DOCSLIB.ORG

Free Volume Effect Via Various Chemical Structured Monomers On

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Free Volume Effect Via Various Chemical Structured Monomers On polymers Article Free Volume Effect via Various Chemical Structured Monomers on Adhesion Property and Relative Permittivity in Acrylic Pressure Sensitive Adhesives Jung-Hun Lee 1,2, Ji-Soo Kim 2 , Hyun-Joong Kim 2,3,* , Kyujong Park 4, Jungwoo Moon 4, Jinyoung Lee 4 and Youngju Park 4 1 Carbon Composite Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, Jeonbuk 55324, Korea; [email protected] 2 Lab. of Adhesion and Bio-Composites, Program in Environmental Materials Science, Department of Agriculture, Forestry and Bioresources Seoul National University, Seoul 08826, Korea; [email protected] 3 Research Institute of Agriculture and Life Sciences, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea 4 Samsung Display Co., Ltd., Yongin 17113, Korea; [email protected] (K.P.); [email protected] (J.M.); [email protected] (J.L.); [email protected] (Y.P.) * Correspondence: [email protected]; Tel.: +82-2-880-4783 Received: 12 October 2020; Accepted: 5 November 2020; Published: 10 November 2020 Abstract: Acrylic pressure-sensitive adhesives (PSAs) are used as fixatives between layers of a display. PSAs’ function is an important factor that determines the performance of the display. Of the various display types available, the touch screen panel (TSP) of smart devices is firmly related to the relative permittivity of the elementals. Therefore, adjusting the relative permittivity of the PSA is indispensable for driving the TSP. Accordingly, selected acrylic pre-polymers were polymerized and the pre-polymer was blended and cross-linked with monomers with different chemical structure to adjust the relative permittivity. The monomers were hexametyldisiloxane (HMDS), N-vinylcaprolactam (NVC), tert-butyl acrylate (TBA), and isooctadecyl acrylate (ISTA). The gel fraction and transmittance as a function of the monomers show a similar result to the pure acrylic PSA. However, the gel fraction value decreased to about 90% and the transmittance decreased to about 85%, due to the immiscibility between nonpolar HMDS and acrylic PSA. On the other hand, the adhesion properties were improved when NVC was added because of the polarity of the nitrogen group. In addition, the relative permittivity of the PSA decreased regardless of the monomer chosen. There was, however, a difference in the optimal content of each monomer, and NVC decreased from 4 phr content to about 3.4 in reducing relative permittivity. Through the above results, it was confirmed that NVC having a nitrogen group is most advantageous in lowering adhesion properties and relative permittivity, and necessitates further research based on the findings. Keywords: acrylic pressure-sensitive adhesive; monomer; adhesion performance; relative permittivity; free volume 1. Introduction Pressure-sensitive adhesives (PSAs) are widely used in various industrial fields, such as medical products, aircraft, space shuttles, electrical devices, optical products, and automobiles. In particular, the demand for functional PSAs is rapidly increasing in the display market [1]. Displays are composed of a plurality of layer types and PSAs play an important fixative role. The PSA can fix the base material by applying slight pressure and becomes easy to adjust, Polymers 2020, 12, 2633; doi:10.3390/polym12112633 www.mdpi.com/journal/polymers Polymers 2020, 12, 2633 2 of 14 Polymers 2020, 12, x FOR PEER REVIEW 2 of 14 basewhile material the processing by applying rate slight can be pressure increased and [2 ].becomes Recently, easy to imto proveadjust, the while technological the processing development rate can beof increased displays, br[2].oader Recently, properties to improve of the PSA the technolo functiongical are required development including of displays, transparency broaderhigh properties elongation, ofhigh the recovery,PSA function and heatare required dissipation including [3]. transparency high elongation, high recovery, and heat dissipationOptical [3]. clarity means a transmittance of 90% or more in the range of 400 to 800 nm and PSA satisfies thisOptical criteria definingclarity means the utility a transmittance of optical clear