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Ayubi BI, Zhang L, Zhou S, Wang Y, Zou L. Investigation of Partial Discharge Transformation Characteristics in Polyimide (PI) Insulations under High-Frequency Electric Stress. Polymers (Basel) 2024; 16:2450. [PMID: 39274082 PMCID: PMC11397631 DOI: 10.3390/polym16172450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2024] [Revised: 08/12/2024] [Accepted: 08/27/2024] [Indexed: 09/16/2024] Open
Abstract
This research delves into the primary issue of polyimide (PI) insulation failures in high-frequency power transformers (HFPTs) by scrutinizing partial discharge development under high-frequency electrical stress. This study employs an experimental approach coupled with a plasma simulation model for a ball-sphere electrode structure. The simulation model integrates the particle transport equation, Poisson equation, and complex chemical reactions to ascertain microscopic parameters, including plasma distribution, electric field, electron density, electron temperature, surface, and space charge distribution. The effect of the voltage polarity and electrical energy on the PD process is also discussed. The contact point plays a pivotal role in triggering partial discharges and culminating in the breakdown of PI insulation. Asymmetry phenomena were found between positive and negative half-cycles by analyzing the PD data stage by stage. A significant number of PDs increased at every stage and the PD amplitude was higher during the negative cycle at the initial stage, but in later stages, the PD amplitude was found to be higher in the positive half-cycle, and scanning electron microscopy (SEM) revealed that the maximum damage occurred near the contact point junction. The simulation results show that the plasma initially accumulates the electron density near the contact point junction. Under the action of the electric field, plasma starts traveling at the PI surface outward from the contact point. Before the PD activity, all parameters have higher values in the plasma head. The microscopic parameters reveal maximum values near the contact point junction, during PD activities where significant damage takes place. These parameter distributions exhibit a decreasing trend over time as when the PD activity ends. The model's predictions are consistent with the experimental data. The paper lays the foundation for future research in polymer insulation design under high-frequency electrical stress.
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Affiliation(s)
- Bilal Iqbal Ayubi
- School of Electrical Engineering, Shandong University, Jinan 250100, China
| | - Li Zhang
- School of Electrical Engineering, Shandong University, Jinan 250100, China
| | - Shengrui Zhou
- School of Electrical Engineering, Shandong University, Jinan 250100, China
| | - Yiwei Wang
- School of Electrical Engineering, Shandong University, Jinan 250100, China
| | - Liang Zou
- School of Electrical Engineering, Shandong University, Jinan 250100, China
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Damnjanović A, Primc G, Zaplotnik R, Mozetič M, Kovačević N. The Impact of Plasma Surface Treatments on the Mechanical Properties and Magnetic Performance of FDM-Printed NdFeB/PA12 Magnets. MATERIALS (BASEL, SWITZERLAND) 2024; 17:2275. [PMID: 38793342 PMCID: PMC11122891 DOI: 10.3390/ma17102275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 05/06/2024] [Accepted: 05/08/2024] [Indexed: 05/26/2024]
Abstract
This study presents a novel approach for improving the interfacial adhesion between Nd-Fe-B spherical magnetic powders and polyamide 12 (PA12) in polymer-bonded magnets using plasma treatments. By applying radio frequency plasma to the magnetic powder and low-pressure microwave plasma to PA12, we achieved a notable enhancement in the mechanical and environmental stability of fused deposition modeling (FDM)-printed Nd-Fe-B/PA12 magnets. The densities of the FDM-printed materials ranged from 92% to 94% of their theoretical values, with magnetic remanence (Br) ranging from 85% to 89% of the theoretical values across all batches. The dual plasma-treated batch demonstrated an optimal mechanical profile with an elastic modulus of 578 MPa and the highest ductility at 21%, along with a tensile strength range of 6 to 7 MPa across all batches. Flexural testing indicated that this batch also achieved the highest flexural strength of 15 MPa with a strain of 5%. Environmental stability assessments confirmed that applied plasma treatments did not compromise resistance to corrosion, evidenced by negligible flux loss in both hygrothermal and bulk corrosion tests. These results highlight plasma treatment's potential to enhance mechanical strength, magnetic performance, and environmental stability.
