bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of perbenzoic acid in analysis of unsaturated compounds. I. Preparation and stability of solutions of perbenzoic acid
Authors: Kolthoff I. M. , Lee Thomas S. , Mairs Mary Anne 
Published: April 2003

AbstractThe preparation of perbenzoic acid has been investigated in a n attempt to obtain standard solutions of perbenzoic acid suitable for the amlyszk of unsaturated compounds. Some modifiations of the procedure given by Braun for the preparation of a solution of perbenzoic acid in a n organic solvent are recommended. A study has been made of the stability of solutions of perbenzoic acid in chloroform and in benzene. Benzene or benzene‐chloroform mixtures are recommended as solvents for perbenzoic acid. Chloroform solutions of perbenzoic acid which do not contain inhibitors for decomposition have been found to be definitely undesirable in analytical work because perbenzoic acid catalyzes the decomposition of chloroform by oxygen. construction Finance Corporation, in connection with the Government Synthetic Rubber Program.
Polyisoprenes: A theory of the formation of terpenes and related compounds
Authors: Tobolsky Arthur V. , Castro Luis , Stein Sidney J. , Sacher Alex 
Published: April 2003

AbstractA mechanism is presented which shows how terpenes and related compounds, some of which are found associated with trans—polyisoprene in nature, may be expected to be formed by a radical chain oxidative degradation of trans—polyisoprene.
Reaction of tetrachlorophthalic anhydride with cellulose derivatives
Authors: Utermohlen William P. , Wallace E. Louise 
Published: April 2003

AbstractTetrachlorophthalic anhydride (TCPA) was reacted with cellulose diacetate and with cellulose diethyl ether in dioxane solution to produce esters with rather low tetrachlorophthalyl contents. Phthalic anhydride was found to be considerably more reactive than was TCPA with these cellulose derivatives, especially if pyridine was used as the reaction solvent. Acylations could not be executed with TCPA in the presence of pyridine as solvent, however, because this material decomposed the anhydride, removing chlorine from it. The TCPA derivatives were more limited in solubility than were the corresponding esters made from phthalic anhydride.
Diffusion of water into a polymer
Authors: Custers J. F. H. 
Published: April 2003

AbstractIn contradistinction to the usual methods, the diffusion of water into a polymer has been investigated by starting from a disk of the material surrounded by water. In this way, actual service conditions are often closely approached. Since a theoretical basis is desirable, equations are given for this type of diffusion, and experiments with a wood flour containing phenol‐formaldehyde material were performed from which values for the permeation constant could be derived.
Influence of structure on polymer‐liquid interaction. I. Relative and absolute values of swelling equilibria
Authors: Salomon G. , Van Amerongen G. J. 
Published: April 2003

AbstractThe swelling of vulcanized natural rubber, Buna S, neoprene, Perbunan, and Perbunan Extra was measured in various organic liquids. The essential influence of polarizability and polarity on the swelling equilibrium is illustrated by comparing series of solvents and polymers with gradually changing geometrical and chemical structure. Experiments on the influence of temperature and of strain on the swelling equilibrium are reported. The swelling properties of ebonites and similar derivatives allow some conclusions on the amount of cross linking in these polymers.
Course of acetylation and deacetylation reactions of cellulose fibers. II. X‐ray diagrams
Authors: Vermaas D. , Hermans P. H. , Weidinger A. 
Published: April 2003

AbstractA discussion is offered of the x‐ray patterns of partially acetylated and saponified cellulose model filaments with varying acetyl contents. They are substantially in conformity with the swelling experiments previously described in Part I (page 397) of this paper. (1) In nonrecrystallized filaments, chemical reaction takes place in the crystallites and the intercrystalline regions from the very beginning of the experiment. The rate of chemical conversion, however, is larger in the latter. (2) Acetylation of the hydrate cellulose crystallites results in a gradual increase in the (101) spacing, A0; the A3 and A4 reflections [corresponding to (101) and (002), respectively] remain unimpaired up to a gross acetyl content of at least 1.5 acetyl groups per glucose residue. (3) Maximally acetylated filaments containing 2.3 acetyl groups per glucose residue may be recrystallized by heating in methanol or ethanol. The diagram of the recrystallized product is identical with the pattern of cellulose triacetate II. With about halfway acetylated or saponified products, recrystallization is not realizable by means of a heating process in water or methanol. (4) Enhanced degree of local order as the result of previous recrystallization of maximally acetylated products produces a more pronounced difference in rate of saponification between the “crystalline” and “amorphous” fiber portions.
Multi‐ingredient polyamides
Authors: Catlin W. E. , Czerwin E. P. , Wiley R. H. 
Published: April 2003

AbstractMulti‐ingredient polymeric amides have been prepared by the condensation, under amide‐forming conditions of various combinations and ratios of components comprising hexamethylenediammonium adipate, hexamethylenediammonium sebacate, and ϵ‐aminocaproic acid or ϵ‐caprolactam. The physical properties of the investigated linear polymeric amides range, depending upon the polymer components and the proportions employed, from high‐softening, stiff, and difficulty soluble compositions to relatively low‐softening, pliable, and easily soluble polymers.
Tensile strengths of pure gum natural rubber compounds
Authors: Gee Geoffrey 
Published: April 2003

AbstractThe tensile properties of a range of pure gum natural rubbers has been reviewed, and it has been shown that their principal features can be understood on the assumption that the tensile strength measured in a given test depends directly on the amount of crystallization at break. The most important single factor in determining tensile strength is the degree of cross linking. Cross linking is only needed in order to prevent plastic flow, thus permitting the molecules to be aligned by stretching, and hence to crystallize. A very highly cross‐linked rubber is weak because the load required to stretch it is so high, that the rubber is broken before the elongation becomes large enough to produce crystallization. In general, vulcanization also involves reactions, e.g., the combination of sulfur with the rubber, which inhibit crystallization by producing structural modifications of the rubber. These reduce the tensile strength, especially when the degree of cross linking is large. These ideas readily explain the effects of swelling and of the temperature of test. They are also used in a brief discussion of the phenomena of overcure, reversion, and aging.
Emulsion polymerization at high temperature
Authors: Rabjohn Norman , Dearborn R. J. , Blackburn W. E. , Inskeep G. E. , Snyder H. R. , Marvel C. S. 
Published: April 2003

AbstractThe emulsion polymerizations of butadiene and styrene and of butadiene alone have been studied at temperature of 90–160°. The effects of changes in catalysts, modifiers, times of polymerization, and other variables have been investigated. The rate of polymerization at 110° is markedly increased over that at 50° and the final product is a less modified and less processable polymer. However, the standard evaluation and road tests indicate this polymer may be a useful one.
Polythene fine structure
Authors: Bryant W. M. D. 
Published: April 2003

AbstractPart 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

AbstractFrom 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

AbstractA 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

AbstractPhysical 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

AbstractFive 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

AbstractIt 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

AbstractPrecise 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

AbstractMethods 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

AbstractThe 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

AbstractThe 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

AbstractExperimental 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

AbstractSolid 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

AbstractDie 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

AbstractThe 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

AbstractThe 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.
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

AbstractThe 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

AbstractThe 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

AbstractThe 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.