bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organic‐inorganic hybrid sol‐gel materials, 1. Preparation and characterization
Authors: Yang Jen Ming , Chen Hao Sheng , Hsu Ying Gev , Wang Winston 
Published: April 2003

AbstractThree organic‐inorganic hybrid materials have been prepared by incorporating poly(styrene‐co‐methyl methacrylate) (poly(St‐co‐MMA)), poly(methyl methacrylate) (PMMA), and polystyrene (PS) structure units covalently into the SiO2 glass network via the sol‐gel approach. The polymer precursors were synthesized by freeradical copolymerization of styrene and/or methyl methacrylate with 3‐(trimethoxysilyl)propyl methacrylate (MSMA) to obtain the poly(St‐co‐MMA‐co‐MSMA) copolymer (molar ratio St/MMA/MSMA = 30/48/22), poly(MMA‐co‐MSMA) copolymer (molar ratio MMA/MSMA = 76/24), and poly(St‐co‐MSMA) copolymer (molar ratio St/MSMA = 69/31) with glass transition temperatures at about 67°C, 68°C, and 61°C, respectively. The characteristics and properties of the copolymers were characterized by 1H NMR, Fourier‐transform infrared spectroscopy (FTIR), gel‐permeation chromatography (GPC), elemental analysis, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The copolymers were then hydrolysed and co‐condensated with tetraethyl orthosilicate (TEOS) in tetrahydrofuran at room temperature to afford monolithic poly(St‐co‐MMA)SiO2, PMMASiO2, and PS‐SiO2 hybrid sol‐gel materials having SiO2 contents of 16–84 wt.‐%. The thermal properties of the hybrid materials were characterized by TGA and DSC.
α,ω‐Difunctional oligo(oxyethylene)‐based crosslinked resins as solid‐liquid phase transfer catalysts
Authors: Teodorescu Mircea , Dimonie Mihai , Languri Jean 
Published: April 2003

AbstractCrosslinked resins were prepared from α,ω‐diglydicyl and α,ω‐dimethacryloyl oligo(ethylene oxide)s by anionic polymerization with triethylenediamine/n‐pentanol initiating system or by free‐radical polymerization, respectively. Their activity as solid‐liquid phase transfer catalysts was proved in the reaction of 1‐bromobutane with potassium phenoxide, and compared with the activity of similar resins synthesized from α,ω‐diglycidyl oligo(ethylene oxide)s and triethylenetetramine (TETA). The catalytic activity of dimethacryloyl resins was higher than that of diglycidyl resins for oligomer chains longer than 6–7 oxyethylene units, whereas the opposite was true for resins of shorter chain lengths. These differences were explained by an unlike graft content of the resins in the former case, and by a different ability to complex the potassium cation into the meshes of the resin lattice, in the latter. In order to improve the catalytic activity of the resins two methods were developed consisting in the increase of the number of grafts either by decreasing the ratio of TETA/epoxy end groups used to the crosslinking of diglycidyl oligomers or by adding 2‐mercaptoethanol as a transfer agent to the free‐radical crosslinking process of dimethacryloyl oligo(ethylene oxide)s.
Structure and properties of poly(vinylamine)‐metal complexes
Authors: Rivas B. L. , Seguel G. V. , Geckeler K. E. 
Published: April 2003

AbstractCoordination polymers of poly(vinylamine) with copper, nickel, or cobalt have been prepared. Only the polychelate with copper was soluble in water. Elemental analysis, as well as magnetic, spectral, and thermal properties, and electrical conductivities (σ) of the chelates were investigated and probable structures were assigned to the chelates. All the polychelates were found to include water. The highest values of σ0 corresponded to the polychelates with Ni(II) (7.4 Ω 10−5 σ−1 Ω cm−1) and with Cu(II) (8.3 Ω 10−5 Ω−1 Ω. cm−1). The polychelate with Ni(II) shows the highest thermal stability.
Redox copolymer with N‐bromosulfonamide groups for the decomposition of cyanide ions in dilute aqueous solutions
Authors: Kociołek‐Balawejder Elżbieta 
Published: April 2003