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Affiliation(s)
- Ana Damnjanović
- Kolektor Mobility d.o.o., SI-5280 Idrija, Slovenia;
- Jožef Stefan International Postgraduate School, SI-1000 Ljubljana, Slovenia
| | - Gregor Primc
- Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia; (G.P.); (R.Z.); (M.M.)
| | - Rok Zaplotnik
- Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia; (G.P.); (R.Z.); (M.M.)
| | - Miran Mozetič
- Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia; (G.P.); (R.Z.); (M.M.)
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Bahrami M, del Real JC, Mehdikhani M, Butenegro JA, Abenojar J, Martínez MÁ. Hybridization Effect on Interlaminar Bond Strength, Flexural Properties, and Hardness of Carbon-Flax Fiber Thermoplastic Bio-Composites. Polymers (Basel) 2023; 15:4619. [PMID: 38139872 PMCID: PMC10748188 DOI: 10.3390/polym15244619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 11/30/2023] [Accepted: 12/01/2023] [Indexed: 12/24/2023] Open
Abstract
Hybridizing carbon-fiber-reinforced polymers with natural fibers could be a solution to prevent delamination and improve the out-of-plane properties of laminated composites. Delamination is one of the initial damage modes in composite laminates, attributed to relatively poor interlaminar mechanical properties, e.g., low interlaminar strength and fracture toughness. This study examined the interlaminar bond strength, flexural properties, and hardness of carbon/flax/polyamide hybrid bio-composites using peel adhesion, three-point bending, and macro-hardness tests, respectively. In this regard, interlayer hybrid laminates were produced with a sandwich fiber hybrid mode, using woven carbon fiber plies (C) as the outer layers and woven flax fiber plies (F) as the inner ones (CFFC) in combination with a bio-based thermoplastic polyamide 11 matrix. In addition, non-hybrid carbon and flax fiber composites with the same matrix were produced as reference laminates to investigate the hybridization effects. The results revealed the advantages of hybridization in terms of flexural properties, including a 212% higher modulus and a 265% higher strength compared to pure flax composites and a 34% higher failure strain compared to pure carbon composites. Additionally, the hybrid composites exhibited a positive hybridization effect in terms of peeling strength, demonstrating a 27% improvement compared to the pure carbon composites. These results provide valuable insights into the mechanical performance of woven carbon-flax hybrid bio-composites, suggesting potential applications in the automotive and construction industries.
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Affiliation(s)
- Mohsen Bahrami
- Materials Science and Engineering and Chemical Engineering Department, University Carlos III de Madrid, 28911 Leganes, Spain; (J.A.B.); (J.A.); (M.Á.M.)
| | - Juan Carlos del Real
- Institute for Research in Technology, Mechanical Engineering Department, ICAI, Universidad Pontificia Comillas, 28015 Madrid, Spain;
| | - Mahoor Mehdikhani
- Department of Materials Engineering, KU Leuven, 3001 Leuven, Belgium;
| | - José Antonio Butenegro
- Materials Science and Engineering and Chemical Engineering Department, University Carlos III de Madrid, 28911 Leganes, Spain; (J.A.B.); (J.A.); (M.Á.M.)
| | - Juana Abenojar
- Materials Science and Engineering and Chemical Engineering Department, University Carlos III de Madrid, 28911 Leganes, Spain; (J.A.B.); (J.A.); (M.Á.M.)
- Institute for Research in Technology, Mechanical Engineering Department, ICAI, Universidad Pontificia Comillas, 28015 Madrid, Spain;
| | - Miguel Ángel Martínez
- Materials Science and Engineering and Chemical Engineering Department, University Carlos III de Madrid, 28911 Leganes, Spain; (J.A.B.); (J.A.); (M.Á.M.)
