bluuebunny/crossref_metadata_2025 huggingface dataset:
Polythene fine structure
Authors: Bryant W. M. D.
Published: April 2003

Part I traces fine structural features of polythene, beginning with the arrangement of carbon atoms disclosed by x‐ray diffraction, and including the incorporation of crystalline segments into crystallites, and finally the combination of crystallites and amorphous regions to form spherulites–the largest structural elements of polythene. Attention is called to the frequent occurrence of side chains in the molecules. The structures of spherulitic and cold‐drawn polythenes are compared. Part II describes an experimental study of the cold‐drawing of polythene which discloses an interesting variant of this process, designated as “redrawing,” in which dimensional changes differ greatly from those of ordinary cold‐drawing. On the basis of these observations and structural considerations presented in Part I, a mechanism of cold‐drawing as a rheological process is outlined.
Molecular structure of cellulose and starch
Authors: Pacsu Eugene
Published: April 2003

From the results of initial acid‐catalyzed hydrolysis of cellulose, and from certain data in the literature it is concluded that (1) native cellulose possesses an indefinitely high molecular weight; (2) as a consequence of common procedure adhered to by most investigators, native cellulose is unintentionally degraded to about DP 3000; (3) mild, initial acidic degradation, intentional or accidental, causes further decrease in the DP values down to the probable limiting value of 128 or 256, with complete loss of the tensile strength of the cellulose fiber; and (4) the few covalent bonds (about 0.3%) which become cleaved during these mild reactions are equally spaced, acid‐sensitive, and entirely different from the regular 1,4‐glycosidic bonds which are responsible for the random hydrolysis of cellulose in strongly acidic media. It is suggested that these acid‐sensitive linkages represent hemiacetal or acetal bonds which originate from openchain glucose anhydride residues of “limit hydrocellulose” units and connect the latter along the a and b axes of the fiber. The length of the “limit hydrocellulose” is supposed to correspond to that of 27 = 128 glucose anhydride residues—that is, 660 Å., or twice these figures. Extension of this concept to starch leads to the postulate of a three‐dimensional network of glucose anhydride units of indefinite number. The latter are held together by regular 1,4‐α‐glucopyranosidic bonds and, at short intervals, probably by acetal bonds of open‐chain glucose anhydride residues. On mild, acid‐catalyzed hy‐drolysis these acid‐sensitive linkages rupture rapidly and completely, giving rise to a material which consists of linear molecules only, containing 1,4‐, 1,6‐, and possibly 1,3‐, glycosidic bonds between two adjacent glucose anhydride residues.
Ethanol—toluene–water as solvent mixture for extraction of nonpolymer from GR‐S
Authors: Kolthoff I. M. , Carr C. W. , Carr Betty J.
Published: April 2003

A solvent prepared by mixing 70 parts by volume of ethanol, 30 parts of toluene, and 10 parts of water is found to be a suitable solvent for the extraction of organic nonrubber material from GR‐S. The presence of the water has no effect on the rate of extraction of the nonrubber, while it reduces the extractibility of low molecular polymer to one‐tenth of that found in the absence of water in the solvent. A procedure is described for the determination of small amounts of GR‐S in the extracts. This procedure is based on the quantitative precipitation of the ICl addition product of the rubber from a chloroform solution by addition of ethanol. A routine procedure for the determination of the amount of rubber in GR‐S is given.
Preparation and properties of rubberlike high polymers. V. Influence of nitrile groups on the properties of copolymers
Authors: Salomon G.
Published: April 2003

Physical and mechanical properties of copolymers from dienes and acrylic nitrile have been studied. The gradual increase of density is an indication of the strong intermolecular forces exerted by nitrile groups. The mutual interaction of nitrile groups and methyl groups leads to a reduction of the mobility of flow units. This can be deduced from a relative comparison of hardness, elastic recovery, stress–strain properties, and brittle point of the three polymer‐homologous series.
Mercaptan structure and regulator activity in emulsion polymerizations
Authors: Frank Robert L. , Smith Paul V. , Woodward Fred E. , Reynolds William B. , Canterino Peter J.
Published: April 2003

Five twelve‐carbon mercaptans of definite structure are prepared and used to demonstrate that the rate of diffusion of mercaptan regulators in emulsion polymerization varies inversely with the length of the longest straight chain of the mercaptan structure (including the sulfur). In a given class of mercaptans (primary, secondary, or tertiary) the mercaptan consumption during polymerization varies directly with the diffusion rate. Solution viscosities of the resulting polymers are in accord with these findings.
Mercaptan derivatives as modifiers in the copolymerization of butadiene and styrene
Authors: Frank Robert L. , Drake Stevens S. , Smith Paul V. , Stevens Calvin
Published: April 2003

It has been demonstrated that the homogeneity in respect to molecular weight of emulsion copolymers of butadiene and styrene can be increased by the use of certain derivatives of n‐dodecyl mercaptan rather than the mercaptan itself. These derivatives decompose and relase n‐dodecyl mercaptan at an even rate during the polymerization reaction. Several new derivatives of n‐dodecyl mercaptan are described.
Determination of unsaturation of synthetic and natural rubbers by means of iodine monochloride
Authors: Lee T. S. , Kolthoff I. M. , Mairs Mary Anne
Published: April 2003

