bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrodynamic properties of polyelectrolytes. Part II. Poly‐4‐vinylpyridine
Authors: Jordan D. O. , Mathieson A. R. , Porter M. R. 
Published: April 2003

AbstractThe hydrodynamic properties of fractionated samples of poly‐4‐vinylpyridine have been studied. The intrinsic viscosities and the Huggins' constant (k′) have been obtained. The effect of shear on the viscosity disappears at high dilution. The sedimentation constants (S0) have been measured, and the streaming birefringence has been investigated at various concentrations and shear gradients. The Peterlin theory for concentrated solutions is in good agreement with the results for the orientation angle, but is not so well in accord with the magnitude of the birefringence. The partial specific volume is low (0.685). Molecular weights have been calculated for the fractions, and it is concluded that the shape of the molecules in solution approximates to that of a stiff coil.
The stress relaxation of sulfur vulcanizates of natural rubber
Authors: Berry J. P. 
Published: April 2003

AbstractAn experimental study is reported of the stress relaxation behavior of sulfur vulcanizates of natural rubber maintained at constant extension. Of particular interest is the effect of oxygen pressure on the shape of the force–time curves, and the relaxation proceeding in absence of oxygen. The results are interpreted according to a two‐stage process: (1) oxidation at the crosslinks and (2) scission of oxidized crosslinks.
The molecular weight‐viscosity relation for polyacrylonitrile
Authors: Onyon P. F. 
Published: April 2003

AbstractA number of low‐conversion unfractionated polymers of acrylonitrile have been prepared by polymerization of the monomer alone and in solution in dimethylformamide. Number‐average molecular weights (28,000 to 1,000,000) were determined by osmometry and intrinsic viscosities measured in dimethylformamide at 25°C. The equation:

was obeyed within the limits of experimental error over the whole range. This relation is derived from one previously obtained by Cleland and Stockmayer from light‐scattering measurements on low‐conversion transfer polymer.
Molecular weights in acrylonitrile polymerization
Authors: Onyon P. F. 
Published: April 2003

AbstractThe rates of polymerization of acrylonitrile at 25°C., initiated by azobisisobutyronitrile, have been measured, together with intrinsic viscosities of the polymer formed. Ratios have been derived for kinetic constants involving transfer to monomer, transfer to dimethyl formamide, propagation, and termination. Molecular weights were obtained using the recently confirmed relation:

The results are consistent with the occurrence of radical termination by disproportionation, and an initiator efficiency of 55%.
Interaction of trifluoroacetic acid with cellulose and related compounds
Authors: Geddes A. L. 
Published: April 2003

AbstractThe reaction of cellulose, cellobiose, and their acetyl derivatives with trifluoroacetic acid has been studied by the method of infrared spectrophotometry. Changes in optical density were measured at 25°C. as a function of time. Band assignments are adequate for the present study, although some uncertainties exist, especially in the 8 to 10 μ region. Trifluoroacetic acid effects the solution of cellulose by an initial process of swelling, rupture of hydrogen bonds, and micellar dispersion of the cellulose structure. Esterification takes place, possibly by a mechanism involving the formation of an intermediate addition compound. Cellobiose reacts in a similar manner. Partially acetylated cellulose is subject to further esterification by trifluoroacetic acid under similar conditions. The results suggest a more rapid rate of esterification of primary than of secondary hydroxyls.
Young's modulus of semicrystalline polymers
Authors: Bueche F. 
Published: April 2003

AbstractThe measurement of crystallinity and Young's modulus for two widely different polyethylenes at temperatures between 30 and 140°C. are reported. A theory is presented which accounts fairly well for the observed values of the modulus. By comparing the theory with experiment it is found that the crystallite sizes in slowly cooled polyethylene vary from about 250 to 400 angstrom units depending upon the linearity of the constituent molecules. The theory is also applied to the data of Leitner for natural rubber. It is found that in this material the crystallites were about 4300 A. long. An observed discrepancy between theory and experiment indicates that the amorphous regions between the crystallites are somewhat ordered.
Vinyl polymerization. XVI. Effect of dimethylaniline on rate of polymerization of vinyl monomers initiated by 2,2′‐azobisisobutyronitrile
Authors: Imoto Minoru , Otsu Takayuki , Ota Tadatoshi , Takatsugi Hiroshi , Matsuda Minoru 
Published: April 2003

