bluuebunny/crossref_metadata_2025 huggingface dataset:
Etude par diffusion de la lumiere et viscosimetrie du bromure de polyvinyle en solution
Authors: Ciferri A. , Kryszewski M. , Weill G.
Published: April 2003

Polyvinylbromide prepared by photopolymerization was fractionated. The molecular weights of the fractions were determined by a method which takes into account the fluorescent light for any polarization of fluorescence and anisotropy of the scattering molecule. The second virial coefficient‐molecular weight relation, the intrinsic viscosity‐molecular weight relation, and the values of the end‐to‐end distance indicate that P.V.B. follows the classical laws for a molecular coil. The molecular distribution curve was determined. The ratio Mw/Mn = 1.8.
Change in electrical resistivity of some high polymers during isothermal polymerization
Authors: Aukward J. A. , Warfield R. W. , Petree M. C.
Published: April 2003

Epoxy, polyester, and styrene isothermal polymerizations have been monitored electrically. Sample resistivity—time records at different temperatures are reported for each class of polymer. These plots suggest that relative rates of reaction could be conveniently obtained if a correlation between extent of polymerization and electrical resistivity were known for the particular resins studied. Qualitative agreement between changes in infrared absorption and changes in volume resistivity as a measure of the extent of polymerization has been obtained.
Thermal degradation of polymethacrylonitrile. Part II. The coloration reaction
Authors: Grassie N. , McNeill I. C.
Published: April 2003

The thermal coloration which occurs in copolymers of methacrylonitrile with small amounts of methacrylic acid has been studied at 140°C. The infrared spectra of colored polymers show a decrease in nitrile absorption (which has been followed quantitatively) and new absorption appears, mainly at 1693–1490 cm.−1 No volatile material is lost during coloration and molecular weight measurements show that neither chain scission nor crosslinking is involved. Copolymers of different compositions have been used to control the length of sequences of adjacent methacrylonitrile units, and it has been found that coloration is inhibited by larger concentrations of methacrylic acid. Colored polymer slowly reverts to the original material in solution, and rapid decoloration is effected by addition of aqueous solutions of acids, alkalis, and salts. A structure has been deduced for colored polymethacrylonitrile analogous to those proposed previously for paracyanogen and colored polyacrylonitrile. Essentially this is the results of the linking up of adjacent nitrile groups to form conjugated carbon‐nitrogen sequences of considerable length. It is suggested that this structure is formed in a nonradical chain process initiated at methacrylic acid units and propagated through adjacent nitrile units. The changes in solubility properties are not the result of crosslinking but of the rigidity of the modified polymer structure.
Intrinsic viscosities of cellulose derivatives
Authors: Flory P. J. , Spurr O. K. , Carpenter D. K.
Published: April 2003

Intrinsic viscosities of cellulose acetates of degrees of substitution 2.86 and 3.00 and of cellulose trinitrate have been investigated as functions of temperature, solvent, and molecular weight. Large negative temperature coefficients (ca. −0.6% per degree) of [η] appear to be characteristic of cellulosic chains. These observed decreases in [η] with temperature are due to increases in chain flexibility, which are reflected in decreases in the characteristic ratio r/M. The rather large variations in [η] with the solvent are shown also to be manifestations of altered chain flexibilities brought about in some manner, as yet unexplained, by specific solvent interaction. This behavior stands in marked contrast to that of other polymers for which r/M is independent of the solvent and varies only slightly with temperature, and for which solvent effects on [η] are wholly attributable to changes in the molecular expansion (α3) brought about by solvent action,
Viscoelasticity of some crosslinked polymers
Authors: Tokita Noboru , Kanamaru Kisou
Published: April 2003

Taking, as the samples for investigation, filaments of viscose rayon (60% crystallinity) and acetate rayon (54% acetyl) both crosslinked to various extents by tetramethylenebisethylene urea and tetramethylenediisocyanate urea as the crosslinking agents, the dynamic and transient moduli, E′, G1, G2, the internal friction, Q−1, and the apparent activation energy for relaxation of segment, ΔU, were measured and the results were considered in their relation to the degree of crosslinking. From the results, the following conclusions were made: (1) When crosslinking is caused by long molecular chains of the crosslinking agents between the nearest neighboring molecules, the intermolecular spaces are widened to some extent and the restraint of segmental motion due to the dipole interaction of the strong polar hydroxyl groups is partly relieved so that the decreases in ΔU, E′, G1, and G2 are rather caused by a small amount of the crosslinking agents; for example, while the values of ΔU and E′, for the original viscose rayon not crosslinked are 230 kcal./mole and 2.0 × 1011 dynes/cm.2, respectively, they both decrease with an increase in degree of crosslinking and each shows a minimum (ΔU = 95 kcal./mole, E′ = 0.9 × 1011 dynes/cm.2) at the amount of bound nitrogen N = 0.73%. When the crosslinking proceeds further, the primary crosslinking effect makes its appearance so that ΔU, E′, G1, and G2 begin to rise with an increase in degree of crosslinking. (2) Due to the strong solvating or plasticizing effects, the water molecules absorbed bring about a strong decrease in the apparent activation energy; ΔU = 90 kcal./mole at 80% RH, 200 kcal./mole at 66% RH, and 210 kcal./mole at 55% RH for viscose rayon.
Polymerization of vinyl stearate by high energy electrons
Authors: Burlant W. , Adicoff A.
Published: April 2003