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Aktas C, Polat O, Beitollahpoor M, Farzam M, Pesika NS, Sahiner N. Force-Based Characterization of the Wetting Properties of LDPE Surfaces Treated with CF 4 and H 2 Plasmas. Polymers (Basel) 2023; 15:polym15092132. [PMID: 37177278 PMCID: PMC10181085 DOI: 10.3390/polym15092132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 04/21/2023] [Accepted: 04/27/2023] [Indexed: 05/15/2023] Open
Abstract
Low-density polyethylene (LDPE) films are widely used in packaging, insulation and many other commodity applications due to their excellent mechanical and chemical properties. However, the water-wetting and water-repellant properties of these films are insufficient for certain applications. In this study, bare LDPE and textured LDPE (T-LDPE) films were subjected to low-pressure plasmas, such as carbon tetrafluoride (CF4) and hydrogen (H2), to see the effect of plasma treatment on the wetting properties of LDPE films. In addition, the surface of the LDPE film was textured to improve the hydrophobicity through the lotus effect. The LDPE and T-LDPE films had contact angle (θ) values of 98.6° ± 0.6 and 143.6° ± 1.0, respectively. After CF4 plasma treatments, the θ values of the surfaces increased for both surfaces, albeit within the standard deviation for the T-LDPE film. On the other hand, the contact angle values after H2 plasma treatment decreased for both surfaces. The surface energy measurements supported the changes in the contact angle values: exposure to H2 plasma decreased the contact angle, while exposure to CF4 plasma increased the contact angle. Kinetic friction force measurements of water drops on LDPE and T-LDPE films showed a decrease in friction after the CF4 plasma treatment, consistent with the contact angle and surface energy measurements. Notably, the kinetic friction force measurements proved to be more sensitive compared to the contact angle measurements in differentiating the wetting properties of the T-LDPE versus 3× CF4-plasma-treated LDPE films. Based on Atomic Force Microscopy (AFM) images of the flat LDPE samples, the 3× CF4 plasma treatment did not significantly change the surface morphology or roughness. However, in the case of the T-LDPE samples, Scanning Electron Microscopy (SEM) images showed noticeable morphological changes, which were more significant at sharp edges of the surface structures.
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Affiliation(s)
- Cihan Aktas
- Department of Chemical, Biomolecular and Materials Engineering, University of South Florida, Tampa, FL 33620, USA
| | - Osman Polat
- Department of Chemical, Biomolecular and Materials Engineering, University of South Florida, Tampa, FL 33620, USA
| | | | - Melika Farzam
- Chemical and Biomolecular Engineering Department, Tulane University, New Orleans, LA 70118, USA
| | - Noshir S Pesika
- Chemical and Biomolecular Engineering Department, Tulane University, New Orleans, LA 70118, USA
| | - Nurettin Sahiner
- Department of Chemical, Biomolecular and Materials Engineering, University of South Florida, Tampa, FL 33620, USA
- Department of Ophthalmology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd, MDC21, Tampa, FL 33612, USA
- Department of Chemistry, Faculty of Science and Arts & Nanoscience, Technology Research and Application Center (NANORAC), Canakkale Onsekiz Mart University, Terzioglu Campus, 17100 Canakkale, Turkey
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Bahrami M, Abenojar J, Martínez MA. Comparative Characterization of Hot-Pressed Polyamide 11 and 12: Mechanical, Thermal and Durability Properties. Polymers (Basel) 2021; 13:3553. [PMID: 34685311 PMCID: PMC8537549 DOI: 10.3390/polym13203553] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 10/08/2021] [Accepted: 10/12/2021] [Indexed: 11/16/2022] Open
Abstract
Chemically speaking, polyamide 11 (PA11) and polyamide 12 (PA12) have a similar backbone, differing only in one carbon. From an origin point of view, PA11 is considered a bioplastic polyamide composed from renewable resources, compared to oil-based PA12. Each of them has a number of advantages over the other, which makes their selection a challenging issue. Depending on the target application, diverse assessments and comparisons are needed to fulfill this mission. The current study addresses this research gap to characterize and compare PA11 and PA12 manufactured by the hot press technique in terms of their mechanical, thermal and durability properties for the first time, demonstrating their potential for future works as matrices in composite materials. In this regard, different characterization techniques are applied to the hot-pressed polymer sheets, including X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The mechanical performance of the PA11 and PA12 sheets is compared based on tensile tests and shore hardness measurement. The durability behavior of these two polyamides is evaluated in water and relative humidity conditions at different aging times. The experimental results show the ductile behavior of PA12 with respect to the quasi-brittle PA11. Both have a relatively small water and moisture gain: 1.5 wt% and 0.8 wt%, respectively. The higher crystallinity of PA12 (2.1 times more than PA11) with γ-phase is one of the leading parameters to achieve better mechanical and durability properties. The FTIR spectra displayed slight acid hydrolysis. Accordingly, absorbed water or moisture does not cause plasticization; thus, neither hardness nor dimension changes.
