bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrasonic degradation of polystyrene. Part II. Experimental
Authors: Gooberman G. , Lamb J. 
Published: April 2003

AbstractMolecular weight distributions have been found for fractions of polystyrene degraded ultrasonically in benzene solution at very low concentrations (0.002% w/v). The distributions show that little, if any, of the degradation products include molecules of molecular weight less than 50,000. The variation of the rate constant for the degradation of the molecules with molecular weight follows the theoretical relation being proportional to M2.82 derived in Part I up to molecular weights of 106. Beyond this value the rate constant increases at a slower rate. This is attributed to a change in the variation of the shock pressure and rear flank of the shock wave with distance from the cavity. The rate constant for a given fraction reaches a peak at a concentration of about 0.01% w/v after which it falls rapidly with increasing concentration. This is attributed to the formation of a network by the polymer which reduces the rate of the cavity collapse.
The growth habit of single polymer crystals
Authors: Price Fraser P. 
Published: April 2003

AbstractWhen polymer single crystals are precipitated from dilute solution all the crystals have very nearly the same basic thickness. This thickness increases with increasing temperature of precipitation. This behavior is shown to result from a growth process in which the rate‐controlling step is the coherent nucleation of new layers of crystal upon the nonfolded planes of existing polymer crystals. The essential feature of the theory is the recognition that a nucleus of folded chains can enlarge easily only in directions parallel to the planes of folds. The theory is concerned primarily with the growth of crystals and only secondarily with their birth. It is shown that for polyethylene at reasonable supercoolings all the crystals will have essentially the same thickness and that this thickness should increase with temperature.
Intermolecular association in organic nitriles; the CN dipole‐pair bond
Authors: Saum A. M. 
Published: April 2003

AbstractThe nature of the intermolecular interactions involving the CN groups in organic nitriles has been investigated through comparison of the physical properties of nitriles and other organic liquids. Evidence is presented that hydrogen bonding is not a significant factor in these interactions. The CN groups tend to associate in pairs by dipole interaction, leading to partial dimerization in mononitriles and to longer‐range association in dinitriles. The energy of interaction between two CN groups is high, about 8 kcal./mole; it is proposed to call this interaction a CN dipole‐pair bond, by analogy with the hydrogen bond. Equations are derived for energies of interaction between dipoles separated by relatively short distances.
The statistical analysis of polymer fractionation data. Part II
Authors: Booth C. , Beason L. R. 
Published: April 2003

AbstractThe analysis of successive polymer fractionation data by conventional and statistical methods is discussed. The data from fractionations of polystyrene and styrene‐butadiene rubber are analyzed by the several methods and the molecular weight distributions so obtained are compared with the molecular weight distributions calculated from a knowledge of the kinetics of the polymerization systems. The direct statistical methods are shown to be superior to the alternative procedures. Such methods approximate the individual fraction distributions by simple statistical distributions (binomial or generalized exponential), the parameters of which are calculated directly from a knowledge of two average molecular weights (M̄n and M̄w).
4‐Vinylbenzenephosphonic acid
Authors: Wiley Richard H. , Trinler W. A. 
Published: April 2003

Abstract4‐Vinylbenzenephosphonic acid has been synthesized by the following reaction sequence: 2‐bromoethylbenzene was nitrated to 1‐(2‐bromoethyl)‐4‐nitrobenzene in 52% yield; the nitro compound was converted with stannous chloride to 4‐(2‐chloroethyl)aniline in 75% yield; the aniline was converted to its diazonium fluoborate (75%) and decomposed in the presence of phosphorus trichloride to give 4‐(2‐chloroethyl)benzenephosphonic acid in 36% yield; and the chloroethyl compound was dehydrohalogenated to the 4‐vinylbenzenephosphonic acid isolated as its hemi potassium salt in 75% yield. The free acid was obtained from the potassium salt by recrystallization from 6N hydrochloric acid.
The incorporation of aroyl peroxide fragments in polystyrene
Authors: Dannley Ralph L. , Essig Henry J. 
Published: April 2003

