Sample records for electro-active polymers pvdf
-
Fabrication and actuation of electro-active polymer actuator based on PSMI-incorporated PVDF
Lu, Jun; Kim, Sang-Gyun; Lee, Sunwoo; Oh, Il-Kwon
2008-08-01
In this study, an ionic networking membrane (INM) of poly(styrene-alt-maleimide) (PSMI)-incorporated poly(vinylidene fluoride) (PVDF) was applied to fabricate electro-active polymer. Based on the same original membrane of PSMI-incorporated PVDF, various samples of INM actuator were prepared for different reduction times with the electroless-plating technique. The as-prepared INM actuators were tested in terms of surface resistance, platinum morphology, resonance frequency, tip displacement, current and blocked force, and their performances were compared to those of the widely used traditional Nafion actuator. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that much smaller and more uniform platinum particles were formed on the surfaces of the INM actuators as well as within their polymer matrix. Although excellent harmonic responses were observed for the newly developed INM actuators, they were found to be sensitive to the applied reduction times during the fabrication. The mechanical displacement of the INM actuator fabricated after the optimum reduction times was much larger than that of its Nafion counterpart of comparable thickness under the stimulus of constant and alternating current voltage. The PSMI-incorporated PVDF actuator can become a promising smart material to be used in the fields of biomimetic robots, biomedical devices, sensors and actuator, haptic interfaces, energy harvesting and so on.
-
Fabrication and actuation of electro-active polymer actuator based on PSMI-incorporated PVDF
International Nuclear Information System (INIS)
Lu, Jun; Oh, Il-Kwon; Kim, Sang-Gyun; Lee, Sunwoo
2008-01-01
In this study, an ionic networking membrane (INM) of poly(styrene-alt-maleimide) (PSMI)-incorporated poly(vinylidene fluoride) (PVDF) was applied to fabricate electro-active polymer. Based on the same original membrane of PSMI-incorporated PVDF, various samples of INM actuator were prepared for different reduction times with the electroless-plating technique. The as-prepared INM actuators were tested in terms of surface resistance, platinum morphology, resonance frequency, tip displacement, current and blocked force, and their performances were compared to those of the widely used traditional Nafion actuator. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that much smaller and more uniform platinum particles were formed on the surfaces of the INM actuators as well as within their polymer matrix. Although excellent harmonic responses were observed for the newly developed INM actuators, they were found to be sensitive to the applied reduction times during the fabrication. The mechanical displacement of the INM actuator fabricated after the optimum reduction times was much larger than that of its Nafion counterpart of comparable thickness under the stimulus of constant and alternating current voltage. The PSMI-incorporated PVDF actuator can become a promising smart material to be used in the fields of biomimetic robots, biomedical devices, sensors and actuator, haptic interfaces, energy harvesting and so on
-
Conservation of the piezoelectric response of PVDF films under irradiation
Melilli, G.; Lairez, D.; Gorse, D.; Garcia-Caurel, E.; Peinado, A.; Cavani, O.; Boizot, B.; Clochard, M.-C.
2018-01-01
As opposed to piezo-ceramics (i.e PZT), flexibility and robustness characterize piezoelectric polymers. The main advantage of a piezoelectric polymer, such as Poly (vinylidene fluoride) (PVDF), is an electric power generation under large reversible elastic deformation. Starting from polarized PVDF, we have shown that, despite the fact that irradiation is known to structurally modify the PVDF by introducing defects (radicals, chain scission and crosslinks), the electro-active properties were not affected. At doses lower than 100 kGy, a comparison between swift heavy-ion (SHI) and e-beam irradiations is presented. A homemade device was realized to measure the output voltage as a function of the bending deformation for irradiated and non-irradiated PVDF film. DSC and FT-IR techniques give new insights on which crystalline part or structural change contributes to the conservation of the output voltage. Results suggest that despite the material after irradiation is composed of smaller crystallites, the β-phase content remains stable around 36%, which explains the remarkable preservation of the piezoelectric response in irradiated polarized PVDF films.
-
Directory of Open Access Journals (Sweden)
G. P. Zheng
2016-09-01
Full Text Available Three-dimensional nanoporous graphene monoliths are utilized to prepare graphene-poly(vinylidene fluoride nanocomposites with enhanced mechanical and electro-mechanical properties. Pre-treatment of the polymer (poly(vinylidene fluoride, PVDF with graphene oxides (GOs facilitates the formation of uniform and thin PVDF films with a typical thickness below 100 nm well coated at the graphene nano-sheets. Besides their excellent compressibility, ductility and mechanical strength, the nanoporous graphene-PVDF nanocomposites are found to possess high sensitivity in strain-dependent electrical conductivity. The improved mechanical and electro-mechanical properties are ascribed to the enhanced crystalline β phase in PVDF which possesses piezoelectricity. The mechanical relaxation analyses on the interfaces between graphene and PVDF reveal that the improved mechanical and electro-mechanical properties could result from the interaction between the –C=O groups in the nanoporous graphene and the –CF2 groups in PVDF, which also explains the important role of GOs in the preparation of the graphene-polymer nanocomposites with superior combined mechanical and electro-mechanical properties.
-
Electro-optic polymers for high speed modulators
Balakrishnan, M.; Diemeer, Mart; Driessen, A.; Faccini, M.; Verboom, Willem; Reinhoudt, David; Leinse, Arne; Megret, P.; Wuilpart, M.; Bette, S.; Staquet, N.
2005-01-01
Different electro-optic polymer systems are analyzed with respect to their electro-optic activity, glass transition temperature $(T_g)$ and photodefinable properties. The polymers tested are polysulfone (PS) and polycarbonate (PC). The electro-optic chromophore,
-
Investigation of ionic conduction in PEO-PVDF based blend polymer electrolytes
Patla, Subir Kumar; Ray, Ruma; Asokan, K.; Karmakar, Sanat
2018-03-01
We investigate the effect of blend host polymer on solid polymer electrolyte (SPE) films doped with ammonium iodide (NH4I) salt using a variety of experimental techniques. Structural studies on the composite SPEs show that the blending of Poly(ethylene oxide) (PEO)-Poly(vinylidene fluoride) (PVDF) polymers in a suitable ratio enhances the amorphous fraction of the polymer matrix and facilitates fast ion conduction through it. We observe that the addition of a small amount of PVDF in the PEO host polymer enhances the ion - polymer interaction leading to more ion dissociation. As a result, the effective number of mobile charge carriers within the polymer matrix increases. Systematic investigation in these blend SPEs shows that the maximum conductivity (1.01 × 10-3 S/cm) is obtained for PEO - rich (80 wt. % PEO, 20 wt. % PVDF) composites at 35 wt. % NH4I concentration at room temperature. Interestingly, at higher salt concentrations (above 35 wt. %), the conductivity is found to decrease in this system. The reduction of conductivity at higher salt concentrations is the consequence of decrease in the carrier concentration due to the formation of an ion pair and ion aggregates. PVDF-rich compositions (20 wt. % PEO and 80 wt. % PVDF), on the other hand, show a very complex porous microstructure. We also observe a much lower ionic conductivity (maximum ˜ 10-6 S/cm at 15 wt. % salt) in these composite systems relative to PEO-rich composites.
-
Energy Harvesting Cycles of Dielectric ElectroActive Polymer Generators
DEFF Research Database (Denmark)
Dimopoulos, Emmanouil; Trintis, Ionut; Munk-Nielsen, Stig
2012-01-01
Energy harvesting via Dielectric ElectroActive Polymer (DEAP) generators has attracted much of the scientific interest over the past few years, mainly due to the advantages that these smart materials offer against competing technologies, as electromagnetic generators and piezoelectrics. Their hig......Energy harvesting via Dielectric ElectroActive Polymer (DEAP) generators has attracted much of the scientific interest over the past few years, mainly due to the advantages that these smart materials offer against competing technologies, as electromagnetic generators and piezoelectrics....... Their higher energy density, superior low-speed performance, light-weighted nature as well as their shapely structure have rendered DEAPs candidate solutions for various actuation and energy harvesting applications. In this paper, a thoroughly analysis of all energy harvesting operational cycles of a DEAP...
-
The Jellyfish: smart electro-active polymers for an autonomous distributed sensing node
Blottman, John B.; Richards, Roger T.
2006-05-01
The US Navy has recently placed emphasis on deployable, distributed sensors for Force Protection, Anti-Terrorism and Homeland Defense missions. The Naval Undersea Warfare Center has embarked on the development of a self-contained deployable node that is composed of electro-active polymers (EAP) for use in a covert persistent distributed surveillance system. Electro-Active Polymers (EAP) have matured to a level that permits their application in energy harvesting, hydrophones, electro-elastic actuation and electroluminescence. The problem to resolve is combining each of these functions into an autonomous sensing platform. The concept presented here promises an operational life several orders of magnitude beyond what is expected of a Sonobuoy due to energy conservation and harvesting, and at a reasonable cost. The embodiment envisioned is that of a deployed device resembling a jellyfish, made in most part of polymers, with the body encapsulating the necessary electronic processing and communications package and the tentacles of the jellyfish housing the sonar sensors. It will be small, neutrally buoyant, and will survey the water column much in the manner of a Cartesian Diver. By using the Electro-Active Polymers as artificial muscles, the motion of the jellyfish can be finely controlled. An increased range of detection and true node autonomy is achieved through volumetric array beamforming to focus the direction of interrogation and to null-out extraneous ambient noise.
-
Energy Technology Data Exchange (ETDEWEB)
Blinov, L. M., E-mail: lev39blinov@gmail.com; Lazarev, V V; Palto, S P; Yudin, S G [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)
2012-04-15
The low-frequency quadratic electro-optical effect with a maximum electro-optical coefficient of g = 8 Multiplication-Sign 10{sup -19} m{sup 2}/V{sup 2} (i.e., four orders of magnitude greater than the standard high-frequency value) has been studied in thin films of ferroelectric polymer PVDF(70%)-TrFE(30%). The observed effect is related to the process of spontaneous polarization switching, during which the electron oscillators of C-F and C-H dipole groups rotate to become parallel to the applied field. As a result, the ellipsoid of the refractive index exhibits narrowing in the direction perpendicular to the field. The field dependence of the electro-optical coefficient g correlates with that of the apparent dielectric permittivity, which can be introduced under the condition of ferroelectric polarization switching. The observed electro-optical effect strongly decreases when the frequency increases up to several hundred hertz. The temperature dependence of the effect exhibits clearly pronounced hysteresis in the region of the ferroelectric phase transition.
-
International Nuclear Information System (INIS)
Lee, ChaBum; Tarbutton, Joshua A
2014-01-01
This paper presents a new additive manufacturing (AM) process to directly and continuously print piezoelectric devices from polyvinylidene fluoride (PVDF) polymeric filament rods under a strong electric field. This process, called ‘electric poling-assisted additive manufacturing or EPAM, combines AM and electric poling processes and is able to fabricate free-form shape piezoelectric devices continuously. In this process, the PVDF polymer dipoles remain well-aligned and uniform over a large area in a single design, production and fabrication step. During EPAM process, molten PVDF polymer is simultaneously mechanically stresses in-situ by the leading nozzle and electrically poled by applying high electric field under high temperature. The EPAM system was constructed to directly print piezoelectric structures from PVDF polymeric filament while applying high electric field between nozzle tip and printing bed in AM machine. Piezoelectric devices were successfully fabricated using the EPAM process. The crystalline phase transitions that occurred from the process were identified by using the Fourier transform infrared spectroscope. The results indicate that devices printed under a strong electric field become piezoelectric during the EPAM process and that stronger electric fields result in greater piezoelectricity as marked by the electrical response and the formation of sharper peaks at the polar β crystalline wavenumber of the PVDF polymer. Performing this process in the absence of an electric field does not result in dipole alignment of PVDF polymer. The EPAM process is expected to lead to the widespread use of AM to fabricate a variety of piezoelectric PVDF polymer-based devices for sensing, actuation and energy harvesting applications with simple, low cost, single processing and fabrication step. (paper)
-
An Electromechanical Model for a Dielectric ElectroActive Polymer Generator
DEFF Research Database (Denmark)
Dimopoulos, Emmanouil; Trintis, Ionut; Munk-Nielsen, Stig
2013-01-01
Smart electroactive materials have attracted much of the scientific interest over the past few years, as they reflect a quite promising alternative to conservative approaches used nowadays in various transducer applications. Especially Dielectric ElectroActive Polymers (DEAPs), which are constantly...
-
Modelling electro-active polymers with a dispersion-type anisotropy
Hossain, Mokarram; Steinmann, Paul
2018-02-01
We propose a novel constitutive framework for electro-active polymers (EAPs) that can take into account anisotropy with a chain dispersion. To enhance actuation behaviour, particle-filled EAPs become promising candidates nowadays. Recent studies suggest that particle-filled EAPs, which can be cured under an electric field during the manufacturing time, do not necessarily form perfect anisotropic composites, rather they create composites with dispersed chains. Hence in this contribution, an electro-mechanically coupled constitutive model is devised that considers the chain dispersion with a probability distribution function in an integral form. To obtain relevant quantities in discrete form, numerical integration over the unit sphere is utilized. Necessary constitutive equations are derived exploiting the basic laws of thermodynamics that result in a thermodynamically consistent formulation. To demonstrate the performance of the proposed electro-mechanically coupled framework, we analytically solve a non-homogeneous boundary value problem, the extension and inflation of an axisymmetric cylindrical tube under electro-mechanically coupled load. The results capture various electro-mechanical couplings with the formulation proposed for EAP composites.
-
Flexible nano-GFO/PVDF piezoelectric-polymer nano-composite films for mechanical energy harvesting
Mishra, Monali; Roy, Amritendu; Dash, Sukalyan; Mukherjee, Somdutta
2018-03-01
Owing to the persistent quest of renewable energy technology, piezoelectric energy harvesters are gathering considerable research interest due to their potential in driving microelectronic devices with small power requirement. Electrical energy (milli to microwatt range) is generated from mechanical counterparts such as vibrations of machines, human motion, flowing water etc. based on the principles of piezoelectricity. Flexible high piezoelectric constant (d33) ceramic/polymer composites are crucial components for fabricating these energy harvesters. The polymer composites composed of gallium ferrite nanoparticles and polyvinylidene fluoride (PVDF) as the matrix have been synthesized by solvent casting method. First, 8 wt. % PVDF was dissolved in DMF and then different compositions of GaFeO3 or GFO (10, 20, 30 wt. %) (with respect to PVDF only) nanocomposites were synthesized. The phase of the synthesized nanocomposites were studied by X- Ray diffraction which shows that with the increase in the GFO concentration, the intensity of diffraction peaks of PVDF steadily decreased and GFO peaks became increasingly sharp. As the concentration of GFO increases in the PVDF polymer matrix, band gap is also increased albeit to a small extent. The maximum measured output voltage and current during mechanical pressing and releasing conditions were found to be ~ 3.5 volt and 4 nA, respectively in 30 wt % GFO-PVDF composite, comparable to the available literature.
-
Activation of PVDF membranes through facile hydroxylation of the polymeric dope
Al-Gharabli, Samer; Mavukkandy, Musthafa O.; Kujawa, Joanna; Nunes, Suzana Pereira; Arafat, Hassan A.
2017-01-01
A method comprising a two-step alkali/acid treatment of poly (vinylidene fluoride) (PVDF) polymer is developed for the fabrication of flat-sheet PVDF membranes functionalized with labile hydroxyl groups. This method involves the application of a short-duration modification in alkali medium (5% KOH). Extensive characterizations were performed on the prepared membranes. Modification of the polymer altered the crystallinity of the PVDF from a mixture of both α and β phases to a predominant β phase. Lower work of adhesion of the modified membrane indicated the formation of a more hydrophobic and wetting-resistant membrane surface. Centrifugation of the polymer dope after the modification had a pronounced impact on the properties of the resultant membranes. This protocol could be utilized in fine-tuning the properties of PVDF membranes for various target-specific applications such as membrane distillation. This method can also be used in functionalizing PVDF membranes further by exploiting the labile –OH group present on the membrane surface.
-
Activation of PVDF membranes through facile hydroxylation of the polymeric dope
Al-Gharabli, Samer
2017-10-30
A method comprising a two-step alkali/acid treatment of poly (vinylidene fluoride) (PVDF) polymer is developed for the fabrication of flat-sheet PVDF membranes functionalized with labile hydroxyl groups. This method involves the application of a short-duration modification in alkali medium (5% KOH). Extensive characterizations were performed on the prepared membranes. Modification of the polymer altered the crystallinity of the PVDF from a mixture of both α and β phases to a predominant β phase. Lower work of adhesion of the modified membrane indicated the formation of a more hydrophobic and wetting-resistant membrane surface. Centrifugation of the polymer dope after the modification had a pronounced impact on the properties of the resultant membranes. This protocol could be utilized in fine-tuning the properties of PVDF membranes for various target-specific applications such as membrane distillation. This method can also be used in functionalizing PVDF membranes further by exploiting the labile –OH group present on the membrane surface.
-
Energy harvesting with Di-Electro Active Polymers
DEFF Research Database (Denmark)
Due, Jens; Munk-Nielsen, Stig; Nielsen, Rasmus Ørndrup
2010-01-01
This article presents a way of using Di-Electro Active Polymers (D-EAPs) for harvesting mechanical energy sources. The article describes the basics of energy harvesting with D-EAPs, and an electrical model of a D-EAP is suggested. This leads to a converter design which is able to extract...... the electrical energy harvested by the D-EAP. This converter is simulated and realized. Through experimental results both the model of the DEAP and the converter are verified. It is found that it is possible to harvest energy with a D-EAP and build a converter that can extract the harvested energy....
-
Rohmawati, L.; Setyarsih, W.; Nurjannah, T.
2018-03-01
Sweep rate of the process voltammetry cyclic characterization is very influential towards the electrode capacitance value, especially on activated carbon electrodes/PVDF. A simple method of this research by use a mixing for electrode activated carbon/10 wt. % PVDF and the separator is made of a polymer electrolyte (PVA/H3PO4) by a sol gel method. The prototype supercapacitor is made in the form of a sandwich with a separator placed between two electrodes. Electrodes and separators are arranged in layers at a pressure of 1500 psi, then heated at 50°C for 10 minutes. Next done cyclic voltammetry in a potential range of -1 V to 1 V with a sweep rate of 5 mV/s, 10 mV/s, 20 mV/s, 25 mV/s and 50 mV/s. This results of curves voltammogram is reversible, the most wide curve on the sweep rate of 5 mV/s and most narrow curve on a sweep rate of 50 mV/s. Supercapacitor capacitance values obtained by 86 F/g, 43 F/g, 21 F/g, 16 F/g, and 8 F/g.
-
Effect of Polyamide 6 on Crystalline Structure of Polymer in PVDF-Nanoclay Nanocomposite
Directory of Open Access Journals (Sweden)
Ali Akbar Yousefi
2012-12-01
Full Text Available The effect of nanocaly on crystalline structure of poly(vinylidene fuoride, PVDF, and the morphology of the resulting nano-composite were investigated using different characterization techniques. The presence of 3wt% Cloisite 30B in PVDF matrix results in 11 fold increase in the percentage of beta crystalline content of the polymer. This was found to be attributed to the epitaxial effect of the clay surface. The beta crystalline content of the pure polymer (6% was raised to 68% in the composite. Addition of 5wt% polyamide 6 (PA6 improved dispersion of nanoclay which led to augmentation of the viscosity and displacement of the crossover frequency of the compatibilized composite towards lower frequencies. However, due to stronger affnity of the PA6 towards organically modifed clay the epitaxial effect of the clay on crystalline structure of PVDF was totally eliminated. The reduction of viscosity in incompatibilized nanocomposite was attributed to reduced number of PVDF chain entanglements in the presence of nanoclay. Meanwhile, increase in viscosity and displacement of crossover frequency towards lower frequencies were attributed to formation of clay-PA nanoparticles and PVDF-polyamide 6 interactions. It is expected that the presence of polyamide 6 promotes the formation of oriented-beta crystals in PVDF, which in turn improves the piezoelectric properties of the polymer.
-
Postgraduate education on electro-active polymers at Southern Denmark University
Jones, Richard W.
2009-03-01
A recently introduced elective to the Master's of Science in Mechatronics program at Southern Denmark University, entitled 'Mechatronics: Design and Build' concentrates on some of the interdisciplinary aspects of Mechatronics Engineering. The 'Motion Control of Mechatronic Devices' is the main theme of this elective. Within this 'theme' the modelling, identification and compensation of nonlinear effects such as friction, stiction and hysteresis are considered. One of the most important components of the elective considers 'Smart Materials' and their use for actuation purposes. The theory, modelling and properties of piezoceramics. magneto- and electro- rheological fluids and dielectric electro active polymers (DEAP) are introduced in the 'Smart Materials' component. This paper initially reviews the laboratory experiments that have been developed for the dielectric electro active polymer section of the 'Mechatronics: Design and Build' elective. In lectures the students are introduced to the basic theory and fabrication of tubular actuators, that use DEAP material based on smart compliant electrode technology. In the laboratory the students to (a) carry out a series of experiments to characterise the tubular actuators, and (b) design a closed-loop position controller and test the performance of the controlled actuator for both step changes in desired position and periodic input reference signals. The last part of this contribution reviews some of the DEAP-based demonstration devices that been developed by Danfoss PolyPower A/S using their PolyPowerTM material which utilizes smart compliant electrode technology.
-
International Nuclear Information System (INIS)
Yang, Chun-Chen; Lian, Zuo-Yu; Lin, S.J.; Shih, Jeng-Ywan; Chen, Wei-Houng
2014-01-01
Graphical abstract: - Highlights: • PVDF-HFP/SBA15 membrane and NCM cathode material were prepared for Li ion battery. • SBA15 fillers can trap more liquid electrolytes to enhance the ionic conductivity. • Modified fillers with functional groups play a key role in reducing impedance. • LiNi 0.5 Co 0.2 Mn 0.3 O 2 polymer battery showed excellent electrochemical performance. - Abstract: This study reports the preparation of a composite polymer electrolyte for application in LiNi 0.5 Co 0.2 Mn 0.3 O 2 lithium-polymer batteries. Poly(vinylidiene fluoride-hexafluoropropylene) (denoted as PVDF-HFP) was used as the polymer host and mesoporous modified-silica fillers (denoted as m-SBA15) used as the solid plasticizer were added into the polymer matrix. The characteristic properties of the composite polymer membranes were examined using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and an AC impedance method. The discharge capacities of LiNi 0.5 Co 0.2 Mn 0.3 O 2 polymer batteries with a PE separator, pure PVDF-HFP polymer membrane, or a PVDF-HFP/10 wt.%m-SBA15 composite at 0.1 C were determined to be 155.5, 159.5, and 198.6 mAh g −1 , respectively. The LiNi 0.5 Co 0.2 Mn 0.3 O 2 polymer battery containing the PVDF-HFP/10 wt.%m-SBA15 composite achieved discharge capacities of 194, 170, 161, 150, 129, 115, and 87 mAh g −1 at 0.1, 0.2, 0.5, 1, 3, 5, and 10 C, respectively. The lithium-polymer battery demonstrated a high coulomb efficiency of ca. 99%. The PVDF-HFP/m-SBA15 composite membrane is a strong candidate for application in LiNi 0.5 Co 0.2 Mn 0.3 O 2 lithium-polymer batteries
-
Mrlík, M.; Leadenham, S.; AlMaadeed, M. A.; Erturk, A.
2016-04-01
The harvesting of mechanical strain and kinetic energy has received great attention over the past two decades in order to power wireless electronic components such as those used in passive and active monitoring applications. Piezoelectric ceramics, such as PZT (lead zirconate titanate), constitute the most commonly used electromechanical interface in vibration energy harvesters. However, there are applications in which piezoelectric ceramics cannot be used due to their low allowable curvature and brittle nature. Soft polymer PVDF (polyvinylidene fluoride) is arguably the most popular non-ceramic soft piezoelectric energy harvester material for such scenarios. Another type of polymer that has received less attention is PP (polypropylene) for electret-based energy harvesting using the thickness mode (33- mode). This work presents figure of merit comparison of PP versus PVDF for off-resonant energy harvesting in thickness mode operation, revealing substantial advantage of PP over PVDF. For thickness mode energy harvesting scenarios (e.g. dynamic compression) at reasonable ambient vibration frequencies, the figure of merit for the maximum power output is proportional to the square of the effective piezoelectric strain constant divided by the effective permittivity constant. Under optimal conditions and for the same volume, it is shown that PP can generate more than two orders of magnitude larger electrical power as compared to PVDF due to the larger effective piezoelectric strain constant and lower permittivity of the former.
-
Investigation of the physico-mechanical properties of electrospun PVDF/cellulose nanofibers.
Issa, A.A.; Al-Maadeed, M.; Luyt, A.S.; Mrlik, M.; Hassan, M.K.
2016-01-01
The electro-activity and mechanical properties of PVDF depends mainly on the b-phase content and degree of crystallinity. In this study, cellulose fibers were used to improve these characteristics. This could be achieved because the hydroxyl groups on cellulose would force the fluorine atoms in PVDF to be in the trans-conformation, and the cellulose particles could act as nucleation centers. Electrospinning was used to prepare the PVDF/cellulose (nano)fibrous films, and this improved the tota...
-
Energy Technology Data Exchange (ETDEWEB)
Singh, Paritosh; Borkar, Hitesh [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory (CSIR-NPL) Campus, Dr. K. S. Krishnan Road, New Delhi, 110012 (India); Singh, B.P.; Singh, V.N. [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012 (India); Kumar, Ashok, E-mail: ashok553@nplindia.org [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory (CSIR-NPL) Campus, Dr. K. S. Krishnan Road, New Delhi, 110012 (India)
2015-11-05
The integration of inorganic fillers in polymer matrix is useful for superior mechanical strength and functional properties of polymer-ceramic composites. We report the fabrication and characterization of polyvinylidene fluoride-CoFe{sub 2}O{sub 4} (PVDF-CFO) (wt% 80:20, respectively) and PVDF-Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3}–CoFe{sub 2}O{sub 4} (PVDF-PZT-CFO) (wt% 80:10:10, respectively) free standing 50 μm thick ferroelectric-polymer-ceramic composites films. X-ray diffraction (XRD) patterns and Raman spectra revealed the presence of major semi-crystalline β-PVDF along with α-phase which is responsible for ferroelectric nature in both the composite systems. Ferroelectric, dielectric and mechanical strength measurements were performed in order to evaluate the effects of CFO and PZT inorganic fillers in PVDF matrix. The inclusion of CFO and PZT micro-/nano-particles in PVDF polymer matrix improved the polarization behavior, dielectric properties and mechanical strength. The energy density was calculated by polarization-electric field hysteresis loop and found in the range of 6–8 J/cm{sup 3} may be useful for microelectronics. - Graphical abstract: Large area PVDF-PZT-CFO nano- and micro-composite films have been fabricated for high energy density storage flexible capacitor. Presence of nanocrystalline PZT and CFO particles in polymer matrix significantly enhanced their energy density capacity. - Highlights: • Physical interaction of cobalt iron oxide with polymer matrix results β-PVDF phase. • Evidence of Micro and Nano crystalline CFO and PZT fillers in polymer matrix. • The CFO and PZT fillers provide better mechanical strength to composite films. • PVDF-ceramic nanocomposites show low leakage behavior for high electric field.
-
Sangeetha, M.; Mallikarjun, A.; Jaipal Reddy, M.; Siva Kumar, J.
2017-08-01
In the present paper; the FTIR and Temperature dependent DC Ionic conductivity studies of polymer (80 Wt% PVDF-HFP) with inorganic lithium tetra fluoroborate salt (20 Wt% LiBF4) as ionic charge carrier and plasticized with various weight ratios of Ethylene carbonate plasticizer (10 Wt% to 70 Wt% EC) as gel polymer electrolytes. Solution casting method is used for the preparation of plasticized polymer-salt electrolyte films. FTIR analysis shows the good complexation between PVDF-HFP: LiBF4 and the presence of functional groups in the plasticized polymer-salt electrolyte membrane. Also the analysis and results show that the highest DC ionic conductivity of 1.66 × 10-3 SCm -1 was found at 373 K for a particular concentration of 80 Wt% PVDF-HFP: 20 Wt% LiBF4: 40 Wt% EC porous gel type polymer-salt plasticized porous membrane. Increase of temperature results expansion and segmental motion of polymer chain that generates free volume in turn promotes hopping of the lithium ions satisfying Vogel-Tammann-Fulcher equation.
-
Balakrishnan, M.; Diemeer, Mart; Driessen, A.; Faccini, M.; Verboom, Willem; Reinhoudt, David; Leinse, Arne; Sidorin, Y.; Waechter, C.A.
2006-01-01
Different electro-optic polymer systems are analyzed with respect to their electro-optic activity, glass transition temperature (Tg) and photodefinable properties. The polymers tested are polysulfone (PS) and SU8. The electro-optic chromophore, tricyanovinylidenediphenylaminobenzene (TCVDPA), which
-
DEFF Research Database (Denmark)
Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.
2012-01-01
The Dielectric Electro Active Polymer (DEAP) material is a very thin (~80 μm) silicone elastomer film with a compliant metallic electrode layer on both sides. The DEAP is fundamentally a capacitor that is capable of very high strain. The property that the polymer changes its shape, as a result...
-
DEFF Research Database (Denmark)
Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe
2016-01-01
This paper presents an overview of the widely usedconventional linear actuator technologies and existing electroactivepolymer based linear and rotary actuators. It also providesthe conceptual, control and driver design considerations for anew dielectric electro-active polymer (DEAP) based...
-
Polymer Coatings Reduce Electro-osmosis
Herren, Blair J.; Snyder, Robert; Shafer, Steven G.; Harris, J. Milton; Van Alstine, James M.
1989-01-01
Poly(ethylene glycol) film controls electrostatic potential. Electro-osmosis in quartz or glass chambers reduced or reversed by coating inside surface of chambers with monomacromolecular layers of poly(ethylene glycol). Stable over long times. Electrostatic potential across surface of untreated glass or plastic chamber used in electro-phoresis is negative and attracts cations in aqueous electrolyte. Cations solvated, entrains flow of electrolyte migrating toward cathode. Electro-osmotic flow interferes with desired electrophoresis of particles suspended in electrolyte. Polymer coats nontoxic, transparent, and neutral, advantageous for use in electrophoresis.
-
Energy harvesting using ionic electro-active polymer thin films with Ag-based electrodes
International Nuclear Information System (INIS)
Anand, S V; Arvind, K; Bharath, P; Roy Mahapatra, D
2010-01-01
In this paper we employ the phenomenon of bending deformation induced transport of cations via the polymer chains in the thickness direction of an electro-active polymer (EAP)–metal composite thin film for mechanical energy harvesting. While EAPs have been applied in the past in actuators and artificial muscles, promising applications of such materials in hydrodynamic and vibratory energy harvesting are reported in this paper. For this, functionalization of EAPs with metal electrodes is the key factor in improving the energy harvesting efficiency. Unlike Pt-based electrodes, Ag-based electrodes have been deposited on an EAP membrane made of Nafion. The developed ionic metal polymer composite (IPMC) membrane is subjected to a dynamic bending load, hydrodynamically, and evaluated for the voltage generated against an external electrical load. An increase of a few orders of magnitude has been observed in the harvested energy density and power density in air, deionized water and in electrolyte solutions with varying concentrations of sodium chloride (NaCl) as compared to Pt-based IPMC performances reported in the published literature. This will have potential applications in hydrodynamic and residual environmental energy harvesting to power sensors and actuators based on micro-and nano-electro-mechanical systems (MEMS and NEMS) for biomedical, aerospace and oceanic applications
-
Balakrishnan, M.; Diemeer, M. B. J.; Driessen, A.; Faccini, M.; Verboom, W.; Reinhoudt, D. N.; Leinse, A.
2006-02-01
Different electro-optic polymer systems are analyzed with respect to their electro-optic activity, glass transition temperature (T g) and photodefinable properties. The polymers tested are polysulfone (PS) and SU8. The electro-optic chromophore, tricyanovinylidenediphenylaminobenzene (TCVDPA), which was reported to have a high photochemical stability 1 has been employed in the current work. Tert-butyl-TCVDPA, having bulky side groups, was synthesized and a doubling of the electro-optic coefficient (r33) compared to the unmodified TCVDPA was shown. A microring resonator design was made based on the PS-TCVDPA system. SU8 (passive) and TCVDPA (active) channel waveguides were fabricated by the photodefinition technique and the passive waveguide losses were measured to be 5 dB/cm at 1550 nm.
-
Improved flexoelectricity in PVDF/barium strontium titanate (BST) nanocomposites
Hu, Xinping; Zhou, Yang; Liu, Jie; Chu, Baojin
2018-04-01
The flexoelectric effect of polymers is normally much weaker than that of ferroelectric oxides. In order to improve the flexoelectric response of the poly(vinylidene fluoride) (PVDF) ferroelectric polymer, PVDF/Ba0.67Si0.33TiO3 (BST) nanocomposites were fabricated. BST nanofibers were prepared by the electrospinning method, and the fibers were further surface modified with H2O2 to achieve a stronger interfacial interaction between the fibers and polymer matrix. Due to the high dielectric properties and strong flexoelectric effect of the BST, both dielectric constant and flexoelectric response of the composite with 25 vol. % surface modified BST are 3-4 times higher than those of PVDF. The dependence of the dielectric constant and the flexoelectric coefficient on the composition of the nanocomposites can be fitted by the empirical Yamada model, and the dielectric constant and the flexoelectric coefficient are correlated by a linear relationship. This study provides an approach to enhance the flexoelectric response of PVDF-based polymers.
-
Fabrication of an electro optic polymer ringresonator
Leinse, Arne; Driessen, A.; Diemeer, Mart; de Ridder, R.M.; de Ridder, R.M; Altena, G.; Altena, G; Geuzebroek, D.H.; Dekker, R; Dekker, R.
2003-01-01
A ringresonator made of an electro optic (EO) polymer was designed, realized and characterized. The ring was made of a 4-dimethylamino-4-nitrostilbene (DANS) containing polymer and used in a vertical coupling with the waveguides. The waveguides were made of the photo-definable SU8, preventing an
-
Surface energy characteristics of zeolite embedded PVDF nanofiber films with electrospinning process
Kang, Dong Hee; Kang, Hyun Wook
2016-11-01
Electrospinning is a nano-scale fiber production method with various polymer materials. This technique allows simple fiber diameters control by changing the physical conditions such as applied voltage and polymer solution viscosity during the fabrication process. The electrospun polymer fibers form a thin porous film with high surface area to volume ratio. Due to these unique characteristics, it is widely used for many application fields such as photocatalyst, electric sensor, and antibacterial scaffold for tissue engineering. Filtration is one of the main applications of electrospun polymer fibers for specific application of filtering out dust particles and dehumidification. Most polymers which are commonly used in electrospinning are hard to perform the filtering and dehumidification simultaneously because of their low hygroscopic property. To overcome this obstacle, the desiccant polymers are developed such as polyacrylic acid and polysulfobetaine methacrylate. However, the desiccant polymers are generally expensive and need special solvent for electrospinning. An alternating way to solve these problems is mixing desiccant material like zeolite in polymer solution during an electrospinning process. In this study, the free surface energy characteristics of electrospun polyvinylidene fluoride (PVDF) film with various zeolite concentrations are investigated to control the hygroscopic property of general polymers. Fundamental physical property of wettability with PVDF shows hydrophobicity. The electrospun PVDF film with small weight ratio with higher than 0.1% of zeolite powder shows diminished contact angles that certifying the wettability of PVDF can be controlled using desiccant material in electrospinning process. To quantify the surface energy of electrospun PVDF films, sessile water droplets are introduced on the electrospun PVDF film surface and the contact angles are measured. The contact angles of PVDF film are 140° for without zeolite and 80° for with 5
-
Static and Dynamic Studies of Electro-Active Polymer Actuators and Integration in a Demonstrator
Directory of Open Access Journals (Sweden)
Pauline Poncet
2017-05-01
Full Text Available Nowadays, the haptic effect is used and developed for many applications—particularly in the automotive industry, where the mechanical feedback induced by a haptic system enables the user to receive information while their attention is kept on the road and on driving. This article presents the development of a vibrotactile button based on printed piezoelectric polymer actuation. Firstly, the characterization of the electro-active polymer used as the actuator and the development of a model able to predict the electromechanical behavior of this device are summarized. Then, the design of circular membranes and their dynamic characterization are presented. Finally, this work is concluded with the construction of a fully functional demonstrator, integrating haptic buttons leading to a clear haptic sensation for the user.
-
Electro-optics of novel polymer-liquid crystalline composites
International Nuclear Information System (INIS)
Ibragimov, T.D.; Bayramov, G.M.; Imamaliyev, A.R.; Bayramov, G.M.
2014-01-01
The polymer network liquid crystals based on the liquid crystals H37 and 5CB with PMVP and PEG have been developed. Mesogene substance HOBA is served for stabilization of obtaining composites. Kinetics of network formation is investigated by methods of polarization microscopy and integrated small-angle scattering. It is shown that gel-like states of the composite H-37+PMVP+HOBA and 5CB+PEG+HOBA are formed at polymer concentration above 7 percent and 9 percent, correspondingly. The basic electro-optic parameters of the obtained composites are determined at room temperature. Experimental results are explained by phase separation of the system, diminution of a working area of electro-optical effects and influence of areas with high polymer concentration on areas with their low concentration
-
DEFF Research Database (Denmark)
Andersen, Thomas; Rødgaard, Martin Schøler; Andersen, Michael A. E.
Through resent years new high performing Dielectric Electro Active Polymers (DEAP) have emerged. To fully utilize the potential of DEAPs a driver with high voltage output is needed. In this paper a piezoelectric transformer based power supply for driving DEAP actuators is developed, utilizing...
-
“Electro-Click” on Conducting Polymer Films
DEFF Research Database (Denmark)
Hansen, Thomas Steen; Lind, Johan Ulrik; Daugaard, Anders Egede
for their own functionalization with high spatial resolution. Interdigitated microelectrodes prepared from the azide-containing conducting polymer were selectively functionalized in sequence by two alkyne-modified fluorophores by control of the applied potentials. “Electro-click” on conducting polymer films......An azide substituted 3,4-ethylenedioxythiophene monomer is polymerised to yield a PEDOT like polymer with available azide groups (Figure 1). The azide groups enable post polymerization functionalization of the conducting polymer using a 1,3 dipolar cycloaddition reaction – also denoted “click...
-
Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe; Andersen, Michael A. E.; Sarban, Rahimullah
2016-01-01
This paper presents an overview of the widely usedconventional linear actuator technologies and existing electroactivepolymer based linear and rotary actuators. It also providesthe conceptual, control and driver design considerations for anew dielectric electro-active polymer (DEAP) based incrementalactuator. The DEAP incremental actuator consists of threeindependent DEAP actuators with a unique cylindrical designthat potentially simplifies mass production and scalabilitycompared to existing ...
-
Park, Joung-Man; Kim, Sung-Ju; Jung, Jin-Gyu; Hansen, George; Yoon, Dong-Jin
2006-03-01
Nondestructive damage sensing and load transfer mechanisms of carbon nanotube (CNT), nanofiber (CNF), and Ni nanowire strands/epoxy composites were investigated using electro-micromechanical technique. Electrospun PVDF nanofiber was also prepared as a piezoelectric sensor. High volume% CNT/epoxy composites showed significantly higher tensile properties than neat and low volume% CNT/epoxy composites. CNF /epoxy composites with smaller aspect ratio showed higher apparent modulus due to high volume content in case of shorter aspect ratio. Using Ni nanowire strands/silicone composites with different content, load sensing response of electrical contact resistivity was investigated under tensile and compression condition. The mechanical properties of Ni nanowire strands with different type and content/epoxy composites were indirectly measured apparent modulus using uniformed cyclic loading and electro-pullout test. CNT or Ni nanowire strands/epoxy composites showed humidity and temperature sensing within limited ranges, 20 vol% reinforcement. Thermal treated electrospun PVDF nanofiber showed higher mechanical properties than the untreated case due to increased crystallization, whereas load sensing decreased in heat treated case. Electrospun PVDF nanofiber web also responded the sensing effect on humidity and temperature. Nanocomposites using CNT, CNF, Ni nanowire strands, and electrospun PVDF nanofiber web can be applicable practically for multifunctional applications nondestructively.
-
PVDF-HFP-based porous polymer electrolyte membranes for lithium-ion batteries
DEFF Research Database (Denmark)
Miao, Ruiying; Liu, Bowen; Zhu, Zhongzheng
2008-01-01
As a potential electrolyte for lithium-ion batteries, a porous polymer electrolyte membrane based on poly(vinylidenefluoride-hexafluoropropylene) (PVDF-HFP) was prepared by a phase inversion method. The casting solution, effects of the solvent and non-solvent and addition of micron scale TiO2...... particles were investigated. The membranes were characterized by SEM, XRD, AC impedance, and charge/discharge tests. By using acetone as the solvent and water as the non-solvent, the prepared membranes showed good ability to absorb and retain the lithium ion containing electrolyte. Addition of micron TiO2...
-
Energy Technology Data Exchange (ETDEWEB)
Oliveira, G.L.; Costa, M.F. [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Metalurgica e de Materiais], e-mail: geovaniolo@metalmat.ufrj.br
2010-07-01
The use polymer materials in complex structure such as flexible risers to offshore application is increasingly on the rise. One the materials used in these structures is poly(vinylidene fluoride) (PVDF). Attentive to the challenges found in the environments in which these structures are employed, PVDF copolymer samples were prepared by compression molding. After, materials were aged in petroleum at 80 deg C to assess effect of fluid in polymer. Characterization of samples was carried out by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and tensile stress according to ASTM D 638. Instrumented indentation testing applying Vickers indenter was used to assess the effect of petroleum in PVDF. (author)
-
Directory of Open Access Journals (Sweden)
Qinglei Zhang
2016-10-01
Full Text Available In this study, Polyvinylidene fluoride (PVDF hollow fiber hemodialysis membranes were prepared by non-solvent induced phase separation (NIPS with compound addtive. The compound additive was made with polyvinyl pyrrolidone (PVP and Poly ethylene glycol (PEG. The results showed that the modified PVDF membrane had better separation performance than virgin PVDF membrane. The UF flux of modified PVDF membrane can reach 684 L·h−1·m−2 and lysozyme (LZM passage is 72.6% while virgin PVDF membrane is 313 L·h−1·m−2 and 53.2%. At the same time, the biocompatibility of PVDF membranes was also improved. Compared with commercial polysulfone hemodialysis membrane (Fresenius F60S membrane, the modified PVDF membrane had better mechanical and separation performance. The stress and tensile elongation of modified PVDF membrane was 0.94 MPa and 352% while Fresenius F60S membrane was 0.79 MPa and 59%. The LZM passage reached 72.6% while Fresenius F60S membrane was 54.4%. It was proven that the modified PVDF membrane showed better hydrophilicity, antithrombogenicity, less BSA adsorption, and lower hemolytic ratio and adhesion of platelets. Water contact angle and BSA adsorption of the modified PVDF membrane are 38° and 45 mg/m2 while Fresenius F60S membrane are 64° and 235 mg/m2. Prothrombin time (PT and activated partial thromboplastin time (APTT of the modified PVDF membrane are 56.5 s and 25.8 s while Fresenius F60S membrane is 35.7 s and 16.6 s. However, further biocompatibility evaluation is needed to obtain a more comprehensive conclusion.
-
International Nuclear Information System (INIS)
Li, Weili; Xing, Yujin; Wu, Yuhui; Wang, Jiawei; Chen, Lizhuang; Yang, Gang; Tang, Benzhong
2015-01-01
In this paper, nanofibrous membranes based on poly(vinylidene fluoride) (PVdF) doped with ion-complex (SiO 2 -PAALi) were prepared by electrospinning technique and the corresponding composite gel-polymer electrolytes (CGPEs) were obtained after being activated in liquid electrolyte. The microstructure, physical and electrochemical performances of the nanofibrous membranes and the corresponding CGPEs were studied by various measurements such as Fourier Transform Infrared Spectroscopy(FTIR), Scanning Electron Microscope (SEM), Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Stress-strain test, Linear Sweep Voltammetry (LSV), AC impedance measurement and Charge/discharge cycle test. As to the ion-complex doped nanofibrous membranes, PVdF can provide mechanical support with network structure composed of fully interconnection; while the ion-complexes are absorbed onto the surface of the PVdF nanofibers evenly instead of being aggregated. With the help of doped ion-complex, the prepared nanofibrous membranes present good liquid electrolyte absorbability, excellent mechanical performance, and high decomposition temperature. For the corresponding CGPEs, they possess high ionic conductivity, wide electrochemical window, and good charge/discharge cycle performance
-
Electro-Optical Parameters Of Hairy Rod Polymer/Dimethylformamide System
International Nuclear Information System (INIS)
Spasevska, Hristina
2003-01-01
Rigid rod polymers are materials with special features, that is the reason why they have large scientific and technological applications like isotropic-nematic and other types of transition. One of the biggest problems that happen while investigation to these polymers, at molecular level, is their poor solubility in most of the common solvents. Solubility gets better if while synthesize junctions flexible side chains, [1]. Remaining polymers belong on one new class - hairy rod polymers and have big potential for their technological applications. Because of their nonlinear optical properties and opportunity for self-organization in super molecular structures (films and fibers), can be used in electronics and telecommunications industry either at display-technologies [2]. That is the main reason why controlling the remaining polymer features and connection of their microscopic and macroscopic characteristics, like an complete characterization (in solutions and solid state) is from essential scientific interest, actually it is an imperative. The polymer POD-2/that is subject of investigation, bellows to hairy rod polymers and it is synthesized for the first time [3] by giving a support to their characterization. Measures on diluted solutions from the system POD-2/dimethylformamide are made by the method electric birefringence, at three temperatures (25, 40 and 55 o C). For different concentrations on system, from obtained electro-optical signals (EOS), dependence on electric birefringence (Δn) against applied electric field (E 2 ), is determined. By investigation of electro-optical effects, especially studding the way of their maintenance and losing, while applying electric square impulses, relaxation time τ o of polymer molecules is calculated. From these parameters, as presented data for EOS rise and decay too, deformational electro-optical effect has been determined. (Author)
-
International Nuclear Information System (INIS)
Virk, H.S.; Chandi, P.S.; Srivastava, A.K.
2001-01-01
Physical and chemical changes induced by 70 MeV carbon ions ( 12 C 5+ ) have been investigated in bulk polyvinylidene fluoride (PVDF) polymer. The induced changes have been studied with respect to their optical, chemical and structural response using UV-visible, FTIR and XRD techniques. The ion fluences ranging from 2.5x10 11 to 9x10 13 ions cm -2 have been used to study the irradiation effects. It has been observed that at the fluence of 9x10 13 ions cm -2 the PVDF sample became brittle and practically it was not possible to handle it for any further measurements. The recorded UV-visible spectra show that the optical absorption increases with increasing fluence, indicating maximum absorption at 200 nm. An interesting feature of UV-visible spectra is that dips change into peaks and vice versa with increase of fluence. In the FTIR spectra, development of new peaks at 1714 and 3692 cm -1 along with disappearance of peaks at 2363 and 3025 cm -1 and shifting of peak at 2984-2974 cm -1 have been observed due to high energy irradiation, indicating the chemical changes induced by 12 C 5+ . The diffraction pattern of PVDF indicates that this polymer is semi-crystalline in nature; a large decrease in the diffraction intensity indicates decrease in crystallinity. Increase in crystallite size has also been observed due to heavy ion irradiation
-
International Nuclear Information System (INIS)
Osmani, Bekim; Töpper, Tino; Weiss, Florian M.; Leung, Vanessa; Müller, Bert; Deschenaux, Christian; Nohava, Jiri
2015-01-01
Treatments of severe incontinence are currently based on purely mechanical systems that generally result in revision after three to five years. Our goal is to develop a prototype acting in a natural-analogue manner as artificial muscle, which is based on electro-active polymers. Dielectric actuators have outstanding performances including millisecond response times, mechanical strains of more than 10 % and power to mass densities similar to natural muscles. They basically consist of polymer films sandwiched between two compliant electrodes. The incompressible but elastic polymer film transduces the electrical energy into mechanical work according to the Maxwell pressure. Available polymer films are micrometers thick and voltages as large as kV are necessary to obtain 10 % strain. For medical implants, polymer films should be nanometer thin to realize actuation below 48 V. The metallic electrodes have to be stretchable to follow the strain of 10 % and remain conductive. Recent results on the stress/strain behavior of anisotropic EAP-cantilevers have shown dependencies on metal electrode preparation. We have investigated tunable anisotropic micro- and nanostructures for metallic electrodes. They show a preferred actuation direction with improved stress-strain behavior. The bending of the cantilever has been characterized by the laser beam deflection method. The impact of the electrode on the effective Young's Modulus is measured using an Ultra Nanoindentation Tester with an integrated reference system for soft polymer surfaces. Once ten thousand layers of nanometer-thin EAP actuators are available, devices beyond the envisioned application will flood the market
-
Energy Technology Data Exchange (ETDEWEB)
Osmani, Bekim, E-mail: bekim.osmani@unibas.ch, E-mail: tino.toepper@unibas.ch; Töpper, Tino, E-mail: bekim.osmani@unibas.ch, E-mail: tino.toepper@unibas.ch; Weiss, Florian M., E-mail: vanessa.leung@unibas.ch, E-mail: bert.mueller@unibas.ch; Leung, Vanessa, E-mail: vanessa.leung@unibas.ch, E-mail: bert.mueller@unibas.ch; Müller, Bert, E-mail: vanessa.leung@unibas.ch, E-mail: bert.mueller@unibas.ch [Biomaterials Science Center, University of Basel, c/o University Hospital, 4031 Basel (Switzerland); Deschenaux, Christian, E-mail: jiri.nohava@anton-paar.com; Nohava, Jiri, E-mail: jiri.nohava@anton-paar.com [Anton Paar TriTec SA, Rue de la Gare 4, Galileo Center, 2034 Peseux (Switzerland)
2015-02-17
Treatments of severe incontinence are currently based on purely mechanical systems that generally result in revision after three to five years. Our goal is to develop a prototype acting in a natural-analogue manner as artificial muscle, which is based on electro-active polymers. Dielectric actuators have outstanding performances including millisecond response times, mechanical strains of more than 10 % and power to mass densities similar to natural muscles. They basically consist of polymer films sandwiched between two compliant electrodes. The incompressible but elastic polymer film transduces the electrical energy into mechanical work according to the Maxwell pressure. Available polymer films are micrometers thick and voltages as large as kV are necessary to obtain 10 % strain. For medical implants, polymer films should be nanometer thin to realize actuation below 48 V. The metallic electrodes have to be stretchable to follow the strain of 10 % and remain conductive. Recent results on the stress/strain behavior of anisotropic EAP-cantilevers have shown dependencies on metal electrode preparation. We have investigated tunable anisotropic micro- and nanostructures for metallic electrodes. They show a preferred actuation direction with improved stress-strain behavior. The bending of the cantilever has been characterized by the laser beam deflection method. The impact of the electrode on the effective Young's Modulus is measured using an Ultra Nanoindentation Tester with an integrated reference system for soft polymer surfaces. Once ten thousand layers of nanometer-thin EAP actuators are available, devices beyond the envisioned application will flood the market.
-
Ultrasound-mediated piezoelectric differentiation of neuron-like PC12 cells on PVDF membranes.
Hoop, Marcus; Chen, Xiang-Zhong; Ferrari, Aldo; Mushtaq, Fajer; Ghazaryan, Gagik; Tervoort, Theo; Poulikakos, Dimos; Nelson, Bradley; Pané, Salvador
2017-06-22
Electrical and/or electromechanical stimulation has been shown to play a significant role in regenerating various functionalities in soft tissues, such as tendons, muscles, and nerves. In this work, we investigate the piezoelectric polymer polyvinylidene fluoride (PVDF) as a potential substrate for wireless neuronal differentiation. Piezoelectric PVDF enables generation of electrical charges on its surface upon acoustic stimulation, inducing neuritogenesis of PC12 cells. We demonstrate that the effect of pure piezoelectric stimulation on neurite generation in PC12 cells is comparable to the ones induced by neuronal growth factor (NGF). In inhibitor experiments, our results indicate that dynamic stimulation of PVDF by ultrasonic (US) waves activates calcium channels, thus inducing the generation of neurites via a cyclic adenosine monophosphate (cAMP)-dependent pathway. This mechanism is independent from the well-studied NGF induced mitogen-activated protein kinases/extracellular signal-regulated kinases (MAPK/ERK) pathway. The use of US, in combination with piezoelectric polymers, is advantageous since focused power transmission can occur deep into biological tissues, which holds great promise for the development of non-invasive neuroregenerative devices.
-
Study of piezoelectric filler on the properties of PZT-PVDF composites
Matei, Alina; Å¢ucureanu, Vasilica; Vlǎzan, Paulina; Cernica, Ileana; Popescu, Marian; RomaniÅ£an, Cosmin
2017-12-01
The ability to obtain composites with desired functionalities is based on advanced knowledge of the processes synthesis and of the structure of piezoceramic materials, as well the incorporation of different fillers in selected polymer matrix. Polyvinylidene fluoride (PVDF) is a fluorinated polymer with excellent mechanical and electric properties, which it was chosen as matrix due to their applications in a wide range of industrial fields [1-4]. The present paper focuses on the development of composites based on PZT particles as filler obtained by conventional methods and PVDF as polymer matrix. The synthesis of PVDF-PZT composites was obtained by dispersing the ceramic powders in a solution of PVDF in N-methyl-pyrrolidone (NMP) under mechanical mixing and ultrasonication, until a homogenous mixture is obtained. The properties of the piezoceramic fillers before and after embedding into the polymeric matrix were investigated by Fourier transform infrared spectrometry, field emission scanning electron microscopy and X-ray diffraction. In the FTIR spectra, appear a large number of absorption bands which are exclusive of the phases from PVDF matrix confirming the total embedding of PZT filler into matrix. Also, the XRD pattern of the composites has confirmed the presence of crystalline phases of PVDF and the ceramic phase of PZT. The SEM results showed a good distribution of fillers in the matrix.
-
High speed electro optic polymer micro-ringresonator
Leinse, Arne; Diemeer, Mart; Driessen, A.
2004-01-01
An electro-optic polymer micro-ring resonator for high speed modulation was designed, realized and characterized. The design of layer-stack and electrodes was done such that modulation frequencies up till 1 GHz should be possible. The device consists of a ridge waveguide, defined in a negative
-
Energy Technology Data Exchange (ETDEWEB)
Costa, Ligia M.M.; Olyveira, Gabriel M. de, E-mail: gmolyveira@yahoo.com.b, E-mail: ligialmmc@hotmail.co [Universidade Federal de Sao Carlos (PPGCEM/UFScar), SP (Brazil). Programa de Pos Graduacao em Ciencia e Engenharia de Materiais; Gregorio Filho, Rinaldo; Pessan, Luiz A., E-mail: pessan@ufscar.b, E-mail: gregorio@ufscar.b [Universidade Federal de Sao Carlos (UFScar), SP (Brazil)
2009-07-01
PVDF nanofibers with and without nanoparticles were produced by the method of electro spinning using dimethylformamide (DMF). Silver nitrate nanoparticles (0,5 and 2 wt %) and silver/titanium dioxide nanoparticles obtained by the reduction method (2 wt %) were synthesized and added to the PVDF solution to prepared nanofibers. The processes of electrospinning and film preparation using PVDF with the nanoparticles were compared. Silver/titanium dioxide nanoparticles were characterized with X-ray diffraction (XRD), Scanning electron microscopy (SEM) with EDX and x-ray photoelectron spectroscopy (XPS) to show silver/titanium dioxide nanoparticles. Nanofibers mats were characterized with SEM to study the effects of the addition of the nanoparticles on the morphology behavior and spectroscopy by Fourier transform infrared (FTIR) to analyze the crystalline phase of PVDF films. (author)
-
Directory of Open Access Journals (Sweden)
Ilhwan Kim
2018-04-01
Full Text Available Here, we fabricate poly(vinylidene fluoride-co-hexafluoropropene (PVDF-co-HFP by electrospinning for a gel polymer electrolyte (GPE for use in flexible Li-ion batteries (LIBs. As a solvent, we use N-methyl-2-pyrrolidone (NMP, which helps produce the cross-linked morphology of PVDF-co-HFP separator, owing to its low volatility. The cross-linked PVDF-co-HFP separator shows an uptake rate higher than that of a commercialized polypropylene (PP separator. Moreover, the PVDF-co-HFP separator shows an ionic conductivity of 2.3 × 10−3 S/cm at room temperature, comparable with previously reported values. An LIB full-cell assembled with the PVDF-co-HFP-based GPE shows capacities higher than its counterpart with the commercialized PP separator, confirming that the cross-linked PVDF-co-HFP separator provides highly efficient ionic conducting pathways. In addition, we integrate a flexible LIB cell using the PVDF-co-HFP GPE with a flexible organic light emitting diode (OLED, demonstrating a fully flexible unit of LIB and OLED.
-
Bouclé, J.; Kassiba, A.; Makowska-Janusik, M.; Herlin-Boime, N.; Reynaud, C.; Desert, A.; Emery, J.; Bulou, A.; Sanetra, J.; Pud, A. A.; Kodjikian, S.
2006-11-01
An electro-optical activity has been recently reported for hybrid nanocomposite thin films where inorganic silicon carbide nanocrystals (ncSiC) are incorporated into polymer matrices. The role of the interface SiC polymer is suggested as the origin of the observed second order nonlinear optical susceptibility in the hybrid materials based on poly-(methylmethacrylate) (PMMA) or poly-( N -vinylcarbazole) matrices. In this work, we report an analysis of the electro-optical response of this hybrid system as a function of the ncSiC content and surface state in order to precise the interface effect in the observed phenomenon. Two specific ncSiC samples with similar morphology and different surface states are incorporated in the PMMA matrix. The effective Pockels parameters of the corresponding hybrid nanocomposites have been estimated up to 7.59±0.74pm/V ( 1wt.% of ncSiC in the matrix). The interfacial region ncSiC polymer is found to play the main role in the observed effect. Particularly, the electronic defects on the ncSiC nanocrystal surface modify the interfacial electrical interactions between the two components. The results are interpreted and discussed on the basis of the strong influence of these active centers in the interfacial region at the nanoscale, which are found to monitor the local hyperpolarizabilities and the macroscopic nonlinear optical susceptibilities. This approach allows us to complete the description and understanding of the electro-optical response in the hybrid SiC /polymer systems.
-
Nanoconfinement: an effective way to enhance PVDF piezoelectric properties.
Cauda, Valentina; Stassi, Stefano; Bejtka, Katarzyna; Canavese, Giancarlo
2013-07-10
The dimensional confinement and oriented crystallization are both key factors in determining the piezoelectric properties of a polymeric nanostructured material. Here we prepare arrays of one-dimensional polymeric nanowires showing piezoelectric features by template-wetting two distinct polymers into anodic porous alumina (APA) membranes. In particular, poly(vinylidene fluoride), PVDF, and its copolymer poly(vinylidene fluoride-trifluoroethylene), PVTF, are obtained in commercially available APA, showing a final diameter of about 200 nm and several micrometers in length, reflecting the templating matrix features. We show that the crystallization of both polymers into a ferroelectric phase is directed by the nanotemplate confinement. Interestingly, the PVDF nanowires mainly crystallize into the β-phase in the nanoporous matrix, whereas the reference thin film of PVDF crystallizes in the α nonpolar phase. In the case of the PVTF nanowires, needle-like crystals oriented perpendicularly to the APA channel walls are observed, giving insight on the molecular orientation of the polymer within the nanowire structure. A remarkable piezoelectric behavior of both 1-D polymeric nanowires is observed, upon recording ferroelectric polarization, hysteresis, and displacement loops. In particular, an outstanding piezoelectric effect is observed for the PVDF nanowires with respect to the polymeric thin film, considering that no poling was carried out. Current versus voltage (I-V) characteristics showed a consistent switching behavior of the ferroelectric polar domains, thus revealing the importance of the confined and oriented crystallization of the polymer in monodimensional nanoarchitectures.
-
Directory of Open Access Journals (Sweden)
Ch. Thirmal
2013-11-01
Full Text Available We have investigated the structure, magnetic and dielectric properties of PVDF-La0.7Sr0.3MnO3 polymer nanocomposite thick film fabricated by dip coating technique along with the magnetodielectric effect. The structure and dielectric properties show the enhanced β phase in the composite compared to the PVDF film. The coupling between the ferroelectric and magnetic phases in the composite is revealed in the form of dielectric anomaly at the ferromagnetic Curie temperature. We observed 1.9% magnetodielectric effect at 300 K with the possibility of enhanced effect near the transition temperature. In addition, the analysis of the electric modulus indicates that the composite exhibits interfacial related relaxation and it follows Arrhenius Law. Our study suggests that the ac conductivity of the PVDF-La0.7Sr0.3MnO3 composite could be explained by correlated barrier hopping mechanism.
-
Electro Optic Modulation In a Polymer Ringresonator
Leinse, A.; Driessen, A.; Diemeer, M. B. J.
2004-05-01
A thermo optic and electro optic (EO) tunable polymer ringresonator was realized and tested. The device consisted of a microring resonator made of the 4-dimethylamino-4‵-nitrostilbene (DANS) containing polymer and measurements were done on the through port of this device. The ring was used in a vertical coupling structure. The port waveguides were made of the photo-definable epoxy (SU8). The rings used had a diameter of 100 μm and thermo optic tuning of about 170 pm/°C was measured. EO modulation was measured for TE polarization.
-
Measurements of nonlinear optical properties of PVDF/ZnO using Z-scan technique
Energy Technology Data Exchange (ETDEWEB)
Shanshool, Haider Mohammed, E-mail: haidshan62@gmail.com [Ministry of Science and Technology, Baghdad (Iraq); Yahaya, Muhammad [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Selangor (Malaysia); Yunus, Wan Mahmood Mat [Department of Physics, Faculty of Science, University Putra Malaysia, Serdang (Malaysia); Abdullah, Ibtisam Yahya [Department of Physics, College of Science, University of Mosul, Mosul (Iraq)
2015-10-15
The nonlinear optical properties of ZnO nanoparticles dispersed in poly (vinylidene fluoride) (PVDF) polymer are investigated. PVDF/ZnO nanocomposites were prepared by mixing different concentrations of ZnO nanoparticles, as the filler, with PVDF, as the polymer matrix, using casting method. Acetone was used as a solvent for the polymer. FTIR spectra of the samples were analyzed thus confirming the formation of α and β phases. The absorbance spectra of the samples were obtained, thereby showing high absorption in the UV region. The linear absorption coefficient was calculated. The single-beam Z-scan technique was used to measure the nonlinear refractive index and the nonlinear absorption coefficient of the PVDF/ZnO nanocomposite samples. We observed that the nonlinear refractive index is in the order of 10{sup -13} cm{sup 2}/W with the negative sign, whereas the nonlinear absorption coefficient is in the order of 10{sup -8} cm/W. (author)
-
Cellulose Electro-Active Paper: From Discovery to Technology Applications
Abas, Zafar; Kim, Heung Soo; Kim, Jaehwan; Kim, Joo-Hyung
2014-09-01
Cellulose electro-active paper (EAPap) is an attractive material of electro-active polymers (EAPs) family due to its smart characteristics. EAPap is thin cellulose film coated with metal electrodes on both sides. Its large displacement output, low actuation voltage and low power consumption can be used for biomimetic sensors/actuators and electromechanical system. Because cellulose EAPap is ultra-lightweight, easy to manufacture, inexpensive, biocompatible, and biodegradable, it has been employed for many applications such as bending actuator, vibration sensor, artificial muscle, flexible speaker, and can be advantageous in areas such as micro-insect robots, micro-flying objects, microelectromechanical systems, biosensors, and flexible displays.
-
Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications.
Khan, Asif; Abas, Zafar; Kim, Heung Soo; Kim, Jaehwan
2016-07-26
We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active paper and its hybrid composites such as blends or coatings with synthetic polymers, biopolymers, carbon nanotubes, chitosan, and metal oxides, are explained. In addition, the integration of cellulose electro-active paper is highlighted to form various functional devices including but not limited to bending actuators, flexible speaker, strain sensors, energy harvesting transducers, biosensors, chemical sensors and transistors for electronic applications. The frontiers in cellulose paper devices are reviewed together with the strategies and perspectives of cellulose electro-active paper and cellulose nanocomposite research and applications.
-
Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications
Directory of Open Access Journals (Sweden)
Asif Khan
2016-07-01
Full Text Available We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active paper and its hybrid composites such as blends or coatings with synthetic polymers, biopolymers, carbon nanotubes, chitosan, and metal oxides, are explained. In addition, the integration of cellulose electro-active paper is highlighted to form various functional devices including but not limited to bending actuators, flexible speaker, strain sensors, energy harvesting transducers, biosensors, chemical sensors and transistors for electronic applications. The frontiers in cellulose paper devices are reviewed together with the strategies and perspectives of cellulose electro-active paper and cellulose nanocomposite research and applications.
-
Kim, Hoejin; Torres, Fernando; Wu, Yanyu; Villagran, Dino; Lin, Yirong; Tseng, Tzu-Liang(Bill
2017-08-01
This paper presents a novel process to fabricate piezoelectric films from polyvinylidene fluoride (PVDF) polymer using integrated fused deposition modeling (FDM) 3D printing and corona poling technique. Corona poling is one of many effective poling processes that has received attention to activate PVDF as a piezoelectric responsive material. The corona poling process occurs when a PVDF polymer is exposed to a high electric field created and controlled through an electrically charged needle and a grid electrode under heating environment. FDM 3D printing has seen extensive progress in fabricating thermoplastic materials and structures, including PVDF. However, post processing techniques such as poling is needed to align the dipoles in order to gain piezoelectric properties. To further simplify the piezoelectric sensors and structures fabrication process, this paper proposes an integrated 3D printing process with corona poling to fabricate piezoelectric PVDF sensors without post poling process. This proposed process, named ‘Integrated 3D Printing and Corona poling process’ (IPC), uses the 3D printer’s nozzle and heating bed as anode and cathode, respectively, to create poling electric fields in a controlled heating environment. The nozzle travels along the programmed path with fixed distance between nozzle tip and sample’s top surface. Simultaneously, the electric field between the nozzle and bottom heating pad promotes the alignment of dipole moment of PVDF molecular chains. The crystalline phase transformation and output current generated by printed samples under different electric fields in this process were characterized by a Fourier transform infrared spectroscopy and through fatigue load frame. It is demonstrated that piezoelectric PVDF films with enhanced β-phase percentage can be fabricated using the IPC process. In addition, mechanical properties of printed PVDF was investigated by tensile testing. It is expected to expand the use of additive
-
Cellulose Electro-Active Paper: From Discovery to Technology Applications
Directory of Open Access Journals (Sweden)
Zafar eAbas
2014-09-01
Full Text Available Cellulose electro-active paper (EAPap is an attractive material of electro-active polymers (EAPs family due to its smart characteristics. EAPap is thin cellulose film coated with metal electrodes on both sides. Its large displacement output, low actuation voltage and low power consumption can be used for biomimetic sensors/actuators and electromechanical system. Because cellulose EAPap is ultra-lightweight, easy to manufacture, inexpensive, biocompatible, and biodegradable, it has been employed for many applications such as bending actuator, vibration sensor, artificial muscle, flexible speaker, and can be advantageous in areas such as micro-insect robots, micro-flying objects, microelectromechanical systems, biosensors, and flexible displays.
-
Assessment of Blend PVDF Membranes, and the Effect of Polymer Concentration and Blend Composition
Directory of Open Access Journals (Sweden)
Imtiaz Ali
2018-03-01
Full Text Available In this work, PVDF homopolymer was blended with PVDF-co-HFP copolymer and studied in terms of morphology, porosity, pore size, hydrophobicity, permeability, and mechanical properties. Different solvents, namely N-Methyl-2 pyrrolidone (NMP, Tetrahydrofuran (THF, and Dimethylformamide (DMF solvents, were used to fabricate blended PVDF flat sheet membranes without the introduction of any pore forming agent, through a non-solvent induced phase separation (NIPS technique. Furthermore, the performance of the fabricated membranes was investigated for pressure and thermal driven applications. The porosity of the membranes was slightly increased with the increase in the overall content of PVDF and by the inclusion of PVDF copolymer. Total PVDF content, copolymer content, and mixed-solvent have a positive effect on mechanical properties. The addition of copolymer increased the hydrophobicity when the total PVDF content was 20%. At 25% and with the inclusion of mixed-solvent, the hydrophobicity was adversely affected. The permeability of the membranes increased with the increase in the overall content of PVDF. Mixed-solvents significantly improved permeability.
-
Assessment of Blend PVDF Membranes, and the Effect of Polymer Concentration and Blend Composition.
Ali, Imtiaz; Bamaga, Omar A; Gzara, Lassaad; Bassyouni, M; Abdel-Aziz, M H; Soliman, M F; Drioli, Enrico; Albeirutty, Mohammed
2018-03-05
In this work, PVDF homopolymer was blended with PVDF-co-HFP copolymer and studied in terms of morphology, porosity, pore size, hydrophobicity, permeability, and mechanical properties. Different solvents, namely N-Methyl-2 pyrrolidone (NMP), Tetrahydrofuran (THF), and Dimethylformamide (DMF) solvents, were used to fabricate blended PVDF flat sheet membranes without the introduction of any pore forming agent, through a non-solvent induced phase separation (NIPS) technique. Furthermore, the performance of the fabricated membranes was investigated for pressure and thermal driven applications. The porosity of the membranes was slightly increased with the increase in the overall content of PVDF and by the inclusion of PVDF copolymer. Total PVDF content, copolymer content, and mixed-solvent have a positive effect on mechanical properties. The addition of copolymer increased the hydrophobicity when the total PVDF content was 20%. At 25% and with the inclusion of mixed-solvent, the hydrophobicity was adversely affected. The permeability of the membranes increased with the increase in the overall content of PVDF. Mixed-solvents significantly improved permeability.
-
Fabrication of PVDF-TrFE based bilayered PbTiO3/PVDF-TrFE films capacitor
Nurbaya, Z.; Wahid, M. H.; Rozana, M. D.; Annuar, I.; Alrokayan, S. A. H.; Khan, H. A.; Rusop, M.
2016-07-01
Development of high performance capacitor is reaching towards new generation where the ferroelectric materials take places as the active dielectric layer. The motivation of this study is to produce high capacitance device with long life cycle. This was configured by preparing bilayered films where lead titanate as an active dielectric layer and stacked with the top dielectric layer, poly(vinyledenefluoride-trifluoroethylene). Both of them are being referred that have one in common which is ferroelectric behavior. Therefore the combination of ceramic and polymer ferroelectric material could perform optimum dielectric characteristic for capacitor applications. The fabrication was done by simple sol-gel spin coating method that being varied at spinning speed property for polymer layers, whereas maintaining the ceramic layer. The characterization of PVDF-TrFE/PbTiO3 was performed according to metal-insulator-metal stacked capacitor measurement which includes structural, dielectric, and ferroelectric measurement.
-
Proton exchange membranes based on PVDF/SEBS blends
Energy Technology Data Exchange (ETDEWEB)
Mokrini, A.; Huneault, M.A. [Industrial Materials Institute, National Research Council of Canada, 75 de Mortagne Blvd., Boucherville, Que. (Canada J4B 6Y4)
2006-03-09
Proton-conductive polymer membranes are used as an electrolyte in the so-called proton exchange membrane fuel cells. Current commercially available membranes are perfluorosulfonic acid polymers, a class of high-cost ionomers. This paper examines the potential of polymer blends, namely those of styrene-(ethylene-butylene)-styrene block copolymer (SEBS) and polyvinylidene fluoride (PVDF), in the proton exchange membrane application. SEBS/PVDF blends were prepared by twin-screw extrusion and the membranes were formed by calendering. SEBS is a phase-segregated material where the polystyrene blocks can be selectively functionalized offering high ionic conductivity, while PVDF insures good dimensional stability and chemical resistance to the films. Proton conductivity of the films was obtained by solid-state grafting of sulfonic acid moieties. The obtained membranes were characterized in terms of conductivity, ionic exchange capacity and water uptake. In addition, the membranes were characterized in terms of morphology, microstructure and thermo-mechanical properties to establish the blends morphology-property relationships. Modification of interfacial properties between SEBS and PVDF was found to be a key to optimize the blends performance. Addition of a methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer (MMA-BA-MMA) was found to compatibilize the blend by reducing the segregation scale and improving the blend homogeneity. Mechanical resistance of the membranes was also improved through the addition of this compatibilizer. As little as 2wt.% compatibilizer was sufficient for complete interfacial coverage and lead to improved mechanical properties. Compatibilized blend membranes also showed higher conductivities, 1.9x10{sup -2} to 5.5x10{sup -3}Scm{sup -1}, and improved water management. (author)
-
Fabrication of PVDF-TrFE based bilayered PbTiO{sub 3}/PVDF-TrFE films capacitor
Energy Technology Data Exchange (ETDEWEB)
Nurbaya, Z., E-mail: nurbayazainal@gmail.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Razak School of Engineering and Advanced Technology, Universiti Teknologi Malaysia, 54100 Kuala Lumpur (Malaysia); Wahid, M. H.; Rozana, M. D. [Faculty of Applied Sciences, Department of Polymer, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Annuar, I. [UiTM Sarawak Kampus Kota Samarahan, Jalan Meranek, 94300 Sarawak (Malaysia); Alrokayan, S. A. H.; Khan, H. A. [Department of Biochemistry, College of Science, Bldg. 5, King Saud University (KSU) P.O: 2454 Riyadh 11451 (Saudi Arabia); Rusop, M., E-mail: nanouitm@gmail.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-Sci Tech Centre (NST), Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)
2016-07-06
Development of high performance capacitor is reaching towards new generation where the ferroelectric materials take places as the active dielectric layer. The motivation of this study is to produce high capacitance device with long life cycle. This was configured by preparing bilayered films where lead titanate as an active dielectric layer and stacked with the top dielectric layer, poly(vinyledenefluoride-trifluoroethylene). Both of them are being referred that have one in common which is ferroelectric behavior. Therefore the combination of ceramic and polymer ferroelectric material could perform optimum dielectric characteristic for capacitor applications. The fabrication was done by simple sol-gel spin coating method that being varied at spinning speed property for polymer layers, whereas maintaining the ceramic layer. The characterization of PVDF-TrFE/PbTiO3 was performed according to metal-insulator-metal stacked capacitor measurement which includes structural, dielectric, and ferroelectric measurement.
