bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of novel β-cyclodextrin cored poly(α-caprolactone)s by anionic ring opening polymerization
Authors: Guo Yingzhi , Yu Changjiang , Gu Zhongwei 
Published: August 2014

Abstract By anionic ring opening polymerization initiated by cyclodextrin oxyanions generated from NaH and β-cyclodextrin(β-CD), novel biodegradable β- CD cored star-shaped poly(ε-caprolactone)s (s-PCLs) were synthesized and then characterized by means of FTIR, GPC, 1H-NMR. The effects of different feed molar ratios of NaH and β-CD on arm number and on the molecular weight of s-PCLs, and the relationship between the polymerization time and monomer conversion were investigated. Moreover, the physical properties of linear PCL (l-PCL) and s- PCLs with similar molecular weights but different arm number were studied and compared by DSC, SEM and intrinsic viscosity measurement, respectively. It was found that the feed molar ratio of NaH and β-CD is an important factor which influences both the molecular weight and arm number. The melting points and intrinsic viscosities of s-PCLs with similar molecular weights were lower than that of l-PCL, and were found to decrease with increasing arm number. Both SEM and AFM showed that the surface morphology of s-PCL films was different from that of l-PCL. These results indicated that s-PCL with different arms and physical properties could be synthesized using just a β-CD core by adjusting the feed molar ratio of NaH and β-CD
Mechanical behavior of high impact polystyrene based on SB copolymers as a function of synthesis conditions: Part II
Authors: Díaz de León Ramón , Morales Graciela , Acuña Pablo , Soriano Florentino 
Published: August 2014

AbstractThe mechanical properties of different high impact polystyrene (HIPS) were determined by means of impact and tensile tests. Impact strength (IS), yield stress (σy) and Young’s modulus (E) were evaluated as a function of the rubber phase morphological features such as type and particle size (Dp), volume fraction (Φ) and interparticle distance (IPD). In order to evaluate the changes produced in the rubber phase, the initiator, chain transfer agent (CTA), and type and concentration of SB copolymer were varied during the synthesis of HIPS. Transmission electron microscopy was used to analyze the materials’ morphology and the data obtained reveal that the Dp and Φ increases mainly with an increase in the PB content and/or with the use of CTA and decreases with an increase in initiator concentration. In addition, E and yield stress diminishes when increasing the dimensions of the rubber phase (Dp and Φ), contrary to the IS. The IPD/Dp ratio also indicates the dependency of the mechanical properties with respect to the rubber phase features. An increase in IPD/Dp provokes an increases in E and σy, whereas IS diminishes.
Chemical modification of poly(vinylacetylene) via click reaction
Authors: Fengling Qing , Rongxing Yao , Lianjun Wang , Hongqi Li , Weidong Meng 
Published: August 2014

AbstractChemical modification of poly(vinylacetylene) (PVacet) was performed through click reactions by which alkyl and fluoroalkyl groups were introduced to the pendent terminal alkynes of PVacet. Novel polymers containing 1,2,3-triazoles were consequently obtained and their structures and properties were characterized by FT-IR, 1H NMR, TGA, DSC and GPC. The polymers modified by alkyl groups had good solubility, thermal stability and reasonable molecular weights. It was also demonstrated that the properties of fluorine-containing polymers were affected by fluorine atoms with hydrophobic and chemical proof properties
Synthesis and characterization of star and brush grafted polysiloxanes, obtained by atom transfer radical polymerization
Authors: Hurduc Nicolae , Sandu Viorel , Ibanescu Constanta , Nor Iulian 
Published: August 2014

AbstractStar- and brush-polysiloxanes were synthesized via living radical polymerization using two different catalytic systems. The new compounds were characterized by 1H-NMR, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) techniques. CuCl and 2,2’-bipyridyl proved to be the most efficient catalytic system. The type of catalytic system and the reaction conditions control the number of arms for star polymers or the grafted-chain density for brush polymers. The use of chloromethyl styrene as monomer or co-monomer yields homogeneous star- or brush-polysiloxanes, although chloromethyl styrene is an inimer system. The homogeneity of materials was verified by GPC and DSC (TOPEM) methods. For linear grafted polysiloxanes the molecular simulations reflect a tendency of chains to adopt globular conformation for high values of the branching density. The polysiloxanes grafted with styrene/chloromethyl styrene were modified with azobenzene in order to obtain systems able to react to the light stimuli. Rheological behavior of the polymer solutions were evaluated before and after irradiation with UV light. After the UV irradiation a significant viscosity increase was evidenced
Uv-Vis investigations on ion beam irradiated polycarbonate
Authors: Chipara Mircea , Chipara Magdalena Dorina 
Published: August 2014

