bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of allyl compounds. IV. Emulsion polymerization of allyl acetate
Authors: Bartlett Paul D. , Nozaki Kenzie 
Published: April 2003

AbstractThe emulsion polymerization of allyl acetate yields a polymer of the same average molecular weight as is obtained in bulk polymerization. The decomposition of potassimn persulfate is of the first order but is greatly accelerated by the presence of allyl acetate or of ethyl acetate. Three independent methods of analysis agree in indicating the presence of sulfate groups in 75% of the polymer molecules. It is concluded that the mechanisms of chain initiation and termination are analogous to those in the peroxide‐induced bulk polymerization of allyl acetate. These facts do not serve to distinguish between different postulated loci reaction in emulsion polymerization.
Note on volume effect in coiling molecules
Authors: Simha Robert 
Published: April 2003

AbstractAn estimate of the magnitude of the interference effect in a coil‐like molecule is made by calculating the nearest neighbor density w around a given link as a function of the total number of contributing chain units. It is shown, for instance, that in a chain consisting of several hundred units, the first fifteen contribute about 75 % of the total nearest neighbor density at distances below the length of a link. The plots presented indicate that after about the first twenty links, the rate of increase of nearest neighbor density begins to flatten off. It is also possible to derive the modification of the distribution function of chain ends in real chains for a given form of w.
n‐Octyl mercaptan as modifier for emulsion polymerization at high temperature
Authors: Marvel C. S. , Lewis C. D. 
Published: April 2003

Abstractn‐Octyl mercaptan has been found to be a better modifier for emulsion copolymerization of butadiene and styrene at 110° than is either n‐butyl mercaptan or n‐dodecyl mercaptan. Physical test data on vulcanized copolymers modified with n‐octyl mercaptan are presented.
Density of undrawn, drawn, and annealed nylon filaments
Authors: Black C. E. , Dole Malcolm 
Published: April 2003

AbstractThe densities of undrawn and drawn nylon filaments (6‐6 Nylon) are found to be 1.1339 and 1.1384, respectively, at 25°C. Annealing either the drawn or undrawn forms to the highest temperature possible short of melting increases the room temperature density to 1.1564, the most rapid increase in density with temperatures annealing coming at 210°C. The temperature coefficient of the density as measured at room temperature is greater for the drawn form of the nylon than the undrawn after annealing has taken place. The density of nylon calculated by Bunn and Garner from x‐ray diagram data is 1.24, considerably higher than the highest value obtained by us on annealing, namely 1.156.
Die kinetik des celluloseabbaus und die langperiodische struktur des cellulosemoleküls
Authors: Schulz G. V. 
Published: April 2003

AbstractEine Übersicht wird gegeben für die Argumente, die für das Vorhandensein eines regelmässigen, langperiodischen Aufbaus von Einheiten von 500 Glukoseresten in Fasercellulosen sprechen. Die Uneinheitlichkeit des Gewichtsdurchschnittes kann in ihrer Abhängigkeit vom Abbaugrad gemessen werden und nimmt viel langsamer ab als unter der Annahme von statistischer Spaltung. Die Interpretierung der kinetischen Studien mit Hilfe der Gleichung von Ekenstam führt zu zwei verschiedenen Geschwindigkeitskonstanten und Aktivierungsenergien für die Zerfallsreaktion. Schliesslich zeigen elektronenmikroskopische Aufnahmen charakteristische Unterschiede zwischen Fasern die durch Nassmahlung und durch Hydrolyse gewonnen wurden.
Calcul de l'écart quadratique moyen entre les extrémités de diverses chaînes moléculaires de type usuel
Authors: Benoit H. 
Published: April 2003

AbstractLe calcul de l'écart quadratique moyen entre les extrémités d'une chaîne moléculaire a été fait de façon complète dans le cas de la chaîne aliphatique à rotations libres. Des solutions partielles ont été proposées dans le cas de la chaîne aliphatique avec empěchements stériques ou intéractions entre les chaînons. Le but du présent travail est de donner une méthode de calcul général que l'on applique aux exemples particuliers les plus usuels. (Chaînes aliphatiques, cellulosiques, polypeptidiques ainsi qu'aux substances type caoutchouc naturel.)
Anionic redox activation of butadiene‐styrene copolymerization
Authors: Johnson Paul H. , Bebb R. L. 
Published: April 2003

