bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lattice sizes, crystallinities, and spacing between amorphous chains - characterization of ethene-/ɑ-olefin copolymers with various comonomers and comonomer contents measured by wide angle X-ray scattering
Authors: Stadler Florian J. , Takahashi Tatsuhiro , Yonetake Koichiro 
Published: August 2014

AbstractEthene-/ɑ-olefin copolymers having a wide range of comonomer contents with comonomers between 4 and 26 carbon atoms in length were characterized by wide angle X-ray scattering (WAXS). It was found that the crystallinities matched fairly well with the crystallinities from DSC and volumetric measurements. An increase of the crystal lattice size was found with increasing comonomer content and comonomer length. Both are attributed to the formation of defects around these short-chain branches in the crystal lattice, which widen it. Increasing the cooling time will lead to a more densely packed crystal structure, if the quenched structure is distorted, i.e. if the sample contains comonomer. A higher molar mass Mwwidens the average space between chains in the amorphous phase as well as the addition of comonomer. The latter finding is explained by the increasing number of chain ends introduced by the comonomer which increases the free volume in the sample because of the worse amorphous packing of the chain ends.
Linear low density polyethylene (LLDPE) films containing perylene dyes as stress-strain luminescent indicators
Authors: Pucci Andrea , Donati Filippo , Ruggeri Giacomo , Ciardelli Francesco 
Published: August 2014

AbstractLinear low density polyethylene (LLDPE) films containing different concentrations of perylene (P) chromophores have been prepared by solution-casting and compression-moulding. The light emission features of the films depend on P concentration and polymer films deformation. A well-defined band attributed to the formation of micro/ nano-structured perylene chromophoric aggregates is observed with more than 0.1 wt.% of P in the film. The occurrence of this phenomenon changed the emission colour of the films from a bright blue (noninteracting dyes) to low intense pale yellow (interacting dyes) colour. During film drawing the LLDPE macromolecules reorganization is able to break the P supramolecular organization, leading to the prevalence of the blue emission of monomeric P. The optical behaviour of perylene dyes acting as internal stressstrain luminescent indicators for polyethylene films, provides a powerful tool to detect macromolecular organization.
Synthesis and self-assembly of poly(ethylene oxide)-b-poly (2-hydroxyethyl methacrylate)
Authors: Yang Runmiao , Wang Yanmei , Zhou Dan , Jia Jianyong , Han Yanchun 
Published: August 2014

AbstractPoly(ethylene oxide)-b-poly(2-hydroxyethyl methacrylate) (PEO-b- PHEMA) was synthesized by successive atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate（HEMA） monomer using PEO-Br macroinitiator as initiator, CuBr/CuBr2 and 2,2‟-bipyridyl (bpy) as catalyst and ligand. IR, 1H NMR, and GPC analysis indicate that PEO-b-PHEMA block copolymer with low polydispersity index (Mw/Mn≈ 1.1) has been formed. Selfassembly of this double hydrophilic block copolymer in the selective solvent and water was also studied. Owing to the high hydrophilic nature of the PEO and PHEMA blocks, this double hydrophilic block copolymer cannot disperse well in water. So block copolymer was modified by part esterification of PEO-b-PHEMA with acetic anhydride, which increased the hydrophobic group of the PHEMA block. The TEM results show that this block copolymer spontaneously form well-defined micelles in water.
Viscometric and rheological study of polyacrylonitrile solutions
Authors: Brunchi Cristina-Eliza , Bercea Maria , Morariu Simona 
Published: August 2014

AbstractThe viscometric behaviour of polyacrylonitrile solutions in dimethylformamide has been examined in dilute and extremely dilute regimes of concentration. For semidilute and concentrated solutions, viscoelastic properties were determined and discussed. The overlap concentration was evidenced as being the crossover of two scaling laws characterizing the entangled and nonentangled solution regimes.
Prediction of crystallinity profile and eject time of injection molded parts using finite element method (FEM)
Authors: Mostafaiyan Mehdi , Sharif Farhad 
Published: August 2014

