bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proton irradiation of ultra high molecular weight polyethylene for space applications
Authors: Stephens C.P. , Benson R.S. , Ling X. , Song H. , Ham H.-J. , Buchanan R.A. , Chipara M. 
Published: August 2014

AbstractThe effect of low dose proton irradiation on the morphology of ultra high molecular weight polyethylene (UHMWPE) was studied. The integral proton dose was ranging from 900 Gy to 1200 Gy. The experimental data revealed that low dose proton irradiation in the presence of oxygen leads to the formation of intermolecular crosslinks in UHMWPE and that proton irradiation produces morphological changes that involve a reduction in the thickness of the interfacial region and increase in the thickness of the amorphous region. The observed morphological changes depend on the integral dose
Optically active poly(ester-imide): synthesis and characterization of new optically active poly(ester-imide) thermoplastic elastomers
Authors: Hajipour Abdol Reza , Zahmatkesh Saeed , Ruoho Arnold E. 
Published: August 2014

AbstractThis Paper deals with the polycondensation between a chiral diacyl chloride (2-(N,N’-pyromelliticdiimido)-bis-propanoic acid chloride (4)) and polyethyleneglycol-diol (PEG-200) and/or three synthetic aromatic diols. The corresponding new PEIs and Co-PEIs which have been obtained in quantitative yields are soluble in polar aprotic solvents, have good thermal stability and optical activity.
Aromatic-aliphatic copolyesters based on waste poly(ethylene terephthalate) and their biodegradability
Authors: Prokopová Irena , Vlčková Eva , Šašek Václav , Náhlík Josef , Soukupová–Chaloupková Veronika , Skolil Jan 
Published: August 2014

AbstractThe solvolysis of poly(ethylene terephthalate) from disposed beverage bottles by an aqueous solution of lactic acid, followed by the zinc acetate catalyzed polycondensation of the solvolytic product, yielded a series of aromatic-aliphatic copolyesters containing up to 55 mol.% of incorporated lactic acid structural units. Their molecular parameters were determined using SEC and viscometry. According to DSC, the copolyesters have amorphous structure. Selected copolyester samples were subjected to abiotic hydrolysis at pH 7 and 60 °C. After three days of hydrolysis, the mass of the samples decreased substantially and their molar mass was reduced. At 37 °C, strong degradation of copolyesters by action of the actinomycete Rhodococcuserythropolis was observed. Biodegradability of the copolyesters was confirmed by a composting test. In addition to the changes of the molecular structure of the composed samples, the physical degradation of the foils of the samples tested was also documented by SEM.
First application of electrosynthesized polyterthiophene to organic solar cells
Authors: del Valle M. Angélica , Soto Giovanny M. , Canales Luis I. , Canales Luis I. , Díaz Fernando R. , Bernède J. Christian 
Published: August 2014

AbstractPolyterthiophene (PTT) thin films have been electrosynthesized using potentiodynamic and potentiostatic methods. The optimal experimental conditions to prepare organic solar cells were determined by deposition of films on platinum and then the process was adapted to an indium tin oxide substrate. Surface morphology of films deposited by potentiostatic methods proved to be more homogeneous than films obtained by potentiodynamic methods. When PTT is employed in photovoltaic cells, the best results are attained using the latter technique. In these solar cells, the polymer is used as electron donor while N,N'- diheptyl-3,4,9,10-perylene-bis-carboximide (PTCDI-C7), deposited by vacuum sublimation, was the electron acceptor. The short circuit current is systematically small, probably due to the roughness of the polymer which induces high series resistance. In any case, it was demonstrated that the electrochemical method is suitable to prepare polymeric layers of electronic devices.
New polyurethane materials from renewable resources: synthesis and characterization
Authors: Macocinschi Doina , Filip Daniela , Vlad Stelian 
Published: August 2014

AbstractIn the present study new types of polyurethane-cellulose derivative biomaterials based on urethane prepolymers functionalized with hydroxypropylcellulose are presented. The aim of the present study is to obtain materials with better haemocompatibility, biocompatibility and amphiphilic microphase-separated domain structures. The outcome of remarkable chemical versatility characteristic to polyurethane materials combined with polymers derived from nature like cellulose derivatives resulting in bulk and surface properties is evidenced by means of different techniques like DSC, TGA, FT-IR, AFM and mechanical tensile tests. The influence of various factors on the developed morphologies and the microstructural changes is investigated. Both polyester and polyether macrodiols have been used to prepare these polyurethanes. The aim of this study is to find also alternative methods for improving biostability while maintaining the excellent biocompatibility and other properties.
Synthesis and Characterization of Highly Soluble and Heat Stable New Poly(amide-ether)s Containing Pyridine Rings in the Main Chain
Authors: Banihashemi Ahmad , Vakili Mohammad Reza 
Published: August 2014

