bluuebunny/crossref_metadata_2025 huggingface dataset:
A study of the cements formed between metal oxides and polyvinylphosphonic acid
Authors: Ellis John , Wilson Alan D.
Published: April 2007

Ionic polymer cements, formed by the reaction of metal oxides or ionleachable glass powders with various polyacids, have found widespread use in dentistry. Commonly, the polyacid employed is a homopolymer or copolymer of acrylic acid. An alternative ionic polymer cement system has recently been developed, based on phosphonic acid polymers. In this study, cement formation between polyvinylphosphonic acid, PVPA, and a range of metal oxides has been examined, including an assessment of hydrolytic stability and the relative stabilities of the Mn+‐PVPA bonds formed. An infrared spectroscopic technique has been used to determine the relative extents of the reactions between PVPA and the various metal oxides.

It is found that cements based on PVPA are far more reactive than those based on the polycarboxylic acids, and that the hydrolytic stability of the cements is greater. This greater resistance to water is probably due to the nature of the binding of the cations to the polyanion.
Thermotropic liquid crystalline copolyesters. II. Synthesis and thermal characterization of copolyesters of terephthalic acid, methyl hydroquinone and 1,4‐butane diol
Authors: Rath Asoke K. , Selvaraj Leena , Ponrathnam Surendra
Published: April 2007

The synthesis and thermodynamic evaluations of a series of random copolyesters based on terephthalic acid, methyl hydroquinone and 1,4‐butane diol are presented. The copolyester composition was varied by altering the relative concentrations of methyl hydroquinone and 1,4‐butane diol. The copolyesters display thermotropic transitions. The enthalpy changes during mesophasic transition display a minimum corresponding to equimolar composition. The copolyester with 75 mol% of spacer diol exhibited the lowest nematic transition temperature (190‐6°C). At this composition the nematic mesophase was most stable (δTN = 115‐6°C). ΔHN‐1 and ΔSN‐1 decrease with increasing rigid diol content. The isotropization temperatures were almost comparable since the largest mesogenic residues are similar in aspect ratio. These residues are required to melt prior to isotropization.
Polymeric surfactants for enhanced oil recovery. Part V: Prediction models for the effect of temperature and length of polyoxyethylene chain or hlb on surface and thermodynamic properties of some ethoxylated polymeric nonionics
Authors: Gendy T. S. , Barakat Y. , Mohamad A. I. , Youssef A. M.
Published: April 2007

Several equation models were investigated to find the relationship between temperature (T). number of ethylene oxide (EO) units (n) or the hydrophile‐lipophile balance (HLB) and the surface and thermodynamic properties of some ethoxylated alkylphenol‐formaldehyde polymeric nonionic surfactants. These properties include critical micelle concentration (CMC), free energy of micellization (ΔGmic), surface tension at CMC (7CMC), effectiveness (γCMC) and efficiency (pC20) of surfactant to reduce the surface tension of water. The values of the ratio CMC/C2(π = 20) were also considered.

The linear multiple regression technique was employed to determine the parameters of the equations and to choose the best forms with the highest values of R2 and F‐ratio which reflect the goodness and the reliability of the fit.
Performance of zircoaluminate coupling agents in wood flour/fibre‐polyolefin composites
Authors: Freischmidt G. , Michell A. J.
Published: April 2007

Wood flour and fibres do not bond well to polyolefins. Fillers or reinforcing agents for polyolefins based on these materials need to be treated before incorporation. This paper describes the property improvements obtained by treating papers, wood flour and wood fibres with zircoaluminate coupling agents before their forming into composites with polyolefins. The zircoaluminates were found to be effective coupling and hydrophobing agents in this system at low concentrations.
Studies on the hydrogenation of alkenes and alkynes using silica coated polymer anchored palladium complexes
Authors: Mathew Joice P. , Srinivasan M.
Published: April 2007

Palladium complexes of polyvinyl pyridine coated silica gel have been prepared and used as hydrogenation catalysts for alkenes and alkynes under ambient conditions. The kinetics of hydrogenation for a few substrates have been studied and a possible mechanism proposed. The kinetic and mechanistic aspects of the hydrogenation of the substrates, effect of additives on the rate of hydrogenation, selectivity of the catalyst and recycling efficiency of the catalyst are presented in this paper.
Synthesis and characterisation of methoxysilyl terminated polybutadienes
Authors: Lindsell W. E. , Radha K. , Soutar I.
Published: April 2007

Polybutadienyllithium systems with M̄n in the range 1.5 × 103‐20 × 103 are formed in hydrocarbon solvents by using n‐butyllithium or 3‐dimethylamino‐propyllithium as initiator. These ‘living’ polymers, of low polydispersity and relatively high 1,4‐structure, react with 3‐chloropropyl(trimethoxy)silane at < − 20°C, in the presence of tetrahydrofuran, to give, primarily, polymers terminated by the 3‐chloropropyl(dimethoxy)silyl group, Si(OMe)2{(CH2)3Cl}, as characterised by GPC and by 1H, 13C and 29Si NMR studies. Quaternisation by iodomethane of the telechelic polybutadiene with a dimethylamino end‐group produces a silylated cationomer containing the terminal functionality, I−+Me3N(CH2)3. In some silylation reactions of polybutadienyllithium systems, especially at higher temperatures, and in related reactions with Si(OMe)4, polymers coupled via the silyl groups are also formed. Hydrolysis of the terminal dimethoxysilyl functions occurs under acidic or basic conditions; end‐group coupling to silica gel also occurs and other reactions have been investigated.
Adsorption effect of 4‐carboxy benzene sulphonyl azide on calcium carbonate in sbr vulcanizates
Authors: Marcos A. , de Benito J. L. , Ibarra L. , Rodriguez A. , González L.
Published: April 2007

