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Edwards TR, Shankar R, Smith PGH, Cross JA, Lequeux ZAB, Kemp LK, Qiang Z, Iacano ST, Morgan SE. β-Phase Crystallinity, Printability, and Piezoelectric Characteristics of Polyvinylidene Fluoride (PVDF)/Poly(methyl methacrylate) (PMMA)/Cyclopentyl-Polyhedral Oligomeric Silsesquioxane (Cp-POSS) Melt-Compounded Blends. ACS APPLIED POLYMER MATERIALS 2024; 6:5803-5813. [PMID: 38807951 PMCID: PMC11129178 DOI: 10.1021/acsapm.4c00468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 05/01/2024] [Accepted: 05/02/2024] [Indexed: 05/30/2024]
Abstract
Poly(vinylidene fluoride) (PVDF) is a semicrystalline polymer that exhibits unique piezoelectric characteristics along with good chemical resistance and high thermal stability. Layer-based material extrusion (MEX) 3D printing of PVDF is desired to create complex structures with piezoelectric properties; however, the melt processing of PVDF typically directs the formation of the α crystalline allomorph, which does not contribute to the piezoelectric response. In this work, PVDF was compounded with poly(methyl methacrylate) (PMMA) and cyclopentyl-polyhedral oligomeric silsesquioxane (Cp-POSS) nanostructured additives in binary and ternary blends to improve MEX printability while maintaining piezoelectric performance. Overall crystallinity and β phase content were evaluated and quantified using a combination of attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and differential scanning calorimetry (DSC). Enhancement of MEX printability was measured by quantifying the interlayer adhesion and warpage of printed parts. All blends studied contained a significant percentage of β allomorph, but it could be detected by ATR-FTIR only after the removal of a thin surface layer. Inclusion of 1% Cp-POSS and up to 10% PMMA in blends with PVDF improved interlayer adhesion (2.3-3.6x) and lowered warpage of MEX printed parts compared to neat PVDF. The blend of 1% Cp-POSS/1% PMMA/PVDF was demonstrated to significantly improve the quality of MEX printed parts while showing similar piezoelectric performance to that of neat PVDF (average piezoelectric coefficient 24 pC/N). MEX printing of PVDF blends directly into usable parts with significant piezoelectric performance while reducing the challenges of printing the semicrystalline polymer opens the potential for application in a number of high value sectors.
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Affiliation(s)
- Toby R. Edwards
- School
of Polymer Science and Engineering, University
of Southern Mississippi, 118 College Drive, #5050, Hattiesburg, Mississippi 39406, United States
| | - Rahul Shankar
- School
of Polymer Science and Engineering, University
of Southern Mississippi, 118 College Drive, #5050, Hattiesburg, Mississippi 39406, United States
| | - Paul G. H. Smith
- School
of Polymer Science and Engineering, University
of Southern Mississippi, 118 College Drive, #5050, Hattiesburg, Mississippi 39406, United States
| | - Jacob A. Cross
- School
of Polymer Science and Engineering, University
of Southern Mississippi, 118 College Drive, #5050, Hattiesburg, Mississippi 39406, United States
| | - Zoe A. B. Lequeux
- School
of Polymer Science and Engineering, University
of Southern Mississippi, 118 College Drive, #5050, Hattiesburg, Mississippi 39406, United States
| | - Lisa K. Kemp
- School
of Polymer Science and Engineering, University
of Southern Mississippi, 118 College Drive, #5050, Hattiesburg, Mississippi 39406, United States
| | - Zhe Qiang
- School
of Polymer Science and Engineering, University
of Southern Mississippi, 118 College Drive, #5050, Hattiesburg, Mississippi 39406, United States
| | - Scott T. Iacano
- Department
of Chemistry and Chemistry Research Center, United States Air Force Academy, 2355 Fairchild Drive, Suite 2N225, Colorado Springs, Colorado 80840, United States
| | - Sarah E. Morgan
- School
of Polymer Science and Engineering, University
of Southern Mississippi, 118 College Drive, #5050, Hattiesburg, Mississippi 39406, United States
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2