AbstractA redox‐activated emulsion polymerization system has been developed in which benzoyl peroxide, sorbose and ferrous ammonium sulfate constitute the oxidation reduction system. Very rapid rates of reaction were obtained which permitted the use of lower polymerization temperatures. Redox polymers made at 10°C. had higher molecular weights and superior physical properties compared to standard GR‐S as well as to polymers prepared in the redox system at higher temperatures.
Combination of potassium ferricyanide, diazothio ether and mercaptan as “catalyst” for emulsion polymerizations of butadiene and styrene
Authors: Kolthoff I. M. , Dale W. J. 
Published: April 2003

AbstractThe combination of a diazothio ether and a mercaptan in an emulsion copolymerization recipe of butadiene and styrene containing potassium ferricyanide as a “catalyst” has a very strong activating effect on the polymerization. p‐Methoxyphenyl diazothio‐(2‐naphthyl) ether, designated as MDN, was found to be particularly suitable. In the present paper, ordinary household soap (S.F. flakes) and dehydrogenated rosin soaps of varying degrees of purity have been used as emulsifiers. By using various tertiary or primary mercaptans, polymers of any degree of modification were obtained. The recommended recipe at 40°C. gives about 80% conversion in 10 hours. The rate of conversion is greatly increased by adding to the recipe substances which have a strongly alkaline reaction in water, as sodium carbonate, trisodium phosphate, or sodium hydroxide. With such “alkaline” recipes attractive rates of conversion are obtained at around 0°C.
Carbonatotetramminocobaltic nitrate activation of butadiene‐styrene emulsion copolymerization
Authors: Deanin Rudolph , Lindsay Rex D. , Leventer Seymour E. 
Published: April 2003

AbstractRapid low‐temperature butadiene‐styrene emulsion copolymerization may be effected by a redox‐activated system composed of carbonatotetramminocobaltic nitrate and dodecyl mercaptan. This system reaches 75% conversion of monomer to polymer in 0.8 hour at 50°C., 2.8 hours at 30°C., or 27 hours at 0°C., and is thus about fifteen times as fast as standard recipes now in use. The modifying effect of dodecyl mercaptan improves as the polymerization temperature is lowered, producing loosely cross‐linked polymers at 30°C. and well‐modified polymers at 0°C.
Nitrostyrenes. I. Polymerization of m‐nitrostyrene
Authors: Wiley Richard H. , Smith Newton R. 
Published: April 2003

Abstractm‐Nitrostyrene, prepared from m‐nitrocinnamic acid in 60% yields, has been converted to polymers of low molecular weight in bulk and in solution with benzoyl peroxide, boron fluoride, and aluminum chloride initiators, and in aqueous emulsion with persulfate initiator.
X‐ray studies of low‐temperature polybutadiene and butadiene‐styrene copolymers
Authors: Beu Karl E. , Reynolds W. B. , Fryling C. F. , McMurry H. L. 
Published: April 2003

AbstractThe fine structures of emulsion polybutadiene prepared at temperatures ranging from 55°C. to −20°C. and of various butadiene‐styrene copolymers prepared at −20°C. have been studied by x‐ray methods. The ability of emulsion‐polymerized butadiene to crystallize was found to depend to a large extent on the temperature of polymerization. Butadiene polymerized at 30°C. and above showed no evidences of crystallization when cooled unstretched to −70°C. as observed by x‐ray diffraction methods; however, butadiene polymerized at 20°C. and below showed crystallization effects when cooled unstretched to −70°C. These crystallization effects became more pronounced for samples polymerized at lower temperatures. Layer‐line diffraction patterns of butadiene polymerized at 30°C. and below were obtained by stretching the polymer at about 0°C. From these patterns the geometrical repeat distance along the polymer chains was found to be 5.1 ± 0.1 Å. This corresponds to a fully extended butadiene unit in the trans configuration. An anomaly was observed in the diffraction patterns of crystallizable polybutadiene stretched at 0°C. Some of the layer‐line spots varied in position with per cent elongation of the sample. This suggests that the molecules in crystallites of the polymer are inclined to the stretch axis at low elongations and that they become more nearly parallel to the stretch axis at higher elongations. A small addition of styrene as comonomer at −20°C. polymerization temperature did not prevent crystallization and preferred orientation effects in the polymer, since these effects could still be found in a 90/10 charge copolymer. Larger amounts of styrene did prevent crystallinity and preferred orientation as shown by the amorphous nature of an 80/20 charge copolymer. The ability of a compounded vulcanizate of a given polymer to crystallize is less than that of the purified polymer under the same conditions. This may be due to the combined effects of milling, vulcanization, and the presence of carbon black particles in the polymer. A description of the apparatus and techniques used for cooling and stretching these polymers is given.
Potentiometric titration of viscose
Authors: Herrent P. , Jnoff G. 
Published: April 2003

