bluuebunny/crossref_metadata_2025 huggingface dataset:
Copolymerization of trialkyl aconitates with butadiene and some vinyl monomers
Authors: Marvel C. S. , Johnson John W. , Economy James , Scott George P. , Taft W. K. , Labbe B. G.
Published: April 2003

Reactivity ratios have been determined for the copolymerization of trimethyl aconitate with butadiene, styrene, acrylonitrile, and vinyl chloride, and for triethyl aconitate with butadiene and styrene. The values obtained indicate that trialkyl aconitates are very reactive in free radical initiated copolymerizations. No copolymerizations of aconitic acid were realized. A copolymer of butadiene and trimethyl aconitate has been prepared in a modified Mutual recipe at 50°C. The copolymer shows fair oil resistance and tensile properties but the low‐temperature properties are poor. The temperature rise of trimethyl aconitate copolymer is possibly better than that of standard GR‐S made at 50°C.
Some experiments on sulfur as inhibitor for the polymerization of styrene
Authors: Bartlett Paul D. , Trifan Daniel S.
Published: April 2003

The rate of thermal polymerization of styrene in the presence of sulfur has been followed viscometrically and dilatometrically and the product has been examined as to its molecular weight, content of total and mercury‐extractable sulfur, and its effect on the polymerization of fresh styrene.

Polymer isolated during the inhibition period by methanol precipitation contains close to eight atoms of sulfur per molecule of polymer, and these sulfur atoms are so located that complete desulforization by Raney nickel reduces the molecular weight of the polymer by not more than a factor of 2–3. The number of sulfur atoms per molecule decreases during the progress of the polymerization. The polysulfides formed at first are inhibitors, as in the case of vinyl acetate polymerization. As the size of the polysulfide units and the inhibitory power decrease, the activity of the polysulfides as chain transfer agents persists and there appears a mild initiatory reaction such that the eventual rate of polymerization is almost twice the normal thermal rate. This acceleration can be produced by adding the precipitated polymer from a sulfur‐inhibited polymerization to fresh styrene.

Judged by the composition of the methanol‐insoluble polymer, the inhibitory constant (kt/kp) of sulfur for styrene is of the order of 52. During the first 24 hours of a sulfurinhibited polymerization at 80–89° sulfur molecules were consumed 22 times as fast as the presumed rate of thermal initiation of pairs of polymerization chains. One‐third of this sulfur was in polymer of too high molecular weight to be the result of diradical initiation intercepted by sulfur. The mechanisms involved are discussed.
Nuclear magnetic resonance absorption in polymethyl methacrylate and polymethyl α‐chloroacrylate
Authors: Powles J. G.
Published: April 2003

Nuclear magnetic resonance absorption measurements on polymethyl methacrylate and polymethyl α‐chloroacrylate in the temperature range −196 to 200°C. are reported. An interpretation of the results is given and a fairly complete correlation is found between the results of the present measurements and the known dielectric and mechanical properties of the materials. The main reduction in line width, in polymethyl methacrylate above 70°C., occurs in two stages corresponding to the two dielectric and mechanical absorption regions, the so‐called α and β processes. The results are not inconsistent with the identification of the β process with motion of the carbomethoxy group and of the α process with chain motion. The results on polymethyl α‐chloroacrylate are unsatisfactory in the low temperature region. Anomalous behavior in the region of −100°C. may be due to a hitherto unnoticed solid state transition. The main line narrowing above 100°C. is correlated satisfactorily with the dielectric and mechanical properties of the material but the α and β processes then fall so close together that rather less detailed information is obtained than with polymethyl methacrylate. A comparison of the behavior of polymethyl methacrylate and polymethyl α‐chloroacrylate provide an interesting example of the way in which nuclear resonance measurements are valuable in the interpretation of the behavior of polymer materials.
Effect of drawing on the infrared dichroism of nylon 66 filaments
Authors: Caroti Gino , Dusenbury Joseph H.
Published: April 2003

Infrared absorption measurements in the 3‐micron region, using polarized radiation, have been made for a series of nylon 66 filaments, ranging in draw ratio from one (undrawn) to four. From consideration of the dichroic ratios obtained, it is suggested that there is a random arrangement of nylon 66 polymer chains at draw ratio one, with these chains becoming increasingly aligned with respect to the filament axis as the drawing increases. The method used to prepare a filament for infrared examination is particularly important, since it has been found that improper preparative procedures may induce orientation in a filament. This effect of specimen preparation is greatest at draw ratio one and becomes less important at higher draw ratios. The results of x‐ray diffraction studies carried out on the same series of filaments are consistent with the infrared findings.
An osmometer with an ideal semipermeable boundary
Authors: Pals D. T. F. , Staverman A. J.
Published: April 2003

An osmometer has been constructed in which the only possible transition from one cell to the other is through the vapor phase. In this way the problem of passage of solute is completely eliminated. In order to obtain a sufficient rate of transition of solvent, the distance between the cells has been made as small as possible. An osmometer with a vapor “membrane” of 0.05 mm. thickness is described and measurements with this osmometer are reported.
Fiber formation from concentrated polymer solutions and the possible origin of long‐range periodicity in synthetic fibers
Authors: Nishijima Yasunori , Oster Gerald
Published: April 2003