AbstractA pyridine-based diacid containing ether linkage was synthesized via reaction of 2,6-dichloropyridine with 3-hydroxybenzoic acid in presence of potassium hydroxide in dimethyl sulfoxide (DMSO). The corresponding diacid chloride was synthesized by reaction of the diacid with oxalyl chloride. New poly (amide-ether)s were prepared by solution polycondensation reaction of the prepared diacid chloride with different commercial aromatic diamines. The synthesized polymers were characterized by elemental analysis, IR, and 1H NMR spectra, wide-angle X-ray diffraction, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC); inherent viscosity and solubility were studied. These polymers showed high thermal stability and good solubility.
Preparation and characterization of a novel spongy hydrogel from aqueous Bombyx mori sericin
Authors: Zhang Haiping , Yang Mingying , Min Sijia , Feng Qiang , Gao Xin , Zhu Liangjun 
Published: August 2014

AbstractWe attempted to obtain a novel spongy hydrogel from aqueous Bombyxmori (B. Mori) sericin by using a freeze-thaw method without any cross-linking reagent. The aqueous sericin solution utilized was extracted from silkworm cocoons by using boiling method, and showed continuous molecular weight distribution mainly from 43 kDa to 212 kDa and even higher. To optimize the conditions for hydrogel preparation, the efficiency of hydrogel transformation from sericin solution were investigated by changing sericin concentration, freezing time, freezing temperature and frozen-thawed repetition. The porous characteristics of sericin hydrogel including the porosity, density and maximal water absorbency were performed by changing freezingn conditions. The pore size and morphology of hydrogels prepared at different concentration and freezing temperatures were observed with SEM. FTIR, XRD and DSC curves indicate that the hydrogel prepared at -20 °C and -80 °C adopt mainly random coil conformation.
Synthesis, characterization, thermal stability, conductivity and band gaps of monomer and oligo-4-[(thien-2-ylmethylene) amino] phenol
Authors: Kaya İsmet , Aydın Aysel 
Published: August 2014

AbstractIn this study, the oxidative polycondensation reaction conditions of 4- [(thien-2-yl-methylene) amino] phenol (4-TMAP) by using oxidants such as air O2, H2O2 and NaOCl were studied in an aqueous alkaline medium between 313 and 363 °K. The structures of the synthesized monomer and oligomer were confirmed by FT-IR, UV-vis, NMR and elemental analysis. The characterization was made by TG-DTA, size exclusion chromatography (SEC) and solubility tests. At the optimum reaction conditions, the yield of oligo-4-[(thien-2-yl-methylene) amino] phenol (O-4- TMAP) was found to be 36% for air O2 oxidant, 40% for H2O2 oxidant and 47% for NaOCl oxidant. According to TG analysis, the weight losses of 4-TMAP and O-4- TMAP were found to be 58.11% and 51.38% at 1273°K, respectively. O-4-TMAP was shown higher stability against thermal decomposition. Also, electrical conductivity of the O-4-TMAP was measured, showing that the polymer is a typical semiconductor. The highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and electrochemical energy gaps ( ' gE ) of 4- TMAP and O-4-TMAP were found to be -6.13, -6.02; -2.72, -2.69; 3.41 and 3.33 eV, respectively.
Transient nucleation in isothermal crystallization of poly(3- hydroxybutyrate)
Authors: Sajkiewicz Pawel , Di Lorenzo Maria Laura , Gradys Arkadiusz 
Published: August 2014

AbstractThe time dependence of nucleation rate in isothermal crystallization of poly(3-hydroxybutyrate) was experimentally shown, both in heterogeneous and homogeneous nucleation. The time dependence of nucleation rate is one of the important limitations for the applicability of the simplified form of Kolmogoroff- Avrami-Evans model with time independent kinetic characteristics. The presented results are interpreted in terms of non-steady-state cluster size distribution underlying transient nature of nucleation. The relaxation time needed for reaching a steady-state cluster size distribution and thus steady-state nucleation rate is relatively long, exceeding the time of exhaustion of heterogeneities. The relaxation time estimated from homogeneous process was tens of seconds in the temperature range between 83 and 120 oC. Application of Arrhenius law allows estimation of relaxation time in broader temperature range, showing an increase of relaxation time with decreasing temperature.
Radiopaque acrylic bone cement with bromine-containing acrylic monomer. II
Authors: Rusu Marius Ciprian , Ichim Ionut Cameliu , Popa Marcel , Rusu Daniela , Rusu Mihai 
Published: August 2014

