bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of hydrogen bonding in poly(vinyl alcohol) by a nuclear magnetic resonance method
Authors: Gupta Ramdas P. , Laible Roy C.
Published: April 2003

The effect of water fixation in poly(vinyl alcohol) yarn has been studied by the NMR method. Water content in the PVA specimen was varied by exposing the specimen to different relative humidity conditions. The NMR wide line spectra have been registered for samples of PVA (a) dried at 80°C. for 24 hr., (b) conditioned to 40% relative humidity, and (c) conditioned to 80% relative humidity. Wide line spectra for the dry specimen of PVA have a broad band only, but the 40% relative humidity conditioned sample has a broad band and a narrow band, and at the same time the sample conditioned to 80% relative humidity has a broad band and two narrow bands. Variation of intensity as a function of water content has been studied. Variation of wide and narrow band intensity shows that at low relative humidity water enters the amorphous and crystalline regions and is held there by the formation of hydrogen bonds. Hydroxyl groups may replace hydrogen atoms at random on a carbon chain without destroying crystallinity. In the amorphous regions water molecules are held relatively free and are accommodated in voids. This would then account for the second peak in the narrow band of the spectrum seen at higher water contents.
Crystal structure of hexagonal polyselenomethylene
Authors: Carazzolo G. , Valle G.
Published: April 2003

The crystal structure of hexagonal polyselenomethylene is described. It has a hexagonal unit cell with a = 5.22 A. and c = 46.25 A. The polymer chains are helices with the helix axis parallel to c. In the identity period of 46.25 A., there are 21 CH2Se units and 11 turns of the helix. The crystal structures of polyoxymethylene, polythiomethylene, and polyselenomethylene are compared.
Ringed spherulite deformation and multiple‐order light scattering from ringed spherulites
Authors: Moore Robert S.
Published: April 2003

Films of low molecular weight linear (LMWL) polyethylene, low molecular weight poly(ethylene adipate), and medium molecular weight linear (MMWL) polyethylene, all of which contained ringed spherulites, were studied by photographic light scattering and by photomicroscopy. The wide‐angle crossed polarizer scattering pattern was observed to consist of a set of arcs if the sample contained uniform well ordered rings, while a diffuse circle was observed as a scattering pattern if the sample contained poorly ordered rings. The first known multiple‐order crossed and parallel polarizer scattering patterns were obtained from samples of LMWL polyethylene and samples of poly(ethylene adipate). Such scattering patterns were not predicted by the theory of Stein and Rhodes for scattering from ringed spherulites. Analysis of these patterns indicates that they are second‐ and third‐order scattering patterns characteristic of the ring spacing. The angular positions of the maxima can be predicted by a generalization of the equation for first‐order ring scattering. The technique of photographic light scattering was also used to study the deformation of ringed spherulites in films of MMWL polyethylene. Results of the light‐scattering measurements indicate that accompanying spherulite deformation there is an increase in the twist distance (and, hence, the ring spacing) of those spherulite fibrils in the direction of tensile stress, and a decrease in the twist distance of those fibrils at right angles to the stress direction. The data are presented and discussed in terms of current theories of spherulite deformation.
Internal motion in organosilicon polymers. I. Linear dimethylpolysilazane
Authors: Model F. S. , Redl G. , Rochow E. G.
Published: April 2003

A linear dimethylpolysilazane polymer has been prepared and its internal motion studied by the techniques of broadline nuclear magnetic resonance. Second moments and line widths are reported as a function of temperature from −196 to 30°C. The results are compared to those for linear dimethylpolysiloxane, as well as to those for the crosslinked siloxane and silazane. The experimental low‐temperature second moment of 7.25 ± 0.5 gauss2 corresponds to a C3 reorientation of methyl groups about the silicon–carbon bond. The motions occurring in the silazane are found to be the same as those in the corresponding siloxane. The transition to low second moments occurs approximately 30°C. higher in the linear silazane than in the linear siloxane. This is attributed to a somewhat greater resistance to motion in the silazane.
γ‐irradiation of siloxane polymers in air and vacuum at several temperatures
Authors: Jenkins Robert
Published: April 2003