A theory of fiber formation from concentrated polymer solutions is presented which is based on the overlap of polymer molecules. The extent of overlapping is estimated from our diffusion measurements (J. Polymer Sci., 19, 337 (1956)). Above a certain concentration, which is lower the greater the size of the individual molecules, the polymer molecules lose their identity and the solution becomes a continuous network. Under these conditions the solution is spinnable and the structure of the network is independent of the molecular weight but depends on the flexibility of the chains. Calculations show that the drawn‐out network which forms the fiber has long‐range periodicity (100–500 A.) and is in agreement with the order of magnitude observed in smallangle x‐ray diffraction of synthetic fibers.
Light scattering by linear macromolecules oriented in laminar flow. II. Determination of the main gyration radii
Authors: Peterlin Anton
Published: April 2003

In laminar flow, polymer molecules are deformed and oriented. The effect is generally observed by investigating the resulting streaming birefringence. From the measurement of the magnitude of the effect, not only the optical anisotropy of the monomer unit, and its dependence on the solvent, but also the uncoiling of the linear macromolecule in the flow can be determined. From the extinction angle, information about the size and flexibility of the coil can be obtained. Since evaluation of the experimental data depends on the special model and on the statistics of the chain elements, an independent check is highly desireble. Light scattering yields such additional information on the size and shape of the deformed macromolecule, information which is less influenced by the special assumptions of the individual models. The pertinent scattering functions are calculated for the freely draining Gaussian coil and for the optically isotropic monomer unit, which in turn allows the determination of molecular parameters i.e., of the main gyration radii from the measurement of the angular dependence of the scattered light.
Effect of x‐rays and γ‐rays on synthetic polymers in aqueous solution
Authors: Alexander Peter , Charlesby Arthur
Published: April 2003

A study has been made of the effect of ionizing radiation (x‐ and γ‐rays) on aqueous solution of the following vinyl polymers: polymethacrylic acid, polyacrylic acid, polyacrylamide, polystyrene sulfonate, polyvinylpyrrolidone, and polyvinyl alcohol. In dilute solutions (<0.3% for the samples of polymer used) all the polymers are degraded by main chain fracture although in some cases dissolved oxygen has to be present. In others, degradation occurs in carefully deoxygenated solution but is increased by the presence of oxygen. The breakdown of polystyrene sulfonate is independent of oxygen. At higher concentration, crosslinking becomes the dominant action for all the polymers studied with the exception of polymethacrylic acid and ionized polyacrylic acid, which degrade at all concentrations. The dose of radiation necessary to produce a gel has been studied as a function of concentration and passes through a minimum. No gel formation occurs below a minimum polymer concentration of about 0.4%. The results cannot be explained on the basis that indirect action by the free radicals formed in the water leads to degradation while direct energy uptake by the polymer itself produces crosslinking. Other possible mechanisms are examined. The manner by which added substances reduce the effectiveness of irradiation (i.e., protect) is discussed briefly.
Mean square length and mean square radius of gyration of 1,4′‐polysaccharides and of polybutadienes
Authors: Eliezer I. , Hayman H. J. G.
Published: April 2003

The mean square length and mean square radius of gyration of 1,4′‐polysaccharides and of cis‐ and trans‐polybutadiene were calculated by an extension of the method of Eyring and Benoit, the results being expressed in terms of the degree of polymerization and of certain parameters of physical significance connected with the rotations about the various single bonds in these molecules. The calculations were based on the simplifying assumptions that no correlation exists between rotations about bonds separated by at least one pyranose ring or double bond and that the polysaccharide molecules are made up of pyranose rings in the “chair” form. The excluded volume effect was neglected throughout. The results obtained show that, if the mean square length is plotted against the degree of polymerization, n, then the deviations for small n from the limiting straight line obtained for larger n will have the form of a damped vibration, n appearing instead of the time. In certain cases, however, the results for odd and even n fall on different curves.
Light scattering of polyphosphates of high molecular weight
Authors: Saini Guido , Trossarelli Luigi
Published: April 2003

This paper reports light scattering and viscosity data concerning a fraction of lithium polyphosphate of high molecular weight (1.0 × 106) dissolved in LiCl solutions whose concentration varied from 0.025 to 0.4 M. The lithium polyphosphate was obtained by adding a cation exchanger (Dowex 50, lithium form) to an aqueous suspension of insoluble potassium Kurrol's salt. The higher fraction of the dissolved product was then precipitated by adding an alcoholic solution of LiCl. The root mean square end‐to‐end distance of the polyelectrolyte molecule, (r2), as obtained from the angular dependence of the scattered light, is as much greater as the ionic strength lowers. The Fox‐Flory relation can be applied in the above range of ionic strength. The second virial coefficient becomes zero at a ionic strength of about 0.4, and the ratio (r/M)1/2 = 1.24 × 10−8cm. shows that the molecule has a low flexibility. The dependence of the expansion coefficients and of the second virial coefficients on ionic strength is discussed, use being made of the theories concerning polyelectrolyte behavior.
Hydrolysis and optical rotation of cellulose, starch, and cycloglucans
Authors: Freudenberg K.
Published: April 2003

