bluuebunny/crossref_metadata_2025_split huggingface dataset:
Processing, rheology and structure of melt compounded PBTclay nanocomposites having different chemical composition.
Authors: Scatteia Luigi , Scarfato Paola , Acierno Domenico 
Published: August 2014

AbstractIn this study the melt flow behavior of poly(butylene terephthalate)-clay nanocomposites produced by melt compounding was investigated. Four commercial organo-modified montmorillonites, differing mainly by the organic treatment used in the modification, were employed as nanometric fillers and blended with the poly(butylene terephthalate) (PBT) at two weight percentages each (6 and 9wt%). The process was carried out using a laboratory-scale twin-screw extruder at two different extrusion rates, in order to evaluate the effect of the shear rate during the process on microstructure and flow properties. In this regard, the nanocomposite samples were submitted to morphological analyses and rheological measurements in the dynamic regime. The effect of temperature on the flow behavior of the hybrids with respect to the neat PBT matrix was also investigated. The obtained data were related to the hybrid compositions and then to the chemical affinity between polymer and clay type. All the reported results have shown a gradual transition from a pseudo-Newtonian trend towards a pseudo-solid-like flow behavior with the increase of the clay loading and the dispersion/exfoliation level of the clay particles, due to the corresponding increase of the polymer-silicate interactions that slow the relaxation times of the PBT chains. Moreover, it was also evident that for the fillers having the higher affinity towards the PBT the nano-scale dispersion benefit from higher residence times, and therefore slower extrusion rates; on the contrary, for the fillers having poor interaction with the polymer, higher shear stress, and therefore higher extrusion rates, are needed to disrupt the clay tactoids in smaller particles. In the last part of the work, in order to verify if a relationship between flow properties and degree of exfoliation does actually exist, the rheological data were also processed using a simple semi-quantitative empirical method proposed in literature. The method failed for our systems, thus underlining the insufficiency of the rheological response alone in quantifying the exfoliation degree of an organoclay in the matrix.
Synthesis and Homopolymerization of the Olefin- Derived Acrylic Monomer, 1-Methyl-1-Propyl-Hexyl Acrylate
Authors: Mange Siyabonga , Tonge Matthew P. , Sanderson Ronald D. 
Published: August 2014

AbstractThe synthesis of a new olefin-derived acrylate monomer, 1-methyl-1-propylhexyl acrylate (1-MPHA), starting from 1-pentene, is reported. 1-MPHA was found to be polymerizable to high conversion by conventional free radical means. Homopolymerization of the monomer in benzene and toluene progressed faster in toluene than in bulk. Kinetic studies show 1-MPHA to be a relatively slow reacting monomer. The homopolymer of 1-MPHA was found to be thermally stable to about 200 °C, and soft at room temperature, with a Tg of -43 °C.
Novel Thermally Stable Poly(sulfone ether ester amide)s with Improved Solubility
Authors: Mehdipour – Ataei Shahram , Babanzadeh Samal , Bahri-Laleh Naeemeh 
Published: August 2014

AbstractA three-step method was used to prepare a novel sulfone ether ester diamine. In the first step, reaction of 1,5-dihydroxy naphthalene with 4- nitrobenzoyl chloride afforded 5-hydroxy-1-naphthyl-4-nitrobenzoate (HNNB). By reduction of nitro group, an amino compound named 5-hydroxyl-1-naphthyl- 4-aminobenzoate (HNAB) was obtained. Reaction of HNAB (two moles) with bis (4-chlorophenyl) sulfone resulted in preparation of a novel sulfone ether ester diamine (SEED). Polycondensation reactions of the diamine with aromatic and aliphatic diacid chlorides led to preparation of new poly(sulfone ether ester amide)s. Conventional methods were used to characterize the structure of the monomer and polymers. Physical properties of the polymers were also studied. The polyamides were thermally stable and they showed improved solubility in dipolar aprotic solvents.
Studies on the Preparation of Telechelic Polymers by Atom Transfer Radical Polymerization and Cross Coupling Processes
Authors: Durmaz Yasemin Yüksel , Cianga Ioan , Yagci Yusuf 
Published: August 2014