Vinyl stearate has been polymerized by 1000 kv. electrons with field intensities ranging from 1.0 × 103 to 20 × 103 rep per second; the polymers are considered to be branched. A discontinuity of reaction rate and molecular weight with respect to temperature was noted in the vicinity of monomer melting point, and it is suggested that in this temperature region, the diffusion constant for propagation is easily affected. A linear relationship between field intensity and polymerization rate, and a constancy in molecular weight with varying field intensities, at constant total dose, indicated that polymerization occurs in “volume elements.”
Copolymerization of vinylene carbonate
Authors: Hayashi K. , Smets G.
Published: April 2003

The copolymerization of vinylene carbonate VC (M2) with several vinyl monomers (M1) has been examined. The reactivity ratios r2 and r1 have been determined in the system VC‐vinyl acetate (0.27 and 3.0), VC‐vinyl chloride (0.09 and 5.2), VC‐vinylpyrrolidone (0.4 and 0.7), VC‐methyl methacrylate (<0.01 and ∼70). These values indicate for vinylene carbonate in the Alfrey‐Price scheme a reactivity Q equal to 0.012 and a polarity e of −0.6. From the r1 and r2 parameters of the system vinyl acetatevinylpyrrolidone (0.38 and 0.44, respectively) the Q and e values of vinylpyrrolidone have also been determined: Q = 0.11 and e = −1.6. The copolymers of vinylene carbonate and vinyl acetate yield on hydrolysis polyalcohols (CH2CHOH)x(CHOH)y of which the solubility decreases with increasing content of hydroxyl groups.
Studies on the sorption of moisture by polymers. I. Effect of crystallinity
Authors: Valentine L.
Published: April 2003

The relation between the sorption of moisture by polymers and their crystalline structure is reviewed, and it is concluded that, if a dry polymer can form well‐defined crystallites, then these crystallites will usually be inaccessible to water vapor. The ratio of the moisture sorption of a polymer to that of its completely amorphous form will thus be a measure of the noncrystalline fraction. Methods of estimating the sorption of the amorphous form of a polymer that is normally partially crystalline are then discussed. In one method, the polymer is prepared in various degrees of crystallinity, and the relation between sorption and crystallinity is extrapolated to zero crystallinity. A variant of this method involves the measurement of the accessibility to some simple reagent that reacts only in the noncrystalline regions, e.g., D2O; the relation between sorption and accessibility is extrapolated to 100% accessibility. The second main technique is based on the fact that conversion of a partially crystalline homopolymer into a random copolymer frequently destroys the crystallinity over a wide range of compositions, within which there is a linear relation between sorption and composition. Extrapolation of this linear relation enables the sorption of the completely amorphous homopolymer to be found. These methods have been applied to several polymers, e.g., cellulose, polyvinyl alcohol, wool. For cellulose, in particular, very good agreement is found between many different methods, and the sorption isotherm of amorphous cellulose has been calculated.
On the stress relaxation of nylon 6
Authors: Yoshitomi Tatsuya , Nagamatsu Kazuo , Kosiyama Kiiti
Published: April 2003

The stress relaxation of low‐crystallinity nylon 6 is measured by torsional method at various temperatures in three (0, 40, and 75%) relative humidities. As the whole procedures are very accurate, the results contain little experimental error. The relaxation data at 0 and 75% relative humidity can be reduced to respective master curves by Ferry's reduction method. Considering the changes of structure by difference in humidity, it is found that these two master curves are reduced further to one single general master curve by the aid of some molecular theory of the crystalline polymers. By the use of first‐order approximation, the relaxation time spectrum of this crystalline polymer is obtained for a very wide time scale range, more than 1021 sec. The resultant spectrum is fairly high and flat, reflecting the characteristic features of crystalline polymers. It has, however, two weak but distinct maxima, corresponding to the so‐called “wedge” and “box” distributions in the relaxation time spectrum of the amorphous polymers. Based on the existence of this box distribution in the spectrum, it is suggested that there should exist some sort of clusters effective in the mechanical behavior of the crystalline polymers.
Copolymerization of vinylene carbonate with vinyl thiolacetate and N,N,N‐triethyl‐N‐[2‐(methacryloxy) ethyl]ammonium iodide with 4‐vinylpyridine
Authors: Overberger C. G. , Biletch H. , Nickerson R. G.
Published: April 2003

Copolymerization reactivity ratios for the system vinyl thiolacetate (M1)‐vinylene carbonate (M2) have been determined to be r1 = 12.9 ± 1.1 and r2 = 0.04 ± 0.01 by the method of Fineman and Ross. For the system 4‐vinylpyridine (M1) and N,N,N‐triethyl‐N‐[2‐(methacryloxy)ethyl]ammonium iodide (M2)r1 = 0.30 ± 0.02 and r2 = 0.61 ± 0.09 as determined by use of the “integrated equation” of Mayo and Lewis. A base‐soluble, easily oxidizable sulfhydryl copolymer has been prepared by hydrolysis of the copolymer of vinyl thiolacetate and vinylene carbonate. The sulfhydryl copolymer is of interest as a successful short lived prophylactic for ionizing radiation.
Diffusion of allyl chloride in polyvinyl acetate. Part I. The steady state of permeation
Authors: Meares P.
Published: April 2003

