bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on PEBAX/organoclay nanocomposites by meltintercalation process: Effect of organoclay surface
Authors: Mohamadi Somayeh , Sanjani Naser Sharifi 
Published: August 2014

AbstractIn this study, the polyetherblock amide (PEBAX)® nanocomposites with 2.5 % and 5 wt.% organoclay, based on Cloisite 30B (montmorillonite intercalated with dimethyl, 2-ethyl hexyl hydrogenated tallow alkyl ammonium cation), were prepared by the melt-intercalation process. The structural properties, thermal behaviors and the mechanical properties were characterized using the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), melt flow index (MFI), differential scanning calorimetry (DSC), thermogravimetry analyses (TGA), transition electron microscopy (TEM), scanning electron microscopy (SEM) and the tensile test. The XRD analysis indicated the formation of intercalated PEBAX nanocomposites. The TGA results revealed that the addition of 2.5 wt.% nanoclay improved the thermal properties, while the nanocomposite with 5 wt.% nanoclay did not enhance the thermal stability. The DSC analysis indicated that, in the case of PEBAX with 2.5 wt.% organoclay, each peak was related to the fusion of the crystalline fraction of the poly ether and poly amide affected blocks. On the contrary, regarding the PEBAX with 5 wt.% nanoclay, only the peak related to polyamide was changed. Interestingly, the tensile modulus increased with the incorporation of 2.5 wt.% clay, but it decreased in PEBA 5. The elongation at break reduced with the incorporation of the clay, attaining a minimum value at the clay concentration of 2.5 wt.%, and followed by an increase at the clay concentration of 5 wt.%.
Starch–metal complexes and their rheology
Authors: Ciesielski Wojciech , Krystyjan Magdalena 
Published: August 2014

AbstractChanges in conductivity of 5 w/w% starch gels was studied on their titration with 0.1 M aqueous solutions of selected metal salts. Starch gels usually trapped around 10 mg metal ions per 1 g starch [Co(II), Cu(II), Fe(III), Ni(II)] and that value was only slightly dependent on starch origin (amaranthus, corn, potato, tapioca, waxy corn). Among salts studied (acetates, chlorides, nitrates) FeCl3 and NiCl2 were likely to be used because they hydrolyzed increasing conductivity of the solutions and formed micelles of corresponding hydroxides adhering to starch micelles and increasing amount of trapped metal. Addition of metal salts to starch gels had a devastating effect on pseudoplasticity and viscosity of starch gels and only potato starch gel was to a certain extent, exceptional in that respect.
FTIR Study of the retardation effect of boric acid on the cyclization reaction of polyacrylonitrile
Authors: Ouyang Qin , Cheng Lu , Wang Haojing , Li Kaixi 
Published: August 2014

AbstractA retardation effect of boric acid on the cyclization reaction of polyacrylonitrile (PAN) was clearly observed by Fourier transform infrared spectroscopy. The Lewis acid nature of boric acid probably accounts for this retardation effect. A quantitative evaluation of this effect was also made, indicating two potential applications, i.e., high temperature stabilization and melt spinning, which are favourable for the cheap and fast fabrication of PAN-based carbon fibers.
New trends in polymer electrolytes: a review
Authors: Srivastava Neelam , Tiwari Tuhina 
Published: August 2014

AbstractSince the work of Armand, polymer electrolytes have received great attention and lots of publication can be found in the literature. Each publication has its particular orientation and tries to emphasize only limited points to prove their system as the better one. But to really get some good fruitful material we need to look simultaneously for different aspects of the electrolyte such as good conductivity and mechanical property, understanding of interaction between the salt and other materials present in the system, nature of solid electrolyte/ electrode interface, electrochemical window, working temperature window etc. Hence a brief summary of the variety of polymer electrolytes is given in the paper with their advantages and disadvantages. Paper discusses polymer electrolytes starting from Dry SPE to the latest IL/Zwitterionic electrolytes and the behavior of the some devices using these materials.
Photoluminescence and electron migration characteristics of aromatic poly(amide-imide) containing 1-naphthaldehyde and 4,4′-diamino diphenyl ether
Authors: Khoee Sepideh , Zamani Somayeh 
Published: August 2014