AbstractA redox copolymer, macroporous poly(styrene‐co‐divinylbenzene) (S/DVB) resin having N‐bromosulfonamide groups, was used for removal of cyanide ions from aqueous solutions. This resin contains active bromine in functional groups (1.86 mmol g−1, i. e. 3.72 meq g−1) and shows oxidative properties. It was employed in static and flow system for oxidation of cyanide ions to non‐toxic compounds. The reactions were carried out in aqueous media containing 26–2600 mg L−1 CN− at different pH values. The data showed that the resin having active bromine easily oxidized cyanides, forming cyanates being 1000‐times less toxic than cyanides. In contact with the resin the concentration of cyanides in tested solutions dropped below 0.05 mg L−1 CN−. During the oxidation processes the SO2NBrNa groups transform to SO2NH2 groups. They can be reactivated by use of sodium hypochlorite and bromide solutions. As an alternative to oxidation of cyanides by N‐bromosulfonamide resin, the oxidation of these ions by N‐chlorosulfonamide resin with addition of a small amount of bromides was examined.
Morphology and mechanical properties of poly(propylene)/polystyrene blends compatibilized with polystyrene‐block‐poly(ethylene‐co‐propylene)
Authors: Radonjič Gregor , Musil Vojko 
Published: April 2003

AbstractCompatibilizing effects of diblock copolymer polystyrene‐block‐poly(ethylene‐co‐propylene) (SEP) on the morphology and mechanical properties of immiscible blends of poly(propylene) (PP) and polystyrene (PS) were investigated. Notched impact strength, yield stress, elongation at yield and Young's modulus were determined as a function of different weight ratios of PP and PS and different amounts of added SEP as well. Scanning electron microscopy revealed a two‐phase morphology of PP/PS blends, which exhibit poor mechanical properties.Even 2,5 wt.‐% of SEP added to PP/PS blends can improve the notched impact strength and elongation at yield compared to non‐compatibilized PP/PS blends. 10 wt.‐% of SEP compatibilizer converted the brittle PP/PS blend to quite impactresistant polymeric material. Mechanical properties were improved because of the morphological changes and increased interfacial adhesion as a result of SEP localization between PP and PS phases.An analysis of yield stress data in terms of theoretical models showed that yield stress values of binary PP/PS blends can be predicted with Nielsen's model.
Polymerization of 1,3‐butadiene with neodymium chloride/2‐ethylhexanolate/triethylaluminium catalyst system
Authors: Rao G. S. Srinivasa , Upadhyay V. K. , Jain R. C. 
Published: April 2003

AbstractNeodymium chloride 2‐ethylhexanolates of the general formula NdCl3 · nL were prepared by ligand exchange reaction between neodymium chloride ispropanolate (I) and 2‐ethylhexanol (EH). These hexanolates, NdCl3 · 1.5 EH (II) and NdCl3 · 2.5 EH (III), were characterized by elemental analysis and gravimetry. The catalytic activity of these hexanolates in combination with triethyl aluminium in the homopolymerization of 1,3‐butadiene was studied, and the activity was found to be higher with III than II. The conversions increased with increasing the catalyst and co‐catalyst concentrations and the temperature, whereas the intrinsic viscosity decreased. The conversions and the intrinsic viscosity decreased. The conversions and the intrinsic viscosity increased with reaction time. The cis‐1,4 structure was influenced by variation in temperature and co‐catalyst concentration, however, the total cis‐1,4 structure was always more than 99% with very low vinyl content (>1%). Addition of an external electron donor decreased the cis‐1,4 content to 87%.
The role of sulfur dioxide and nitrogen dioxide on the degradation of polymers
Authors: Dulog L. 
Published: April 2003

AbstractThe photodegradation of poly(tert‐butyl methacrylate) (PtBMA) and polystyrene (PS) films under 100 ppm sulfur dioxide and 100 ppm nitrogen dioxide in air and mixtures of the gases in air at constant temperature (30 °C) and relative humidity (30 %) was studied. in the presence of sulfur dioxide and nitrogen dioxide, under irradiation the polymers show a rapid degradation, while the thermal degradation is very small as well as the photodegradation in air. Peroxide groups in the polymer have an accelerating effect on the photodegradation in presence of the gases as well as dew and dry cycles (15 min each).An equation was derived to characterize the degradation by a linear and an autoacceleration factor.
Hydrolytic and thermal stability of novel polyurethane elastomers
Authors: Furukawa Mutsuhisa 
Published: April 2003

