bluuebunny/crossref_metadata_2025_split huggingface dataset:
A novel hyperbranched polyester based on 2,2-bis(hydro xylmethyl)butyric acid: synthesis and characterization
Authors: Soccio Michelina , Finelli Lara , Lotti Nadia , Marchese Paola , Siracusa Valentina , Munari Andrea 
Published: August 2014

AbstractA novel hyperbranched polyester was synthesized in bulk from 2,2- bis(hydroxymethyl)butyric acid and two different core molecules (1,1,1-tris- (hydroxylmethyl)propane and 1,3,5-tris(2-hydroxyethyl)cyanuric acid), using ptoluensolfonic acid, scandium trifluoromethanesulfonate, titanium tetrabutoxide and dibutyltin oxide as catalysts and varied reaction temperature and time. At room temperature the samples obtained appeared as glassy, slightly yellow solids, with Mn (calculated by 1H-NMR spectra) in the range 500 - 2000. The degree of branching of the polyesters was determined by 13C-NMR spectroscopy and was found in the range 0.32 - 0.53. The introduction of the monomer in various steps seems to influence slightly the degree of branching, but has no effect on the molecular weight of these polymers. The polyesters exhibited a good thermal stability, as revealed by TGA technique, and the glass transition temperature, determined by DSC, was found to depend on the molecular weight and the kind of catalyst employed.
Synthesis and photophysical properties of fluorescent polystyrene containing 1,8-naphthalimide via atom transfer polymerization
Authors: Zhengneng Jin , Jianmei Lu , Qingfeng Xu , Lihua Wang , Xuewei Xia 
Published: August 2014

AbstractFluorescent polystyrene was synthesized by Atom transfer polymerization with a novel 1,8-naphthalimide derivative as initiator. The optical characteristics of initiator and obtained polystyrene in DMF solution are discussed. Results indicate that both initiator and polystyrene can emit intensive green luminescence at 520 nm, but the polymer has a higher quantum yield and energy yield.
Performance Improvement of Nano-silica/Polypropylene Composites through in-situ Graft Modification of Nanoparticles during Melt Compounding
Authors: Zhou Tong Hui , Ruan Wen Hong , Wang Yue Lin , Mai Yu Liang , Rong Min Zhi , Zhang Ming Qiu 
Published: August 2014

AbstractTo prepare inorganic nanoparticles filled polymer composites, reactive monomer was added to the ingredients prior to manufacturing. The results showed that in-situ graft polymerization of butyl acrylate onto nano-silica occurred during melt compounding with polypropylene matrix. As a result, dispersion of the grafted nanoparticles in the polymer became much more homogeneous than in the case of untreated version, and filler/matrix interaction was enhanced due to the intimate adhesion among the components. Both tensile performance and impact toughness of the composites were improved at rather low filler loading. Compared to the twostep approach developed in our lab, by which nanoparticles are treated by graft polymerization firstly and then mixed with polymer melt, the current one-step method is simpler and able to provide the composites with much higher notched impact resistance.
Synthesis of cationic flocculants based on acrylamide and [2-(acryloyloxy)ethyl]trimethylammonium chloride copolymers by semicontinuous inverse microemulsion polymerization. Part III: influence of HLB and surfactant blend concentration on flocculating performance
Authors: Río Francisca , José R. , Ochoa G. , Sasia Pedro M. , Escudero Francisco J. , Díaz de Apodaca Elena , Nieto Javier , Katime Issa 
Published: August 2014