AbstractA new photoactive polymer poly(amide-imide), was fabricated by reacting two synthesized monomers, N,N'-(4,4'-oxy-bis(4,1-phenylene))-bis-(1,3- dioxo-1,3-dihydroisobenzofuran-5-carbox amide) and N-(4,6-diamino-1,3,5- triazine-2-yl)-1-naphthamide. Polycondensation reaction of the two monomers was performed under 10 min microwave irradiation in o-cresol as solvent for producing a photoactive poly(amide-imide) in a quantitative yield. The resulting polymer was characterized by FT-IR, 1H-NMR, TGA techniques and its solvatochromic and fluorescence properties were investigated in different solvents. The poly(amideimide) exhibit broad fluorescent band, and the fluorescence intensity is related to the intermolecular chain-chain or chain-solvent interaction. Also the self-quenching mechanism was studied according to the specific behavior of the polymer in different solvents and the self-quenching rate constant for the association reaction in the excited state (Kq) could be measured from the Stern-Volmer equation. This kind of fused system and diamines show various electron migration mechanisms and photoluminescent properties in the singlet excited states.
Morphology, thermal and mechanical properties of PVAc/ TiO2 hybrid nanofibers
Authors: Wu Ning , Wang Jiaxi , Wei Qufu , Cai Yibing , Lu Bing 
Published: August 2014

AbstractOrganic/inorganic hybrid was successfully prepared by sol-gel technique, which consisted of polyvinyl acetate (PVAc) as organic segment and titanium dioxide (TiO2) as inorganic part. The PVAc/ TiO2 hybrid nanofibers were fabricated by electrospinning. The structures and properties of the hybrid nanofibers were investigated by transmission electronic microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analyzer (TGA) and tensile testing. SEM observation revealed the fibrous structures of the hybrid nanofibers. AFM and TEM images indicated the surface morphology and inner structures of the hybrid nanofibers. It was found by TGA analysis that the thermal stability of pure PVAc nanofibers was enhanced by the increase of TiO2 phase. The breaking strength was increased while the breaking elongation was decreased as the TiO2 content increased.
Influence of the molecular weight distribution on the percolation threshold of carbon nanotube – polystyrene composites
Authors: Hermant Marie Claire , Smeets Niels M. B. , Hal Roger C. F. van , Meuldijk Jan , Heuts Hans P. A. , Klumperman Bert , Herk Alex M. van , Koning Cor E. 
Published: August 2014

AbstractCarbon nanotubes were introduced into insulating polystyrene (PS) and poly(methyl methacrylate) (PMMA) by means of a latex-based technique. A systematic study of the effect of the polydispersity index, more particularly the presence of different amounts of low molar mass polymer, on the final composite conductivity was performed. Six latexes with varying molecular weight distributions were prepared by means of conventional free radical emulsion polymerization in the presence of different amounts of chain transfer agent, namely n-dodecyl mercaptan. Composites were prepared with both multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs). Shifts in the percolation threshold from 0.9 to 0.6 wt% for MWCNTs and from 0.7 to 0.4 wt% for SWCNTs were observed for PS matrix material, whereas for PMMA matrix material the percolation thresholds shifted from 0.6 to 0.3 wt% for MWCNTs and 0.35 to 0.2 wt% for SWCNTs upon increasing the amount of low molecular weight polymer in the polymer matrix.
Application of the Monte Carlo simulation method to the Investigation of the effect of chain-length-dependent bimolecular termination on ATRP
Authors: Najafi Mohammad , Haddadi-Asl Vahid , Salami-Kalajahi Mehdi , Mamaghani Hossein Roughani 
Published: August 2014

