bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on polymer latex films: II. Effect of surfactants on the water vapour permeability of polymer latex films
Authors: Roulstone B. J. , Wilkinson M. C. , Hearn J. 
Published: April 2007

AbstractPoly(butyl methacrylate) films have been prepared from surfactant‐free latices which had post‐added commonly used latex stabilisers. Water vapour transmission rates were used to study film permeability in relation to morphology, which was also studied by freeze fracture replication transmission electron microscopy. The extent of latex coalescence depended upon the chemical nature of the stabiliser employed and at monolayer coverage was not necessarily deleterious to the barrier properties of the films.
Chemical modification of crosslinked phenyl acrylate copolymers with monoethanolamine
Authors: Narasimhaswamy T. , Sumathi S. C. , Reddy B. S. R. , Devasagayam G. D. 
Published: April 2007

AbstractCopolymerisation of phenyl methacrylate, 4‐chlorophenyl acrylate, 4‐nitrophenyl acrylate and 2,4,6‐tribromophenyl acrylate with divinyl benzene was carried out in aqueous suspension medium at 80°C using benzoyl peroxide as radical initiator. The resulting beaded copolymers were characterised by FTIR. optical and scanning electron microscopy. Polymer analogue reactions of these particulate copolymers with monoethanolamine were carried out at 60.80 and 100°C in dimethyl sulphoxide as solvent. The progress of the reactions was followed by observing the disappearance of phenyl ester carbonyl absorption at 1750 cm−1 and the appearance of 1650cm−1 vibration corresponding to the characteristic amide carbonyl. The percentage conversions were calculated, and the effect of polar substituents in the phenyl acrylates as well as temperature on the reaction are discussed.
Free radical solution copolymerization of glycidyl methacrylate with n‐vinyl pyrrolidinone
Authors: Wen Shao , Xiaonan Yin , Stevenson William T. K. 
Published: April 2007

AbstractCopolymers of glycidyl methacrylate (monomer 1) with N‐vinyl pyrrolidinone (monomer 2) were prepared at 70°C in low yield by free radical initiated solution polymerizations in ethyl acetate, 1,4‐dioxane and mixtures of the two solvents. Copolymer compositions were determined by proton nuclear magnetic resonance spectroscopy. Monomer reactivity ratios were then derived using the method of Kelen & Tudos. The magnitude of r1 was relatively unaffected by solvent composition, and ranged from 4.32 to 4.53 in a random fashion. In contrast, values of r2 showed a greater relative (but still random) spread from 0.0075 to 0.0147. Copolymers prepared by batch polymerization are selectively enriched with GMA monomer.
Free radical initiation mechanisms in copolymerisation studied by the nitroxide trapping technique
Authors: Ken Busfield W. , Darren Grice I. , Jenkins Ian D. 
Published: April 2007

AbstractThe initiation mechanism for the radical copolymerisation of vinyl acetate, a typical electron donor monomer, and acrylonitrile, a typical electron acceptor monomer, initiated by t‐butoxy radicals, has been investigated by the nitroxide radical trapping technique: 1,1,3,3‐tetramethyl‐1,3‐dihydroisoindol‐2‐yloxyl (T) was the radical trapping agent.Two adducts (diastereomers) containing both vinyl acetate and acryionitrile monomers were isolated. From a kinetic analysis of these and other products over a wide range of conditions, a mechanism involving separate monomer addition, which may be regarded as normal kinetic control of monomer addition, is shown to be most consistent with the observed results.
On hybrid toughened DGEBA epoxy resins
Authors: Low I. M. , Bandyopadhyay S. , Mai Y. W. 
Published: April 2007

AbstractConsiderable improvements in the fracture resistance of epoxy resins have recently been achieved by adding either rubbery or rigid second phase dispersions, or both, to an epoxy matrix. These multiphase epoxy systems are particularly useful as high performance adhesives and as matrix materials in advanced composites. This paper describes the development of new toughened epoxy hybrids, which contain both rubbery and rigid dispersions. The latter dispersions were either zirconia particles, short alumina fibres or glassy‐metal ribbons. Micromechanisms of toughening and failure processes in these new materials are identified and discussed in the light of microstructures.
Silicones on glass surfaces
Authors: Bennett David R. , Matisons Janis G. , Netting Angus K. O. , Smart Roger St C. , Swincer A. Geoffrey 
Published: April 2007