AbstractThe influence of HLB (hydrophilic-lipophilic balance) and surfactant blend concentration (SBC) on flocculating performance of latex particles of acrylamide and [2-(acryloyloxy)ethyl]trimethylammonium chloride copolymers with a cationic charge density of 40%, obtained by inverse microemulsion copolymerization by using a surfactant blend of Arlacel 83 and Softanol 90 as emulsifier and Rolling M-245, a mixture of n-decane and n-tetradecane in about 40/60 weight ratio, as oil phase, has been studied for a total comonomer concentration of 32.5% (w/w). Comonomer inverse microemulsion copolymerizations were carried out in the semicontinuous mode by adding continuously an aqueous solution of sodium metabisulfite (SMB) as initiator into stirred inverse comonomer microemulsions. From 7.75 to 8.26, HLB has a strong influence on average molar mass (Mw) and flocculating performance (FP), the higher the HLB the higher the FP. A small decrease in SBC causes a dramatic increase in Mw and a decrease in FP although the influence on copolymer viscosity is small. Results are explained in terms of copolymer structuring degree and collapsed state of copolymer chains inside latex particles as well as in terms of the observed composition drift with conversion.
Bioactive cellulose fibres with silver nanoparticles
Authors: Kulpinski Piotr 
Published: August 2014

AbstractCellulose fibres were prepared from N-methylmorpholine-N-oxide (NMMO) as a direct solvent. The specific chemical properties of NMMO allow in-situ silver particles to be generated during the process of cellulose dissolution. The fibres obtained contained 0.005% (50 ppm) to 3% w/w of silver. The SEM images showed that the silver particles size is in the range between 30 and 330 nm. The antibacterial properties of the cellulose fibres obtained showed their high bioactivity against E. coli and S. aureus bacteria. The mechanical properties, the size of silver crystallites and SEM images of the fibres obtained were examined.
The study of synthesis of poly(ethylene oxide)-b-poly(N,Ndimethylacrylamide) by atom transfer radical polymerization and self-assembly in selective solvents
Authors: Runmiao Yang , Ronghua Shi , Dan Zhou , Yanmei Wang , Yanchun Han 
Published: August 2014

AbstractPoly(ethylene oxide)-b-poly(N, N-dimethylacrylamide) (PEO-b-PDMA) was synthesized by successive atom transfer radical polymerization (ATRP) of N,N-dimethylacrylamide (DMA) monomer using PEO-Br macro initiators as initiator, CuBr and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazamacrocyclotetra decane (Me6[14]aneN4) as catalyst and ligand.PEO-Br macroinitiator was synthesized by esterification of PEO with 2-bromoisobutyryl bromide. GPC and 1H NMR studies show that the plot of ln([DMA]0/[DMA]) against the reaction time is linear, and the molecular weight of the resulting PDMA increased linearly with the conversion. Within 3 h, the polymerization can reach almost 60% of conversion. PEO-b-PDMA copolymer with low polydispersity index (Mw/Mn≈1.1) is obtained. Self-assembly of PEO-b-PDMA in selective solvents is also studied. It could self-assemble into micelles in methanol/acetone (1/10, v/v) solution. TEM analyses of the PEO-b- PDMA micelles with narrow size distribution revealed that their size and shape depend much on the copolymer composition.
Swelling of iota-carrageenan gels prepared with various CaCl2 content: A fluorescence study
Authors: Tarı Özlem , Pekcan Önder 
Published: August 2014

AbstractIota carrageenan gels prepared with various CaCl2 content were completely dried and then swelled in water vapor. Steady-state fluorescence (SSF) technique was used to monitor the swelling process of each iota carrageenan gels at various temperatures. Pyranine was used as a fluorescence probe. Apparent fluorescence intensity, I increased as swelling time increased for all gel samples. The increase in I was modelled using Li-Tanaka equation from which the swelling time constants, τ1 and cooperative diffusion coefficients, Dc were determined. It was observed that Dc increased as the swelling temperature was increased. On the other hand at each temperature, it was seen that Dc decreased as CaCl2 content was increased. Activation energies for swelling were obtained and found to be 60.5, 61.0, 61.5 and 62.8 kJmol-1 for the gels prepared with increasing amount of CaCl2 content.
Synthesis and characterization of some composites with bioactive properties on the basis of vinyl ester resins
Authors: Rosu Dan , Cascaval Constantin N. , Rosu Liliana 
Published: August 2014