AbstractA new method is investigated to determine by means of potentiometric titration the degree of ripening of viscose. It is found that when the e.m.f. of a characteristic inflection in the potentiometric titration curve is plotted against a measure of the degree of viscose ripening a sharp minimum occurs at a point corresponding to the optimal degree of ripening. Moreover, evidence is offered to indicate the formation of sodium dithiocarbonate in viscose during ripening. This last fact leads to a reasonable postulation of the complete scheme of reactions taking place in a ripening viscose.
Beiträge zur kinetik der indenpolymerisation. V. Reaktionskinetik der indenvulkanisation
Authors: Halla F. , Schützner W. 
Published: April 2003

AbstractEs wird gezeigt, dass die Reaktion von Indol mit Schwefel zu einem Polymer führt, das ein Schwefelatom pro Indoleinheit enthält. Der Brechungsindex und das Absorptionsspektrum des Polymers werden mitgeteilt. Die Kinetik der Schwefelreaktion, mit und ohne Zusatz von Beschleunigern, wird untersucht um den Einfluss der Beschleuniger auf die Reaktiongeschwindigkeit und die Temperaturabhängigkeit der Reaktion festzustellen.
Refractometric determination of second‐order transition temperatures in polymers. III. Acrylates and methacrylates
Authors: Wiley Richard H. , Brauer G. M. 
Published: April 2003

AbstractA refractometric technique for determination of second‐order transition temperatures (Tm) of polymers has been extended to include a series of alkyl acrylate and methacrylate polymers with transitions at temperatures down to −50°C. A convenient technique for determining refractive index down to −75°C. is described. Certain long‐chain alkyl polymers are birefringent below Tm. Correlations of brittle point with Tm and relations between viscosity and Tm are reported.
Elastoviscous properties of polyisobutylene. I. Relaxation of stress in whole polymer of different molecular weights at elevated temperatures
Authors: Andrews R. D. , Hofman‐Bang N. , Tobolsky A. V. 
Published: April 2003

AbstractThe relaxation of stress in polyisobutylene whole polymer of different average molecular weights has been investigated over the temperature range 30–100°C., and at different elongations. The shape of the relaxation curve is independent of elongation in a range of low elongations; above this range there is a gradual change in curve shape with increasing elongation. The shape of the relaxation curve for a given molecular weight is the same at different temperatures, when plotted as reduced stress vs. logarithmic time; a change in temperature essentially shifts the position of the curve along the logarithmic time scale. The activation energy for relaxation, calculated by use of the Arrhenius equation, is found to be independent of molecular weight in the molecular weight range investigated (M̄v = 665,00.0 to 1,420,000), the average value being 15.4 kcal. Straight lines are obtained when reciprocal viscosity‐average molecular weight is plotted against log time required for the reduced stress to reach a certain arbitrary value, at a fixed temperature and elongation. Relaxation rate depends on molecular weight with sufficient sensitivity so that relaxation measurements may be a practical method of measuring molecular weight directly in the solid state.
Action of regulators in polymerization of monomers containing allyl and methacrylate groups
Authors: Cohen Saul G. , Sparrow Donald B. 
Published: April 2003

AbstractThe peroxide‐initiated polymerization of allyl methacrylate has been examined in the presence of certain additives. By the use of mercaptans and diisopropyl dixanthogen the extent of polymerization at the point where gelation occurs may be extended from about 6% to 20–30% polymerization. Examination of samples of polyallyl methacrylate, polymethyl methacrylate, and the copolymer of methyl methacrylate and allyl chloroacetate indicates that the postponement of gelation results largely from diminution of the molecular weight by the regulators. The effects of regulators on the composition of copolymers and the molecular weight of polymers, and the relation between molecular weight and extent of reaction at the gel point are discussed.
Cross linking of nitrocellulose studied with the ultracentrifuge and consistometer
Authors: Jullander Ingvar , Blom‐Sallin Brita‐Stina 
Published: April 2003