AbstractUV-VIS investigations on polycarbonate irradiated with accelerated U ions are reported. The experimental data are consistent with the decrease of the energy gap due to irradiation and indicate the formation of isolated conjugated structures. The relatively weak decrease of the energy gap and the shape of the electron spin resonance lines indicate that the conjugated structures are isolated within the polymeric matrix
Characterization and optical properties of a novel conjugated polynitrile produced by plasma polymerization
Authors: Zhao Xiong-Yan 
Published: August 2014

AbstractA novel conjugated polynitrile thin film, plasma-polymerized 3- quinolinecarbonitrile (PP3QCN) thin film was prepared by plasma polymerization of 3-quinolinecarbonitrile. Fourier transform infrared (FT-IR), Ultraviolet-visible spectroscopy (UV-Vis), and X-ray photoelectron spectroscopy (XPS) studies revealed that extensively conjugated C=N double bonds were formed in the deposited plasma film and the plasma polymerization of 3-quinolinecarbonitrile took place mainly through the opening of the π bonds of C ≡ N functional group under our experimental conditions. Plasma-polymerized 3-quinolinecarbonitrile thin film shows a blue emission with relatively high photoluminescence (PL) intensity at about 475 nm wavelength. The fabricated devices with PP3QCN as electroluminescent layer sandwiched between Indium Tin Oxides (ITO) and aluminium (Al) were also found to show a blue emission.
Poly(aniline)/poly(methylmethacrylate) films obtained from waterborne latex nanoparticles
Authors: Oliveira Melo Luciana , Ponzio Eduardo A. , Carmona-Ribeiro Ana M. , Torresi Roberto M. 
Published: August 2014

AbstractThis paper presents the characterization of poly(aniline) (PANI) and poly(methyl methacrylate) (PMMA) coatings obtained by mixing PANI with PMMA aqueous dispersions (latex particles). These dispersions were characterized by using dynamic light scattering for sizing, zeta-potential analysis and thermal analysis. PMMA and PANI/PMMA dispersions show negative charged particles with zeta potential greater than |40| mV, a zeta-average diameter of 64 nm for pure PMMA and a bi-modal particle-size distribution centered at 45 and 120 nm for a mixture with 25% w/w of PANI. Films obtained by casting were characterized by using scanning electron microscopy and they show a conductivity increase upon PANI content reaching a value of 1 mS cm-1 for a film with 25% w/w of PANI. In addition, Raman spectroscopy have shown the presence of the conducting form of PANI in the films and cyclic voltammetry experiments corroborated that they are electroactive in both acid and neutral solutions.
Controlling the phase morphology of immiscible poly(2,6- dimethyl-1,4-phenylene ether)/poly(styrene-co-acrylonitrile) blends via addition of polystyrene
Authors: Göldel Andreas , Ruckdäschel Holger , Müller Axel H.E. , Pötschke Petra , Altstädt Volker 
Published: August 2014

AbstractThe microstructure of melt-processed, immiscible poly(2,6-dimethyl-1,4- phenylene ether)/poly(styrene-co-acrylonitrile) blends (PPE/SAN) was controlled by systematically adjusting the viscosity ratio between both phases. For this purpose, low-viscous polystyrene (PS) was added as a third component, as it shows selective miscibility with PPE and thus allows the varying of the shear viscosity of PPE over a broad range. In order to theoretically predict the phase morphology, a model following Utracki was applied taking into account the viscosity ratio and the respective volume contents of each phase. Detailed transmission electron microscopic investigations of the blend morphologies demonstrated excellent agreement with theory. Moreover, quantitative evaluation of the observed microstructures allowed further description of the degree of blend co-continuity. Thus, desirable compositions of the ternary blend systems could be identified which potentially show enhanced properties such as a high heat deflection temperature, an elevated strength, stiffness, and ease of processing. Finally, a optimum (PPE/PS)/SAN blend system that has been optimised regarding the aforementioned properties was compatibilized by polystyrene-b-poly(1,4-butadiene)-b-poly(methyl methacrylate) triblock terpolymers. Due to the interfacial enrichment of the block copolymer, nanostructured blend morphologies were observed. In the view of these results, pathways to control both the micro- and the nanostructure of PPE/SAN blends are derived, potentially useful to enhance the mechanical as well as thermomechanical property profile.
Study on the effect of galbanic acid on photo-oxidative degradation of linear low density polyethylene (LLDPE) films
Authors: Jahanmardi Reza , Assempour Homa 
Published: August 2014

