bluuebunny/crossref_metadata_2025 huggingface dataset:
Infrared spectrum and crystal structure of cellulose
Authors: Tsuboi Masamichi
Published: April 2003

Infrared absorption spectra of oriented cellulose fibers have been observed using polarized radiation. Natural fibers are in general too thick but swelling them in NaOH solution followed by pressing, washing, and drying is an effective way of obtaining a suitable thickness in the 650–3100 cm.−1 region. The dichroism observed for the bands which can be assigned has been interpreted on the basis of the crystal structure of cellulose. The CH stretching band is polarized perpendicular to the fiber axis, in accord with the previously proposed model of the crystal structure (Meyer and Misch). Because both the CH2 symmetric and antisymmetric stretching bands are polarized parallel, a modification of the previously proposed model is necessary. In the region of CH and OH deformation frequencies (1200–1500 cm.−1) nine bands are observed, of which four are polarized parallel and five, perpendicular, to the fiber axis. Deuteration effect of amorphous cellulose on the spectrum in this region was examined. Probable assignments are given for these bands. In the region of CO and CC stretching frequencies (800–1200 cm.−1) all the bands are polarized parallel to the fiber axis. Observations were also made on deuterated cellulose, i.e., cellulose which had been swelled in NaOD. Of the six OD stretching bands observed, five show parallel dichroism, indicating that the OH bands in cellulose are arranged predominantly parallel to the fiber axis. The OH out‐of‐plane deformation band at 650 cm.−1 is polarized perpendicular to the fiber axis.
p‐Vinylbenzyltrialkyl ammonium salts in vinyl polymerization
Authors: Jones Giffin D. , Goetz Shirley J.
Published: April 2003

Polymers and copolymers of a quaternary monomer, vinylbenzyltrimethylammonium chloride, have been studied. A product similar to that previously obtained by partially chloromethylating polystyrene and aminating with trimethylamine has been made. The product with 15 to 25 mole per cent quaternary groups forms metastable aqueous solutions. Light scattering measurements in the presence of added salt do not indicate aggregation. The quaternary monomer exhibits micellar behavior in conductivity measurements. Copolymers with acrylamide are water‐soluble and substantive to paper pulp; copolymers in minor amount with acrylonitrile are dyeable with acid dyes; copolymers in minor amounts with styrene are clear and free of tendency to pick‐up or maintain a static charge.
Improved rotation viscometer for the study of low viscosity liquids at low and intermediate rates of shear
Authors: Frei E. H. , Treves D. , Eisenberg H.
Published: April 2003

An improved model of a precision rotation viscometer with electrostatic restoring torque for the centipoise range is described. In this instrument torques from 0.1 to 500 dyne cm. are measured with an accuracy of 0.2%. Rates of shear range from 0.1 to 200 sec.−1.
Dependence of mechanical shear degradation of polymers in solution on rate of energy application and on concentration
Authors: Goodman Philip
Published: April 2003

The kinetics of the degradation of polyisobutene in cetane solutions produced by mechanical shearing action in a capillary has been studied as a function of rate of shear energy application and of concentration. The initial rate constant, k, for the degradation was determined as the initial rate of bond cleavage per unit concentration by weight. Log k was found to be a linear function of the reciprocal of the rate of shear energy application per unit volume, J. At all concentrations studied in the range 5–20 weight per cent, log k was the same function of 1/J, but such a plot for 3% solutions had a much greater negative slope. This indicates a decreased efficiency for the concentration of mechanical energy by the polymer molecules in less concentrated solutions.
Polymers and copolymers of N‐1,1‐dihydroperfluoroalkyl acrylamides
Authors: Knobloch Fred W.
Published: April 2003

A series of six new fluorinated acrylamide monomers has been studied. These included the N‐1,1‐dihydrotrifluoroethyl acrylamide, the N‐1,1‐dihydroheptafluorobutyl acrylamide and the N‐methyl, ‐ethyl, ‐n‐butyl and ‐isobutyl derivatives of the latter. Homopolymerization of the fluoroacrylamide monomers with benzoyl peroxide readily proceeded both in bulk and solution. Both liquid and crystalline fluorinated acrylamide monomers polymerized in emulsion with persulfate initiators. All homopolymers were thermoplastics which could be cast to yield clear transparent films. Specific evaluation was made of the electrical properties of polymeric N‐n‐butyl‐N‐1,1‐dihydroperfluorobutyl acrylamide before and after exposure to gamma radiation. A time—conversion polymerization curve was determined for the N‐ethyl‐N‐1,1‐dihydroperfluorobutyl acrylamide. The rapid polymerization found for this monomer characterizes the behavior of all the fluorinated acrylamide monomers. Copolymerization proceeded with a number of comonomers which included alkyl acrylates, fluoroalkyl acrylates, vinyl ethers, and several dienes. Reactivity ratios were evaluated for the copolymerization of N‐ethyl‐N‐1,1‐dihydroperfluorobutyl acrylamide (N‐EFBAm) with methyl methacrylate (MMA). Values determined were r1 = 0.89 (N‐EFBAm) and r2 = 0.77 (MMA).