AbstractA study has been made of the effect of dimethylaniline on the polymerization of styrene, methyl methacrylate, butyl acrylate, vinyl chloride, and acrylonitrile initiated by 2,2′‐azobisisobutyronitrile at 50°C. It was found that the rate of polymerization decreased with addition of dimethylaniline, but the rate of decomposition of 2,2′‐azobisisobutyronitrile remained constant. The chain transfer constants for the polymerization of these monomers were determined according to Mayo's equation. It was observed that the values of the chain transfer constant for dimethylaniline were proportional to those of the retardation by the latter. From these results, it is assumed that the decrease in rate of polymerization by addition of dimethylaniline is due to the chain transfer reaction.
Molecular weight distribution of a vinylidene cyanide/vinyl acetate copolymer
Authors: Yanko John A. 
Published: April 2003

AbstractA copolymer of VCVA (vinylidene cyanide/vinyl acetate) was fractionated into twenty‐five fractions ranging in Mn values from 7,000 to 535,000. The differential weight molecular weight distribution curve for this copolymer exhibited two maxima, one occurring at a Mn value of 100,000 and the other at 340,000. The original copolymer had a Mn value of 89,000 and after extraction with acetone the Mn value was increased to 137,000. Molecular weights varying from 7,000 to 24,000 were determined for the acetone‐soluble fractions. At 25.00°C. the relationship between intrinsic viscosity measurements in DMF and molecular weight is given by the equation [η]0 = 1.536 × 10−4 M0.78. Using the equations of Huggins, a μ1 value of 0.373 ± 0.019 and a k′ value of 0.373 ± 0.025 were determined for the VCVA fractions solubilized in DMF at 25.00°C. The μ1 values decreased slightly with decreasing molecular weight, indicating a small change in chemical structure or composition of the VCVA molecules as a function of decreasing molecular weight. Approximately 23% of the original VCVA copolymer was in the molecular weight range of 84,600 to below 7,000 and here with decreasing molecular weight the VA component (per mole of VC) present in the copolymer increased from 1.075 to 2.32 moles. Using the Flory equation, root mean square end‐to‐end values of the VCVA fractions in DMF at 25.00°C. were calculated. Assuming the absence of branching or crosslinking, the degree of coiling of the VCVA chain appeared to increase as the molecular weight increased. The cohesive energy density of the VCVA copolymer was calculated to be 122.8 cal./cc.
Copolymers of allyl alcohol and acrylonitrile produced by dye‐sensitized photopolymerization
Authors: Oster Gerald , Mizutani Yoshimasa 
Published: April 2003

AbstractRelatively high molecular weight copolymers of acrylonitrile and allyl alcohol have been produced using dye‐sensitized photopolymerization. The chemical constituent of the copolymers was determined by nitrogen analysis and by infrared spectrum. The calculated reactivity ratios of copolymerization were r1 = 3.96 and r2 = 0.11. The copolymers obtained beyond 0.70–0.75 mole fraction of allyl alcohol are soluble in acetone.
Ozonolytic degradation of interpolymers of natural rubber with methyl methacrylate and styrene
Authors: Barnard D. 
Published: April 2003

AbstractA simple ozonolytic method has been developed which enables the natural rubber trunk chains of rubber‐polymethyl methacrylate and rubber‐polystyrene interpolymers to be degraded into low molecular weight fragments from which the liberated polymer may be easily separated for characterization purposes. A dialkyl sulfide is used as a protective agent to prevent the attack of ozone on the polymer and the marked drop in molecular weight which would otherwise result.
Sound velocity, young's modulus and transition temperature in polythenes with different degrees of crystallinity
Authors: Baccaredda M. , Butta E. 
Published: April 2003

AbstractMechanical dynamic properties of some polythenes with different degrees of crystalinity have been measured over a temperature range from −70°C. to above room temperature, at frequencies in the range 5–30 kcps. At room temperature Young's modulus and resonance coefficient increase with increasing crystallinity. A transition temperature, independent of the degree of crystallinity, at about −24°C. is found in partially amorphous polythenes. The transition region is sharper for more amorphous samples. The modulus increases with increasing degree of crystallinity at temperatures above the transition point but appears to decrease somewhat with increasing degree of crystallinity below the transition point.
Copolymerization of methyl trans‐β‐benzoylacrylate with butadiene
Authors: Marvel C. S. , Farrar Ralph C. 
Published: April 2003