Precise analytical methods are developed using iodine monochloride for the determination of unsaturation in polybutadiene and polyisoprene and their copolymers with styrene. The complicating side reactions, splitting out and substitution, as well as the influence of the solvent employed are investigated in detail. It is concluded that GR‐S at various conversions has the theoretical unsaturation. Emulsion polybutadiene exhibits 97 to 98% of the theoretical unsaturation, emulsion polyisoprene 97% sodium polybutadiene 92%, and sodium polyisoprene 85%. The amount of unsaturation in these last two polymers as well as in the sodium copolymer of butadiene and styrene (75:25) is considerable less than theoretically expected.
Polymeric amides from omega‐amino acids
Authors: Coffman D. D. , Cox N. L. , Martin E. L. , Mochel W. E. , Van Natta F. J.
Published: April 2003

Methods for the preparation of fiber‐forming polymeric amides from ω‐amino acids and The variation in melting points of the polymeric their amide‐forming derivatives are described. The variation in melting points of the polymeric amides with increasing chain length of the recurring unit is discussed.
Influence of structure on polymer–liquid interaction. II. Influence of nitrile groups
Authors: Salomon G.
Published: April 2003

The swelling of vulcanized copolymers from dienes and acrylonitrile is measured in various organic liquids. Equilibria change gradually as a function of nitrile concentration. The occurrence of ideal, regular and irregular systems is discussed, and intermolecular attraction is interpreted in terms of Langmuir's theory of independent surface action.
Plasticizers for rubbers and resins
Authors: Stickney Palmer B. , Cheyney LaVerne E.
Published: April 2003

The mechanism of plasticizer action has been discussed for linear, slightly and highly crosslinked polymers. The important factors considered are the flexibility of the polymer chain, the polar interaction of groups along the chain, the masking of these interactions by plasticizer molecules, and the importance of the relative shape of polymer unit and plasticizer in the effectiveness of separating the chains. For nonpolar polymers, without secondary valence cross links, the plasticization is largely an entropy effect since no secondary valence bonds are broken or formed.
Experimental study of copolymerization. III. Copolymerization behavior of polychloroethylenes
Authors: Alfrey Turner , Greenberg Sidney
Published: April 2003

Experimental results are reported for the copolymerization of cis‐ and trans‐dichloroethylenes and trichloroethylene with vinyl acetate and styrene. Unsymmetrical as well as symmetrical 1,2 polysubstituted ethylenes exhibit extremely small rate constants for self‐propagation, but are easily attacked by vinyl‐type radicals such as that formed by vinyl acetate. The attack of such monomers by vinyl “growing chain” radicals is retarded by substitution on the attacked carbon atom, but is favored by substitution on the other carbon atom of the double bond.
Spherulite formation in polyhexamethylene adipamide
Authors: Langkammerer C. M. , Catlin W. E.
Published: April 2003

Solid polyhexamethylene adipamide prepared by slow cooling of a melt is opaque as a result of formation of spherulites. Spherulites may also be formed by slow evaporation of a phenol solution of polyhexamethylene adipamide. Transparent, nonspherulitic polymer of a low degree of lateral order can be formed by cooling the polymer rapidly. Heat treatment or aging of this polymer increases the lateral order without the formation of microscopically visible spherulites. Spherulites usually reduce tensile strength, increase opacity, and decrease workability.
Beitrage zur kinetik der indenpolymerisation. I. Thermische polymerisation von inden
Authors: Schmid H. , Gutmann V.
Published: April 2003

Die Geschwindigkeitskonstante der thermischen Polymerisation von Inden bei 150° und 175° in Abwesenheit von Sauerstoff wird zu 6.0 × 10−6 und 3.16 × 10−5 min.−1 resp., bestimmt. Der durchschnittliche mittlere Polymerisationsgrad war etwas geringer als 4 bei beiden Versuchstemperaturen.
Reduction activation of emulsion copolymerization of butadiene and styrene. II. Different organic peroxides and reducing activators in presence and absence of metals
Authors: Marvel C. S. , Deanin Rudolph , Kuhn Beryl M. , Landes Gloria Brock
Published: April 2003

The effect of different peroxides as catalysts and different polyhydroxy compounds as reducing activators both in the presence and absence of metals in a standard emulsion copolymerization of butadiene and styrene has been determined. The results of this study further emphasize the importance of a careful balance of all ingredients in any reduction‐activation system.
Polymeric phosphonitrilic esters: A new type of inorganic‐organic plastics
Authors: Goldschmidt F. , Dishon B.
Published: April 2003

The attempt to replace chlorine in polyphosphonitrilic chloride with alkoxyl groups is successful except that oxygen rather than alkoxyl substitution occurs to some extent. The amount of oxygen substitution and the extent of degradation are minimized if the polyphosphonitrilic chloride is swollen prior to alcoholysis. The substituted product is insoluble until treated with boiling tetrachloroethane. The final products, the esters, are very tacky when pure but can be incorporated with other polymers to give desirable products.
Chain transfer in copolymerization reactions
Authors: Alfrey Turner , Hardy Victor
Published: April 2003

An expression for the amount of chain transfer occurring in a copolymerization carried out in solvent media can be derived in a manner similar to the composition‐kinetic treatment for tripolymer formation. As a result, the relative reactivity of the chain‐transfer solvent can be determined.
Diacyl peroxides as polymerization initiators: Rate of polymerization of styrene in relation to rate of decomposition of four organic peroxides
Authors: Redington Louis E.
Published: April 2003