Under the title “Contributions to the Chemistry of High Molecular Natural Substances” (J. Polymer Sci., 16, 155 (1955)) a short survey of the author's work on cellulose, starch, catechintannins, and lignin is given. The present paper gives a detailed derivation of the kinetic and preparative evidence for the structure of cellulose, starch, and the Schardinger dextrins (cycloglucans).
Chromatographic fractionation of sugar beet araban
Authors: Goodban A. E. , Owens H. S.
Published: April 2003

Crude araban prepared from sugar beet pulp is not a pure araban, but yields appreciable amounts of galactose upon hydrolysis. In order to obtain galactose‐free araban this material was acetylated and fractionated by precipitation from acetone by the addition of petroleum ether. Arabinose content rose from 78 to 85%. Chromatographic fractionation on a charcoal column by elution with chloroform‐acetone mixtures resulted in an increase in purity from 89 to 95%. Optical rotation was the most sensitive indication of the progress of the fractionation, with the chromatographic fractionation resulting in a change from −102 to −124°. Specific viscosity measurements support the findings of Claesson that retention volume is related to molecular weight; the strength of adsorption increasing with molecular weight up to a maximum near a molecular weight of 10,000. Reported molecular weights for sugar beet araban have ranged from 5,700 to 10,000. An arabogalactan was found which is strongly adsorbed, and is not eluted by chloroform, but may be removed with pyridine. Total recovery from the column was 89%.
Action des pH acides sur la sérum albumine bovine en solution
Authors: Champagne M.
Published: April 2003

On a montré dans une publication précédente, que l'on pouvait définir un ellipsoïde équivalent à la molécule de sérum albumine en mesurant dans des conditions de pH et de forces ioniques définies: le coefficient de diffusion brownienne; la viscosité intrinsèque et la masse de la particule. Les mesures avaient été faites dans unintervalle de pH allant de 3,5 à 9. De forme sphérique au point isoionique, la molécule de sérum albumine s'allonge de part et d'autre et son volume diminue. Les modifications sont réversibles. Pour des pH inférieurs à 3,2 un trouble apparaît dans les solutions de sérum albumine. Nous avons pu l'identifier comme étant de nature lipidique. Nous avons précisé les conditions e'élimination totale de cette impureté. II est possible alors d'étudier les modifications subies par la sérum albumine à des pH très acides. Nous avons poussé l'étudej usqu'à pH 1,5 et montré en particulier que la reversibilité était encore totale à pH 1,97. Nous avons comparé parallèlement l'activité antigénique d'une sérum albumine portée à pH 2 et ramenée à pH neutre et celle de la sérum albumine native.
Viscometric investigation into the influence of pH and ionic strength on molecular shape of a structural muscle protein
Authors: Wassermann Albert
Published: April 2003

An attempt to explain some viscosity properties of actomyosin in terms of a reversible polymerization reaction cannot be reconciled with experimental results described in this paper. A consistent explanation of these experiments can be given if it is postulated that actomyosin, in dilute solution, is composed of flexible chains, the shape of which depends on pH and ionic strength of the solvent. The order of magnitude of the average distance between the chain ends of actomyosin molecules is estimated.
Dilatometric measurements on gels of cellulose tributyrate and cellulose nitrate
Authors: Vrancken M. N. , Ferry John D.
Published: April 2003

Glass transition temperatures (Tg) and thermal expansion coefficients (α) above and below Tg have been determined for gels of cellulose tributyrate in dimethyl phthalate (weight fraction polymer, w2, of 0.20 and 0.43) and of cellulose nitrate in diethyl phthalate (w2 = 0.12 to 0.37). Below Tg, α increases with w2; above Tg, α decreases with increasing w2. In the tributyrate (w2 = 0.43) a second transition appears, as noted by Mandelkern and Flory for the undiluted polymer. By combining the Tg values with the coefficients of the WLF equation, the quantities fg and αf are calculated for the tributyrate gels. Here fg, interpreted as the relative free volume at Tg, is about 0.020; while αf, interpreted as the expansion coefficient of free volume relative to the total volume, is 4.8 × 10−4 deg.−1, approximately equal to the macroscopic change in α at Tg.
Polymers and group interaction. V. Reaction of diazomethane on polymethacroyl chloride
Authors: Rondou S. , Smets G. , De Wilde‐Delvaux M. C.
Published: April 2003

In order to follow the course of the Arndt‐Eistert reaction on a polymeric system, polymethacryol chloride has been reacted with diazomethane in dioxane solution using different molar ratios of diazomethane/acid chloride at different temperatures. The structure of the reaction products has been determined by chemical methods and by infrared spectrometry. The contents of acid chloride and diazoketone units have been evaluated from chlorine and nitrogen analyses, respectively; conductometric and potentiometric titrations allow determination of the percentages of ketene and pseudo‐acid groups. From these data it is concluded that the first reaction products of diazomethane on an acid chloride unit are diazoketone groups, as expected; however, the interaction of these primary groups with the neighboring acid chloride units yields principally β‐ketocycloketene functions. The presence of these groups and their content have been confirmed by a decarboxylation reaction effected by hydrolysis in acidic medium, during which carbon dioxide is evolved, while the acid content decreases and cyclic ketones are formed. Their presence has also been confirmed by oxidation with dilute nitric acid, which transforms the polymer into polymethacrylic acid. These results of decarboxylation and of oxidation are unreconcilable with the formation of the higher homolog of polymethacrylic acid, the polyisopropenylacetic acid, which would be the normal chainlengthening reaction product of the Arndt‐Eistert reaction. Infrared spectrometry shows, in the triple bond region, absorption bands at 4.65 and 4.73 μ, and, in the double bond region, bands at 5.55, 5.70, 5.80, and 6.10 μ. By comparison with the data in the literature, and especially with the spectrum of the glutaric bisdiazoketone, these different bands have been assigned and their relative intensities interpreted. The spectrometric results confirm the presence of diazoketone and β‐ketoketene groups; moreover, they show relatively low amounts of cyclopentanone rings and of ester functions.
Anomalous behavior of polymer solutions. I. Non‐Newtonian behavior of polyvinyl acetate solutions
Authors: Kapur S. L. , Gundiah S.
Published: April 2003

