bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study in the formation and characterisation of oxazolidone‐isocyanurate polymers using differential scanning calorimetry and infrared spectroscopy
Authors: Lee Yvonne S‐K , Hodd Ken , Wright William W. , Barton John M. 
Published: April 2007

AbstractEpoxy resins of functionality 2–4 were reacted with 4,4′‐diisocyanato diphenyl methane within the range of isocyanate to epoxide ratios of 0.5–1‐5 in the presence of 2‐ethyl‐4‐methyl imidazole to form oxazolidone‐isocyanurate polymers. The state and extent of cure of the resins were followed by infrared spectroscopy in conjunction with differential scanning calorimetry. The ratios of isocyanurate to oxazolidone linkages in the cured resins were determined quantitatively by an infrared method and the glass transition temperatures of the corresponding structures were measured by differential scanning calorimetry and dynamic mechanical thermal analysis.
Thermal and spectroscopic studies on flame‐retardant cotton cellulose modified with THPC‐urea‐ADP and its transition metal complexes
Authors: Bagga Swaran L. , Jain Rajesh K. , Gur Ishwar S. , Bhatnagar Hari L. 
Published: April 2007

AbstractCotton cellulose has been treated with tetrakis(hydroxymethyl)phosphonium chloride (THPC), urea and small amounts of ammonium dihydrogen orthophosphate (ADP) to impart flame retardancy. Complexes of cell‐THPC‐urea‐ADP with transition metals such as chromium, manganese, iron, cobalt, nickel, copper and zinc have been characterized by reflectance UV‐visible spectra. The samples were subjected to differential thermal analysis and thermogravimetry from ambient temperature to 700°C in air to study their thermal behaviour. From the resulting data, various kinetic parameters for different stages of thermal degradation were obtained following the method of Broido. For the decomposition of cellulose and flame‐retardant celluloses, the activation energy was found to increase from 242 to 322kJ mol−1, the entropy of activation from 140 to 307 JK−1 mol−1 and the char yield from 2.5 to 31%. The free energy of activation for decomposition of cellulose and its derivatives was almost the same, viz. 148–162 kJ mol−1, indicating that the basic steps in the decomposition of cellulose and its derivatives are the same. The IR spectra of the thermally degraded residues of cell‐THPC‐urea‐ADP and its metal complexes indicate that dehydration takes place and a compound containing the carbonyl group is formed. The electron paramagnetic resonance signals indicate the formation of trapped and stable free radicals in the thermal degradation of cellulose and its derivatives.
Synthesis of block copolymers based on oxyethylene chains and their use as polymer electrolytes
Authors: Wilson David J. , Nicholas Christian V. , Mobbs Richard H. , Booth Colin , Giles Jeremy R. M. 
Published: April 2007

AbstractHigh‐molecular‐weight copolymers were prepared consisting predominantly of oxyethylene and oxymethylene‐oligo(oxyethylene) blocks with a small 1‐phenylethylene block. Ionic conductivities of mixtures of the copolymers with CF3SO3Li were measured.
Preferential plasticization of SBS triblock copolymer
Authors: Canevarolo Sebastiao V. , Mattoso Luiz H. C. 
Published: April 2007

AbstractThermoplastic rubbers made of triblock copolymers of styrene‐butadiene‐styrene in commercial formulations are commonly used in conjunction with petroleum extender oils, in order to reduce the melt viscosity of the rubber during its processing. These mineral oils contain known quantities of paraffinic‐naphthenic and aromatic molecules, which in turn are preferably absorbed by the rubbery and glassy phases respectively, affecting selectively the copolymer domain structure and thus the rheological and mechanical properties. Using a plasticizer, the melt viscosity of the system is reduced due to the plasticization of the phases, as expected. The melt rheological transition temperature shown by the unplasticized block copolymer is still present in the oil extended formulations. The flow activation energy is affected by the temperature, type and content of plasticizer. For temperatures lower than the rheological transition temperature the aromatic oil gradually weakens and destroys the polystyrene aggregates and the paraffinic oil induces a greater segregation of the polystyrene aggregates. At temperatures above the rheological transition temperature the behaviour of the two is similar because the flow is homogeneous.
Glass fibre reinforced composites of triglycidyl‐p‐aminophenol
Authors: Thakkar Jatin R. , Patel Ravji D. , Patel Ranjan G. , Patel Vithal S. 
Published: April 2007