The rates of decomposition of benzoyl, lauroyl, bis(p‐chlorobenzoyl), and bis(2,4‐dichlorobenzoyl) peroxides, 0.0133 molar in styrene, have been determined at 34.8, 49.4, 61.0, 74.8, and 100°C., and the corresponding rates of polymerization of styrene have also been determined. Assuming the initial rate of polymerization of styrene, produced by benzoyl peroxide at an initial concentration of 0.0133 m./l. at each of the five temperatures used to be unity, the relative initial rates of polymerization produced by the peroxides studied are as follows: bis(2,4‐dichlorobenzoyl) 2.15, lauroyl 1.52, and bis(p‐chlorobenzoyl) 0.87. The rate data have been subjected to an approximate kinetic analysis, from which one may conclude that the order of intrinsic effectiveness of the peroxides as chain‐initiating agents in styrene is benzoyl > bis(p‐chlorobenzoyl) > lauroyl > bis(2,4‐dichlorobenzoyl), and that the effectiveness increases with increasing temperature. The activation energy for the peroxide‐initiated polymerization of styrene was found to be 21 kcal. per mole. The molecular weight of polystyrene appears to be an inverse function of the temperature, the polymerization rate, the peroxide decomposition rate, and the extent of wasteful decomposition of the peroxide.
Constitution of the side chains of lignin
Authors: Wacek A. v. , Kratzl K.
Published: April 2003

The evidence for the nature of the side chains in lignin resulting from investigations of the reactions of model substances has been summarized. The studies have involved investigation of the reactions with (a) sulfite, (b) alkali and nitrobenzene, and (c) hot alkali.

Reaction with sulfite occurs readily for model substances with β‐hydroxyl or α,β unsaturated keto groupings (“aldol type”). Hydroxyl groups adjacent to a ring are somewhat reactive but or‐hydroxyketo groupings (“acyloin type”) do not react.

Alkaline oxidation to aldehyde or carboxyl with nitrobenzene is effective in degrading a side chain para to a free hydroxyl group having an oxygen atom on the α‐carbon atom. Conversion of the para‐phenolic hydroxyl to a methyl ether neutralizes its promoting influence.

Cleavage to an aldehyde with hot alkali in the absence of air is specific for the “aldol type” grouping in the side chain. This is regarded as a reverse aldol condensation and it has been demonstrated that acetaldehyde can be isolated from such degradations.

These results, together with the behavior of lignin and its derivatives, are interpreted in terms of probable structures for the side‐chain units in lignin.
Transport and equilibrium phenomena in gas–elastomer systems. I. Kinetic phenomena
Authors: Barrer R. M. , Skirrow G.
Published: April 2003

The influence has been studied of systematic alterations in the amount of cross linking in elastomers upon diffusion coefficients and permeability constants in elastomers of homologous paraffin hydrocarbons. In a number of such media the influence of chain length of the paraffins upon the transport phenomena has also been investigated, using CH4, C2H6, C2H4, C3H8, and n‐C4H10.

Apparent activation energies for permeation (Ep) and for diffusion (ED) for degrees of vulcanization up to 11.3% combined sulfur are in the decreasing order:

For low vulcanizates, EP is not very sensitive to the per cent sulfur. However for higher percentages of sulfur, EP tends to rise, especially when the migrating molecule is a large one. ED is rather more sensitive both to molecular size and to per cent combined sulfur.

Both EP and ED for natural rubber vulcanizates show definite temperature coefficients, manifested as curvature when log10 D or log 10 P is plotted against 1/T. Such curvature was absent, however, in butyl rubber.

The results have been interpreted in terms of the molecular nature of elastic networks and in terms of the kinetic‐statistical (zone) theory and the transitionstate theory. All treatments indicate the need for a considerable zone of activation for each unit diffusion process, confirming an earlier investigation. When, in the Arrhenius equation, D = D0e, one plots log10D0 against ED/T, the clear functional relationship:

emerges. A simple interpretation of this and of similar functional relationships for other “activated” physical and chemical rate processes has been given.
Denaturation of plant proteins. I
Authors: Jirgensons B.
Published: April 2003

By denaturation of potato albumin by pyridine or by heat the viscosity increases; simultaneously the capability of the denatured protein t o reduce iodine increases, which, according to Anson, is due to the liberation of SH groups. A similar increase of viscosity was observed by the conversion of legumin into a water‐soluble modification, and further by heating the solution of this protein; the volume of iodine required for oxidation of the denatured protein is greater than that of the native legumin. This denatured protein can be reconverted into its native state, whereupon the reducing capacity again decreases. Several fractions of green pen and horse bean legumin were denatured by urea and it was found that the viscosity and the reducing capacity thereby increase. In the case of legumelin the viscosity is low but the reducing power high; this indicates that legumelin is a degradation product having globular molecules.
Beiträge zur kinetik der indenpolymerisation. VII. Die beschleunigung der indenpolymerisation durch die oxypolymeren des indens
Authors: Gutmann V.
Published: April 2003

Polymere Oxydationsprodukte des Indens verhalten sich in Bezug auf Polymerisationsreaktionen wie typische Peroxyde. Ihre verhältnismässig hohe Stabilität bedingt eine relative geringe Reaktionsbeschleunigung, wobei Bruchstücke des zerfallenden Peroxyds in die polymere Molekel eintreten.
Adhesion of high polymers to cellulose. Influence of structure, polarity, and tack temperature
Authors: McLaren A. D.
Published: April 2003