AbstractPhoto-oxidative degradation of LLDPE films (~ 250 μm thick) containing varying amounts of galbanic acid (a type of coumarin derivatives) was investigated by exposing the films to an artificial sunlight (emitted by 300 W OSRAM Ultra- Vitalux lamps) at 40°C for extended time periods. Photo-oxidative degradation of the neat polymer film and the LLDPE films containing benzophenone (an active photo-initiator for PE) and coumarin alone were also studied under similar conditions for comparison. The rate of photo-oxidation was assessed by measuring tensile properties, gel content, carbonyl index, molecular weight and density. It was shown that galbanic acid was highly effective in accelerating photo-oxidation of LLDPE films and an outstanding acceleration of photo-oxidation was observed for the film containing 0.2 wt % of galbanic acid in comparison with the film containing the same amount of benzophenone. However, the film containing coumarin did not exhibit considerable difference in behaviour in photo-oxidation relative to the neat LLDPE film during the exposure time. On the basis of the obtained results, the prooxidant activity of galbanic acid was described in terms of activity of the functional groups existing in the substituted moiety of its molecules.
Synthesis and swelling characteristics of zwitterionic hydrogel
Authors: Singh Meenakshi , Singh Paresh Kumar , Singh Vinay Kumar 
Published: August 2014

AbstractHydrogels comprising of zwitterionic repeat units were synthesized. The amine groups of the poly (ester amine) were quaternized with 1,3-propane sultone. The gelation was observed on treatment with sultone. The hydrophilic gel thus formed is sensitive to temperature, pH, ionic strength and nature of electrolytes in aqueous solution. In absence of any electrolyte, the extent of swelling decreased with temperature, but in the monovalent salt solution the equilibrium swelling diminished with temperature and the contrary behaviour was experiential in bivalent electrolytes.
Effect of the initial water activity on the yields and molecular wWeights of the lipase-catalysed synthesis of aliphatic polyesters in low pressure liquid R-134a
Authors: García-Arrazola Roeb , Gimeno Miquel , Bárzana Eduardo 
Published: August 2014

AbstractThe enzymatic synthesis of the polyester poly(epsilon-caprolactone) (PCL) were evaluated on the basis of the initial water activity (awi) using liquid 1,1,1,2-tetrafluoroethane (R-134a) as solvent media at 2.5 MPa. Polymer yields and molecular weights were directly related to awi and reaction times. The highest molecular weight (Mn) was 83,600 gmol-1, Mw /Mn 1.4, with a 67% yield after 48 h of reaction with the lowest biocatalyst awi preparation (awi <0.16). It is suggested that the enhanced solubility of the growing polymer chains in liquid R-134a may be responsible for the attainment of such high molecular weight. A maximum polymer yield of 99% with Mn 7,246 gmol-1 and Mw/Mn 4.5 was attained when the biocatalyst was adjusted to awi =0.22.
A high mechanical strength hydrogel from polyacrylamide/polyacrylamide with interpenetrating network structure by two-steps synthesis method
Authors: Tang Qunwei , Wu Jihuai , Lin Jianming , Sun Hui , Ao Haiyong 
Published: August 2014

AbstractA simple two-steps polymerization method was used to prepare a polyacrylamide hydrogel with a full interpenetrating network structure based on the sorption and porous properties of polyacrylamide superabsorbent. In conditions of 10 g acrylamide monomer, 0.04 g crosslinker for the first polymerization and the second polymerization, respectively, and the swelling ratio of 9, the hydrogel possessed a tensile strength of 1.22 MPa and elongation at break of 900 %.
Rheological behaviour of low/high density polyethylene melt flowing through micro-channels
Authors: Chen Chun-Sheng 
Published: August 2014

