bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of emulsifier adsorption and nucleation of latex particles
Authors: Dunn Alexander S.
Published: April 2007

Evidence suggesting that the ultimate latex particles formed in the emulsion polymerisation of styrene are formed by the coalescence of unstable primary particles appears incompatible with the usual assumption that latex particles are predominantly nucleated from monomer‐swollen micelles in this system. However, this is not necessarily the case if the rate of emulsifier adsorption is not always sufficient to maintain a saturated monolayer of adsorbed emulsifier at the surface of growing latex particles so long as emulsifier micelles remain in the system. This appears to be the situation particularly when non‐ionic emulsifiers are used. Even with ionic emulsifiers abnormally high emulsifier/monomer ratios are needed to prevent the coalescence of primary latex particles. Some very high molecular weight polymer (controlled by the transfer constant to monomer) would be expected in the initial stage of styrene emulsion polymerisation if the micellar nucleation of latex particles is dominant.
Phase study of nylon 6/poly (acrylic acid) blends cast from solutions in aqueous formic acid
Authors: Nishio Yoshiyuki , Suzuki Hidematsu , Morisaki Kazue
Published: April 2007

Blends of nylon 6 (Ny6) with poly(acrylic acid) (PAA) were prepared in film form from solutions in a mixture of formic acid and water by evaporating the solvent. The miscibility and phase constitution of the binary blends obtained over a wide composition range (5/95–95/5) were examined by wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and dynamic mechanical measurements. A Ny6 homopolymer film and Ny6/PAA blends with PAA concentrations ≥ 50 wt% exhibited a WAXD profile stemmed from the coexistence of two different crystalline modifications of Ny6, i.e. the α and γ forms. Above 50 wt% PAA content, the solution‐cast blends showed no definite crystallinity. It was found by DSC thermal analysis that the polymer pair is substantially miscible in the non‐crystalline state, since a single glass transition temperature (Tg) was situated between the Tgs of the two homopolymers at every composition; however, the Tg versus composition plots did not follow a monotonic function but yielded a peak maximum at a PAA concentration of c. 25 wt%. In order to interpret this phenomenon, attention was given to the following point revealed by dynamic mechanical measurements: at the compositions of Ny6/PAA = 100/0–50/50, a phase of low regularity such as a nematic structure is formed in the cast films.
Anionic difunctionalization with 1,1‐bis(4‐t‐butyldimethylsiloxyphenyl) ethylene. Synthesis of ω,ω‐bis(phenol)‐functionalized polystyrene condensation macromonomers
Authors: Quirk Roderic P. , Wang Yuechuan
Published: April 2007

ω,ω‐Diphenolpolystyrenes (6) can be synthesized in quantitative yields by reacting poly(styryl)lithium with 1,1‐bis(4‐t‐butyldimethylsiloxyphenyl)ethylene (1), followed by methanol termination and hydrolysis with dilute acid. The initially formed 1,1‐bis(4‐t‐butyldimethylsiloxyphenyl)alkyllithium can be reacted with additional styrene monomer to form a polystyrene internally substituted with two in‐chain phenol groups after methanol termination and acid hydrolysis. The diphenol‐substituted polystyrene condensation macromonomers have been characterized by end‐group titration, size exclusion chromatography, thin‐layer chromatography, and ultraviolet‐visible, 1H and 13C NMR spectroscopy. Chain‐extension reactions of 6 (Mn = 2.6 × 103g mol−1) with bis(trichloromethyl)carbonate produced the corresponding comb‐type, branched polymer with estimated Mn(SEC, polystyrene standards) = 1.2 × 104g mol−1 and no detectable residual condensation macromonomer. The second order rate constants for the addition reaction of excess poly(styryl)lithium with 1 and with 1‐(4‐t‐butyldimethylsiloxy‐phenyl)‐1‐phenylethylene (3) have been estimated to be 1.7 × 10−3M−1/2S−1 and 3.2 × 10−3M−1/2S−1 respectively. A sigma value (σ) of −0.46 has been estimated for the t‐butyldimethylsiloxy substituent.
Haloaldehyde polymers 60. Co‐oligomerization of chloral and bromal
Authors: Kruger F. W. Hein , Simonsick William J. , Asada Takeshi , Ute Koichi , Hatada Koichi , Vogl Otto
Published: April 2007

Co‐oligomers of chloral and bromal were synthesized by initiating a 1:1 mixture of chloral and bromal with about 20mol% of lithium tertiary‐butoxide or lithium bornyl oxide followed by acetate endcapping. The co‐oligomer compositions were analyzed by GC, capillary GC, high resolution NMR spectroscopy and HPLC. Co‐oligomers up to the pentamers were characterized by potassium ionization of desorbed species (K+IDS) mass spectrometry.
Synthesis of new polymers via Diels–Alder reaction. III. Biscyclohexadienephthalimides as dienes
Authors: Kuhrau Martin , Stadler Reimund
Published: April 2007

Difunctional cyclohexadienes with dihydrophthalimide central units and phenyl side groups to increase solubility are used as bisdienes in repetitive Diels‐Alder polyadditions with bis(4‐(1,2,4,‐triazoline‐3,5‐dione‐4‐yl)phenyl)methane as a difunctional dienophile. The polymers show good solubility in CH2CI2 and CHCI3. Non‐stoichiometric Diels‐Alder polyaddition with slight excess of the bistriazo‐linedione provides the possibility of synthesizing telechelics with highly reactive triazolinedione end groups.
An investigation into the preparation of polyorganosiloxane materials from olivine
Authors: Bains Raghbir S. , Kendrick Dafydd Ap , Parsonage John R.
Published: April 2007