The effects of γ‐irradiation on two polysiloxanes in environments of air and vacuum at several selected temperatures were studied. The physical property monitored during the γ‐irradiation of the two polysiloxanes was the change in dynamic modulus which, in turn, is proportional to the change in the number of elastically effective chains in the polymer network. The measurements were accomplished by recording in situ the freeend response of the polymeric cantilever reeds in forced resonance at and near their fundamental frequency of resonance. The apparent energy of activation of crosslinking for the polydimethylsiloxane polymer was found to be 0.56 kcal./mole in vacuum over a limited temperature range, and 3.5 kcal./mole in air. For the polydimethyl‐diphenylsiloxane polymer, the apparent energy of activation was found to be about 1.3 kcal./mole in vacuum, whereas in air the polymer response was complex, displaying both scissioning and crosslinking reactions so that a value could not be obtained. The ability of the pendant phenyl groups to reduce the effective crosslinking rate was found to be sensitive to both temperature and environment.
Room temperature polymerization of glycidol
Authors: Sandler Stanley R. , Berg Florence R.
Published: April 2003

Glycidol has been shown to be easily polymerized at room temperature in the presence of triethylamine, pyridine, lithium hydroxide, potassium hydroxide, sodium hydroxide, sodium methoxide, sodium amide, and other catalysts. Its reactivity with these catalysts is vastly greater than that of propylene oxide. Evidence is presented to support the structural assignment for polyglycidol and the mechanism of polymerization.
Radiation‐induced solid‐state copolymerization of maleic anhydride and acenaphthylene
Authors: Shimizu Akira , Hayashi Koichiro
Published: April 2003

Radiation‐induced solid‐state copolymerization of the maleic anhydride–acenaphthylene system was carried out for the purpose of studying the solid‐state polymerization of vinyl compounds in a binary system. Melting point measurement confirmed that this binary monomer system forms a eutectic mixture in the solid state. The solid‐state polymerization of these monomers proceeds at maximum rate at the eutectic composition, and the polymerization products consist of a mixture of polyacenaphthylene and 1:1 maleic anhydride–acenaphthylene alternating copolymer. Since the 1:1 copolymer was obtained in solution polymerization also and maleic anhydride did not homopolymerize in solid state, it is considered that the solid‐state copolymerization of maleic anhydride and acenaphthylene occurs in a liquidlike state at the boundary of the two monomer crystals.
Isomorphism in copolyamides of long repeating chain units containing oxa‐ and thia‐alkylene linkages
Authors: Saotome Kazuo , Komoto Hiroshi
Published: April 2003

Various copolyamides of long repeating chain units were prepared from hexamethylenediamine (HMDA) and p‐xylylenediamine (PXDA) with aliphatic dicarboxylic acids of three structural types: α,ω‐alkanedioic, α,ω‐oxaalkanedioic, and α,ω‐thiaalkanedioic acids. Both binary and ternary combinations of these dicarboxylic acids having the same number of chain atoms with the diamine afforded highly crystalline copolyamides. In all cases of these copolymers, the plots of the melting points versus the compositions are expressed by linear relations, even in the ternary systems. For example, the melting points of the copolyamides of HMDA with 6‐oxaundecanedioic and 6‐thiaundecanedioic acids are practically unchanged in all ranges of composition. The same relation is also observed in the corresponding copolyamides of PXDA. The relation between the densities and the composition is plotted with good linearity in every case. From x‐ray examination, the lattice spacings of each copolyamide are ascertained to be unchanged by the composition. These results reveal that methylene, ether, and thioether linkages are in the relation of isomorphous replacements for each other in these copolyamide systems. Moreover, the linear relationship between the melting point and the composition is explained by assuming that the entropy of fusion in these copolyamides changes linearly according to the change of the composition.
Polymerization of butene‐2 with isomerization to butene‐1
Authors: Otsu Takayuki , Shimizu Akihiko , Imoto Minoru
Published: April 2003