The fractionations of two copolymers are discussed in relation to compositional and structural variations present in the copolymers. Indication that these copolymers were essentially linear was provided by a determination of the Huggins empirical slope constants.
Conductivity of solutions of the potassium salts of carboxymethylcellulose and sulfonated polystyrene in the presence of potassium chloride
Authors: Longworth R. , Hermans J. J.
Published: April 2003

The conductivity of the potassium salts of carboxymethylcellulose (CMC) and poly‐p‐styrene sulfonate (PSS) in the presence of KCl shows a behavior which is in striking contrast to the results of a previously developed theory: when the total concentration of K plus Cl ions is kept constant, the conductivity decreases with increasing polymer content in the majority of cases. Qualitatively this can be explained by a theory of the relaxation effect. This theory makes use of the model of a porous sphere in which the counter ions completely compensate the charge of the fixed ions. The use of the Debye‐Hückel approximation is avoided. The charge resulting from relaxation effects is treated as a surface charge.
Propagation of stress waves in rubber rods
Authors: Cramer William S.
Published: April 2003

The propagation of longitudinal, torsional, and flexural waves in rubber rods was studied by a moving probe method. Conditions and materials were used for which the attenuation was sufficient to eliminate standing waves. Velocity and attenuation data were obtained for the different wave types over the frequency range 1 to 8 kc. at or near room temperature for different rubbers of accurately specified compositions. Complex Young's moduli were computed from both the longitudinal and flexural propagation data and found to be in good agreement with each other for the same rods under the same conditions. Complex shear moduli were computed from the torsional data. Ratios of the respective real parts and loss tangents of the Young's and shear moduli showed good agreement with theory but some dependence on material. Measurements were also made of the complex bulk moduli of materials identical to those studied in rod form.
Kinetics of polymerization of nitroethylene. II. Study of molecular weights (by cryoscopic method)
Authors: Vofsi D. , Katchalsky A.
Published: April 2003

The study of the polymerization of nitroethylene in methyl ethyl ketone and catalyzed by bases of the pyridine series—as reported in part I—was extended in the present work. The MW of a number of polymers was determined by a semimicro cryoscopic method, which is described in detail. Of all the reaction parameters, at 20°C., the MW was found to depend only on the initial monomer concentration. To account for this dependence, an additional step was included in the three‐step mechanism suggested earlier, namely, that of catalyst transfer to monomer. Spectroscopic examination of the polymers support the suggestion that termination, or transfer, is accompanied by ring closure and the formation of cyclic structures.
Diffusion in ethylene polymers. II. Desorption of water
Authors: McCall D. W. , Ambrose J. F. , Lanza V. L.
Published: April 2003

The kinetics of desorption for water from various ethylene polymers have been studied by weight loss. In either branched (DYNK) or linear (Marlex 50) polymers the solubility of water was too low to be measured by our techniques (< 0.05 mg. H2O/g. polymer). This result is not in agreement with values reported by earlier workers (0.2–0.9 mg. H2O/g. polymer). When DYNK is oxidized, however, measurable quantities are absorbed. We find 0.11 mg. H2O/g. polymer for DYNK containing about 0.6% oxygen by weight. In this case the desorption data provide a measure of the diffusion coefficient, D ≃ 10−7 cm.2/sec. Similar results are found for a cable compound containing about 5% butyl rubber and 0.07% antioxidant introduced into DYNK by milling.
Molecular motion in polyethylene
Authors: McCall D. W. , Slichter W. P.
Published: April 2003

Molecular motion has been studied in a highly branched polyethylene, DYNK, and in a linear polyethylene, Marlex 50. The studies centered around the use of nuclear magnetic resonance spectroscopy, with additional information from measurements of x‐ray diffraction, dielectric relaxation, and the diffusion of small molecules into the polymers. The nuclear resonance studies extended over a temperature range of 80 to 410°K., and studies by the other techniques included some measurements at low and high temperatures. It is shown that crystallinity in the linear polyethylene persists to within only a few degrees of the “melting point” of the gross polymer, and that chain rotation within the crystallites is comparatively restricted until shortly below the temperature of fusion. On the other hand, chain rotation within the crystallites of the branched polyethylene is much freer, presumably due to the presence of lattice defects, such as might be caused by the incorporation of branch points into the crystallites. Crystallinity in the branched polyethylene disappears at much lower temperatures than in the linear polymer. There is considerable motion of chain segments within the amorphous regions of both kinds of polyethylene, although at a given temperature the linear polymer exhibits more constraint than does the branched polymer. It is evident that the amorphous portions of both polymers possess the attributes of a viscous liquid, even at temperatures well below the melting point of the gross material. Activation energies and frequency factors for the motions of chain segments in the amorphous portions have been computed and are compared with the data from earlier measurements of dielectric and mechanical relaxation.
A photoelectric instrument for the measurement of molecular orientation in films of high polymers
Authors: Winogradoff N. N. , Bisset D. C.
Published: April 2003

A simple, continuously recording instrument capable of measuring retardations down to the order of 10−8 cm. is described. The instrument is based on photoelectric measurement of the intensity of light transmitted by two crossed rotating Polaroids when an oriented film of high polymer exhibiting optical anisotropy is placed between them. This intensity is related to the birefringences of the sample for light vibrating in three mutually perpendicular directions. These three birefringences can be used to specify physical properties and have been used to study the effect of sorption, desorption, annealing, and stretching processes on molecular configuration. Some examples of such applications are discussed.
Effect of gamma‐radiation on cellulose
Authors: Glegg R. E. , Kertesz Z. I.
Published: April 2003