AbstractVinyl ester resins are unsaturated polyesters, widely used as matrix for high performance composite materials. The paper presents the synthesis and characterization of some vinyl ester resin/hydroxyapatite bioactive compositions using an unsaturated copolyester based on turpentine oil as reactive diluent. The vinyl ester oligomer /unsaturated copolyester/hydroxyapatite structural complex was characterized from the morphological point of view, water absorbtion, density measurements and volume contraction. The water uptake is dependent on the concentration in vinyl ester resin. The increase of the vinyl ester resin content in the bioactive composite leads to the increase of the density, respectively to a significant decrease of the volume contraction
Rheological studies of uncured epoxy–organoclay nanocomposite coatings
Authors: Zaarei Davood , Sarabi Ali Asghar , Sharif Farhad , Kassiriha Seyed Mahmoud , Gudarzi Mohsen Moazzami 
Published: August 2014

AbstractWe investigated the influence of loading two different types of organoclay on the linear viscoelastic properties of an uncured epoxy nanocomposite coating. Meanwhile, the effect of sonication in the dispersion process on the characteristics of nanocomposite has been studied. To achieve fully dispersed structures of clay-epoxy, we applied high shear mixing and high-intensity ultrasound during the synthesis of clay-epoxy nanocomposites.The flow properties of the compositions with clay loadings more than 4 wt% of low CEC quaternary ammonium modified clay, as analyzed by rheomechanical spectroscopy (RMS), showed a solid-like behavior. While the neat resin system exhibited Newtonian flow, some nanodispersed coatings exhibited pseudo plastic flow behavior, typical of polymeric fluids such as gels and pastes. With varying the type of the clay the resultant coatings exhibited a storage modulus ranging from 0.01 to over 400 Pa and a loss modulus ranging from 4 to over 200 Pa. Moreover, the complex viscosity was ranging from 12 to 1100 Pas as the clay loading increased from 0 to 8wt %. The strong increase in modulus of one type of the clays was due to the mainly intercalated and dispersed silicate platelets. The increase rate in storage modulus of these compositions decreased at higher organoclay loadings and was not linear. These results can lead to the prediction of film formation properties and application conditions of these nanocomposite coatings
Assessment of protective effect of polycation on plasmid DNA attached on the metal surface by SPR
Authors: Bao Junbo , Song Cunxian 
Published: August 2014

AbstractSurface modification of the metal is a critical procedure for gene therapy on the metal implants, such as stent and artificial joint. Polycations can condense with DNA by self-assembly, form polyplexes spontaneously as a result of electrostatic interactions and protect DNA from degradation by DNase. The ability of chitosan, polyethyleneimine (PEI), and poly(amidoamine) (PAMAM) dendrimers to condense plasmid DNA(pDNA) was determined by electrophoresis, X-ray photoelectron spectroscopy (XPS) and surface plasmon resonance (SPR). Polycation’s attachment of pDNA to the metal surface was confirmed by XPS which showed no phosphorus peaks on the interface showing the protective effect on pDNA from DNase degradation. Polycations with higher molecular weight or hyperbranched or dendrimer structures can fulfill many of the requirements for effective gene protection from DNase degradation. Chitosan with higher molecular weight (>= 200 kDa) has superior efficiency to protect pDNA against DNase degradation on the surface of the gold chip. Hyperbranched PEIs and PAMAM dendrimers, even with lower molecular weight (for example, 20kDa for PEI, 50kDa for G5) can protect pDNA against DNase degradation. The results of this study present a platform for further optimization studies of polycation-based gene delivery systems.
Thermomechanical behavior of nanoclay filled TPU/PP blends
Authors: Kannan M. , Bhagawan S.S. , Joseph Kuruvilla , Thomas Sabu 
Published: August 2014

