Skip Navigation Links Home : MemberDetails
             
Name : Rami Abdel-Majid Abdel-Rahem

Academic Rank: Associate Professor

Administrative Position : Head of Department

Office 7115       Ext No 6500

Email : rabdelrahem@uop.edu.jo

Specialization: Chemistry

Graduate Of: University of Bayreuth

Download CV Download CV

Qualification

    Qualification

    University

    Country

    Year

    Bachelor
    Jordan University of Science and Technology
    Jordan
    1996
    Master's
    Jordan University of Science and Technology
    Jordan
    2000
    Ph.D
    University of Bayreuth
    Germany
    2003



  • Journal Paper





      Jingchen Hao, Jingzh, " Zn+2-Induced Vesicle Formation " , "J. Phys. Chem. B",Vol.108,No.4, American Chemical Society, USA, 06/01/2004 Abstract:
      Zn2+-induced vesicle formation has been studied for the first time in aqueous mixtures of tetradecyldimethylamine oxide (C14DMAO) and zinc 2,2-dihydroperfluorooctanoate [Zn(C6F13CH2COO)2]. The charged vesicle phase without any cosurfactants was prepared in the aqueous mixtures. The charged vesicle phase has interesting rheological properties. This ionically charged vesicle phase is not shielded by excess salts because of saltfree aqueous solutions. Such a vesicle phase is important for many applications where cosurfactant is not used. A cationic/anionic surfactant C14DMAOH+ -OOCCH2C6F13 system could be produced from C14DMAO/ Zn(C6F13CH2COO)2 mixtures because the zwiterionic surfactant C14DMAO can be charged by the H+ released from H2S to a cationic surfactant and Zn2+ is precipitated. After ZnS particles are removed from the cationic/ anionic surfactant solutions, the finally mixed sample does not contain excess salts as do other studied cationic/ anionic surfactant systems. The sample is a birefringent LR-phase and consists of unilamellar and multilamellar vesicles. The novel vesicle reproduction route should provide a new method to prepare nanoscale particles.




      R. A. El-Ghazawy, R., " Surface activity - thermodynamic properties and light scattering studies for some novel aliphatic polyester surfactants " , "Polymers for Advanced Technologies ",Vol.15,No.5, John Wiley & Sons, Ltd, USA, 04/29/2004 Abstract:
      The preparation of 12 new polyester surfactants based on aliphatic amines and different ethylene oxide content is described. These surfactants were characterized by determining their molecular weights and polydispersity by gel permeation chromatography (GPC) and nitrogen content. Drop volume tensiometry (DVT) was used to measure the surface tension at 25, 35, 45 and 55°C. The surface tension isotherms were used to determine critical micelle concentration (CMC), maximum Gibb's adsorption (Γmax), minimum area per molecule (Amin), the effectiveness of surface tension reduction (πcmc) and the efficiency (pC20). The thermodynamic parameters of micellization (ΔGmic, ΔHmic, ΔSmic) and of adsorption (ΔGad, ΔHad, ΔSad) were calculated and the data showed that these surfactants favor micellization to adsorption. The static scattered light intensity measurements provide the calculation of the molecular weight of micelle and the aggregation number (N°), while the dynamic light scattering provide the hydrodynamic radius of micelle (RH) and the diffusion coefficient at different surfactant concentrations. The hydrodynamic radius of micelle (RH) at different surfactant concentrations could be used also to determine the CMC giving results that are comparable to those obtained by surface tension measurements. All the data are discussed regarding the chemical structure of the polymeric surfactants.




      A.M. Al-Sabagh, M.E., " Surface activity and light scattering investigation for some novel aromatic polyester amine surfactants " , "Colloids and Surfaces A: Physicochemical and Engineering Aspects",Vol.251,No.1-3, Elsevier, Amsterdam, 12/20/2004 Abstract:
      The preparation of nine novel nonionic polymeric surfactants based on ethoxylated aniline, 2-amino benzene thiol and benzene sulphonamide was described. The number of ethylene oxide units was 2, 10 and 20. The prepared surfactants were characterized by determining their molecular weights and polydispersity by the GPC and also by nitrogen content. Surface tension as a function of concentration of the surfactants in the aqueous phase was measured at 25, 35, 45 and 55 °C using the drop volume tensiometer. From these measurements, the critical micelle concentration (CMC), the maximum surface excess concentration (Γmax), minimum area per molecule (Amin), the effectiveness of surface reduction and the efficiency (pc20) were calculated. The thermodynamic parameters of micellization (ΔGmic, ΔHmic, ΔSmic) and of adsorption (ΔGad, ΔHad, ΔSad) for those nonionic polyester surfactants were also calculated. The static light scattering was used to determine the aggregation number (N°), while the dynamic light scattering provides the hydrodynamic radius of the micelle (RH) and the diffusion coefficient at different surfactant concentrations. The values of RH at different concentrations were used to determine the critical micelle concentration (CMC) giving results that are comparable to those obtained by the surface tension measurements.




