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Polymers Dec 2023Improvement techniques aimed at enhancing the dielectric strength and minimizing the dielectric loss of insulation materials have piqued the interest of many...
Improvement techniques aimed at enhancing the dielectric strength and minimizing the dielectric loss of insulation materials have piqued the interest of many researchers. It is worth noting that the electrical breakdown traits of insulation material are determined by their electrochemical and mechanical performance. Possible good mechanical, electrical, and chemical properties of new materials are considered during the generation process. Thermoplastic polyurethane (TPU) is often used as a high-voltage insulator due to its favorable mechanical properties, high insulation resistance, lightweight qualities, recovery, large actuation strain, and cost-effectiveness. The elastomer structure of thermoplastic polyurethane (TPU) enables its application in a broad range of high-voltage (HV) insulation systems. This study aims to evaluate the feasibility of using TPU on transformer windings as a solid insulator instead of pressboards. The investigation conducted through experiments sheds light on the potential of TPU in expanding the range of insulating materials for HV transformers. Transformers play a crucial role in HV systems, hence the selection of suitable materials like cellulose and polyurethane is of utmost importance. This study involved the preparation of an experimental setup in the laboratory. Breakdown tests were conducted by generating a non-uniform electric field using a needle-plane electrode configuration in a test chamber filled with mineral oil. Various voltages ranging from 14.4 kV to 25.2 kV were applied to induce electric field stress with a step rise of 3.6 kV. The partial discharges and peak numbers were measured based on the predetermined threshold values. The study investigated and compared the behaviors of two solid insulating materials under differing non-electric field stress conditions. Harmonic component analysis was utilized to observe the differences between the two materials. Notably, at 21.6 kV and 25.2 kV, polyurethane demonstrated superior performance compared to pressboard with regards to the threshold value of leakage current.
PubMed: 38139923
DOI: 10.3390/polym15244671 -
Heliyon Aug 2023The preferable properties of indoor heat blockage material for tropical environments are blocking outside heat without absorbing and storing it inside the blockage...
The preferable properties of indoor heat blockage material for tropical environments are blocking outside heat without absorbing and storing it inside the blockage material, therefore studying the component and the composite properties are crucial. This study, therefore, aims to prepare and characterize a new hybrid foam concrete based on Rice Husk Ash (RHA) composite panels as an indoor building material called Hybrid Foam Panel (HFP). Polyurethane made of the combination of blended polyol (catalyst and surfactant) and diphenylmethane-4,4'-diisocyanate with a constant proportion was used as a matrix, while white Portland cement and RHA with various compositions were used as fillers. The formation of polyurethane foam and related chemical reactions are confirmed and RHA in HFP composition gave significant roles in composite properties. HFP made with the right constituent composition caused much lower thermal conductivity (down to 0.22 W/mK) than the control, blocked the IR radiation heat, and it has moderate compressive strength. HFP with RHA content in consolidated parameters shows a compressive strength of 7.25-12.37 MPa; densities of 1216-1351 kg/m and a porosity of 62%. HFP also stands for heat at least 300 °C, thereby it is a potential interior solar heat blockade, especially in the tropical region.
PubMed: 37593610
DOI: 10.1016/j.heliyon.2023.e18925 -
ACS Biomaterials Science & Engineering Nov 2023The solid-aqueous boundary formed upon biomaterial implantation provides a playground for most biochemical reactions and physiological processes involved in implant-host...
The solid-aqueous boundary formed upon biomaterial implantation provides a playground for most biochemical reactions and physiological processes involved in implant-host interactions. Therefore, for biomaterial development, optimization, and application, it is essential to understand the biomaterial-water interface in depth. In this study, oxygen plasma-functionalized polyurethane surfaces that can be successfully utilized in contact with the tissue of the respiratory system were prepared and investigated. Through experiments, the influence of plasma treatment on the physicochemical properties of polyurethane was investigated by atomic force microscopy, attenuated total reflection infrared spectroscopy, differential thermal analysis, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and contact angle measurements, supplemented with biological tests using the A549 cell line and two bacteria strains ( and ). The molecular interpretation of the experimental findings was achieved by molecular dynamics simulations employing newly developed, fully atomistic models of unmodified and plasma-functionalized polyurethane materials to characterize the polyurethane-water interfaces at the nanoscale in detail. The experimentally obtained polar and dispersive surface free energies were consistent with the calculated free energies, verifying the adequacy of the developed models. A 20% substitution of the polymeric chain termini by their oxidized variants was observed in the experimentally obtained plasma-modified polyurethane surface, indicating the surface saturation with oxygen-containing functional groups.