AbstractCombination of Atom Transfer Radical Polymerization (ATRP) and Atom Transfer Radical Cross Coupling (ATRCC) processes as a route to prepare telechelic polymers was described. The concept is based on the activation of the dormant species at the chain ends of polystyrene (Br-PS-Br or PS-Br) prepared by ATRP and functional ATRP initiator (F-R-Br) in the absence of a monomer. Depending on the type of polystyrene used in the system, cross coupling of these active species gives α,ω-polystyrene and ω-polystyrene telechelics. Detailed investigations using a model system revealed that the efficiency of functionalization was not very high because of the self-coupling of the species derived from the polymer and functional initiator. However, the highest functionalization (Xf=0.85) was achieved by introducing a small amount of styrene in the ATRCC.
Comb-like copolymers of n-alkyl monoitaconates and styrene
Authors: Inciarte Helen , Orozco Margie , Fuenmayor Miladys , López-Carrasquero Francisco , Oliva Haydee 
Published: August 2014

AbstractRandom and block copolymers containing styrene and mono n-alkyl itaconates with n = 12, 14, 16, 18 and 22 have been prepared by free radical polymerization and nitroxide-mediated radical polymerization. The molar fraction of the mono n-alkyl itaconate in block copolymers increased with increasing size of the alkyl group in the ester substituent. A calorimetric study of all these copolymers was performed. No glass transition (Tg) was observed in the temperature range - 30ºC-120ºC for random copolymers. Melting process attributed to crystalline order in the long side chains was observed for some copolymers depending on their composition and of the monoitaconate chain side length.
Synthesis by oxidative polymerization of optically active, regioregular polythiophene from quinquethiophene monomer bearing chiral and n-dodecyl groups as substituents
Authors: Angiolini Luigi , Brazzi Alice , Grenci Valeria , Salatelli Elisabetta 
Published: August 2014

AbstractThe synthesis and characterization of an optically active quinquethiophene monomer 3,3””-didodecyl-4’,3”’-di[(S)-(+)-2-methylbutyl]- 2,2’:5’,2”:5”,2”’:5”’,2””-quinquethiophene [(S)-(+)-DDDMBQT], bearing at the C-β positions of thiophene rings both linear C12 alkyl chain and chiral, enantiomerically pure, alkyl group is described. The polymerization of [(S)-(+)-DDDMBQT] by oxidative mechanism has been optimized in terms of yield of soluble polymer with high molecular weight.The obtained polymeric derivative displays enhanced conjugation extension with respect to similar poly(3-alkylthiophene)s reported in the literature and optical activity in the spectral region related to the chromophore absorptions when in the microaggregate state, indicative of the presence of supramolecular chiral conformations.
Infrared study of the photochemical behaviour of aromatic Poly (ether urethanes)
Authors: Mendikute G. , Irusta L. , Fernández-Berridi M.J. 
Published: August 2014

AbstractPoly(ether urethanes) based on aromatic diisocyanates and poly(propylene glycol) of different molecular weight and different hard segment content have been synthesised. The extent of the photooxidation of UV exposed samples has been evaluated by FTIR spectroscopy. The results proved that both the isocyanate chemical nature and polyol molecular weight play an important role in the photooxidation behaviour of these systems.
Synthesis of azobenzene-centered (co)polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization
Authors: Liping Yu , Jian Zhu , Zhenping Cheng , Zhengbiao Zhang , Wei Zhang , Xiulin Zhu 
Published: August 2014

Abstract An azobenzene-based dithiocarbamate, 4,4'-bis[2-(carbazole-N-dithio formatyl)-2-methyl-propionatyl]-azobenzene (CDMPA), was synthesized and used as the chain transfer agent (CTA) for reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene in anisole solution. Well-defined azobenzene-centered and carbazole-ended polystyrene (PS) with well-controlled molecular weight (Mn) and narrow molecular weight distributions (Mw/Mn) was obtained. The good agreement between the theoretical molecular weight (Mn,th) and the 1H NMR determined molecular weight (Mn,NMR) indicated that most of the polymer chains contained an azo-functional center-group end-capped with the carbazole moieties, which were derived from the RAFT agent. The obtained polystyrene (PS) showed a strong ultraviolet absorption in tetrahydrofuran (THF) and emitted fluorescence after excited by UV-irradiation in N,N’-dimethyl formamide (DMF) solutions. The PS was used as the macro-RAFT agent to carry out the polymerization of methyl acrylate (MA) and N-isopropylacrylamide (NIPAAM). Triblock copolymers (PMA-b-PS-b-PMA), and pentablock copolymers (PNIPAAM-b-PMA-b-PS-b-PMA-b-PNIPAAM) were obtained, respectively. These copolymers were characterized by gel permeation chromatography (GPC), FT-IR spectroscopy and NMR spectroscopy.
The study on effective thermal conductivity of carbon foam based on fractal theory
Authors: Yong Wang , Qingqing An , Lingling Cao , Xiaojuan Si , Donghui Liu , Jianjun Chen , Yimin Wang , Kin Tak Lau 
Published: August 2014