AbstractBoth ester- and ether- based thermoplastic polyurethane (TPU) nanocomposites were prepared by melt blending, using 3 wt % Cloisite 10A (organically modified montmorillonite clay) as the nanoscale reinforcement. The nanocomposites were subsequently melt-blended with polypropylene (PP) using maleic anhydride grafted polypropylene (MA-g-PP) as a compatibilizer (in the ratio of 70/30- TPU nano/PP, 70/25/5-TPU nano/PP/MA-g-PP). Besides giving substantial increase in modulus, tensile strength and other properties organoclay reinforcement functions as a surface modifier for TPU hard segment. X-ray diffraction studies revealed that compatibilization is further improved by introducing functionalized PP (MA-g-PP) in the organoclay containing blends. The blend system was evaluated by DSC, DMA, SEM, mechanical properties and Xray diffraction. The results indicate that the ester- TPU exhibited greater miscibility than ether-TPU. Abrasion resistance and water absorption were also better for compatibilised ester- TPU blends as compared to the ether-TPU materials.
Improving the biocompatibility of poly(ε-caprolactone) by surface Immobilization of chitosan and heparin
Authors: Zhong Wei , Liu Zongjun , Tomasik Piotr , Jin Huigen , Lv Nianjian , Meng Sheng , Guo Zhang , Wu Lingxiang 
Published: August 2014

AbstractOppositely charged natural polyelectrolyte Heparin (HS) and chitosan (CS) were immobilized on the surface of poly(ε-caprolactone) (PCL) by a layer-bylayer (LBL) self-assembly procedure. Positively charged poly(allylamine hydrochloride) (PAH) was used as the first layer onto the surface of PCL. Then negatively charged HS and positively charged CS were deposited in a LBL assembly manner. The effect of this surface modification method was evaluated by ATR-FTIR spectroscopy and static contact angle measurements. The anticoagulant activity of modified PCL was evaluated using full human blood. The modified PCL samples showed prolonged activated partial thromboplastin time (APTT), prothrombin time (PT) and thromboplastin time (TT) compared with neat PCL. Scanning electron microscopy (SEM) indicated that adhered platelets retained their natural, round morphology on the modified PCL surface. The cytocompatibility of the HS/CS surface modified PCL sample was evaluated with pig iliac arteries endothelial cells (PIECs). The proliferation of the cells cultured on modified PCL films was better than those on neat PCL films.
Use of 4-vinylpyridine and 2-hydroxyethylmethacrylate monomer mixture grafted poly(ethylene terephthalate) fibers for removal of congo red from aqueous solution
Authors: Arslan Metin , Yiğitoğlu Mustafa 
Published: August 2014

AbstractIn this study, a novel fibrous adsorbent made by grafting 4-vinyl pyridine (4-VP) and 2-hydroxyethylmethacrylate (HEMA) monomer mixture onto poly(ethylene terephthalate) (PET) fibers was used for removal of Congo red (CR) in aqueous solutions by a batch equilibration technique. The influence of treatment time, pH of solution, dyes concentration, and reaction temperature on adsorbed amount was investigated. Adsorption time of 60 min. was found sufficient to reach adsorption equilibrium for CR. It was found that the adsorption isotherm of CR fits to Langmuir type isotherms. The highest adsorption capacity was found to be 11.87 mg CR per gram adsorbent. The adsorption rate of CR is much higher on the comonomers grafted PET fibers than on the ungrafted PET fibers. CR was removed 97 % when the initial dye concentration was 5 mg L-1 and 38% at 150 mg L-1 by monomers mixture grafted PET fibers. The adsorption of the dye was endothermic in nature (ΔH°=45.3 KJmol-1). It was found that the reactive fibers are stable and regenerate by acid without losing its activity.
Effect of internal electron donor on copolymerization of ethylene and 1-hexene catalyzed by supported Ziegler- Natta catalysts
Authors: Fan Zhiqiang , Zhang Letian , Fu Zhisheng 
Published: August 2014