The effects of calcium carbonate modified with 4‐carboxy benzene sulphonyl azide on the mechanical properties of SBR mixes have been investigated. The studies include determination and comparison of tensile strength, elongation, tear strength, compression‐relaxation behaviour, and swelling measurements of modified and unmodified filler systems. The results show that the azide attached to the surface of the filler particles reacts with the rubber and improves the mechanical properties.
Mechanistic and kinetic studies on the polymerization of styrene initiated by dimethyl sulfonium 2‐pyridyl carbonyl methylide
Authors: Bhatnagar Urvi , Srivastava A. K.
Published: April 2007

Dimethyl sulfonium 2‐pyridyl carbonyl methylide (Ypy‐s) initiated radical polymerization of styrene in dimethyl sulfoxide at 85±0.1°C for 6 h under a nitrogen blanket using dilatometric techniques has been studied. The initiator and monomer exponent values were calculated to be 0.5 and 1.2, respectively. The system follows ideal radical kinetics with bimolecular termination. The higher monomer exponent value is ascribed to significant solvent effects on the initiation rate. The overall activation energy and average value of k2p/kt are 52.0 kJ mol−1 and 1.0 × 10−3 litre mol−1 s−1, respectively. The polymerization was retarded in the presence of hydroquinone or benzene; dimethylformamide, however, enhanced the rate of polymerization. Kinetic data and ESR studies indicate that the overall polymerization takes place via triplet carbene formation which acts as a source of free radicals.
Singlet oxygen lifetime in polymer films
Authors: Schiller Kurt , Müller Franz Werner
Published: April 2007

Singlet oxygen lifetimes [τ(1O2)] in polymer matrices were calculated using the strong exponential correlation between the incremental rate constant (Kxy) of energy transfer from 1O2 to terminal oscillators X—Y contained in solvent molecules and the energy (Exy) of the highest fundamental vibration of the oscillator X—Y. The lifetimes in polymers correspond very well to experimental data in the literature. They depend only on the nature and quantity of molecular oscillators in the medium but not on the state of aggregation. The computed lifetimes in common polymers vary only from 10 to 50 μs. Therefore the lifetime of 1O2 in singlet oxygen reactions in polymers is of secondary importance in comparison to the diffusion coefficient.
Synthesis and characterisation of graft copolymers of oxidised rubber and 2‐hydroxy ethyl methacrylate
Authors: Devi Surekha , Rakshit Animesh Kumar , Guthrie James T.
Published: April 2007

Natural rubber was oxidised by hydrogen peroxide using 7 radiation. Various conditions such as variations in time of exposure to 7 radiation, H2O2 concentration, grafting reaction time and monomer to polymer ratio were examined with respect to optimisation of grafting. The resulting graft ccpolymers were characterised by FTIR, DSC, contact angle measurement and electrokinetic potential measurements.
Synthetic polyelectrolytes—A review
Authors: Mortimer David A.
Published: April 2007

The ability to control charge nature, charge density and molecular weight enables the polymer chemist to design polyelectrolytes to provide a wide variety of functions, essential in many industrial processes. The flexibility of polymer design is summarised.
Thermally stimulated discharge current studies in pure and fe‐doped polystyrene films
Authors: Sharma A. K. , Sagar D. Santhi
Published: April 2007

Studies were made on the thermally stimulated discharge currents (TSDCs) in pure (undoped) and Fe‐doped polystyrene films as a function of polarizing field, polarizing temperature and dopant concentration. While undoped films exhibited a single peak, doped films showed two peaks one at low temperatures and another at high temperatures. The low temperature peak, which exhibits a shift towards lower temperatures with increasing dopant concentration, is attributed to the relaxation of the main chain, while the high temperature peak, which shows a tendency to shift towards higher temperatures with dopant concentration, is due to space charge polarization. The TSDCs were higher for low dopant concentrations than their undoped counterparts, while for high concentrations of the dopant, the TSDCs decreased. Formation of charge transfer complexes at low dopant concentrations and molecular aggregates at higher dopant concentrations are suggested as the possible reasons for this behaviour.
Calorimetric study of some poly(mono‐n‐alkyl itaconates)
Authors: Diaz‐Calleja Ricardo , Ribes‐Greus Amparo , Gargallo Ligia , Radić Deodato
Published: April 2007

A calorimetric study of poly(mono‐n‐alkyl itaconates) containing 8, 10, 12 and 14 carbon atoms in the side chain was performed. No glass transition temperature (Tg) was observed in the temperature range 213‐263 K, but a melting process was observed for the dodecyl and tetradecyl derivatives, which was attributed to crystalline order in the long side chains.
Electrochemical behaviour of polyaniline in aromatic sulphonic acids
Authors: Dhawan Sundeep Kumar , Trivedi Dinesh Chandra
Published: April 2007

This report describes the synthesis and redox behaviour of polyaniline in aqueous solutions of benzene sulphonic acid and 4‐toluene sulphonic acid. The characterization of the polymer was carried out by electronic spectra, FTIR studies and 1HNMR in DMSO‐d6.
Tensile yield parameters for poly(vinylchloride) blends with a methyl methacrylate–butadiene–styrene impact modifier
Authors: Havriliak S. , Slavin S. E. , Shortridge T. J.
Published: April 2007