AbstractA further study of the copolymerization of methyl trans‐β‐benzoylacrylate has been made. The copolymer prepared in a neutral recipe at 66% conversion contains 15.4% of combined ester from a charging stock which contains 20% of ester. The copolymer has some increased resistance over GR‐S to special solvents but in general is an inferior rubber.
Polyvinyl trifluoroacetate
Authors: Haas Howard C. , Emerson Eugene S. , Schuler Norman W. 
Published: April 2003

AbstractVinyl trifluoroacetate and its homopolymer have been investigated. In copolymerization, the monomer behaves normally, having a Q similar to that of vinyl acetate and a positive e value resulting from fluorine substitution. Unlike the vinyl acetate system, polyvinyl trifluoroacetate is insoluble in its monomer and polymerization leads to no increase in DP with conversion. It is suspected that substitution of CH3 by CF3 has greatly reduced chain transfer and branching. Infrared spectra of vinyl trifluoroacetate and its polymer are presented and solubilities of the latter reported. Polyvinyl trifluoroacetate is very unstable to the hydrolytic loss of the perfluoro acid. The fluoropolymer is much harder than polyvinyl acetate and higher values are obtained for its softening point and apparent second‐order transition temperature. Although no difference can be found by infrared measurements between authentic polyvinyl alcohol and that obtained by hydrolysis of the fluoropolymer, a large difference in their water solubilities exists. Polyvinyl trifluoroacetate is readily oriented by stretching and some polarized infrared absorption data are presented. X‐ray diffraction photographs of stretched specimens indicate moderate order and considerable orientation. These results are surprising when considered in the light of the general concepts regarding polymer structure and crystallinity. Extremely highly ordered and highly birefringent polyvinyl alcohol can be obtained readily from stretched polyvinyl trifluoroacetate by conversion of the latter with gaseous ammonia.
Pectic substances–water. I. Structural changes in the polygalacturonide chains during water adsorption
Authors: Bettelheim Frederick A. , Sterling Clarence , Volman David H. 
Published: April 2003

AbstractAn apparatus suitable for studying adsorption of water vapor both volumetrically and gravimetrically is described. Water vapor isotherms of highly esterified pectin, sodium pectate and pectic acid were determined. Equatorial and meridional spacings of the x‐ray diffraction patterns were measured as a function of equilibrium water content in these materials. The interchain separations, as measured by the changes in the equatorial spacings of x‐ray reflections, follow the shape of the adsorption isotherms. In esterified pectin and sodium pectate, the fiber repeat period increases until 5 molecules of water content per 3 galacturonide residues are adsorbed, thereafter remaining constant. The fiber period of pectic acid is constant throughout water adsorption.
Pyrolysis of crosslinked styrene polymers
Authors: Winslow F. H. , Matreyek W. 
Published: April 2003

AbstractThe effect of network density on pyrolysis of polymers and copolymers of styrene, divinylbenzene, and trivinylbenzene was studied over a wide range of temperature. Thermal stability of polymers and size of carbon residues increased with crosslink concentration as volatilization rates declined. Rate of gas evolution was dependent on particle size, but was unaffected by catalyst content and moderate pressure changes. The results indicate extensive alteration of monomer units, possibly by a hydrogen transfer process which favors carbon formation rather than vaporization.
Copolymerization of styrene and acrylonitrile in aqueous dispersion
Authors: Mino G. 
Published: April 2003

AbstractThe bead copolymerization of styrene‐acrylonitrile, in the presence of 1‐azobis‐1‐phenylethane, was investigated at high temperature (90–100°C.). The initial distribution of acrylonitrile between styrene and the aqueous phase was determined and the change of this distribution during the copolymerization. The concentration of acrylonitrile in the aqueous phase remains fairly constant up to 20–25% conversion, then it decreases rapidly up to about 90% conversion. The over‐all rate of copolymerization following an induction period, remains constant up to about 30–35% conversion, then it increases slightly only to decrease rapidly at about 90% conversion. In a system of this type the mole fraction of acrylonitrile in the oil phase increases through the polymerization, partly because acrylonitrile reacts at a lower relative rate, partly because the acrylonitrile dissolved in the aqueous phase diffuses continuously into the beads. The reactivities of styrene and acrylonitrile in aqueous dispersion are the same as in bulk if the partition of acrylonitrile between the two phases is taken into account. The initial rates of copolymerization, in bulk, increase with the acrylonitrile content of the mixture. At high conversion, a marked acceleration in rates takes place. This autoacceleration is due to the increased viscosity of the medium and to the variation of the comonomer composition with conversion.
Crystallite regularity and void content in cellulose fibers as shown by small‐angle x‐ray scattering
Authors: Statton W. O. 
Published: April 2003