-
Radiodegradation process in PVDF with different molecular weight
International Nuclear Information System (INIS)
Silva, L.; Batista, A.S.M.; Nascimento, J.P.; Furtado, C.A.; Faria, L.O.
2017-01-01
Poly(vinylidene fluoride) (PVDF) is a semi-crystalline polymer with several industrial applications due to its mechanical, ferroelectric and biocompatibility properties. Due to the particularity of some of its applications this polymer is exposed to high energy radiation, for example in the aerospace industry and with biomaterial, in sterilization processes. In this sense it is of interest studies that evaluate the radiodegradation of this material, as a way to predict its mechanical behavior after processes of exposure to gamma radiation. In this study the radioresistance of PVDF with different molecular weights is evaluated, considering that large molecular chains can provide greater resistance than smaller chains. Method: PVDF samples with different molecular weights were produced by the solvent dilution process. They were irradiated with gamma doses of 100, 300, 500, 1000 and 2000 kGy with a source of cobalt in the Laboratório de Irradiação Gama (LIG) of the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN). FTIR, UV-Vis, DSC and XRD analyzes were used to evaluate the induced radiodegradation processes immediately after irradiation and one month later. Results: The FTIR and UV-Vis analyzes showed formation of unsaturations in the polymer chains. The DSC technique showed a drop in the crystalline fraction of the polymer confirmed by the XRD technique. Conclusion: Post-irradiation sample evaluations are discussed in terms of the effect of high energy ionizing radiation on polymeric mate-rials for industrial and biomedical use for safety in quality assurance and performance in service. (author)
-
Radiodegradation process in PVDF with different molecular weight
Energy Technology Data Exchange (ETDEWEB)
Silva, L.; Batista, A.S.M., E-mail: adriananuclear@yahoo.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Nascimento, J.P.; Furtado, C.A.; Faria, L.O. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)
2017-07-01
Poly(vinylidene fluoride) (PVDF) is a semi-crystalline polymer with several industrial applications due to its mechanical, ferroelectric and biocompatibility properties. Due to the particularity of some of its applications this polymer is exposed to high energy radiation, for example in the aerospace industry and with biomaterial, in sterilization processes. In this sense it is of interest studies that evaluate the radiodegradation of this material, as a way to predict its mechanical behavior after processes of exposure to gamma radiation. In this study the radioresistance of PVDF with different molecular weights is evaluated, considering that large molecular chains can provide greater resistance than smaller chains. Method: PVDF samples with different molecular weights were produced by the solvent dilution process. They were irradiated with gamma doses of 100, 300, 500, 1000 and 2000 kGy with a source of cobalt in the Laboratório de Irradiação Gama (LIG) of the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN). FTIR, UV-Vis, DSC and XRD analyzes were used to evaluate the induced radiodegradation processes immediately after irradiation and one month later. Results: The FTIR and UV-Vis analyzes showed formation of unsaturations in the polymer chains. The DSC technique showed a drop in the crystalline fraction of the polymer confirmed by the XRD technique. Conclusion: Post-irradiation sample evaluations are discussed in terms of the effect of high energy ionizing radiation on polymeric mate-rials for industrial and biomedical use for safety in quality assurance and performance in service. (author)
-
Pradhan, Lagen Kumar; Pandey, Rabichandra; Kumar, Sunil; Kar, Manoranjan
2018-05-01
Novel ceramic-polymer nanocomposites have great potential for electrical energy storage applications due to its high energy storage density. In the present work, BNT and PVDF based flexible polymer nanocomposites (BNT-PVDF) with different volume fraction (ϕ = 0, 5, 10, 15) were fabricated by solution casting method. Enhancement in beta phase of PVDF polymer matrix with the volume fraction (ϕ = 5, 10, 15) of BNT has been confirmed by X-ray diffraction (XRD) technique as well as Fourier transform infrared (FTIR) spectroscopy analysis. The enhancement of β phase increases as compared to (α) phases with volume fraction (ϕ) of nanofiller (BNT) in the matrix (PVDF) due to internal stress at the interface as well as structural modification of PVDF matrix. BNT-PVDF nanocomposites (with ϕ=10) showed a high dielectric constant (ɛr ≈ 78) relative to pure PVDF (ɛr ≈ 10) at 100 Hz. In addition to this, it exhibits relaxor type ferroelectric behavior with energy storage efficiency up to 77% for the volume fraction (ϕ) of 10.
-
Directory of Open Access Journals (Sweden)
Sinan Sezgin
2014-01-01
Full Text Available Proton exchange membrane fuel cells (PEMFCs are considered to be a promising technology for clean and efficient power generation in the twenty-first century. In this study, high performance of poly(vinylidene fluoride (PVDF and proton conductivity of poly(1-vinyl-1,2,4-triazole (PVTri were combined in a graft copolymer, PVDF-g-PVTri, by the polymerization of 1-vinyl-1,2,4-triazole on a PVDF based matrix under UV light in one step. The polymers were doped with triflic acid (TA at different stoichiometric ratios with respect to triazole units and the anhydrous polymer electrolyte membranes were prepared. All samples were characterized by FTIR and 1H-NMR spectroscopies. Their thermal properties were examined by thermogravimetric analysis (TGA and differential scanning calorimetry (DSC. TGA demonstrated that the PVDF-g-PVTri and PVDF-g-PVTri-(TAx membranes were thermally stable up to 390°C and 330°C, respectively. NMR and energy dispersive X-ray spectroscopy (EDS results demonstrated that PVDF-g-PVTri was successfully synthesized with a degree of grafting of 21%. PVDF-g-PVTri-(TA3 showed a maximum proton conductivity of 6×10-3 Scm−1 at 150°C and anhydrous conditions. CV study illustrated that electrochemical stability domain for PVDF-g-PVTri-(TA3 extended over 4.0 V.
-
Energy Technology Data Exchange (ETDEWEB)
Spasova, M.; Manolova, N. [Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev St, bl. 103A, BG-1113 Sofia (Bulgaria); Markova, N. [Institute of Microbiology, Bulgarian Academy of Sciences, Acad. G. Bonchev St, bl. 26, BG-1113 Sofia (Bulgaria); Rashkov, I., E-mail: rashkov@polymer.bas.bg [Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev St, bl. 103A, BG-1113 Sofia (Bulgaria)
2016-02-15
Graphical abstract: - Highlights: • New PVDF and PVDF-HFP nanofibers decorated with ZnO nanoparticles and a model drug. • The nanofibrous materials were fabricated by one-pot electrospinning. • The obtained materials are superhybrophobic and possess antibacterial properties. - Abstract: Superhydrophobic nanofibrous materials of poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) were prepared by one-pot electrospinning technique. The mats were decorated with ZnO nanoparticles with silanized surface and a model drug – 5-chloro-8-hydroxyquinolinol (5Cl8HQ). The obtained hybrid nanofibrous materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), contact angle measurements, mechanical and microbiological tests. The results showed that the incorporation of ZnO nanoparticles into PVDF and PVDF-HFP nanofibers increased the hydrophobicity (contact angle 152°), improved the thermal stability and imparted to the nanofibrous materials anti-adhesive and antimicrobial properties. The mats containing the model drug possessed antibacterial activity against Escherichia coli and Staphylococcus aureus. The results suggested that the obtained hybrid mats could find potential biomedical applications requiring antibacterial and anti-biofouling properties.
-
Formation of controllable polymer micropatterns through liquid film electro-dewetting
Zhou, Shangru; Zheng, Huai; Li, Guoliang; Liu, Jie; Liu, Sheng
2018-04-01
Controllable polymer micropatterns, served as indispensable function structures, are extensively required in many micro/nano scientific areas and engineering applications. Exploring advanced methods of fabricating micropatterns is always a research hotspot. In this article, we introduce a novel method of patterning polymer by the electro-dewetting induced by corona discharge. For the first time, it is observed experimentally that liquid polymer on conductive/non-conductive patterned substrates, spontaneously converges from non-conductive areas to conductive areas under the action of ion wind. Taking advantage of such a flow phenomenon, controllable polymer micropatterns including microbump arrays and microwell arrays are fabricated successfully. Their sizes range from hundreds of microns to millimeters. Micropattern surfaces present an ultra-smooth characteristic, with roughness in the nanometer range.
-
Growth of BaTiO3-PVDF composite thick films by using aerosol deposition
Cho, Sung Hwan; Yoon, Young Joon
2016-01-01
Barium titanate (BaTiO3)-polyvinylidene fluoride (PVDF) composite thick films were grown by using aerosol deposition at room temperature with BaTiO3 and PVDF powders. To produce a uniform composition in ceramic and polymer composite films, which show a substantial difference in specific gravity, we used PVDF-coated BaTiO3 powders as the starting materials. An examination of the microstructure confirmed that the BaTiO3 were well distributed in the PVDF matrix in the form of a 0 - 3 compound. The crystallite size in the BaTiO3-PVDF composite thick films was 5 ˜ 50 times higher than that in pure BaTiO3 thick films. PVDF plays a role in suppressing the fragmentation of BaTiO3 powder during the aerosol deposition process and in controlling the relative permittivity.
-
Large-area Fabry-Perot modulator based on electro-optic polymers
DEFF Research Database (Denmark)
Benter, Nils; Bertram, Ralph Peter; Soergel, Elisabeth
2006-01-01
We present a large-area electro-optic Fabry-Perot modulator utilizing a photoaddressable bis-azo polymer placed between two dielectric mirrors with an open aperture of 2 cm. A modulation efficientcy of 1% at an effective modulation voltage of 20 V for a wavelength of 1.55 mymeter is demonstrated...
-
Directory of Open Access Journals (Sweden)
Liu J.
2016-03-01
Full Text Available Five polymers dispersed liquid crystalline (LC films were fabricated using photo-polymerizable monomers with different lengths of carbon chains. These LC films have shown different electro-optical (EO properties. Through their SEM pictures, the relationship between the linear electro-optical effect and the mesh size of the polymer network was explored. With the increase of number of photo-polymerizable monomers, the mesh size of the polymer network would become larger. So the liquid crystal molecules would be easily oriented in the electric field and therefore, the threshold voltage and saturation voltage would decrease. The open state response times were also reduced and the off state response times would be extended. The DFT simulations have shown principal role of the ground state dipole moments in the observed electro-optical efficiency.
-
International Nuclear Information System (INIS)
Junoh, H.; Jaafar, J.; Norddin, M.N.A.M.; Ismail, A.F.; Othman, M.H.D.; Rahman, M.A.; Yusof, N.; Salleh, W.N.W.; Junoh, H.; Jaafar, J.; Norddin, M.N.A.M.; Ismail, A.F.; Othman, M.H.D.; Rahman, M.A.; Yusof, N.; Salleh, W.N.W.; Hamid Ilbeygi, H.
2014-01-01
Proton exchange membrane (PEM) is an electrolyte which behaves as important indicator for fuel cell’s performance. Research and development (R and D) on fabrication of desirable PEM have burgeoned year by year, especially for direct methanol fuel cell (DMFC). However, most of the R and Ds only focus on the parent polymer electrolyte rather than polymer inorganic composites. This might be due to the difficulties faced in producing good dispersion of inorganic filler within the polymer matrix, which would consequently reduce the DMFC’s performance. Electro spinning is a promising technique to cater for this arising problem owing to its more widespread dispersion of inorganic filler within the polymer matrix, which can reduce the size of the filler up to nano scale. There has been a huge development on fabricating electrolyte nano composite membrane, regardless of the effect of electro spun nano composite membrane on the fuel cell’s performance. In this present paper, issues regarding the R and D on electro spun sulfonated poly (ether ether ketone) (SPEEK)/inorganic nano composite fiber are addressed.
-
Effects of static electricity and fabrication parameters on PVDF film ...
Indian Academy of Sciences (India)
2018-03-28
Mar 28, 2018 ... Degree of crystallinity and β-phase fraction are important factors in ... performance. In the present work, effects of intrinsic static electricity, substrate type, PVDF ... the best electroactive properties among all polymers [1] and.
-
Monitoring of composite structures using a network of integrated PVDF film transducers
International Nuclear Information System (INIS)
Guzmán, Enrique; Cugnoni, Joël; Gmür, Thomas
2015-01-01
Aiming to reduce costs, polyvinylidene difluoride (PVDF) film patches are an emerging alternative to more classic piezoelectric technologies, like ceramic patches, as transducers to measure local deformation in many structural applications. This choice is supported by advantages such as the low weight and mechanical flexibility of PVDF, making this polymer suitable for embedding inside full scale polymer based composite structures. Piezoelectric transducer patches can be used as actuators to dynamically excite full-scale composite structures, and as sensors to measure the strain. The main objective of this paper is to verify that the PVDF transducers can provide exploitable signals in the context of structural health monitoring. In order to do so, two aspects of the design of transducer network are investigated: the optimization of the sensor network, for which the effective independence method is proposed, and the use of operational modal analysis (OMA), since it is a simple method to extract the natural frequencies of a structure from a time series. The results of the analysis are compared to a reference set issued from experimental modal analysis (EMA), a simple, well-known, classic method, which is carried out using accelerometers and an impact hammer. By statistical means, it is shown that there is no significant difference between the two methods, and an optimized PVDF transducer network combined with OMA can perform the dynamic analysis of a structure as well as a classic EMA setup would do. This leads the way to the use of low-cost PVDF embedded transducer networks for robust composite material characterization. (paper)
-
A facile TiO{sub 2}/PVDF composite membrane synthesis and their application in water purification
Energy Technology Data Exchange (ETDEWEB)
Zhang, Wei, E-mail: wei.zhang@unisa.edu.au; Zhang, Yiming; Fan, Rong; Lewis, Rosmala [University of South Australia, Centre for Water Management and Reuse (Australia)
2016-01-15
In this work, we have demonstrated a facile wet chemical method to synthesise TiO{sub 2}/PVDF composite membranes as alternative water purification method to traditional polymer-based membrane. For the first time, hydrothermally grown TiO{sub 2} nanofibers under alkali conditions were successfully inserted into PVDF membranes matrix. The structure, permeability and anti-fouling performance of as-prepared PVDF/TiO{sub 2} composite membranes were studied systematically. The TiO{sub 2}/PVDF composite membranes prepared in this work promise great potential uses in water purification applications as microfiltration membranes due to its excellent physical/chemical resistance, anti-fouling and mechanical properties.
-
DEFF Research Database (Denmark)
Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.
2014-01-01
This paper presents a digital control technique toachieve valley switching in a bidirectional flyback converterused to drive a dielectric electro active polymer basedincremental actuator. The incremental actuator consists ofthree electrically isolated, mechanically connected capacitiveactuators...... switchingtechnique during both charge and discharge processes, withoutthe need to sense signals on the output high-voltage side.Experimental results verifying the bidirectional operation of asingle high voltage flyback converter are presented, using afilm capacitor as the load. Energy efficiency measurements...
-
A multifunctional PVDF-based tactile sensor for minimally invasive surgery
Sokhanvar, S.; Packirisamy, M.; Dargahi, J.
2007-08-01
In this paper a multifunctional tactile sensor system using PVDF (polyvinylidene fluoride), is proposed, designed, analyzed, tested and validated. The working principle of the sensor is in such a way that it can be used in combination with almost any end-effectors. However, the sensor is particularly designed to be integrated with minimally invasive surgery (MIS) tools. In addition, the structural and transduction materials are selected to be compatible with micro-electro-mechanical systems (MEMS) technology, so that miniaturization would be possible. The corrugated shape of the sensor ensures the safe tissue grasping and compatibility with the traditional tooth-like end effectors of MIS tools. A unit of this sensor comprised of a base, a flexible beam and three PVDF sensing elements. Two PVDF sensing elements sandwiched at the end supports work in thickness mode to measure the magnitude and position of applied load. The third PVDF sensing element is attached to the beam and it works in the extensional mode to measure the softness of the contact object. The proposed sensor is modeled both analytically and numerically and a series of simulations are performed in order to estimate the characteristics of the sensor in measuring the magnitude and position of a point load, distributed load, and also the softness of the contact object. Furthermore, in order to validate the theoretical results, the prototyped sensor was tested and the results are compared. The results are very promising and proving the capability of the sensor for haptic sensing.
-
International Nuclear Information System (INIS)
Senthil, R.A.; Theerthagiri, J.; Madhavan, J.; Murugan, K.; Arunachalam, Prabhakarn; Arof, A.K.
2016-01-01
This work describes the effect of 2-aminopyrimidine (2-APY) on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) blend polymer electrolyte along with binary iodide salts (tetrabutylammonium iodide (TBAI) and potassium iodide (KI)) and iodine (I 2 ) were studied for enhancing the efficiency of the dye-sensitized solar cells (DSSCs) consisting of g-C 3 N 4 /TiO 2 composite as photoanode. The g-C 3 N 4 was synthesized from low cost urea by thermal condensation method. It was used as a precursor to synthesize the various weight percentage ratios (5%, 10% and 15%) of g-C 3 N 4 /TiO 2 composites by wet-impregnation method. The pure and 2-APY incorporated PVDF-HFP/PEO polymer blend electrolytes were arranged by wet chemical process (casting method) using DMF as a solvent. The synthesized g-C 3 N 4 /TiO 2 composites and polymer blend electrolytes were studied and analyzed by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The ionic conductivity values of the pure and 2-APY incorporated PVDF-HFP/PEO blend electrolytes were estimated to be 4.53×10 −5 and 1.87×10 −4 Scm −1 respectively. The UV–vis absorption spectroscopy was carried out for the pure and different wt% of g-C 3 N 4 /TiO 2 composites coated FTO films after N3 dye-sensitization. The 10 wt% g-C 3 N 4 /TiO 2 composite film showed a maximum absorption compared to the others. The DSSC assembled with 10 wt% g-C 3 N 4 /TiO 2 as photoanode using the pure polymer blend electrolyte exhibited a power conversion efficiency (PCE) of 3.17% , which was superior than that of DSSC based pure TiO 2 (2.46%). However, the PCE was increased to 4.73% for the DSSC assembled using 10 wt% g-C 3 N 4 /TiO 2 as photoanode with 2-APY incorporated polymer blend electrolyte. Hence, the present study is a successful attempt to provide a new pathway to enhance the performance of DSSCs. - Graphical abstract: In this study, the g-C 3 N
-
Nanoclay-Directed Structure and Morphology in PVDF Electrospun Membranes
Directory of Open Access Journals (Sweden)
Kyunghwan Yoon
2014-01-01
Full Text Available The incorporation of organically modified Lucentite nanoclay dramatically modifies the structure and morphology of the PVDF electrospun fibers. In a molecular level, the nanoclay preferentially stabilizes the all-trans conformation of the polymer chain, promoting an α to β transformation of the crystalline phase. The piezoelectric properties of the β-phase carry great promise for energy harvest applications. At a larger scale, the nanoclay facilitates the formation of highly uniform, bead-free fibers. Such an effect can be attributed to the enhanced conductivity and viscoelasticity of the PVDF-clay suspension. The homogenous distribution of the directionally aligned nanoclays imparts advanced mechanical properties to the nanofibers.
-
Sezgin, Sinan; Sinirlioglu, Deniz; Muftuoglu, Ali Ekrem; Bozkurt, Ayhan
2014-01-01
Proton exchange membrane fuel cells (PEMFCs) are considered to be a promising technology for clean and efficient power generation in the twenty-first century. In this study, high performance of poly(vinylidene fluoride) (PVDF) and proton conductivity of poly(1-vinyl-1,2,4-triazole) (PVTri) were combined in a graft copolymer, PVDF-g-PVTri, by the polymerization of 1-vinyl-1,2,4-triazole on a PVDF based matrix under UV light in one step. The polymers were doped with triflic acid (TA) at differe...
-
Synthesis and electro-optic properties of the chromophore-containing NLO polyarylate polymers
Ren, Haohui; Peng, Chengcheng; Bo, Shuhui; Fan, Guofang; Xu, Guangming; Zhao, Hui; Zhen, Zhen; Liu, Xinhou
2014-03-01
Base on the same two monomers, diphenolic acid (DPA) and isophthaloyl chloride (IPC), three chromophore-containing nonlinear optical (NLO) polyarylate polymers were prepared. A tricyanofuran (TCF)-acceptor type chromophore group was in main-chain (mPAR-chr1), side-chain (sPAR-chr1) and side-chain with a 1,1-bis(4-hydroxyphenyl)-1-phenyl-2,2,2-trifluoroethane (BPAPF) group (sPAR-F-chr1), respectively. The obtained polymers were characterized and evaluated by UV-Vis, 1H NMR, DSC and TGA. All the polymers exhibited good electro-optic (EO) activity. The relationship between EO coefficients (r33) and the chromophore concentration of the three polymers were also characterized and discussed. There were no obvious differences found in EO activity between mPAR-chr1 and sPAR-chr1 polyarylates with the same chromophore. The fluorinated block polyarylate sPAR-F-chr1 has the largest r33 value in these three polyarylates which is 52 pm/V at the wavelength of 1310 nm (which is almost twice the r33 value of normal polymers contained the same chormophore at the same content), when the concentration of chromophore 1 is 18wt.%. 85% of the r33 value was retained in the sPAR-F-chr1 after being heated at 85°C for 600 hours. The polymer sPAR-F-chr1, with good solubility, high Tg (above 200 °C) and side functional group at the same time, may probably be a practical NLO material. These properties make the new polyarylates have potential applications in EO devices such as EO modulators and switches.
-
Directory of Open Access Journals (Sweden)
I.S. Elashmawi
Full Text Available Novel nanocomposites based on PVDF/PVC blend containing graphene oxide nanoparticles (GO were prepare using sonicator. IR analysis revealed that the addition of GO prompts a crystal transformation of α-phase of PVDF. The change of the structural before and after adding GO to PVDF/PVC were studied by X-ray diffraction. A decrease in activation energy gap from UV data was observed with increasing GO content, implying a variation of reactivity as a result of reaction extent. The variation of ε′ with frequency is nearly the same as that of ε″. At higher frequencies, the decrease of both ε′ and ε″ becomes nearly constant. The dispersion at lower frequencies ε′ of ε′ polarization is of Maxwell–Wagner interfacial polarization but at higher frequencies, it levels off. The behavior of conductivity (σAC tends to acquire constant values approaching it DC values. The values of σAC was increased after doped GO with exponential increase after the critical value of frequency. All nanocomposites behaved the same fashion revealing that a higher number of polarons were getting added to conducting pool in composites as graphene content was increased. Conduction mechanism appeared to be getting expedited with increasing frequency due to fact that increase in frequency enhances polaron hopping frequency. Keywords: Nanocomposites, Graphene oxide, FT-IR, X-ray, AC conductivity
-
Park, Jihoon
2015-01-01
We report a simple two-step annealing scheme for the fabrication of stable non-volatile memory devices employing poly(vinylidene fluoride) (PVDF) polymer thin-films. The proposed two-step annealing scheme comprises the crystallization of the ferroelectric gamma-phase during the first step and enhancement of the PVDF film dense morphology during the second step. Moreover, when we extended the processing time of the second step, we obtained good hysteresis curves down to 1 Hz, the first such report for ferroelectric PVDF films. The PVDF films also exhibit a coercive field of 113 MV m-1 and a ferroelectric polarization of 5.4 μC cm-2. © The Royal Society of Chemistry 2015.
-
Ultra-thin silicon/electro-optic polymer hybrid waveguide modulators
Energy Technology Data Exchange (ETDEWEB)
Qiu, Feng; Spring, Andrew M. [Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Sato, Hiromu [Department of Molecular and Material Sciences, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Maeda, Daisuke; Ozawa, Masa-aki; Odoi, Keisuke [Nissan Chemical Industries, Ltd., 2-10-1 Tuboi Nishi, Funabashi, Chiba 274-8507 (Japan); Aoki, Isao; Otomo, Akira [National Institute of Information and Communications Technology, 588-2 Iwaoka, Nishi-ku, Kobe 651-2492 (Japan); Yokoyama, Shiyoshi, E-mail: s-yokoyama@cm.kyushu-u.ac.jp [Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Department of Molecular and Material Sciences, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan)
2015-09-21
Ultra-thin silicon and electro-optic (EO) polymer hybrid waveguide modulators have been designed and fabricated. The waveguide consists of a silicon core with a thickness of 30 nm and a width of 2 μm. The cladding is an EO polymer. Optical mode calculation reveals that 55% of the optical field around the silicon extends into the EO polymer in the TE mode. A Mach-Zehnder interferometer (MZI) modulator was prepared using common coplanar electrodes. The measured half-wave voltage of the MZI with 7 μm spacing and 1.3 cm long electrodes is 4.6 V at 1550 nm. The evaluated EO coefficient is 70 pm/V, which is comparable to that of the bulk EO polymer film. Using ultra-thin silicon is beneficial in order to reduce the side-wall scattering loss, yielding a propagation loss of 4.0 dB/cm. We also investigated a mode converter which couples light from the hybrid EO waveguide into a strip silicon waveguide. The calculation indicates that the coupling loss between these two devices is small enough to exploit the potential fusion of a hybrid EO polymer modulator together with a silicon micro-photonics device.
-
Radiation resistance of electro-optic polymer-based modulators
International Nuclear Information System (INIS)
Taylor, Edward W.; Nichter, James E.; Nash, Fazio D.; Haas, Franz; Szep, Attila A.; Michalak, Richard J.; Flusche, Brian M.; Cook, Paul R.; McEwen, Tom A.; McKeon, Brian F.; Payson, Paul M.; Brost, George A.; Pirich, Andrew R.; Castaneda, Carlos; Tsap, Boris; Fetterman, Harold R.
2005-01-01
Mach-Zehnder interferometric electro-optic polymer modulators composed of highly nonlinear phenyltetraene bridge-type chromophores within an amorphous polycarbonate host matrix were investigated for their resistance to gamma rays and 25.6 MeV protons. No device failures were observed and the majority of irradiated modulators exhibited decreases in half-wave voltage and optical insertion losses compared to nonirradiated control samples undergoing aging processes. Irradiated device responses were attributed to scission, cross-linking, and free volume processes. The data suggests that strongly poled devices are less likely to de-pole under the influence of ionizing radiation
-
Fabrication of Carbon Nanotube Polymer Actuator Using Nanofiber Sheet
Kato, Hayato; Shimizu, Akikazu; Sato, Taiga; Kushida, Masahito
2017-11-01
Carbon nanotube polymer actuators were developed using composite nanofiber sheets fabricated by multi-walled carbon nanotubes(MWCNTs) and poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Nanofiber sheets were fabricated by electrospinning method. The effect of flow rate and polymer concentration on nanofiber formation were verified for optimum condition for fabricating nanofiber sheets. We examined the properties of MWCNT/PVDF-HFP nanofiber sheets, as follows. Electrical conductivity and mechanical strength increased as the MWCNT weight ratio increased. We fabricated carbon nanotube polymer actuators using MWCNT/PVDF-HFP nanofiber sheets and succeeded in operating of our actuators.
-
Piezoelectric and optoelectronic properties of electrospinning hybrid PVDF and ZnO nanofibers
Ma, Jian; Zhang, Qian; Lin, Kabin; Zhou, Lei; Ni, Zhonghua
2018-03-01
Polyvinylidene fluoride (PVDF) is a unique ferroelectric polymer with significant promise for energy harvesting, data storage, and sensing applications. ZnO is a wide direct band gap semiconductor (3.37 eV), commonly used as ultraviolet photodetectors, nanoelectronics, photonicsand piezoelectric generators. In this study, we produced high output piezoelectric energy harvesting materials using hybrid PVDF/ZnO nanofibers deposited via electrospinning. The strong electric fields and stretching forces during the electrospinning process helps to align dipoles in the nanofiber crystal such that the nonpolar α-phase (random orientation of dipoles) is transformed into polar β-phase in produced nanofibers. The effect of the additional ZnO nanowires on the nanofiber β-phase composition and output voltage are investigated. The maximum output voltage generated by a single hybrid PVDF and ZnO nanofiber (33 wt% ZnO nanowires) is over 300% of the voltage produced by a single nanofiber made of pure PVDF. The ZnO NWs served not only as a piezoelectric material, but also as a semiconducting material. The electrical conductivity of the hybrid PVDF/ZnO nanofibers increased by more than a factor of 4 when exposed under ultraviolet (UV) light.
-
Remanan, Sanjay; Sharma, Maya; Jayashree, Priyadarshini; Parameswaranpillai, Jyotishkumar; Fabian, Thomas; Shih, Julie; Shankarappa, Prasad; Nuggehalli, Bharath; Bose, Suryasarathi
2017-06-01
This study demonstrates flame retardant materials designed using bi-phasic polymer blends of acrylonitrile butadiene styrene (ABS) and polyvinylidene fluoride (PVDF) containing halloysite nanotubes (HNTs) and Cloisite 30B nanoclay. The prepared blends with and without nanoparticles were extensively characterized. The nanoparticles were added in different weight concentrations to improve the flame retardancy. It was observed that prepared ABS/PVDF blends showed better flame retardancy than ABS based composites. The flame resistance was further improved by the addition of nanoparticles in the blends. The microscale combustion calorimetry (MCC) test showed better flame resistance in ABS/PVDF blends filled with 5 wt% HNTs than other composites. The total heat release of ABS/PVDF blend filled with 5 wt% HNTs decreased by 31% and also the heat of combustion decreased by 26% as compared to neat ABS. When compared with nanoparticles, the addition of PVDF reduced the peak heat release rate (PHRR) and increased the char residue more effectively. A synergistic improvement was observed from both PVDF and HNTs on the flame resistance properties.
-
Nanocomposites for Improved Physical Durability of Porous PVDF Membranes
Lai, Chi Yan; Groth, Andrew; Gray, Stephen; Duke, Mikel
2014-01-01
Current commercial polymer membranes have shown high performance and durability in water treatment, converting poor quality waters to higher quality suitable for drinking, agriculture and recycling. However, to extend the treatment into more challenging water sources containing abrasive particles, micro and ultrafiltration membranes with enhanced physical durability are highly desirable. This review summarises the current limits of the existing polymeric membranes to treat harsh water sources, followed by the development of nanocomposite poly(vinylidene fluoride) (PVDF) membranes for improved physical durability. Various types of nanofillers including nanoparticles, carbon nanotubes (CNT) and nanoclays were evaluated for their effect on flux, fouling resistance, mechanical strength and abrasion resistance on PVDF membranes. The mechanisms of abrasive wear and how the more durable materials provide resistance was also explored. PMID:24957121
-
International Nuclear Information System (INIS)
York, A; Seelecke, S; Dunn, J
2010-01-01
Dielectric electro-active polymers (DEAPs) can achieve substantial deformation (>300% strain) while sustaining, compared to their ionic counterparts, large forces. This makes them attractive for various actuation and sensing applications such as in light weight and energy efficient valve and pumping systems. Many applications operate DEAP actuators at higher frequencies where rate-dependent effects influence their performance. This motivates the seeking of dynamic characterization of these actuators beyond the quasi-static regime. This paper provides a systematic experimental investigation of the quasi-static and dynamic electromechanical properties of a DEAP actuator. In order to completely characterize the fully coupled behavior, force versus displacement measurements at various constant voltages and force versus voltage measurements at various fixed displacements are conducted. The experiments are conducted with a particular focus on the hysteretic and rate-dependent material behavior. These experiments provide insight into the electrical dynamics and viscoelastic relaxation inherent in DEAP actuators. This study is intended to provide information, including high frequency performance analysis, useful to anyone designing dynamic actuator systems using DEAPs
-
Demonstration of an optical phased array using electro-optic polymer phase shifters
Hirano, Yoshikuni; Motoyama, Yasushi; Tanaka, Katsu; Machida, Kenji; Yamada, Toshiki; Otomo, Akira; Kikuchi, Hiroshi
2018-03-01
We have been investigating an optical phased array (OPA) using electro-optic (EO) polymers in phase shifters to achieve ultrafast optical beam steering. In this paper, we describe the basic structures of the OPA using EO polymer phase shifters and show the beam steering capability of the OPA. The designed OPA has a multimode interference (MMI) beam splitter and 8-channel polymer waveguides with EO polymer phase shifters. We compare 1 × 8 MMI and cascaded 1 × 2 MMI beam splitters numerically and experimentally, and then obtain uniform intensity outputs from the 1 × 8 beam splitter. We fabricate the EO polymer OPA with a 1 × 8 MMI beam splitter to prevent intensity dispersion due to radiation loss in bending waveguides. We also evaluate the optical beam steering capability of the fabricated OPA and found a 2.7° deflection of far-field patterns when applying a voltage difference of 25 V in adjacent phase shifters.
-
Buehler, Martin (Inventor)
2009-01-01
An electro-active sensor includes a nonconductive platform with a first electrode set attached with a first side of a nonconductive platform. The first electrode set serves as an electrochemical cell that may be utilized to detect electro-active species in solution. A plurality of electrode sets and a variety of additional electrochemical cells and sensors may be attached with the nonconductive platform. The present invention also includes a method for constructing the aforementioned electro-active sensor. Additionally, an apparatus for detection and observation is disclosed, where the apparatus includes a sealable chamber for insertion of a portion of an electro-active sensor. The apparatus allows for monitoring and detection activities. Allowing for control of attached cells and sensors, a dual-mode circuitry is also disclosed. The dual-mode circuitry includes a switch, allowing the circuitry to be switched from a potentiostat to a galvanostat mode.
-
Directory of Open Access Journals (Sweden)
Aisha Al-Saygh
2017-01-01
Full Text Available A novel flexible nanocomposite pressure sensor with a tensile strength of about 47 MPa is fabricated in this work. Nanolayers of titanium dioxide (titania nanolayers, TNL synthesized by hydrothermal method are used to reinforce the polyvinylidene fluoride (PVDF by simple solution mixing. A hybrid composite is prepared by incorporating the TNL (2.5 wt % with reduced graphene oxide (rGO (2.5 wt % synthesized by improved graphene oxide synthesis to form a PVDF/rGO-TNL composite. A comparison between PVDF, PVDF/rGO (5 wt %, PVDF/TNL (5 wt % and PVDF/rGO-TNL (total additives 5 wt % samples are analyzed for their sensing, thermal and dielectric characteristics. The new shape of additives (with sharp morphology, good interaction and well distributed hybrid additives in the matrix increased the sensitivity by 333.46% at 5 kPa, 200.7% at 10.7 kPa and 246.7% at 17.6 kPa compared to the individual PVDF composite of TNL, confirming its possible application in fabricating low cost and light weight pressure sensing devices and electronic devices with reduced quantity of metal oxides. Increase in the β crystallinity percentage and removal of α phase for PVDF was detected for the hybrid composite and linked to the improvement in the mechanical properties. Tensile strength for the hybrid composite (46.91 MPa was 115% higher than that of the neat polymer matrix. Improvement in the wettability and less roughness in the hybrid composites were observed, which can prevent fouling, a major disadvantage in many sensor applications.
-
International Nuclear Information System (INIS)
York, A; Seelecke, S; Dunn, J
2013-01-01
Dielectric electro-active polymers (DEAPs) have become attractive materials for various actuation and sensing applications due to their high energy and power density, high efficiency, light weight, and fast response speed. However, commercial development has been hindered due to a variety of constraints such as reliability, non-linear behavior, cost of driving electronics, and form factor requirements. This paper presents the systematic development from laboratory concept to commercial readiness of a novel pressure sensing system using a DEAP membrane. The pressure sensing system was designed for in-line pressure measurements for low pressure applications such as health systems monitoring. A first generation sensor was designed, built and tested with a focus on the qualitative capabilities of EAP membranes as sensors. Experimental measurements were conducted that demonstrated the capability of the sensor to output a voltage signal proportional to a changing pressure. Several undesirable characteristics were observed during these initial tests such as strong hysteresis, non-linearity, very limited pressure range, and low fatigue life. A second generation prototype was then designed to remove or compensate for these undesirable characteristics. This prototype was then built and tested. The new design showed an almost complete removal of hysteretic non-linear effects and was capable of operating at 10 × the pressure range of the initial generation. This new design is the framework for a novel DEAP based pressure sensor ready for commercial applications. (paper)
-
Czech Academy of Sciences Publication Activity Database
Malik, P.; Bubnov, Alexej M.; Raina, K.K.
2008-01-01
Roč. 494, č. 12 (2008), s. 242-251 ISSN 1542-1406 Institutional research plan: CEZ:AV0Z10100520 Keywords : polymer dispersed liquid crystals * electro-optics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.537, year: 2008
-
On nonlinear thermo-electro-elasticity.
Mehnert, Markus; Hossain, Mokarram; Steinmann, Paul
2016-06-01
Electro-active polymers (EAPs) for large actuations are nowadays well-known and promising candidates for producing sensors, actuators and generators. In general, polymeric materials are sensitive to differential temperature histories. During experimental characterizations of EAPs under electro-mechanically coupled loads, it is difficult to maintain constant temperature not only because of an external differential temperature history but also because of the changes in internal temperature caused by the application of high electric loads. In this contribution, a thermo-electro-mechanically coupled constitutive framework is proposed based on the total energy approach. Departing from relevant laws of thermodynamics, thermodynamically consistent constitutive equations are formulated. To demonstrate the performance of the proposed thermo-electro-mechanically coupled framework, a frequently used non-homogeneous boundary-value problem, i.e. the extension and inflation of a cylindrical tube, is solved analytically. The results illustrate the influence of various thermo-electro-mechanical couplings.
-
Energy Technology Data Exchange (ETDEWEB)
Senthil, R.A.; Theerthagiri, J. [Solar Energy Lab, Department of Chemistry, Thiruvalluvar University, Vellore 632115 (India); Madhavan, J., E-mail: jagan.madhavan@gmail.com [Solar Energy Lab, Department of Chemistry, Thiruvalluvar University, Vellore 632115 (India); Murugan, K. [Department of Zoology, Bharathiar University, Coimbatore 641046 (India); Arunachalam, Prabhakarn [Electrochemistry Research Group, Chemistry Department, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia); Arof, A.K. [Centre for Ionics University Malaya, Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia)
2016-10-15
This work describes the effect of 2-aminopyrimidine (2-APY) on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) blend polymer electrolyte along with binary iodide salts (tetrabutylammonium iodide (TBAI) and potassium iodide (KI)) and iodine (I{sub 2}) were studied for enhancing the efficiency of the dye-sensitized solar cells (DSSCs) consisting of g-C{sub 3}N{sub 4}/TiO{sub 2} composite as photoanode. The g-C{sub 3}N{sub 4} was synthesized from low cost urea by thermal condensation method. It was used as a precursor to synthesize the various weight percentage ratios (5%, 10% and 15%) of g-C{sub 3}N{sub 4}/TiO{sub 2} composites by wet-impregnation method. The pure and 2-APY incorporated PVDF-HFP/PEO polymer blend electrolytes were arranged by wet chemical process (casting method) using DMF as a solvent. The synthesized g-C{sub 3}N{sub 4}/TiO{sub 2} composites and polymer blend electrolytes were studied and analyzed by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The ionic conductivity values of the pure and 2-APY incorporated PVDF-HFP/PEO blend electrolytes were estimated to be 4.53×10{sup −5} and 1.87×10{sup −4} Scm{sup −1} respectively. The UV–vis absorption spectroscopy was carried out for the pure and different wt% of g-C{sub 3}N{sub 4}/TiO{sub 2} composites coated FTO films after N3 dye-sensitization. The 10 wt% g-C{sub 3}N{sub 4}/TiO{sub 2} composite film showed a maximum absorption compared to the others. The DSSC assembled with 10 wt% g-C{sub 3}N{sub 4}/TiO{sub 2} as photoanode using the pure polymer blend electrolyte exhibited a power conversion efficiency (PCE) of 3.17% , which was superior than that of DSSC based pure TiO{sub 2} (2.46%). However, the PCE was increased to 4.73% for the DSSC assembled using 10 wt% g-C{sub 3}N{sub 4}/TiO{sub 2} as photoanode with 2-APY incorporated polymer blend electrolyte. Hence, the present study is a
-
International Nuclear Information System (INIS)
Liu, Jiuqing; Wu, Xiufeng; He, Junying; Li, Jie; Lai, Yanqing
2017-01-01
Poly(vinylidenefluoride)/graphene (PVDF/graphene) gel polymer electrolyte is prepared via non-solvent induced phase separation (NIPS) technique for lithium ion battery application. The effect of graphene on the ion conductivity is investigated by AC impedance measurement. The relationship among the chemical structure, PVDF crystallinity, the graphene on macroporous formation and the ion conductivity are investigated. The results indicate that the graphene disperses homogenously in PVDF, and it also increases the porosity and decreases the crystallinity of the PVDF. At the same time, the unique structure increases the liquid uptake capability of PVDF/graphene polymer electrolyte. The ionic conductivity of the PVDF/graphene polymer electrolyte increases significantly from 1.85 mS cm"−"1 in pristine PVDF to 3.61 mS cm"−"1 with 0.002 wt% graphene. It is found that graphene not only increases the ionic conductivity but also markedly enhances the rate capability and the cycling performances of coin cell. This study shows that PVDF/graphene gel polymer electrolyte is a very promising material for lithium ion batteries.
-
Directory of Open Access Journals (Sweden)
Vincenzo Guarino
2016-05-01
Full Text Available Through recent discoveries and new knowledge among correlations between molecular biology and materials science, it is a growing interest to design new biomaterials able to interact—i.e., to influence, to guide or to detect—with cells and their surrounding microenvironments, in order to better control biological phenomena. In this context, electro-active polymers (EAPs are showing great promise as biomaterials acting as an interface between electronics and biology. This is ascribable to the highly tunability of chemical/physical properties which confer them different conductive properties for various applicative uses (i.e., molecular targeting, biosensors, biocompatible scaffolds. This review article is divided into three parts: the first one is an overview on EAPs to introduce basic conductivity mechanisms and their classification. The second one is focused on the description of most common processes used to manipulate EAPs in the form of two-dimensional (2D and three-dimensional (3D materials. The last part addresses their use in current applications in different biomedical research areas including tissue engineering, biosensors and molecular delivery.
-
Polymer waveguides for electro-optical integration in data centers and high-performance computers.
Dangel, Roger; Hofrichter, Jens; Horst, Folkert; Jubin, Daniel; La Porta, Antonio; Meier, Norbert; Soganci, Ibrahim Murat; Weiss, Jonas; Offrein, Bert Jan
2015-02-23
To satisfy the intra- and inter-system bandwidth requirements of future data centers and high-performance computers, low-cost low-power high-throughput optical interconnects will become a key enabling technology. To tightly integrate optics with the computing hardware, particularly in the context of CMOS-compatible silicon photonics, optical printed circuit boards using polymer waveguides are considered as a formidable platform. IBM Research has already demonstrated the essential silicon photonics and interconnection building blocks. A remaining challenge is electro-optical packaging, i.e., the connection of the silicon photonics chips with the system. In this paper, we present a new single-mode polymer waveguide technology and a scalable method for building the optical interface between silicon photonics chips and single-mode polymer waveguides.
-
Improved PVDF membrane performance by doping extracellular polymeric substances of activated sludge.
Guan, Yan-Fang; Huang, Bao-Cheng; Qian, Chen; Wang, Long-Fei; Yu, Han-Qing
2017-04-15
Polyvinylidene fluoride (PVDF) membrane has been widely applied in water and wastewater treatment because of its high mechanical strength, thermal stability and chemical resistance. However, the hydrophobic nature of PVDF membrane makes it readily fouled, substantially reducing water flux and overall membrane rejection ability. In this work, an in-situ blending modifier, i.e., extracellular polymeric substances (EPS) from activated sludge, was used to enhance the anti-fouling ability of PVDF membrane. Results indicate that the pure water flux of the membrane and its anti-fouling performance were substantially improved by blending 8% EPS into the membrane. By introducing EPS, the membrane hydrophilicity was increased and the cross section morphology was changed when it interacted with polyvinl pyrrolidone, resulting in the formation of large cavities below the finger-like pores. In addition, the fraction of pores with a size of 100-500 nm increased, which was also beneficial to improving membrane performance. Surface thermodynamic calculations indicate the EPS-functionalized membrane had a higher cohesion free energy, implying its good pollutant rejection and anti-fouling ability. This work provides a simple, efficient and cost-effective method to improve membrane performance and also extends the applications of EPS. Copyright © 2017 Elsevier Ltd. All rights reserved.
-
Electro-Active Polymer (EAP) Actuators for Planetary Applications
Bar-Cohen, Y.; Leary, S.; Shahinpoor, M.; Harrison, J. O.; Smith, J.
1999-01-01
NASA is seeking to reduce the mass, size, consumed power, and cost of the instrumentation used in its future missions. An important element of many instruments and devices is the actuation mechanism and electroactive polymers (EAP) are offering an effective alternative to current actuators. In this study, two families of EAP materials were investigated, including bending ionomers and longitudinal electrostatically driven elastomers. These materials were demonstrated to effectively actuate manipulation devices and their performance is being enhanced in this on-going study. The recent observations are reported in this paper, include the operation of the bending-EAP at conditions that exceed the harsh environment on Mars, and identify the obstacles that its properties and characteristics are posing to using them as actuators. Analysis of the electrical characteristics of the ionomer EAP showed that it is a current driven material rather than voltage driven and the conductivity distribution on the surface of the material greatly influences the bending performance. An accurate equivalent circuit modeling of the ionomer EAP performance is essential for the design of effective drive electronics. The ionomer main limitations are the fact that it needs to be moist continuously and the process of electrolysis that takes place during activation. An effective coating technique using a sprayed polymer was developed extending its operation in air from a few minutes to about four months. The coating technique effectively forms the equivalent of a skin to protect the moisture content of the ionomer. In parallel to the development of the bending EAP, the development of computer control of actuated longitudinal EAP has been pursued. An EAP driven miniature robotic arm was constructed and it is controlled by a MATLAB code to drop and lift the arm and close and open EAP fingers of a 4-finger gripper. Keywords: Miniature Robotics, Electroactive Polymers, Electroactive Actuators, EAP
-
Design of UV-absorbing PVDF membrane via surface-initiated AGET ATRP
Dong, Li; Liu, Xiangdong; Xiong, Zhengrong; Sheng, Dekun; Zhou, Yan; Lin, Changhong; Yang, Yuming
2018-03-01
Herein, PVDF membranes with excellent UV-absorbing property were first synthesized through grafting the polymerizable low-molecular-weight organic UV-absorber 2-hydroxy-4-(3-methacryloxy-2-hydroxylpropoxy) benzophenone (BPMA) onto α-bromoester-functionalized PVDF membranes via the surface-initiated activator generated by electron transfer atom transfer radical polymerization (SI-AGET ATRP). The surface initiators were immobilized by the reaction between 2-bromoisobutyryl bromide (BIBB) and the hydroxylated PVDF membranes. PVDF-g-PBPMA membranes with different grafting densities were obtained by tuning the polymerization time and the modified membranes were characterized by 1H-NMR, FT-IR, XPS, SEM, UV-vis Spectrophotometer, TGA and DSC. The experimental results indicated that PBPMA chains were successfully introduced onto PVDF membranes. Most importantly, the PVDF-g-PBPMA membranes exhibited outstanding UV-shielding property. UV-vis transmittance spectra showed that most UV light below 360 nm could be absorbed by PVDF-g-PBPMA membranes and the whole UV light region (200-400 nm) can be blocked with the reaction time increased.
-
Electro-optical properties of a polymer light-emitting diode with an injection-limited hole contact
van Woudenbergh, T; Blom, PWM; Huiberts, JN
2003-01-01
The electro-optical characteristics of a polymer light-emitting diode with a strongly reduced hole injection have been investigated. A silver contact on poly-dialkoxy-p-phenylene vinylene decreases the hole injection by five orders of magnitude, resulting in both a highly reduced light output and
-
International Nuclear Information System (INIS)
Xu, Chenqi; Huang, Wei; Lu, Xin; Yan, Deyue; Chen, Shutao; Huang, Hua
2012-01-01
The hydrophilic PVDF-g-PVP powder was used as additive to prepare a series of PVDF/PVDF-g-PVP blend porous membranes via an immersion precipitation phase inversion process. FTIR-ATR measurements confirmed that the hydrophilic PVP preferentially segregated to the interface between membrane and coagulant. SEM images showed that there was no big change in the membrane cross-section with the amount of PVDF-g-PVP increased. However, the membrane surface roughness increased with the amount of PVDF-g-PVP increased according to AFM data. The mean pore size of membranes reached max when the amount of PVDF-g-PVP was 10 wt%. The water contact angle and filtration experiments revealed that the surface enrichment of PVP endowed the membranes with significantly enhanced surface hydrophilicity and protein-adsorption resistance. The flux recovery of the porous membranes was increased from 37.50% to 77.23% with the amount of PVDF-g-PVP increased from 0 to 50 wt%, also indicating that the antifouling property of the porous membranes was improved. - Highlights: ► The hydrophilic PVDF-g-PVP powder is used as additive to prepare PVDF/PVDF-g-PVP blend porous membranes. ► The immersion precipitation phase inversion process is adopted to prepare the blend membranes. ► The hydrophilicity of the porous membranes surface is enhanced with increasing the amount of PVDF-g-PVP. ► The pure water flux of the porous membranes depends on the amount of PVDF-g-PVP in the porous membranes. ► Antifouling property of the porous membranes is improved obviously comparing with a pristine PVDF membrane.
-
Piezoelectric PVDF materials performance and operation limits in space environments
International Nuclear Information System (INIS)
Dargaville, Tim Richard; Assink, Roger Alan; Clough, Roger Lee; Celina, Mathias Christopher
2004-01-01
Piezoelectric polymers based on polyvinylidene fluoride (PVDF) are of interest for large aperture space-based telescopes. Dimensional adjustments of adaptive polymer films are achieved via charge deposition and require a detailed understanding of the piezoelectric material responses which are expected to suffer due to strong vacuum UV, gamma, X-ray, energetic particles and atomic oxygen under low earth orbit exposure conditions. The degradation of PVDF and its copolymers under various stress environments has been investigated. Initial radiation aging studies using gamma- and e-beam irradiation have shown complex material changes with significant crosslinking, lowered melting and Curie points (where observable), effects on crystallinity, but little influence on overall piezoelectric properties. Surprisingly, complex aging processes have also been observed in elevated temperature environments with annealing phenomena and cyclic stresses resulting in thermal depoling of domains. Overall materials performance appears to be governed by a combination of chemical and physical degradation processes. Molecular changes are primarily induced via radiative damage, and physical damage from temperature and AO exposure is evident as depoling and surface erosion. Major differences between individual copolymers have been observed providing feedback on material selection strategies
-
Structural changes in PVDF fibers due to electrospinning and its effect on biological function
International Nuclear Information System (INIS)
Damaraju, Sita M; Wu, Siliang; Jaffe, Michael; Arinzeh, Treena Livingston
2013-01-01
Polyvinylidine fluoride (PVDF) is being investigated as a potential scaffold for bone tissue engineering because of its proven biocompatibility and piezoelectric property, wherein it can generate electrical activity when mechanically deformed. In this study, PVDF scaffolds were prepared by electrospinning using different voltages (12–30 kV), evaluated for the presence of the piezoelectric β-crystal phase and its effect on biological function. Electrospun PVDF was compared with unprocessed/raw PVDF, films and melt-spun fibers for the presence of the piezoelectric β-phase using differential scanning calorimetry, Fourier transform infrared spectroscopy and x-ray diffraction. The osteogenic differentiation of human mesenchymal stem cells (MSCs) was evaluated on scaffolds electrospun at 12 and 25 kV (PVDF-12 kV and PVDF-25 kV, respectively) and compared to tissue culture polystyrene (TCP). Electrospinning PVDF resulted in the formation of the piezoelectric β-phase with the highest β-phase fraction of 72% for electrospun PVDF at 25 kV. MSCs cultured on both the scaffolds were well attached as indicated by a spread morphology. Cells on PVDF-25 kV scaffolds had the greatest alkaline phosphatase activity and early mineralization by day 10 as compared to TCP and PVDF-12 kV. The results demonstrate the potential for the use of PVDF scaffolds for bone tissue engineering applications. (paper)
-
Park, Jihoon; Kurra, Narendra; AlMadhoun, M. N.; Odeh, Ihab N.; Alshareef, Husam N.
2015-01-01
We report a simple two-step annealing scheme for the fabrication of stable non-volatile memory devices employing poly(vinylidene fluoride) (PVDF) polymer thin-films. The proposed two-step annealing scheme comprises the crystallization
-
based gel polymer electrolytes
Indian Academy of Sciences (India)
(PVdF) as a host polymer, lithium perchlorate (LiClO4), lithium triflate ... TG/DTA studies showed the thermal stability of the polymer electrolytes. .... are observed while comparing pure XRD spectra with .... batteries as its operating temperature is normally in the .... chain ion movements and the conductivity of the polymer.
-
Energy Technology Data Exchange (ETDEWEB)
Inan, Tuelay Y.; Dogan, Hacer; Unveren, Elif E. [The Scientific and Technological Research Council of Turkey (TUBITAK), Marmara Research Center, Chemistry Institute, 41470 Gebze, Kocaeli (Turkey); Eker, Ersoy [Tuerk Demirdoekuem Fabrikalari A.S., 11300 Bozueyuek, Bilecik (Turkey)
2010-11-15
This work clearly demonstrates the effect of the type and molecular weight of the fluorinated polymer of SPEEK/Fluorinated polymer blends for low temperature (<80 C) Fuel Cell Applications. Comparisons with trademarks (e.g., Nafion {sup registered}) suggests that the membranes we have prepared in this study have good compatibility in all application respects. Membranes were prepared by solution casting method from four different fluorinated polymers; poly (vinylidene fluoride) with three different molecular weights (PVDF, M{sub w}: 180.000, M{sub w}: 275.000, M{sub w}: 530.000); Poli(vinylidene fluoride-co-Hexafluoro propylen) (PVDF-HFP M{sub n}:130.000) and sulfonated poly(ether ether ketone) (SPEEK) with sulfonation degree (SD) of 70. The sulfonation degree (SD) of SPEEK was determined by FTIR, {sup 1}H NMR and ion exchange capacity (IEC) measurements. Thermo-oxidative stability and proton conductivity of the membranes were determined by using thermal gravimetric analysis (TGA) and BT-512 BekkTech membrane test systems, respectively. Chemical degradation of SPEEK membranes was investigated via Fenton test. The morphology of the membranes were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Water uptake and proton conductivity values decreased with the addition of fluorinated polymers (PVDF, PVDF-HFP) as expected, but proton conductivity values were still comparable to that of Nafion 117 {sup registered} membrane. Addition of fluorinated polymers improved chemical degradation of the blend membranes in all ratios while addition of PVDF-HFP to the SPEEK70 caused phase separations in all ratios. Methanol permeability value of SPEEK70/PVDF(M{sub w} = 275.000) blend membrane (3.13E-07 (cm{sup 2}/s)) was much lower than Nafion 117 {sup registered} (1.21E-06 (cm{sup 2}/s)). PVDF addition to the SPEEK polymers caused increase in elongation of the membranes. Increase in the molecular weight of the PVDF did not show any effect on
-
Spectral response analysis of PVDF capacitive sensors
Reyes-Ramírez, B.; García-Segundo, C.; García-Valenzuela, A.
2013-06-01
We investigate the spectral response to ultrasound waves in water of low-noise capacitive sensors based on PVDF polymer piezoelectric films. First, we analyze theoretically the mechanical-to-electrical transduction as a function of the frequency of ultrasonic signals and derive an analytic expression of the sensor's transfer function. Then we present experimental results of the frequency response of a home-made PDVF in water to test signals from 1 to 20 MHz induced by a commercial hydrophone powered by a signal generator and compare with our theoretical model.
-
Ferroelectric Phase Diagram of PVDF:PMMA
Li, Mengyuan; Stingelin, Natalie; Michels, Jasper J.; Spijkman, Mark-Jan; Asadi, Kamal; Feldman, Kirill; Blom, Paul W. M.; de Leeuw, Dago M.
2012-01-01
We have investigated the ferroelectric phase diagram of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA). The binary nonequilibrium temperature composition diagram was determined and melting of alpha- and beta-phase PVDF was identified. Ferroelectric beta-PVDF:PMMA blend films were made by melting, ice quenching, and subsequent annealing above the glass transition temperature of PMMA, close to the melting temperature of PVDF. Addition of PMMA suppresses the crystallizatio...
-
International Nuclear Information System (INIS)
Sohn, Joon Yong; Shin, Jun Hwa; Nho, Young Chang
2010-01-01
PVDF-HFP (binder)/silylated alumina (inorganic particle)-coated PE (polyethylene)separators were with various compositions of binder and inorganic particle were prepared by a dip-coating process with humidity control (R.H. 25% and 50%) using electron beam irradiation. The morphology of the coated PVDF-HFP/AI 2 O 3 layer with various compositions of PVDF-HFP and AI 2 O 3 , and humidity condition was found to be an important factor in determining ionic conductivity of the prepared separators. The PVDF-HFP/AI 2 O 3 (5/5)-coated PE separator prepared at R.H. 50% followed by electron beam irradiation at 200 kGy was applied for lithium-ion polymer battery and cell test results showed improved high-rate discharge performance and better cyclic stability compared to the cells with the bare PE and the PVDF-HFP-coated PE separators
-
Zhao, Xinzhen; He, Chunju
2015-08-19
On the basis of the excellent fouling resistance of zwitterionic materials, the super antifouling polyvinylidene fluoride (PVDF) membrane was efficiently prepared though one-step sulfonation of PVDF and polyaniline blend membrane in situ. The self-doped sulfonated polyaniline (SPANI) was generated as a novel zwitterionic polymer to improve the antifouling property of PVDF ultrafiltration membrane used in sewage treatment. Surface attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, surface zeta potential, and water contact angle demonstrated the successful fabrication of zwitterionic interface by convenient sulfonation modification. The static adsorption fouling test showed the quantified adsorption mass of bovine serum albumin (BSA) pollutant on the PVDF/SPANI membrane surface decreases to 3(±2) μg/cm(2), and the water flux recovery ratio (FRR) values were no less than 95% for the three model pollutants of BSA, sodium alginate (SA), and humic acid (HA), which were corresponding hydrophobic, hydrophilic, and natural pollutants in sewage, respectively. This Research Article demonstrated the antifouling advantages of zwitterionic SPANI and aimed to provide a simple method for the large scale preparation of zwitterionic antifouling ultrafiltration membranes.
-
Solid-state-processing of d_PVDF
Martín, Jaime; Zhao, Dong; Lenz, Thomas; Katsouras, Ilias; de Leeuw, Dago M.; Stingelin, Natalie
2017-01-01
Poly(vinylidene fluoride) (PVDF) has long been regarded as an ideal piezoelectric plastic because it exhibits a large piezoelectric response and a high thermal stability. However, the realization of piezoelectric PVDF elements has proven to be problematic, amongst others, due to the lack of industrially-scalable methods to process PVDF into the appropriate polar crystalline forms. Here, we show that fully piezoelectric PVDF films can be produced via a single-step process that exploits the fac...
-
Ionic relaxation in PEO/PVDF-HFP-LiClO4 blend polymer electrolytes: dependence on salt concentration
Das, S.; Ghosh, A.
2016-06-01
In this paper, we have studied the effect of LiClO4 salt concentration on the ionic conduction and relaxation in poly ethylene oxide (PEO) and poly (vinylidene fluoride hexafluoropropylene) (PVDF-HFP) blend polymer electrolytes, in which the molar ratio of ethylene oxide segments to lithium ions (R = EO: Li) has been varied between 3 and 35. We have observed two phases in the samples containing low salt concentrations (R > 9) and single phase in the samples containing high salt concentrations (R ⩽ 9). The scanning electron microscopic images indicate that there exists no phase separation in the blend polymer electrolytes. The temperature dependence of the ionic conductivity shows two slopes corresponding to high and low temperatures and follows Arrhenius relation for the samples containing low salt concentrations (R > 9). The conductivity relaxation as well as the structural relaxation has been clearly observed at around 104 Hz and 106 Hz for these concentrations of the blended electrolytes. However, a single conductivity relaxation peak has been observed for the compositions with R ⩽ 9. The scaling of the conductivity spectra shows that the relaxation mechanism is independent of temperature, but depends on salt concentration.
-
Directory of Open Access Journals (Sweden)
Yujian Sun
2016-12-01
Full Text Available Polymer-dispersed liquid crystal (PDLC films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found that the weight ratio among acrylate monomers, thiol monomer PETMP and the polymercaptan Capcure 3-800 showed great influence on the properties of the fabricated PDLC films because of the existence of competition between thiol-acrylate reaction and acrylate monomer polymerization reaction. While adding polymercaptans curing agent Capcure 3-800 with appropriate concentration into the PDLC system, lower driven voltage and higher contrast ratio were achieved. This made the polymer network and electro-optical properties of the PDLC films easily tunable by the introduction of the thiol monomers.
-
Sun, Yujian; Zhang, Cuihong; Zhou, Le; Fang, Hua; Huang, Jianhua; Ma, Haipeng; Zhang, Yi; Yang, Jie; Zhang, Lan-Ying; Song, Ping; Gao, Yanzi; Xiao, Jiumei; Li, Fasheng; Li, Kexuan
2016-12-30
Polymer-dispersed liquid crystal (PDLC) films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found that the weight ratio among acrylate monomers, thiol monomer PETMP and the polymercaptan Capcure 3-800 showed great influence on the properties of the fabricated PDLC films because of the existence of competition between thiol-acrylate reaction and acrylate monomer polymerization reaction. While adding polymercaptans curing agent Capcure 3-800 with appropriate concentration into the PDLC system, lower driven voltage and higher contrast ratio were achieved. This made the polymer network and electro-optical properties of the PDLC films easily tunable by the introduction of the thiol monomers.
-
Study on CO2/ N2 separation: the effect of rubbery polymer coating on PVDF membrane
Zuwairi, M. Z.; Rahman, S. A.
2017-06-01
The emission of harmful gases such as carbon dioxide (CO2) via gas processing plant and daily human activities gave negative impacts to the environment and global inhabitant. Flat sheet asymmetric membranes were produced from homogenous solution of Poly(vinylideneflouride) (PVDF) via phase inversion method using N-methyl-2-pyrrolidone (NMP) as the solvent. While the poly ether b-amide (PEBAX) was dissolve by using of (70 ethanol and 30 water) as a solvent and and lithium chloride as a additives. The morphology and cross section of the produced membranes were observed by Scanning Electron Microscope (SEM). Then, the membranes were tested for chemical analysis to define the presence of PEBAX in the membrane by using Fourier Transform Infrared (FTIR) spectroscopy. The permeation performances of the membranes were evaluated in terms of permeability and selectivity of the membranes by using gas permeation test. Increasing the PEBAX content significantly increased the selectivity of the PVDF membrane to separate the CO2/N2 gases but decreased the amount of the gases that passed through the membrane.
-
Rational design of organic electro-optic materials
Dalton, L R
2003-01-01
Quantum mechanical calculations are used to optimize the molecular first hyperpolarizability of organic chromophores and statistical mechanical calculations are used to optimize the translation of molecular hyperpolarizability to macroscopic electro-optic activity (to values of greater than 100 pm V sup - sup 1 at telecommunications wavelengths). Macroscopic material architectures are implemented exploiting new concepts in nanoscale architectural engineering. Multi-chromophore-containing dendrimers and dendronized polymers not only permit optimization of electro-optic activity but also of auxiliary properties including optical loss (both absorption and scattering), thermal and photochemical stability and processability. New reactive ion etching and photolithographic techniques permit the fabrication of three-dimensional optical circuitry and the integration of that circuitry with semiconductor very-large-scale integration electronics and silica fibre optics. Electro-optic devices have been fabricated exploiti...
-
Electro-active bio-films: formation, characterization and mechanisms
International Nuclear Information System (INIS)
Parot, Sandrine
2007-01-01
Some bacteria, which are able to exchange electrons with a conductive material without mediator form on conductive surfaces electro-active bio-films. This bacterial property has been recently discovered (2001). Objectives of this work are to develop electro-active bio-films in various natural environments from indigenous flora, then through complementary electrochemical techniques (chrono-amperometry and cyclic voltammetry), to evaluate electro-activity of isolates coming from so-formed bio-films and to characterize mechanisms of electron transfer between bacteria and materials. First, electro-active bio-films have been developed under chrono-amperometry in garden compost and in water coming from Guyana mangrove. These bio-films were respectively able to use an electrode as electron acceptor (oxidation) or as electron donor (reduction). In compost, results obtained in chrono-amperometry and cyclic voltammetry suggest a two-step electron transfer: slow substrate consumption, then rapid electron transfer between bacteria and the electrode. Thereafter, the ability to reduce oxygen was demonstrated with cyclic voltammetry for facultative aerobic isolates from compost bio-films (Enterobacter spp. and Pseudomonas spp.) and for aerobic isolates obtained from marine electro-active bio-films (Roseobacter spp. in majority). Finally, bio-films inducing current increase in chrono-amperometry were developed in bioreactor with synthetic medium from a pure culture of isolates. Hence, for the first time, electro-activity of several anaerobic strains of Geobacter bremensis isolated from compost bio-films was highlighted. (author) [fr
-
Electrically aligned cellulose film for electro-active paper and its piezoelectricity
International Nuclear Information System (INIS)
Yun, Sungryul; Jang, Sangdong; Yun, Gyu-Young; Kim, Jaehwan
2009-01-01
Electrically aligned regenerated cellulose films were fabricated and the effect of applied electric field was investigated for the piezoelectricity of electro-active paper (EAPap). The EAPap was fabricated by coating gold electrodes on both sides of regenerated cellulose film. The cellulose film was prepared by dissolving cotton pulp in LiCl/N,N-dimethylacetamide solution followed by a cellulose chain regeneration process. During the regeneration process an external electric field was applied in the direction of mechanical stretching. Alignment of cellulose fiber chains was investigated as a function of applied electric field. The material characteristics of the cellulose films were analyzed by using an x-ray diffractometer, a field emission scanning electron microscope and a high voltage electron microscope. The application of external electric fields was found to induce formation of nanofibers in the cellulose, resulting in an increase in the crystallinity index (CI) values. It was also found that samples with higher CI values showed higher in-plane piezoelectric constant, d 31 , values. The piezoelectricity of the current EAPap films was measured to be equivalent or better than that of ordinary PVDF films. Therefore, an external electric field applied to a cellulose film along with a mechanical stretching during the regeneration process can enhance the piezoelectricity. (technical note)
-
Directory of Open Access Journals (Sweden)
Endah R. Dyartanti
2018-07-01
Full Text Available In this paper, we present the characteristics and performance of polymer electrolyte membranes (PEMs based on poly(vinylidene fluoride (PVDF. The membranes were prepared via a phase-inversion method (non-solvent-induced phase separation (NIPS. As separators for lithium battery systems, additive modified montmorillonite (MMT nano-clay served as a filler and poly(vinylpyrrolidone (PVP was used as a pore-forming agent. The membranes modified with an additive (8 wt % nano-clay and 7 wt % PVP showed an increased porosity (87% and an uptake of a large amount of electrolyte (801.69%, which generated a high level of ionic conductivity (5.61 mS cm−1 at room temperature. A graphite/PEMs/LiFePO4 coin cell CR2032 showed excellent stability in cycling performance (average discharge capacity 127 mA h g−1. Based on these results, PEMs are promising materials to be used in Polymer Electrolyte Membranes in lithium-ion batteries.
-
International Nuclear Information System (INIS)
Li, Hongbin; Shi, Wenying; Zhang, Yufeng; Zhou, Rong; Zhang, Haixia
2015-01-01
Graphical abstract: - Highlights: • High modulus PPTA molecules were introduced into PVDF membrane matrix through in situ polycondensation. • Membrane surface hydrophilicity and mechanical strength were improved. • An enhanced antifouling property was obtained when blend membrane was applied in the MBR in the treatment of landfill leachate. • Blend membrane also showed a relatively high removal rate of chemical oxygen demand (COD) and chrom. - Abstract: High modulus poly(p-phenylene terephtalamide) (PPTA) reinforced composites are of great scientific interests. But the thermodynamic difference makes the polymer pairs incompatible and endows the composites with inferior physical-chemical properties. In this study, hydrophilic poly(vinylidene fluoride) (PVDF)/poly(p-phenylene terephtalamide) (PPTA) blend membrane with improved hydrophilicity and mechanical strength was prepared through in situ polycondensation of p-phenylene diamine (PPD) and terephthaloyl chloride (TPC) in PVDF solution and subsequent immersion precipitation phase inversion process. The effects of PPTA concentration in polymer dopes on membrane formation process, structure, morphology and performance were systematically investigated. The results showed that thermodynamically, PPTA acted as a demixing enhancer which accelerated the phase inversion process. Dynamically, liquid-liquid phase separation was still in control of membrane formation process especially in the later period, whereas the addition of PPTA mainly promoted the early emergence of the liquid-liquid demixing. The surface hydrophilicity, ant-fouling properties and mechanical strength were significantly improved when PPTA content was 17 wt%. When PPTA content increased to 26 wt%, membrane bursting pressure increased to nearly 0.6 MPa which was 1.5 times higher than that of PVDF membrane. The resultant PVDF/PPTA blend membrane exhibited an improved antifouling property than that of PVDF membrane when applied in the MBR in the
-
Energy Technology Data Exchange (ETDEWEB)
Li, Hongbin, E-mail: qinyu1105@126.com [School of Textiles Engineering, Henan Institute of Engineering, Zhengzhou, 450007 (China); Shi, Wenying [School of Textiles Engineering, Henan Institute of Engineering, Zhengzhou, 450007 (China); Zhang, Yufeng [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300387 (China); Zhou, Rong; Zhang, Haixia [School of Textiles Engineering, Henan Institute of Engineering, Zhengzhou, 450007 (China)
2015-08-15
Graphical abstract: - Highlights: • High modulus PPTA molecules were introduced into PVDF membrane matrix through in situ polycondensation. • Membrane surface hydrophilicity and mechanical strength were improved. • An enhanced antifouling property was obtained when blend membrane was applied in the MBR in the treatment of landfill leachate. • Blend membrane also showed a relatively high removal rate of chemical oxygen demand (COD) and chrom. - Abstract: High modulus poly(p-phenylene terephtalamide) (PPTA) reinforced composites are of great scientific interests. But the thermodynamic difference makes the polymer pairs incompatible and endows the composites with inferior physical-chemical properties. In this study, hydrophilic poly(vinylidene fluoride) (PVDF)/poly(p-phenylene terephtalamide) (PPTA) blend membrane with improved hydrophilicity and mechanical strength was prepared through in situ polycondensation of p-phenylene diamine (PPD) and terephthaloyl chloride (TPC) in PVDF solution and subsequent immersion precipitation phase inversion process. The effects of PPTA concentration in polymer dopes on membrane formation process, structure, morphology and performance were systematically investigated. The results showed that thermodynamically, PPTA acted as a demixing enhancer which accelerated the phase inversion process. Dynamically, liquid-liquid phase separation was still in control of membrane formation process especially in the later period, whereas the addition of PPTA mainly promoted the early emergence of the liquid-liquid demixing. The surface hydrophilicity, ant-fouling properties and mechanical strength were significantly improved when PPTA content was 17 wt%. When PPTA content increased to 26 wt%, membrane bursting pressure increased to nearly 0.6 MPa which was 1.5 times higher than that of PVDF membrane. The resultant PVDF/PPTA blend membrane exhibited an improved antifouling property than that of PVDF membrane when applied in the MBR in the
-
Kaneto, Keiichi; Yoshino, Katsumi; Inuishi, Yoshio
1983-07-01
Detailed characteristics of electro-optic elements (color switching and memory) utilizing the spectral change of conducting polymers by electrochemical doping and undoping are studied. The response time of color switching, for example, red≤ftrightarrowblue in polythiophene film in the electrolyte of LiBF4/acetonitrile is 30˜100 msec under the applied voltages of -2.0{≤ftrightarrow}+4.0 V vs. Li plate. More than 103 cycles of color switch are observed quite reproducibly. Three color states of yellow green, dark brown and blue are demonstrated for polypyrrole film.