Only for neopentane in polyisobutene and for methylene chloride in polystyrene has the diffusion coefficient of a vapor in a polymer been determined both by steady‐state and by transient‐state methods. In the former case, well above the glass temperature of the polymer, there was a good agreement. In the latter case, below the glass temperature, the two methods seriously disagreed. This paper describes steady‐state measurements for allyl chloride in polyvinyl acetate at 40°, a few degrees above the glass temperature. Experiments were made with thin membranes of polymer mounted in a stainless steel cell. Vapor permeating was collected in a known volume and its pressure determined as a function of time, using a Pirani gage, for short periods until a steady state was established. The permeation data have been used to determine the integral D, differential D, and intrinsic 𝒟 diffusion coefficients as a function of concentration cg up to 0.085 g. allyl chloride per g. polymer. Log D is found to be a curved function of cg. Kokes and Long, from observations of sorption kinetics, have also determined D for this system and find log D to be linearly related to cg. The data given here can also be represented by a straight line, but of steeper slope, over the concentration range studied by Kokes and Long. This line and the data of Kokes and Long extrapolate to the same value of log D at cg = 0. It is concluded that transient and steady‐state determinations agree when there is no polymer swelling but that, at finite concentrations of penetrant, the polymer chains do not have time to assume their equilibrium configuration during the transient‐state experiments. Complete relaxation occurs before a steady state is established and this leads to a higher value of D being recorded. Bueche's theory of segmental mobility can be applied to the change in jumping frequency of the polymer segments with diluent concentration at constant temperature. Assuming a direct proportionality between jumping frequency and 𝒟, the theoretical equation successfully predicts the observed dependence of 𝒟 on the volume fraction of diluent using physically justified values for all parameters.
Thermodynamic properties of solutions of cellulose derivatives. I. Dilute solutions of secondary cellulose acetate
Authors: Moore W. R. , Tidswell B. M.
Published: April 2003

Osmotic pressure of dilute solutions (c≤1.0 g./100 ml.) of a fraction from a secondary cellulose acetate in representative solvents have been measured at two or three temperatures. Number‐average molecular weights in acetone, aniline, methyl acetate, and pyridine do not vary with temperature but are significantly higher in methyl acetate in which association of polymer is possible. Molecular weights in acetic acid, nitromethane, and dioxane decrease with increase of temperature presumably because of degradation. Values of ΔF1, ΔH1, and ΔS1 have been estimated from temperature coefficients of osmotic pressure. All the systems are endothermal. It is suggested that the polymer is fully solvated and that solvated polymer and solvent mix with absorption of heat. With the exception of the aniline system, values for which are high, values of ΔH1 appear to be in the order to be expected from the solubility parameters of solvent and solvated polymer. ΔH1 and ΔS1 decrease with increase of temperature in all cases except that of acetic acid. ΔH1/ϕ, where ϕ2 is the volume fraction of polymer, seems to be effectively constant at each temperature. Values of ΔS1 are greater than “ideal” values but are less than those obtained for comparable systems containing more flexible and less polar polymers. ΔS1/ϕ decreases with increase of concentration but in some cases there is an increase at the highest concentration. ΔF1 becomes more negative with increase of temperature. It would seem that both entropy and heat terms contribute to the value of the interaction parameter χ1. It is possible, if solvation and the segment size and stiffness of chains are taken into account, that approximate lattice theories may apply to solutions of cellulose derivatives at lower concentrations than in cases of more flexible and less polar polymers.
The degradation of addition polymers by ultrasonic waves. II.
Authors: Mostafa M. A. K.
Published: April 2003

An accurate solution of the kinetics of degradation of addition polymers of known initial size distribution is given. This solution differs from an approximate solution given in a previous paper. The result obtained is applied to a sample of 1% polystyrene in benzene. The theoretical weight distribution curves at different stages of degradation, derived from the approximate and the accurate solutions, are given. The points of difference between the two resulting distributions are briefly discussed.
Polymerization of triallyl cyanurate
Authors: Clampitt Bert H. , German Dale E. , Galli Joseph R.
Published: April 2003

Differential thermal analysis (DTA) curves for the polymerization of triallyl cyanurate show two exothermic maxima. By integrating the area under the DTA curves the heats evolved during each exotherm are determined. Combination of these heat values with infrared spectral data indicates that the first step in the polymerization of TAC involves polymerization of two allyl groups, and the second step involves rearrangement to the polymerized triallyl isocyanurate form followed by polymerization of the remaining allyl group. Heats of combustion of TAC and TAIC indicate that the magnitude of the heat released during the second exotherm is reasonable and in line with the proposed mechanism.
Separation of amylose from amylopectin of starch by an extraction‐sedimentation procedure
Authors: Montgomery Edna M. , Senti F. R.
Published: April 2003

Corn, wheat, and potato starch were fractionated into their amylose and amylopectin components by selective extraction of amylose in hot water after the starch had been pretreated by heating in aqueous mixtures of glycerol, n‐butanol, Pentasol, Cellosolve, or dioxane. About three‐fourths of the amylose was leached in relatively pure form from starch in the first extraction at 98°C. The granule residue, sedimented by centrifugation, was separated as relatively pure amylopectin after two or more additional extractions. Retention of the coherent structure of the granule in the extracted residue emphasizes the importance of amylopectin to granule properties. Amylose fractions isolated from successive extractions had progressively lower intrinsic viscosities and absorption coefficients of their iodine complexes indicating that this component was subfractionated according to molecular size and/or structure. X‐ray diffraction patterns of the pretreated starches indicated that a complex of amylose and organic solvent was formed which may account for the increased solubility of amylose after pretreatment. Evidence is presented which shows that little, if any, amylose occurs in the crystalline regions of granular starches.
The ultracentrifuge as an instrument for testing adhesion
Authors: Patrick R. L. , Vaughan W. A. , Doede C. M.
Published: April 2003

