- Abstract: High-performance materials for flameproofing, phosphates (polyphosphate and ammonium phosphate) were synthesized on viscose rayon felt. This surface reaction has the advantage of a nonblooming effect and an application in thermosetting plastics. Metal complexes have the effect of reducing the amount of smoke. Therefore, in the second step, transition-metal complexes were synthesized on the viscose rayon ammonium phosphate felt. This article focuses on the surface modification of phosphates... Show More
- Abstract: Nonhalogen compounds have been studied for improvements in the flameproofing property and toxicity of flame retardants. Borate compounds have properties of multifunctional smoke suppressants, flame retardants, and afterglow suppressants. In this study, borate was coupled onto the surface of viscose rayon felt. Coupling and carbonization were confirmed by attenuated total reflectance Fourier transform infrared (ATR FTIR). The initial carbonization temperature was certified with ATR FTIR,... Show More
- Abstract: Phosphates (polyphosphate and ammonium phosphate) are synthesized onto the viscose rayon felt as high-performance materials for flame retardancy. This surface reaction has advantages of non-blooming effect and application to thermosetting plastics. Metal complexes have been known to have the effect of reducing amounts of smoke. Therefore, in second step, transition metal complexes were synthesized onto the viscose rayon ammonium phosphate felt. This article focuses on surface modification of... Show More
- Abstract: A new chelating fiber, poly(acrylo-amidino diethylenediamine), was synthesized based on polyacrylonitrile fibers in diethylenetriamine with the aid of AlCl3. Complex formation with CrO42– was strongly pH-dependent, as complexes formed only in the presence of NH3+ and NH2+. In the medium pH region, both ionic and hydrogen bonds were formed between poly(acrylo-amidino diethylenediamine) and the chromate ion, as was confirmed by means of FT-IR spectroscopy.
- Abstract: The main objective of this work is to prepare activated carbon fibers (ACF), analyze a synthesis mechanism of those fibers, and develop a new dye adsorption model. The surface chemical structures of the synthesized viscose rayon phosphates and ACF were analyzed using TOF–SIMS and ATR FT-IR. After steam-activation of carbon fiber at high temperature, the carboxyl group could not be observed due to the high temperature activation. Only the oxygen-contained carbon ring groups appeared. The... Show More
- Abstract: We have been searching a new ion exchange material in the form of a fiber which could get large advantages over the conventional bead type. In this approach, an effective chelating fiber is prepared by the coupling of polyacrylonitrile (PAN) and ethylenediamine. A synthesized ion exchange fiber (poly(acrylo-amidino ethylene amine), PAEA) achieved 7.8 mequiv/g of adsorption capacity in a batch test. The coupling process and capacity were confirmed through FT-IR, acid−base neutralization... Show More
- Abstract: The role of hydrogen bonding in the chemistry of transition-metal complexes remains a topic of intense scientific and technological interest. Poly(acrylo-amidino diethylenediamine) was synthesized to study the effects of hydrogen bonding on complexes at different pHs. The polymer was synthesized through the coupling of diethylene triamine with polyacrylonitrile fiber in the presence of AlCl3 · 6H2O addition. The adsorption capacity of this polymer was 11.4 mequiv/g. The ions used for the... Show More
- Abstract: In this article, we present a new adsorption model of anion particles onto a chelating fiber. Nonideal H+ adsorption on the chelating fiber can be described adequately by the use of the heterogeneity factor β and the parameter Φ indicates the geometric factor of effective concentration in this model. The best fits of amines adsorption data were obtained by means of the developed model using two factors. Poly(acrylo-amidino diethylene diamine) was synthesized as a chelating polymer through... Show More
- Abstract: Poly(acryloamidino ethyleneamine) (PAEA) and poly(acryloamidino diethylene diamine) (PADD) have been synthesized for the observation of CuII complex and Cu(OH)2 crystal-growth on the surface of different numbers of amino groups immobilized on polyacrylonitrile (PAN) fibers. The shape of CuII crystal growth depends on the amine chain length of the chelating fiber; Cu(OH)2 crystals grow on the surface of the chelating fiber after CuII adsorption.
