bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of quench‐rolled polyethylene film
Authors: Kwei T. K. , Wang Tsuey T. , Bair H. E. 
Published: June 2010

AbstractThe dynamic mechanical properties, creep, and melting characteristics of a transparent polyethylene film prepared by a novel process of simultaneous high speed quenching and shear were examined. A high degree of orientation was attained in the process, the polymer chain backbone being aligned in the direction of shear. As a result of chain orientation, the dynamic in‐phase moduli in the temperature range from −160 to +120°C are about three to seven times the values for the compression‐molded material. Changes in β and α dispersion peaks are also noticed. The quench‐rolled film contains high melting point fractions which suggest very strongly the presence of thick crystals, perhaps up to about 1000 Å in thickness. Excellent resistance to creep, comparable to that of the cold‐drawn polyethylene, was observed.
Fluorescence methods in polymer science
Authors: Nishijima Yasunori 
Published: June 2010

AbstractVarious aspects of the application of fluorescence characteristics in the field of polymer research are described. The polarization characteristics of fluorescence, that is, the angular distribution of the intensity of the polarized component, are indicative of the distribution patterns of fluorescent molecules in the medium. This principle can be utilized for the investigation of molecular orientation behavior in polymer solids. Examples are given for the molecular orientation behaviors during the deformation of poly(vinyl alcohol) and polypropylene films. The phenomenon of rotational depolarization of fluorescence is applied to the measurement of micro‐Brownian motions of polymer chains and the local viscosity of polymer solutions and melts. The internal structure of concentrated poly(styrene) solutions and the molecular motions in the melts of n‐paraffins and polyethylene homologs are discussed. Rotational relaxation time ranging from 10−12 to 10−5 sec can be measured by this method by using the lifetime of excitation of fluorescent groups as the reference time scale. The phenomenon of the excimer fluorescence emitted from the excited dimer provides a new method for studying molecular configuration and conformation of polymer molecules. Examples are given for the case of naphthalenecontaining polymers. The sequence of monomeric units in copolymers of vinylnaphthalene and styrene are studied from the intensity of excimer fluorescence relative to that of ordinary fluorescence from the naphthalene groups. The intramolecular excimer formations of polymer molecules are also discussed in relation to molecular motions.
On the use of electron paramagnetic resonance in fracture mechanics
Authors: Devries K. L. 
Published: June 2010

AbstractElectron spin resonance (ESR) provides a sensitive tool by which microscopic bond rupture can be monitored simultaneous with measurements of macroscopic deformation and failure. The use of this tool to study fracture of semicrystalline polymers, rubber at very low temperatures, and rubber in the presence of ozone is discussed. In these cases, a large number of ruptured bonds precedes macroscopic failure. The micromacro behavior of these materials will be discussed in terms of some various stages of fracture and some recently proposed models of polymers. To reliably predict the strength of a polymer from the strength of the molecular chains, it is important to understand the distribution in effective length of these load‐carrying chains. ESR provides a means of obtaining insight into such information. Straining rubber before lowering its temperature to −100°C results in crystallization and subsequent fracture behavior very similar to that of polycrystalline polymers. Rate of molecular bond scission is successfully correlated by a Griffithtype energy balance to the strain energy release rate during ozone cracking of rubber.
Relaxations during the formation of films
Authors: Myers Raymond R. 
Published: June 2010

AbstractThe Stefan equation for the separation of parallel surfaces confining a viscous medium relates the tensile stress to the product of the separation velocity and the liquid viscosity. This equation is applied to roll coating; two constraints to its use are imposed as a result of incomplete relaxation of stresses during the process. These constraints are the inability of any liquid to flow rapidly enough under tension to avoid cavitation and the appearance of a sizeable elastic component in the polymer solutions which one usually applies to substrates.During film hardening the measurement of relaxation is performed by cyclic shearing at the low and middle range of the viscoelastic spectrum. The in‐phase and out‐of‐phase components of the complex modulus of rigidity are significant in this regard. Applied as a liquid, the coating must relax to a smooth layer without sagging and then be converted into a solid without developing destructively large residual stresses. Control over the mechanical properties during the formation of films is gained only after the molecular basis of relaxation and retardation is understood.
Time‐temperature superposition in thermorheologically complex materials
Authors: Fesko D. G. , Tschoegl N. W. 
Published: June 2010

