bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability of inverse microemulsions of acrylamide-based anionic flocculants: evidence about the need of unsaturated surfactants
Authors: Ochoa G José R. , Muñoz H. Marta , Reinoso Diego , Sasia Pedro M. , Escudero Francisco J. , Río Francisca , Nieto Mestre Javier , Torrecilla Jesús 
Published: August 2014

AbstractInfluence of surfactant structural characteristics on stability of inverse microemulsions of acrylamide-based anionic flocculants (40% (w/w) sodium acrylate and 60% (w/w) acrylamide, based on total amount of comonomers) has been studied by using 17 surfactant blends consisting of two non ionic surfactants with different length of hydrophobic chains, different number of hydrophobic chains per molecule, and with and without double bonds on their hydrophobic chains. Experimental evidence shows that unsaturated emulsifiers are needed for obtaining stable inverse microemulsions of acrylamide-based anionic flocculants and that presence of double bonds on the hydrophobic tails of a surfactant is its major structural characteristic to stabilize this kind of polymeric inverse microemulsions (PIM).
Electrical conductivity of poly(N-vinylcarbazole)-based polysodium-2,9,16,23-tetramethylamine tetracyclohexane tetrazaporphyrin composites
Authors: Zamora Fernando , González Carmen , Carballo Tamara , Zamora Nuria , Lezama Luis 
Published: August 2014

AbstractEfforts to improve dc-conductivity in poly(N-vinylcarbazole) (PVK) are addressed through composites. Such systems included phthalocyanine-based additives with both electronic and ionic character. We present a polysodium- 2,9,16,23-tetramethylamine tetracyclohexanetetrazaporphyrine, acting as the conductive additive in a PVK-binder. A paramagnetic behaviour appears in the additive when heated in the range 70-100°C, which induced further conductivity in the sample. Dc-electrical conductivity was studied for different PVK-additive compositions, in isothermal conditions, using a sandwich Pt/sample/Pt cell. By applying the Poole-Frenkel theory a trapping state was evidenced showing temperature and electric field dependence. An electric field of 9x104V/m establishes a frontier from which the conductivity mechanism is changed. Mobility of charge carriers was calculated according to the Mott-Gurney´s equation
The effect of temperature on tacticity for bulk thermal polymerization of styrene
Authors: Ziaee Farshid , Nekoomanesh Mehdi , Mobarakeh Hamid Salehi , Arabi Hassan 
Published: August 2014

AbstractThree types of polystyrenes were prepared at different temperatures of 50, 150 and 250°C by bulk thermal polymerization of styrene below 20 percent of conversion. The assignment of all stereosequences at pentad level of quaternary aromatic carbon and hexad level of methylene carbon of the polystyrenes were done using 13C Liquid NMR in deuterated chloroform at similar conditions. Bernoullian and first-order Markov statistics were calculated and the results were compared with experimental NMR results. It is shown that first-order Markov statistics fit slightly better than Bernoullian statistics for the assigned carbons. The results indicated that by increasing polymerization temperature the probability of meso addition (Pm) in polystyrene chains was enhanced. Pm was calculated for polystyrenes prepared at 50, 150 and 250°C and corresponding values were 0.378, 0.398 and 0.402 respectively. It was shown that by increasing temperature the polymerization is directed toward the Bernoullian propagation. By increasing the NMR acquisition temperature from 20 to 65°C higher resolution especially in quaternary aromatic carbon was achieved and the related peak was splitted to 16 peaks corresponding to a heptad level compared to 10 peaks in 20°C.
Novel polymeric surfactants and their applications in miniemulsions
Authors: Cismaru Lucretiu , Hamaide Thierry , Popa Marcel 
Published: August 2014

AbstractN-Vinyl-2-pyrrolidone (NVP) and maleic anhydride (MA) copolymers were synthesized via radical polymerization. The synthesized copolymers were grafted with methoxypolyethylene glycol (MPEG) chains of different average molecular weights (350, 550, 750 Da). The grafted copolymers were used as surfactants in the synthesis of poly(ε-caprolactone) (PCL) nanoparticles in water by solvent evaporation technique. In order to further test the synthesized surfactants, the miniemulsion polymerization of vinyl acetate was performed. Two methods of obtaining miniemulsion were employed: a sonicator and a static mixer. The synthesized surfactants performed well in both type of experiments while in the case of static mixer nanoparticles with a lower polydispersity were obtained. Droplets with a mean diameter of 250 nm were obtained when using the sonicator while the static mixer led to formation of droplets with a mean diameter of 600 nm.
Studies on thermal stability and UV-resistant performance of poly(MMA-co-M12-co-BPMA)/TiO2 composite particles
Authors: Zou Jiangpeng , Yang MingJiao , Jiang Long , Dan Yi 
Published: August 2014