AbstractLong spacing order in the fiber axis direction is found for the majority of viscose rayon yarns, varying in repeat spacing from about 170 to 220 A. This order is interpreted as a regularity of crystallite placement such that the crystallites themselves act as diffracting centers to form a line lattice with long spacings. The diffraction found for different rayons varies in intensity and perfection as well as repeat spacing. This new structural feature can be related to the periodic length determined by the limiting degree of polymerization after hydrolysis. Current interpretations in the literature regarding the diffuse scattering at small angles are extended to include scattering due to micro‐voids or regions of low electron density. Since it is known that the materials are so dense that interparticle interference arises for the particle scattering, the reciprocity rule dictates that the voids are the source of the major amount of the scattering, not the crystallites. This interpretation is in agreement with the concepts of polymer structure from other techniques and can be used to explain the changes in scattering with swelling or the very small changes with crystallization. The micro‐voids are elongated in the fiber axes direction. For a dry cellulose fiber a distribution of sizes of the axes of the ellipsoidal voids can be obtained for relative comparisons.
Factors influencing removal of pentosan from birch wood: Evidence on the lignin‐carbohydrate bond
Authors: Nelson Russell , Schuerch Conrad 
Published: April 2003

AbstractThe effect of particle size, alkali concentration, and temperature on the rate of extraction of pentosans and on the amount of pentosans extractable from birch wood meal has been studied. In general, a very rapid extraction of accessible pentosans is followed by a slow, almost negligible, diffusion of inaccessible pentosans. There is, therefore, almost a limiting amount of pentosans not extractable under each given set of conditions. The effect of decreasing particle size is to increase the amount of pentosan extractable under any given set of conditions. The optimum sodium hydroxide concentrations at 0, 20, 40, 60 and 80 degrees are about 2, 4, 7, 10 and 12%, and under the last of these conditions at least 80% of the pentosans can be extracted rapidly from the wood meal. Pentosan is made more accessible by increasing the alkali concentration up to these levels, but thereafter the amount of accessible pentosan is decreased by an increase in alkali concentration. The decrease in extractability has the same concentration and temperature dependence as the increase in cellulose swelling under the same conditions. Therefore, pentosan removal is inhibited by excessive swelling restricted within the rigid lignin and fiber structure. Similar but less marked inhibition by swelling occurs even after lignin removal.Even under conditions of low alkali concentration, when no inhibition of solution by restricted swelling occurs, neither the temperature nor alkali dependence of rate is typical of a chemical process. The factors which inhibit the removal of pentosan are therefore physical and the inhibition of solution of pentosan from birch wood gives no support to the concept of a lignin‐carbohydrate bond.
A recording apparatus for measuring the dynamic mechanical properties of polymers
Authors: Kline Donald E. 
Published: April 2003

AbstractAn apparatus for measuring the dynamic mechanical properties of polymers is described. Rodlike specimens are driven through a transverse resonant mode by changing the driving frequency. The specimen response is obtained and automatically plotted by a recorder. Resonant frequency and width of the resonance curve constitute a measure of the dynamic mechanical properties. The temperature range of the apparatus is 4°K. to more than 600°K., and the frequency range is at least 50 to 5000 cps. Damping values have been measured from 10−4 to 5 × 10−1.
Light scattering and viscosity studies on poly‐4‐vinylpyridine
Authors: Boyes Allan G. , Strauss Ulrich P. 
Published: April 2003