It has been demonstrated that the adhesion of high polymers to cellulose is a function of tack temperatures and dielectric constants, ϵ, of the polymers and of dipole moments, μ, of polar groups. A plot of tack temperature versus mirror image force, μ1μ2/,of copolymers gives an area of adhesion bounded by a tack temperature of 100% and mirror image forces of 0.7 and 1.3 and opening toward lower tack temperatures. Outside of the area polymers do not adhere well to cellulose. By coating polymers on cellulose pretreated with Werner chromium complexes of acids bearing polar groups, it has been found that adhesion is a specific function of the polar groups within the polymer and on the modilied cellulose. Adhesion is strongest with approximately equal dipole moment substituents on the modified cellulose and in the copolymers.
Refractometric determination of second‐order transition temperatures in polymers. IV. Butadiene‐acrylonitrile copolymers
Authors: Wiley Richard H. , Brauer G. M.
Published: April 2003

The second‐order transition temperatures (Tm) for foruteen commercially available butadiene‐acrylonitrile copolymers with 18–50% acrylonitrile have been determined refractometrically and found to be somewhat lower than the corresponding brittle temperatrues (Tb). The data show a linear relation between Tm and acrylonitrile content.
Depolarization of light scattered from dilute macromolecular solutions. II. Experimental results
Authors: Doty Paul , Stein S. J.
Published: April 2003

Depolarization measurements on solutions of polystyrene, polyvinyl chloride, polyvinyl acetate, polvdieblorostyrene, and tobacco mosaic virus have been made in order to examine various aspects of the qualitative theory proposed in the foregoing paper. In the case of the polymers the variation Of Ph and p, with concentration and solvent ability have been verified. The value of P, for tobacco mosaic virus is quite small as expected, and the value of ph for different virus preparations increases with decreasing molecular length as predicted.
Temperature dependence of copolymerization
Authors: Goldfinger G. , Steidlitz M.
Published: April 2003

Copolymerization rate constant ratios have been determined as a function of temperature for the monomer pairs: styrene‐acrylonitrile and dichlorostyrene‐acrylonitrile. The temperature dependence, which represents the difference of the activation energies of the respective addition reactions, is of the magnitude expected, except for the styrene‐dichlorostyrene system.
Relation of intrinsic viscosity of polymer solutions to degree of polymerization and temperature
Authors: Sadron Charles
Published: April 2003

The fundamental basis of our work is the application of statistics involving both the energy of interaction between solute and solvent molecules and the effect of steric hindrances: the statistics of freely rotating chains (sometimes called the statistics of Kuhn) are a special limiting case. Using this we can show that in the law [η] = KNα the coefficient is a function of N having a value close to 2 for small values of N, and approaching on first approximation a value of 0.5 when N increases infinitely. This statistical method has the advantage of permitting an approach to the important problem of the variation of the intrinsic viscosity as a function of the temperature T. The behavior of intrinsic viscosity with degree of polymerization and temperature as predicted by the theory check with experiment, and, in the case of the hemipolystyrenes, it has been possible to obtain very satisfactory quantitative verification. In view of numerous experiments which show that, at a given temperature, the limiting value of α for very large N is greater than 0.5, we have altered the theory of the equivalent particle accordingly. As a basis for the change the concept of porosity is examined with several other concepts, and it is shown that it is likely to apply only with reservations when the molecular structure of the solvent is taken into account.
La vitesse de propagation des ultra‐sons dans les macromolecules
Authors: Natta G. , Baccaredda M.
Published: April 2003

Il est montré que le rapport entre la vitesse de propagation des ultra‐sons et la densité (u/p) des polymères est fonction de la forme des molécules. En particulier on trouve: (1) dans les composés à chaîne rigide paraffinique non ramifiée, ce rapport à la température de 20° s'accroît sensiblement avec le poids moléculaire de 1.67 pour les hydrocarbures du poids moléculaire bas à 1.92 pour le polythène à poids moléculaire élevé; (2) dans les composés ramifiés ayant des groupes méthyliques ou éthyliques, ce rapport est pratiquement constant pour tous les composés examinés jusqu'au poids moléculaire 15.000; (3) dans les composés linéaires contenants des groupes latéraux de dimensions plus grandes (p.e., phényliques ou oxybutyliques), ce rapport est plus petit pour les hauts polymères que pour les composés à poids moléculaire bas; (4) en général la compressibilité est plus élevé pour les polymères avec des ramifications fréquentes et longues que pour les polymères peu ou pas du tout ramifiés.
Titration potentiometrique de la viscose. II
Authors: Herrent P. , Jnoff G.
Published: April 2003

En cherchant à interpréter la courbe expérimentale de la titration potentiométrique de la viscose par l'AgNO3, 0.1 N, on a découvert que les composés sulfurés de la viscose devaient se trouver sous la forme “ortho.” Ceci a permis de proposer une nouvelle théorie du mürissement de la viscose.
Thermal degradation of polystyrene. Part I
Authors: Jellinek H. H. G.
Published: April 2003