- Abstract: A polyacrylonitrile (PAN) fiber was adopted for the backbone of a chelate polymer and poly(acrylo-amidino ethylene amine) (PAEA) was prepared through a one-step reaction between the PAN fiber and ethylenediamine (EDA). The maximum removal capacity and degree of substitution were 7.8 meq per gram of dried PAEA and 98%, respectively. The PAEA was tested as an adsorbent in single and two-component metal aqueous solutions under changing pH. The Cu2+ ion accomplished maximum adsorption amount at... Show More
- Abstract: For studying the influences of alkyl chain length, end groups of the side chains, and mixture on enhancing the shear stress of electrorheological (ER) fluids, chitosan carboxylates were synthesized for ER particles and prepared ER fluids by dispersing the particles in silicone oil. After comparing the shear stress of all prepared ER fluids, the conclusion obtained was that ER particles having two functional groups showed higher shear stress than those having one functional group. However,... Show More
- Abstract: Field-emission scanning electron microscopy (FESEM) was used to monitor pinecone-like Cu(II) crystal growth on polymeric fibers for various growth times. In FESEM images, Cu(II) complexes and Cu(OH)2 crystal growth on poly(acryloamidino ethylene amine) and poly(acryloamidino diethylenediamine) were observed. Up to an elapsed time of 16 min, crystal growth was observed in only one direction. However, after an elapsed time of 20 h, pinecone-like crystals covered the entire surfaces of the... Show More
- Abstract: Stable dispersions of monodisperse colloidal PS spheres of submicron-size have been synthesized according to a general emulsion polymerization procedure for PBG crystals. The size of the PS spheres can be controlled by the amounts of surfactant and monomer. The periodically ordered three-dimensional porous structure having submicron PS spheres was obtained using a precisely controlled withdrawing method in which the fabrication of the template and the infiltration of the voids of the... Show More
- Abstract: A unique chemosensor for Ag ions was created by coupling an anthracene signaling unit onto an amine-terminated glass slide. Chemical dye (Orange 11) was applied to establish the exposed amine groups on the surface, because the coupling reaction is dependent on the amount of the exposed amine groups. The assembled layer had a surface that was not flat but, instead, had an embossed shape, on the microscale; the surface roughness was greater than that of the original glass, because of the... Show More
- Abstract: By this time, when electrorheological (ER) fluids were applied long term, these have been limited because of problems with particle sedimentation. To solve the sedimentation problem, we report on the preparation of hollow polyaniline (PANI) sphere with nano-scale as the disperse phase for estimating electrical and ER properties. A procedure has been developed to coat colloidal polystyrene (PS) core within a PANI shell by chemical oxidation polymerization. The core-shell particles can be... Show More
- Abstract: In this study, functional pendants of chitosan were focused on enhancing the shear stress of electrorheological (ER) fluids. Chitosan succinates and chitosan phthalate were synthesized for ER particles and ER fluids were prepared by dispersing the particles in silicone oil. After comparing the shear stress of all prepared ER fluids, obtained conclusions were that ER particle having two functional groups (one is +ve charge and another is −ve charge) showed higher shear stress than that having... Show More
- Abstract: The electrorheological (ER) performance of submicron-sized hollow polyaniline (PANI) dicarboxylate salt form as an anhydrous ER materials suspended in a silicone oil, was studied under several applied external field strength. The influences of alkyl chain length, functional group, and hollow sphere of the novel synthesized PANI salt derivatives was focus on this paper, and their suspensions showed good ER response and dispersion stability. Throughout the experimental results, for hollow PANI... Show More
- Abstract: A viscose rayon succinate (VRS) was studied as a chelating fiber for the removal of metal ions from an aqueous solution. VRS was synthesized successfully from viscose rayon (VR) and succinic anhydride in the presence of dimethylsulfoxide (DMSO), and was characterized by C13 nuclear magnetic resonance 13C NMR, scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) analysis. The maximum bivalent metal ion adsorption capacity of the VRS was 6.2meq/g. Studies on the... Show More
- Abstract: This paper focused on effects of amine and π-orbital for enhancing electrorheological properties. Various aminated chitosans were synthesized by coupling of diethylenetriamine, melamine, and Bismarck brown R onto chitosan in this study. After comparing the shear stress of all prepared ER fluids, melamine and Bismarck brown R coupled chitosans showed higher shear stress than other ER chitosan derivatives. Because amine group is cation, cation–π interaction could be expected for enhancing... Show More