AbstractSeven fractionated and three unfractionated samples of poly‐4‐vinylpyridine, ranging in molecular weight from about 7 × 104 to 2 × 106, were investigated by light scattering and viscosity studies at 25°C. Intrinsic viscosity‐molecular weight relationships in 86:14 butanone‐isopropanol and in 92.01 weight per cent ethanol were [η] = 3.80 × 10−4 M0.57 and [η] = 1.20 × 10−4 M0.73, respectively. Flory's constant K, defined by the relation [η]θ = KM0.5, was determined by two independent methods to be 8.1 × 10−4. The close agreement of this value with that obtained for polystyrene confirms Flory's hypothesis that the unperturbed molecular dimensions are controlled by steric effects. The relationship between molecular dimensions and second virial coefficient is in fair agreement with recently proposed theoretical relations. The negative temperature coefficient of the solubility of poly‐4‐vinylpyridine in tert‐butanol‐benzene mixtures indicates strong solvation through hydrogen bonding between pyridine and hydroxyl groups.
Light scattering and viscosity study of electron‐irradiated polystyrene and polymethacrylates
Authors: Shultz Allan R. , Roth Paul I. , Rathmann George B. 
Published: April 2003

AbstractThe solution viscosity behavior of polymers previously irradiated by high‐energy sources is treated theoretically by a combination of existing random crosslinking and degradation theory and branched‐polymer solution viscosity theory. The derived relations are applied to data on polystyrene, polymethyl methacrylate and poly‐tert‐butyl methacrylate irradiated as films in air with 1000 kvp. electrons. Polystyrene films underwent gelation exhibiting an energy dissipation per crosslinked unit Ec = 855 electron volts and a main‐chain scission to crosslinked unit ratio α/β = 0.35. Pregelation light‐scattering molecular weights of the irradiated polystyrene predicted an incident gelation dose (9.4 megareps) in good agreement with that (10.3 megareps) observed by gel measurements. Theory satisfactorily reproduced the solution viscosity data over a wide range of pregelation radiation doses. A combination of light‐scattering and intrinsic viscosity data proved conclusively that no appreciable crosslinking occurs during the degradation of polymethyl methacrylate under 1000 kvp. electrons. The apparent energy dissipation per main‐chain scission, Ed = 58–62 e.v., determined by viscometry is therefore the true Ed in this instance. Reactions leading to crosslinking in polyacrylates are either blocked or diverted by the methyl group on the polymethacrylate backbone. Poly‐tert‐butyl methacrylate degrades under electron bombardment with an Ed = 43 e.v.
Sorption of water vapor by water‐soluble polymers: Kinetic, equilibrium, and glass temperature data
Authors: Hughes L. J. Thompson , Fordyce D. B. 
Published: April 2003

AbstractEquilibrium and kinetic studies of the sorption and desorption of water vapor by poly(acrylic acid), poly(sodium acrylate), sodium carboxy methyl cellulose, methyl cellulose, and a series of poly(methyl acrylate) hydrolyzates in acid and sodium salt forms were made at 30°C. It was found, as expected, that equilibrium sorption increased and was greater for polymers containing strong‐electrolyte type substituents than for those containing an equivalent number of weakly ionizable units. In general, the diffusion is somewhat slower than in the case of water‐insoluble polymers. It was also found that water solubility of a polymer does not per se result in anomalous water sorption. In Methocel, for example, water diffusion is both Fickian and concentration‐independent. All of the results, particularly those on the poly(methyl acrylate) hydrolyzates which ranged from completely water‐soluble to insoluble systems, support the following conclusion: For water‐soluble polymers both anomalous diffusion and relatively high glass temperatures are associated with high concentrations along polymer chains of very polar or ionic groups, such as OH, COOH, and CO2−Na+. Presumably both the anomalies and high transition temperatures are associated with restricted segmental mobility resulting from strong chain‐chain interactions which originate in the highly polar and ionic, water‐solubilizing chain substituents.
Dilute solution studies on polystyrene by light scattering and viscosity
Authors: Chinai S. N. , Scherer P. C. , Bondurant C. W. , Levi D. W. 
Published: April 2003

AbstractPolystyrene was fractionated and refractionated to obtain essentially homogeneous fractions. The constants K and a in the conventional equation [η] = KMa were determined. The intrinsic viscosity in an ideal solvent fitted the relation [η]θ = KM1/2 over the molecular weight range 0.04 × 106 to 1.46 × 106. The degree of flexibility of polystyrene chains in solution is compared with those of polymethyl and polyethyl methacrylates.