The decrease of the limiting viscosities of unfractionated and fractionated polystyrene with time has been studied over a range of temperatures from 248 to 340°C. in vacuo. Distribution curves of several degraded samples have been determined. It has been established that the theory of random breaking of links is not applicable in the case of polystyrene. Three major deviations from the random theory have been found. The experimental results have been evaluated employing the weak link theory. The mechanisms proposed account satisfactorily for the deviations from the random theory, and give a fair representation of the experimental results, only the experimental distribution curves still showing deviations from those predicted by theory. The elementary steps for the degradation in vacuo have been discussed and the role of oxygen during polymerization has been indicated.
Thermal degradation of polystyrene and polyethylene. Part III
Authors: Jellinek H. H. G.
Published: April 2003

An apparatus has been constructed which enables one to follow continuously the formation of monomer during degradation in vacuum. Experimental results are presented on the degradation of fractionated and unfractionated polystyrene over a range of temperatures from 340–400°C. in vacuum. A mechanism has been proposed which accounts satisfactorily for the apparent zero‐order reaction and for the dependence of the rate of degradation on chain length. This mechanism allows one to estimate relative number average molecular weights and the number of weak points per original chain. The influence of a platinum surface on degradation has been indicated. The degradation of poly‐alpha‐methylstyrene has been investigated over a range of temperatures from 281 to 363°C. in vacuum. The mechanism of the degradation of branched polymer chains has been discussed. The degradation of cross‐linked polystyrene containing various amount of m‐divinylbenzene has been studied at 364°C. in vacuum. The reaction shows long induction periods depending on the amount of m‐divinylbenzene and on the presence of benzoyl peroxide during polymerization. The degradation of polyethylene shows this polymer to be more heat resistant than polystyrene. Various grades of different average molecular weight have been investigated over a range of temperatures from 375 to 436°C. in vacuum. The energy of activation has been found dependent on chain length. A mechanism has been suggested to account for the observed experimental results.
Polyelectrolytes. IV. Conductance of n‐butyl bromide addition compounds of 4‐vinylpyridine‐styrene copolymers in nitromethane‐dioxane mixtures
Authors: Cathers George I. , Fuoss Raymond M.
Published: April 2003

The conductance of a series of salts made by the addition of n‐butyl bromide to 4‐vinylpyridine‐styrene copolymers (1.5 to 90 mole per cent vinylpyridine) has been measured in dioxane (ϵ′ = 2.2), ethylene dichloride (ϵ′ = 10.2), and a series of nitromethane‐dioxane mixtures (16.0 ≤ ϵ′ ≤ 39.4). Three independent arguments deduced from the data show that ionic association under the influence of interionic electrostatic forces must occur in solutions of polyelectrolytes in such a way that a certain average fraction of the counter ions accompany the large polycation and contribute nothing to conductance. First, the conductance at fixed copolymer composition and fixed salt concentration decreases with decreasing dielectric constant of the solvent medium. Second, at a given counter ion concentration in a given solvent, the conductance decreases with increasing pyridonium content of the chain. Third, for a given salt and solvent, the conductance decreases with increasing salt concentration at a rate much slower than that characteristic of simple electrolytes.
Ionic polymerization of mono‐olefinic hydrocarbons at low temperatures. A review of proposed mechanisms
Authors: Heiligmann Randall G.
Published: April 2003

The mechanism presented constitute proposals made in attempts to portray the role that electrophilic halides play in catalyzing the polymerization of unsaturated hydrocarbons. All of these halides require the presence of a Friedel‐Crafts catalyst in the reaction mixture and differ primarily in the interpretation of what constitutes the active factor in the initiation, propagation, and cessation steps. Mechanisms involving a thermal activation and dehydrohalogenation are discussed briefly and rejected as rather improbable. On the other hand, mechanisms involving a cationoid complex intermediate and a carbonium ion are extensively reviewed, especially in light of the recent findings of British investigators regarding the function of the so‐called third component or cocatalyst. Attention is called to the rather marked specificity of reactions involving water or other polar cocatalysts, and, in addition, it is pointed out that, although cocatalysts appear to be necessary prerequisities for activation in a number of cases, the phenomenon is not a general one, since systems exist in which proton‐supplying cocatalysts have not been proved necessary to initiate growth. To date, no single mechanism seems to satisfy all of the qualitative observations and known data. It is intended that the present discussion summarize available facts in terms of possible mechanisms, and, in addition, evaluate their plausibility in the light of present knowledge.
Copolymers of 1,3‐butadiene and 2,3‐dimethyl‐1,3‐butadiene
Authors: Marvel C. S. , Williams Jack L. R.
Published: April 2003

Some experiments on the polymerization of 2,3‐dimethyl‐1,3‐butadiene and its copolymerization with butadiene are reported. This monomer requires very little modifier as compared to butadiene.
Osmometry of high polymer solutions. I. Osmometer and membranes
Authors: Masson C. R. , Melville H. W.
Published: April 2003

The construction of a thermostated osmometer of the Fuoss‐Mead pattern is described. The technique of preparation of bacterial cellulose membranes for osmotic measurements on high polymer systems is given. The permeability of such membranes may be controlled by growth to a thickness of 4‐5 mm., drying in contact with a stainless steel surface, and reswelling in water or alcohol‐water mixtures. The degree of reswelling required to give membranes suitable for use with polymers of a range of molecular weights is given. The factors affecting the behaviour of the membranes in the osmometer are discussed.
Osmometry of high polymer solutions. II. Osmotic measurements using bacterial cellulose membranes
Authors: Masson C. R. , Melville H. W.
Published: April 2003

