bluuebunny/crossref_metadata_2025_split huggingface dataset:
DEA and DSC study of cubic silsesquioxane epoxy resin nanocomposites
Authors: Dias Filho Newton Luiz , Aquino Hermes Adolfo de 
Published: August 2014

AbstractNon-isothermal dielectric analysis (DEA) and differential scanning calorimetry (DSC) techniques were used to study the epoxy nanocomposites prepared by reacting 1,3,5,7,9,11,13,15-octa[dimethylsiloxypropylglycidylether] pentaciclo [9.5.1.13,9.15,15 .17,13] octasilsesquioxane (ODPG) with methylenedianiline (MDA). Loss factor (ε”) and activation energy were calculated by DEA. The relationships between the loss factor, the activation energy, the structure of the network, and the mechanical properties were investigated. Activation energies determined by DEA and DSC, heat of polymerization, fracture toughness and tensile modulus show the same profile for mechanical properties with respect to ODPG content.
Synthesis and radical polymerizations of acrylamides having Gabapentin moieties
Authors: Akat Hakan , Balcan Mehmet 
Published: August 2014

Abstract The synthesis and radical polymerizations of several acrylamides having Gabapentin(GBP) moieties were examined. The monomers were prepared by the reactions of 1-aminomethyl-1-cyclohexane acetic acid salts with acryloyl chloride in the presence of triethylamine in moderate yields. Radical polymerizations of the monomers were carried out in the presence of AIBN (3 mol%) in Dimethyl formamide (DMF) with moderate yield. The thermal behavior of the polymers was investigated by thermo gravimetric analysis (TGA) and differential scanning calorimeter (DSC) to determine the thermal degradation pattern and glass transition temperature (Tg). The resulting polymers showed a thermal stability up to 400 °C. The glass transition temperatures of the polymers were found not to depend on the substituents of the GBP moieties. Nearly the same TG’s were observed for polymers. We found the molecular weights of the polymers to be between 20700 and 2300 g/mol. We obtained poly(HFCHA) as a water-soluble polymer. Poly(MFCHA), poly(EFCHA) and poly(PFCHA) were soluble in common solvents.
Morphological and chromatographic characterization of molecularly imprinted monolithic columns.
Authors: Sirc Jakub , Bosakova Zuzana , Coufal Pavel , Michalek Jiri , Pradny Martin , Hobzova Radka , Hradil Jiri 
Published: August 2014

AbstractThe chromatographic stationary phases based on molecularly imprinted monoliths were prepared by free radical polymerization and subsequently characterized. The mixture of commonly used comonomers of ethylene dimethacrylate/methacrylic acid was polymerized in presence of various porogenic mixtures. Tosyl-L-phenylalanine was selected as a model template. Polymerization steps were carried out in the glass columns (i.d. of 3.3 mm) enabling UV initiation. Difficulties encountered with polymerization in situ, e.g. volume contraction and adhesion of polymer onto the glass inner wall, were successfully solved. The morphology of monoliths was investigated by electron microscopy, mercury porosimetry and surface area measurements. The influence of polymerization conditions on monolith morphology and subsequent chromatographic properties was evaluated. Polymers prepared by UV polymerization showed higher total porosity and the most frequent pore radius compared to the same polymers prepared thermally. The prepared monoliths by UV irradiation were also significantly more permeable for mobile phase during the chromatography tests. Morphology of monoliths prepared in dodecanol/toluene porogenic mixture markedly depended on the temperature of polymerization; the most frequent pore radius decreased with increasing temperature. From chromatographic point of view, monolithic columns were tested by separations of standard hydrophobic solutes. Height equivalent to a theoretical plate reached the values of approx. 25 μm, Walters indices of hydrophobicity laid slightly above 3. Prepared monoliths were compared to the conventional columns, filled with the particles prepared from the polymer of the same composition and preparation. In many cases the monolithic columns showed better chromatographic parameters.
On polyamide 6-montmorillonite nanocomposites obtained by in-situ polymerization
Authors: Monticelli Orietta , Musina Zenfira , Ghigliotti Francesca , Russo Saverio , Causin Valerio 
Published: August 2014