      Rami Abdel-Rahem Abstract:
      This paper investigates the effects of counterion microenvironments on the phase properties of ionic surfactants. The results of different isomers of hydroxy naphthoic acids (x, y HNC) and the cationic surfactant hexadecyltrimethylammonium hydroxide (HTAOH) are included. Mixing 3,2 HNC, 2,1 HNC or 6,2 HNC with micellar solutions of HTAOH transforms the micellar microstructure into different morphologies depending on the counterion microenvironments. The vesicles at equal concentration ratio of 3,2 HNC/HTAOH and 2,1 HNC/HTAOH have been characterized by freeze fracture electron microscopy (FF-TEM) and small angle neutron scattering (SANS). 6,2 HNC/HTAOH system does not form a liquid crystalline phase (La-phase) at and above the equal concentration ratio. With these systems the effects that the hydrophobic counterion microenvironments have on the aggregate microstructure, rheological behavior, Krafft temperature and other physiochemical properties are discussed.




      R. Abdel-Rahem, M. G, " A Novel Viscoelastic System from a Cationic Surfactant and a Hydrophobic Counterion " , "Journal of colloid and interfacial science",Vol.288,No.2, Elsevier, USA, 04/27/2005 Abstract:
      The phase behavior of 2-hydroxy-1-naphthoic acid (2,1-HNC) mixed with cetyltrimethylammonium hydroxide (CTAOH) is reported. This novel system is compared with the published one of 3-hydroxy-2-naphthoic acid (3,2-HNC) mixed with CTAOH. We investigated the phase behavior and properties of the phases in aqueous solutions of 100 mM CTAOH with 2,1-HNC. In both systems a multilamellar vesicle phase is formed when the naphthoate/surfactant ratio (r) reaches unity. When an increasing amount of 2,1-HNC is mixed with a micellar solution of 100 mM CTAOH, an isotropic low-viscous micellar solution, a viscoelastic gel (consisting of rodlike micelles), a turbid region (two-phase region), and a viscoelastic liquid crystalline gel (consisting of multilamellar vesicles, MLV) were formed. The vesicular phase is highly viscoelastic and has a yield stress value. The transition from the micellar to the vesicle phase occurs for CTAOH/2,1-HNC over a two-phase region, where micelles and vesicles coexist. Also it was noticed that 2,1-HNC is dissolved in 100 mM CTAOH until the naphthoate/surfactant ratio reaches ∼ 1.5, and the liquid crystalline phases were found to change their color systematically when they were viewed between two crossed polarizers. The vesicles have been characterized by differential interference contrast microscopy, freeze-fracture electron microscopy, and cryo-electron microscopy (cryo-TEM). The vesicles were polydisperse and their diameter ranged from 100 to 1000 nm. The interlamellar spacing between the bilayers was determined with small angle neutron scattering and agrees with the results from different microscopical methods. The complex viscosity rises by six orders of magnitude when rodlike micelles are formed. The complex viscosity decreases again in the turbid region, and then rises approximately six orders of magnitude above the water viscosity. This second rising is due to the formation of the liquid crystalline MLV phase.




      R. Abdel-Rahem and H, " The Distinction of Viscoelastic Phases from Entangled Worm Like Micelles and of Densely Packed Multilamellar Vesicles on the Basis of Rheological Measurements " , "Rheologica Acta",Vol.45,No.6, Springer , Germany , 07/26/2006 Abstract:
      It is shown in this work how two viscoelastic surfactant systems that are both shear thinning but differ in their morphology can be distinguished on the basis of rheological measurements. The measurements were carried out on the novel surfactant system cetyltrimethylammonium 2-hydroxy-1-naphthoate. The phases in this system are produced by mixing cetyltrimethylammonium hydroxide and 2-hydroxy-1-naphthoic acid.With increasing counterion surfactant ratio X, the system has two viscoelastic regions that are separated by a twophase region. It is shown by cryotransmission electron microscopy and by small angle neutron scattering that the first viscoelastic region which exists between X=0.5 and X=0.75 contains wormlike micelles, while the second viscoelastic region that exists between X=0.9 and X=1.4 contains multilamellar vesicles. Both phases look alike, are highly viscoelastic, have similar storage modulus values, and are shear thinning. The phases and the properties of the phases for the studied system are very similar as the phases for the system CTA-3-hydroxy- 2-naphthoate that has been studied before (see Hassan et al. Langmuir, 12:4350–4357, 1996; Horbaschek et al. J Colloid Interface Sci, 206:439–456, 1998). The two viscoelastic phases show the same shear-thinning behavior, but differ in other rheological results. The phases can most easily be distinguished with the help of normal stress measurements. The wormlike viscoelastic solutions show large normal stresses that give rise to a large Weissenberg effect while the vesicle phases show no Weissenberg effect.