AbstractAn optimized and high-performance Monte Carlo simulation is developed to take thorough account of the influence of chain-length-dependent termination rate constant on polymer microstructure in ATRP. According to the simulation results, bimolecular termination rate constant sharply drops throughout the polymerization when chain length dependency is applied to the program. The dependence of on reaction time, as a common feature of ATRP, is almost linear. Moreover, the polymerization proceeds to higher conversion when the chain-length-dependent termination rate constant is applied to the simulation model. In addition, the plot of against reaction time is completely linear; also, the initiator is entirely decomposed at the early stages of the polymerization as the plot of CIagainst time shows. The concentration of the catalyst in lower oxidation state decreases first and then plateaus at higher conversion. Furthermore, the amount of Mtn Y/L used in the polymerization is lower when the chain-length-dependent termination rate constant is employed in the simulation. Finally, the peak of molecular weight distribution of polymer chains shifts toward higher molecular weight during the reaction. Besides, the molecular weight distribution broadens at higher conversion. However, the molecular weight distribution of polymer chains produced under conditions of applying chain-lengthdependent termination rate constant is narrower.
Thermal, mechanical and wettability properties of some branched polyetherurethane elastomers
Authors: Vlad Stelian , Spiridon Iuliana , Grigoras Cristian Vasile , Drobota Mioara , Nistor Alexandra 
Published: August 2014

AbstractIn this study three series of polyetherurethanes (PEU) based on Terathane ® (polytetramethyleneetherglycol - PTMEG, Mn 1400) as polyol; isophorone diisocyanate (IPDI), 4,4’-methylene-bis-(cyclohexyl-isocyanate) (HMDI) and hexamethylene diisocyanate (HDI) as aliphatic diisocyanate components; 1,4- butanediol (BD) and glycerin (Gly) as chain extenders were synthesized. The glycerin as triol is responsible for the crosslinking structures. All polyether urethanes were synthesized by prepolymer method. The PTMEG was reacted with diisocyanate to realize a diisocyanate-terminated prepolymer, which in next step was extended with blend of the 1,4-butanediol (BD) and glycerin (Gly) in different proportion. The influence of the diisocyanate structure and chain extender functionality on the thermal, mechanical and wettability properties were the aim of this study. The physical, mechanical and wettability properties of these polymers were measured according to standard methods. All polymers were characterized by conventional characterization methods. Different methods of thermal analysis (TGA and DSC) were used for characterization. Wettability was estimated by determination of the dynamic contact angle. The structures were confirmed by FTIR and H-NMR analysis. The results show that the thermal stability, mechanical and wettability properties of the final products are influenced by the diisocyanate and chain extenders nature.
Coating of Al mould surfaces with polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxy (PFA) and ethylene-tetrafluoroethylene (ETFE)
Authors: Akinci Akin , Cobanoglu Ebutalip 
Published: August 2014

AbstractBecause of low cost, easily productivity and high thermal conductivity, aluminum (Al) moulds are preferred in the production of the polyurethane (PUR) parts. In this study, adhesion behavior and surface properties of coated materials between mould used in the production of automotive seat and PUR materials were investigated. Four different polymer types were coated on Al mould and they were characterized using contact angle, surface roughness, coating thickness, adhesion, cross-cut and SEM test methods. It was found that, PFA has the least value of surface roughness and ETFE has the highest one in the four different coatings produced. After holding period in isocyanate, decrease were measured on the angle values of all coatings. In the contact angle measurements before and after isocyanate tests, PFA exhibited the highest contact angle value.
Synthesis, Characterization and Adsorption Performance of Semi-crystalline/Liquid Crystalline Polyether Chelating Resins
Authors: Zhang Shuangqing , Zhang Chaocan , He Changhai , Xu Jun 
Published: August 2014

AbstractA series of polyether chelating resins with pendent biphenyl mesogenic groups were synthesized, and the chemical structure of monomers and polymers were confirmed by IR and 1H NMR detection. The thermal properties of resins were investigated by the Differential Scanning Calorimetry (DSC) and Polarizing Microscopy (POM), and the results showed that only the product of polyepichlorohydrin grafted with 4-cyano-4’-hydrobiphenyl, i.e., HPCN resin, was a kind of nematic liquid crystal polymer with typical schlieren texture (70-130 0C) and other resins were semi-crystalline. The results of adsorption experiments showed that all five resins exhibited a higher adsorption capacity (>1.0 mmol/g) for Cu (II) and Hg (II) and medium adsorption ability for Cd (II), Zn (II), Pb (II) and Co (II), however, a poor adsorption capacity (<0.3 mmol/g) for Mg (II), indicating that this type of polyether resins have a better selective adsorption for above metal ions. In addition, the adsorption capacity of HPnCP resins was generally higher than that of HPd and HPCN owing to the existence of terminal pyrrole coordination groups in HPnCP resins.
Photoinduced supramolecular chirality in glassy nematic linear and star shaped methacrylic azopolymers obtained by ATRP
Authors: Angiolini Luigi , Barberá Joaquín , Benelli Tiziana , Giorgini Loris , Paris Fabio , Salatelli Elisabetta , Tejedor Rosa M. 
Published: August 2014