The viscosity behavior of dilute solutions of polyvinyl acetate fractions in benzene has been investigated at different shear rates and at two temperatures. The importance of the effect of shear on the various physical constants has been discussed. It is shown that the value of Huggins' constant k′ at zero shear is independent of molecular weight for a given polymer and is a fundamental property associated with the inherent character of the polymer chains and their interaction with the solvent at a particular temperature.
A study of the rates of denaturation of arachin and conarachin II
Authors: Naismith W. E. F. , Williams R. K.
Published: April 2003

The rates of denaturation of arachin and conarachin II with sodium hydroxide and guanidine hydrochloride have been studied. Arachin is more susceptible to denaturation with both reagents. The rates of denaturation of the two proteins with sodium hydroxide or guanidine hydrochloride are decreased by increasing the sodium chloride concentration. Arachin is changed by both denaturants to slowly sedimenting material by way of an intermediate sedimenting component, but no intermediate component has been observed with conarachin II. Whereas the rate of alkaline denaturation of both proteins is very sensitive to temperature changes, with guanidine hydrochloride the rate is not affected appreciably by changes in temperature. This would indicate that an appreciable activation energy is required for the alkaline denaturation. Confirmation of this is seen in that the alkaline denaturation is always completely irreversible whereas with guanidine hydrochloride some reversibility has been observed. Although there was no increase in rate with increase in protein concentration for either protein, in no case did the plot of log concentration vs. time give the straight line graph expected of a reaction which is first order with respect to protein concentration.
Molecular orbital theory of reactivity in ionic polymerizations
Authors: Yonezawa T. , Higashimura T. , Katagiri K. , Hayashi K. , Okamura S. , Fukui K.
Published: April 2003

The stabilization energy due to the conjugation taking place between a monomer and an ion in the transition state is calculated by the LCAO perturbation theory, in the same way in which the reactivity in radical copolymerization has previously been treated. In terms of this stabilization energy, the reactivity ratios of several monomer pairs in ionic copolymerization are satisfactorily interpreted. It is noted that, by the present method, both the radical and ionic copolymerization can be treated in a unified manner, whereas it is difficult in existing empirical methods. The positions of attack in polymer ions as well as in monomers, which are predicted by the frontier electron densities, are shown to agree well with experimental facts. The relative reactivities of vinyl monomers in ionic homopolymerization is also explained successfully by the magnitude of the localization energy computed by the LCAO method.
A fundamental investigation of adhesion. II. Method for measuring shrinkage stress in restrained gelatin films
Authors: Weatherwax Richard C. , Coleman Beverly , Tarkow Harold
Published: April 2003

Gelatin solutions shrink as water evaporates from the gel. If the shrinkage is prevented, tensile stresses develop. A technique is described for measuring the tensile stress developing in the plane of edge‐clamped gelatin films during drying. It is based on measurement of the elastic deformation of the film when stressed normally to the plane of the film. A stress of 4000 pounds per square inch was observed in a dried gelatin film. The reality of the stress was confirmed in a completely independent manner.
Physicochemical studies on starches. VII. The infrared absorption spectrum of the amylose‐iodine complex
Authors: Greenwood C. T. , Rossotti Hazel
Published: April 2003

Changes in the infrared absorption spectrum of amylose on complex formation with iodine, bromine, and iodine cyanide vapor are consistent with the occurrence of halogen‐oxygen interaction in the solid complexes. The implications of these results are discussed in terms of the possible conformations of the glucopyranose rings and their relationships to the helical structure for amylose. It is suggested that the most probable conformation is a chair‐form in which only one substituent is axial to the plane of the ring.
The mechanism of protection by the deactivating effect
Authors: Bras Jean Le , Danjard Jean‐Claude , Boucher Madeleine
Published: April 2003

The mechanism of protection by the deactivating effect has been studied on the basis of data from continuous and discontinuous relaxation experiments on vulcanizates accelerated with mercaptobenzothiazol and with diphenylguanidine. It has been shown that the mechanism involves the formation of intermolecular crosslinks, which restore the damages due to the thermo‐oxidative ruptures in the vulcanizate network. These intermolecular crosslinks are formed by the free sulfur present in the vulcanizates under the influence of the deactivator, which acts as a slow accelerator, as has been proved by free sulfur determinations carried out during aging. The resistance of these crosslinks to the thermooxidative degradation is specific for the deactivator; this allows for interpretation of the more or less pronounced effect of the deactivator upon aging as a function of the nature of the accelerator used during vulcanization. This explanation of the deactivating mechanism gives not only a better understanding of the phenomena, but also presents new ideas for the general interpretation of aging of vulcanized rubber.
Non‐stationary state kinetic determination of polymer radical lifetimes
Authors: Funt B. Lionel , Collins Edward
Published: April 2003