      R. Abdel-Rahem, and , " Novel Viscoelastic Systems from a Cationic Surfactant and a Hydrophobic Counterion: influence of surfactant chain length " , "Journal of Colloid and Interface Science",Vol.312,No.1, Elsevier, USA, 08/01/2007 Abstract:
      In continuation of our previous investigations on the aqueous phase behavior of cetyltrimethylammonium 2-hydroxy-1-carboxy-naphthoate (CTA-2,1-HCN) (see J. Colloid Interface Sci. 288 (2005) 570), we have studied the phase behavior and the properties of the phases of the two shorter homologues, C14TA-2,1-HCN and C12TA-2,1-HCN. The phases were prepared from the alkyltrimethylammonium hydroxides RTAOH and the naphtholcarboxylic acid. By preparing the systems in this way the surfactant solutions contain no excess salt. With increasing counter-ion–surfactant ratio r we observed the same sequence of phases as for the previously studied C16-system, namely a L1-phase and a Lα-phase with multilamellar vesicles (MLV). The single phases are separated by a two-phase L1/Lα region. The phases were characterized with FF-TEM, rheological and SANS measurements. For both systems the viscosity of the L1-phases passes with increasing counter-ion/surfactant ratio over a maximum. The height of the maximum decreases strongly with decreasing chain length while the complex viscosity of the MLV-phase depends little on the chain length. For 100 mM solution both MLV phases behave like a weak gel and have a yield stress value. It is thus shown that it is possible to prepare viscoelastic surfactant solutions with a yield stress value from single chain surfactants with a dodecyl chain.




      R. Abdel Rahem
      Abstract:
      We have investigated the phase behavior and characterized the microstructure of the phases that result from mixing of alkyltrimethylammonium hydroxides CxTAOH (x = 10.8) with 2-hydroxy 1-carboxy-naphthoate. We compare the results of this work with the published one of alkyltrimethylammonium 2-hydroxy-1-carboxy-naphthoate (CxTA 2,1 HCN, x = 16.14 or 12) [2]. With increasing counter-ion surfactant ratio r we observed transition from the isotropic L1-phase to multilamellar vesicles (MLV) Lα-phase. The single phases are separated by a two phase L1/Lα region. The phases were characterized with FF-TEM, rheological and SANS measurements. For 100mM solution of either C8TAOH/2,1 HNC or C10TAOH/2,1 HNC, both MLV phases behave like a weak gel and have a yield stress value. It is thus shown that it is possible to prepare viscoelastic surfactant solutions with a small yield stress value from single chain surfactants with decyl or octylchain.




      R. Abdel-Rahem and J, " Dissolution Rate of Sodium Fatty Alcohol Sulfate FAS – Surfactants " , "Tenside Surfactants Detergents ",Vol.44,No.5, Hanser, Germany, 10/01/2007 Abstract:
      We represent an applicable problem that arises when long chain surfactant fatty alcohol sulfate FAS is used in washing process. Octadecyl fatty alcohol sulfate C18-FAS is known for its strong washing performance, however it has the disadvantages of high Krafft point and its long dissolution rate. We demonstrate the factors that affect dissolution rates of FAS-surfactants, and how one can vary these factors in order to achieve particular dissolution rate. In this study, we have used a reproducible method for determining the rate of dissolution of anionic surfactants tablet and the effect of, temperature, hardness of FAS-tablets, stirring rate, FAS chain length, mixing with other surfactants and additives on the rate of dissolution of FAS have been studied.




      R. Abdel-Rahem and A, " Surface Activity of Newly Nonionic Surfactants at Air/Water Interface and their Interaction with Clay and Teflon " , "Tenside Surfactants Detergents ",Vol.45,No.3, Hanser, Germany , 06/01/2008 Abstract:
      The surface activity of newly nonionic hydroxyl mixed ether surfactants HMEn at air/water and solid/water interfaces was studied as a function of ethoxylation degree (n-value). The characteristics of this series of nonionic surfactant, including surface tension, critical micelle concentration cmc, adsorption onto hydrophilic saponite clay and hydrophobic Teflon are reported. The surface tension results indicate that cmc, surface tension after γcmc, and the minimum surface area per adsorbed HME-surfactant molecule Amin are all increased with n-value. Results of static light scattering are in agreements with those obtained using surface tension method. For HME-surfactants, strong adsorption measured by surface tension onto the hydrophilic synthetic clay mineral saponite. This result was also observed by atomic force microscopy AFM for HME9.7 onto hydrophilic mica surface. On the other hand, the adsorption of HME-surfactant onto hydrophobic polytetraflouroethylene PTFE (Teflon) is less than that measured onto saponite. However, the adsorption at both surfaces has the same dependency on n-value.




      R. Abdel-Rahem, " The influence of hydrophobic counterions on micellar growth of ionic surfactants " , "Advances in Colloid and Interface Science",Vol.141,No.1-2, Elsevier, USA, 09/01/2008 Abstract:
      This review covers the effects of hydrophobic counterions on the phase behavior of ionic surfactants and the properties of the phases. Mixing hydrophobic counterions with ionic surfactant micellar solutions may initiate the micellar growth and transform the micellar microstructure into different morphologies. This behavior may also be achieved by mixing ionic surfactants with hydrophilic counterions, although higher counterionic concentrations are then required. First, the role of hydrophilic and hydrophobic counterions in regards to micelle growth is discussed. Second, the effect of the hydrophobic counterion on the self-assembly of cationic and anionic surfactants and their viscoelastic behavior are presented. Third, the relationships between geometry, hydrophobicity and their consequences on micellar growth for different hydrophobic counterions are reviewed. Forth, the influence of hydrophobic counterion substituents (substitution pattern) on the phase behavior is discussed. Some results we previously obtained for different isomers of hydroxy naphthaoic acids and the cationic surfactant cetyltrimethylammonium hydroxide are included. With these systems the effect that the hydrophobic counterion microenvironment has on the phase behavior, rheological behavior and the micellar microstructure is discussed. The results from other research groups are also discussed.