Tensile yield measurements were made on blends of poly(vinyl chloride) (PVC) with a methyl methacrylate‐butadiene‐styrene impact modifier (MBS) covering a blend range of 0 to 20 wt % MBS, a temperature range of −50 to 25°C, and a strain rate range of 10−3 to 10° s−1. Increasing MBS level in PVC reduces the tensile yield stress. The tensile yield stress variation with temperature and strain rate at constant MBS level was represented in terms of the Ree‐Eyring‐Roetling rate model. This model represents the experimental data within experimental error. The tensile yield parameters were also determined by assuming that stress concentrations exist around the modifier equatorial plane. Estimates of these stress concentrations were made and are discussed in terms of Goodier's model for spherical inclusions.
pH‐stat methodology in continuous monitoring of the kinetics of hydrolysis of phosphate esters catalysed by alkaline phosphatase from human placenta: II. Kinetic aspects
Authors: Roig M. G. , Serrano M. A. , Bello J. F. , Cachaza J. M. , Kennedy J. F.
Published: April 2007

The adaptation of the pH‐stat to continuous monitoring of the in‐vitro hydrolase activity of alkaline phosphatase in solution, an activity which until now has only been analysed by means of spectrophotometric methods in a continuous or static state, is described. To control the reliability of the method in the monitoring of these enzymic reactions, a series of kinetics of hydrolysis of chromogenic (p‐nitrophenyl and o‐carboxyphenyl phosphates) and non‐chromogenic (ATP) substrates was carried out, comparing the results obtained via continuous spectrophotometric analysis of the corresponding phenol released or via a discontinuous technique by the phosphate produced with those results obtained via pH‐stat analysis of the H+ released or utilized by the enzymic reaction of hydrolysis. It can be concluded that kinetic studies carried out on the pH‐stat of in‐vitro alkaline phosphatase activity offer results analogous to those obtained for the same system through classic spectrophotometric methods, offering as well notable advantages of speed and simplicity in the kinetic assays since it is always possible to monitor the enzymic activity continuously, with chromogenic or non‐chromogenic substrates. The pH‐stat methodology affords additional information on the kinetics of action of alkaline phosphatase from placenta acting on non‐chromogenic biological substrates. In this sense, kinetic studies with the pH‐stat on the enzymic hydrolysis of ATP were begun, determining their rate versus pH profile (optimum pH at 9.1) and proposing possible ‘non‐Michaelian’ type kinetic behaviour of the enzyme in solution as deduced from the graphical analysis of the data v([ATP]).
Poly(chloroprene)‐castor oil based polyurethane semi‐interpenetrating polymer network as an adhesive
Authors: Rajalingam P. , Radhakrishnan Ganga
Published: April 2007

The adhesive behaviour of polychloroprene rubber (CR)‐castor oil based polyurethane (CPU) semi‐interpenetrating network (SIPN) was studied by peel strength and shear strength. The order of peel and shear strength is leather‐leather>leather‐rubber>rubber‐rubber. Effects of solvents and acids on the bonded assembly were tested.
Epoxides bearing azomethine linkages
Authors: Mikroyannidis John A.
Published: April 2007

Seven structurally different diepoxides, triepoxides or tetraepoxides bearing azomethine linkages were synthesized and characterized. The reactions of 4‐hydroxybenzaldehyde or 3,4‐dihydroxybenzaldehyde with 4‐aminophenol or 4‐aminobenzoic acid afforded azomethines, which reacted subsequently with excess of epichlorohydrin in the presence of benzyltrimethylammonium bromide to yield diepoxides or triepoxides. Triepoxides were prepared by reacting 4‐hydroxybenzaldehyde with 5‐aminoisophthalic acid or 4‐amino‐2‐hydroxybenzoic acid again to yield azomethines, which were subsequently reacted with epichlorohydrin. In addition, a tetraepoxide was prepared from the reaction of 1,4‐benzenedicarbaldehyde with a double molar amount of 4‐amino‐2‐hydroxybenzoic acid to afford a bisazomethine followed by reaction with epichlorohydrin. The epoxy compounds were characterized by IR and 1H NMR spectroscopy. Their thermal polymerization in the presence of 4,4‐diaminodiphenylsulfone (DDS) was investigated by DTA. Thermal stabilities of cured resins were ascertained by TGA and isothermal gravimetric analysis (IGA) in N2 or air. The polymer derived from the tetraepoxide was the most heat‐resistant. It was stable in N2 up to 313°C and afforded an anaerobic char yield of 58% at 800°C.
Experimental evidence for the existence of intramolecular hydrogen bonds in the water‐insoluble sodium salt of carboxyethyl cellulose solid
Authors: Kowsaka Keisuke , Yasuda Katsunari , Okajima Kunihiko , Kamide Kenji
Published: April 2007

An attempt has been made to explain the solubility behavior of sodium carboxyethyl cellulose (NaCEC) towards water and aqueous sodium hydroxide (aq. NaOH) in terms of supermolecular structure, i.e. degree of breakdown of intramolecular hydrogen bonding related to the degree of substitution. For this purpose, five NaCEC samples with «F» ranging from 0.03 to 0.0.39 were prepared in homogeneous aqueous media and subjected to CP/MAS 13C NMR and deuteration IR measurements. Existence of O3H…O'5 intramolecular hydrogen bonds in solid water‐insoluble NaCEC was first confirmed using both CP/MAS NMR and deuteration IR. This fact strongly suggests that for cellulose derivatives with relatively low «F» the solubility of the derivative in water or aq. NaOH is mainly governed by the considerable destruction of intramolecular hydrogen bonds. These findings are consistent with our previous conclusions [Polym. J., 16 (1984) 857] that the solubility of pure cellulose solid in aq. NaOH is mainly governed by the destruction of intramolecular hydrogen bonds.
Review: Complex formation between polymer pairs for template polymerization
Authors: Srivastava A. K. , Tewari Neeta , Awasthi Sanjay K.
Published: April 2007