An attempt has been made to prepare a high molecular weight isotactic polybutene‐1 from cis‐ or trans‐butene‐2. Polymerization of butene‐2 did not occur due to the steric effect of the substituents. In the presence of TiCl3–Al(C2H5)3 catalyst, however, both butene‐2 monomers were found to polymerize at a slower rate than butene‐1 and to give polymers consisting of the repeating unit of butene‐1. From the gas chromatographic determination of the isomer distribution of the butenes recovered after the polymerization, it was found that the butenes isomerized, in the presence of the catalyst system containing TiCl3, to approach the thermodynamic equilibrium mixture of butene‐1, cis‐butene‐2, and trans‐butene‐2. It was also found that the rates of polymerization of butene‐2 for the catalyst systems used were proportional to the isomerization rates. These results show that butene‐2 isomerizes first to butene‐1 which has less steric hindrance and then polymerizes as butene‐1, through ordinary vinyl polymerization by a coordinated anionic mechanism. This type of polymerization was observed in some other linear β‐olefins such as n‐pentene‐2 and n‐hexene‐2.
Studies on Ziegler‐Natta catalysts. Part III. Composition of the nonvolatile product of the reaction between titanium trichloride and trimethylaluminum or dimethylaluminum chloride
Authors: van Looy H. M. , Rodriguez L. A. M. , Gabant J. A.
Published: April 2003

The surface product formed in the reaction between TiCl3 and Al(CH3)3 has been studied. Stoichiometric data, CH3/CD3 exchange, and infrared spectra permit the conclusion that the surface product is essentially a compound having the formula
magnified image
A model structure is proposed for this compound, valid for the 001 face of α‐TiCl3. In it the titanium and chlorine atoms maintain the positions which they occupy in the α‐TiCl3 lattice. One of the methyl groups protrudes from the surface whereas the other occupies the chlorine vacancy created during the reaction in the chlorine surface layer. A different sterism of the methyl groups is compatible with the experimental result that half of the methyl groups are very easily exchanged whereas the other half are not touched by the exchanging agent. According to this model it has to be assumed that the titanium atoms in the 001 plane, by far the largest face of the α‐TiCl3 crystal, are not accessible. A similar model, loading to equivalence conclusions is proposed for β‐TiCl3. The infrared spectra of Al(CH3)3, Al(CD3)3, AlCl(CH3)2, AlCl(CD3)2, AlCl2CH3, AlCl2CD3, TiCl3CH3, TiCl3CD3, Hg(CD3)2, and Zn(CD3)2 are discussed. Spectra of surface products formed on interaction of some of these compounds with TiCl3 are given.
Polymers from vinyl esters of perhydrogenated rosin
Authors: Liepins R. , Marvel C. S.
Published: April 2003

Vinyl esters of tetrahydro acids from perhydrogenated rosin have been homopolymerized; copolymerized with vinyl chloride, vinyl acetate, butadiene; and terpolymerized with styrene and acrylonitrile. Materials containing such vinyl esters of tetrahydro acids can be readily crosslinked with peroxide.
Anionic copolymerization of styrene and 1,1‐diphenylethylene
Authors: Ureta E. , Smid J. , Szwarc M.
Published: April 2003

Kinetics of anionic copolymerization of styrene (S) and 1,1‐diphenylethylene (D) were investigated in THF. The rate constant of addition of D to living polystyrene was found to be k1,2 ± = 250 l./mole‐sec. for , Na+ ion‐pair, and that for the free , Na+ ion is k1,2−∼400,000 l./mole‐sec. Both values refer to 25°C. The addition of styrene to D−, Na+ was found to be reversible:
magnified image
and k2,1 was determined by three different methods to be ∼0.5–0.7 l./mole‐sec. Studies performed in a stirred‐flow reactor led to k‐21 = 13 sec. −1 and K21 ∼ 5 × 10−2 l./mole. An alternating copolymer is obtained in the presence of a large excess of 1,1‐diphenylethylene.
Polyelectrolytic character of amylose. I.
Authors: Doppert H. L. , Staverman A. J.
Published: April 2003

Electrophoresis and titration experiments on amylose solutions and gels are described. The experimental results clearly demonstrate the negative charge of the amylose molecules at pH values of 11 and higher. With the assumption that a monomer unit can carry one charge only, pK's of amylose are calculated. The agreement between the pK's of amylose and glucose forms an indication that hydroxyl groups dissociate in the above‐mentioned pH range.
Cyclo‐ and cyclized diene polymers. XII. Cationic polymerization of isoprene
Authors: Gaylord N. G. , Matyska B. , Mach K. , Vodehnal J.
Published: April 2003