      Ayman S. Ayesh and R, " Optical and Electrical Properties of Polycarbonate/MnCl2 Composite Films " , "Journal of Plastic Film and Sheeting",Vol.24,No.2, SAGE, USA, 08/21/2008 Abstract:
      The dependence of the absorption coefficient () on photon energy (h) is determined in the spectral range from 200 to 800nm at room temperature for polycarbonate (PC)/MnCl2 composite films. The variation of the absorption coefficient (), optical gap (Eopt), dielectric permittivity ("0), dielectric loss ("00), loss tangent (tan ), impedance (Z), AC conductivity (ac), DC conductivity (dc), and relaxation time () with salt concentration and frequency are reported. The observed optical energy gap (Eopt) and energy gap tail (E) is calculated from the measured absorption spectra. It is found that optical energy gap decreases with increasing MnCl2 concentration and the absorption coefficient reduces sharply (with reduction ratio of 79%) in the UV region at concentration of 20 wt% compared with the PC host. All measured electrical parameters of the composite sheets show frequency and content dependence. Both AC conductivity and DC conductivity increase with MnCl2 concentration while impedance decreases. Correlation between observed energy gap and AC conductivity is presented.




      R. Abdel-Rahem and , " Physiochemical Properties of Hydroxy Mixed Ether HMEn Surfactants and their Interaction with Sodium Dodecyl Sulfate SDS " , "Tenside Surfactants Detergents ",Vol.46,No.2, Hanser , Germany , 04/01/2009 Abstract:
      This paper is focused on the phase behavior, interaction with anionic surfactant sodium dodecyl sulfate SDS, adsorption and wetting investigations of new hydroxy mixed ether nonionic surfactants HMEn. The phase diagrams of (0.1–100) %wt of HMEn (n-value is the ethoxylation number EO) at the temperature range 20–100°C have shown that the increasing of n-value raises the cloud boundary toward higher temperature. Remarkable result was obtained from the interaction between SDS and HMEB, at which the mixed system exhibits a unique homogeneity and a liquid crystal phase formation. Macroscopically, the liquid crystal region was found when the SDS concentration range between 8 and 24 mM mixed with 10% wt HMEB. The interaction between HMEn and mica was also investigated using atomic force microscopy AFM and a pronounced adsorption of HMEn on mica was observed. Moreover, contact angle results reveal that glass substrate shows strong wettability of HMEn surfactant solutions compared with polyethylene PE and polymethylmethaacrylate PMMA substrates. This wettability however also decreases with EO number.




      Rami Abdel-Rahem, " Synergism in Mixed Anionic–Amphoteric Surfactant Solutions: Influence of Anionic Surfactant Chain Length " , "Tenside Surfactants Detergents",Vol.46,No.5, Hanser , Germany , 10/01/2009 Abstract:
      The influence of chain length on the composition of mixed micelles in binary mixtures of N,N-dimethyldodecylamine oxide (DDAO) and sodium decyl-, sodium dodecyl- and sodium tetradecylsulfate (abbreviated as SDeS, SDS and STS, respectively) has been determined at 30°C. From the surface tension measurements, the critical micelle concentration (cmc) data were measured as a function of mixing composition. Cmc-values were then analyzed according to regular solution model. The composition of mixed micelles, the interaction parameter (β) and the activity coefficients were evaluated from the regular solution model for the all anionic-amphoteric mixed systems. The interaction parameter values indicated a synergistic interaction between DDAO and the three anionic surfactants at all mole fractions to be due to an overall attractive interaction in the mixed micelles. The strength of the interaction between the amphoteric surfactant and the sodium alkyl sulfate in three mixed systems obeys the following order: SDeS/DDAO > SDS/DDAO > STS/DDAO suggesting that the decrease in the length of anionic surfactant alkyl chain results in a stronger interaction with DDAO. On the other hand, the viscosity data reveals a viscosity increasing trend of STS/DDAO > SDS/DDAO > SDeS/DDAO.