AbstractThe four kinds of TiCl4/MgCl2 type supported Ziegler-Natta catalysts, Cat-1, Cat-2, Cat-3 and Cat-4, were prepared by reaction of MgCl2-ethanol adduct with TiCl4. Cat-1 contains no internal electron donor (ID), Cat-2 contains diethyl phthalate (DEP) as ID, Cat-3 contains anisole as ID, and Cat-4 contains both DEP and anisole as ID. Ethylene copolymerizations with 1-hexene by these catalysts were compared. Influences of the internal electron donor on catalyst activity, copolymer composition, composition distribution, molecular weight and molecular weight distribution were investigated. Cat-3 showed the largest ability of incorporating 1-hexene into copolymer chains among the four catalysts. Each copolymer sample was fractionated into two fractions: fraction soluble in boiling nheptane (HS) and fraction insoluble in boiling n-heptane (HI). 1-Hexene content of the HS fraction is 6~10 times of that in the HI fractions. Amount of the HS fraction of copolymer by Cat-2 and Cat-4 was much lower than that of Cat-1 and Cat-3. Introduction of internal donor to the catalysts, especially diethyl phthalate (DEP), increased the blockiness of HI fractions. The molecular weight of both fractions increased when there is ID in the catalyst. Addition of anisole reduced the difference in molecular weight between HS fraction and HI fraction, but addition of PA enlarged the difference. The results are discussed based on a mechanistic model of MgCl2-supported Ziegler-Natta catalysts.
Novel conductive polymer composites based on poly(butylene terephtalate) filled with carbon fibers
Authors: Bardash Liubov , Boiteux Gisèle , Seytre Gérard , Hakme Chady , Dargère Nicolas , Rybak Andrzej , Melis Flavien 
Published: August 2014

AbstractPoly(butylene terephthalate) (cPBT) synthesized from cyclic Butylene Terephthalate oligomers (CBT) was used as a matrix for carbon fibre (CF) conducting polymer composites (CPC). DSC, rheological studies and measurements of torque of CBT/CF were performed in order to optimise the processing conditions of CPC. DC and AC measurements were carried out for these composites and have shown a low percolation threshold for cPBT/CF.
Synthesis of new polyimides with 1,2,3-triazole units
Authors: Gaina Constantin , Gaina Viorica 
Published: August 2014

AbstractNew polyimides with 1,2,3-triazole units were prepared by click reaction of α,α’-bis(azidosuccinimide)s with bispropargyl monomers or AB-monomers containing azide and propargyl groups. The α,α’-bis(azidosuccinimide)s were obtained by the addition of hydrazoic acid to bismaleimide monomers. The structure of monomers and polymers was confirmed by FTIR and 1H-NMR spectroscopy and all synthesized compounds were characterized through thermal methods.
Stabilization effect of polypyrrole in ϒ-irradiated low density polyethylene
Authors: Zaharescu Traian , Jipa Silviu 
Published: August 2014

AbstractUnder the degradative action of γ-rays, low density polyethylene (LDPE) blended with 5% polypyrrole (PPy) was oxidized extra slow than the neat polymer. FTIR and UV-Viz spectroscopy’s were used for the assessment of the accumulation of oxygen-containing products. The transmittance recorded for LDPE at characteristic bands was higher than similar features obtained for LDPE/PPy samples. The protective action of PPy against oxidative ageing of polymer substrate is due to the movable proton belonging to pyrrole ring. A protection mechanism scheme is proposed for antioxidant activity of polypyrrole
Residual stresses determination in injection molded virgin and recycled HDPE blends: mechanical properties and morphology
Authors: Altan Mirigul , Yurci Mehmet Emin , Nugay Nihan 
Published: August 2014