Polymerization of isoprene with Lewis acids in n‐heptane is a process leading to a quasiequilibrium which is characterized by very low conversions. Polymerization rates in aromatic solvents are much higher due to extensive chain transfer with solvent with regeneration of the original active centers. The rate of monomer disappearance in benzene or toluene when aluminum bromide is the catalyst is second order with respect to monomer concentration. The reaction order with respect to the catalyst depends on the reaction conditions; at constant monomer concentration it is approximately one. Polymerization rates in halogenated solvents with the use of syringe techniques are much higher than those in aromatic solvents. Polymers obtained with various cationic catalysts ranged from oils to white powders having molecular weights up to more than 100,000 depending on reaction conditions. All polymers exhibited infrared spectra characteristic of cyclopolydienes, and the content of linear structures usually did not exceed 20%, irrespective of the nature of the catalyst or solvent. In solvents of higher polarity, such as o‐dichlorobenzene, more linear structures were detected. Among residual linear forms the trans‐1,4 addition was found to prevail. Residual unsaturation in polymers did not exceed 30%.
Kinetic study of heterogeneous polymerizations of styrene and/or β,β‐d2‐styrene by Ziegler‐Natta catalysis
Authors: Simon A. , Jarovitzky P. A. , Overberger C. G.
Published: April 2003

Substantial concentrations of tetravalent titanium have been shown to exist in a TiCl4—Al(C2H5)3—benzene catalytic system for catalyst aging times ≥ 20 min. at 60°C. Substitution of β,β‐d2‐styrene for styrene with the above catalysic system appears to have no effect on either rate of polymerization or product intrinsic viscosities. These phenomena support a mechanism of chain propagation and termination as suggested earlier.
ESR study of free radicals formed by γ‐irradiation of poly(ethylene terephthalate)
Authors: Campbell D. , Araki K. , Turner D. T.
Published: April 2003

Free radicals formed by γ‐irradiation of oriented samples of poly(ethylene terephthalate) (PET) were studied at 25°C. by ESR spectroscopy. The G value for trapped free radicals is 0.02. The predominant radical is identified as $\text{O} - \text{\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{C} H} - \text{CH}_\text{2} - \text{O} -$, and a minor component of the spectrum is tentatively assigned to the radical COĊ6H3CO. The absence of cyclohexadienyl type radicals is discussed. Previously reported dose rate effects in PET are explained by reference to a chain reaction involving β‐bond scission of the radical $\text{O} - \text{\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{C} H} - \text{CH}_\text{2} - \text{O} -$.
Alternation Tendency in Copolymerization
Authors: Tada Koichi , Fueno Takayuki , Furukawa Junji
Published: April 2003

The number fractions of the alternate diads and triads and the average length of the alternate sequence may be used as the indices of the alternation tendency of binary copolymerizations. It is shown that these indices take on maximum values when the monomer feed ratio is such that [M1]/[M2] = (r2/r1)1/2. The physical significance of the customary measure of the alternation tendency r1r2 is discussed.
Elastic properties and network structure in silicone gum vulcanizates
Authors: Bobear W. J.
Published: April 2003

A model of a rubber network formed from finite, linear polymer chains is treated, using expressions from accepted elastic theory as well as relationships that have been less generally used or only implied. The resultant empirical mathematical expressions conform very closely to the predictions of the simple kinetic theory of rubber elasticity and are mathematically consistent, in that the major properties and measurements are interrelated, and apparent inconsistencies in the literature are reconciled. As a consequence, an empirical equation is developed for the relationship between elastic properties and network structure in silicone gum vulcanizates. This equation is then applied to the estimation of peroxide crosslinking efficiencies.
Kinetic and equilibrium phenomena in the system: Acetone vapor and polycarbonate film
Authors: Kambour R. P. , Karasz F. E. , Daane J. H.
Published: April 2003

Amorphous films of Lexan polycarbonate have been exposed to acetone vapor at controlled temperatures and partial pressures in order to study sorption kinetics and thermodynamics and polymer crystallization behavior. Sorption isotherms show a discontinuity is slope at or near the depressed glass transition, which itself was identified by torsion pendulum measurements. Crystallization abruptly begins to occur at partial pressures equal to or slightly above that of the solubility transition and is manifested by delayed desorption and whitening phenomena. In this process 20% crystallinity is usually developed, as measured by calorimetry which, however, produces a 40% drop in acetone solubility. Although the depressed glass temperature is near 0°C. in saturated atmospheres—a drop of 145°C.—the melting point is only depressed 60 or 70°C. Such disparity probably accounts for the enhanced polycarbonate crystallization rate in acetone over that in the dry bulk polymer above the normal Tg.
Relaxation phenomena in concentrated polyelectrolyte solution. II
Authors: Nishida Noboru
Published: April 2003