AbstractQuality of injection molded parts of semi-crystalline polymers has been the subject of intense interest from both analytical and industrial points of view. Crystallinity profile plays an important role in determining mechanical properties of a part and its quality. Therefore it is important to analyze the effect of injection molding parameters on the crystallinity profile of the molded parts. In this study, finite element analysis has been used to solve the equations of mass, momentum, and energy conservation simultaneously with the equation of crystallization kinetics to predict melt front, its solidification and crystallinity profile. The results from our numerical analysis have been compared with the reported experimental results. Furthermore, progress of the crystallization is proposed to be a proper criterion for estimation of the eject time. Finally, the effects of mold and melt temperature on the eject time; part temperature and average degree of crystallinity, for a specific compound are also presented.
Microwave-assisted synthesis and characterization of some optically active poly(ester-imide) thermoplastic elastomers
Authors: Zahmatkesh Saeed , Hajipour Abdol Reza 
Published: August 2014

AbstractPyromellitic dianhydride (1) was reacted with L-leucine (2) to result in [N,N'-(pyromellitoyl)-bis-L-leucine diacid] (3). This compound (3) was converted to N,N'-(pyromellitoyl)-bis-L-leucine diacid chloride (4) by reaction with thionyl chloride. The microwave-assisted polycondensation of this diacid chloride (4) with polyethyleneglycol-diol (PEG-200) and/or three synthetic bisphenols furnish a series of new PEIs and Co-PEIs in a laboratory microwave oven (Milestone). The resulting polymers and copolymers have inherent viscosities in the range of 0.31- 0.53 dl g-1. These polymers are optically active, thermally stable and soluble in polar aprotic solvents such as DMF, DMSO, NMP, DMAc and sulfuric acid. All of the above polymers were fully characterized by IR spectroscopy, 1H NMR spectroscopy, elemental analyses, specific rotation and thermal analyses. Some structural characterizations and physical properties of these optically active PEIs and Co-PEIs are reported.
Novel electron-acceptor conjugated polymer materials based on poly(thienylene ethynylene) derivatives
Authors: Liu Kuan , Li Yang , Yang Mujie 
Published: August 2014

AbstractNovel electron-acceptor materials based on poly(thienylene ethynylene) derivatives (PTE-BT and PTE-DCNTB) were synthesized and characterized by FTIR spectroscopy. Their thermal, electrochemical and optical properties were investigated. The π-conjugated polymers are soluble in common organic solvents. The maximum UV-Vis absorptions of PTE-BT and PTE-DCNTB in solution are observed at 460 and 390 nm, respectively. The electrochemical band gap was found to be 1.89 eV for PTE-BT and 2.01 eV for PTE-DCNTB. Both polymers are promising as electron-acceptor materials for photovoltaic applications.
pH-Driven synthesis of collagen-silica nanohybrids
Authors: García-Valdés C. J. , Hernández-Padrón G. , García-Garduño M. V. , Castaño V. M. 
Published: August 2014

AbstractImmobilization of the protein collagen Type I into transparent porous silica matrices produced by the sol-gel process was achieved by using a high concentration of precursor and a low pH. Surface silanol groups interact chemically with the amide and carboxylic groups of the collagen Type I to produce a novel nanohybrid.
Temperature-modulated DSC studies of time evolution of the polymorphic structure of PA6/clay nanocomposites
Authors: Zhao Xiong-Yan 
Published: August 2014

AbstractTwo PA 6/clay nanocomposites, NCN5 and NCN10 with 5 and 10% (wt %) clay, respectively, were prepared by a twin screw extruder. The effects of annealing including solid-state annealing and melt-state annealing on the polymorphic behavior and thermal property of nanocomposites have been comparatively studied as a function of annealing time using Modulated Differential Scanning Calorimetry (MDSC). It was demonstrated that NCN5 and NCN10 exhibit a similar polymorphic behavior when they were annealed in solid-state for different durations. As the annealing temperature was elevated to 245 °C (melt-state annealing), significant differences in thermal behavior and polymorphism between NCN5 and NCN10 could be found. For NCN5, the α structure became the absolutely dominating crystalline phase independent of the annealing durations, for NCN10, however, the formation of γ structure is greatly enhanced and longer annealing time would amplify this phenomenon. Moreover, a low-temperature endothermic peak was observed around 180 °C in both NCN5 and NCN10 samples which was also found to strongly depend on the thermal history.
Rheology, morphology and mechanical properties of LLDPE/PS blends catalyzed by combined Lewis acids
Authors: Liu Yan-Long , Yin Li-Gang , Ke Zhuo , Shi Qiang , Yin Jing-Hua 
Published: August 2014