- Abstract: In this study, polymeric chelating fiber with good adsorbing capacity (11.4mequiv./g) and activated carbon fiber with high specific area (1560m2/g) were synthesized to compare the adsorption of heavy metal ions on these materials. The adsorption isotherm of various cations on activated carbon fiber and poly(acrylo-amidino diethylenediamine) showed similar adsorption behavior. High adsorptions were found at high pHs. At low pHs, adsorbed H+s on the benzene (in the case of activated carbon... Show More
Publications citing this author (581)
[Show abstract] [Hide abstract] ABSTRACT: A unique consideration is intended, concerning the creation of functional groups during the production of carbon fibres from polyacrylonitrile, i.e. oxidation/stabilization, carbonization/pyrolysis and electrochemical modification processes and their role for applications. Acrylic fibres of homopolymer PAN are subjected to thermo-oxidative treatment following a four-stage or a two-stage isothermal programme, and the resulting oxidized fibres are pyrolyzed up to 1000 °C for 30 min or they are flash-pyrolyzed at 1000 °C for 5 min, and the shrinkage and weight loss are determined. According to FTIR spectra, two indices were expressed to follow the dehydrogenations and cyclizations (nitrile groups) and the band intensity of carbonyl groups to follow the oxidation. The carbon fibres produced from the four-stage oxidation were examined using SEM/EDS. Based on SEM/EDS analysis, an oxygen content of approx. 8.7 at.% in the fibres is needed for the stabilization of the fibres during the oxidation by a four-stage treatment up to 300 °C. These carbon fibres were electrochemically modified by Cyclic Voltammetry in narrow and wide potential regions, using aqueous H2SO4. The electrochemical treatment of carbon fibres in the wide region leads to the introduction of an additional amount of oxygen of about 5 at.%, exhibiting also acidic and basic groups in adequate amount. The formation of oxygenous groups on carbon fibres during the three processes is indirectly followed by their ability to adsorb methylene blue or alizarin yellow dyes, based on the concept of “acid–base interaction”. Considering a model of a graphitic monolayer of a basic square that includes 9 rings, the O atoms introduced in this segment were estimated. Carbon fibre applications depend on the amount and type of oxygenous groups that can be targeted by selecting proper treatment conditions.
- Furthermore, other processes take place depending on the application sector of the carbon fibres e.g. their electrochemical treatment for their use as reinforcement in composites  , their activation for their use in environmental sector  and electrochemical deposition of noble metals on them for catalysts and electrodes in fuel cells .The PAN-based carbon fibres have been extensively used for reinforcement of composites, in the form of woven textiles, pre-pregs, continuous fibres/rovings, and chopped fibres [10, 11] , they are also used in the fabrication of heatshielding and chemically resistant materials, and materials with controllable electro-physical and physicochemical properties [2, 11, 12] because they combine superior properties including, high tensile strength and Young's modulus, excellent heat resistance, low density, high thermal and chemical stabilities in the absence of oxidizing agents, good thermal and electrical conductivities, and excellent creep resistance [6, 10]. The first step for the conversion of PAN fibres to carbon fibres is their oxidative treatment to form pyridine stabilized structures based on the cyclization of nitrile groups.
[Show abstract] [Hide abstract] ABSTRACT: A new carboxylated cellulose derivative (CTA) was prepared from the esterification of cellulose with 1,2,4–Benzenetricarboxylic anhydride. CTA was characterized by percent weight gain (pwg), amount of carboxylic acid groups (nCOOH), elemental analysis, FTIR, TGA, solid-state 13C NMR, X-ray diffraction (DRX), specific surface area, pore size distribution, SEM and EDX. The best CTA synthesis condition yielded a pwg and nCOOH of 94.5% and 6.81 mmol.g–1, respectively. CTA was used as an adsorbent material to remove Co2+, Cu2+ and Ni2+ from monocomponent spiked aqueous solution. Adsorption studies were developed as a function of the solution pH, contact time and initial adsorbate concentration. Langmuir model better fitted the experimental adsorption data and the maximum adsorption capacities estimated by this model were 0.749, 1.487, and 1.001 mmol.g–1 for Co2+, Cu2+ and Ni2+, respectively. The adsorption mechanism was investigated by using isothermal titration calorimetry. The values of ΔadsH° were in the range from 5.36 to 8.09 kJ.mol-1, suggesting that the mechanism controlling the phenomenon is physisorption. Desorption and re–adsorption studies were also performed. Desorption and re–adsorption efficiencies were closer to 100%, allowing the recovery of both metal ions and CTA adsorbent.