Dynamic viscoelastic properties of 10 and 20% aqueous solutions of sodium polyacrylate were studied by the electromagnetic transducer method at 500 cps in the temperature range of 0–50°C. These solutions distinctly showed a relaxation phenomenon in this temperature range which was also affected by addition of such compounds as sodium chloride, urea, and dioxane. An anomalous behavior that cannot be explained as due to the relaxation phenomenon was observed on the addition of small amounts of these agents. One of the causes of this behavior is ascribed to the ion association in the solution. The static viscosity of the solution was also measured by using a rotating cylinder viscometer and the results compared with the dynamic data.
Light‐scattering study of the molecular weight distribution of polypropylene
Authors: Carpenter Dewey K.
Published: April 2003

A light‐scattering study is presented of two isotactic polypropylene samples with broad molecular weight distributions (Mw/Mn = 8.1 and 8.7, respectively) dissolved in α‐chloronaphthalene at 147°C. Incident radiation of 5460, 4358, and 3650 A. was used. The reciprocal intramolecular scattering function, P−1(u) is expressed as a function of the variable [sin(θ/2)/λ′]2. This provides a wider range of experimental values of the variable u = 16π2(b2/6) [sin(θ/2)/λ′]2 than is accessible by the usual technique of using only one wavelength. The shape of the function P−1(u) is closer to that predicted theoretically if the weight distribution function f(N) in the equation

is given by the log‐normal distribution rather than the distribution function of Schulz and Zimm. The method is applicable to polymer samples for which the average molecular weights are too low to be measured by the light‐scattering method of Benoit and Loucheux.
Redox‐initiated vinyl polymerization with thiourea as the reductant
Authors: Mukherjee Asish R. , Pal Runu , Amarendra  , Biswas M. , Maiti Sukumar
Published: April 2003

A few redox systems containing thiourea as reductant have been found to be quite effective in initiating vinyl polymerization in aqueous media and polymers obtained in the process have all been found to contain amino endgroups to various extents by the application of dye techniques. Quite a few oxidants have so far been utilized for this purpose; among them are ferric chloride (Fe3+), ethylene dibiguanide complex salts of tripositive silver (Ag3+), hydrogen peroxide (H2O2), persulfate (S2O82−), bromate (BrO3−) + hydrochloric acid (HCl). In case of oxidants Fe3+ and Ag3+, amino endgroups are mainly incorporated in polymers; but in case of oxidants H2O2 and S2O82−, fragments of oxidants are also incorporated as hydroxyl and sulfate endgroups. BrO3−, however, forms a very efficient redox‐initiating system with thiourea, as is evidenced by its capability of polymerizing even hydroquinone‐stabilized water‐soluble vinyl monomers at very low temperature (∼0°C.) and at a quite rapid rate. Besides amino endgroups, sulfonate endgroups have also been detected in polymers in this case, and the relative extents of these two types of endgroups depend generally on the acid concentration of the system. Evidences so far collected indicate the generation of SC(NH)NH2 radicals in the system by oxidation of isothiourea, HSC(NH)NH2, and these are incorporated in polymers as endgroups. Sulfonate endgroups may be generated by oxidation of these amino‐bearing endgroups. Suitable initiation mechanisms have been suggested in each case.
High‐pressure reactions. III. Hydrolysis of polyacrylonitrile
Authors: Prince M. , Hornyak J.
Published: April 2003

Polyacrylonitrile prepared from γ‐irradiated monomer was found to react readily with water over a pressure range of 5,130–34,200 atm. to yield polyacrylamide, while polymer prepared by conventional free‐radical catalysts will not hydrolyze under the same conditions. Reaction rates at 85°C. were measured; hydrolysis was extremely rapid at higher temperatures. Results are presented to indicate the radical nature of the reaction. Addition of a free‐radical source increases the amount of hydrolysis. Pressure has an effect on the properties of the resulting polyacrylamide.
Emulsion polymerization of acrylonitrile. Part II. Mechanism of emulsion polymerization of acrylonitrile
Authors: Izumi Zenzi
Published: April 2003