Lifetimes of polymer radicals were determined by a direct flow technique. The variation of yield of polymer with the period between initiation by an ultraviolet source and destruction in an inhibitor solution was determined by spectrophotometric analysis. A swiftly falling stream of monomer was irradiated by a sharply focussed beam of intense ultraviolet radiation, and the time of radical growth was controlled by varying the distance of fall at a constant flow rate. The variation of yield of polymer with the time interval between photochemical initiation an destruction in an inhibitor solution was determined by spectrophotometric analysis of the polymer formed. A polished elliptical reflector was used, instead of the customary quartz lenses, with the source and stream at the foci of the ellipse. A water‐jacketed capillary was employed to eliminate spurious thermal initiation. Radical lifetimes of 0.24 seconds for styrene and 1.80 seconds for butyl acrylate were obtained. The data were compared with values calculated on the basis of non‐stationary state kinetics in a flow system.
Sulfostyrenes1. Reactivity ratios for the copolymerization of styrene with potassium p‐vinylbenzenesulfonate and with p‐sulfoamidostyrene
Authors: Wiley Richard H. , Trinler W. A.
Published: April 2003

Determination of the copolymerization reactivity ratios for the styrene/p‐sulfonamidostyrene and styrene/potassium p‐vinylbenzenesulfonate has given values of r1 = 0.24; r2 = 1.07 and r1 = 0; r2 = 0.56, respectively. Values for the salt copolymerizations are subject to considerable variations, presumably due to adsorption of the monomer on the precipitating copolymers. The significance of these data in determining the distribution of the ionic groups in copolymers derived from these monomer pairs is discussed.
Use of the second virial coefficient to estimate chain branching
Authors: Krigbaum W. R. , Trementozzi Q. A.
Published: April 2003

Branching frequencies have been determined by dilute solution measurements through evaluation of the radius of gyration, either directly by light scattering or indirectly through the intrinsic viscosity. A third possibility is presented by the decrease in the second virial coefficient, A2, with branching. Through use of a semi‐empirical relation between A2 and [η], it is shown that a reasonable approximation over a wide range of branching frequencies should be furnished by:

where the quantities designated by an asterisk refer to the branched polymer, and the corresponding unmarked quantities to a linear polymer having the same molecular weight. The validity of the approximate relation between A2 and branching is confirmed using the data of Thurmond and Zimm for linear and branched polystyrene, and using data for linear and branched polyethylene presented here. This procedure should prove useful inasmuch as the molecular weight of a branched polymer must be determined by an absolute method, and the branching frequency can be estimated through the A/A2 ratio from these same data.
Molekulargewichtsverteilungen in Polykondensaten aus 2.6‐dioxymethyl‐4‐methylphenol (Polyoxybenzyläthern). Osmotische Molekulargewichtsbestimmungen unter einem Molekulargewicht von 20000 mit einem modifizierten Heppschen Osmometer
Authors: Kämmerer H. , Kern W. , Heuser G.
Published: April 2003

2,6‐Dioxymethyl‐4‐methylphenol wird bei 130°C derart kondensiert, dass hierbei fast ausschliesslich Polyoxybenzyläther entstehen. Die Konstitution dieser Polyätherketten wird durch die quantitative Bestimmung der Spaltprodukte bei der Polykondensation und durch die Bromwerte der HBr‐Hydrolysate der Polykondensate bewiesen. Verhältnismässig hochmolekulare Polyoxybenzyläther lassen sich in Benzol als Losungs‐ und mit Petroläther als Fällungsmittel durch Fällringstitration in Fraktionen zerlegen, wobei jeder Fraktion eine Fällbarkeit γ* zugeordnet werden kann. Für diese Fraktionen gilt log M = a − b · γ* im Molekulargewichtsbereich von 2500 bis 20000. Die Molekulargewichte wurden mit einem Osmometer nach Owens und Immergut osmotisch twstimmt. Sind die Polyoxybenzyläther genügend hochmolekular, so können unter Vernachlässigen der Anteile mit Molekulargew‐icht unter 2500 (P = 17) integrale und differentielle Massenverteilungen ermittelt werden. Es lässt sich nicht eindeutig feststellen, ob oder wie stark die experimentell ermittelten von den statistischen Massenverteilungen abweichen.
Viscosités intrinseques de solutions de chaînes courtes
Authors: Sadron Charles , Rempp Paul
Published: April 2003