Cotton and wood cellulose were irradiated with gamma rays within the dosage range 60 X 103 r to 2,300 X 103 r. A measure of the degradation was obtained from intrinsic viscosities obtained from viscosity determinations in cupriethylenediamine solution. The presence of water had no significant effect on the extent of radiation‐induced degradation. Thus there was little or no difference between the results on irradiated samples of wood cellulose containing 3.3, 4.6, and 5.6% moisture. Cotton cellulose irradiated in the presence of excess water or 3.5% moisture was equally degraded. At lower moisture levels (0.26–0.32%) an aftereffect was observed in which the solution viscosities of the irradiated samples progressively decreased up to 30 days in storage. The duration of the effect was independent of the dosage levels studied. From the experimental results reported here and from recalculations of data in the literature the radiation threshold dosage for isolated celluloses appears to be in the range of 28.4 to 81.2 X 103 r. Cellulose is degraded at gamma‐radiation dosages equal to or below those required for softening plant tissues such as apples, carrots, and beets. Therefore it seems probable that the degradation of this cell wall constituent is a major factor in the radiation‐induced softening of plant tissues.
Effect of olefin structure on the ceiling temperature for olefin polysulfone formation
Authors: Cook R. E. , Dainton F. S. , Ivin K. J.
Published: April 2003

Ceiling temperatures Tc (at which the free energy change for the reaction is zero) have been determined for the formation of polysulfones from a wide variety of olefins and allyl compounds under standard concentration conditions ([M] [S] = 27 mole2 liter−2, M = unsaturated compound, S = sulfur dioxide). In the 1‐olefin series Tc falls from ethylene to propylene 90°, to 1‐butene 64°, and then remains approximate constant as the chain is lengthened. With 2‐olefins there is a progressive decrease from butene 34°, to pentene 8°, to heptene −38°. Branching invariably lowers Tc and the effect is greatest when the branching is at the double bond; thus isobutene 4°, 3‐methyl‐1‐butene 36°, 4,4‐dimethyl‐1‐pentene 14°. 2‐ethyl substitution of a 1‐olefin, or 2, 3, or 4 branching of a 2‐olefin results in inability to react (Tc < −80°). Cycloolefins have Tc values considerably higher than the corresponding 2‐olefins; thus cyclopentene 102°, cyclohexene 24°. In the allyl compounds a carboxyl group tends to lower Tc but a hydroxyl group raises Tc. An ether group raises Tc slightly. The results are discussed in terms of structural effects on the heat and entropy changes and on the monomer activity coefficients and polymer solubilities. The infrared absorption spectra of 20 polysulfones and 3 aliphatic sulfones are recorded for the sulfone stretching region (7.5–9.5 μ).
Dynamic viscosity and shear modulus of molten polystyrene as a function of molecular weight
Authors: Cox W. P. , Nielsen L. E. , Keeney R.
Published: April 2003

The dynamic mechanical properties of several polystyrene fractions were measured in the frequency range 0.05–5 cycles per second and the temperature range 160–220°C. Data obtained at different temperatures with each fraction were superposed by means of Ferry's reduced variables. The empirical temperature shift factors involved in this superposition agreed well with values calculated from the universal function of Williams. The observed molecular weight dependence of the dynamic properties agreed qualitatively with the predictions of the Rouse theory as modified by Ferry, Landel, and Williams for application to polymer melts.
Theory of light scattering by polymer solutions
Authors: Flory P. J. , Bueche A. M.
Published: April 2003

The intermolecular contribution to light scattering by polymer solutions has been treated according to the smoothed Gaussian sphere model. Combining the results with the usual term for the individual molecule scattering we obtain for the reciprocal turbidity:

The third virial term is also formulated. The angle dependent factor Q(θ) falls appreciably below unity at higher angles for large molecules in good solvents. Calculation of Q(θ) according to the theory is illustrated. Its replacement by unity may under some circumstances invite appreciable error.
Infrared spectra of high polymers. VI. Polystyrene
Authors: Liang C. Y. , Krimm S.
Published: April 2003

The infrared spectrum of polystyrene has been obtained in the region of 70 cm.−1 to 3200 cm.−1. These data, plus Raman scattering data from the literature, are used to make a complete assignment of the normal modes of the polystyrene molecule. The benzene ring modes have been analyzed in detail in terms of C2v symmetry, and a set of normal vibrations has been proposed. On the basis of previous analyses of the benzene and monosubstituted benzenes, and a study of the combination bands, it has been possible to make a fairly satisfactory assignment of all of the benzene ring fundamentals. Assignments of the CH2, CH, and skeletal modes are made on the basis of previous studies of spectra of high polymers. The interpretation of the spectrum is in agreement with other evidence that the chain configuration is a random one, i.e., that the polymer is amorphous.
Reactions of phosphoric acid with polyvinyl acetals
Authors: Barnes Roderick A.
Published: April 2003

Two of the possible reactions between polyvinylbutyral and phosphoric acid in 95% ethanol have been investigated. Some hydrolysis of the acetal linkages has been found to take place although the extent of this reaction is less than for simple monomeric acetals. No evidence has been found to indicate that there is, in ethanol, any esterification of the phosphoric acid by the hydroxyl groups of the polymer.
A light scattering study of alfin polybutadiene
Authors: Cleland Robert L.
Published: April 2003