- Then, the flask was put in an oil bath at 100 °C placed on a heating plate (Corning Ò , model PC-420D) and magnetically stirred at 300 rpm for 1 h. At the end of reaction time, the flask was removed from the bath and left to cool (30 min) and the suspension was poured into a 250 mL Becker containing 125 mL of iso- propanol . The suspension was magnetically stirred for 30 min before being transferred to a sintered Büchner glass funnel (150 mL; porosity 3).
[Show abstract] [Hide abstract] ABSTRACT: Three kinds of electrorheological (ER) materials with carboxyl, amido and hydroxyl group, respectively, were synthesized by a simple adsorption method. The powder of silicon dioxide as a substrate of the materials, as well as terephthalic acid [p-C6H4(COOH)2, abbr.: phen-COOH], p-phenylenediamine [p-C6H4(NH2)2, abbr.: phen-NH2] and hydroquinone [p-C6H4(OH)2, abbr.: phen-OH] were chosen as starting materials. The ER properties of suspensions of the materials in silicon oil were studied. The suspension of the material adsorbing phen-COOH reveals the highest ER activity, the relative shear stress of the suspension (25 wt%), τr(=τE/τ0, τE and τ0 are the shear stresses at electric field strengths of E=4.2 and 0 kV/mm, respectively), reaches 220 under a DC electric field at a shear rate of 14.5 s−1. The shear stress of the suspension of the material adsorbing phen-NH2 is the largest at an high electric field strength. The ER activity of the material adsorbing phen-OH is the lowest among the three materials. The molecule structure is an importance factor in influencing ER performance of the materials for similar compounds with different polar function groups. The relationship between the ER activity and dielectric property of the materials was discussed. Keywordselectrorheological material–polar function group–chemical synthesis
- Lu Kun Quan et al. (Lu et al., 2007) succeeded in making a variety of new ER fluids containing polar organic molecules in particle materials, called polar molecule dominated ER fluids. The function group in the polar molecule are known to improve the ER effect of a material (Fang et al.,2006; Shen et al., 2009; Sung et al., 2007; Ko et al., 2006; Cho et al., 2005; Ko et al., 2004), and the molecules with π bond favor the ER performance (Hao, 2002). As is well knowledge, the comparison between three kinds of different polar function groups in influencing ER performance has not been reported.
[Show abstract] [Hide abstract] ABSTRACT: Thermal Properties of Polyaniline (PANI) Composite Film Synthesized by Nanocomposite Material TiO2 and Polyvinyl Alcohol has been investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dc conductivity analyses. The results clearly demonstrate that the composite film of nanocomposite material (encapsulated nano-TiO2 and Polyaniline) and poly-vinyl alcohol are more stable at higher temperature than pure polyaniline.
- For these nanocomposites (Nano TiO2 and PANI) most of the studies are completed with optical properties2324, electrical properties [20,2425 and magnetic properties . Electrical properties are significantly modified due to modified nano TiO2272829 and dispersion of nanoparticles polyaniline , or nano TiO2 in suitable medium as PVA3132, PMMA3334, EVA3536 is a novel technique to prepare a new composite film. Polyvinyl alcohol (PVA) is widely used as host matrix in the preparation of conducting polymer polyaniline nano composite film3738.
[Show abstract] [Hide abstract] ABSTRACT: Mg–Zn–Al LDH and its corresponding oxide were successfully employed for Cr(VI) removal from aqueous solutions. Maximum adsorption capacity of 29.25 and 33.82 mg g−1 for Mg–Zn–Al LDH and calcined Mg–Zn–Al LDH, respectively, was achieved using Cr(VI) initial concentration of 70 mg L−1, 0.2 g L−1 of adsorbent, stirring rate of 160 rpm, pH 6, a contact time of 105 min, and a reaction temperature of 298 K. The results show that the adsorption of Cr(VI) through the rehydration of calcined Mg–Zn–Al LDH is considerably higher than that through the anion exchange of Mg–Zn–Al LDH. Cr(VI) removal from aqueous solutions takes place via either anion exchange between interlayer anions of LDHs and Cr(VI) oxyanions or surface complexation between Cr(VI) oxyanions and inner and outer hydroxyl groups of LDH surfaces.