AbstractGlass fibre reinforced epoxy composites were fabricated from the matrix resins diglycidyl ether of bisphenol A (DGEBA) and triglycidyl‐p‐aminophenol (TGAP) using diethylene triamine as curing agent. The epoxy laminates were evaluated for their mechanical properties, dielectrical properties and chemical resistance. Significant improvement in fiexural strength but a slight deterioration in dielectrical properties were observed on incorporation of an epoxy fortifier into the resin system before fabricating the composites.
Mechanical properties of natural rubber/grafted cellulose fibre composites
Authors: Flink Per , Stenberg Bengt 
Published: April 2007

AbstractMechanical properties of natural rubber/allyl acrylate and allyl methacrylate grafted cellulose fibre composites are presented. Stress/strain measurements and dynamic mechanical measurements indicate that the adhesion between grafted fibres and matrix is better than that in samples containing untreated cellulose fibres. This makes it possible to vary the composite properties by varying the fibre type and/or fibre amount.
Measurement of transport properties of poly(methylmethacrylate‐co‐methacrylic acid) ion‐containing membranes
Authors: Şanli Oya , Aras Leyla 
Published: April 2007

AbstractSeveral membranes prepared from poly(methylmethacrylate‐co‐methacrylic acid) and its Li+ and Zn2+ ionomers were tested for NaCl, creatinine and urea permeability. The permeabilities of the membranes were explained on the basis of pore contents determined from their scanning electron microscope micrographs. All the membranes showed higher permeabilities during the first 2 hours of experimentation. Introduction of Zn2+ ions into the copolymer as crosslinking agent did not have much effect on the membrane properties but the properties of the copolymer were modified.
Studies on the hydrogenation of olefins using polymer‐bound palladium (II) species
Authors: Mani Ramanathan , Mahadevan Venkatraman , Srinivasan Mahalingam 
Published: April 2007

Abstractbis‐Benzonitriledichloropalladium(II) [(PhCN)2PdCl2] has been supported on two copolymers containing carboxyl and pyridyl groups and has been employed as a catalyst for the hydrogenation of olefins under mild conditions. The coordination environment and the nature of the metal species on the polymer have been studied by IR, ESCA, X‐ray and a chemical test based on KCN treatment.Based on experimental evidence it is proposed that the polymer‐palladium complexes initially contain palladium atoms with chlorine atom bridges which are cleaved in the activation. The catalysts were found to be active towards the hydrogenation of olefins under ambient conditions (room temperature and 1 atmosphere total pressure). The kinetic and mechanistic aspects of the hydrogenation of styrene and acrylonitrile and recycling capacity data using one catalyst (Cat‐I) are reported.
Polymers for use in drug delivery—property and structure requirements
Authors: Petrak K. 
Published: April 2007

AbstractThe purpose of this paper is to discuss some of the requirements placed on materials needed for improved administration of drugs. Emphasis is placed on macromolecules that need to be designed and prepared to perform specific pharmacological functions, particularly to act as vehicles for delivering drugs to specific locations within the body.After introducing the reasons for more selective drug delivery, and explaining the rationale for using macromolecules, practical examples of results with linking drugs to polymers, modifying polymers to increase their biological compatibility, attachment to polymers of groups that could mediate their specific recognition, modification of proteins with polymers, and the use of polymer complexes will be given to indicate the areas of need for further development of pharmaceutically useful macromolecules.
Some properties of β‐D‐Glucosidase from Trichoderma harzianum C1R1
Authors: Todorović R. , Grujić S. , Petrović J. 
Published: April 2007

Abstractβ‐D‐Glucosidase from Trichoderma harzianum C1R1 consists of several isocomponents having isoelectric points in the pH range of 4.85‐7.50. All the components exhibit both cellobiase and 4‐nitrophenyl β‐D‐glucosidase (4NPGase) activity. The enzyme affinity for cellobiose (Km = 3.92 mmol dm−3) is 14.5 times weaker than for 4NPG (Km = 0.27 mmol dm−3). The hydrolysis of both substrates is competitively inhibited by glucose, the inhibition of 4NPG hydrolysis (K1 = 2.00 mmol dm−3) being about 4.2 times stronger compared to the hydrolysis of cellobiose (K1 = 8.43 mmol dm−3). The 4NPG hydrolysis is also competitively inhibited by the presence of cellobiose and D‐glucono‐1,5‐lactone (Ki(cellobiose) = 5.00 mmol dm−3; Ki(D‐glucono‐1,5‐lactone) = 22 μmol dm−3). The optimal hydrolysis conditions are the same for both substrates (pH 4.5,55° C). The half‐lives of thermal inactivation at 61° C are 27 and 10min for cellobiase and 4NPGase, respectively.
Solution properties of poly(thiocarbonates) containing cyclic side chains
Authors: Gargallo Ligia , Tagle Luis H. , Radic Deodato 
Published: April 2007