Topics: Polyurethanes; Biocompatible Materials; Surface Properties; Water; Oxygen
PubMed: 37909715
DOI: 10.1021/acsbiomaterials.3c01367 -
IScience Jul 2023Cartilage tissue engineering necessitates the right mechanical cues to regenerate impaired tissue. For this reason, bioreactors can be employed to induce joint-relevant...
Cartilage tissue engineering necessitates the right mechanical cues to regenerate impaired tissue. For this reason, bioreactors can be employed to induce joint-relevant mechanical loading, such as compression and shear. However, current articulating joint bioreactor designs are lacking in terms of sample size and usability. In this paper, we describe a new, simple-to-build and operate, multi-well kinematic load bioreactor and investigate its effect on the chondrogenic differentiation of human bone marrow-derived stem cells (MSCs). We seeded MSCs into a fibrin-polyurethane scaffold and subsequently exposed the samples to a combination of compression and shear for 25 days. The mechanical loading activates transforming growth factor beta 1, upregulates chondrogenic genes, and increases sulfated glycosaminoglycan retention within the scaffolds. Such a higher-throughput bioreactor could be operated in most cell culture laboratories, dramatically accelerating and improving the testing of cells, new biomaterials, and tissue-engineered constructs.
PubMed: 37408683
DOI: 10.1016/j.isci.2023.107092 -
Emergencias : Revista de La Sociedad... Oct 2023
Topics: Humans; Polyurethanes; Eating
PubMed: 37801425
DOI: 10.55633/s3me/E034.2023 -
Polymers Sep 2023Polyurethane elastomer (PUE), which is widely used in coatings for construction, transportation, electronics, aerospace, and other fields, has excellent physical... (Review)
Review
Polyurethane elastomer (PUE), which is widely used in coatings for construction, transportation, electronics, aerospace, and other fields, has excellent physical properties. However, polyurethane elastomers are flammable, which limits their daily use, so the flame retardancy of polyurethane elastomers is very important. Reactive flame retardants have the advantages of little influence on the physical properties of polymers and low tendency to migrate out. Due to the remarkable needs of non-halogenated flame retardants, phosphorus flame retardant has gradually stood out as the main alternative. In this review, we focus on the fire safety of PUE and provide a detailed overview of the current molecular design and mechanisms of reactive phosphorus-containing, as well as P-N synergistic, flame retardants in PUE. From the structural characteristics, several basic aspects of PUE are overviewed, including thermal performance, combustion performance, and mechanical properties. In addition, the perspectives on the future advancement of phosphorus-containing flame-retarded polyurethane elastomers (PUE) are also discussed. Based on the past research, this study provides prospects for the application of flame-retarded PUE in the fields of self-healing materials, bio-based materials, wearable electronic devices, and solid-state electrolytes.
PubMed: 37765565
DOI: 10.3390/polym15183711 -
ACS Omega Aug 2023The development of self-healing materials has gained significance in the medical field to enhance the longevity and reliability of medical devices and implants. Material... (Review)
Review
The development of self-healing materials has gained significance in the medical field to enhance the longevity and reliability of medical devices and implants. Material degradation caused by mechanical stress, environmental factors, and damage during use can lead to failure and necessitate manual inspection and maintenance. Self-healing materials, including polymers and elastomers, offer a promising solution by activating microdamage repair mechanisms. Polyurea coatings, known for their durability, flexibility, and versatility, have found widespread applications in various industries to prevent corrosion and abrasion and impact damage. This review focuses on the self-healing capability of polyurethane coatings and the efficacy of fabricated microcapsules. Experimental results elucidate the necessary conditions for achieving self-healing in polyurethane coatings encapsulated with suitable healing agents. These factors directly impact the self-healing potential of polyurea coatings and provide insights for medical device manufacturers seeking optimal coatings. The report also discusses challenges in fabrication and sample preparation, along with limitations of the project and recommendations for future research.