AbstractNovel carbon foam with high thermal conductivity is prepared by thermal treating of mesophase pitch under certain temperature and pressure condition. With fractal theory, the thermal conducting property of this novel porous material is discussed. Then we deduce the area fractal dimension of carbon foam. A thermal conductivity model of carbon foam is proposed. The relationship formula of effective thermal conductivity is presented by using thermal resistance method. Through computation, the effective thermal conductivity of carbon foam is acquired. The value of model forecast is consistent with that of the actual observed for carbon foam. This method has provided the theoretical basis for better using its fine heat conduction performance.
Microencapsulation of n-hexadecane as phase change material by suspension polymerization
Authors: Yafei Ai , Yong Jin , Jing Sun , Deqing Wei 
Published: August 2014

AbstractIn this study, suspension polymerization is described to fabricate microcapsules containing n-hexadecane as phase change material. In the suspension polymerization, casein is employed as emulsifier and stabilizer instead of synthetic surfactant. Microcapsules with polystyrene as shell and n-hexadecane as core have an average diameter of 3~15μm and the size distribution are narrow. Thermal properties are investigated by differential scanning calorimetry (DSC) showing that the microcapsules can store and release an amount of latent heat over a temperature range nearing the melting point of pure n-hexadecane. The latent heat of fusion of microencapsulated n-hexadecane decreases after microencapsulation. The melting point of microencapsulated n-hexadecane is near but higher than that of pure n-hexadecane, and the polymerization time has little effect on the melting point.
The effect of attapulgite on crystallization behavior of Poly(ethylene terephthalate) (PET)/Attapulgite (AT) nano composites
Authors: Xufen Fan , Dajun Chen 
Published: August 2014

AbstractPoly (ethylene terephthalate) (PET)/Attapulgite (AT) nanocomposites were prepared via in-situ polymerization. According to the observation of transmission electron microscopy (TEM), attapulgite is well dispersed in the PET matrix in a nanometer scale. The influence of attapulgite content on the nonisothermal crystallization kinetics was studied using a classical Avrami equation with Jeziorny method. The crystalline structures of the pure PET and PET/AT nanocomposites with different amount of AT (0.2%, 0.5%, 1%, 2%) were characterized by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) methods. It was found that the crystallization temperature for PET/AT nanocomposites with 0.2% and 0.5% content of AT were higher than pure PET and the rate of crystallization of all PET/AT nanocomposite samples increased significantly which indicated that attapulgite could be used as an effective nucleating agent in PET. However, with the addition of AT, smaller crystalline size, more crystalline defects and lower degree of crystallization was demonstrated.
Comparison of the structure and thermal properties of a poly(aryl ether ketone ether ketone naphthyl ketone) with those of poly(aryl ether ketone ether ketone ketone)
Authors: Dosière Marcel , Villers Didier , Zolotukhin Mikhail G. , Koch Michel H.J. 
Published: August 2014

AbstractPoly(oxy-1,4-phenylene carbonyl-1,4-phenylene oxy-1,4-phenylene carbonyl-2,6-naphthalene carbonyl-1,4-phenylene) or 2,6-PEKEKNK is a polymer of the poly(aryl ether ketone) family differing from PEKEKK by the presence of a naphthyl group linked at positions 2 and 6 to the two ketone groups. It is synthesized by electrophilic precipitation polycondensation of 2,6- naphthalenedicarboxylic acid chloride with 4,4’-bis-(4-phenoxy) benzophenone in the presence of aluminium chloride. The dimensions of the orthorhombic unit cell determined from an initially amorphous, stretched film are: a = 0.778 nm, b = 0.613 nm, c = 5.52 nm. In contrast with PEKEKK no signs of polymorphism were found for 2,6 PEKEKNK. Its glass transition and melting temperatures are 20 °C and 2 °C above those of PEKEKK, respectively.
RAFT Polymerization of Styrene Using Dithioester with Anthracene Z Group as Chain Transfer Agent
Authors: Nianchen Zhou , Jian Zhu , Zhengbiao Zhang , Xiulin Zhu 
Published: August 2014