AbstractPoly(thiocarbonates) with cyclic side chains have been studied in the theta solvent 1,4‐dioxane. The Mark‐Houwink‐Sakurada (MHS) relationships were established and the unperturbed dimensions determined. The conformational parameters were compared with those of other poly(thiocarbonates) and related polymers. It was found that the polymers containing cyclic groups present a more extended and rigid chain. A marked influence of the nature and structure of the side chain on the conformational parameters was found.
Solution behavior of Na sulfonated polystyrene: Dipole moment determinations
Authors: Güler Hatice , Aras Leyla , Vanderschueren J. 
Published: April 2007

AbstractSolution behavior of Na sulfonated polystyrene (NaSPS) ionomers with different percentages of sulfonate was studied by viscosity and dipole moment measurements. Two solvents of different character were chosen, i.e. dioxane (ϵ = 2.22) and dimethyl formamide (DMF, ϵ = 36) and their mixtures. The reduced viscosity as a function of concentration in polar solvents reflects the ‘polyelectrolyte’ behaviour of the ionomers.Mean‐squared dipole moment (<μ2>/x) values were calculated over a temperature range of 20–100°C, in dioxane and in a mixture of 4% DMF in dioxane. The results confirm the ‘polyelectrolyte’ behavior of ionomers by the addition of a small amount of polar cosolvent. The effect of increasing temperature on <μ2>/x in the DMF‐dioxane mixture is attributed to the formation of a coordination complex.
Amine functionalization of poly(styryl)lithium with N‐(benzylidene)trimethylsilylamine
Authors: Quirk Roderic P. , Summers Gabriel J. 
Published: April 2007

AbstractFunctionalization reactions of poly(styryl)lithium with N‐(benzylidene)‐trimethylsilylamine produce polymers containing significant amounts of coupling products for Mn = 2.8 × 103g/mol (19% coupling) and Mn = 15 × 103g/mol (15% coupling). Isolation and characterization of the products for the amination of poly(styryl)lithium with Mn = 2.8 × 13g/mol indicates that the non‐coupled products consist of a primary amine‐terminated polymer (69% yield) and an acetophenone‐type functionalized polymer (12% yield). The dimeric product (19% yield) has a primary amine functional group. The formation of these products is rationalized by a Cannizzaro‐type reaction of the initially formed polymeric lithium silylamide product with excess N‐(benzylidene)(trimethylsilylamine to form the corresponding polymer with imine chain‐end functionality which can react with another molecule of poly(styryl)lithium to form dimer product or hydrolyze to the acetophenone functionality on work‐up.
Preferential adsorption in polymer/solvent‐1 /solvent‐2 solutions by infrared spectroscopy
Authors: González Carmen , Zamora Fernando , Gutierrez Eva , Ramirez Juan C. , León Luis M. 
Published: April 2007

AbstractIR spectroscopy is shown to be a suitable technique for preferential adsorption studies in the following solvent‐1/solvent‐2/polymer systems: poly(N‐vinylcarbazole) and polyacenaphthene in nitrobenzene/dioxane, nitrobenzene/ tetrahydrofuran, and nitrobenzene/cyclohexanone. Values of the preferential adsorption parameters derived from the Schultz‐Flory theory agree with those from IR when both solvents in the ternary system are considered to be good solvents for the polymer. In the systems studied, the relative adsorptions of solvent‐1 and solvent‐2 by the polymer depend on the solvent mixture composition. The number of adsorbed molecules and their performance are correlated with the ternary interaction parameters, Xm3, and the Mark‐Houwink‐Sakurada exponent, a′. The adsorption changes observed are greater in those systems in which tetrahydrofuran was present.
A Review of Polymer Interfaces in Tyre Technology
Authors: Lechtenboehmer A. , Moneypenny H. G. , Mersch F. 
Published: April 2007