AbstractX‐Ray photoelectron spectroscopy can be applied to the study of the bonding of highly functionalised silicones on to E‐glass fibres. The adsorption of six types of silicones (hydrido, epoxy, unsaturated imino, methacryl. ‘terminal’ amino and ‘pendant’ amino) from dilute toluene solutions were compared with that of a standard silane coupling agent. The calcium concentration was found to be an effective determinant of surface coverage by the siloxanes. as well as enabling the thicknesses of the adsorbed layers to be determined.
Properties of a semi‐crystalline and an amorphous thermotropic liquid crystalline polymer
Authors: Turek Douglas E. , Simon George P. 
Published: April 2007

AbstractThe physical properties, thermal stability, rheology and tensile properties of a commercial semi‐crystalline and an amorphous thermotropic liquid crystalline polymer (TLCP) have been investigated. Analysis by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) confirm the presence of a small melting endotherm and a glass transition in the former material. The as‐received amorphous TLCP exhibits no obvious melting endotherm and a strong glass transition is detected. The flow and tensile properties of the semicrystalline polymer are dominated by the presence of the crystalline to nematic transition temperature. The properties of the amorphous TLCP appear to be governed by increasing mobility afforded by increasing temperature. Based on flow behaviour and further DSC analysis it has been shown that under appropriate annealing conditions the as‐received amorphous TLCP can develop solid crystalline order.
Thermotropic Liquid Crystalline Aromatic Copolyesters with Flexible Spacers
Authors: Bao Jing‐Sheng , Fan Hong‐Ni 
Published: April 2007

AbstractTwo series of thermotropic liquid crystalline polymers were prepared from hydroquinone, methylhydroquinone, 2,5‐dichloroterephthaloyl chloride and four terephthalates with varying length substituents. Some of the properties of the terephthalates and polymers were characterized by IR, elementary analysis, differential scanning calorimetry (DSC), X‐ray diffraction and polarized hot‐stage microscopy.
Dopant Exchange in Conducting Polypyrrole Films
Authors: Maddison David S. , Jenden Charles M. 
Published: April 2007

AbstractPolypyrrole films containing a variety of dopants were synthesised. Special attention was given to ensuring that all films were morphologically similar so that differences in the electronic properties of the films were more strongly associated with the intrinsic character of the dopants, in particular their electron affinity. To achieve this, dopant exchange was performed by an electrochemical process and a strong correlation was found between dopant electron affinity (X) and film electrical conductivity.
Photo‐reversible Reaction in Polymer Langmuir‐Blodgett Films
Authors: Nakanishi Fusae 
Published: April 2007

AbstractPreparation of photoreactive Langmuir‐Blodgett (LB) films was carried out using polymers/oligomers prepared from long‐chain dialkyl esters of di‐and tetra‐olefins and having cyclobutane rings in the main chain. These polymers/oligomers formed stable monolayers on a water surface when mixed with arachidic acid. These monolayers could be deposited onto a substrate successfully forming Y‐type films. The oligomer LB films were polymerized on irradiation. The polymer LB films showed a photo‐reversible process between polymers and oligomers, depending on wavelength of the irradiating light. On the basis of spectral data and molecular weight change, this behaviour was found to be caused by cleavage and formation of cyclobutane rings.
The influence of the draw ratio of melt‐spun polyethylene fibres on γ‐irradiation induced effects as observed by ESR
Authors: Albert Candiera F. , Ken Busfield W. , Pomery Peter J. 
Published: April 2007

AbstractThe influence of draw ratio on free radical behaviour in melt‐spun polyethylene fibres has been examined using ESR spectroscopy. The stability of free radicals produced by γ‐irradiation is greatest some where between draw ratio 1 and 10. The general trend of radical stability has been found to correlate with the trend of gel content with draw ratio. The possible link between the extent of crosslinking and the production of stable radicals has been discussed in terms of morphological aspects.
Crystallization kinetics of native (pure) and commercial gutta percha (transpolyisoprene) and the influence of metal salts, oxides, ‘thermoplast’ and colouring agents on its crystallization rate
Authors: Arvanitoyannis Ioannis , Blanshard John M. V. , Kolokuris Ioannis 
Published: April 2007

AbstractThe kinetics of crystallization of gutta percha (trans‐polyisoprene) were studied both in its native form and as the commercial product currently used for dental purposes. Mixtures of native gutta percha with selected low molecular weight substances (BaSO4, CdSO4, Bi2O3, ZnO), ‘Thermoplast’—a commercially formulated plasticizer, and colouring agents were also examined. It was shown that any incompatibility of the aforementioned substances caused an increase in the crystallization rate, while compatibility decreased the rate of crystallization.
Studies on polymer latex films: IV. Comparison of the permeability of latex and solvent‐cast films
Authors: Roulstone B. J. , Wilkinson M. C. , Hearn J. 
Published: April 2007