AbstractInitiation of the solution polymerization of styrene by catalytic quantities of p‐chloro‐,p‐bromo‐, and p‐nitrobenzoyl peroxides leads to incorporation of catalyst fragments which are primarily (88–95%) aroyloxy groups. Use of p‐iodobenzoyl peroxide gives polymers of somewhat higher molecular weight and lower (79%) aroyloxy fragment content. This anomalous behavior of the iodo compound may be due to its rearrangement to an iodosobenzoate‐type compound. Treatment of polystyrene in benzene solution with these same peroxides leads to incorporation of catalyst fragments 96% chlorobenzoyloxy and 48% bromobenzoyloxy groups. p‐Nitrobenzoyl peroxide is not incorporated under these conditions. This is due to a scavenging action of the benzene solvent. p‐Iodobenzoyl peroxide again did not fit a general pattern and introduced 68% aroyloxy groups. In all of these reactions and increase in molecular weight of the polymer occurred. Treatment of bulk polystyrene with the peroxides led to incorporation of 70% chlorobenzoyloxy, 55% bromobenzoyloxy, and 3% p‐nitrobenzoyloxy groups. In these reactions the molecular weights of the polystyrene samples always decreased.
Viscosity relationship in solutions of polyethylene glycols
Authors: Thomas D. K. , Charlesby A. 
Published: April 2003

AbstractThe intrinsic viscosities of a series of polyethylene glycols have been measured in water and toluene, and a relationship proposed between molecular weight and intrinsic viscosity. Values obtained for the Huggins constant below a molecular weight of 4000 are much larger than would be anticipated for linear high polymers. Some information about the variation of configuration with molecular weight has been obtained by comparing the specific viscosities with those expected from the relationships of Einstein and Guth and Gold for spherical particles, and those of Kuhn and Simha for rodlike particles.
The mechanisms of radiation‐induced changes in vinyl polymers
Authors: Todd Audrey 
Published: April 2003

AbstractAn investigation has been made to discover why some polymers degrade while others predominantly crosslink on exposure to high‐energy radiation. All the work was carried out on pure vinyl polymers prepared under controlled conditions, and the irradiations were conducted in vacuo. The volatile irradiation products were analyzed by mass spectrography, and the polymer residues were examined by solubility tests, viscosity measurements, and radioactive assay of 14C‐labeled polymers. The results confirmed that vinyl polymers containing a qunternary carbon atom degraded while the rest became crosslinked. Polymethyl methacrylate underwent random main‐chain scission with the elimination of rather less than one. COOCH3 side group for each main‐chain fracture. Some of the polymers which crosslinked lost side groups but this was not related directly to the crosslinking reaction. Free radical mechanisms are proposed to explain the occurrence and the observed features of the radiation‐induced degradation and crosslinking reactions.
The diethylenetriamine‐cellulose complex
Authors: Segal Leon , Loeb Leopold 
Published: April 2003

AbstractDiethylenetriamine and cellulose form a stable complex with interplanar spacings of d101 = 11.54, d = 4.53, and d002 = 4.18 A. The spacings are almost identical to those of the ethylenediamine‐cellulose complex. It is concluded from the x‐ray data that the triamine molecule separates two cellulose chains and crosslinks them through the secondary and one primary amino group of the triamine.
Anionic polymerization. Mechanism of methyl methacrylate polymerizations initiated by metal amides in liquid ammonia
Authors: Goode William E. , Snyder William H. , Fettes Robert C. 
Published: April 2003

AbstractPolymerizations of methyl methacrylate initiated by potassium and sodium amides in liquid ammonia solution proceed extremely rapidly even at low temperatures. The resulting polymers have relatively narrow molecular weight distributions M̄v/M̄n ∼ 1.5 and, unlike polymers of styrene prepared similarly, do not contain terminal amine groups. The molecular weight of poly(methyl methacrylate) prepared with potassium amide is independent of the monomer concentration and of the concentrations of potassium amide, potassium ion, and amide ion. The absence of terminal amine groups suggests that methoxide ion, produced by 1,2‐addition of amide ion to the monomer, is the actual initiating species. The substantial absence of a termination step is indicated by the narrow distribution of molecular weights. Several minor variations of this general reaction sequence may give the experimentally observed independence of molecular weight on reactant concentrations. One such modification is considered by way of illustration, although final selection of a detailed mechanism is not possible on the basis of the present results.
Polymerization of butadiene with aluminum triisobutyl–titanium tetrachloride catalyst system
Authors: Gaylord Norman G. , Kwei Ti‐Kang , Mark Herman F. 
Published: April 2003