AbstractNovel Polyester glycols with alkyl side groups were used for the improvement of thermal stability and hydrolytic stability of polyester urethane elastomers. The novel polyester glycols used are poly( β ‐methyl‐ δ ‐valerolactone)glycol (PMVL), poly(3‐methyl pentamethylene adipate) glycol (PMPA), poly(nonamethylene‐co‐2‐methyl octamcthylene carbonate) gycol (PNCO). A mixture of PNCO and poly(dimethyl siloxane)gycol (PNCO/PDMS) was also used. Polyurethane network elastomers were prepared from 4,4′‐diphenylmethane diisocyanate (or 2,4‐tolylene diisocyanate), and a mixture of 1,4‐butane diol and trimethylol propane by a prepolymer method. Mechanical properties, Tg, thermal stability, and hydrolytic stability were measured. Morphology were also measured by means of polarizing microscopy, dynamic viscoelastometer, and ESR. The properties of novel polyurethane elastomers have good mechanical properties comparable to those of the general purpose polyester urethanes, and better thermal and hydrolytic stability than PTMG‐based polyurethane. These polyurethane elastomers were exposed in out door during 2 year in Nagasaki, JAPAN. The novel polyurethane clastomers held alomost constant values for gel fraction, swelling ratio, relative modulus during 12 months, while poly(oxytetramethylene oxide)‐based polyurethane as a control decreased the these values. Relationship of degradation behaviors with chemical structure and morphology were discussed.
Aging in nonlinear optical polymer waveguides
Authors: Lindsay Geoffrey A. , Roberts M. Joseph , Nadler M. P. , Yee R. Y. 
Published: April 2003

AbstractThe role that polymers will play as optical waveguides in the photonic communications revolution is described, including examples of polymer photonic devices, physical and optical requirements, aging mechanisms, competing materials, electric‐field poled polymer films, room‐temperature processed polymer films, and analytical methods for studying physical aging. Several important recent aging studies on nonlinear optical polymers, both thermoplastic and thermoset, are reviewed.
Calculated and measured outdoor UV doses
Authors: Pickett James E. , Webb Karen K. 
Published: April 2003

AbstractThe ultraviolet (UV) radiation dose received by a sample is often the determining factor in its outdoor weathering lifetime. However, little relevant data exist for UV doses except for certain standard locations and orientations such as for the commercial test sites in Florida and Arizona. We have modified a computer program by Jokela based on other atmospheric radiation models in the literature to calculate UV doses for any latitude and orientation relative to standard exposure in Florida and have used the fraction of sunshine data for various sites that are readily available from meteorlogical compendia to correct for cloudiness. The usefulness of the calculations have been substantiated by examining the amount of yellowing in unstabilized polycarbonate films exposed at several orientations at six sites in the northern hemisphere. The calculations and doses inferred from the yellowing data are in generally good agreement, although there is increased error in highly cloudy regions and for the northerly exposures.
Chemiluminescence in thermal oxidation of rubbers under stress
Authors: Zlatkevich Lev 
Published: April 2003

AbstractThe thermal oxidative stability of 100 μm sulfur vulcanized latex film stretched to various extent was studied by means of the chemiluminescence technique in 130–160°C temperature interval. In the 130–150°C temperature region the induction period of oxidation increases with deformation, reaches a limiting value at about 60–70% and remains unchanged up to 200%. This effect becomes less pronounced as temperature rises from 130 to 150°C and at 160°C no change in the induction period with the extent of deformation is observed. The oxidation rate constant exhibited different behavior. It was constant in the entire region of deformations studied at 130°C, while a slight increase at extensions exceeding 100% was noticed at higher temperatures. Original sample exhibited a substantially reversible deformation at ambient conditions even when stretched 200% for 1 hour. On the other hand, preliminary 200% stretching for 30 min under nitrogen at 150°C led to 67% residual deformation at room temperature. The latter sample was found to be essentially less stable than the unstretched material. Surprisingly enough, 100% elongation imposed on the sample with residual deformation resulted in the improvement in stability which was primarily due to the rise in the induction period value. The activation energy of oxidation was 62.8 kJ/mol for unstrained and about 12.6 kJ/mol less for all strained samples.
A very effective method for the cationic modification of cellulose
Authors: Petzold Gudrun , Schwarz Simona , Buchhammer Heide‐Marie , Lunkwitz Klaus 
Published: April 2003

AbstractThe interaction between the oppositely charged polymers poly(diallyldimethylammonium chloride) (PDADMAC) and poly(maleic acid‐co‐α‐methylstyrene) (P(MAMS)) in the presence of cellulose can be used for strong surface modification. The dependence of the modification effect on the concentration of polymers and on the method of modification is investigated in detail. Different methods are applied to the characterization of the effect, e.g. polyelectrolyte titration, adsorption of an anionic dye, or measurement of zeta potential (streaming potential). All of these methods can represent the results very well under certain conditions. Polyelectrolyte titration is correlated to the outer layer of the modified material, whereas dye adsorption is sensitive rather to the inner surface region and is very time‐dependent. Another significant value is the isoelectric point, which is shifted to higher pH in dependence on the quantity of surface charges. The stability of modification, tested with different methods, was shown to be very good for water and good for treatment with hydrochloric acid.
Functionalized polyisobutenes by SH‐en addition
Authors: Gorski Ute , Maenz Karsten , Stadermann Dietmar 
Published: April 2003