-
Bismuth Oxysulfide and Its Polymer Nanocomposites for Efficient Purification
Directory of Open Access Journals (Sweden)
Yidong Luo
2018-03-01
Full Text Available The danger of toxic organic pollutants in both aquatic and air environments calls for high-efficiency purification material. Herein, layered bismuth copper oxychalcogenides, BiCuSO, nanosheets of high photocatalytic activity were introduced to the PVDF (Polyvinylidene Fluoride. The fibrous membranes provide an easy, efficient, and recyclable way to purify organic pollutant. The physical and photophysical properties of the BiCuSO and its polymer composite were characterized by scanning electron microscopy (SEM, X-ray diffraction (XRD, ultraviolet-visible diffuse reflection spectroscopy (DRS, X-ray photoelectron spectroscopy (XPS, electron spin resonance (EPR. Photocatalysis of Congo Red reveals that the BiCuSO/PVDF shows a superior photocatalytic activity of a 55% degradation rate in 70 min at visible light. The high photocatalytic activity is attributed to the exposed active {101} facets and the triple vacant associates V B i ‴ V O • • V B i ‴ . By engineering the intrinsic defects on the surface of bismuth oxysulfide, high solar-driven photocatalytic activity can be approached. The successful fabrication of the bismuth oxysulfide and its polymer nanocomposites provides an easy and general approach for high-performance purification materials for various applications.
-
Biswas, Md Rokon Ud Dowla; Oh, Won-Chun
2018-06-01
BiVO4-GO-PVDF (PVDF = Polyvinylidene Difluoride) photocatalyst is successfully synthesized by ultrasonication method and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques. Morphology of BiVO4-GO-PVDF looks like a human embryo embedded inside an amniotic sac. Photocatalytic performance of BiVO4-GO-PVDF for decolorization of methylene blue is investigated. BiVO4-GO-PVDF system reveals enhanced photocatalytic activity degradation of methylene blue (MB), Rhodamine B (RhB) & Safranin-O (SO) in water under visible light irradiation as compared to the pure BiVO4 catalyst, BiVO4 & PTFE decorated on the graphene sheet. The experimental result reveals that the covering of graphene sheets in this composite catalyst enhances photocatalytic performance under visible light. This enhanced activity is mainly attributed to effective quenching of the photogenerated electron-hole pairs confirmed by photoluminescence spectra. Trapping experiments of radicals and holes were conducted to detect reactive species generated in the photocatalytic system, experimental results revealed that direct hole oxidation reaction is obviously dominant during photocatalytic reactions on the BiVO4-GO-PVDF system.
-
Superhydrophobicity and regeneration of PVDF/SiO2 composite films
Liu, Tao; Li, Xianfeng; Wang, Daohui; Huang, Qinglin; Liu, Zhen; Li, Nana; Xiao, Changfa
2017-02-01
Superhydrophobicity of polymers is easily destroyed by careless touching due to the softness of microstructures. In this study, based on a well-constructed polyvinylidene fluoride (PVDF) surface, a novel superhydrophobic PVDF/SiO2 composite film was fabricated by adding hydrophobic SiO2 nanoparticle and solvent into a coagulation bath. The water contact angle of the composite film reached 162.3° and the sliding angle was as low as 1.5°. More importantly, the composite film could be regenerated only through immersing the composite film in the designed regeneration agent. The composition of the designed regeneration agent ensured that SiO2 nanoparticles were firmly adhered on the film surface even under the ultrasonic cleaning. Hence, the superhydrophobicity and self-cleaing property could be regenerated and maintained effectively, and moreover, these propeties could resist a proper pressure. In addition, after many rubbing-regenerating cycles, the regeneration method was still valid.
-
Nanodiamond particles/PVDF nanocomposite flexible films: thermal, mechanical and physical properties
Jaleh, Babak; Sodagar, Shima; Momeni, Amir; Jabbari, Ameneh
2016-08-01
Recently, polymer nanocomposites reinforced with nanoparticles have attracted a lot of attention due to their unique physical and mechanical properties. In this work, poly (vinylidene fluoride)/nanodiamond particles nanocomposite films were prepared by solution casting method with various nanodiamond particles contents. The samples were investigated by Fourier transform infrared spectroscopy and x-ray diffraction technique. The results revealed an obvious α to β-phase transformation compared to pure PVDF. The most (or the maximum) phase transformation from α to β-phase (>90%) was found for nanocomposite film with 8% wt nanodiamond particles. Scanning electron micrographs showed considerable decrease in the size of spherulitic crystal structure of PVDF with adding nanoparticles. The photoluminescence property of nanocomposite films was investigated by photoluminescence spectroscopy and the optical band gap value was calculated from the UV-visible absorption spectra. The results showed that after the incorporation of nanoparticles into PVDF, the value of optical band gap decreased. Thermal stability of samples was studied by thermogravimetric analysis. Due to an increase in the electroactive phase (β) percentage by adding nanoparticles, the resistance of samples to thermal degradation improved. The mechanical properties of samples were investigated by tensile test and hardness measurements. The elastic modulus and hardness of samples were enhanced by adding nanodiamond particles and elongation to fracture decreased.
-
Scalable electro-photonic integration concept based on polymer waveguides
Bosman, E.; Van Steenberge, G.; Boersma, A.; Wiegersma, S.; Harmsma, P.; Karppinen, M.; Korhonen, T.; Offrein, B. J.; Dangel, R.; Daly, A.; Ortsiefer, M.; Justice, J.; Corbett, B.; Dorrestein, S.; Duis, J.
2016-03-01
A novel method for fabricating a single mode optical interconnection platform is presented. The method comprises the miniaturized assembly of optoelectronic single dies, the scalable fabrication of polymer single mode waveguides and the coupling to glass fiber arrays providing the I/O's. The low cost approach for the polymer waveguide fabrication is based on the nano-imprinting of a spin-coated waveguide core layer. The assembly of VCSELs and photodiodes is performed before waveguide layers are applied. By embedding these components in deep reactive ion etched pockets in the silicon substrate, the planarity of the substrate for subsequent layer processing is guaranteed and the thermal path of chip-to-substrate is minimized. Optical coupling of the embedded devices to the nano-imprinted waveguides is performed by laser ablating 45 degree trenches which act as optical mirror for 90 degree deviation of the light from VCSEL to waveguide. Laser ablation is also implemented for removing parts of the polymer stack in order to mount a custom fabricated connector containing glass fiber arrays. A demonstration device was built to show the proof of principle of the novel fabrication, packaging and optical coupling principles as described above, combined with a set of sub-demonstrators showing the functionality of the different techniques separately. The paper represents a significant part of the electro-photonic integration accomplishments in the European 7th Framework project "Firefly" and not only discusses the development of the different assembly processes described above, but the efforts on the complete integration of all process approaches into the single device demonstrator.
-
Study of pyroelectric activity of PZT/PVDF-HFP composite
Directory of Open Access Journals (Sweden)
Luiz Francisco Malmonge
2003-12-01
Full Text Available Flexible, free-standing piezo and pyroelectric composite with 0 to 3 connectivity was made up from Lead Zirconate Titanate (PZT powder and poly(vinylidene fluoride-hexafluoropropylene (PVDF-HFP copolymer. The pyroelectric and the piezoelectric longitudinal (d33 coefficients were measured. A 50/50 vol.% PZT/PVDF-HFP composite resulted in piezo and pyroelectric coefficients of d33 = 25.0 pC/N and p = 4.5 × 10-4 C/m²K at 70 °C, respectively. Analysis of the complex permittivity in a wide range of frequency was carried out indicating lower permittivity of the composite in comparison with a permittivity of the PZT ceramic. The low value of the permittivity gives a high pyroelectric figure of merit indicating that this material can be used to build a temperature sensor in spite of the lower pyroelectric coefficient compared with PZT.
-
Hinojosa, A.; Shive, C.; Sharma, Suresh
2010-03-01
We have studied the electro-optical properties of a polymer-dispersed liquid crystal (PDLC) as functions of relative concentrations of gold nanoparticles. PDLC samples were synthesized between indium-tin-oxide (ITO) coated glass slides, separated by SiO2 spacers, by using liquid crystal E44, a monofunctional acrylic oligomer (CN135), and a tetrafunctional crosslinker (SR295). A UV photoinitiator (SR1124) was used to facilitate the curing of the monomer exposed to UV radiation from a Hg spectral lamp. A He-Ne laser was used to measure optical transmission through the PDLC as a function of applied ac electric field (1 kHz). The PDLC without gold nanoparticles shows the expected behavior; transmission through the PDLC increases from a minimum (opaque) to a maximum (transparent) with increasing electric field. The electro-optical behavior of the PDLC is altered significantly (e. g., relatively low switching field) upon addition of relatively low concentrations of gold nanoparticles into the starting PDLC syrup. We present electro-optical data as functions of gold nanoparticle concentration and discuss possible mechanism to understand our results.
-
Directory of Open Access Journals (Sweden)
Yeong-Soon Gal
2008-01-01
Full Text Available The electro-optical and electrochemical properties of poly(diethyl dipropargylmalonate were measured and discussed. Poly(diethyl dipropargylmalonate prepared by (NBDPdCl2 catalyst was used for study. The chemical structure of poly(diethyl dipropargylmalonate was characterized by such instrumental methods as NMR (1H-, 13C-, IR, and UV-visible spectroscopies to have the conjugated cyclopolymer backbone system. The microstructure analysis of polymer revealed that this polymer have the six-membered ring moieties majorly. The photoluminescence peak of polymer was observed at 543 nm, which is corresponded to the photon energy of 2.51 eV. The cyclovoltamograms of the polymer exhibited the irreversible electrochemical behaviors between the doping and undoping peaks. It was found that the kinetics of the redox process of this conjugated cyclopolymer might be controlled by the diffusion-control process from the experiment of the oxidation current density of polymer versus the scan rate.
-
Electro active polymers : novel bio-electrodes and implants for urinary continence
Energy Technology Data Exchange (ETDEWEB)
Rajagopalan, S.; Sawan, M.; Savadogo, O. [Ecole Polytechnique, Montreal, PQ (Canada). Laboratoire de nouveaux materiaux pour les systemes electrochimiques et energetiques
2006-07-01
This paper presented a technical solution to spinal cord injuries that result in urinary bladder dysfunction. It involves miniaturized implants based on polypyrrole, an electroactive polymer, as smart drug-eluting electrodes for neural stimulation to restore bladder function. The nerve-electrode interface is the most vulnerable point in the design and operation of neuro-electronic implants. The main disadvantages are decreased impedance and protein build-up at the stimulation site due to an inflammatory reaction. Polypyrrole is a naturally conducting polymer having both electron-conducting properties as well as actuating properties, rendering it suitable as a drug-eluting electrode for a neurostimulator. Polypyrrole electrochemically coated on platinum increases biocompatibility and reduces electric impedance by increasing the surface area of the electrode. When electrically stimulated, polypyrrole also serves as a matrix to release a negatively-charged anti-inflammatory drug fosfosal. This technology may prove useful in reconstructing a severely damaged bladder through electroactive biomaterials. Polyelectrolyte gels, such as poly(sodium) acrylate, reversibly contract and relax when activated electrically or under the influx of divalent ions. These artificial muscles can be connected to a polypyrrole strain sensor to alert the microcontroller to activate the sphincter muscle, thereby creating an artificial bladder.
-
Flexible PVDF ferroelectric capacitive temperature sensor
Khan, Naveed
2015-08-02
In this paper, a capacitive temperature sensor based on polyvinylidene fluoride (PVDF) capacitor is explored. The PVDF capacitor is characterized below its Curie temperature. The capacitance of the PVDF capacitor changes vs temperature with a sensitivity of 16pF/°C. The linearity measurement of the capacitance-temperature relation shows less than 0.7°C error from a best fit straight line. An LC oscillator based temperature sensor is demonstrated based on this capacitor.
-
Advances in ferroelectric polymers for shock compression sensors
International Nuclear Information System (INIS)
Bauer, F.; Moulard, H.; Samara, G.
1997-01-01
Our studies of the shock compression response of PVDF polymer are continuing in order to understand the physical properties under shock loading and to develop high fidelity, reproducible, time-resolved dynamic stress gauges. New PVDF technology, new electrode configurations and piezoelectric analysis have resulted in enhanced precision gauges. Our new standard gauges have a precision of better than 1% in electric charge release under shock up to 15 GPa. The piezoelectric response of shock compressed PVDF gauges 1 mm 2 in active area has been studied and yielded well-behaved reproducible data up to 20 GPa. Analysis of the response of these gauges in the open-quotes thin mode regimeclose quotes using a Lagrangian hydrocode will be presented. P(VDF-TrFE) copolymers exhibit unique piezoelectric properties over a wide range of temperature depending on the composition. Their properties and phase transitions are being investigated. Emphasis of the presentation will be on key results and implications
-
International Nuclear Information System (INIS)
Friia, Manel; Legros, Veronique; Tortajada, Jeanine; Buchmann, William
2012-01-01
Desorption Electro-Spray Ionization (DESI) - Orbitrap Mass Spectrometry (MS) was evaluated as a new tool for the characterization of various industrial synthetic polymers (poly(ethylene glycol), poly(propylene glycol), poly(methylmethacrylate), poly(dimethylsiloxane)) and copolymers, with masses ranging from 500 g.mol -1 up to more than 20000 g.mol -1 . Satisfying results in terms of signal stability and sensitivity were obtained from hydrophobic surfaces (HTC Prosolia) with a mixture water/methanol (10/90) as spray solvent in the presence of sodium salt. Taking into account the formation of multiplied charged species by DESI-MS, a strategy based on the use of a deconvolution software followed by the automatic assignment of the ions was described allowing the rapid determination of Mn, Mw and PDI values. DESI-Orbitrap MS results were compared to those obtained from matrix-assisted laser desorption/ionization- time-of-flight MS and gel permeation chromatography. An application of DESI-Orbitrap MS for the detection and identification of polymers directly from cosmetics was described. (authors)
-
Directory of Open Access Journals (Sweden)
Cao Vu Dung
2016-04-01
Full Text Available Polyvinylidene Flouride (PVDF is a film-type polymer that has been used as sensors and actuators in various applications due to its mechanical toughness, flexibility, and low density. A PVDF sensor typically covers an area of the host structure over which mechanical stress/strain is averaged and converted to electrical energy. This study investigates the fundamental “stress-averaging” mechanism for dynamic strain sensing in the in-plane mode. A numerical simulation was conducted to simulate the “stress-averaging” mechanism of a PVDF sensor attached on a cantilever beam subjected to an impact loading, taking into account the contribution of piezoelectricity, the cantilever beam’s modal properties, and electronic signal conditioning. Impact tests and FEM analysis were also carried out to verify the numerical simulation results. The results of impact tests indicate the excellent capability of the attached PVDF sensor in capturing the fundamental natural frequencies of the cantilever beam. There is a good agreement between the PVDF sensor’s output voltage predicted by the numerical simulation and that obtained in the impact tests. Parametric studies were conducted to investigate the effects of sensor size and sensor position and it is shown that a larger sensor tends to generate higher output voltage than a smaller one at the same location. However, the effect of sensor location seems to be more significant for larger sensors due to the cancelling problem. Overall, PVDF sensors exhibit excellent sensing capability for in-plane dynamic strain induced by impact loading.
-
Wang, Xushan; Wang, Zihong; Wang, Zhe; Cao, Yu; Meng, Jianqiang
2017-10-01
Antifouling PVDF membranes were prepared by grafting hyperbranched polyols on the membrane surface via a three-step modification method. The membrane was first prepared by alkaline treatment to introduce alkenyl groups, then chemically immobilizing hyperbranched poly(ethyleneimine) (HPEI) on membrane surface through Michael reaction followed by ring opening reaction of the glycidol with amine groups. Chemical compositions, surface morphology and physicochemical properties of the original and modified membranes were characterized via attenuated total refection-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), water contact angle (WCA) and zeta potential measurements. The antifouling property of the modified membrane was assessed by the static bovine serum albumin (BSA) and lysozyme (LZM) adsorption as well as cross-flow filtration of BSA aqueous solution. The results explicate that surface modification using hyperbranched polymers can alter membrane chemistry and morphology significantly. In contrast to the original PVDF membrane, the modified membrane shows superhydrophilic property and relatively high capability to resist nonspecific protein adsorption. Three HPEIs were used for modification and the obtained PVDFA-g-PG60,000 membrane has a static BSA protein adsorption of 45 μg/cm2 and shows the highest protein resistance. However, the PVDF-g-PG membrane is positively charged due to the unreacted amine groups. As a result, the PVDF-g-PG membranes also show high flux decline during the filtration of BSA aqueous solution due to the electrostatic interaction. In spite of that, the PVDF-g-PG membranes still maintain high flux recovery ratio and good washing properties.
-
Energy Technology Data Exchange (ETDEWEB)
Nasef, Mohamed Mahmoud [Business and Advanced Technology Centre, Universiti Teknologi Malaysia, Jalan Semarak, 54100 Kuala Lumpur (Malaysia); Suppiah, Raja Rajeswary [Chemical Engineering Program, Universiti Teknologi Petronas, Bandar Seri Iskandar, 37150 Tronoh, Perak (Malaysia); Dahlan, Khairul Zaman Mohd [Malaysian Institute for Nuclear Technology Research, Bangi, 43000 Kajang (Malaysia)
2004-07-30
Polymer electrolyte membranes with different degrees of grafting were prepared by radiation-induced graft copolymerization of styrene monomer onto poly(vinylidene fluoride) (PVDF) films and subsequent chemical activation with liquid electrolyte consisting of lithium hexafluorophosphate (LiPF{sub 6}) in a mixture of ethylene carbonate/diethylene carbonate (EC/DEC). The chemical changes in the PVDF films after styrene grafting and subsequent chemical activation were monitored by FTIR spectroscopic analysis and the crystallinity was evaluated using differential scanning calorimetric (DSC) analysis. The swelling in electrolyte solution (electrolyte uptake) and the ionic conductivity of the membranes were determined at various degrees of grafting. The conductivity of the membranes was found to increase with the increase in the degree of grafting and reached a magnitude of 10{sup -3} S/cm at a degree of grafting of 50%. The results of this work suggest that radiation-induced graft polymerization provides an alternative method to substitute blending in preparation of polymer electrolyte membranes for application in lithium batteries.
-
Energy Technology Data Exchange (ETDEWEB)
Ouskova, Elena; Sio, Luciano De, E-mail: luciano@beamco.com; Vergara, Rafael; Tabiryan, Nelson [Beam Engineering for Advanced Measurements Company, Winter Park, Florida 32789 (United States); White, Timothy J.; Bunning, Timothy J. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433-7707 (United States)
2014-12-08
A different generation of polymer-dispersed liquid crystals (PDLCs) based on a liquid crystalline polymer host is reported wherein the fluid behavior of the reactive mesogenic monomer is an enabler to concentration windows (liquid crystal polymer/liquid crystal) (and subsequent morphologies) not previously explored. These liquid crystal (LC) polymer/LC composites, LCPDLCs, exhibit excellent optical and electro-optical properties with negligible scattering losses in both the ON and OFF states. These systems thus have application in systems where fast phase modulation of optical signal instead of amplitude control is needed. Polarized optical microscopy and high resolution scanning electron microscopy confirm a bicontinuous morphology composed of aligned LC polymer coexisting with a phase separated LC fluid. Operating voltages, switching times, and spectra of LCPDLCs compare favourably to conventional PDLC films. The LCPDLCs exhibit a low switching voltage (4–5 V/μm), symmetric and submillisecond (200 μs) on/off response times, and high transmission in both the as formed and switched state in a phase modulation geometry.
-
International Nuclear Information System (INIS)
Magerramov, A.M; Rustamova, D.F.
2010-01-01
Full text : Fluoropolymers are known, as one of the most promising polymers of electro active materials and they are very sensitive to radiation, with the prone to decomposition processes. One way to stabilize the piezoelectric properties of Fluor polymers may be their radiation modification of gamma-irradiation. The aim of the present work is to study the effect of gamma-irradiation on the piezoelectric properties of the copolymer of vinylidene fluoride with tetrafluoroethylene-P (VDF-TeFE). The polarization produced in the optimal range for the electric field. Irradiation of the films performed at the facility Rahm-gamma-30 both before and after polarization. For gamma irradiation, apparently as a result of conformational transitions alpha and beta is a change of relations of ferroelectric and par electric phases in upward of crystallinity, i e an increase in the ferroelectric polymer. It was discussed possible mechanisms of changes in the dielectric, piezoelectric and ferroelectric properties (hysteresis loops, the values of the coercive field) with a residual polarization of Fluor polymers when exposed to gamma-irradiation.
-
The Application of PVDF in Converter Cooling Pipeline
Geng, Man; Lu, Zhimin
2017-11-01
The structure, mechanical property, thermodynamics property, electrical aspects, radiation property and chemical property were introduced, and PVDF could satisfy the requirement of converter cooling pipe. PVDF department and pipe of distribution pipeline of converter cooling system in Debao HVDC project are used to introduce the molding process of PVDF.
-
Chen, Fengtao; Shi, Xingxing; Chen, Xiaobing; Chen, Wenxing
2018-01-01
A facile strategy to improve the hydrophilicity and the antifouling properties of poly(vinylidene fluoride) (PVDF) membranes, a functional monomer of 4-methacrylamidobenzenesulfonic acid (MABS), was designed and synthesized through the amidation reaction between 2-methylacryloyl chloride and sulfanilic acid. Utilizing PVDF and the obtained MABS as reaction monomers, a novel amphiphilic copolymer was firstly prepared by radical polymerization method. The resulting PVDF-g-PMABS was used as a hydrophilic additive in the fabrication of PVDF porous membranes via immersion precipitation process. The surface chemical compositions and structure morphologies of as-prepared blend membranes (PVDF-g-PMABS/PVDF) were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. Contact angle measurement and cross-flow permeation test were employed to evaluate the hydrophilicity and antifouling properties of the membranes. It was found that the blend membrane with 4 wt.% PVDF-g-PMABS exhibited a noticeable pure water flux (136.34 L m-2 h-1) and a remarkable flux recovery ratio (FRR) of 98.60% in comparison with the pristine PVDF membrane (63.37 L m-2 h-1 and 38.67%, respectively). The enhanced performance was attributed to the synergetic effects of the strong hydrogen bonding force and the electrostatic repulsion of sulfonic groups against the protein foulants.
-
International Nuclear Information System (INIS)
Nur Izzah Md Fadilah; Abdul Rahman Hassan
2016-01-01
The role of surfactants in the formation of active Poly(vinylidene fluoride) (PVDF) ultrafiltration (AUF) membranes was studied. The effect combination of surfactants that are Sodium dodecyl sulfate (SDS)/ Tween 80 and Tween 80/ Triton X-100 formulations on performance and morphological structures were investigated for the first time. The influence of surfactants blends on the membrane pores was also examined. Experimental data showed that combination of Tween 80/ Triton X-100 give the highest BSA permeation flux with a value of 285.51 Lm -2 h -1 . With combination of SDS/ Tween 80, the AUF membrane showed the highest protein rejection up to 93 % and 79 % for Bovine Serum Albumin (BSA) and Egg Albumin (EA), respectively. Moreover, membranes characterization demonstrated that the addition of SDS/ Tween 80 and Tween 80/ Triton X-100 were found to affect the performance, surface morphologies and membrane pores of AUF PVDF membranes. (author)
-
Directory of Open Access Journals (Sweden)
Giovanni De Filpo
2018-06-01
Full Text Available The chemical binding of photocatalytic materials, such as TiO2 and ZnO nanoparticles, onto porous polymer membranes requires a series of chemical reactions and long purification processes, which often result in small amounts of trapped nanoparticles with reduced photocatalytic activity. In this work, a chemical vapor deposition technique was investigated in order to allow the nucleation and growth of ZnO and TiO2 nanoparticles onto polyvinylidene difluoride (PVDF porous membranes for application in advanced oxidation processes. The thickness of obtained surface coatings by sputtered nanoparticles was found to depend on process conditions. The photocatalytic efficiency of sputtered membranes was tested against both a model drug and a model organic pollutant in a small continuous flow reactor.
-
Ab initio studies of polarization and piezoelectricity in vinylidene fluoride and BN-based polymers.
Nakhmanson, S M; Nardelli, M Buongiorno; Bernholc, J
2004-03-19
Highly piezoelectric and pyroelectric phases of boron-nitrogen-based polymers have been designed from first principles. They offer excellent electrical and structural properties, with up to 100% improvement in the piezoelectic response and an enhanced thermal stability with respect to polyvinylidene fluoride (PVDF). Since methods for their synthesis are readily available, these polymers are extremely promising for numerous technological applications, rivaling the properties of ferroelectric ceramics and superseding PVDF-based materials in high-performance devices.
-
Ceramic-polymer nanocomposites with increased dielectric permittivity and low dielectric loss
International Nuclear Information System (INIS)
Bhardwaj, Sumit; Paul, Joginder; Raina, K. K.; Thakur, N. S.; Kumar, Ravi
2014-01-01
The use of lead free materials in device fabrication is very essential from environmental point of view. We have synthesized the lead free ferroelectric polymer nanocomposite films with increased dielectric properties. Lead free bismuth titanate has been used as active ceramic nanofillers having crystallite size 24nm and PVDF as the polymer matrix. Ferroelectric β-phase of the polymer composite films was confirmed by X-ray diffraction pattern. Mapping data confirms the homogeneous dispersion of ceramic particles into the polymer matrix. Frequency dependent dielectric constant increases up to 43.4 at 100Hz, whereas dielectric loss decreases with 7 wt% bismuth titanate loading. This high dielectric constant lead free ferroelectric polymer films can be used for energy density applications
-
Development of Polyvinylidene fluoride (PVDF)-ZIF-8 Membrane for Wastewater Treatment
Ibrahim, N. A.; Wirzal, M. D. H.; Nordin, N. A. H.; Halim, N. S. Abd
2018-04-01
Nowadays, the water shortage problem following the urbanization and increasing pollution of natural water source have increased the awareness to treat wastewater. Membrane filtration is often used in wastewater treatment plants to filter out more residual activated sludge from aeration process in the secondary stage. However, fouling is the main concern due to the fact it can happen to any membrane application. Antifouling properties in membrane can be improved by blending membranes with fillers or additives to make them more hydrophilic. This study aims to improve the antifouling properties in polyvinylidene fluoride (PVDF) membranes while optimizing the loading of Zeolitic imidazolate framework-8 (ZIF-8) fillers; at different loading (2.0 wt. %, 4.0 wt. %, 6.0 wt. %, 8.0 wt. % and 10.0 wt. %). Manual hand-casting of flat sheet membrane was done and the fabricated membranes were tested for their filterability against pure water and domestic wastewater. Both permeability tests showed that PVDF with 8% ZIF-8 membrane was the most permeable with a pure water and wastewater permeability of 150 L/m2.h.bar and 94 L/m2.h.bar, respectively. The pure water permeability of PVDF with 8% ZIF-8 membrane increases for about 130% compared to the pure PVDF membrane. The turbidity test of the initial feed and final permeate of wastewater, PVDF with 8% ZIF-8 membrane also gave out the highest reduction rate at 87%, which is 36% higher than that of pure PVDF membrane. It can be deduced that 8% of ZIF-8 is the ideal loading to PVDF in improving its antifouling properties to be used in domestic wastewater treatment.
-
Styrene-Based Copolymer for Polymer Membrane Modifications
Harsha Srivastava; Harshad Lade; Diby Paul; G. Arthanareeswaran; Ji Hyang Kweon
2016-01-01
Poly(vinylidene fluoride) (PVDF) was modified with a styrene-based copolymer. The crystalline behavior, phase, thermal stability, and surface morphology of the modified membranes were analyzed. The membrane surface roughness showed a strong dependence on the styrene-acrylonitrile content and was reduced to 34% for a PVDF/styrene-acrylonitrile blend membrane with a 40/60 ratio. The thermal and crystalline behavior confirmed the blend miscibility of both polymers. It was observed in X-ray diffr...
-
Complex Surface Concentration Gradients by Stenciled "Electro Click Chemistry"
DEFF Research Database (Denmark)
Hansen, Thomas Steen; Lind, Johan Ulrik; Daugaard, Anders Egede
2010-01-01
Complex one- or two-dimensional concentration gradients of alkynated molecules are produced on azidized conducting polymer substrates by stenciled "electro click chemistry". The latter describes the local electrochemical generation of catalytically active Cu(I) required to complete a "click...... reaction" between alkynes and azides at room temperature. A stencil on the counter electrode defines the shape and multiplicity of the gradient(s) on the conducting polymer substrate, while the specific reaction conditions control gradient steepness and the maximum concentration deposited. Biologically...
-
Directory of Open Access Journals (Sweden)
Nita Kusumawati
2018-05-01
Full Text Available Asymmetric polysulfone (PSf membrane is prepared using phase inversion method and blending with polyvinylidene fluoride (PVDF on the gauze solid support. Casting solution composition optimization has been done to get PSf/PVDF membrane with best characteristics and permeability. The result shows that blending on PSf with PVDF polymer using phase inversion method has been very helpful in creating an asymmetric porous membrane. Increased level of PVDF in casting solution has increased the formation of asymmetry structure and corresponding flux membrane. The result from thermal test using Differential Scanning Calorimetry (DSC-Thermal Gravimetric Analysis (TGA shows the resistance of the membrane to temperature 460 °C. Membrane resistance against acid looks from undetectable changes on infrared spectra after immersion process in H2SO4 6–98 v/v%. While membrane color changes from white to brownish and black is detected after the immersion process in sodium hydroxide (NaOH 0.15–80 w/v%.
-
Evaluation of PVDF/MWCNT - ZRO{sub 2} nanocomposites for X-Rays attenuation
Energy Technology Data Exchange (ETDEWEB)
Pereira, Esther L.M.; Oliveira, Arno H., E-mail: esther_machado@outlook.com.br, E-mail: heeren@nuclear.ufmg.br [Universidade Federal de Minas Gerais (CCTN/UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Batista, Adriana S.M., E-mail: adriananuclear@yahoo.com.br [Departamento de Anatomia e Imagem (IMA), Belo Horizonte, MG (Brazil); Ribeiro, Fabíola A.S.; Santos, Adelina P.; Faria, Luiz O., E-mail: adelina@cdtn.br, E-mail: farialo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)
2017-07-01
Recently, polymer-based nanocomposites filled with zirconium oxide (ZrO{sub 2}) nanoparticles have been suggested to be used in radiology procedures as X-rays attenuators. On the other hand, multi walled carbon nanotubes (MWCNT) has been reported to have enhanced X-rays attenuation features, when compared to other materials. In this work polymer-based nanocomposites made of a poly(vinylidene fluoride) [PVDF] homopolymer co-filled with MWCNT and zirconia (ZrO{sub 2}) were prepared, in order to investigate them for radiation shielding purposes. The PVDF matrix was added to 1.3% ZrO{sub 2} and the MWCNT in three different proportions: 0.33%, 0.66% and 1% of MWCNT.The arrangement between these materials causes new properties to be introduced to the constituents due to morphological modifications or electronic interactions between them, resulting in a nanocomposite of higher properties. The radiation shielding characterization was performed by using the X-ray beam of a XRD equipment. Photons with energies of 6.5 keV, 17.5 keV and 22.1 keV, corresponding to the anodes of cobalt, molybdenum and silver respectively, were used. The results are discussed in terms of the attenuation percentage of the nanocomposites produced in relation to the energy of the exposed radiation beam and varying the thickness of the samples. A comparison with cataloged aluminum data is also performed. (author)
-
Energy Technology Data Exchange (ETDEWEB)
Chi, Q. G., E-mail: qgchi@hotmail.com, E-mail: empty-cy@l63.com [Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, Harbin University of Science and Technology, Harbin 150080 (China); State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049 (China); Gao, L. [Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, Harbin University of Science and Technology, Harbin 150080 (China); College of Electrical Engineering, Suihua University, Suihua 152061 (China); Wang, X.; Chen, Y., E-mail: qgchi@hotmail.com, E-mail: empty-cy@l63.com; Dong, J. F.; Cui, Y.; Lei, Q. Q. [Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, Harbin University of Science and Technology, Harbin 150080 (China)
2015-11-15
Using melt mixing, we produced a ceramic/polymer composite with a matrix of polyvinylidene fluoride (PVDF) and a filler of 5 vol.% Ni-deposited CaCu{sub 3}Ti{sub 4}O{sub 12} core-shell ceramic particles (CCTO@Ni), and studied its prominent dielectric characteristics for the first. Its phase composition and morphology were analyzed by X-ray diffraction and scanning electron microscopy, respectively. After treating the composite films with various durations of a magnetic field treatment, we compared their dielectric properties. We found that the CCTO@Ni ceramic had a typical urchin-like core-shell structure, and that different durations of the magnetic field treatment produced different distributions of ceramic particles in the PVDF matrix. The dielectric permittivity of the untreated CCTO@Ni/PVDF composite was 20% higher than that of neat PVDF, and it had a low loss tangent. However, only the composite treated for 30 min in the magnetic field had an ultra-high dielectric permittivity of 1.41 × 10{sup 4} at 10 Hz, three orders of magnitude higher than the untreated composite, which declined dramatically with increasing frequency, accompanied by an insulating-conducting phase transition and an increase in loss tangent. Our results demonstrate that changes in the dielectric properties of PVDF composites with magnetic field treatment are closely related to the percolation effect and interfacial polarization.
-
Yujian Sun; Cuihong Zhang; Le Zhou; Hua Fang; Jianhua Huang; Haipeng Ma; Yi Zhang; Jie Yang; Lan-Ying Zhang; Ping Song; Yanzi Gao; Jiumei Xiao; Fasheng Li; Kexuan Li
2016-01-01
Polymer-dispersed liquid crystal (PDLC) films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found...
-
International Nuclear Information System (INIS)
Nouralishahi, Amideddin; Khodadadi, Abbas Ali; Mortazavi, Yadollah; Rashidi, Alimorad; Choolaei, Mohammadmehdi
2014-01-01
Highlights: • Promoting effects of manganese oxide (MnO x ) on methanol electro-oxidation over Pt/MWCNTs are studied. • 3.3 times higher activity and improved stability are observed on Pt/MnO x -MWCNTs in MOR. • Both hydrogen spill over and bi-functional mechanism are facilitated in presence of MnO x . • MnO x significantly enhances electrochemical active surface area and dispersion of Pt nanoparticles. • Proton conductivity of electrocatalyst layer is improved upon MnO x incorporation. - Abstract: Electro-oxidation of methanol on platinum nanoparticles supported on a nanocomposite of manganese oxide (MnO x ) and multi-wall carbon nanotubes (MWCNTs) is investigated. The morphology, structure, and chemical composition of the electro-catalysts are characterized by TEM, XRD, EDS, TGA, and H 2 -TPR. The electro-catalytic properties of electrodes are examined by cyclic voltammetry, CO-stripping, electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV). Compared to Pt/MWCNTs, the Pt/MnO x -MWCNTs electro-catalyst exhibits about 3.3 times higher forward peak current density, during cyclic voltammetry, and 4.6 times higher exchange current density in methanol electro-oxidation reaction. In addition, deposition of manganese oxide onto MWCNTs dramatically increases the electrochemical active surface area from 29.7 for Pt/MWCNTs to 89.4 m 2 g −1 Pt for Pt/MnO x -MWCNTs. The results of long-term cyclic voltammetry show superior stability of Pt nanoparticles upon addition of manganese oxide to the support. Furthermore, the kinetics of formation of the chemisorbed OH groups improves upon manganese oxide incorporation. This leads to a lower onset potential of CO ads oxidation on Pt/MnO x -MWCNTs than on Pt/MWCNTs
-
Optical rotation and electron spin resonance of an electro-optically active polythiophene
International Nuclear Information System (INIS)
Goto, Hiromasa
2010-01-01
Graphical abstract: The electro-chiroptical polythiophene displays optical rotation at wavelengths corresponding to the doping band observable in the absorption spectra. The formation of polarons on the main-chain is confirmed by electron spin resonance measurements. - Abstract: A chiroptical polythiophene, is synthesized by electrolytic polymerization in a cholesteric liquid crystal electrolyte solution. The polymer displays a fingerprint texture similar to that of the cholesteric electrolyte solution. Upon electrochemical doping, the polymer displays optical rotation at wavelengths corresponding to the doping band observable in the absorption spectra. The formation of polarons on the main-chain is confirmed by electron spin resonance measurements. The results demonstrate the intermolecular chirality of polarons in this π-conjugated polymer, indicating continuum delocalized polarons are in a three-dimensional helical environment.
-
PVDF-PZT nanocomposite film based self-charging power cell.
Zhang, Yan; Zhang, Yujing; Xue, Xinyu; Cui, Chunxiao; He, Bin; Nie, Yuxin; Deng, Ping; Lin Wang, Zhong
2014-03-14
A novel PVDF-PZT nanocomposite film has been proposed and used as a piezoseparator in self-charging power cells (SCPCs). The structure, composed of poly(vinylidene fluoride) (PVDF) and lead zirconate titanate (PZT), provides a high piezoelectric output, because PZT in this nanocomposite film can improve the piezopotential compared to the pure PVDF film. The SCPC based on this nanocomposite film can be efficiently charged up by the mechanical deformation in the absence of an external power source. The charge capacity of the PVDF-PZT nanocomposite film based SCPC in 240 s is ∼0.010 μA h, higher than that of a pure PVDF film based SCPC (∼0.004 μA h). This is the first demonstration of using PVDF-PZT nanocomposite film as a piezoseparator for SCPC, and is an important step for the practical applications of SCPC for harvesting and storing mechanical energy.
-
Li, Mingming; Shi, Jie; Chen, Cheng; Li, Nan; Xu, Zhiwei; Li, Jing; Lv, Hanming; Qian, Xiaoming; Jiao, Xiaoning
2017-03-01
Nanoparticles may have suffered from low modification efficiency in hybrid membranes due to embedding and aggregating in polymer matrix. In order to analyze the modification mechanisms of nanoparticle migration and dispersion on the properties of hybrid membranes, we designed different F/ O ratios ( R F/ O ) of fluorinated graphene oxide (FGO, diameter = 1.5 17.5 μm) by carbon tetrafluoride (CF4) plasma treatment GO for 3, 5, 10, 15, and 20 min and successfully prepared novel PVDF hybrid membranes containing FGO via the phase inversion method. After a prolonged plasma treatment, the R F/ O of FGO was enhanced sharply, indicating an increasing compatibility of FGO with the matrix, especially FGO-20 (GO treated for 20 min). FGO contents in the top layer, sublayer, and the whole of membranes were probed by X-ray photoelectron spectroscopy, energy-dispersive spectrometer, and indirect computation, respectively. In the top layer of membranes, FGO contents declined from 13.14 wt% (PVDF/GO) to 4.00 wt% (PVDF/FGO-10) and 1.96 wt% (PVDF/FGO-20) due to the reduced migration ability of FGO. It is worth mentioning that PVDF/FGO-10 membranes exhibited an excellent water flux and flux recovery rate (up to 406.90 L m-2 h-1 and 88.9%), which were improved by 67.3% and 14.6% and 52.5% and 24.0% compared with those of PVDF/GO and PVDF/FGO-20 membranes, respectively, although the dispersion and migration ability of FGO-10 was maintained at a moderate level. It indicated that the migration and dispersion of FGO in membranes could result in dynamic equilibrium, which played a key role in making the best use of nanomaterials to optimize membrane performance.
-
Energy Technology Data Exchange (ETDEWEB)
Li, Mingming; Shi, Jie; Chen, Cheng; Li, Nan; Xu, Zhiwei, E-mail: xuzhiwei@tjpu.edu.cn; Li, Jing; Lv, Hanming; Qian, Xiaoming, E-mail: qianxiaoming@tjpu.edu.cn; Jiao, Xiaoning [Tianjin Polytechnic University, State Key Laboratory of Separation Membranes and Membrane Processes, School of Textiles (China)
2017-03-15
Nanoparticles may have suffered from low modification efficiency in hybrid membranes due to embedding and aggregating in polymer matrix. In order to analyze the modification mechanisms of nanoparticle migration and dispersion on the properties of hybrid membranes, we designed different F/O ratios (R{sub F/O}) of fluorinated graphene oxide (FGO, diameter = 1.5 ~ 17.5 μm) by carbon tetrafluoride (CF{sub 4}) plasma treatment GO for 3, 5, 10, 15, and 20 min and successfully prepared novel PVDF hybrid membranes containing FGO via the phase inversion method. After a prolonged plasma treatment, the R{sub F/O} of FGO was enhanced sharply, indicating an increasing compatibility of FGO with the matrix, especially FGO-20 (GO treated for 20 min). FGO contents in the top layer, sublayer, and the whole of membranes were probed by X-ray photoelectron spectroscopy, energy-dispersive spectrometer, and indirect computation, respectively. In the top layer of membranes, FGO contents declined from 13.14 wt% (PVDF/GO) to 4.00 wt% (PVDF/FGO-10) and 1.96 wt% (PVDF/FGO-20) due to the reduced migration ability of FGO. It is worth mentioning that PVDF/FGO-10 membranes exhibited an excellent water flux and flux recovery rate (up to 406.90 L m{sup −2} h{sup −1} and 88.9%), which were improved by 67.3% and 14.6% and 52.5% and 24.0% compared with those of PVDF/GO and PVDF/FGO-20 membranes, respectively, although the dispersion and migration ability of FGO-10 was maintained at a moderate level. It indicated that the migration and dispersion of FGO in membranes could result in dynamic equilibrium, which played a key role in making the best use of nanomaterials to optimize membrane performance.
-
Yang, Wulin
2014-10-14
Air cathodes used in microbial fuel cells (MFCs) need to have high catalytic activity for oxygen reduction, but they must also be easy to manufacture, inexpensive, and watertight. A simple one-step, phase inversion process was used here to construct an inexpensive MFC cathode using a poly(vinylidene fluoride) (PVDF) binder and an activated carbon catalyst. The phase inversion process enabled cathode preparation at room temperatures, without the need for additional heat treatment, and it produced for the first time a cathode that did not require a separate diffusion layer to prevent water leakage. MFCs using this new type of cathode produced a maximum power density of 1470 ± 50 mW m–2 with acetate as a substrate, and 230 ± 10 mW m–2 with domestic wastewater. These power densities were similar to those obtained using cathodes made using more expensive materials or more complex procedures, such as cathodes with a polytetrafluoroethylene (PTFE) binder and a poly(dimethylsiloxane) (PDMS) diffusion layer, or a Pt catalyst. Even though the PVDF cathodes did not have a diffusion layer, they withstood up to 1.22 ± 0.04 m of water head (∼12 kPa) without leakage, compared to 0.18 ± 0.02 m for cathodes made using PTFE binder and PDMS diffusion layer. The cost of PVDF and activated carbon ($3 m–2) was less than that of the stainless steel mesh current collector ($12 m–2). PVDF-based AC cathodes therefore are inexpensive, have excellent performance in terms of power and water leakage, and they can be easily manufactured using a single phase inversion process at room temperature.
-
Ghasemian, Samaneh; Sahari, Mohammad Ali; Barzegar, Mohsen; Ahmadi Gavlighi, Hasan
2017-09-01
In this study, polyvinylidene fluoride (PVDF) and nano-porous silica particle were used to fabricate an asymmetric nano-composite membrane. Silica particles enhanced the thermal stability of PVDF/SiO 2 membranes; increasing the decomposition temperature from 371°C to 408°C. Cross sectional morphology showed that silica particles were dispersed in polymer matrix uniformly. However, particle agglomeration was found at higher loading of silica (i.e., 20 by weight%). The separation performance of nano-composite membranes was also evaluated using the omega-3 polyunsaturated fatty acids (PUFA) concentration at a temperature and pressure of 30°C and 4bar, respectively. Silica particle increased the omega-3PUFA concentration from 34.8 by weight% in neat PVDF to 53.9 by weight% in PVDF with 15 by weight% of silica. Moreover, PVDF/SiO 2 nano-composite membranes exhibited enhanced anti-fouling property compared to neat PVDF membrane. Fouling mechanism analysis revealed that complete pore blocking was the predominant mechanism occurring in oil filtration. The concentration of omega-3 polyunsaturated fatty acids (PUFA) is important in the oil industries. While the current methods demand high energy consumptions in concentrating the omega-3, membrane separation technology offers noticeable advantages in producing pure omega-3 PUFA. Moreover, concentrating omega-3 via membrane separation produces products in the triacylglycerol form which possess better oxidative stability. In this work, the detailed mechanisms of fouling which limits the performance of membrane separation were investigated. Incorporating silica particles to polymeric membrane resulted in the formation of mixed matrix membrane with improved anti-fouling behaviour compared to the neat polymeric membrane. Hence, the industrial potential of membrane processing to concentrate omega-3 fatty acids is enhanced. Copyright © 2017. Published by Elsevier Ltd.
-
APPLICATION OF PIEZOELECTRIC MATERIAL FILM PVDF (Polyvinylidene Flouride AS LIQUID VISCOSITY SENSOR
Directory of Open Access Journals (Sweden)
Hananto F. S, Santoso D.R., Julius
2012-03-01
Research was done by taking 10 samples of oil and 3 different size ofPVDF film and a strain gage,that are: 1 cm x 3 cm (PVDF1; 1 cm x 2 cm (PVDF2; 1 cm x 1 cm (PVDF3. Results showed that the resolution of PVDF1, PVDF2 and PVDF3 are 4.6 mv/cPois; 3.1 mv/cPois and 1.5 mv/cPois respectively, while the strain gage produce a resolution of 1.2 mv/cPois. The average resolution of PVDF is 1.53 mv.cPois-1.cm-2, which means that every 1 cm2 PVDF film area and the increase of 1 cPois of viscosity of the material will produce 1.53 millivolts.
-
Efome, Johnson E; Rana, Dipak; Matsuura, Takeshi; Lan, Christopher Q
2016-02-01
Membrane distillation (MD) is a promising separation technique capable of being used in the desalination of marine and brackish water. Poly(vinylidene fluoride) (PVDF) flat sheet nano-composite membranes were surface modified by coating with electro-spun PVDF nano-fibres to increase the surface hydrophobicity. For this purpose, the nano-composite membrane containing 7 wt.% superhydrophobic SiO2 nano-particles, which showed the highest flux in our previous work, was first subjected to pore size augmentation by increasing the concentration of the pore forming agent (Di-ionized water). Then, the prepared flat sheet membranes were subjected to nanofibres coating by electro-spinning. The uncoated and coated composite fabricated membranes were characterized using contact angle, liquid entry pressure of water, and scanning electron microscopy. The membranes were further tested for 6 h desalination by direct contact membrane distillation (DCMD) and vacuum membrane distillation (VMD), with a 3.5 wt.% synthetic NaClaq as the feed. In DCMD the feed liquid and permeate side temperature were maintained at 27.5 °C and 15 °C, respectively. For VMD, the feed liquid temperature was 27 °C and a vacuum of 94.8 kPa was applied on the permeate side. The maximum permeate flux achieved was 3.2 kg/m(2).h for VMD and 6.5 kg/m(2).h for DCMD. The salt rejection obtained was higher than 99.98%. The coated membranes showed a more stable flux than the uncoated membranes indicating that the double layered membranes have great potential in solving the pore wetting problem in MD. Copyright © 2015 Elsevier Ltd. All rights reserved.
-
Kamberi, Marika; Pinson, David; Pacetti, Stephen; Perkins, Laura E L; Hossainy, Syed; Mori, Hiroyoshi; Rapoza, Richard J; Kolodgie, Frank; Virmani, Renu
2017-09-07
The polymers poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and poly(n-butyl methacrylate) (PBMA) are employed in manufacturing the XIENCE family of coronary stents. PBMA serves as a primer and adheres to both the stent and the drug coating. PVDF-HFP is employed in the drug matrix layer to hold the drug everolimus on the stent and control its release. Chemical stability of the polymers of XIENCE stents in the in-vivo environment was evaluated by pyrolysis-gas chromatography with mass spectrometry (Py-GC/MS) detection. For this evaluation, XIENCE stents explanted from porcine coronary arteries and from human coronary artery specimens at autopsy after 2-4 and 5-7 years of implantation, respectively, were compared to freshly manufactured XIENCE stents (controls). The comparison of pyrograms of explanted stent samples and controls showed identical fragmentation fingerprints of polymers, indicating that PVDF-HFP and PBMA maintained their chemical integrity after multiple years of XIENCE coronary stent implantation. The findings of the present study demonstrate the chemical stability of PVDF-HFP and PBMA polymers of the XIENCE family of coronary stents in the in-vivo environment, and constitute a further proof of the suitability of PVDF-HFP as a drug carrier for the drug eluting stent applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.
-
Energy Technology Data Exchange (ETDEWEB)
Nguyen, L.; Mighri, F.; Deyrail, Y. [CREPEC, Center for Applied Research on Polymers and Composites, QC (Canada); Department of Chemical Engineering, Laval University, QC (Canada); Elkoun, S. [CREPEC, Center for Applied Research on Polymers and Composites, QC (Canada); Department of Mechanical Engineering, Sherbrooke University, QC (Canada)
2010-12-15
The aim of this work was to develop and characterise electrically conductive materials for proton exchange membrane fuel cells and bipolar plates (BPPs). These BPPs were made from highly conductive blends of polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF), as matrix phase. The conductive materials were developed from carefully formulated blends composed of conductive carbon black (CB) powder and, in some cases, graphite synthetic flakes mixed with pure PET, PVDF or with PVDF/PET systems. They were first developed by twin-screw extrusion process then compression-molded to give BPP final shape. As the developed blends have to meet properties suitable for BPP applications, they were characterised for their rheological properties, electrical through-plane resistivity (the inverse of conductivity), oxygen permeability, flexural and impact properties. Results showed that lower resistivity was obtained with PVDF/CB blends due to the higher interfacial energy between the PVDF matrix and CB and also the higher density and crystallinity of PVDF, compared to those of PET. It was also observed that the lowest resistivity values were obtained with mixing PVDF and PET at controlled compositions to ensure PVDF/PET co-continuous morphology. Also, slow cooling rates helped to attain the lowest values of through-plane resistivity for all studied blends. This behaviour was related to the higher crystallinity obtained with low cooling rates leading to smaller amorphous regions in which carbon particles are much more concentrated. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
-
International Nuclear Information System (INIS)
Truong, Bui Ngoc Minh; Nam, Doan Ngoc Chi; Ahn, Kyoung Kwan
2013-01-01
Dielectric electro-active polymer (DEAP) materials are attractive since they are low cost, lightweight and have a large deformation capability. They have no operating noise, very low electric power consumption and higher performance and efficiency than competing technologies. However, DEAP materials generally have strong hysteresis as well as uncertain and nonlinear characteristics. These disadvantages can limit the efficiency in the use of DEAP materials. To address these limitations, this research will present the combination of the Preisach model and the dynamic nonlinear autoregressive exogenous (NARX) fuzzy model-based adaptive particle swarm optimization (APSO) identification algorithm for modeling and identification of the nonlinear behavior of one typical type of DEAP actuator. Firstly, open loop input signals are applied to obtain nonlinear features and to investigate the responses of the DEAP actuator system. Then, a Preisach model can be combined with a dynamic NARX fuzzy structure to estimate the tip displacement of a DEAP actuator. To optimize all unknown parameters of the designed combination, an identification scheme based on a least squares method and an APSO algorithm is carried out. Finally, experimental validation research is carefully completed, and the effectiveness of the proposed model is evaluated by employing various input signals. (paper)
-
Töpper, Tino; Osmani, Bekim; Weiss, Florian M.; Winterhalter, Carla; Wohlfender, Fabian; Leung, Vanessa; Müller, Bert
2015-04-01
Fecal incontinence describes the involuntary loss of bowel content and affects about 45 % of retirement home residents and overall more than 12 % of the adult population. Artificial sphincter implants for treating incontinence are currently based on mechanical systems with failure rates resulting in revision after three to five years. To overcome this drawback, artificial muscle sphincters based on bio-mimetic electro-active polymer (EAP) actuators are under development. Such implants require polymer films that are nanometer-thin, allowing actuation below 24 V, and electrodes that are stretchable, remaining conductive at strains of about 10 %. Strain-dependent resistivity measurements reveal an enhanced conductivity of 10 nm compared to 30 nm sputtered Au on silicone for strains higher than 5 %. Thus, strain-dependent morphology characterization with optical microscopy and atomic force microscopy could demonstrate these phenomena. Cantilever bending measurements are utilized to determine elastic/viscoelastic properties of the EAP films as well as their long-term actuation behavior. Controlling these properties enables the adjustment of growth parameters of nanometer-thin EAP actuators.
-
International Nuclear Information System (INIS)
Nasef, Mohamed Mahmoud; Dahlan, Khairul Zaman M.
2003-01-01
The effects of electron beam irradiation on two partially fluorinated polymer films i.e. poly(vinylidene fluoride) (PVDF) and poly(ethylene-tetrafluoroethylene) copolymer (ETFE) are studied at doses ranging from 100 to 1200 kGy in air at room temperature. Chemical structure, thermal and mechanical properties of irradiated films are investigated. FTIR show that both PVDF and ETFE films undergo similar changes in their chemical structures including the formation of carbonyl groups and double bonding. The changes in melting and crystallisation temperatures (T m and T c ) in both irradiated films are functions of irradiation dose and reflect the disorder in the chemical structure caused by the competition between crosslinking and chain scission. The heat of melting (ΔH m ) and the degree of crystallinity (X c ) of PVDF films show no significant changes with the dose increase, whereas those of ETFE films are reduced rapidly after the first 100 kGy. The tensile strength of PVDF films is improved by irradiation compared to its rapid deterioration in ETFE films, which stemmed from the degradation prompted by the presence of radiation sensitive tetrafluoroethylene (TFE) comonomer units. The elongation at break of both films drops gradually with the dose increase indicating the formation of predominant crosslinked structures at high doses. However, the response of each polymer to crosslinking and main chain scission at various irradiation doses varies from PVDF to ETFE films
-
Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications
Asif Khan; Zafar Abas; Heung Soo Kim; Jaehwan Kim
2016-01-01
We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active pa...
-
An investigation of energy harvesting from renewable sources with PVDF and PZT
International Nuclear Information System (INIS)
Vatansever, D; Hadimani, R L; Shah, T; Siores, E
2011-01-01
Piezoelectric materials have been in use for many years; however, with an increasing concern about global warming, piezoelectricity has gained significant importance in research and development for extracting energy from the environment. In this work the voltage responses of ceramic based piezoelectric fibre composite structures (PFCs) and polymer based piezoelectric strips, PVDF (polyvinylidene fluoride), were evaluated when subjected to various wind speeds and water droplets in order to investigate the possibility of energy generation from these two natural renewable energy sources for utilization in low power electronic devices. The effects of material dimensions, drop mass, releasing height of the drops and wind speed on the voltage output were studied and the power was calculated. This work showed that piezoelectric polymer materials can generate higher voltage/power than ceramic based piezoelectric materials and it was proved that producing energy from renewable sources such as rain drops and wind is possible by using piezoelectric polymer materials
-
The Integration and Applications of Organic Thin Film Transistors and Ferroelectric Polymers
Hsu, Yu-Jen
using a UV-Ozone treatment to shift the threshold voltage and increase the current of the transistor under both compressive and tensile strain. An array of strain sensors which maps the strain field on a PVDF film surface is demonstrated in this work. The strain sensor experience inspires a tone analyzer built using distributed resonator architecture on a tensioned piezoelectric PVDF sheet. This sheet is used as both the resonator and detection element. Two architectures are demonstrated; one uses distributed directly addressed elements as a proof of concept, and the other integrates organic thin film transistor-based transimpedance amplifiers monolithically with the PVDF sheet to convert the piezoelectric charge signal into a current signal for future applications such as sound field imaging. The PVDF sheet material is instrumented along its length and the amplitude response at 15 sites is recorded and analyzed as a function of the frequency of excitation. The determination of the dominant frequency component of an incoming sound is demonstrated using linear system decomposition of the time-averaged response of the sheet using no time domain detection. Our design allows for the determination of the spectral composition of a sound using the mechanical signal processing provided by the amplitude response and eliminates the need for time-domain electronic signal processing of the incoming signal. The concepts of the PVDF strain sensor and the tone analyzer trigger the idea of an active matrix microphone through the integration of organic thin film transistors with a freestanding piezoelectric polymer sheet. Localized acoustic pressure detection is enabled by switch transistors and local transimpedance amplification built into the active matrix architecture. The frequency of detection ranges from DC to 15KHz; the bandwidth is extended using an architecture that provides for virtually zero gate/source and gate/drain capacitance at the sensing transistors and low overlap
-
Impedance characteristics of nanoparticle-LiCoO{sub 2}+PVDF
Energy Technology Data Exchange (ETDEWEB)
Panjaitan, Elman, E-mail: elmanp@batan.go.id; Kartini, Evvy, E-mail: kartini@batan.go.id; Honggowiranto, Wagiyo [Center for Science and Technology for Advanced Materials, National Nuclear Energy Agency Kawasan Puspiptek Serpong, Tangerang Selatan15314 (Indonesia)
2016-02-08
The impendance of np-LiCoO{sub 2}+xPVDF, as a cathode material candidate for lithium-ion battery (LIB), has been characterized using impedance spectroscopy for x = 0, 5, 10, 15 and 20 volume percentage (%v/v) and for frequencies in the 42 Hz to 5 MHz range. Both real and imaginary components of the impedance were found to be frequency dependent, and both tend to increase for increasing PVDF (polyvinyilidene fluoride) concentration, except that for 10% PVDF both real and imaginary components of impedance are smaller than for 5%. The mechanism for relaxation time for each addition of PVDF was analyzed using Cole-Cole plots. The analysis showed that the relaxation times of the nanostructured LiCoO{sub 2} with PVDF additive is relatively constant. Further, PVDF addition increases the bulk resistance and decreases the bulk capacitance of the nanostructured LiCoO{sub 2}.
-
Electrospun PVdF-based fibrous polymer electrolytes for lithium ion polymer batteries
International Nuclear Information System (INIS)
Kim, Jeong Rae; Choi, Sung Won; Jo, Seong Mu; Lee, Wha Seop; Kim, Byung Chul
2004-01-01
This paper discusses the preparation of microporous fibrous membranes from PVdF solutions with different polymer contents, using the electrospinning technique. Electrospun PVdF-based fibrous membranes with average fiber diameters (AFD's) of 0.45-1.38 μm have an apparent porosity and a mean pore size (MPS) of 80-89% and 1.1-4.3 μm, respectively. They exhibited a high uptake of the electrolyte solution (320-350%) and a high ionic conductivity of above 1 x 10 -3 s/cm at room temperature. Their ionic conductivity increased with the decrease in the AFD of the fibrous membrane due to its high electrolyte uptake. The interaction between the electrolyte molecules and the PVdF with a high crystalline content may have had a minor effect on the lithium ion transfer in the fibrous polymer electrolyte, unlike in a nanoporous gel polymer electrolyte. The fibrous polymer electrolyte that contained a 1 M LiPF 6 -EC/DMC/DEC (1/1/1 by weight) solution showed a high electrochemical stability of above 5.0 V, which increased with the decrease in the AFD The interfacial resistance (R i ) between the polymer electrolyte and the lithium electrode slightly increased with the storage time, compared with the higher increase in the interfacial resistance of other gel polymer electrolytes. The prototype cell (MCMB/PVdF-based fibrous electrolyte/LiCoO 2 ) showed a very stable charge-discharge behavior with a slight capacity loss under constant current and voltage conditions at the C/2-rate of 20 and 60 deg. C
-
Theory-Guided Design of Organic Electro-Optic Materials and Devices
Directory of Open Access Journals (Sweden)
Stephanie Benight
2011-08-01
Full Text Available Integrated (multi-scale quantum and statistical mechanical theoretical methods have guided the nano-engineering of controlled intermolecular electrostatic interactions for the dramatic improvement of acentric order and thus electro-optic activity of melt-processable organic polymer and dendrimer electro-optic materials. New measurement techniques have permitted quantitative determination of the molecular order parameters, lattice dimensionality, and nanoscale viscoelasticity properties of these new soft matter materials and have facilitated comparison of theoretically-predicted structures and thermodynamic properties with experimentally-defined structures and properties. New processing protocols have permitted further enhancement of material properties and have facilitated the fabrication of complex device structures. The integration of organic electro-optic materials into silicon photonic, plasmonic, and metamaterial device architectures has led to impressive new performance metrics for a variety of technological applications.
-
Coupled modeling and simulation of electro-elastic materials at large strains
Possart, Gunnar; Steinmann, Paul; Vu, Duc-Khoi
2006-03-01
In the recent years various novel materials have been developed that respond to the application of electrical loading by large strains. An example is the class of so-called electro-active polymers (EAP). Certainly these materials are technologically very interesting, e.g. for the design of actuators in mechatronics or in the area of artificial tissues. This work focuses on the phenomenological modeling of such materials within the setting of continuum-electro-dynamics specialized to the case of electro-hyperelastostatics and the corresponding computational setting. Thereby a highly nonlinear coupled problem for the deformation and the electric potential has to be considered. The finite element method is applied to solve the underlying equations numerically and some exemplary applications are presented.
-
International Nuclear Information System (INIS)
Raja, Mohan; Shanmugharaj, A.M.; Ryu, Sung Hun; Subha, J.
2011-01-01
Highlights: → Polyurethane based on pristine and metal (Ag and Cu) nanoparticle decorated CNTs nanocomposites are prepared through melt blending process. → The electrical, mechanical, dynamic mechanical, thermal conductivity and electro active shape memory properties of the PU nanocomposites were investigated. → The influence of metal nanoparticle decorated CNTs showed significant improvement in their all properties to compare to pristine CNTs. → Electro active shape memory studies of the PU/M-CNTs nanocomposites reveal extraordinary recoverability of its shape at lower applied dc voltages. - Abstract: Polymer nanocomposites based on thermoplastic polyurethane (PU) elastomer and metal nanoparticle (Ag and Cu) decorated multiwall carbon nanotubes (M-CNTs) were prepared through melt mixing process and investigated for its mechanical, dynamic mechanical and electro active shape memory properties. Structural characterization and morphological characterization of the PU nanocomposites were done using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Morphological characterization revealed better dispersion of M-CNTs in the polyurethane, which is attributed to the improved interaction between the M-CNTs and polyurethane. Loading of the metal nanoparticle coated carbon nanotubes resulted in the significant improvement on the mechanical properties such as tensile strength of the PU composites in comparison to the pristine carbon nanotubes (P-CNTs). Dynamic mechanical analysis showed that the glass transition temperature (Tg) of the polyurethane increases slightly with increasing loading of both pristine and metal nanoparticle functionalized carbon nanotubes. The metal nanoparticles decorated carbon nanotubes also showed significant improvement in the thermal and electrical conductivity of the PU/M-CNTs nanocomposites. Shape memory studies of the PU/M-CNTs nanocomposites exhibit remarkable recoverability of its shape at lower applied dc voltages.
-
Investigations on Structural, Mechanical, and Dielectric Properties of PVDF/Ceramic Composites
Directory of Open Access Journals (Sweden)
Anshuman Srivastava
2015-01-01
Full Text Available Polymer ceramic composites are widely used for embedded capacitor application. In the present work PVDF has been used as a matrix and CCTO and LaCCTO have been used as reinforcement. Extrusion process has been used for the synthesis of composites. X-ray diffraction (XRD patterns confirm the formation of single phase CCTO, and LaCCTO in its pure as well as composite state. It is found that La doping in CCTO considerably increases the dielectric constant and reduces the dielectric loss. A similar trend is observed in the composites with the increasing content of CCTO and LaCCTO.
-
Enhanced dielectric and electrical properties of annealed PVDF thin film
Arshad, A. N.; Rozana, M. D.; Wahid, M. H. M.; Mahmood, M. K. A.; Sarip, M. N.; Habibah, Z.; Rusop, M.
2018-05-01
Poly (vinylideneflouride) (PVDF) thin films were annealed at various annealing temperatures ranging from 70°C to 170°C. This study demonstrates that PVDF thin films annealed at temperature of 70°C (AN70) showed significant enhancement in their dielectric constant (14) at frequency of 1 kHz in comparison to un-annealed PVDF (UN-PVDF), dielectric constant (10) at the same measured frequency. As the annealing temperature was increased from 90°C (AN90) to 150°C (AN150), the dielectric constant value of PVDF thin films was observed to decrease gradually to 11. AN70 also revealed low tangent loss (tan δ) value at similar frequency. With respect to its resistivity properties, the values were found to increase from 1.98×104 Ω.cm to 3.24×104 Ω.cm for AN70 and UN-PVDF films respectively. The improved in dielectric constant, with low tangent loss and high resistivity value suggests that 70°C is the favorable annealing temperature for PVDF thin films. Hence, AN70 is a promising film to be utilized for application in electronic devices such as low frequency capacitor.
-
Prediction and correlation of high-pressure gas solubility in polymers with simplified PC-SAFT
DEFF Research Database (Denmark)
von Solms, Nicolas; Michelsen, Michael Locht; Kontogeorgis, Georgios
2005-01-01
Using simplified PC-SAFT we have modeled gas solubilities at high temperatures and pressures for the gases methane and carbon dioxide in each of the three polymers high-density polyethylene (HDPE), nylon polyamide-11 (PA-11), and poly(vinylidene fluoride) (PVDF). In general the results are satisf......Using simplified PC-SAFT we have modeled gas solubilities at high temperatures and pressures for the gases methane and carbon dioxide in each of the three polymers high-density polyethylene (HDPE), nylon polyamide-11 (PA-11), and poly(vinylidene fluoride) (PVDF). In general the results...
-
Swift Heavy Ion Induced Modification of Aliphatic Polymers
Hossain, Umme Habiba
2015-01-01
In this thesis, the high energy heavy ion induced modification of aliphatic polymers is studied. Two polymer groups, namely polyvinyl polymers (PVF, PVAc, PVA and PMMA) and fluoropolymers (PVDF, ETFE, PFA and FEP) were used in this work. Polyvinyl polymers were investigated since they will be used as insulating materials in the superconducting magnets of the new ion accelerators of the planned International Facility for Antiproton and Ion Research (FAIR) at the GSI Helmholtz-Centre of Heavy I...
-
Xie, Yunchuan; Wang, Jian; Yu, Yangyang; Jiang, Wanrong; Zhang, Zhicheng
2018-05-01
Polymer/ceramic nanocomposites are promising dielectrics for high energy storage density (Ue) capacitors. However, their low breakdown strength (Eb) and high dielectric loss due to heterogeneous structure seriously limit their applications under high electric field. In this work, boron nitride nano-sheets (BNNS) exfoliated from BN particles were introduced into PVDF-based BaTiO3 (mBT) binary composites to reduce the dielectric loss and promote the Ue. The effects of BNNS on the dielectric properties, especially breakdown resistance, and energy storage performance of the resultant composites were carefully investigated by comparing with the composites without BNNS. The introduction of BNNS could significantly improve Eb and Ue of the final composites. Ternary composite with particle contents of 6 wt% BNNS and 5 wt% mBT presented a Eb of about 400 MV/m and Ue of 5.2 J/cm3, which is 40% and 30% superior to that of the binary composite with 5 wt% mBT, respectively. That may be attributed to the 2D structure, high bulk electrical resistivity, and fine dispersion in PVDF of BNNS, which is acting as an efficient insulating barrier against the leakage current and charges conduction. The depression effect of BNNS onto the charge mobility and the interfacial polarization of the polymer composites is finely addressed, which may offer a promising strategy for the fabrication of high-k polymer composites with low loss.
-
Energy Technology Data Exchange (ETDEWEB)
Nasef, Mohamed Mahmoud [Business and Advanced Technology Centre (BATC), Universiti Teknologi Malaysia, Jalan Semarak, 54100 Kuala Lumpur (Malaysia)]. E-mail: mahmoudeithar@mailcity.com; Saidi, Hamdani [Business and Advanced Technology Centre (BATC), Universiti Teknologi Malaysia, Jalan Semarak, 54100 Kuala Lumpur (Malaysia)
2006-10-10
Structural, thermal and ion transport properties of lithium conductive polymer electrolytes prepared by radiation-induced grafting of styrene onto poly(vinylidene fluoride) (PVDF) films and subsequent activation with LiPH{sub 6}/EC/DEC liquid electrolyte were investigated in correlation with the content of the grafted polystyrene (Y%). The changes in the structure were studied using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Thermal gravimetric analysis (TGA) was used to evaluate the thermal stability. The ionic conductivity was measured by means of ac impedance spectroscopy at various temperatures. The polymer electrolytes were found to undergo considerable structural and morphological changes that resulted in a noticeable increase in their ionic conductivity with the increase in Y% at various temperatures (25-65 deg. C). The ionic conductivity achieved a value of 1.61 x 10{sup -3} S cm{sup -1} when Y of the polymer electrolyte reached 50% and at 25 deg. C. The polymer electrolytes also showed a multi-step degradation behaviour and thermal stability up to 120 deg. C, which suits normal lithium battery operation temperature range. The overall results of this work suggest that the structural changes took place in PVDF matrix during the preparation of these polymer electrolytes have a strong impact on their various properties.
-
Dorneanu, Petronela Pascariu; Cojocaru, Corneliu; Olaru, Niculae; Samoila, Petrisor; Airinei, Anton; Sacarescu, Liviu
2017-12-01
In this work, pure polyvinylidene fluoride (PVDF) and PVDF/cobalt ferrite (CoFe2O4) magnetic fibrous composite were successfully prepared by electrospinning method for oil spill sorption applications. The pure spinel phase of CoFe2O4 and PVDF/CoFe2O4 composites were confirmed by X-ray diffraction analysis (XRD). Electrospun sorbent materials were characterized by scanning and transmission electron microscopy (SEM and TEM) as well as by contact angle measurements. In addition, the composite sorbent (PVDF/CoFe2O4) was characterized by magnetic measurements. It revealed good magnetic properties that are of real interest to facilitate the separation of the oil-loaded sorbent under the external magnetic field. Finally, the produced electrospun sorbents were tested for sorption of oily liquids, such as: decane, dodecane and commercial motor oils. We obtained good oil sorption capacity (between 9.751-23.615 g/g of pure PVDF) and (8.133-18.074 g/g for the magnetic composite) depending on the nature of oil tested. The present electrospun magnetic PVDF/CoFe2O4 fibrous composite could be potentially useful for the efficient removal of oil in water and recovery of sorbent material.
-
Energy Technology Data Exchange (ETDEWEB)
Lafarge, M.
2004-12-15
Pipeline structures are used for the transport of crude oil in offshore fields. Flexible pipelines are made of an inner metallic layer, which accommodates flexural and tensile strains and of a PVDF layer, which guarantees watertightness. The aim of the study is to determine which conditions can lead to a risk of brittle fracture of the polymer material. The PVDF of interest was extruded without plasticizer and therefore it differs considerably from the standard industrial grade. The lack of plasticizer leads to a difficult extrusion, which creates significant porosity (10%). Several specimens with various geometries were tested in order to analyse the detrimental effect of a defect regarding damage evolution and fracture mechanisms. During the deformation process, the material is characterized by whitening due to void growth and material elongation. Ductile fracture of PVDF is promoted by high temperatures, low strain rates, low stress triaxiality ratios and flexural loading, whereas brittle fracture is favoured by low temperatures (T{<=}Tg = -42 C), high strain rates, high stress triaxiality ratios and tensile loading. The Gurson-Tvergaard-Needleman model, usually used for metallic materials, was employed to model behaviour and damage of PVDF material at various temperatures. Damage is essentially due to void growth and is described by using q1 and q2 parameters. The constitutive model has been successfully applied to account for all aspects of the mechanical behaviour of the material. Crazing is the failure mode and final fracture is assumed to occur when either, the maximum principal plastic strain at low stress triaxiality or the porosity at high stress triaxiality reaches respectively a critical value. Furthermore, the ductile to brittle transition criterion is found to be the maximum principal stress. This latter allows to explain both fracture mechanisms modes in flexural and tensile loading. (author)
-
Enhanced discharge energy density of rGO/PVDF nanocomposites: The role of the heterointerface
Zhang, Ye; Wang, Yaqiong; Qi, Shaojun; Dunn, Steve; Dong, Hanshan; Button, Tim
2018-05-01
Recent reports of conductive-filler/polymer composites with large dielectric permittivity (K) make them potential candidates for flexible capacitors. Hence, an interesting question is how these high K composites behave under a strong electric field strength. In this letter, we use in-situ-reduced graphite oxide (rGO)/poly(vinylidene fluoride) (PVDF) nanocomposites as an example to study the energy storage behaviour of high K materials. We show the dielectric behaviour contrasts between weak and strong fields. High K materials inevitably become more lossy with increasing field strength. Simultaneously, we reveal that the in-situ reduction temperature can affect the energy storage performance. Improved energy storage performance is achieved for a nanocomposite reduced at a moderate temperature. When reduced at 160 °C, a device with an rGO volume fraction of 1.5 vol. % displayed a discharge energy density of 0.67 J/cm3 at 50 MV/m. This was 2.9 times greater than pure PVDF. We develop a model to explain this behaviour that proposes a reduced electrical contrast of the rGO/PVDF heterointerface minimising the recombination of localized charge carriers. Our results indicate, simultaneously, the potential and limitation of high K nanocomposites and shed light on the optimisation of the design and fabrication of high discharge energy density flexible capacitors for microelectronic devices.