AbstractBromine-containing methacrylate, 2-(2-bromoisobutyryloxy) ethyl methacrylate (BIEM), had been used in the formulation of acrylic radiopaque cements. The effect of this monomer incorporated into the liquid phase of acrylic bone cement (ABC), on the curing parameters, thermal properties, water absorption, density, compression tests and radiopacity was studied. A decrease of maximum temperature and an increase of the setting time were observed with the addition of the brominecontaining monomer in the radiolucent cement composition. Adding BIEM in radiolucent ABCs composition results in the decrease of glass transition temperature and increase in its thermal stability. The ABCs modified with bromine-containing comonomer are characterized by polymerization shrinkage lower than the radiolucent cement. Addition of bromine-containing comonomer in radiolucent ABC composition determines the increase of compressive strength. The ABCs modified with brominecontaining comonomer proved to be radiopaque.
Predicting flow induced change in phase diagram of polymer solutions in simple shear flow
Authors: Mazinani Saeedeh , Sharif Farhad , Mohammadi Naser 
Published: August 2014

AbstractThe change in the phase diagram of polymer mixtures under flow is an important issue since flow may promote mixing or demixing of the phases in a polymer mixture. This work, compared to previous studies, presents a different approach with special attention to the rheology of polymer solutions and flow conditions. Different approaches including Marrucci's approach in calculating stored elastic free energy (ΔGE) have been reviewed. Marrucci’s equation is obtained based on a fundamental analysis of polymer chains microstructure. The new approach introduces the proper viscoelastic constitutive equations to estimate ΔGE. Selecting the appropriate rheological model is essential to correctly estimate the state of stress and deformation rates due to the flow. Moreover, the parameters of viscoelastic constitutive equations were defined, from the microstructural viewpoint, as functions of composition and temperature in semi-concentrated regions. Finally, flow induced change in the phase diagram of polymer solutions is predicted for a well-defined flow condition (constant shear rate and stress), and the results are compared with the previously reported experimental observations of mixing and demixing.
Anionic polyacrylamide “water-in-water” emulsion prepared by dispersion polymerization in mixed salt aqueous media
Authors: Lü Yongli , Feng Yujun , Zhao Yongfeng , Zhang Sheng , Shu Songkuang , Luo Pingya 
Published: August 2014

AbstractPolyacrylamide “water-in-water” emulsion was regarded as a new generation of water-soluble polymeric materials and has attracted much attention from both academia and industry because of its environmentally-friendly character. Anionic polymeric “water-in-water” emulsions prepared by dispersion polymerization of acrylamide (AM) and sodium acrylic acid (NaAA) in mixed solution of Na2SO4 and (NH4)2SO4 are reported in this paper, and the parameters influencing polymerization and the final dispersion stability, including, N2 flow rate, chain transfer agent content, inorganic salt content, and the molar ratio of AM to NaAA were examined and opitimized. It was found that the intrinsic viscosity of resulting copolymers decreased as the N2 flow rate and CTA concentration increased, and the resultant dispersions with 27 % ∼ 28 % inorganic salt have regular particle shape, lowest particle size, better flowability and storage stability. The salt level in the reaction system would also dominate the time that the dispersion formed, and the ratio of AM to NaAA would influence the total monomers conversion and polymerization rate.
Hyperbranched poly(amine-ester) polyol: Synthesis, characterization, thermal stability, solubility and surface activity
Authors: Xuechuan Wang , Xuzheng Yuan , Taotao Qiang , Xing Chen 
Published: August 2014

