bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molten Salt as a Green Reaction Medium: Synthesis of Polyureas Containing 4-phenylurazole Moiety in the Main Chain in the Presence of Tetrabutylammonium bromide as an Ionic Liquid
Authors: Mallakpour Shadpour , Dinari Mohammad 
Published: August 2014

AbstractIonic Liquids (IL)s have been generating increased interest over the last decade. ILs were initially introduced as an alternative green reaction media because of their unique chemical and physical properties of nonvolatility, nonflammability, thermal stability, and controlled miscibility. The step-growth polymerization reactions of 4-phenylurazole (PHU) with various diisocyanates such as hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), and toluylene-2,4-diisocyanate (TDI) were performed in the presence of tetrabutylammonium bromide (TBAB) as a reaction medium with or without dibutyltin dilurate (DBTDL) as a catalyst. The polymerization reaction gave similar results in the presence or absence of DBTDL, indicating that, the catalyst is not needed in this process. The resulting polyureas showed high yields and moderate inherent viscosities in a range of 0.23-0.29 dL/g in N,N-dimethylformamide (DMF) at 25 °C and they are soluble in most polar aprotic organic solvents. This method was compared with the polymerization reaction in conventional solvent such as, N,N-dimethylacetamide (DMAc). In the case of using TBAB, higher yields and inherent viscosities were obtained. All of the above polymers were characterized by FT-IR and thermogravimetric analysis (TGA).
Synthesis, characterization and properties of polymers containing simultaneously the imine and amide moieties.
Authors: Sánchez Christian , Bustos Carlos , Alvarado Fabiola , Schott Eduardo , Gatica Nicolas , Bernede Jean-Christian 
Published: August 2014

Abstract We present the synthesis of polymers by means of self-condensation of ethyl 3-aminophenyl acetate, using HCl as catalyst at high temperature and reduced pressure. This polymer was fractionated by successive precipitation from mixtures of methanol/diethylether of different polarity, yielding three polymeric fractions: Poly A, Poly B and Poly C. Likewise, under the same conditions, 3- aminophenyl acetic acid yields only one polymeric fraction, Poly D. These polymers were characterized by elemental analysis, IR and, in some cases, by 1H-NMR and X-Ray Photoelectron Spectroscopy (XPS). The obtained results show that polymers can be classified as hybrid materials, because in the backbone, they contain simultaneously the amide and imine groups and, at the end of the chain, they have amine and carboxylic acid functions. High solubility of some of these polymers in DMF or methanol has permitted the determination of viscosities and the preparation of films. Poly B and Poly C films exhibit amorphous morphology; and Poly D display spherullitic-type semi-crystallization pattern. The polymers can absorb solvents and they can swell up forming large-sized gels in DMF and methanol. Besides these polymers have high thermal stability that reaches a weight loss of 11.60% at 353 °C.
Gas sensing property of a conducting copolymer
Authors: Ak Metin , Yigitsoy Basak , Yagci Yusuf , Toppare Levent 
Published: August 2014

AbstractA bifunctional amido thiophene, namely hexamethylene (bis-3-thiophene acetamide) (HMTA) was synthesized and its copolymer with pyrrole was electrochemically prepared in water/PTSA solvent/electrolyte medium. Sensory behavior of this copolymer against ammonia, methanol, dichloromethane (DCM) and n-hexane vapors was investigated. The methanol vapor, which can form hydrogen bonds with the polar groups on the copolymer surface, showed the maximum response. DCM, which is less polar, yielded relatively lower response than methanol. Hexane, being the non-polar vapor, showed the lowest response.
Mechanism of sintering of polyoxymethylene powders investigated by small-angle X-ray scattering
Authors: Sixou Bruno , Jebawi Kassem Al , Seguela Roland , Vigier Gérard 
Published: August 2014