-
Directory of Open Access Journals (Sweden)
B. V. Bhaskara Rao
2016-06-01
Full Text Available Radar X-band electromagnetic interference shielding (EMS is one of the prime requirements for any air vehicle coating; with limitations on the balance between strength and thickness of the EMS material. Nanocomposite of multiwalled-carbon-nanotubes (MWCNT has been homogeneously integrated (0 – 9 wt% with polymer, poly (vinylidene fluoride, PVDF to yield 300 micron film. The PVDF + 9 wt% MWCNT sample of density 1.41 g/cm3 show specific shielding effectiveness (SSE of 17.7 dB/(g/cm3 (99.6% EMS, with maintained hardness and improved conductivity. With multilayer stacking (900 microns of these films of density 1.37 g/cm3, the sample showed increase in SSE to 23.3 dB/(g/cm3 (99.93% EMS. Uniform dispersion of MWCNTs in the PVDF matrix gives rise to increased conductivity in the sample beyond 5 wt% MWCNT reinforcement. The results are correlated to the hardness, reflection loss, absorption loss, percolation threshold, permittivity and the conductivity data. An extremely thin film with maximum EMS property is hence proposed.
-
Dielectric and polarization behaviour of cellulose electro-active paper (EAPap)
International Nuclear Information System (INIS)
Yun, Gyu-Young; Kim, Joo-Hyung; Kim, Jaehwan
2009-01-01
Dielectric and polarization behaviour of electro-active paper (EAPap) were studied to understand the detailed material behaviour of EAPap as a novel smart material. It was revealed that the dielectric constant of EAPap was temperature and frequency dependent. The largest change in the dielectric constant was observed near 0 0 C while the highest dielectric constant was obtained at around 100 0 C, which might be related to the dipolar behaviour of the hydroxyl structure of cellulose and adsorbed or existing internal water molecules in cellulose EAPap. By thermal stimulated current measurement for polarization behaviour of cellulose EAPap, it was shown that the maximum current was observed in the temperature range 105-110 0 C. Compared with the polarization behaviour in the low temperature range, abnormal polarization was observed under an applied field mainly due to the trapped space charge in EAPap, which indicates that cellulose EAPap has a similar material behaviour to that of electret polymers. (fast track communication)
-
Electro-Conductive Membranes for Permeation Enhancement and Fouling Mitigation: A Short Review
Directory of Open Access Journals (Sweden)
Patrizia Formoso
2017-07-01
Full Text Available The research on electro-conductive membranes has expanded in recent years. These membranes have strong prospective as key components in next generation water treatment plants because they are engineered in order to enhance their performance in terms of separation, flux, fouling potential, and permselectivity. The present review summarizes recent developments in the preparation of electro-conductive membranes and the mechanisms of their response to external electric voltages in order to obtain an improvement in permeation and mitigation in the fouling growth. In particular, this paper deals with the properties of electro-conductive polymers and the preparation of electro-conductive polymer membranes with a focus on responsive membranes based on polyaniline, polypyrrole and carbon nanotubes. Then, some examples of electro-conductive membranes for permeation enhancement and fouling mitigation by electrostatic repulsion, hydrogen peroxide generation and electrochemical oxidation will be presented.
-
Electro-Conductive Membranes for Permeation Enhancement and Fouling Mitigation: A Short Review.
Formoso, Patrizia; Pantuso, Elvira; De Filpo, Giovanni; Nicoletta, Fiore Pasquale
2017-07-28
The research on electro-conductive membranes has expanded in recent years. These membranes have strong prospective as key components in next generation water treatment plants because they are engineered in order to enhance their performance in terms of separation, flux, fouling potential, and permselectivity. The present review summarizes recent developments in the preparation of electro-conductive membranes and the mechanisms of their response to external electric voltages in order to obtain an improvement in permeation and mitigation in the fouling growth. In particular, this paper deals with the properties of electro-conductive polymers and the preparation of electro-conductive polymer membranes with a focus on responsive membranes based on polyaniline, polypyrrole and carbon nanotubes. Then, some examples of electro-conductive membranes for permeation enhancement and fouling mitigation by electrostatic repulsion, hydrogen peroxide generation and electrochemical oxidation will be presented.
-
Renault, Christophe; Marchuk, Kyle; Ahn, Hyun S; Titus, Eric J; Kim, Jiyeon; Willets, Katherine A; Bard, Allen J
2015-06-02
We report a method to study electro-active defects in passivated electrodes. This method couples fluorescence microscopy and electrochemistry to localize and size electro-active defects. The method was validated by comparison with a scanning probe technique, scanning electrochemical microscopy. We used our method for studying electro-active defects in thin TiO2 layers electrodeposited on 25 μm diameter Pt ultramicroelectrodes (UMEs). The permeability of the TiO2 layer was estimated by measuring the oxidation of ferrocenemethanol at the UME. Blocking of current ranging from 91.4 to 99.8% was achieved. Electro-active defects with an average radius ranging between 9 and 90 nm were observed in these TiO2 blocking layers. The distribution of electro-active defects over the TiO2 layer is highly inhomogeneous and the number of electro-active defect increases for lower degree of current blocking. The interest of the proposed technique is the possibility to quickly (less than 15 min) image samples as large as several hundreds of μm(2) while being able to detect electro-active defects of only a few tens of nm in radius.
-
International Nuclear Information System (INIS)
Krecinic, F; Duc, T Chu; Sarro, P M; Lau, G K
2008-01-01
This paper presents simulation and experimental characterization of an electro-thermally actuated micro gripper. This micro actuator can conceptually be seen as a bi-morph structure of SU-8 and silicon, actuated by thermal expansion of the polymer. The polymer micro gripper with an embedded comb-like silicon skeleton is designed to reduce unwanted out-of-plane bending of the actuator, while offering a large gripper stroke. The temperature and displacement field of the micro gripper structure is determined using a two-dimensional finite element analysis. This analysis is compared to experimental data from steady-state and transient measurements of the integrated heater resistance, which depends on the average temperature of the actuator. The stability of the polymer actuator is evaluated by recording the transient behaviour of the actual jaw displacements. The maximum single jaw displacement of this micro gripper design is 34 µm at a driving voltage of 4 V and an average actuator temperature of 170 °C. The transient thermal response is modelled by a first-order system with a characteristic time constant of 11.1 ms. The simulated force capability of the device is 0.57 mN per µm jaw displacement
-
Directory of Open Access Journals (Sweden)
Marzieh Sedaghat
2015-09-01
Full Text Available Polyvinylidene fluoride (PVDF membranes are widely used in microfiltration and ultrafiltration processes for their excellent mechanical and chemical resistance and thermal stability in comparison with other polymeric membranes. Non-solvent induced phase separation (NIPS is the most important method by which the PVDF membranes are prepared. The structure of the membranes prepared by NIPS method depends on different parameters including the concentration of the polymer solution, polymer molecular weight, the composition and temperature of coagulation bath, type of solvent and the presence of additives in the initial solution. In the present work, the effects of coagulation bath temperature and LiCl content of the dope solution were studied with respect to the structure and performance of PVDF membranes. N-Methyl-2-pyrrolidone and water were used as solvent and coagulation bath, respectively. A set of analytical techniques including: scanning electron microscopy, mechanical test, pure water permeability and mean pore radius of pores was used to characterize the membranes. Moreover, the separation of humic acid, a main biological contaminant in surface water resources, was studied to determine membranes performance. The results show that at constant coagulation bath temperature, presence of LiCl in the dope solution increased the number as well as the mean pore radius of the pores at the surface of membranes and consequently, pure water permeability of the membranes was increased, whereas, the mechanical strength and humic acid rejection of the membranes were dropped. Moreover, at a constant content of LiCl, increasing the coagulation bath temperature decreased the size of macrovoids so that the mechanical strength as well as humic acid rejection of the membranes was increased.
-
Absorbed dose/melting heat dependence studies for the PVDF homopolymer
International Nuclear Information System (INIS)
Batista, Adriana S.M.; Gual, Maritza R.; Pereira, Claubia
2013-01-01
Differential Scanning Calorimetry (DSC) of gamma irradiated Poly (vinylidene Fluoride) [PVDF] homopolymer has been studied in connection with the use of material in industrial high gamma dose measurement. Interaction between gamma radiation and PVDF leads to the radio-induction of C=O and conjugated C=C bonds, as it can be inferred from previous infrared (FTIR) and ultraviolet-visible (UV-Vis) spectrometric data. These induced defects result in a decrease of the polymer crystallinity that can be followed with DSC scans, by measuring the latent heat during the melting transition (Hmelt). After a systematic investigation, we have found that Hmelt is unambiguously related to the delivered doses ranging from 100 to 2,000 kGy of gamma radiation. One the other hand, further fading investigation analysis has proved that the Hmelt x Dose relationship can be fitted by an exponential function that remains constant for several months. Both the very large range of dose measurement and also the possibility of evaluating high gamma doses until five months after irradiation make PVDF homopolymers very good candidates to be investigated as commercial high gamma dose dosimeters. The high gamma dose irradiation facilities in Brazil used to develop high dose dosimeters are all devoted to industrial and medical purposes. Therefore, in view of the uncertainties involved in the dose measurements related to the electronic equilibrium correction factors and backscattering in the isodose curves used at the irradiation setup, a validation process is required to correctly evaluate the delivered absorbed doses. The sample irradiations were performed with a Co-60 source, at 12kGy/h and 2,592 kGy/h, in the high gamma dose facilities at Centro de Desenvolvimento da Tecnologia Nuclear CDTN/CNEN, Belo Horizonte, Brazil. The comparison of the curve of the Hmelt vs Dose is presented in this paper. (author)
-
Near DC force measurement using PVDF sensors
Ramanathan, Arun Kumar; Headings, Leon M.; Dapino, Marcelo J.
2018-03-01
There is a need for high-performance force sensors capable of operating at frequencies near DC while producing a minimal mass penalty. Example application areas include steering wheel sensors, powertrain torque sensors, robotic arms, and minimally invasive surgery. The beta crystallographic phase polyvinylidene fluoride (PVDF) films are suitable for this purpose owing to their large piezoelectric constant. Unlike conventional capacitive sensors, beta crystallographic phase PVDF films exhibit a broad linear range and can potentially be designed to operate without complex electronics or signal processing. A fundamental challenge that prevents the implementation of PVDF in certain high-performance applications is their inability to measure static signals, which results from their first-order electrical impedance. Charge readout algorithms have been implemented which address this issue only partially, as they often require integration of the output signal to obtain the applied force profile, resulting in signal drift and signal processing complexities. In this paper, we propose a straightforward real time drift compensation strategy that is applicable to high output impedance PVDF films. This strategy makes it possible to utilize long sample times with a minimal loss of accuracy; our measurements show that the static output remains within 5% of the original value during half-hour measurements. The sensitivity and full-scale range are shown to be determined by the feedback capacitance of the charge amplifier. A linear model of the PVDF sensor system is developed and validated against experimental measurements, along with benchmark tests against a commercial load cell.
-
Directory of Open Access Journals (Sweden)
Kyungwho Choi
2017-01-01
Full Text Available In contrast to commercial piezoelectric ceramics, lead-free materials such as ZnO and a polymer matrix are proper candidates for use in ecofriendly applications. In this article, the authors represent a technique using ZnO nanowires with a polyvinylidene fluoride (PVDF matrix in a piezoelectric polymer composite. By aligning the nanowires in the matrix in a desired direction by AC dielectrophoresis, the piezoelectric behavior was enhanced. The dielectric constant of the composite was improved by increasing the concentration of the ZnO nanowires as well. Specifically, the resulting dielectric constant shows an improvement of 400% with aligned ZnO nanowires by increasing the poling effect compared to that of a randomly oriented nanowire composite without a poling process.
-
Kumaran, R.; Alagar, M.; Dinesh Kumar, S.; Subramanian, V.; Dinakaran, K.
2015-09-01
We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.
-
Directory of Open Access Journals (Sweden)
Rui Li
2017-08-01
Full Text Available Piezoelectric lead zirconatetitanate (PZT/polymer composites were prepared by two typical polymer matrixes using the hot-press method. The micromorphology, microstructure, dielectric properties, and piezoelectric properties of the PZT/polymer composites were characterized and investigated. The results showed that when the condition of frequency is 103 Hz, the dielectric and piezoelectric properties of PZT/poly(vinylidene fluoride were both better than that of PZT/polyvinyl chloride (PVC. When the volume fraction of PZT was 50%, PZT/PVDF prepared by the hot-press method had better comprehensive electric property.
-
Electro-optical properties of low viscosity driven holographic polymer dispersed liquid crystals
Moon, K. R.; Bae, S. Y.; Kim, B. K.
2015-04-01
Relative diffraction efficiency (RDE), operating voltage, and response times are most important performance characteristics of holographic polymer dispersed liquid crystals (HPDLC). Two types of triallyl isocyanurate (TI) having different structures were incorporated into the conventional transmission grating of HPDLC. Premix viscosity decreased by 13-18% with up to 3% TI, beyond which it increased. TI eliminated induction period and augmented initial grating formation rate at all contents. Saturation RDE increased over 200% while threshold voltage and rise time decreased to about half and 2/3, respectively up to 3% TI, beyond which the tendencies were reversed. Among the two TIs, low viscosity monomer (TA) showed high RDE, while high miscibility monomer (TE) low characteristic voltages and short response times. It is concluded that grating formation is largely favored by low viscosity, while interface tensions and electro-optical performances by miscibility at similar viscosities.
-
Surface Modifications of Polymers Induced by Heavy Ions Grafting
Energy Technology Data Exchange (ETDEWEB)
Mazzei, R O; Lombardo, J; Camporotondi, D; Tadey, D; Bermudez, G G [National Atomic Energy Commission, Ezeiza Atomic Centre, Ezeiza (Argentina)
2012-09-15
Polymer surfaces are modified by the application of swift heavy ions etching and grafting procedures. The residual active sites produced by heavy ion beams, remaining after the etching process, were used to start the grafting process. In order to produce tracks on foils of poly(vinylidene fluoride) (PVDF) they were irradiated with {sup 208}Pb of 25.62 MeV/n or with 115 MeV Cl ions. Moreover, foils of polypropylene (PP) were irradiated with {sup 208}Pb of 25.62 MeV/n. Then, they were etched and grafted with N-isopropylacrylamide (NIPAAm) monomers or with acrylic acid (AAc) monomers, respectively. The replica method allowed the observation of the shape of the grafted tracks using transmission electron microscopy (TEM). In addition NIPAAm grafted foils were analyzed using Fourier transform infrared spectroscopy (FTIR). The sulfonation procedure (methodology previously described for perfluorated polymers) was applied on grafted PVDF. A new method is described to produce a thin layer of poly-acrylic-acid (membranes) that grows on the surface of PVDF foils implanted by an Ar{sup +} beam with energies between 30-150 keV. Different combinations of monomers in water solutions were used such as: acrylic acid (AAc); acrylic acid-glycidyl methacrylate (AAc-GMA); acrylic acid-styrene (AAc-S); acrylic acid-N-isopropyl acrylamide (AAc-NIPAAm) and acrylic acid-N-isopropyl acrylamide - glycidyl methacrylate (AAc-NIPAAm-GMA). The experimental results show that for particular values of: ion fluence and energy, AAc concentration, sulphuric acid and PVDF polymorphous (alpha or beta) a huge percentage of grafting was obtained. At certain point of the grafting process the development of the PolyAAc-Xmonomer produce a detachment from the irradiated substrate and continue its grafting outside it. This method produces a membrane that is an increased replica of the original implanted surface. Finally, PVDF films implanted by an Ar{sup +} beam with energies about 100 keV and a fluence of 10
-
Rational design of organic electro-optic materials
International Nuclear Information System (INIS)
Dalton, L R
2003-01-01
Quantum mechanical calculations are used to optimize the molecular first hyperpolarizability of organic chromophores and statistical mechanical calculations are used to optimize the translation of molecular hyperpolarizability to macroscopic electro-optic activity (to values of greater than 100 pm V -1 at telecommunications wavelengths). Macroscopic material architectures are implemented exploiting new concepts in nanoscale architectural engineering. Multi-chromophore-containing dendrimers and dendronized polymers not only permit optimization of electro-optic activity but also of auxiliary properties including optical loss (both absorption and scattering), thermal and photochemical stability and processability. New reactive ion etching and photolithographic techniques permit the fabrication of three-dimensional optical circuitry and the integration of that circuitry with semiconductor very-large-scale integration electronics and silica fibre optics. Electro-optic devices have been fabricated exploiting stripline, cascaded prism and microresonator device structures. Sub-1 V drive voltages and operational bandwidths of greater than 100 GHz have been demonstrated. Both single-and double-ring microresonators have been fabricated for applications such as active wavelength division multiplexing. Free spectral range values of 1 THz and per channel modulation bandwidths of 15 GHz have been realized permitting single-chip data rates of 500 Gb s -1 . Other demonstrated devices include phased array radar, optical gyroscopes, acoustic spectrum analysers, ultrafast analog/digital converters and ultrahigh bandwidth signal generators. (topical review)
-
Energy Technology Data Exchange (ETDEWEB)
Jalarvo, N., E-mail: jalarvonh@ornl.gov, E-mail: abhijit.pramanick@gmail.com, E-mail: omardiallos@ornl.gov [Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, 52428 Jülich (Germany); Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Pramanick, A., E-mail: jalarvonh@ornl.gov, E-mail: abhijit.pramanick@gmail.com, E-mail: omardiallos@ornl.gov [Department of Physics and Materials Science, City University of Hong Kong, Kowloon (Hong Kong); Do, C. [Biology and Soft-Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Diallo, S. O., E-mail: jalarvonh@ornl.gov, E-mail: abhijit.pramanick@gmail.com, E-mail: omardiallos@ornl.gov [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
2015-08-24
We present a comparative study of proton dynamics in unpoled non-ferroelectric polymer polyvinylidene fluoride (PVDF) and in its trifluoroethylene containing ferroelectric copolymer (with 70/30 molar proportion), using quasi-elastic neutron scattering. The neutron data reveal the existence of two distinct types of molecular motions in the temperature range investigated. The slower motion, which is characterized in details here, is ascribed to protons jump diffusion along the polymeric carbon chains, while the faster motion could be attributed to localized rotational motion of methylene groups. At temperatures below the Curie point (T{sub c} ∼ 385 K) of the composite polymer, the slower diffusive mode experiences longer relaxation times in the ferroelectric blend than in the bare PVDF, although the net corresponding diffusion coefficient remains comparatively the same in both polymers with characteristic activation energy of E{sub A} ≈ 27–33 kJ/mol. This arises because of a temperature dependent jump length r{sub 0}, which we observe to be effectively longer in the copolymer, possibly due to the formation of ordered ferroelectric domains below T{sub c}. Above T{sub c}, there is no appreciable difference in r{sub 0} between the two systems. This observation directly relates the known dependence of T{sub c} on molar ratio to changes in r{sub 0}, providing fundamental insight into the ferroelectric properties of PVDF-based copolymers.
-
Characterization of Dielectric Electroactive Polymer transducers
DEFF Research Database (Denmark)
Nielsen, Dennis; Møller, Martin B.; Sarban, Rahimullah
2014-01-01
This paper analysis the small-signal model of the Dielectric Electro Active Polymer (DEAP) transducer. The DEAP transducer have been proposed as an alternative to the electrodynamic transducer in sound reproduction systems. In order to understand how the DEAP transducer works, and provide...
-
International Nuclear Information System (INIS)
Rajabi, Hamid; Ghaemi, Negin; Madaeni, Sayed S.; Daraei, Parisa; Khadivi, Mohammad Ali; Falsafi, Monir
2014-01-01
Highlights: • Nanocomposite membranes were prepared by addition of OMMT to PVDF membrane. • Addition of nanoclay considerably increased the hydrophilicity of PVDF membrane. • Nanocomposite membranes had higher water flux and antifouling properties. • Fouling of membranes blended with nanoclay (<4 wt.%) reduced. - Abstract: In this paper, nanocomposite PVDF/nanoclay membranes were prepared with addition of different concentrations of organically modified montmorillonite (OMMT) into the polymeric casting solution using combination of solution dispersion and phase inversion methods. Membranes were characterized by use of X-ray diffraction (XRD), water contact angle, scanning electron microscopy (SEM) and atomic force microscopy (AFM), and their performances were evaluated in terms of pure water flux and fouling parameters. The surface hydrophilicity of all nanocomposites markedly improved compared to nascent PVDF. In addition, XRD patterns revealed the formation of intercalated layers of mineral clays in PVDF matrix. SEM and AFM images showed that addition of OMMT resulted in nanocomposite membranes with thinner skin layer and higher porosity rather than PVDF membranes. Pure water flux of PVDF/OMMT membranes increased significantly (particularly for fabricated membranes by 4 and 6 wt.% OMMT) compared to that of PVDF membrane. Moreover, nanocomposite membranes showed the elevated antifouling properties, and flux recovery of nascent PVDF membranes increased from 51 to 72% with addition of 2 wt.% OMMT nanoparticles. These nanocomposite membranes also offered a remarkable reusability and durability against biofouling
-
Energy Technology Data Exchange (ETDEWEB)
Rajabi, Hamid [Membrane Research Centre, Department of Chemical Engineering, Razi University, Tagh Bostan, 67149 Kermanshah (Iran, Islamic Republic of); Department of Civil Engineering, Razi University, 67149 Kermanshah (Iran, Islamic Republic of); Ghaemi, Negin, E-mail: negin_ghaemi@kut.ac.ir [Department of Chemical Engineering, Kermanshah University of Technology, 67178 Kermanshah (Iran, Islamic Republic of); Madaeni, Sayed S. [Membrane Research Centre, Department of Chemical Engineering, Razi University, Tagh Bostan, 67149 Kermanshah (Iran, Islamic Republic of); Daraei, Parisa [Department of Chemical Engineering, Kermanshah University of Technology, 67178 Kermanshah (Iran, Islamic Republic of); Khadivi, Mohammad Ali [Friedrich-Alexander University, Erlangen-Nuremberg, Egerland Strasse 3, D-91058 Erlangen (Germany); Falsafi, Monir [Department of Chemistry, Faculty of Science, Razi University, 67149 Kermanshah (Iran, Islamic Republic of)
2014-09-15
Highlights: • Nanocomposite membranes were prepared by addition of OMMT to PVDF membrane. • Addition of nanoclay considerably increased the hydrophilicity of PVDF membrane. • Nanocomposite membranes had higher water flux and antifouling properties. • Fouling of membranes blended with nanoclay (<4 wt.%) reduced. - Abstract: In this paper, nanocomposite PVDF/nanoclay membranes were prepared with addition of different concentrations of organically modified montmorillonite (OMMT) into the polymeric casting solution using combination of solution dispersion and phase inversion methods. Membranes were characterized by use of X-ray diffraction (XRD), water contact angle, scanning electron microscopy (SEM) and atomic force microscopy (AFM), and their performances were evaluated in terms of pure water flux and fouling parameters. The surface hydrophilicity of all nanocomposites markedly improved compared to nascent PVDF. In addition, XRD patterns revealed the formation of intercalated layers of mineral clays in PVDF matrix. SEM and AFM images showed that addition of OMMT resulted in nanocomposite membranes with thinner skin layer and higher porosity rather than PVDF membranes. Pure water flux of PVDF/OMMT membranes increased significantly (particularly for fabricated membranes by 4 and 6 wt.% OMMT) compared to that of PVDF membrane. Moreover, nanocomposite membranes showed the elevated antifouling properties, and flux recovery of nascent PVDF membranes increased from 51 to 72% with addition of 2 wt.% OMMT nanoparticles. These nanocomposite membranes also offered a remarkable reusability and durability against biofouling.
-
Energy Technology Data Exchange (ETDEWEB)
Li Jianhua, E-mail: jhli_2005@163.com [Institute of Biomedical and Pharmaceutical Technology and College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350001 (China); Li Mizi; Miao Jing; Wang Jiabin; Shao Xisheng [Institute of Biomedical and Pharmaceutical Technology and College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350001 (China); Zhang Qiqing, E-mail: zhangqiq@126.com [Institute of Biomedical and Pharmaceutical Technology and College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350001 (China) and Institute of Biomedical Engineering, Chinese Academy of Medical Science, Peking Union Medical College, Tianjin 300192 (China)
2012-06-15
An attempt to improve hydrophilicity and anti-fouling properties of PVDF membranes, a novel amphiphilic zwitterionic copolymer poly(vinylidene fluoride)-graft-poly(sulfobetaine methacrylate) (PVDF-g-PSBMA) was firstly synthesized by atom transfer radical polymerization (ATRP) and used as amphiphilic copolymer additive in the preparation of PVDF membranes. The PVDF-g-PSBMA/PVDF blend membranes were prepared by immersion precipitation process. Fourier transform infrared attenuated reflection spectroscopy (FTIR-ATR) and X-ray photoelectronic spectroscopy (XPS) measurements confirmed that PSBMA brushes from amphiphilic additives were preferentially segregated to membrane-coagulant interface during membrane formation. The morphology of membranes was characterized by scanning electron microscopy (SEM). Water contact angle measurements showed that the surface hydrophilicity of PVDF membranes was improved significantly with the increasing of amphiphilic copolymer PVDF-g-PSBMA in cast solution. Protein static adsorption experiment and dynamic fouling resistance experiment revealed that the surface enrichment of PSBMA brush endowed PVDF blend membrane great improvement of surface anti-fouling ability.
-
International Nuclear Information System (INIS)
Li Jianhua; Li Mizi; Miao Jing; Wang Jiabin; Shao Xisheng; Zhang Qiqing
2012-01-01
An attempt to improve hydrophilicity and anti-fouling properties of PVDF membranes, a novel amphiphilic zwitterionic copolymer poly(vinylidene fluoride)-graft-poly(sulfobetaine methacrylate) (PVDF-g-PSBMA) was firstly synthesized by atom transfer radical polymerization (ATRP) and used as amphiphilic copolymer additive in the preparation of PVDF membranes. The PVDF-g-PSBMA/PVDF blend membranes were prepared by immersion precipitation process. Fourier transform infrared attenuated reflection spectroscopy (FTIR-ATR) and X-ray photoelectronic spectroscopy (XPS) measurements confirmed that PSBMA brushes from amphiphilic additives were preferentially segregated to membrane-coagulant interface during membrane formation. The morphology of membranes was characterized by scanning electron microscopy (SEM). Water contact angle measurements showed that the surface hydrophilicity of PVDF membranes was improved significantly with the increasing of amphiphilic copolymer PVDF-g-PSBMA in cast solution. Protein static adsorption experiment and dynamic fouling resistance experiment revealed that the surface enrichment of PSBMA brush endowed PVDF blend membrane great improvement of surface anti-fouling ability.
-
Energy Technology Data Exchange (ETDEWEB)
Silva, Agmar J.J.; Costa, Marysilvia F., E-mail: agmar@metalmat.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil)
2015-07-01
This work discuss firstly the effect of the ethanol fuel absorption by PVDF at 60°C through mass variation tests. A Fickian character was observed for the ethanol absorption kinetics of the aged PVDF at 60°C. In the second step, the dynamic mechanical thermal properties (E’, E’, E” and tan δ) of the PVDF were evaluated through dynamic mechanical thermal analysis (DMTA). The chemical structure of the materials was analyzed by X-ray diffraction analysis (XRD), and significant changes in the degree of crystallinity were verified after the aging. However, DMTA results showed a reduction in the storage modulus (E') of the aged PVDF, which was associated to diffusion of ethanol and swelling of the PVDF, which generated a prevailing plasticizing effect and led to reduction of its structural stiffness. (author)
-
Directory of Open Access Journals (Sweden)
U. Bunyatova
2016-07-01
Full Text Available This work presented a new approach to fabricate polymer nanocomposites films with nanofiber structures from solution blends of poly(vinyl alcohol + octadecyl amine-montmorillonite (ODA-MMT (matrix with poly(N-vinylpyrrolidone + ODA-MMT (partner-1, poly(N-vinylpyrrolidone-alt-maleic anhydride ((poly(VP-alt-MA + (ODA-MMT (partner-2 and their silver (Ag-carrying polymer complexes by electrospinning. Chemical and physical structures, surface morphologies, thermal behaviors, electrical conductivity and thermal resistance parameters of nanofiber structures were investigated. Poly(VP-alt-MA was used both as a crosslinker and a donor of the hydrophilic groups such as ‒COOH and ‒NH–C=O amide from pyrrolidone ring. Reactive poly(VP-alt-MA, in situ generated Ag nanoparticles (AgNPs and original partner polymer had an significant effect on the morphology and diameter distribution of nanofibers. High and excellent conductive behaviors were observed for the homopolymer and copolymer of VP based fiber structures, respectively. Upon successive chemical cross-linking of the nanofiber structures by reactive partner copolymer, the conductivity of nanofiber films as electro-active platforms dramatically increased to 3.90·10–2 S·cm–1 at room temperature. Comparative analysis results also indicated that electrical properties strongly depended on the loaded reactive organoclay and in situ generated AgNPs.
-
Polymer-ZnO nanocomposites foils and thin films for UV protection
International Nuclear Information System (INIS)
Shanshool, Haider Mohammed; Yahaya, Muhammad; Abdullah, Ibtisam Yahya; Yunus, Wan Mahmood Mat
2014-01-01
The damage of UV radiation on human eye and skin is extensively studied. In the present work, the nanocomposites foils and thin films have been prepared by using casting method and spin coating, respectively. Nanocomposites were prepared by mixing ZnO nanoparticles with Polymethyl methacrylate (PMMA) and Polyvinylidene fluoride (PVDF) as polymer matrix. Different contents of ZnO nanoparticles were used as filler in the nanocomposites. UV-Vis spectra showed very low transmittance in UV region that decreases with increase content of ZnO. PVDF/ZnO samples showed the lowest transmittance. The rough surface of PVDF was observed from SEM image. While a homogeneous dispersion of ZnO nanoparticles in PMMA were indicated by FESEM images
-
Polymer-ZnO nanocomposites foils and thin films for UV protection
Energy Technology Data Exchange (ETDEWEB)
Shanshool, Haider Mohammed; Yahaya, Muhammad; Abdullah, Ibtisam Yahya [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Yunus, Wan Mahmood Mat [Department of Physics, Faculty of Science, University Putra Malaysia, 43400 UPM, Serdang (Malaysia)
2014-09-03
The damage of UV radiation on human eye and skin is extensively studied. In the present work, the nanocomposites foils and thin films have been prepared by using casting method and spin coating, respectively. Nanocomposites were prepared by mixing ZnO nanoparticles with Polymethyl methacrylate (PMMA) and Polyvinylidene fluoride (PVDF) as polymer matrix. Different contents of ZnO nanoparticles were used as filler in the nanocomposites. UV-Vis spectra showed very low transmittance in UV region that decreases with increase content of ZnO. PVDF/ZnO samples showed the lowest transmittance. The rough surface of PVDF was observed from SEM image. While a homogeneous dispersion of ZnO nanoparticles in PMMA were indicated by FESEM images.
-
Chu, Baojin
Miniature of power electronics, scaling-down of microelectronics and other electrical and electronic systems, and development of many technologies (such as hybrid vehicles or implantable heart defibrillators) require capacitors with high energy density to improve the weight and volume efficiency of the whole system. Various capacitor technologies are investigated to meet the requirements of developing future technologies. Among these technologies, polymer film capacitor technology is one of the most promising. Besides high energy density, polymer-based capacitors possess the merits of high power density, low loss, high reliability (self-healing), easy processing, and feasibility (in size, shape and energy level). Due to the ferroelectricity of polyvinylidene fluoride (PVDF)-based polymers, they exhibit much higher polarization response under an electric field, in comparison with other linear dielectric polymers for capacitor applications. The maximum polarization level of PVDF-based polymers can be as high as 0.1 C/m2 and the breakdown field can be higher than 600 MV/m. An estimated energy density of around 30 J/cm3 can be expected in this class of materials. However, this value is much higher than the energy density that can be achieved in the PVDF homopolymer and the poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymers due to the polarization hysteresis in these polymers. Therefore, in this thesis, PVDF-based polymer materials were investigated and developed to approach this expected energy density by various strategies. An energy density of higher than 24 J/cm 3, which is close to the predicted value, was found in PVDF-based copolymers. Recently, the poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) terpolymer was developed in Prof. Qiming Zhang's group. Previous works have shown that incorporation of CTE into P(VDF-TrFE) copolymers, in which bulky CFE acts as a defect, could convert the copolymer into relaxor
-
Effects of Additives on the Morphology and Performance of PPTA/PVDF in Situ Blend UF Membrane
Directory of Open Access Journals (Sweden)
Hong-Bin Li
2014-06-01
Full Text Available Poly(p-phenylene terephtalamide (PPTA, a high-performance polymer with high modulus and good hydrophilicity, is often used as a reinforced material. However, due to its high crystallity, micro-phase separation often occurs in the blends. In this paper, PPTA/poly(vinylidene fluoride (PVDF compatible blend solution was synthesized by in situ polycondensation. Blend ultra-filtration membrane was prepared through the immersion phase inversion process. In order to obtain desired pore structure, the effects of different additives including hydrophilic polymer (polyethylene glycol (PEG, inorganic salt (lithium chloride (LiCl and the surfactant (Tween-80 on the morphology and performance of PPTA/PVDF blend membranes were studied. The membrane formation process was investigated through ternary phase diagram (thermodynamics and viscosities (kinetics analysis. It was found that, with the increasing of LiCl content, a porous membrane structure with long finger-like pores was formed due to the accelerated demixing process which resulted in the increase of porosity and pore diameter as well as the enhancement of water flux and the decline of PEG rejection. When Tween content increased to over 3 wt%, dynamic viscosity became the main factor resulting in a decreased phase separation rate. The transfer of PEG and LiCl molecules onto membrane surface increased the surface hydrophilicity. The effect of Tween content on membrane hydrophilicity was also correlated with the compatibility of blend components.
-
International Nuclear Information System (INIS)
Goto, Hiromasa
2014-01-01
Electrochemical synthesis in liquid crystal (LC) affords conducting polymers having LC molecular order and electro-activity. The polymerisation method can be referred to as structure organising polymerisation (SOP). The optical textures of the polymers thus prepared appear very similar to that of the LC electrolyte solution used for the polymerisation. Especially, polymers prepared in cholesteric LC (chiral LC) having structural chirality show doping-dedoping (redox) driven change in chiroptical activity (controllable circular dichroism and optical rotation), as e lectro-chiroptical effect . The polymer films exhibit interference colour and electrochemically driven refractive index modulations. The chiroptical activity of the polymer prepared in cholesteric LC comes from axial chirality of the helical structure
-
Lv, Jinling; Zhang, Guoquan; Zhang, Hanmin; Zhao, Chuanqi; Yang, Fenglin
2018-05-01
Hydrophilic cellulose nanocrystal (CNC) was incorporated into hydrophobic poly(vinylidene fluoride) (PVDF) membrane via phase inversion process to improve membrane antifouling property. The effects of CNC on membrane morphology, hydrophilicity, permeability and antifouling property were investigated in-detail. Results indicated that the introduction of CNC into PVDF membrane enhanced the permeability by optimizing membrane microstructure and improving membrane hydrophilicity. A higher pure water flux of 206.9 L m-2 h-1 was achieved for CNC/PVDF membrane at 100 kPa, which was 20 times that of PVDF membrane (9.8 L m-2 h-1). In bovine serum albumin filtration measurements, the permeation flux and flux recovery ratio of CNC/PVDF membrane were increased remarkably, while the irreversible fouling-resistance of CNC/PVDF membrane decreased by 48.8%. These results indicated that the CNC/PVDF membrane possessed superior antifouling property due to the hydrophilicity of CNC that formed a hydration layer on the membrane surface to effectively reduce contaminants adsorption/deposition.
-
Synthesis And Characterization of PVDF-LiBOB Electrolyte Membrane With ZrO2 As Additives
Directory of Open Access Journals (Sweden)
Etty Wigayati
2017-09-01
Full Text Available The electrolyte membrane serves as ions medium transport and as a separator between the anode and cathode in lithium ion battery. The polymer used for the electrolyte membrane must have sufficiently high mechanical strength to withstand the pressure between the anode and cathode, a thin size and has a chemical and thermal stability. Polymer electrolyte membrane of Lithium bisoxalate Borate(LiBOB salt with PVdF as matrix polymer and the additive is ZrO2 has been fabricated. The method used is a doctor blade. The concentration of the additive is varied. The membranes were characterized using FT-IR, XRD, SEM and EIS. XRD analysis showed that the crystallinity index increases with the addition of ZrO2. The presence of functional groups bewteen Lithium salts and polymer interaction shown by FTIR analysis. The morphology of the membrane surface was shown by SEM analysis. SEM image and mapping show the morphology of the membrane have typical porous layer. The electrical conductivity increases with additions of ZrO2.
-
Electro-synthesis of novel nanostructured PEDOT films and their application as catalyst support
Directory of Open Access Journals (Sweden)
Yan Yushan
2011-01-01
Full Text Available Abstract Poly(3,4-ethylenedioxythiophene (PEDOT films doped with nitric and chlorine ions have been electrochemically deposited simply by a one-step electrochemical method in an aqueous media in the absence of any surfactant. The fabricated PEDOT films were characterized by scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The results indicate that the hierarchical structured PEDOT film doped with nitric ions displays a 'lunar craters' porous morphology consisting of PEDOT nano-sheets with a thickness of less than 2 nm. The effect of counter ions on the electro-polymerization, the electrochemistry, and the morphology of the polymer film was studied. Compared with PEDOT film doped with nitric acid, PEDOT film deposited in the presence of chlorine ions shows irregular morphology and less electrochemical activity. The specific nanostructure of the polymer was further studied as catalyst support for platinum nanoparticles to methanol electro-oxidation.
-
Electro-thermal modelling of polymer lithium batteries for starting period and pulse power
Energy Technology Data Exchange (ETDEWEB)
Baudry, P. [Electricite de France DER, Site des Renardieres, Moret-sur-Loing (France); Neri, M. [Electricite de France DER, Site des Renardieres, Moret-sur-Loing (France); Gueguen, M. [Bollore Technologies, Odet, 29 Quimper (France); Lonchampt, G. [CEA/CEREM, CENG-85X, 38 Grenoble (France)
1995-04-01
Since power capabilities of solid polymer lithium batteries can only be delivered above 60 C, the thermal management in electric-vehicle applications has to be carefully considered. Electro-thermal modelling of a thermally insulated 200 kg battery was performed, and electrochemical data were obtained from laboratory cell impedance measurements at 20 and 80 C. Starting at 20 C as initial working temperature, the battery reaches 40 C after 150 s of discharge in a 0.5 {Omega} resistance. At 40 C, the useful peak power is 20 kW. The energy expense for heating the battery from 20 to 40 C is 1.4 kWh, corresponding to 6% of the energy available in the battery. After a stand-by period of 24 h, the temperature decreases from 80 to 50 C, allowing efficient starting conditions. (orig.)
-
Design of an Electro-Optic Modulator for High Speed Communications
Espinoza, David
The telecommunications and computer technology industries have been requiring higher communications speeds at all levels for devices, components and interconnected systems. Optical devices and optical interconnections are a viable alternative over other traditional technologies such as copper-based interconnections. Latency reductions can be achieved through the use of optical interconnections. Currently, a particular architecture for optical interconnections is being studied at the University of Colorado at Boulder in the EMT/NANO project, called Broadcast Optical Interconnects for Global Communication in Many-Core Chip Multiprocessor. As with most types of networks, including optical networks, one of the most important components are modulators. Therefore adequate design and fabrication techniques for modulators contribute to higher modulation rates which lead to improve the efficiency and reductions in the latency of the optical network. Electro-optical modulators are presented in this study as an alternative to achieve this end. In recent years, nonlinear optical (NLO) materials have been used for the fabrication of high-speed electro-optical modulators. Polymers doped with chromophores are an alternative among NLO materials because they can develop large electro-optic coefficients and low dielectric constants. These two factors are critical for achieving high-speed modulation rates. These polymer-based electro-optical modulators can be fabricated using standard laboratory techniques, such as polymer spin-coating onto substrates, UV bleaching to achieve a refractive index variation and poling techniques to align the chromophores in cured polymers. The design of the electro-optic modulators require the use of the optical parameters of the materials to be used. Therefore the characterization of these materials is a required previous step. This characterization is performed by the fabrication of chromophores-doped polymer samples and conducting transmission and
-
Origin of dielectric relaxor behavior in PVDF-based copolymer and terpolymer films
Pramanick, Abhijit; Osti, Naresh C.; Jalarvo, Niina; Misture, Scott T.; Diallo, Souleymane Omar; Mamontov, Eugene; Luo, Y.; Keum, Jong-Kahk; Littrell, Ken
2018-04-01
Relaxor ferroelectrics exhibit frequency-dispersion of their dielectric permittivity peak as a function of temperature, the origin of which has been widely debated. Microscopic understanding of such behavior for polymeric ferroelectrics has presented new challenges since unlike traditional ceramic ferroelectrics, dielectric relaxation in polymers is a consequence of short-range molecular dynamics that are difficult to measure directly. Here, through careful analysis of atomic-level H-atom dynamics as determined by Quasi-elastic Neutron Scattering (QENS), we show that short-range molecular dynamics within crystalline domains cannot explain the macroscopic frequency-dispersion of dielectric properties observed in prototypical polyvinylidene-fluoride (PVDF)-based relaxor ferroelectrics. Instead, from multiscale quantitative microstructural characterization, a clear correlation between the amount of crystalline-amorphous interfaces and dielectric relaxation is observed, which indicates that such interfaces play a central role. These results provide critical insights into the role of atomic and microscopic structures towards relaxor behavior in ferroelectric polymers, which will be important for their future design.
-
Origin of dielectric relaxor behavior in PVDF-based copolymer and terpolymer films
Directory of Open Access Journals (Sweden)
Abhijit Pramanick
2018-04-01
Full Text Available Relaxor ferroelectrics exhibit frequency-dispersion of their dielectric permittivity peak as a function of temperature, the origin of which has been widely debated. Microscopic understanding of such behavior for polymeric ferroelectrics has presented new challenges since unlike traditional ceramic ferroelectrics, dielectric relaxation in polymers is a consequence of short-range molecular dynamics that are difficult to measure directly. Here, through careful analysis of atomic-level H-atom dynamics as determined by Quasi-elastic Neutron Scattering (QENS, we show that short-range molecular dynamics within crystalline domains cannot explain the macroscopic frequency-dispersion of dielectric properties observed in prototypical polyvinylidene-fluoride (PVDF-based relaxor ferroelectrics. Instead, from multiscale quantitative microstructural characterization, a clear correlation between the amount of crystalline-amorphous interfaces and dielectric relaxation is observed, which indicates that such interfaces play a central role. These results provide critical insights into the role of atomic and microscopic structures towards relaxor behavior in ferroelectric polymers, which will be important for their future design.
-
Evaluation of ethanol aged PVDF: diffusion, crystallinity and dynamic mechanical thermal properties
International Nuclear Information System (INIS)
Silva, Agmar J.J.; Costa, Marysilvia F.
2015-01-01
This work discuss firstly the effect of the ethanol fuel absorption by PVDF at 60°C through mass variation tests. A Fickian character was observed for the ethanol absorption kinetics of the aged PVDF at 60°C. In the second step, the dynamic mechanical thermal properties (E’, E’, E” and tan δ) of the PVDF were evaluated through dynamic mechanical thermal analysis (DMTA). The chemical structure of the materials was analyzed by X-ray diffraction analysis (XRD), and significant changes in the degree of crystallinity were verified after the aging. However, DMTA results showed a reduction in the storage modulus (E') of the aged PVDF, which was associated to diffusion of ethanol and swelling of the PVDF, which generated a prevailing plasticizing effect and led to reduction of its structural stiffness. (author)
-
Nasef, M M
2003-01-01
The effects of electron beam irradiation on two partially fluorinated polymer films i.e. poly(vinylidene fluoride) (PVDF) and poly(ethylene-tetrafluoroethylene) copolymer (ETFE) are studied at doses ranging from 100 to 1200 kGy in air at room temperature. Chemical structure, thermal and mechanical properties of irradiated films are investigated. FTIR show that both PVDF and ETFE films undergo similar changes in their chemical structures including the formation of carbonyl groups and double bonding. The changes in melting and crystallisation temperatures (T sub m and T sub c) in both irradiated films are functions of irradiation dose and reflect the disorder in the chemical structure caused by the competition between crosslinking and chain scission. The heat of melting (DELTA H sub m) and the degree of crystallinity (X sub c) of PVDF films show no significant changes with the dose increase, whereas those of ETFE films are reduced rapidly after the first 100 kGy. The tensile strength of PVDF films is improved b...
-
International Nuclear Information System (INIS)
Syahidah, S. Nuur; Majid, S.R.
2013-01-01
This study reports on the fabrication and comparative performance characteristics of a symmetrical electrical double-layer capacitor (EDLC) employed gel polymer electrolyte (GPE) assembled between carbon based electrodes. Three cells, A, B and C were fabricated using different composition of active materials (activated or porous carbon), binder (PVdF-HFP) and conductivity enhancer (super-P). The configuration of cell A: 0.9 porous carbon/0.1 PVdF-HFP, cell B: 0.45 activated carbon/0.45 porous carbon/0.1 PVdF-HFP and cell C: 0.8 activated carbon/0.1 super-P/0.1 PVdF-HFP. The GPE, comprising a poly(vinyl pyrrolidone) (PVP)/poly(vinylidene fluoride co-hexafluoroproplyne) (PVdF-HFP) blend complexed with magnesium triflate, Mg(CF 3 SO 3 ) 2 , was prepared by the solution casting technique at 60 °C. The physico-chemical properties of the GPEs were characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), linear sweep voltammetry (LSV) and cyclic voltammetry (CV). The ionic conductivity at the ambient temperature of the GPE is 2.16 × 10 −4 S cm −1 at 7.5 wt.% of Mg(CF 3 SO 3 ) 2 with a ∼2.6 V electro-chemical stability window. At the 1000th cycle, the specific capacitance, C s of cell A is 89 F g −1 while cell B and C are 63 and 49 F g −1 . Cell A shows excellent long-term cyclic stability (less than a 5% decrease in specific capacitance after 1000 cycles). The best operating voltage for cell A is 1.6 V with the specific capacitance 106 F g −1 after 500 cycles
-
Indermun, S.; Choonara, Y.E.; Kumar, Pradeep; Toit, Du L.C.; Modi, G.; Luttge, R.; Pillay, V.
2014-01-01
This paper highlights the use of hydrogels in controlled drug delivery, and their application in stimuli responsive, especially electro-responsive, drug release. electro-conductive hydrogels (ECHs) displaying electro-responsive drug release were synthesized from semi-interpenetrating networks
-
A Study on Detection of Elastic Wave Using Patch Type Piezo-Polymer Sensor
International Nuclear Information System (INIS)
Kim, Ki Bok; Yoon, Dong Jin; Kueon, Jae Hwa; Lee, Young Seop
2004-01-01
Patch type piezo-polymer sensors for smart structures were experimented to detect elastic wave. The pencil lead braking test was performed to analyze the characteristics of patch-type piezo-polymer sensors such as polyvinyliden fluoride (PVDF) and polyvinylidene fluoride trifluorethylene (P(VDF-TrFE)) for several test specimens with various elastic wave velocities and acoustical impedances. The characteristics of the patch-type piezo-polymer sensor were compared with the commercial PZT acoustic emission (AE) sensor. The vacuum grease and epoxy resin were used as a couplant for the acoustic impedance matching between the sensor and specimen. The peak amplitude of elastic wave increased as the diameter of piezo-film and acoustical impedance of the specimen increased. The frequency detection range of the piezo-film sensors decreased with increasing diameter of the piezo-film sensor. The P(VDF-TrFE) sensor was more sensitive than the PVDF sensor
-
11. SIBEE: Brazilian symposium on electrochemistry and electro analytics
International Nuclear Information System (INIS)
1999-01-01
Theoretical and experimental papers are presented in these proceedings on the following subjects: fundamental electrochemistry, energy electrochemical conversion, electro catalysis, corrosion, polymers, molecular electrochemistry and bio electrochemistry
-
Structural, morphological and Raman studies on hybridized PVDF/BaTiO3 nanocomposites
Rajamanickam, N.; Jayakumar, K.; Ramachandran, K.
2017-05-01
Hybridized nanocomposites of polyvinylidene fluoride (PVDF) and nano - barium titanate (BaTiO3) were prepared using the solution casting method for different concentrations of nano-BaTiO3 and were characterized by X-ray diffraction and scanning electron microscopy. The flower like structure for morphology was observed in SEM. Raman analysis showed that the modified BaTiO3 particles, due to higher specific surfaces, induce, predominantly, the crystallization of the electrically active β-phase of PVDF, while the initial micron size particles induce the formation of the most common but non-polar α-crystal form.
-
Energy Technology Data Exchange (ETDEWEB)
Geraldes, Adriana N.; Zen, Heloisa A.; Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B.; Linardi, Marcelo [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: angeral@ipen.br
2007-07-01
Grafting of styrene onto polyvinylidenefluoride (PVDF), polytetrafluoroethylene (PTFE) was studied using styrene/toluene solutions. First, PTFE and PVDF films were prepared and the process was conducted by radiation induced graft polymerization of styrene, by a Co{sup 60} source. Films of PTFE and PVDF were immersed in styrene/toluene at 1:1 (v/v) concentration and then submitted to gamma radiation at 20 kGy doses. After irradiation, the samples were evaluated at the period of 21 days at room temperature in order to observe the grafting degree. Chemical changes in the PVDF and PTFE films after styrene grafting were monitored and the results were evaluated by FTIR, DSC, TGA and degree of grafting (DOG). The ion exchange capacity (IEC) after sulfonation of 1, 2 and 24 hours were also determined. (author)
-
Yun, Gyu-Young; Yun, Ki-Ju; Kim, Joo-Hyung; Kim, Jaehwan
2011-01-01
In order to understand the electro-mechanical behavior of piezoelectric electro active paper (EAPap), the converse and direct piezoelectric characterization of cellulose EAPap was studied and compared. A delay between the electrical field and the induced strain of EAPap was observed due to the inner nano-voids or the localized amorphous regions in layer-by-layered structure to capture or hold the electrical charges and remnant ions. The linear relation between electric field and induced strain is also observed. The electro-mechanical performance of EAPap is discussed in detail in this paper.
-
Sigamani, Nirmal Shankar
Both ionic and electronic electroactive polymers (EAPs) have displayed great potential as actuators. Current ionic EAPs have limited practical application due to their slow response time and their low blocked force; furthermore, their ion transport-based mechanism necessitates the presence of an electrolyte, which complicates issues of packaging and device lifetime. On the other hand, despite the advantages of electronic EAPs such as their efficient electromechanical coupling and relatively rapid response time, there are major obstacles blocking their transition to application as well; most notably, they require high actuation voltages (threshold voltage needed to generate electroactive strain) and they have low blocked stress (the stress at which the actuator stops moving). Hence, the main objective of this study was to develop a new kind of polymer nanocomposite for actuator applications that would exhibit simultaneous improvement in both electromechanical response and strain energy density. As a first step, we investigated the impact of the 2-dimensional GO and reduced GO on the electromechanical response of PVDF, a polar polymer. The 1 wt % reduced-GO-PVDF nanocomposites showed a tremendous improvement in dielectric permittivity and electrical conductivity. The dielectric permittivity at 1 KHz increased almost eight fold, while the electrical conductivity showed an increase of four orders of magnitude in comparison to the corresponding values for the unmodified PVDF. The reduced GO-PVDF polymer films showed a bending actuation response with a DC electric field, thus demonstrating its potential as EAP. The mechanism responsible for this bending actuation response is determined to be electrostriction, because the strain (S11) exhibited a quadratic response with the applied electric field while Joule heating and Maxwell stress effects were shown to be negligible. Although coefficient of electrostriction of reduced GO-PVDF is higher than most of the existing
-
Directory of Open Access Journals (Sweden)
Douglas M. Davenport
2016-01-01
Full Text Available Membranes are finding wide applications in various fields spanning biological, water, and energy areas. Synthesis of membranes to provide tunable flux, metal sorption, and catalysis has been done through pore functionalization of microfiltration (MF type membranes with responsive behavior. This methodology provides an opportunity to improve synthetic membrane performance via polymer fabrication and surface modification. By optimizing the polymer coagulation conditions in phase inversion fabrication, spongy polyvinylidene fluoride (PVDF membranes with high porosity and large internal pore volume were created in lab and full scale. This robust membrane shows a promising mechanical strength as well as high capacity for loading of adsorptive and catalytic materials. By applying surface modification techniques, synthetic membranes with different functionality (carboxyl, amine, and nanoparticle-based were obtained. These functionalities provide an opportunity to fine-tune the membrane surface properties such as charge and reactivity. The incorporation of stimuli-responsive acrylic polymers (polyacrylic acid or sodium polyacrylate in membrane pores also results in tunable pore size and ion-exchange capacity. This provides the added benefits of adjustable membrane permeability and metal capture efficiency. The equilibrium and dynamic binding capacity of these functionalized spongy membranes were studied via calcium ion-exchange. Iron/palladium catalytic nanoparticles were immobilized in the polymer matrix in order to perform the challenging degradation of the environmental pollutant trichloroethylene (TCE.
-
Electro-catalytic activity of Ni–Co-based catalysts for oxygen evolution reaction
Energy Technology Data Exchange (ETDEWEB)
Ju, Hua [School of Urban Rail Transportation, Soochow University, Suzhou 215006 (China); Li, Zhihu [College of Physics, Optoelectronics and Energy, Soochow University, Moye Rd. 688, Suzhou 215006 (China); Xu, Yanhui, E-mail: xuyanhui@suda.edu.cn [College of Physics, Optoelectronics and Energy, Soochow University, Moye Rd. 688, Suzhou 215006 (China)
2015-04-15
Graphical abstract: The electro-catalytic activity of different electro-catalysts with a porous electrode structure was compared considering the real electrode area that was evaluated by cyclic measurement. - Highlights: • Ni–Co-based electro-catalysts for OER have been studied and compared. • The real electrode area is calculated and used for assessing the electro-catalysts. • Exchange current and reaction rate constant are estimated. • Ni is more useful for OER reaction than Co. - Abstract: In the present work, Ni–Co-based electrocatalysts (Ni/Co = 0:6, 1:5, 2:4, 3:3, 4:2, 5:1 and 6:0) have been studied for oxygen evolution reaction. The phase structure has been analyzed by X-ray diffraction technique. Based on the XRD and SEM results, it is believed that the synthesized products are poorly crystallized. To exclude the disturbance of electrode preparation technology on the evaluation of electro-catalytic activity, the real electrode surface area is calculated based on the cyclic voltammetry data, assumed that the specific surface capacitance is 60 μF cm{sup −2} for metal oxide electrode. The real electrode area data are used to calculate the current density. The reaction rate constant of OER at different electrodes is also estimated based on basic reaction kinetic equations. It is found that the exchange current is 0.05–0.47 mA cm{sup −2} (the real surface area), and the reaction rate constant has an order of magnitude of 10{sup −7}–10{sup −6} cm s{sup −1}. The influence of the electrode potential on OER rate has been also studied by electrochemical impedance spectroscopy (EIS) technique. Our investigation has shown that the nickel element has more contribution than the cobalt; the nickel oxide has the best electro-catalytic activity toward OER.
-
Photodefinable electro-optic polymer for high-speed modulators
Balakrishnan, M.; Faccini, M.; Diemeer, Mart; Verboom, Willem; Driessen, A.; Reinhoudt, David; Leinse, Arne
2006-01-01
Direct waveguide definition of a negative photoresist (SU8) containing tricyanovinylidenediphenylaminobenzene (TCVDPA) as electro-optic (EO) chromophore, has been demonstrated for the first time. This was possible by utilising the chromophore low absorption window in the UV region allowing
-
The effect of electro-activation and eggshell powder on the neutralization of acid mine drainage
Directory of Open Access Journals (Sweden)
Alexey Kastyuchik
2017-01-01
Full Text Available Acid mine drainage (AMD production by sulfide mine tailing (SMT is a major environmental preoccupation because it can degrade water surface quality on account of its strong acidity and advanced content of sulfide, iron (Fe and other metals and metalloids. Acid neutralization and the precipitation of metals present in AMD were carried out by electro-activation with ion-exchange membranes, which is based on the self-generation of necessary conditions for acid neutralization and metal precipitation. The treatment of SMT was carried out by using an electro-activation cell generated alkaline solution in the cathode compartment. After 60 min of electro-activation, a pHcatholyte of 7.9–9.6, depending on the experimental conditions, was obtained. The absence of Fe and other trace metal ions in the catholyte provide evidence that the electro-activation of SMT promotes the precipitation of insoluble trace metals in the cathode compartment. This approach can be applied to real conditions in combination with a pretreatment of SMT neutralization, in which biological calcareous amendments are available. Finally, the electro-activation technology of acid mine drainage may be a feasible, cost-effective approach for SMT neutralization because it focuses on sustainable development.
-
Using PVDF for wavenumber-frequency analysis and excitation of guided waves
Ren, Baiyang; Cho, Hwanjeong; Lissenden, Cliff J.
2018-04-01
The role of transducers in nondestructive evaluation using ultrasonic guided waves cannot be overstated. Energy conversion from electrical to mechanical for actuation and then back to electrical for signal processing broadly describes transduction, but there are many other aspects of transducers that determine their effectiveness. Recently we have reported on polyvinylidene difluoride (PVDF) array sensors that enable determination of the wavenumber spectrum, which enables modal content in the received signal to be characterized. Modal content is an important damage indicator because, for example, mode conversion is a frequent consequence of wave interaction with defects. Some of the positive attributes of PVDF sensors are: broad frequency bandwidth, compliance for use on curved surfaces, limited influence on the passing wave, minimal cross-talk between elements, low profile, low mass, and inexpensive. The anisotropy of PVDF films also enables them to receive either Lamb waves or shear horizontal waves by proper alignment of the material principal coordinate axes. Placing a patterned set of electrodes on the PVDF film provides data from an array of elements. A linear array of elements is used to enable a 2D fast Fourier transform to determine the wavenumber spectrum of both Lamb waves and shear horizontal waves in an aluminum plate. Moreover, since PVDF film can sustain high voltage excitation, high power pulsers can be used to improve the signal-to-noise ratio. The capability of PVDF as a transmitter has been demonstrated with high voltage excitation.
-
PEGDA/PVdF/F127 gel type polymer electrolyte membranes for lithium secondary batteries
Energy Technology Data Exchange (ETDEWEB)
Wang, Yan-Jie; Kim, Dukjoon [Department of Chemical Engineering, Polymer Technology Institute, Sungkyunkwan University, Suwon, Kyunggi 440-746 (Korea)
2007-03-30
A novel porous gel polymer electrolyte (GPE) membrane based on poly(ethylene glycol) diacrylate (PEGDA), poly(vinylidene fluoride) (PVdF), and polyethylene oxide-co-polypropylene oxide-co-polyethylene oxide (PEO-PPO-PEO, F127) was fabricated by a phase inversion technique. The PEGDA cross-linking oligomer could be randomly mixed with unraveled PVdF polymer chains to form the interpenetrating polymer network (IPN) structure. Several experimental techniques including infrared (IR) spectra, differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and potentiostat/galvanostat were employed to investigate the characteristics of the polymer membranes. PEGDA and F127 influenced the porous size and structure. The mechanical strength and flexibility of the membrane were controlled by its composition. The membrane with the composition of PEGDA/PVdF/F127 (0/4/4) showed the highest electrolyte uptake of 152.6% and the maximum ionic conductivity of 2.0 x 10{sup -3} S cm{sup -1} at room temperature. All GPEs prepared in this study were electrochemically stable up to 4.5 V. (author)
-
Directory of Open Access Journals (Sweden)
Qian Li
2014-04-01
Full Text Available Based on a two-step polymerization method, two sulfobetaine-based zwitterionic monomers, including 3-(methacryloylamino propyl-dimethyl-(3-sulfopropyl ammonium hydroxide (MPDSAH and 2-(methacryloyloxyethyl ethyl-dimethyl-(3-sulfopropyl ammonium (MEDSA, were successfully grafted from poly(vinylidene fluoride (PVDF hollow fiber membrane surfaces in the presence of N,N′-methylene bisacrylamide (MBAA as a cross-linking agent. The mechanical properties of the PVDF membrane were improved by the zwitterionic surface layers. The surface hydrophilicity of PVDF membranes was significantly enhanced and the polyMPDSAH-g-PVDF membrane showed a higher hydrophilicity due to the higher grafting amount. Compared to the polyMEDSA-g-PVDF membrane, the polyMPDSAH-g-PVDF membrane showed excellent significantly better anti-protein-fouling performance with a flux recovery ratio (RFR higher than 90% during the cyclic filtration of a bovine serum albumin (BSA solution. The polyMPDSAH-g-PVDF membrane showed an obvious electrolyte-responsive behavior and its protein-fouling-resistance performance was improved further during the filtration of the protein solution with 100 mmol/L of NaCl. After cleaned with a membrane cleaning solution for 16 days, the grafted MPDSAH layer on the PVDF membrane could be maintain without any chang; however, the polyMEDSA-g-PVDF membrane lost the grafted MEDSA layer after this treatment. Therefore, the amide group of sulfobetaine, which contributed significantly to the higher hydrophilicity and stability, was shown to be imperative in modifying the PVDF membrane for a stable anti-protein-fouling performance via the two-step polymerization method.
-
Energy Technology Data Exchange (ETDEWEB)
Liu, Z.H. [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Center for Nanoscience & Nanotechnology, National Sun Yat-Sen University, Taiwan (China); National Science Council Core Facilities Laboratory for Nano-Science and Nano-Technology in Kaohsiung-Pingtung Area, Taiwan (China); Micro/Meso Mechanical Manufacturing R& D Department, Metal Industries Research and Development Centre, Kaohsiung 81160, Taiwan (China); Pan, C.T., E-mail: panct@mail.nsysu.edu.tw [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Center for Nanoscience & Nanotechnology, National Sun Yat-Sen University, Taiwan (China); National Science Council Core Facilities Laboratory for Nano-Science and Nano-Technology in Kaohsiung-Pingtung Area, Taiwan (China); Yen, C.K. [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Center for Nanoscience & Nanotechnology, National Sun Yat-Sen University, Taiwan (China); National Science Council Core Facilities Laboratory for Nano-Science and Nano-Technology in Kaohsiung-Pingtung Area, Taiwan (China); Lin, L.W. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Berkeley Sensor and Actuator Center, University of California, Berkeley, CA 94720 (United States); Huang, J.C. [Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Ke, C.A. [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China)
2015-08-15
Highlights: • Performance of the hollow cylindrical near-field electrospinning (HCNFES). • Well-aligned self-assembled PVDF nonwoven fiber fabrics. • Highly durable wearable sensors. • The mechanical characterization of HCNFES piezoelectric NFFs. • The formation of β-form extended-chain crystallites in the PVDF nanofibers. - Abstract: The mechanical characterization of the electrospinning polyvinylidene fluoride (PVDF) nonwoven fiber fabrics (NFFs) doped with multi-walled carbon nanotubes (MWCNTs) was investigated. Piezoelectric composite nanofibers of the PVDF/MWCNTs were directly electrospun by the hollow cylindrical near-field electrospinning (HCNFES) without any post-poling treatment. We have made the HCNFES NFFs consisted of high-orderly arranged nanofiber assemblies for further characterizing the effect of MWCNTs filling PVDF nanofibers. An in situ electrical poling and high uniaxial stretching imparted on the polymer jet during the HCNFES process, which naturally align the dipoles in the PVDF crystals and promote the formation of the polar β-crystalline phase within the fibers. Moreover, the reinforcement of the HCNFES PVDF nanofibers indicated the improvement in mechanical properties and the degree of high oriented extended-chain crystallites through adding adequate contents of MWCNTs. In the case of alignment of the all-trans polymer chains in the vicinity of MWCNTs along the fiber axis, X-ray diffraction (XRD) patterns showed the strongest diffraction peak of the β-crystalline phase. In the comparison of the near-field electrospinning (NFES), the HCNFES nanofibers with smooth surface and smaller diameter can easily form high density structural NFFs. After nano-indentation and tensile strength measurements, the results indicated that the mechanical properties of the HCNFES NFFs are better than the NFES ones. When 16 wt% PVDF solution doped with 0.03 wt% MWCNTs, the results reveal that Young's modulus, hardness, yield stress, yield strain
-
Electroassembly of smart polymer structures (role of polyelectrolytes)
Wallace, Gordon G.; Adeloju, Samuel B.; Shaw, Shannon J.
1997-02-01
Polymers are ubiquitous in nature, owing to their use as both structural and active components in dynamic, living systems. From a synthetic point of view man has utilized the excellent structural properties of polymers (light weight/high strength) for some decades now. However, the integration of active functional polymers into engineered systems and structures is a more recent endeavour with numerous challenges still to be overcome. Conducting electroactive polymers such as polypyrroles, polythiophenes and polyanilines are a fascinating group of functional polymers. They are electronic conductors and in addition they response to chemical or electrical stimuli in a number of ways. They are truly electrofunctional polymers. This unique combination of properties has led to the use of conducting polymers for electronic components, chemical sensors and biosensors, membranes for solution or gas separations, electromechanical actuators, electro-optical devices, biomaterials capable of controlled release of drugs or stimulation of biological processes, and for corrosion protection.
-
A review study of (bio)sensor systems based on conducting polymers.
Ates, Murat
2013-05-01
This review article concentrates on the electrochemical biosensor systems with conducting polymers. The area of electro-active polymers confined to different electrode surfaces has attracted great attention. Polymer modified carbon substrate electrodes can be designed through polymer screening to provide tremendous improvements in sensitivity, selectivity, stability and reproducibility of the electrode response to detect a variety of analytes. The electro-active films have been used to entrap different enzymes and/or proteins at the electrode surface, but without obvious loss of their bioactivity for the development of biosensors. Electropolymerization is a well-known technique used to immobilize biomaterials to the modified electrode surface. Polymers might be covalently bonding to enzymes or proteins; therefore, thickness, permeation and charge transport characteristics of the polymeric films can be easily and precisely controlled by modulating the electrochemical parameters for various electrochemical techniques, such as chronoamperometry, chronopotentiometry, cyclic voltammetry, and differential pulse voltammetry. This review article is divided into three main parts as given in the table of contents related to the immobilization process of some important conducting polymers, polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene), polycarbazole, polyaniline, polyphenol, poly(o-phenylenediamine), polyacetylene, polyfuran and their derivatives. A total of 216 references are cited in this review article. The literature reviewed covers a 7 year period beginning from 2005. Copyright © 2013 Elsevier B.V. All rights reserved.
-
Revathi, S; Kennedy, L John; Basha, S K Khadheer; Padmanabhan, R
2018-07-01
Nanostructured PbZr0.52Ti0.48O3 (PZT) powder was synthesized at 500 °C-800 °C using sol-gel route. X-ray diffraction and Rietveld analysis confirmed the formation of perovskite structure. The sample heat treated at 800 °C alone showed the formation of morphotropic phase boundary with coexistence of tetragonal and rhombohedral phase. The PZT powder and PVDF were used in 0-3 connectivity to form the PZT/PVDF composite film using solvent casting method. The composite films containing 10%, 50%, 70% and 80% volume fraction of PZT in PVDF were fabricated. The XRD spectra validated that the PZT structure remains unaltered in the composites and was not affected by the presence of PVDF. The scanning electron microscopy images show good degree of dispersion of PZT in PVDF matrix and the formation of pores at higher PZT loading. The quantitative analysis of elements and their composition were confirmed from energy dispersive X-ray analysis. The optical band gap of the PVDF film is 3.3 eV and the band gap decreased with increase in volume fraction of PZT fillers. The FTIR spectra showed the bands corresponding to different phases of PVDF (α, β, γ) and perovskite phase of PZT. The thermogravimetric analysis showed that PZT/PVDF composite films showed better thermal stability than the pure PVDF film and hydrophobicity. The dielectric constant was measured at frequency ranging from 1 Hz to 6 MHz and for temperature ranging from room temperature to 150 °C. The composite with 50% PZT filler loading shows the maximum dielectric constant at the studied frequency and temperature range with flexibility.
-
Poling of PVDF matrix composites for integrated structural load sensing
Haghiashtiani, Ghazaleh; Greminger, Michael A.; Zhao, Ping
2014-03-01
The purpose of this study is to create and evaluate a smart composite structure that can be used for integrated load sensing and structural health monitoring. In this structure, PVDF films are used as the matrix material instead of epoxy resin or other thermoplastics. The reinforcements are two layers of carbon fiber with one layer of Kevlar separating them. Due to the electrical conductivity properties of carbon fiber and the dielectric effect of Kevlar, the structure acts as a capacitor. Furthermore, the piezoelectric properties of the PVDF matrix can be used to monitor the response of the structure under applied loads. In order to exploit the piezoelectric properties of PVDF, the PVDF material must be polarized to align the dipole moments of its crystalline structure. The optimal condition for poling the structure was found by performing a 23 factorial design of experiment (DoE). The factors that were studied in DoE were temperature, voltage, and duration of poling. Finally, the response of the poled structure was monitored by exposing the samples to an applied load.
-
A method to modify PVDF microfiltration membrane via ATRP with low-temperature plasma pretreatment
Energy Technology Data Exchange (ETDEWEB)
Han, Yu [School of Marine Science, Ningbo University, Fenghua Road 818, Ningbo, 315211 (China); Ningbo University of Technology, Fenghua Road 201, Ningbo, 315211 (China); Song, Shuijun [School of Marine Science, Ningbo University, Fenghua Road 818, Ningbo, 315211 (China); Zhejiang University of Science Technology, Liuhe Road 318, Hangzhou, 310023 (China); Lu, Yin, E-mail: luyin@nbu.edu.cn [School of Marine Science, Ningbo University, Fenghua Road 818, Ningbo, 315211 (China); Zhu, Dongfa [School of Marine Science, Ningbo University, Fenghua Road 818, Ningbo, 315211 (China)
2016-08-30
Highlights: • We report a simple method to modify hydrophobic PVDF modification membrane. • Surface modification of PVDF membrane via ATRP with plasma pre-treatment. • ATRP grafting of SBMA onto the PVDF membrane surface form PVDF-g-SBMA membrane. • PVDF-g-SBMA membrane shows superior antifouling properties and hydrophilic. - Abstract: The hydrophilic modification of a polyvinylidene fluoride (PVDF) microfiltration membrane via pretreatment with argon plasma and direct surface-initiated atom transfer radical polymerization (ATRP) was studied. Both modified and unmodified PVDF membranes were characterized by Fourier transform infrared spectroscopy (FTIR), water contact angle, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and pore size distribution measurements. FTIR and XPS spectra confirmed that sulfobetaine methacrylate (SBMA) had been grafted onto the membrane surface. The initial contact angle decreased from 87.0° to 29.8° and a water drop penetrated into the modified membrane completely in 8 s. The pore size distribution of the modified membrane exhibited a smaller mean value than that of the original membrane. The antifouling properties of the modified PVDF membrane were evaluated by a filtration test using bovine serum albumin (BSA) solution. The results showed that the initial flux of the modified membrane increased from 2140.1 L/m{sup 2} h to 2812.7 L/m{sup 2} h and the equilibrium flux of BSA solution increased from 31 L/m{sup 2} h to 53 L/m{sup 2} h.
-
A method to modify PVDF microfiltration membrane via ATRP with low-temperature plasma pretreatment
International Nuclear Information System (INIS)
Han, Yu; Song, Shuijun; Lu, Yin; Zhu, Dongfa
2016-01-01
Highlights: • We report a simple method to modify hydrophobic PVDF modification membrane. • Surface modification of PVDF membrane via ATRP with plasma pre-treatment. • ATRP grafting of SBMA onto the PVDF membrane surface form PVDF-g-SBMA membrane. • PVDF-g-SBMA membrane shows superior antifouling properties and hydrophilic. - Abstract: The hydrophilic modification of a polyvinylidene fluoride (PVDF) microfiltration membrane via pretreatment with argon plasma and direct surface-initiated atom transfer radical polymerization (ATRP) was studied. Both modified and unmodified PVDF membranes were characterized by Fourier transform infrared spectroscopy (FTIR), water contact angle, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and pore size distribution measurements. FTIR and XPS spectra confirmed that sulfobetaine methacrylate (SBMA) had been grafted onto the membrane surface. The initial contact angle decreased from 87.0° to 29.8° and a water drop penetrated into the modified membrane completely in 8 s. The pore size distribution of the modified membrane exhibited a smaller mean value than that of the original membrane. The antifouling properties of the modified PVDF membrane were evaluated by a filtration test using bovine serum albumin (BSA) solution. The results showed that the initial flux of the modified membrane increased from 2140.1 L/m"2 h to 2812.7 L/m"2 h and the equilibrium flux of BSA solution increased from 31 L/m"2 h to 53 L/m"2 h.