AbstractThe rheological, morphological and mechanical properties of LLDPE/PS blends with a combined catalyst, Me3SiCl and InCl3·4H2O, were studied in this work. The higher complex viscosity and storage modulus at low frequency were ascribed to the presence of graft copolymers, which were in situ formed during the mixing process. From the rheological experiments, the complex viscosity and storage modulus of reactive blends were higher than the physical blends. The dispersion of LLDPE particles of reactive blending becomes finer than that of physical blends, consistent with the rheological results. As a result of increased compatibility between LLDPE/PS, the mechanical properties of reactive blends show much higher tensile and Izod impact strength than those of physical blends.
Preparation and characterization of hyperbranched polyimides based on 4,4’,4’’-triaminotriphenyl-methane
Authors: Sysel Petr , Minko Evgenia , Čechová Radana 
Published: August 2014

AbstractThis work focuses on the preparation and characterization of novel hyperbranched polyimides based on commercially available 4,4,’4’’- triaminotriphenylmethane and pyromellitic dianhydride or 4,4’-oxydiphthalic anhydride. The bi- and trifunctional monomers were reacted in a molar ratio of 1:1 or 2:1 to prepare polyimide precursors (hyperbranched polyamic acids) endcapped with either amino or anhydride groups. The precursors were then transformed into hyperbranched polyimides using thermal imidization. The final products were self-standing films, whose thermal behaviour was characterized by having no weight loss up to 250 ºC and by having glass transition temperatures above 200 ºC. We monitored the permeability of carbon dioxide, organic vapours and water vapour through these membranes. We also compared the properties of these materials with linear polyimides based on 4,4’-methylenedianiline combined with either pyromellitic dianhydride or 4,4’-oxydiphthalic anhydride.
Thermal properties of novel clay containing nanocomposites based on low density polyethylene/ ethylene-octene copolymer blends
Authors: Baghaei Bahareh , Jafari Seyed Hassan , Khonakdar Hossein Ali , Ashabi Ladan 
Published: August 2014

AbstractThermal behaviour of low-density polyethylene (LDPE)/ ethylene-octene copolymer (POE)/ organo-montmorillonite (org-MMT) nanocomposites, prepared via melt compounding were studied by means of differential scanning calorimetry (DSC), thermogravimetry analysis (TGA) and dynamic mechanical thermal analysis (DMTA) techniques. These nanocomposites showed different levels of intercalated structures depending on clay content, blend composition and compatibilization. Addition of polyethylene grafted maleic anhydride (PE-g-MA), as a compatibilizer, improved the intercalation process. The nanocomposites with 5% org-MMT and 5% PE-g-MA showed improved storage modulus and thermal stability in dynamic mechanical and thermal analysis, respectively. The degradation trends of nanocomposites were almost similar to the neat blends in nitrogen environment, but in air atmosphere thermal stability of the nanocomposites increased. The DSC results showed that the org-MMT layers dispersed in the nanocomposites could act as nucleation agents for the crystallization of the LDPE matrix. The results indicated that clay dispersion and interfacial adhesion, and consequently thermal properties of nanocomposites, are greatly affected by addition of PE-g-MA.
Investigation and modeling of the thermal conductivity of PP/clay nanocomposites and PP/MWCNT nanocomposites
Authors: Nejad Shahryar Jafari , Golzary Aboali 
Published: August 2014

AbstractIn this study, polypropylene/clay nanocomposites were prepared by melt blending method and their thermal conductivity and the thermal conductivity of polypropylene/multi-wall carbon nanotube (MWCNT) nanocomposites were investigated and modeled. It is found that the thermal conductivity of the PP/Clay and PP/MWCNT nanocomposites is increased with increasing temperature. The thermal conductivity of the nanocomposites is improved due to incorporation of nanoclay and MWCNT compared with pure PP matrix
Study on micro-phase separation structure of poly(ethylene terephthalate)-poly(hexylene terephthalate) (PET-PCT) copolymer
Authors: Wang Yuan , Yang Shenglin , Li Guang 
Published: August 2014