of adhesives90% or more (OCAs). in the PSA range includes of 400 rubber, to 800 acrylic, nm and silicone, PSA satisfiesand urethane, this criteria and acrylic defining PSA the is widelyutility of used optical in terms clear of adhesives their optical (OCAs). clarity. PSA Mo reover,includes the rubber, process acrylic,time can silicone, be significantly and urethane, reduced, and andacrylic UV crosslinkingPSA is widely is considerablyused in terms economical of their optical as a techni clarity.que. Moreover,As the transmittance the process of time PSA can is a verybe significantly important factorreduced, in dis andplay UV qua crosslinlity, a lokingw transmittance is considerably may economicallimit its application as a technique. in the displayAs the transmittance industry [4,5]. of PSA is a very important factor in display quality, a low Atransmittance touch screen may panel limit (TSP) its isapplication a major technology in the display for increasing industry [4,5]. input convenience and reducing productA touch weight screen by panel replacing (TSP) theis a keyboardmajor technology in the display for increasing of electronic input convenience devices. The and demand reducing for productTSP has weight soared by owing replacing to the the spread keyboard of smart in the phones display and of tabletelectronic PCs, devices. and it is The essential demand to improvefor TSP hastouch soared sensitivity. owing to A the capacitive spread touchof smart screen phones panel and is tablet composed PCs, and of a topit is andessential bottom to improve plate, on touch which sensitivity.a transparent A capacitive electrode touch (indium screen tin oxide,panel ITO)is composed is deposited of a andtop and each bottom layer isplate, fixed on using which PSAs a transparent(see Figure 1electrode). As part (indium of the capacitive tin oxide, method,ITO) is deposited a current flowand operateseach layer through is fixed ITO using on onePSAs side (see of Figurethe glass 1). orAs apart transparent of the capacitive film and amethod, touch operation a current is flow recognized operates by through sensing ITO a change on one in side capacitance of the glassthat occursor a transparent when a finger film orand a toucha touch pen operation touches theis recognized touch screen by surface. sensing a change in capacitance that occurs when a finger or a touch pen touches the touch screen surface. FigureFigure 1. 1. StructureStructure of of capacitance capacitance type type touch touch screen screen pa panelnel (TSP). (TSP). PSA, PSA, pressu pressure-sensitivere-sensitive adhesive; adhesive; ITO,ITO, indium indium tin tin oxide. oxide. TheThe relative relative permittivity isis aa measuremeasure of of the the degree degree of polarizationof polarizati ofon electric of electric charges charges inside inside when whenan electric an electric field isfield applied is applied to the to non-conductor the non-conduc surfacetor surface from from the outside. the outside. From From this pointthis point of vie ofw, view,the non-cond the non-conductoructor is called is called the dielectric the dielectric ("). The (ε relative). The relative permittivity permittivity ("γ, dielectric (ɛγ, dielectric constant) constant) refers to refersthe ratio to the of theratio permittivity of the permittivity of the material of the base material relative base to therelative permittivity to the permittivity in a vacuum. in I na vacuum. other wo rds,In otherthe relative words, permittivitythe relative ispermittivi determinedty is bydetermined the permittivity by the ofpermittivity a substance of (see a substance Figure2)[ (see6] andFigure can 2) be [6]expressed and can bybe expressed the following by the equation: following equation: "γ = "/"0 (1) ɛγ = ɛ/ɛ0 (1) Over the past decade, the performance of microelectronic integrated circuits (ICs) that make-up Over the past decade, the performance of microelectronic integrated circuits (ICs) that make-up electronic devices has been improved owing to an increase in transistor speed and a decrease in size. electronic devices has been improved owing to an increase in transistor speed and a decrease in size. ICs have become faster and more complex because smaller transistors run faster. However, these efforts ICs have become faster and more complex because