AbstractIn this paper, the thermal stability and UV-resistant performance of the poly(methyl methacrylate-co-sodium sulfopropyl lauryl maleate-co-2-hydroxy-4-(3- methacryloxy-2-hydroxylpropoxy) benzophenone) /TiO2 (i.e. poly(MMA-co-M12-co- BPMA)/TiO2) composite particles were studied by means of laser diffraction particle size analyzer (LDPSA), thermogravimetric analysis (TGA), ultraviolet-visible absorption spectroscopy (UV-vis), ultraviolet-visible diffuse reflectance spectroscopy (DRS), differential scanning calorimeter (DSC) and weight loss measurements. The results indicate that the dispersion of composite particles is better than that of TiO2 particles and the thermal stability of composite particles is better than that of poly(MMA-co-M12-co-BPMA). The poly(MMA-co-M12-co- BPMA)/TiO2 composite particles could absorb more than 90% of UV light in the 210-400 nm wavelength, which was useful to enhance the UV-resistant performance of polymers (e.g. PMMA) . The Tg of polymer grafted from the surface of TiO2 did not change after UV irradiation for 500 h but that of PMMA changed a lot, the weight loss of composite particles was much lower than that of PMMA after UV irradiation, showing that the UV-resistant performance of PMMA has been enhanced by introducing the organic UV-stabilizer BPMA and the inorganic UVstabilizer titanium dioxide into the polymer chains by covalent bonding.
Synthesis and Characterization of Poly(methyl acrylate) + SiO2 Hybrids
Authors: Brostow Witold , Datashvili Tea , Hackenberg Ken P. 
Published: August 2014

AbstractPoly(methyl acrylate) (PMA) + SiO2 composites were synthesized via a sol-gel reaction. The base acrylic copolymers with a content of alkoxysilane groups were prepared by co-polymerization of methylacrylate (MA) with 3-(trimethoxysilyl) propylmethacrylate (3MPS) or vinyltrimethoxysilane (VTMS); the products were cocondensed with tetraethylorthosilicate (TEOS). The PMA + SiO2 hybrids were characterized. Thermal stability of PMA is enhanced by copolymerization with 3-MPS or VTMS and the presence of SiO2; significant weight loss occurs only above 400°C. Decomposition temperatures are higher by 20 - 25 K as compared to the initial PMA. During the sol-gel process the trimethoxysilyl groups in PMA/3MPS are transformed into a strong silica network. Two different methods of creation of hybrids were used; ESEM shows that only one of them leads to uniform distribution of silica in polymeric matrices.
Sulphonation of Expanded Polystyrene Waste Under Microwave Irradiation
Authors: Sułkowski Wiesław W. , Wolińska Agnieszka , Sułkowska Anna , Nowak Krzysztof , Bogdal Dariusz 
Published: August 2014

AbstractChemical modification of polymeric materials is one way of polymer waste management. In our study, expanded polystyrene waste (EPS), used as the reference material, was converted into polymeric flocculants by the sulphonation reaction. Thus, poly(styrenesulphonate) acids (EPSS) were obtained from EPS during the sulphonation process with sulphuric acid as the sulphonation agent and Ag2SO4 as the catalyst under both conventional heating and microwave conditions. At the termination of the process the products were precipitated in the form of sodium salts (NaEPSS) in the reaction with Na2CO3 and their characteristics were given. The influence of temperature and time of reaction on the properties of EPSS and NaEPSS was studied and compared with conventional and microwave conditions. The results showed that the sulphonation process performed under microwave irradiation allowed us to receive products with properties similar to the ones obtained under conventional conditions but the reaction time was substantially reduced from 1 and ½ hour to 15 min.
Preparation of high-yield polyaniline nanofibers via an unstirred polymerization
Authors: Lü Qiufeng , Cheng Xiansu 
Published: August 2014