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Affiliation(s)
- Mohsen Bahrami
- Materials Science and Engineering and Chemical Engineering Department, University Carlos III de Madrid, 28911 Leganes, Spain; (J.A.); (M.A.M.)
| | - Juana Abenojar
- Materials Science and Engineering and Chemical Engineering Department, University Carlos III de Madrid, 28911 Leganes, Spain; (J.A.); (M.A.M.)
- Mechanical Engineering Department, ICAI, Universidad Pontificia Comillas, 28015 Madrid, Spain
| | - Miguel Angel Martínez
- Materials Science and Engineering and Chemical Engineering Department, University Carlos III de Madrid, 28911 Leganes, Spain; (J.A.); (M.A.M.)
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Korzec D, Andres T, Brandes E, Nettesheim S. Visualization of Activated Area on Polymers for Evaluation of Atmospheric Pressure Plasma Jets. Polymers (Basel) 2021; 13:polym13162711. [PMID: 34451254 PMCID: PMC8401304 DOI: 10.3390/polym13162711] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/30/2021] [Accepted: 08/08/2021] [Indexed: 11/16/2022] Open
Abstract
The treatment of a polymer surface using an atmospheric pressure plasma jet (APPJ) causes a local increase of the surface free energy (SFE). The plasma-treated zone can be visualized with the use of a test ink and quantitatively evaluated. However, the inked area is shrinking with time. The shrinkage characteristics are collected using activation image recording (AIR). The recording is conducted by a digital camera. The physical mechanisms of activation area shrinkage are discussed. The error sources are analyzed and methods of error reduction are proposed. The standard deviation of the activation area is less than 3%. Three polymers, acrylonitrile butadiene styrene (ABS), high-density polyethylene (HDPE), and polyoxymethylene (POM), are examined as a test substrate material. Due to a wide variation range of SFE and a small hydrophobic recovery, HDPE is chosen. Since the chemical mixtures tend to temporal changes of the stoichiometry, the pure formamide test ink with 58 mN/m is selected. The method is tested for the characterization of five different types of discharge: (i) pulsed arc APPJ with the power of about 700 W; (ii) piezoelectric direct discharge APPJ; (iii) piezoelectric driven needle corona in ambient air; (iv) piezoelectric driven plasma needle in argon; and (v) piezoelectric driven dielectric barrier discharge (DBD). For piezoelectrically driven discharges, the power was either 4.5 W or 8 W. It is shown how the AIR method can be used to solve different engineering problems.
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Surface modification of PMMA polymer and its composites with PC 61BM fullerene derivative using an atmospheric pressure microwave argon plasma sheet. Sci Rep 2021; 11:9270. [PMID: 33927242 PMCID: PMC8084952 DOI: 10.1038/s41598-021-88553-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/14/2021] [Indexed: 11/26/2022] Open
Abstract
This paper presents the results of experimental investigations of the plasma surface modification of a poly(methyl methacrylate) (PMMA) polymer and PMMA composites with a [6,6]-phenyl-C61-butyric acid methyl ester fullerene derivative (PC61BM). An atmospheric pressure microwave (2.45 GHz) argon plasma sheet was used. The experimental parameters were: an argon (Ar) flow rate (up to 20 NL/min), microwave power (up to 530 W), number of plasma scans (up to 3) and, the kind of treated material. In order to assess the plasma effect, the possible changes in the wettability, roughness, chemical composition, and mechanical properties of the plasma-treated samples’ surfaces were evaluated by water contact angle goniometry (WCA), atomic force microscopy (AFM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The best result concerning the water contact angle reduction was from 83° to 29.7° for the PMMA material. The ageing studies of the PMMA plasma-modified surface showed long term (100 h) improved wettability. As a result of plasma treating, changes in the samples surface roughness parameters were observed, however their dependence on the number of plasma scans is irregular. The ATR-FTIR spectra of the PMMA plasma-treated surfaces showed only slight changes in comparison with the spectra of an untreated sample. The more significant differences were demonstrated by XPS measurements indicating the surface chemical composition changes after plasma treatment and revealing the oxygen to carbon ratio increase from 0.1 to 0.4.
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