This review paper presents an account of complex formation between polymer pairs for template polymerisation. The values for the coefficient of interaction KAB, evaluated using the polymer solvent method have been examined for a number of vinyl polymers in different solvents.
Phase equilibria and solution thermodynamics in the ternary system, poly(acrylic acid)‐dioxane‐water
Authors: Cowie John M. G. , Swinyard Brian
Published: April 2007

The stability of solutions of poly(acrylic acid) in dioxane‐water mixtures has been examined as a function of temperature and three phase boundaries have been located when water contents are less than 10 (wt/vol)%. These collapse into one boundary at higher water contents up to 25 (wt/vol)%. The cloud points have the characteristics of a quasi‐LCST, a UCST, and an LCST, in order of increasing temperature, and this behaviour is comparable to the behaviour of poly(acrylic acid)‐dioxane solutions. Measurements of the heat of dilution showed that this changes from being endothermic in dioxane solutions to exothermic in aqueous systems at temperatures below the quasi‐LCST. Laser Raman spectra indicate the presence of hydrogen bonding between water and the polymer in the mixed solvent, which may explain the improved solvating power when water is added to dioxane.
Dielectric dispersions in a commercial acrylonitrile‐butadiene‐styrene polymer
Authors: Yeow Ong Hian , Pratt Graeme J.
Published: April 2007

Observations of dielectric constant and loss from −120°C to +140°C over the frequency range 30 Hz to 3MHz are presented for a low rubber content acrylonitrile‐butadiene‐styrene (ABS) polymer of commercial origin. Seven dielectric dispersions are distinguished in the tan δ contour map and constant‐frequency plots together with evidence for an eighth at the lowest temperatures.

Possible sources for each dispersion are proposed in relation to the miscibility and morphology of the individual phases present in this multicomponent polymeric material.
Mechanism of the copolymerization of styrene with methyl, ethyl, and n‐butyl acrylates in the presence of zinc chloride
Authors: Srivastava N. , Rai J. S. P.
Published: April 2007

The complexes of methyl acrylate (MA), ethyl acrylate (EA) and n‐butyl acrylate (BA) with zinc chloride (ZnCl2) were prepared at 300 K and found to be polar in nature. The viscosity and density of the complexes increased while the tendency to form a binary complex decreased with increase in size of the alkyl substituents of the acrylate monomers. The copolymerization of MA and BA with styrene (Sty) followed a cross‐propagation mechanism, whereas the copolymerization of EA with Sty followed a radical‐complex mechanism in the presence of their complexes with ZnCl2.
Non‐steady‐state model for kinetics of free radical polymerization, 2. Redox initiation
Authors: Yan Deyue , Lin Jianming , Yuan Cuiming , Feng Jing
Published: April 2007

This work deals with the non‐steady‐state kinetics of free radical polymerization with redox initiation. Rigorous expressions for the radical concentration, monomer conversion, molecular size distribution function, and number‐average and weight‐average molecular weights, etc., were derived. The molecular parameters of the resulting polymer were evaluated in relation to the polymerization conditions.
Synthesis and characterization of acrylamide‐hexyl methacrylate copolymers
Authors: Srinivasulu B. , Raghunath Rao P. , Sundaram E. V.
Published: April 2007

The free radical copolymerization of acrylamide with hexyl methacrylate has been carried out in dimethyl formamide at 60°C by using 2,2′‐azobis‐isobutyronitrile. The copolymer composition was determined from the nitrogen estimation. Reactivity ratios were calculated by the Fineman‐Ross and Kelen‐Tüdos methods. The copolymers were characterized by IR, 1H‐NMR, 13C‐NMR and dielectric studies. Molecular weights of the copolymers were of the order of 105.
Viscometric study of extremely dilute macromolecular solutions: Critical concentration c and the intrinsic viscosity of the polystyrene through scaling laws. The values of the Huggins constant
Authors: Dondos Anastasios , Tsitsilianis Constantinos
Published: April 2007

A crossover is observed in the variation of the reduced viscosity, ηsp/c, as a function of the concentration, c, for polystyrene solutions in cyclohexane and dioxane. This crossover is attributed to the critical concentration c at which the macromolecular coils start to contact. The critical concentration c is related to the molecular weight and the intrinsic viscosity of the polystyrene through scaling laws. The values of the Huggins constant k' determined in the concentration regions below c (extremely dilute solutions) confirm the Peterson‐Fixman theory.
Organotin polymers—XVII. Azeotropy in terpolymerization reactions of tri‐n‐butyltin 4‐acryloyloxybenzoate wit alkyl acrylates or styrene and acrylonitrile
Authors: Mahmoud A. A. , Shaaban A. F. , Azab M. M. , Messiha N. N.
Published: April 2007

Ternary copolymerizations of tri‐n‐butyltin 4‐acryloyloxybenzoate (ABTB) with acrylonitrile (AN) and alkyl acrylates [methyl (MA), ethyl (EA) or butyl acrylate (BA)], methyl methacrylate (MMA) or styrene (ST) were carried out in solution at 70°C in the presence of free radical initiator. Experimental terpolymerization data agreed well with calculations based on the Alfrey‐Goldfinger equation. The determination of unitary, binary and ternary azeotropies of various systems studied was easily handled by a computer program. The results obtained show that there is no ternary azeotropic composition for any terpolymer, system studied. Selective unitary and binary azeotropic compositions were polymerized and the results obtained show good agreement between the theoretical and experimental terpolymer composition for each case.
Copolymerization of ethene and dimethanooctahydronaphthalene with aluminoxane containing catalysts
Authors: Kaminsky Walter , Bark Andreas
Published: April 2007