The weight average molecular weights, Mu, of some unfractionated Alfin polybutadienes ranged from 5 to 20 million. The ratio of the mean‐square radius of a linear polybutadiene molecule to its molecular weight in a thermodynamically neutral solvent is estimated to be R2/M = 2.2 (±0.3) × 10−17 cm.2g.−1 mole. The relationship [η] = 0.125 Mv0.77 between intrinsic viscosity and molecular weight is estimated for linear polybutadiene in cyclohexane at 25°. The average value of Φ′, the parameter in the Flory‐Fox theory of intrinsic viscosity, is found to be 3.6 × 1024 mole−1 (or Φ = 2.5 × 1023 mole−1) for linear molecules and appears to increase with branching. Branching is found to decrease with increasing conversion for this polymer. Values of the osmotic second virial coefficient, A2, are discussed in connection with theoretical predictions. Various corrections to measured quantities required because of polydispersity in polymer samples are presented.
Diffusion of allyl chloride in polyvinyl acetate. Part II. The transient state of permeation
Authors: Meares P.
Published: April 2003

The permeation rate of allyl chloride through polyvinyl acetate films has been studied as a function of time during the transient period preceding the establishment of steady states of permeation. It was found that two distinct processes could be distinguished. When the ingoing pressure of allyl chloride was changed from a value at which a steady state had been established to a new value, there was a gradual change in the permeation rate to a new steady value. Depending upon the initial and final pressures this change required from several hours to several weeks. When the initial ingoing pressure was small or zero there was a large and immediate increase in the permeation rate when the ingoing pressure was increased. This rapid rate decreased over periods which ranged from about three hours at low ingoing pressures to a few minutes for higher ones, and died away before the more gradual increase in rate had begun to take effect. Using the equations of Frisch, the time lags for transition between pairs of steady states have been calculated, from previously determined sorption and diffusion data, and compared with the observed values. The calculated values were usually smaller than the observed ones. The discrepancy was most serious at low vapor concentrations and decreased with increasing concentration. For concentrations greater than 1 × 10−3 mole cm.−3 there was a close agreement. For comparable concentrations, the discrepancy was less marked for decreasing than for increasing ingoing pressure and was also less for thin membranes than for thicker ones. These observations are consistent with the theory that the swelling of the membrane which accompanies the sorption of vapor gives rise to elastic stresses which slowly decay by viscous movements within the polymer. The initial jump in permeation rate proved more difficult to study. As far as could be determined it occurred instantaneously. When plotted against logarithmic time, S‐shaped curves were obtained very similar in appearance to elastic stress decay curves observed for polymers and predicted theoretically for a series of Maxwell units with a wide distribution of relaxation times. This suggests that the high permeability may arise from lateral strains set up when an instantaneous swelling takes place at the ingoing face of the membrane on the admission of more vapor. The instantaneous stress then decays by elastic motions of segments of polymer molecules, over a period determined by the temperature and initial sweller concentration, and so reduces the high permeation rate. For initially unswollen polyvinyl acetate at 40° the time for half‐decay of the permeation rate was agout 25 minutes for a membrane 32 μ thick. It was found that the peak permeation rate increased as successive experiments were performed with the same membrane. This suggested that permeation through a membrane clamped in a diffusion cell produced orientation parallel to the membrane surface. It has not yet been possible to confirm this.
Monolayer studies of some hydroxylated polyolefin rubbers
Authors: Dean W. R. , Perera V. , Glazer J.
Published: April 2003

When thin films of natural rubber, gutta‐percha, polybutadiene, and polybutadiene‐styrene copolymers are deposited at the surface of aqueous acidified potassium permanganate, they undergo a surface reaction and spread spontaneously. A study of the products of this reaction has been made, and their surface characteristics are described. The reaction products are polyhydroxy derivatives of the polyolefins and are shown to form stable monomolecular layers at an air‐water interface. The areas of the hydroxylated olefin residues have been determined, and their magnitude and orientation at the interface is discussed. The agreement between experimentally determined areas and theoretical areas (from established interatomic distances) is good. Results suggest that butadiene‐styrene copolymers contain an appreciable number of blocks of contiguous styrene units.
Polymerization of silicic acid in alkaline solutions a kinetics study
Authors: Greenberg S. A.
Published: April 2003

The polymerization of silicic acid in solutions buffered with ammonium acetate was followed by interferometer measurements. The results were interpreted to indicate that the rate of polymerization is first order in silicic acid concentration and inversely proportional to the concentration of hydroxyl ions.
Influence of rate of shear on the apparent viscosity of dilute polymer solutions
Authors: Takemura Tetuo
Published: April 2003