A technique was developed which allows the determination of essentially pure tensile strengths of single interface adhesive samples. Utilizing a suitably modified ultracentrifuge, model adhesive systems were ruptured in an attempt to obtain relative strengths of adhesive bonds in the interface.
The Flory constants for poly‐4‐vinylpyridine in ethanol
Authors: Berkowitz Joan B. , Yamin Michael , Fuoss Raymond M.
Published: April 2003

Vinylpyridine was polymerized in suspension, using azobis‐iso‐butyronitrile as initiator. The polymer was fractionated by partial precipitation from methanol solutions by addition of toluene to cloud point in chilled solution and then raising the temperature. Viscosities of four fractions were determined at 25, 50, and 70° in absolute ethanol. Rayleigh ratios and scattering asymmetry were determined for eight fractions; from the corresponding Zimm plots, molecular weights, coil diameters, and virial coefficients were determined. Addition of ammonia was found necessary at low concentrations to suppress ionization due to traces of acid impurities. Addition of water (a nonsolvent) lowers the second virial coefficient. Molecular weights were determined for two fractions by osmotic pressure. In absolute ethanol, the results are summarized by the equation [η] = 2.5 × 10−4M0.68; experimental range 0.102 ⩽ 106 M ⩽ 1.85. The second virial coefficient from light scattering was 4.2 ± 0.3 × 10−4, independent of molecular weight; the osmotic values agreed within experimental error. The Flory constant was found to be 2.1 ± 0.3 × 1021. Extrapolation for the θ‐point leads to the rough estimate θ ≈ −50°C. Evidence is presented which shows that polyvinylpyridine degrades slowly in solution.
Linear polyesters derived from protocatechuic acid
Authors: Bock Louis H. , Anderson James K.
Published: April 2003

Protocatechuic acid which is available from tree sources was converted to a hydroxymethyl‐1,4‐benzodioxan carboxylic acid by reaction with epichlorohydrin. This hydroxy acid was condensed by heating under vacuum to from a linear polyester which was converted to fibers by melt spinning. By applying stretch during spinning a fiber with a tenacity of 4.4 g. per denier, a melting point of 210°C. and a softening point of 145°C. was obtained. Removal of one of the isomers formed in the preparation materially raised the softening point and raised the melting point above the decomposition temperature.
A diffusivity approach for studying polymer structure
Authors: Auerbach I. , Miller W. R. , Kuryla W. C. , Gehman S. D.
Published: April 2003

Study of the diffusion in polymers of molecules comparable in size and structure to the segments of the chain molecules is suggested as a means of securing information on structure and molecular friction forces in polymers. A convenient method for measuring the diffusivity in polymers of such compounds tagged with C‐14 was devised and used to study the diffusivity of octadecane, octadecanol, stearic acid, and octadecyl stearate for a range of temperatures in polymers including natural rubber, GR‐S, polybutadiene, polyisoprene, and polyisobutylene. Diffusivities were independent of concentration for the range used. The diffusivities of straight chain hydrocarbons in natural rubber appear to vary inversely as the molecular weight of the diffusing compound. Evidence was found for association effects in the diffusion of stearic acid in natural rubber. Activation energies for diffusion of the compounds were quite similar in any one polymer and of the same order as reported for low molecular weight hydrocarbons and for viscous flow. Larger differences in activation energies were observed for diffusion in the different polymers. Correlations were observed for the diffusivities of octadecane in a series of polymers with their densities and thermal expansivities, especially the latter. Some study was given to the effect on the diffusivity of octadecane of such parameters as polymer unsaturation, solution viscosity, molecular weight, and crosslink density. The diffusivity of octadecane in natural rubber had a pronounced maximum as a function of crosslink density, coinciding with the maximum in tensile strength. Possible implications of this are discussed. The diffusivities of octadecane in a series of elastomers were studied in relation to the internal frictional losses observed for 60 cps vibrations over a range of temperatures. It was concluded that frictional forces deduced from the diffusivity measurements have some correspondence to high frequency viscoelastic phenomena which involve small units of structure comparable in size to the segments of the polymer molecules.
Copolymers of butadiene and unsaturated acids: Crosslinking by metal oxides
Authors: Cooper W.
Published: April 2003

Butadiene copolymers of low molecular weight containing combined acid groups react with metal oxides to give products with unusual properties. The salts, particularly the zinc and cadmium compounds, exhibit plastic flow under slowly applied stresses but are highly elastic on sharp impact; products closely resembling the silicone “bouncing putty” can be obtained. Although these salts contain many “crosslinks” per chain they are, within limits, soluble in solvents such as benzene or pyridine. The solubility is determined by the molecular weight of the copolymer, its acid content, and the nature of the metal ion. Their solutions are characterized by marked changes in viscosity on dilution and they develop osmotic pressures in dilute solution comparable to those from the unreacted acid copolymers. The high molecular weight polymers are strong elastomers which show marked creep under stress. The properties of salts of both high and low molecular weight copolymers are consistent with the view that exchange reactions can occur between ionic crosslinks on different chains when stressed or under the influence of solvents. This ability to relieve local stresses on stretching is thought to be of consequence when considering the tensile properties of these and other elastomers.
Estimating the unperturbed dimensions of polymer molecules
Authors: Krigbaum W. R.
Published: April 2003