AbstractLow molecular weight polyisobutenes can be transformed into macromonomers by means of SH‐en addition, provided that the thiols contain an additional hydroxy group. The product structures formed by free‐radical or electrophilic addition reactions can be determined on model compounds as well as on the polymers by 1H‐ and 13C‐NMR spectroscopy.
Gas separation with organo‐soluble high performance aromatic polyimide films
Authors: Li Baozhong , Fan Guangyu , He Tianbai , Ding Mengxian 
Published: April 2003

AbstractAn organo‐soluble polyimide based on 4,4′‐(1,4‐phenylenedioxy)diphthalic anhydride and 2,2′‐dimethyl‐4,4′‐methylenedianiline was synthesized by two‐step polycondensation accompanied by chemical imidization. Polyimide films were prepared by spray casting onto glass substrates. The study focused on the separation of carbon dioxide (CO2) from natural gas and the enrichment of methane (CH4) from butane (C4H18). The permeability and permselectivity coefficients of these gases were determined.
Synthesis and characterization of polyazomethine conducting polymers and oligomers
Authors: El‐Shekeil Ali G. , Hamid Saad‐Addin M. K. , Ali Dheya A. 
Published: April 2003

AbstractConjugated polyazomethine polymers were prepared from the polycondensation of terephthalaldehyde with 4,4′‐thiodianiline, and 4,4‐thiodibenzaldehyde with 4,4′‐thiodianiline, 4,4′‐phenylenediamine and benzidine. The polymers showed good stability in air and were soluble in many organic solvents. The electrical conductivities of the undoped and doped (H2SO4 and I2) polymers were studied. Doping the polymers markedly increased their conductivities from 10−8 − 10−11 S cm−1 (dielectric region) to 10−3 − 10−5 S cm−1 (semiconducting region). The polymers were characterized by IR spectroscopy, elemental analyses, viscosity measurements and X‐ray diffraction.Furthermore, polyazomethine oligomers were prepared and a comparative study of the physical properties of the oligomers and their corresponding polymers was performed. The electrical behavior of the oligomers was studied. It was found that oligomers with a minimum of eight aromatic (Ar) rings gave almost the same electrical conductivities as long‐chain polymers.
Synthèse d'une résine antistatique par introduction de sites ioniques dans le système Epikote 1001®‐Euredur 423®
Authors: Bonnans‐Plaisance Chantal , Cheradi Karim , Gressier Jean Claude , Greuin Odile , Nakache Evelyne 
Published: April 2003

AbstractLe but de cette étude est d'apporter des propriétés antistatiques durables à la résine époxy obtenue à partir d'Epikote 1001® et d'Euredur 423®. Deux composés pouvant se lier chimiquement à la résine ont été choisis: le chlorure de (2,3‐époxypropyl)triméthylammonium qui contient un groupe époxy comme l'Epikote 1001® et un groupement chlorure d'ammonium pour les propriétés antistatiques et le 2‐aminoéthanesulfonate de tétrabutylammonium qui contient un groupement amine comme l'Euredur 423® et le groupement sulfonate. Différentes formulations de la résine ont été préparées avec ces deux composés. Leur viscosité et leur résistivité ont été mesurées. Des propriétés antistatiques ont été observées avec des échantillons à taux élevé de composé époxyde. Par contre, le composé à groupement amine n'a montré aucune propriété antistatique. Des tests de dureté et d'adhérence se sont révèlés intéressants pour les formulations présentant des propriétés antistatiques.
The state of water in styrene‐grafted and sulfonated poly(vinylidene fluoride) membranes
Authors: Hietala Sami , Holmberg Svante , Näsman Jan , Ostrovskii Denis , Paronen Mikael , Serimaa Ritva , Sundholm Franciska , Torell Lena , Torkkeli Mika 
Published: April 2003