La relation entre la viscosité intrinsèque et la masse moléculaire de molécules à chaîne courte fait l'objet du présent travail. Une relation du type

rend compte des résultats expérimentaux dans le cas des polyoxyéthylhe glycols dans tout le domaine de masses moléculaires considéré. Par contre la viscosité intrinsèque des α,ω‐diméthoxy polyéthylèneglycols diffère de celle des polyoxyéthylène glycols correspondants de façon assez notable dans le domaine des masses moléculaires faibles. Le raccordement satisfaisant des courbes [η] = f(M) relatives aux deux séries de substances nous incite à admettre d'une façon générale, dans le domaine de masses moléculaires considéré, une loi de viscosité de la forme:

dans laquelle le premier terme est en rapport avec la nature chimique de la chaine et le deuxième résulte de ses configurations statistiques.
Branching in macromolecules of different synthetic rubbers
Authors: Poddubnyi I. Ya. , Ehrenburg E. G.
Published: April 2003

From results of a study of the intrinsic viscosity and the dynamooptical properties of homogeneous polymer fraction solutions, the influence of the polymerization temperature on the degree of branching in various synthetic rubbers was determined. The dynamooptical method proved to be the most suitable for our purpose. It was found that the influence of the polymerization temperature on the degree of branching of rubber macromolecules prepared in the presence of sodium, potassium, and lithium depends largely on the metal employed. With sodium‐butadiene rubbers, even a considerable change in the temperature of polymerization has little influence on the degree of branching of the macromolecules. On the other hand, when potassium is used as the catalyst, an increase in the polymerization temperature leads to a marked increase of the degree of branching. A considerable increase in the degree of branching was also observed in high‐temperature, lithium‐catalyzed polymerization. A relatively small effect of temperature on the degree of branching was observed in the case of butadiene‐styrene copolymers obtained by free radical‐initiated emulsion polymerization. The determination of the intrinsic viscosity of polymer fractions of various molecular weights in an ideal (Θ) solvent permits a quantitative evaluation of the degree of branching by applying Flory's equation, as modified for the case of branched polymers. Such an evaluation was made for three samples of lithium‐isoprene polymers. For two samples which were found to be branched, it was discovered that one branch unit occurs for every ∼4000 monomer units.
Conductance of partially neutralized polymethacrylic and polyacrylic acids, using a polarization compensated twin cell
Authors: Eisenberg H.
Published: April 2003

The a.c. conductance of partially neutralized fractions of polyacrylic and polymethacrylic acids has been investigated in salt‐free solutions. Experimental variables included frequency (10 to 50,000 cycles), nature of counterions (potassium, sodium, and lithium), molecular weight, degree of ionization, concentration, and temperature. The use of a polarization compensated twin cell arrangement in frequency dispersion measurements is described.
Donor‐acceptor interactions in cationic polymerization. II. Influence of some bases on polymerization of isobutylene
Authors: Ambrož L. , Zlámal Z.
Published: April 2003

Analysis of literature data permits the conclusion that a close link exists between cocatalytic effects and inhibition in cationic polymerization. All compounds described as efficient co‐catalysts of isobutene polymerization, e.g., water, alcohols, acetic and trichloroacetic acid, can have inhibiting effects under other conditions. All these compounds can be considered as weak bases able to form a catalytic complex on interaction with aluminum trichloride. It was found that the dependence of the molecular weight of polyisobutene on the ratio of the concentration of the organic base to that of the aluminum trichloride exhibits a clear maximum at the molar ratio of 1:1. A number of simple compounds containing oxygen, sulfur, and nitrogen were investigated, e.g., alcohols, ethers, esters, aldehydes, ketones, mercaptans, hydrogen sulfide, ammonia, amines, and nitriles. The results obtained indicate that co‐catalytic activity is not limited to compounds with “active” hydrogen. In the case of acetic and chloroacetic acids, anomalous behavior was found. This is explained by acid‐base equilibria between these acids and aluminum trichloride in ethyl chloride solution.
Mutual solubility of polymers and properties of their mixtures
Authors: Slonimskiĭ G. L.
Published: April 2003

Heats of mixing of polymers with each other have been measured, the behavior of the mixtures of solutions of various polymers has been studied, and the dependence of mechanical properties of polymer mixtures on the ratio of components has been investigated. It has been shown that mixing of polymers with each other is usually an endothermic process and, therefore, leads to formation of macroscopically homogenous, but actually microheterogenous, systems with an extremely high degree of dispersion. These microheterogenous polymer mixtures are formed because of the enormous viscosity of polymer mixtures, which prevents macroscopic separation into phases but does not hinder the considerable mobility of the segments of flexible chain molecules. It has been shown that the dependence of mechanical properties of microheterogenous polymer mixtures on the ratio of polymers in the mixture have sharp maxima or minima which cannot be found in the case of true polymers in polymer solutions. It has been found that the behavior of some polymer pairs is anomalous, in that exothermal mixing is supplemented by separation of the solution mixture into phases and by the appearance of maxima or minima in the dependences of the properties of polymer mixtures on the ratio of polymers in the mixture. This anomaly has been attributed to the effect of loose packing of the molecules of the polymers which show anomalous behavior. It has been shown that, in these systems, there necessarily exists a lower critical temperature of mixing whose value can be decreased by adding low‐molecular solvents to the loosely packed polymer. Attention has been drawn to the fact that, although mixing of amorphous polymers should be considered on a thermodynamic basis to be a mutual solution of two liquid phases, the large dimensions and the flexibility of polymer chain molecules require a critical revision of the possibility of formal application of the basis thermodynamic concepts and relations to a theoretical analysis of the behavior of polymer mixtures.
Synthese eines gegenüber Nickel selektiven Ionenaustauschers
Authors: Štamberg J. , Seidl J. , Rahm J.
Published: April 2003