Modification of the Lentz trimethylsilylation technique was used to synthesize QxMy and QxMy(OH)2 polyorganosiloxanes from olivine (Q = SiO4/2, M = (Me3SiO1/2). The products ranged from viscous mobile liquids to hydrophobic insoluble solids with a molecular weight distribution between 3 × 103 and 400 × 103 depending on the time of addition of silylating agent, hexamethyldisiloxane (MM), to the preformed silicic acids. The stabilisation of the silicic acids leached from olivine was controlled by varying the period of silicic acid condensation‐polymerisation reactions and their solution concentration. The absence of the phase transfer agent propan‐2‐ol from the modified trimethylsilylation reaction resulted in the formation of silica gel. Propan‐2‐ol, by associating with silicic acids leached from olivine, produced a stable pre‐polymer suspension consisting of partially capped silicic acids.
A study of the thermal and dynamic mechanical properties of functionalized aryl cyanate esters and their polymers
Authors: Barton John M. , Hamerton Ian , Jones John R.
Published: April 2007

Differential scanning calorimetry (DSC) was employed to examine the thermally initiated and catalysed polymerizations of a number of cyanate ester monomers. Rigorous purification by preparative HPLC was found to have marked effects on the thermal polymerization characteristics of these compounds as determined by DSC. The effects on the thermal behaviour of varying the heating rate and level of catalysis were also examined. The thermal polymerization of the cyanate ester monomers was found to obey a first order model over wide apparent conversion limits. Functionalized cyanate ester/bis‐maleimide copolymers were prepared and the thermal stabilities of these were evaluated by thermogravimetric analysis (TGA) alongside a variety of commercial blends and homopolymers. The dynamic mechanical properties of the cured neat resins were also investigated.
Estimation of the equation of state exchange energy and entropy parameters of a polymer‐solvent pair by intrinsic viscosity measurements
Authors: Yilmaz Ferdane , Baysal Bahattin M.
Published: April 2007

The intrinsic viscosity data of linear poly(4‐chlorostyrene) in n‐propylbenzene and isopropylbenzene were used to estimate the equation of state exchange energy (X12) and entropy (Q12) parameters. The quantities estimated for X12 were 6.7 and 8.1 J cm−3 and those of Q12 were −0.069 and −0.063 J cm−3 deg−1 in n‐propylbenzene and isopropylbenzene, respectively. The average values of the chain unperturbed dimension constant (Ko) and the characteristic ratio (Cx) were found to be 0.55 × 10−3 dl mol1/2g−3/2 and 10.54, respectively, from the intrinsic viscosities measured at the corresponding θ‐temperatures.
Formation of cross‐links during prepolymerisation reaction of methylene‐bis (4‐phenylisocyanate) with poly (tetramethyleneoxide) in N,N‐Dimethylacetamide
Authors: Kamide Kenji , Hanahata Hiroyuki
Published: April 2007

An attempt was made to investigate the cross‐linking reaction which occurs as a side reaction when an excess of methylene‐bis(4‐phenylisocyanate) (MDI) is reacted with polytetramethyleneoxide (PTMO) (number‐average molecular weight 2010) in N,N‐dimethylacetamide (DMAc) prepolymerisation reaction) to give an isocyanate‐terminated prepolymer having urethane groups. Cross‐links existing in the prepolymer were shown to be of the biuret type by high performance liquid chromatography (HPLC) analysis on a product prepared by the raction of excess phenylisocyanate with n‐butanol in DMAc. The biuret‐forming reaction, as well as the urethane reaction (i.e. the main reaction), is accelerated remarkably by an N,N‐dimethyl‐N'‐phenyl(phenylcarbamoyl)acetamidine derivative formed from a side reaction of MDI with DMAc, and the former reaction is suppressed dratically by neutralising the corresponding amidine with, for ecample, H2SO4. A novel kinetic model of the prepolymerisation reaction is proposed and reaction orders and rate constants are derived. Three heterocompetitive reactions are involved: (1) urethane groups formed from MDI with PRMOin the prepolymer, and subsequent formation of (2) biuret type cross‐links between isocyanates and urea groups formed from MDI with DMAc as a side reaction, and (3) the corresponding amidine derivative.
A novel synthesis of polymers with anthracene and dihydroanthracene subunits in the main chain
Authors: Bartz Thomas , Klapper Markus , Müllen Klaus , Schulz Rolf C.
Published: April 2007

A new polycondensation method to connect redox‐active and chromophoric subunits by forming a C‐C bond and leading to a polyhydrocarbon is described. 1,ω‐bis(9,10‐Dihydro‐9‐anthry)alkanes with various alkylene spacers can be deprotonated by butyllithium to afford a monoanion in each dihydroanthracene moiety. Alkylation with dielectrophiles such as dibromoalkanes yields soluble polymers with dihydroanthracene units in the main chain. The reaction proceeds regioselectively in the 9,10‐position. Aromatization generates a polymer with anthracene units. The molecular weights are determined by GPC up to M̄n = 10 000. To prove the structure and to calibrate the GPC, suitable model compounds were synthesized.
Miscibility and enthalpy relaxations in polysulfone—Carboxylated polysulfone blends
Authors: Lau Wayne W. Y. , Jiang Y. Q. , Tan Pedro P. K.
Published: April 2007

Phase behavior in polysulfone‐carboxylated polysulfone (PSf‐CPSf) blends was studied by glass transition observations in conjunction with enthalpy relaxation technique. Miscibility in all proportions was detected in blends where CPSf has a degree of carboxylation (DC, i.e. number of carboxyl groups per repeat unit) less than about 1.3. Partial miscibility was detected in blends for DC > 1.4 and up to DC = 1.9, probably as a result of decreasing intermolecular interactions with increase in DC.
Polymerization of isoprene initiated by α, ω‐dilithiopolyisoprene: 7Li NMR study of lonic species
Authors: Madani Abdelaziz El , Belleney Joël , Favier Jean‐Claude , Hémery Patrick , Sigwalt Pierre
Published: April 2007