AbstractPolyaniline nanofibers with high yield (93%) have been synthesized by an unstirred polymerization of aniline in aqueous acid media with ammonium persulfate as an oxidant in the absence of any template, dopant or surfactant. The morphology, structure and electrical conductivity of the nanostructural polyaniline prepared under different conditions were characterized by means of scanning electron microscopy, FTIR, UV-vis and four-probe techniques. It was found that branched network-like polyaniline nanofibers were prepared without any mechanical stirring, whereas irregular and rodlike structural polyaniline samples were obtained with mechanical stirring under the same reaction conditions. Flowerlike polyaniline microspheres of ca. 3.5 μm in outer diameter, which were constructed with nanostructural polyaniline lamellar by self-assembly process, were synthesized during the polymerization at 0 °C for 72 h. The as-synthesized HCldoped polyaniline nanofibers have good room-temperature electrical conductivity of 5.0 S/cm.
Supercritical carbon dioxide-assisted solid-phase free radical grafting of butyl acrylate onto PP
Authors: Jian Wang , Deng-Fei Wang , Wei Du , En-Guang Zou , Qun Dong 
Published: August 2014

AbstractFree radical grafting copolymerization of butyl acrylate (BA) onto polypropylene (PP) matrix was investigated using supercritical CO2 as a swelling agent and carrier solvent. The monomer BA and initiator AIBN were first dissolved in supercritical CO2, and then these small molecules were diffused into the grafting zones of PP matrix. As grafting reaction temperature (about 80 °C) was far below the melting point, PP was modified in the solid phase. The effects of different experimental conditions such as soaking time and temperature, supercritical CO2 pressure; monomer and initiator concentration; PP particle diameter; solid phase grafting reaction time and temperature on grafting percentage were studied. Fourier transform infrared spectroscopy (FTIR) results and gel content experiment prove that the monomers were indeed grafted onto PP chains. Scanning electron microscope (SEM) analysis of the grafted sample indicates that the grafting branches PBA were homogeneously distributed onto the surfaces and micropores of PP particles. Thermal gravimetric analysis (TGA) results show that the grafted samples had a higher onset thermal degradation temperature and a lower weight loss at a particular temperature than pure PP. The water contact angle of PP-g-BA decreased from 98° to 72°, indicating the polarity and hydrophilicity of PP were improved effectively. The melt flow rate (MFR) and mechanical analysis results show that the grafting sample remained its versatile physical properties though introducing the grafting BA branch chain. This is prominent when it was compared with normal solid grafting product.
A biodegradable copolymer from coupling poly(pdioxanone) with poly(ethylene succinate) via toluene-2,4- diisocyanate
Authors: Wang Xiu-Li , Chen Si-Chong , Zhang Yu-Hua , Yang Ke-Ke , Wang Yu-Zhong 
Published: August 2014

AbstractPoly(p-dioxanone) (PPDO) and poly(ethylene succinate) (PES) prepolymers were reacted together using toluene-2,4-diisocyanate (TDI) as a chain extender to produce high molecular weight of chain-extended products of PPDO and PES (PPDOES) in a suitable reaction condition. The novel biodegradable polymers were characterized by 1H-NMR, DSC, POM and WAXD. DSC measurement shows that PPDOES has only one Tg, which means that PPDO has good compatibility with PES. Beside this, the glass transition temperatures and the melting temperatures of PPDOES increased with the increase of PES content. The crystallization rate of PPDOES was slower than that of PPDO as confirmed by DSC and POM. The diffraction peaks of PPDOES appear at the same 2θ angles as that of homopolymers, suggesting that PPDO and PES segment of the chainextended products reserve their own crystallization form. The results of thermal oxidative degradation show that chain-extended products have better thermal stability than PPDO.
Poly(N-isopropylacrylamide) gel beads prepared by waterin- oil suspension polymerization for the adsorption of fluorescently tagged hepcidin
Authors: Abbate Vincenzo , Jaiash Dareen , Bansal Sukhi 
Published: August 2014

AbstractPoly(N-isopropylacrylamide) (PNIPAm) gel beads were prepared by water in oil (w/o) suspension polymerization using aqueous acetonitrile to dissolve the monomer phase, toluene or cyclohexane as the continuous phase and ethyl cellulose (EC) as the stabilizer. The beads were analyzed by FT-IR and their morphology was investigated by optical and electron microscopy. The advantages of this novel synthetic method for PNIPAm preparation include efficient polymerization and mild experimental conditions, as well as the formation of spherical and relatively uniformly sized particles. The microgels were then evaluated for their efficiency to absorb fluorescently labelled hepcidin. The beads were found to rapidly capture the target peptide from neutral aqueous solutions. Notably, bovine serum albumin (BSA) did not bind to the polymer beads at the cross-linking ratio used; therefore, size-exclusion properties may be controlled by finely tuning monomer to cross-linker ratio and/or monomer concentration during polymer design. The route could potentially be useful for diagnostic, drug delivery or peptide immobilization, as well as for the molecular imprinting of peptides and proteins.
Study of rheological behaviours of electrostatic thermoset powder coatings
Authors: Ehsani Morteza , Yousefi Ali Akbar , Yeganeh Saeed Samiei 
Published: August 2014