Es wurde die Synthese eines gegenüber Nickel selektiven und 1,2‐Dioximgruppe als aktive Gruppe enthältenden Ionenaustauschers untersucht. Dieses Problem wurde schon früher von Kljatschko studiert, der die Darstellung eines Kunstharzionenaus‐tauschers durch die Einführung von Dimethylglyoxim in den Sulfo‐Resorcin‐Kationen austauscher im Stadium der Kondensation in kurzgefasster Form beschrieben hat. Bei der Anwendung seiner Methode wurde festgestellt, dass sie nicht zu positiven Resultaten führt. Dimethylglyoxim wird dabei aus dem Harze teilweise extrahiert, grösstenteils aber durch die Einwirkung von Formaldehyd zersetzt, und die komplexbildenden Eigenschaften eingebüsst werden. Die Elution von Dimethylglyoxim aus dem Harze kann durch die Einführung der 1,2‐Dioximgruppe in das Molekül beseitigt werden, das mit Formaldehyd in Polykondensation treten kann z. B. p, p′‐Dioxybenzildioxim; es wird dabei jedoch der destruktive Einfluss von Formaldehyd auf die Dioximgruppe nicht beseitigt. Eine andere Möglichkeit bietet eine geeignete Behandlung des Phenol‐Formaldehydharzes. So eignet sich z.B. für eine Nickelaufnahme das o‐2,3‐Dioximinobutylderivat des Resorcin‐Formaldehyd‐Harzes. Es besitzt jedoch eine geringe Stabilität, besonders bei erhöhten pH‐Werten. Harze mit erhöhter Beständigkeit wurden aus Polystyrol‐Harz hergestellt durch die aufeinander folgenden: Propionylierung, Nitrosierung und Oximierung. Das Studium über die Struktur des polymären Materials zeigte, dass die Einführung der Propionylgruppe p‐ständig verläuft, während in dem Styrolmonomeren die Propionylgruppe in die ω‐Stellung an der Seitenkette eintritt. Das Dioximderivat Polystyrols besitzt für Nickel eine Austauschkapazität von 2 meter/g und das Verfärben des Polymeren bei der Sorption entspricht dem Verfärben der niedermolekularen Dioxim–Nickel‐Komplexe. Die von linearen Polystyrol dargestellten Ionenaustauscher besassen nicht die erforderlichen mechanischen Eigenschaften; es wurden also Versuche ausgeführt mit einem Styrol‐Divinylbenzol Suspensionskopolymeren (0,3; 1.0% DVB). Es wurden dabei Bedingungen für das Erreichen des erforderten Umsetzungsgrades gefunden. Gegenwärtig wird der Einfluss von der Konzentration des primären Substituents auf die Reaktionsfähigkeit des Mischpolymerisats untersucht.
Lithium‐initiated copolymerization of styrene and methyl methacrylate. I
Authors: O'Driscoll K. F. , Boudreau R. J. , Tobolsky A. V.
Published: April 2003

The copolymerization of methyl methacrylate and styrene has been investigated using metallic lithium as an initiator. The unusual composition of the polymer produced does not permit description of lithium as either a classical ionic or radical initiator. A new concept must be adduced to explain the observed results.
Some special features of organic polymers containing phosphorus
Authors: Korshak V. V.
Published: April 2003

Results obtained in the investigation of polymers containing pentavalent phosphorus in the main polymer chain are presented. A number of polyamides and polyesters derived from phosphorus‐containing dicarboxylic acids have been synthesized. Two types of dicarboxylic acids were used: alkyl‐ or aryl‐phosphinic acids (I) and bis‐carboxyphenyl‐phosphine oxides (II):
magnified image
their chloroanhydrides or esters being used in the reaction. To obtain polyesters, various glycols or dihydric phenols were used as the second component. For preparing polyamides, aliphatic diamines were used as the second component. The nature of the starting materials has a very marked effect on the properties of the polymers obtained. Polyesters with an aliphatic chain are viscous, thick oils or low‐melting resins. Polyesters with aromatic unit are high‐melting, solid elastic substances. Comparison of the properties of the polymers synthesized by us with the properties of polymers of related composition not containing phosphorus, shows that the introduction of phosphorus into the chain leads to molecules of much greater flexibility. For this reason the softening points of the phosphorus‐containing polymers are much lower than those of their carbon analogues.
Amines and carboxylic acids as initiators of polymerization in caprolactam
Authors: Majury T. G.
Published: April 2003

Evidence is presented for the initiation of polymerization in caprolactam by two primary amines and two carboxylic acids, with rigorous precautions to exclude water from the systems. The kinetics of the reactions have been studied dilatometrically and all are shown to share two major features: (1) the plot of conversion vs. time is characteristically sigmoid in shape, and (2) the maximum slope of this plot tends to be proprtional to the square root of the initiator concentration. The rate data show that acids induce rather more rapid polymerization than bases. When combined with data in the literature on the polymerization induced by aminocaproic acid or water, they indicate that reaction of lactam at the amino and carboxyl groups accounts for an appreciable but minor proportion of the observed reaction rate; the remainder is presumably attributable to the mechanism of alternate hydrolysis of lactam and condensation of terminal amino and carboxyl groups. The explanation of the precise mechanism by which amines and acids induce polymerization offers some difficulty. A molecular ring‐addition mechanism fails to account for the square root concentration dependence mentioned above. The hypothesis of ring‐insertion at chain amide linkages is capable of yielding a suitable rate dependence but is shown to be invalidated by other evidence. A tentative suggestion of an ionic ring‐addition process is made which is consistent with the major kinetic characteristics of these reactions.
Ion exchange resins as catalysts in the decomposition of sarin
Authors: Chasanov Martin G. , Epstein Joseph
Published: April 2003