AbstractA series of hyperbranched poly(amine-ester) polyols were synthesized by the polycondensation of N,N-diethylol-3-amine-methylpropionate [prepared by the Michael addition reaction of methyl acrylate (MA) with diethanolamine (DEA)] as an AB2-type monomer with trimethylol propane (TMP) as the core moiety, proceeding in one-step procedure in the melt with p-toluenesulfonic acid (p-TSA)as catalyst. The Michael addition reaction and polycondensation behaviors were systematically investigated, in an effort to optimize the reaction conditions, respectively. Optimum parameters for addition reaction: at MA/DEA ratio of 2:1 for 4 h at 35 °C, adding MA to DEA, using methyl alcohol as solvent; and for polymerization: dosage of p-TSA was 2 wt % (based on total weight of AB2-type monomer and core) for 4~5 h at 120 °C, adding monomer to core. The obtained monomer and polymers were characterized by Fourier transform infrared spectroscopy (FTIR), 1H-NMR spectroscopy and gel permeation chromatography (GPC). It was suggested that the hyperbranched poly(amine-ester) polyol formed via a mechanism of a combination of transesterification and addition reactions. The thermal stability, solubility and surface activity in aqueous solution of the polymers were also examined.
Influence of side chain lengths of graft copolymers on compatibilization of homopolymer a/homopolymer b/graft copolymer ternary blends: a Monte Carlo Simulation
Authors: Zhu Yutian , Shi Dean , Jiang Wei , Yiu Li Robert Kwok 
Published: August 2014

AbstractThe Monte Carlo method was used to investigate the effect of graft length and architecture on the efficiency of compatibilization in A/B/graft copolymer ternary blends. In this study, homopolymer B is always dispersed phase. When the graft length of the copolymer is relatively short, A20Bn copolymers (A block is the backbone, and B block is the graft) tend to form micelles in the matrix phase, whereas the B20An (B block is the backbone, and A block is the graft) copolymers tend to form micelles in the dispersed phase. We also find that the micelles in the dispersed phase (formed by B20An copolymers) can effectively suppress the coalescence of the dispersed phases, whereas the micelles in matrix phase (formed by A20Bn copolymers) have no effect on suppressing the coalescence. As a result, when the graft length is relatively short, B20An copolymers can lead to smaller dispersed phases than A20Bn copolymers. Moreover, when the graft is relatively long, A20Bn copolymers were found to connect the dispersed phases and form netlike structure, whereas B20An copolymers were found to locate at the phase interface and anchor the dispersed phase and matrix phase. Furthermore, both A20Bn and B20An copolymers with relatively long graft lengths can well reduce the size of the dispersed phase.
Facile synthesis of fluorescent ABA type amphiphilic triblock copolymers via RAFT polymerization and their aggregation behavior in a selective solvent
Authors: Fu Junwei , Cheng Zhenping , Zhou Nianchen , Zhu Jian , Zhang Wei , Zhu Xiulin 
Published: August 2014

AbstractWell-defined naphthalene end-capped poly(styrene)-block-poly(Nisopropyl- acrylamide)-block-poly(styrene) (PS-b-PNIPAM-b-PS) amphiphilic triblock copolymers with different molecular weights and block copolymer compositions were successfully prepared via consecutive reversible additionfragmentation chain transfer (RAFT) polymerizations using a novel RAFT reagent, S,S'-bis(1-naphthylmethyl) trithiocarbonate (BNTTC). The aggregation behaviour of the prepared PS-b-PNIPAM-b-PS in water/DMF mixture was studied by transmission electron microscopy (TEM). The effect of the copolymer concentration, PNIPAM block length and the irradiation of UV-light on the sizes and morphologies of micelles were also investigated.
Synthesis and properties of novel polyimides containing 2,6-benzobisoxazole units
Authors: Meng Xiangli , Huang Yudong , Lv Zushun , Yu Hong 
Published: August 2014

AbstractThe diamine monomer, 2,6-bis(p-aminophenyl)-benzo-[1,2-d; 5,4-d’] bisoxazole was successfully synthesized. Three aromatic polyimides (PI) based on 2,6-bis(p-aminophenyl)-benzo-[1,2-d; 5,4-d’] bisoxazole were prepared via a conventional two-stage procedure with a variety of dianhydrides. Their structures and properties were characterized by FTIR, 1H NMR, TG, DSC and XRD. The intermediate poly(amic-acid)s (PAA) had inherent viscosities of 1.18-1.70 dL/g and could be thermally converted into lightly yellow polyimide films. The resulted polyimides showed excellent thermal stability, and the glass transition temperatures (Tg) of all polymers were above 280 oC, and the 5% weight loss temperatures of polymers were about 550 oC in N2. The solubility of these polyimides in various solvents was evaluated. They were all insoluble in conventional polar aprotic solvents.
Modification of cellulose by UV-grafting of an organopolysilazane oligomer
Authors: Serafini P.M. , Bongiovanni R. , Zeno E. 
Published: August 2014