smaller transistors run faster. However, these are causing a decrease in the speed of signal propagation. The signal delay can increase with the size efforts are causing a decrease in the speed of signal propagation. The signal delay can increase with of the electronic device, which can degrade the performance of the final product. In other words, the size of the electronic device, which can degrade the performance of the final product. In other continuous shrinkage increases the speed of the transistor, but decreases the interconnection between words, continuous shrinkage increases the speed of the transistor, but decreases the interconnection the transistors. A way to improve this is to use a non-conductor with a low dielectric constant [7]. between the transistors. A way to improve this is to use a non-conductor with a low dielectric Non-conductors with a relative permittivity of 4.2 or less are called low-k dielectrics [8]. In addition, constant [7]. Non-conductors with a relative permittivity of 4.2 or less are called low-k
Load more

Recommended publications
  • Electric Permittivity of Carbon Fiber
    Carbon 143 (2019) 475e480 Contents lists available at ScienceDirect Carbon journal homepage: www.elsevier.com/locate/carbon Electric permittivity of carbon fiber * Asma A. Eddib, D.D.L. Chung Composite Materials Research Laboratory, Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260-4400, USA article info abstract Article history: The electric permittivity is a fundamental material property that affects electrical, electromagnetic and Received 19 July 2018 electrochemical applications. This work provides the first determination of the permittivity of contin- Received in revised form uous carbon fibers. The measurement is conducted along the fiber axis by capacitance measurement at 25 October 2018 2 kHz using an LCR meter, with a dielectric film between specimen and electrode (necessary because an Accepted 11 November 2018 LCR meter is not designed to measure the capacitance of an electrical conductor), and with decoupling of Available online 19 November 2018 the contributions of the specimen volume and specimen-electrode interface to the measured capaci- tance. The relative permittivity is 4960 ± 662 and 3960 ± 450 for Thornel P-100 (more graphitic) and Thornel P-25 fibers (less graphitic), respectively. These values are high compared to those of discon- tinuous carbons, such as reduced graphite oxide (relative permittivity 1130), but are low compared to those of steels, which are more conductive than carbon fibers. The high permittivity of carbon fibers compared to discontinuous carbons is attributed to the continuity of the fibers and the consequent substantial distance that the electrons can move during polarization. The P-100/P-25 permittivity ratio is 1.3, whereas the P-100/P-25 conductivity ratio is 67.
    [Show full text]
  • VELOCITY of PROPAGATION by RON HRANAC
    Originally appeared in the March 2010 issue of Communications Technology. VELOCITY OF PROPAGATION By RON HRANAC If you’ve looked at a spec sheet for coaxial cable, you’ve no doubt seen a parameter called velocity of propagation. For instance, the published velocity of propagation for CommScope’s F59 HEC-2 headend cable is "84% nominal," and Times Fiber’s T10.500 feeder cable has a published value of "87% nominal." What do these numbers mean, and where do they come from? We know that the speed of light in free space is 299,792,458 meters per second, which works out to 299,792,458/0.3048 = 983,571,056.43 feet per second, or 983,571,056.43/5,280 = 186,282.4 miles per second. The reciprocal of the free space value of the speed of light in feet per second is the time it takes for light to travel 1 foot: 1/983,571,056.43 = 1.02E-9 second, or 1.02 nanosecond. In other words, light travels a foot in free space in about a billionth of a second. Light is part of the electromagnetic spectrum, as is RF. That means RF zips along at the same speed that light does. "The major culprit that slows the waves down is the dielectric — and it slows TEM waves down a bunch." Now let’s define velocity of propagation: It’s the speed at which an electromagnetic wave propagates through a medium such as coaxial cable, expressed as a percentage of the free space value of the speed of light.