-
Silitonga, Romaya Sitha; Widiastuti, Nurul; Jaafar, Juhana; Ismail, Ahmad Fauzi; Abidin, Muhammad Nidzhom Zainol; Azelee, Ihsan Wan; Naidu, Mahesan
2018-01-01
Poly(vinylidene fluoride) (PVDF) has outstanding properties such as high thermal stability, resistance to acid solvents and good mechanical strength. Due to its properties, PVDF is widely used as a membrane matrix. However, PVDF membrane is hydrophobic properties, so as for specific applications, the surface of membrane needs to be modified to become hydrophilic. This research aims to modify PVDF membrane surface with chitosan and glutaraldehyde as a crosslinker agent. The FTIR spectra showed...
-
Structural Changes of PVDF Membranes by Phase Separation Control
International Nuclear Information System (INIS)
Lee, Semin; Kim, Sung Soo
2016-01-01
Thermally induced phase separation (TIPS) and nonsolvent induced phase separation (NIPS) were simultaneously induced for the preparation of flat PVDF membranes. N-methyl-2-pyrrolidone (NMP) was used as a solvent and dibutyl-phthlate (DBP) was used as a diluent for PVDF. When PVDF was melt blended with NMP and DBP, crystallization temperature was lowered for TIPS and unstable region was expanded for NIPS. Ratio of solvent to diluent changed the phase separation mechanism to obtain the various membrane structures. Contact mode of dope solution with nonsolvent determined the dominant phase separation behavior. Since heat transfer rate was greater than mass transfer rate, surface structure was formed by NIPS and inner structure was by TIPS. Quenching temperature of dope solution also affected the phase separation mechanism and phase separation rate to result in the variation of structure
-
Wang, Shuai; Li, Tong; Chen, Chen; Chen, Sheng; Liu, Baicang; Crittenden, John
2018-03-01
Ultrafiltration (UF) membranes composed of poly(vinylidene fluoride) (PVDF) blended with poly(vinylidene fluoride)-graft-poly(ethylene glycol) methyl ether methacrylate (PVDF-g-PEGMA) can present high flux and excellent foulant removal efficiencies under suitable preparation conditions. However, these PVDF/PVDF-g-PEGMA blended membranes cannot be applied industrially because of the insufficient mechanical strength (strength-to-break value of 8.4 ± 0.6 MPa). We incorporated two types of non-woven polyethylene terephthalate (PET) fabrics (thin hydrophobic and thick hydrophilic fabrics) as support layers to improve the mechanical properties of the blended membranes. The thin and thick PET fabrics were able to significantly improve the tensile strength to 23.3 ± 3.7 MPa and 30.1 ± 1.4 MPa, respectively. The PET fabrics had a limited impact on the separation-related membrane performance such as hydrophilicity, foulant rejection, whereas the mechanical strength and pure water flux was improved several folds. The enhanced flux was attributed to the higher surface porosity and wider finger-like voids in the cross-section. The thin PET fabric with larger porosity was able to maintain a consistent toughness simultaneously; thus it is recommended as a support material for this blended membrane.
-
Directory of Open Access Journals (Sweden)
Faisal Abdulla AlMarzooqi
2017-02-01
Full Text Available Polyvinylidene fluoride (PVDF is a popular polymer material for making membranes for several applications, including membrane distillation (MD, via the phase inversion process. Non-solvent-induced phase separation (NIPS and vapor-induced phase separation (VIPS are applied to achieve a porous PVDF membrane with low mass-transfer resistance and high contact angle (hydrophobicity. In this work, firstly, the impacts of several preparation parameters on membrane properties using VIPS and NIPS were studied. Then, the performance of the selected membrane was assessed in a lab-scale direct-contact MD (DCMD unit. The parametric study shows that decreasing PVDF concentration while increasing both relative humidity (RH and exposure time increased the contact angle and bubble-point pore size (BP. Those trends were investigated further by varying the casting thickness. At higher casting thicknesses and longer exposure time (up to 7.5 min, contact angle (CA increased but BP significantly decreased. The latter showed a dominant trend leading to liquid entry pressure (LEP increase with thickness.
-
Enhanced methanol electro-oxidation reaction on Pt-CoOx/MWCNTs hybrid electro-catalyst
International Nuclear Information System (INIS)
Nouralishahi, Amideddin; Rashidi, Ali Morad; Mortazavi, Yadollah; Khodadadi, Abbas Ali; Choolaei, Mohammadmehdi
2015-01-01
Highlights: • Promoting effects of Cobalt oxide on methanol electro-oxidation over Pt/MWCNTs are investigated. • Higher activity, about 2.9 times, and enhanced stability are observed on Pt-CoO x /MWCNTs. • Electrochemical active surface area of Pt nanoparticles is significantly improved upon CoO x addition. • Bi-functional mechanism is facilitated in presence of CoO x . - Abstract: The electro-catalytic behavior of Pt-CoO x /MWCNTs in methanol electro-oxidation reaction (MOR) is investigated and compared to that of Pt/MWCNTs. The electro-catalysts were synthesized by an impregnation method using NaBH 4 as the reducing agent. The morphological and physical characteristics of samples are examined by XRD, TEM, ICP and EDS techniques. In the presence of CoO x , Pt nanoparticles were highly distributed on the support with an average particle size of 2 nm, an obvious decrease from 5.1 nm for Pt/MWCNTs. Cyclic voltammetry, CO-stripping, Chronoamperometry, and electrochemical impedance spectroscopy (EIS) measurements are used to study the electrochemical behavior of the electro-catalysts. The results revealed a considerable enhancement in the oxidation kinetics of CO ads on Pt active sites by the participation of CoO x . Compared to Pt/MWCNTs, Pt-CoO x /MWCNTs sample has a larger electrochemical active surface area (ECSA) and higher electro-catalytic activity and stability toward methanol electro-oxidation. According to the results of cyclic voltammetry, the forward anodic peak current density enhances more than 89% at the optimum atomic ratio of Pt:Co = 2:1. Furthermore, inclusion of cobalt oxide species causes the onset potential of methanol electro-oxidation reaction to shift 84 mV to negative values compared to that on Pt/MWCNTs. Based on EIS data, dehydrogenation of methanol is the rate-determining step of MOR on both Pt/MWCNTs and Pt-CoO x /MWCNTs, at small overpotentials. However, at higher overpotentials, the oxidation of adsorbed oxygen-containing groups
-
Prateek; Thakur, Vijay Kumar; Gupta, Raju Kumar
2016-04-13
Dielectric polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. In this Review, we present a comprehensive review of the use of ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications. Various parameters like dielectric constant, dielectric loss, breakdown strength, energy density, and flexibility of the polymer nanocomposites have been thoroughly investigated. Fillers with different shapes have been found to cause significant variation in the physical and electrical properties. Generally, one-dimensional and two-dimensional nanofillers with large aspect ratios provide enhanced flexibility versus zero-dimensional fillers. Surface modification of nanomaterials as well as polymers adds flavor to the dielectric properties of the resulting nanocomposites. Nowadays, three-phase nanocomposites with either combination of fillers or polymer matrix help in further improving the dielectric properties as compared to two-phase nanocomposites. Recent research has been focused on altering the dielectric properties of different materials while also maintaining their superior flexibility. Flexible polymer nanocomposites are the best candidates for application in various fields. However, certain challenges still present, which can be solved only by extensive research in this field.
-
Kareb, Ourdia; Gomaa, Ahmed; Champagne, Claude P; Jean, Julie; Aïder, Mohammed
2017-04-15
Electro-activation was used to add value to sweet defatted whey. This study aimed to investigate and to characterize the bioactive compounds formed under different electro-activation conditions by molecular and proteomic approaches. The effects of electric current intensity (400, 500 or 600mA) and whey concentration (7, 14 or 21% (w/v)) as a function of the electro-activation time (0, 15, 30 or 45min) were evaluated. The targeted dependent variables were the formation of Maillard reaction products (MRPs), protein hydrolysates and glycated compounds. It was shown that the MRPs derived from electro-activated whey at a concentration of 14% had the highest potential of biological activity. SDS-PAGE analyses indicated the formation of hydrolysates and glycated compounds with different molecular weight distributions. FTIR indicated the predominance of intermediate MRPs, such as the Schiff base compounds. LC-MS/MS and proteomics analysis showed the production of multi-functional bioactive peptides due to the hydrolysis of whey proteins. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.
-
Dong, Li; Liu, Xiangdong; Xiong, Zhengrong; Sheng, Dekun; Lin, Changhong; Zhou, Yan; Yang, Yuming
2018-06-01
We first reported a strategy to prepare functional poly(vinylidene fluoride) (PVDF) membranes with excellent ultraviolet-absorbing property through chemically induced grafting. Herein, the polymerizable ultraviolet (UV) absorber 2-hydroxy-4-(3-methacryloxy-2-hydroxylpropoxy) benzophenone (BPMA) made by ourselves was grafted onto the PVDF chains that have been pretreated with tetraethylammonium hydroxide (TEAH) alkaline solution. Moreover, the effect of experiment conditions such as the alkali and monomer concentrations, alkali treatment time on the UV-absorbing property of the obtained PVDF-g-PBPMA membranes were studied in detail. The chemical structure of the modified membranes was confirmed by 1H NMR, FT-IR and XPS measurements. Meanwhile, the thermal and UV-absorbing properties were characterized by TGA, DSC and UV-Vis spectrophotometer, respectively. The results indicated that BPMA side chains were successfully introduced onto PVDF backbones. Most importantly, the obtained PVDF-g-PBPMA membranes exhibited excellent UV-absorbing property. The transmittance of UV light at 300 nm decreased to as low as 0.02% and the UV light below 388 nm could be completely absorbed by the PVDF-g-PBPMA membrane made under optimal condition.
-
Improvement of β-phase crystal formation in a BaTiO3-modified PVDF membrane
Lin, SHEN; Lei, GONG; Shuhua, CHEN; Shiping, ZHAN; Cheng, ZHANG; Tao, SHAO
2018-04-01
In this paper, low temperature plasma is used to modify the surface of barium titanate (BaTiO3) nanoparticles in order to enhance the interfacial compatibility between ferroelectric poly(vinylidene fluoride) (PVDF) and BaTiO3 nanoparticles. The results demonstrate that oxygenic groups are successfully attached to the BaTiO3 surface, and the quantity of the functional groups increases with the treatment voltage. Furthermore, the effect of modified BaTiO3 nanoparticles on the morphology and crystal structure of the PVDF/BaTiO3 membrane is investigated. The results reveal that the dispersion of BaTiO3 nanoparticles in the PVDF matrix was greatly improved due to the modification of the BaTiO3 nanoparticles by air plasma. It is worth noting that the formation of a β-phase in a PVDF/modified BaTiO3 membrane is observably promoted, which results from the strong interaction between PVDF chains and oxygenic groups fixed on the BaTiO3 surface and the better dispersion of BaTiO3 nanoparticles in the PVDF matrix. Besides, the PVDF/modified BaTiO3 membrane at the treatment voltage of 24 kV exhibits a lower water contact angle (≈68.4°) compared with the unmodified one (≈86.7°). Meanwhile, the dielectric constant of PVDF/BaTiO3 nanocomposites increases with the increase of working voltage.
-
Nair, Manjula G.; Malakar, Meenakshi; Mohapatra, Saumya R.; Chowdhury, Avijit
2018-05-01
This research reports the observation of bipolar resistive switching memory in ZnO nanorod based polymer nanocomposites. We synthesized ZnO nanorods by wet-chemical method and characterized them using XRD, UV-VIS spectroscopy and SEM. The synthesized materials have hexagonal ZnO phase with grain size of 24 nm and having strong orientation along (101) direction as observed from XRD. The SEM micrograph confirms the formation of ZnO nanorods with diameter in the range of 10 to 20 nm and length of the order of 1 µm. From optical absorption spectra the band gap is estimated to be 2.42 eV. ZnO nanorods were dispersed in PVDF-HFP polymer matrix to prepare the nanocomposite. This nanocomposite was used as active layer in the devices having sandwich structure of ITO/PVDF-HFP+ZnO nanorods/Al. Bipolar non-volatile memory was observed with ON-OFF resistance ratio of the order of 103 and with a wide voltage window of 2.3V. The switching mechanism could be due to the trapping and de-trapping of electrons by the ZnO nanorods in the nanocomposite during ON and OFF states respectively.
-
Preparation and characterization of the PVDF-based composite membrane for direct methanol fuel cells
Qian Liu, Laizhou Song, Zhihui Zhang, Xiaowei Liu
2010-01-01
The polyvinylidene fluoride-sulfonated polystyrene composite membrane with proton exchange performance, denoted as PVDF-SPS, was prepared using a thermally induced polymerization technique. The thermal stability of the PVDF-SPS composite membrane was investigated using thermogravimetric (TG) analysis. The complex formation of the composite membrane was ascertained by Fourier transform infrared spectroscopy (FTIR). The surface compositions of the PVDF-SPS membrane were analyzed using X-ray pho...
-
Energy Technology Data Exchange (ETDEWEB)
Das, Arindam; Raffi, Muhammad; Megaridis, Constantine, E-mail: cmm@uic.edu [University of Illinois at Chicago, Department of Mechanical and Industrial Engineering (United States); Fragouli, Despina [Istituto Italiano di Tecnologia, Smart Materials, Nanophysics (Italy); Innocenti, Claudia [Universita di Firenze, INSTM Research Unit and Department of Chemistry (Italy); Athanassiou, Athanassia [Istituto Italiano di Tecnologia, Smart Materials, Nanophysics (Italy)
2015-01-15
A mild-temperature, nonchemical technique is used to produce a nanohybrid multifunctional (electro-conducting and magnetic) powder material by intercalating iron oxide nanoparticles in large aspect ratio, open-ended, hollow-core carbon nanofibers (CNFs). Single-crystal, superparamagnetic Fe{sub 3}O{sub 4} nanoparticles (10 nm average diameter) filled the CNF internal cavity (diameter <100 nm) after successive steps starting with dispersion of CNFs and magnetite nanoparticles in aqueous or organic solvents, sequencing or combining sonication-assisted capillary imbibition and concentration-driven diffusion, and finally drying at mild temperatures. The influence of several process parameters—such as sonication type and duration, concentration of solids dispersed in solvent, CNF-to-nanoparticle mass ratio, and drying temperature—on intercalation efficiency (evaluated in terms of particle packing in the CNF cavity) was studied using electron microscopy. The magnetic CNF powder was used as a low-concentration filler in poly(methyl methacrylate) to demonstrate thin free-standing polymer films with simultaneous magnetic and electro-conducting properties. Such films could be implemented in sensors, optoelectromagnetic devices, or electromagnetic interference shields.
-
Lai, Wei-Chi; Tseng, Shen-Jhen; Huang, Po-Hsun
2015-11-01
We report a method for tuning the nanoarchitectures of 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol (DMDBS) with poly(vinylidene fluoride) (PVDF) polymer matrices. Hydrophobic PVDF facilitated the formation of nanofibrils during heating. The self-assembly behaviors of DMDBS were further tuned by altering the different heat treatments. When the samples were prepared with a rapid heating rate (shorter annealing time), smaller amounts of melted PVDF were excluded due to the shorter time for aggregation of DMDBS, leading to larger complex structures of DMDBS and PVDF. Therefore, longer and thicker nanofibrils (around 100 nm) were observed using scanning electron microscopy. As the samples were prepared with a slow heating rate (longer annealing time), DMDBS had more time to aggregate, and therefore, larger amounts of melted PVDF were excluded. Smaller complex structures of DMDBS and PVDF caused the formation of shorter and thinner nanofibrils (around 40 nm). In addition, small-angle X-ray scattering results indicated that the longer and thicker nanofibrils were mostly excluded outside the PVDF crystalline bundles after cooling because they were too large to be easily incorporated between the PVDF crystalline lamellae. However, a large portion of the smaller and thinner nanofibrils was trapped between the crystalline lamellae after cooling due to their smaller sizes. As expected, the PVDF spherulitic morphologies were affected, but the PVDF crystalline microstructures were not significantly altered by the addition of DMDBS, as shown by the results from polarized optical microscopy and Fourier transform infrared spectroscopy.
-
Aligned carbon nanotube with electro-catalytic activity for oxygen reduction reaction
Liu, Di-Jia; Yang, Junbing; Wang, Xiaoping
2010-08-03
A catalyst for an electro-chemical oxygen reduction reaction (ORR) of a bundle of longitudinally aligned carbon nanotubes having a catalytically active transition metal incorporated longitudinally in said nanotubes. A method of making an electro-chemical catalyst for an oxygen reduction reaction (ORR) having a bundle of longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes, where a substrate is in a first reaction zone, and a combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas is introduced into the first reaction zone which is maintained at a first reaction temperature for a time sufficient to vaporize material therein. The vaporized material is then introduced to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes over the substrate with a catalytically active transition metal incorporated throughout the nanotubes.
-
Electro-Optical Characterization of Bistable Smectic A Liquid Crystal Displays
Buyuktanir, Ebru Aylin
My dissertation focuses the characterization and optimization of the electro-optical properties of smectic A (SmA) based liquid crystal (LC) displays. I present the development of robust and flexible bistable SmA LC displays utilizing polymer dispersed liquid crystal (PDLC) technology. The SmA PDLC displays produced on plastic substrates present electrically reversible memory, high contrast ratio, paper-like sunlight readability, and wide viewing angle characteristics. In order to optimize the SmA PDLC display, I investigated polymerization conditions, such as polymer concentration effect, polymerization temperature, and UV-light intensity variations. I characterized the electro-optical responses-such as static-response, time-response, threshold characteristics, and contrast ratio values' of the optimized SmA PDLC display and compared them to those of the pure SmA LC. The best electro-optical performance of SmA PDLC formulation was obtained using the combination of low mW/cm 2 and high mW/cm2 UV-light curing intensity. The contrast ratio of the optimum SmA PDLC at a 5o collection angle was 83% of that of the pure SmA material on plastic substrates. I fabricated 2.5 x 2.5 in., 4 x 4 in., and 6 x 6 in. sized monochrome flexible SmA PDLC displays, as well as red, yellow, and fluorescent dyes colored SmA PDLC displays on plastic substrates. The electro-optic performance of the bistable SmA LC display consisting of a patterned field-induced polymer wall infrastructure was also studied and compared to those of pure SmA material. I found that the contrast ratio of the SmA LC encapsulated between polymer walls was much greater than that of the SmA PDLC system, approaching the contrast ratio value of the pure SmA material. I also improved the electro-optical characteristics of bistable SmA LC displays by adding ferroparticles into the system. Finally, I illustrated the unique capabilities of polarized confocal Raman microscopy (CRM) to resolve the orientational order of Sm
-
Sabira, K.; Saheeda, P.; Divyasree, M. C.; Jayalekshmi, S.
2017-12-01
In the present work, the nonlinear optical properties of free-standing films of Poly(vinylidene fluoride) (PVDF)/reduced graphene oxide (RGO) nanocomposite are investigated to assess their suitability as efficient optical limiters. The PVDF/RGO nanocomposite films are generated by mixing different concentrations of RGO as the filler, with PVDF, using solution casting method. The XRD and FTIR data of these nanocomposite films confirm the enhancement in the β phase of PVDF when RGO is added to PVDF, which is one of the prime factors, enhancing the nonlinear response of the nanocomposite. The open aperture and closed aperture Z-scan technique under nanosecond excitation (532 nm, 7 ns) is used to investigate the nonlinear optical characteristics of the PVDF/RGO nanocomposite films. These films are found to exhibit two photon absorption assisted optical non linearity in the nanosecond regime. The highlight of the present work is the observation of quite low values of the normalized transmittance and low optical limiting threshold power in free standing films of PVDF/RGO nanocomposite. These flexible, free-standing and stable nanocomposite films offer high application prospects in the design of efficient optical limiting devices of any desired size or shape.
-
Kirigami-based PVDF thin-film as stretchable strain sensor
Hu, Nan; Chen, Dajing; Hao, Nanjing; Huang, Shicheng; Yu, Xiaojiao; Zhang, John X. J.; Chen, Zi
Kirigami, as the sister of the origami, involves cutting of 2D sheets to form complex 3D geometries with out-of-plane patterns. Motivated by the development of the high-stretchable biomedical devices, we explore the stretchability of the kirigami-based PVDF thin film under tension. Our structural prototypes include a set of 2D geometry with kirigami-based pattern cutting on PVDF thin films. We first used paper models to generate a wide range of cutting patterns to study the deformation under compression tests, the results of which are compared with finite element simulations. We then proceeded to test different kirigami-based designs to identify geometric parameters that can tune the post-buckling response and strain distribution. Next, we fabricated and tested the PVDF thin film with kirigami pattern. Experiments showed that the PVDF film in the absence of cutting can be stretched to a limited extent and will break upon further stretching. In contrast, the kirigami-based films can be stretched up to 100% without failure. Our designs demonstrate the ability to significantly improve the strain range of the structure and sensing ability of a sensor. We envision a promising future to use this class of structural elements to develop highly stretchable materials, structures, and devices. Z.C. acknowledges the Society in Science-Branco Weiss fellowship, administered by ETH Zürich. J.X.J.Z. acknowledges the NIH Director's Transformative Research Award (1R01 OD022910-01).
-
Tan, Zhongyang; Wang, Xuemei; Fu, Chao; Chen, Chunhai; Ran, Xianghai
2018-03-01
In this study, we successfully prepared the pure PVDF film containing almost exclusive γ-phase (γ-PVDF) using 15 wt% solution in N, N-dimethylformamide. These γ-PVDF films were irradiated by 3.0 MeV electron beam in vacuum at room temperature up to 358 kGy. The effect of the irradiation on the chemical structural and thermal properties of pristine and irradiated γ-PVDF films were detailedly investigated by FTIR, XRD and DSC, respectively. DSC results show that two single and different melting endotherms from the successive heating curves correspond to γ-phase and α-phase, respectively. FTIR results show that the characteristic absorption peaks corresponding to γ-phase do not shift, and the C˭C bond formation is not significantly observed in the irradiated γ-PVDF films until above 30 kGy. XRD results show that the crystal form of γ-PVDF is not influenced significantly by irradiation. All PVDF films exhibit a single melting endotherm, irrespective of the irradiation dose. Two superpositioned crystallization peaks were observed for PVDF films only irradiated at high dose of 232 and 358 kGy, which can be related to the fractionated crystallization of irradiated PVDF. The dependences of thermal characteristics on the irradiation dose were detailedly investigated by DSC in this study.
-
International Nuclear Information System (INIS)
Saito, Masaaki; Imaizumi, Hiroshi; Kato, Norio; Ishii, Yoshiyuki; Saito, Keiichi
2010-01-01
Anomalies in tritium enrichment cannot be explained only by isotopic effects in water electrolysis. The temperature dependence of the enrichment factor had been reported as increasing with 1/T. However, the increase was difficult to explain on the basis of kinetics. In this study, electro-osmotic drag (EOD, number of water molecule accompanied by a proton) and tritium enrichment ratio were investigated using light water (H 2 O) and heavy water (D 2 O) by solid polymer electrolysis. The EOD decreased and tritium enrichment ratio increased at low temperature for H 2 O. Electrolysis showed no temperature dependence for D 2 O. It was revealed that proton hopping by a hydrogen bond network of water molecules (the Grotthuss mechanism) affects the temperature dependence of EOD and tritium enrichment in the case of H 2 O. (author)
-
Iwagoshi, Joel A.
Research on alternative energies has become an area of increased interest due to economic and environmental concerns. Green energy sources, such as ocean, wind, and solar power, are subject to predictable and unpredictable generation intermittencies which cause instability in the electrical grid. This problem could be solved through the use of short term energy storage devices. Capacitors made from composite polymer:nanoparticle thin films have been shown to be an economically viable option. Through thermal vapor deposition, we fabricated dielectric thin films composed of the polymer polyvinylidine fluoride (PVDF) and the ceramic nanoparticle titanium dioxide (TiO2). Fully understanding the deposition process required an investigation of electrode and dielectric film deposition. Film composition can be controlled by the mass ratio of PVDF:TiO2 prior to deposition. An analysis of the relationship between the ratio of PVDF:TiO2 before and after deposition will improve our understanding of this novel deposition method. X-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy were used to analyze film atomic concentrations. The results indicate a broad distribution of deposited TiO2 concentrations with the highest deposited amount at an initial mass concentration of 17% TiO2. The nanoparticle dispersion throughout the film is analyzed through atomic force microscopy and energy dispersive x-ray spectroscopy. Images from these two techniques confirm uniform TiO2 dispersion with cluster size less than 300 nm. These results, combined with spectroscopic analysis, verify control over the deposition process. Capacitors were fabricated using gold parallel plates with PVDF:TiO 2 dielectrics. These capacitors were analyzed using the atomic force microscope and a capacohmeter. Atomic force microscope images confirm that our gold films are acceptably smooth. Preliminary capacohmeter measurements indicate capacitance values of 6 nF and break down voltages of 2.4 V
-
Zuo, Jian; Chung, Neal Tai-Shung
2016-01-01
A novel and effective one-step method has been demonstrated to fabricate cross-linked polyvinylidene fluoride (PVDF) membranes with better mechanical properties and flux for seawater desalination via vacuum membrane distillation (VMD). This method involves the addition of two functional nonsolvent additives; namely, water and ethylenediamine (EDA), into the polymer casting solution. The former acts as a pore forming agent, while the latter performs as a cross-linking inducer. The incorporation of water tends to increase membrane flux via increasing porosity and pore size but sacrifices membrane mechanical properties. Conversely, the presence of EDA enhances membrane mechanical properties through in-situ cross-linking reaction. Therefore, by synergistically combining the effects of both functional additives, the resultant PVDF membranes have shown good MD performance and mechanical properties simultaneously. The parameters that affect the cross-link reaction and membrane mechanical properties such as reaction duration and EDA concentration have been systematically studied. The membranes cast from an optimal reaction condition comprising 0.8 wt % EDA and 3-hour reaction not only shows a 40% enhancement in membrane Young's Modulus compared to the one without EDA but also achieves a good VMD flux of 43.6 L/m2-h at 60°C. This study may open up a totally new approach to design next-generation high performance MD membranes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4013–4022, 2016
-
Zuo, Jian
2016-05-12
A novel and effective one-step method has been demonstrated to fabricate cross-linked polyvinylidene fluoride (PVDF) membranes with better mechanical properties and flux for seawater desalination via vacuum membrane distillation (VMD). This method involves the addition of two functional nonsolvent additives; namely, water and ethylenediamine (EDA), into the polymer casting solution. The former acts as a pore forming agent, while the latter performs as a cross-linking inducer. The incorporation of water tends to increase membrane flux via increasing porosity and pore size but sacrifices membrane mechanical properties. Conversely, the presence of EDA enhances membrane mechanical properties through in-situ cross-linking reaction. Therefore, by synergistically combining the effects of both functional additives, the resultant PVDF membranes have shown good MD performance and mechanical properties simultaneously. The parameters that affect the cross-link reaction and membrane mechanical properties such as reaction duration and EDA concentration have been systematically studied. The membranes cast from an optimal reaction condition comprising 0.8 wt % EDA and 3-hour reaction not only shows a 40% enhancement in membrane Young\\'s Modulus compared to the one without EDA but also achieves a good VMD flux of 43.6 L/m2-h at 60°C. This study may open up a totally new approach to design next-generation high performance MD membranes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4013–4022, 2016
-
Optics Communications: Special issue on Polymer Photonics and Its Applications
Zhang, Ziyang; Pitwon, Richard C. A.; Feng, Jing
2016-03-01
In the last decade polymer photonics has witnessed a tremendous boost in research efforts and practical applications. Polymer materials can be engineered to exhibit unique optical and electrical properties. Extremely transparent and reliable passive optical polymers have been made commercially available and paved the ground for the development of various waveguide components. Advancement in the research activities regarding the synthesis of active polymers has enabled devices such as ultra-fast electro-optic modulators, efficient white light emitting diodes, broadband solar cells, flexible displays, and so on. The fabrication technology is not only fast and cost-effective, but also provides flexibility and broad compatibility with other semiconductor processing technologies. Reports show that polymers have been integrated in photonic platforms such as silicon-on-insulator (SOI), III-V semiconductors, and silica PLCs, and vice versa, photonic components made from a multitude of materials have been integrated, in a heterogeneous/hybrid manner, in polymer photonic platforms.
-
Enhanced methanol electro-oxidation reaction on Pt-CoO{sub x}/MWCNTs hybrid electro-catalyst
Energy Technology Data Exchange (ETDEWEB)
Nouralishahi, Amideddin, E-mail: Nouralishahi@ut.ac.ir [Catalysis and Nanostructured Materials Research Laboratory, School of Chemical Engineering, University of Tehran, P.O. Box 11155/4563, Tehran (Iran, Islamic Republic of); Caspian Faculty of Engineering, University of Tehran, P.O. Box 43841-119, Rezvanshahr (Iran, Islamic Republic of); Catalysis and Nanotechnology Research Division, Research Institute of Petroleum Industry (RIPI), P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of); Rashidi, Ali Morad, E-mail: Rashidiam@ripi.ir [Catalysis and Nanotechnology Research Division, Research Institute of Petroleum Industry (RIPI), P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of); Mortazavi, Yadollah, E-mail: Mortazav@ut.ac.ir [Catalysis and Nanostructured Materials Research Laboratory, School of Chemical Engineering, University of Tehran, P.O. Box 11155/4563, Tehran (Iran, Islamic Republic of); Khodadadi, Abbas Ali, E-mail: Khodadad@ut.ac.ir [Catalysis and Nanostructured Materials Research Laboratory, School of Chemical Engineering, University of Tehran, P.O. Box 11155/4563, Tehran (Iran, Islamic Republic of); Choolaei, Mohammadmehdi, E-mail: Choolaeimm@ripi.ir [Catalysis and Nanotechnology Research Division, Research Institute of Petroleum Industry (RIPI), P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of)
2015-04-30
Highlights: • Promoting effects of Cobalt oxide on methanol electro-oxidation over Pt/MWCNTs are investigated. • Higher activity, about 2.9 times, and enhanced stability are observed on Pt-CoO{sub x}/MWCNTs. • Electrochemical active surface area of Pt nanoparticles is significantly improved upon CoO{sub x} addition. • Bi-functional mechanism is facilitated in presence of CoO{sub x}. - Abstract: The electro-catalytic behavior of Pt-CoO{sub x}/MWCNTs in methanol electro-oxidation reaction (MOR) is investigated and compared to that of Pt/MWCNTs. The electro-catalysts were synthesized by an impregnation method using NaBH{sub 4} as the reducing agent. The morphological and physical characteristics of samples are examined by XRD, TEM, ICP and EDS techniques. In the presence of CoO{sub x}, Pt nanoparticles were highly distributed on the support with an average particle size of 2 nm, an obvious decrease from 5.1 nm for Pt/MWCNTs. Cyclic voltammetry, CO-stripping, Chronoamperometry, and electrochemical impedance spectroscopy (EIS) measurements are used to study the electrochemical behavior of the electro-catalysts. The results revealed a considerable enhancement in the oxidation kinetics of CO{sub ads} on Pt active sites by the participation of CoO{sub x}. Compared to Pt/MWCNTs, Pt-CoO{sub x}/MWCNTs sample has a larger electrochemical active surface area (ECSA) and higher electro-catalytic activity and stability toward methanol electro-oxidation. According to the results of cyclic voltammetry, the forward anodic peak current density enhances more than 89% at the optimum atomic ratio of Pt:Co = 2:1. Furthermore, inclusion of cobalt oxide species causes the onset potential of methanol electro-oxidation reaction to shift 84 mV to negative values compared to that on Pt/MWCNTs. Based on EIS data, dehydrogenation of methanol is the rate-determining step of MOR on both Pt/MWCNTs and Pt-CoO{sub x}/MWCNTs, at small overpotentials. However, at higher overpotentials, the
-
Characterization and electromechanical performance of cellulose–chitosan blend electro-active paper
International Nuclear Information System (INIS)
Cai Zhijiang; Kim, Jaehwan
2008-01-01
Cellulose-based electro-active paper (EAPap) has been reported as a smart material that has merits in terms of light weight, dry condition, biodegradability, sustainability, large displacement output and low actuation voltage. However, its actuator performance is very sensitive to humidity and degrades with time. To solve these drawbacks, we introduce an EAPap actuator made with cellulose and chitosan blend films. Cellulose–chitosan blend films were prepared by dissolving the polymers in trifluoroacetic acid as a co-solvent followed by spin-coating onto glass substrates. A bending EAPap actuator is made by depositing thin gold electrodes on both sides of the cellulose–chitosan films. Characteristics of these blend films are performed by FT-IR, XRD, TGA, SEM and a pull test. The electromechanical performance of the EAPap actuator is evaluated in terms of free bending displacement with respect to the actuation frequency, voltage, time variation and humidity levels. Results show that this chitosan–cellulose-based EAPap actuator is less sensitive to humidity: it shows a large bending displacement (about 4.1 mm) and long lifetime (more than 9 h) at room humidity conditions. It indicates that this chitosan–cellulose EAPap is promising for many biomimetic applications in the foreseeable future
-
High-throughput screening of ionic conductivity in polymer membranes
International Nuclear Information System (INIS)
Zapata, Pedro; Basak, Pratyay; Carson Meredith, J.
2009-01-01
Combinatorial and high-throughput techniques have been successfully used for efficient and rapid property screening in multiple fields. The use of these techniques can be an advantageous new approach to assay ionic conductivity and accelerate the development of novel materials in research areas such as fuel cells. A high-throughput ionic conductivity (HTC) apparatus is described and applied to screening candidate polymer electrolyte membranes for fuel cell applications. The device uses a miniature four-point probe for rapid, automated point-to-point AC electrochemical impedance measurements in both liquid and humid air environments. The conductivity of Nafion 112 HTC validation standards was within 1.8% of the manufacturer's specification. HTC screening of 40 novel Kynar poly(vinylidene fluoride) (PVDF)/acrylic polyelectrolyte (PE) membranes focused on varying the Kynar type (5x) and PE composition (8x) using reduced sample sizes. Two factors were found to be significant in determining the proton conducting capacity: (1) Kynar PVDF series: membranes containing a particular Kynar PVDF type exhibited statistically identical mean conductivity as other membranes containing different Kynar PVDF types that belong to the same series or family. (2) Maximum effective amount of polyelectrolyte: increments in polyelectrolyte content from 55 wt% to 60 wt% showed no statistically significant effect in increasing conductivity. In fact, some membranes experienced a reduction in conductivity.
-
Directory of Open Access Journals (Sweden)
Mingquan Wang
2016-04-01
Full Text Available Steroidal estrogens are a representative type of endocrine-disrupting chemical contaminant that has been detected in surface water. In this paper, modified polyvinylidene fluoride (PVDF membranes were prepared by adding different amounts of polyvinyl pyrrolidone (PVP and nano-TiO2 particles. PVDF-PVP membrane adsorption, UV photolysis and PVDF-PVP-TiO2 membrane photocatalysis performance were investigated by considering the rejection of estrone (E1 and 17β-estradiol (E2 in the cross-flow filtration experiments. The mechanism of photocatalytic degradation on TiO2-doped PVDF membranes was also evaluated. The results from the study indicated that adding PVP and nano-TiO2 appropriately in PVDF membranes could be an effective method for better E1and E2 rejection due to adsorption and photocatalytic degradation.
-
Vinogradov, Aleksandra M.; Ihlefeld, Curtis M.; Henslee, Issac
2009-01-01
The paper concerns the time-dependent behavior of electroactive polymers (EAP) and their use in advanced intelligent structures for space exploration. Innovative actuator design for low weight and low power valves required in small plants planned for use on the moon for chemical analysis is discussed. It is shown that in-depth understanding of cyclic loading effects observed through accelerated creep rates due to creep-fatigue interaction in polymers is critical in terms of proper functioning of EAP based actuator devices. In the paper, an overview of experimental results concerning the creep properties and cyclic creep response of a thin film piezoelectric polymer polyvinylidene fluoride (PVDF) is presented. The development of a constitutive creep-fatigue interaction model to predict the durability and service life of electroactive polymers is discussed. A novel method is proposed to predict damage accumulation and fatigue life of polymers under oyclic loading conditions in the presence of creep. The study provides a basis for ongoing research initiatives at the NASA Kennedy Space Center in the pursuit of new technologies using EAP as active elements for lunar exploration systems.
-
Finite element modeling of the electromechanical coupling in ionic polymer transducers
Akle, Barbar; Habchi, Wassim; Wallmersperger, Thomas; Leo, Donald
2010-04-01
Several researchers are actively studying Ionomeric polymer transducers (IPT) as a large strain low voltage Electro- Active Polymer (EAP) actuator. EAPs are devices that do not contain any moving parts leading to a potential large life time. Furthermore, they are light weight and flexible. An IPT is made of an ion saturated polymer usually Nafion, sandwiched between two electrodes made of a mixture of Nafion and electrically conductive particles usually RuO2 or platinum. Nafion is an acid membrane in which the cations are mobile while the anions are covalently fixed to the polymer structure. Upon the application of an electric potential on the order of 2V at the electrodes the mobile positive ions migrate towards the cathode leading to bending strains in the order of 5%. Our earlier studies demonstrate that the cations develop thin boundary layers around the electrode. Later developments in this finite element model captured the importance of adding particles in the electrode. This study presents the electromechanical coupling in ionic polymer transducers. Since all our earlier models were restricted to the electro-chemical part, here we will introduce the chemomechanical coupling. This coupling is performed based on previous studies (Akle and Leo) in which the authors experimentally showed that the mechanical strain in IPTs is proportional to a linear term and a quadratic term of the charge accumulated at the electrode. The values of the linear and quadratic terms are extracted from experimental data.
-
Indermun, Sunaina; Choonara, Yahya E; Kumar, Pradeep; Du Toit, Lisa C; Modi, Girish; Luttge, Regina; Pillay, Viness
2014-02-01
Chronic pain poses a major concern to modern medicine and is frequently undertreated, causing suffering and disability. Patient-controlled analgesia, although successful, does have limitations. Transdermal delivery is the pivot to which analgesic research in drug delivery has centralized, especially with the confines of needle phobias and associated pain related to traditional injections, and the existing limitations associated with oral drug delivery. Highlighted within is the possibility of further developing transdermal drug delivery for chronic pain treatment using iontophoresis-based microneedle array patches. A concerted effort was made to review critically all available therapies designed for the treatment of chronic pain. The drug delivery systems developed for this purpose and nondrug routes are elaborated on, in a systematic manner. Recent developments and future goals in transdermal delivery as a means to overcome the individual limitations of the aforementioned delivery routes are represented as well. The approval of patch-like devices that contain both the microelectronic-processing mechanism and the active medicament in a small portable device is still awaited by the pharmaceutical industry. This anticipated platform may provide transdermal electro-activated and electro-modulated drug delivery systems a feasible attempt in chronic pain treatment. Iontophoresis has been proven an effective mode used to administer ionized drugs in physiotherapeutic, diagnostic, and dermatological applications and may be an encouraging probability for the development of devices and aids in the treatment of chronic pain. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.
-
Enhancement of polar crystalline phase formation in transparent PVDF-CaF{sub 2} composite films
Energy Technology Data Exchange (ETDEWEB)
Lee, Sang Goo; Ha, Jong-Wook, E-mail: jongwook@krict.re.kr; Sohn, Eun-Ho; Park, In Jun; Lee, Soo-Bok
2016-12-30
Highlights: • The crystalline phase in transparent PVDF-CaF{sub 2} composite films was investigated. • CaF{sub 2} promoted the formation of polar crystalline phases in PVDF matrix. • Ordered γ-phase was obtained by thermal treatment of as-cast films at the vicinity of its melting temperature. - Abstract: We consider the influence of calcium fluoride (CaF{sub 2}) nanoparticles on the crystalline phase formation of poly(vinylidene fluoride) (PVDF) for the first time. The transparent PVDF-CaF{sub 2} composite films were prepared by casting on PET substrates using N,N-dimethylacetamide (DMAc) as a solvent. It was found that CaF{sub 2} promoted the formation of polar crystalline phase of PVDF in composites, whereas nonpolar α-phase was dominant in the neat PVDF film prepared at the same condition. The portion of polar crystalline phase increased in proportional to the weight fraction of CaF{sub 2} in the composite films up to 10 wt%. Further addition of CaF{sub 2} suppressed completely the α-phase formation. Polar crystalline phase observed in as-cast composite films was a mixture of β- and γ-polymorph structures. It was also shown that much ordered γ-phase could be obtained through thermal treatment of as-cast PVDF-CaF{sub 2} composite film at the temperatures above the melting temperature of the composite films, but below that of γ-phase.
-
Zheng, Chuan-Tao; Ma, Chun-Sheng; Yan, Xin; Wang, Xian-Yin; Zhang, Da-Ming
2008-07-01
Structural model and design technique are proposed for a polymer directional coupler electro-optic switch with rib waveguides and push-pull electrodes, of which the electric field distribution is analyzed by the conformal transforming method and image method. In order to get the minimum mode loss and the minimum switching voltage, the parameters of the waveguide and electrode are optimized, such as the core with, core thickness, buffer layer between the core and the electrode, coupling gap between the waveguides, electrode thickness, electrode width and electrode gap. Switching Characteristics are analyzed, which include the output power, insertion loss, and crosstalk. To realize normal switching function, the fabrication error, spectrum shift, and coupling loss between a single mode fiber (SMF) and the waveguide are discussed. Simulation results show that the coupling length is 3082 μm, push-pull switching voltage is 2.14 V, insertion loss is less than 1.17 dB, and crosstalk is less than -30 dB for the designed device.
-
Arefi-Oskoui, Samira; Khataee, Alireza; Vatanpour, Vahid
2017-07-10
In this research, MgAl-CO 3 2- nanolayered double hydroxide (NLDH) was synthesized through a facile coprecipitation method, followed by a hydrothermal treatment. The prepared NLDHs were used as a hydrophilic nanofiller for improving the performance of the PVDF-based ultrafiltration membranes. The main objective of this research was to obtain the optimized formula of NLDH/PVDF nanocomposite membrane presenting the best performance using computational techniques as a cost-effective method. For this aim, an artificial neural network (ANN) model was developed for modeling and expressing the relationship between the performance of the nanocomposite membrane (pure water flux, protein flux and flux recovery ratio) and the affecting parameters including the NLDH, PVP 29000 and polymer concentrations. The effects of the mentioned parameters and the interaction between the parameters were investigated using the contour plot predicted with the developed model. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and water contact angle techniques were applied to characterize the nanocomposite membranes and to interpret the predictions of the ANN model. The developed ANN model was introduced to genetic algorithm (GA) as a bioinspired optimizer to determine the optimum values of input parameters leading to high pure water flux, protein flux, and flux recovery ratio. The optimum values for NLDH, PVP 29000 and the PVDF concentration were determined to be 0.54, 1, and 18 wt %, respectively. The performance of the nanocomposite membrane prepared using the optimum values proposed by GA was investigated experimentally, in which the results were in good agreement with the values predicted by ANN model with error lower than 6%. This good agreement confirmed that the nanocomposite membranes prformance could be successfully modeled and optimized by ANN-GA system.
-
Energy Technology Data Exchange (ETDEWEB)
Zhao, Xing Guan; Jin, En Mei; Gu, Hal-Bon, E-mail: hbgu@chonnam.ac.kr
2013-12-15
The PEO and PVDF-HFP mixtures were used as polymer electrolytes in solid-state dye-sensitized solar cells (DSSCs). Correlation between the ionic conductivity and cell performance by varying the composition of polymer electrolytes was investigated to elucidate the importance of the ionic conductivity in determining the charge transfer and energy conversion efficiency of solid-state DSSCs. In this work, for increasing the ionic conductivity and charge transfer, GNF was added to the polymer electrolyte. The ionic conductivity of polymer electrolyte containing GNF (0.005 g) is 8.67 × 10{sup −4} S cm{sup −1} and pristine polymer electrolyte is 3.81 × 10{sup −4} S cm{sup −1}. The charge transfer of GNF (0.005 g) added DSSCs is faster than the other samples, the electron transport time is 1.53 ms and electron life time is 27.20 ms. The increase of current density with the polymer electrolyte containing GNF (0.005 g) can be possibly attributed to the direct contact between dye/TiO{sub 2} and I{sup −}/I{sub 3}{sup −} that will improve the charge transportation. The highest energy conversion efficiency of 4.60% is obtained for polymer electrolyte containing GNF (0.005 g)
-
Polymer poling characterization using second harmonic generation (SHG)
Tellier, Gildas; Averty, Dominique; Blart, Errol; Boisrobert, Christian; Gundel, Hartmut; Le Tacon, Sylvain; Monnereau, Cyrille; Odobel, Fabrice; Seveno, Raynald
2006-04-01
Several polymer molecules have structures which are suitable for the non-linear optic applications. We report on the design and fabrication of a high performance electro-optic modulator made of polymer thin films. The polymer we study contains a chromophore based on Disperse Red One covalently grafted to a host-matrix. The polymer materials are deposited in thin layers on a glass substrate by chemical solution deposition, either by spin-coating or by dip-coating. The thickness of the films is ranging from a hundred nanometers to several micrometers. Initially, the polymer molecules are randomly oriented and the films are isotropic, hence no electro-optic effect can be observed. In order to break the symmetry and align the chromophores, the films are submitted to the so-called corona poling process. As a result, their structure become non-centrosymmetric and the second-order susceptibility is no longer zero. The corona poling method consists of applying a high electric field to the polymer by means of a needle electrode, placed above the polymer film which is posed on a grounded sample support electrode. Thermal regulation of the support electrode allows to control the temperature during the poling of the films. Once the poling process has been established, a chemical cross-linking function is thermally activated in order to fix the orientation of the chromophores in the polymer matrix. The orientation and its stability in time is evaluated with a Second Harmonic Generation measurement set-up using the Makers Fringes configuration. We studied the influence of the poling temperature, the distance between the corona needle electrode and the sample, the high voltage applied, and the duration of the poling process on the efficiency of chromophore orientation in order to optimize the poling procedure. Finally, aging of poled polymer samples has been investigated at elevated temperatures, confirming the stability of the cross-linking process.
-
Sol-Gel Material-Enabled Electro-Optic Polymer Modulators
Himmelhuber, Roland; Norwood, Robert A.; Enami, Yasufumi; Peyghambarian, Nasser
2015-01-01
Sol-gels are an important material class, as they provide easy modification of material properties, good processability and are easy to synthesize. In general, an electro-optic (EO) modulator transforms an electrical signal into an optical signal. The incoming electrical signal is most commonly information encoded in a voltage change. This voltage change is then transformed into either a phase change or an intensity change in the light signal. The less voltage needed to drive the modulator and the lower the optical loss, the higher the link gain and, therefore, the better the performance of the modulator. In this review, we will show how sol-gels can be used to enhance the performance of electro-optic modulators by allowing for designs with low optical loss, increased poling efficiency and manipulation of the electric field used for driving the modulator. The optical loss is influenced by the propagation loss in the device, as well as the losses occurring during fiber coupling in and out of the device. In both cases, the use of sol-gel materials can be beneficial due to the wide range of available refractive indices and low optical attenuation. The influence of material properties and synthesis conditions on the device performance will be discussed. PMID:26225971
-
Merati, Zohreh; Basiri Parsa, Jalal
2018-03-01
Catalyst supports play important role in governing overall catalyst activity and durability. In this study metal oxides (SnO2, Sb and Nb doped SnO2) were electrochemically deposited on titanium substrate (Ti) as a new support material for Pt catalyst in order to electro-oxidation of methanol. Afterward platinum nanoparticles were deposited on metal oxide film via electro reduction of platinum salt in an acidic solution. The surface morphology of modified electrodes were evaluated by field-emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDX) techniques. The electro-catalytic activities of prepared electrodes for methanol oxidation reaction (MOR) and oxidation of carbon monoxide (CO) absorbed on Pt was considered with cyclic voltammetry. The results showed high catalytic activity for Pt/Nb-SnO2/Ti electrode. The electrochemical surface area (ECSA) of a platinum electro-catalyst was determined by hydrogen adsorption. Pt/Nb-SnO2/Ti electrode has highest ECSA compared to other electrode resulting in high activity toward methanol electro-oxidation and CO stripping experiments. The doping of SnO2 with Sb and Nb improved ECSA and MOR activity, which act as electronic donors to increase electronic conductivity.
-
International Nuclear Information System (INIS)
Ganesan, Lakshmi Meena; Wirges, Werner; Gerhard, Reimund; Mellinger, Axel
2010-01-01
Polymer-dispersed liquid crystals (PDLCs) are composite materials that consist of micrometre-sized liquid-crystal (LC) droplets embedded in a polymer matrix. From ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) and a nematic LC, PDLC films containing 10 and 60 wt% LC were prepared, and their electro-optical and piezo-optical behaviour was investigated. The electric field that is generated by the application of mechanical stress leads to changes in the transmittance of the PDLC film through a combination of piezoelectric and electro-optical effects. Such a piezo-optical PDLC material may be useful, e.g., in sensing and visualization applications.
-
Hernández, Jaime J.; Monclús, Miguel A.; Navarro-Baena, Iván; Viela, Felipe; Molina-Aldareguia, Jon M.; Rodríguez, Isabel
2017-03-01
This paper presents a multifunctional polymer surface that provides superhydrophobicity and self-cleaning functions together with an enhancement in mechanical and electrical performance. These functionalities are produced by nanoimprinting high aspect ratio pillar arrays on polymeric matrix incorporating functional reinforcing elements. Two distinct matrix-filler systems are investigated specifically, Carbon Nanotube reinforced Polystyrene (CNT-PS) and Reduced Graphene Oxide reinforced Polyvinylidene Difluoride (RGO-PVDF). Mechanical characterization of the topographies by quantitative nanoindentation and nanoscratch tests are performed to evidence a considerable increase in stiffness, Young’s modulus and critical failure load with respect to the pristine polymers. The improvement on the mechanical properties is rationalized in terms of effective dispersion and penetration of the fillers into the imprinted structures as determined by confocal Raman and SEM studies. In addition, an increase in the degree of crystallization for the PVDF-RGO imprinted nanocomposite possibly accounts for the larger enhancement observed. Improvement of the mechanical ruggedness of functional textured surfaces with appropriate fillers will enable the implementation of multifunctional nanotextured materials in real applications.
-
Mechanical Degradation of Graphite/PVDF Composite Electrodes: A Model-Experimental Study
Energy Technology Data Exchange (ETDEWEB)
Takahashi, K; Higa, K; Mair, S; Chintapalli, M; Balsara, N; Srinivasan, V
2015-12-11
Mechanical failure modes of a graphite/polyvinylidene difluoride (PVDF) composite electrode for lithium-ion batteries were investigated by combining realistic stress-stain tests and mathematical model predictions. Samples of PVDF mixed with conductive additive were prepared in a similar way to graphite electrodes and tested while submerged in electrolyte solution. Young's modulus and tensile strength values of wet samples were found to be approximately one-fifth and one-half of those measured for dry samples. Simulations of graphite particles surrounded by binder layers given the measured material property values suggest that the particles are unlikely to experience mechanical damage during cycling, but that the fate of the surrounding composite of PVDF and conductive additive depends completely upon the conditions under which its mechanical properties were obtained. Simulations using realistic property values produced results that were consistent with earlier experimental observations.
-
Synergistic promotion of polar phase crystallization of PVDF by ionic liquid with PEG segment
Xu, Pei; Fu, Weijia; Cui, Zhaopei; Ding, Yunsheng
2018-06-01
To investigate the effect of imidazolium ionic liquid with poly(ethylene glycol) segment (IL) on the polar phase crystallization behavior of poly(vinylidene fluoride) (PVDF), a series of PVDF/IL composites were prepared using solution-cast method. The crystallization peak temperature of PVDF composites and the growth speed of samples decrease with increasing of IL. The >CF2 groups in amorphous region are retained and >CF2 groups in crystalline region are liberated by the PEG long soft segments of IL. The intensity of peaks represented as α phase reduces, moreover polar phase content increases with increasing of IL. The interaction between the >CF2 and the imidazolium cation can induce the polar phase, and the interaction between the >CF2 and PEG soft segment can strengthen polar crystalline induction. PVDF/12IL composite can form big γ spherulite circled by β phase.
-
Structure-Function Relationships of Ferroelectric Polymers.
Pavlopoulou, Eleni; Maiz, Jon; Spampinato, Nicoletta; Maglione, Mario; Hadziioannou, Georges
Poly(vinylidene fluoride), PVDF, and its copolymers with trifluoroethylene, P(VDF-co-TrFE) have been long appreciated for their excellent ferroelectric properties. Although they have been mainly studied in the 80s and 90s, understanding their performance is still lacking. Yet the increasing use of P(VDF-co-TrFE) thin films in organic electronic devices during the last ten years revives the need for apprehending the function of these materials. In this work we investigate the structure of P(VDF-co-TrFE) films and correlate it to their ferroelectric properties. Our results show that ferroelectric performance is solely driven by the fraction of polymer that has been crystallized in the ferroelectric phases of PVDF. The relations between remnant polarization, coercive field and dipole switching rate of P(VDF-co-TrFE) with the ferroelectric crystallinity are demonstrated. The French Research Agency (ANR), the Aquitaine Region, Arkema and STMicroelectronics are kindly acknowledged for financial support.
-
International Nuclear Information System (INIS)
Haghiashtiani, Ghazaleh; Greminger, Michael A
2015-01-01
The focus of this work is to evaluate a new carbon fiber reinforced composite structure with integrated sensing capabilities. In this composite structure, the typical matrix material used for carbon fiber reinforced composites is replaced with the thermoplastic polyvinylidene difluoride (PVDF). Since PVDF has piezoelectric properties, it enables the structure to be used for integrated load sensing. In addition, the electrical conductivity property of the carbon fabric is harnessed to form the electrodes of the integrated sensor. In order to prevent the carbon fiber electrodes from shorting to each other, a thin Kevlar fabric layer is placed between the two carbon fiber electrode layers as a dielectric. The optimal polarization parameters were determined using a design of experiments approach. Once polarized, the samples were then used in compression and tensile tests to determine the effective d 33 and d 31 piezoelectric coefficients. The degree of polarization of the PVDF material was determined by relating the effective d 33 coefficient of the composite to the achieved d 33 of the PVDF component of the composite using a closed form expression. Using this approach, it was shown that optimal polarization of the composite material results in a PVDF component d 33 of 3.2 pC N −1 . Moreover, the Young’s modulus of the composite structure has been characterized. (paper)
-
Directory of Open Access Journals (Sweden)
Seungjun Lee
2016-01-01
Full Text Available In Li-ion batteries, the mechanical strengths at the interfaces of binder/particle and binder/current collector play an important role in maintaining the mechanical integrity of the composite electrode. In this work, the separation behaviors between polyvinylidene fluoride (PVDF binders and copper current collectors are studied in the opening and sliding modes using molecular dynamics (MD simulations. The simulation shows that the separation occurs inside the PVDF rather than at the interface due to the strong adhesion between PVDF and copper. This fracture behavior is different from the behavior of the PVDF/graphite basal plane that shows a clear separation at the interface. The results suggest that the adhesion strength of the PVDF/copper is stronger than that of the PVDF/graphite basal plane. The methodology used in MD simulation can directly evaluate the adhesion strength at the interfaces of various materials between binders, substrates, and particles at the atomic scales. The proposed method can therefore provide a guideline for the design of the electrode in order to enhance the mechanical integrity for better battery performance.
-
Writing on ultra thin uniaxially oriented polymer films with an electron beam
International Nuclear Information System (INIS)
Petermann, J.; Wenderoth, K.
1990-01-01
Information storage polymers have been described and used for many years. When using an electron beam to store information, chemical changes in the macromolecules via local radiation damage is utilized to print the information into the polymer. This letter reports the writing of optically detectable information into birefringent polymer films. The method is based on the fact that preferred orientation of the macromolecules can be destroyed by electron radiation damage. The damage is produced by an electron beam in a transmission electron microscope. The resulting information is observed optically in a polarizing microscope. The polymer films used in the present study were polybutene 1 (PB 1), polyethylene (PE) and polyvinyl-idenfluoride (PVDF). (author)
-
International Nuclear Information System (INIS)
Park, Joung-Man; Gu, Ga-Young; Wang, Zuo-Jia; Kwon, Dong-Jun; DeVries, K. Lawrence
2013-01-01
Interfacial durability and electrical properties of CNT (carbon nanotube) or ITO (indium tin oxide) coated PVDF (poly(vinylidene fluoride)) nanocomposites were investigated for self-sensor and micro-actuator applications. The electrical resistivity of nanocomposites and the durability of interfacial adhesion were measured using a four points method during cyclic fatigue loading. Although the CNT/PVDF nanocomposites exhibited lower electrical resistivity due to the inherently low resistivity of CNT, both composite types showed good self-sensing performance. The durability of the adhesion at the interface was also good for both CNT and ITO/PVDF nanocomposites. Static contact angle, surface energy, work of adhesion, and spreading coefficient between either CNT or ITO and PVDF were determined as checks to verify the durability of the interfacial adhesion. The actuation performance of CNT or ITO coated PVDF specimens was determined through measurements of the induced displacement using a laser displacement sensor, while both the frequency and voltage were changed. The displacement of these actuated nanocomposites increased with increasing voltage and decreased with increasing frequency. CNT/PVDF nanocomposites exhibited better performance as self-sensors and micro-actuators than did ITO/PVDF nanocomposites.
-
Synthesis and Applications of Inorganic/Organic-Polymer Nanocomposites
Goyal, Anubha
(vinylidene fluoride-hexafluoropropylene (PVDF-HFP) polymer electrolyte with the three-dimensional (3D), nanostructured electrode composed of aligned carbon nanotube (CNT)-copper oxide hybrid. This hybrid electrode was fabricated by a combination of chemical vapor deposition and electrodeposition techniques. Embedding it in PVDF polymer results in a flexible system and also renders an external separator redundant. This new design shows an improvement in electrochemical performance over pure CNTs as both CNTs and Cu2O contribute towards electrochemical activity. Efforts have also been undertaken towards synthesizing synthetic adhesives by mimicking the design principles found in nature. Aligned patterned CNTs have been used to replicate the fibrillar structure found in geckos' toes which generates adhesion through van der Waals forces. The adhesive forces in CNTs were found to be higher than in geckos and the key to this phenomenon lies in the extensive side-wall contact obtained on compressing CNTs against a surface.
-
International Nuclear Information System (INIS)
Dumas, L.
2012-01-01
This work deals with the modification of VDF-based polymer induced by γ-radiation as the polymer may be used in electrochemical super-capacitors. The main objective was to limit the swelling of the fluorinated matrix with a given electrolyte while a good wetting of the polymer by the liquid was also required. As the main basic process involved in polymer radiolysis is the formation of radicals, a part of the work was dedicated to the study of such species by using Electron Spin Resonance spectroscopy. A simulation model of ESR spectra was established in order to identify and quantify each radical species. The effect of several parameters such as radiation dose, annealing time or the nature of polymer matrix on the concentration of each species where investigated. A relation with the evolution of the crosslink density of the network formed during the radiolysis was proposed. In addition, one of the key steps of this work was to study the radiation crosslinking ability of VDF-based polymers and find a way to increase the crosslink density. This was achieved by incorporating, prior to the radiation process, a radiation sensitive cross linker: TAIC. Finally, a new strategy based on the modification of surface properties of PVDF was investigated. It consists in the radiation grafting of penta-fluor-styrene onto PVDF surface followed by the chemo-selective functionalization of the grafted segments. As a conclusion, the different approaches used in this thesis allowed us to understand the radiolysis of VDF-based polymers and take advantage of the elementary process involved in this type of chemistry, to build up robust and promising strategies for tuning properties. (author)
-
Optimization Of PVDF-TrFE Processing Conditions For The Fabrication Of Organic MEMS Resonators.
Ducrot, Pierre-Henri; Dufour, Isabelle; Ayela, Cédric
2016-01-21
This paper reports a systematic optimization of processing conditions of PVDF-TrFE piezoelectric thin films, used as integrated transducers in organic MEMS resonators. Indeed, despite data on electromechanical properties of PVDF found in the literature, optimized processing conditions that lead to these properties remain only partially described. In this work, a rigorous optimization of parameters enabling state-of-the-art piezoelectric properties of PVDF-TrFE thin films has been performed via the evaluation of the actuation performance of MEMS resonators. Conditions such as annealing duration, poling field and poling duration have been optimized and repeatability of the process has been demonstrated.
-
Patel, Arunendra Kumar; Sunder, Aishwarya; Mishra, Shweta; Bajpai, Rakesh
2018-05-01
This paper gives an insight on the synthesis and crystalline properties of Polyvinylidene Fluoride (PVDF) (host matrix) composites impregnated with Cadmium Sulphide (CdS) using Dimethyl formamide (DMF) as the base, prepared by the well known solvent casting technique. The effect of doping concentration of CdS in to the PVDF matrix was studied using X-ray diffraction technique. The structural properties like crystallinity Cr, interplanar distance d, average size of the crystalline region (D), and average inter crystalline separation (R) have been estimated for the developed composite. The crystallinity index, crystallite size and inter crystalline separation is increasing with increase in the concentration of CdS in to the PVDF matrix while the interplanar distance d is decreasing.
-
Takagi, Hiroshi
2011-05-01
The oldest pottery in Japan was made 16,500 years ago in Jomon period. On the background of a long history of Japanese ceramics, Murata and other Japanese manufacturers have been developing electro-ceramic materials and manufacturing many kinds of electronic components using them. In 1937, TDK manufactured ferrite cores first in the world. Then, Japanese electro-ceramic industry has led the world on electro-ceramic materials and components until now, especially in the fields of BaTiO3, PZT, PTC thermistor, ZnO varistor and insulating ceramics. From the analysis of the papers reported lately, R&D activities of Japanese manufacturers are understood to cover not only improving properties of electro-ceramics, but also appropriate technologies and basic technologies.
-
Mechanical properties of cellulose electro-active paper under different environmental conditions
International Nuclear Information System (INIS)
Kim, Heung Soo; Kim, Jaehwan; Jung, Woochul; Ampofo, Joshua; Craft, William; Sankar, Jagannathan
2008-01-01
The mechanical properties of cellulose-based electro-active paper (EAPap) are investigated under various environmental conditions. Cellulose EAPap has been discovered as a smart material that can be used as both sensor and actuator. Its advantages include low voltage operation, light weight, low power consumption, biodegradability and low cost. EAPap is made with cellulose paper coated with thin electrodes. EAPap shows a reversible and reproducible bending movement as well as longitudinal displacement under an electric field. However, EAPap is a complex anisotropic material which has not been fully characterized. This study investigates the mechanical properties of cellulose-based EAPap, including Young's modulus, yield strength, ultimate strength and creep, along with orientation directions, humidity and temperature levels. To test the materials in different humidity and temperature levels, a special material testing system was made that can control the testing environmental conditions. The initial Young's modulus of EAPap is in the range of 4–9 GPa, which was higher than that of other polymer materials. Also, the Young's modulus is orientation dependent, which may be associated with the piezoelectricity of EAPap materials. The elastic strength and stiffness gradually decreased when the humidity and temperature were increased. Creep and relaxation were observed under constant stress and strain, respectively. Through scanning electron microscopy, EAPap is shown to exhibit both layered and oriented cellulose macromolecular structures that impact both the elastic and plastic behavior
-
Energy Technology Data Exchange (ETDEWEB)
Li, Dong; Wang, Zhen; Han, Xuemeng; Li, Yue; Guo, Xiaobin; Zuo, Yalu; Xi, Li, E-mail: xili@lzu.edu.cn
2015-02-01
FeCo films with various thicknesses were fabricated by direct-current magnetron sputtering on corning glass and organic ferroelectric PVDF substrates at the same time with 5 nm Ru seed layer and 5 nm Ta protective layer. The in-plane uniaxial anisotropy field of FeCo on glass substrate increases from 24 to 36 Oe with the increase of FeCo film thickness from 5 to 100 nm. However, a large in-plane anisotropy field of FeCo on PVDF substrate increases with FeCo thickness from 5 to 20 nm and gradually decreases with the FeCo thickness further increasing. Atomic force microscope images of FeCo on glass show quite smooth surface with root-mean-square roughness around 0.5 nm and have none visible granules on the surface for all samples. While, AFM images of FeCo on PVDF show quite rough surface with RMS roughness around 25 nm and have visible granules with the smallest granules appearing at the FeCo thickness of 20 nm. The permeability spectra show the typical ferromagnetic resonance phenomenon and can be well fitted by the LLG equation with the obtained experimental parameters. The ferromagnetic resonance frequency can reach 7.0 GHz for the 20 nm FeCo film on PVDF. Moreover, the quality factor of this sample can respectively reach 26, 12 and 7 at 1.0, 2.0, and 3.0 GHz, indicating the potential real 3G application for high-frequency devices. - Highlights: 1.Magnetic and morphological properties of FeCo films on PVDF substrates are studied. 2.The large anisotropy field of FeCo films on PVDF is obtained. 3.Improved high frequency properties of FeCo films on flexible substrates are obtained. 4.The origin of improved high frequency properties of FeCo films on PVDF is studied.
-
Rozana, M. D.; Arshad, A. N.; Wahid, M. H. M.; Habibah, Z.; Sarip, M. N.; Rusop, M.
2018-05-01
This study investigates the effect of annealing on the topography, morphology and crystal phases of poly(vinylideneflouride)/Magnesium Oxide (MgO) nanocomposites thin films via AFM, FESEM and ATR-FTIR. The nanocomposites thin films were annealed at temperatures ranging from 70°C to 170°C. The annealed PVDF/MgO nanocomposites thin films were then cooled at room temperature before removal from the oven. This is to restructure the crystal lattice and to reduce imperfection for the PVDF/MgO nanocomposites thin films. PVDF/MgO nanocomposites thin films with annealing temperatures of 70°C, 90°C and 110°C showed uniform distribution of MgO nanoparticles, relatively low average surface roughness and no visible of defects. High application of annealing temperature on PVDF/MgO nanocomposites thin films caused tear-like defects on the thin films surface as observed by FESEM. The PVDF/MgO nanocomposites thin films annealed at 70°C was found to be a favourable film to be utilized in this study due to its enhanced β-crystalites of PVDF as evident in ATR-FTIR spectra.
-
Sheikh, Faheem A.; Zargar, Mohammad Afzal; Tamboli, Ashif H.; Kim, Hern
2016-11-01
Nanofibers fabricated from Poly(vinylidene fluoride) (PVDF) possesses potential applications in the field of filtrations, because of their excellent resistance towards harsh chemicals. However, the hydrophobicity restricts its further application. In this work, we focus on optimal parameters for post-electrospun tethering of Poly(vinyl alcohol) (PVA) as superhydrophilic domain onto each individual PVDF nanofibers by exploiting the in situ hydrothermal approach. The results indicated an increase in nanofiber diameters due to coating of PVA and improved surface wettability of PVDF nanofibers. The tensile tests of nanofibers indicated that mechanical properties of PVDF nanofibers could be sharply tuned from rigid to ductile. Furthermore, the studies strongly suggest that in situ hydrothermal treatment of post-electrospun nanofibers can improve the water contact angle and these nanofibers can be used in varied applications (e.g., in water purification systems).
-
International Nuclear Information System (INIS)
Iyore, O.D.; Roodenko, K.; Winkler, P.S.; Noriega, J.R.; Vasselli, J.J.; Chabal, Y.J.; Gnade, B.E.
2013-01-01
We report the characterization of photo-crosslinked polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) thin film, metal–insulator–metal capacitors fabricated using standard semiconductor processing techniques. We characterize the capacitors using in-situ vibrational spectroscopy during thermally-assisted poling and correlate the Fourier transform infrared spectroscopy (FTIR) results with X-ray diffraction (XRD) results. FTIR analysis of the neat PVDF-HFP showed α → β transformations during poling at room temperature and at 55 °C. α → β transformations were observed for the crosslinked polymer only during poling at 55 °C. XRD data revealed that photo-crosslinking caused the polymer to partially crystallize into the β-phase. The similar behavior of the neat and crosslinked samples at 55 °C suggests that a higher activation energy was needed for α → β transformations in crosslinked PVDF-HFP during poling. Electrical measurements showed that photo-crosslinking had no significant effect on the dielectric constant and dielectric loss of PVDF-HFP. However, the dielectric strength and maximum energy density of the crosslinked polymer were severely reduced. - Highlights: • Polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) dielectrics were studied. • Phase transformations were observed only at 55 °C for the crosslinked PVDF-HFP. • Crosslinking had no strong effect on the dielectric constant of PVDF-HFP. • Breakdown strengths were 620 MVm −1 and 362 MVm −1 for neat and crosslinked films
-
Fabrication of a sulfite biosensor by the use of conducting polymer
International Nuclear Information System (INIS)
Hosseini, M.; Bahmani, B; Moztarzadeh, F.; Rabiee, M.
2008-01-01
In this research, an enzyme modified electrode has been produced during the electro polymerization of aniline through incorporation of Sulfite oxidase into a conducting polymer. Then the bioelectrochemical response of resulted sulfite biosensor was investigated at different experimental conditions. Study of the stability of the resulted sulfite biosensor revealed that formation of a passive film on the aluminum surface causes improved stability of the electro active films formed on the electrode surface. The bioelectrochemical response of the enzyme-modified electrode as a sulfite biosensor was investigated at different experimental conditions. The optimum p H and temperature were 8.5 and 35 d eg C , respectively. The apparent Michaelis-Menten constant and the activation energy of the enzyme catalyzed reaction were calculated
-
Directory of Open Access Journals (Sweden)
Irina S. Flyagina
2017-08-01
Full Text Available Mixed-matrix membranes are contemporary nanocomposite materials with many potential applications, from liquid and gas separations to chemical sensors and biomedicine. We report fabrication of a metal-organic framework (MOF-based nanocomposite, combining polyvinylidene difluoride (PVDF polymer as the matrix and ZIF-90 nanocrystals of up to 30 wt. % filler content. The focus is to establish the processing—microstructure—mechanical property relationships. We reveal the importance for quantifying salient effects of the filler contents: (i tensile strength degrades beyond 10 wt. % and (ii mechanical toughness declines due to membrane embrittlement. These are vital mechanical aspects but widely overlooked in the emergent field of MOF membranes and composites.
-
Flyagina, Irina S.; Mahdi, E. M.; Titov, Kirill; Tan, Jin-Chong
2017-08-01
Mixed-matrix membranes are contemporary nanocomposite materials with many potential applications, from liquid and gas separations to chemical sensors and biomedicine. We report fabrication of a metal-organic framework (MOF)-based nanocomposite, combining polyvinylidene difluoride (PVDF) polymer as the matrix and ZIF-90 nanocrystals of up to 30 wt. % filler content. The focus is to establish the processing—microstructure—mechanical property relationships. We reveal the importance for quantifying salient effects of the filler contents: (i) tensile strength degrades beyond 10 wt. % and (ii) mechanical toughness declines due to membrane embrittlement. These are vital mechanical aspects but widely overlooked in the emergent field of MOF membranes and composites.
-
Niang, Pape Momar; Huang, Zhiwei; Dulong, Virginie; Souguir, Zied; Le Cerf, Didier; Picton, Luc
2016-03-30
Several thermo-sensitive polyelectrolyte complexes were prepared by ionic self-association between an anionic polysaccharide (alginate) and a monocationic copolymer (polyether amine, Jeffamine®-M2005) with a 'Low Critical Solubility Temperature' (LCST). We show that electro-association must be established below the aggregation temperature of the free Jeffamine®, after which the organization of the system is controlled by the thermo-association of Jeffamine® that was previously electro-associated with the alginate. Evidence for this comes primarily from the rheology in the semi-dilute region. Electro- and thermo-associative behaviours are optimal at a pH corresponding to maximum ionization of both compounds (around pH 7). High ionic strength could prevent the electro-association. The reversibility of the transition is possible only at temperatures lower than the LCST of Jeffamine®. Similar behaviour has been obtained with carboxymethyl cellulose (CMC), which suggests that this behaviour can be observed using a range of anionic polyelectrolytes. In contrast, no specific properties have been found for pullulan, which is a neutral polysaccharide. Copyright © 2015 Elsevier Ltd. All rights reserved.
-
Jang, Suk-Yong; Han, Sien-Ho
2016-12-19
Currently, Si as an active material for LIBs has been attracting much attention due to its high theoretical specific capacity (3572 mAh g -1 ). However, a disadvantage when using a Si negative electrode for LIBs is the abrupt drop of its capabilities during the cycling process. Therefore, there have been a few studies of polymers such as poly(vinylidene fluoride) (PVdF), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR) and polyacrylic acid (PAA) given that the robust structure of a polymeric binder to LIBs anodes is a promising means by which to enhance the performance of high-capacity anodes. These studies essentially focused mainly on modifying of the linear-polymer component or on copolymers dissolved in solvents. Cross-linking polymers as a binder may be preferred due to their good scratch resistance, excellent chemical resistance and high levels of adhesion and resilience. However, because these types of polymers (with a rigid structure and cross-linking points) are also insoluble in general organic solvents, applying these types in this capacity is virtually impossible.