7Li nuclear magnetic resonance (NMR) of dilute solutions in hexane of α, ω‐dilithiopolyisoprenes with two degrees of polymerization (DP) values was studied at several temperatures. For DP ≈ 500, the spectrum is similar to that of monofunctional poly(isoprenyl)lithium. When the DP is low (e.g. 80) new resonances appear upfield, showing the existence of more aggregated species. Their formation was attributed to the ability of dilithio compounds to undergo cyclization by intramolecular association. These observations and a computer simulation permit us to explain the kinetics of polymerization.
Solution properties of poly(fluorostyrene‐co‐chlorostyrene) copolymers. I. Light scattering, differential refractometry and viscometry
Authors: Segudovic Nikola , Vukovic Radivoje , Kuresevic Vjera , Karasz Frank E. , Macknight William J.
Published: April 2007

The weight‐average molecular weights (M̄w) of nominally random, unfractionated copolymers of ortho‐ and para‐fluorostyrene and ortho‐ and para‐chlorostyrene were determined by light scattering measurements in tetrahydro‐furan, toluene, carbon tetrachloride and chloroform. It was shown that there is no significant variation in measured M̄w in the various solvents, a finding indicating that the copolymers are not compositionally heterogeneous. Intrinsic viscosity measurements in the same solvents established a consistent relationship between [n] and M̄w despite the differences in copolymer compositions. It was not possible to establish a similar relationship between the second virial coefficient A2 and M̄w. It was concluded that measurements of the specific refractive index increment could be used for determining copolymer composition if the measurements were performed in thermodynamically poorer solvents. The results established for the Mark‐Houwink constant α, intrinsic viscosity, and A2 values indicated that these solvated copolymer molecules are in a less expanded conformation than are polystyrene molecules of similar molecular weights in a given solvent.
Polyelectrolyte solutions. Electrical conductivity and counterion condensation
Authors: Ricos Hernán E. , Barraza Raúl G. , Gamboa Irma C.
Published: April 2007

We have analyzed the electrical conductivity of a linear high charge density polyelectrolyte aqueous solution, finding that the counterion association order follows the same pattern as that described for a cyclic monomeric polyelectrolyte, i.e. NO > Br− > Cl− > F−. However, these counterions interact in a very different manner with this polyion, making Eisenberg's relationship inapplicable in this system. Consequently, an alternative method is proposed for treating data.
Synthesis, characterization and kinetics of terpolymerization of acrylonitrile, N‐vinyl pyrrolidone and styrene
Authors: Kumar Paritosh , Narayan D. , Srivastava A. K.
Published: April 2007

Synthesis of a series of novel terpolymers, consisting of two electron‐donating monomers, viz. N‐vinyl pyrrolidone (N‐VP) (heterocyclic polar monomer) and styrene (Sty) (non‐polar monomer), with one electron‐accepting polar monomer, i.e. acrylonitrile (AN), using α,α'‐azobisisobutyronitrile as radical initiator and benzene as diluent at 60°C, has been extensively surveyed. Besides the synthesis, an attempt has been made to study the kinetics and various properties of the terpolymers, such as softening temperature and chemical resistance. The system follows non‐ideal kinetics and the kinetic equation for the present system can be written as
equation image

This non‐ideality can be explained on the basis of significant initiator‐dependent termination through primary radicals and degradative chain transfer to acrylonitrile monomer. The overall energy of activation is 72.4 kJ mol−1 and kp2/kt is 0.26 × 10−3 litre mol−1 s−1.

The effects of various additives such as imidazolium‐p‐chlorophenacylide (ICPY) and ZnCl2 were also studied. ICPY functions as a chain transfer agent (Ctr = 0.43 × 10−4), whereas ZnCl2 accelerates the rate of reaction. IR spectroscopy was used to confirm the structure of the terpolymers.
Studies on kinetics of bulk polymerization of divinyl ester by radical‐initiated thermal and photo‐polymerization
Authors: Chandra R. , Soni R. K.
Published: April 2007

Di(2‐hydroxy propane methacrylate) ester of adipic acid (DAP) was prepared by reacting adipic acid with glycidyl methacrylate using triphenyl phosphine as catalyst. The kinetics of bulk polymerization of the prepared compound using benzoyl peroxide as initiator were determined using isothermal differential scanning calorimetry (DSC). The kinetic order of the reaction (order exponent n and autocatalytic exponent m) and apparent reaction rate constant (k) were determined. The kinetics of radical‐initiated photo‐polymerization of DAP were also studied by differential photocalorimetry (DPC), using benzophenone as initiator. The rate of reaction was found to be much higher in radical‐initiated photo‐polymerization than in radical‐initiated thermal polymerization.
Functionality distribution and crosslink density of hydroxyl‐terminated polybutadiene
Authors: Ninan K. N. , Balagangadharan V. P. , Ambikadevi K. , Catherine K. B.
Published: April 2007

A novel approach is proposed for estimating the average molecular weight between crosslinks (M̄c) from the functionality distribution of hydroxyl‐terminated polybutadiene (HTPB). The functionality distribution of four free‐radically polymerised HTPB prepolymers of varying hydroxyl content and molecular weight was determined by a combination of preparative and analytical gel permeation chromatography. The gumstock properties of the samples cured with stoichiometric amounts of toluene diisocyanate were not correlatable with the relative amounts of difunctional chain extender and multifunctional crosslinker present, unlike the case of HTPB with similar hydroxyl content and molecular weight. However, the mechanical properties and sol content could be correlated with the average molecular weight between crosslink sites, M̄c, of the cured polymer. The M̄c values derived by our method compare well with those of classical methods, and the observed differences are attributed to segmental entanglement. These M̄c values give consistently good correlation with all the gumstock properties, confirming the validity of our approach and the soundness of the techniques developed for the determination of the functionality distribution of HTPB.
Template polymerization of chromium acrylate
Authors: Chaturvedi Bharti , Srivastava A. K.
Published: April 2007