      Ayman S. Ayesh and, " Effect of Ba0.9725 (Ti(0.9)Sn0.1)O3 Ceramic Doping on the Optical, Thermal and Dielectric Properties of Polycarbonate Host " , "Bulletin of Materials Science ",Vol.33,No.3, Springer , India , 10/01/2010 Abstract:
      Ba(Ti(0⋅9)Sn0⋅1)O3 (BTS) ceramic was prepared by a conventional ceramic processing. BTS– polycarbonate (PC) composites were prepared at different BTS concentrations by weight in order to study their optical and dielectric properties. The absorption coefficient (α) was determined in the wavelength range from 250–600 nm at room temperature for all BTS–PC composites. The optical gap (E opt) was also determined for BTS–PC composites. The variation of the absorption coefficient (α) and optical gap (E opt) with BTS content are reported. It was found that BTS ceramic highly enhances the UV absorption of PC host at 300 nm. The optical gap decreases up to the value of 3⋅93 eV as BTS content increases up to 35 wt% and this was attributed to the formation of localized states in the forbidden gap. The relative dielectric permittivity, dielectric loss and loss tangent were measured at temperature range from room temperature up to 150°C and at frequency values 1 kHz, 10 kHz and 50 kHz. Addition of BTS to PC host, however, will increase relative dielectric permittivity, dielectric loss and loss tangent. Besides, increasing of temperature will also increase relative dielectric permittivity, dielectric loss and loss tangent especially above the glass transition temperature of PC host and this behaviour was attributed to the segmental motion of polymer chains. On the other hand, this study shows that there is a good agreement between SEM, DSC and dielectric results and also between optical gap and a.c. conductivity results. Moreover, SEM and DSC results reveal that addition of BTS ceramic particles to PC host will reduce the physical bond between polymer chains or may be will increase the free volume in the polymer host and consequently will enhance the segmental motion of polymer chains and this behaviour is independent of ceramic phase.




      H. Hoffmann and R. A, " Influence of co-solvent on the rheological behavior of aqueous viscoelastic surfactant systems " , "Find out how to access preview-only content Colloid and Polymer Science ",Vol.288,No.6, Springer , Germany , 02/23/2010 Abstract:
      We have studied the influence of glycerol on the rheological behavior of viscoelastic surfactant solutions. The measurements were carried out on the system CTAB and NaSal. This system shows two viscosity maxima with increasing NaSal concentration. When water is replaced by glycerol, the viscosities and the structural relaxation times at the viscosity maxima decrease while they increase at the viscosity minimum. As a result of the opposite changes the two maxima are replaced by a single maxima when 40% water is replaced by glycerol. The change of the viscosities is a consequence of a change of the structural relaxation times while the storage moduli remain constant. The opposite changes are a result of different mechanisms for the relaxation times. At the maxima, the relaxation times are reptation controlled and depend on the intermicellar interaction energy. At the minimum, relaxation times are kinetically controlled and depend on the intramolecular interaction.




      R. Abdel-Rahem, " Effect of Glycerol on the Swelling of Multilamellar Vesicles Composed of Cetyltrimethylammonium Bromide and Sodium Hydroxy-naphthoate " , "Journal of Dispersion Science and Technology",Vol.32,No.6, Taylor & Francis, UK, 05/23/2011 Abstract:
      A biphasic solution containing an isotropic L1-phase and La-phase (multilamellar vesicles) was illustrated in order to investigate the consequences of glycerol addition on the swelling behavior of La-phase at different glycerol concentrations and temperature values. The multilamellar vesicles were prepared from mixing cationic surfactant cetyltrimethylammonium bromide (CTAB) and hydrophobic counterion sodium 3-hydroxynaphthalene 2-carboxylate (NaHNC) at the same molar ratio. Different techniques were used in order to investigate the swelling behavior of the La-phase by establishing the phase diagram, observing the solutions via polarizing microscopy, and measuring different rheological parameters. A comparison study between the effect of glycerol addition and temperature on the swelling behavior was performed. By adding glycerol to water at 40%, the two-phase L1/La region was swollen to a single La phase and the solution became transparent at 40C. On the other hand, the swelling of La-phase was observed in water solvent at higher temperature values. The vesicles were with higher flexibility at low glycerol content and became rigid when the glycerol content was increased. In addition, the complex viscosity, g followed the same increase-decrease in two conditions. In the first case, g was varied with glycerol content at constant temperature and in the second case g was varied with temperature at constant glycerol content. Such a result indicates that the rheological behavior is also influenced by the solvent properties. Furthermore, this study shows that with increasing glycerol content, the swelling in the La phase was attributed with a decrease in the attraction energy between the vesicles. Ultimately, it has shown that it is possible to convert the two-phase L1/La into a single La phase by controlling some physical parameters of the medium as the static dielectric constant and the refractive index. The results obtained are expected to be useful in many different applications of surfactant solutions.




      Rami Abdel-Rahem , A, " The Influence of Surfactant's Synergism on the Solubilization of Some Fluorescent Compounds " , "Tenside Surfactants Detergents",Vol.48,No.6, Hanser , Germany , 12/01/2012 Abstract:
      Aqueous solutions of anionic surfactant sodium dodecylsulfate (SDS) and cationic surfactant cetyltrimethyammonium bromide (CTAB) were prepared at room temperature in order to investigate the influences of surfactants mixing on the solubilization of 2-naphthol-6-sulfonate and toluene. The phase behavior of CTAB/SDS was firstly investigated to obtain the optimum ratio of CTAB/SDS that result in an isotropic solution before reaching the two phase region. From the conductivity and surface tension measurements, the critical micelle concentrations (CMC) of single and mixed surfactant solutions were obtained and the interaction parameter (β) were evaluated. Water solubility enhancement of (0 – 3 wt.%) toluene by micellar solutions of single surfactant SDS, CTAB and mixed solutions of SDS-CTAB surfactants were then investigated by establishing the phase behavior and measuring the absorption and the emission spectra of these solutions. The toluene was completely solubilized by the micellar solution of single surfactants, whereas turbidity was observed at toluene concentration of about 1.5 wt.% in the micellar solution of SDS-CTAB. The fluorescence behavior of 2-naphthol-6-sulfonate (2NO6S) and toluene in the single and mixed surfactant solutions was also compared. The solubilization of toluene in surfactant solutions was explained in terms of hydrophobic interaction occurring within the surfactant core and the palisade layers.