AbstractPET-PCT copolyesters were prepared from terephthalic acid (PTA), ethylene glycol (EG) and 1,4-cyclohexane dimethanol (CHDM) through direct esterification and the subsequent polycondensation. The chemical composition and sequence length distribution of the copolyesters were investigated by 1H-NMR and 13C-NMR. The dynamic rheological behavior and dynamic mechanical property were studied by means of ARES-RFS and DMA. The results demonstrated that the obtained PET-PCT copolyesters were random block copolyesters and the content of PCT units incorporated was always greater than the feed and the numberaverage sequence length of each block in the copolyesters was in proportion to its content. The relation between storage modulus (G’) and frequency (freq) deviated from linearity as the frequency (freq) tend to zero (the terminal region effect), and the frequency band where the terminal region effect appeared would shift to higher value with the increasing content of PCT, suggesting the presence of phase separations. Moreover, two glass transition temperatures were observed from DMA curves, which revealed the incompatibility of PET segments and PCT segments, i.e. the micro-phase separation took place in PET-PCT copolyesters.
Fabrication of poly(lactic acid) scaffolds by a modified solvent casting/porogen leaching method
Authors: Gong Xinghou , Tang Chak Yin , Wong Chi Tak , Lu William Weijia , Zhang Yugang , Lam Wing Moon , Wu Shuping , Liu Jianing 
Published: August 2014

AbstractA modified solvent casting/particulate leaching (SC/PL) method was developed to fabricate thick three-dimensional poly(lactic acid) (PLA) scaffolds with controlled pore size and porosity, and much shorter processing time. The pasty mixture of PLA/CHCl3/NaCl was sealed in a Buchner funnel by a piston with a suction flask connected. A vacuum pump was used to facilitate the volatilization of solvent. The scaffolds were obtained by subsequent removal of NaCl in deionized water. The pore size within the scaffold was in good accordance with the particle size of NaCl (< 210, 210~310, 310~420 and 420~500 μm), all of which had more than 89 % of porosity, 1.95 ± 0.2 MPa of compressive modulus and non-cytotoxic to L929 cells. To demonstrate the applicability of the SC/VV/PL method, thick cylindrical and tubular porous scaffolds have been produced in this study. Compared with the traditional SC/PL without vacuum volatilization, the modified method, namely, solvent casting/vacuum volatilization/particulate leaching (SC/VV/PL) method, provide a more efficient way to fabricate thick scaffolds.
Critical conversion in the processes of polymer formation
Authors: Irzhak Tamara F. , Irzhak Vadim I. 
Published: August 2014

AbstractRelations between the critical conversion of gelation αc and the conditions of polymer formation by living and terminated polymerization were studied. It was shown that the weight average functionality of the initial system given by the formula,Φ22(0)=∑ i(i-1)mi where mi is the initial concentration of an i-functional monomer, is the parameter determining the value of αc. Formulas relating the critical conversion to the kinetic parameters of polymerization processes are presented. For polycondensation processes the kinetic equation based on the concept of bond blocks is proposed. It allows for estimating the gel point even for systems in which the substitution effect takes place for one of the components. The equation α ∑ i(i-1)ni=1 is , where α is the current conversion and ni are the values specifying the concentrations of i-functional blocks. The latter values are functions of α and may be calculated kinetically.
The effect of vinyl benzyl chloride on emulsion polymerization of styrene
Authors: Chaabouni Amel , Massardier-Nageotte Valerie , Elleuch Boubaker , Chehimi Mohamed M. , Elaissari Abdelhamid 
Published: August 2014

AbstractPolystyrene latexes were prepared, in the presence of, vinyl benzyl chloride (VBC) monomer. These particles were synthesized in surfactant-free batch radical emulsion polymerization of styrene and VBC monomer mixture, with 2,2’- azobis(2-amidino propane)di-hydrochloride (V50) initiator. The polymerization kinetics was found to be rapid, as a function of VBC monomer concentration in the polymerization recipe. It is interesting to notice that high VBC amount leads to marked coagulum formation. The final hydrodynamic particle size was found to be slightly sensitive to the VBC concentration in the investigated range. The presence of VBC at the surface of the particles was investigated by XPS analysis.
Liquid crystalline polyureas with oligo(ethylene glycol) sequences
Authors: Mehdipour-Ataei Shahram , Akbarian-Feizi Leila 
Published: August 2014

AbstractA diamine monomer containing ester, amide and ether functional groups was prepared and its polymerization reaction with different diisocyanates to give main chain poly(ester amide ether urea)s was investigated. The monomer was synthesized via reaction of terephthaloyl chloride with 4-hydroxybenzoic acid and subsequent reaction of the resulted diacid with 1,8-diamino-3,6-dioxaoctane. The polymers were characterized by FT-IR and 1H-NMR spectroscopic method and elemental analysis. The resulting polymers exhibited excellent solubility in polar solvents. Crystallinity of the resulted polymers was evaluated by wide-angle X-ray diffraction (WXRD) method, and they exhibited semi-crystalline patterns. The glass transition temperatures (Tg) of the polymers determined by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) were in the range of 88-112 °C. The temperatures for 10% weight loss (T10) from their thermogravimetric analysis (TGA) curves were found to be in the range of 297-312 °C in air. Also the prepared polyureas showed liquid crystalline character.
Synthesis and characterization of novel value added biodegradable poly(aleuritic acid) from renewable resources (shellac) and invertible amphiphilic behaviors in various solvents
Authors: Pandey Asutosh K. , Nande Smita S. , Selukar Balaji S. , Garnaik Baijayantimala 
Published: August 2014