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Wei D, Zeng F, Cui J. Reactive Molecular Dynamics Study of the Mechanism and Effect of Various Protective Coatings on the Protection of Polyimide Antierosion from Atomic Oxygen. J Phys Chem A 2024; 128:378-391. [PMID: 38171542 DOI: 10.1021/acs.jpca.3c06406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Polyimide (PI), due to its exceptional performance, is commonly utilized in spacecraft. However, when such polymers are used in spacecraft navigating low Earth orbit, they are exposed to atomic oxygen (AO) that can cause the polymer to decompose. A protective coating method is a more effective way to safeguard the polymer from erosion caused by AO. This study employs the molecular dynamics simulation based on the reaction force field to investigate the protective effects of various coatings, including polydimethylsiloxane (PDMS), graphene (Gr), polytetrafluoroethylene (PTFE), and the (0 0 1), (0 1 1), and (1 1 1) surfaces of SiO2. The results indicate that the protective performance of the (0 1 1) surface is superior to that of the (0 0 1) and (1 1 1) surfaces. Moreover, protective coatings are classified into three categories based on different protective mechanisms: rebound, absorption, and sacrificial. The protective effectiveness of coatings depends on their anti-AO performance and ability to combine with the substrate. Gr displays exceptional anti-AO properties and can effectively shield the substrate from AO erosion. Silicone-based coatings have a superior ability to adhere to PI substrates, and PDMS is an excellent choice for protective coatings. This paper offers guidance for the protective coating method of PIs against AO erosion.
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Affiliation(s)
- Dahai Wei
- Department of Astronautic Science and Mechanics, Harbin Institute of Technology, Harbin 150006, People's Republic of China
| | - Fanlin Zeng
- Department of Astronautic Science and Mechanics, Harbin Institute of Technology, Harbin 150006, People's Republic of China
| | - Jianzheng Cui
- Department of Astronautic Science and Mechanics, Harbin Institute of Technology, Harbin 150006, People's Republic of China
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3
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Nguyen VP, Jeon I, Yang S, Choi ST. Mesoscale Simulation of Polymer Pyrolysis by Coarse-Grained Molecular Dynamics: A Parametric Study. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37307299 DOI: 10.1021/acsami.3c04192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Full comprehension of the pyrolysis of polymer materials is crucial for the design and application of thermal protection systems; however, it involves complex phenomena at different spatial and temporal scales. To bridge the gap between the abundant atomistic simulations and continuum modeling in the literature, we perform a novel mesoscale study of the pyrolysis process using coarse-grained molecular dynamics (CG MD) simulations. Polyethylene (PE) consisting of united atoms including implicit hydrogen is considered a model polymer, and the configurational change of PE in thermal degradation is modeled by applying the bond-breaking phenomenon based on bond energy or bond length criteria. A cook-off simulation is implemented to optimize the heuristic protocol of bond dissociation by comparing the reaction products with a ReaxFF simulation. The aerobic hyperthermal pyrolysis under oxygen bombardment is simulated at a large scale of hundreds of nanometers to observe the intricate phenomena occurring from the surface to the depth inside the material. The intrinsic thermal durability of the model polymer at extreme conditions with and without oxygen environment can be effectively simulated from the proposed mesoscale simulation to predict important thermal degradation properties required for continuum-scale pyrolysis and ablation simulations. This work serves as an initial investigation of polymer pyrolysis at the mesoscale and helps understand the concept at a larger scale.