    [Show full text]
  • Importance of Varying Permittivity on the Conductivity of Polyelectrolyte Solutions
    Importance of Varying Permittivity on the Conductivity of Polyelectrolyte Solutions Florian Fahrenberger, Owen A. Hickey, Jens Smiatek, and Christian Holm∗ Institut f¨urComputerphysik, Universit¨atStuttgart, Allmandring 3, Stuttgart 70569, Germany (Dated: September 8, 2018) Dissolved ions can alter the local permittivity of water, nevertheless most theories and simulations ignore this fact. We present a novel algorithm for treating spatial and temporal variations in the permittivity and use it to measure the equivalent conductivity of a salt-free polyelectrolyte solution. Our new approach quantitatively reproduces experimental results unlike simulations with a constant permittivity that even qualitatively fail to describe the data. We can relate this success to a change in the ion distribution close to the polymer due to the built-up of a permittivity gradient. The dielectric permittivity " measures the polarizabil- grained approach is necessary due to the excessive sys- ity of a medium subjected to an electric field and is one of tem size. Molecular Dynamics (MD) simulations of only two fundamental constants in Maxwell's equations. charged systems typically work with the restricted prim- The relative permittivity of pure water at room temper- itive model by simulating the ions as hard spheres while ature is roughly 78.5, but charged objects dissolved in accounting for the solvent implicitly through a con- the fluid significantly reduce the local dielectric constant stant background dielectric. Crucially, the solvent me- because water dipoles align with the local electric field diates hydrodynamic interactions and reduces the elec- created by the object rather than the external field [1{3]. trostatic interactions due to its polarizability.
    [Show full text]
  • Measurement of Dielectric Material Properties Application Note
    with examples examples with solutions testing practical to show written properties. dielectric to the s-parameters converting for methods shows Italso analyzer. a network using materials of properties dielectric the measure to methods the describes note The application | | | | Products: Note Application Properties Material of Dielectric Measurement R&S R&S R&S R&S ZNB ZNB ZVT ZVA ZNC ZNC Another application note will be will note application Another <Application Note> Kuek Chee Yaw 04.2012- RAC0607-0019_1_4E Table of Contents Table of Contents 1 Overview ................................................................................. 3 2 Measurement Methods .......................................................... 3 Transmission/Reflection Line method ....................................................... 5 Open ended coaxial probe method ............................................................ 7 Free space method ....................................................................................... 8 Resonant method ......................................................................................... 9 3 Measurement Procedure ..................................................... 11 4 Conversion Methods ............................................................ 11 Nicholson-Ross-Weir (NRW) .....................................................................12 NIST Iterative...............................................................................................13 New non-iterative .......................................................................................14
    [Show full text]
  • Product Information PA 2200
    Product Information PA 2200 PA 2200 is a non-filled powder on basis of PA 12. General Properties Property Measurement Method Units Value DIN/ISO Water absorption ISO 62 / DIN 53495 100°C, saturation in water % 1.93 23°C, 96% RF % 1.33 23°C, 50% RF % 0.52 Property Measurement Method Unit Value DIN/ISO Coefficient of linear thermal ex- ISO 11359 / DIN 53752-A x10-4 /K 1.09 pansion Specific heat DIN 51005 J/gK 2.35 Thermal properties of sintered parts Property Measurement Method Unit Value DIN/ISO Thermal conductivity DIN 52616 vertical to sintered layers W/mK 0.144 parallel to sintered layers W/mK 0.127 EOS GmbH - Electro Optical Systems Robert-Stirling-Ring 1 D-82152 Krailling / München Telefon: +49 (0)89 / 893 36-0 AHO / 03.10 Telefax: +49 (0)89 / 893 36-285 PA2200_Product_information_03-10_en.doc 1 / 10 Internet: www.eos.info Product Information Short term influcence of temperature on mechanical properties An overview about the temperature dependence of mechanical properties of PA 12 can be re- trieved from the curves for dynamic shear modulus and loss factor as function of temperature according to ISO 537. PA 2200 dynamic mechanical analysis (torsion) Temp.: - 100 bis 188°C 1E+10 G' 1E+03 G" tan_delta 1E+02 1E+09 , 1E+01 1E+08 tan_delta 1E+00 1E+07 loss modulus G´´ [Pa] 1E-01 storage modulus G´ [Pa] modulus storage 1E+06 1E-02 1E+05 1E-03 -100 -50 0 50 100 150 200 Temperature [°C] In general parts made of PA 12 show high mechanical strength and elasticity under steady stress in a temperature range from - 40°C till + 80°C.