- 2. After adsorption of Cr(VI), the intensity of the characteristic band of CO 2À 3 anions decreased, indicating that these interlayer anions were replaced by Cr(VI) anions in solution. The main vibration bands for Cr(VI) are located at 940 (Cr–O) and 750 (Cr–O) cm −1 . No vibration bands are observed around 750 cm −1 .
[Show abstract] [Hide abstract] ABSTRACT: The core/shell structural dielectric particles are applied widely in the electrorheological (ER) fluids. In this work, we rationally designed and constructed two kinds of core/shell structured SiO2-based particles with TiO2 and hydroxyl titanium oxalate (TOC) as shell, respectively. The obtained core/shell structural SiO2/TiO2 and SiO2/TOC particles were well dispersed spherical nanoparticles with ideal morphology and a narrow size distribution. Under DC electric fields, the ER effect of the two kinds of core/shell particles dispersed in electrically insulating oil was examined and compared by steady shear flow and dynamic shear modes. It was found that the SiO2/TOC ER fluid showed a stronger ER effect compared to the SiO2/TiO2 ER fluid. The static yield stress of the SiO2/TOC ER fluid was up to 45 kPa at 5 kV/mm, which was twice of the SiO2/TiO2 ER fluid and 9 times of the SiO2 ER fluid. On the other hand, the zero field viscosity of the SiO2/TOC ER fluid was obviously lower than that of the SiO2/TiO2 ER fluid. Therefore, the ER efficiency of the SiO2/TOC ER fluid was much higher than that of SiO2/TiO2 ER fluid at the same electric field.
- Electrorheological (ER) fluids are a kind of smart materials which show a reversible and very fast (in a fraction of millisecond) transition from a liquid to a nearly solid state under the presence of external electric fields. These fluids can exhibit changes in apparent viscosity of several orders of magnitude when applied electric field densities of order of 1 kV/mm123456789 . This outstanding property makes them very good candidates for applications in electromechanical devices that require the active control of vibrations or the transmission of torque, such as active devices, clutches, brakes, shock absorbers, etc.101112131415.
[Show abstract] [Hide abstract] ABSTRACT: Polyacrylonitrile/polypyrrole (PAN/PPy) core/shell nanofiber mat was prepared through electrospinningfollowed by a simple chemical oxidation method. The polypyrrole-functionalized nanofiber mats showedselective adsorption performance for anions. The interaction between heavy metal anions and polypyrrole(especially the interaction between Cr2O72−and polypyrrole) during the adsorption process was studied.The results showed that the adsorption process included two steps: one was the anion exchange processbetween the Cl−and Cr(VI), and the other was the redox process for the Cr(VI) ions. The adsorptionamount was related to the protonation time of the PAN/PPy nanofiber mat and increased as protonationtime increased. Meanwhile, the Cr(VI) ions were reduced to Cr(III) through the reaction with aminogroups of polypyrrole (from secondary amines to tertiary amines). PAN/PPy nanofiber mat showed highselectivity for Cr(VI), and the adsorption performance was nearly unaffected by other co-existing anions(Cl−, NO3−, and SO42−) except for PO43−for the pH change.
- The modified PAN fibers showed good adsorption performance for both Pb 2+ and Cu 2+ at the pH values ranging from 2.3 to 6.0. Poly(acrylo-amidino ethylene amine) (PAEA) fibers synthesized through the coupling of reaction of polyacrylonitrile and ethylenediamine have also been used as the adsorbents for heavy metal ions . The maximum adsorption capacities for Cu 2+ , Ag + , Zn 2+ , Ni 2+ , and Pb 2+ were 3.21, 3.14, 2.22, 1.69, and 0.93 mmol/g of PAEA.