AbstractThe induction of chirality in achiral liquid crystalline azoaromatic polymers with circularly polarized light (CPL) has been studied on well-defined macromolecular derivatives with different molecular structures, synthesized by atom transfer radical polymerization (ATRP). Two methacrylic homopolymers have been investigated: a linear and a three arms star polymer. Both the polymeric samples are featured by low polydispersity and similar average polymerization degree, so that structure-properties correlations are made possible. Irradiation with CPL of one handed rotation sense of casted films and a planar cell of these polymers in the glassy nematic phase allowed to ascertain by UV-Vis and CD spectroscopy the formation of a supramolecular chiral structure with high chirality induced into the material. The results are interpreted in terms of the structural features of the polymers.
Improved dispersion of multi-wall carbon nanotubes in poly(butylene terephthalate) using benzimidazolium surfactants
Authors: Colonna Martino , Berti Corrado , Binassi Enrico , Fiorini Maurizio , Acquasanta Francesco , Celli Annamaria 
Published: August 2014

AbstractMulti-wall carbon nanotubes/poly(butylene terephthalate) nanocomposites have been prepared by in-situ polymerization. Benzimidazolium tetrafluoroborate salts improve the dispersion of carbon nanotubes in the polymer matrix due to the formation of “π-cation” interactions of the imidazolium salt with the surface of the carbon nanotubes. An improved dispersion of the nanotubes in butanediol was also observed using the benzimidazolium salt. The presence of the compatibilization agent gives rise to improved thermo-mechanical properties and electrical conductivity for the nanocomposite. The presence of the nanotubes also consistently increases the thermal stability and enhances the nucleation process on PBT crystallization.
Vitrification and devitrification of the rigid amorphous fraction in poly(ethylene terephthalate)
Authors: Righetti Maria Cristina , Di Lorenzo Maria Laura 
Published: August 2014

AbstractVitrification and devitrification of the rigid amorphous fraction (RAF) of poly(ethylene terephthalate) (PET), analyzed during development and disappearance of the three phase structure, are detailed in this contribution. Upon cooling from the melt at a constant rate, the rigid amorphous fraction starts to vitrify when the crystallization process is almost finished, and continues on further cooling. The rigid amorphous fraction is formed in the same temperature range of the secondary crystal growth. Analysis of the low melting endotherm that is observed in isothermally crystallized PET a few degrees above the crystallization temperature reveals a joint contribution of melting and devitrification of the rigid amorphous fraction. The results confirm a link between secondary crystallization and vitrification of the rigid amorphous fraction in semicrystalline polymers. Secondary crystallization takes place in geometrically restricted areas, in which the polymer chains undergo large constraints, so that the mobility of the amorphous chain portions coupled with the crystal phase is reduced. Similarly, the gain in mobility upon partial melting of thinner and/or more defective crystals allows an increase in mobility of the coupled amorphous regions, which results in concurrent mobilization of the rigid amorphous fraction.
The role of the matrix-filler affinity on morphology and properties of polyethylene/clay and polyethylene/ compatibilizer/clay nanocomposites drawn fibers
Authors: Dintcheva Nadka Tzankova , Marino Rosamaria , La Mantia Francesco Paolo 
Published: August 2014