AbstractTwo‐phase polymeric materials such as polymer blends, block copolymers, and graft copolymers, are thermorheologically complex. Mechanical response curves obtained on such materials at different temperatures cannot, in principle, be brought into superposition by a simple shift along the logarithmic time or frequency axis. The shift factors become functions of time or frequency in addition to temperature.A general treatment of time‐temperature superposition in thermorheologically complex materials is developed and a model is proposed from which, for a two‐phase material, the amount of shift can be calculated which is necessary to bring a point on a mechanical response curve obtained at a given temperature and time or frequency into superposition at another temperature. The mechanical responses of the constituent homopolymers and their temperature functions must be known.
Flow behavior of polyethylene melts containing dissolved gases
Authors: Blyler L. L. , Kwei T. K. 
Published: June 2010

AbstractThe influence of dissolved gases on the flow behavior of high and low density polyethylene melts was investigated using a capillary extrusion rheometer. Gases were introduced by decomposition of a blowing agent incorporated in the polymer. Data are presented in the form of flow curves (log shear stress vs. log apparent shear rate at the capillary wall), and the data treatment is justified by a continuum analysis which accounts for the change of specific volume of the polymer‐gas solution during transit through the capillary. The results indicate the addition of gas in the amount of 0.5% by weight to both high and low density polyethylene melts causes a viscosity reduction of approximately 20% at constant shear rate. The view is taken that the gas increases the free volume available in the system, thereby lowering viscosity. An analysis is presented which indicates that Doolittle's viscosity‐free volume equation can account for the viscosity reduction effected by the gas. The experimental observations also indicate that the flow curve discontinuity marking the onset of unstable flow of high density polyethylene is completely suppressed by the addition of gas at the 0.5%w level. This result is discussed in terms of the axial shear stress distribution in the capillary and the suppression of slip mechanisms occurring in the capillary owing to enhanced interpenetration of molecular chains across the slip interface.
Latex particle size analysis. Part III. Particle size distribution by flow ultramicroscopy
Authors: Davidson J. A. , Collins E. A. , Haller H. S. 
Published: June 2010

AbstractA single particle photometer is described which enables the rapid measurement of latex particle size and size distribution in the range of 500–3500Å. The instrument is a modification of the flow ultramicroscope described previously and employs an argon ion laser light source and a photoelectric detection system to observe scattering from single particles at 90°. The data are collected on a multichannel analyzer in terms of scattered intensity versus number of particles counted. A front collecting lens half‐angle of 2° was found to be adequate for direct use of the Lorentz‐Mie theory to compute particle diameters. The instrument is calibrated by determining from a suitable latex sample, the intensity of the first maximum in the intensity versus α relationship obtained from the Lorentz‐Mie theory. Particle diameters and distributions obtained on a series of 5 Dow Polystyrene latexes agreed well with those obtained by other methods. The results were found to be repeatable to ±4% at 90% confidence.
A model for interaction of nonpolar molecules differing in size and shape
Authors: Company Jean‐Claude , Renon Henri 
Published: June 2010

AbstractThermodynamic properties of pure nonpolar liquids, including long‐chain hydrocarbons are obtained accurately by derivation from an analytical partition function and the corresponding‐states principle. The characteristic parameters are interpreted in terms of group contributions in order to relate them to the structure of the molecule and further to provide a useful basis for a predictive theory of the properties of mixtures. The model for interactions between molecules takes into account the influence of molecular shape on the number of nearest neighbors and the limited number of interacting groups in a binary intermolecular contact. One obtains energy and size characteristic group interaction parameters related to those derived from London's formula and a unique function of the number of carbon atoms to characterize the shape of the molecules. Using these results obtained from pure liquids, one can predict at the same time excess enthalpies and Gibbs free energies of mixtures.
Calorimetric studies of polycarboxylic acids in aqueous solution. II. Maleic acid–butyl vinyl ether copolymer
Authors: Crescenzi V. , Quadrifoglio F. , Delben F. 
Published: June 2010