      Jibril Al-Hawarin, , " Dielectric and Thermal Properties of PEO Doped with Cadmium Chloride salt " , "Chinese Journal of Polymer Science",Vol.30,No.2, Springer , China, 11/30/2012 Abstract:
      The main aim of this research is to investigate the effect of salt concentration on the dielectric properties (AC (AC), permittivity ('), dielectric loss (''), and dielectric relaxation process) and melting behavior of polyethylene oxide (PEO)/CdCl2 complexes. The dielectric study was carried out over a frequency range 10335 kHz and a temperature range 2545C. The AC conductivity, permittivity and dielectric loss of the PEO/CdCl2 complexes increase with increasing salt concentration and temperature. Also, it was found that the addition of CdCl2 salt to PEO host reduced the melting temperature of PEO host. Dielectric results reveal that the relaxation process of these complexes is due to viscoelastic relaxation or non-Debye relaxation at room temperature. Additionally, it was found that relaxation behavior remained viscoelastic at different temperatures and salt concentrations.




      Rami A. Abdel-Rahe, " Micellar Parameters in Solutions with Cationic Surfactants and N,N-dimethyldodecylamine oxide: Influence of Cationic Surfactants Chain Length " , "Journal of Chemical and Engendering Data",Vol.57,No., American Chemical Society, USA, 01/27/2012 Abstract:
      The influence of chain length on the composition of mixed micelles in binary mixtures of N,N-dimethyldodecan-1-amine oxide (DDAO) and decyl-, dodecyl-, and tetradecyl-trimethyl-ammonium bromide surfactants (abbreviated as C10TAB, C12TAB, and C14TAB, respectively) has been determined at 298 K. From the surface tension measurements, the critical micelle concentration (cmc) data were measured as a function of mixing composition. The cmc values were then analyzed according to regular solution model. The composition of mixed micelles, the interaction parameter (β), and the activity coefficients were evaluated from the regular solution model for all cationic−amphoteric mixed systems. The interaction parameter values indicated somehow a small deviation from ideality for the three mixed surfactant systems, for all investigated mole fractions. The strength of the interaction between the amphoteric surfactant and the alkyl-trimethyl-ammonium bromide surfactants in three mixed systems obeys the following order: (C10TAB + DDAO) > (C12TAB + DDAO) > (C14TAB + DDAO) suggesting that the decrease in the length of cationic surfactant alkyl chain results in a stronger interaction with DDAO. Rheological measurements of these solutions in the presence of sodium salicylate, NaSal, for the three mixed systems were also measured. The viscosity data reveal a viscosity increasing trend of (C14TAB + DDAO) > (C12TAB + DDAO) > (C10TAB + DDAO).




      Rami A. Abdel-Rahem<, " 1,3-butanediol as a co-solvent for the surfactant solutions " , "Colloid Polym Sci",Vol.290,No.10, Springer , Germany , 07/01/2012 Abstract:
      A biphasic solution containing water and precipitated phosphocholine (PC) is presented in order to investigate the consequences of 1,3-butanediol addition on the phase behavior of PC at different 1,3-butanediol concentrations and temperature values. With increasing the concentration of 1,3-butanediol in the mixed solvent at room temperature, the biphasic solution converts into turbid phase, two phase, and finally to a clear phase that is birefringent when viewed between two crossed polarizers. The birefringent phase moves to lower 1,3-butanediol contents at higher temperature values. The birefringent phase was observed via polarizing microscopy, and its rheological parameters were measured with cone plate method. In high 1,3-butanediol contents, solutions with 2.5% of PC behave as a gel with high yield stress value. The micellization of cetyltrimethyammonium bromide (CTAB) in a series of 1,3-butanediol/water mixed solvent at room temperature was also investigated. From the conductivity measurements, the critical micelle concentration and the degree of counterion dissociation of CTAB were obtained as a function of 1,3-butanediol. Standard free energy of micellization, as a function of 1,3-butanediol contents, was also estimated and discussed. Gibbs energies of micellization were found to have a good correlation with dielectric constant and Gordon parameters.




      Rami Abdel-Rahem and, " Rheological Investigations on the Viscoelastic Properties of alkyimethylammonium 2-hydroxy-1-carboxy-naphthoate and 2-hydroxy-1-carboxy-naphthoate in aqueous Solutions " , "Journal of Dispersion Science and Technology",Vol.34,No.1, Taylor & Francis, UK, 12/26/2012 Abstract:
      The rheological behavior of alkyimethylammonium 2-hydroxy-1-carboxy-naphthoate, CxTA-2.1- HCN (x¼16, 14, 12, 10, and 8) is presented. With increasing 2.1 HNC/CxTAOH (x¼16, 14, 12) ratio, the viscoelasticity of the solutions changes due to a transition in the micellar shape from small micelles to rodlike micelles and finally to multilamellar vesicles (MLV). On the other hand, a transition from small micelles to multilamellar vesicles (MLV) was observed for solution with CxTA-2.1-HCN (x¼10 and 8). The MLV phases behave like a weak gel and have a yield stress value. Rheological measurements were performed for these viscoelastic systems in order to find out the dependency of the viscoelastic behavior on the surfactant chain length and hydrophobic counterion concentration. Some theoretical models as reptation mechanism was also applied in order to get some structural details and to illustrate the rheological behavior of these viscoelastic systems. Some models that correlate MLV-modulus on the surfactant morphology are also presented and discussed.