AbstractThe effect of Al/Ti molar ratio, temperature, and solvent on the microstructure of polybutadiene prepared with an aluminum triisobutyl–titanium tetrachloride catalyst system was investigated. Although polymers containing as much as 98% trans‐1,4 structure were obtained, under appropriate conditions, no polymers with greater than 60% cis‐1,4 structure were obtained. The amount of 1,2‐structure was generally below 10%. The rate of polymerization was measured at 25°C. in heptane by following the drop of butadiene pressure with time in a constant volume apparatus. The rate was a function of the Al/Ti molar ratio and was directly proportional to the amount of catalyst used. The rate of polymerization was proportional to the square of monomer pressure at Al/Ti ratios greater than 2.0. When the molar ratio was between 1.0 and 1.6, the rate was proportional to the first power of the monomer pressure. At molar ratios of 1.8 and 1.9 the dependence of rate on monomer pressure could be represented by −dP/dt = aP + bP2, indicating the possible existence of two concurrent reactions. When the ratio fell below unity the uptake of butadiene was at first rapid but soon slowed to a stop. Possible kinetic schemes are discussed in terms of Rideal and Langmuir‐Hinshelwood mechanisms.
The effect of depropagation on copolymer composition. I. General theory for one depropagating monomer
Authors: Lowry George G. 
Published: April 2003

AbstractThe following mechanism is postulated for the copolymerization of α‐methylstyrene (or similar 1,1‐disubstituted ethylene), M2, at temperatures near its ceiling temperature but far below the ceiling temperature of the comonomer, M1. Either M1 or M2 may combine with a polymer chain ending in either m or m. When either monomer adds to a chain ending in m, the new active chain is stable to depropagation, as is a new active chain formed by either monomer adding to a chain ending in m1m. However, whenever either monomer adds to a chain ending in m1(m2), where n ≥ 2, the newly formed active chain will have a finite tendency to depropagate and to “unzip” until the terminal radical is m1(m2), which itself is stable to depropagation. However, a sequence of m1(m2) becomes trapped, or stabilized, if it reacts with a molecule of M1 and then with a molecule of either M1 or M2 before the first unit of monomer M1 can split off. A steady‐state kinetic analysis of this mechanism leads to a copolymer composition equation which, although unwieldy, allows the following general predications. (1) Temperature will have a marked effect on the shape of the copolymer composition curve in the region of the ceiling temperature of M2. (2) Dilution of the monomers by an inert solvent will have a marked effect on the shape of the copolymer composition curve in the region of the ceiling temperature of M2. (3) The limiting mole fraction of M2 in a copolymer prepared at high temperature will be two‐thirds. Two other mechanisms of copolymerization involving the depropagation reaction of one monomer are analyzed to obtain copolymer composition equations. In one of these, it is assumed that M1 will never split off an active chain. This results in the same qualitative predictions as above but slightly different quantitative predictions. In the other case studied, it is assumed that M1 will never split off an active chain and that when a chain ends in m1(m2), it can unzip all the way to m1m. This leads to the same qualitative predictions as before but the limiting mole fraction of M2 in a copolymer prepared at high temperature is one‐half rather than two‐thirds.
Cationic polymerization in liquid sulfur dioxide. I. Cationic polymerization of styrene with SnCl4
Authors: Asami Ryuzo , Tokura Niichiro 
Published: April 2003

AbstractCationic polymerization of styrene in liquied sulfur dioxide was carried out at 0 and 25° using SnCl4 as a catalyst, and polystyrene was obtained very rapidly and in a quantitative yield. Flash polymerization was obtained with concentrations of stannic chloride above 10−2 mole/1. The molecular weight of polystyrene thereby formed ranged from 2 × 104 to 9 × 104 at 0°, much greater than that obtained by cationic polymerization in organic solvents. It was found that \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {{\rm DP}} $\end{document} (at 0°) depended on [St]/[SnCl4], and it was assumed that the polymerization of styrene by stannic chloride in liquid sulfur dioxide is a cationic polymerization of the “living polymer” type, strengthened by dissociating and solvating characteristics of liquid sulfur dioxide.
Polymer chain dimensions in mixed solvents
Authors: Noel R. , Patterson D. , Somcynsky T. 
Published: April 2003