With homogeneous catalysts on the basis of chiral metallocenes and methylaluminoxane it has become possible to polymerize cyclic olefins like cyclobutene, cyclopentene, norbornene, or dimethanonaphthalene (DMON). No ring opening reaction occurs. The crystalline polycycloalkenes show extremely high melting points between 400 and 600°C. Copolymers of DMON with ethene are amorphous. They have molecular weights between 50000 and 150000 and high glass transition points up to 160°C. These copolymers could be used as materials for optical discs and fibers.
Template polymerization of dimethylaminoethylmethacrylate in the presence of polyacrylic acid
Authors: Abd‐Ellatif Z. H.
Published: April 2007

The occurrence of a template process in the system polyacrylic acid (PAA) as the template for the polymerization of dimethylaminoethylmethacrylate (DMAEM) has been deduced from kinetic observations. Radical photopolymerization was carried out in aqueous acetone solution (1:2 v/v) using azobisisobutyronitrile (AIBN, 1 x 10‐3 mol litre‐1) as the radical initiator. Polymerizations were carried out using different concentration ratios of template [T] to monomer [M]. All runs were performed in evacuated dilatometers. The rate of polymerization increased in the presence of the polymer catalyst and was found to attain a maximum value at a ratio of [T]/[M] of about 1.5 in the presence of UV light of λ = 365 nm and at a temperature of 25 /pm 0.05°C. Partial separation of the PAA from the daughter polymer PDMAEM has been achieved.
Homogeneous acetalization of cellulose in lithium chloride and dimethylacetamide
Authors: Suzuki Kimihiro , Kurata Syuhei , Ikeda Isao
Published: April 2007

Cellulose acetal derivatives were prepared by treating regenerated cellulose with various acetals in LiCl/dimethylacetamide (DMAc). Their IR and NMR spectra as well as gas chromatograms of their hydrolyzates proved that they have hemi‐acetal structures. The degree of benzacetalization increased with an increase in catalyst, acetal and cellulose concentrations, and reached a maximum at 50–60°C of reaction temperature. Benzacetalization under reduced pressure gave the maximum degree of substitution, 2–1. The acetalization of cellulose is a reversible bimolecular reaction and its equilibrium constant is about 0.001–0.023. The heat of reaction and the activation energy of the forward and back reactions were 12‐1, 18‐5 and 7–8 kcal/mol, respectively. The equilibrium degree of acetalization with various alkylacetals increased in the electron‐releasing order of alkyl group. Cellulose acetals with a low degree of substitution were soluble in cold water as well as in dimethyl sulfoxide.
Synthetic resins: XV. Chelation ion exchange properties of 2,4‐ dinitrophenylhydrazone of resacetophenone‐formaldehyde resin
Authors: Lenka S. , Parija A. , Nayak P. L.
Published: April 2007

A number of copolymers were synthesised by condensing the 2,4‐dinitrophenylhydrazone of resacetophenone with substituted benzoic acids/ phenols and formaldehyde in the presence of sodium hydroxide or hydrochloric acid. The decomposition temperature, solubility and viscosity of the polymers have been determined. The ion‐exchange properties have been studied by using a batch equilibrium method. The distribution of a number of metal ions between an aqueous solution and the resin have been measured. A wide range of pH and variable ionic strengths have been investigated.
Thermogravimetry and wide angle X‐ray diffraction study on the structure of irradiated and thermally treated kodar film
Authors: Singh R. P. , Thombre S. M. , Kuber M. V.
Published: April 2007

The degradation behaviour of Kodar [poly(1,4‐cyclohexylene dimethyl‐eneterephthalate)] was investigated in air using thermogravimetry, differential thermal analysis and wide angle X‐ray diffraction studies. The rates of crystallization and degradation were influenced by thermal exposure and polychromatic irradiation (Λ > 290 nm) for different time intervals. The crystallinity changes (Xc%) and activation energies (ΔE) for the systems have been determined.
Use of inverse thin layer chromatography with amino acids to characterize molecular interactions on conducting polymers
Authors: Teasdale Peter R. , Ge Hailin , Gilmore Kerry , Wallace Gordon G.
Published: April 2007

A new method for characterizing conducting polymers, based on thin layer chromatography, is evaluated. Polypyrrole and polyaniline were used as the stationary phase and molecular probes were used to characterize favourable interactions on the polymers. Amino acids were chosen as the molecular probes because of the range of properties they exhibit and because there are numerous methods for their detection. Some difficulties were experienced in preparing stationary phases with suitable physical properties. However, once this was overcome, useful information was obtained with inverse TLC. Polypyrrole and polyaniline were both found to behave predominantly as anion‐exchange materials.
Anionic copolymers of octanelactam with laurolactam (nylon 8/12 copolymers)—v. Effect of annealing on thermal properties and crystalline structure
Authors: Arvanitoyannis Ioannis , Blanshard John M. V.
Published: April 2007

The effects of different annealing time/temperature regimes on the thermal and crystalline behaviour of a series of statistical copolyamides (nylon 8/nylon 12), prepared by activated anionic polymerization of octanelactam/laurolactam (OL/LL), were determined by DSC, X‐ray (WAXS), density and viscosity measurements. The melting temperature and the heat of melting increased with annealing time and temperature. The results were correlated with the molar composition of the copolyamides and showed a gradual increase in percentage crystallinity with time.
Delayed action heat seal adhesives. I: Dielectric relaxation studies of mixtures of dicyclohexyl phthalate with poly(vinyl acetate) and polystyrene
Authors: Elwell Richard , Hayward David , Pethrick Richard A.
Published: April 2007