    [Show full text]
  • Properties of Cryogenic Insulants J
    Cryogenics 38 (1998) 1063–1081 1998 Elsevier Science Ltd. All rights reserved Printed in Great Britain PII: S0011-2275(98)00094-0 0011-2275/98/$ - see front matter Properties of cryogenic insulants J. Gerhold Technische Universitat Graz, Institut fur Electrische Maschinen und Antriebestechnik, Kopernikusgasse 24, A-8010 Graz, Austria Received 27 April 1998; revised 18 June 1998 High vacuum, cold gases and liquids, and solids are the principal insulating materials for superconducting apparatus. All these insulants have been claimed to show fairly good intrinsic dielectric performance under laboratory conditions where small scale experiments in the short term range are typical. However, the insulants must be inte- grated into large scaled insulating systems which must withstand any particular stress- ing voltage seen by the actual apparatus over the full life period. Estimation of the amount of degradation needs a reliable extrapolation from small scale experimental data. The latter are reviewed in the light of new experimental data, and guidelines for extrapolation are discussed. No degradation may be seen in resistivity and permit- tivity. Dielectric losses in liquids, however, show some degradation, and breakdown as a statistical event must be scrutinized very critically. Although information for break- down strength degradation in large systems is still fragmentary, some thumb rules can be recommended for design. 1998 Elsevier Science Ltd. All rights reserved Keywords: dielectric properties; vacuum; fluids; solids; power applications; supercon- ductors The dielectric insulation design of any superconducting Of special interest for normal operation are the resis- power apparatus must be based on the available insulators. tivity, the permittivity, and the dielectric losses.
    [Show full text]
  • Acid Dissociation Constant - Wikipedia, the Free Encyclopedia Page 1
    Acid dissociation constant - Wikipedia, the free encyclopedia Page 1 Help us provide free content to the world by donating today ! Acid dissociation constant From Wikipedia, the free encyclopedia An acid dissociation constant (aka acidity constant, acid-ionization constant) is an equilibrium constant for the dissociation of an acid. It is denoted by Ka. For an equilibrium between a generic acid, HA, and − its conjugate base, A , The weak acid acetic acid donates a proton to water in an equilibrium reaction to give the acetate ion and − + HA A + H the hydronium ion. Key: Hydrogen is white, oxygen is red, carbon is gray. Lines are chemical bonds. K is defined, subject to certain conditions, as a where [HA], [A−] and [H+] are equilibrium concentrations of the reactants. The term acid dissociation constant is also used for pKa, which is equal to −log 10 Ka. The term pKb is used in relation to bases, though pKb has faded from modern use due to the easy relationship available between the strength of an acid and the strength of its conjugate base. Though discussions of this topic typically assume water as the solvent, particularly at introductory levels, the Brønsted–Lowry acid-base theory is versatile enough that acidic behavior can now be characterized even in non-aqueous solutions. The value of pK indicates the strength of an acid: the larger the value the weaker the acid. In aqueous a solution, simple acids are partially dissociated to an appreciable extent in in the pH range pK ± 2. The a actual extent of the dissociation can be calculated if the acid concentration and pH are known.