      Rami A. Abdel-Rahem, " The Adsorption of Newly Hydroxyl Mixed Ether Nonionic Polymeric Surfactants at Air/Water and Solid/Water Interfaces: Influence of Surfactant Molecular Structure " , "Journal of Surfactants and Detergents ",Vol.16,No.1, Springer & AOCS, USA, 01/01/2013 Abstract:
      This paper reports the adsorption of four nonionic Hydroxyl Mixed Ether (HME) polymeric surfactants at air/water and solid/water interfaces. The characteristics of these nonionic surfactants, including surface tension, critical micelle concentration (CMC) and adsorption onto saponite and Teflon are investigated. At the air/water interface, the surface activity of the HME-surfactants decreases with an increasing degree of ethoxylation. The surface tension results indicate that CMC, surface tension at CMC (cCMC), and the minimum surface area per adsorbed HME-surfactant molecule (Amin) all increased with the degree of ethoxylation for surfactants with similar hydrocarbon chain lengths. Additionally, a strong adsorption onto the saponite (synthetic clay) was measured and found dependent on both the degree of ethoxylation and the hydrocarbon chain length. This adsorption was also observed by atomic force microscopy (AFM). On the other hand, the adsorption of HME-surfactants on Teflon was independent of the hydrocarbon chain length.




      Rami A. Abdel-Rahem, " Influence of Glycerol and Temperature on the Phase Behavior and Micellization of CTAB and SDS in Aqueous Solutions " , "Journal of Dispersion Science and Technology",Vol.34,No.7, Taylor & Francis Group, UK, 07/03/2013 Abstract:
      In this work the micellization of sodium dodecylsulfate (SDS) and cetyltrimethyammonium bromide (CTAB) in water-glycerol mixed solvent have been investigated at 25, 35, and 45°C, respectively. The micellization of both surfactants in pure water at different temperatures has also been studied. The phase diagrams of the surfactants in water-glycerol mixed solvent were also established. From the conductivity measurements, the critical micelle concentration (CMC) and the degree of counterion dissociation (β) were obtained as a function of glycerol-water ratio and temperature. Standard free energy of micellization (ΔG°mic) as a function of glycerol contents and temperature was calculated and discussed. It has been found that the micellization of the two surfactant in solutions with glycerol at 25°C and in pure water at higher temperatures are not the same although they have equal dielectric constants values.




      Rami A. Abdel-Rahem,, " Rheology of Aqueous Solutions Containing SLES, CAPB,and Microemulsion: Influence of Cosurfactant and Salt " , "Journal of Dispersion Science and Technology",Vol.35,No.1, Taylor & Francis, UK, 12/20/2013 Abstract:
      Aqueous solutions containing sodium lauryl ether sulphate (SLES) and cocamidopropyl Betaine (CAPB) with a constant total surfactant concentration (10 wt%) but different volume mixing ratios were prepared. A remarkable increase in the solutions’ viscosity at a volume mixing ratio of 34 v/v% SLES to 66 v/v% CAPB was observed. By increasing the volume ratio of SLES (r-value) in the binary mixture, the viscosity of 10 wt% SLES, which is close to that of water, increases to a maximum, but then drops down drastically at high r values (>45 v/v%). The maximum viscosity (Vmax) is 2.8 Pas, whereas the minimum is 2 mPas. The rheological behavior at Vmax has the remarkable feature of a simple Maxwell fluid over a large frequency range with one relaxation time. By adding a microemulsion (Plantasil Micro), the value of Vmax decreases extremely, whereas adding cosurfactants like isodecyltrietheleneoxide (IT3) or salts, like calcium chloride, leads to a pronounced increase in the value of Vmax. At 0.76 wt% CaCl2, Vmax is 140 Pas and 150 Pas in the presence of 1 wt% IT3. By increasing the SLES volume mixing ratio in the solution the maximum viscosity is shifted to higher CaCl2 amounts. The increasing viscosity can be explained by a transformation of the micelle shape from spherical to rod-like. Whereas adding cosurfactants or salts leads to an increased entanglement between the rod-like micelles. Consequently, higher microemulsion amounts can be added before reaching the minimum viscosity.