The measured viscosity of polymer solutions varies with the magnitude of the applied shearing stress. In this paper a modified Rouse model of a polymer molecule (which has some stiffness) is used, and the diffusion equation is solved with respect to the co‐ordinates system moving with the polymer molecule. Results indicate: (1) The above phenomena is a natural consequence of the fact that the molecules are caused to rotate by the shearing action. (2) This is the same mechanism with the dynamic viscosity caused by the applied periodic shearing stress.
The hydrolysis of n‐amyltriethoxysilane and phenyltriethoxysilane
Authors: Sprung M. M. , Guenther F. O.
Published: April 2003

n‐Amyltriethoxysilane and phenyltriethoxysilane were hydrolyzed in organic solvents in the presence of acidic or basic catalysts. The bulky substituents allow relatively large amounts of low‐molecular‐weight partial hydrolysis products to be isolated and stabilize the silanol functions present against further condensation. Cyclic ethoxypolysiloxanols in the molecular weight range 500–1000 are principal products of acid catalyzed hydrolysis. More extensive condensation occurs under alkaline conditions. Relatively high yields of low‐polymeric silsesquioxanes (octamers and possibly hexamers) are then obtained. The major product obtained from phenyltriethoxysilane, when hydrolyzed in a ketone solvent with a quaternary base as catalyst, is an amorphous high polymer virtually free of functional groups. In inert solvents in the presence of traces of catalyst a very facile rearrangement occurs, giving the octamer (and possibly the hexamer) in very high yield.
Sorption kinetics of water vapor in wool fibers
Authors: Downes J. G. , Mackay B. H.
Published: April 2003

Using a modification of the vibroscope technique, studies have been made of the sorption kinetics of water vapor in single wool fibers. Small changes in water content, described as interval sorption and desorption, occur in two stages, the first occupying a few minutes and the second many hours (at room temperature). This behavior is similar to that recently reported for interval sorption of organic vapors in “glassy” polymers (e.g., acetone in cellulose acetate). The first stage of sorption is considered to be due to diffusion in accordance with Fick's law; the slow increase in concentration during the second stage is thought to result from partial relaxation of the swelling stress. Large changes in water content are described as integral sorption and desorption. In integral sorption the slow second stage of sorption is not observed; the explanation is thought to be that relaxation of swelling stress, and hence the second stage, are greatly accelerated by the transient stress associated with the steep concentration gradient present during integral sorption. The slow second stage is present in integral desorption, the probable reason being that in this case there is no steep concentration gradient. Integral sorption to a given value of relative humidity (R.H.) results in a higher equilibrium water content than if the same R.H. is reached in a series of interval steps. This effect is thought to be related to the hysteresis which is observed in the isotherm in a sorption‐desorption cycle; the transient stress present in integral sorption leaves the material in the same condition as if it had been brought down the desorption curve of the isotherm. The sorption hysteresis is thought to result from metastability of the interchain bonds which undergo relaxation in the second stage of interval sorption and desorption. All the effects observed are likely to be qualitatively characteristic of vapor sorption in any polymer at temperatures below the second‐order transition.
The determination of the stiffness of the chain of a rubber‐like polymer
Authors: Stein Richard S.
Published: April 2003

A theory for the infrared dichroism of a crosslinked, rubber‐like amorphous polymer is described. The dichroism of a typical rubber is estimated to be measurable. The dichroism‐stress ratio is independent of strain and degree of crosslinking and serves as a measure of the number of monomer units per statistical segment, an index of chain stiffness.
Effect of pile irradiation on the dynamic mechanical properties of polyethylene
Authors: Deeley C. W. , Kline D. E. , Sauer J. A. , Woodward A. E.
Published: April 2003

The effects of pile irradiation on the damping and resonant frequency of a “high pressure” polyethylene has been investigated over a temperature range from 80 to 550°K. in the audiofrequency region using an apparatus which drives rod‐like specimens in their transverse modes. Using irradiation dosages which result in approximately 4% crosslinking or greater, the mechanical loss peaks found at about 165, 265, and 355°K. in polyethylene are altered. Definite changes in the resonant frequency or modulus‐temperature plots also occur. The 355°K. peak, attributed to the melting of the crystalline portions of the sample, decreases in height and shifts to lower temperatures with increasing irradiation dose. A decrease in the height of the 265°K. peak accompained by a shift to higher temperatures takes place. The 165°K. peak initially increases in height and peak temperature but at higher dosages a marked decrease in the damping maximum occurs. The damping behavior in the 165 and 265°K. regions is discussed in terms of diffusional motion of chain segments in the amorphous polymer portions.
Melting points and heats of fusion of some polyamides and polyesters
Authors: Flory Paul J. , Bedon Helen D. , Keefer Edward H.
Published: April 2003

Melting points of three polyamides, four polyesters, and their mixtures with diluents have been determined by application of dilatometry to observe the latent volume change during gradual melting extending over many days in each case. Heats of fusion were calculated from the depressions of the melting point by varying volume fractions of diluents. The results, given in °C. and in cal./g., respectively, are as follows: decamethylene sebacamide, 216°, 24.5; decamethylene azelamide, 214°, 27; the sebacamide of 1,10‐dipiperazyldecane, 129.5°, 34.5; decamethylene azelate, 69°, 31; nonamethylene azelate, 65°, 33; decamethylene terephthalate, 138°, 36; hexamethylene terephthalate 160.5°, 34. The results are compared with those previously reported for related polymers. A possible explanation is suggested for the fact that the heats of fusion of polyesters exceed those for the corresponding polyamides. High melting points appear to be associated with low entropies of fusion rather than with high heats of fusion.
Properties of polyesters of bisphenols and dicarboxylic acids
Authors: Levine Max , Temin Samuel C.
Published: April 2003