Bacterial cellulose membranes have been used successfully to measure the osmotic pressures of a number of high polymer‐solvent systems. The dynamic method of Fuoss and Mead has been used in most cases, but for polyvinylxylene in benzene the rate curves are not symmetrical since the solvent passes through the membrane faster from the solution side. The molecular weight values for two polyvinyl acetates agree well with the calculated kinetic values, and for polyethyl sebacate the value obtained agrees with that found by endgroup titration. Values of the Huggins “constant” μ are given for various systems.
Dependence of tensile strength of vulcanized rubber on degree of cross‐linking
Authors: Flory Paul J. , Rabjohn Norman , Shaffer Marcia C.
Published: April 2003

Tensile strengths of natural rubber samples quantitatively crosslinked with decamethylene dis‐methyl azodicarboxylate have been determined. The proportion of the azo vulcanizing agent was varied 80‐fold, the fraction p of cross‐linked units in the products ranging from 0.10x 10−2 to 8.0 x 10−2. In spite of the small dimensions of the test specimen (cross section 0.10 in. by about 0.005 in.), the average error for a single observation is similar to that obtained in conventional testing procedures applied to specimens vulcanized with sulfur and accelerators. Deviations from the mean for 262 tests on 15 different cures are well represented by a Gaussian error function; a slight intimation of skewness is evident only at the extremities of the distribution of deviations. These results are incompatible with the commonly held view that rupture of the sample takes place at the “weakest link” in the series of flaws inevitably occurring along the specimen. It would appear that the ability to withstand tensile stress (applied in a specified manner) is an inherent characteristic of the bulk material. The rapid increase in tensile strength with the degree of crosslinking p for small values of this quantity is consistent with the conclusion, previously reached in the investigation of the physical properties of butyl rubber (6) that the tensile strength is directly related to the fraction of the structure which is permanently oriented by stretching. At higher degrees of cross‐linking (at ρ x 100 = 1.0 to 1.5, depending on the molecular weight of the rubber) the tensile strength passes through a maximum and then declines steadily to quite low values for higher ρ's. This adverse effect of higher degrees of cross‐linking is believed to result from the diminished elongation at which crystallization sets in and, hence, the smaller fraction of the network elements sufficiently oriented to participate in crystallite formation. Modification of up to 7% of the isoprene units of the rubber with the monofunctional compound, ethyl azodicarboxylate, depresses the tensile strength of the disazo vulcanized rubber relatively little. Evidently, the limited extent to which these modified (or copolymer) chains may enter into crystallization is adequate to bring about high tensile strength. Lack of direct correlation between modulus and tensile strength for rubbers vulcanized with various sulfur‐accelerator combinations can only be explained by assuming that conventional vulcanization processes are accompanied to varying degrees by chain scission reactions. When vulcanized rubber is “over‐cured,” or heat aged, chain scission becomes excessive.
Denaturation of plant proteins. II. Increase of viscosity and reducing capability (estimated by titration with iodine) associated with denaturation
Authors: Jirgensons B.
Published: April 2003

Legumin of green peas and horse beans was dissolved in solutions of several salts and the viscosity and reducing capability of these solutions was determined. The amounts of iodine required for titration (reducing capability) are dependent on the pH of the solution and on the temperature; between pH 5.0 to 5.8 and +5° to +25° the titration values are almost constant. By comparing several neutral salts it was found that in the cases of sodium chloride, potassium bromide, potassium iodide, calcium chloride and magnesium nitrate the reducing capability and intrinsic viscosity of legumin both are low; however, in the case of potassium thiocyanate both values are high. No denaturation takes place in solutions containing 2‐30% ethyl‐ or propylic alcohol and calcium chloride or like salts. Sodium salicylate causes denaturation; the intrinsic viscosity and reducing capability of legumin in these solutions is high. Sodium dodecylbenzene sulfonate has a strong peptizing action on legumin and denaturates it. After a mild deamination of legumin with nitrous acid only slight differences in viscosity and reducing capability could be observed. The solutions containing much propylic alcohol and salt grew in time more and more viscous, if the concentration of legumin was high, but remained of the same viscosity when the concentration of legumin was low. It was concluded that in these cases the high viscosity of legumin is due not to unfolding of the compact coils of native legumin, but to the interaction of the particles with the molecules of the solvent and to subsequent structuration. Loosening and transformation in more elongated particles may be assumed in the cases with thiocyanate, salicylate, and the detergent.
Copolymerization. VII. Relative rates of addition of various monomers in copolymerization
Authors: Chapin Earl C. , Ham George E. , Mills Charles L.
Published: April 2003

Information concerning monomer reactivity in copolymerization has been obtained for thirteen copolymerization systems. The influence of substituents and chain length in vinyl polymerization is discussed in the light of this and preceding data. Unsaturated acid behavior in copolymerizations is discussed for the first time.
Reactivity of fibrous cellulose
Authors: Meller Alexander
Published: April 2003