AbstractNanocomposites based on polyamide 6 (PA6) and montmorillonite-type (MMT) commercial clays, either unmodified or organically modified, were prepared by in-situ polymerization of ε-caprolactam (CL). The above materials were characterized in detail by a number of experimental techniques, including transmission electron microscopy (TEM), wide angle X-ray diffraction (WAXD), infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The formation of nanostructured systems was checked not only for the commonly used ω-aminoacid-modified clay, but also for other types of organoclays. In general, a correlation was found between nanoscopic swelling of the clay in molten CL, measured by X-ray diffraction, and level of clay dispersion in PA6. Specifically, with the most swellable clays, completely exfoliated nanocomposites were obtained. However, also layered silicates modified by compatibilizers having carboxy groups, because of the active role of latter in CL polymerization, formed delaminated nanocomposites despite their low degree of swelling in CL monomer. Both molecular mass and crystallinity of the polyamide matrix were found to be strongly influenced by the presence of specific layered silicates. In particular, some characterization techniques (WAXD, FTIR) have evidenced a close relationship between the MMT used and PA6 crystal structure. Namely, PA6 γ-form is promoted by clay with compatibilizer bearing the carboxy group, which is able to induce the polymer to be tethered on the silicate layers, thus provoking conditions of restricted mobility to occur.
Construction of an arranged nano-fibrous structure by selforganization of a designed amphiphilic peptide based on β- strand
Authors: Hattori Makoto , Hayashi Shujiro , Yokoi Hidenori , Tanaka Masayoshi , Kinoshita Takatoshi 
Published: August 2014

AbstractAn amphiphilic peptide having alternate sequence of hydrophobic and charged amino acid residues, RFDF16 (CH3CO-RFDFRFDFRFDFRFDF-NH2), was designed to form a β-sheet monolayer at the air/water interface. The peptide monolayer was prepared by Langmuir-Blodgett (LB) method. The LB films were transferred onto mica substrates without the compressing process at various pH values in order to investigate a self-organized structure of peptide monolayer. Surface morphology of LB films showed arranged nano-fibers which have differences in interval between fibers and their orientation depending on pH of the subphase. On the other hand, the self-organized nano-fiber was also re-arranged by compressing process. The nano-fibers became elongated and aligned upon compression to higher surface pressures. The exploitation of an electrostatic interaction and compressing process will allow a larger two-dimensionally regulated nano-structure.
Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization of Vinyl Monomers Initiated by Poly(methyl methacrylate) Peroxide
Authors: Zhang Zhengbiao , Zhu Xiulin , Zhu Jian , Cheng Zhenping 
Published: August 2014

AbstractPoly(methyl methacrylate) peroxide (PMMAP) was synthesized and used as the initiator in the reversible addition-fragmentation chain transfer (RAFT) polymerization. Methyl methacrylate (MMA) as the monomer and 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN) as the chain transfer agent was used in the polymerization system. The polymerization was successfully initiated by PMMAP while maintaining features of “living”/controlled radical polymerization such as the number-average molecular weights (Mn) increasing linearly with the monomer conversions and low polydispersity index (PDI) values. The results of 1H NMR and IR spectra confirmed that a small quantity of polymer chains were derived from the PMMAP moieties. The PMMAP can also initiate the RAFT polymerization of styrene (St) and methyl acrylate (MA), and the polymerization proceeded in a “living”/controlled fashion.
Effect of addition of organic solvents on properties of the chemically synthesized polyaniline in aqueous solutions
Authors: Xing Shuangxi , Jing Shengyu , Zhao Chun , Wang Zichen 
Published: August 2014

AbstractIn the process of polymerization of aniline in aqueous solution, different kinds or volumes of organic solvents were added. The effects of the organic solvents on the morphology, structure, conductivity and water-dispersity of the resulting polyaniline (PANI) were investigated with the aid of SEM, UV-Vis, FT-IR and Raman spectra and conductivity measurements. The results showed that the weak H-bond interactions between PANI and the solvents might play an important role in forming uniform nanofibers with relatively high conductivity and good waterdispersity. However, excessive addition of organic solvents led to the aggregation of the nanofibers and the corresponding PANI had a bad water-dispersity.
Synthesis and stimuli-responsive properties of Polyacrylic acid and Polyacrylamide Trapped with Polysodium-pstyrenesulfonate semi-IPN hydrogels
Authors: Wang Yansong , Wu Chengxun 
Published: August 2014