A series of linear polyesters have been made by polymerization of dibasic acids with acetyl derivatives of p,p′‐diphenolic compounds. The diphenolic compounds were of either the dihydroxydiphenyl or the methylenebisphenol type with varying degrees of alkyl substitution. The crystallinity and first‐ and second‐order transition temperatures of the polymers are considered in terms of their chemical structures. The effects of symmetry and aromaticity are discussed.
α,β‐Unsaturated ketones. II. Copolymerization reactions of trans‐cinnamoylferrocene
Authors: Coleman L. E. , Rausch M. D.
Published: April 2003

The polymerization reactions of trans‐cinnamoylferrocene have been described and a number of copolymers have been characterized. trans‐Cinnamoylferrocene does not homopolymerize using conventional free radical techniques but forms copolymers with styrene, acrylonitrile, methyl methacrylate, ethyl acrylate, butadiene, isoprene, and 1,1‐dihydroperfluorobutyl acrylate.
Graft interpolymers formed by γ‐irradiation of methyl methacrylate‐natural rubber mixtures
Authors: Angier D. J. , Turner D. T.
Published: April 2003

On exposure to Co‐60 γ‐radiation, mixtures of natural rubber and methyl methacrylate yield almost exclusively rubber‐polymethyl methacrylate graft polymers. An appreciable amount of free polymethyl methacrylate is formed only in the presence of a transfer agent or following radiation‐induced degradation of the interpolymer. Structural characterization of the products has been made. The findings are not consistent with random grafting of the synthetic polymer on linear rubber molecules of random molecular size distribution—the rubber component appears to comprise several crosslinked molecules. The influence of the purity of the rubber, monomer concentration, field intensity, the presence of transfer agent, and the gel effect on the rate of formation, yield, and structure of the interpolymer are reported.
Sorption and diffusion in ethyl cellulose. Part IV. Water in ethyl cellulose
Authors: Barrer R. M. , Barrie J. A.
Published: April 2003

An account has been given of sorption and diffusion of water by ethyl cellulose. In contrast with diffusion coefficients of some other penetrants, those of water decrease with increase of water sorption in the manner previously observed by Rouse for water–polythene systems. The sorption isotherms have the opposite curvature to Langmuir or Freundlich isotherms, and hence also to the isotherms of benzene, C4 and C5 paraffins, or acetone sorbed at low penetrant concentration by the same polymer. The results have been interpreted in terms of cluster formation of water molecules either in preexisting cavities in the polymer or, less probably, in the polymer matrix itself. Visual evidence of cluster formation is provided by the onset of light scattering by the membrane as the relative humidity reaches a critical range. The opacity disappears again as the humidity is decreased.
Studies on the low pressure polymerization of ethylene using catalysts containing lithium alkyls
Authors: Frankel Max , Rabani Joseph , Zilkha Albert
Published: April 2003

The low and atmospheric pressure polymerizations of ethylene using catalysts prepared from n‐butyl lithium or isoamyl lithium and titanium tetrachloride were studied. The efficiency of the catalyst depended on the molecular ratio of the alkyl lithium to titanium tetrachloride. Optimum molecular ratio for the n‐butyl lithium–titanium tetrachloride was found to be between 2.15–2.47 with a sharp drop between 2.15–1.49; for the isoamyl lithium the optimum was between 2.5–4.3. Within the examined interval (of atmospheric pressure to a pressure of 60–70 lb./sq. in.) higher pressure caused an increase in the yield of polyethylene. No pronounced effect in polymerization was found in the temperature interval of −10–55°. The catalyst is stable for a few days if kept refrigerated. Petroleum ether, b.p. 40–80°, was the best solvent both for the preparation of the catalyst and for the polymerization. Ligroin, toluene, and especially ether interfered with the polymerization. The polyethylenes obtained melted between 125–135°.
A study of chain transfer in homologous vinyl esters
Authors: Buselli Alio J. , Lindemann Martin K. , Blades Charles E.
Published: April 2003

The principal complication arising out of free radical‐initiated polymerizations involving vinyl acetate has been the chain transfer to monomer and polymer which results in a highly branched polymer chain. Some evidence has also been presented to show that the degree of branching in polyvinyl esters increases with an increasing number of carbon atoms in the vinyl ester. It was of interest, therefore, to obtain a relative measure of the chain transfer constants for successive members of the homologous series of vinyl esters and to relate the constants to the actual structure of the respective polyvinyl ester. Accordingly, the study of the chain transfer in the benzoyl peroxideinitiated polymerizations of vinyl acetate in the presence of a homologous series of ethyl esters of fatty acids was made. Chain transfer constants versus number of carbon atoms in the carboxylate portion of the fatty acid ester resulted in a linear relationship which can be expressed as

where n is the number of non‐α‐methylene groups in the side chain. A concurrent study of the influence of monomer chain lengths of selected vinyl esters on molecular weight of the derived homopolymer was also carried out. The results obtained provide a basis for predicting the trends for changes in branching and degree of polymerization within the homologous series of vinyl esters.
Degradation of addition polymers by ultrasonic waves. IV. The effect of ultrasonic intensity
Authors: Mostafa M. A. K.
Published: April 2003

The effect of ultrasonic intensity on degradation parameters K and y for a polystyrene in benzene sample was investigated. The results are discussed in relation to a theory previously developed for the degradation of addition polymers by ultrasonic waves. It is shown that for a constant ultrasonic frequency the experimental results can be explained by theories which assume that degradation is caused by frictional or impact forces.
Diffusion‐controlled stress relaxation in polymers. III. Stress relaxation in a swelling polymer
Authors: Kishimoto Akira , Fujita Hiroshi
Published: April 2003