AbstractThe structural reorganization of polyoxymethylene powders during sintering has been investigated through a detailed analysis of the SAXS data in order to determine the origin of the mechanical property improvement with regard to the compression-moulded counterpart. Two approaches afford a quantitative evaluation of the structural parameter evolutions. On one hand, the correlation and interface distribution functions were calculated for the samples submitted to various thermo-mechanical treatments. On the other hand, the Hosemann’s paracrystalline model modified with Reinhold distributions of the crystal and amorphous phase thicknesses was used to evaluate the disorder in the lamella stacking. Both approaches suggest that a more perfect and regular crystalline structure with thicker and wider crystals develops in the sintered samples as compared with the parent powders and the material crystallized from the melt. Theses morphological modifications are discussed in relation to the very high stiffness and brittleness of the sintered materials. Two possible mechanisms of coalescence of the powder grains via the crystalline phase are proposed to account for these specific mechanical properties of the sintered materials.
High temperature reaction between poly(glycolic acid) and ε-caprolactone in ionic liquids
Authors: Dali Souad , Lefebvre Hervé , Gharbi Rachid El , Fradet Alain 
Published: August 2014

Abstractε-Caprolactone (CL) was reacted with PGA oligomers in ionic liquids in the presence of Ti(OBu)4, both ring-opening polymerization initiator and polyesterification catalyst. 1H and 13C NMR studies showed that the fast polymerization of CL was followed by simultaneous slow polyesterification and ester-interchange reactions leading to random PGA/CL copolyesters after 6 h reaction. The nature of the catalyst and the ionic liquid did not influence much reaction rate. Hydroxyacetyl end-groups appeared to be much less reactive than the corresponding hydroxycaproyl end-groups, which were consumed at the beginning of reaction. The 50/50 and 60/40 oxyacetyl (G)/oxycaproyl (L) (mass-%) copolyesters were amorphous, while copolyesters containing larger amounts of G units were semi-crystalline. The variations of the Tg of all copolyesters versus composition follow the Flory-Fox law.
Rheological Properties of Calcium Carbonate-Epoxidized Natural Rubber Composites Prepared In Latex State
Authors: Lohakul A. , Kaesaman A. , Rungvichaniwat A. , Nakason C. 
Published: August 2014

AbstractEpoxidized natural rubber was prepared by performic acid epoxidation. It was then blended with calcium carbonate dispersion in latex state, which was later coagulated and dried. Rheological properties in terms of Mooney viscosity and shear flow properties were determined. We found that at a given shear rate, the Mooney viscosities, shear stress and shear viscosity increased with increasing levels of epoxide groups in the ENR molecules and increasing loading levels as well as decreasing particle sizes of CaCO3. This is attributed to increased level of chemical interaction between polar functional groups in the ENR molecules with increase in the epoxide content. This gives rise to greater chemical interaction between the ENR and CaCO3 interface upon increase in amount of CaCO3. Greater surface areas of the smaller filler particles also caused higher chemical interaction between difference phases.
Copolymerization of two bromine containing methacrylate monomers with methylmethacrylate. Determination of reactivity ratios by in situ quantitative 1H NMR monitoring
Authors: Cameliu Ichim Ionut , Rusu Marius Ciprian , Rusu Mihai , Marcel Popa , Delaite Christelle , Riess Gerard 
Published: August 2014

AbstractAn important method used to make medical implants radiologically visible is based on introduction of radiopaque bromine or iodine containing methacrylic monomers. Thus, 2-(2-bromopropionyloxy) propyl methacrylate (BPPM) and 2-(2-bromoisobutyryloxy) propyl methacrylate (BIPM) were synthesized with the aim to use them as radiopaque agents. The free radical initiated copolymerization of BPPM and BIPM with methyl methacrylate (MMA) were performed directly in a thermostatic cell of the NMR spectrometer. The copolymer compositions obtained from 1H NMR spectra led to the determination of the reactivity ratios (rMMA = 1.08 ± 0.12; rBPPM = 1.01 ± 0.13 and rMMA = 0.95 ± 0.09; rBIPM = 0.95 ± 0.1). The reactivity ratios of these two monomers is similar to that of MMA suggesting that the length of the bromine containing monomers side chain does not affect significantly the reactivity of the methacrylic double bond. From the results we conclude the copolymers to have random structure.
Structure and properties of styrene-butadiene rubber/ pristine clay nanocomposites prepared by latex compounding method
Authors: Abdollahi Mahdi , Rahmatpour Ali , Aalaie Jamal , Khanli Homayon Hossein 
Published: August 2014