By applying hydrochloric acid solution at different temperatures to various fibrous cellulose samples and following the per cent loss in weight with time, hydrolysis‐time curves have been obtained. These plots have been resolved into a straight line and a curve, representing the rate of removal of difficultly and easily removable components, respectively. Under the experimental conditions applied, the ratedetermining reaction in the removal of the difficultly accessible components from the fibers is essentially a kinetically zero‐order reaction. This was borne out by the results of hydrolyses of hydrocellulose preparations. Within the experimental range the temperature coefficient of this rate is independent of the representative fibrous materials and is relatively high, corresponding to an energy of activation of 28‐29 kcal./mol. The easily and difficultly accessible regions, assessed by resolving the rate plots, are different with the same fibers, depending on the experimental conditions. The reactivity of both the easily and difficultly hydrolyzable constituents varies with different cellulose fibers. The complex nature of the kinetics of removal (hydrolysis) of the easily accessible components is discussed.
Copolymérisation de l'Anhydride Maléique avec Différents Monomères Vinyliques
Authors: De Wilde M. C. , Smets G.
Published: April 2003

Die Mischpolymerisation von Maleinsaeure Anydrid mit verschiedenen Vinyl‐Verbindungen wie Methakrylsaeure, Methylester, Vinylchlorid, Vinylazetat und Isopropenylazetat wurde untersucht. Die Verhaeltnisse der Geschwindigkeits‐Konstanten r1 und r2 wurden fuer jeden dieser Faelle festgestellt. Die Mischpolymerisation mit Monomeren, die eine elektronreiche Doppelverbindung enthalten, zeichnet sich durch eine hohe Selektivitaet aus. In diesen Faellen koennen die Ergebnisse nicht gaenzlich durch das Alfrey‐Price Schema erklaert werden.
Untersuchung einer katalysierten leinölstandölkochung unter heranziehung der ultraviolettspektrographie (vergleich mit nichtkatalysierten prozessen)
Authors: Maschka A. , Mendl A.
Published: April 2003

(1) Laboratoriumsmässige Leinölstandölkochungen mit und ohne Katalysator in Kohlensäureatmosphäre, sowie eine Leinölfirnis‐ und eine Leinölstandölfirniskochung werden untersucht. (2) Neben den üblichen Kennzahlen werden auch die Ultraviolettabsorptionsspektren der einzelnen Proben ermittelt und daraus die Mengen der intermediär auftretenden Systeme mit zweifach und dreifach konjugierten Doppelbindungen berechnet. (3) Diese Zwischenstoffkonzentrationskurven und die übrigen Kennzahlen stimmen für die beiden Standölkochungen und einen in der Literatur beschriebenen technischen Prozess qualitativ überein. Naturgemäss verläuft der katalysierte Vorgang viel rascher. (4) Aus den Ergebnissen wird der Schluss gezogen, dass die in der Literatur als wahrscheinlich hingestellte Reaktionsfolge (Konjugation der isolierten Doppelbindungen—intra—bzw. intermolekulare Polymerisation im Sinne einer Diensynthese nach Diels–Alder) auch beim katalysierten Prozess auftritt. Der Katalysator beschleunigt alle Teilreaktionen. (5) Es wird der Versuch gemacht, aus der Zunahme der Viskosität und der Jodzahlsenkung die Bedeutung der Umesterung für die Viskositäts (Molekulargewichts) zunahme abzuleiten.
Optische anisotropie und form von fadenmolekülen. I. Depolarisationsgrad der lichtzerstreuung von lösungen mit fadenmolekülen
Authors: Stuart H. A. , Peterlin A.
Published: April 2003

Es wird der Depolarisationsgrad bei der molekularen Lichtzerstreuung von statistisch geknickten Fadenmolekülen in Abhängigkeit vom Polymerisationsgrade berechnet und die Giiltigkeitsgrenzen der Theorie näher diskutiert.
Titration potentiométrique de la viscose. III
Authors: Herrent P. , Jnoff G.
Published: April 2003

En combinant différentes méthodes d'analyse courantes à notre méthode de titration potentiométrique, nous avons pu tracer la courbe individuelle de la variation de la teneur de chacun des éléments constitutifs d'une viscose en fonction de la durée du mǔrissement de la viscose.
Tetramethylthiuram disulfide vulcanization of extracted rubber. IV. Behavior of rubber as an acid
Authors: Craig David , Juve A. E. , Davidson W. L.
Published: April 2003

(1) The reaction of rubber with zinc palmitate was found to liberate palmitic acid at low pressures, thus revealing that rubber is acidic. (2) The reaction of zinc oxide with palmitic acid in toluene solution was enhanced by the presence of water. (3) The small increase in the nitrogen content of rubber caused by its reaction with TMTD was equivalent to the palmitic acid liberated by the zinc palmitate reaction. (4) The use of TMTD as a reagent for organic acids has been studied and found to convert carboxyl groups into dimethylamide groups. This result suggests that the acidic nature of rubber is due to carboxyl groups in the rubber molecule, a suggestion which is compatible with the nearly complete removal of zinc from the TMTD vulcanizate by the zinc removal technique.
Preparation of cyclized rubber from natural rubber latex
Authors: Van Veersen G. J.
Published: April 2003

In this paper a new method for the preparation of cyclized rubber from natural rubber latex is described. In this method, which follows logically from the new way of preparing rubber hydrochloride from natural rubber latex, latex stabilized with nonionic or cationic emulsifying agents is mixed with sulfuric acid. If a sufficient amount of sulfuric acid is added, cyclized rubber is formed after some heating. The influence of sulfuric acid concentration and the temperature on the rate of reaction have been investigated. Other cyclizing agents proved to be hydrogen fluoride and boron trifluoride. The advantage of the method described is that cyclized rubber can be obtained in the form of a latex.
Some aspects of depolymerization kinetics
Authors: Simha Robert , Wall L. A.
Published: April 2003