AbstractThe determination of the proper rheological behaviour of the polymer melt within micro structured geometry is vital for accurately simulating the micro moulding. The paucity of suitable equipments is one of main hurdles in the investigation of micro melt rheology. In the present study, a measurement system for the melt viscosity of low and high density polyethylene polymer melts flowing through micro-channels was established. The capillary flow model with Rabinowitsch correction was used in the calculations of the viscosity based on the measured pressure drop and volumetric flow rate. The effect of the morphology structure on the viscosity characteristics for both the LDPE and HDPE resins within micro-channels was investigated and discussed. It was found that the measured viscosity values for LDPE and HDPE in the test ranges are significantly lower (about 40~56% and 22~29% for LDPE and HDPE, respectively, flowing through a channel size of 150μm) than those obtained with a traditional capillary rheometer. Moreover, both the percentage reduction in the viscosity value and the ratio of the slip velocity to the mean velocity increase as the micro-channel size decreases. It can be observed that the rheological behaviours of the HDPE and LDPE resins in microscopic scale are different from those in macroscopic scale as a result of the wall slip effect. It also revealed that the wall slip occurs more easily for the LDPE resin within micro channels than HDPE resin due to enlarged effect of morphology structure.
Synthesis and characterization of new liquid, branched and random poly(methylhydrosiloxanes)
Authors: Chruściel Jerzy , Fejdyś Marzena , Michalska Zofia , Fortuniak Witold 
Published: August 2014

AbstractTwelve new liquid branched poly(methylhydrosiloxanes) of random structures (b-r-PMHS), containing triple branching units MeSiO1.5 (T), both Me2SiO (D) and MeHSiO (DH) chain building units (or only mers MeHSiO), and terminal groups Me3SiO0.5, have been prepared by hydrolytic polycondensation method of appropriate organic chlorosilanes in diethyl ether medium at temperatures < 0 °C. Two b-r-PMHS containing structural units: M, D, DH, T and TH have been obtained as well. Volatile low molecular weight oligosiloxanes were removed by vacuum distillation at 125-150 °C. Yields of b-r-PMHS ranged from 57 to 84 wt. %. All polymeric products were characterized by FT-IR, 1H- and 29Si-NMR, and elemental analysis. Their dynamic viscosities were determined in the Brookfield HBDV+IIcP cone-plate viscometer. The molecular weights of b-r-PMHS and polydispersities of MW were analyzed by size exclusion chromatography (SEC).
Effect of LiCl and non-ionic surfactant on morphology of polystyrene electrospun nanofibers
Authors: Fallahi Delaram , Rafizadeh Mehdi , Mohammadi Naser , Vahidi Behrooz 
Published: August 2014

AbstractPolystyrene fibers were produced by the electrospinning technique. The effects of solution conductivity, surface tension and concentration on morphology and average diameter of electrospun fibers were investigated by scanning electron microscopy (SEM). Solutions of 12, 10, 8, 6% (w/v) polystyrene in dimethylformamide were prepared. Lithium Chloride and a non-ionic surfactant were used to change the conductivity and surface tension of the solutions, respectively. The results indicate that increasing the solution conductivity eliminates the bead formation and increases the fiber diameters. By addition of salt, fine and consistent fibers could be produced from electrospinning of 8% (w/v) PS/DMF solution. Adding 0.1% surfactant reduces the solution surface tension and results in smaller beads and higher fiber diameters. By increasing the amount of surfactant to 0.3%, big beads and thinner fibers are produced.
All furanic polyhydrazides and corresponding polyoxadiazoles
Authors: Afli Aljia , Abid Souhir , El Gharbi Rachid 
Published: August 2014

AbstractPolyhydrazides based on furanic diacid chlorides and furanic dihydrazides were prepared. The properties of the products are discussed in terms of the backbone structure and the polycondensation technique employed. Their cyclodehydration was carried out by heating in SOCl2 to give new polyoxadiazoles consisting of alternating furanic units and 1,3,4-oxadiazole rings.
Synthesis and structural studies of poly(tetramethyleneoxypropylene p, p´-bibenzoate)
Authors: Martínez-Gómez Aránzazu , Bello Antonio , Pérez Ernesto 
Published: August 2014