AbstractA calorimetric investigation of the heat of dissociation of a maleic acid‐butyl vinyl ether copolymer sample in aqueous solution has been carried out. Measurements were performed using dilute copolymer solutions (ca. 10−2 equiv/liter) in water, 0.04M NaCl, and 0.20M NaCl, respectively, at 25°C. Heat of dissociation data for the copolymer in water at 45°C are also reported. The calorimetric data allow evaluation in each case, (except for the solutions in 0.2M NaCl) of the enthalpy for the conformational transition which the maleic acid‐copolymer undergoes upon ionization. With the aid of potentiometric data the associated entropy changes are finally estimated. Our data point out the notable influences of temperature and of added simple salts on the energetics of the conformational transition.
Quenching of poly(vinyl phenyl ketone) photolysis by energy transfer in solution
Authors: Hrdlovič P. , Lukáč I. , Paška I. 
Published: June 2010

AbstractThe Stern‐Volmer constant of 40 quenchers was determined at 366 nm for poly(vinyl phenyl ketone) photolysis in benzene and dioxane solution at room temperature. Aromatic hydrocarbons, dienes and olefins were used as quenchers. A procedure for quantitative separation of the screening effect of quenchers absorbing at irradiation wavelength was elaborated. The correctness of this procedure was checked using 2‐hydroxy‐5‐methyl benzophenone over the concentration range 0‐10−3 mole/1. The values of the Stern‐Volmer constants lay within the range 0‐250 1./mole, expressing changes of the rate constant of quenching. Stern‐Volmer constants were found to be constant for naphthalene, its alkyl, halogen derivatives and esters at about 70 1./mole, that of 1‐naphtyl amine 1‐ and 2‐naphtol being, however, substantially higher. Electron‐deficient olefins were equally effective as dienes. There has not so far been found a parameter to characterize unambiguously the quenching efficiency of the compounds investigated.
Torsional braid analysis of lignin derived rubber stabilizers
Authors: Braddon D. V. , Falkehag S. I. 
Published: June 2010

AbstractSeveral materials derived from kraft lignin have been shown to exhibit distinct antioxidant activity for the stabilization of raw rubber against heat accelerated degradation. Selected lignin derivatives alone or in combination with amine or sulfide antioxidants were effective stabilizers for an oil‐extended styrene‐butadiene rubber (SBR). Synergism with a phosphite has been demonstrated with unextended SBR.Candidate stabilizers were screened using the relatively rapid torsional braid analyzer (TBA) technique. Pertinent samples were then tested with the conventional, but slower, technique of measuring Mooney viscosity. Mooney and TBA tests correlated for lignin derivatives, but the TBA predictions were low for typical commercial stabilizers such as phenyl‐beta‐naphthylamine (PBNA). Apparently the more volatile stabilizers, such as PBNA, escape during the aging process from the thin rubber sample employed in TBA testing. This observation limits the utility of the TBA technique to samples of similar and preferably low volatility.Lignin derived stabilizers are unique in that they are non‐discoloring, nonstaining, and relatively low in volatility and cost.
Antioxidants and stabilizers. XLV. Oxidation of halogenated dihydric phenols with oxygen and its comparison with antioxidative activity
Authors: Lerchová J. , Pospíšil J. 
Published: June 2010

AbstractSelected alkylated and halogenated derivatives of pyrocatechol and hydroquinone were oxidized with oxygen at 150°C in trichlorobenzene. The results allow an evaluation of participation of the direct oxidation of the antioxidant in the overall mechanism of its deactivation during the stabilization of polyolefins. Further data were obtained by oxidation performed in an alkaline medium. Specific relationships between the direct oxidation of halogenated dihydric phenols and their antioxidative activity in polypropylene and low‐molecular weight hydrocarbons are discussed.
Transport properties of nitrile polymers
Authors: Salame Morris 
Published: June 2010

AbstractThe transport properties of gases and vapors in high barrier polymers and copolymers containing nitrile functionalities are discussed. The permeation behavior of oxygen, nitrogen, carbon dioxide, and water vapor are given in detail. Polymers containing methacrylonitrile as well as acrylonitrile units are included: magnified imageRelationships of structure to permeability are given, in the light of known parameters for other polymers. A discussion of the Permachor values of nitrile polymers is presented, and methods of predicting permeation are given. Some anomalous behavior of transport under certain conditions are also presented.
Polyhydantions from glutamic acid
Authors: Santi E. , Babé S. G. , Fontán J. 
Published: June 2010