A procedure is described for estimating unperturbed molecular dimensions from data obtained in “nonideal” solvents. A knowledge of [η], M, and A2 is required. This should be particularly useful for high melting crystalline polymers, since for these polymers a direct determination by light scattering measurements performed under Flory θ conditions is complicated by the tendency of the polymer to crystallize from solution as the solvent becomes thermodynamically poorer. The intrinsic viscosity at θ, [η]θ, is calculated from the semi‐empirical relation:

where Γ2 = A2M. The unperturbed dimensions are then calculated through use of the relations appearing in Flory's treatment of intrinsic viscosity:

Unperturbed dimensions calculated in this manner for polyisobutylene and polystyrene compare favorably with values directly measured by light scattering. This procedure is used to estimate the unperturbed dimensions of polyethylene, 6,6‐nylon, polyethylene terephthalate, and polyacrylonitrile. A comparison of the relative chain stiffness of these polymers allows some interesting correlations with Flory's theoretical treatment of semi‐flexible chain molecules.
A study of the elastic modulus and extensibility of the crystalline regions in highly oriented polymers
Authors: Dulmage W. J. , Contois L. E.
Published: April 2003

The elastic modulus of highly oriented crystalline polymers is discussed in terms of a series model. As has been shown previously, if a polymer has fully extended chain configurations within the crystalline regions, the modulus of this phase may be expected to be high. In this case the macroscopic elastic modulus is limited primarily by the characteristics of the amorphous phase and the degree of crystallinity. Where the fiber identity period (FIP) indicates a contracted chain configuration, the crystalline regions, themselves, may be extensible and their modulus may not be much greater than that of the unoriented amorphous phase. In this case the macroscopic elastic modulus is much less dependent upon orientation and crystallinity. The elastic moduli of eight chemically different polymers have been determined from measurements of their macroscopic moduli and the extensions of their FIP when subjected to small strains. Where the degree of crystallinity could also be determined the modulus of the amorphous phases were also determined from these same measurements. The moduli of some of these systems are discussed in terms of their structure as deduced from birefringence measurements and x‐ray diffraction patterns.
Solution and fractionation properties of graft polymers
Authors: Kilb R. W. , Bueche A. M.
Published: April 2003

The lattice model is used to predict the solution properties of graft and block polymers. It is found that the solubility of a graft polymer is critically dependent on the heat of interaction of the various components of the polymers with the solvent. Furthermore, the precipitates from fractionations of graft polymer solutions are no longer simple functions of the over‐all molecular weight.
Isopiestic measurements of electrolyte activity—sky blue FF and sodium polymethacrylate
Authors: Chadwick C. S. , Neale S. M.
Published: April 2003

Isopiestic measurements have been made on aqueous solutions of Sky Blue FF and of sodium polymethacrylate, and the relevant activity coefficients estimated.
Formation of block polymers of butyl acrylate with styrene and vinyl pyridine
Authors: Funt B. Lionel , Collins Edward
Published: April 2003

Block copolymers of butyl acrylate–styrene and butyl acrylate–2‐vinyl pyridine were prepared in a flow system. An intense ultraviolet source was focussed on a stream of monomer falling into a second monomer. The period between photochemical initiation in the stream and block polymer formation was controlled by varying the flow rate and distance of fall. By application of nonstationary state kinetics the yield of polymer in the stream was calculated and compared with the experimental yield determined spectrophotometrically. A comparison was made of the composition of random copolymer based on the copolymerization equation and that determined experimentally. The yields and compositions of the products showed that the desired block copolymers had been formed.
Graft copolymers: Synthesis and characterization
Authors: Shashoua V. E. , Van Holde K. E.
Published: April 2003

True 100% grafted polymers were prepared in a two‐stage emulsion polymerization process. Microgels of styrene crosslinked with divinylbenzene, methyl acrylate crosslinked with divinylbenzene, and acrylonitrile crosslinked with methylene‐bisacrylamide were used as first stage polymers, and the grafting of styrene and acrylonitrile were studied. The polymers were analyzed as microsols by limiting viscosity number and by ultracentrifuge measurements. In the ultracentrifuge the quantitative separation of crosslinked particles from linear polymers was demonstrated. From a study of the polymerization conditions which result in a single sedimenting component in the ultracentrifuge, 100% grafted polymers were synthesized. The results indicated that in order to obtain 100% grafting initiation must be by free radicals present in the polymer particles with none from residual catalyst or by thermal initiation. The existence of polymeric free radicals of lives greater than 100 days is demonstrated.
Further study of the decomposition of benzoyl peroxide in the presence of styrene
Authors: Bevington J. C. , Toole J.
Published: April 2003

Styrene has been polymerized at 80°C. using as sensitizer benzoyl peroxide labeled with carbon‐14 in the benzene rings. From the specific activities of the polymers before and after hydrolysis, it has been possible to compare the velocity constants for the alternative reactions of the benzoyloxy radical, viz., addition to monomer or decomposition into a phenyl radical and carbon dioxide. By combining these results with those obtained at 60°C., the difference between the activation energies for the two reactions of the benzoyloxy radical has been calculated. Assuming normal values for the activation energy of the addition reaction and for the frequency factor of the decomposition reaction, the rate constant for the latter has been calculated.
Rebound relaxation spectra and principle of constant isoelastic curing rates
Authors: Gordon Manfred , Grieveson Brian M.
Published: April 2003