AbstractAn extension of the Shultz‐Flory theory of polymer chain dimensions in mixed solvents is proposed. It is based on solution thermodynamics with z, the lattice coordination number, finite rather than effectively infinite. Intrinsic viscosities of polyisobutylene in cyclohexane–benzene solutions have been obtained over the range of compositions and theoretical values compared with them. Those with z ∼ 4 give the best fit. A similar analysis has been performed for published intrinsic values of polystyrene in the same mixture, giving z ∼ 3. The z values compare well with those found for polyisobutylene–benzene and polystyrene–benzene by other methods, and this low value may be due to backcoiling of the polymer molecules.
Determination of degree of crosslinking in natural rubber vulcanizates. Part V. Effect of network flaws due to free chain ends
Authors: Mullins L. , Thomas A. G. 
Published: April 2003

AbstractPrevious studies of the effect of flaws due to free chains ends on the elastic behavior of crosslinked polymer networks have considered either (1) the scission of chains in an initially perfect network, or (2) the crosslinking of chains of finite molecular weight. Published relations for the behavior of networks derived in these alternative ways are different. That derived from the first has been preferred for stress relaxation measurements, and that derived from the second for gel point theory. It is shown that the two treatments should be essentially equivalent. Critical consideration of what constitutes an elastically active chain resolves the anomaly of the difference between the two treatments and provides a new relation which should be valid for all ratios of crosslinks to chain ends. The new relation is checked by direct computation of the number of effective chains. This gives satisfactory agreement over the range where approximations, introduced during computation, are small.
Infrared spectra of crystalline polysaccharides. III. Mercerized cellulose
Authors: Marchessault R. H. , Liang C. Y. 
Published: April 2003

AbstractThe infrared spectra of doubly oriented films of mercerized ramie and Fortisan crystallites were observed over the 650–3600 cm. −1 frequency range. Polarization properties of the bands were determined. The CH2 symmetric bending frequency was found to be parallel polarized, from which it was concluded that the C6 hydroxyl groups are not engaged in intramolecular hydrogen bonds. The perpendicular bands in the OH stretching region are associated with intermolecular hydrogen bonds most probably in the 101 plane. The two bands showing strong parallel dichroism in the OH stretching region are associated with O3 → O′5 intramolecular hydrogen bonds. The observed data allowed a critical evaluation of the various hydrogen bonding schemes which have been proposed for cellulose II. Alternate schemes which are in better agreement with the infrared data are considered.
Infrared spectra of crystalline polysaccharides. V. Chitin
Authors: Pearson F. G. , Marchessault R. H. , Liang C. Y. 
Published: April 2003

AbstractThe polarized infrared spectra of crab chitin crystallites, blowfly larval cuticle, lobster tendon, and partially deacetylated lobster chitin have been studied. In addition, the spectra of amorphous deacetylated chitin, deuterated lobster chitin and crystalline N‐acetylated chitohexaose were obtained and analyzed. Band assignments have been made with the aid of previous work on celluloses and other related molecules. The complete intermolecular CO‐‐‐‐HN hydrogen bonding scheme, orginally proposed by Carlstrom from x‐ray studies, is in agreement with the infrared data. With the aid of a scale model of the chitin unit cell, a number of hydrogen‐bonding schemes involving the primary hydroxyl group have been examined and are discussed.
Phenylene sulfide polymers. II. Structure of polymers obtained by the Macallum polymerization
Authors: Lenz Robert W. , Handlovits Carl E. 
Published: April 2003

AbstractPolymers prepared by the Macallum homopolymerization and copolymerization were compared to a linear phenylene sulfide polymer prepared by the self‐condensation of sodium p‐chlorothiophenoxide. The properties compared included solubility, softening point, melting point, x‐ray diffraction pattern, infrared spectrum, and thermal stability. For the last named, both differential thermal analyses and thermal gravimetric analyses were obtained. The linear polyphenylene sulfide and the Macallum polymers were found to be essentially identical in all of these properties, even though the sulfur contents ofthe latter were generally higher by 15–20% of the amount present than in the linear polymer. Consideration of this identity and of the probable mechanism of the Macallum polymerization led to the postulation of a structure for the Macallum polymers consisting of a crosslinked core to which are attached more or less extended, linear chains.
Synthesis of fluorinated N‐alkyl substituted polyamides
Authors: Marks Burton S. , Schweiker George C. 
Published: April 2003