[Show abstract] [Hide abstract] ABSTRACT: The assembly of colloidal building-blocks is an efficient, inexpensive and flexible approach for the fabrication of a wide variety of photonic materials with designed shapes and large areas. In this review, the various assembly routes to the fabrication of colloidal crystals and their post-assembly modifications to the production of photonic materials are first described. Then, the emerging applications of the colloidal photonic structures in various fields such as biological and chemical sensing, anti-reflection, photovoltaics, and light extraction are summarized.
- The previous methods involved the fabrication of colloidal crystals directly onto the substrates, while the Langmuir–Blodgett technique is a two-step process whereby a two-dimensional colloidal crystal monolayer is first formed on a water surface before it is transferred onto the substrate [41,44,55]. The monolayer of particles is formed by first spreading a colloidal suspension onto the surface of water and then followed by compacting the particles on the water surface by using mobile (a) spin-coating ; (b) vertical deposition; (c) dip coating ; and (d) shear alignment .
[Show abstract] [Hide abstract] ABSTRACT: The adsorption of Cr(VI) from aqueous solutions to activated carbon fiber (ACF) was investigated using both batch and flow-through column experiments. The batch experiments (adsorbent dose, 10 g/L; initial Cr(VI) concentration, 5-500 mg/L) showed that the maximum adsorption capacity of Cr(VI) to ACF was determined to 20.54 mg/g. The adsorption of Cr(VI) to ACF was sensitive to solution pH, decreasing from 9.09 to 0.66 mg/g with increasing pH from 2.6 to 9.9; the adsorption capacity was the highest at the highly acidic solution pHs. Kinetic model analysis showed that the Elovich model was the most suitable for describing the kinetic data among three (pseudo-first-order, pseudo-second-order, and Elovich) models. From the nonlinear regression analysis, the Elovich model parameter values were determined to be α = 162.65 mg/g/h and β = 2.10 g/mg. Equilibrium isotherm model analysis demonstrated that among three (Langmuir, Freundlich, Redlich-Peterson) models, both Freundlich and Redlich-Peterson models were suitable for describing the equilibrium data. In the model analysis, the Redlich-Peterson model ft was superimposed on the Freundlich ft. The Freundlich model parameter values were determined to be KF = 0.52 L/g and 1/n = 0.56. The flow-through column experiments showed that the adsorption capacities of ACF in the given experimental conditions (column length, 10 cm; inner diameter, 1.5 cm; flow rate, 0.5 and 1.0 mL/min; influent Cr(VI) concentration, 10 mg/L) were in the range of 2.35-4.20 mg/g. This study demonstrated that activated carbon fiber was effective for the removal of Cr(VI) from aqueous solutions.
- Note that the point of zero charge (pH pzc ) of ACF was reported to be 4.3. Our result agreed well with the report of Ko and Choiwho showed that Cr(VI) adsorption to ACF decreased from 1.3 mmol/g to near zero with increasing pH from 1.5 to 12.7. Other researchers also reported that the adsorption of Cr(VI) to ACF was maximal at pH 3 and decreased with increasing pH.Cr(VI) Sorption to ACF dlich constant, Q m is the maximum mass of Cr(VI) removed per unit mass of adsorbent (removal capacity), K L is the Langmuir constant related to the binding energy, K R is the Redlich–Peterson constant related to the adsorption capacity, a R is the Redlich– Peterson constant related to the affinity of the binding sites, and g is the Redlich–Peterson constant related to the adsorption intensity.
[Show abstract] [Hide abstract] ABSTRACT: The electromechanical behavior of thermoplastic elastomer polyurethane (TPE-PU) is investigated under the effects of urethane type (ester and ether-types) and soft–hard segments at various electric field strengths and temperatures. The highest dielectric constant, electrical breakdown strength, and specific conductivity belong to the ester-type polyurethane (LPR matrix), while the lowest values are obtained from the ether-type polyurethane composing predominantly with the soft-segment (E 80A matrix). Under the electric field strength in the range between 0 and 2 kV/mm, the LPR matrix attains the storage modulus sensitivity (ΔG′/G′0) up to 2 at 2 kV/mm. For the temporal response, the polyurethanes behave with good reproductively (number of cycles >105 times) and with very good recoverability. The steady state behavior can be attained at the first actuation and at the electric field strength of 1 kV/mm. Furthermore, the storage modulus (G′) shows linearly negative responses with increasing temperature. In the deflection experiments, the deflection distance and the dielectrophoresis force increase monotonically with increasing electric field strength. All of the TPE-PU possesses very fast response times for activation (<10 s.) and deactivation (<5 s.). TPE-PU material is systematically shown here to be a potentially good actuator material with high efficiency based on the electrostrictive performance data obtained.