AbstractExperiments with cross linking of nitrocellulose in butyl acetate solution by means of titanium tetrachloride are described. The gels have been examined by means of sedimentation in the ultracentrifuge and measurements with a consistometer. The yield value of the flow curves and the extent of cross linking were studied as functions of nitrocellulose concentration, amount of cross‐linking substance, and time of reaction.
Occurrence of head‐to‐head arrangements of structural units in polyvinyl alcohol
Authors: Flory Paul J. , Leutner Fred S. 
Published: April 2003

AbstractPolyvinyl alcohol prepared by hydrolyzing polymerized vinyl acetate is partially degraded within a few minutes by reagents known to attack 1,2‐glycol structures. The degree of degradation is limited, however, the final molecular weights of the degraded products being in the range of 3700 to 6500 (viscosity averages). The extent of degradation seems to depend solely on the temperature at which the vinyl acetate was polymerized. Mole percentages (based on the structural unit CH2CHOH) of 1,2‐glycol structures, corresponding to head‐to‐head unit arrangements, have been computed from the degree of degradation with periodic acid. They increase from about 1.23% for polymerization at 25°C. to 1.95% at 110°C. The occurrence of head‐to‐head structures is attributed to occasional “abnormal” addition of monomer in the chain‐growth phase of the polymerization. The activation energy for the abnormal addition reaction is 1250 calories higher than for the normal (preferred) addition; the steric factor for the abnormal addition is about one‐tenth that for the normal addition.
Copolymerization. VI. Mechanism of emulsion polymerization
Authors: Fordyce R. G. , Ham G. E. 
Published: April 2003

AbstractAdditional data relating to the mechanism of the emulsion copolymerization of styrene and copolymerization of styrene and acrylonitrile are presented. These results show the influence of varying the emulsifier and of varying the water–monomer ratio upon the relationship between monomer composition and the composition of the initial copolymer molecules formed. The composition of the initial copolymer produced in emulsion is the same as that which would be predicted if polymerization occurred in the oil droplet.
Application of infrared analysis to elucidate the mechanism of the boron trifluoride catalyzed vapor phase polymerization of isobutene at room temperature
Authors: Dainton F. S. , Sutherland G. B. B. M. 
Published: April 2003

AbstractMeasurement of the infrared absorption spectrum of the lowmolecular liquid polymer formed at room temperature from gaseous isobutene using BF3 as a catalyst and D2O as a cocatalyst indicates that the dominant end groups in the final polymer are (CH3)3C and , and that the cocatalyst D2O undergoes partial conversation to H2O during reaction. These results substantiate the mechanism advanced by Polanyi and others, namely: (a) initiation through formation of the trimethyl carbonium ion by acceptance by isobutene of a proton (or deuteron) from the catalyst‐cocatalyst complex, and (b) termination by explusion of a proton from a methyl group to the anionic complex fragment, with corresponding catalyst regeneration, i.e.:

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Photochemistry of proteins. V. Effect of pH and urea on ultraviolet light inactivation of crystalline pepsin
Authors: McLaren A. D. , Pearson Sidney 
Published: April 2003

AbstractQuantum yields for the inactivation of crystalline swine pepsin have been determined as a function of pH at 2537 A. The quantum yield is near a minimum at pH 4.08, at which point a value of 0.0019 was found, rises rapidly above pH 6, and shows a slight maximum near pH 2.7. The maximum is more pronounced with polychromatic light. The quantum yield (at pH 2.01) was found to be the same with either hemoglobin or casein as a substrate. Urea had no effect on the quantum yield although urea alone, 7 M, inactivates pepsin at an appreciable rate. Urea and light denaturation do not modify the absorption spectrum of pepsin in the same way. The data of Gates has been recalculated; it shows an increase of quantum yields with decreasing wave length. It has been concluded, from experiments with model substances, that inactivation can occur by the absorption of a quantum by any aromatic group in pepsin.
Degree of lateral order in various rayons as deduced from x‐ray measurements
Authors: Hermans P. H. 
Published: April 2003