AbstractLatex and solvent‐cast films have been prepared from poly(butyl methacrylate) surfactant‐free latices and their permeabilities to water vapour and an aqueous organic solute (p‐nitrophenol) have been studied. Latex films show considerable ageing effects and their performance is very dependent upon the conditions of film formation but their barrier properties are not necessarily inferior. A greater dependence on film orientation is evident for latex films.
Structural adhesive performance in marine environments
Authors: Horton Trevor , Spinks Geoffrey M. , Isles Neils A. 
Published: April 2007

AbstractDurability of adhesively bonded aluminium joints was investigated for both stressed and unstressed joints exposed to environments of air, distilled water, 0.5% sodium chloride solution and 5% sodium chloride solution. Testing involved the use of marine grade aluminium, two acrylic adhesives and two epoxy resin adhesives. Surface preparation consisted of a solvent wipe degreasing procedure. The acrylic adhesives used in this study displayed greater bond durability than cpoxy resins. Results also reaffirmed that the combination of stress and environmental exposure is more detrimental to bond durability than environmental exposure alone. The combined effects of stress and dilute salt solution were found to be more detrimental to adhesive bond durability than stress combined with distilled water, or concentrated salt solution. Two possible causes of bond deterioration considered were corrosion of the aluminium adherend and instability of the interface. Either of these explanations could account for the observed results; however, more work is required to verify these theories.
Microstructure of styrene copolymers with 2‐phenyl‐1,1‐dicyanoethene
Authors: Kharas Gregory B. , Mirau Peter A. , Watson Kenneth , James Harwood H. 
Published: April 2007

AbstractMicrostructure analysis of styrene copolymers with 2‐phenyl‐1,1‐dicyanoethene, as deduced from high resolution 1H and 13C NMR spectroscopy (DEPT, HETCOR, NOESY and JMODXH). demonstrated the formation of both head‐to‐head and head‐to‐tail alternating monomer structures. Conventional head‐to‐tail structures are explained as the result of cross propagation of ‘free’ monomers, whereas anomalous head‐to‐head structures are rationalized through the addition of monomer complexes of predicted geometry. The results indicated that the copolymer skeletal regioselectivity is dependent on participation of both free monomers and monomer donor‐acceptor complexes in the propagation steps of the copolymerization.
A kinetic study on MMA bulk radical polymerization
Authors: Shen Jia‐Cong , Wang Gou‐Bin , Yang Mei‐Lin , Zheng Ying‐Guang 
Published: April 2007

AbstractThe nonequalities of the reactivity and the micro‐environment of propagating radicals has been found in MMA bulk polymerization. This nonequal reactivity results from varying rates of diffusion in different micro‐surroundings. The decrease of radical reactivity is caused by the trapping of the segments around the propagating radical.
The synthesis and characterization of poly(ethylene oxide)‐b‐poly‐(dimethylsiloxane) diblock copolymers
Authors: Kiràly Zoltàn , Vincent Brian 
Published: April 2007

AbstractPoly(ethylene oxide)‐b‐poly(dimethylsiloxane) (PEO‐b‐PDMS) diblock copolymers have been synthesized by hydrosilation coupling. Allyl‐terminated PEO and dimethylsilane‐terminated PDMS macromers have been prepared by living anionic polymerization, followed by subsequent functionalization. The diblock copolymers, as well as the preformed macromers, have been characterized by gel‐permeation chromatography, vapour pressure osmometry, FTIR spectroscopy and 1H‐, 13C‐ and 29Si‐FTNMR spectroscopy. The results obtained from these techniques are presented in detail for PEO(M̄;n = 2120), PDMS(M̄n = 2220) and the corresponding diblock copolymer.
Non‐steady‐state model for kinetics of free radical polymerization, 4. Direct thermal initiation
Authors: Yan Deyue , Lin Jianming , Yuan Cuiming 
Published: April 2007

AbstractThis paper deals with the non‐steady‐state kinetics of direct thermal initiated polymerization. The initiation is assumed to be a bimolecular reaction of the monomer. The relationship between the radical concentration and the monomer conversion is rigorously derived. In further treatment a few very close approximations are introduced based on the fact that the number of monomer molecules reacting in the initiation step is much less than that consumed in the propagation step for a process producing high polymer, and the value of the rate constant for propagation or chain transfer is much lower than that for chain termination. Expressions for various molecular parameters, such as molecular weight distribution, number‐average and weight‐average degrees of polymerization, and dispersity, are given. Several numerical examples are provided.
Drop stabilisation by inorganic solids in suspension polymerisation: modification by electrolytes using a wax model
Authors: Zhiping Wang , Brooks B. W. 
Published: April 2007