- The smart materials generally tend to respond with any external stimuli such as pH , temperature , electric field  and etc, by changing shapes and or dimensions. Electroactive polymers (EAPs) belong to one sub-group of the smart materials in which the mechanical response can be induced by electric field ; as these materials can be utilized in the actuator and transducer applica- tions . There are many required properties: lightweight, good mechanical flexibility, high resilience, good processability and short response time [6e8].
[Show abstract] [Hide abstract] ABSTRACT: The reduction in specific heat commonly encountered due to the addition of nanoparticles to a heat transfer fluid such as propylene glycol-water mixture, can be overcome by co-dispersing surfactant-encapsulated paraffin wax, leading to formation of a hybrid nanofluid. Experimental investigations have been carried out on the preparation and evaluation of thermophysical properties of a hybrid nanofluid containing pluronic P-123 encapsulated paraffin wax (70–120 nm diameter, 1–5 wt.%) and sand nanopar-ticles (1 vol%) in propylene glycol-water mixture. The comparison of results of differential scanning calorimetry of pure paraffin wax and encapsulated paraffin wax revealed encapsulation efficiency of 84.4%. The specific heat of hybrid nanofluids monotonously increased with paraffin wax concentration, with 9.1% enhancement in specific heat for hybrid nanofluid containing 5 wt.% paraffin wax, in comparison to propylene glycol-water mixture. There exists an optimum paraffin wax concentration (1 wt.%) for the hybrid nanofluid at which the combination of various thermophysical properties such as specific heat, thermal conductivity and viscosity are favorable for use as heat transfer fluid. Such a hybrid nanofluid can be used as a substitute for propylene glycol-water mixture in solar thermal systems.
- The latent heats of melting and fusion for the encapsulated paraffin wax and paraffin wax were obtained from the differential scanning calorimetry results of three heating and cooling cycles respectively. The encapsulation ratio (g r ) was calculated as the ratio of latent heat of melting of encapsulated paraffin wax (k ep,m ) to the latent heat of melting of paraffin wax (k p,m ) .
[Show abstract] [Hide abstract] ABSTRACT: Aminated polyacrylonitrile(APAN) nanofiber mat was a surface modification of electrospun polyacrylonitrile (e-spun PAN) with diethylenetriamine (DETA). It was developed for the removal of Ag(I), Cu(II), Pb(II) and Fe(II) from aqueous solution. The results showed that adsorbent has the highest adsorption capacity for Ag(I) and Cu(II) in ions mixture system. The parameters of adsorption behavior were also investigated, such as pH-value, initial concentration and contact time. Langmuir and Freundlich isotherm models were applied to analyze the experimental data. Desorption experiments by elution of the adsorbent with a nitric acid show that the APAN nanofiber mats could be reused. APAN nanofiber mat has been shown to have the potential to be used as an effective adsorbent for the removal as well as selective recovery of heavy metal ions in water or wastewater treatment.
- On the other hand, the spectra of the APAN fiber mats showed new absorption bands at 3339, 1656, 1600, and 1480 cm 1 . These can be assigned to the stretching vibrations of the secondary amine (NH), the amidine group (NC=N), and the primary amine (NH 2 ) and the bending vibrations of the methyl group of DETA, respectively , . As result, it can be indicated that both of nitrile and carbonyl group are conversed to amidine and amide group, respectively, which is shown inFig.
[Show abstract] [Hide abstract] ABSTRACT: Application of thermogravimetry (TG) alone to study compatibility/incompatibility of active pharmaceutical ingredients (APIs) with excipients yields to misleading results due to overlapping of the thermal stages in the course of decomposition of both ingredients and their pharmaceutical mixtures. Hence, the purpose of this study was to assess the usefulness of multivariate statistical analysis as a supporting tool for interpretation of the TG traces during assessing compatibility of hydrocortisone as an API with selected excipients (mannitol, starch, lactose, methylcellulose, β-cyclodextrin, meglumine, chitosan, magnesium stearate and polyvinylpyrrolidone). The results show that two multivariate techniques, principal component analysis (PCA) and cluster analysis (CA), can be successfully used for interpretation of TG traces, while the TG is used alone as a screening technique to assess compatibility. The results obtained by using TG analysis, supported by PCA and CA, were approved by those of differential scanning calorimetry, infrared spectroscopy and X-ray powder diffraction. Incompatibilities were only found in mixtures of hydrocortisone with magnesium stearate and β-cyclodextrin.