AbstractStyrene- butadiene rubber (SBR)/ clay nanocomposites were prepared by mixing the SBR latex with aqueous clay dispersion and co-coagulating the mixture. Tapping mode AFM and XRD were applied to characterize the structure of nanocomposites. It was found that fully exfoliated structure could be obtained by this method only when the low loading of layered silicate (< 10 phr) is used. With increasing the clay content, both non-exfoliated (stacked layers) and exfoliated structures can be observed simultaneously in the nanocomposites. The results of mechanical tests on the vulcanized pure SBR and SBR/ clay nanocomposites showed that the nanocomposites presents better mechanical properties than clayfree SBR vulcanizate. Furthermore, initial modulus, tensile strength, tensile strain at break, hardness (shore A) and tear strength increased with increasing the clay content, indicating the nanoreinforcement effect of clay on the mechanical properties of SBR/ clay nanocomposites. Compared to the clay free SBR vulcanizate, the nanocomposite vulcanizates exhibit a lower tanδ peak value, higher storage modulus and higher tanδ value at the rubbery region (0-60 °C) which indicate that the elastic responses of pure SBR towards deformation are strongly influenced by the presence of nanodisperced natural sodium montmorillonite layers especially completely exfoliated silicate layers.
Preparation of highly stable polypyrrole dispersions in the mixed aqueous solution of sodium dodecyl sulfate and polyvinyl pyrrolidone
Authors: Shuangxi Xing , Guoku Zhao 
Published: August 2014

AbstractPolypyrrole (PPy) dispersions with high stability were prepared in the mixed aqueous solution comprising an anionic surfactant (sodium dodecyl sulfate, SDS) and a polymeric stabilizer (polyvinyl pyrrolidone, PVP). By choosing proper mass ratios of the surfactant to the monomer, stable dispersions could be obtained owing to the interaction between the two components. The structure, morphology, stability, particle size, polydispersity index and conductivity of the samples obtained from different conditions were investigated. The PPy dispersions prepared from mixed aqueous solutions were much more stable than those from single component solution.
Preparation of (tri-isopropoxidesilane)-acrylate latex and the properties of its film formed in room temperature
Authors: Xi Chen , Tianying Guo , Guang jie Hao , Moudao Song , Banghua Zhang 
Published: August 2014

Abstract The vinyl (tri-isopropoxide silane)-co-methyl methacrylate-co-n-butyl acrylate-co-styrene latex was prepared by emulsion polymerization. The crosslinked structure was formed in the copolymer latex film and the crosslinking degree of the copolymer latex film increases with the increasing vinyl triisopropoxide silane content. The tensile stress and water repellent property were also strengthened, when the vinyl tri-isopropoxide silane was introduced into the copolymer latex film.
Polymer Characterization by Electrospray-Mass- Spectrometry – shifting the upper mass limit
Authors: Kehr Seda , Luftmann Heinrich 
Published: August 2014

AbstractThe described approach allows the determination of homopolymer characteristics from complex electrospray mass spectra of multicharged ions in the range of 5000 to 20000. It makes mass spectrometric characterizations possible where compounds are fragmented under MALDI conditions. The determination is accomplished by simulation of the observed complex mass spectra with an Excel based computer program (PolyCalc). The parameters molecular weight (M), reduced sum of end groups (EG), mean molecular weights and polydispersity (Mn, Mw, PDI) are obtained by recursive iteration.
Temperature-responsive hydrogels containing new LCST methacrylate macromonomers
Authors: Korytkowska-Wałach Anna , Porwoł Anna , Gibas Mirosław 
Published: August 2014

