, of poly(caprolactone) segments, facilitating their degradation. The biodegradable PUs were synthesised using these copolymers as soft segments and were characterised through various physicochemical techniques, including bioassays and water absorption measurements. It was determined that mechanical behaviour and water absorption depended significantly on molecular weight, L-lactide content in the soft segment, and the crystallinity of the hard segment. Additionally, two types of chain extenders were also evaluated: hydrolysable and non-hydrolysable. PUs based on hydrolysable chain extenders achieved higher molecular weights and exhibited better mechanical performance than their non-hydrolysable counterparts. To assess the cytocompatibility of these materials, an endothelial model was used, involving metabolic activity and DNA content analysis. The results demonstrated good cell adhesion and the absence of toxicity, confirming the viability of cell growth on the surfaces of these biodegradable PUs. The PUs developed in this study exhibited a low initial modulus and adjustable mechanical properties, highlighting their potential application in tissue engineering as biodegradable and biocompatible biomedical materials. Full article
(This article belongs to the Special Issue Advanced Biodegradable Polymers for Biomedical Applications)
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15 pages, 5199 KiB  
Article
Biodegradable, Wear-Resistant and Resilient Thermoplastic Polycarbonate-Based Polyurethane with Nanoscale Microphase Structure
by Shuang Su, Jintao Wang, Qi Yan, Anqi Li, Chuang Liu, Xianli Wu and Yuezhong Meng
Polymers 2025, 17(12), 1665; https://doi.org/10.3390/polym17121665 - 16 Jun 2025
Viewed by 498
Abstract
A series of PPCDL-PEG1000-TPU were prepared by melting method using CO2 based biodegradable polycarbonate diol (PPCDL) and polyethylene glycol (PEG1000) as soft segments, and hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) as hard segments. Their structure and properties were characterized to [...] Read more.
A series of PPCDL-PEG1000-TPU were prepared by melting method using CO2 based biodegradable polycarbonate diol (PPCDL) and polyethylene glycol (PEG1000) as soft segments, and hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) as hard segments. Their structure and properties were characterized to show that the products have nanoscale microphase separation, excellent wear-resistance and high resilience. PPCDL-PEG1000-TPUs have high tensile strength, high elongation at break, controllable hardness and excellent wear resistance when the content of hard segment is about 20%. Compared to PPCDL-TPU with only PPCDL as soft segment, the mechanical properties of TPU increase rather than decrease after the addition of PEG due to the crystallization behavior of PEG units in block copolymers. When the ratios of nPPCDL:nPEG are 10:1 and 4:1, the tensile strength of PPCDL-PEG1000-TPU reaches 27.5 MPa and 16.5 MPa (an increase of nearly 200% and 20% than PPCDL-TPU). The elongation at break reaches 1995% and 2485% (an increase of nearly 40% and 75% than PPCDL-TPU). Hardness of the prepared PPCDL-PEG1000-TPUs’ Shore A can be controlled in range of 70~85 by regulating the addition of PEG and their glass transition temperature (Tg) decreases with the increase of the amount of PEG incorporated. All PPCDL-PEG1000-TPUs exhibit good wear resistance with the average Akron wear volume of 12 mm3 after 4000 cycles of experiments according to national standards. PPCDL-PEG1000-TPUs show a high resilience performance with a negligible change in the hysteresis loop area after six cycles of tensile stretching. Furthermore, all PPCDL-PEG1000-TPUs possess high thermal stability, strong hydrophobicity, and low water absorption. This material has excellent application prospects and competitiveness in footwear and shock-absorbing materials. Full article
(This article belongs to the Section Polymer Analysis and Characterization)
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15 pages, 1315 KiB  
Article
Functionalisation of Lignin-Derived Diols for the Synthesis of Thermoplastic Polyurethanes and Polyester Resins
by Rachele N. Carafa, Justin J. S. Kosalka, Brigida V. Fernandes, Unnati Desai, Daniel A. Foucher and Guerino G. Sacripante
Molecules 2025, 30(12), 2604; https://doi.org/10.3390/molecules30122604 - 16 Jun 2025
Viewed by 449
Abstract
The functionalisation of lignin-derived phenolics (guaiacol, 4-propylguaiacol, eugenol, isoeugenol, phenol, m-cresol, catechol, syringol, syringaldehyde, and vanillin) for the synthesis of thermoplastic polyurethanes (PUs) and polyester (PE) resins is herein described. Diols were synthesised from phenolics in a one-step reaction using either glycerol [...] Read more.