- A detailed inspection of the thermal events due to the melting of hydrocortisone (216 °C , 214 °C  or 221.5 °C ) and of anhydrous a-lactose (222.8 °C , 223 °C ) suggests that both endothermic peaks are superimposed excluding incompatibility. The IR spectra of hydrocortisone, excipients and their mixtures are shown in Figs. 8 and 9. Inspection of these spectra shows that characteristic bands of ingredients alone are consistent with those reported in the literature . There are characteristic bands of hydrocortisone due to stretching vibrations of the O–H groups, C–H bonds, C=O groups and C– OH bonds over the ranges 3650–3100, 3100–2800, 1850–1540 and 1260–1000 cm -1 , respectively.
[Show abstract] [Hide abstract] ABSTRACT: The present investigation explores the chemical modification of natural dry babassu coconut (Orbignya speciosa) mesocarp (BM), using a quasi solvent-free procedure in which the precursor was added to molten succinic (S), maleic (M) or phthalic (P) anhydrides, to give new products named BMS, BMM and BMP (babassu coconut mesocarp modified with succinic, maleic and phthalic anhydride, respectively). These synthesized biopolymers were characterized by infrared spectroscopy and thermogravimetry and the degree of substitution was calculated, based on the number of carboxylic groups covalently attached to the lignocellulosic polymer. The chemically modified biopolymers suspended in aqueous or hydroalcoholic solutions have the ability to remove copper from aqueous or aqueous-alcohol solutions in the order BMS > BMP > BMM. The kinetic process followed a pseudo-second-order model and the results for sorbents were better represented by the Langmuir sorption model. The effectiveness of these biopolymers for application to real samples of sugar cane spirits reflected in using only 1.0 g dm−3 to reduce the copper to a value lower than 5.0 mg dm−3 for all sorbents. Thus, these inexpensive chemically modified biopolymers may be useful to permit sugar cane spirits to meet the requirements of Brazilian legislation with respect to copper contamination.
- On the other hand, the increase in pH deprotonates carboxylate groups, a condition that favors their chelating abilities and, consequently, the amount of sorbed Cu 2+ ions is increased. An identical behavior was previously observed for other systems, in which the attached function, derived from succinic anhydride, chelated bivalent and trivalent cations10111224,25].
[Show abstract] [Hide abstract] ABSTRACT: Efficient removal of benzene, toluene, ethylbenzene and xylene (BTEX) from aqueous solution has been studied with a β-cyclodextrin (β-CD) modified poly(butyl methacrylate) resin (poly(BMA-Co-CD). The effects of the amount of β-CD in poly(BMA-Co-CD), pH, ionic strength, contact time, and temperature of the solution on the adsorption of BTEX were investigated in details. Adsorption data were fitted very well to Freundlich model. The results showed that the β-CD groups on the resin played a significant role for adsorption of BTEX, and quantum chemical calculation confirmed the experimental results. The resin exhibits good performance e.g. high adsorption capacity, high separation efficiency, and easy regeneration.
- The adsorption energy (E a ) can give information about chemical and physical adsorption about chemical and physical adsorption for the adsorption process . If E a is in the range of 1–8 kJ/mol, the adsorption is physical adsorption; If E a is between 8 and 16 kJ/mol, the adsorption process follows by ion exchange, whereas E a in the range of 20–40 kJ mol À1 is indicative of chemisorption [24,25]. As listed in Table s3, E a are 4.41, 5.02, and 8.86 kJ/mol for benzene, 4.51, 5.25, and 13.81 kJ mol À1 for toluene, 10.97, 11.91, and 13.67 kJ mol À1 for ethylbenzene, and 13.18, 11.60, and 15.91 kJ mol À1 for p-Xylene at 20, 30, and 40 °C, respectively.
Korea UniversitySŏul, Seoul, South Korea