-
International Nuclear Information System (INIS)
Zeng, Guangyong; He, Yi; Yu, Zongxue; Zhan, Yingqing; Ma, Lan; Zhang, Lei
2016-01-01
Highlights: • A novel TiO_2-HNTs/PVDF ultrafiltration membrane was prepared. • TiO_2 dispersed well in membrane matrix by loading on the surface of HNTs. • The hydrophilicity of membrane was improved with the addition of TiO_2-HNTs. • TiO_2-HNTs/PVDF membranes showed good antifouling performance. - Abstract: Novel polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared by blending with different contents of titanium dioxide-halloysite nanotubes (TiO_2-HNTs) composites into the PVDF matrix. The effects of TiO_2-HNTs content on the membrane performances, such as hydrophilicity, rejection ratio and antifouling properties were investigated in detail. X-ray diffraction (XRD), thermo-gravimetric analyzer (TGA) and scanning electron microscope (SEM) analyses showed that TiO_2 was loaded on the surface of HNTs successfully and homogeneously by sol-gel method. The morphologies and microstructure of the membranes were characterized by SEM and atomic force microscopy (AFM). The contact angle (CA) tests indicated that the hydrophilicity of membranes was significantly increased with the addition of TiO_2-HNTs. The pure water flux of 3%TiO_2-HNTs/PVDF was increased by 264.8% and 35.6%, respectively, compared with pure PVDF membrane and 3%TiO_2/PVDF membrane, although the rejection of bovine serum albumin (BSA) was slightly decreased. More importantly, TiO_2-HNTs/PVDF membrane exhibited an excellent anti-fouling performance, which was attributed to the hydrophobic contaminants being resisted by hydrophilic nanoparticles. It can be expected that this work may provide some references to solve the dispersion of nanoparticle in the membrane and improve the anti-fouling performance of membrane in the field of wastewater treatment.
-
Active material, optical mode and cavity impact on nanoscale electro-optic modulation performance
Amin, Rubab; Suer, Can; Ma, Zhizhen; Sarpkaya, Ibrahim; Khurgin, Jacob B.; Agarwal, Ritesh; Sorger, Volker J.
2017-10-01
Electro-optic modulation is a key function in optical data communication and possible future optical compute engines. The performance of modulators intricately depends on the interaction between the actively modulated material and the propagating waveguide mode. While a variety of high-performance modulators have been demonstrated, no comprehensive picture of what factors are most responsible for high performance has emerged so far. Here we report the first systematic and comprehensive analytical and computational investigation for high-performance compact on-chip electro-optic modulators by considering emerging active materials, model considerations and cavity feedback at the nanoscale. We discover that the delicate interplay between the material characteristics and the optical mode properties plays a key role in defining the modulator performance. Based on physical tradeoffs between index modulation, loss, optical confinement factors and slow-light effects, we find that there exist combinations of bias, material and optical mode that yield efficient phase or amplitude modulation with acceptable insertion loss. Furthermore, we show how material properties in the epsilon near zero regime enable reduction of length by as much as by 15 times. Lastly, we introduce and apply a cavity-based electro-optic modulator figure of merit, Δλ/Δα, relating obtainable resonance tuning via phase shifting relative to the incurred losses due to the fundamental Kramers-Kronig relations suggesting optimized device operating regions with optimized modulation-to-loss tradeoffs. This work paves the way for a holistic design rule of electro-optic modulators for high-density on-chip integration.
-
New membranes obtained by grafted irradiated PVDF foils
International Nuclear Information System (INIS)
Mazzei, R.; García Bermúdez, G.; Camporotondi, D.E.; Arbeitman, C.
2012-01-01
The present work describes a new method to produce membranes of poly(Acrylic-acid-Xmonomer) using the grafting procedure. PVDF foils irradiated with Ar + beam with energies between 30 and 150 keV were employed as substratum. Different combinations of monomers in water solutions were used: acrylic acid (AAc); acrylic acid–glycidyl methacrylate (AAc–GMA); acrylic acid–styrene (AAc–S), acrylic acid-N-isopropyl acrylamide (AAc–NIPAAm) and acrylic acid-N-isopropyl acrylamide–glycidyl methacrylate (AAc-NIPAAm–GMA). A large percentage of grafting results for specific values of: ion fluence and energy, AAc and sulfuric acid concentration, and different substrata PVDF polymorphous (alpha or beta). At a particular time of the grafting process, the poly(AAc-Xmonomer) membranes detach from the substratum and continue their grafting in the solution. This method is useful to produce increased replicated membranes of the irradiated original surface.
-
On the modelling of electro-viscoelastic response of electrostrictive polyurethane elastomers
International Nuclear Information System (INIS)
Ask, A; Menzel, A; Ristinmaa, M
2010-01-01
Electroactive polymers (EAP) deform under electric fields. This effect in fact generates various new fields of engineering applications of high technological interest. As an advantage, EAP may undergo deformations much larger than those capable by electroactive ceramics-however, to the price of acting at comparatively low forces. As common for polymers, EAP exhibit time-dependent material behaviour. The model proposed in this contribution, on the one hand, captures these electro-viscoelastic effects and, on the other hand, also nicely fits into iterative finite element formulations in order to simulate general boundary value problems. While the deformation itself as well as the electric potential are introduced as global degrees of freedom, the internal variables accounting for the viscous response are incorporated at the so-called local integration point level. Apart form calibrating the model against experimental data, a simple coupled finite element example is studied to show the applicability of the finite deformation electro-viscoelastic formulation proposed.
-
Some fundamental and applicative properties of [polymer/nano-SiC] hybrid nanocomposites
International Nuclear Information System (INIS)
Kassiba, A; Boucle, J; Makowska-Janusik, M; Errien, N
2007-01-01
Hybrid nanocomposites which combine polymer as host matrix and nanocrystals as active elements are promising functional materials for electronics, optics or photonics. In these systems, the physical response is governed by the nanocrystal features (size, surface and defect states), the polymer properties and the polymer-nanocrystal interface. This work reviews some selective nanostructured architectures based on active elements such as silicon carbide (SiC) nanocrystals and polymer host matrices. Beyond an overview of some key properties of the nanocrystals, a main part will be devoted to the electro-optical (EO) properties of SiC based hybrid systems where SiC nanocrystals are embedded in polymer matrices of different chemical nature such as poly-(methylmethacrylate) (PMMA), poly-vinylcarbazole (PVK) or polycarbonate. Using this approach, the organic-inorganic interface effects are emphasised with regard to the dielectric or hole transporting behaviour of PMMA and PVK respectively. These effects are illustrated through different EO responses associated with hybrid composites based on PMMA or PVK
-
Some fundamental and applicative properties of [polymer/nano-SiC] hybrid nanocomposites
Kassiba, A.; Bouclé, J.; Makowska-Janusik, M.; Errien, N.
2007-08-01
Hybrid nanocomposites which combine polymer as host matrix and nanocrystals as active elements are promising functional materials for electronics, optics or photonics. In these systems, the physical response is governed by the nanocrystal features (size, surface and defect states), the polymer properties and the polymer-nanocrystal interface. This work reviews some selective nanostructured architectures based on active elements such as silicon carbide (SiC) nanocrystals and polymer host matrices. Beyond an overview of some key properties of the nanocrystals, a main part will be devoted to the electro-optical (EO) properties of SiC based hybrid systems where SiC nanocrystals are embedded in polymer matrices of different chemical nature such as poly-(methylmethacrylate) (PMMA), poly-vinylcarbazole (PVK) or polycarbonate. Using this approach, the organic-inorganic interface effects are emphasised with regard to the dielectric or hole transporting behaviour of PMMA and PVK respectively. These effects are illustrated through different EO responses associated with hybrid composites based on PMMA or PVK.
-
New Results on Plasma Activated Bonding of Imprinted Polymer Features for Bio MEMS Applications
International Nuclear Information System (INIS)
Kettner, P; Pelzer, R L; Glinsner, T; Farrens, S; Lee, D
2006-01-01
Nanoimprint Lithography is a well-acknowledged low cost, high resolution, large area 3D patterning process for polymers. It includes the most promising methods: high pressure hot embossing (HE) and UV-Nanoimprint Lithography (UV-NIL). Curing of the imprinted structures is either done by cooling down below the glass transition temperature of the thermoplastic polymer in case of HE or by subsequent UV-light exposure and cross-linking in case of UV-NIL. Both techniques allow rapid prototyping for high volume production of fully patterned substrates for a wide range of materials. The advantages of using polymer substrates over common Micro-Electro-Mechanical Systems (MEMS) processing materials like glass, silicon or quartz are: bio-compatible surfaces, easy manufacturability, low cost for high volume production, suitable for use in micro- and nano-fabrication, low conductivity, wide range of optical properties just to name a few. We will present experimental results on HE processes with PMMA as well as UV-NIL imprints in selected UV-curable resists. In the second part of the work we will describe the bonding techniques for packaging of the micro or nano structures. Packaging of the imprinted features is a key technology for a wide variety of field of applications: μ-TAS, biochemistry, micro-mixers, micro-reactors, electrophoresis cells, life science, micro-optical and nano-optical applications (switches) nanofluidics, data storage, etc. for features down to sub-100 nm range. Most bonding techniques for polymer use adhesives as intermediate layers. We will demonstrate a promising technique for dense and very strong bonds using plasma activation of polymers and glass. This bonding technology allows for bonding at low temperatures well below the glass transition temperature of the polymers, which will ensure that the structures are not deformed
-
Near-Field Scanning Optical Microscope for the Study of Polymer-Nanotube Interactions
National Research Council Canada - National Science Library
Carroll, David
2000-01-01
... optical properties in comparison to the intrinsic polymers Recent absorption and luminescence studies of carbon nanotube composites based on electro-optic polymer hosts such as MEH-PPV, have revealed...
-
Dawande, Kiran; Patel, Swarnim; Bajpai, Rakesh; Keller, J. M.
2018-05-01
Thermally stimulated discharge currents in PVFO: PVDF blend samples of weight percentage ratio 80:20 and 95:05 prepared by the solution cast technique have been studied as function of polarizing temperature. Three distinct peaks are found at 60±10, 100±10, and 140 ±10 °C respectively. Activation energy values been calculated by initial rise method and it were found to range from 0.22 to 1.0 eV.
-
Energy Technology Data Exchange (ETDEWEB)
Wang, Xiaoguang; Wang, Weimin; Qi, Zhen; Zhao, Changchun; Ji, Hong; Zhang, Zhonghua [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (MOE), School of Materials Science and Engineering, Shandong University, Jingshi Road 73, Jinan 250061 (China)
2009-10-15
Nanoporous palladium (NPPd) with ultrafine ligament size of 3-6 nm was fabricated by dealloying of an Al-Pd alloy in an alkaline solution. Electrochemical measurements indicate that NPPd exhibits significantly high electrochemical active specific surface area (23 m{sup 2} g{sup -1}), and high catalytic activity for electro-oxidation of methanol, ethanol, and formic acid. Mass activities can reach 149, 148, 262 mA mg{sup -1} for the oxidation of methanol, ethanol and formic acid, respectively. Moreover, superior steady-state activities can be observed for all the electro-oxidation processes. NPPd will be a promising candidate for the anode catalyst for direct alcohol or formic acid fuel cells. (author)
-
Liu, Yiwei; Wang, Baomin; Zhan, Qingfeng; Tang, Zhenhua; Yang, Huali; Liu, Gang; Zuo, Zhenghu; Zhang, Xiaoshan; Xie, Yali; Zhu, Xiaojian; Chen, Bin; Wang, Junling; Li, Run-Wei
2014-01-01
The magnetic anisotropy is decreased with increasing temperature in normal magnetic materials, which is harmful to the thermal stability of magnetic devices. Here, we report the realization of positive temperature coefficient of magnetic anisotropy in a novel composite combining β-phase polyvinylidene fluoride (PVDF) with magnetostrictive materials (magnetostrictive film/PVDF bilayer structure). We ascribe the enhanced magnetic anisotropy of the magnetic film at elevated temperature to the st...
-
Influence of the dose rate in the PVDF degradation processes
Energy Technology Data Exchange (ETDEWEB)
Batista, Adriana S.M.; Pereira, Claubia, E-mail: adriananuclear@yahoo.com.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Gual, Maritza R., E-mail: maritzargual@gmail.com [Instituto Superior de Tecnologias y Ciencias Aplicadas (InsTEC), Departamento de Ingenieria Nuclear, La Habana (Cuba); Faria, Luiz O., E-mail: farialo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)
2015-07-01
Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from gamma radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation by products such as peroxide degradation. Radiation cross-linking technologies include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, polymer recycling, hydrogels etc. The degradation of PVDF polymer exposed to gamma irradiation in oxygen atmosphere in high dose rate has been studied and compared to obtained under smaller dose rates. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h and 2,592 kGy/h), with doses ranging from 100 kGy to 3,000 kGy. Different dose rate determine the prevalence of the processes being evaluated in this work by thermal measurements and infrared spectroscopy. It is shown that the degradation processes involve chain scissions and crosslink formation. The formation of oxidation products was shown at the surface of the irradiated film. The FTIR data revealed absorption bands at 1730 and 1853 cm{sup -1} which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm{sup -1} which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm{sup -1} which were associated with NH stretch of NH{sub 2} and OH. Thermogravimetric studies reveal that the irradiation induced the increasing residues and decrease of the temperature of the decomposition start. (author)
-
Influence of the dose rate in the PVDF degradation processes
International Nuclear Information System (INIS)
Batista, Adriana S.M.; Pereira, Claubia; Gual, Maritza R.; Faria, Luiz O.
2015-01-01
Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from gamma radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation by products such as peroxide degradation. Radiation cross-linking technologies include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, polymer recycling, hydrogels etc. The degradation of PVDF polymer exposed to gamma irradiation in oxygen atmosphere in high dose rate has been studied and compared to obtained under smaller dose rates. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h and 2,592 kGy/h), with doses ranging from 100 kGy to 3,000 kGy. Different dose rate determine the prevalence of the processes being evaluated in this work by thermal measurements and infrared spectroscopy. It is shown that the degradation processes involve chain scissions and crosslink formation. The formation of oxidation products was shown at the surface of the irradiated film. The FTIR data revealed absorption bands at 1730 and 1853 cm -1 which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm -1 which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm -1 which were associated with NH stretch of NH 2 and OH. Thermogravimetric studies reveal that the irradiation induced the increasing residues and decrease of the temperature of the decomposition start. (author)
-
New membranes obtained by grafted irradiated PVDF foils
Energy Technology Data Exchange (ETDEWEB)
Mazzei, R. [Unidad de Actividades Tecnologicas y Agropecuarias, Laboratorio de Polimeros, Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Universidad Tecnologica Nacional Facultad Regional, Buenos Aires (Argentina); Garcia Bermudez, G. [Gerencia de Investigacion y Aplicaciones, Laboratorio Tandar, Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, Universidad Nacional de General San Martin, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires (Argentina); Camporotondi, D.E., E-mail: camporotondi@cae.cnea.gov.ar [Unidad de Actividades Tecnologicas y Agropecuarias, Laboratorio de Polimeros, Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Arbeitman, C. [Gerencia de Investigacion y Aplicaciones, Laboratorio Tandar, Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires (Argentina); and others
2012-09-15
The present work describes a new method to produce membranes of poly(Acrylic-acid-Xmonomer) using the grafting procedure. PVDF foils irradiated with Ar{sup +} beam with energies between 30 and 150 keV were employed as substratum. Different combinations of monomers in water solutions were used: acrylic acid (AAc); acrylic acid-glycidyl methacrylate (AAc-GMA); acrylic acid-styrene (AAc-S), acrylic acid-N-isopropyl acrylamide (AAc-NIPAAm) and acrylic acid-N-isopropyl acrylamide-glycidyl methacrylate (AAc-NIPAAm-GMA). A large percentage of grafting results for specific values of: ion fluence and energy, AAc and sulfuric acid concentration, and different substrata PVDF polymorphous (alpha or beta). At a particular time of the grafting process, the poly(AAc-Xmonomer) membranes detach from the substratum and continue their grafting in the solution. This method is useful to produce increased replicated membranes of the irradiated original surface.
-
Ideris, N.; Ahmad, A. L.; Ooi, B. S.; Low, S. C.
2018-05-01
Microporous PVDF membranes were used as protein capture matrices in immunoassays. Because the most common labels in immunoassays were detected based on the colour change, an understanding of how protein concentration varies on different PVDF surfaces was needed. Herein, the correlation between the membrane pore size and protein adsorption was systematically investigated. Five different PVDF membrane morphologies were prepared and FTIR/ATR was employed to accurately quantify the surface protein concentration on membranes with small pore sizes. SigmaPlot® was used to find a suitable curve fit for protein adsorption and membrane pore size, with a high correlation coefficient, R2, of 0.9971.
-
Desenvolvimento de um acelerometro em PVDF e sua aplicação a sistemas vibratorios
Carlos Minor Tomiyoshi
1994-01-01
Resumo:O nível de voltagem gerado pelo acelerômetro em PVDF foi utilizado como parâmetro referencial para verificação da conformidade de sistemas mecânicos, de modo simples e direto. 0 método desenvolvido foi baseado em um novo tipo de acelerômetro, de concepção original, composto por duas películas piezelétricas em PVDF (Polyvinylidene Fluoride) e massa líquida (mercúrio) como elemento excitador. O acelerômetro em PVDF funcionou como um componente binário (on/off), para indicar se o nível de...
-
International Nuclear Information System (INIS)
Son, Dong-Ick; Kim, Ji-Hwan; Park, Dong-Hee; Choi, Won Kook; Li, Fushan; Ham, Jung Hun; Kim, Tae Whan
2008-01-01
The bistable effects of CdSe/ZnS nanoparticles embedded in a conducting poly N-vinylcarbazole (PVK) polymer layer by using flexible poly-vinylidene difluoride (PVDF) and polyethylene terephthalate (PET) substrates were investigated. Transmission electron microscopy (TEM) images revealed that CdSe/ZnS nanoparticles were formed inside the PVK polymer layer. Current-voltage (I-V) measurement on the Al/[CdSe/ZnS nanoparticles+ PVK]/ITO/PVDF and Al/[CdSe/ZnS nanoparticles+ PVK ]/ITO/PET structures at 300 K showed a nonvolatile electrical bistability behavior with a flat-band voltage shift due to the existence of the CdSe/ZnS nanoparticles, indicative of trapping, storing and emission of charges in the electronic states of the CdSe nanoparticles. A bistable behavior for the fabricated organic bistable device (OBD) structures is described on the basis of the I-V results. These results indicate that OBDs fabricated by embedding inorganic CdSe/ZnS nanoparticles in a conducting polymer matrix on flexible substrates are prospects for potential applications in flexible nonvolatile flash memory devices
-
Energy Technology Data Exchange (ETDEWEB)
Zeng, Guangyong [College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Oil & Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); He, Yi, E-mail: heyi@swpu.edu.cn [College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Oil & Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Yu, Zongxue; Zhan, Yingqing; Ma, Lan [College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Oil & Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Zhang, Lei, E-mail: zgc166929@sohu.com [College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Oil & Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, Sichuan 610500 (China)
2016-05-15
Highlights: • A novel TiO{sub 2}-HNTs/PVDF ultrafiltration membrane was prepared. • TiO{sub 2} dispersed well in membrane matrix by loading on the surface of HNTs. • The hydrophilicity of membrane was improved with the addition of TiO{sub 2}-HNTs. • TiO{sub 2}-HNTs/PVDF membranes showed good antifouling performance. - Abstract: Novel polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared by blending with different contents of titanium dioxide-halloysite nanotubes (TiO{sub 2}-HNTs) composites into the PVDF matrix. The effects of TiO{sub 2}-HNTs content on the membrane performances, such as hydrophilicity, rejection ratio and antifouling properties were investigated in detail. X-ray diffraction (XRD), thermo-gravimetric analyzer (TGA) and scanning electron microscope (SEM) analyses showed that TiO{sub 2} was loaded on the surface of HNTs successfully and homogeneously by sol-gel method. The morphologies and microstructure of the membranes were characterized by SEM and atomic force microscopy (AFM). The contact angle (CA) tests indicated that the hydrophilicity of membranes was significantly increased with the addition of TiO{sub 2}-HNTs. The pure water flux of 3%TiO{sub 2}-HNTs/PVDF was increased by 264.8% and 35.6%, respectively, compared with pure PVDF membrane and 3%TiO{sub 2}/PVDF membrane, although the rejection of bovine serum albumin (BSA) was slightly decreased. More importantly, TiO{sub 2}-HNTs/PVDF membrane exhibited an excellent anti-fouling performance, which was attributed to the hydrophobic contaminants being resisted by hydrophilic nanoparticles. It can be expected that this work may provide some references to solve the dispersion of nanoparticle in the membrane and improve the anti-fouling performance of membrane in the field of wastewater treatment.
-
4.4 V lithium-ion polymer batteries with a chemical stable gel electrolyte
Energy Technology Data Exchange (ETDEWEB)
Yamamoto, Takeru; Hara, Tomitaro; Akashi, Hiroyuki [Sony Corporation, Energy Business Group, R and D Division, 1-1 Aza, Shimosugishita, Takakura, Hiwada-machi, Koriyama-shi, Fukushima 963-0531 (Japan); Segawa, Ken; Honda, Kazuo [Sony Energy Device Corporation, PB Technology Center, 1-1 Aza, Shimosugishita, Takakura, Hiwada-machi, Koriyama-shi, Fukushima 963-0531 (Japan)
2007-12-06
We tested 4.2 V Li-ion polymer batteries (LIPB) with physical gel electrolyte, poly(vinylidene fluoride) (PVDF), 4.4 V LIPB and 4.4 V Li-ion batteries (LIB) with a liquid electrolyte. The discharge capacity of the 4.4 V LIPB reached 520 Wh l{sup -1} which was 9% higher than that of the 4.2 V LIPB. The 4.4 V LIPB had a high capacity retention ratio of 91.4% at 3 C because of the excellent ion conductivity of the PVDF gel. The capacity retention ratio of the 4.4 V LIPB was 82% after 500 cycles, which is comparable to those of some commercial LIBs. The 4.4 V LIPB retained its original thickness even after many cycles and after being stored at 90 C, whereas the 4.4 V LIB swelled by over 20%. Peaks in the FT-IR spectrum of the discolored separator in the 4.4 V LIB after storage were assigned to C=C double bonds, suggesting that the separator in direct contact with the 4.4 V cathode had been oxidized. The PVDF gel electrolyte not only had a high ionic conductivity but also completely suppressed oxidation. The 4.4 V LIPB with PVDF gel electrolyte has properties suitable for practical cells, namely, high energy density, high permanence and it is safe to use. (author)
-
Energy Technology Data Exchange (ETDEWEB)
Iyore, O.D.; Roodenko, K.; Winkler, P.S. [Materials Science and Engineering Department, The University of Texas at Dallas, Richardson, TX 75080 (United States); Noriega, J.R.; Vasselli, J.J. [Electrical Engineering Department, The University of Texas at Tyler, Tyler, TX 75799 (United States); Chabal, Y.J. [Materials Science and Engineering Department, The University of Texas at Dallas, Richardson, TX 75080 (United States); Gnade, B.E., E-mail: gnade@utdallas.edu [Materials Science and Engineering Department, The University of Texas at Dallas, Richardson, TX 75080 (United States)
2013-12-02
We report the characterization of photo-crosslinked polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) thin film, metal–insulator–metal capacitors fabricated using standard semiconductor processing techniques. We characterize the capacitors using in-situ vibrational spectroscopy during thermally-assisted poling and correlate the Fourier transform infrared spectroscopy (FTIR) results with X-ray diffraction (XRD) results. FTIR analysis of the neat PVDF-HFP showed α → β transformations during poling at room temperature and at 55 °C. α → β transformations were observed for the crosslinked polymer only during poling at 55 °C. XRD data revealed that photo-crosslinking caused the polymer to partially crystallize into the β-phase. The similar behavior of the neat and crosslinked samples at 55 °C suggests that a higher activation energy was needed for α → β transformations in crosslinked PVDF-HFP during poling. Electrical measurements showed that photo-crosslinking had no significant effect on the dielectric constant and dielectric loss of PVDF-HFP. However, the dielectric strength and maximum energy density of the crosslinked polymer were severely reduced. - Highlights: • Polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) dielectrics were studied. • Phase transformations were observed only at 55 °C for the crosslinked PVDF-HFP. • Crosslinking had no strong effect on the dielectric constant of PVDF-HFP. • Breakdown strengths were 620 MVm{sup −1} and 362 MVm{sup −1} for neat and crosslinked films.
-
Yu, Gui-Feng; Yan, Xu; Yu, Miao; Jia, Meng-Yang; Pan, Wei; He, Xiao-Xiao; Han, Wen-Peng; Zhang, Zhi-Ming; Yu, Liang-Min; Long, Yun-Ze
2016-01-01
A facile fabrication strategy via electrospinning and followed by in situ polymerization to fabricate a patterned, highly stretchable, and conductive polyaniline/poly(vinylidene fluoride) (PANI/PVDF) nanofibrous membrane is reported. Owing to the patterned structure, the nanofibrous PANI/PVDF strain sensor can detect a strain up to 110%, for comparison, which is 2.6 times higher than the common nonwoven PANI/PVDF mat and much larger than the previously reported values (usually less than 15%). Meanwhile, the conductivity of the patterned strain sensor shows a linear response to the applied strain in a wide range from 0% to about 85%. Additionally, the patterned PANI/PVDF strain sensor can completely recover to its original electrical and mechanical values within a strain range of more than 22%, and exhibits good durability over 10 000 folding-unfolding tests. Furthermore, the strain sensor also can be used to detect finger motion. The results demonstrate promising application of the patterned nanofibrous membrane in flexible electronic fields.A facile fabrication strategy via electrospinning and followed by in situ polymerization to fabricate a patterned, highly stretchable, and conductive polyaniline/poly(vinylidene fluoride) (PANI/PVDF) nanofibrous membrane is reported. Owing to the patterned structure, the nanofibrous PANI/PVDF strain sensor can detect a strain up to 110%, for comparison, which is 2.6 times higher than the common nonwoven PANI/PVDF mat and much larger than the previously reported values (usually less than 15%). Meanwhile, the conductivity of the patterned strain sensor shows a linear response to the applied strain in a wide range from 0% to about 85%. Additionally, the patterned PANI/PVDF strain sensor can completely recover to its original electrical and mechanical values within a strain range of more than 22%, and exhibits good durability over 10 000 folding-unfolding tests. Furthermore, the strain sensor also can be used to detect finger
-
Haptic device development based on electro static force of cellulose electro active paper
Yun, Gyu-young; Kim, Sang-Youn; Jang, Sang-Dong; Kim, Dong-Gu; Kim, Jaehwan
2011-04-01
Haptic is one of well-considered device which is suitable for demanding virtual reality applications such as medical equipment, mobile devices, the online marketing and so on. Nowadays, many of concepts for haptic devices have been suggested to meet the demand of industries. Cellulose has received much attention as an emerging smart material, named as electro-active paper (EAPap). The EAPap is attractive for mobile haptic devices due to its unique characteristics in terms of low actuation power, suitability for thin devices and transparency. In this paper, we suggest a new concept of haptic actuator with the use of cellulose EAPap. Its performance is evaluated depending on various actuation conditions. As a result, cellulose electrostatic force actuator shows a large output displacement and fast response, which is suitable for mobile haptic devices.
-
Liato, Viacheslav; Hammami, Riadh; Aïder, Mohammed
2017-06-01
The aim of this work was to study the potential of diluted electro-activated solutions of weak organic acid salts (potassium acetate, potassium citrate and calcium lactate) to extend the shelf life of blueberries during post-harvest storage. The sanitizing capacity of these solutions was studied against pathogenic bacteria Listeria monocytogenes and E. coli O157:H7 as well as phytopathogenic fungi A. alternata, F. oxysporum and B. cinerea. The results showed that a 5-min treatment of inoculated blueberries with electro-activated solutions resulted in a 4 log CFU/g reduction in Listeria monocytogenes for all solutions. For E. coli O157:H7, the electro-activated potassium acetate and potassium citrate solutions achieved a decrease of 3.5 log CFU/g after 5 min of berry washing. The most important fungus reduction was found when blueberries were washed with an electro-activated solution of potassium acetate and a NaOCl solution. After 5 min of blueberry washing with an electro-activated potassium acetate solution, a very high reduction effect was observed for A. alternata, F. oxysporum and B. cinerea, which showed survival levels of only 2.2 ± 0.16, 0.34 ± 0.15 and 0.21 ± 0.16 log CFU/g, respectively. Regarding the effect of the washing on the organoleptic quality of blueberries, the obtained results showed no negative effect on the product color or textural profile. Finally, this work suggests that washing with electro-activated solutions of weak organic acid salts can be used to enhance the shelf-life of blueberries during post-harvest storage. Copyright © 2016 Elsevier Ltd. All rights reserved.
-
Electro-mechanical properties of hydrogel composites with micro- and nano-cellulose fillers
International Nuclear Information System (INIS)
Shahid U N, Mohamed; Deshpande, Abhijit P; Rao, C Lakshmana
2015-01-01
Stimuli responsive cross-linked hydrogels are of great interest for applications in diverse fields such as sensors and biomaterials. In this study, we investigate polymer composites filled with cellulose fillers. The celluloses used in making the composites were a microcrystalline cellulose of commercial grade and cellulose nano-whiskers obtained through acid hydrolysis of microcrystalline cellulose. The filler concentration was varied and corresponding physical, mechanical and electro-mechanical characterization was carried out. The electro-mechanical properties were determined using a quasi-static method. The fillers not only enhance the mechanical properties of the composite by providing better reinforcement but also provide a quantitative electric potential in the composite. The measurements reveal that the polymer composites prepared from two different cellulose fillers possess a quantitative electric potential which can be utilized in biomedical applications. It is argued that the mechanism behind the quantitative electric potential in the composites is due to streaming potentials arising due to electrical double layer formation. (paper)
-
Li, Zetang; Zhang, Xu; Li, Guanghe
2014-03-28
A PVDF-ZnO nanowires (NWs) hybrid generator (PZHG) was designed. A simple, cost effective method to produce the PVDF β phase by nano force is introduced. With the ZnO NWs growing, the in situ nano extension force promotes the phase change. A theoretical analysis of the ZnO NWs acting as a self-rectifier of the nano generator is established. The ZnO NWs acted as a self-adjustment diode to control the current output of the PZHG by piezo-electric and semi-conductive effects. Based on the self-controllability of the piezoelectric output, three kinds of finger touching are distinguished by the output performances of the PZHG, which is applicable to an LCD touch pad.
-
Sahoo, Bichitra Nanda; Balasubramanian, Kandasubramanian
2014-12-15
We have elucidated a cost effective fabrication technique to produce superhydrophobic polyvinylidene fluoride (PVDF/DMF/candle soot particle and PVDF/DMF/camphor soot particle composite) porous materials. The water repellent dry composite was formed by the interaction of non-solvent (methanol) into PVDF/carbon soot particles suspension in N,N-dimethylformamide (DMF). It is seen that longer quenching time effectively changes the surface morphology of dry composites. The nano broccoli like hierarchical microstructure with micro or nano scaled roughen surface was obtained for PVDF/DMF/camphor soot particle, which reveals water contact angle of 172° with roll off angle of 2°. However, composite coating of PVDF/DMF/candle soot particle shows nano cauliflower like hierarchical, which illustrates water contact angle of 169° with roll off angle of 3°. To elucidate the enhancement of water repellent property of PVDF composites, we further divulge the evolution mechanism of nano cauliflower and nano broccoli structure. In order to evaluate the water contact angle of PVDF composites, surface diffusion of water inside the pores is investigated. Furthermore, the addition of small amount of carbon soot particles in composite not only provides the crystallization of PVDF, but also leads to dramatical amendment of surface morphology which increases the surface texture and roughness for superhydrophobicity. Copyright © 2014 Elsevier Inc. All rights reserved.
-
Abolhasani, Mohammad Mahdi; Naebe, Minoo; Jalali-Arani, Azam; Guo, Qipeng
2014-01-01
In this paper, intercalation of nanoclay in the miscible polymer blend of poly(vinylidene fluoride) (PVDF) and acrylic rubber(ACM) was studied. X-ray diffraction was used to investigate the formation of nanoscale polymer blend/clay hybrid. Infrared spectroscopy and X-ray analysis revealed the coexistence of β and γ crystalline forms in PVDF/Clay nanocomposite while α crystalline form was found to be dominant in PVDF/ACM/Clay miscible hybrids. Flory-Huggins interaction parameter (B) was used to further explain the miscibility phenomenon observed. The B parameter was determined by combining the melting point depression and the binary interaction model. The estimated B values for the ternary PVDF/ACM/Clay and PVDF/ACM pairs were all negative, showing both proper intercalation of the polymer melt into the nanoclay galleries and the good miscibility of PVDF and ACM blend. The B value for the PVDF/ACM blend was almost the same as that measured for the PVDF/ACM/Clay hybrid, suggesting that PVDF chains in nanocomposite hybrids interact with ACM chains and that nanoclay in hybrid systems is wrapped by ACM molecules.
-
Directory of Open Access Journals (Sweden)
N. Eguchi
2017-10-01
Full Text Available Electrochemical preparation of a composite consisting of poly[2,2′-bis(3,4-ethylenedioxythiophene-alt-fluorene] and hydroxypropyl cellulose (PEFE/HPC was carried out. We conducted electrochemical polymerization of poly[2,2′-bis(3,4-ethylenedioxythiophene-alt-fluorene] (EFE as a monomer in a lyotropic liquid crystal of HPC. We used an organic solvent instead of water for lyotropic liquid crystal medium to expand the possibility of the range of monomers, although water is usually employed as a solvent for HPC for showing liquid crystallinity. Here, we employed N,N-dimethylformamide (DMF as a solvent for HPC. Electrochemical polymerization in the polymer liquid crystal was carried out to obtain a polymer film with liquid crystal order. The polymer film thus prepared exhibited optical activity. Fourier transfer infrared (FT-IR absorption spectroscopy reveals that the film is a composite consisting of HPC and polymer. The composite PEFE/HPC thus prepared in HPC/DMF system showed electrochromism.
-
Khalifa, Mohammed; Deeksha, B.; Mahendran, Arunjunairaj; Anandhan, S.
2018-03-01
Poly(vinlylidene fluoride) (PVDF) is known for its electroactive phases, which can be nucleated by incorporating nanoparticles into PVDF to enhance its piezoelectric performance. In this study, the synergistic effect of electrospinning and nano alumina trihydrate (ATH) filler was used to enhance the electroactive β phase of PVDF. Electrospun nanofibers of PVDF/ATH nanocomposite (PANCF) were synthesized with different loadings of ATH. The presence of ATH enhances the surface charges of the electrospun droplets, leading to thinner fibers. The highest β-phase content was found to be 70.1% for PANCF with 10% ATH. The piezoelectric performance of the nanofiber mats was studied using an indigenous setup. The highest voltage output of 840 mV was produced by PANCF with 10% ATH. These nanofibers could be a promising material in the field of sensors, actuators and energy-harvesting applications.
-
Preliminary study on gas separation performance of flat sheet mixed matrix (PVDF/Zeolite)
Rahman, Sunarti Abd; Abdalla Suliman Haron, Gamal; Krishna Roshan Kanasan, Raj; Hasbullah, Hasrinah
2018-04-01
Membrane separation has attracted a lot of attention over the last years mainly due to its separation ability, operational capability and economical viability. Mixed matrix membrane (MMM) combines the superior transport and selectivity properties of inorganic membrane materials and the excellent fabrication properties of organic polymers. This emerging technology can be utilized to purify biogas which can be used in a variety of applications. In this study, flat sheet mixed matrix membranes were synthesized with different percentages of N-Mehtyl-2-pyrrolidone (NMP) as solvent, Polyvinylidene Fluoride (PVDF) as the polymer matrix and zeolite 4A as the dispersed fine particles, membrane A (80: 20: 0), membrane B (80: 18: 2), membrane C (80: 15: 5), and membrane D (75: 15: 10) respectively. The membranes were fabricated using dry/wet phase inversion method. The membrane’s performance in terms of permeability and selectivity was examined using the single gas permeation device. The general trend was that, the permeability of the two gases (CO2/CH4) decreased with the increase of the pressure (0.5, 1, 1.5) bar. Membrane D was found to be suitable to separate the pair gas (CO2/CH4) as the permeability was 65623.412, Barrer and 15587.508, Barrer respectively, and its selectivity for was 4.21 at 0.5 bar.
-
Energy Technology Data Exchange (ETDEWEB)
Cedrola, S.M.L.; Costa, M.F. da; Pasqualino, I.P., E-mail: samanta@metalmat.ufrj.b [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)
2010-07-01
Pipelines are of great concern in the transport sector of oil and gas industries, mainly due to the natural internal aging process caused by contact with the different transported fluids. Installation of polymeric pipes called liners is a good option for rehabilitation of long segments of deteriorated pipelines. Among the potential materials for such application is Poly (vinylidene fluoride) (PVDF). Meanwhile the installation process cannot be carried out in one single step and the polymeric pipe must be cut in sections that are welded during the installation process. In this research welding methodology was studied aiming to optimize welding conditions and the mechanical properties of the joined materials. The first step was processing the PVDF via compression molding on different conditions. Then, the sample was cut and butt-welded. Welding parameters such as, time control, temperature and contact pressure were studied. Afterwards, the stress-strain properties of the welded material was evaluated and physical characterization was carried by x-ray diffraction (DRX). (author)
-
Energy Technology Data Exchange (ETDEWEB)
Rahmani, Ali Reza; Azarian, Ghasem; Berizi, Zohreh [Hamadan University of Medical Sciences, Hamadan (Iran, Islamic Republic of); Nematollahi, Davood [Bu-Ali-Sina University, Hamadan (Iran, Islamic Republic of); Godini, Kazem [Ilam University of Medical Sciences, Ilam (Iran, Islamic Republic of)
2015-08-15
This study was conducted to evaluate the mineralization of activated sludge (MAS) by a facile and environmentally friendly electro-Fenton process (EFP). The effects of initial H{sub 2}O{sub 2} concentration, pH value, applied current density and operating time on MAS through determining the removal rate of chemical oxygen demand (COD) and total coliform (TC) were studied. 72% of COD was removed by indirect oxidation double-mediated based on the electro- generation of hydroxyl radical and active chlorine, under the following optimum conditions: 127mmol L{sup -}1 of hydrogen peroxide, pH=3.0, 10 mA cm{sup -}2 of DC current, 120min of operating time, and 0.22mol L{sup -}1 of NaCl as the supporting electrolyte. Only in 10 min and pH 3.0 approximately 100% of TC was removed. The findings indicated that EFP can be applied efficiently for MAS by selecting appropriate operating conditions. The bottom line is that the process is entirely effective owing to the application of green oxidants (hydroxyl radical and active chlorine) and lack of being influenced by environmental situations, which can be introduced as an alternative to current conventional methods.
-
International Nuclear Information System (INIS)
Rahmani, Ali Reza; Azarian, Ghasem; Berizi, Zohreh; Nematollahi, Davood; Godini, Kazem
2015-01-01
This study was conducted to evaluate the mineralization of activated sludge (MAS) by a facile and environmentally friendly electro-Fenton process (EFP). The effects of initial H 2 O 2 concentration, pH value, applied current density and operating time on MAS through determining the removal rate of chemical oxygen demand (COD) and total coliform (TC) were studied. 72% of COD was removed by indirect oxidation double-mediated based on the electro- generation of hydroxyl radical and active chlorine, under the following optimum conditions: 127mmol L - 1 of hydrogen peroxide, pH=3.0, 10 mA cm - 2 of DC current, 120min of operating time, and 0.22mol L - 1 of NaCl as the supporting electrolyte. Only in 10 min and pH 3.0 approximately 100% of TC was removed. The findings indicated that EFP can be applied efficiently for MAS by selecting appropriate operating conditions. The bottom line is that the process is entirely effective owing to the application of green oxidants (hydroxyl radical and active chlorine) and lack of being influenced by environmental situations, which can be introduced as an alternative to current conventional methods.
-
Hydrophobic Hyflon® AD/PVDF membranes for butanol dehydration via pervaporation
Jalal, Taghreed; Bettahalli Narasimha, Murthy Srivatsa; Le, Ngoc Lieu; Nunes, Suzana Pereira
2015-01-01
Novel hydrophobic Hyflon® AD /PVDF membranes were developed and investigated for n-butanol dehydration via pervaporation. The coating protocols for thin defect-free Hyflon® AD selective layer on the PVDF support was optimized. Water and n-butanol transport was measured, analyzing the effect of operating conditions. The water flux through the newly developed membranes was higher than 150 g/m2.h with selectivity for water higher than 99 wt %. The focus was on the use of Hyflon® AD as the selective layer for n-butanol dehydration. The membrane application can be extended to other solvents, supporting an effective and simple method for dehydration with hydrophobic membranes.
-
Hydrophobic Hyflon® AD/PVDF membranes for butanol dehydration via pervaporation
Jalal, Taghreed
2015-10-21
Novel hydrophobic Hyflon® AD /PVDF membranes were developed and investigated for n-butanol dehydration via pervaporation. The coating protocols for thin defect-free Hyflon® AD selective layer on the PVDF support was optimized. Water and n-butanol transport was measured, analyzing the effect of operating conditions. The water flux through the newly developed membranes was higher than 150 g/m2.h with selectivity for water higher than 99 wt %. The focus was on the use of Hyflon® AD as the selective layer for n-butanol dehydration. The membrane application can be extended to other solvents, supporting an effective and simple method for dehydration with hydrophobic membranes.
-
International Nuclear Information System (INIS)
Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B.
2011-01-01
Polymers exhibiting ion exchange capacity are studied for many years due to their application in several fields, such as membranes for proton exchange fuel cells, filtration membranes, heavy ions recovery and artificial muscles and sensors. Radiation induced grafting followed by sulfonation is a well-known way to obtain ion exchange polymers. Fluorinated polymers are frequently used as polymeric matrix for grafting due to their excellent physicochemical properties. Radiation induced grafting of styrene into poly (vinylidene fluoride) (PVDF) by simultaneous method in 1:1 styrene/toluene or styrene/N,N-dimethylformamide solutions was studied. Irradiations were performed under nitrogen atmosphere, room temperature and at doses of 5, 10 and 20 kGy with dose rate of 5 kGy.h -1 from a 60 Co gamma source. After washing, grafted materials were sulfonated in 10% chlorosulfonic acid/1,2-dichloroethane solutions for 4 h at room temperature. Characterization shows that increasing irradiation dose corresponds to increases in the grafting yield (GY %) gravimetrically calculated and these different solvents shows different grafting behaviors. Toluene allows no more than 3 % of grafting while DMF allows up to 55 % of grafting in the same condition. Grafting in toluene solution occurs on the surface and in DMF solution it occurs in the bulk, as confirmed by SEM. Both irradiation doses and solvent used have direct effects in the ion exchange capacities (calculated after titrations). FT-IR spectra exhibit new peaks after grafting and after sulfonation, attributed to grafted monomer and sulfonic groups attached to the styrene. DSC shows differences in thermal behavior of the polymer before and after each step. (author)
-
Energy Technology Data Exchange (ETDEWEB)
Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2011-07-01
Polymers exhibiting ion exchange capacity are studied for many years due to their application in several fields, such as membranes for proton exchange fuel cells, filtration membranes, heavy ions recovery and artificial muscles and sensors. Radiation induced grafting followed by sulfonation is a well-known way to obtain ion exchange polymers. Fluorinated polymers are frequently used as polymeric matrix for grafting due to their excellent physicochemical properties. Radiation induced grafting of styrene into poly (vinylidene fluoride) (PVDF) by simultaneous method in 1:1 styrene/toluene or styrene/N,N-dimethylformamide solutions was studied. Irradiations were performed under nitrogen atmosphere, room temperature and at doses of 5, 10 and 20 kGy with dose rate of 5 kGy.h{sup -1} from a {sup 60}Co gamma source. After washing, grafted materials were sulfonated in 10% chlorosulfonic acid/1,2-dichloroethane solutions for 4 h at room temperature. Characterization shows that increasing irradiation dose corresponds to increases in the grafting yield (GY %) gravimetrically calculated and these different solvents shows different grafting behaviors. Toluene allows no more than 3 % of grafting while DMF allows up to 55 % of grafting in the same condition. Grafting in toluene solution occurs on the surface and in DMF solution it occurs in the bulk, as confirmed by SEM. Both irradiation doses and solvent used have direct effects in the ion exchange capacities (calculated after titrations). FT-IR spectra exhibit new peaks after grafting and after sulfonation, attributed to grafted monomer and sulfonic groups attached to the styrene. DSC shows differences in thermal behavior of the polymer before and after each step. (author)
-
Deposition of a thin electro-polymerized organic film on iron surface
International Nuclear Information System (INIS)
Lecayon, Gerard
1980-01-01
We use an electrochemical method to prepare a polymerized thin film, obtained from acrylonitrile in a solution of acetonitrile and tetraethylammonium perchlorate. The films are deposited on oxidized iron electrodes, with a surface area varying from a few mm to several cm, their thickness ranges from ten A to thousand A. This result is obtained by controlling the evolution of reactions: duplication, hydrogenation, polymerization which occur during the electrochemical reduction of acrylonitrile. The choice of suitable experimental conditions enhances the polymerization and increases the adherence of the polymer on the electrode. The usual methods of surface studies: S.E.M., A.E.S., S.I.M.S., permit the characterization of the electrode surface and the chemical composition of the deposit films. The molecular structure of polymer, and its evolution under aging or heating was studied by infrared multi-reflection spectroscopy. Very good correlation exists between the electrochemical characteristic: I = f(t), the initial surface state of the electrodes, and the homogeneity of the electro-polymerized films. Diagrams corresponding to mechanisms of different stages of electro-polymerization are proposed. (author) [fr
-
Energy Technology Data Exchange (ETDEWEB)
Taer, E.; Awitdrus,; Farma, R. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Department of Physics, Faculty of Mathematics and Natural Sciences, University of Riau, 28293 Pekanbaru, Riau (Indonesia); Deraman, M., E-mail: madra@ukm.my; Talib, I. A.; Ishak, M. M.; Omar, R.; Dolah, B. N. M.; Basri, N. H.; Othman, M. A. R. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Kanwal, S. [ICCBS, H.E.J. Research Institute of Chemistry, University of Karachi, 75270 Karachi (Pakistan)
2015-04-16
Activated carbon powders (ACP) were produced from the KOH treated pre-carbonized rubber wood sawdust. Different conductive materials (graphite, carbon black and carbon nanotubes (CNTs)) were added with a binder (polivinylidene fluoride (PVDF)) into ACP to improve the supercapacitive performance of the activated carbon (AC) electrodes. Symmetric supercapacitor cells, fabricated using these AC electrodes and 1 molar H{sub 2}SO{sub 4} electrolyte, were analyzed using a standard electrochemical impedance spectroscopy technique. The addition of graphite, carbon black and CNTs was found effective in reducing the cell resistance from 165 to 68, 23 and 49 Ohm respectively, and increasing the specific capacitance of the AC electrodes from 3 to 7, 17, 32 F g{sup −1} respectively. Since the addition of CNTs can produce the highest specific capacitance, CNTs were chosen as a conductive material to produce AC composite electrodes that were added with 2.5 %, 5 % and 10 % (by weight) electro-active material namely ruthenium oxide; PVDF binder and CNTs contents were kept at 5 % by weight in each AC composite produced. The highest specific capacitance of the cells obtained in this study was 86 F g{sup −1}, i.e. for the cell with the resistance of 15 Ohm and composite electrode consists of 5 % ruthenium oxide.
-
Effect of roll hot press temperature on crystallite size of PVDF film
Energy Technology Data Exchange (ETDEWEB)
Hartono, Ambran, E-mail: ambranhartono@yahoo.com; Sanjaya, Edi [Departement of Physics Faculty of Science and Technology, Islamic State University Syarif Hidayatullah , Jl. Juanda 95 Ciputat Jakarta (Indonesia); Djamal, Mitra; Satira, Suparno; Bahar, Herman [Theoretical High Energy Physics and Instrumentation Group Research, Faculty Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung (Indonesia); Ramli [Departement of Physics, Faculty of Mathematics and Natural Sciences, Universitas Negeri Padang, Jl.Prof. Hamka, Padang 25131 (Indonesia)
2014-03-24
Fabrication PVDF films have been made using Hot Roll Press. Preparation of samples carried out for nine different temperatures. This condition is carried out to see the effect of Roll Hot Press temperature on the size of the crystallite of PVDF films. To obtain the diffraction pattern of sample characterization is performed using X-Ray Diffraction. Furthermore, from the diffraction pattern is obtained, the calculation to determine the crystallite size of the sample by using the Scherrer equation. From the experimental results and the calculation of crystallite sizes obtained for the samples with temperature 130 °C up to 170 °C respectively increased from 7.2 nm up to 20.54 nm. These results show that increasing temperatures will also increase the size of the crystallite of the sample. This happens because with the increasing temperature causes the higher the degree of crystallization of PVDF film sample is formed, so that the crystallite size also increases. This condition indicates that the specific volume or size of the crystals depends on the magnitude of the temperature as it has been studied by Nakagawa.
-
Glauß, Benjamin; Steinmann, Wilhelm; Walter, Stephan; Beckers, Markus; Seide, Gunnar; Gries, Thomas; Roth, Georg
2013-07-03
This research explains the melt spinning of bicomponent fibers, consisting of a conductive polypropylene (PP) core and a piezoelectric sheath (polyvinylidene fluoride). Previously analyzed piezoelectric capabilities of polyvinylidene fluoride (PVDF) are to be exploited in sensor filaments. The PP compound contains a 10 wt % carbon nanotubes (CNTs) and 2 wt % sodium stearate (NaSt). The sodium stearate is added to lower the viscosity of the melt. The compound constitutes the fiber core that is conductive due to a percolation CNT network. The PVDF sheath's piezoelectric effect is based on the formation of an all-trans conformation β phase, caused by draw-winding of the fibers. The core and sheath materials, as well as the bicomponent fibers, are characterized through different analytical methods. These include wide-angle X-ray diffraction (WAXD) to analyze crucial parameters for the development of a crystalline β phase. The distribution of CNTs in the polymer matrix, which affects the conductivity of the core, was investigated by transmission electron microscopy (TEM). Thermal characterization is carried out by conventional differential scanning calorimetry (DSC). Optical microscopy is used to determine the fibers' diameter regularity (core and sheath). The materials' viscosity is determined by rheometry. Eventually, an LCR tester is used to determine the core's specific resistance.
-
Bifunctional Pt-Si Alloys for Small Organic Molecule Electro-oxidation
DEFF Research Database (Denmark)
Permyakova, Anastasia Aleksandrovna; Suntivich, Jin; Han, Binghong
Designing highly active catalysts for electro-oxidation of small organic molecules can help to reduce the anodic overpotential for more efficient utilization of hydrocarbon fuels. The challenge in developing more active electrocatalysts for electro-oxidation reactions is to satisfy the stringent...... adsorption site. We will discuss the enhanced activity of Pt-Si alloys for small organic molecule oxidation, which can be attributed to the improved CO electro-oxidation kinetics on Pt-Si....
-
Directory of Open Access Journals (Sweden)
Yue Li
2017-09-01
Full Text Available In the past few decades, Poly(vinylidene fluoride/Polymethylmethacrylate (PVDF/PMMA binary blend has attracted substantial attention in the scientific community due to possible intriguing mechanical, optical and ferroelectric properties that are closely related to its multiple crystal structures/phases. However, the effect of PMMA phase on the polymorphism of PVDF, especially the relationship between miscibility and polymorphism, remains an open question and is not yet fully understood. In this work, three series of particle blends with varied levels of miscibility between PVDF and PMMA were prepared via seeded emulsion polymerization: PVDF–PMMA core–shell particle (PVDF@PMMA with high miscibility; PVDF/PMMA latex blend with modest miscibility; and PVDF@c–PMMA (crosslinked PMMA core–shell particle with negligible miscibility. The difference in miscibility, and the corresponding morphology and polymorphism were systematically studied to correlate the PMMA/PVDF miscibility with PVDF polymorphism. It is of interest to observe that the formation of polar β/γ phase during melt crystallization could be governed in two ways: dipole–dipole interaction and fast crystallization. For PVDF@PMMA and PVDF/PMMA systems, in which fast crystallization was unlikely triggered, higher content of β/γ phase, and intense suppression of crystallization temperature and capacity were observed in PVDF@PMMA, because high miscibility favored a higher intensity of overall dipole–dipole interaction and a longer interaction time. For PVDF@c–PMMA system, after a complete coverage of PVDF seeds by PMMA shells, nearly pure β/γ phase was obtained owing to the fast homogeneous nucleation. This is the first report that high miscibility between PVDF and PMMA could favor the formation of β/γ phase.
-
Study of the Melting Latent Heat of Semicrystalline PVDF applied to High Gamma Dose Dosimetry
Energy Technology Data Exchange (ETDEWEB)
Batista, Adriana S.M. [Departamento de Anatomia e Imagem - IMA, Universidade Federal de Minas Gerais, Av. Prof. Alfredo Balena, 190, 30130-100, Belo Horizonte, MG (Brazil); Gual, Maritza R.; Faria, Luiz O. [Centro de Desenvolvimento da Tecnologia Nuclear - CDTN, Av. Antonio Carlos 6627, C.P. 941, 31270-901, Belo Horizonte, MG (Brazil); Lima, Claubia P.B. [Departamento de Engenharia Nuclear - DEN, Universidade Federal de Minas Gerais - UFMG, Av. Antonio Carlos 6627, 31270-970 Belo Horizonte, MG (Brazil)
2015-07-01
Poly(vinylidene fluoride) homopolymers [PVDF] homopolymers were irradiated with gamma doses ranging from 0.5 to 2.75 MGy. Differential scanning calorimetry (DSC) and FTIR spectrometry were used in order to study the effects of gamma radiation in the amorphous and crystalline polymer structures. The FTIR data revealed absorption bands at 1730 and 1853 cm{sup -1} which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm{sup -1} which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm{sup -1} which were associated with NH stretch of NH{sub 2} and OH. The melting latent heat (LM) measured by DSC was used to construct an unambiguous relationship with the delivered dose. Regression analyses revealed that the best mathematical function that fits the experimental calibration curve is a 4-degree polynomial function, with an adjusted Rsquare of 0.99817. (authors)
-
International Nuclear Information System (INIS)
Gros, Pierre
1996-01-01
This research thesis reports a study which aims at developing, analyzing and integrating an electrode-enzyme interface within an electro-enzymatic reactor to develop electrochemical biosensors. The adopted method comprises a confinement of the enzyme at the electrode surface by means of an electro-formed poly-pyrrole film. The author reports an experimental and theoretical study of the coupling between electrochemical reaction, enzymatic reaction and matter transfer in the polymer in order to better understand the operation of so-modified electrodes. Different parameters have an influence on the reaction rate. A numerical model (validated by experiments) allows the identification of the reaction limiting stages. A new elaboration protocol allows the polymer permeability to be increased. The interface is first applied to the reduction of the NAD coenzyme, and the process is also applied to the production of gluconic acid [fr
-
Kamkar, Milad; Aliabadian, Ehsan; Shayesteh Zeraati, Ali; Sundararaj, Uttandaraman
2018-02-01
Carbon nanotube (CNT)/polymer nanocomposites exhibit excellent electrical properties by forming a percolated network. Adding a secondary filler can significantly affect the CNTs' network, resulting in changing the electrical properties. In this work, we investigated the effect of adding manganese dioxide nanowires (MnO2NWs) as a secondary nanofiller on the CNTs' network structure inside a poly(vinylidene fluoride) (PVDF) matrix. Incorporating MnO2NWs to PVDF/CNT samples produced a better state of dispersion of CNTs, as corroborated by light microscopy and transmission electron microscopy. The steady shear and oscillatory shear flows were employed to obtain a better insight into the nanofiller structure and viscoelastic behavior of the nanocomposites. The transient response under steady shear flow revealed that the stress overshoot of hybrid nanocomposites (two-fillers), PVDF/CNT/MnO2NWs, increased dramatically in comparison to binary nanocomposites (single-filler), PVDF/CNT and PVDF/MnO2NWs. This can be attributed to microstructural changes. Large amplitude oscillatory shear characterization was also performed to further investigate the effect of the secondary nanofiller on the nonlinear viscoelastic behavior of the samples. The nonlinear rheological observations were explained using quantitative nonlinear parameters [strain-stiffening ratio (S) and shear-thickening ratio (T)] and Lissajous-Bowditch plots. Results indicated that a more rigid nanofiller network was formed for the hybrid nanocomposites due to the better dispersion state of CNTs and this led to a more nonlinear viscoelastic behavior.
-
Ultrasensitive Detection of Proteins on Western Blots with Semiconducting Polymer Dots
Ye, Fangmao; Smith, Polina B.; Wu, Changfeng; Chiu, Daniel T.
2013-01-01
We demonstrate ultrasensitive fluorescence imaging of proteins on Western blots using a bright, compact, and orange-emitting semiconducting polymer dot (CN-PPV). We achieved a detection limit at the single-picogram level in dot blots; with conventional Western blotting, we detected 50 pg of transferrin and trypsin inhibitor after SDS-PAGE and transfer onto a PVDF membrane. Our method does not require any additional equipment or time compared to the conventional procedure with traditional fluo...
-
Fundamental characteristics study of anion-exchange PVDF-SiO(2) membranes.
Zuo, Xingtao; Shi, Wenxin; Yu, Shuili; He, Jiajie
2012-01-01
A new type of poly(vinylidene fluoride)(PVDF)-SiO(2) hybrid anion-exchange membrane was prepared by blending method. The anion-exchange groups were introduced by the reaction of epoxy groups with trimethylamine (TMA). Contact angle between water and the membrane surface was measured to characterize the hydrophilicity change of the membrane surface. The effects of nano-sized SiO(2) particles in the membrane-forming materials on the membrane mechanical properties and conductivity were also investigated. The experimental results indicated that PVDF-SiO(2) anion-exchange membranes exhibited better water content, ion-exchange capacity, conductivity and mechanic properties, and so may find potential applications in alkaline membrane fuel cells and water treatment processes.
-
Human exhaled air energy harvesting with specific reference to PVDF film
Directory of Open Access Journals (Sweden)
Manisha Rajesh Mhetre
2017-02-01
Full Text Available Spirometer is a medical equipment used to measure lung capacity of a human being. It leads to diagnosis of several diseases. The researchers worked on harvesting energy from human exhalation while carrying out measurements using spirometer. A prototype has been developed using piezoelectric material i.e. PVDF (polyvinylidene fluoride film as sensor. This paper presents the methodology and experimentation carried out for exhaled air energy harvesting using PVDF film. Experimental results obtained are encouraging. Measurements are also carried out on various subjects having different height, weight, age and gender. Data analysis shows variation in the energy harvested with different physical parameters and gender. Experimentation shows that voltage generated due to exhaled air is promising for harvesting.
-
Abolhasani, Mohammad Mahdi; Naebe, Minoo; Jalali-Arani, Azam; Guo, Qipeng
2014-01-01
In this paper, intercalation of nanoclay in the miscible polymer blend of poly(vinylidene fluoride) (PVDF) and acrylic rubber(ACM) was studied. X-ray diffraction was used to investigate the formation of nanoscale polymer blend/clay hybrid. Infrared spectroscopy and X-ray analysis revealed the coexistence of β and γ crystalline forms in PVDF/Clay nanocomposite while α crystalline form was found to be dominant in PVDF/ACM/Clay miscible hybrids. Flory-Huggins interaction parameter (B) was used to further explain the miscibility phenomenon observed. The B parameter was determined by combining the melting point depression and the binary interaction model. The estimated B values for the ternary PVDF/ACM/Clay and PVDF/ACM pairs were all negative, showing both proper intercalation of the polymer melt into the nanoclay galleries and the good miscibility of PVDF and ACM blend. The B value for the PVDF/ACM blend was almost the same as that measured for the PVDF/ACM/Clay hybrid, suggesting that PVDF chains in nanocomposite hybrids interact with ACM chains and that nanoclay in hybrid systems is wrapped by ACM molecules. PMID:24551141
-
Directory of Open Access Journals (Sweden)
Mohammad Mahdi Abolhasani
Full Text Available In this paper, intercalation of nanoclay in the miscible polymer blend of poly(vinylidene fluoride (PVDF and acrylic rubber(ACM was studied. X-ray diffraction was used to investigate the formation of nanoscale polymer blend/clay hybrid. Infrared spectroscopy and X-ray analysis revealed the coexistence of β and γ crystalline forms in PVDF/Clay nanocomposite while α crystalline form was found to be dominant in PVDF/ACM/Clay miscible hybrids. Flory-Huggins interaction parameter (B was used to further explain the miscibility phenomenon observed. The B parameter was determined by combining the melting point depression and the binary interaction model. The estimated B values for the ternary PVDF/ACM/Clay and PVDF/ACM pairs were all negative, showing both proper intercalation of the polymer melt into the nanoclay galleries and the good miscibility of PVDF and ACM blend. The B value for the PVDF/ACM blend was almost the same as that measured for the PVDF/ACM/Clay hybrid, suggesting that PVDF chains in nanocomposite hybrids interact with ACM chains and that nanoclay in hybrid systems is wrapped by ACM molecules.
-
Piezoelectric Polymer Ultrasound Transducers and Its Biomedical Applications
Energy Technology Data Exchange (ETDEWEB)
Ha, Kang Lyeol; Cao, Yanggang [Department of Physics, Pukyong National University, Busan (Korea, Republic of)
2012-10-15
PVDF(poly vinylidene fluoride) and P(VDF-TrFE)(poly vinylidene fluoride-tetrafluoroethylene) are the typical piezoelectric polymers with unique properties. Even they are inferior to conventional piezoelectric ceramics PZT in electromechanical conversion efficiency and interior loss, though they are superior in receiving sensitivity and frequency bandwidth. Their acoustic impedances are relatively close to water or biological tissue and it is easier to make thin film than other piezoelectric materials. Furthermore, the film is so flexible that it is easy to attach on a complex surface. Those properties are suitable for the ultrasound transducers which are useful for medical and biological application, so that various types of polymer transducers have been developed. In this paper, several important considerations for design and fabrication of piezoelectric polymer transducers were described and their effect on the transducer performance were demonstrated through the KLM model analysis. Then, it was briefly reviewed about the structures of the polymer transducers developed for obtaining images as well as the characteristics of the images in several important medical and biological application fields.
-
High Temperature Electro-Mechanical Devices For Nuclear Applications
International Nuclear Information System (INIS)
Robertson, D.
2010-01-01
Nuclear power plants require a number of electro-mechanical devices, for example, Control Rod Drive Mechanisms (CRDM's) to control the raising and lowering of control rods and Reactor Coolant Pumps (RCP's) to circulate the primary coolant. There are potential benefits in locating electro-mechanical components in areas of the plant with high ambient temperatures. One such benefit is the reduced need to make penetrations in pressure vessels leading to simplified plant design and improved inherent safety. The feature that limits the ambient temperature at which most electrical machines may operate is the material used for the electrical insulation of the machine windings. Conventional electrical machines generally use polymer-based insulation that limits the ambient temperature they can operate in to below 200 degrees Celsius. This means that when a conventional electrical machine is required to operate in a hot area it must be actively cooled necessitating additional systems. This paper presents data gathered during investigations undertaken by Rolls-Royce into the design of high temperature electrical machines. The research was undertaken at Rolls-Royce's University Technology Centre in Advanced Electrical Machines and Drives at Sheffield University. Rolls- Royce has also been investigating high temperature wire and encapsulants and latterly techniques to provide high temperature insulation to terminations. Rolls-Royce used the experience gained from these tests to produce a high temperature electrical linear actuator at sizes representative of those used in reactor systems. This machine was tested successfully at temperatures equivalent to those found inside the reactor vessel of a pressurised water reactor through a full series of operations that replicated in service duty. The paper will conclude by discussing the impact of the findings and potential electro-mechanical designs that may utilise such high temperature technologies. (authors)
-
International Nuclear Information System (INIS)
Yang Xuanxuan; Deng Bo; Yu Ming; Yu Yang; Zhang Bowu; Li Jingye
2011-01-01
Acryl amide (AAm) was grafted onto poly (vinylidene fluoride) (PVDF) powder by a γ-rays pre-irradiation induced graft polymerization technique. The DG values of the PVDF-g-PAM powder were determined by fluorine elemental analysis. Effects of grafting time on DG of PVDF-g-PAM powder at the same monomer concentration were studied. And modified powder was dissolved in NMP and added PVP as pre-forming agent. The microfiltration (MF) membranes were cast using a phase inversion method. The contact angle, degree of swelling, water flux and antifouling properties of those modified MF membranes were investigated. The results indicated that the hydrophilicity of modified MF membranes was improved obviously and the antifouling property of modified MF membranes (DG of 13%) was better than that of the pristine membrane. (authors)
-
International Nuclear Information System (INIS)
Renard, Ingrid; Li Hongmei; Marsan, Benoit
2003-01-01
Liquid electrolytes containing a cesium thiolate/disulfide redox couple, prepared from 5-mercapto-1-methyltetrazole cesium salt (CsT) and di-5-(1-methyltetrazole)disulfide (T 2 ) dissolved in several aprotic solvents and solvent mixtures, have been studied using various techniques. FTIR spectroscopy reveals that relatively strong interactions occur between the reduced species T - and DMSO or DMF while Cs + ions are very weakly coordinated to the S=O or C=O bond. It is shown that the electrolyte consisting of 1.55 mol kg -1 CsT in the solvent mixture DMSO/DMF (40/60%) exhibits the highest conductivity (1.1x10 -2 and 2.3x10 -2 S cm -1 at 23 and 80 deg. C, respectively), and that the presence of the oxidized species T 2 does not affect significantly its electrical properties up to a CsT:T 2 molar ratio of 5:1. Conductivity values as a function of salt concentration are discussed in terms of the effective number of charge carriers, taking into account the level of ionic association, and of the ionic mobility. Optically transparent gel electrolytes have been prepared by incorporation of the optimal liquid electrolyte into various amounts of poly(vinylidene fluoride) (PVDF). It is shown that ionic mobility is not much affected by the polymer concentration, suggesting that migration of ions occurs mainly through the solvent mixture surrounded by the PVDF matrix
-
Surface Modification of Electrospun PVDF/PAN Nanofibrous Layers by Low Vacuum Plasma Treatment
Directory of Open Access Journals (Sweden)
Fatma Yalcinkaya
2016-01-01
Full Text Available Nanofibres are very promising for water remediation due to their high porosity and small pore size. Mechanical properties of nanofibres restrict the application of pressure needed water treatments. Various PAN, PVDF, and PVDF/PAN nanofibre layers were produced, and mechanical properties were improved via a lamination process. Low vacuum plasma treatment was applied for the surface modification of nanofibres. Atmospheric air was used to improve hydrophilicity while sulphur hexafluoride gas was used to improve hydrophobicity of membranes. Hydrophilic membranes showed higher affinity to attach plasma particles compared to hydrophobic membranes.
-
Kim, Jungsoo; Kim, Yang Do; Nam, Dae Geun
2013-05-01
Graphene was coated on low carbon steel (SS400) by electro spray coating method to improve its properties of corrosion resistance and contact resistance. Exfoliated graphite was made of the graphite by chemical treatment (Chemically Converted Graphene, CCG). CCG is distributed using dispersing agent, and low carbon steel was coated with diffuse graphene solution by electro spray coating method. The structure of the CCG was analyzed using XRD and the coating layer of surface was analyzed using SEM. Analysis showed that multi-layered graphite structure was destroyed and it was transformed in to fine layers graphene structure. And the result of SEM analysis on the surface and the cross section, graphene layer was uniformly formed with 3-5 microm thickness on the surface of substrate. Corrosion resistance test was applied in the corrosive solution which is similar to the polymer electrolyte membrane fuel cell (PEMFC) stack inside. And interfacial contact resistance (ICR) test was measured to simulate the internal operating conditions of PEMFC stack. As a result of measuring corrosion resistance and contact resistance, it could be confirmed that low carbon steel coated with CCG was revealed to be more effective in terms of its applicability as PEMFC bipolar plate.
-
Carbon nano tubes embedded in polymer nano fibers
International Nuclear Information System (INIS)
Dror, Y.; Kedem, S.; Khalfin, R.L.; Paz, Y.; Cohenl, Y.; Salalha, Y.; Yarin, A.L.; Zussman, A.
2004-01-01
Full Text: The electro spinning process was used successfully to embed Multi-walled carbon nano tubes (MWCNTs) and single-walled carbon nano tubes (SWCNTs) in a matrix of poly(ethylene oxide) (PEO) forming composite nano fibers. Initial dispersion of SWCNTs in water was achieved by the use of an amphphilic alternating copolymer of styrene and sodium maleate. MWNT dispersion was achieved by ionic and nonionic surfactants. The distribution and conformation of the nano tubes in the nano fibers were studied by transmission electron microscopy (TEM). Oxygen plasma etching was used to expose the nano tubes within the nano fibers to facilitate direct observation. Nano tube alignment within the nano fibers was shown to depend strongly on the quality of the initial dispersions. Well-dispersed and separated nano tubes were embedded in a straight and aligned form while entangled non-separated nano tubes were incorporated as dense aggregates. X-ray diffraction demonstrated a high degree of orientation of the PEO crystals in the electro spun nano fibers with embedded SWCNTs, whereas incorporation of MVCNTs had a detrimental effect on the polymer orientation. Composite polymer nano fibers containing dispersed phases of nanometric TiO 2 particles and MWCNTs were also prepared electro spinning. In this case, the polymer matrix was poly(acrylonitrile) (PAN). The morphology and possible applications of these composite nano fibers will be discussed
-
Directory of Open Access Journals (Sweden)
Yuntao Xia
2017-04-01
Full Text Available A pyro-electro-chemical catalytic dye decomposition using lead-free BaTiO3 nanofibers was realized under room-temperature cold–hot cycle excitation (30–47 °C with a high Rhodamine B (RhB decomposition efficiency ~99%, which should be ascribed to the product of pyro-electric effect and electrochemical redox reaction. Furthermore, the existence of intermediate product of hydroxyl radical in pyro-electro-chemical catalytic process was also observed. There is no significant decrease in pyro-electro-chemical catalysis activity after being recycled five times. The pyro-electrically induced pyro-electro-chemical catalysis provides a high-efficient, reusable and environmentally friendly technology to remove organic pollutants from water.
-
Integration of active and passive polymer optics
DEFF Research Database (Denmark)
Christiansen, Mads Brøkner; Schøler, Mikkel; Kristensen, Anders
2007-01-01
We demonstrate a wafer scale fabrication process for integration of active and passive polymer optics: Polymer DFB lasers and waveguides. Polymer dye DFB lasers are fabricated by combined nanoimprint and photolithography (CNP). The CNP fabrication relies on an UV transparent stamp with nm sized...... wavelength from temperature and refractive index changes in the surroundings is investigated, pointing towards the use of the described fabrication method for on-chip polymer sensor systems....
-
Energy Technology Data Exchange (ETDEWEB)
Andrieu, X.; Boudin, F. [Alcatel Alsthom Recherche, 91 - Marcoussis (France)
1996-12-31
The lithium carbon batteries studied in this paper use plasticized polymer electrolytes made with passive polymer matrix swollen by a liquid electrolyte with a high ionic conductivity (> 10{sup -3} S/cm at 25 deg. C). The polymers used to prepare the gels are polyacrylonitrile (PAN) and vinylidene poly-fluoride (PVdF). The electrochemical and physical properties of these materials are analyzed according to their composition. The behaviour of solid electrolytes with different materials of lithium ion insertion (graphite and LiNiO{sub 2}) are studied and compared to liquid electrolytes. The parameters taken into account are the reversible and irreversible capacities, the cycling performance and the admissible current densities. Finally, complete lithium ion batteries with gelled electrolytes were manufactured and tested. (J.S.) 2 refs.
-
Energy Technology Data Exchange (ETDEWEB)
Andrieu, X; Boudin, F [Alcatel Alsthom Recherche, 91 - Marcoussis (France)
1997-12-31
The lithium carbon batteries studied in this paper use plasticized polymer electrolytes made with passive polymer matrix swollen by a liquid electrolyte with a high ionic conductivity (> 10{sup -3} S/cm at 25 deg. C). The polymers used to prepare the gels are polyacrylonitrile (PAN) and vinylidene poly-fluoride (PVdF). The electrochemical and physical properties of these materials are analyzed according to their composition. The behaviour of solid electrolytes with different materials of lithium ion insertion (graphite and LiNiO{sub 2}) are studied and compared to liquid electrolytes. The parameters taken into account are the reversible and irreversible capacities, the cycling performance and the admissible current densities. Finally, complete lithium ion batteries with gelled electrolytes were manufactured and tested. (J.S.) 2 refs.