An approximate theory of the relaxation of stress in amorphous linear polymers accompanying sorption of a low molecular weight penetrant is worked out on the assumption that the relaxation time of each Maxwellian relaxation mechanism involved is changed in the presence of penetrant by a factor dependent on penetrant concentration. A method is derived from the theory which permits approximate evaluation of the integral diffusion coefficient D̄ of the penetrant in the polymer from stress‐relaxation data on swelling systems. The theory is checked on experimental data for the systems polymethyl acrylate‐water and polymethyl acrylate‐methanol at 40°C., and it is found that, for both systems studied, the values of D̄ computed from mechanical data agree reasonably with those evaluated directly from usual sorption experiments. The theory described presents only a first attempt to the quantitative interpretation of the phenomenon discussed. Further improvement and modification of it is apparently desirable, in view of some drastic approximations incorporated in its mathematical development.
Statistics of flexible macromolecules at interfaces
Authors: Simha Robert
Published: April 2003

The subject is of importance in a variety of colloidal and biological problems. It includes (a) adsorption on solid surfaces, (b) the equation of state of mono or multilayers on liquid interfaces, (c) surface tension of solutions. There are two aspects, namely the molecular configurations at the interface and the resulting contributions to the free energy. Assume the surface to be a regular array of adsorbing sites, each accommodating one chain segment. Unless the segment‐site interaction is extremely large in comparison with kT and of long range, flexible chains will not deposit completely. H. L. Frisch and the author have previously shown for random coils that the average number v of segments adsorbed out of a total of t per chain is proportional to t1/2 and increases with chain flexibility and thus temperature in a good solvent. They also established the consequences of this for (a) and (b). The present discussion, based on work in collaboration with Frisch, includes surface tension and differs from our earlier results at low surface concentration θ. As previously, the treatment neglects fluctuations in v, which are small for large t. The isotherm in dilute solutions is essentially θ/[v(1 − θ)v] = Kc, where K is a function of v, T, depending on the properties of the bulk polymer and solvent and increasing with molecular weight. Deviations from a Langmuir isotherm are less pronounced than for rigid molecules. The second virial coefficient of the pressurearea curve depends on the ratio v/t and hence on molecular weight and flexibility differently from a completely deposited molecule, flexible or rigid. The limiting change in surface tension depends on two‐opposing terms. When adsorption is sufficiently strong, a decrease proportional to K, and hence increasing with molecular weight, results. This competes with an increase proportional to v/t ∝ t−1/2, arising from the activity of the solvent.
Anomalies de la biréfringence d'écoulement de certaines solutions très diluées d'acide desoxyribonucléique
Authors: Joly M.
Published: April 2003

L'influence de la concentration sur la biréfringence d'écoulement des solutions de desoxyribonucléate de sodium est étudiée pour divers échantillons d'ADN. Lors du gonflement dans NaCl molaire du gel d'ADN obtenu par précipitation alcoolique, l'ADN se dissout progressivement. Des prélèvements successifs permettent de séparer des fractions qui diffèrent par leurs propriétés en solution diluée. Certaines fractions, principalement celles d'extraction précoce, présentent, aux très faibles concentrations, des anomalies de biréfringence d'écoulement. C'est ainsi qu'à gradient de vitesse constant l'angle d'extinction χ et le facteur optique ψ augmcntent de façon anormalement rapide avec la dilution dès que la concentration devient inférieure à 2 × 10−5 g/ml. Dans les conditions de l'expérience, les particules d'ADN sont pratiquement indéformables; les variations de χ et de ψ. semblent donc indiquer, aux grandes dilutions, une importante diminution de la taille des particiilrs et une augmentation de leur anisotropie. Au contraire, avec les fractions d'extraction tardive, l'augmentation d'anisotropie est souvent accompagnée d'un accroissement apparent de taille. Par contre, avec les mêmes échantillons d'ADN et dnns le même domaine de concentration, la visrosimétric et l'ultracentrifugation ne mettent pas d'anomalir en évidence, d'où une apparente contradiction. La question est discutée tie savoir si les effets observés en biréfringence d'écoulement peuvent être ou non imputés à des intcractions entre les molécules dissoutes. On recherche aussi quel modèle de particule peut être simultanénent compatible avec les résultats de la biréfringence d'écodement, de la viscosité et de la sédimentation, compte tenu des données récentes sur la structure de l'ADN. Certaincs contradictions semblant difficilement réductibles, on est conduit à suggerer l'éventuelle nécessité de reconsiderér la signification physique des grandeurs mesurées et des divers paramètres utilisés pour caractériser les particules de polyelectrolytes macromoléculaires en solutions très diluées.
The second virial coefficients of polymethyl methacrylate mixed fractions in acetone
Authors: Jen‐Yuan Chien , Liang‐Ho Shih , Shih‐Chen Yu
Published: April 2003

