bluuebunny/crossref_metadata_2025 huggingface dataset:
The thermal degradation of poly‐p‐xylylene
Authors: Schaefgen J. R.
Published: April 2003

The thermal stability of poly‐p‐xylylene prepared in solution by the Hofmann reaction has been measured by a viscometric method. The polymer decomposes by a first‐order random cleavage mechanism with an activation energy of 58 kcal./mole. The latter value is identified with the bond strength of the carbon‐carbon bond between methylene groups connecting benzene rings. The stability of this polymer is thus limited only by the strength of the weakest link along the chain. The polymer is shown to be more stable thermally and more soluble than polymer prepared from p‐xylene by the pyrolytic method. The effect of chain transfer agents on the thermal stability was investigated.
Polyolefin production with preformed solid catalysts
Authors: Harban A. A. , Field Edmund , Friedlander H. N.
Published: April 2003

A broad range of plastic and elastomeric materials can be made from olefins by solid catalysts, either precipitated in situ or preformed with high surface area. Solid catalysts have been applied to polymer production in two basic processes: suspension and solution. In the suspension process, polymer is made below its softening point in a medium that dissolves neither catalyst nor polymer. In the solution process, polymer is made in solution with a solid catalyst dispersed in the solvent. The literature implies that suspension polymerization is always used with precipitated catalysts, and solution polymerization with preformed catalysts. However, the processes are independent of the catalysts. For example, a single family of promoted preformed catalysts can produce linear polyethylene of low melt index or polypropylene by a suspension process below 150°C., and linear polyethylene of normal melt index or copolymers of ethylene and α‐olefins by a solution process above 150°C. All these routes produce useful polymers with desirable properties. Suspension polymerization is used when the catalyst requires operation at low temperatures, when the product with desired properties can only be obtained at low temperatures, or when the molecular weight of the polymer is too high to give solutions of reasonable viscosity. Solution polymerization is used when the catalyst permits or requires higher temperatures of operation, when the desired product can be made at these temperatures, or when the molecular weight of the product is low enough to form solutions of viscosities that can be readily handled.
Radiation graft copolymerization in aqueous dispersion
Authors: Cooper W. , Sewell P. R. , Vaughan G.
Published: April 2003

The rates of polymerization of monomers in rubber in aqueous dispersion are higher than in the corresponding bulk polymerizations. The higher rates, which are independent of latex concentration over the range of concentration studied, have been attributed to the ingress of free radicals from a certain volume of the aqueous phase surrounding each particle. The γ‐radiation‐initiated graft polymerization of styrene with rubber is similar to that with methyl methacrylate, though the fraction of grafted polymer is lower. In the photoinitiated systems, styrene behaves differently from methyl methacrylate in that the rate of polymerization diminishes at higher monomer concentrations.
Electron resonance spectra of gamma‐irradiated polymers: Measurements at 77°K. on polymethacrylic acid and related compounds
Authors: Ovenall Derick W.
Published: April 2003

The electron spin resonance (e.s.r.) spectra of free radicals trapped in some addition polymers after gamma‐irradiation at 77°K. are described and discussed. When polymethacrylic acid is gamma‐irradiated at 77°K., the e.s.r. spectrum at this temperature consists of a symmetrical pattern of seven lines which may be due to dimethyl carboxy methyl radicals, (CH3)2C—CO2H. On warming to 300°K. this spectrum is replaced by the normal “five‐plus‐four line” spectrum, which has been attributed to trapped propagating radicals. When polymethacrylic acid freed from monomer is gamma‐irradiated at 77°K. the e.s.r. spectrum is a single line, probably arising from trapped ·CO2H radicals. A reaction scheme is put forward to account for the production of these radicals. Some observations on polymethyl, polyethyl, poly n‐butyl, and poly n‐hexyl methacrylates and polydimethyl itaconate are also reported.
Thioglycol polymers. I. Hydrochloric acid‐catalyzed autocondensation of thiodiglycol
Authors: Woodward F. N.
Published: April 2003

The possibility of including autocondensation of thiodiglycol in the presence of potential dehydrating catalysts has been investigated. Of the possible catalysts examined, hydrochloric and sulfuric acids were found to be the most effective. In the presence of 0.5–3.0% of the former at temperatures in the range 50–200°, low molecular weight, waxy, water‐soluble, solid polymers of the type HO[C2H4SC2H4O]nC2H4SC2H4OH were obtained in yields upto 67% in addition to some ring closure to give thioxane. The dimer (n = 1) was obtained in a pure state, and the next five members in the series (n = 2–6), in impure form. Evidence was obtained of the formation of the compounds with molecular weights up to about 1300 (n = 11).
Thioglycol polymers. II. Phosphorus pentoxide‐catalyzed autocondensation of thiodiglycol and 2,2′‐dihydroxydiethyl disulfide
Authors: Abrams J. T. , Andrews K. J. M. , Woodward F. N.
Published: April 2003