A brief discussion of the importance of the transfer step and its effect in the pyrolysis of polyethylene is given. In this case the removal, by molecular distillation, of smaller species from the reacting mixture modifies the kinetics. The molecular weight decreases less rapidly and tends to a limiting value depending on the maximum size of the evaporating molecules. The number distribution of the latter is, in a first approximation, independent of their size. The pertinent expressions are presented and the general solution of the rate equations which can be used to obtain higher approximations is given.
New oxidants for initiation of emulsion polymerization in antifreeze recipes at −10°C.
Authors: Fryling Charles F. , Follett Archie E.
Published: April 2003

The introduction of the Dioxes as oxidants in emulsion polymerizations at subfreezing temperatures has opened up new horizons especially in the direction of the utilization of commercially available rosin acid soaps in formulations containing low iron concentrations. It is now possible to copolymerize butadiene and styrene to 60% conversion in 16 hours in an emulsion recipe containing only 0.3 millimole of iron per 100 g. of monomers with Diox* D, Dresinate 214, and potassium soap flakes; formerly it had been impossible to reach such a conversion within 24 hours. By the use of mixed potassium laurate‐ myristate emulsifier and Diox 7, a conversion of 60% with a fluid latex was achieved in 119 hours at −10°C. In order to attain these high rates of conversion, it is necessary that the redox components of the polymerization recipe be properly “balanced” with respect to the mole ratio of oxidant to iron, and that the potassium chloride concentration in the activator and the pH of the emulsifier solution be adjusted to their optimum values.
Studies on rate of emulsion polymerization of butadiene‐styrene (75:25) as a function of amount and kind of emulsifier used. III. Effect of amount of soap on rate of polymerization
Authors: Kolthoff I. M. , Meehan E. J. , Carr C. W.
Published: April 2003

The rate of emulsion copolymerization of butadiene‐styrene (75:25) has been studied at 50°C. as a function of the amount of soap. The following soaps were investigated: potassium myristate, potassium laurate, sodium caprate, sodium salt of dispropor‐ tionated rosin acids, and a commercial soap (largely sodium palmitate, oleate, and stearate). The initial rate of polymerization is decreased as the amount of soap is decreased, but the rate after about 25% conversion becomes almost independent of the amount of soap. If the concentration of soap in the aqueous phase is less than the critical concentration for micelle formation the initial rate is extremely small and becomes about equal to the rate in the absence of emulsifier. The initial rate with varying amounts of different detergents is approximately proportional to the amount of solu‐ bilization by the soap or other detergent solution. The data confirm Harkins' theory that solnbilization by soap micelles is a major factor in the initial stages of emulsion polymerization.
Denaturation of plant proteins. IV. Increase in reducing capacity, viscosity, and optical rotation upon denaturation with guanidine hydrochloride
Authors: Jirgensons B.
Published: April 2003

Legumin of vetch and tuberin of potato have been denatured by guanidine hydrochloride. It was found that the reducing capacity (as estimated by titration with iodine in slightly acid solutions), the optical rotation, and the viscosity thereby increase. The specific rotation of legumin is increased from −42° for native legumin up to −90° for denatured legumin. The optical rotation and reducing capacity decrease with decreasing pH. According to the titration data, only about 12% of the sulfide can be detected by iodine; upon denaturation, the amount of detectable SH groups increases up to 40–80%.
Treatment of wood with ultrasonic waves
Authors: Gralén Nils , Berg Stig
Published: April 2003

The treatment of wood with ultrasonic waves causes a disintegrating of the biostructure of wood and splits the bonds between lignin and cellulose or other carbohydrates. It is possible that the bonds of the cellulose molecule are split at the same time, but certainly to a lesser degree or at a slower rate. After treatment with ultrasound, about 50% of the wood can be dissolved in cuprammonium. The dissolved material (carbohydrates) consists of two main components with different sedimentation constants. The two components are approximately classified as the cellulose and the hemicellulose of the wood.
Crystallinity of celluloses after treatment with sodium hydroxide (mercerization)
Authors: Hermans P. H. , Weidinger A.
Published: April 2003

The crystallinity of rayons measured with a standardized x‐ray method increases from 40 to 50% after previous treatment with 18% sodium hydroxide followed by removal of the alkali with boiling water. If the washing‐out of the alkali is carried out at room temperature, or if 4% sodium hydroxide is employed, the increase in crystallinity is smaller. Neither exclusion of oxygen during mercerization nor addition of hydrogen peroxide to the soaking lye has an influence on the final crystallinity. Native celluloses (ramie and wood pulp), after soaking in 18% sodium hydroxide and washing at the boil, yield the same figure of 50% crystallinity. A crystallinity figure of 50% is also obtained upon heterogeneous acid hydrolysis of rayon fibers at 100°C. and in cellulose precipitated from dilute viscose solution at 100°.
Viscosity‐molecular weight relationship for cellulose acetate in acetone
Authors: Philipp Howard J. , Bjork Carold F.
Published: April 2003

Careful viscosity and osmotic pressure measurements with a membrane of known reliability are reported for 14 fractions of cellulose acetate prepared by repeated refractionation, For molecular weights up to 115,000 the following relation is obtained between intrinsic viscosity and absolute molecular weight:

the units of [η] being 100ml./g. An explanation is offered for the difference between this equation and other equations in the literature as well as for the discrepancies among the various literature equations.