AbstractIn this work the structural variations and mechanical performance of polyethylene/clay nanocomposite drawn fibres, also in the presence of compatibilizer, such as a commercial maleic anhydride grafted polyethylene, PEgMA, was studied. In the isotropic state both systems show intercalated morphology.After spinning and cold drawing, by adding the nanoparticles, the tensile strength as a function of the draw ratio increases and this rise is more pronounced for the filled compatibilized system. The reduction of the elongation at break, on the contrary, is about the same for all the examined samples. The orientation of the macromolecules, evaluated by measurements of the birefringence and calorimetric analysis, is similar for all the samples, but the filled, drawn fibres show a higher level of intercalation and, in particular, some exfoliation, more and more pronounced with the draw ratio and in presence of compatibilizer, as a consequence of the application of the extensional (at low and high temperature) flow. For the three components system with greater affinity between the polymer matrix and clay, the extensional flow is more efficient. The initial intercalated morphology changes to some more intercalation and finally, at the highest anisotropic condition in the presence of the PEgMA, evolves to delaminated clay structure.
Modelling of mechanical behaviour of polyamide nanocomposite fibres using a three-phase Halpin-Tsai model
Authors: Garofalo Emilia , Russo Giovanna Maria , Di Maio Luciano , Incarnato Loredana 
Published: August 2014

AbstractThe aim of the present study is to correlate the features of the elongational flow-induced morphology to the mechanical properties of polyamide based nanocomposite fibres. Particular attention was paid to modelling the mechanical behaviour of the hybrids which were produced by fibre spinning technique and collected at different draw ratios.Tensile properties of as-spun and stretched fibres were investigated and correlated to their nanostructure through analytical techniques sensitive to different aspects of the hybrids morphology, such as X-Ray diffraction and TEM analysis. In particular, the TEM images of the nanocomposite systems showed intercalated/exfoliated morphology in all hybrids. For this reason, a three-phase Halpin-Tsai model, based on polyamide-6 matrix, exfoliated clay platelets and nanolayer intercalated clusters, was used to fit the experimental data.This method was applied to calculate the Young’s modulus of nanocomposite fibres both as-spun and stretched ones. Moreover, the model was used for predicting the effect of various morphological parameters including the exfoliation degree, clay layer and cluster aspect ratio.
Synthesis and characterization of poly(4-oxyalkylenoxy benzoate)s of different chain length
Authors: Siracusa Valentina , Lotti Nadia , Puglisi Concetto , Samperi Filippo , Munari Andrea , Finelli Lara , Battiato Salvatore 
Published: August 2014

AbstractThree different monomers starting from p-(4-hydroxy)benzoic acid and 3- chloro-1-propanol, 4-chloro-1-butanol and 6-chloro-1-hexanol, respectively, were synthesized and extensively characterized by means of 1H and 13C NMR, MALDITOF MS and elemental analysis. Subsequently, poly(4-oxyalkylenoxy benzoate)s polymers with different chain length were prepared in bulk starting from the mentioned above monomers, employing Ti(OBu)4 as catalyst, according to the usual two-stage polymerization procedure. The polymers were characterized in terms of chemical structure, molecular mass and thermal behaviour. Tg, Tm and the ability to crystallize were found to be affected by the number of methylene groups per repeat unit and the results were explained mainly on the basis of the increment of the chain flexibility.
Synthesis and characterization of amphiphilic graft copolymers of poly(1,3 dioxolane) macromonomers with styrene and methyl methacrylate
Authors: Bendaikha Hayet , Clisson Gérald , Khoukh Abdelouahad , François Jeanne , Kada Seghier Ould 
Published: August 2014

AbstractMethacrylate-terminated Poly(1,3 dioxolane) (PDXL) macromonomers were synthesized by cationic ring-opening polymerization in the presence of 2- hydroxypropyl methacrylate (2-HPMA) as transfer agent. Molecular weights, polydispersity index and functionality of the PDXL macromonomers were evaluated by size exclusion chromatography (SEC) and 1H nuclear magnetic resonance spectroscopy (1H-NMR). Copolymerizations of PDXL macromonomers, of different molecular weights, with styrene (St) and methyl methacrylate (MMA) were carried out using various feed molar ratios. The resulting polymers confirmed the grafting of PDXL with PS and PMMA by SEC and 1H-NMR Monomer reactivity ratios between the macromonomers and the comonomers were estimated from the copolymerization results. Macromonomer reactivity depends on the comonomer considered. Glass transition temperatures of the copolymers were found to decrease with an increase in the amount of PDXL in the copolymers. The values of Tg depend on the composition and the size of the PDXL grafts.