AbstractThe modification of cellulose fibers by grafting specific functions could improve their quality and allow their use for the development of new products. In this work we report about the functionalization of a cellulose fiber network (filters) with organo-polysilazane oligomers by UV-irradiation. Photo-induced grafting, as assessed by contact angle and TGA measurements, was successful: an interesting enhancement of thermal resistance and mechanical properties was obtained. Water repellency was also achieved.
Thermal stability of ammonium salts as compatibilizers in polymer/layered silicate nanocomposites
Authors: Galimberti Maurizio , Martino Marco , Guenzi Monica , Leonardi Gabriella , Citterio Attilio 
Published: August 2014

AbstractThermal stability of alkyl and arylalkyl quaternary ammonium cation (onium) in starting chloride salt, in organoclay obtained after exchange with montmorillonite (MMT) and after mixing of the organoclay with isoprene rubber was examined using conventional TGA and by mass spectrometry pyrolysis/GC-MS. Degradation was observed to occur at T ≥ 170 °C for organoclays and the main volatile compounds were identified as tertiary amines, chloroalkanes and alkenes. Mechanisms for their formation are proposed and the role of residual onium chloride and basic centers of layered silicate is discussed.
Synthesis and basic properties of sulfonated polysulfone/phosphotungstic acid (H3O40PW12) composite proton exchange membrane
Authors: Li Weidong , Fei Guoping , Zhao Jiongxin 
Published: August 2014

AbstractThe sulfonated polysulfone/phosphotungstic acid (SPSU/PWA) composite membranes were investigated for proton exchange membranes. The influence of the interactions between sulfonic acid groups and phosphotungstic acid on the properties of composite membranes was studied in detail. The study showed that special interaction has great influence on the membrane properties. Fourier transform infrared (FTIR) spectroscopy of the composite membranes exhibited band shifts showing a possibility of intermolecular hydrogen bonding interaction between SPSU and PWA additives. SPSU/PWA composite membranes were evaluated for thermal stability, ion exchange capacity, water uptake and proton conductivity. Also the extraction of PWA from the composite membranes and their chemical stability were determined. Thermal analysis of the composites showed that it promotes the decomposition temperature of the sulfonic acid groups with increase in PWA weight content. Though the IEC and water uptake decreased with increase in PWA content, the proton conductivity of the composite membranes increased with increase in PWA content. The proton conductivity of the composites with 5 wt.%, 20 wt.% and 30 wt.% PWA is 2.62×10-2, 1.34×10-1 and 1.66×10-1 s·cm-1 at 80oC, respectively.
Preparation of epoxy/urethane graft interpenetrating polymer networks and study of mechanical, thermal and morphological properties
Authors: Ghafghazi Mehdi , Esfandeh Masoud , Morshedian Jalil 
Published: August 2014

AbstractThis paper describes the preparation of Epoxy/Urethane (EP/PU) graft interpenetrating polymer networks (g-IPNs) and investigates the effect of EP/PU weight ratio and urethane's prepolymer molecular weight on the mechanical, morphological and thermal properties of the IPN system. Here, g-IPN was prepared by thorough mixing of an isocyanate-terminated urethane prepolymer with an epoxy resin followed by simultaneous curing of the resins. Polytetra hydrofuranate (PTHF), molecular weights (Mw) 1000, 2000 and 3000 g/gmol, was used to prepare urethane prepolymers. EP/PU weight ratios were 75/25, 50/50, 30/70 and 15/85. Disappearance of epoxide and isocyanate functional groups was followed by Fourier Transform Infrared spectroscopy (FT-IR), showing curing of the resins. Differential Scanning Calorimetry (DSC) was used to investigate the glass transition temperature (Tg) of the IPNs. Thermal Gravimetric Analysis (TGA), Dynamic Mechanical Thermal Analysis (DMTA), tensile measurements and Scanning Electron Microscopy (SEM) were used to study thermal, mechanical and morphological properties of the prepared systems. The best mechanical properties were obtained at EP/PU weight ratio 75/25 which also shows a fine and uniformly dispersed morphology. Moreover, at this ratio, with increasing PTHF Mw in the urethane prepolymer, the mechanical properties were improved whereas a decrease was observed in Tg and thermal degradation temperature of g-IPNs.