AbstractThe study of polymer interfaces is of prime importance in the field of tyre technology due to the critical role these contribute to tyre operation. The paper reviews the main polymer interfaces present in a tyre—(1) tyre/road (tyre wear or abrasion; tyre traction/skid resistance); (2) polymer/filler (carbon black; silica); (3) polymer/cord (brass coated steel wire; textile—rayon, nylon, polyester, aramid); (4) compound/compound (tack); (5) tyre/air (oxygen/ozone protection)—with respect to the criteria required, physical and chemical, to achieve optimum performance.
The role of impurities in the mechanisms and kinetics of reactions of epoxy resins and their effects on final resin properties
Authors: Grenier‐Loustalot Marie‐Florence , Grenier Philippe 
Published: April 2007

AbstractA series of commercial tetrafunctional epoxy prepolymers were step‐growth polymerised with aromatic amines. The roles of non‐epoxy chain ends and of impurities in the polymer were shown in terms of the mechanisms, reaction kinetics and final thermal properties of the material.The pure prepolymer was studied after preparative chromatographic separation. In the temperature range 100–180°C, epoxy‐primary amine reactions predominate at the beginning, followed by epoxy‐hydroxyl and epoxy‐secondary amine reactions at the end of the reaction sequence.These reactions may be either intermolecular forming cross‐linked networks, or intramolecular forming rings, the latter occurring primarily at the end of heat treatment.At temperatures higher than 180°C, there are breakdown reactions and homopolymerisation of epoxy groups.Based on data obtained with 13C solid phase cross polarization magic angle spinning nuclear magnetic resonance, inverse phase gas chromatography and Calvet microcalorimetry, the progress of the reaction could be determined up to the gel point and in the vitrification zone.Based on structural results (assays of residual functions and those formed in the cross‐linked networks), it was possible to establish relationships between structures and thermal properties.
Pyroelectric behaviour of solution‐grown cellulose acetate polymer films
Authors: Sharma A. K. , Ramu Ch. 
Published: April 2007

AbstractThe pyroelectric behaviour of cellulose acetate polymer films was studied in a vacuum of 10−3 torr under a polarizing field strength range of 6.25 × 105–50 × 105 V/m and a polarizing temperature range of 304–406 K.The pyroelectric coefficient exhibited abnormal behaviour, starting initially on the negative side and then changing sign from negative to positive. Negative coefficients are believed to be due to dipolar orientation, whereas space charge polarization is responsible for positive pyroelectric coefficients.
Anionic functional initiators. 1: 3‐dimethylaminopropyllithium as an initiator for the synthesis of Bi‐ and difunctional polybutadienes
Authors: Stewart Malcolm J. , Shepherd Neil , Service David M. 
Published: April 2007

AbstractMethods are described whereby a series of novel bi‐ and difunctional (telechelic) high 1,4‐microstructure polybutadienes are prepared by use of an anionic functional initiator. This initiator, 3‐dimethylaminopropyllithium, has been extensively investigated and methods for its preparation and use in non‐polar solvents are described. When utilised in such non‐polar solvents the polybutadienes produced are uniquely functionalised, possessing a high 1,4‐structure and a low glass transition temperature. Evidence is presented to demonstrate that these reactions are true ‘living’ polymerisations and that quantitative functional termination reactions may be used to yield a wide range of multi‐, bi‐ or difunctional polymers.
Preparation and properties of aromatic‐aliphatic cardopolyamides from phenoxathiins and thianthrenes
Authors: Reddy K. Audisesha , Srinivasan M. 
Published: April 2007