An apparatus has been constructed for measuring rapidly the coefficient of restitution by impact of a steel ball on samples of polymers as a function of temperature. Such measurements are described as rebound relaxation “spectra,” the energyEabsorbed on impact being plotted against temperatureT. The main absorption peak corresponds to the dynamic second order transition. First‐order transitions give anS‐shapedE–Tplot. The validity and sensitivity of the technique are illustrated with rebound spectra of amorphous and crystalline linear polymers as well as crosslinked resins. The kinetics of various “curing” (crosslinking) reactions are followed in terms of the displacement of the second order transition peak towards higher temperatures. Where such a curing reaction approaches an equilibrium (or pseudo‐equilibrium), the observed kinetics are interpretable on the theory of relaxation processes. For this purpose, the displacement of the peak may be charted fromisothermalmeasurements ofE. A more significant technique usesisoelasticmeasurements of the peak displacement,i.e., measurements of the change with time of the temperature required to keep the rebound height constant. The isothermal approach of the peak to its equilibrium value is a typical Maxwellian (first order) rate process. The isoelastic approach to equilibrium atconstantrebound producesconstantrates of peak displacement over big temperature ranges. This is explained qualitatively because elastic rebound and chemical crosslinking are both dependent on the molecular relaxation rate of chain segments. The theory is illustrated with the curring reactions of expoxide, polyester, urea‐formaldehyde, and phenol‐formaldehyde resins. The epoxide system studied behaves as a “conservative” system, in which the rate of cure is dependent on the state of cure and the temperature, but not on the curing schedule by which that state of cure has been achieved.
The phenomenon of “inversion” in thermal diffusion of high polymer solutions
Authors: Kossler I. , Krejsa J.
Published: April 2003

In the study of thermal diffusion of high polymers in a solvent, instruments are commonly used which have a lower and upper chamber. The thermal diffusion effect causes an increase of concentration in the lower chamber and, conversely, a decrease in the upper one. Simultaneous changes in the average molecular weights occur in both chambers, and, in agreement with theory, the average molecular weight in the lower chamber increases. In our experiments we found that the average molecular weight first increases in the upper chamber, reaches a maximum, and then decreases to values even below the initial value. The opposite occurs in the lower chamber. This phenomenon of “inversion” must be taken into account in studying the applicability of thermal diffusion for obtaining distribution curves. We are also attempting to use it directly for separating fractions of lower molecular weight.
Détermination de la fonction de distribution d'un polymère en solution. Etude et comparison de deux méthodes
Authors: Freund L. , Daune M.
Published: April 2003

On considère les fonctions de distribution g(S) et f(D) d'un polymère, relatives aux deux paramètres: constante de sédimentation S et constante de diffusion D. La distribution g(S) est obtenue à partir des mesures de vitesse de sédimentation par la méthode de Baldwin et Williams. Pour obtenir la distribution f(D) on applique la méthode que nous avons précédemment décrite et qui consiste à effectuer une double transformation de Fourier sur la courbe expérimentale. Après avoir établi les deux courbes de distribution dans le cas d'un alcool polyvinylique, nous avons comparé les résultats des deux méthodes et essayé de déterminer la courbe de distribution des masses moléculaires.
Aromatic polyanhydrides, a new class of high melting fiber‐forming polymers
Authors: Conix Andre
Published: April 2003

Contrary to the aliphatic polyanhydrides prepared by Carothers, polyanhydrides containing aromatic nuclei in the main chain possess high melting points and good hydrolytic stability. A number of different aromatic polyanhydrides were prepared. Their preparation and properties, such as fiber‐forming properties, melting points, glass transition temperatures, and crystallinity, are described. An effort has been made to correlate some selected physical properties, such as melting points and crystallizability, with the chemical structure of the particular polyanhydride. The influence of p‐phenylene, m‐phenylene, carbonyl, ether, thioether groups, etc. on the properties of the polymers is discussed.
Synthèse de copolymères greffés par action des rayonnements ionisants sur des solutions de polyisobutylène dans le styrolène
Authors: Sebban‐Danon Jeanne
Published: April 2003

On étudie la polymérisation radiochimique du styrolène en présence de polyisobutylène. La polymérisation du styrolène est amorcée par les radicaux provenant du styrokléne et les radicaux provenant du polyisobutyléne, ces deux sortes d'amorcage conduisant respectivement à la formation de polystyroléne et de copolymère greffé, polystyroléne sur polyisobytyléne. On édie l'influence de l'intensité du rayonnement et de la concentration initiale en polyisobutylène sur la cinétique de la réaction.
Etude de la polarisation de fluorescence de la polyéthylène imine conjuguee
Authors: Wahl Ph.
Published: April 2003

Un appareil de mesiire oculaire de la polarisation de fluorescence a été construit. Avec cet appareil nous avons étudié la polarisation de la lumière fluorescente émise par des polymères possédrtnt des groupes NH ou NH2, et sur lesquels a été fixé le chlorure de l'acidc 1‐diméthylaminonaphtalène‐5 sulfonicque. De la variation de la polarisation avec la température on déduit le temps de relaxation de l'unité rotetionnelle de ces polymères. Ceci renseigne sur leur rigiditè. Des résultats sont présentés pour la polyéthylène‐imine.
Contribution à l'étude des hauts polymeres par la viscosité des couches monomoléculaires
Authors: Jaffe J. , Loutz J. M.
Published: April 2003