The hydrolysis rate of the nerve gas Sarin in aqueous solution may be accelerated by strongly acidic and strongly basic ion exchange resins. Basic resins are more effective than acid resins. Depending on the resin type and internal structure, a diffusional process or the chemical reaction may be rate determining. In distilled water, cationic resins behave as true catalysts, whereas the products of decomposition of Sarin destroy the effectiveness of anion resins. Dissolved salts in the water lower the useful life of both types of resins by replacement of the active hydrogen or hydroxyl groups.
The kinetics of the heterogeneous hydrolysis of poly(vinyl formate) and of poly(vinyl formate‐co‐stearate)
Authors: Jordan Edmund F. , Port William S.
Published: April 2003

The rate of hydrolysis of formate and stearate segments from poly(vinyl formate) and from poly(vinyl formate‐co‐stearate) suspended in dilute aqueous hydrochloric acid was studied. Evidence was presented to show that the hydrolysis follows pseudo‐first‐order kinetics. The Arrhenius constants and the entropies and free energies of activation for the hydrolysis of formate and stearate groups from copolymers containing 0, 3, 5, and 10 mole‐% vinyl stearate were calculated from the partially reduced reaction rate constants at three temperatures. For the hydrolysis of formate segments, ΔS‡ is markedly affected by the stearate content, whereas the variation in ΔF‡ is small. Variations in vinyl formate content have smaller effects on the thermodynamic constants of the activated complex for the hydrolysis of the stearate segments. At approximately 95°C., some anomalous kinetic behavior was observed.
Tests on the hydrolysis of certain synthetic polymers
Authors: Bevington J. C. , Eaves D. E. , Vale R. L.
Published: April 2003

Polymers of methyl methacrylate, methyl acrylate, vinyl acetate, and acrylonitrile labeled with carbon‐14 in the functional groups have been prepared. The labeled polymers have been subjected to hydrolysis, and the specific activities before and after treatment have been compared. Almost complete hydrolysis of polymethyl acrylate and polyvinyl alcohol is readily achieved. It has been confirmed that polymethyl methacrylate is rather resistant to hydrolysis, but ester endgroups in this polymer are easily detached. During treatment of polyacrylonitrile with acid or alkali, no carbon atoms are lost from the polymer.
The molecular weight of polyacrylonitrile
Authors: Krigbaum W. R. , Kotliar A. M.
Published: April 2003

There is a surprising lack of agreement between the values which have been reported for both the number‐average and weight‐average molecular weights of polyacrylonitrile. We have undertaken an investigation of both whole polymers and polymer fractions to discover and eliminate the sources of systematic error which would lead to these differences, and thereby to develop procedures yielding reliable molecular weight values for this polymer. Our experience indicates that the procedure which must be followed to obtain reliable osmotic data depends upon the conditions under which the polymer was prepared, whether the sample is a whole polymer or a fraction, and the purity of the solvent. Designating solution polymers by S and those prepared in an aqueous system with a persulfate‐bisulfite initiator by A, we conclude that reliable M̄n values can be obtained for S polymers by using dimethylformaide (DMF) which has been purified by deionization or distillation, for fractions of A polymers by using deionized DMF, and for whole A polymers by performing the measurements upon DMF solutions which have been deionized by passage through a column of Amberlite MB‐3 resin. Fictitiously low M̄n values are observed for A polymers dissolved in distilled DMF. The value of the secon virial coefficient is very ensitive to the presence of traces of water. Turning to weight‐average molecular weights, a 60% discrepancy exists between the values obtained from light scattering by Stockmayer and Casassa and by Bisschops from sedimentationdiffusion. We believe the correct M̄w values lie midway between these. A part of the 60% difference is due to the omission of a correction to the sedimentation data for the effect of hydrostatic pressure. This correction was evaluated from sedimentation data by the procedure of Oth and Desreux and increases the molecular weight values deduced from sedimentation by 30%. The remainder of the difference appears to be due to the effects of depolarization and fluorescence upon the light scattering data. Thus, our data for two fractions which exhibited a limiting depolarization ρu = 0.09 yielded high M̄w values standing in agreement with the relation of Stockmayer and Casassa, while the result obtained for a whole polymer having a negligible limiting depolarization agrees with those obtained from the corrected sedimentation data. The latter polymer also exhibited a more normal scattering behavior. A comparison of the weight and number‐average values indicates that the M̄w/M̄n ratio is 2.1 ± 0.1 for the whole S polymers and 2.8 ± 0.3 for the whole A polymers. The broader distribution in the latter case suggests that termination occurs by both coupling and disproportionation in the aqueous polymerization.