AbstractA novel biodegradable polymer poly(aleuritic acid) (PAA) ( M̄w 120,000) was prepared from aleuritic acid, which was obtained from renewable resources (Lac) by using tin catalyst. Aleuritic acid (AL) was protected at 9, 10 position by dimethoxy propane. The protected AL (Pro.AL) was further polymerized to obtain linear protected polyaleuritic acid (PAL) by dehydropolycondensation. Effects of various kinetic and thermodynamic parameters were studied. After polymerization, the deprotection of PAL was carried out. The synthesized PAL and PAA were characterized by using various techniques such as FT-IR, LC-MS, SEC, NMR (1H and 13C), 13C CP/MAS (Cross Polarization / Magic Angle Spinning) of solid PAA, DSC, SEM and TEM etc. The micelle and inverted micelle -structure in polar and nonpolar solvents are highlighted.
Curing kinetics study of epoxy resin/hyperbranched poly(amideamine)s system by non-isothermal and isothermal DSC
Authors: Zhang Li , Yang Hui Kang , Shi Guang 
Published: August 2014

AbstractCuring kinetics of epoxy resin/hyperbranched poly(amide amine)s (HPAMAM) system was studied by non-isothermal and isothermal differential scanning calorimetry (DSC). Non-isothermal DSC scans indicated that H-PAMAM was an effective curing agent of epoxy resin. The apparent activation energy (E) was 54.3 kJ/mol calculated through Kissinger method, and the kinetic parameters were determined by Málek method for the kinetic analysis of the thermal treatment obtained by DSC measurement. A two-parameter (m, n) autocatalytic model (Sěsták-Berggren equation) was found to be the most adequate selected kinetic model. In addition, the predicted curves from the kinetic model fit well with the nonisothermal DSC thermogram. The isothermal DSC method was used to investigate the curing process for resin at 60, 65, 70, 75 and 80 °С, respectively. Isothermal kinetic parameters, including k1, k2, m and n, were determined based on an autocatalytic mechanism proposed by Kamal. Both models were validated for a fitting to the experimental data by the Levenberg-Marquardt method. A process to determine the initial values for the fitting procedure was also proposed. The predictions of the validated models were in good agreement with the measured data, and were therefore applicable for numerical process optimization
Nitroxide-mediated polymerization of styrene in the presence of a novel trinitroxide
Authors: Li Jieai , Zhang Zhengbiao , Zhu Xiulin , Zhu Jian , Cheng Zhenping 
Published: August 2014

AbstractThe bulk polymerizations of styrene were performed in the presence of a novel trinitroxide, 2,4,6-tri(4’-oxy-2’,2’,6’,6’-tetramethyl-1’-piperidinyloxy)-1,3,5- triazine (TTPT). Typical features of controlled polymerization were observed, such as the first-order kinetics, the molecular weights (Mn) linearly increased with the conversion, and relatively narrow molecular weight distributions (Mw/Mn). The 1H NMR was used to characterize the obtained polystyrene. The most of obtained polymers at 110 °C were the polymer with two-arm linear structure, not the expected three-arm structure, which was confirmed by the analysis of degradation of obtained polymer by ascorbic acid. A proposed polymerization route of styrene mediated by TTPT was also discussed.
Investigation of gel-spun PAN fiber morphology by membrane technology techniques
Authors: Ma Caixia , Qin Zongyi , Pan Ding 
Published: August 2014

AbstractThe as-formed structure of gel-spun polyacrylonitrile (PAN) fiber from the solvent mixture system has been probed exploiting AFM techniques developed in the membrane industry. The surface structure of PAN membranes, prepared by phase transition under different casting conditions, was investigated by tapping mode atomic force microscopy. The results obtained show that the size and the density of these aggregates are dependent on the casting solution, namely on the type and concentration of the non-solvent. In the present work, tapping mode atomic force microscopy is used to comply with the main objective of differentiating surface morphologies of membranes.