AbstractThe state of water in proton exchange membranes prepared by pre‐irradiation (electron beam, 100 kGy) grafting of styrene onto poly(vinylidene fluoride) films (PVDF‐g‐PS), followed by sulfonation (PVDF‐g‐PSSA), has been studied with thermal analysis, Raman spectroscopy and small angle X‐ray diffraction (SAXS). Raman spectra show that, in addition to free liquid water in the membranes, single water molecules are weakly bound to the polymer backbone. Thermal analysis shows that there are three types of water molecules in the membrane; non‐freezable water associated with the ionic sites, freezable free water, and freezable bound water. The amount of non‐freezable water is around 10 H2O/SO3H (mol/mol), and is independent of the degree of grafting (d.o.g.). The amount of freezable water is strongly dependent on the d.o.g. as long as the grafting has not penetrated the whole of the film, and reaches a value of around 40 H2O/SO3H (mol/mol) above a d.o.g. of 50%. The conductivity of membranes containing only the non‐freezable water is low, i. e. the ionically bound water alone does not form the domains necessary for proton and water transport. SAXS measurements show that water/sulfonic acid clusters in hydrated PVDF‐g‐PSSA membranes with a Bragg distance of 25 Å are formed; these form the ion conducting channels in the membrane.
Metallization of poly(vinylidene fluoride) by reduction of polymer‐incorporated metal ions
Authors: Shibata Mitsuhiro , Yosomiya Ryutoku , Yosomiya Takatoshi 
Published: April 2003

AbstractThe metallization of poly(vinylidene fluoride) (PVdF) films by reduction of polymer‐incorporated metal chlorides and perchlorates with an aqueous NaBH4 solution was investigated. The conductivity of the metal layers deposited by reduction decreased in the order Cu2+ > Ni2+ > Co2+ > Fe3+ regarding the metal cation, and in the order of Cl− > ClO−4 regarding the counter anion. The high conductivity of the Cu layer deposited from PVdF containing CuCl2 is thought to be attributed to the facts that no side‐reaction occurs during the reduction in contrast to the formation of metal boride in CoCl2 and NiCl2 systems and iron oxides in FeCl3 system, and the surface of the Cu layer is smooth as compared with that obtained with the Cu(ClO4)2 system.
Tensile and flexural behavior of polypropene sheets with different crystallinities of surface layer
Authors: Kawamoto Naoshi , Mori Hideharu , Yui Nobuhiko , Nitta Koh‐hei , Terano Minoru 
Published: April 2003

AbstractThe tensile and flexural moduli of the compression‐molded sheets of polypropene with different surface layer crystallinity were investigated based on a layered composite model. It was found that the tensile stress‐strain curve and flexural deflection depended largely on the surface layer crystallinity, but the ultimate strain‐at‐break values were independent of the surface layer crystallinity. It is suggested that the tensile and flexural behavior can be characterized using a layered composite model in which a bulk plate was sandwiched between two surface layers.
Polymer composition versus low‐temperature characteristics of polysiloxane elastomers
Authors: Polmanteer K. E. , Hunter M. J. 
Published: April 2003

AbstractGehman cold‐flex, volume‐temperature, and stress‐temperature studies were used to investigate the low‐temperature characteristics of polysiloxane copolymers with respect to copolymer composition. A complete range of phenyl methyl‐dimethyl siloxane copolymers were examined as elastomeric compounds. Like other copolymers, the stiffening temperature was dependent upon the composition of the copolymer. Stiffening of the elastomers was due to crystallization in some cases and second‐order transition in others. Copolymers having either low or high amounts of PhMeSO stiffened because of crystallization, while copolymers of intermediate composition (7.5 to 15 mole‐% PhMeSiO) stiffened because of nearness to their respective second‐order transition temperatures. Second‐order transition temperature increased with the PhMeSiO content. For those siloxane polymers and copolymers that crystallized, the process was rapid when compared with crystallization behavior of other polymer systems. Only one minimum low‐temperature stiffening point was found in the phenyl methyl‐dimethyl siloxane copolymer system. The unique low‐temperature characteristics of polysiloxane elastomers are explainable on the basis of three factors. These are: (a) very flexible molecules, (b) low temperature coefficient of viscosity over a broad temperature range including low temperatures, and (c) copolymerizability of dimethyl siloxane with other siloxanes containing bulky pendant groups which lower the stiffening temperature.
Anisotropic properties of strained viscoelastic fluids. I. A method for measuring strain birefringence
Authors: Gill Stanley J. 
Published: April 2003

AbstractA mechanism has been devised for the purpose of introducing a sudden strain of calculable amount into a viscoelastic fluid. The principle of the apparatus relies upon the deformation caused by the rotation of an elliptical sleeve about a flexible tube containing polymer solution. An apparatus has been constructed which can produce a 90° rotation (with consequent deformation) in the period of one millisecond. The detection of the strained state is accomplished by means of strain birefringence. In this way, relaxation can be studied in concentrated solutions for a time range beyond one millisecond.