-
Gadinski, Matthew R.
As the world begins to turn to alternative energy technologies and our electronic devices have become more both mobile and integral to everyday life, increasing interest has been focused on energy storage technologies. Capacitors are one of these energy storage technologies that utilize the polarization of an insulating material sandwiched by two electrodes as a means to store electric charge. Polymers are a preferred dielectric material for capacitors because of both their performance and practicality. However, polymer dielectrics are limited in energy density by low dielectric constant, and high loss at elevated temperature. This work aims to address these issues in order to enable polymer dielectrics for future applications and demands. As most polymer tend to have low dielectric constants (˜2-3), but impressive breakdown strengths, only a moderate improvement in dielectric constant has the potential to vastly improve the energy density of polymer capacitors. As such tremendous interest has been placed on poly(vinylidene fluoride) (PVDF) which has a dielectric of 10+ due to the highly polar C-F bonds of its backbone. To improve PVDF's performance defect monomers have been introduced to tailor the polymorphic crystalline phase to tune its properties. Additionally, this defect modification has implications for piezoelectric, electrocaloric, and thermoelectric applications of PVDF. In Chapter 2 a copolymer of VDF and bromotrifluoroethylene (BTFE) was produced. The effect of BTFE on the structure and dielectric properties of the resulting copolymer had not been previously evaluated, and its synthesis allowed for the comparison to previously reported VDF based copolymers including P(VDF-CTFE) and P(VDF-HFP). Through 19F NMR it was determined due to reactivity ratio differences of BTFE in comparison to previously explored copolymers, BTFE during synthesis is much more likely to link with itself. This results in long runs of BTFE-BTFE defects along with isolated
-
International Nuclear Information System (INIS)
Lu, Haibao; Leng, Jinsong; Du, Shanyi; Gou, Jihua
2011-01-01
This work studies the synergistic effect of carbon nanofiber (CNF) and sub-micro filamentary nickel nanostrand on the thermal and electrical properties, as well as the electro-active shape memory behavior, of a shape memory polymer (SMP) nanocomposite. The combination of electrical CNF and electromagnetic nickel nanostrand is used to render insulating thermo-responsive SMPs conductive. Subsequently, the shape memory behavior of the SMP can be activated by the electrical resistive heating. It is shown that sub-micro filamentary nickel-coated nanostrands significantly improved the electrical conductivity to facilitate the actuation of the SMP nanocomposite despite the low nanostrand volume content and low electrical voltage. Also the CNFs are blended with the SMP resin to facilitate the dispersion of nanostrands and improve the thermal conductivity to accelerate the electro- and thermo-active responses
-
Processing influence on the morphology of PVDF/PMMA blends examined by scanning electron microscopy
International Nuclear Information System (INIS)
Freire, Estevao; Forte, Maria M.C.; Monteiro, Elisabeth E.C.
2011-01-01
PVDF/PMMA blends were melt blended in proportions of 20, 40 e 60% PVDF by weight in two different mixers, a low shear and a high shear mixer. The compositions obtained were examined by scanning electron microscopy. The results were correlated with the two types of processing and showed that the type of mixer affects the morphology of the blend. The morphologies obtained corroborated the NMR analysis demonstrating the phase separation phenomena and the effect of the type of mixer used in this study. (author)
-
International Nuclear Information System (INIS)
Yang, Sang Yeol; Mahadeva, Suresha K; Kim, Jaehwan
2010-01-01
This paper reports a wirelessly driven electro-active paper actuator that consists of a dipole rectenna array, a power control circuit and two cellulose–polypyrrole–ionic liquid (CPIL) electro-active paper actuators. The CPIL nanocomposite actuator was fabricated by incorporating nanoscaled PPy onto cellulose by an in situ polymerization technique, which was followed by activation in a room temperature ionic liquid. The CPIL actuator shows its maximum bending displacement of 10 mm at an ambient humidity condition with 30 mW electrical power consumption. The CPIL actuator is very stable in its actuator performance. The dipole rectenna array receives microwaves and converts them to dc power so as to wirelessly supply power to the actuators. Three flexible dipole rectenna arrays are designed, manufactured and characterized. The rectenna array that has nine rectenna elements generates the maximum power of 75 mW. This power was used to successfully activate the two CPIL actuators and the control circuit. Detailed fabrication and characterization of the CPIL actuator and the dipole rectenna array as well as the control circuit are explained
-
Energy Technology Data Exchange (ETDEWEB)
Zhang, Xianhong; Zhao, Sidi; Wang, Fang [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Ma, Yuhong, E-mail: mayh@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Engineering Research Center of Syntheses and Applications of Waterborne Polymers, Beijing University of Chemical Technology, 100029 (China); Wang, Li; Chen, Dong; Zhao, Changwen [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Engineering Research Center of Syntheses and Applications of Waterborne Polymers, Beijing University of Chemical Technology, 100029 (China); Yang, Wantai, E-mail: yangwt@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Engineering Research Center of Syntheses and Applications of Waterborne Polymers, Beijing University of Chemical Technology, 100029 (China)
2017-05-01
Highlights: • Core-shell structured BT@PMMA and BT@PTFEMA nanoparticles were synthesized. • The dispersity of BT nanoparticles in PVDF matrix was improved significantly. • Dielectric properties both of BT@PMMA/PVDF and BT@PTFEMA/PVDF composites were improved. • The frequency dependence of dielectric constant attenuation of BT@PTFEMA/PVDF composites was smaller than that of BT@PMMA/PVDF composites. - Abstract: Polymer based dielectric composites were fabricated through incorporation of core-shell structured BaTiO{sub 3} (BT) nanoparticles into PVDF matrix by means of solution blending. Core-shell structured BT nanoparticles with different shell composition and shell thickness were prepared by grafting methacrylate monomer (MMA or TFEMA) onto the surface of BT nanoparticles via surface initiated atom transfer radical polymerization (SI-ATRP). The content of the grafted polymer and the micro-morphology of the core-shell structured BT nanoparticles were investigated by thermo gravimetric analyses (TGA) and transmission electron microscopy (TEM), respectively. The dielectric properties were measured by broadband dielectric spectroscopy. The results showed that high dielectric constant and low dielectric loss are successfully realized in the polymer based composites. Moreover, the type of the grafted polymer and its content had different effect on the dielectric constant. In detail, the attenuation of dielectric constant was 16.6% for BT@PMMA1/PVDF and 10.7% for BT@PMMA2/PVDF composite in the range of 10 Hz to 100 kHz, in which the grafted content of PMMA was 5.5% and 8.0%, respectively. However, the attenuation of dielectric constant was 5.5% for BT@PTFEMA1/PVDF and 4.0% for BT@PTFEMA2/PVDF composite, in which the grafted content of PTFEMA was 1.5% and 2.0%, respectively. These attractive features of BT@PTFEMA/PVDF composites suggested that dielectric ceramic fillers modified with fluorinated polymer can be used to prepare high performance composites, especially
-
International Nuclear Information System (INIS)
Zhang, Xianhong; Zhao, Sidi; Wang, Fang; Ma, Yuhong; Wang, Li; Chen, Dong; Zhao, Changwen; Yang, Wantai
2017-01-01
Highlights: • Core-shell structured BT@PMMA and BT@PTFEMA nanoparticles were synthesized. • The dispersity of BT nanoparticles in PVDF matrix was improved significantly. • Dielectric properties both of BT@PMMA/PVDF and BT@PTFEMA/PVDF composites were improved. • The frequency dependence of dielectric constant attenuation of BT@PTFEMA/PVDF composites was smaller than that of BT@PMMA/PVDF composites. - Abstract: Polymer based dielectric composites were fabricated through incorporation of core-shell structured BaTiO_3 (BT) nanoparticles into PVDF matrix by means of solution blending. Core-shell structured BT nanoparticles with different shell composition and shell thickness were prepared by grafting methacrylate monomer (MMA or TFEMA) onto the surface of BT nanoparticles via surface initiated atom transfer radical polymerization (SI-ATRP). The content of the grafted polymer and the micro-morphology of the core-shell structured BT nanoparticles were investigated by thermo gravimetric analyses (TGA) and transmission electron microscopy (TEM), respectively. The dielectric properties were measured by broadband dielectric spectroscopy. The results showed that high dielectric constant and low dielectric loss are successfully realized in the polymer based composites. Moreover, the type of the grafted polymer and its content had different effect on the dielectric constant. In detail, the attenuation of dielectric constant was 16.6% for BT@PMMA1/PVDF and 10.7% for BT@PMMA2/PVDF composite in the range of 10 Hz to 100 kHz, in which the grafted content of PMMA was 5.5% and 8.0%, respectively. However, the attenuation of dielectric constant was 5.5% for BT@PTFEMA1/PVDF and 4.0% for BT@PTFEMA2/PVDF composite, in which the grafted content of PTFEMA was 1.5% and 2.0%, respectively. These attractive features of BT@PTFEMA/PVDF composites suggested that dielectric ceramic fillers modified with fluorinated polymer can be used to prepare high performance composites, especially
-
Hema, M.; Tamilselvi, P.; Pandaram, P.
2017-07-01
Nanocomposite polymer electrolyte has been irradiated with 15 Gy Gamma rays. Exposure of gamma radiation caused scissoring and crosslinking of polymer chains thereby increasing amorphous phase of the polymer matrix because of which the ionic conductivity has been enhanced. Ionic conductivity of irradiated nanocomposite polymer electrolyte is enhanced to 9.4 × 10-4 Scm-1 at 303 K compared to un-irradiated system (σ ∼ 1.7 × 10-4 Scm-1). Temperature dependence of ionic conductivity of both un-irradiated and irradiated systems obeys VTF relation. Frequency and temperature dependence of dielectric and modulus of both systems have been analyzed. The ionic transference number of polymer electrolyte has been calculated by Wagner's polarization technique and it confirms that conducting species are predominantly due to ions in both systems.
-
A Four-Quadrant PVDF Transducer for Surface Acoustic Wave Detection
Directory of Open Access Journals (Sweden)
Zhi Chen
2012-08-01
Full Text Available In this paper, a polyvinylidene fluoride (PVDF piezoelectric transducer was developed to detect laser-induced surface acoustic waves in a SiO2-thin film–Si-substrate structure. In order to solve the problems related to, firstly, the position of the probe, and secondly, the fact that signals at different points cannot be detected simultaneously during the detection process, a four-quadrant surface acoustic wave PVDF transducer was designed and constructed for the purpose of detecting surface acoustic waves excited by a pulse laser line source. The experimental results of the four-quadrant piezoelectric detection in comparison with the commercial nanoindentation technology were consistent, the relative error is 0.56%, and the system eliminates the piezoelectric surface wave detection direction deviation errors, improves the accuracy of the testing system by 1.30%, achieving the acquisition at the same time at different testing positions of the sample.
-
Understanding the origins of metal-organic framework/polymer compatibility.
Semino, R; Moreton, J C; Ramsahye, N A; Cohen, S M; Maurin, G
2018-01-14
The microscopic interfacial structures for a series of metal-organic framework/polymer composites consisting of the Zr-based UiO-66 coupled with different polymers are systematically explored by applying a computational methodology that integrates density functional theory calculations and force field-based molecular dynamics simulations. These predictions are correlated with experimental findings to unravel the structure-compatibility relationship of the MOF/polymer pairs. The relative contributions of the intermolecular MOF/polymer interactions and the flexibility/rigidity of the polymer with respect to the microscopic structure of the interface are rationalized, and their impact on the compatibility of the two components in the resulting composite is discussed. The most compatible pairs among those investigated involve more flexible polymers, i.e. polyvinylidene fluoride (PVDF) and polyethylene glycol (PEG). These polymers exhibit an enhanced contact surface, due to a better adaptation of their configuration to the MOF surface. In these cases, the irregularities at the MOF surface are filled by the polymer, and even some penetration of the terminal groups of the polymer into the pores of the MOF can be observed. As a result, the affinity between the MOF and the polymer is very high; however, the pores of the MOF may be sterically blocked due to the strong MOF/polymer interactions, as evidenced by UiO-66/PEG composites. In contrast, composites involving polymers that exhibit higher rigidity, such as the polymer of intrinsic microporosity-1 (PIM-1) or polystyrene (PS), present interfacial microvoids that contribute to a decrease in the contact surface between the two components, thus reducing the MOF/polymer affinity.
-
Hu, Penghao; Jia, Zhuye; Shen, Zhonghui; Wang, Peng; Liu, Xiaoru
2018-05-01
To realize application in high-capacity capacitors and portable electric devices, large energy density is eagerly desired for polymer-based nanocomposite. The core-shell structured nanofillers with inorganic buffer layer are recently supposed to be promising in improving the dielectric property of polymer nanocomposite. In this work, core-shell structured TO@BT nanoparticles with crystalline TiO2 buffer layer coated on BaTiO3 nanoparticle were fabricated via solution method and heat treatment. The thickness of the TO buffer layer can be tailored by modulating the additive amount of the titanate coupling agent in preparation process, and the apparent dielectric properties of nanocomposite are much related to the thickness of the TO layer. The relatively thin TO layer prefer to generate high polarization to increase dielectric constant while the relatively thick TO layer would rather to homogenize field to maintain breakdown strength. Simulation of electric field distribution in the interfacial region reveals the improving effect of the TO buffer layer on the dielectric properties of nanocomposite which accords with the experimental results well. The optimized nanoparticle TO@BT-2 with a mean thickness of 3-5 nm buffer layer of TO is effective in increasing both the ε and Eb in the PVDF composite film. The maximal discharged energy density of 8.78 J/cm3 with high energy efficiency above 0.6 is obtained in TO@BT-2/PVDF nanocomposite with 2.5 vol% loading close to the breakdown strength of 380 kV/mm. The present study demonstrates the approach to optimize the structure of core-shell nanoparticles by modulating buffer layer and provides a new way to further enlarge energy density in polymer nanocomposite.
-
An, Alicia Kyoungjin; Guo, Jiaxin; Lee, Eui-Jong; Jeong, Sanghyun; Zhao, Yanhua; Wang, Zuankai; Leiknes, TorOve
2016-01-01
.4°) and roughness (Ra = 1,285mm). The zeta potential of E-PDMS membrane surface showed a higher negative value than that of a commercial PVDF (C-PVDF) membrane. These properties of E-PDMS membrane provided an antifouling in treating of differently-charged dyes
-
Ramlee, Azierah; Chiam, Chel-Ken; Sarbatly, Rosalam
2018-05-01
This work presents a study of destabilization of oil droplets in the produced water from alkaline-surfactant-polymer (ASP) flooding by using four types of laboratory-fabricated polyvinylidene fluoride (PVDF) membranes. The PVDF membranes were fabricated via immersion precipitation method with ethanol (0 - 30 %, v/v) as the coagulant. The membranes with the effective area of 17.35 cm2 were tested with synthesized ASP solution as the feed in cross-flow microfiltration process. The ASP feed solution initially contained the oil droplets with radius ranged from 40 to 100 nm and the mean radius was 61 nm. Results have shown that the concentration of the ethanol in the coagulation bath affects the formation of the membrane structure and the corresponding porosity, while no significance influence on the membrane thickness. Coalescence of the oil droplets was occurred when the ASP solution permeated through the asymmetric PVDF membranes. Through the coalescence process, the oil droplets were destabilized where the radius of the oil droplets in the permeates increased to 1.5-4 µm with the corresponding mean radius ranged from 2.4 to 2.7 µm.
-
Polymer-Ceramic Composite Materials for Pyroelectric Infrared Detectors: An Overview
Aggarwal, M. D; Currie, J. R.; Penn, B. G.; Batra, A. K.; Lal, R. B.
2007-01-01
Ferroelectrics:Polymer composites can be considered an established substitute for conventional electroceramics and ferroelectric polymers. The composites have a unique blend of polymeric properties such as mechanical flexibility, high strength, formability, and low cost, with the high electro-active properties of ceramic materials. They have attracted considerable interest because of their potential use in pyroelectric infrared detecting devices and piezoelectric transducers. These flexible sensors and transducers may eventually be useful for their health monitoring applications for NASA crew launch vehicles and crew exploration vehicles being developed. In the light of many technologically important applications in this field, it is worthwhile to present an overview of the pyroelectric infrared detector theory, models to predict dielectric behavior and pyroelectric coefficient, and the concept of connectivity and fabrication techniques of biphasic composites. An elaborate review of Pyroelectric-Polymer composite materials investigated to date for their potential use in pyroelectric infrared detectors is presented.
-
Alsaery, Salim A.
2017-05-01
With the increase of population every year, fresh water scarcity has rapidly increased and it is reaching a risky level, particularly in Africa and the Middle East. Desalination of seawater is an essential process for fresh water generation. One of the methods for desalination is membrane distillation (MD). MD process separates an aqueous liquid feed across a porous hydrophobic membrane to produce pure water via evaporation. Polyvinlidene fluoride (PVDF) membranes reinforced with a polyester fabric were fabricated as potential candidates for MD. Non-solvent induced phase separation coupled with steam treatment was used to prepare the PVDF membranes. A portion of the prepared membrane was coated with Teflon (AF2400) to increase its hydrophobicity. In the first study, the fabricated membranes were characterized using scanning electron microscopy and other techniques, and they were evaluated using direct contact MD (DCMD). The fabricated membranes showed a porous sponge-like structure with some macrovoids. The macrovoid formation and the spongy structure in the membrane cross-sections contributed significantly to a high permeate flux as they provide a large space for vapor water transport. The modified PVDF membranes with steaming and coating exhibited a permeate flux of around 40 L/h m2 (i.e. 27-30% increase to the control PVDF membrane) at temperatures of 60 °C (feed) and 20 °C (permeate). This increase in the permeate flux for the modified membranes was mainly attributed to its larger pore size on the bottom surface. In the second study, the control PVDF membrane was tested in two different module designs (i.e. semi-circular pipe and rectangular duct module designs). The semi-circular module design (turbulent regime) exhibited a higher permeate flux, 3-fold higher than that of the rectangular duct module design (laminar regime) at feed temperature of 60 °C. Furthermore, a heat energy balance was performed for each module design to determine the temperature
-
Characterization of modified PVDF membrane by gamma irradiation for non-potable water reuse.
Lim, Seung Joo; Kim, Tak-Hyun; Shin, In Hwan
2015-01-01
Poly(vinylidene fluorine) (PVDF) membranes were grafted by gamma-ray irradiation and were sulfonated by sodium sulfite to modify the surface of the membranes. The characteristics of the modified PVDF membranes were evaluated by the data of Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscope (FE-SEM), the contact angle of the membrane surface and the water permeability. From the results of FT-IR, XPS and FE-SEM, it was shown that the modified membranes were successfully grafted by gamma-ray irradiation and were sulfonated. The content of oxygen and sulfur increased with the monomer concentration, while the content of fluorine sharply decreased. The pore size of the modified membranes decreased after gamma-ray irradiation. The contact angle and the water permeability showed that the hydrophilicity of the modified membranes played a role in determining the membrane performance. The feasibility study of the modified PVDF membranes for using non-potable water reuse were carried out using a laboratory-scale microfiltration system. Grey wastewater was used as the influent in the filtration unit, and permeate quality satisfied non-potable water reuse guidelines in the Republic of Korea.
-
Kovacs, Gabor M.
2017-04-01
In the past decades the development of compliant dielectric materials, capable of storing high electric energy density, is the object of considerable research efforts for commercial applications. Compared to the widely used soft dielectrics as compliant insulators, only a small variety of commercially products based on dielectric polymer transducers are available on the market up to date. A whole bunch of research activities worldwide has created a lot of very useful knowledge; but many researchers have been faced to different obstacles to manufacture devices for demonstrations. However, building handy demonstrators is one of the most relevant action in order to attract the interest of decision makers of industrial companies. Moreover, low cost devices strictly require highly efficient production methods and facilities to become competitive on the market. This aspect contains the ultimate requirement especially for very high output rates and represents one of the major topic at most negotiations. All technological problems linked to this issue have been addressed only a little in the past R+D activities and are still widely not satisfactory solved. The present talk will provide an overview of the options for opening the door of industrial production of polymer transducers and the remaining obstacles to be solved for the next step. In particular, the most relevant actions to be taken for enabling high capacity production at very low cost will be discussed, which have an essential impact on the direction of future research activities.
-
Bioelectrochemical control of neural cell development on conducting polymers.
Collazos-Castro, Jorge E; Polo, José L; Hernández-Labrado, Gabriel R; Padial-Cañete, Vanesa; García-Rama, Concepción
2010-12-01
Electrically conducting polymers hold promise for developing advanced neuroprostheses, bionic systems and neural repair devices. Among them, poly(3, 4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) exhibits superior physicochemical properties but biocompatibility issues have limited its use. We describe combinations of electrochemical and molecule self-assembling methods to consistently control neural cell development on PEDOT:PSS while maintaining very low interfacial impedance. Electro-adsorbed polylysine enabled long-term neuronal survival and growth on the nanostructured polymer. Neurite extension was strongly inhibited by an additional layer of PSS or heparin, which in turn could be either removed electrically or further coated with spermine to activate cell growth. Binding basic fibroblast growth factor (bFGF) to the heparin layer inhibited neurons but promoted proliferation and migration of precursor cells. This methodology may orchestrate neural cell behavior on electroactive polymers, thus improving cell/electrode communication in prosthetic devices and providing a platform for tissue repair strategies. Copyright © 2010 Elsevier Ltd. All rights reserved.
-
International Nuclear Information System (INIS)
Liu, Z H; Pan, C T; Ou, Z Y; Lin, L W; Huang, J C
2014-01-01
One-dimensional piezoelectric nanomaterials have attracted great attention in recent years for their possible applications in mechanical energy scavenging devices. However, it is difficult to control the structural diameter, length, and density of these fibers fabricated by micro/nano-technologies. This work presents a hollow cylindrical near-field electrospinning (HCNFES) process to address production and performance issues encountered previously in either far-field electrospinning (FFES) or near-field electrospinning (NFES) processes. Oriented polyvinylidene fluoride (PVDF) fibers in the form of nonwoven fabric have been directly written on a glass tube for aligned piezoelectricity. Under a high in situ electrical poling field and strong mechanical stretching (the tangential speed on the glass tube collector is about 1989.3 mm s −1 ), the HCNFES process is able to uniformly deposit large arrays of PVDF fibers with good concentrations of piezoelectric β-phase. The nonwoven fiber fabric (NFF) is transferred onto a polyethylene terephthalate (PET) substrate and fixed at both ends using copper foil electrodes as a flexible textile-fiber-based PVDF energy harvester. Repeated stretching and releasing of PVDF NFF with a strain of 0.05% at 7 Hz produces a maximum peak voltage and current at 76 mV and 39 nA, respectively. (paper)
-
Umar, Yunusa
2014-01-01
A simple and effective hands-on classroom activity designed to illustrate basic polymer concepts is presented. In this activity, students build primary structures of homopolymers and different arrangements of monomers in copolymer using paper clips as monomers. The activity supports formation of a basic understanding of polymer structures,…
-
International Nuclear Information System (INIS)
Liu Qi; Zhu Zhiyong; Yang Xiaomin; Chen Xiliang; Song Yufeng
2007-01-01
N-isopropylacrylamide (NIPAAm) monomer was grafted on and in poly(vinylidene fluoride) (PVDF) micro-pore membrane by γ-irradiation. The influence of irradiation and reaction conditions on the grafting yield was investigated in detail. The chemical structure of NIPAAm-grafted PVDF (NIPAAm-g-PVDF) membrane was characterized by Fourier transform infrared spectra and X-ray photoelectron spectra measurements. The morphology of the sample surface as well as the cross-section before and after grafting was characterized by scanning electron microscope. The temperature sensitive properties of the membrane were monitored by measuring the conductance as well as the water flux through the sample thickness. The results show that the membrane exhibits clearly temperature-sensitive permeability to water as expected, i.e. the permeability of water changes dramatically as the temperature goes over the lower critical solution temperature of NIPAAm
-
Li, Deke; Gou, Xuelian; Wu, Daheng; Guo, Zhiguang
2018-04-05
The wide application of superhydrophobic membranes has been limited due to their complicated preparation technology and weak durability. Inspired by the mechanical flexibility of nanofibrous biomaterials, nanofibrils have been successfully generated from Kevlar, which is one of the strongest synthetic fibers, by appropriate hydrothermal treatment. In this study, a robust superhydrophobic PDMS/PVDF@KNFs membrane is prepared via a simple one-step process and subsequent curing without combination with inorganic fillers. The as-prepared PDMS/PVDF@KNFs membrane not only shows efficient oil/water separation ability and oil absorption capacity but also has excellent superhydrophobicity stability after deformation. The resultant membrane shows stretchability, flexibility and flame retardance because of the reinforcing effect and the excellent flame retardancy of Kevlar. We believe that this simple fabrication of PDMS/PVDF@KNFs has promising applications in filtering membranes and wearable devices.
-
Medically relevant ElectroNeedle technology development.
Energy Technology Data Exchange (ETDEWEB)
Schmidt, Carrie Frances; Thomas, Michael Loren; McClain, Jaime L.; Harper, Jason C.; Achyuthan, Komandoor E.; Ten Eyck, Gregory A.
2008-11-01
ElectroNeedles technology was developed as part of an earlier Grand Challenge effort on Bio-Micro Fuel Cell project. During this earlier work, the fabrication of the ElectroNeedles was accomplished along with proof-of-concept work on several electrochemically active analytes such as glucose, quinone and ferricyanide. Additionally, earlier work demonstrated technology potential in the field of immunosensors by specifically detecting Troponin, a cardiac biomarker. The current work focused upon fabrication process reproducibility of the ElectroNeedles and then using the devices to sensitively detect p-cresol, a biomarker for kidney failure or nephrotoxicity. Valuable lessons were learned regarding fabrication assurance and quality. The detection of p-cresol was accomplished by electrochemistry as well as using fluorescence to benchmark ElectroNeedles performance. Results from these studies will serve as a guide for the future fabrication processes involving ElectroNeedles as well as provide the groundwork necessary to expand technology applications. One paper has been accepted for publication acknowledging LDRD funding (K. E. Achyuthan et al, Comb. Chem. & HTS, 2008). We are exploring the scope for a second paper describing the applications potential of this technology.
-
Energy Technology Data Exchange (ETDEWEB)
Bessbousse, H [Laboratoire des Solides Irradies, CEA-CNRS-Ecole Polytechnique, 91128 Palaiseau (France); Nadhakumar, I [School of Chemistry, University of Southampton, University Road, Southampton S017 1BJ (United Kingdom); Decker, M; Clochard, M -C; Wade, T L [Laboratoire des Solides Irradies, CEA-CNRS-Ecole Polytechnique, 91128 Palaiseau (France); Barsbay, M [Hacettepe University, Department of Chemistry, Polymer Chemistry Division, 06800 Beytepe Ankara (Turkey)
2012-09-15
Track etched functionalized nanoporous {beta}-PVDF membrane electrodes, or functionalized membrane electrodes (FME), are thin-layer cells made from poly(acrylic acid) (PAA) functionalized nanoporous {beta}-poly(vinylidene fluoride) ({beta}-PVDF) membranes with thin Au films sputtered on each side as electrodes. The Au film is thin enough that the pores of the membranes are not completely covered. The PAA functionalization is specifically localised in the walls of the nanoporous {beta}-PVDF membrane by grafting. The PAA is a cation exchange polymer that adsorbs metal ions, such as Pb{sup 2+}, from aqueous solutions concentrating the ions into the membrane. After a time the FME is transferred to an electrochemical cell for analysis. A negative potential is applied to the Au film of the FME for a set time to reduce the adsorbed ions onto the Au film working electrode. The other metalized side of the FME functions as a counter electrode. Finally, square-wave anodic stripping voltammetry (SW-ASV) is performed on the FME to determine the metal ion concentrations in the original solution. The calibration curve of charge versus log concentration has a Temkin isotherm form. The FME membranes are 9 {mu}m thick and have 40 nm diameter pores with a density of 10{sup 10} pores/cm{sup 2}. This high pore density provides a large capacity for ion adsorption. Au ingress in the pores during sputtering forms a random array of nanoelectrodes. Like surface modified electrodes for adsorptive stripping voltammetry, the pre-concentration step for the FME is performed at open circuit. The zero current intercept of the calibration for Pb{sup 2+} is 0.13 ppb ({mu}g/L) and a detection limit of 0.050 ppb based on 3S/N from blank measurements. Voltammetry (CV) and chronoapmerometry (CA) were used to characterize the system. The apparent diffusion coefficient (D) for Pb{sup 2+} in the PAA functionalized pores was determined to be 2.44 x 10{sup -7} cm{sup 2}/s and the partition coefficient (p
-
International Nuclear Information System (INIS)
Gimenes, T.C.; Pereira, E.A.; Montanhera, M.A.; Paula, F.R. de; Spada, E.R.
2016-01-01
In this study we obtained nanofibers titanium dioxide (TiO2) incorporated into the poly (vinylidene fluoride) - PVDF in different concentrations, using a new technique denominated Solution Blow Spinning. This technique has the merits of simplicity, low cost and high efficiency in the production of nanofibers, compared with the technique of Electrospinning, using pressurized gas instead of high voltage, is not limited to the dielectric constant of the material and provides a processing period of at least 100 times faster. The obtained nanofibers exhibit little account and a very smooth morphology, with diameters ranging from 400 to 700 nm and with presence of crystalline anatase phase. The tests showed photocatalytic degradation of Rhodamine B dye, being more degradation shown by the PVDF nanofibers containing 0,7 g of TiO 2 , approximately 75 % of degraded dye. However nanofibers obtained the PVDF/TiO2 applications of this material are numerous, as filters, conductive nanofibers, photocatalysis and sensors. (author)
-
Energy harvesting efficiency of piezoelectric polymer film with graphene and metal electrodes.
Park, Sanghoon; Kim, Yura; Jung, Hyosub; Park, Jun-Young; Lee, Naesung; Seo, Yongho
2017-12-11
In this study, we investigated an energy harvesting effect of tensile stress using piezoelectric polymers and flexible electrodes. A chemical-vapor-deposition grown graphene film was transferred onto both sides of the PVDF and P(VDF-TrFE) films simultaneously by means of a conventional wet chemical method. Output voltage induced by sound waves was measured and analyzed when a mechanical tension was applied to the device. Another energy harvester was made with a metallic electrode, where Al and Ag were deposited by using an electron-beam evaporator. When acoustic vibrations (105 dB) were applied to the graphene/PVDF/graphene device, an induced voltage of 7.6 V pp was measured with a tensile stress of 1.75 MPa, and this was increased up to 9.1 V pp with a stress of 2.18 MPa for the metal/P(VDF-TrFE)/metal device. The 9 metal/PVDF/metal layers were stacked as an energy harvester, and tension was applied by using springs. Also, we fabricated a full-wave rectifying circuit to store the electrical energy in a 100 μF capacitor, and external vibration generated the electrical charges. As a result, the stored voltage at the capacitor, obtained from the harvester via a bridge diode rectifier, was saturated to ~7.04 V after 180 s charging time.
-
International Nuclear Information System (INIS)
Rouabah, Hamza A; Morgan, Hywel; Green, Nicolas G; Park, Benjamin Y; Zaouk, Rabih B; Madou, Marc J
2011-01-01
Lab-on-a-chip devices require integrated pumping and fluid control in microchannels. A recently developed mechanism that can produce fluid flow is an integrated ac-electro-osmosis micropump. However, like most electrokinetic pumps, ac-electro-osmotic pumps are incapable of handling backpressure as the pumping force mechanism acts on the surface of the fluid rather than the bulk. This paper presents a novel 3D electrode structure designed to overcome this limitation. The electrodes are fabricated using carbon-MEMS technology based on the pyrolysis of the photo-patternable polymer SU-8. The novel ac-electro-osmosis micropump shows an increase in the flow velocity compared to planar electrodes.
-
Electro photographic materials
International Nuclear Information System (INIS)
Buzdugan, A.; Andries, A.; Iovu, M.
2000-01-01
The invention relates to the creation of electro photographic materials . The invention allows to extend the material photosensitivity into the infrared range of the spectrum. An electro photographic materials contains an electro conducting base, including a dielectric base 1, for example glass, an electro conducting layer 2, for example of Al, Ni, Cr, an injecting layer 3, consisting of amorphous indium phosphide, a vitreous layer 4 of the arsenic sulphide - antimony sulphide system and a transporting layer 5 of the arsenic sulphide or arsenic selenide
-
Structural control of side-chain chromophores to achieve highly efficient electro-optic activity.
Yang, Yuhui; Chen, Zhuo; Liu, Jialei; Xiao, Hongyan; Zhen, Zhen; Liu, Xinhou; Jiang, Guohua
2017-05-10
A series of chromophores J1-J4 have been synthesized based on julolidine donors modified with different rigid steric hindrance groups. Compared with the chromophore (J1) without the isolation group, chromophores J2, J3 and J4 show better stability. Structural analysis and photophysical property measurements were carried out to compare the molecular mobility and steric hindrance effect of the different donor-modified chromophores. All of these chromophores with isolation groups showed superb thermal stabilities with high thermal decomposition temperatures above 250 °C. Furthermore, with rigid steric hindrance, chromophores J3 and J4 showed more enhanced thermal stabilities with thermal decomposition temperatures of 269 °C and 275 °C, respectively. Density functional theory was used to calculate the hyperpolarizability (β), and the high molecular hyperpolarizability of these chromophores can be effectively translated into large electro-optic coefficients. The electro-optic coefficients of poled films containing 20 wt% of these new chromophores doped in amorphous polycarbonate were 127, 266 and 209 pm V -1 at 1310 nm for chromophores J1-J3, respectively, while the film containing chromophore J4 showed the largest r 33 value of only 97 pm V -1 at 25 wt%. These results indicated that the introduced isolation group can reduce intermolecular electrostatic interactions, thus enhancing the macroscopic electro-optic activity, while the size of the isolation group should be suitable.
-
Theory-inspired development of organic electro-optic materials
Energy Technology Data Exchange (ETDEWEB)
Dalton, Larry R., E-mail: dalton@chem.washington.ed [Department of Chemistry, Bagley Hall 202D, Box 351700, University of Washington, Seattle, Washington 98195-1700 (United States); Department of Electrical Engineering, Bagley Hall 202D, Box 351700, University of Washington, Seattle, Washington 98195-1700 (United States)
2009-11-30
Real-time, time-dependent density functional theory (RTTDDFT) and pseudo-atomistic Monte Carlo-molecular dynamics (PAMCMD) calculations have been used in a correlated manner to achieve quantitative definition of structure/function relationships necessary for the optimization of electro-optic activity in organic materials. Utilizing theoretical guidance, electro-optic coefficients (at telecommunication wavelengths) have been increased to 500 pm/V while keeping optical loss to less than 2 dB/cm. RTTDDFT affords the advantage of permitting explicit treatment of time-dependent electric fields, both applied fields and internal fields. This modification has permitted the quantitative simulation of the variation of linear and nonlinear optical properties of chromophores and the electro-optic activity of materials with optical frequency and dielectric permittivity. PAMCMD statistical mechanical calculations have proven an effective means of treating the full range of spatially-anisotropic intermolecular electrostatic interactions that play critical roles in defining the degree of noncentrosymmetric order that is achieved by electric field poling of organic electro-optic materials near their glass transition temperatures. New techniques have been developed for the experimental characterization of poling-induced acentric order including a modification of variable angle polarization absorption spectroscopy (VAPAS) permitting a meaningful correlation of theoretical and experimental data related to poling-induced order for a variety of complex organic electro-optic materials.
-
Theory-inspired development of organic electro-optic materials
International Nuclear Information System (INIS)
Dalton, Larry R.
2009-01-01
Real-time, time-dependent density functional theory (RTTDDFT) and pseudo-atomistic Monte Carlo-molecular dynamics (PAMCMD) calculations have been used in a correlated manner to achieve quantitative definition of structure/function relationships necessary for the optimization of electro-optic activity in organic materials. Utilizing theoretical guidance, electro-optic coefficients (at telecommunication wavelengths) have been increased to 500 pm/V while keeping optical loss to less than 2 dB/cm. RTTDDFT affords the advantage of permitting explicit treatment of time-dependent electric fields, both applied fields and internal fields. This modification has permitted the quantitative simulation of the variation of linear and nonlinear optical properties of chromophores and the electro-optic activity of materials with optical frequency and dielectric permittivity. PAMCMD statistical mechanical calculations have proven an effective means of treating the full range of spatially-anisotropic intermolecular electrostatic interactions that play critical roles in defining the degree of noncentrosymmetric order that is achieved by electric field poling of organic electro-optic materials near their glass transition temperatures. New techniques have been developed for the experimental characterization of poling-induced acentric order including a modification of variable angle polarization absorption spectroscopy (VAPAS) permitting a meaningful correlation of theoretical and experimental data related to poling-induced order for a variety of complex organic electro-optic materials.
-
Song, Shixin; Xia, Shan; Jiang, Shangkun; Lv, Xue; Sun, Shulin; Li, Quanming
2018-01-01
A facile strategy is adopted to prepare carboxylic functionalized multiwalled carbon nanotube (c-MWCNT) modified high dielectric constant (high-k) poly(vinylidene fluoride) (PVDF) composites with the aid of methyl methacrylate-co-glycidyl methacrylate copolymer (MG). The MG is miscible with PVDF and the epoxy groups of the copolymer can react with the carboxylic groups of c-MWCNT, which induce the uniform dispersion of c-MWCNT and a form insulator layer on the surface of c-MWCNT. The c-MWCNTs/MG/PVDF composites with 8 vol % c-MWCNT present excellent dielectric properties with high dielectric constant (~448) and low dielectric loss (~2.36) at the frequency of 1 KHz, the dielectric loss is much lower than the c-MWCNT/PVDF composites without MG. The obvious improvement in dielectric properties ascribes to the existence of MG, which impede the direct contact of c-MWCNTs and PVDF and avoid the formation of conductive network. Therefore, we propose a practical and simple strategy for preparing composites with excellent dielectric properties, which are promising for applications in electronics devices. PMID:29495491
-
Ionic Liquids in Electro-active Devices (ILED)
2013-12-12
near a charged wall can be modeled by Poisson- Nernst -Planck (PNP) equations , Poisson-Boltzmann (PB) equations , and Gouy-Chapman-Stern (GCS) model...actuators can be calculated from the bending curvature к and the Young’s moduli of the ionic polymer layer Yi and the Au layer Ym by the equation below...Arrhenius equation exp a E p p RT (1) wherein p and aE are the conducting ion concentration as T and the activation energy for conducting
-
Electro-optical rendezvous and docking sensors
Tubbs, David J.; Kesler, Lynn O.; Sirko, Robert J.
1991-01-01
Electro-optical sensors provide unique and critical functionality for space missions requiring rendezvous, docking, and berthing. McDonnell Douglas is developing a complete rendezvous and docking system for both manned and unmanned missions. This paper examines our sensor development and the systems and missions which benefit from rendezvous and docking sensors. Simulation results quantifying system performance improvements in key areas are given, with associated sensor performance requirements. A brief review of NASA-funded development activities and the current performance of electro-optical sensors for space applications is given. We will also describe current activities at McDonnell Douglas for a fully functional demonstration to address specific NASA mission needs.
-
International Nuclear Information System (INIS)
Im, Jong Su; Sohn, Joon Yong; Shin, Jun Hwa; Nho, Young Chang; Kim, Jeong Soo
2009-01-01
Several PVDF-HFP/silylated γ-AI 2 O 3 -coated PE (polyethylene) separators with various solidities (various compositions of PVDF-HFP/silylated γ-AI 2 O 3 ) were prepared by a dip-coating of PE separators in PVDF-HFP/silylated γ-AI 2 O 3 /acetone mixtures. FT-IR spectroscopy was used to confirm the chemical reactions between silane coupling agent and γ-AI 2 O 3 . The SEM images of the coated separators showed that various morphologies could be produced by changing the composition of total contents of binder and solid contents. The effects of composition in inorganic material (silane coupling agent-treated γ-AI 2 O 3 ) and binder (PVDF-HFP) on the physio-chemical properties of the prepared separators such as liquid electrolyte uptake, and ion conductivity were investigated and reported in this paper
-
Gamma irradiation effects on poly(vinylidene fluoride) films
International Nuclear Information System (INIS)
Ribeiro, Geise; Zen, Heloisa A.; Geraldes, Adriana N.; Souza, Camila P.; Parra, Duclerc F.; Lima, Luis Filipe C.P.; Lugao, Ademar B.
2009-01-01
In this work, the properties of Poly(vinylidene fluoride) PVDF films after exposing to gamma radiation at different doses (5, 10 and 15 kGy) were investigated. PVDF is a semicrystalline polymer that shows good properties in terms of chemical, thermal and electrical stabilities. The gamma radiation is a convenient and effective way of modification perfluorinated and partially fluorinated polymers such as PVDF. The properties of the pristine and irradiated PVDF films were studied by infrared spectroscopy, thermal analysis (TGA and DSC) and mechanical measurements at room temperature and at melting temperature of the PVDF. The infrared spectra of the irradiated PVDF samples do not present significant alterations in the absorption bands at all irradiated doses. The results obtained by thermal analysis indicate that the radiation does not alter significantly the decomposition temperature of the pristine PVDF film. Tensile strength measurements at room temperature before and after exposition to gamma radiation showed decrease of elongation at rupture in relation of pristine PVDF, suggesting that the radiation caused the crosslinking or chain scission of the PVDF film. (author)
-
International Nuclear Information System (INIS)
Karimi, G.; Li, X.
2005-01-01
Polymer electrolyte membrane (PEM) fuel cells are highly efficient and environmentally clean, and hence one of the most promising power sources for both stationary and mobile applications. The operations of PEM fuel cells are complicated by the electroosmotic flow of water from anode to cathode through the polymer electrolyte membrane leading to the membrane dehydration and fuel cell performance degradations. In this study, electro osmotic flow in polymer electrolyte membranes is modeled by incorporating the electro kinetic effects in the presence of euphoric acid. The governing Poisson-Boatman and the Nervier-Stokes equations were solved numerically for a single membrane pore to determine the electro osmotic flow distributions through the membrane over a wide range of acid concentrations. The presence of euphoric acid modifies the protons distribution in the membrane and hence alters the driving force for electroosmotic drag. Numerical results indicate that the electro osmotic flow increases steadily with acid concentration. The water transport due to electro osmosis is almost doubled at 2 M acid concentration compared with that of non-doped membrane. The value of electroosmotic drag coefficient however falls steadily with acid concentration due to the presence of a larger number of protons in the electrolyte. (author)
-
Directory of Open Access Journals (Sweden)
Feifel Sven C
2011-12-01
Full Text Available Abstract Background For bioanalytical systems sensitivity and biomolecule activity are critical issues. The immobilization of proteins into multilayer systems by the layer-by-layer deposition has become one of the favorite methods with this respect. Moreover, the combination of nanoparticles with biomolecules on electrodes is a matter of particular interest since several examples with high activities and direct electron transfer have been found. Our study describes the investigation on silica nanoparticles and the redox protein cytochrome c for the construction of electro-active multilayer architectures, and the electron transfer within such systems. The novelty of this work is the construction of such artificial architectures with a non-conducting building block. Furthermore a detailed study of the size influence of silica nanoparticles is performed with regard to formation and electrochemical behavior of these systems. Results We report on interprotein electron transfer (IET reaction cascades of cytochrome c (cyt c immobilized by the use of modified silica nanoparticles (SiNPs to act as an artificial matrix. The layer-by-layer deposition technique has been used for the formation of silica particles/cytochrome c multilayer assemblies on electrodes. The silica particles are characterized by dynamic light scattering (DLS, Fourier transformed infrared spectroscopy (FT-IR, Zeta-potential and transmission electron microscopy (TEM. The modified particles have been studied with respect to act as an artificial network for cytochrome c and to allow efficient interprotein electron transfer reactions. We demonstrate that it is possible to form electro-active assemblies with these non-conducting particles. The electrochemical response is increasing linearly with the number of layers deposited, reaching a cyt c surface concentration of about 80 pmol/cm2 with a 5 layer architecture. The interprotein electron transfer through the layer system and the
-
Energy Technology Data Exchange (ETDEWEB)
Muthuraaman, B. [Department of Energy, University of Madras, Guindy campus, Chennai 600025 (India); Maruthamuthu, P., E-mail: pmaruthu@yahoo.com [Department of Energy, University of Madras, Guindy campus, Chennai 600025 (India)
2011-09-01
Highlights: > Incorporation of a {pi}-electron donor compound as dopant in poly(vinylidene fluoride) along with redox couple (I{sup -}/I{sub 3}{sup -}) which forms brush like nanotubes. > Investigations about the use of conducting carbon coated FTO as a durable counter electrode and its effects in DSC. > High charge separation and the channelized flow of electrons in the nanotubes in electrolyte favors stable performance. - Abstract: In the present work, we report the incorporation of 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) in poly(vinylidene fluoride) (PVDF) along with the redox couple (I{sup -}/I{sub 3}{sup -}). When ABTS, a {pi}-electron donor, is used to dope PVDF, the polymer composite forms brush-like nanotubes and has been successfully used as a solid polymer electrolyte in dye-sensitized solar cells. Under the given conditions, the electrolyte composition forms nanotubes while it is doped with ABTS, a {pi}-electron donor. With this new electrolyte, a dye-sensitized solar cell was fabricated using N3 dye adsorbed over TiO{sub 2} nanoparticles as the photoanode and conducting carbon cement coated FTO as counter electrode.
-
Directory of Open Access Journals (Sweden)
Gemima Lara Hernandez
2013-01-01
Full Text Available Among the photothermal methods, the photopyroelectric (PPE technique is a suitable method to determine thermal properties of different kinds of samples ranging from solids to liquids and gases. Polyvinylidene difluoride (PVDF is one of the most frequently used pyroelectric sensors in PPE technique but has the disadvantage that it can be easily deformed by the sample weight. This deformation could add a piezoelectric effect to the thermal parameters assessment; also PVDF has a narrow temperature operation range when compared with ceramic pyroelectric sensors. In order to minimize possible piezoelectric effects due to sensor deformation, a ceramic of lanthanum modified lead zirconate (PLZT was used as pyroelectric sensor in the PPE technique. Then, thermal diffusivity of some liquid samples was measured, by using the PPE configuration that denominated the thermal wave resonator cavity (TWRC, with a PLZT ceramic as pyroelectric detector. The performance obtained with the proposed ceramic in the TWRC configuration was compared with that obtained with PVDF by using the same configuration.
-
Electro-optic polymeric reflection modulator based on plasmonic metamaterial
Abbas, A.; Swillam, M.
2018-02-01
A novel low power design for polymeric Electro-Optic reflection modulator is proposed based on the Extraordinary Reflection of light from multilayer structure consisting of a plasmonic metasurface with a periodic structure of sub wavelength circular apertures in a gold film above a thin layer of EO polymer and above another thin gold layer. The interference of the different reflected beams from different layer construct the modulated beam, The applied input driving voltage change the polymer refractive index which in turn determine whether the interference is constructive or destructive, so both phase and intensity modulation could be achieved. The resonant wavelength is tuned to the standard telecommunication wavelength 1.55μm, at this wavelength the reflection is minimum, while the absorption is maximum due to plasmonic resonance (PR) and the coupling between the incident light and the plasmonic metasurface.
-
International Nuclear Information System (INIS)
Wulkersdorfer, B.; Kao, K.K.; Agopian, V.G.; Ahn, A.; Dunn, J.C.; Wu, B.M.; Stelzner, M.; Kao, K.K.; Agopian, K.J.; Dunn, J.C.; Wu, B.M.; Stelzner, M.; Dunn, J.C.; Wu, B.M.
2009-01-01
Electro spinning is a method to produce fine, bio polymer mesh with a three-dimensional architecture that mimics native extra-cellular matrix. Due to the small fiber diameter created in this process, conventional electro spun scaffolds have pore sizes smaller than the diameter of most cells. These scaffolds have limited application in tissue engineering due to poor cell penetration. We developed a hybrid electro spinning/particulate leaching technique to create scaffolds with increased porosity and improved cellular ingrowth. Poly(glycolic acid) (PGA) and a sucrose-ethanol suspension were electro spun in equal, alternating sequences at intervals of one, two, and ten minutes each. The scaffolds revealed fiber mesh with micropores of 10 μm and uniformly distributed sucrose particles. Particulate leaching of sucrose from the one- or two-minute scaffolds revealed honeycomb structures with interconnected macro pores between 50 and 250 μm. Sucrose leaching from the ten-minute scaffolds resulted in laminated structures with isolated macro pores between 200 and 350 μm. Macro pore size was directly proportional to the duration of the sucrose spinning interval. After 24 hours of cell culture, conventionally spun scaffolds demonstrated no cellular penetration. Conversely, the PGA/sucrose scaffolds demonstrated deep cellular penetration. This hybrid technique represents a novel method of generating electro spun scaffolds with interconnected pores suitable for cellular ingrowth.
-
Liang, Shuai
2013-07-24
Polyvinylidene fluoride (PVDF) has drawn much attention as a predominant ultrafiltration (UF) membrane material due to its outstanding mechanical and physicochemical properties. However, current applications suffer from the low fouling resistance of the PVDF membrane due to the intrinsic hydrophobic property of the membrane. The present study demonstrates a novel approach for the fabrication of a highly hydrophilic PVDF UF membrane via postfabrication tethering of superhydrophilic silica nanoparticles (NPs) to the membrane surface. The pristine PVDF membrane was grafted with poly(methacrylic acid) (PMAA) by plasma induced graft copolymerization, providing sufficient carboxyl groups as anchor sites for the binding of silica NPs, which were surface-tailored with amine-terminated cationic ligands. The NP binding was achieved through a remarkably simple and effective dip-coating technique in the presence or absence of the N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) cross-linking process. The properties of the membrane prepared from the modification without EDC/NHS cross-linking were comparable to those for the membrane prepared with the EDC/NHS cross-linking. Both modifications almost doubled the surface energy of the functionalized membranes, which significantly improved the wettability of the membrane and converted the membrane surface from hydrophobic to highly hydrophilic. The irreversibly bound layer of superhydrophilic silica NPs endowed the membranes with strong antifouling performance as demonstrated by three sequential fouling filtration runs using bovine serum albumin (BSA) as a model organic foulant. The results suggest promising applications of the postfabrication surface modification technique in various membrane separation areas. © 2013 American Chemical Society.
-
Study of PVDF/Graphene oxide nanocomposites by UV-Vis analysis
International Nuclear Information System (INIS)
Pereira, Juliana V.
2013-01-01
In this work we have prepared nanocomposites made by mixing Poly (vinylidene fluoride) [PVDF] and grapheme oxide nanosheets (GO) aiming to find dosimetric properties for applications in high dose dosimetry. Graphene Oxides (GO) nanosheets were synthesized by the Hummers method, using graphite supplied by Aldrich as the starting material. Nanocomposites were produced by mixing solved PDVF in DMAc with GO dispersed in an aqueous solution by sonication. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h), with doses ranging from 50 to 1,000 kGy. The UV-Vis and spectrophotometry have been used to monitor the appearing of C=C conjugated bonds and radio-oxidation of carbon (C=O). The PVDF/OG nanocomposites prepared with 1.88 at.% of OG presented the best dosimetric properties. In this material, UVVis spectrometry has revealed that the absorbance intensities at 250 nm can be used for high dosimetry purposes for gamma doses ranging from 100 to 750 kGy. In this range, it is possible to observe a linear relationship between Abs and Dose. (author)
-
International Nuclear Information System (INIS)
Jiang Yuanyuan; Lu Yizhong; Han Dongxue; Zhang Qixian; Niu Li
2012-01-01
Ag nanowires are prepared as templates by a polyol reduction process. Then Ag nanotubes coated with a thin layer of Pd are synthesized through sequential reduction accompanied with the galvanic displacement reaction. The products show a hollow core–shell nanotubular structure, as demonstrated by detailed characterizations. The Ag-Pd can significantly improve the electrocatalytic activity towards the electro-oxidation of formic acid and enhance the stability of the Pd component. It is proposed that the enhanced electrochemically active surface area and modulated electron structure of Pd by Ag are responsible for the improvement of electrocatalytic activity and durability. The results obtained in this work are different from those previous reports, in which alloy walls with hollow interiors are usually formed. This work provides a new and simple method for synthesizing novel bimetallic core–shell structure with a hollow interior, which can be applied as high-performance catalysts for the electro-oxidation of formic acid. (paper)
-
Development of zwitterionic chromophores for electro-optic applications
Xiong, Ying
In order to unlock the full potential of the zwitterionic NLO chromophores for electro-optic (EO) applications, a new series of PeQDM chromophores with large first hyperpolarizabilities (beta0 ˜ 600 x 10-30 esu) have been designed and synthesized. A large EO coefficient (r33) of 110 pm/V at 1550 nm has been realized with a 5 wt% (corresponding to 3.8 wt% core content) chromophore doped polymer. The EO study of guest-host polymers reveals that dipolar dye aggregation in a less polar medium is responsible for a low chromophore loading and low EO activity. Modification of NLO chromophore by attaching large dendrons can effectively increase the chromophore loading in a host and improve the poling efficiency. Crosslinkable NLO polymers have also been prepared to improve the temporal stability of the poled noncentrosymmetric order. The following are some important highlights from this thesis work. (1) A series of thermally stable zwitterionic chromophores (PeQDM) with large first hyperpolarizabilities (beta up to -1797 x 10-30 esu) are synthesized in good yields (˜ 50%). The charge-separated ground state is evident by a negative solvatochromism. X-ray crystallographic data further confirms the zwitterionic nature and demonstrates a face-to-face anti-parallel H-aggregation of two monomers due to strong electrostatic interactions between the dipoles. (2) PeQDM chromophores are also NIR fluorescent (lambdaPL ˜ 840-870 nm in solution) and labile to acid, making them potential candidates for NIR pH sensor applications. (3) The hydroxyl-containing PeQDM chromophores are modified with ES-dendron, which exhibit good solubility in solvents and polymers. Self-forming films can be prepared by direct casting or spin-coating of two dendrons modified chromophores (ES-PeQDM-2 and ES-PeQDM-3), in which the chromophore core contents reach 14.9 and 16.9 wt%, respectively. Compared to ES-PeQDM-2 with two dendrons only at the donor part (r33 = 0 pm/V), ES-PeQDM-3 with the bulky ES
-
Ultra-Sensitive Strain Sensor Based on Flexible Poly(vinylidene fluoride) Piezoelectric Film
Lu, Kai; Huang, Wen; Guo, Junxiong; Gong, Tianxun; Wei, Xiongbang; Lu, Bing-Wei; Liu, Si-Yi; Yu, Bin
2018-03-01
A flexible 4 × 4 sensor array with 16 micro-scale capacitive units has been demonstrated based on flexible piezoelectric poly(vinylidene fluoride) (PVDF) film. The piezoelectricity and surface morphology of the PVDF were examined by optical imaging and piezoresponse force microscopy (PFM). The PFM shows phase contrast, indicating clear interface between the PVDF and electrode. The electro-mechanical properties show that the sensor exhibits excellent output response and an ultra-high signal-to-noise ratio. The output voltage and the applied pressure possess linear relationship with a slope of 12 mV/kPa. The hold-and-release output characteristics recover in less than 2.5 μs, demonstrating outstanding electro-mechanical response. Additionally, signal interference between the adjacent arrays has been investigated via theoretical simulation. The results show the interference reduces with decreasing pressure at a rate of 0.028 mV/kPa, highly scalable with electrode size and becoming insignificant for pressure level under 178 kPa.
-
Federal Laboratory Consortium — The electro-deposition laboratory can electro-deposit various coatings onto small test samples and bench level prototypes. This facility provides the foundation for...
-
International Nuclear Information System (INIS)
Peng, Xinglan; Zhao, Yanchun; Chen, Duhong; Fan, Yanfang; Wang, Xiao; Wang, Weili; Tian, Jianniao
2014-01-01
The outstanding performance PtCu y (y = 1,2,3) alloy nanoparticles supported on reduced graphene oxide (rGO) have been synthesized by a facile, efficient, one-pot hydrothermal synthesis approach. The as-prepared PtCu y /rGO catalysts are comprehensively characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy. Cyclic voltammetry, CO-stripping voltammetry and chronoamperometry results reveal that the PtCu y /rGO catalysts have higher electro-catalytic activity, more negative onset oxidative potential, more excellent tolerance ability for CO poisoning and enhanced stability for the electro-oxidation of methanol compared to pure Pt/rGO. As far as the as-made PtCu y /rGO catalysts are concerned, the PtCu 2 /rGO exhibits the highest electro-catalytic activity. The mechanism of the promoting effect of Cu on Pt is explained based on the electronic modification effect. The nature of interfacial interactions between the Pt-Cu active metal phase and the rGO supporting materials is crucial to achieving high performance
-
Polymerization speed and diffractive experiments in polymer network LC test cells
Braun, Larissa; Gong, Zhen; Habibpourmoghadam, Atefeh; Schafforz, Samuel L.; Wolfram, Lukas; Lorenz, Alexander
2018-02-01
Polymer-network liquid crystals (LCs), where the response properties of a LC can be enhanced by the presence of a porous polymer network, are investigated. In the reported experiments, liquid crystals were doped with a small amount (situ generated polymer network, the electro-optic response properties of photo cured samples were enhanced. For example, their continuous phase modulation properties led to more localized responses in samples with interdigitated electrodes, which caused suppression of selected diffraction orders in the diffraction patterns recorded in polymer network LC samples. Moreover, capacitance changes were investigated during photopolymerization of a blue phase LC.
-
Effects of electric discharges on polymers
International Nuclear Information System (INIS)
Bagirov, M.A.
2002-01-01
Full text: One of the reasons for the worsening of electrical properties of polymeric isolation in use in the effect of the electric discharges which developing in the gas inclusions and in the interlayer inside the isolation itself. The electrical discharges in the gas gap lead to the electrical growing old and the worsening of its electro physical qualities. We have learned the changes of electrical properties (dielectrical permeability and dielectrical loss, and electrical conductivity, electrical strength) of polymer films under the influence of electrical discharges. This paper shows the ways of increase of stability of polymers to the electrical discharges
-
Energy Technology Data Exchange (ETDEWEB)
Reiner, A.
2007-07-01
This illustrated, comprehensive dissertation by Dr. Andreas Reiner presents an in-depth analysis of polymer electrolyte fuel cells (PEFC) and in particular, their platinum catalyst layer. First of all, the thermodynamics and kinetics involved are reviewed, along with components, their efficiencies and the catalyst layer. The methods used, including scanning electron microscope, x-ray and Rutherford spectroscopy are discussed. The structure and composition of co-sputtered catalyst layers and their production are described. Electro-chemical activation and the electro-chemical properties of the layers are discussed. The second part of the dissertation deals with the principle of hydrogen under-potential deposition. This method provides information about the electrochemically active platinum surface fraction. The results of investigations made are presented and discussed.
-
Frictional behaviour of polymer films under mechanical and electrostatic loads
International Nuclear Information System (INIS)
Ginés, R; Christen, R; Motavalli, M; Bergamini, A; Ermanni, P
2013-01-01
Different polymer foils, namely polyimide, FEP, PFA and PVDF were tested on a setup designed to measure the static coefficient of friction between them. The setup was designed according to the requirements of a damping device based on electrostatically tunable friction. The foils were tested under different mechanically applied forces and showed reproducible results for the static coefficient of friction. With the same setup the measurements were performed under an electric field as the source of the normal force. Up to a certain electric field the values were in good agreement. Beyond this field discrepancies were found. (paper)
-
Performance of injection-limited polymer light-emitting diodes
Blom, P.W.M.; Woudenberg, T.V.; Huiberts, H.; Jabbour, GE; Carter, SA; Kido, J; Lee, ST; Sariciftci, NS
2002-01-01
The electro-optical characteristics of a polymer light emitting diode (PLED) with a strongly reduced hole injection have been investigated. The device consists of a poly-p-phenylene vinylene semiconductor with a Ag hole injecting contact, which has an injection barrier of about 1 eV. It is observed
-
Electro-catalytic degradation of sulfisoxazole by using graphene anode.
Wang, Yanyan; Liu, Shuan; Li, Ruiping; Huang, Yingping; Chen, Chuncheng
2016-05-01
Graphite and graphene electrodes were prepared by using pure graphite as precursor. The electrode materials were characterized by a scanning electron microscope (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV) measurements. The electro-catalytic activity for degradation of sulfisoxazole (SIZ) was investigated by using prepared graphene or graphite anode. The results showed that the degradation of SIZ was much more rapid on the graphene than that on the graphite electrode. Moreover, the graphene electrode exhibited good stability and recyclability. The analysis on the intermediate products and the measurement of active species during the SIZ degradation demonstrated that indirect oxidation is the dominant mechanism, involving the electro-catalytic generation of OH and O2(-) as the main active oxygen species. This study implies that graphene is a promising potential electrode material for long-term application to electro-catalytic degradation of organic pollutants. Copyright © 2015. Published by Elsevier B.V.
-
Electro-active polymers containing pendent 2,7-diarylfluorene fragments as materials for OLEDs
Krucaite, G.; Tavgeniene, D.; Peciulyte, L.; Buika, G.; Liu, L.; Zhang, B.; Xie, Z.; Grigalevicius, S.
2016-05-01
Poly[2-phenyl-7-(4-vinylphenyl)-9,9-diethylfluorene)], poly[2-(1-naphtyl)-7-(4-vinylphenyl)-9,9-diethylfluorene)] and poly[2-(4-biphenyl)-7-(4-vinylphenyl)-9,9-diethylfluorene)] were synthesized and characterized by NMR spectroscopy, elemental analysis and gel permeation chromatography. The derivatives represent materials of high thermal stability with initial thermal destruction temperatures from 390°C to 400 °C. The glass transition temperatures of the amorphous materials were 182 °C, 151 °C and 159 °C respectively. Hole-transporting properties of the polymeric materials were tested in the structures of organic light emitting diodes with Alq3 as the green emitter and electron transporting material. The device containing hole-transporting layers of polymer with 2-(4-biphenyl)-7-(4-vinylphenyl)-9,9-diethylfluorene moieties exhibited the best overall performance with turn on voltage of 3.6 V, a maximum photometric efficiency of 3.1 cd/A and maximum brightness of about 5300 cd/m2.
-
Du, Guofeng; Li, Zhao; Song, Gangbing
2018-05-23
Impact loads can have major adverse effects on the safety of civil engineering structures, such as concrete-filled steel tubular (CFST) columns. The study of mechanical behavior and stress analysis of CFST columns under impact loads is very important to ensure their safety against such loads. At present, the internal stress monitoring of the concrete cores CFST columns under impact loads is still a very challenging subject. In this paper, a PVDF (Polyvinylidene Fluoride) piezoelectric smart sensor was developed and successfully applied to the monitoring of the internal stress of the concrete core of a CFST column under impact loads. The smart sensor consists of a PVDF piezoelectric film sandwiched between two thin steel plates through epoxy. The protection not only prevents the PVDF film from impact damages but also ensures insulation and waterproofing. The smart sensors were embedded into the circular concrete-filled steel tube specimen during concrete pouring. The specimen was tested against impact loads, and testing data were collected. The time history of the stress obtained from the PVDF smart sensor revealed the evolution of core concrete internal stress under impact loads when compared with the impact force⁻time curve of the hammer. Nonlinear finite element simulations of the impact process were also carried out. The results of FEM simulations had good agreement with the test results. The results showed that the proposed PVDF piezoelectric smart sensors can effectively monitor the internal stress of concrete-filled steel tubular columns under impact loads.
-
Yang, Wulin
2014-12-01
A low cost poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) phase inversion coating was developed as a cathode diffusion layer to enhance the performance of microbial fuel cells (MFCs). A maximum power density of 1430 ± 90 mW m-2 was achieved at a PVDF-HFP loading of 4.4 mg cm-2 (4:1 polymer:carbon black), with activated carbon as the oxygen reduction cathode catalyst. This power density was 31% higher than that obtained with a more conventional platinum (Pt) catalyst on carbon cloth (Pt/C) cathode with a poly(tetrafluoroethylene) (PTFE) diffusion layer (1090 ± 30 mW m-2). The improved performance was due in part to a larger oxygen mass transfer coefficient of 3 × 10-3 cm s-1 for the PVDF-HFP coated cathode, compared to 1.7 × 10-3 cm s -1 for the carbon cloth/PTFE-based cathode. The diffusion layer was resistant to electrolyte leakage up to water column heights of 41 ± 0.5 cm (4.4 mg cm-2 loading of 4:1 polymer:carbon black) to 70 ± 5 cm (8.8 mg cm-2 loading of 4:1 polymer:carbon black). This new type of PVDF-HFP/carbon black diffusion layer could reduce the cost of manufacturing cathodes for MFCs. © 2014 Elsevier B.V. All rights reserved.
-
International Nuclear Information System (INIS)
Santos, Elizabeth; Schmickler, Wolfgang
2008-01-01
A unified model for electrochemical electron transfer reactions which explicitly accounts for the electronic structure of the electrode recently proposed by us is applied to the hydrogen oxidation reaction at different metal electrocatalysts. We focus on the changes produced in the transition state (saddle point) as a consequence of the interactions with d-bands. We discuss different empirical correlations between properties of the metal and catalytic activity proposed in the past. We show which role is played by the band structure of the different metals and its interaction with the molecule for decreasing the activation barrier. Finally, we demonstrate why some metals are better electrocatalysts for the hydrogen electro-oxidation reaction than others
-
Sayyed, M. I.; AlZaatreh, M. Y.; Matori, K. A.; Sidek, H. A. A.; Zaid, M. H. M.
2018-06-01
In the present study, the exposure buildup factors (EBF) have been investigated using geometric progression (G-P) fitting method for different types of smart polymers (DMSO, PDMS, PES, PMA, PVDC, and PVDF) in the energy range of 0.015-15 MeV. From the calculations, the values of the EBF were depended on the incident photon energy, penetration depth as well as chemical composition of the polymers. In the intermediate energy region, the EBF values were reached at maximum point while in low and high energy regions, the EBF values were decreased at minimum point. The obtained results of the selected polymers have been compared in terms of EBF with Al2O3 and other common polymers such as PAN, Teflon and SR. The shielding effectiveness of the selected polymers is found to be comparable to the common polymers. The results of this work should be useful in radiation shielding applications such as in industry, medical and nuclear engineering.
-
Lee, Kyung Min; Tondiglia, Vincent P.; Bunning, Timothy J.; White, Timothy J.
2017-02-01
Recently, we reported direct current (DC) field controllable electro-optic (EO) responses of negative dielectric anisotropy polymer stabilized cholesteric liquid crystals (PSCLCs). A potential mechanism is: Ions in the liquid crystal mixtures are trapped in/on the polymer network during the fast photopolymerization process, and the movement of ions by the application of the DC field distorts polymer network toward the negative electrode, inducing pitch variation through the cell thickness, i.e., pitch compression on the negative electrode side and pitch expansion on positive electrode side. As the DC voltage is directly applied to a target voltage, charged polymer network is deformed and the reflection band is tuned. Interestingly, the polymer network deforms further (red shift of reflection band) with time when constantly applied DC voltage, illustrating DC field induced time dependent deformation of polymer network (creep-like behavior). This time dependent reflection band changes in PSCLCs are investigated by varying the several factors, such as type and concentration of photoinitiators, liquid crystal monomer content, and curing condition (UV intensity and curing time). In addition, simple linear viscoelastic spring-dashpot models, such as 2-parameter Kelvin and 3-parameter linear models, are used to investigate the time-dependent viscoelastic behaviors of polymer networks in PSCLC.
-
Stimuli-Responsive Polymer-Clay Nanocomposites under Electric Fields
Piao, Shang Hao; Kwon, Seung Hyuk; Choi, Hyoung Jin
2016-01-01
This short Feature Article reviews electric stimuli-responsive polymer/clay nanocomposites with respect to their fabrication, physical characteristics and electrorheological (ER) behaviors under applied electric fields when dispersed in oil. Their structural characteristics, morphological features and thermal degradation behavior were examined by X-ray diffraction pattern, scanning electron microscopy and transmission electron microscopy, and thermogravimetric analysis, respectively. Particular focus is given to the electro-responsive ER characteristics of the polymer/clay nanocomposites in terms of the yield stress and viscoelastic properties along with their applications. PMID:28787852
-
El Gibari , Mohammed
2009-01-01
The electro-optical polymers are expected to allow realizing eventually cheaper modulators with better performances than those based on inorganic crystals such as LiNbO3 and semiconductors such as GaAs. This PhD thesis concerns the study and the design of the microwave and optical structure of a Mach-Zehnder modulator based on polymer, in order to demonstrate the feasibility of its realization based on the electro-optical polymer PIII (PGMA/DR1). The study of the optical structure using the s...
-
Investigations on PVdF- HFP - PEMA polymer blend electrolytes doped with different lithium salts
Manojkumar Ubarhande, Radha; Bhattacharya, Shreya; Usha Rani, M.; Shanker Babu, Ravi; Krishnaveni, S.
2017-11-01
Plasticized polymer blend electrolytes were prepared by incorporating poly (vinylidenefluoride-co-hexafluoropropylene)(PVdF-HFP) and poly(ethylmethacrylate) (PEMA) complexed with plasticizer (PC) and different lithium salts such as LiClO4, LiBF4, LiCF3SO3 and LiN (CF3SO2)2) using solution-casting technique. X-ray diffraction and Fourier transform infra-red techniques confirms the structural characters and complex formation of the polymer electrolytes respectively. AC impedance analysis was carried out for all the samples in the range303-373K. The results suggest that among the various lithium salts, LiN (CF3SO2)2) based electrolytes exhibited the highest ionic conductivity (3.17 × 10-3 Scm-1).
-
Pulsed-diode-pumped, all-solid-state, electro-optically controlled picosecond Nd:YAG lasers
International Nuclear Information System (INIS)
Gorbunkov, Mikhail V; Shabalin, Yu V; Konyashkin, A V; Kostryukov, P V; Olenin, A N; Tunkin, V G; Morozov, V B; Rusov, V A; Telegin, L S; Yakovlev, D V
2005-01-01
The results of the development of repetitively pulsed, diode-pumped, electro-optically controlled picosecond Nd:YAG lasers of two designs are presented. The first design uses the active-passive mode locking with electro-optical lasing control and semiconductor saturable absorber mirrors (SESAM). This design allows the generation of 15-50-ps pulses with an energy up to 0.5 mJ and a maximum pulse repetition rate of 100 Hz. The laser of the second design generates 30-ps pulses due to combination of positive and negative electro-optical feedback and the control of the electro-optical modulator by the photocurrent of high-speed semiconductor structures. (active media. lasers)
-
Design principles and realization of electro-optical circuit boards
Betschon, Felix; Lamprecht, Tobias; Halter, Markus; Beyer, Stefan; Peterson, Harry
2013-02-01
The manufacturing of electro-optical circuit boards (EOCB) is based to a large extent on established technologies. First products with embedded polymer waveguides are currently produced in series. The range of applications within the sensor and data communication markets is growing with the increasing maturity level. EOCBs require design flows, processes and techniques similar to existing printed circuit board (PCB) manufacturing and appropriate for optical signal transmission. A key aspect is the precise and automated assembly of active and passive optical components to the optical waveguides which has to be supported by the technology. The design flow is described after a short introduction into the build-up of EOCBs and the motivation for the usage of this technology within the different application fields. Basis for the design of EOCBs are the required optical signal transmission properties. Thereafter, the devices for the electro-optical conversion are chosen and the optical coupling approach is defined. Then, the planar optical elements (waveguides, splitters, couplers) are designed and simulated. This phase already requires co-design of the optical and electrical domain using novel design flows. The actual integration of an optical system into a PCB is shown in the last part. The optical layer is thereby laminated to the purely electrical PCB using a conventional PCB-lamination process to form the EOCB. The precise alignment of the various electrical and optical layers is thereby essential. Electrical vias are then generated, penetrating also the optical layer, to connect the individual electrical layers. Finally, the board has to be tested electrically and optically.
-
Duan, C.; Gao, K.; Colberts, F. J. M.; Liu, F.; Meskers, S. C. J.; Wienk, M. M.; Janssen, R. A. J.
2017-01-01
Developing novel materials that tolerate thickness variations of the active layer is critical to further enhance the efficiency of polymer solar cells and enable large-scale manufacturing. Presently, only a few polymers afford high efficiencies at active layer thickness exceeding 200 nm and
-
Proposal for electro-optic multiplier based on dual transverse electro-optic Kerr effect.
Li, Changsheng
2008-10-20
A novel electro-optic multiplier is proposed, which can perform voltage multiplication operation by use of the Kerr medium exhibiting dual transverse electro-optic Kerr effect. In this kind of Kerr medium, electro-optic phase retardation is proportional to the square of its applied electric field, and orientations of the field-induced birefringent axes are only related to the direction of the field. Based on this effect, we can design an electro-optic multiplier by selecting the crystals of 6/mmm, 432, and m3m classes and isotropic Kerr media such as glass. Simple calculation demonstrates that a kind of glass-ceramic material with a large Kerr constant can be used for the design of the proposed electro-optic multiplier.