The functionalisation of lignin-derived phenolics (guaiacol, 4-propylguaiacol, eugenol, isoeugenol, phenol, m-cresol, catechol, syringol, syringaldehyde, and vanillin) for the synthesis of thermoplastic polyurethanes (PUs) and polyester (PE) resins is herein described. Diols were synthesised from phenolics in a one-step reaction using either glycerol carbonate or ethylene carbonate as a greener, solvent-free synthetic route. Nine of the diols were selected for the synthesis of Pus, and two of the diols were used for the synthesis of PE resins, with their physical and thermal properties characterised. Analysis of the PUs by differential scanning calorimetry (DSC) confirmed their amorphous nature, while thermogravimetric analysis (TGA) suggested improved thermal stability for all PUs with the addition of an alkyl or aldehyde substituent on the benzene ring regardless of the diisocyanate used. However, lower PU thermal stabilities were observed with the use of an aliphatic diisocyanate over an aromatic diisocyanate in the absence of an additional substituent. Analysis of the PEs by DSC also confirmed that the clear resins were all amorphous, and gel permeation chromatography (GPC) revealed significantly higher molecular weights and dispersities when an aliphatic diacid was utilised over an aromatic diacid. Full article
(This article belongs to the Special Issue Advances in Polymer Materials Based on Lignocellulosic Biomass)
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16 pages, 1767 KiB  
Article
Common Food-Wrap Film as a Cost-Effective and Readily Available Alternative to Thermoplastic Polyurethane (TPU) Membranes for Microfluidic On-Chip Valves and Pumps
by Huu Anh Minh Nguyen, Mark Volosov, Jessica Maffei, Dae Jung Martins Cruz and Roman Voronov
Micromachines 2025, 16(6), 657; https://doi.org/10.3390/mi16060657 - 30 May 2025
Viewed by 2914
Abstract
Microfluidic devices rely on precise fluid control to enable complex operations in diagnostics, chemical synthesis, and biological research. Central to this control are microvalves, which regulate on-chip flow but require flexible membranes for active operation. While the laser cutting of thermoplastics offers a [...] Read more.
Microfluidic devices rely on precise fluid control to enable complex operations in diagnostics, chemical synthesis, and biological research. Central to this control are microvalves, which regulate on-chip flow but require flexible membranes for active operation. While the laser cutting of thermoplastics offers a fast, automated method for fabricating rigid microfluidic components, integrating flexible elements like valves and pumps remains a key challenge. Thermoplastic polyurethane (TPU) membranes have been adopted to address this need but are costly and difficult to procure reliably. In this study, we present commercial food-wrap film (FWF) as a low-cost, widely available alternative membrane material. We demonstrate FWF’s compatibility with laser-cut thermoplastic microfluidic devices by successfully fabricating Quake-style valves and peristaltic pumps. FWF valves maintained reliable sealing at 40 psi, maintained stable flow rates of ~1.33 μL/min during peristaltic operation, and sustained over one million continuous actuation cycles without performance degradation. Burst pressure testing confirmed robustness up to 60 psi. Additionally, FWF’s thermal resistance up to 140 °C enabled effective thermal bonding with PMMA layers, simplifying device assembly. These results establish FWF as a viable substitute for TPU membranes, offering an accessible and scalable solution for microfluidic device fabrication, particularly in resource-limited settings where TPU availability is constrained. Full article
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17 pages, 3434 KiB  
Article
Experimental Study of Comprehensive Performance Analysis Regarding the Dynamical/Mechanical Aspects of 3D-Printed UAV Propellers and Sound Footprint
by Florin Popișter
Polymers 2025, 17(11), 1466; https://doi.org/10.3390/polym17111466 - 25 May 2025
Viewed by 826
Abstract
The present study evaluates the viability of fabricating unmanned aerial vehicle (UAV) propellers using fused filament fabrication (FFF), with an emphasis on low-cost, desktop-scale production. The study’s backdrop is the recent adoption of UAVs and advancements in additive manufacturing. While the scope targets [...] Read more.
The present study evaluates the viability of fabricating unmanned aerial vehicle (UAV) propellers using fused filament fabrication (FFF), with an emphasis on low-cost, desktop-scale production. The study’s backdrop is the recent adoption of UAVs and advancements in additive manufacturing. While the scope targets accessibility for individual and small-scale users, the results have broader implications for scalable UAV propulsion systems. The research was conducted within an experimental UAV development framework aimed at optimizing propeller performance through strategic material selection, geometrical design optimization, and additive manufacturing processes. Six propeller variants were manufactured using widely available thermoplastic polymers, including polyethylene terephthalate glycol-modified (PETG) and thermoplastic polyurethane (TPU), as well as photopolymer-based propellers fabricated using vat photopolymerization, also known as digital light processing (DLP). Mechanical and aerodynamic characterizations were performed to assess the structural integrity, flexibility, and performance of each material under dynamic conditions. Two blade configurations, a toroidal propeller with anticipated aerodynamic advantages and a conventional tri-blade propeller (Gemfan 51466-3)—were comparatively analyzed. The primary contribution of this work is the systematic evaluation of performance metrics such as thrust generation, acoustic signature, mechanical strength, and thermal stress imposed on the electrical motor, thereby establishing a benchmark for polymer-based propeller fabrication via additive manufacturing. The findings underscore the potential of polymeric materials and layer-based manufacturing techniques in advancing the design and production of UAV propulsion components. Full article
(This article belongs to the Special Issue 3D Printing and Molding Study in Polymeric Materials)
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