bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase equilibria and solution thermodynamics in the ternary system, poly(acrylic acid)‐dioxane‐water
Authors: Cowie John M. G. , Swinyard Brian 
Published: April 2007

AbstractThe 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

AbstractObservations 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

AbstractThe 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

AbstractThis 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

AbstractThe 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

AbstractA 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

AbstractTernary 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

AbstractWith 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

AbstractThe 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

AbstractCellulose 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

AbstractA 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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractThe 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

AbstractPermeation 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

AbstractConversion 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

AbstractThe 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

AbstractIt 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

AbstractThe 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

AbstractSurface 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

AbstractCarbon 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

AbstractCrosslinked 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

AbstractThis 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

AbstractGraft 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

AbstractA 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.