-
Jia, Nan; Xing, Qian; Liu, Xu; Sun, Jing; Xia, Guangmei; Huang, Wei; Song, Rui
2015-09-01
Poly(vinylidene fluoride) (PVDF) is a semi-crystalline polymer and the polar β-phase of PVDF shows superb electroactive properties. In order to enhance the β-phase of PVDF, extreme low content of BaTiO3 nanoparticles (BT-NPs) coated with polydopamine (Pdop) were incorporated into PVDF matrix by solution casting. The β-phase of the resulting PVDF nanocomposites film was dramatically increased and the d33 value reached 34.3±0.4 pCN(-1). It is found that the Pdop layer could improve the dispersibility and stability of the BT NPs in solution and endow the BT NPs good dispersity in the PVDF matrix. Moreover, the interfacial interaction between PVDF chains and the surface of BT-Pdop nanoparticles (BT-Pdop NPs) were revealed, in which the CF2 groups on PVDF could interact with the electron-rich plane of aromatic ring of Pdop moiety. This interaction, led to the increase of the crystallization activation energy as derived from the DSC nonisothermal crystallization measurement. The α-β crystal transformation, organization of interfacial interactions as well as the prevention of agglomeration of BT-NPs confer the improvement of mechanical and thermal properties of PVDF, such as toughness, tensile strength, elongation at break, and thermal conductivity. Copyright © 2015 Elsevier Inc. All rights reserved.
-
Scalable electro-photonic integration concept based on polymer waveguides
Bosman, E.; Steenberge, G. van; Boersma, A.; Wiegersma, S.; Harmsma, P.J.; Karppinen, M.; Korhonen, T.; Offrein, B.J.; Dangel, R.; Daly, A.; Ortsiefer, M.; Justice, J.; Corbett, B.; Dorrestein, S.; Duis, J.
2016-01-01
A novel method for fabricating a single mode optical interconnection platform is presented. The method comprises the miniaturized assembly of optoelectronic single dies, the scalable fabrication of polymer single mode waveguides and the coupling to glass fiber arrays providing the I/O's. The low
-
Composite polymer electrolyte based on PEO/Pvdf-HFP with MWCNT for lithium battery applications
Energy Technology Data Exchange (ETDEWEB)
Pradeepa, P.; Edwinraj, S.; Sowmya, G.; Kalaiselvimary, J.; Selvakumar, K.; Prabhu, M. Ramesh, E-mail: email-mkram83@gmail.com [Department of Physics, Alagappa University, Karaikudi – 630 004 (India)
2016-05-06
In the present study PEO and PVdF-HFP blend based composite polymer electrolytes (CPEs) has been prepared by using Multi Walled Carbon Nanotube (MWCNT), in order to examine the filler addition effect on the electrochemical properties. The complexed nanocomposite polymer electrolytes were obtained in the form of dimensionally stable and free standing films by using solution casting technique. The electrochemical properties of CPEs were measured by the AC impedance method. From the ionic conductivity results, the CPE containing MWCNT 2wt% showed the highest ionic conductivity with an excellent thermal stability at room temperature. The dielectric loss curve s for the sample 6.25wt% PEO: 18.75 wt% PVdF-HFP: 2wt% MWCNT reveal the low frequency β relaxation peak pronounced at high temperature, and it may caused by side group dipoles.
-
Possibility of cellulose-based electro-active paper energy scavenging transducer.
Abas, Zafar; Kim, Heung Soo; Zhai, Lindong; Kim, Jaehwan; Kim, Joo Hyung
2014-10-01
In this paper, a cellulose-based Electro-Active Paper (EAPap) energy scavenging transducer is presented. Cellulose is proven as a smart material, and exhibits piezoelectric effect. Specimens were prepared by coating gold electrodes on both sides of cellulose film. The fabricated specimens were tested by a base excited aluminum cantilever beam at resonant frequency. Different tests were performed with single and multiple parallel connected electrodes coated on the cellulose film. A maximum of 131 mV output voltage was measured, when three electrodes were connected in parallel. It was observed that voltage output increases significantly with the area of electrodes. From these results, it can be concluded that the piezoelectricity of cellulose-based EAPap can be used in energy transduction application.
-
Kareb, Ourdia; Champagne, Claude P; Aïder, Mohammed
2016-04-01
Cheese-whey, a major co-product of the dairy industry, has recently been the subject of many technological applications. We studied the bioconversion of whey into valuable bio-products such as a potential lactulose prebiotic and compounds with antioxidant properties. This paper examines efficiency, safety, and economics of electro-activation as an eco-friendly technology for a maximum valorization of whey. Thus, a bottom-up approach was therefore addressed. The effect of 4 experimental parameters--low working temperatures (0, 10, and 25 °C), current intensities (400, 600, and 800 mA), volume conditions (100, 200, and 300 mL), and feed concentrations [7, 14, and 28% (wt/vol)]--on lactose-whey isomerization to lactulose under electro-activation process were studied. Structural characteristics of whey proteins and antioxidant functionality were also investigated. The results showed a compromise to be reached between both parameters. Therefore, the maximum yield of 35% of lactulose was achieved after 40 min of reaction at the working temperature of 10 °C under 400 mA electric current field and 100-mL volume conditions with using feed solution at 7% (wt/vol). The isomerization of lactose to lactulose is accomplished by subsequent degradation to galactose, but only at a very small amount. Additionally, whey electro-activation showed significantly elevated antioxidant capacity compared with the untreated samples. The enhancement of antioxidant functionality of whey electro-activation resulted from the synergistic effect of its partial hydrolysis and the formation of antioxidant components that were able to scavenge free radicals. In conclusion, the findings of this study reveal that the whey treated by the safety electro-activation technology has both lactulose-prebiotic and antioxidant properties and could have a substantial application in the manufacture of pharmaceutical and functional foods. Copyright © 2016 American Dairy Science Association. Published by Elsevier
-
International Nuclear Information System (INIS)
Yaldagard, Maryam; Jahanshahi, Mohsen; Seghatoleslami, Naser
2014-01-01
Highlights: • In this work nanosized WC/C were successfully coated by PANI. • Pt particles (10.56 nm) were uniformly dispersed on the surface of PANI/WC/C support. • The Pt/PANI/WC/C exhibited higher MOR activity and CO tolerance than Pt/C. • The Pt/PANI/WC/C exhibited higher activity for ORR than Pt/C in RDE experiments. • Pt/PANI/WC/C showed good stability than that of Pt/C in the presence of methanol. - Abstract: In the present study a Pt/PANI/WC/C electrocatalyst was developed to increase the methanol electro-oxidation and oxygen electro-reduction activity and stability of commercial Pt/C electrocatalyst. WC/C was coated with protonated polyaniline (PANI) in situ during the polymerization of aniline. Fourier transform infrared (FTIR) results illustrate the presence of PANI in the composite. The conductivity of PANI coated – WC/C has been compared with the conductivity of the corresponding mixtures of WC/C and Vulcan XC-72. X-ray diffraction results showed that Pt particles were dispersed on the support with mean particle size of about 10.56 nm. Transition electron microscopy images showed that the nanosized WC/C were successfully coated by PANI. Based on the electrochemical properties characterized by cyclic voltammetry, CO stripping and rotating disk electrode measurements it was found that the as prepared Pt/PANI/WC/C electrocatalyst exhibited a comparable activity for methanol oxidation reaction and oxygen reduction reaction with respect to the commercial one. A significant reduction in the potential of CO electro-oxidation peak from 0.75 V for Pt/C to 0.52 V for Pt/PANI/WC/C electrocatalyst indicates that an increase in the activity for CO electro-oxidation is achieved by replacing the carbon support by PANI coated WC/C. Chronoamerometry results also showed, in the presence of methanol the Pt/PANI/WC/C electrocatalyst still maintains a higher current density than Pt/WC/C and Pt/C
-
Energy Technology Data Exchange (ETDEWEB)
Yaldagard, Maryam, E-mail: m_yaldagard@yahoo.com [Department of Chemical Engineering, Ferdowsi University of Mashhad, P.O. Box 91775-1111 (Iran, Islamic Republic of); Nanotechnology Research Institute, School of Chemical Engineering, Babol University of Technology (Iran, Islamic Republic of); Jahanshahi, Mohsen, E-mail: mjahan@nit.um.ac.ir [Nanotechnology Research Institute, School of Chemical Engineering, Babol University of Technology (Iran, Islamic Republic of); Seghatoleslami, Naser, E-mail: Slami@um.ac.ir [Department of Chemical Engineering, Ferdowsi University of Mashhad, P.O. Box 91775-1111 (Iran, Islamic Republic of)
2014-10-30
Highlights: • In this work nanosized WC/C were successfully coated by PANI. • Pt particles (10.56 nm) were uniformly dispersed on the surface of PANI/WC/C support. • The Pt/PANI/WC/C exhibited higher MOR activity and CO tolerance than Pt/C. • The Pt/PANI/WC/C exhibited higher activity for ORR than Pt/C in RDE experiments. • Pt/PANI/WC/C showed good stability than that of Pt/C in the presence of methanol. - Abstract: In the present study a Pt/PANI/WC/C electrocatalyst was developed to increase the methanol electro-oxidation and oxygen electro-reduction activity and stability of commercial Pt/C electrocatalyst. WC/C was coated with protonated polyaniline (PANI) in situ during the polymerization of aniline. Fourier transform infrared (FTIR) results illustrate the presence of PANI in the composite. The conductivity of PANI coated – WC/C has been compared with the conductivity of the corresponding mixtures of WC/C and Vulcan XC-72. X-ray diffraction results showed that Pt particles were dispersed on the support with mean particle size of about 10.56 nm. Transition electron microscopy images showed that the nanosized WC/C were successfully coated by PANI. Based on the electrochemical properties characterized by cyclic voltammetry, CO stripping and rotating disk electrode measurements it was found that the as prepared Pt/PANI/WC/C electrocatalyst exhibited a comparable activity for methanol oxidation reaction and oxygen reduction reaction with respect to the commercial one. A significant reduction in the potential of CO electro-oxidation peak from 0.75 V for Pt/C to 0.52 V for Pt/PANI/WC/C electrocatalyst indicates that an increase in the activity for CO electro-oxidation is achieved by replacing the carbon support by PANI coated WC/C. Chronoamerometry results also showed, in the presence of methanol the Pt/PANI/WC/C electrocatalyst still maintains a higher current density than Pt/WC/C and Pt/C.
-
Directory of Open Access Journals (Sweden)
R. Bera
2017-05-01
Full Text Available To avoid the interference of electromagnetic radiation from other devices, an electronic device needs to be fabricated with flexible and light weight electromagnetic interference (EMI shielding materials with high efficiency. According, highly flexible porous poly(vinylidene fluoride (PVDF/PFR (Fe3O4 decorated polyaniline/RGO composite composite was prepared through solution blending of PVDF with pre-synthesized PFR conductive composite that involves in-situ oxidative polymerization of aniline in the presence of reduced graphene oxide (RGO using FeCl3 as oxidant. The porous morphology of the composite was created by leaching out of mixed NaCl from the composite. Polyaniline and RGO were mutually decorated by chemically in-situ synthesized ferrosoferric oxide (Fe3O4 using the Fe source of FeCl3. A homogeneous dispersion of PFR in insulated PVDF matrix resulted in a highly electrical conductive composite (PVDF-PFR material through formation of three dimensional continuous conductive networks of polyaniline-RGO in the matrix phase. The composite shows an outstanding EMI shielding effectiveness (EMI SE property due to the porous structure and the presence of conductive network and ferromagnetic Fe3O4 nanoparticles. The PVDF-PFR composite (0.5 mm thickness depicts a great permittivity and permeability value and achieve high EMI SE value (≈–28.18 dB and conductivity value of ≈1.10·10–1 S·cm–1 at very low loading (5 wt% of RGO.
-
International Nuclear Information System (INIS)
Cedrola, S.M.L.; Costa, M.F. da; Pasqualino, I.P.
2010-01-01
Pipelines are of great concern in the transport sector of oil and gas industries, mainly due to the natural internal aging process caused by contact with the different transported fluids. Installation of polymeric pipes called liners is a good option for rehabilitation of long segments of deteriorated pipelines. Among the potential materials for such application is Poly (vinylidene fluoride) (PVDF). Meanwhile the installation process cannot be carried out in one single step and the polymeric pipe must be cut in sections that are welded during the installation process. In this research welding methodology was studied aiming to optimize welding conditions and the mechanical properties of the joined materials. The first step was processing the PVDF via compression molding on different conditions. Then, the sample was cut and butt-welded. Welding parameters such as, time control, temperature and contact pressure were studied. Afterwards, the stress-strain properties of the welded material was evaluated and physical characterization was carried by x-ray diffraction (DRX). (author)
-
A Close Look at Charge Generation in Polymer:Fullerene Blends with Microstructure Control
Scarongella, Mariateresa
2015-03-04
© 2015 American Chemical Society. We reveal some of the key mechanisms during charge generation in polymer:fullerene blends exploiting our well-defined understanding of the microstructures obtained in pBTTT:PCBM systems via processing with fatty acid methyl ester additives. Based on ultrafast transient absorption, electro-absorption, and fluorescence up-conversion spectroscopy, we find that exciton diffusion through relatively phase-pure polymer or fullerene domains limits the rate of electron and hole transfer, while prompt charge separation occurs in regions where the polymer and fullerene are molecularly intermixed (such as the co-crystal phase where fullerenes intercalate between polymer chains in pBTTT:PCBM). We moreover confirm the importance of neat domains, which are essential to prevent geminate recombination of bound electron-hole pairs. Most interestingly, using an electro-absorption (Stark effect) signature, we directly visualize the migration of holes from intermixed to neat regions, which occurs on the subpicosecond time scale. This ultrafast transport is likely sustained by high local mobility (possibly along chains extending from the co-crystal phase to neat regions) and by an energy cascade driving the holes toward the neat domains.
-
A Close Look at Charge Generation in Polymer:Fullerene Blends with Microstructure Control
Scarongella, Mariateresa; De Jonghe-Risse, Jelissa; Buchaca-Domingo, Ester; Causa’ , Martina; Fei, Zhuping; Heeney, Martin; Moser, Jacques-E.; Stingelin, Natalie; Banerji, Natalie
2015-01-01
© 2015 American Chemical Society. We reveal some of the key mechanisms during charge generation in polymer:fullerene blends exploiting our well-defined understanding of the microstructures obtained in pBTTT:PCBM systems via processing with fatty acid methyl ester additives. Based on ultrafast transient absorption, electro-absorption, and fluorescence up-conversion spectroscopy, we find that exciton diffusion through relatively phase-pure polymer or fullerene domains limits the rate of electron and hole transfer, while prompt charge separation occurs in regions where the polymer and fullerene are molecularly intermixed (such as the co-crystal phase where fullerenes intercalate between polymer chains in pBTTT:PCBM). We moreover confirm the importance of neat domains, which are essential to prevent geminate recombination of bound electron-hole pairs. Most interestingly, using an electro-absorption (Stark effect) signature, we directly visualize the migration of holes from intermixed to neat regions, which occurs on the subpicosecond time scale. This ultrafast transport is likely sustained by high local mobility (possibly along chains extending from the co-crystal phase to neat regions) and by an energy cascade driving the holes toward the neat domains.
-
Sutherland, Richard L.
2002-12-01
Polarization properties and electro-optical switching behavior of holographic polymer-dispersed liquid-crystal (HPDLC) reflection and transmission gratings are studied. A theoretical model is developed that combines anisotropic coupled-wave theory with an elongated liquid-crystal-droplet switching model and includes the effects of a statistical orientational distribution of droplet-symmetry axes. Angle- and polarization-dependent switching behaviors of HPDLC gratings are elucidated, and the effects on dynamic range are described. A new type of electro-optical switching not seen in ordinary polymer-dispersed liquid crystals, to the best of the author's knowledge, is presented and given a physical interpretation. The model provides valuable insight to the physics of these gratings and can be applied to the design of HPDLC holographic optical elements.
-
International Nuclear Information System (INIS)
Stöckl, Markus; Schlegel, Christin; Sydow, Anne; Holtmann, Dirk; Ulber, Roland; Mangold, Klaus-Michael
2016-01-01
Highlights: • Development of a membrane separated electrochemical flow cell. • Simultaneous combination of EIS and CLSM. • Monitoring of bacterial cell attachment to anode of MFC. • Cell attachment of Shewanella oneidensis is shown. - Abstract: Understanding the attachment of electro-active bacteria to electrode surfaces and their subsequent biofilm formation is one of the major challenges for the establishment of bacterial bioelectrochemial systems (BES). For a constant observation of biofilm growth, providing information on different stages of biofilm formation, continuous monitoring methods are required. In this paper a combination of two powerful analytical methods, Electrochemical Impedance Spectroscopy (EIS) and Confocal Laser Scanning Microscopy (CLSM), for biofilm monitoring is presented. A custom-built flow cell with a transparent indium tin oxide working electrode (WE) was constructed allowing monitoring of cell attachment to a working electrode simultaneously by EIS and CLSM. Cyclic Voltammetry (CV) and EIS of an iron (II)/iron (III) redox couple indicate that the flow cell is suitable for electrochemical experiments. An engineered Shewanella oneidensis MR-1 (ATCC700550) producing eGFP was used as electro-active model organism to demonstrate the practical application of the flow cell as BES to monitor cell attachment simultaneously with EIS and CLSM. Applying the flow cell as MFC (transparent working electrode poised as anode) produced a typical current curve for such a system. From the equivalent circuit used to interpret EIS data the charge transfer resistance R CT is sensitive to attachment of microorganisms. Fitted R CT was increased initially after cell inoculation and then lowered constantly with progressing experimental time. In parallel taken CLSM images show that bacteria already adhered to the WE 5 min after inoculation. A mono- respectively bilayer of electro-active cells was observed after 17 h on the WE surface. With the presented
-
Preparation and properties of homogeneous-reinforced polyvinylidene fluoride hollow fiber membrane
Energy Technology Data Exchange (ETDEWEB)
Zhang Xuliang [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300387 (China); Xiao Changfa, E-mail: xiaotjpu@163.com [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300387 (China); Hu Xiaoyu; Bai Qianqian [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300387 (China)
2013-01-01
Highlights: Black-Right-Pointing-Pointer The homogeneous-reinforced method has been adopted firstly in preparing of PVDF membranes. Black-Right-Pointing-Pointer The HR membranes have a favorable interfacial bonding between the coating layer and the matrix membrane. Black-Right-Pointing-Pointer The better performance of the HR membranes in protein solution can indirectly improve the service life of membranes. - Abstract: Homogeneous-reinforced (HR) polyvinylidene fluoride (PVDF) hollow fiber membranes include PVDF polymer solutions (coating layer) and the matrix membrane prepared through the dry-wet spinning process. The performance of HR membranes varies with the polymer concentration in the polymer solutions and is characterized in terms of pure water flux, rejection of protein, porosity, infiltration property, a mechanical strength test, and morphology observations by a field emission scanning electron microscope (FESEM). The results of this study indicate that the tensile strength of the HR PVDF membranes decreases slights compared with that of the matrix membrane, but the elongation at break increases much more and the hollow fiber membranes are endowed with better flexibility performance. The HR PVDF hollow fiber membranes have a favorable interfacial bonding between the coating layer and the matrix membrane, as shown by FESEM. The infiltration property is characterized by the contact angle experiments. Pure water flux decreases while the rejection ratio with an increase in polymer concentration increasing. The protein solution flux of the HR PVDF membranes is higher than that of the matrix membrane after 100 min of infiltration.
-
Preparation and properties of homogeneous-reinforced polyvinylidene fluoride hollow fiber membrane
International Nuclear Information System (INIS)
Zhang Xuliang; Xiao Changfa; Hu Xiaoyu; Bai Qianqian
2013-01-01
Highlights: ► The homogeneous-reinforced method has been adopted firstly in preparing of PVDF membranes. ► The HR membranes have a favorable interfacial bonding between the coating layer and the matrix membrane. ► The better performance of the HR membranes in protein solution can indirectly improve the service life of membranes. - Abstract: Homogeneous-reinforced (HR) polyvinylidene fluoride (PVDF) hollow fiber membranes include PVDF polymer solutions (coating layer) and the matrix membrane prepared through the dry-wet spinning process. The performance of HR membranes varies with the polymer concentration in the polymer solutions and is characterized in terms of pure water flux, rejection of protein, porosity, infiltration property, a mechanical strength test, and morphology observations by a field emission scanning electron microscope (FESEM). The results of this study indicate that the tensile strength of the HR PVDF membranes decreases slights compared with that of the matrix membrane, but the elongation at break increases much more and the hollow fiber membranes are endowed with better flexibility performance. The HR PVDF hollow fiber membranes have a favorable interfacial bonding between the coating layer and the matrix membrane, as shown by FESEM. The infiltration property is characterized by the contact angle experiments. Pure water flux decreases while the rejection ratio with an increase in polymer concentration increasing. The protein solution flux of the HR PVDF membranes is higher than that of the matrix membrane after 100 min of infiltration.
-
DEFF Research Database (Denmark)
2008-01-01
R&D international contributions to design of next generation of mechatronic products, competencies and novel actuator technology.Special topics including Electro Active Polymers (artificial muscles).......R&D international contributions to design of next generation of mechatronic products, competencies and novel actuator technology.Special topics including Electro Active Polymers (artificial muscles)....
-
Modeling and control of a self-sensing polymer metal composite actuator
International Nuclear Information System (INIS)
Nam, Doan Ngoc Chi; Ahn, Kyoung Kwan
2014-01-01
An ion polymer metal composite (IPMC) is an electro-active polymer (EAP) that bends in response to a small applied electrical field as a result of mobility of cations in the polymer network and vice versa. One drawback in the use of an IPMC is the sensing problem for such a small size actuator. The aim of this paper is to develop a physical model for a self-sensing IPMC actuator and to verify its applicability for practical position control. Firstly, ion dynamics inside a polymer membrane is investigated with an asymmetric solution in the presence of distributed surface resistance. Based on this analysis, a modified equivalent circuit and a simple configuration to realize the self-sensing IPMC actuator are proposed. Mathematical modelling and experimental evaluation indicate that the bending curvature can be obtained accurately using several feedback voltage signals along with the IPMC length. Finally, the controllability of the developed self-sensing IPMC actuator is investigated using a robust position control. Experimental results prove that the self-sensing characteristics can be applied in engineering control problems to provide a more convenient sensing method for IPMC actuating systems. (paper)
-
Study of β-phase development in spin-coated PVDF thick films
Indian Academy of Sciences (India)
2017-06-09
Jun 9, 2017 ... C and increase in spin speed increases the β-phase ... extensively used in the field of sensors and actuators [1–8]. ... some methods to achieve these polar phases in PVDF such as ... ites with materials, such as, gold nanoparticles [14], carbon ..... change in degree of crystallinity of the films subject to the ...
-
International Nuclear Information System (INIS)
Ahmad, Zeeshan; Prasad, Ashutosh; Prasad, K.
2009-01-01
The present study addresses the problem of quantitative prediction of effective relative permittivity, dielectric loss factor, piezoelectric charge coefficient, and Young's modulus of PZT/PVDF diphasic ceramic-polymer composite as a function of volume fraction of PZT in the different compositions. Theoretical results for effective relative permittivity derived from several dielectric mixture equations like those of Knott, Rother-Lichtenecker, Bruggeman, Maxwell-Wagner-Webmann-Skipetrov or Dias-Dasgupta, Furukawa, Lewin, Wiener, Jayasundere-Smith, Modified Cule-Torquato, Taylor, Poon-Shin and Rao et al. were fitted to the experimental data taken from previous works of Yamada et al. Similarly, the results for effective piezoelectric coefficient and Young's modulus, derived from different appropriate equations were fitted to the corresponding experimental data taken from the literature. The study revealed that only a few equations like modified Rother-Lichtenecker equation, Dias-Dasgupta equation and Rao equation for dielectric and piezoelectric properties while the four new equations developed in the present study of elastic property (Young's modulus) well fitted the corresponding experimental results. Further, the acceptable data put to various regression analyses showed that in most of the cases the third order polynomial regression analysis provided more acceptable fits.
-
Pt-Si Bifunctional Surfaces for CO and Methanol Electro-Oxidation
DEFF Research Database (Denmark)
Permyakova, Anastasia A.; Han, Binghong; Jensen, Jens Oluf
2015-01-01
and storage. Here we report on Pt-Si bulk samples prepared by arc-melting, for the first time, with high activities toward the electro-oxidation of CO and methanol. Increasing the Si concentration on the surface was correlated with the shifts of onset oxidation potentials to lower values and higher activities...... for CO and methanol electro-oxidation. It is proposed that the reaction on the Pt-Si catalyst could follow a Langmuir-Hinshelwood type of mechanism, where substantially enhanced catalytic activity is attributed to the fine-tuning of the surface Pt-Si atomic structure....
-
Xiao, Peishuang; Yi, Ningbo; Zhang, Tengfei; Huang, Yi; Chang, Huicong; Yang, Yang; Zhou, Ying; Chen, Yongsheng
2016-06-01
Smart actuators have many potential applications in various areas, so the development of novel actuation materials, with facile fabricating methods and excellent performances, are still urgent needs. In this work, a novel electromechanical bimorph actuator constituted by a graphene layer and a PVDF layer, is fabricated through a simple yet versatile solution approach. The bimorph actuator can deflect toward the graphene side under electrical stimulus, due to the differences in coefficient of thermal expansion between the two layers and the converse piezoelectric effect and electrostrictive property of the PVDF layer. Under low voltage stimulus, the actuator (length: 20 mm, width: 3 mm) can generate large actuation motion with a maximum deflection of about 14.0 mm within 0.262 s and produce high actuation stress (more than 312.7 MPa/g). The bimorph actuator also can display reversible swing behavior with long cycle life under high frequencies. on this basis, a fish-like robot that can swim at the speed of 5.02 mm/s is designed and demonstrated. The designed graphene-PVDF bimorph actuator exhibits the overall novel performance compared with many other electromechanical avtuators, and may contribute to the practical actuation applications of graphene-based materials at a macro scale.
-
Xiao, Peishuang; Yi, Ningbo; Zhang, Tengfei; Chang, Huicong; Yang, Yang; Zhou, Ying
2016-01-01
Smart actuators have many potential applications in various areas, so the development of novel actuation materials, with facile fabricating methods and excellent performances, are still urgent needs. In this work, a novel electromechanical bimorph actuator constituted by a graphene layer and a PVDF layer, is fabricated through a simple yet versatile solution approach. The bimorph actuator can deflect toward the graphene side under electrical stimulus, due to the differences in coefficient of thermal expansion between the two layers and the converse piezoelectric effect and electrostrictive property of the PVDF layer. Under low voltage stimulus, the actuator (length: 20 mm, width: 3 mm) can generate large actuation motion with a maximum deflection of about 14.0 mm within 0.262 s and produce high actuation stress (more than 312.7 MPa/g). The bimorph actuator also can display reversible swing behavior with long cycle life under high frequencies. on this basis, a fish‐like robot that can swim at the speed of 5.02 mm/s is designed and demonstrated. The designed graphene‐PVDF bimorph actuator exhibits the overall novel performance compared with many other electromechanical avtuators, and may contribute to the practical actuation applications of graphene‐based materials at a macro scale. PMID:27818900
-
Activated Flake Graphite Coated with Pyrolysis Carbon as Promising Anode for Lithium Storage
International Nuclear Information System (INIS)
Chen, Jun; Zou, Guoqiang; Zhang, Yan; Song, Weixin; Hou, Hongshuai; Huang, Zhaodong; Liao, Hanxiao; Li, Simin; Ji, Xiaobo
2016-01-01
A facile route to improve the lithium-storage properties of flake graphite (FG) is proposed through coating pyrolysis carbon from polyvinylidene fluoride (PVDF) assisted by KOH activation. The interplanar distance between the graphene sheets of activated PVDF/FG is enlarged, effectively suppressing the electrode deformation during lithium (de)-intercalation. More edge and porous structures of PVDF/FG arising from KOH activation on graphite flakes contribute to improved electron and ion transport, leading to great improvement in its rate and cycling performances. The initial specific capacity of the activated PVDF/FG is 476.6 mAh g −1 at 50 mA g −1 and when the current increases to 1000 mA g −1 , the value still retains 142.6 mAh g −1 .
-
Spontaneously Bi decorated carbon supported Pd nanoparticles for formic acid electro-oxidation
International Nuclear Information System (INIS)
Bauskar, Akshay S.; Rice, Cynthia A.
2013-01-01
Highlights: • Selective decoration of Bi onto commercial Pd/C is carried out by a simple gas controlled surface potential modulation technique. • Bi decorated Pd/C catalyst exhibits higher and sustained formic acid oxidation activity presumably via the electronic effect. • Shielding of Pd atoms by Bi increases long term stability. • Formic acid electro-oxidation current increased by 121% at 0.2 V vs. RHE. -- Abstract: The activity and stability of carbon supported palladium (Pd/C) nanoparticles decorated with a submonolayer of bismuth (Bi) for formic acid (FA) electro-oxidation was investigated herein. The FA electro-oxidation activity enhancement of Bi decorated Pd/C was evaluated electrochemically using a rotating disk electrode configuration by linear sweep voltammetric and chronoamperometric measurements. Commercial Pd/C was decorated by irreversible adsorption of Bi via a simple gas controlled surface potential modulation technique, and the coverage of Bi adatoms as measured by cyclic voltammetry was controlled in the range of 30–87%. An optimal Bi coverage was observed to be 40%, resulting in a favorable decrease in the FA onset potential by greater than 0.1 V and increase in electro-oxidation current density from 0.25 mA cm −2 SA to 0.55 mA cm −2 SA at 0.2 V vs. RHE, compared to commercial Pd/C. The results indicate that Bi decorated Pd nanoparticles have excellent properties for the electro-oxidation of FA, i.e. high electro-catalytic activity and excellent stability, due to sustained promotion of dehydrogenation pathway attributed to the electronic effect, thereby promoting FA adsorption in the CH-down orientation. Based on no significant shifting in the CO stripping peak position, minimal impact of Bi on the Pd-CO bond strength is observed. Chronoamperometry results show much better long-term electro-catalytic activity for Bi decorated Pd nanoparticles attributed to shielding of surface Pd atoms by Bi and reducing Pd dissolution
-
Zhang, Shuyou; Cao, Jingjing; Ma, Na; You, Meng; Wang, Xushan; Meng, Jianqiang
2018-01-01
A fast and facile protocol is reported aiming at improving the antifouling property and hemocompatibility of poly(vinylidene fluoride) (PVDF) membranes by tethering PEG hydrogel and zwitterion immobilization. The coated PEG hydrogel was first prepared by interfacial polymerization and tethered on an alkali treated PVDF membrane (PVDFA) surface via a simultaneous thio-ene and thiol-epoxy reaction. Then, the thiol groups of cysteine reacted with the epoxy groups in PEG hydrogel to fabricate the PVDFA-g-Cys membrane. The membrane fabrication was complete within less than 20 min and was conducted in mild conditions. The successful preparation of PVDFA-g-Cys membrane was confirmed by ATR-FTIR and XPS. Raman spectroscopy showed that the hydrogels covalently bonded to the PVDF membrane surface. The membrane retained its mechanical strength after modification. The SEM measurements suggested that the membrane became denser after hydrogel coating, meanwhile, the EDX test verified that the functional species uniformly distributed in the membrane matrix. Water contact angle (WCA), protein adsorption and protein filtration tests showed significant improvements in hydrophilicity and antifouling properties for the modified membrane. The negativity of the membrane surface measured by the streaming potential method provides a basis for protein resistance and hemocompatibility. Moreover, the suppressed platelet adhesion and prolonged plasma coagulant time show that the PVDFA-g-Cys membrane has ultralow thrombotic potential and better hemocompatibility. The reported surface modification method combing thio-ene and thio-epoxy chemistry not only facilitates fabrication of hemocompatible PVDF membrane but also provide an universal chemical platform for multifunctionalization of porous membranes.
-
Kumar, Sweta Binod; Sharnagat, Preeti; Manna, Paramita; Bhattacharya, Amit; Haldar, Soumya
2017-02-01
Isolation of diversified bacteria from seawater is a major challenge in the field of environmental microbiology. In the present study, an attempt has been made to select specific membrane with improved property of attaching diversified bacteria. Initially, different concentrations (15, 18, and 20% W/W) of polysulfone (PSF) were used to check their affinity for the attachment of selected gram-positive (Bacillus subtilis) and gram-negative (Escherichia coli) bacteria. Among these, 20% W/W PSF showed maximum attachment. Therefore, membrane prepared with other materials such as polyvinylidene fluoride (PVDF) and polyether sulfone (PES) were used with the same concentration (20% W/W) to check their improved bacterial attachment property. Comparative study of bacterial attachment on three different membranes revealed that PVDF possessed the highest affinity towards both the groups of bacteria. This property was confirmed by different analytical methods viz. contact angle, atomic force microscopy, zeta potential, and flux study and further validated with seawater samples collected from seven sites of western coast and Lakshadweep island of India, using Biolog EcoPlate™. All the samples showed that bacterial richness and diversity was high in PVDF membrane in comparison to surrounding seawater samples. Interestingly, affinity for more diversified bacteria was reported to be higher in water sample with less turbidity and low bacteria load. This finding can facilitate the development of PVDF (20% W/W) membrane as a simple, cheap, and less labor intensive environmental sampling tool for the isolation of diversified bacteria from seawater sample wih different physiochemical properties. Graphical abstract ᅟ.
-
Energy Technology Data Exchange (ETDEWEB)
Nikooe, Naeme, E-mail: naeme.nikooe@stu.um.ac.ir; Saljoughi, Ehsan, E-mail: saljoughi@um.ac.ir
2017-08-15
Highlights: • Preparation of novel PVDF nanofiltration membranes with noticeable hydrophilicity. • Simultaneous achievement of hydrophilicity and dye removal via addition of Brij-58. • In situ modification and stability of hydrophilic property via addition of Brij-58. - Abstract: In the present research, for the first time PVDF/Brij-58 blend nanofiltration membranes with remarkable performance in filtration of dye aqueous solution were prepared via immersion precipitation. A noticeable improvement in water permeation and fouling resistance of the PVDF membranes was achieved by using Brij-58 surfactant as a hydrophilic additive. Scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and water contact angle were applied for the investigation of membrane morphology, detection of the surface chemical composition and relative hydrophilicity/hydrophobicity, respectively. The membrane performance was studied and compared by determination of pure water flux (PWF) and filtration of synthetic reactive dye aqueous solutions as well as bovine serum albumin (BSA) as foulant model. It was found out that addition of 4 wt.% Brij-58 to the casting solution results in formation of membrane with remarkable hydrophilicity and fouling resistance (contact angle of 46° and flux recovery ratio (FRR) = 90%), higher porosity and consequently noticeable PWF (31.2 L/m{sup 2} h) and recognized dye rejection value (90%) in comparison with the pristine PVDF nanofiltration membrane. Addition of Brij-58 surfactant to the casting solution resulted in formation of NF membrane with higher hydrophilicity and permeability as well as higher dye rejection value in comparison with the addition of PEG 400 additive.
-
Qi, Baoxin; Kong, Qingzhao; Qian, Hui; Patil, Devendra; Lim, Ing; Li, Mo; Liu, Dong; Song, Gangbing
2018-02-24
Compared to conventional concrete, polyvinyl alcohol fiber reinforced engineering cementitious composite (PVA-ECC) offers high-strength, ductility, formability, and excellent fatigue resistance. However, impact-induced structural damage is a major concern and has not been previously characterized in PVA-ECC structures. We investigate the damage of PVA-ECC beams under low-velocity impact loading. A series of ball-drop impact tests were performed at different drop weights and heights to simulate various impact energies. The impact results of PVA-ECC beams were compared with mortar beams. A combination of polyvinylidene fluoride (PVDF) thin-film sensors and piezoceramic-based smart aggregate were used for impact monitoring, which included impact initiation and crack evolution. Short-time Fourier transform (STFT) of the signal received by PVDF thin-film sensors was performed to identify impact events, while active-sensing approach was utilized to detect impact-induced crack evolution by the attenuation of a propagated guided wave. Wavelet packet-based energy analysis was performed to quantify failure development under repeated impact tests.
-
Hybrid Photonic Integration on a Polymer Platform
Directory of Open Access Journals (Sweden)
Ziyang Zhang
2015-09-01
Full Text Available To fulfill the functionality demands from the fast developing optical networks, a hybrid integration approach allows for combining the advantages of various material platforms. We have established a polymer-based hybrid integration platform (polyboard, which provides flexible optical input/ouptut interfaces (I/Os that allow robust coupling of indium phosphide (InP-based active components, passive insertion of thin-film-based optical elements, and on-chip attachment of optical fibers. This work reviews the recent progress of our polyboard platform. On the fundamental level, multi-core waveguides and polymer/silicon nitride heterogeneous waveguides have been fabricated, broadening device design possibilities and enabling 3D photonic integration. Furthermore, 40-channel optical line terminals and compact, bi-directional optical network units have been developed as highly functional, low-cost devices for the wavelength division multiplexed passive optical network. On a larger scale, thermo-optic elements, thin-film elements and an InP gain chip have been integrated on the polyboard to realize a colorless, dual-polarization optical 90° hybrid as the frontend of a coherent receiver. For high-end applications, a wavelength tunable 100Gbaud transmitter module has been demonstrated, manifesting the joint contribution from the polyboard technology, high speed polymer electro-optic modulator, InP driver electronics and ceramic electronic interconnects.
-
Electro-optically actuated liquid-lens zoom
Pütsch, O.; Loosen, P.
2012-06-01
Progressive miniaturization and mass market orientation denote a challenge to the design of dynamic optical systems such as zoom-lenses. Two working principles can be identified: mechanical actuation and application of active optical components. Mechanical actuation changes the focal length of a zoom-lens system by varying the axial positions of optical elements. These systems are limited in speed and often require complex coupled movements. However, well established optical design approaches can be applied. In contrast, active optical components change their optical properties by varying their physical structure by means of applying external electric signals. An example are liquidlenses which vary their curvatures to change the refractive power. Zoom-lenses benefit from active optical components in two ways: first, no moveable structures are required and second, fast response characteristics can be realized. The precommercial development of zoom-lenses demands simplified and cost-effective system designs. However the number of efficient optical designs for electro-optically actuated zoom-lenses is limited. In this paper, the systematic development of an electro-optically actuated zoom-lens will be discussed. The application of aberration polynomials enables a better comprehension of the primary monochromatic aberrations at the lens elements during a change in magnification. This enables an enhanced synthesis of the system behavior and leads to a simplified zoom-lens design with no moving elements. The change of focal length is achieved only by varying curvatures of targeted integrated electro-optically actuated lenses.
-
Nickel as a catalyst for the electro-oxidation of methanol in alkaline medium
Abdel Rahim, M. A.; Abdel Hameed, R. M.; Khalil, M. W.
The use of Ni as a catalyst for the electro-oxidation of methanol in alkaline medium was studied by cyclic voltammetry. It was found that only Ni dispersed on graphite shows a catalytic activity towards methanol oxidation but massive Ni does not. Ni was dispersed on graphite by the electro-deposition from acidic NiSO 4 solution using potentiostatic and galvanostatic techniques. The catalytic activity of the C/Ni electrodes towards methanol oxidation was found to vary with the amount of electro-deposited Ni. The dependence of the oxidation current on methanol concentration and scan rate was discussed. It was concluded from the electro-chemical measurements and SEM analysis that methanol oxidation starts as Ni-oxide is formed on the electrode surface.
-
Directory of Open Access Journals (Sweden)
В.В. Березуцький
2012-10-01
Full Text Available In the article theoretical bases of electro-coagulation of admixtures are examined in a water technological environment with the use of theory of the active hittings, which are based on the results of the executed researches and analysis of scientific information. Application of theory of the active hittings is in coagulation, provides high efficiency of process of extraction of admixtures from water environments during minimization of energy consumption and expenses of materials.
-
Transflective multiplexing of holographic polymer dispersed liquid crystal using Si additives
Directory of Open Access Journals (Sweden)
2011-01-01
Full Text Available Morphology, grating formation dynamics and electro-optical performance of transflective multiplexing with holographic polymer dispersed liquid crystal (HPDLC were investigated in the presence of silica nanoparticles (Aerosil R812 (RS and modified Aerosil 200 (MS and silicon monomer (vinyltrimethoxy silane (VTMS by using three coherent laser beams. The addition of Si additive significantly augmented the diffraction efficiencies of transmission and reflection gratings due to the enhanced phase separation with large LC channels. The film was driven only with Si additives which are enriched at the polymer-LC interfaces. As the additive content increased, driving voltage decreased to a minimum of 30 V at 2.0 wt% VTMS. It was found that the interface modification and large droplet size are crucial to operate the film. Among the three types of Si additive, VTMS showed the highest electro-optical performance due to its low viscosity and high reactivity.
-
Electro-active paper for a durable biomimetic actuator
International Nuclear Information System (INIS)
Yun, Sung-Ryul; Yun, Gyu Young; Kim, Jung Hwan; Chen, Yi; Kim, Jaehwan
2009-01-01
Cellulose electro-active paper (EAPap), known as a smart material, has merits in terms of low voltage operation, light weight, dryness, low power consumption, biodegradability, abundance and low price. Since EAPap requires low power consumption, a remotely driven actuator has been proposed using microwave power transmission. This concept is attractive for many biomimetic systems such as crawling micro-insect robots, flying objects like dragon flies and smart wallpapers. However, the actuation performance of EAPap is sensitive to humidity and degrades with time. Thus, in this paper, a durable EAPap is studied. The fabrication of EAPap is explained and the actuation performance is shown with applied electric field, frequency, humidity level and time. The fabrication process includes dissolving cellulose fibers, eliminating solvent and Li ions with a mixture of deionized water and isopropyl alcohol, washing with water, drying and coating with gold. The morphology of the fabricated EAPap is analyzed by taking scanning electron microscope images and x-ray diffractograms. The actuation performance is tested in terms of bending displacement with frequency, time and humidity level
-
Roy, Krittish; Mandal, Dipankar
2018-04-01
In this work, we demonstrate a simple and facile route ofcadmium sulfide (CdS) nanoparticle (NPs) grafted reduced graphene oxide (rGO) synthesis. It is found that a pinch (0.25 wt%) of as synthesisedCdS/rGOnanocompositecan induce more than 90% of electroactive phases in the electrospunpoly(vinylidene fluoride) (PVDF) nanofiber. Moreover, CdS/rGO nanocomposite doped PVDF nanofiber based nanogenerator (NG) can generate an output voltage of approximately 4 V upon repetitive finger imparting. Thus, the NG can be used as a mechanical energy harvester and power source for portable electronic and optoelectronic wearable devices.
-
An improved method for piezoelectric characterization of polymers for energy harvesting applications
Gusarova, E.; Gusarov, B.; Zakharov, D.; Bousquet, M.; Viala, B.; Cugat, O.; Delamare, J.; Gimeno, L.
2013-12-01
This work presents an improved method for measuring the direct piezoelectric voltage and energy of flexible polymers. Well-controlled stress is applied with a four-point bending system and voltage is measured in real open-circuit conditions. The presented method separates the piezoelectric part from the measurement part by introducing a mechanical switch, allowing instantaneous post-deformation discharge measurements. Oscilloscope and contact-less electrostatic voltmeter are compared. Direct piezoelectric measurements under open-circuit conditions have been performed on commercial PVDF (polyvinylidene fluoride) and its copolymers. Significant differences to data sheet values (close-circuit conditions) are reported and commented.
-
An, Alicia Kyoungjin
2016-10-21
Fouling in membrane distillation (MD) results in an increase in operation costs and deterioration in a water quality. In this work, a poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) electrospun (E-PH) membrane was fabricated by hybridizing polydimethylsiloxane (PDMS) polymeric microspheres with superhydrophobicity onto the E-PH membrane via electrospinning. The resulting hybrid PDMS with E-PH (E-PDMS) membrane showed a significant enhancement in surface hydrophobicity (contact angle, CA = 155.4°) and roughness (Ra = 1,285mm). The zeta potential of E-PDMS membrane surface showed a higher negative value than that of a commercial PVDF (C-PVDF) membrane. These properties of E-PDMS membrane provided an antifouling in treating of differently-charged dyes and generated a flake-like dye–dye (loosely bound foulant) structure on the membrane surface rather than in the membrane pores. This also led to a high productivity of E-PDMS membrane (34 Lm-2h-1, 50% higher than that of C-PVDF membrane) without fouling or wetting. In addition, complete color removal and pure water production were achieved during a long-term operation. An application of intermittent water flushing (WF) in direct contact MD (DCMD) operation led to a 99% CA recovery of E-PDMS membrane indicating its sustainability. Therefore, the E-PDMS membrane is a promising candidate for MD application in dyeing wastewater treatment.
-
Suitability of some common polymer films for MeV proton beam dosimetry
International Nuclear Information System (INIS)
Makkonen-Craig, S.; Paronen, M.; Arstila, K.; Helariutta, K.; Rauhala, E.; Tikkanen, P.
2005-01-01
We have been evaluating the efficacy of polymer films for proton beam dosimetry. PE, PS, PVF, PVDF, PFA and FEP films were irradiated with 4.1 and 9.4 MeV protons at a flux of 2.5 x 10 11 cm -2 s -1 and a fluence of 2.5 x 10 13 cm -2 . The perfluorinated films were relatively insensitive to the proton irradiation. The UV absorption of PS displayed significant radiation-induced red shift, but no quantifiable absorption peaks. The strongly absorbing chromophore at 225 nm of irradiated PVDF is too unstable for practical dosimetry. PE has a stable and moderately absorbing radiolytic chromophore at 235 nm, but is transparent in the visible wavelength region. Irradiated PVF absorbs strongly in both UV and visible regions, and its UV absorbance is linearly proportional to the dose over the range of 10-1000 kGy when irradiated with 4.1 MeV protons at a dose rate of 840 Gy s -1 . PVF shows the most potential as multipurpose dosimeter for high resolution profiling of ion beams. Pertinent applications include irradiations that require verification of lateral beam homogeneity
-
Solvent influence during radiation induced grafting of styrene in PVDF
International Nuclear Information System (INIS)
Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B.
2013-01-01
Radiation-induced grafting was studied to produce styrene grafted poly(vinylidene fluoride) (PVDF) membranes. PVDF films with 0.125 mm thickness were irradiated at doses between 5 and 20 kGy in the presence of styrene/N,N-dimethylformamide (DMF), styrene/acetone or styrene/toluene solutions (1:1, v/v) at dose rate of 5 kGy h -1 by simultaneous method, using gamma rays from a Co-60, under nitrogen atmosphere and at room temperature. The films were characterized before and after modification by grafting yield (GY %), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM and EDS), differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). GY results shows that grafting increases with dose and toluene hinders the grafting, leading to a small GY comparing to DMF and acetone. It was possible to confirm the grafting of styrene by FT-IR due to the new characteristics peaks and by the TG and DSC due to changes in thermal behavior of the grafted material. SEM and EDS show surface and cross-section distribution of the grafting, which takes place on the surface and heterogeneously with toluene as solvent and homogeneously and penetrating into the inner layers of the matrix using DMF and acetone as solvent. (author)
-
Solvent influence during radiation induced grafting of styrene in PVDF
Energy Technology Data Exchange (ETDEWEB)
Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B., E-mail: hp.ferreira@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2013-07-01
Radiation-induced grafting was studied to produce styrene grafted poly(vinylidene fluoride) (PVDF) membranes. PVDF films with 0.125 mm thickness were irradiated at doses between 5 and 20 kGy in the presence of styrene/N,N-dimethylformamide (DMF), styrene/acetone or styrene/toluene solutions (1:1, v/v) at dose rate of 5 kGy h{sup -1} by simultaneous method, using gamma rays from a Co-60, under nitrogen atmosphere and at room temperature. The films were characterized before and after modification by grafting yield (GY %), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM and EDS), differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). GY results shows that grafting increases with dose and toluene hinders the grafting, leading to a small GY comparing to DMF and acetone. It was possible to confirm the grafting of styrene by FT-IR due to the new characteristics peaks and by the TG and DSC due to changes in thermal behavior of the grafted material. SEM and EDS show surface and cross-section distribution of the grafting, which takes place on the surface and heterogeneously with toluene as solvent and homogeneously and penetrating into the inner layers of the matrix using DMF and acetone as solvent. (author)
-
Energy Technology Data Exchange (ETDEWEB)
Guarino, Vincenzo, E-mail: vguarino@unina.it; Altobelli, Rosaria; Cirillo, Valentina; Ambrosio, Luigi [Institute for Polymers, Composites and Biomaterials, Department of Chemical Sciences & Materials Technology, National Research Council of Italy, V.le Kennedy 54, Naples (Italy)
2015-12-17
A large variety of processes and tools is continuously investigated to discover new solutions to design instructive materials with controlled chemical, physical and biological properties for tissue engineering and drug delivery. Among them, electro fluido dynamic techniques (EFDTs) are emerging as an interesting strategy, based on highly flexible and low-cost processes, to revisit old biomaterial’s manufacturing approach by utilizing electrostatic forces as the driving force for the fabrication of 3D architectures with controlled physical and chemical functionalities to guide in vitro and in vivo cell activities. By a rational selection of polymer solution properties and process conditions, EFDTs allow to produce fibres and/or particles at micro and/or nanometric size scale which may be variously assembled by tailored experimental setups, thus giving the chance to generate a plethora of different 3D devices able to incorporate biopolymers (i.e., proteins, polysaccharides) or active molecules (e.g., drugs) for different applications. Here, we focus on the optimization of basic EFDTs - namely electrospinning, electrospraying and electrodynamic atomization - to develop active platforms (i.e., monocomponent, protein and drug loaded scaffolds and µ-scaffolds) made of synthetic (PCL, PLGA) or natural (chitosan, alginate) polymers. In particular, we investigate how to set materials and process parameters to impart specific morphological, biochemical or physical cues to trigger all the fundamental cell–biomaterial and cell– cell cross-talking elicited during regenerative processes, in order to reproduce the complex microenvironment of native or pathological tissues.
-
International Nuclear Information System (INIS)
Guarino, Vincenzo; Altobelli, Rosaria; Cirillo, Valentina; Ambrosio, Luigi
2015-01-01
A large variety of processes and tools is continuously investigated to discover new solutions to design instructive materials with controlled chemical, physical and biological properties for tissue engineering and drug delivery. Among them, electro fluido dynamic techniques (EFDTs) are emerging as an interesting strategy, based on highly flexible and low-cost processes, to revisit old biomaterial’s manufacturing approach by utilizing electrostatic forces as the driving force for the fabrication of 3D architectures with controlled physical and chemical functionalities to guide in vitro and in vivo cell activities. By a rational selection of polymer solution properties and process conditions, EFDTs allow to produce fibres and/or particles at micro and/or nanometric size scale which may be variously assembled by tailored experimental setups, thus giving the chance to generate a plethora of different 3D devices able to incorporate biopolymers (i.e., proteins, polysaccharides) or active molecules (e.g., drugs) for different applications. Here, we focus on the optimization of basic EFDTs - namely electrospinning, electrospraying and electrodynamic atomization - to develop active platforms (i.e., monocomponent, protein and drug loaded scaffolds and µ-scaffolds) made of synthetic (PCL, PLGA) or natural (chitosan, alginate) polymers. In particular, we investigate how to set materials and process parameters to impart specific morphological, biochemical or physical cues to trigger all the fundamental cell–biomaterial and cell– cell cross-talking elicited during regenerative processes, in order to reproduce the complex microenvironment of native or pathological tissues
-
Guarino, Vincenzo; Altobelli, Rosaria; Cirillo, Valentina; Ambrosio, Luigi
2015-12-01
A large variety of processes and tools is continuously investigated to discover new solutions to design instructive materials with controlled chemical, physical and biological properties for tissue engineering and drug delivery. Among them, electro fluido dynamic techniques (EFDTs) are emerging as an interesting strategy, based on highly flexible and low-cost processes, to revisit old biomaterial's manufacturing approach by utilizing electrostatic forces as the driving force for the fabrication of 3D architectures with controlled physical and chemical functionalities to guide in vitro and in vivo cell activities. By a rational selection of polymer solution properties and process conditions, EFDTs allow to produce fibres and/or particles at micro and/or nanometric size scale which may be variously assembled by tailored experimental setups, thus giving the chance to generate a plethora of different 3D devices able to incorporate biopolymers (i.e., proteins, polysaccharides) or active molecules (e.g., drugs) for different applications. Here, we focus on the optimization of basic EFDTs - namely electrospinning, electrospraying and electrodynamic atomization - to develop active platforms (i.e., monocomponent, protein and drug loaded scaffolds and µ-scaffolds) made of synthetic (PCL, PLGA) or natural (chitosan, alginate) polymers. In particular, we investigate how to set materials and process parameters to impart specific morphological, biochemical or physical cues to trigger all the fundamental cell-biomaterial and cell- cell cross-talking elicited during regenerative processes, in order to reproduce the complex microenvironment of native or pathological tissues.
-
Energy Technology Data Exchange (ETDEWEB)
Fontainha, C.C.P.; Nunes, M.; Rosas, V.A., E-mail: crissia@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Anatomia e Imagem; Furtado, C.A.; Faria, L.O. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)
2017-07-01
Medical radiology offers great benefit to patients, however, the radiation contributes for the workers and individuals exposure, significantly increasing dose to population. New attenuators materials have been widely investigated for radiation shielding to apply in medical procedures. Polymeric composites filled with attenuating metals and functionalized with carbon nanotubes (NTC) are being largely developed. In this work, composites were produced for radiation attenuation in radiodiagnostic imaging procedures. Two types of polymer matrices, polyvinylidene fluoride, PVDF, and its copolymer, poly(vinylidene-trifluorylene fluoride), P(VDF-TrFE), were filled bismuth oxide nanoparticles. Carbon nanotubes were added with different concentrations at the solution of attenuator metal under controlled magnetic stirring. The composites were characterized by differential heat flow scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and dispersive energy X-ray spectrometry (EDS) for thermal analysis. In this setup, one reference measure is directly exposed to the x-rays being diffracted by single crystal of Si (111). Another measure the attenuated beam is performed with the composite sample under detector. The samples present a good dispersion of the attenuator metal and the nanotube carbon. On the other hand, composites with PVDF matrix lost their plasticity, stiffening their structure, becoming brittle, even using the same methodology of synthesis. The P(VDF-Trfe) matrix showed better maleability than PVDF matrix. The cheaptube dispersion in the P(VDF-Trfe) matrix presented better than the 3100 carbon nanotubes. The attenuation for 8.047 keV monoenergetic photons was about 90% to 100 μm thickness for all composites. (author)
-
International Nuclear Information System (INIS)
Fontainha, C.C.P.; Nunes, M.; Rosas, V.A.
2017-01-01
Medical radiology offers great benefit to patients, however, the radiation contributes for the workers and individuals exposure, significantly increasing dose to population. New attenuators materials have been widely investigated for radiation shielding to apply in medical procedures. Polymeric composites filled with attenuating metals and functionalized with carbon nanotubes (NTC) are being largely developed. In this work, composites were produced for radiation attenuation in radiodiagnostic imaging procedures. Two types of polymer matrices, polyvinylidene fluoride, PVDF, and its copolymer, poly(vinylidene-trifluorylene fluoride), P(VDF-TrFE), were filled bismuth oxide nanoparticles. Carbon nanotubes were added with different concentrations at the solution of attenuator metal under controlled magnetic stirring. The composites were characterized by differential heat flow scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and dispersive energy X-ray spectrometry (EDS) for thermal analysis. In this setup, one reference measure is directly exposed to the x-rays being diffracted by single crystal of Si (111). Another measure the attenuated beam is performed with the composite sample under detector. The samples present a good dispersion of the attenuator metal and the nanotube carbon. On the other hand, composites with PVDF matrix lost their plasticity, stiffening their structure, becoming brittle, even using the same methodology of synthesis. The P(VDF-Trfe) matrix showed better maleability than PVDF matrix. The cheaptube dispersion in the P(VDF-Trfe) matrix presented better than the 3100 carbon nanotubes. The attenuation for 8.047 keV monoenergetic photons was about 90% to 100 μm thickness for all composites. (author)
-
Energy Technology Data Exchange (ETDEWEB)
Arbab, Alvira Ayoub, E-mail: alvira_arbab@yahoo.com [Department of Organic and Nano Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Sun, Kyung Chul, E-mail: hytec@hanyang.ac.kr [Department of Fuel cells and hydrogen technology, Hanyang University, Seoul 133-791 (Korea, Republic of); Sahito, Iftikhar Ali, E-mail: iftikhar.sahito@faculty.muet.edu.pk [Department of Organic and Nano Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Qadir, Muhammad Bilal, E-mail: bilal_ntu81@hotmail.com [Department of Organic and Nano Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Jeong, Sung Hoon, E-mail: shjeong@hanyang.ac.kr [Department of Organic and Nano Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)
2015-09-15
Graphical abstract: - Highlights: • We prepared three different types of enzyme dispersed multiwall carbon nanotube (E-MWCNT) layer for application in Pt-free dye sensitized solar cell (DSSCs). • E-MWCNT catalysts exhibited an extremely good electro-catalytic activity (ECA), compared with the conventional catalyst, when synthesized with lipase enzyme. • E-MWCNT as counter electrode exhibits a high power conversion efficiency (PCE) of 7.5%, which can be compared to 8% efficiency of Pt catalyst. - Abstract: Highly dispersed conductive suspensions of multi walled carbon nanotubes (MWCNT) can have intrinsic electrical and electrochemical characteristics, which make them useful candidate for platinum (Pt)-free, dye sensitized solar cells (DSSCs). High energy conversion efficiency of 7.52% is demonstrated in DSSCs, based on enzyme dispersed MWCNT (E-MWCNT) layer deposited on fluorine doped tin oxide (FTO) glass. The E-MWCNT layer shows a pivotal role as platform to reduce large amount of iodide species via electro catalytically active layer, fabricated by facile tape casting under air drying technique. The E-MWCNT layer with large surface area, high mechanical adhesion, and good interconnectivity is derived from an appropriate enzyme dispersion, which provides not only enhanced interaction sites for the electrolyte/counter electrode interface but also improved electron transport mechanism. The surface morphology and structural characterization were investigated using field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy and electronic microscopy techniques. Electro catalytic activity (ECA) and electrochemical properties of E-MWCNT counter electrode (CE) were investigated using cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) measurements. The high power conversion efficiency (PCE) of E-MWCNT CE is associated with the low charge transfer
-
International Nuclear Information System (INIS)
Arbab, Alvira Ayoub; Sun, Kyung Chul; Sahito, Iftikhar Ali; Qadir, Muhammad Bilal; Jeong, Sung Hoon
2015-01-01
Graphical abstract: - Highlights: • We prepared three different types of enzyme dispersed multiwall carbon nanotube (E-MWCNT) layer for application in Pt-free dye sensitized solar cell (DSSCs). • E-MWCNT catalysts exhibited an extremely good electro-catalytic activity (ECA), compared with the conventional catalyst, when synthesized with lipase enzyme. • E-MWCNT as counter electrode exhibits a high power conversion efficiency (PCE) of 7.5%, which can be compared to 8% efficiency of Pt catalyst. - Abstract: Highly dispersed conductive suspensions of multi walled carbon nanotubes (MWCNT) can have intrinsic electrical and electrochemical characteristics, which make them useful candidate for platinum (Pt)-free, dye sensitized solar cells (DSSCs). High energy conversion efficiency of 7.52% is demonstrated in DSSCs, based on enzyme dispersed MWCNT (E-MWCNT) layer deposited on fluorine doped tin oxide (FTO) glass. The E-MWCNT layer shows a pivotal role as platform to reduce large amount of iodide species via electro catalytically active layer, fabricated by facile tape casting under air drying technique. The E-MWCNT layer with large surface area, high mechanical adhesion, and good interconnectivity is derived from an appropriate enzyme dispersion, which provides not only enhanced interaction sites for the electrolyte/counter electrode interface but also improved electron transport mechanism. The surface morphology and structural characterization were investigated using field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy and electronic microscopy techniques. Electro catalytic activity (ECA) and electrochemical properties of E-MWCNT counter electrode (CE) were investigated using cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) measurements. The high power conversion efficiency (PCE) of E-MWCNT CE is associated with the low charge transfer
-
Electro-oxidation of methanol on copper in alkaline solution
International Nuclear Information System (INIS)
Heli, H.; Jafarian, M.; Mahjani, M.G.; Gobal, F.
2004-01-01
The electro-oxidation of methanol on copper in alkaline solutions has been studied by the methods of cyclic voltammetry, quasi-steady state polarization and chronoamperometry. It has been found that in the course of an anodic potential sweep the electro-oxidation of methanol follows the formation of Cu III and is catalysed by this species through a mediated electron transfer mechanism. The reaction also continues in the early stages of the reversed cycle until it is stopped by the prohibitively negative potentials. The process is diffusion controlled and the current-time responses follow Cottrellian behavior. The rate constants, turnover frequency, anodic transfer coefficient and the apparent activation energy of the electro-oxidation reaction are reported
-
Assiongbon, K. A.; Roy, D.
2005-12-01
Electro-catalytic oxidation of methanol is the anode reaction in direct methanol fuel cells. We have studied the adsorption characteristics of the intermediate reactants of this multistep reaction on a gold film electrode in alkaline solutions by combining surface plasmon resonance (SPR) measurements with Fourier transform electro-chemical impedance spectroscopy (FT-EIS). Methanol oxidation in this system shows no significant effects of "site poisoning" by chemisorbed CO. Our results suggest that OH - chemisorbed onto Au acts as a stabilizing agent for the surface species of electro-active methanol. Double layer charging/discharging and adsorption/desorption of OH - show more pronounced effects than adsorption/oxidation of methanol in controlling the surface charge density of the Au substrate. These effects are manifested in both the EIS and the SPR data, and serve as key indicators of the surface reaction kinetics. The data presented here describe the important role of adsorbed OH - in electro-catalysis of methanol on Au, and demonstrate how SPR and FT-EIS can be combined for quantitative probing of catalytically active metal-solution interfaces.
-
Energy Technology Data Exchange (ETDEWEB)
Lee, Jun Su; Chang, Jin Ho [Dept. of Electronic Engineering, Sogang University, Seoul (Korea, Republic of)
2015-04-15
Photoacoustic microscopy is capable of providing high-resolution molecular images, and its spatial resolution is typically determined by ultrasonic transducers used to receive the photoacoustic signals. Therefore, ultrasonic transducers for photoacoustic microscopy (PAM) should have a high operating frequency, broad bandwidth, and high signal-reception efficiency. Polyvinylidene fluoride (PVDF) is a suitable material. To take full advantage of this material, the selection of the backing material is crucial, as it influences the center frequency and bandwidth of the transducer. Therefore, we experimentally determined the most suitable backing material among EPO-TEK 301, E-Solder 3022, and RTV. For this, three PVDF high-frequency single-element transducers were fabricated with each backing material. The center frequency and -6 dB bandwidth of each transducer were ascertained by a pulse-echo test. The spatial resolution of each transducer was examined using wire-target images. The experimental results indicated that EPO-TEK 301 is the most suitable backing material for a PAM transducer. This material provides the highest signal magnitude and a reasonable bandwidth because a large portion of the energy propagates toward the front medium, and the PVDF resonates in the half-wave mode.
-
Active Polymers — Emergent Conformational and Dynamical Properties: A Brief Review
Winkler, Roland G.; Elgeti, Jens; Gompper, Gerhard
2017-10-01
Active matter exhibits a wealth of emerging nonequilibrium behaviours. A paradigmatic example is the interior of cells, where active components, such as the cytoskeleton, are responsible for its structural organization and the dynamics of the various components. Of particular interest are the properties of polymers and filaments. The intimate coupling of thermal and active noise, hydrodynamic interactions, and polymer conformations implies the emergence of novel structural and dynamical features. In this article, we review recent theoretical and simulation developments and results for the structural and dynamical properties of polymers exposed to activity. Two- and three-dimensional filaments are considered propelled by different mechanisms such as active Brownian particles or hydrodynamically-coupled force dipoles.
-
Jin, Zhao; Wang, Qiyu; Zheng, Weitao; Cui, Xiaoqiang
2016-03-02
The catalytic electro-oxidation of ethanol is the essential technique for direct alcohol fuel cells (DAFCs) in the area of alternative energy for the ability of converting the chemical energy of alcohol into the electric energy directly. Developing highly efficient and stable electrode materials with antipoisoning ability for ethanol electro-oxidation remains a challenge. A highly ordered periodic Au-nanoparticle (NP)-decorated bilayer TiO2 nanotube (BTNT) heteronanostructure was fabricated by a two-step anodic oxidation of Ti foil and the subsequent photoreduction of HAuCl4. The plasmon-induced charge separation on the heterointerface of Au/TiO2 electrode enhances the electrocatalytic activity and stability for the ethanol oxidation under visible light irradiation. The highly ordered periodic heterostructure on the electrode surface enhanced the light harvesting and led to the greater performance of ethanol electro-oxidation under irradiation compared with the ordinary Au NPs-decorated monolayer TiO2 nanotube (MTNT). This novel Au/TiO2 electrode also performed a self-cleaning property under visible light attributed to the enhanced electro-oxidation of the adsorbed intermediates. This light-driven enhancement of the electrochemical performances provides a development strategy for the design and construction of DAFCs.
-
Beretta, Giovanni L.; Folini, Marco; Cavalieri, Francesca; Yan, Yan; Fresch, Enrico; Kaliappan, Subramanian; Hasenöhrl, Christoph; Richardson, Joseph J.; Tinelli, Stella; Fery, Andreas; Caruso, Frank; Zaffaroni, Nadia
2015-03-01
Redox-active polymers and carriers are oxidizing nanoagents that can potentially trigger intracellular off-target effects. In the present study, we investigated the occurrence of off-target effects in prostate cancer cells following exposure to redox-active polymer and thin multilayer capsules with different chemical properties. We show that, depending on the intracellular antioxidant capacity, thiol-functionalized poly(methacrylic acid), PMASH triggers cell defense responses/perturbations that result in off-target effects (i.e., induction of autophagy and down-regulation of survivin). Importantly, the conversion of the carboxyl groups of PMASH into the neutral amides of poly(hydroxypropylmetacrylamide) (pHPMASH) nullified the off-target effects and cytotoxicity in tested cell lines. This suggests that the simultaneous action of carboxyl and disulfide groups in PMASH polymer or capsules may play a role in mediating the intracellular off-target effects. Our work provides evidence that the rational design of redox-active carriers for therapeutic-related application should be guided by a careful investigation on potential disturbance of the cellular machineries related to the carrier association.Redox-active polymers and carriers are oxidizing nanoagents that can potentially trigger intracellular off-target effects. In the present study, we investigated the occurrence of off-target effects in prostate cancer cells following exposure to redox-active polymer and thin multilayer capsules with different chemical properties. We show that, depending on the intracellular antioxidant capacity, thiol-functionalized poly(methacrylic acid), PMASH triggers cell defense responses/perturbations that result in off-target effects (i.e., induction of autophagy and down-regulation of survivin). Importantly, the conversion of the carboxyl groups of PMASH into the neutral amides of poly(hydroxypropylmetacrylamide) (pHPMASH) nullified the off-target effects and cytotoxicity in tested cell
-
Microring resonator based modulator made by direct photodefinition of an electro-optic polymer
Balakrishnan, M.; Faccini, M.; Diemeer, M. B. J.; Klein, E. J.; Sengo, G.; Driessen, A.; Verboom, W.; Reinhoudt, D. N.
2008-04-01
A laterally coupled microring resonator was fabricated by direct photodefinition of negative photoresist SU8, containing tricyanovinylidenediphenylaminobenzene chromophore, by exploiting the low ultraviolet absorption window of this chromophore. The ring resonator was first photodefined by slight cross-linking. Thereafter, poling (to align the chromophores) and further cross-linking (to increase the glass transition temperature) were simultaneously carried out. The material showed excellent photostability and the electro-optic modulation with an r33 of 11pm/V was demonstrated at 10MHz.
-
Energy Technology Data Exchange (ETDEWEB)
Jo, Du-Hwan; Noh, Sang-Geol; Park, Jong-Tae; Kang, Choon-Ho [POSCO Technical Research Laboratories, Pohang (Korea, Republic of)
2015-10-15
Recently, household electronic industries require environmentally-friendly and highly functional steels in order to enhance the quality of human life. Customers especially require both excellent corrosion and abrasion resistant anti-fingerprint steels for digital TV panels. Thus POSCO has developed new functional electro-galvanized steels, which have double coated layers with organic-inorganic composites on the zinc surface of the steel for usage as the bottom chassis panel of TVs. The inorganic solution for the bottom layer consists of inorganic phosphate, magnesium, and zirconium compounds with a small amount of epoxy binder, and affords both improved adhesion properties by chemical conversion reactions and corrosion resistance due to a self-healing effect. The composite solution for the top layer was prepared by fine dispersion of organic-inorganic ingredients that consist of a urethane modified polyacrylate polymer, hardener, silica sol and a titanium complex inhibitor in aqueous media. Both composite solutions were coated on the steel surface by using a roll coater and then cured through an induction furnace in the electro-galvanizing line. New anti-fingerprint steel was evaluated for quality performance through such procedures as the salt spray test for corrosion resistance, tribological test for abrasion resistance, and conductivity test for surface electric conductance regarding to both types of polymer resin and coating weight of composite solution. New composite coated anti-fingerprint steels afford both better corrosion resistance and abrasion properties compared to conventional anti-fingerprint steel that mainly consists of acrylate polymers. Detailed discussions of both composite solutions and experimental results suggest that urethane modifications of acrylate polymers of composite solutions play a key role in enhanced quality performances.
-
Polymeric drugs: Advances in the development of pharmacologically active polymers
Li, Jing; Yu, Fei; Chen, Yi; Oupický, David
2015-01-01
Synthetic polymers play a critical role in pharmaceutical discovery and development. Current research and applications of pharmaceutical polymers are mainly focused on their functions as excipients and inert carriers of other pharmacologically active agents. This review article surveys recent advances in alternative pharmaceutical use of polymers as pharmacologically active agents known as polymeric drugs. Emphasis is placed on the benefits of polymeric drugs that are associated with their macromolecular character and their ability to explore biologically relevant multivalency processes. We discuss the main therapeutic uses of polymeric drugs as sequestrants, antimicrobials, antivirals, and anticancer and anti-inflammatory agents. PMID:26410809
-
Dynamic structurization in solutions of hydrodynamically active polymers
International Nuclear Information System (INIS)
Pogrebnyak, V.G.; Tverdokhleb, S.V.; Naumchuk, N.V.
1993-01-01
The processes of ordering and self-regulation in nonlinear systems have attracted great attention because understanding the principles of self-regulation and its thermodynamics can become a clue to many physical phenomena. In this work, it is experimentally established that, under the condition of elongational flows, dynamic structurization and periodic processes may originate in the solutions of flexible, hydrodynamically-active polymers due to self-regulation in these systems. The hydrodynamic elongational field was created using the flow of a Newtonian liquid (water, acetone, dioxane) converging to a small opening. The hydrodynamically-active polymers were polyethylene oxide or hydrolyzed polyacrylamide
-
International Nuclear Information System (INIS)
Cui, Zhongping; Qi, Ji; Xu, Xinxin; Liu, Lu; Wang, Yi
2013-01-01
To enhance photocatalytic property of coordination polymer in visible light region, polyaniline (PANI) loaded coordination polymer photocatalyst was synthesized through in-situ chemical oxidation of aniline on the surface of coordination polymer. The photocatalytic activity of PANI loaded coordination polymer composite material for degradation of Rhodamine B (RhB) was investigated. Compared with pure coordination polymer photocatalyst, which can decompose RhB merely under UV light irradiation, PANI loaded coordination polymer photocatalyst displays more excellent photocatalytic activity in visible light region. Furthermore, PANI loaded coordination polymer photocatalyst exhibits outstanding stability during the degradation of RhB. - Graphical abstract: PANI loaded coordination polymer composite material, which displays excellent photocatalytic activity under visible light was firstly synthesized through in-situ chemical oxidation of aniline on surface of coordination polymer. Display Omitted - Highlights: • This PANI loaded coordination polymer composite material represents the first conductive polymer loaded coordination polymer composite material. • PANI/coordination polymer composite material displays more excellent photocatalytic activity for the degradation of MO in visible light region. • The “combination” of coordination polymer and PANI will enable us to design high-activity, high-stability and visible light driven photocatalyst in the future
-
DEFF Research Database (Denmark)
Pedersen, Katrine E; Einholm, Anja P; Christensen, Anni
2003-01-01
Negatively charged organochemical inactivators of the anti-proteolytic activity of plasminogen activator inhibitor-1 (PAI-1) convert it to inactive polymers. As investigated by native gel electrophoresis, the size of the PAI-1 polymers ranged from dimers to multimers of more than 20 units. As com...