AbstractThe use of dynamic viscosity/time (temperature) cure curves is seen as a powerful technique to quantify formulation and resin design parameters. The behaviour of different thermoset powder coating systems, epoxy/polyester (50/50, 40/60 and 30/70) as well as the impact of the filler, the curing temperature and the frequency upon gel-time have been examined based upon the rheological measurements and compared with PE/TGIC systems. Two disparate methodologies have been utilized to determine gel-time. The behaviour of dissimilar systems bearing different formulations has been compared by means of the non-isothermal DSC test. The effects of resin percentage and the formulation on physical and mechanical properties of coating have been studied.
Release behavior of 2,4-dichlorophenoxyacetic acid herbicide using novel porous polyacrylamide hydrogels
Authors: Mahdavinia Gholam Reza , Mousavi Seyyed Bahman , Karimi Farrokh , Marandi Gholam Bagheri , Shahabivand Saleh , Harati Mohammad 
Published: August 2014

AbstractPorous polyacrylamide (PAAm) was synthesized using calcium carbonate (CCb) micro-powder and subsequent leaching process. Polymerization was carried out in a solution environment system containing methylenebis acrylamide (MBA) and acrylamide (AAm) as crosslinker and monomer, respectively. CCb micro-powders were introduced to the polymerization solution before adding initiator. Ammonium persulfate/sodium metabisulfite (APS/SMBS) were used as a redox initiator system. HCl solution was used to remove CCb powders. The effect of MBA concentration and CCB amount on the swelling of hydrogels were studied. The porous structure of hydrogels was investigated and verified using scanning electron microscopy (SEM). 2,4-Dichlorophenoxyacetic acid (2,4-D) was loaded into the hydrogels and release of this herbicide was investigated. The effect of MBA concentration and addition of CCb on the content of released herbicide was studied. Also, the study of herbicide release in a solution under various pH revealed the pH-dependency release of 2,4-D herbicide.
A feasible synthetic strategy for three-armed star poly(ester amine) via Michael addition polymerization
Authors: Yang Wei , Pan Cai-Yuan 
Published: August 2014

AbstractThree-armed star-shaped poly(ester amine) was synthesized by Michael addition polymerizations of equal molar ratio of ethylene glycol diacrylate (EGDA) and piperazine (PZ) in the presence of a small amount of multifunctional monomer, 1,3,5-triacryloylhexa-hydro-1,3,5-triazine (TT) in CHCl3. When the polymerization proceeded almost completely, the molecular weight of the polymers formed were determined by the feed molar ratio of difunctional monomer to multifunctional monomer, and the molecular weight distribution (Mw/Mn) approached the theoretical value (Mw/Mn =1+1/f). The mechanism of the polymerization was investigated by 1H NMR and Gel permeation chromatography (GPC). The monomer concentration and the molar ratio of difunctional monomers/multifunctional monomer played an important role in the polymerization.
Optimization of melting conditions for the analysis of crystallization kinetics of poly(3-hydroxybutyrate)
Authors: Di Lorenzo Maria Laura , Sajkiewicz Pawel , Gradys Arkadiusz , La Pietra Paola 
Published: August 2014

AbstractStudies of kinetics of polymer crystallization are generally performed by heating the material above the melting point, in order to erase previous thermal and mechanical history, followed by rapid cooling to the desired crystallization temperature or by cooling at a constant rate. For poly(3-hydroxybutyrate) this procedure implies some degradation of the polymer chain, which starts below the onset of melting. In this article the effects of melting conditions on the subsequent crystallization kinetics are discussed. It is shown that in order to sufficiently cancel memories of previous crystalline order of the analyzed PHB, it is necessary to bring the material at a temperature higher than 192 °C. Thermal treatments conducted at lower temperatures are not sufficient to destroy all solid aggregates, and crystallization of PHB has an anticipated onset of crystallization due to nucleation occurring via self-seeding. The chain degradation attained upon exposure at high temperatures has much lesser influence on crystallization kinetics than incomplete melting, with some effects detectable on the spherulitic morphology and on the final degree of crystallinity.
(Quaternized/betainized) amino-based amphiphilic block copolymers: quantitative composition characterization via FTIR and thermogravimetry
Authors: Bomfim João A. S. , Mincheva Rosica , Beigbeder Alexandre , Persenaire Olivier , Dubois Philippe 
Published: August 2014