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Affiliation(s)
- Vinh Phu Nguyen
- Functional Materials and Applied Mechanics Lab, School of Mechanical Engineering, Chung-Ang University, 84 Heukseok-Ro, Dongjak-Gu, Seoul 06974, Republic of Korea
| | - Inseok Jeon
- Mechanical Energy Engineering Division, School of Energy Systems Engineering, Chung-Ang University, 84 Heukseok-Ro, Dongjak-Gu, Seoul 06974, Republic of Korea
| | - Seunghwa Yang
- Mechanical Energy Engineering Division, School of Energy Systems Engineering, Chung-Ang University, 84 Heukseok-Ro, Dongjak-Gu, Seoul 06974, Republic of Korea
| | - Seung Tae Choi
- Functional Materials and Applied Mechanics Lab, School of Mechanical Engineering, Chung-Ang University, 84 Heukseok-Ro, Dongjak-Gu, Seoul 06974, Republic of Korea
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4
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Zhao W, Wei Q, Huang C, Zhu Y, Hu N. Dependence of Incidence Angle and Flux Density in the Damage Effect of Atomic Oxygen on Kapton Film. Polymers (Basel) 2022; 14:polym14245444. [PMID: 36559810 PMCID: PMC9781240 DOI: 10.3390/polym14245444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 11/27/2022] [Accepted: 12/09/2022] [Indexed: 12/15/2022] Open
Abstract
Kapton film is a polymeric material widely used on low-Earth-orbit (LEO) spacecraft surfaces. In the LEO environment, atomic oxygen (AO) is spaceflight materials' most destructive environmental factor. The erosion mechanism of AO on Kapton films has long been an important issue, where the parameter dependence of the AO effect has received increasing attention. Studies of AO energy and cumulative flux have been extensively carried out, while the influence mechanism of the incidence angle and flux density is not fully understood. The AO incidence angle and flux density in space are diverse, which may cause different damage effects on aerospace materials. In this paper, the dependence of the incidence angle and flux density in the damaging effect of AO on Kapton films was investigated using ground-based AO test technology and the reactive molecular dynamics (ReaxFF MD) simulation technique. Firstly, the ground-based experiment obtained the mass loss data of Kapton films under the action of AO with a variable incidence angle and flux density. Then, the mass loss, temperature rise, product, and erosion yield of Kapton during AO impact with different incidence angles and dose rates were calculated using the ReaxFF MD method. The influences of the incidence angle and flux density on the damage mechanism of the AO effect were discussed by comparing the simulation and test results. The results show that the AO effect in the lower incidence angle range (0-60°) is independent of the incidence angle and depends only on the amount of impacted atomic oxygen. AO in the higher incidence angle range (60-90°) has a surface stripping effect, which causes more significant mass loss and a temperature rise while stripping raised macromolecules from rough surfaces, and the erosion effect increases with the increasing incidence angle and amount of impacted atomic oxygen. There is a critical value for the influence of flux density on the AO effect. Above this critical value, AO has a reduced erosive capacity due to a lower chance of participating in the reaction. The amount of each main product from the AO effect varies with the incidence angle and flux density. Nonetheless, the total content of the main products is essentially constant, around 70%. This work will contribute to our understanding of the incidence angle and flux density dependence of the AO effect and provide valuable information for the development of standards for ground simulation tests.