    [Show full text]
  • Determination of the Relative Permittivity, E′, of Methylbenzene
    1056 J. Chem. Eng. Data 2008, 53, 1056–1065 Determination of the Relative Permittivity, E′, of Methylbenzene at Temperatures between (290 and 406) K and Pressures below 20 MPa with a Radio Frequency Re-Entrant Cavity and Evaluation of a MEMS Capacitor for the Measurement of E′ Mohamed E. Kandil and Kenneth N. Marsh Department of Chemical and Process Engineering, University of Canterbury, Christchurch, New Zealand Anthony R. H. Goodwin* Schlumberger Technology Corporation, 125 Industrial Boulevard, Sugar Land, Texas 77478 The relative electric permittivity of liquid methylbenzene has been determined with an uncertainty of 0.01 % from measurements of the resonance frequency of the lowest order inductive-capacitance mode of a re-entrant cavity (J. Chem. Thermodyn. 2005, 37, 684–691) at temperatures between (290 and 406) K and pressures below 20 MPa and at T ) 297 K with a MicroElectricalMechanical System (MEMS) interdigitated comb capacitor. For the re-entrant cavity, the working equations were a combination of the expressions reported by Hamelin et al. (ReV. Sci. Instrum. 1998, 69, 255-260) and a function to account for dilation of the resonator vessel walls with pressure that was determined by calibration with methane (J. Chem. Eng. Data 2007, 52, 1660–1671). The results were represented by an empirical equation reported by Owen and Brinkley (Liq. Phys. ReV. 1943, 64, 32–36) analogous to the Tait equation (Br. J. Appl. Phys. 1967, 18, 965–977) with a standard (k ) 1) uncertainty of 0.33 %. The values reported by Mospik (J. Chem. Phys. 1969, 50, 2559–2569) differed from the interpolating equation by <( 0.2 % at temperatures that overlap ours; extrapolating the smoothing expression to T ) 223 K, a temperature of 40 K below the lowest used for the measurements, provided values within ( 0.6 % of the data reported by Mospik.
    [Show full text]
  • Electrical Properties of Polyethylene/Polypropylene Compounds for High-Voltage Insulation
    energies Article Electrical Properties of Polyethylene/Polypropylene Compounds for High-Voltage Insulation Sameh Ziad Ahmed Dabbak 1, Hazlee Azil Illias 1,* ID , Bee Chin Ang 2, Nurul Ain Abdul Latiff 1 and Mohamad Zul Hilmey Makmud 1,3,* ID 1 Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia; [email protected] (S.Z.A.D.); [email protected] (N.A.A.L.) 2 Department of Chemical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia; [email protected] 3 Complex of Science and Technology, Faculty of Science and Natural Resources, University Malaysia Sabah, Kota Kinabalu 88400, Malaysia * Correspondence: [email protected] (H.A.I.); [email protected] (M.Z.H.M.); Tel.: +60-3-7967-4483 (H.A.I.) Received: 12 April 2018; Accepted: 30 May 2018; Published: 4 June 2018 Abstract: In high-voltage insulation systems, the most commonly used material is polymeric material because of its high dielectric strength, high resistivity, and low dielectric loss in addition to good chemical and mechanical properties. In this work, various polymer compounds were prepared, consisting of low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), HDPE/PP, and LDPE/PP polymer blends. The relative permittivity and breakdown strength of each sample types were evaluated. In order to determine the physical properties of the prepared samples, the samples were also characterized using differential scanning calorimetry (DSC). The results showed that the dielectric constant of PP increased with the increase of HDPE and LDPE content. The breakdown measurement data for all samples were analyzed using the cumulative probability plot of Weibull distribution.
    [Show full text]
  • Elektrochemia Simr 02 En
    Electrochemistry course Electrolyte - reminder ACME Faculty, EHVE course Liquid or solid that conducts electricity B.Sc. Studies, II year, IV semester by means of its ions. Ions can move when they have freedom Leszek Niedzicki, PhD, DSc, Eng. of movement. That freedom can be provided by molten salt (ionic liquid) , specific structure of solid enabling ionic mobility or (most commonly) solvation of ions in the solution by solvent Fundamentals of ionics molecules (and as a result - shielding them from counter-ions and causing dissociation). 2 Solvation once more Dynamic equilibrium Disturbance of solvent structure by an ion: • It is a phenomenon observed when on a large scale (e.g. billions of billions of molecules) a statistical equilibrium A – I solvation layer (directly coordinated by a cation) is observed, i.e. mean value of a given parameter is B – II and further solvation layers (attracted steady, but individual molecules often change their electrostatically by a cation and can interact with other solvent state. molecules – e.g. through the hydrogen bonds) • In practice dynamic equilibrium is defined C – solvent structure disturbed by the cation as an equilibrium of two opposite processes, which presence in the vicinity occur at the same rate (in a given conditions). In case D – original solvent structure of solvation solvent molecules are all the time C+ joining and leaving solvation layer (e.g. are knocked A B out of it). However, mean solvent molecules C in solvation layer of a given ion stays the same. D 3 4 Dynamic equilibrium Solvent • In dissociation or solvation case dynamic • Solvent in the electrolyte formation process is equilibrium forms because solvent molecules required to solvate ions (shields them against and ions are bumping on each other association or crystal formation) and dissociate compound into ions (strength of interaction with part (and at the vessel walls) all the time (due to chaotic of the compound tears it from the other part moves, vibrations, etc.