The design of delayed action heat seal adhesives depends on the physical properties of the polymer, plasticiser and their resultant mixtures. This paper explores the relationships between various molecular interactions and the performance of the adhesives. Dielectric relaxation measurements of mixtures of poly(vinyl acetate) or polystyrene and a plasticiser, dicyclohexyl phthalate, were performed to characterise the molecular dynamics of the system. Binary mixtures over the entire composition range were examined from 244 to 408 K and over a frequency range from 10−1 to 6 × 104 Hz, and allowed the nature of the interaction between plasticiser and polymer to be quantified. Dielectric studies are compared with measurements of the glass transition temperature obtained using thermal and mechanical analysis, and indicate that over certain composition ranges segregation of the components occurs at a molecular level. These observations are discussed in relation to the design of a delayed action heat seal formulation.
Temperature effects on permeation of modified atmosphere gas mixtures through a low density polyethylene package film
Authors: Tokatli Kamil , Özilgen Mustafa
Published: April 2007

Permeation of CO2 and O2 through a low density polyethylene film was studied with CO2‐N2 mixtures in the temperature range 263‐283 K, and with CO2‐O2‐N2 mixtures in the range 257‐313 K. The temperature dependence of the permeabilities of these gases agreed with the Arrhenius expression. The activation energy for carbon dioxide diffusion was between 3.53 × 104 and 3.74 × 104J/mol; the activation energy for oxygen diffusion was 3.13 × 104J/mol. The pre‐exponential constant for oxygen was higher than that of carbon dioxide in various mixtures. It was also found that the pre‐exponential constant of carbon dioxide decreased with increasing CO2 concentration in the mixtures.
Reactant partitioning in free‐radical heterophase polymerization: The case of inverse microemulsion polymerization of acrylamide
Authors: Bartoň Jaroslav
Published: April 2007

Conversion curves have been determined at 60°C for the polymerization of acrylamide in percolating inverse microemulsions. Ammonium peroxo‐disulphate (APS) and dibenzoyl peroxide (DBP) were used as initiators of free‐radical polymerization in the presence or absence of potassium nitrosodisulphonate (Fremy's salt, FS). The percolation decreases the rate of polymerization of acrylamide initiated by APS. The polymerization is inhibited by FS. After an inhibition period, retardation of acrylamide polymerization is more pronounced in non‐percolating microemulsions. No inhibition periods were observed for DBP‐initiated polymerization of acrylamide. The percolation shortens the time interval of the ‘slow’ polymerization of acrylamide, but the rates of rapid acrylamide polymerization above 10% conversion are the same for percolating and for non‐percolating inverse microemulsions. The polymer particle diameter is a function of acrylamide/water weight ratio and of [water]/[AOT] (AOT: bis(2‐ethylhexyl)‐sulphosuccinate sodium salt) molar ratio. No effect of the initiator's nature either in the presence or in the absence of FS was found. The results are interpreted on the basis of initiator and/or nitroxide radical partitioning between oil and water phases of the inverse microemulsion, and are discussed with respect to the mechanism of acrylamide polymerization and polymer particle formation proposed for non‐percolating inverse microemulsions.
A new approach to continuous emulsion polymerization
Authors: Imamura Tsuyoshi , Saito Koichi , Ishikura Shinichi , Nomura Mamoru
Published: April 2007

The application of a continuous Couette‐Taylor vortex reactor to continuous emulsion polymerization was studied. First, the mixing characteristics of the reactor were examined by the stimulus‐response method. It was found that the reactor performance was similar to that of a continuous flow reactor consisting of more than 60 well‐stirred tanks in series if the reactor was properly designed and operated near the critical Taylor number. It was also demonstrated by a comparison of the particle size distributions of the latexes produced in a batch reactor and in the continuous Couette‐Taylor vortex reactor that the continuous reactor could produce latex particles with fairly narrow size distribution. Furthermore, since no stirrer is involved, this continuous reactor is suited for the purpose of avoiding coagulation of latex particles that are very sensitive to mechanical shear.
Kinetics of styrene emulsion polymerization with a stable monomer radical
Authors: Litt Morton
Published: April 2007

It was shown previously that chain transfer in the vinyl group of vinyl acetate produces a stable radical which reinitiates slowly. Similarly, chain transfer on styrene monomer should produce a stable radical. This was confirmed by analysis of the copolymerization data of phenyl acetylene with methyl acrylate and methyl methacrylate. The propagation rate constant towards styrene would be in the region of 0.1‐5 (mols)−1.

The kinetics of seeded emulsion polymerization of styrene (small seeds, low initiator concentration) was derived using the hypothesis of a stable radical which could desorb from the particle and be swept up by other particles. Using the developed equations, the data of Hawkett et al. [JCS. Faraday I., 76 (1980) 1323] were analyzed. The data could be fitted well and gave an estimated rate constant for reinitiation of ≥ 0.1 (mols)−1 and ≥ 0.1 s−1 for the desorption rate constant for this particle size. This was shown to be a reasonable value. Thus the emulsion polymerization of styrene under Smith‐Ewart Case 1 conditions can be interpreted using normal rate constants and mechanisms if we accept the hypothesis of a relatively stable chain transferred monomer radical.
Electroviscous effect in dilute suspensions of ionic polymer latices
Authors: Yamanaka J. , Hashimoto S. , Yamaguchi T. , Saeki S. , Tsubokawa M. , Matsuoka H. , Kitano H. , Ise N.
Published: April 2007