The study of the autocondensation of thiodiglycol initiated in Part I has been extended under conditions likely to give water‐insoluble polymers of higher molecular weight. The catalytic power of 27 compounds was first determined, and the rates of polymer production were assessed for reaction in the presence of those eleven compounds thus found to be most effective. On the basis of mean molecular weight (3300), solubility in benzene, yield, and appearance of the product, phosphorus pentoxide was chosen for more exhaustive tests. Heating thiodiglycol with P2O5 (2.0%) for 12 hr. at 140°/760 mm., followed by heating for increasing periods at 150°/40 mm., yielded products ranging from a viscous liquid (M.W. 2500; ηsp 0.067) to a rubbery dark‐brown wax (M.W. 6500; ηsp 1.061). The solubility in benzene, chloroform, and dichlorodiethyl ether decreased with increasing molecular weight. The catalyst tended to become exhausted: this was found to be due to chemical combination. 2,2′‐Dihydroxydiethyl disulfide was successfully autocondensed under similar conditions to give an elastic, insoluble polymer with some tendency to cold flow, presumably built up from C2H4OC2H4S2 units.
Polymerization of butene‐1 with Ziegler catalysts
Authors: Medalia A. I. , Orzechowski A. , Trinchera J. A. , Morley J. P.
Published: April 2003

The Ziegler polymerization of butene‐1 has been studied in detail, by means of the pressure bottle technique. Eight principal conditions of polymerization have been varied. The amount and properties of the polymer have been studied, with particular emphasis on the atactic polymer. The polymers are generally from 50 to 70% atactic. Yields of over 300 g. polymer per gram of triisobutyl aluminum and intrinsic viscosities of over 2.5 have been obtained. The rate of polymerization goes through a sharp maximum at a catalyst ratio (Al/Ti) of 1.5–1.7. The kinetics are first‐order in monomer, with a sharp drop in the rate constant after 1–5 hr. of polymerization.
Phenylene sulfide polymers. I. Mechanism of the macallum polymerization
Authors: Lenz Robert W. , Carrington William K.
Published: April 2003

The reactions used in the past for the preparation of phenylene sulfide and related polymers are reviewed. The Macallum polymerization is a polycondensation of an aryl halide and an inorganic sulfide or polysulfide in the absence of solvents. The monomer system studied most thoroughly is represented by the following, unbalanced equation:
The synthesis of aromatic divinylogs and aromatic halogenated vinylogs
Authors: Frisch K. C.
Published: April 2003

Two new higher homologues of p‐divinylbenzene, p‐allylstyrene (p‐allylvinylbenzene) and p‐1‐propenylstyrene (p‐1‐propenylvinylbenzene) were synthesized and characterized. Intermediates for the synthesis of difunctional aromatic vinylogs, p‐chloro‐allylbenzene was prepared for the first time and p‐bromostyrene was made by methods different from those reported previously for this material. The usefulness of anhydrous cobaltous chloride for the activation of vinyl bromide in the reaction with aromatic Grignard compounds was demonstrated in the synthesis of p‐allyl‐ and p‐bromostyrene. Rearrangement of the allyl to the 1‐propenyl group on treatment with activated alumina at 300° was shown in the synthesis of p‐1‐propenylstyrene and 1‐propenylbenzene. Peroxide‐initiated bulk polymerization of p‐divinylbenzene, p‐1‐propenylstyrene, and p‐allylstyrene established the following order of reactivity: vinyl > 1‐propenyl > allyl. Preliminary polymerization of 1‐propenylstyrene and copolymerization with styrene in bulk and in solution showed the former to be an efficient though slower crosslinking agent than p‐divinylbenzene. Molding of solid copolymers of styrene and p‐1‐propenyl‐styrene was carried out, resulting in the formation of thermosetting clear and brittle resins.
The stereoregular polymerization of isoprene with lithium and organolithium compounds
Authors: Stearns R. S. , Forman L. E.
Published: April 2003