AbstractX‐ray measurements on 16 different specimens of regenerated cellulose reveals that there exists a pronounced negative correlation between the integrated intensity of the 101 interference and its halfwidth. The 101 plane is a preferred cleavage plane and represents the lamellar plane of the ribbon‐shaped crystallites. Variations in the intensity of the other interferences are much less or nonexistent. These results show that the degree and the perfection of lateral order according to the 101 and 002 planes is little at variance, but that order according to the 101 plane is extremely variable in such a way that if the average thickness and (or) perfection of the lamellae increases, the total number of well‐ordered 101 plane contacts diminishes. As a possible explanation of this phenomenon it is suggested that various degrees of recrystallization with reference to this particular plane (i.e., various degrees of lateral order) may be associated with the various rayon specimens. This, however, does not necessarily imply differences in the total amount of ordered substance. This explanation is corroborated by the fact that cellulose acetate fibers which were previously allowed to “recrystallize” by heating in methanol, after saponification yield a rayon with a particularly sharp, but also particularly weak, 101 interference, without exhibiting a higher total percentage of ordered substance than the saponification products of acetate treated in this manner.
Preparation and properties of rubberlike high polymers. VI. Polymerization and dimerization of isoprene
Authors: Salomon G. , Boonstra B. B. S. T. , van der Meer S. , Ultée A. J. 
Published: April 2003

AbstractThe inhibitor and initiator action of 33 compounds on the bulk polymerization of pure isoprene has been studied. Picric acid was found to be the most powerful inhibitor at 100°C. The conclusion reached in Part I, that the initiator activity of diazoaminobenzene is superior to all other compounds has been found to be valid also between 100–150°C. The heat polymerization of isoprene between 100–150°C. in the presence of picric acid leads only to the formation of dimers. Three of the four possible isomers have been separated. The solid complex compound of diprene (I) with silver nitrate has been used to separate it from dipentene (II) and the hydrocarbon of Lebedew (III, IV) has been identified as a monochloride. The relative yields (I): (II): (III+IV) = 16:1:2 are in agreement with the relative availability and localization of π‐electrons in isoprene. Observations on the properties of polyisoprene are in agreement with the more extensive work by d'Ianni. Some remarks on polymers from bulk polymerization are added. Isoprene acts as a powerful inhibitor on the polymerization of vinylidene chloride. This effect is independent of the method of polymerization.
Investigations on cellulose nitrate. II. Liquid and vapor phase adsorption of acetone
Authors: Campbell H. , Johnson P. 
Published: April 2003

AbstractThe discrepancies in the published work on the interaction of acetone and cellulose nitrate are discussed and explained. Vapor phase adsorption isotherms for the adsorption of acetone by cellulose nitrate have been determined with an adsorption balance. They have been shown to be independent of the crystalline‐amorphous ratio of the polymer but dependent upon its nitrogen content. In cellulose nitrates which are completely soluble in acetone, no limiting adsorption has been found. Adsorption analysis (a modification of chromatography) has been applied to the determination of the liquid phase adsorption by cellulose nitrate of acetone from mixtures with petroleum ether. In terms of the liquid mixture concentrations, there appears to be limited adsorption, but this is shown to be due to the nonideal nature of the solutions of acetone and petroleum ether. When allowance is made for this, the liquid and vapor phase isotherms are the same within experimental error and do not support the existence of compounds of acetone and cellulose nitrate.
Polymerization in a system of discrete particles
Authors: Haward R. N. 
Published: April 2003

AbstractIt has been shown that subdivision of certain homogeneous polymerizing systems into droplets of diameter 10−4 to 10−5 cm. will entail a probability of finding only one active chain in each particle if the kinetics of the reaction remained otherwise unaffected. Some cases of polymerization in compartmentalized systems have been considered, and it has been shown that, where active centers are generated singly within completely isolated drops, the effect of increasing subdivision would be to increase the rate of reaction and chain length. On the other hand, with the formation of active chains in pairs, the opposite effect is to be anticipated, namely a decreasing rate of reaction with increasing subdivision. These conclusions are briefly considered in relation to the problem of dispersion polymerization, and it is shown that the theory of compartmentalization could account for the occurrence of high rates of reaction and chain lengths in the emulsion process, as compared with a bulk system. On the other hand, there is no evidence showing that the reaction rate is ever reduced in finely dispersed systems.
Polydispersité de la cellulose de la pâte de bois
Authors: Herrent P. , Govaerts R. 
Published: April 2003

AbstractNous avons étudié une méthode pratique et simple, dont les résultats soient parfaitement reproductibles, de détermination de la répartition des longueurs de chaînes de la cellulose provenant de pâtes de bois différentes. Cette méthode nous permettra de mieux comprendre l'influence des différents facteurs de fabrication sur les qualités mécaniques de nos produits finis.