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Affiliation(s)
- Wang Zhao
- Key Laboratory of Hebei Province on Scale-Span Intelligent Equipment Technology, School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China
| | - Qiang Wei
- Key Laboratory of Hebei Province on Scale-Span Intelligent Equipment Technology, School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China
- State Key Laboratory of Reliability and Intelligence Electrical Equipment, Hebei University of Technology, Tianjin 300401, China
- Correspondence:
| | - Chuanjin Huang
- Key Laboratory of Hebei Province on Scale-Span Intelligent Equipment Technology, School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China
| | - Yaoshun Zhu
- Key Laboratory of Hebei Province on Scale-Span Intelligent Equipment Technology, School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China
| | - Ning Hu
- Key Laboratory of Hebei Province on Scale-Span Intelligent Equipment Technology, School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China
- State Key Laboratory of Reliability and Intelligence Electrical Equipment, Hebei University of Technology, Tianjin 300401, China
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5
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The effects of atomic oxygen and ion irradiation degradation on multi-polymers: A combined ground-based exposure and ReaxFF-MD simulation. Polym Degrad Stab 2022. [DOI: 10.1016/j.polymdegradstab.2022.110134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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6
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Zhang Y, Li Q, Yuan H, Yan W, Chen S, Qiu M, Liao B, Chen L, Ouyang X, Zhang X, Ying M. Mechanically Robust Irradiation, Atomic Oxygen, and Static-Durable CrO x/CuNi Coatings on Kapton Serving as Space Station Solar Cell Arrays. ACS APPLIED MATERIALS & INTERFACES 2022; 14:21461-21473. [PMID: 35475345 DOI: 10.1021/acsami.2c03123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The polymers that served for solar cell arrays are constantly subject to various hazards, such as atomic oxygen (AO), ion irradiation, or electrostatic discharge (ESD) events. To address these issues, we fabricated and sifted CrO0.16/CuNi-coated Kapton with a gradient structure with the goal of reaching an equilibrium between AO durability and resistance. The resulting material exhibits an impressively low Ey of 6.61 × 10-26 cm3 atom-1, 2.20% of which was detected as pristine Kapton. Self-evolution of the CrO0.16 coating under 525.4 displacement per atom (dpa) Fe+ ion irradiation indicated that it can still maintain a good state of ultrafine nanocrystalline in addition to local amorphization. Its AO-based degradation and irradiation evolution are demonstrated by molecular dynamics (MD) simulations. It is mechanically robust enough to endure the cyclic folding treatments attributed to its gradient structure fabrication. Moreover, the CrO0.16/CuNi-coated Kapton exhibits alleviated electrostatic accumulation capability and sufficient conductivity. Our strategy has promising potential for creating surface protection on flexible polymers operating in the low Earth orbit (LEO).
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Affiliation(s)
- Yifan Zhang
- Key Laboratory of Beam Technology of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
| | - Qian Li
- Key Laboratory of Beam Technology of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
| | - Heng Yuan
- Key Laboratory of Beam Technology of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
| | - Weiqing Yan
- Key Laboratory of Beam Technology of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
| | - Shunian Chen
- Key Laboratory of Beam Technology of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
| | - Menglin Qiu
- Key Laboratory of Beam Technology of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
| | - Bin Liao
- Key Laboratory of Beam Technology of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
| | - Lin Chen
- Key Laboratory of Beam Technology of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
| | - Xiao Ouyang
- Key Laboratory of Beam Technology of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
| | - Xu Zhang
- Key Laboratory of Beam Technology of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
| | - Minju Ying
- Key Laboratory of Beam Technology of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
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Marmolejo-Tejada JM, De La Roche-Yepes J, Pérez-López CA, Taborda JAP, Ávila A, Jaramillo-Botero A. Understanding the Origin of Enhanced Piezoelectric Response in PVDF Matrices with Embedded ZnO Nanoparticles, from Polarizable Molecular Dynamics Simulations. J Chem Inf Model 2021; 61:4537-4543. [PMID: 34519202 DOI: 10.1021/acs.jcim.1c00822] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The pervasive use of portable electronic devices, powered from rechargeable batteries, represents a significant portion of the electricity consumption in the world. A sustainable and alternative energy source for these devices would require unconventional power sources, such as harvesting kinetic/potential energy from mechanical vibrations, ultrasound waves, and biomechanical motion, to name a few. Piezoelectric materials transform mechanical deformation into electric fields or, conversely, external electric fields into mechanical motion. Therefore, accurate prediction of elastic and piezoelectric properties of materials, from the atomic structure and composition, is essential for studying and optimizing new piezogenerators. Here, we demonstrate the application of harmonic-covalent and reactive force fields (FF), Dreiding and ReaxFF, respectively, coupled to the polarizable charge equilibration (PQEq) model for predicting the elastic moduli and piezoelectric response of crystalline zinc oxide (ZnO) and polyvinylidene difluoride (PVDF). Furthermore, we parametrized the ReaxFF atomic interactions for Zn-F in order to characterize the interfacial effects in hybrid PVDF matrices with embedded ZnO nanoparticles (NPs). We capture the nonlinear piezoelectric behavior of the PVDF-ZnO system at different ZnO concentrations and the enhanced response that was recently observed experimentally, between 5 and 7 wt % ZnO concentrations. From our simulation results, we demonstrate that the origin of this enhancement is due to an increase in the total atomic stress distribution at the interface between the two materials. This result provides valuable insight into the design of new and improved piezoelectric nanogenerators and demonstrates the practical value of these first-principles based modeling methods in materials science.