AbstractA series of hydrogels were synthesized: homopolymers of new temperature-sensitive methacrylate macromonomers of ether-ester structure, derived from monomethacrylate of tetraethylene glycol via Michael-type addition - oligo(TTEGMMA), and copolymers of oligo(TTEGMMA) with N-isopropylacrylamide (NIPAAm) or 2-hydroxyethyl methacrylate (HEMA). Hydrogels based on oligo(TTEGMMA) demonstrate broad volume phase transition. Combination of oligo(TTEGMMA) with NIPAAm or HEMA yielded hydrogels having narrower phase transition and lower gel transition temperature (LGTT) up to 43 °C at the most, which is in the range of interest for most biomedical applications.
Preparation of azobenzene-terminated polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization
Authors: Wan Xiaoming , Zhang Zhengbiao , Zhu Xiulin , Zhu Jian , Cheng Zhenping 
Published: August 2014

AbstractThree azobenzene-based dithiocarbamates, 2-(phenylazo-phenoxycarbonyl) prop-2-yl 9H-carbazole-9-carbodithioate (APCDT), 2-(4-nitro-phenylazophenoxy- carbonyl)prop-2-yl 9H-carbazole-9-carbodithioate (ANPCDT), 2-(4-cyanophenylazo- phenoxy-carbonyl)pro-2-yl 9H-carbazole-9-carbodithioate (ACPCDT), were synthesized and used as RAFT agents in the polymerizations of styrene (St) and methyl methacrylate (MMA). The results showed that APCDT, ACPCDT and ANPCDT were effective RAFT agents for the polymerization of St. In the case of MMA, the polymerization showed hybrid behavior. The different substitutes on azobenzene moiety in dithiocarbamates did not show obvious influence on the controllability of the polymerizations. The UV and fluorescence spectra of RAFT agents and obtained azobenzene-terminated polymers were investigated
Synthesis of poly(methyl methacrylate)-b-poly(acrylic acid) by DPE method
Authors: Chen Dong , Liu Ruixue , Fu Zhifeng , Shi Yan 
Published: August 2014

AbstractAmphiphilic diblock copolymer poly(methyl methacrylate)-b-poly(acrylic acid) (PMMA-b-PAA) was prepared by 1,1-diphenylethene (DPE) method. Firstly, free radical polymerization of methyl methacrylate was carried out with AIBN as initiator in the presence of DPE, giving a DPE-containing PMMA precursor with controlled molecular weight. tert-Butyl acrylate (tBA) was then polymerized in the presence of the PMMA precursor, and PMMA-b-PtBA diblock copolymer with controlled molecular weight was prepared. Finally, amphiphilic diblock copolymer PMMA-b-PAA was obtained by hydrolysis of PMMA-b-PtBA. The formation of PMMA-b-PAA was confirmed by 1H NMR spectrum and gel permeation chromatography. Transmission electron microscopy and dynamic light scattering were used to detect the self-assembly behavior of the amphiphilic diblock polymers in methanol.
Chitosan based antimicrobial films for food packaging applications
Authors: Tripathi Shipra , Mehrotra G. K. , Dutta P. K. 
Published: August 2014