AbstractA series of Polyacrylic acid (PAA)/Poly (Sodium-p-styrenesulfonate) (PSS) and Polyacrylamide (PAAm)/PSS semi-IPN hydrogel with different contents of PSS were prepared. The swelling behaviour of PAA hydrogel in alkaline environment was improved while the swelling ratio of PAAm hydrogel was decreased after PSS was added. With the increase of ionic strength in solution, the swelling ratios of PAA/PSS and PAAm/PSS showed a decreasing trend. Moreover the swelling ratio of PAAm/PSS decreased more quickly than that of PAA/PSS. The swelling speed of PAA and PAAm both decreased after adding PSS and a more rapid responsive speed was found in the former system. The experiment of in vitro drug release showed that the drug release speed from PAAM/PSS semi-IPN hydrogel was slower than that from PAA/PSS semi-IPN hydrogel. These results suggested that the polymer composition and the trapped polyelectrolyte made a great influence on the drug release behavior.
Adsorption Behaviour of Methylene Blue from Aqueous Solution on Poly(Ethylene Terephthalate)-g-4-Vinylpyridine/ 2-Hydroxyethylmethacrylate Fibers
Authors: Yiğitoğlu Mustafa , Arslan Metin 
Published: August 2014

AbstractIn this study, a novel fibrous adsorbent obtained by grafting 4-vinyl pyridine (4-VP)/2-hydroxyethylmethacrylate (HEMA) comonomers onto poly (ethylene terephthalate) (PET) fibers was used for removal of methylene blue (MB) from aqueous solutions through a batch equilibration technique. The Influence of treatment time, pH of the solution, dye concentration, reaction temperature and percent graft yield on adsorbed amount were investigated. 300 min. of adsorption time was found sufficient to reach adsorption equilibrium for MB. It was found that the adsorption isotherm of MB fitted to Langmuir type isotherm. The highest adsorption capacity was found to be 55.33 mg MB per gram adsorbent. The adsorbed amount of MB was much higher on the comonomers grafted PET fibers than on the ungrafted PET fibers. MB was removed by 98 % while the initial dye concentration was at 5 mg L-1 and by 88% at 300 mg L-1 by monomers mixture grafted PET fibers. It was found that the reactive fibers were stable and regenerable by acid without loosing their activity.
Fatigue Crack Growth Process in CPVC Pipe Couplings
Authors: Khan Z. , Merah N. , Saghi F. 
Published: August 2014

AbstractAn investigation of the influence of temperature and loading frequencies on the morphological features found on the fatigue fractured surface of chlorinated polyvinyl chloride (CPVC) has been conducted. Single edge notched rectangular coupons obtained by flattening schedule 80 CPVC pipe couplings were subjected to fatigue loading at different temperatures of 0, 23, 40, and 70 °C and frequencies of 0.1, 1, and 50 Hz. Crack growth in CPVC, involved a combination of shear yielding and crazing processes. At the test temperature of 0 °C and 23 °C, the fatigue crack growth was noted to occur predominantly by shear yielding while crazing played a secondary role. On the other hand at 40 °C and 70 °C, the fatigue crack growth process appeared to predominantly involve a crazing process while shear yielding played a less significant role. Filler material particles played a major role as brittle second phase stress-raiser particles and facilitated craze initiation. iDiscontinuous crack growth bands (DGBs) indicating repeated crack arrests were also noted on the fracture surface.
A novel low k thin film based on plasma-polymerized 1- cyano isoquinoline
Authors: Xiong-Yan Zhao , Ming-Zhu Wang , Zhi Wang 
Published: August 2014

AbstractA novel low dielectric constant polymer, plasma-polymerized 1-cyano isoquinoline (PPCIQ) was prepared by plasma polymerization for the first time. The structure and surface compositions of the deposited PPCIQ thin films were investigated by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The results show that a high retention of the aromatic ring structure of the starting monomer in the deposited plasma films is obtained when a low discharge power of 15 W was used during film formation. In the case of higher discharge power of 35 W, more severe monomer molecular fragmentation can be observed. The dielectric properties measurements show that a low dielctric constant of 2.62 can be obtained for PPCIQ thin film deposited at 15 W.
Use of chemically modified poly(ethylene terephthalate)-g- (acryl amide) fibers for α-amylase immobilization
Authors: Temoçin Zülfikar , Yiğitoğlu Mustafa 
Published: August 2014