AbstractFinely divided inorganic solids can be used for drop stabilisation in suspension polymerisation. Usually solids are dispersed in water in the presence of electrolytes formed during their preparation. Experiments, using a wax model as described previously,1 have been carried out by using two inorganic solids, magnesium phosphate and calcium phosphate, in either the presence or absence of electrolytes. The experiments showed that the effect of electrolytes depends on both the inorganic solid which is used and on the nature of the electrolyte which is present. Magnesium phosphate was a destabiliser in the absence of electrolytes but could act as a stabiliser in the presence of sodium sulphate. Calcium phosphate acted as a stabiliser both in the presence and in the absence of electrolytes.
Chain‐folding in polyethylene lamellar structure
Authors: Al‐Raheil I. A. M. , Okaz Ali M. 
Published: April 2007

AbstractThe nature of the chain‐folding in polyethylene lamellar structure from the melt has been studied. Permanganic etching was used to reveal the morphology by selective removal of material from the surface of the specimen. This was done to prepare the sample for transmission electron microscopy. The micrographs indicate the presence of lines (traces) parallel to the chain molecular axis. The chain inclination to the basal plane of the lamellar normal was assumed to be around 35°. With simple geometrical calculations the fold surfaces were found to be {20} planes, for which the exact angle is 34.4°.
Gamma‐radiation stabilization of polypropylene
Authors: Hassan Rezk A. M. , Senna M. M. , Abdel‐Bary E. M. 
Published: April 2007

AbstractEspecially synthesized compounds, together with conventional antioxi‐dants, were evaluated as radiation stabilizers of isotactic polypropylene. Electron spin resonance (ESR) determinations of free radical populations in stabilized and unstabilized samples were carried out after irradiation and at periods of up to 460 h. The same samples were mechanically tested and a correlation was found to exist between the concentration of trapped peroxy radicals and the radiation deterioration in the polymer. Post‐irradiation effects were evaluated using accelerated aging at 70°C and carbonyl index determinations at periods of up to 110 days indicated that some of the stabilizers examined are efficient inhibitors of post‐irradiation oxidation. The results are discussed in the light of the free radical mechanism of the radiation‐induced auto‐oxidative degradation of polymers.
PEO‐based polymer electrolytes
Authors: Magistris Aldo , Singh Kamal 
Published: April 2007

AbstractLike a liquid solvent, poly(ethylene oxide) dissolves a wide variety of inorganic salts. Ionic conductivity occurs in the amorphous region of the polymer and typically both anions and cations are mobile to some extent. This paper discusses the preparation, thermal behaviour and ionic transport of thin cast films of PEO‐based electrolytes containing monovalent and divalent cations. The techniques that shed light on the structure‐conductivity relationship are emphasized. The temperature and composition dependence of conductivity is also considered. Finally, attention has been paid to the possible uses of these polymeric electrolytes in solid‐state electrochemical devices such as primary and secondary batteries, electrochromic displays and sensors.
Metathesis ring opening polymerization of 5,6‐dimethylenebicyclo[2.2.1]hept‐2‐ene
Authors: Shahada Lamies A. , James Feast W. 
Published: April 2007

Abstract5,6‐Dimethylenebicyclo[2.2.1]hept‐2‐ene (I) polymerizes in the presence of the two‐component ring opening metathesis polymerization (ROMP) initiators WCl6/(CH3)4Sn and MoCl5/(CH3)4Sn. The product polymers were insoluble in all of many solvents investigated and are presumably cross‐linked. The product polymers were investigated by IR and solid state 13C NMR spectroscopy, which established that the material consisted predominantly of poly(1,4‐(2,3‐dimethylene‐cyclopentylene)vinylene) (II). A possible alternative route to II via thermal dehydrochlorination of poly(1,4‐(2,3‐bis(chloromethyl)cyclopentylene) vinylene) (IV) was also examined.
Chemically induced graft copolymerization of acrylonitrile on to hydrolysed wood pulp
Authors: Sabaa Magdy W. , Safy El‐Din Nabil M. 
Published: April 2007