AbstractSeveral new aromatic‐aliphatic cardopolyamides containing phenoxathiin and thianthrene derivatives were prepared by the direct polycondensation of 2,8‐phenoxathiin‐bis(γ‐ketobutyric acid) (PA) or 2,7‐thianthrene‐bis(γ‐ketobutyric acid) (TA) with 3,3‐bis(4‐aminophenyl phthalide) (PDA), 9,9‐bis(4‐aminophenyl fluorene (FDA), or 9,9‐bis(4‐aminophenyl) anthrone (ADA) in a triphenyl phosphite‐pyridine system. The cardopolyamides were obtained in 80–95% yield and possessed viscosities in the range 0.90‐1.35 dl/g. They showed better solubility and heat resistance than analogous noncardopolyamides derived from conventional diamines. All the polymers were characterised by IR spectra, density, solubility, crystallinity and thermal analysis. Integral procedural decomposition temperatures (IPDT) were calculated from the primary thermograms in the temperature range 100–650°C to give quantitative data regarding the thermal stabilities. The molecular weight and molecular weight distribution of the polyamides were determined by gel‐permeation chromatography (GPC).
Studies on the radical copolymerization of methylacrylate with styrene using ZnCl2 as an accelerator
Authors: Srivastava N. , Rai J. S. P. 
Published: April 2007

AbstractThe kinetic investigation of the radical copolymerization of methylacrylate (MA) with styrene (Sty) using zinc chloride (ZnCl2) as an accelerator was carried out at 60 ± 0.1 °C for 120 min. The rate of polymerization was proportional to the concentrations of ZnCl2 and monomers. The energies of activation in the presence and absence of the complex are 34 and 89 kJ mol−1, respectively.
Studies on certain new polymaleamidehydrazides
Authors: Nagarathinam Rangasamy , Rajeswari Natesan , Viswanathan Seshaiyer , Kothandaraman Harimurthi , Ponnusamy Ettigounder 
Published: April 2007

AbstractThree polymaleamidehydrazides have been synthesised by the ring‐opening polyaddition of N,N′‐bisisomaleimide with aromatic diamines (having methyl or methoxy ring substituents or flexible SO2 groups between benzene rings) at room temperature. Thermogravimetry and mass spectrometry have been used in conjunction with infrared spectroscopy, inherent viscosity measurements, NMR and UV‐visible spectroscopy to characterise these polymers.
Synthesis and characterization of maleic anhydride oligomers
Authors: Severini Febo , Pegoraro Mario , Ricca Giuliana , Audisio Guido , Dainese Donatella , Gallo Raffaele 
Published: April 2007

AbstractMaleic anhydride (MA) reacts in acetone solution with pyridine (Py) at room temperature with carbon dioxide evolution and formation of oligomers having average M̄n ranging from 400 to 700 daltons. The influence of pyridine concentration on the rate of decarboxylation has been studied. The product obtained with molar ratio MA/Py = 1.64 is very reproducible. This product has been characterized with different analytical techniques. The results obtained allowed us to propose a reaction scheme for the oligomerization.
Synthesis and characterization of carboxylated polysulfones
Authors: Guiver Michael D. , Croteau S. , Hazlett John D. , Kutowy O. 
Published: April 2007

AbstractPolysulfone has been carboxylated, via a metalated intermediate, by reaction of a THF solution of polymer with n‐butyllithium and then treatment with carbon dioxide. The polymer reactions with n‐butyllithium were close to quantitative and did not require the use of a tertiary amine catalyst. A series of polymers ranging from 0.2 to 1.9 carboxyl groups per repeat unit was prepared by this method in the salt, acid and ester form. The structures of these polymer derivatives were characterized by 1H‐NMR, 13C‐NMR and IR. The glass transition temperatures and thermal stabilities were characterized by differential scanning calorimetry (DSC) and thermogravimetry (TG).
Industry drivers of global strategy and organization
Authors: Yip George S. 
Published: April 2007

AbstractThis article reports on a research study of how 18 worldwide businesses belonging to some of the largest American multinational companies responded in their strategies to industry globalization forces. The findings reveal some effective approaches, but at the same time show that most of these businesses lagged in their response. In particular, organizational, managerial and cultural barriers to implementation hampered efforts to change. This article develops a series of lessons on how multinational companies can improve their formulation and implementation of global strategy. © 1995 John Wiley & Sons, Inc.
A revised framework of global strategy: Extending the coordination‐configuration framework
Authors: Moon H. Chang 
Published: April 2007

AbstractAlthough there have been significant efforts in conceptualizing global strategies, few frameworks have been developed to measure the relative globalness of firms. Porter proposed a specific framework of coordination and configuration for this purpose. This article proposes a new framework of global strategy by extending Porter's original framework. The conceptual clarification of this article will be useful in understanding different types of firms that are pursuing a global strategy. © 1995 John Wiley & Sons, Inc.