AbstractMethods of synthesizing linear, N‐alkyl substituted, fluorine‐containing polyamides of two types were investigated. Type I is represented by the general formula
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and Type II by the formula
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The method most suitable for Type I polymers consisted in reacting N,N′‐dialkyl substituted diamines with dimethyl perfluoroglutarate, while the technique most suitable for Type II polymers was reaction of N,N′‐dialkyl substituted 2,2,3,3,4,4‐hexafluoropentanediamines with adipyl chloride. Type I polyamides formed more readily and were of higher molecular weights than Type II polyamides. The difficulty in the formation of high molecular weight Type II polyamides is due to the weakly basic properties of the fluorinated diamines. All the higher molecular weight polymers were dark brown rubberlike gums. In general, solubility of the polymers in organic solvents increased as the size of the N‐substituent progressed, from methyl to n‐butyl. Type I polyamides readily hydrolyzed whereas Type II did not. A minimum in the approximate brittle temperatures was noted when R = ethyl for Type I polyamides, and when R = n‐butyl for Type II polyamides.
Mechanical anisotropy in drawn films of regenerated cellulose
Authors: Wilson N. 
Published: April 2003

AbstractThe Young's moduli of drawn films of regenerated cellulose have been measured for loads applied parallel and perpendicular to the direction of drawing. Measurements were made at 20°C. at 65 and 100% R. H. Two types of films were investigated; both had been prepared by saponification of cellulose acetate, but in one type (prestretched) the drawing process preceded the saponification, while in the other type (poststretched) the drawing process followed the saponification. For both types of films the Young's modulus parallel to the direction of drawing increased markedly with draw ratio, while that perpendicular to the direction of drawing decreased slightly. At the highest draw ratios the ratio of the two moduli was approximately 5 at 65% R. H. and 10 at 100% R. H. No large differences were found between the two types of film.
The copolymerization of cyclic siloxanes
Authors: Merker Robert L. , Scott Mary Jane 
Published: April 2003

AbstractThe Mayo and Lewis reactivity ratio concept was found to be applicable to the treatment of the data obtained from base‐catalyzed copolymerization studies involving eight cyclic siloxane monomers. The cyclics investigated were hexamethylcyclotrisiloxane, hexaphenylcyclotrisiloxane, and all six members of the series, where R is methyl and/or phenyl. The products of the reactivity ratios for a number of the monomer pairs studied were close to unity, thus indicating little catalyst specificity. Polymerization reactivity increased with increased ring strain and increased degree of phenyl substitution. The tetraphenyl silethylene‐siloxane cyclic, the most reactive cyclic to base‐catalyzed polymerization, was found to be about one hundred and sixty times more reactive than the least reactive cyclic, hexamethylcyclotrisiloxane. Reactivity ratios were found to be quite temperature‐dependent, thus suggesting rather large differences in activation energy. With increasing temperature, the reactivity ratios approached a value of unity.
Chain structure of poly‐m‐methylstyrene
Authors: Corradini P. , Ganis P. 
Published: April 2003

AbstractThe chain conformation of the isotactic polymer of m‐methylstyrene is discussed in this paper. As it was possible to foresee, the chain has a helicoidal shape, but, contrary to other chains of isotactic polymers, it contains 11 monomeric units in 3 pitches. Owing to the structural complexity which does not allow a calculation of structure factors, the distribution of intensity in the x‐ray fiber spectrum is compared with the distribution of intensity, which should provide an isolated chain having the proposed conformation. The calculation has been performed according to a formula previously deduced. The agreement obtained is satisfactory. The possibility of applying the same procedure to the resolution of other problems is briefly discussed.
Vapor pressure of 2,4,6‐triamino‐s‐triazine (melamine)
Authors: Hirt R. C. , Steger J. E. , Simard G. L. 
Published: April 2003

AbstractThe vapor pressure of melamine was measured in the temperature range of 144–341°C. by the dynamic method, ultraviolet spectrophotometry being used to determine the amounts transferred at the lower vapor pressures. Nitrogen and ammonia were used as carrier gases. The vapor pressures are given by the expression log P = 12.52 − (6440/T). The average heat of sublimation was found to be 29 ± 1 kcal./mole.