The template polymerization of chromium acrylate (CrA3) with poly‐(vinyl acetate) (PVAc, M̄v = 56 265) at 90 ±0.1°C for 2 h in dimethylformamide has been studied dilatometrically to examine the effects of concentration and average molecular weight of template, and of monomer concentration upon the kinetics and mechanism of template polymerization. The viscometric measurements showed that the complexation between poly‐CrA3 and PVAc was at a maximum when the template/polymer ratio was 1:1, and the time required for complete complexation was 8 min. The value of the coefficient of interaction (KAB) between the two polymers was high for DMSO, medium for DMF and low for dioxane, and is a direct function of the polarity of the solvent. The KAB values indicate that an interaction, which consists of van der Waals forces and hydrogen bonding, exists between the polymers. The overall activation energy was 72.1 and 57.3 kJ mol−1 in the absence and presence of PVAc, respectively.
Structure in mesogenic diol‐containing polyesters
Authors: Fischer Hartmut , Karasz Frank E. , Macknight William J.
Published: April 2007

Copolyesters synthesized from two mesogenic monomers have been investigated. The monomers are 4,4′‐bis(6‐hydroxyhexoxy)biphenyl (BHHBP) and the p‐diester made from terephthaloyl dichloride and p‐hydroxybenzoic acid. The incorporation of a very rigid, second mesogen increases the ability of BHHBP to form tilted mesophases. An untilted smectic A phase is formed initially, but the final, stable phase is a highly ordered, tilted smectic phase. Similar behavior is observed when BHHBP is combined with a mixture of the diacids of the crown ether dibenzo‐18‐crown‐6. A copolymer of this type also forms a smectic A phase. For both types of copolymers, there is good agreement between the measured and calculated values for the layer distances.
Synthesis of amphiphilic polystyrene–ionene diblock copolymers with controlled block lengths
Authors: Schipper Eugène T. W. M. , van Hest Jan C. M. , Roelofs Alexander H. C. , Piet Pieter , German Anton L.
Published: April 2007

Amphiphilic polystyrene‐ionene diblock copolymers with blocks of controlled molecular weights were synthesized by a new method. The preparation starts with the anionic polymerization of styrene with 3‐(dimethylamino)propyl‐lithium as initiator, yielding tertiary amino end‐functionalized polystyrenes of molecular weights that can be varied over a wide range from 1 to 100kg/mol, and a relatively low polydispersity (M̄w/M̄n = 1.1–1.4). The crucial step in this method is the stepwise coupling of the reactive end‐group of the polystyrene with bromo‐ and tertiary‐amino‐terminated monodisperse oligomeric 2,4‐ionenes. The amphiphilic polymers with well‐defined block lengths were characterized by thin‐layer chromatography, end‐group titration and elemental analysis. Amphiphilic block copolymers with a monodisperse ionene block consisting of up to 10 quaternary ammonium groups could be derived.
Kinetic investigation of the radical polymerization of N‐acryloylpiperidine in solution
Authors: Ebraheem Kais A. K. , Al‐Issa Mahmoud A. , Mohammed Nedhal Y.
Published: April 2007

The kinetics of free radical polymerizations of N‐acryloylpiperidine (NAPi) were studied in benzene (Bz) using 2,2′‐azobisisobutyronitrile (AIBN) as initiator. The activation energy was determined to be 111.7 kJ mol−1. The overall rate of polymerization of the NAPi‐AIBN‐Bz system at 60°C was investigated as a function of monomer and initiator concentrations. Deviation from normal kinetics was observed with an order of 1.48 with respect to the monomer. The observed dependence of the rate constants kp/k on monomer concentration could not be explained by the diffusion theory or the theory of electron donor‐acceptor (EDA) complexes. The observed data have, however, been satisfactorily interpreted by the ‘hot’ radical theory.
Thermal and mechanical properties of thermoplastic polyurethane elastomers from different polymerization methods
Authors: Ahn Tae Oan , Choi Ii Seok , Jeong Han Mo , Cho Kilwon
Published: April 2007

Thermoplastic polyurethane elastomers (TPUs) based on 4,4′‐methylene‐diphenyl diisocyanate, poly(tetramethylene glycol), diamine‐terminated aliphatic nylon oligomer, and 1,4‐butanediol were synthesized by two different polymerization methods, i.e. one shot and prepolymer methods. The effects of the polymerization method on the thermal and mechanical properties of the TPUs have been studied. A broader distribution of hard segment lengths in TPUs prepared by the one shot method was observed from thermal and tensile property measurements, compared with those prepared by the prepolymer method. TPUs by the one shot method showed a higher Tm of the hard segments and better tensile properties when soft‐hard segment interaction was relatively small. However, inferior tensile properties were observed when the soft‐hard segment interaction was high; typically when nylon oligomer was used as a soft segment.
Association between polyether–polyamine block‐copolymers and low molecular weight polyacids in solution
Authors: Toncheva Veska , Velichkova Roumiana , Trossaert Geert , Goethals Eric J.
Published: April 2007