The viscosity of dilute suspensions of ionic polymer latices was measured using a variable‐shear capillary viscometer, a rotational viscometer and an Ubbelohde viscometer. The viscosity of the suspension was much larger than the Einstein theoretical value and showed a marked shear‐thinning behaviour, due to the electroviscous effect. The dependence of the reduced viscosity of latex suspensions on latex concentration, salt concentration and solvent was essentially the same as that of linear ionic polymer solutions. Counterion effect was also investigated.
Synthesis, characterization and application of surface active initiators
Authors: Taued Klaus , Kosmella Sabine
Published: April 2007

Surface active azo initiators have been synthesized starting from 2,2′‐azoisobutyronitrile (AIBN) and different a, o‐diols. Values of the production rate of free radicals from these initiators (2fkd) were obtained from ESR investigations of initiator solutions with a spin labelling technique as well as from solution polymerization of acrylonitrile and from emulsion polymerization of vinyl chloride under monomer starved conditions. The 2fkd values from the polymerization experiments were higher than those from the ESR investigations. Furthermore, the results show an influence on the kinetic constants and latex properties of the initiator structure. The emulsion polymerization of styrene was investigated at temperatures from ambient to 373 K with different initiator‐emulsifier systems (IES) including persulphate, AIBN and surface active initiators. From these data were obtained Arrhenius plots for the mean degree of polymerization (DP) and for the particle number (N ), and overall activation energies were estimated. These activation energies show a strong dependence on the IES employed.
Carbon fibre reinforced epoxy composites
Authors: Patel Rasmika H. , Patel Ranjan G.
Published: April 2007

Carbon fibre reinforced epoxy composites were fabricated from the matrix resin diglycidyl ether of bisphenol‐A and novel tetrafunctional epoxy resins N,N,N′,N′‐tetraglycidyl‐2,2‐bis[4‐(4‐aminophenoxy)phenyl]propane and N,N,N′N′‐tetraglycidyl‐1,1 ′‐bis[4‐(4‐aminophenoxy)phenyl]cyclohexane using diaminodiphenyl methane as curing agent. Mechanical properties and chemical resistance of the composites were determined. Significant improvements in the mechanical properties were observed by adding epoxy fortifier to the resin‐curing agent mixtures before fabrication of composites.
Spectral characterization and thermal behaviour of crosslinked poly(hydroxyethylmethacrylate) beads prepared by suspension polymerization
Authors: Kiremitçi MenemşE , Çukurova Hakan , Özkar Saim
Published: April 2007

Crosslinked poly(hydroxyethylmethacrylate) [poly(HEMA)] beads were prepared by the suspension copolymerization of 2‐hydroxyethylmethacrylate monomer with ethyleneglycol dimethacrylate (EGDMA) in aqueous media which contained only magnesium oxide (MgO) as a suspension stabilizer and also salting‐out agent. The procedure gives spherical particles with narrow size distribution. The reaction mechanism, composition and structure of poly(HEMA) beads were studied by solid‐state 13C CP/MAS NMR, FTIR, ESCA, and elemental analysis. 13C NMR implies the existence of unreacted pendant groups in the HEMA‐EGDMA copolymer. The surface composition obtained by ESCA is almost the same as the bulk composition determined by elemental analysis. FTIR spectra provide compelling evidence for the presence of carboxyl and hydroxyl groups. The glass‐transition temperature and the thermal stability of beads were determined by DSC.
Kinetics of two‐step anionic polymerization
Authors: Feng Jing , Yan Deyue
Published: April 2007

This article deals with the kinetics of two‐step anionic polymerization by way of a non‐steady state method. Several molecular parameters can be evaluated using the formulae developed. A bimodal molecular weight distribution function for the resulting polymer is derived from the set of kinetic differential equations, which is in agreement with the experimental data reported.
Radiation grafting of acrylic acid on to polypropylene filaments. I: Effect of reaction conditions
Authors: Koul Veena , Guha S. K. , Choudhary Veena
Published: April 2007

Graft copolymerization of acrylic acid on to polypropylene filaments was investigated by a simultaneous irradiation technique. The effect of various solvents and solvent combinations on swelling behaviour and on percentage grafting was studied. At a constant dose, the percentage grafting was found to be higher at low dose rates and it increased linearly up to 0.25 Mrad and then saturated. It was also observed that grafting increases with increasing monomer concentration up to 2 mole/litre. Graft copolymers were characterized by infrared spectroscopy and colour formation with methylene blue.
Copolymer composition control in emulsion polymerization using technical grade monomers
Authors: Leiza José R. , Arzamendi Gurutze , Asua José M.
Published: April 2007

A method to determine the minimum time monomer addition policy for composition control in emulsion polymerization systems when technical grade monomers are used is presented. The method involves a series of semicontinuous emulsion copolymerizations carried out under semistarved conditions. The values of the propagation rate constants, reactivity ratios and monomer partition coefficients are required to use the approach. The method is model‐independent and does not require extremely accurate measurements of the particle size. The method was checked in the methyl methacrylate‐ethyl acrylate seeded emulsion copolymerization. The monomers contained 4‐methoxyphenol as inhibitor. It was found that the iterative approach converged rapidly.
Shell growth mechanism in emulsifier‐free emulsion polymerization: Morphological and kinetic studies
Authors: Chen Show‐An , Lee Song‐Tai , Lee Shien‐Jy
Published: April 2007