AbstractA novel dithioester, bearing anthracene as Z group, benzyl anthracene-10-carbodithioate (BAC) was successfully synthesized and used as the RAFT agent for the RAFT polymerizations of styrene (St). The results indicated that the polymerization presented the characteristics of “living”/controlled radical polymerization. 1H NMR characterization of obtained polystyrene confirmed that most of the polymer chains were end-capped by the anthracene moiety. The successful chain extension experiment further demonstrated the “living” character of the polymer. The fluorescence investigation of the polymers contained an anthrancene moiety of BAC in the chain end expressed enhanced fluorescence property than that of BAC in CHCl3 solution.
Structure and Mechanical Behavior of Isotactic Polypropylene Composites Filled with Silver Nanoparticles
Authors: Tjong Sie Chin , Bao Suping 
Published: August 2014

AbstractIsotactic polypropylene (PP) nanocomposites containing 0.1, 0.3, 0.5 and 1.0 wt % silver (Ag) nanoparticles were prepared via melt compounding in a twin-screw extruder followed by injection molding The effects of the Ag nanoparticle additions on the structure and mechanical behavior of PP were studied using DSC, WXRD, optical microscopy, tensile and Izod impact techniques. DSC and WXRD measurements showed that the addition of only 0.1 wt% Ag nanoparticles promote the formation of β-form PP. Further increasing Ag content would not lead to additional increase of the β-PP phase content. The induced β- form PP phase is beneficial to enhance the impact strength and tensile ductility of the PP/Ag nanocomposites.
Effect of temperature and pH on swelling behavior of hydroxyethyl cellullose-acrylamide hydrogel
Authors: Alonso Gabriel J. , Rivera José Luis A. , Mendoza Ana María M. , Mendez Maria Leonor H. 
Published: August 2014

AbstractThe swelling behavior of hydroxyethyl cellulose-acrylamide hydrogels at different pH and temperatures was studied. The absorption increased for the first 12 hours and then decreased. Several hydroxyethyl cellulose-acrylamide ratios were studied. Increasing hydroxyethyl cellulose amount decreased swelling, indicating that swelling was affected by increase in crosslinking. Three different levels of crosslinking agent were studied. Hydrogels exhibited a thermal and pH sensitive behaviour. Highest swelling capacity was found at pH 7.0 and 30 °C. All samples were characterized by means of infrared spectroscopy (FTIR). Characteristic absorbance peaks for both materials were found, showing the presence of hydroxyethyl cellulose and acrylamide on hydrogel.
Thermoresponsive hydrogels of hydrophobically modified polyglycidol
Authors: Utrata-Wesołek Alicja , Trzebicka Barbara , Dworak Andrzej , Ivanova Sijka , Christova Darinka 
Published: August 2014

AbstractSynthesis, swelling properties and thermoresponsive behavior of a new class of hydrogels based on high molar mass polyglycidol are presented. High molar mass polyglycidol was synthesized by coordination polymerization. Thermosensitive poly(glycidol-co-glycidyl ethyl carbamate)s were obtained via a simple chemical modification of the polyglycidol with ethyl isocyanate. Polyglycidol and poly(glycidol-co-glycidyl ethyl carbamate)s were chemically crosslinked in DMF solution using oligomeric poly(ethylene glycol)-bis-(carboxymethyl ether chloride) as crosslinking agent. The hydrogels of degree of swelling of over 1000% were obtained. Thermoresponsive properties of the networks and the swellingdeswelling behavior of hydrogels in response to cyclic changes of the temperature were studied.
Investigation of Poly(vinyl pyrrolidone) in methanol by dynamic light scattering and viscosity techniques
Authors: Aschi Adel , Jebari Mohamed Mondher , Gharbi Abdelhafidh 
Published: August 2014

AbstractThe behavior of poly(vinyl pyrrolidone) (PVP) in methanol was examined using several independent methods. The hydrodynamic radius (Rh) of individual samples, over a range of molecular weights (10,000-360,000), was determined using dynamic light scattering (DLS) measurements. Dynamic Light Scattering (DLS) techniques directly probe such dynamics by monitoring and analyzing the pattern of fluctuations of the light scattered from polymer molecules. Some viscosity measurements were also performed to complete the DLS measurements and to provide more information on the particle structure. The results obtained with PVP-methanol system showed that plotting the variation of intrinsic viscosity versus the logarithm of the molecular mass of this polymer, we observe one crossover point. This crossover point appears when we reach the Θ-solvent behavior and delimit two molecular mass regions. The second order least-squares regression was used as an approach and was in excellent agreement with viscometric experimental results.
Synthesis, Chemical Structure and Properties of Crosslinked Poly(esterurethanes) Based on Unsaturated Oligo(alkyleneester)diols
Authors: Jasinska Lidia , Balas Adolf , Haponiuk Jozef T. 
Published: August 2014