An ABA block‐copolymer in which A is a poly(N‐tert‐butylimino‐ethylene) segment and B a poly(oxytetramethylene) segment has been prepared. The salt form of this polymer, obtained with low molecular weight polycarboxylic acids such as citric acid or benzene‐1,3,5‐tricarboxylic acid, was found to form ionic networks in organic solvents of low or medium polarity, when the concentration of the polymeric salt exceeded a critical concentration, between 2 and 4wt%. The viscosities of the polymeric salt solutions were strongly pseudoplastic, showing a yield point and thixotropic behaviour.
Durable glass–epoxy composites cured at low temperatures—Effects of thermal cycling, UV irradiation and wet environment
Authors: Rinaldi Gilberto , Maura Giancarlo
Published: April 2007

Glass‐fibre‐epoxy composites cured with oligomeric polyaminophenolic agents have shown good dimensional stability during thermal cycling at temperatures over 100°C, even if their curing is carried out at room temperature. It was therefore believed important to evaluate their behaviour in different environmental conditions. Their good mechanical characteristics are maintained after saturation with water, UV irradiation, and thermal cycling between 0 and 110°C. From the following tests the environmental resistance is clearly higher than that of composites cured with other aminic agents.
Curing theory of the Aai–Bbj type polycondensation. (I) intramolecular cyclization and gelation equations
Authors: Zheng Fu‐An , Liu Feng‐Qi , Tang Xin‐Yi
Published: April 2007

This paper investigates in detail the ring‐chain competition in Aai–Bbj type polycondensations by use of a molecular model of tree branching and the basic principles of probability. The intramolecular cyclization equations and the critical gelation condition containing both intermolecular and intramolecular reaction parameters have been obtained.
Curing theory of the Aai–Bbj type polycondensation. (II) sol‐gel distribution
Authors: Zheng Fu‐An , Hu Yu‐Xin , Min Yong‐Gang , Tang Xin‐Yi
Published: April 2007

An alternative way is proposed to approach the sol‐gel distribution of Aai–Bbj type polycondensation by taking into consideration intramolecular reaction. The equations deduced basically from the definition of the sol fraction and the chemical equilibrium of reactants in this paper can be reduced to those of Tang Au‐chin's and Miller's expressions. Comparing experimental with theoretical values, we found that the results of this paper are closer to the real cases than those of other authors.
Stability and compatibility in blends of silicone and vinylacrylic polymer emulsions
Authors: Richard J. , Mignaud C. , Sartre A.
Published: April 2007

Special, unexpected properties may arise from blending of polymer emulsions, depending on the miscibility and stability of the resulting dispersions on the one hand, and the morphology of the films obtained upon drying on the other hand. In the field of water‐repellent paints, blends of silicone and vinylacrylic copolymer emulsions have been previously shown to be a tricky means to associate binding ability and water permeability properties in the same material. It is currently assumed that the resulting morphology and physical properties of films obtained from these blends upon drying is partially controlled by the compatibility of the two kinds of polymers. In the present paper, the crucial problem of stability and compatibility in blends of silicone and vinylacrylic copolymer emulsions is investigated; more particularly, the effect of pH of the vinylacrylic copolymer latex, as well as the influence of the stabilizing system of both emulsions, on the stability of emulsion blends is qualitatively described. As regards the morphology of the films, the strong incompatibility of the two polymers is shown, which results in large macroscopic heterogeneities in the dried composite films. Furthermore, semi‐quantitative angle‐resolved ESCA measurements have evidenced a pronounced diffusion of the silicone species towards the surface of the samples. Investigations into different ways to increase compatibility of the two phases is presented. It is shown that phase separation at the macroscopic scale can be controlled either by lowering the interfacial tension between the two phases by grafting silane compatibilizers on to the latex particles, or by decreasing the molecular mobility of the silicone phase by cross‐linking. Diffusion of the silicone chains towards the surface of the composite films can only be significantly restricted by cross‐linking of this species.
Synthesis and characterisation of carboxylic acid and diphenylphosphine derivatives in the 1,3‐diyne series: Spectral properties of polydiacetylene carboxylates
Authors: Agh‐Atabay N. M. , Lindsell W. Edward , Preston Peter N. , Tomb Peter J.
Published: April 2007

Symmetrically substituted 1,3‐diynes containing hydroxyalkyl (1a‐d), bromoalkyl (1e‐h) (diphenylphosphinyl) (1i‐k) and carboxyalkyl (2a‐d) substituents have been prepared and characterised; the phosphine derivative (1k) has been converted with alkyl iodides (RI; R = Me, Et) into bis(phosphonium) salts (1l and m). During preparation of the diynedioic acid. (2a), the non‐centrosymmetrical diyne, HO2CCH2CC—CC(CH2)2OH (3), was also isolated. 60Co γ‐Irradiation of diacetylene monomers (2a–d) and 10,12‐tricosadiyn‐1‐oic acid gave the corresponding polydiacetylene derivatives (4a–d and 5), respectively. Rubidium salts of (4c) and (4d), a barium salt of (4c), and a potassium salt of (5) were prepared and isolated; soluble potassium salts of the carboxylic acid polymers (4) were generated in aqueous solution. The effects of changes in pH on the UV/visible absorption spectra of aqueous solutions of selected carboxylic acid polydiacetylenes have been recorded, and are discussed.
Reactivity ratios for new copolymerizations relevant to thermosetting resins
Authors: Mao Runsheng , Huglin Malcolm B. , Davis Thomas P. , Overend Andrew S.
Published: April 2007