AbstractGrafting of acrylonitrile on to hydrocellulose derived from the hydrolysis of wood pulp has been studied using cerie ammonium nitrate as initiator. The graft yield, the grafting efficiency and the total conversion were found to be highly affected by the various parameters studied including the initiator and monomer concentrations, the polymerization time and temperature. Moreover, the effect of the extent of grafting on the moisture regain property of the hydrolysed wood pulp has been also investigated.
Dielectric relaxation in poly(ethylene glycols) at 9.83 GHz
Authors: Sengwa Ram J. , Purohit Hari D. 
Published: April 2007

AbstractDielectric relaxation studies of poly(ethylene glycols), average molecular weight 200–9000, have been carried out in carbon tetrachloride solutions at microwave frequency, i.e. 9.83 GHz. Average relaxation times τ0 and relaxation times corresponding to segmental motion τ1, and group rotations τ2 have been calculated. The variations of relaxation times with increase in degree of polymerization and temperature have been determined. With the increase in the degree of polymerization the flexibility increases and hence the coiling of the chain increases. At a certain temperature there is a decrease in the relaxation time corresponding to segmental motion, suggestive of some switch‐over mechanism in higher polymers. The relaxation time corresponding to group rotations is independent of temperature and degree of polymerization.
Synthesis and characterisation of N‐toluyl methacrylatoethyl carbamates, homopolymers and copolymers with methyl methacrylate
Authors: Santhana Krishnan P. Gopala , Choudhary Veena , Varma I. K. 
Published: April 2007

AbstractThe paper describes the synthesis of N‐2/4‐toluyl methacrylatoethyl carbamates using 2/4‐toluyl isocyanate and 2‐hydroxyethyl methacrylate. Homopolymerisation and copolymerisation of these novel monomers with methyl methacrylate was carried out using benzoyl peroxide as an initiator and tetrahydrofuran as solvent. Photopolymerisation of N‐4‐toluyl methacrylatoethyl carbamate could be carried out without the use of photosensitiser. Structural characterisation of copolymers was done using 1H‐NMR. Thermal stability of copolymers was evaluated in a nitrogen atmosphere by dynamic thermogravimetry.
Synthesis and properties of poly(phenylene sulfide)s containing carbonyl and sulfonyl groups
Authors: Joseph K. Abraham , Srinivasan M. 
Published: April 2007

AbstractWith a view to study and compare the properties of poly(phenyienc sulfide)s containing carbonyl and sulfonyl backbone units, 1,4‐bis(phenylthio)‐benzene, and bis(4‐phenylthio)diphenyl sulfone, were prepared and subjected to Fricdel‐Crafts type polycondensation with various aromatic diacid chlorides. The resulting polymers had inherent viscosities in the range 0.101—0.141 dl/g. These polymers were not soluble in common organic solvents and exhibited good thermal stabilities.
Effect of initiator structure on physical and thermal properties of nylon‐6
Authors: Desai Manish R. , Pandya Madhav V. , Shah Chaitanya S. 
Published: April 2007

AbstractNylon‐6 is synthesised from ε‐caprolactam by an anionic polymerisation method, through a two‐step process using sodium metal as a catalyst and diisocyanate‐caprolactam block initiator. Two different aliphatic diisocyanates are used. The effects of diisocyanate structure and concentration on percentage cryslallinity, molecular weight, density and thermal properties of nylon are discussed.
Silica‐supported polymer‐palladium complexes as catalysts for the reduction of nitro and azo groups
Authors: Mathew Joice P. , Srinivasan M. 
Published: April 2007

AbstractPalladium complexes of cross‐linked polyvinylpyridine and poly(acryl‐amide‐methacrylic acid) copolymer coated on silica gel have been used as catalysts for the hydrogenation of azo and nitro groups under 101 kPa hydrogen pressure at 30°C. Nitro aromatics were selectively and almost completely reduced to the corresponding amines. A rate equation of the type, rate = k[cat][H2] has been derived for the hydrogenation of nitrobenzene on the basis of the experimental results and kinetic data. Also the selective hydrogenation of azobenzene to hydrazobenzene could be achieved with these catalysts.
A new difunctional anionic initiator soluble in non‐polar solvents
Authors: Nugay Turgut , Küçükyavuz Savaş 
Published: April 2007

AbstractThe reaction between 1,5‐diethenylnaphthalene and sec‐butyllithium produces a new difunctional organolithium initiator which is soluble in non‐polar solvents and effective in the synthesis of styrene‐isoprene‐styrene triblock copolymer. Monomodal molecular weight distributions are observed for block copolymers and styrene homopolymers. The microstructure of polyisoprene blocks is similar to those polymers initiated by butyllithium in the same solvent.