All of the alkali metals catalyze the polymerization of dienes such as butadiene and isoprene. A stereoregular polymer is obtained when the polymerization of isoprene is catalyzed by lithium or organolithium compounds in the absence of oxygen contaning solvents. The polymer has molecular structure, configuration, and physical properties similar to Hevea rubber, and a microstructure comprised of 93–95% cis‐1,4 and 5–7% 3,4 addition. The polymerization appears to proceed by way of an homogeneous catalytic mechanism. Stereoregularity is a result of cis coordination between a monomer molecule with a carbon bound lithium atom and formation of a six membered, cyclic, activated complex. This complex owes its relative stability to the capability of the lithium atom to undergo hybridization and to behave as an atom with considerable divalent character. The observed effects of temperature, catalyst concentration, type of solvent, and effect of Lewis bases such as ethers on the microstructure of these isoprene polymers are consistent with the catalytic reaction mechanism advanced.
The polymerization and copolymerization of alkylvinylacetylene derivatives
Authors: Price Charles C. , McKeon Thomas F.
Published: April 2003

With the use of free radical initiators, homopolymers from vinylacetylene (I), 2‐ethyl‐1‐vinylacetylene (II), isopropenylacetylene (III), and 2‐ethyl‐1‐isopropenylacetylene (IV) have been prepared in which the ethynyl group was largely preserved. Copolymers of these monomers with methyl acrylate, methyl methacrylate, acrylonitrile, styrene, and 2‐vinylpyridine have also been prepared. The Q and e values were determined from 2‐vinylpyridine and acrylonitrile copolymers: Q = 0.50, e = −0.40 for vinylacetylene; Q = 0.44, e = −0.35 for 2‐ethyl‐1‐vinylacetylene; and Q = 0.35, e = −0.30 for isopropenylacetylene. The polymers absorbed oxygen and became crosslinked and insoluble on exposure to air, which complicated, the investigation of molecular weight and ultraviolet spectra.
Studies on the enzymatic synthesis of dextran
Authors: Braswell Emory , Stern Kurt G.
Published: April 2003

The molecular weight (determined by light scattering) of the dextran produced during the enzymatic synthesis increases while the intrinsic viscosity decreases throughout the course of the reaction. The size and spherical shape of the dextran molecule does not change significantly throughout the course of the reaction. The “branching ratio” (1,6‐links to non‐1,6‐links) as indicated by periodate titration increases with the degree of conversion. An increase in branching would explain the intrinsic viscosity decrease and the density increase with increasing molecular weight. Fructose, which accumulates as a byproduct in the reaction mixture, is not responsible for these effects. The molecular weight of the dextran resulting from purified enzyme is much greater than that produced from crude enzyme. Because of this it is difficult to make conclusions about the mechanism of synthesis from this kind of data.
Poly‐N‐lauryl methacrylate. V. Dilute solution properties by viscosity and light scattering
Authors: Chinai S. N. , Guzzi R. A.
Published: April 2003

Poly‐n‐lauryl methacrylate, prepared by the emulsion technique, was fractionally precipitated to obtain nine sharp fractions. These fractions were studied in an ideal solvent, isopropyl acetate at 13°C., and in a nonideal solvent, n‐butyl acetate at 23°C., by the light scattering and viscosity methods. The principal relationships obtained are: in isopropyl acetate at 13°C. (theta solvent); [η]θ = 3.22 × 10−4 M, (r02)½ = 0.49 M; and the the good solvent, n‐butyl acetate at 23°C.; [η] = 8.46 × 10−5 M, (r2)½ = 0.35 M; for λ = 5460 A., A2 = 9.782 × 10−3 M and for λ = 4360A., A2 = 9.778 × 10−3 M. The effect of the size of the pendent groups on the degree of chain extension in ideal solvents is discussed. It was found that the degree of chain extension of the polymers thus far studied follows the order poly‐n‐lauryl methacrylate > poly‐n‐hexyl methacrylate > poly‐n‐octyl methacrylate > poly‐n‐butyl methacrylate > poly ethyl methacrylate ≥ polymethyl methacrylate.
Polyelectrolyte behavior of glycerol‐treated psoas fibers
Authors: Blum J. J. , Felauer E.
Published: April 2003

Glycerol‐treated psoas fibers lengthen when transferred from distilled water to 0.01M barbital at pH 3.3. The addition of electrolyte then causes a considerable shortening, depending primarily on the charge of the anion. The effects of the ionic strength are reversible. The extraction of myosin from the fiber increases the pH at which length changes are observable.
The effect of polymer composition on radiation‐induced crosslinking
Authors: Witt Edward
Published: April 2003