Free radical copolymerizations of four new systems, namely (1) methyl methacrylate (MMA) with β‐acryloxypropionic acid (AOPA); (2) MMA with p‐styrene sulphonyl chloride (SSC); (3) 2‐[(phenylamino) carbonyl] oxyethyl methacrylate (PCOMA) with 2‐phenoxyethyl methacrylate (PEMA); and (4) PCOMA with 1‐methyl‐2‐phenoxyethyl methacrylate (MPEMA), have been carried out at 60°C for systems 1 and 2 and at 70°C for systems 3 and 4. The copolymer compositions were analysed by acid‐base titration for system 1 and by FTIR for systems 2–4. The monomer reactivity ratios as well as the 95% individual confidence intervals and 95% joint confidence intervals were calculated from the Kelen‐Tüdős method, the Extended Kelen‐Tüdőos method, and from a new iterative linear method by Mao and Huglin. The results show that all these copolymerizations are strictly linear systems describable by the Mayo‐Lewis equation based on the terminal model and that accurate reactivity ratio data can be obtained. The Q‐e values of the monomers AOPA and SSC have been estimated. Some physical properties of AOPA, PEMA and MPEMA are also presented for the first time.
Nucleophilic reactivity of aniline derivatives towards the nitroso group
Authors: da Silva Gabriel , Kennedy Eric M. , Dlugogorski Bogdan Z.
Published: April 2007

This study investigates the reactivity of the electrophilic nitroso group towards nucleophilic aniline derivatives from various nitrosating agents. A relationship between the rate of nitrosation and Edwards' nucleophilic parameter (En) is disclosed, indicative of a transition state that is mostly product‐like in nature with respect to cleavage of the nitroso bond in the nitrosating agent. A similar relationship based on the work of Marcus provides a considerably better explanation of the data. Through application of the Marcus equation, the free energy change of reaction is calculated for the nitrosation reactions studied, which in turn is applied to develop an equation linking the free energy of formation of a nitrosamine and its corresponding protonated amine. This equation accounts for the often‐observed Brønsted relationships in nitrosation reactions. The intrinsic barrier to reaction is estimated to be 10 kJ mol−1, indicating that the main impedance to nitrosation arises from the unfavourable reaction thermodynamics. However, for the nitrosation of aniline derivatives substituted with π‐electron withdrawing groups, an unbalancing of the transition state results in an increased intrinsic barrier, of the order of 19 kJ mol−1. For electronic‐effect aniline derivatives, a More O'Ferrall–Jencks diagram shows the nitrosation transition state to be synchronously well balanced between reactants and products. This diagram also confirms that the reaction follows a concerted mechanism. The nitrosation of resonance‐stabilised aniline derivatives is somewhat less synchronous, however, due to delocalisation of the lone electron pair on the amino group, induced by π electron withdrawing substituents. Transition states were located according to the theory of harmonic parabolic wells. The results of these calculations agreed with transition state locations predicted using linear free energy relationship techniques. A method is developed which approximates free energy profiles by treating the product and reactant free energy wells as harmonic parabola, while the free energy profile around the transition state is taken as the parabolic barrier to the product and reactant energy wells. Applying this technique, free energy profiles for electronic‐effect and resonance‐stabilised aniline nitrosation are predicted, utilising measured kinetic values and predicted thermodynamic properties. We couple the simulated free energy profiles with their corresponding More O'Ferrall–Jencks diagrams in order to elucidate the three‐dimensional reaction path traversed between reactants and products, in terms of both structure and energy. We also demonstrate that the nitrosonium ion behaves as a soft acid, and should therefore undergo covalent frontier‐orbital controlled bonding. Copyright © 2007 John Wiley & Sons, Ltd.
Work disability associated with cancer survivorship and other chronic conditions
Authors: Short Pamela Farley , Vasey Joseph J. , BeLue Rhonda
Published: April 2007

The long‐term effects of cancer and its treatment on employment and productivity are a major concern for the 40% of cancer survivors in the U.S. who are working age. This study's objectives were (1) to quantify the increase in work disability attributable to cancer in a cohort of adult survivors who were an average of 46 months post‐diagnosis and (2) to compare disability rates in cancer survivors to individuals with other chronic conditions. Data from the Penn State Cancer Survivor Study (PSCSS) and the Health and Retirement Study (HRS) were compared. The PSCSS sample included 647 survivors age 55–65, diagnosed at four medical centers in Pennsylvania and Maryland. There were 5988 similarly aged subjects without cancer in the HRS. Adjusted odds ratios for work disability were estimated for cancer survivorship, heart disease, stroke, diabetes, lung disease, and arthritis/rheumatism with multivariate logistic regression. Even for cancer‐free survivors, the adjusted disability rate was significantly higher in comparison to adults with no chronic conditions (female OR = 1.94; male OR = 1.89). There were few significant differences between disability rates for cancer and other conditions. The elevated disability rate is another argument for viewing cancer survivorship as a chronic condition potentially requiring a broad range of psychosocial services. Copyright © 2007 John Wiley & Sons, Ltd.
The impact of physical and psychosocial factors on work characteristics after cancer
Authors: Steiner John F. , Cavender Tia A. , Nowels Carolyn T. , Beaty Brenda L. , Bradley Cathy J. , Fairclough Diane L. , Main Deborah S.
Published: April 2007

Most previously employed cancer survivors continue to work after treatment, but the impact of cancer symptoms or psychosocial concerns on their work has seldom been assessed. We conducted a community‐based survey of cancer survivors from the Colorado Central Cancer Registry to assess the changes in their work and the demographic, clinical, and psychosocial characteristics associated with work changes over the 2 years following diagnosis. Of 100 survivors, 92 returned to work, but 57% of those reduced their work by more than 4 h/week, and 56% noted a change in some aspect of their occupational role. Physical symptoms, particularly lack of energy or nausea/vomiting, and psychological symptoms, particularly feeling bored or useless or feeling depressed, were significantly associated with a reduction in work hours or a change in occupational role. Since changes in work are common and are associated with both physical and psychosocial symptoms, strategies are needed to reduce symptom burden and barriers to work and to improve work capacity for working‐age cancer survivors. Copyright © 2007 John Wiley & Sons, Ltd.
Cutoff value of lipid‐laden alveolar macrophages for diagnosing aspiration in infants and children
Authors: Furuya María E.Y. , Moreno‐Córdova Verónica , Ramírez‐Figueroa Jorge L. , Vargas Mario H. , Ramón‐García Guillermo , Juan David H. Ramírez‐San
Published: April 2007