AbstractThe objective of the present study is the introduction of well known and readily accessible analytical methods as FTIR, thermogravimetric (TGA) and evolved gas analysis (EGA) for quantitative determination of the degree of polymerization (DP) and degree of quaternization (DQ)/betainization (DB) of amino-based amphiphilic block copolymers. For this purpose a series of amphiphilic poly(dimethylsiloxane)-b-poly[2-{dimethylamino)ethyl methacrylate] (PDMS-b-DMAEMA) diblock copolymers with DP of the PDMAEMA-block ranging from 22 to 162 was synthesized by atom transfer radical polymerization and analyzed by 1H NMR, ATR-FTIR and TGA-co-EGA. The determined composition results have shown linear correlation between the FTIR or TGA and the 1H NMR data and equations allowing the quantitative calculation of PDMAEMA-block DP were found. The errors estimated by ATR-FTIR were less than 1.5%. Further, the PDMAEMA-block was quaternized (or betainized) with DQ (or DB) from 25 % to 100 % and analyzed by TGA-co-EGA. Again, a linear correlation between the quaternized (betainized) PDMAEMA-block mass fraction and the DQ (DB) degrees was obtained by 1H NMR.
Morphology and orientation of thin poly(3-hexylthiophene) (P3HT) films on differently silanized silicon oxide
Authors: Scavia Guido , Porzio William , Destri Silvia , Schieroni Alberto Giacometti , Bertini Fabio 
Published: August 2014

AbstractThe morphology and structure of the overlying poly(3-hexylthiophene) (P3HT) layer onto differently silanized silicon oxide has been studied by Atomic Force Microscopy (AFM) and X-Ray Diffraction (XRD) techniques. By increasing the silanizer alkyl chain length, the layer morphology evolves from a filament like to globular needle like as a consequence of the different SAM organization, while the P3HT conformation remains edge-on. For each case the effect of the annealing temperature has been studied. For all the cases a particular attention has been paid to the first thin layers close to the interface P3HT/SiOx. The effect of a polar substituent and presence of aromatic ring has been also studied.
Determination of thermorheological phase diagram of poly(propylene)/poly(ethylene-b-ethylene oxide) blends
Authors: Özen İlhan , Rustal Claude , Dirnberger Klaus , Fritz Hans-Gerhard , Eisenbach Claus Dieter 
Published: August 2014

AbstractThe phase diagram of the polypropylene (PP)/poly(ethylene-blockethylene oxide) (P(E-b-EO) blends exhibiting upper critical solution temperature (UCST) was experimentally established by using small amplitude oscillatory shear rheology, in which the binodal line was obtained by dynamic temperature ramps and the spinodal temperatures were quantitatively estimated on the basis of the theory developed by Ajji et al. The measurements were carried out in the linear viscoelastic regime in which the material functions are sensitive to phase separation.
Photosensitive poly(ether sulfone)s for thiol/ene UV curable coatings: synthesis, characterization and crosslinking
Authors: Zeng Zhi , Guan Shaowei , Zhang Haibo , Zhang Linlin , Liu Baijun , Jiang Zhenhua 
Published: August 2014

AbstractNovel photocrosslinkable poly(ether sulfone)s copolymers with allyl pendants (AS-PES) have been synthesized from 3,3’-diallyl-4,4’-dihydroxydiphenyl sulfone (DA-DHDPS), 4,4’-dihydroxydiphenyl sulfone (DHDPS) and 4,4’- dichlorophenylsulfone (DCDPS). The resulting polymers could be photocrosslinked in the presence of thiol at room temperature. The crosslinking process was monitored by “Real Time Fourier Transform Infrared Spectroscopy” (RTIR). It proves that a small amount (1.0 wt%) of the thiol crosslinker addition is sufficient to form a chemical network under UV irradiation. After UV curing, AS-PES-20 coating showed high Tg, good thermal stability and excellent resistance to the acid, salt, and alkali. Accordingly, this method could successfully provide a new approach to make rapidly photocrosslinking poly(ether sulfone) coatings without losing their good thermal properties.