AbstractPolyhydantoins have been prepared by a polyaddition cyclocondensation reaction of glutamic acid with aromatic diisocyanates in apolar medium (diphenyl ether).The reaction takes place in two steps: in the first with the formation of polyamide‐ureas and thermal cyclation of them in a second step. These polyhydantoins are soluble in polar solvents and show good thermal stability.
Anionic polymerization of caprolactam. XLVI. Ketone forming units in anionic caprolactam and α‐methylcaprolactam polymers
Authors: Stehlíček J. , Čefelín P. , Šebenda J. 
Published: June 2010

AbstractN, 2‐Disubstituted and N, 2, 2‐trisubstituted amides of 3‐oxocarboxylic acids represent the model moieties incorporated in the anionic polymers of lactams and α‐substituted lactams as a result of side reactions of the catalyst components. Aminoketones traced in polymers prepared by means of 3‐oxoamides as activators indicate the prefered mechanism of regeneration of the growths centers during polymerization. The presence of ketone units in anionic α‐methyl‐ε‐caprolactam polymers indicates condensation at the α‐carbon atom similarly as in the case of nonsubstituted caprolactam polymers.
Effect of temperature on the solid‐state polymerization of N‐tert‐alkylacrylamides
Authors: Zurakowska‐Orszagh J. , Zaleski B. , Gumulka A. , Busz W. 
Published: June 2010

AbstractFollowing our former investigations on the radiation‐induced solid state polymerization of N‐substituted alkylacrylamides, we studied the effect of the temperature during irradiation for several selected monomers of this series namely: N‐tert‐butylacrylamide, N‐tertamylacrylamide, N‐tert‐hexylacrylamide, and N‐tert‐heptylacrylamide. Irradiations were carried out to high doses of conversion at temperatures varying in the range from 300°K up to temperatures near the melting point of particular monomers. The physicochemical properties of polymers obtained were presented as a function of the temperature and time of irradiation. The results show the effect of two competetive reactions; chain propagation in the solid state and interaction of radiation with the polymer formed. Both reactions occur at a different rate depending on the temperature and the corresponding mobility of the molecules in the solid state. Some interesting relations have been observed.
New hydrophilic materials for chromatography: Glycol methacrylates
Authors: Čoupek J. , Křiváková M. , Pokorný S. 
Published: June 2010

AbstractHomogeneous and hetrogeneous crosslinked copolymers of 2‐hydroxyethyl methacrylate and ethylene dimethacrylate were prepared by a suspension copolymerization in oil and water dispersion medium, respectively. The copolymers obtained were tested for their hydrolytic and thermal stability and found to be good gel chromatography packings with a broad range of applications.
Radiation induced grafting of butadiene to chlorinated polyethylene and poly (vinyl chloride)
Authors: Block Ira , Silverman Joseph 
Published: June 2010

AbstractThe radiation‐induced grafting of butadiene (BD) from methanol solution to films of low density polyethylene (LDPE), chlorinated polyethylene (PECL), and poly (vinyl chloride) (PVC) was studied as a function of chlorine content, dose rate, irradiation time, and BD concentration at room temperature. It was found that the graft yield to PECL increased with increasing glass transition temperature (Tg) of the polymer until the Tg of the chlorinated polymer was equal to the reaction temperature. As the degree of chlorination was increased beyond this point, little increase in graft yield was realized. Further increase in graft yield was obtained upon dilution of the monomer with methanol. The results are explained in terms of the effect of the added chlorine and absorbed monomer on the viscosity of the monomer‐swollen amorphous polymer.
Oligomeric initiators of radical polymerization on the basis of poly(phenylene toluylene esters)
Authors: Chuchin A. E. , Rozhkov V. V. , Fromberg M. B. 
Published: June 2010