AbstractAcryl amide grafted Poly(ethylene terephthalate) (AAm-g-PET) fiber was used for covalent coupling of α-amylase. The amide groups of Poly(acryl amide) were converted to the amine groups by Hofmann degradation reaction. The amine groups were activated by glutaraldehyde, before coupling of the enzyme. The free α-amylase and immobilized α-amylase were characterized by determining the activity profile as function of pH, temperature, thermal stability and storage stability. For the immobilized α-amylase, operational stability was also determined. The immobilization of α-amylase on support caused the optimal reaction pH to shift from 5 to 6. The maximum activity of the free and immobilized enzymes occurred at 50 0C. Km for the immobilized system was higher than that for the free enzyme. The activity of the free enzyme ended in 30 days, whereas the activity of the immobilized enzyme lasted for 60 days at storage conditions. α-Amylase immobilized on matrix maintained 40% of its original activity after 30 times of repeated use.
Highly gas permselective polyetherketone hollow fibre membranes using aqueous sulfuric acid solution as coagulant
Authors: Yang Jiping , Brown Philip J 
Published: August 2014

AbstractHollow fibre membranes with more sponge-like morphology and improved gas permeation performance were spun from 20% polyetherketone (PEK) /sulfuric acid (H2SO4) dope solution with aqueous sulfuric acid solution as coagulant using dry-jet wet spinning process. The membrane morphology, mechanical properties and gas separation performance (hydrogen, methane and carbon dioxide) of as-spun PEK hollow fibres have been measured using SEM, Instron and gas test rig. Better cross section structures and mechanical properties in as-spun PEK hollow fibres were observed when aqueous sulfuric acid solution replaced water as coagulant (internal and external). The hydrogen/methane selectivity of up to 40 and hydrogen permeation rate of 3.65 GPU obtained in PEK hollow fibre membranes using 30% sulfuric acid solution as internal and external coagulant simultaneously at the bore fluid injection rate of 30 ml/h are higher than those reported in literatures. Furthermore the effects of bore fluid injection rate and various coagulants on the membrane morphology, mechanical properties and gas separation properties were investigated, as well.
Novel poly(fluorene-alt-squaraine) derivatives having large coverage with solar spectrum
Authors: Jiangyong Wu , Erfu Huo , Zhibing Wu , ZhiYun Lu , Minggui Xie , Qing Jiang 
Published: August 2014

AbstractNovel main-chain-conjugated poly(fluorene-alt-squaraine) using vinyl as linkage group were synthesized through direct condensation of 9,9’-dioctylfluorene derivates and squaric acid. The resulting polyfluorenes were characterized by NMR and FT-IR. They have good solubility in common organic solvents, good thermal stability and electrochemical reversibility. The structure of donor-acceptor-donor interaction in the polymer backbone resulted in much more red-shifted absorption spectra of 500-1000 nm, and extremely low band gaps of ~1.2 eV have been obtained. Their absorption spectra have large coverage with solar spectrum, suggesting that they are potential materials that can be used in photovoltaic devices.
Surface Characterization of Absorbing Polymer Films Deposited on Transparent Glasses
Authors: Gonçalves Débora , Travain Silmar A. , Giacometti José A. , Irene Eugene A. 
Published: August 2014

AbstractPANI films were deposited on glass substrates by in-situ polymerization and characterized by UV-VIS spectroscopy and atomic force microscopy. A method is developed to accurately analyze ellipsometric data obtained for transparent glass substrates before and after modification with absorbing polymer films. Surface modification was made with an overlayer such as polyaniline (PANI), which exhibits different optical properties by varying its oxidation state. First, the issue of using transparent substrates for ellipsometry studies was examined and then, spectroscopic ellipsometry was used to characterize absorbing overlayers on transparent glasses. The same methodologies of data analysis can be also applied to other absorbing films on transparent substrates, and deposited by different techniques
The structure and property of the electrospinning silk fibroin/gelatin blend nanofibers
Authors: Weiwei Bao , Youzhu Zhang , Guibo Yin , Jialin Wu 
Published: August 2014

AbstractNanofibers could provide benefits due to high surface area for biomaterial scaffolds. In order to improve both silk fibroin and gelatin performance for potential biomedical applications, in this article the electrospinning of silk fibroin (SF)/gelatin (GT) blends with different composition ratio and concentration was performed with formic acid as a spinning solvent. The nanofibers morphologies and diameters were observed by Scanning electron microscopy (SEM). Blending with GT could improve the viscosity and spinnability of spinning solution. As-spun SF/GT blend nanofibers were more homogeneous and non-beaded than pure SF nanofibers. The diameter decreased with higher voltage at same electric field intensity. On increasing the concentrations of spinning solution, the pore diameter of nanofibers decreased, and the porosity increased. In addition, FTIR and DTA analyses showed SF/GT nanofibers had more β-sheets than pure SF nanofibers, which may be caused by an intermolecular interaction between SF and GT. Blending with GT also led to substantial enhancement in mechanical properties of SF nanofibers.
Using eggshell as a filler in elastomeric compounds: effect of incubation period on its performance toward elastomers
Authors: Dakhel Hadi Ramezani 
Published: August 2014