    [Show full text]
  • Anhydrous Formic Acid and Acetic Anhydride As Solvent Or Additive in Non- Aqueous Titrations
    ORIGINAL ARTICLES Department of Inorganic and Analytical Chemistry1,Eo¨tvo¨s University, Budapest; Department of Inorganic and Analytical Chemistry2, Debrecen University, Debrecen, Hungary Anhydrous formic acid and acetic anhydride as solvent or additive in non- aqueous titrations A´ . Buva´ri-Barcza 1,I.To´th2, L. Barcza1 Received November 21, 2003, accepted October 26, 2004 Dr. A´ gnes Buva´ri-Barcza, Department of Inorganic and Analytical Chemistry, Eo¨tvo¨s University H-1518 Budapest 112, P.O. Box 32, Hungary [email protected] Pharmazie 60: 650–655 (2005) The use and importance of formic acid and acetic anhydride (Ac2O) is increasing in nonaqueous acid- base titrations, but their interaction with the solutes is poorly understood. This paper attempts to clarify the effect of the solvents; NMR and spectrophotometric investigations were done to reveal the interac- tions between some bases and the mentioned solvents. Anhydrous formic acid is a typical protogenic solvent but both the relative permittivity and acidity are higher than those of acetic acid (mostly used in assays of bases). These differences originate from the different chemical structures: liquid acetic acid contains basically cyclic dimers while formic acid forms linear associates. Ac2O is obviously not an acidic but an aprotic (very slightly protophilic) solvent, which supposedly dissociates slightly into þ À acetyl (CH3CO ) and acetate (AcO ) ions. In fact, some bases react with Ac2O forming an associate: the Acþ group is bound to the dÀ charged atom of the reactant while AcOÀ is associated with the dþ group at appropriate distance. 1. Introduction fects of cis-trans isomerisation (more exactly the forma- tion of cis isomer) of DMAAB could be eliminated.
    [Show full text]
  • Method for Estimating the Dielectric Constant of Natural Gas Mixtures1
    International Journal of Thermophysics, Vol. 26, No. 1, January 2005 (© 2005) DOI: 10.1007/s10765-005-2351-5 Method for Estimating the Dielectric Constant of Natural Gas Mixtures1 A. H. Harvey2,3 and E. W. Lemmon2 A method has been developed for calculating the static dielectric constant (relative permittivity) of fluid mixtures, with an emphasis on natural gas. The dielectric constant is calculated as a function of temperature, density, and composition; the density is calculated with a fundamental mixture equation of state. Theory-based correlations were developed for the dielectric constant of all significant components of natural gas, including not only light hydro- carbons but also gases such as nitrogen and carbon dioxide. In many cases, these correlations took advantage of new, highly accurate data measured in cross capacitors. For mixtures, the pure-component values are combined as proposed by Harvey and Prausnitz; this produces better results than the tra- ditional mixing rule. KEY WORDS: dielectric constant; energy; mixtures; natural gas; polariza- tion; relative permittivity. 1. INTRODUCTION Natural gas is an increasingly important energy source. There is inter- est in methods, based on relatively simple measurements, for estimating important properties such as the heating value. It has been proposed [1,2] that measurements of the static dielectric constant could be a part of such a method. In order to evaluate and optimize such methods, a procedure is needed for accurate calculations of the dielectric constant of natural gas as 1Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A. 2Physical and Chemical Properties Division, National Institute of Standards and Technol- ogy, 325 Broadway, Boulder, Colorado 80305-3328, U.S.A.
    [Show full text]