Abstract A smectic main chain polybibenzoate has been synthesized using a mixture of the branched ether-diols: HO(CH2)4OCH(CH3)CH2OH and HO(CH2)4OCH2CH(CH3)OH, as flexible spacers. The mesophase has been identified as SmCalt by optical microscopy and X-ray diffraction experiments. The irregular chemical structure of the polymer, due to the asymmetry of the spacers, produce two important effects: the mesophase is stabilized and the liquid crystallization is slowed down, making possible the freezing of the amorphous glass by supercooling the isotropic melt. Therefore, both the amorphous glass and the smectic glass can be obtained and analyzed. By differential scanning calorimetric measurements it was found that the glass transition of the mesophase appears at lower temperature than the glass transition of the amorphous state. Depending on the temperature and rate of deformation, the molecular orientation in the drawn smectic phase can be perpendicular (anomalous orientation) or parallel (normal orientation) to the stretching direction (or a mixture of both orientations). The morphology of these oriented samples has been studied by scanning electron microscopy.
Copolymerization of Ethylene and 1-Hexene Catalyzed by the Zirconocene/Al(i-Bu)3/B(C6F5)3 Catalytic System
Authors: Zhang Puyu , Li Yonghong , Chai Yun 
Published: August 2014

AbstractCopolymerizations of ethylene/1-hexene were conducted using different zirconocene/AlR3/B(C6F5)3 catalytic systems at 50°C. When AlEt3 was used as alkylate agent, very low copolymerization activity was observed with both bridged catalyst Et[Ind]2ZrCl2 and unbridged zirconocene Cp2ZrCl2 in-situ activated with B(C6F5)3. In appropriate Al/Zr mole ratio using Al(i-Bu)3, the catalytic activities of both zirconocene catalytic systems were similar to those of sophisticated zirconocene/methylaluminoxane(MAO) catalytic system. The catalytic activities, comonomer incorporation and molecular weight of the copolymer synthesized with Et[Ind]2ZrCl2/Al(i-Bu)3/B(C6F5)3 were higher than those obtained with Cp2ZrCl2/Al(i- Bu)3/B(C6F5)3. The effect of the concentration of 1-hexene on catalytic activity, copolymer molecular weight, and comonomer incorporation was investigated. The complicated “co-monomer effect”, together with an increase in comonomer incorporation, a decrease in the copolymer molecular weight, was found when the comonomer concentration was increased.
Correlation between morphology and NGM of 3,4- ethylenedioxythiophene (EDOT) in acetonitrile
Authors: del Valle María Angélica , Belén Camarada María , Díaz Fernando , East Gastón 
Published: August 2014

AbstractThe nucleation and growth mechanism (NGM) for the electro-oxidation of 3,4-ethylenedioxythiophene (EDOT) in acetonitrile on platinum and tin(IV) oxide electrodes was determined by analyzing the potentiostatic current-time transients inferred from electrocrystallization theory. The measurements were complemented by using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Preliminary studies performed to establish the working conditions for the potentiostatic technique using cyclic voltammetry (CV) demonstrated that under the working conditions employed herein the best potential scan-rate to obtain electrodeposits of poly(EDOT) was 50 mV·s-1. The prepared polymer displayed electrochromic properties and p- and n-doping, the p-doping being chemically reversible. In addition, it was observed that the electropolymerization mechanisms on both electrode materials were a combination of two contributions: progressive nucleation, followed by diffusion-controlled tridimensional growth, PN3Ddif; and instantaneous nucleation followed by three-dimensional growth under charge transfer control, IN3Dct. At shorter times, the IN3Dct contribution prevail giving rise to conical deposits, while at longer electrolysis times the polymeric deposit is made of granules, corresponding to the PN3Ddif mechanism. The electrode material has no effect at all on the global mechanism, but affects the time at which either contribution predominates. However, the morphological predictions made from the NGMs must be corroborated by other techniques before using the data to control the deposit to be prepared.
Modification of poly(butylene terephthalate) by reaction with 1,4-butane sultone; synthesis and thermal characterization of new telechelic PBT ionomers
Authors: Berti Corrado , Celli Annamaria , Marianucci Elisabetta , Vannini Micaela 
Published: August 2014

AbstractNew telechelic poly(butylene terephthalate) (PBT) ionomers, characterized by the presence of some aliphatic sulfonated chain ends, were prepared by reaction with the 1,4-butane sultone. Two methods of synthesis were compared and the final polymers, containing different percentages of ionic groups, were characterized, with particular attention to the thermal properties. Thermogravimetric analysis shows that the presence of ionic groups does not modify the thermal stability of PBT. The differential scanning calorimetry indicates that the crystalline phase and the crystallinity degree of PBT do not change in the presence of ionic chain ends, whereas the crystallization rate was found to be strongly modified. The ionomers crystallize at very high rate, due to the nucleating effect of the ionic aggregations formed in the melt.