      Rami A. Abdel-Rahem, " Influence of 1,3-Butanediol on the Viscoelasticity of Surfactant Solutions " , "Journal of Surfactants and Detergents",Vol.17,No.2, Springer, USA, 03/01/2014 Abstract:
      The rheological behavior of rodlike micelles in a 1,3-butanediol/water mixed solvent was investigated. The rodlike micelles were prepared by mixing sodium salicylate, with cetyltrimethylammonium bromide. When water was replaced by 1,3-butanediol, the viscosity maxima decreased drastically. The viscosity minimum, on the other hand, increased at low 1,3-butanediol contents and decreased again at higher amounts of 1,3-butanediol. As a result of the opposite changes the two maxima were replaced by a single maxima when the content of 1,3-butanediol was 15 %. The change in the viscosity was a consequence of a change in the structural relaxation times while the storage moduli remained constant. The stress relaxation was due to a reptation mechanism at maximum points while at the minimum of the viscosity the mechanism was due to a kinetic controlled mechanism.




      Ayman S. Ayesh, S. S. Ibrahim, Abdullah A. Al-Jaafari, Rami A. Abdel-Rahem, Nadeem S. Sheikh, and H. Mahfoz Kotb,, " Electrical and Mechanical Properties of β-Hydroxynaphthoic Acid-MWCNTs Polystyrene Nanocomposites " , " Journal of Thermoplastic Composite Materials",Vol.28,No.6, SAGE, USA, 05/15/2015 Abstract:
      The effect of -hydroxynaphthoic acid (-HNA) addition on electrical and mechanical properties of multiwalled carbon nanotubes (MWCNTs)–polystyrene (PS) composite at a fixed amount of MWCNTs (0.85 wt%) are delineated. Obtained electrical, mechanical, morphological, and Fourier transform infrared results showed that addition of -HNA up to 1 wt% to MWCNTs-PS composite enhanced the dispersion of MWCNTs in the neat PS, formation of MWCNTs-PS network, relative permittivity, dielectric loss, and the electrical conductivity increased by about three orders of magnitude for the prepared composite. Dielectric relaxation results showed that at the domain frequency range, the relaxation process below 1.0 wt% -HNA was mostly due to polymer molecular relaxation process, while at 1.0 wt% -HNA, the composite relaxation behavior was mostly due to charge conductivity relaxation. Mechanical results showed that addition of -HNA to composite system up to 1.0 wt% increased the elastic modulus, yieldstress, and tensile strength of the composites by about 12.2, 17.1, and 10.0%, respectively, which indicated that the addition of -HNA to composite system improved MWCNTs dispersion in PS matrix and enhanced the interfacial bond in the -HNAMWCNTs- PS network.




      Altwaiq, A., Rami Abdel-Rahem, AlShamaileh, E., Al-luaibi, S., Khouri,, " Sodium lignosulfonate as a friendly-environment corrosion inhibitor for zinc metal in acidic media " , "Eurasian Journal of Analytical Chemistry",Vol.10,No.1, iSER , Turkey , 01/01/2015 Abstract:
      The corrosion inhibition property of sodium lignosulfonate is investigated by three different independent monitoring techniques. These methods include weight loss measurements, electrical conductance and potentiodynamic polarization. Solutions with and without sodium lignosulfonate in 0.01 M HCl and 0.1 M HCl were prepared at 20 oC to study the influence of sodium lignosulfonate on the corrosion of zinc sheets. The results obtained from the three different methods indicate the protection role of sodium lignosulfonate, which is considered as a friendly-environment corrosion inhibitor, in the corrosion of zinc sheets. The reduction of the zinc corrosion in solutions with HCl and different concentrations of sodium lignosulfonate using potentiodynamic polarization followed the order: 30 mM > 10 mM > 5 mM >1 mM. The obtained results from weight loss, potentiodynamic polarization and electrical conductance experiments were in good agreement with each other.




      Abstract:
      Abstract The influence of surfactant synergism on Zn corrosion inhibition in 0.1-M HCl aqueous solutions has been determined at room temperature. Solutions of single and mixed surfactants consisting of sodium dodecylsulfate (SDS) and N,N dimethyldodecan-1-amine oxide (DDAO) in water and in 0.1-M HCl were also prepared at room temperature. Critical micelle concentration (CMC) data were obtained through surface tension measurements as a function of mixing composition. A regular solution model was considered to analyze CMC values. The interaction parameter (b), the composition of mixed micelles (x) and the activity coefficients (f) were estimated by a regular solution model for all amphoteric–anionic mixed systems. b Values showed synergism for the binary mixtures of these solutions in the absence and presence of 0.1-M HCl at all investigated compositions. Zinc corrosion in single and binary SDS/DDAO mixed solutions at 5-mM total surfactant concentrations in the presence of 0.1-M HCl was also investigated at static and dynamic conditions. The weight loss data revealed corrosion inhibition activity obeyed the following order: binary (0.75 DDAO ? 0.25 SDS)[binary (0.50 DDAO : 0.50 SDS)[single DDAO[single SDS, suggesting an enhancement in the corrosion inhibition activity of DDAO in the presence of a proper amount of SDS. Conductivity time measurements show a similar trend as that obtained by a weight loss method at (0.50 DDAO : 0.50 SDS). The results were illustrated on the basis of synergistic interaction between the mixed surfactants.
  • Event Calendar
    <January 2017>
    SunMonTueWedThuFriSat
    1234567
    891011121314
    15161718192021
    22232425262728
    293031