The gelation induced by Co60 gamma radiation in butadiene‐styrene copolymers, homopolymers, and mixtures of these homopolymers was studied by use of random crosslinking theory. The number of crosslinks formed per 100 e.v. of energy absorbed by the polymer, G(X), was found to be 0.045 for polystyrene and 3.6 for polybutadiene. The behavior of styrene units in copolymers and physical mixtures of butadiene and styrene homopolymers was different for the two polymer systems. Gel measurements showed that in the copolymer system there was a transfer of radiation energy from butadiene to styrene units, whereas there was no energy transfer in mill‐ and latex–prepared physical mixtures. It was further determined that terpolymerization of methyl methacrylate with butadiene and styrene induces some chain scission within the polymer chain when it is irradiated, thereby lowering further the net crosslinking of the resulting polymer.
Ultrasonic degradation of polystyrene. Part II. Experimental
Authors: Gooberman G. , Lamb J.
Published: April 2003

Molecular 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

When 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

The 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

The 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

4‐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

Initiation 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

The 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

An 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

Diethylenetriamine 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

Polymerizations 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

The 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

The 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

Cationic 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

An 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

Previous 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

The 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

The 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

Polymers 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

Methods of synthesizing linear, N‐alkyl substituted, fluorine‐containing polyamides of two types were investigated. Type I is represented by the general formula
magnified image
and Type II by the formula
magnified image
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

The 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

The 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

The 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

The 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.
Results of osmotic and of Donnan equilibria measurements in polymethacrylic acid–sodium bromide solutions. Part II
Authors: Alexandrowicz Z.
Published: April 2003

The osmotic and Donnan equilibria were measured in solutions of polymethacrylic acid in the presence of sodium bromide. The primary aim of these measurements was to apply a previously proposed thermodynamical interpretation of the experimental data. The Donnan distribution was determined by titration of the bromide, and was used to calculate the activity coefficient of the salt (in the presence of PMA). The osmotic equilibrium was determined by the previously described osmotic concentration method, and served to evaluate the osmotic coefficient of the solvent. The measurements were carried out at several degrees of ionization in solutions in which the concentration of both solutes was varied a thousandfold. The graphical differentiation of the above coefficients and the use of certain thermodynamical relations led to the calculation of the partial derivatives of the activity coefficients of the polyelectrolyte itself. The results obtained for the activity coefficients of salt, solvent, and polyelectrolyte could be described by equations of a very simple form, dependent only of the composition of the solution and on the experimentally determined osmotic coefficients of the pure solutions of the polyelectrolyte (i.e., with no salt added). These equations permit an unamiguous calculation of the activity of the various components in a salt‐containing polyelectrolyte solution of any given composition. Furthermore, their simple form should facilitate the theoretical interpretation of the properties of polyelectrolytes.
Heat of fusion of polyvinyl fluoride and its interaction with diluents
Authors: Sapper David I.
Published: April 2003

By employing a simple light‐scattering technique to obtain a higher order Tyndall spectrum in mixtures of polyvinyl fluoride with dimethyl sulfoxide, γ‐butyrolactone, and N‐methylpyrrolidone, melting point data were readily obtained. From these data the heat of fusion per crystalline unit of polymer was found to be about 1800 cal., and the entropy of fusion per unit per bond, 1.9 cal./deg. Of the solvents investigated, N‐methylpyrrolidone and dimethyl sulfoxide exhibited the most interaction with the polymer as indicated by interaction energy densities of −9.7 and −4.3 cal./cc., respectively.
Nitrogen‐containing monomers. II. Reactivity ratios of n‐vinyloxazolidone and N‐vinylpyrrolidone with vinyl monomers
Authors: Bork John F. , Coleman L. E.
Published: April 2003

The reactivity ratios in the copolymerization of N‐vinyloxazolidone with styrene, methyl methacrylate, decyl methacrylate, vinyl acetate, and vinyl chloride have been determined and the Alfrey‐Price Q and e values calculated. Reactivity ratios in the copolymerization of N‐vinylpyrrolidone with styrene, methyl methacrylate, and vinyl acetate have also been determined and the Q and e values determined. N‐Vinyloxazolidone was found to be similar but less reactive than N‐vinylpyrrolidone as a comonomer; however, the properties of the resultant copolymers differed appreciably.
A comparison of some physical properties of polyethylene–styrene graft copolymers prepared by the trapped free radical method and polyethylene–polystyrene blends
Authors: Anderson Leigh C. , Roper Don A. , Rieke James K.
Published: April 2003

The preparation and properties of polyethylene–styrene graft copolymers using trapped free radicals produced by gamma rays has been reported. When polystyrene branches are attached to the polyethylene chain there is reinforcement of the properties of polyethylene, whereas the corresponding physical blend of polystyrene and polyethylene has lowered physical properties.
Elution fractionation of crystalline and amorphous polymers
Authors: Kenyon A. S. , Salyer I. O.
Published: April 2003