Les propriétés des couches monomoléculaires constituent un moyen d'investigation qui fournit des renseignements sur la grandeur de la molécule, sur sa morphologie e t parfois sur sa structure. C'est l'application de I'osmométrie superficielle qui conduit à la détermination de la masse nioléculaire de certaines macromolécules. De nombreux exemples montrent m e concordance avec les résultats classiques obtenus par d'autres procédés. Cette méthode a été employée avec succès surtout pour les protéines. En ce qui concerne les macromolécules de synthèse, on observe des résultats qui ne sont pas toujours en accord avec les données obtenues par les techniques hahituelles. En général, ces résultats sont moins concordants pour les macromolécules possédant une faible rigidité. Dans ce travail, nous prenons en considération deux cas: une macromolécule assez rigide, e t deux autres plus ou moins flexibles. Nous proposons m e nouvelle méthode dc détcrmination de la masse moléc:ulaire par la viscosimétrie superficielle. Cette méthotle envisage la transposition de l'équation de Staudinger dans l'espace à deux dimensions.
Neuere bestimmungen des molekulargewichtes und der molekularen konstanten von cellulosenitraten in lösung
Authors: Meyerhoff G.
Published: April 2003

Es wurden die Sedimentations‐ und Diffusionskonstanten für zwölf Fraktionen und ein sehr hohes unfraktioniertes Präparat von nitrierter Baumwollcellulose untersucht. Der Stickstoffgehalt aller Präparate lag bei 13,8%. Für die Viskositätszahl in Aceton bei 20°C ergibt sich zum Ultrazentrifugenmolekulargewicht die Beziehung [η] = 2,8 × 10−3 M1.00S.D in cm3 g−1 beim Gradienten 0. Rechnet man die Ultrazentrifugenmessungen von Jullander auf unseren Stickstoffgehalt um und die Messungen von Newman, Loeb, Conrad in Aethylacetat auf Aceton, so zeigen die drei Ultrazentrifugenmessungen untereinander recht gute Uebereinstimmung. Dagegen liegen die Lichtstreuungsmolekulargewichte MLS bei gleicher Viskositätszahl druchweg höher, was vielleicht durch den Eichstandard oder auch durch nicht ganz reine Lösungen erklärt werden kann. Aus [η], M und dem Reibungsfaktor f werden nach Debye‐Bueche‐Peterlin die Knäueldurchmesser berechnet. Da MLS viel grösser als MS.D, ist, lassen sich die Knäuelradien als Funktion des Molekulargewichtes bei den verschiedenen Methoden nicht vergleichen. Jedoch stimmen bei gleicher Viskositätszahl die Knäueldurchmesser (r)1/2 der Lichtstreuung gut mit den berechneten überein. Es ergibt sich für alle Molekulargewichte, dass mit guter Näherung (r2) proportional M1,34 ist, an Stelle von M1,00 beim idealen Knäuel. Das sehr steife Cellulosemolekül zeigt also in Lösung ein nicht‐ideales Verhalten. Die Gleichung (r2) ∼ M gilt nicht, wir finden auch keinen Hinweis darauf, dass sie vielleicht noch als Grenzgesetz für extrem hohe, nicht mehr messbare Molekulargewichte erreicht wird. Es besteht für Cellulosenitrate ein ähnlicher Zusammenhang, wie er früher für Polymethacrylate in Aceton gefunden wurde, nur dass hier die Effekte ausgeprägter sind. Ein Exponent > 1/2 in der Viskositäts‐Molekulargewichtsbeziehung läuft parallel mit einem zweiten Virialkoeffizienten > 0 und einer Zunahme des Kuhn'‐schen statistischen Fadenelementes mit wachsendem Molekulargewicht.
Chemical effects in the irradiation of polymers in the solid state
Authors: Weiss J.
Published: April 2003

The action of ionizing radiations on polymers leads, in general, to degradation and, in certain cases, to some further polymerization (crosslinking). It is known, on general physical grounds, that the energy of the radiation is converted into ionization and excitation of the molecules present in the system. The question arises as to how the radiation‐produced primary species enter into the mechanism of the subsequent chemical processes. It is suggested that electronic processes are of considerable importance in the radiation‐induced reactions of solid polymers; this is discussed with reference to various physical and chemical data on irradiated polymers (radiation‐induced electrical conductivity, paramagnetic resonance, etc.). A unified picture for the mechanism of the action of ionizing radiations is proposed, based on the zone theory of solids.
Molecular distributions in polycondensations involving unlike reactants. II. Linear distributions
Authors: Case L. C.
Published: April 2003