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Affiliation(s)
- Juan M Marmolejo-Tejada
- Omicas Program, Pontificia Universidad Javeriana, Cali 760031, Colombia.,Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | | | - Carlos A Pérez-López
- Centro de Microelectrónica (CMUA), Departamento de Ingeniería Eléctrica y Electrónica, Universidad de los Andes, Bogotá 111711, Colombia
| | - Jaime A Pérez Taborda
- Centro de Microelectrónica (CMUA), Departamento de Ingeniería Eléctrica y Electrónica, Universidad de los Andes, Bogotá 111711, Colombia
| | - Alba Ávila
- Centro de Microelectrónica (CMUA), Departamento de Ingeniería Eléctrica y Electrónica, Universidad de los Andes, Bogotá 111711, Colombia
| | - Andres Jaramillo-Botero
- Omicas Program, Pontificia Universidad Javeriana, Cali 760031, Colombia.,Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, United States
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8
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Yu C, Ju P, Wan H, Chen L, Li H, Zhou H, Chen J. Tribological properties of the polyacrylate/PTFE coating modified by POSS in the space environment. J Appl Polym Sci 2020. [DOI: 10.1002/app.48730] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Chuanyong Yu
- State Key Laboratory of Solid LubricationLanzhou Institute of Chemical Physics, Chinese Academy of Sciences Lanzhou 730000 China
- Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of Sciences Beijing 100049 China
| | - Pengfei Ju
- Shanghai Aerospace Equipment Manufacture Shanghai 200245 China
| | - Hongqi Wan
- State Key Laboratory of Solid LubricationLanzhou Institute of Chemical Physics, Chinese Academy of Sciences Lanzhou 730000 China
| | - Lei Chen
- State Key Laboratory of Solid LubricationLanzhou Institute of Chemical Physics, Chinese Academy of Sciences Lanzhou 730000 China
- Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of Sciences Beijing 100049 China
| | - Hongxuan Li
- State Key Laboratory of Solid LubricationLanzhou Institute of Chemical Physics, Chinese Academy of Sciences Lanzhou 730000 China
- Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of Sciences Beijing 100049 China
| | - Huidi Zhou
- State Key Laboratory of Solid LubricationLanzhou Institute of Chemical Physics, Chinese Academy of Sciences Lanzhou 730000 China
- Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of Sciences Beijing 100049 China
| | - Jianmin Chen
- State Key Laboratory of Solid LubricationLanzhou Institute of Chemical Physics, Chinese Academy of Sciences Lanzhou 730000 China
- Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of Sciences Beijing 100049 China
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9
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Liu Y, Wu X, Sun Y, Xie W. POSS Dental Nanocomposite Resin: Synthesis, Shrinkage, Double Bond Conversion, Hardness, and Resistance Properties. Polymers (Basel) 2018; 10:E369. [PMID: 30966404 PMCID: PMC6415207 DOI: 10.3390/polym10040369] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 03/23/2018] [Accepted: 03/23/2018] [Indexed: 11/16/2022] Open
Abstract
Nanocomposite dental resins with 0, 2, 5, and 10 wt % methacryl polyhedral oligomeric silsesquioxane (POSS) as filler in the resin matrix were prepared by a light curing method.The atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR), nanoindentation, and nanoscratch tests were carried out to study the effect of POSS contents on the compatibility, double bond conversion, volumetric shrinkage, hardness, modulus, and resistance of the dental resins. POSS was very uniformly dispersed and showed a good compatibility with the matrix. The double bond conversion increased and the volume reduced with the addition of POSS. As the POSS addition increased, the mechanical properties increased initially. Small addition of POSS remarkably enhanced the hardness and scratch resistance of the resin matrix.