AbstractThe cross-linked poly(esterurethanes) (PEU) based on unsaturated oligo(alkyleneester)diol (OAE) are presented. OAE was prepared from adipic acid, maleic anhydride and ethylene glycol and then characterized by elemental analysis, FTIR, 1H NMR and 13C NMR spectroscopy in account of double bonds and -COOH end groups. The synthesis of PEU was conducted in two steps. In the first step the prepolymers, containing free NCO or OH groups, were obtained via the reaction of OAE with 4,4`-diphenylmethane diisocyanate (MDI) used in excess. The cross-linking was achieved in the next step, in which the prepolymers were dissolved in methyl methacrylate (MMA) of concentrations in the range of 30 to 50 wt% in the presence of 1 wt% of methyl ethyl peroxide and 0.003 wt% of cobalt (II) 2-ethylhexanoate. It is proved that both chemical structure and MDI content in prepolymer influence the static and dynamic mechanical properties and thermal stability of the poly(esterurethanes).
Synthesis and characterization of new macromolecule systems for colon-specific drug delivery
Authors: Galehassadi M. , Mahkam M. , Hosseinzadeh F. 
Published: August 2014

AbstractNetwork polymers containing silyl groups were synthesized. Silyl derivatives of 2-hydroxyethylmethacrylate (HEMA), and methacrylic acid (MAA) were copolymerized with 1,2-bis(vinylphenyl)ethane (BVPE) and divinylbenzene (DVB) as cross-linking agents by radical polymerization using α,α′-azobis (isobutyronitrile) (AIBN) as initiator to produce network polymers. Then mesalasine (MZ) were loaded to these network polymers, and amount of drug entrapped was determined. In vitro release studies showed that drug delivery property was modified and showed considerable difference in swelling at pH 1 and 7.4. Incorporation of silyl groups in new macromolecule system modified network polymers for drug delivery. Monomers and polymers were characterized by spectroscopic methods.
Comparative studies of functional nanostructures sputtered on polypropylene nonwovens
Authors: Wei Qufu , Yu Liangyan , Hou Dayin , Wang Yingying 
Published: August 2014

Abstract Functional nanocomposite nonwoven materials were prepared by surface coating with copper and silver using magnetron sputter coating. The composite nonwoven materials with metallic nanostructures were analyzed and compared by means of atomic force microscopy, energy dispersive X-ray analysis and electrical and optical tests. The observations by atomic force microscopy revealed the formation of functional nanostructures on the fibre surfaces. It was found that copper had more compact structures on the fiber surface than silver under the same sputtering conditions. The transmittance analysis showed that the nonwoven substrates deposited with nanostructural copper showed better ultraviolet and visible light absorption than those coated with silver. The functional nonwoven materials coated with silver had lower electrical resistance than those coated with copper.
Novel Polymerization of Myrcene in Aqueous Media via Cyclodextrin-Complexes
Authors: Choi SooWhan , Ritter Helmut 
Published: August 2014

AbstractFree radical homopolymerization with methylated β-cyclodextrin (CD) complexed myrcene (1a) and co-polymerization of 1a with diethyl fumarate (2a) and styrene (3a) were carried out using redox initiator in aqueous media at room temperature. Control experiments showed that uncomplexed myrcene (1) does not polymerize under similar conditions in water. The polymers obtained were characterized by means of 1H/13C-NMR spectroscopy, differential scanning calorimetry (DSC) and gel-permeation chromatography (GPC). Additionally, Nisopropylacrylamide containing copolymer was synthesized in water using redox initiator and the lower critical solution temperature (LCST) behaviour was studied.
Application possibilities of preparative size exclusion chromatography to analytical problems in polymer science
Authors: Thijs Hanneke M. L. , Meier Michael A. R. , Schubert Ulrich S. 
Published: August 2014

AbstractThe application possibilities of preparative size exclusion chromatography for the detailed analysis of polymer analytes are discussed. Using the example of star-shaped polymer architecture, the possibilities of utilizing fractions obtained from preparative size exclusion chromatography and their subsequent off-line characterization with a variety of hyphenated analytic techniques are discussed and compared to one another. It was, for instance, possible to obtain an absolute SEC calibration for the investigated star-shaped polymers that showed very good agreement with theoretical expected values and values obtained by absolute molecular weight determination techniques by analyzing fractions of different molecular weights of this polymer architecture by MALDI-TOFMS in order obtain the Mp values required for SEC calibrations. Moreover, the star-shaped polymers were investigated by SEC-viscometry in order to obtain their absolute molecular weight. All analytical results are compared to each other and possibilities as well as limitations are discussed.