The second virial coefficients of two polymethylmethacrylate fractions of M̄w = 1.18 × 106 and 9.2 × 104 and a series of mixed fractions from them have been measured by osmotic pressure and by light scattering in acetone at 25°C. The results show that A is practically insensitive to an admixed lower molecular weight component but very sensitive to any higher molecular weight component contained in the sample. On the contrary, A2 is sensitive to the lower molecular weight component as well as to the higher molecular weight component present. The values of A2 and A for the mixed fractions, estimated according to the theory of Flory and Krigbaum, show agreement in the general character of the A2‐ and A‐composition curves. A broad maximum occurs on the A2‐composition curve around 20% of the higher molecular weight fraction, while a rather sharp maximum occurs on the A‐composition curve around 6% of the higher molecular weight fraction.
An analysis of the experimental data of fractionation and viscometry
Authors: Mussa I.V. Carlo
Published: April 2003

A method of plotting the fractionation and viscometry data, suggested in earlier work, is illustrated by its application to the analysis of experimental data obtained by various authors in the case of nylon, polymethylmethacrylate, polystyrene, and high‐ and low‐pressure polyethylenes.
Sur la caracterisation du microgel et des molecules ramifiées dans les polyéthylènes “haute pression”
Authors: Nicolas Louis
Published: April 2003

Les masses moléculaires et les rayons de giration moyens mesurés par diffusion de la lumière sur les solutions de polyéthylène “haute pression” ne paraissent pas dépendre, d'une manière notable, de la température des mesures ou de la nature du solvant utilisé. Leur valeur élevée est due à la présence, dans la solution de particules non dissociables (microgel) engendrées par l'intervention combinée des réactions de transfert intermoléculaire et des réactions de terminaison mutuelle avec combinaison. L'agglomération progressive de ces particules, quand on ajoute du précipitant dans la solution provoque une anomalie dans le comportement du coefficient k′ de Huggins. La proportion de microgel varie beaucoup suivant l'origine du polyéthylène: les polyéthylènes Bakélite contiennent plus de microgel que les Plastylènes, mais ceux‐ci, en revanche contiennent davantage de molécules à poids moléculaire et taux de ramification intermédiaires. Différentes caractéristiques des diagrammes de Zimm révèlent la structure compacte de ces particules de microgel et la limitation de leur croissance par transfert intermoléculaire. On en conclut qu'on ne peut pas déduire valablement le taux moyen des ramifications à longue chaîne de la comparaison des valeurs de Mw/Mn avec les résultats des calculs cinétiques qui ne tiennent pas compte de cette limitation.
Work with labeled initiators
Authors: Bevington J. C.
Published: April 2003

The use of isotopically labelled reagents has contributed significantly to study of many of the processes in radical polymerizations; one of the most useful applications concerns the detailed mechanisms of initiation processes in sensitized polymerizations. Work with a typical azo initiator is reviewed. Recent studies with 14C‐benzoyl peroxide are discussed in more detail. It is shown that it is possible to determine accurately the rates of initiation processes involving benzoyloxy and phenyl radicals. It is also possible to determine the relative reactivities of unsaturated compounds towards the benzoyloxy radical. A description is given of some preliminary studies of N‐nitrosoacetanilide as a source of free radicals.
The mechanism of initiation in vinyl polymerization
Authors: Jenkins A. D.
Published: April 2003

Many studies of the polymerization of vinyl monomers initiated by molecules which decompose with the formation of free radicals have indicated that the rate of the initiation step may be a function of the monomer concentration. The present paper examines the mechanisms previously proposed to account for this behavior in the light of data on a variety of catalyst‐monomer‐solvent systems. It is shown that the rate and efficiency of initiation may, on the basis of the “cage‐effect,” vary with monomer concentration in various ways according to the relative rates of the processes involved and that, in some circumstance, the efficiency of initiation may appear to exceed unity.
Kinetics of polymerization of vinylene carbonate
Authors: Smets G. , Hayashi K.
Published: April 2003

The kinetics of polymerization of vinylene carbonate have been studied as a function of the concentration of initiator, the concentration of monomer, and the temperature. In acetone solution, the order of reaction with respect to the concentration of initiator is equal to 0.5, independent of the monomer concentration ((M) = 4.15 and 14.7 mole/l.); moreover any thermal polymerization is absent at 70°C. Contrary in ethylbenzoate ((M) = 3.41 mole/l. at 77°C.) the apparent order with respect to the initiator is 0.77; in agreement with the results of Scanlan in the case of vinylacetate. This behavior is interpreted on the basis of an efficiency factor q, corresponding to the fraction of solvent radicals able to reinitiate a growing chain. In ethylbenzoate solution this factor q is equal to 0.45 and 0.80 for vinylene carbonate and vinylacetate, respectively. With respect to the monomer concentration, the order of the reaction is 1 in the presence of ethylene carbonate as solvent over the total range of concentrations. The transfer constant with this solvent is negligible because it results from molecular weight determinations at constant initiator concentration. In acetone and in benzene the apparent order of reaction is 1, only in dilute solutions; in concentrated solutions small amounts of solvent cause a strong decrease of the rates of reactions. This behavior has been interpreted on the basis of a general kinetic scheme, in which the cross‐termination rate constant Φ and the chain transfer constant with the solvent are the predominant factors. In ethylbenzoate the reaction is characterized by a partial degradative chain transfer. The overall activation energy of the polymerization of vinylene carbonate is 22.2 kcal./mole and the coefficient A of the Arrhenius equation is equal to 3.0 × 10−9.