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Affiliation(s)
- Yizhi Liu
- Department of Astronautic Science and Mechanics, Harbin Institute of Technology, Harbin 150001, China.
| | - Xiaorong Wu
- Department of Astronautic Science and Mechanics, Harbin Institute of Technology, Harbin 150001, China.
| | - Yi Sun
- Department of Astronautic Science and Mechanics, Harbin Institute of Technology, Harbin 150001, China.
| | - Weili Xie
- Department of Stomatology, Harbin Medical University, Harbin 150001, China.
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10
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Rahmani F, Nouranian S, Li X, Al-Ostaz A. Reactive Molecular Simulation of the Damage Mitigation Efficacy of POSS-, Graphene-, and Carbon Nanotube-Loaded Polyimide Coatings Exposed to Atomic Oxygen Bombardment. ACS APPLIED MATERIALS & INTERFACES 2017; 9:12802-12811. [PMID: 28322054 DOI: 10.1021/acsami.7b02032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Reactive molecular dynamics simulation was employed to compare the damage mitigation efficacy of pristine and polyimide (PI)-grafted polyoctahedral silsesquioxane (POSS), graphene (Gr), and carbon nanotubes (CNTs) in a PI matrix exposed to atomic oxygen (AO) bombardment. The concentration of POSS and the orientation of Gr and CNT nanoparticles were further investigated. Overall, the mass loss, erosion yield, surface damage, AO penetration depth, and temperature evolution are lower for the PI systems with randomly oriented CNTs and Gr or PI-grafted POSS compared to those of the pristine POSS or aligned CNT and Gr systems at the same nanoparticle concentration. On the basis of experimental early degradation data (before the onset of nanoparticle damage), the amount of exposed PI, which has the highest erosion yield of all material components, on the material surface is the most important parameter affecting the erosion yield of the hybrid material. Our data indicate that the PI systems with randomly oriented Gr and CNT nanoparticles have the lowest amount of exposed PI on the material surface; therefore, a lower erosion yield is obtained for these systems compared to that of the PI systems with aligned Gr and CNT nanoparticles. However, the PI/grafted-POSS system has a significantly lower erosion yield than that of the PI systems with aligned Gr and CNT nanoparticles, again due to a lower amount of exposed PI on the surface. When comparing the PI systems loaded with PI-grafted POSS versus pristine POSS at low and high nanoparticle concentrations, our data indicate that grafting the POSS and increasing the POSS concentration lower the erosion yield by a factor of about 4 and 1.5, respectively. The former is attributed to a better dispersion of PI-grafted POSS versus that of the pristine POSS in the PI matrix, as determined by the radial distribution function.
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Affiliation(s)
- Farzin Rahmani
- Department of Chemical Engineering and ‡Department of Civil Engineering, University of Mississippi , Mississippi 38677, United States
| | - Sasan Nouranian
- Department of Chemical Engineering and ‡Department of Civil Engineering, University of Mississippi , Mississippi 38677, United States
| | - Xiaobing Li
- Department of Chemical Engineering and ‡Department of Civil Engineering, University of Mississippi , Mississippi 38677, United States
| | - Ahmed Al-Ostaz
- Department of Chemical Engineering and ‡Department of Civil Engineering, University of Mississippi , Mississippi 38677, United States
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