AbstractAn experimental study of residual thermal stresses has been carried out in injection molded virgin and recycled high density polyethylene (HDPE) blends. Effects of blend concentrations on residual stresses were investigated under different injection conditions such as melt temperature, mold temperature and cooling time. Layer removal technique was used for measuring residual stresses. In order to determine the relation between the residual stresses and material characteristic of HDPE blends, mechanical and morphological properties of the blends were also investigated. Elastic modulus and impact strength were important key factors for determining the blend characteristics. As a result, it was found that HDPE blends gave higher residual stresses but lower impact strength with higher elastic modulus when recycled concentration was increased. Furthermore, it was seen that shape and size of the crystallites were also effective on residual stresses. Small and spherulitic crystallite structured blends such as 30 % recycled HDPE induced reduction in residual stresses due to easier relaxation with lower elastic modulus and higher impact strength while lamellar crystallite structured blends such as 50 % recycled HDPE gave higher elastic modulus but lower impact strength with higher residual stresses.
Synthesis and characterization of triphenylamine and Bbis(indolyl)methane center-functionalized polymer via reversible addition-fragmentation chain transfer polymerization
Authors: Xu Jie , Shang Wei , Zhu Jian , Cheng Zhenping , Zhou Nianchen , Zhu Xiulin 
Published: August 2014

AbstractA novel bis-functional reversible addition-fragmentation chain transfer (RAFT) agent bearing triphenylamine (TPA) and bis(indolyl)methane (BIM) groups, {4-[bis(1-carbodithioic acid benzyl ester-indol-3-yl)methyl]phenyl}diphenylamine (BCIMPDPA), was synthesized and successfully used as the RAFT agent to mediate the polymerization of styrene (St). The polymerization results showed that reversible addition-fragmentation chain transfer (RAFT) polymerization of St could be well controlled. The kinetic plot showed it was of first order and the numberaverage molecular weight (Mn(GPC)) of the polymer measured by GPC increased linearly with monomer conversion, simultaneously, the molecular weight distribution of the polymer was also relatively narrow. In addition, the existence of the TPA and BIM groups in the middle of polymer chain was confirmed by chain extension reaction and 1H NMR spectrum. The optical properties of the functionalized polystyrene (PS) in chloroform solution were also investigated. Furthermore, the redox process of the RAFT agent and the functionalized PS were studied by cyclic voltammetry method.
Synthesis and RGD peptide modification of poly{(lactic acid)-co-[(glycolic acid )-alt-(L-lysine)]}
Authors: Yan Qiongjiao , Li Juan , Li Shipu , Yin Yixia , Zhang Ping 
Published: August 2014

AbstractA new polymer poly{(lactic acid)-co-[(glycolic acid)-alt-(L-lysine)]} (poly[LA-co-(Glc-alt-Lys)]) was synthesized and modified with a cell adhesion peptide, Gly-Arg-Gly-Asp-Tyr (GRGDY, abbreviated as RGD). The process for preparing poly[LA-co-(Glc-alt-Lys)]/RGD involved four steps: Firstly, (3S)-3-[4- (benzyloxycarbonylamino)butyl]morpholine-2,5-dione (BMD) was synthesized by bromoacetyl bromide and Nε-(benzyloxycarbonyl)-L-lysine [L-Lys(Z)]. Secondly, poly{(lactic acid)-co-[(glycolic acid)-alt-(Nεn-benzyloxycarbonyl-L-lysine)]} (poly{LAco-[ Glc-alt-Lys(z)]}) was obtained by copolymerization of D,L-lactide and BMD. Then, poly[LA-co-(Glc-alt-Lys)] was synthesized by catalytic hydrogenation of poly{LA-co-[Glc-alt-Lys(z)]}. Finally, poly[LA-co-(Glc-alt-Lys)] was modified with RGD peptide in the presence of 1,1́-carbonyldiimidazole (CDI). The structures of poly[LA-co-(Glc-alt-Lys)]/RGD and its precursors were characterized by FT-IR, 1H NMR, 13C NMR, MS, gel permeation chromatography (GPC), amino acid analysis(AAA). RSC96 cells were used to evaluate the cell affinity of the poly[LAco-( Glc-alt-Lys)]/RGD films and poly(D,L-lactide) (PDLLA ) films. The results of cell culture showed that poly[LA-co-(Glc-alt-Lys)]/RGD was more beneficial to cell adherence and growth than PDLLA.