AbstractThe effect of incubation period and the presence of organic membrane on eggshell activity toward elastomers (NBR, NR and SBR) has been investigated. After hatching eggshell (AHES) showed enhanced mechanical properties when compared to before hatching eggshell (BHES) and calcium carbonate. Compounds containing BHES powder also showed good mechanical properties. Both types of eggshells reduced optimum curing time of the compounds. This trend was more considerable in NBR compound. The improvement of mechanical properties of the compounds attributed to elemental composition and higher specific area of AHES. The results of this study showed both before hatching and after hatching eggshell can be used in elastomeric compound as a bio-filler
Polyhydroxyalkylation of urea with ethylene carbonate and application of obtained products as components of polyurethane foams
Authors: Zarzyka-Niemiec Iwona 
Published: August 2014

AbstractThe reaction between urea and ethylene carbonate occur with partial release of CO2 and partial incorporation of carbonate groups into products. The carbonate groups were found to be attached both to nitrogen of urea and to oxyethylene chain. The most effective catalyst of the synthesis was potassium carbonate. The hydroxyethyl and hydroxyethoxy groups of urea derivatives undergo partial dimerization to form carbamate groups in the products. The products of reaction between urea and ethylene carbonate have good thermal stability, they start to decompose at 200°C. The obtained products can be used as polyol components for polyurethane foams. Polyurethane foams obtained from hydroxyethoxy derivatives of urea (EC8) are rigid products of low water uptake, good stability of dimensions, low mass loss on 30 days heating at 150°C, enhanced thermal stability and good compressive strength.
MWNT Surface Self-Assembling in Fire Retardant Polyethylene-Carbon nanotubes nanocomposites
Authors: Bocchini Sergio , Annibale Emanuela , Frache Alberto , Camino Giovanni 
Published: August 2014

AbstractMultiwall carbon nanotubes (MWNT) were melt blended at different concentration with linear low density polyethylene (LLDPE). The nanotubes impart the fire-retardant characteristics to the polymer by formation of a thin protective film of MWNT/carbon char generated on the surface of the nanocomposites. The film formation mechanism is discussed
Sisal, Sugarcane Bagasse and Microcrystalline Celluloses: Influence of the Composition of the Solvent System N,NDimethylacetamide /Lithium Chloride on the Solubility and Acetylation of these Polysaccharides
Authors: Ciacco Gabriela T. , Ramos Ludmila A. , Frollini Elisabete , Ass Beatriz A. P. 
Published: August 2014

AbstractThe present work describes an investigation concerning the acetylation of celluloses extracted from short-life-cycle plant sources (i.e. sugarcane bagasse and sisal fiber) as well as microcrystalline cellulose. The acetylation was carried out under homogeneous conditions using the solvent system N,Ndimethylacetamide/ lithium chloride. The celluloses were characterized, and the characterizations included an evaluation of the amount of hemicellulose present in the materials obtained from lignocellulosics sources (sugarcane and sisal). The amount of LiCl was varied and its influence on the degree of acetate substitution was analyzed. It was found that the solvent system composition and the nature of the cellulose influenced both the state of chain dissolution and the product characteristics. The obtained results demonstrated the importance of developing specific studies on the dissolution process as well as on the derivatization of celluloses from various sources.
Modeling the physical properties of a homologous series on the melting temperatures and densities of n-alkanes and their simple alkyl-derivatives
Authors: Rubčić Antun , Rubčić Jasna , Chickos James S. 
Published: August 2014

AbstractSeveral aspects of the melting temperatures (MT) of linear chain homologs are discussed. It is shown that with some reasonable modifications of Einstein's model of simple solids, the MT of n-alkanes and their derivatives can be successfully modeled. Results are compared with those obtained by previous authors who have used numerical methods and thermodynamics. Results of investigation of quadratic recurrence relations of the second order and forms including exponential functions are reported. Finally, the correlation of MT with density at T = 298.15 K gives the limiting value, 0.86 gcm-3 , at the temperature of nearly 420 K. It is expected that proper correlations should use densities of liquids just at the MT, because some available data suggest a linear dependence of MT on density. All results obtained are mutually consistent