PubMed: 37546595
DOI: 10.1021/acsomega.3c02723 -
Materials (Basel, Switzerland) Oct 2023Based on flexible polyurethane foam (FPUF), which is reversible after compression, and expanded polystyrene foam (EPS), which has a high cushioning energy absorption...
Based on flexible polyurethane foam (FPUF), which is reversible after compression, and expanded polystyrene foam (EPS), which has a high cushioning energy absorption capacity, the parallel and series combinations of FPUF and EPS are provided. According to experimental data of FPUF and EPS uniaxial compression large deformation, the mechanical properties and cushioning effectiveness of the FPUF-EPS combination materials with different structural scale parameters were investigated by theory analysis and finite element simulation. The mechanical response and the cushioning effectiveness influencing factors of FPUF-EPS parallel (FE-P) and FPUF-EPS series (FE-S) combination materials under single compressive load, single-impact load, and multiple compressive loads were obtained. The differences in mechanical properties and cushioning effectiveness of FE-P, FE-S, FPUF, and EPS are analyzed. The influence law of structural scale parameters and load strength on the mechanical properties and cushioning effectiveness of FE-P and FE-S is provided. It indicates that the cushion properties of combination materials should be adjusted to satisfy product protection requirements. It is beneficial for the design optimization of cushioning and packaging protection.
PubMed: 37959483
DOI: 10.3390/ma16216886 -
Polymers Sep 2023The reuse of construction and demolition waste as a substitute for natural coarse aggregate in the production of recycled concrete has been widely used. In order to...
The reuse of construction and demolition waste as a substitute for natural coarse aggregate in the production of recycled concrete has been widely used. In order to study the capillary water absorption performance of waterborne-polyurethane-modified recycled aggregate concrete (WPUMRC), the effects of different curing systems, polymer-cement ratios, and waterborne polyurethane addition methods on the cumulative water absorption and the rate of capillary water absorption of WPUMRC were analyzed, and through MIP tests, the micro modification mechanism of waterborne polyurethane in recycled concrete was analyzed. The results indicate that the optimal curing system for both DC (waterborne polyurethane is added separately from water) and HC (waterborne polyurethane is mixed with some effective water and then added) is the 14 d standard curing-14 d indoor natural drying curing system. Waterborne polyurethane can fill the pores and micro-cracks inside WPUMRC or interweave with the hydration products of cement to form a spatial network structure, reducing the porosity, and thereby improving the capillary water absorption performance of WPUMRC. Based on the MIP test results, the grey correlation method was used to establish the relationship between capillary water absorption and the pore structure of WPUMRC under the optimal curing system. In addition, the prediction model of capillary water absorption in recycled concrete was established according to the test results, which can be used to predict WPUMRC's capillary water absorption performance.
PubMed: 37835909
DOI: 10.3390/polym15193860 -
Scientific Reports Oct 2023A theoretical study of urethane formation through the reaction of phenyl isocyanate and butan-1-ol was carried out, without and in the presence of morpholine, and...
A theoretical study of urethane formation through the reaction of phenyl isocyanate and butan-1-ol was carried out, without and in the presence of morpholine, and 4-methylmorpholine catalysts. The reaction with and without catalysts was studied at BHandHLYP/6-31G(d) and G3MP2BHandHLYP levels of theories. The reaction mechanism in the presence of catalysts differs significantly from the catalyst-free case and includes seven steps. The catalyst-free system was investigated along with the catalytic process, the geometries were optimized, and the corresponding thermodynamic properties were calculated. Calculated reactant complexes were compared with crystal structures of morpholine, and 4-methylmorpholine complexed with diols found in the literature. The structures were strikingly similar and thus, the validity of the proposed and studied general organocatalytic reaction mechanism was partially verified. Meanwhile, an irregularity in the energy profile occurred due to the zwitterionic nature of an intermediate. To handle the irregularity, a correction was implemented which handles the appearance of a zwitterionic structure and the corresponding energetic properties. The results showed that morpholine is less effective catalyst compared to 4-methylmorpholine, which can be associated with the difference in their PA (1523.95 and 963.07 kJ/mol, respectively). The current results prove the important role of amine catalysts in urethane synthesis which can be applied in polyurethane catalyst design and development.
PubMed: 37863884
DOI: 10.1038/s41598-023-44492-x