For systems of emulsifier‐free emulsion polymerization having particle diameter (Dp) greater than 0.15–0.2μm, a shell‐growth mechanism for particle growth was proposed. According to the mechanism, the polymeric radicals can propagate only within the shell region having a thickness about equal to the most probable end‐to‐end distance of the terminated polymer. This mechanism was considered to result from anchoring of hydrophilic ends of the growing radicals on the particle surface and from a high average number of radicals per particle. The occurrence of limiting conversion for such large particles was attributed to the consequence of shell‐region polymerization characteristic of large emulsion particles and a monomer‐diffusion‐controlled polymerization mechanism within the particles during the high conversion period.
Monodisperse microspheres of copolymers of glycidyl methacrylate and its derivatives as materials for biomedical application
Authors: Hosaka Shuntaro , Murao Yasuo , Tamaki Hideaki , Masuko Sanae , Miura Kumiko , Kawabata Yasuro
Published: April 2007

Monodisperse microspheres of copolymers of glycidyl methacrylate were prepared by dispersion polymerization in organic media. The microsphere diameter could be adjusted in the range from 0$md$5 μm to 5μm by changing the monomer concentration, the type of dispersion medium and the content of the comonomers. Terpolymers of glycidyl methacrylate, 2‐hydroxyethyl methacrylate and tri(ethylene glycol) dimethacrylate were analysed by thermal decomposition gas chromatography and the compositions of the polymers agreed well with those of the monomer mixtures. The epoxide of the polymer microspheres was hydrolysed to α,β‐diol with dilute sulphuric acid without side reactions except the slight formation of sulphate. It was confirmed by the 13CFT‐NMR spectrum that the main structure of the hydrolysate was that of poly(glyceryl methacrylate). In the reaction of the epoxide with ammonia, the predominant production of tertiary amine was presumed by the relationship between the conversion of the epoxide and the nitrogen content of the reaction product. The amination of the epoxide with secondary amines resulted in the quantitative formation of the corresponding tertiary amines.
Grafting of polyacrylamide on to guar gum with the redox system potassium bromate/thiomalic acid
Authors: Bajpai U. D. N. , Jain Alka
Published: April 2007

The kinetics of graft copolymerization of polyacrylamide on to a natural polysaccharide guar gum have been studied in aqueous medium at 35 ± 0.2°C. Chemical initiation, using a water‐soluble redox system, potassium bromate/thiomalic acid, was used. This redox pair works in the presence of oxygen and thus makes the whole system cost‐effective. A plausible mechanism of graft copolymerization has been suggested on the basis of the experimental results obtained by varying the parameters.
Synthesis and curing behaviour of urethane‐modified epoxy resin having hydroxymethyl group
Authors: Ohtsuka Keiko , Hasegawa Kiichi , Fukuda Akinori
Published: April 2007

Synthesis and curing behaviour of urethane‐modified epoxy resins were studied. The epoxy resins were synthesized by the reaction of 4‐cresol‐type epoxy resin having hydroxymethyl group (EPCDA) with isocyanates. First, as a model compound, EPCDAPI was synthesized by the reaction of EPCDA with phenyl isocyanate (PI). EPCDAPI was heated at 180°C and the reaction products were identified and the reaction mechanism was studied. The following reactions occurred: regeneration of hydroxymethyl group and PI by thermal dissociation of urethane linkage; reaction of epoxide ring and urethane linkage; reaction of epoxide ring and regenerated PI. Urethane‐modified epoxy resin having hydroxymethyl group and urethane linkage (EPCDAMDI) was synthesized by the reaction of EPCDA with 4,4′‐diphenylmethane diisocynate (MDI). The structure was identified by IR, 1H NMR and 13C NMR. The epoxy resin was cured with a mixture of 4,4′‐diaminodiphenylmethane and 1.3‐phenylenediamine (molar ratio 6:4) as a hardener. Curing behaviour of the epoxy resin with hardener was examined by differential scanning calorimetry (DSC). It was found that onset and peak temperatures of the exothermic cure reaction of the EPCDAMDI system were lower than those of the 2‐cresol novolac‐type epoxy resin (EOCN) system, and the rate constant (k) of the cure reaction at 100° C of the former system was about six times larger than that of the latter system and was the same as that of 2‐cresol resol‐type epoxy resin (EOCDA). Viscoelastic properties of the cured resin were studied by dynamic mechanical analysis. It was found that the tan δ of the EPCDAMDI system had two peaks and the lower temperature peak disappeared after further curing over 200° C.
Characterization of crosslinked ethylene—Vinylacetate copolymers
Authors: Huskić Miroslav , Šebenik Anton
Published: April 2007

Two types of ethylene‐vinylacetate copolymers, containing 16% and 9% of vinylacetate, respectively, were crosslinked with dicumyl peroxide in a Brabender plastograf. The time of the torque maximum was proportional to the degree of crosslinking. The degree of crosslinking was determined by extraction and depended on the concentration of the crosslinking agent and of vinylacetate in the copolymer, and on the crosslinking temperature and time. It was found by DSC and by solid‐state CP‐MAS 13C NMR that with the progress of crosslinking the crystalline phase of the copolymers changed to the amorphous phase. Crosslinking took place mostly on the acetate groups.
Electrochemical, FTIR and morphological study of polypyrrole—Polystyrenesulphonate conducting films
Authors: González‐Tejera M. J. , De Plaza M. A. La , Sánchez La Blanca E. De , Hernández‐Fuentes I.
Published: April 2007

The electrochemical behaviour, FTIR spectrum and the morphology of polypyrrole‐polystyrenesulphonate (PPy‐PSS) films obtained potentiostatically at 0.6 V in a 0.05m Py + 1.7 × 10−2m NaPSS medium have been analysed. Different electrochemical parameters have been modified in order to establish the first polaron formation, the reversibility of the redox process and the doping mechanism.

The FTIR spectrum confirms the existence of CO groups in the film structure and two possible explanations are suggested. SEM reveals a higher homogeneity in these films than in PPy films doped with smaller counterions.