A general procedure is developed for the treatment of the molecular distributions arising from linear polycondensations involving more than one monomer. The distributions actually arising are rather complex, and are usually represented by several series. A method is elucidated by which the number average molecular weight may be derived directly and by which normalizing factors for the number and weight fraction distributions may be determined. The general expression for the number fraction of a given species of molecule is found to be a product of several probabilities. The weight fraction distribution and the weight average molecular weight may be derived in a straightforward manner from the number fraction distribution. A number of molecular distributions are worked out in detail. These include reactions of diacids with glycols, reactions of acid anhydrides with glycols, reactions involving asymmetric reactants, and reactions of mixtures of the above types of reactants. Certain polycondensations of interest are treated by the methods of this work. The results are the following: (1) The distribution of AB self‐condensing is identical to the condensation of AA with BB only if all have identical molecular weights and equivalent amounts of AA and BB are used. (2) In the condensation of AA with BB, the more unequal the proportions, the broader the molecular weight distribution. (3) In the above condensation, the greater the difference in molecular weights, the broader the distribution. (4) For all distributions, as M̄N → ∞ M̄W/M̄N → 2. (5) The distributions for anhydrides or unsymmetrical reactants are narrower than for symmetrical reactants, and are different from each other.
Freie radikale in fester phase
Authors: Breitenbach J. W. , Frittum H.
Published: April 2003

Radikalbidende Substanzen, in festen Polymeren gelöst, geben unter geeigneten Reaktionsbedingungen freie Radikale, die in den hochpolymeren Substanzen verteilt sind. Bei der Reaktion zwischen Radikal und Polymeren werden Seitengruppen in dieses eingeführt und es tritt auch ein Kettenabbau des Polymeren ein. Bei Raumtemperatur ist die Reaktionsmöglichkeit der Radikale so stark herabgesetzt, dass es gelingt die Radikale durch längere Zeit in dem Polymeren zu konservieren.
Influence of the solvent on the polymerization velocity of trifluorochloroethylene
Authors: Lazár M.
Published: April 2003

The influence of carbon tetrachloride, pentachloroethane, 1,2‐dichloroethane, 1,1,2‐trifluorotrichloroethane, benzene, and 1,3,5‐trimethylbenzene on the velocity of the benzoyl peroxide‐initiated polymerization of trifluorochloroethylene was studied over a wide range of concentrations. Throughout the entire range of variation of concentration of trifluorochloroethylene, there was no simple relation between concentration and velocity of polymerization; the solvents in these systems did not behave merely as diluents. The influence of the solvents on the polymerization velocity of trifluorochloroethylene varies greatly: some solvents behave as an inert medium for example, 1,1,2‐trifluorochlorethane, benzene; other solvents, however, act as inhibitors 1,3,5‐trimethylbenzene. Finally, certain chlorinated hydrocarbons carbon tetrachlorides, pentachloroethane, 1,2‐dichloroethane show a maximum in the reaction velocity at a certain ratio to the monomer. Various possible hypotheses are discussed which could explain the observed anomalous dependence of increased polymerization velocity, on a lowering of the concentration of trifluorochloroethylene.
Chain transfer of polymer in radical polymerization
Authors: Lím D. , Wichterle O.
Published: April 2003

Chain transfer with polymethylacrylate was determined by measuring chain transfer constants with model substances resembling part of polymer chain with P = 1–3 and extrapolating to higher P. The found value, 5 × 10−5, is much less than expected for an explanation of gel formation in the polymerization of methyl acrylate.
Une méthode nouvelle de synthese de la polyvinylamine
Authors: Hart R.
Published: April 2003

La polyvinylamine a été obtenue par solvolyse des poly‐N‐vinylcarbamates dont la préparation et les propriétés ont été décrites dans une étude antérieure [Bull. soc. chim. Belges, 66, 229 (1957)]. La polyvinylamine peut ainsi être synthétisée à partir de l'acide acrylique:
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La solvolyse des esters de l'acide poly‐N‐vinylcarbamique peut être effectuée soit en milieu aqueux (hydrolyse acide ou alcaline), soit en milieu anhydre (HBr ou HCl dans l'acide acétique glacial). Une polyvinylamine pratiquement pure est obtenue lorsque le poly‐N‐vinylcarbamate de benzyle est traité par l'acide bromhydrique dans l'acide acétique, a température ordinaire. La structure des polymères ainsi préparés est établie par l'analyse élémentaire, la détermination de la teneur en groupes amines primaires (méthode de Van Slyke), ainsi que par des titrations potentiométriques et conductimétriques. Tous ces résultats sont concordants. LEs courbes viscosimétriques présentent l'allure caractéristique des polyélectrolytes.
Principles of protein structure and their application to synthetic polypeptides and fibrous proteins
Authors: Huggins Maurice L.
Published: April 2003

The principles of protein structure may be stated as follows: (1) Proteins are composed primarily of long polypeptide chain molecules. (2) In natural proteins, only levo orientations are present. (3) The distances between adjacent bonded atoms and the angles between adjacent bonds are approximately the same as in comparable small molecules. (4) Hydrogen bonds are formed wherever possible. (5) Like atomic groups tend to be surrounded by close neighbors in a like manner. (6) Atoms, atomic groups, and molecules tend to pack as closely as possible. These principles, first published by the writer in 1943, have been amply verified by subsequent developments. Their application is illustrated by brief consideration of the structures of silk, polyglycine II, α‐ and β‐polypeptides, α‐ and β‐keratin, and collagen. It is proposed that in α‐keratin the polypeptide helices are grouped (not coiled) into triplets, triple‐triplets or “nonets,” and 27‐chain groups, to give most efficient packing of the side chains. For collagen, a single chain helical molecule is proposed, with hydrogen bonds forming 10‐atom rings and with the residues in groups of three. One residue of each group, it is suggested, is pro, hypro, asp, or glu, with the last two types existing as rings, formed either by condensation or by hydrogen‐bonding.