AbstractAntimicrobial packaging is one of the most promising active packaging systems. Antimicrobial packaging is the packaging system that is able to kill or inhibit spoilage and pathogenic microorganisms that are contaminating foods. A tremendous effort has been made over the last decade to develop and test films with antimicrobial properties to improve food safety and shelf life. For food preservation, chitosan films are very effective. Chitosan has widely been used in antimicrobial films, to provide edible protective coating, dipping and spraying for the food products due to its antimicrobial properties. Chitosan can be formed into fibers, films, gels, sponges, beads or nanoparticles. Chitosan films have been used as a packaging material for the quality preservation of a variety of food. Chitosan has great potential for a wide range of applications due to its biodegradability, biocompatibility, antimicrobial activity, non-toxicity and versatile chemical and physical properties. The present review outlines the preparation and antimicrobial activity of chitosan based films.
Bovine serum albumin imprinted calcium phosphate /polyacrylate/alginate multi-hybrid polymer microspheres in inverse-phase suspension
Authors: Zhao Kong Yin , Kan Bo Hong , Wei Jun Fu , Cheng Guo Xiang , Chen Li 
Published: August 2014

AbstractMacromolecularly imprinted calcium phosphate/polyacrylate/alginate (CP/PA/A) multi-hybrid polymer microspheres with the surface and embedded imprinting of bovine serum albumin were prepared with sodium alginate (SA), (NH4)2HPO4 and sodium polyacrylate (SPA) by using CaCl2 as gelling agent in inverse-phase suspension. Infrared spectrum analysis demonstrated that multihybrid components were produced in the microspheres. Rebinding dynamic of both imprinted microspheres proved a higher BSA rebinding relative to those nonimprinted ones. The specific surface area of CP/PA/A microspheres increased when compared with non-imprinted ones. The specific rebinding peak and imprinting efficiency cross point have appeared in rebinding dynamic curves, which showed remarkable difference in rebinding behaviours between surface and embedding imprinted microspheres.
Second Order Nonlinear Optical Properties of Multifunctional Chiral Azobenzene Polymers
Authors: Angiolini Luigi , Benelli Tiziana , Bozio Renato , Cozzuol Matteo , Giorgini Loris , Pedron Danilo , Salatelli Elisabetta 
Published: August 2014

AbstractCorona poling behaviours of optically active photochromic copolymers derived from methyl methacrylate (MMA) and the methacrylic ester of (S)-3- hydroxy pyrrolidine linked through the nitrogen atom to the highly conjugated photochromic 4'-(β-cyano-β-(methylsulfonyl)vinyl)-4-azobenzene moiety, have been investigated with the aim to evaluate the effect on the non-linear optical (NLO) properties originated by the presence of inactive side-chain MMA groups along the main chain. The NLO properties of in situ corona poled polymeric films have been studied by second harmonic generation (SHG) measurements. The d33 values of the investigated polymers were determined to be in the range 10-86 pm/V after corona poling. The temporal and thermal stability of the optimal SHG signals obtained after corona poling process of all the macromolecular materials has been investigated and compared. The results indicate that the maximum of these properties can be obtained at a molar content of photochromic units around 20- 40%.
Novel blocked mercaptosilane (3-propionylthio-1- propyltrimethoxylsilane) for natural rubber/silica composite reinforcement in various curing systems
Authors: Peng Hualong , Liu Lan , Luo Yuanfang , Jia Demin , Fu Weiwen 
Published: August 2014

AbstractIn present work, the effect of novel blocked mercaptosilane(3- propionylthio-1-propyltrimethoxylsilane) (called hereafter PXT) on structure and dynamic mechanical properties of natural rubber/silica (NR/silica) composites was studied in efficient, semi-efficient and conventional vulcanization systems. Equilibrium swelling method investigation indicates that PXT is able to enhance crosslinking density of composites. The investigation of properties shows that PXT can strengthen the reinforcement of silica for NR vulcanizates and substantially enhance the resistance to flex cracking and abrasion of NR/silica composites. Since PXT possess two functionally active end groups which can chemically react with both silica and rubber, at 2 phr of the PXT content, NR/silica composites possess optimum comprehensive dynamic mechanical properties.
Fine structure and physical properties of poly(butylene terephthalate) sheets prepared by roll drawing
Authors: Lee Sunhee , Nakayama Kazuo , Cho Hyunhok 
Published: August 2014