AbstractBy the oxidation of some alkylene aromatic oligomers under soft conditions we succeeded in introducing into them peroxide‐type groups containing active oxygen. Such oligomers may be used as explosion‐proof initiators of radical polymerization of vinyl monomers. In addition to initiation, similar oligomers can act as agents, modifying the properties of the polymers obtained.Oxidation in different solvents of poly (phenylene toluylene ethers) (PPTE), obtained by condensation of difterent substitutes of diphenyl ether of general formula X‐CH2 , where X = Cl, OH, OCH3, OC2H5, and Y = H or CH2 X, allows the introduction 0.2–0.5% of active oxygen into them. Stability of peroxide groups in oxidized PPTE has been estimated under various conditions. The initiating activity of oxidized PPTE in polymerization of styrene at 80° is arranged in succession depending on the nature of the X substitute: OCH3 > OC2H5 > Cl.
Infrared study on the nature of active centers in anionic polymerization
Authors: Basova R. V. , Koslova N. V. , Gantmakher A. R. 
Published: June 2010

AbstractThe active species structure in alkali metal‐initiated polymerization in different media has been investigated, living polydienes of low molecular weight being used as the main objects. An investigation of the IR spectra of living polydienes in the regions from 350 to 650 cm−1 and from 1500 cm−1 to 1700 cm−1 made it possible to find out the influence of the synthesis conditions on the metal‐carbon and carbon‐carbon double bond stretching frequencies in the active center. In alkali metal‐initiated polymerization of hydrocarbon monomers the character of the polymerization process is greatly dependent on the nature of alkali metal and the solvent. By comparison of the spectral data with the microstructure of polymers formed under the same conditions the possible structures of different types of active centers are discussed.
Polymerization and properties of optically active 2‐(para substituted‐benzenesulfo‐namido)‐3‐propiothiolactones
Authors: Fleš D. , Tomašić V. , Samsa M. , Ahmetović D. , Jerman B. , Fleš Melita 
Published: June 2010

AbstractOptically active propiothiolactones I (R = OMe, Me, H, Cl, and NO2) were prepared by debenzylation of the corresponding 2‐para‐substituted‐benzenesulfonamido‐3‐benzyl‐mercaptopropionyl chlorides in the presence of 3 moles of aluminum bromide under the conditions of Friedel‐Crafts synthesis. The para‐substituted‐benzenesulfonamido‐propio‐thiolactones were polymerized in bulk and in DMF solution in the presence of benzyl mercaptan as initiator. The rate of polymerization was determined by measuring the change of specific rotation with time. The relative reactivity, expressed in logarithmic form, was plotted against Hammett's σ funtions showing a linear relationship, with reaction constant σ = –0.36. The temperature dependence of rate constants was determined and the activation energy in the polymerization of I (R = OMe, Me, and Cl) was determined: EA = 9.9 kcal/mole for I (R = OMe); 12.3 kcal/mole for I (R = Me), and 15.2 kcal/mole for I (R = Cl).
Chemical structure of radiation‐cured polyester resins
Authors: Funke W. , Schuh H. 
Published: June 2010

AbstractThe structure of electron‐beam‐cured polyester resins has been compared with that of the same resins which have been crosslinked by peroxide as a radical source. The copolymer chains of the radiation cured system are shorter, their composition more uniform, and the chain length distribution much smaller than with the peroxide cured resins. Polyester resins crosslinked by electron beams therefore have a more homogeneous structure than peroxide‐cured resins under usual conditions.
Formation of inhibiting active products from phenolic and amino antioxidants. III. Interactions of components of oxidized inhibitors
Authors: Gömöry Ivan , Gömöryová A. 
Published: June 2010

AbstractDuring the induction period of oxidation of polymers inhibited with phenolic and amino antioxidants, inhibiting active products are formed by oxidative transformations of original inhibitors. The interactions of the components of oxidized inhibitors were investigated by the oxidation of polyethylene inhibited by binary mixtures of particular components. The mutual interactions were determined by varying the weight ratio of both components of the binary mixture and by evaluating the deviations from additive dependence of the induction period on composition of the binary mixture. The results indicate that the type of the interaction and the quantitative effect are very sensitive to the composition of the binary mixture and to the experimental conditions of the oxidation–the temperature and the summary concentration.