Chronic passage of gastric and/or alimentary material into the airways is a frequent and difficult‐to‐diagnose condition. Because alveolar macrophages phagocytose aspirated material, it has been suggested that their identification is a useful diagnostic method. To know the usefulness of the lipid‐laden alveolar macrophages (LLAM) index as a diagnostic tool for aspiration, children from 1 month to 16 years of age were included in three groups: G‐I, children with pulmonary pathology and suspicion of aspiration by clinic or image evaluation; G‐II, with pulmonary pathology without suspicion of aspiration; and G‐III, without respiratory symptoms nor suspicion of aspiration. Bronchoalveolar lavage was obtained through bronchoscopy in G‐I and G‐II, and through endotracheal tube in G‐III, and the LLAM index (0–400) was determined. A total of 112 patients (41, 30, and 41 in G‐I to III, respectively) were studied. LLAM index (mean ± SEM) was highest in G‐I (233.2 ± 5.5), as compared with G‐II (187.8 ± 11.6, P < 0.05), and G‐III (108.5 ± 13.5, P < 0.001). However, notable overlap of LLAM values was observed between G‐I and G‐II, and between G‐II and G‐III. When patients from G‐I and G‐III were jointly analyzed, the area under the ROC curve for diagnosing aspiration was 0.92, with a best cutoff value of >165 (98.6% sensitivity, 78.0% specificity, 87.8% overall accuracy). LLAM index, with a cutoff value of >165 is a useful diagnostic test for aspiration when there is suspicion of this condition. However, due to its low specificity, it does not discriminate other causes of chronic lung disease. Pediatr Pulmonol. 2007; 42:452–457. © 2007 Wiley‐Liss, Inc.
Human metapneumovirus bronchiolitis in infancy is an important risk factor for asthma at age 5
Authors: García‐García M.L. , Calvo C. , Casas I. , Bracamonte T. , Rellán A. , Gozalo F. , Tenorio T. , Pérez‐Breña P.
Published: April 2007

Background

Human metapneumovirus (hMPV) infection plays an important role in the pediatric respiratory infections. However, little is known about the relationship between hMPV‐bronchiolitis and the development of subsequent wheezing. The aim of this study was to evaluate the outcome at third to fifth year after admission for hMPV‐bronchiolitis and to compare it with children admitted for respiratory syncytial virus (RSV)‐bronchiolitis and with children without lower respiratory disease in the first 2 years of life.

Methods

We studied 55 children (23 hMPV and 32 RSV acute bronchiolitis) aged 3–5 years and hospitalized during the seasons 2000–2005. Thirty‐eight children admitted due to acute rotavirus gastroenteritis in the same seasons, and without bronchiolitis during infancy, were also analyzed. Clinical data were collected through structured clinical interviews at the follow‐up visit. Skin prick tests to food and inhaled allergens were performed.

Results

Asthma was significantly more frequent in children with hMPV‐bronchiolitis (odds ratio (OR) = 5.21), RSV‐bronchiolitis (OR = 4.68), allergic rhinitis (OR = 1.7), and siblings with atopy (OR = 1.75). In the multivariate analyses, hMPV was the most important risk factor for asthma in preschool years (OR = 15.9), followed by RSV‐bronchiolitis (OR = 10.1) and allergic rhinitis (OR = 4.9).

No differences were found with respect to allergic rhinitis, atopic dermatitis, food allergy, proportion of positive prick tests, family history of atopy, and asthma.

Conclusions

hMPV‐bronchiolitis in infancy was strongly associated with asthma as well as other forms of bronchial obstructive disease at third and fifth year of life. This association is, at least, as strong as the association observed with RSV infections. Pediatr Pulmonol. 2007; 42:458–464. © 2007 Wiley‐Liss, Inc.
Thermal Decomposition of Organic Peroxides TATP and HMTD by T‐Jump/FTIR Spectroscopy
Authors: Hiyoshi Reiko I. , Nakamura Jun , Brill Thomas B.
Published: April 2007

The thermal decomposition of the peroxides, triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) was investigated as a function of pressure, temperature and atmosphere by T‐jump/FT‐IR spectroscopy. In an Ar atmosphere at fast heating rates, the dominant decomposition product of TATP was methane rather than acetone which dominates at slow heating rates. The products of TATP were different in Ar and in air which implies that decomposition occurs primarily in the gas phase. In contrast, the products from HMTD were independent of the surrounding atmosphere implying that it decomposes primarily in the condensed phase. The IR spectra of the decomposition products of HMTD exhibited some dependence on pressure but not on the pyrolysis filament temperature.
Vapor Pressures, Mass Spectra and Thermal Decomposition Processes of Bis(2,2‐Dintropropyl)acetal (BDNPA) and Bis(2,2‐Dinitropropyl)formal (BDNPF)
Authors: Rauch Rory B. , Behrens Richard
Published: April 2007

Simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) and Fourier‐transform ion cyclotron resonance (FTICR) instruments have been used to measure the mass spectra, measure vapor pressures and evaluate the thermal decomposition mechanism of bis(2,2‐dinitropropyl)acetal (BDNPA) and bis(2,2‐dinitropropyl)formal (BDNPF). The high mass accuracy FTICR mass spectra provide the chemical formulas of the ion fragments formed in the mass spectra of BDNPA, BDNPF and their decomposition products, and provide a basis for predicting possible structures of the ion fragments. The heat of vaporization (ΔvapH) and vapor pressure at 25 °C are 93.01±0.38 kJ/mol and 1.4532+0.40/−0.27 mPa for BDNPA, and 84.77±0.88 kJ/mol and 2.20+1.87/−1.07 mPa for BDNPF. STMBMS data support a nitro‐nitrite (NO2→ONO) rearrangement mechanism for both compounds. Upon rearrangement, both NO and NO2 are cleaved from the structure, thus producing a ketone radical. The nitro‐nitrite rearrangement begins to occur at appreciable rates between 160 and 180 °C. Additional decomposition products include amines, imines and amides, as well as CO2 and H2O at higher temperatures. STMBMS mass loss data suggest the formation of a residue during the decomposition of BDNPA and BDNPF. The major difference between the decomposition of the two compounds is the slower reaction rate of BDNPF. We postulate that the less sterically hindered formal carbon of BDNPF subjects it to interactions with an intermediate, thus forming a complex and delaying its release. Methods to elucidate complex thermal decomposition mechanisms from STMBMS data are illustrated.
Combustion Reactions of Poly(Carbon Monofluoride), (CF)n, with Different Reductants and Characterization of the Products
Authors: Cudziło Stanisław , Szala Mateusz , Huczko Andrzej , Bystrzejewski Michał
Published: April 2007

Mixtures of poly(carbon monofluoride) also known as graphite fluoride, (CF)n, with different reductants, such as NaN3, B, Ti, ZrTi, Si, CaSi2, AlSi, TiSi, MoSi2 and CrSi2 were investigated. Reactions between these substrates are fast and exothermic enough to proceed in a high temperature, self‐sustaining regime. Heat effects accompanying the reactions were measured and the solid reaction products were analyzed. SEM observation revealed the presence of exfoliated graphite in each case. Nanostructures, like nanofibers, nanorods, nanospheres and nanosized crystals, were also present in most of the products. Phase (XRD) and elemental composition as well as porous structure (N2 adsorption) of chosen reaction products were also determined.
Application of Cerimetric Methods for Determining the Metallic Aluminum Content in Ultrafine Aluminum Powders
Authors: Fedotova Tatyana D. , Glotov Oleg G. , Zarko Vladimir E.
Published: April 2007

Ultrafine (nano‐sized) aluminum is a promising component for solid propellants, gel propellants, explosives, etc. The work is focused upon a problem of determining active (metallic) aluminum content in nanoAl powders as one of the characteristics of their reactivity. It is shown that the high reactivity, the presence of either the gases adsorbed or coating matter on the particle surface restricts the traditionally used permanganatometric and volumetric analytic methods. A new technique determining the active aluminum content is presented. This is the adaptation of known cerimetric method based on the analytical reaction Ce4++e−=Ce3+. The method can be applied for analysis of metallic aluminum in the probes of nanoAl (including ones with organic coating), as well as micron sized aluminum, and their condensed combustion products.
On Shear Rheology of Gel Propellants
Authors: Rahimi Shai , Peretz Arie , Natan Benveniste
Published: April 2007

Selected fuel, oxidizer and simulant gels were prepared and rheologically characterized using a rotational rheometer. For fuel gelation both organic and inorganic gellants were utilized, whereas oxidizers and simulants were gelled with addition of silica and polysaccharides, respectively. The generalized Herschel‐Bulkley constitutive model was found to most adequately represent the gels studied. Hydrazine‐based fuels, gelled with polysaccharides, were characterized as shear‐thinning pseudoplastic fluids with low shear yield stress, whereas inhibited red‐fuming nitric acid (IRFNA) and hydrogen peroxide oxidizers, gelled with silica, were characterized as yield thixotropic fluids with significant shear yield stress. Creep tests were conducted on two rheological types of gels with different gellant content and the results were fitted by Burgers‐Kelvin viscoelastic constitutive model. The effect of temperature on the rheological properties of gel propellant simulants was also investigated. A general rheological classification of gel propellants and simulants is proposed.
An Advanced GAP/AN/TAGN Propellant. Part I: Ballistic Properties
Authors: Judge Michael D. , Lessard Pierre
Published: April 2007

A solid rocket propellant based on glycidyl azide polymer (GAP) binder plasticized with nitrate esters and oxidized with a mixture of ammonium nitrate (AN) and triaminoguanidine nitrate (TAGN) was formulated and characterized. Non‐lead ballistic modifiers were also included in order to obtain a propellant with non‐acidic and non‐toxic exhaust. This propellant was found to exhibit a burning rate approximately twice that of standard GAP/AN propellants. The exponent of the propellant is high compared to commonly used composite propellants but is still in the useable range at pressures below 13.8 MPa. This propellant may present a good compromise for applications requiring intermediate burn rate and impulse combined with low‐smoke and non‐toxic exhaust.
Targeted molecular dynamics simulation studies of binding and conformational changes in E. coli MurD
Authors: Perdih Andrej , Kotnik Miha , Hodoscek Milan , Solmajer Tom
Published: April 2007

Enzymes involved in the biosynthesis of bacterial peptidoglycan, an essential cell wall polymer unique to prokaryotic cells, represent a highly interesting target for antibacterial drug design. Structural studies of E. coli MurD, a three‐domain ATP hydrolysis driven muramyl ligase revealed two inactive open conformations of the enzyme with a distinct C‐terminal domain position. It was hypothesized that the rigid body rotation of this domain brings the enzyme to its closed active conformation, a structure, which was also determined experimentally. Targeted molecular dynamics 1 ns‐length simulations were performed in order to examine the substrate binding process and gain insight into structural changes in the enzyme that occur during the conformational transitions into the active conformation. The key interactions essential for the conformational transitions and substrate binding were identified. The results of such studies provide an important step toward more powerful exploitation of experimental protein structures in structure‐based inhibitor design. Proteins 2007. © 2007 Wiley‐Liss, Inc.