AbstractPBT sheets were extruded from T-die using a single extruder and were winded by a take-up roller controlled at 50°C and with speed at 1.2 m/min. Oriented PBT sheets were prepared with various winding roll speeds at 3.6, 4.8 and 6.0 m/min. Fine structure and physical properties of PBT sheets thus obtained were investigated by measuring the molecular orientation, crystal structure, dynamic visco-elasticity, thermal and mechanical properties, sonic modulus, etc. PBT melts were found to be readily crystallizable in the sheet. In the case of roll drawing, the DRmax of PBT sheet was 5. The PBT sheets prepared from winding speed at 6 m/min showed polymorphism of both α- and β-form crystallites with crystallinity of about 24%. In the tri-directional WAXD patterns, the PBT sheets by the roll drawing method turned out to be oriented in the uniplanar-axial form. For the roll drawn PBT sheets with various winding speeds, large orientation effects were observed in the winding direction together with improved thermal and mechanical properties.
Cerium oxide hollow nanospheres prepared by polymermonomer self-assembly
Authors: Gao Yongyi , Ding Xiaobin , Zheng Zhaohui , Peng Yuxing 
Published: August 2014

AbstractIn this paper, cerium oxide hollow nanospheres have been prepared via a polymer-monomer self-assembly route; it may be possible to extend this approach to fabricate other metal oxide hollow nanospheres. In this method, cerium oxide hollow nanospheres were fabricated by calcining hollow polymer spheres which were prepared via addition of ceric ammonium nitrate (CAN) into self-assembled micelles which were prepared through dissolving chitosan (CS) in methacrylic acid (MAA) solution.
Polymer-silica hybrids latexes dyed with Rhodamine B
Authors: Nistor Cristina Lavinia , Donescu Dan , Purcar Violeta , Petcu Cristian , Serban Sever , Ghiurea Marius , Corobea Mihai Cosmin 
Published: August 2014

AbstractSynthesis of latexes based on polystyrene (PSt) and polybutylacrylate (PBuA) dyed with Rhodamine B (RhB), by polymerization in ternary microemulsions, is discussed in this paper. Silica was generated through the solgel process of methacryloxypropyl-trimethoxysilane (MPTS) and glycidyloxypropyltrimethoxysilane (GMPS). MPTS copolymerizes, through its double bounds, with St or BuA. GMPS can form covalent bonds with RhB by opening of the oxyranic cycle. The smallest average diameter of the particles was obtained for latexes prepared with MPTS+GMPS couple. Latexes with RhB prepared in the presence of an organophilic layered silicate (Cloisite 20 A) were used for comparing the influence of the inorganic fillers on microemulsion properties. By St and BuA copolymerization with MPTS hybrids which can react by sol-gel process with GMPS, a coupling agent for RhB, were prepared. By using RhB as molecular sample, polarity modifications for polymer-inorganic latexes were put in evidence.
Fabrication and electrical conducting behavior of carbon nanofiber reinforced high-density polyethylene/ polystyrene nanocomposites with low percolation threshold
Authors: Liang Guodong , Bao Suping , Tjong Sie Chin 
Published: August 2014

AbstractTernary high-density polyethylene/polystyrene/carbon nanofiber nano composites were fabricated by melt-compounding. The effect of melt compounding sequences on electrical conducting behavior of such composites was examined. Two compounding sequences were adopted in this study. Route I consisted of an initial melt mixing of HDPE and PS, followed by blending with CNFs. Route II involved an initial formation of the PS/CNF master batch, followed by blending with HDPE. The results showed that CNFs were dispersed in HDPE phase of Route I prepared HDPE/PS/CNF nanocomposites whilst they resided in PS phase of Route II formed nanocomposites. Electrical measurement showed that Route II prepared nanocomposites had a low percolation concentration of 1.1 vol% CNF.