Elution fractionation has been applied to crystalline and amorphous polymers. Variables such as the method of polymer deposition, elution rate, and temperature have been studied. Atactic polystyrene can be fractionated successfully by either selective or nonselective deposition of the polymer onto the sand column support. However, only polymers having a sufficiently high diffusion rate can be fractionated by nonselective deposition methods. Other polymers with low diffusion rates, such as polyethylene, must be selectively deposited by precipitating the high molecular species first. The fractionation, in this case, is done during the deposition step. The reliability of the fractionation has been checked by additional measurements on the fractions with light scattering, osmotic pressure, and sedimentation. Reproducibility was checked by repeated fractionation of the same polymer, by a blend of two polymers with previously determined molecular weight distributions, and by comparison of calculated and observed molecular weight distribution curves. Intergral and differential molecular curves have also been compared to theoretical logarithmic distributions with good agreement. The paper describes some of the limitations of the elution method such as high molecular weight, highly branched polyethylenes. The elution fractionation has been shown to be a reliable method for establishing molecular weight distributions.
Two different polymerization mechanisms of acrylonitrile initiated by γ‐irradiation
Authors: Sobue Hiroshi , Tabata Yoneho
Published: April 2003

The polymerization of acrylonitrile induced by ionizing radiation was investigated in bulk in the temperature range 15 to −196°C. It was found from this investigation that two different mechanisms could exist in the polymerization under the same conditions in different temperature regions. The two polymerization phenomena at room and at very low temperatures were studied from the point of view of radical and ionic polymerization mechanisms. It has been well known that the polymerization at room temperature proceeds by radical mechanism. In the solid state polymerization at very low temperatures the following results were obtained: first, the activation energy is very low, i.e., ca. 0.4 kcal./mole; second, an induction period was not observed under various conditions; third, the monomer containing a radical scavenger was easily polymerized. The authors believe that the facts described above indicate that polymerization in the solid state should proceed by an ionic mechanism.
Chain transfer constants of polyethylene glycol and its dodecyl ether in radical polymerization
Authors: Okamura S. , Katagiri K. , Motoyama T.
Published: April 2003

Chain transfer constants of the end groups (CE) and of the middle portions (CM) of the polymer chain of polyethylene glycol and its dodecyl ether were determined at 60°C. in vinyl acetate polymerization. In the case of polyethylene glycol, CE and CM represent the chain transfer constants of (HOC2H4) and that of (CH2CH2O) which were estimated as 0.004 and 0.0017 respectively, and were compared with the chain transfer constants of propanol and ethanol. The chain transfer constant of the dodecyl radical in polyethylene glycol dodecyl ether is estimated as 0.001, which is in fairly good agreement with that obtained theoretically from the chain transfer constant of the methylene group in acetic esters, but not from that in alcohols. This situation may be attributed to the inhibition of resonance energy transfer by the etherlike oxygen atom.
Phosphines: Chain transfer studies with styrene and methyl methacrylate
Authors: Pellon Joseph
Published: April 2003

The nature of the trivalent phosphorus radical (R2P) was explored through chain transfer studies. The chain transfer constants with styrene and methyl methacrylate were determined at 60°C. for a series of phosphines; namely, the phenyl‐, 2‐cyanoethyl‐, bis(2‐cyanoethyl)‐, and octyl‐compounds. The transfer constants were all greater than one and comparable to those for thiols. The Qtr–etr constants (Alfrey‐Price scheme extended to chain transfer) were calculated and used to discuss structural effects on reactivity. The Qtr–etr parameters for several thiols were also calculated here for the first time and provide additional information concerning their utility. The Qtr–etr values allow the thiols to be compared directly with the phosphines. Comparison indicates that in radical displacements, while both classes are electron acceptors, the phosphines are generally less “electrophilic” than the thiols. The Qtr–etr values for these two important classes of transfer agents permit the transfer constants for these compounds to be calculated with any monomer for which Q–e values are available.
Vinylmercaptobenzothiazole and its polymers
Authors: Kern R. J.
Published: April 2003

2‐Vinylmercaptobenzothiazole (VMBT) may be polymerized to a low molecular weight polymer by using an azo catalyst. Conventional peroxide initiators attack the monomer in nonpolymer forming reactions. VMBT copolymerizes with styrene, acrylonitrile, and methyl methacrylate. Reactivity ratios for VMBT/methyl acrylate were determined to be 1.0 and 0.1. Monomer and polymer were compared in reactions involving oxidation, nitration, nitrogen quaternization, and rearrangement of substituents from sulfur to nitrogen.