The mechanism of emulsion polymerization of acrylonitrile has been studied by measuring by dilatometry and electron microscopy the adsorption of monomer into polymer particles and polymerization characteristics such as rate, degree of polymerization, the growth of the particle during polymerization, and the degree of dispersion. In the emulsion polymerization of acrylonitrile, new particles are formed during polymerization at a rate which is proportional to the rate of polymerization and the ratio of unreacted monomer. The total amount of monomer adsorbed on or in the polymer particles is rather small, but the concentration on or in the polymer particles is sufficiently high and proportional to the monomer concentration in aqueous phase. The polymerization proceeds concurrently on or in the polymer particles and in aqueous phase, but the three loci may be continuous rather than discrete. A reaction scheme is introduced here which shows the coexistence of polymerizations on or in the polymer particles and in the aqueous phase.
Phenyl‐substituted polyquinoxalines
Authors: Hergenrother Paul M. , Levine Harold H.
Published: April 2003

Four phenyl‐substituted polyquinoxalines have been prepared by the reaction of combinations of two tetraamines, 3,3′‐diaminobenzidine and 3,3,′4,4′‐tetraaminodiphenyl ether, with two bisbenzils, 4,4′‐dibenzil and 4,4′‐oxydibenzil. The polymers were prepared by melt and solution polymerizations. Melt condensations were performed at 180, 220, and 280°C. and samples were periodically removed and characterized. The solution polymerizations consisted of two stages, initially forming an intermediate molecular weight polymer (ηinh 0.6–1.0) which was advanced at 400°C. to final polymer (ηinh 1.5 to 2.2). Clear yellow films, cast from m‐cresol solution, exhibited good toughness and flexibility. The phenyl‐substituted polyquinoxalines exhibited excellent oxidative and thermal stability. Polymer decomposition temperatures in air were generally about 550°C. Isothermal aging at 371°C. (700°F.) in air showed weight retentions as high as 93 and 50% after 100 and 200 hr., respectively. Weight‐average molecular weight determination by light‐scattering technique on a polymer with an ηinh of 2.16 suggested a value of 247,000. Certain physical properties of the phenyl‐substituted polyquinoxalines are compared with those of the corresponding ordinary polyquinoxalines to illustrate the advantageous effect of introducing a phenyl group on the quinoxaline ring.
Comments on the theories of the intrinsic viscosity of chain polymers
Authors: Isihara A.
Published: April 2003

The theory of intrinsic viscosity developed recently by the present author is examined and compared with experiments and the theories by Peterlin, Kirkwood and Riseman, Brinkman, and Debye and Bueche. The fundamental assumptions and essential approximations in the theories are criticized.
Synthesis and properties of polyimidazopyrrolones
Authors: Bell Vernon L. , Jewell Robert A.
Published: April 2003

The preparation of polyimidazopyrrolones by three general synthetic methods has been presented. The effects of structure, conversion temperature, and conversion environment were determined. The polyimidazopyrrolones were shown to retain useful mechanical properties at elevated temperatures, after severe chemical treatment and after unusually high exposure to ionizing radiation. Thermogravimetric analysis of the polymers indicated the effect of structure on oxidative stability was relatively minor; furthermore, the relative stabilities of a series of eight polymers in air were not directly comparable to the order of stability in a vacuum environment.
Elastic behavior, birefringence, and swelling of amorphous polyethylene networks
Authors: Gent A. N. , Vickroy V. V.
Published: April 2003

Polyethylene networks were prepared by γ‐irradiation of linear polyethylene, both molten and crystalline. The elastic and photoelastic properties of the networks were studied at high temperatures, i.e., in the molten state. The equilibrium swelling was also measured in several solvents. Values of the crosslinking efficiency G of γ‐radiation, the molecular, weight Me between entanglements, the optical anisotropy α of the equivalent random link, and the polymer‐solvent interaction parameter μ are deduced. Samples prepared by irradiation in the amorphous state showed markedly non‐Gaussian elastic behavior. The presence of a large non‐Gaussian term in the optical anisotropy is also deduced. The value of α obtained for swollen samples, which showed substantially Gaussian elastic behavior, was 3.9 × 10−24 cm.3, about one‐half of that obtained for dry samples. It corresponds to an equivalent random link of only about 5 CH2 units, on the basis of Denbigh's values for bond polarizabilities. The samples prepared by irradiation in the crystalline state showed lower values for α, which also depended upon the degree of crosslinking. This is attributed to the nonrandom chain configurations prevailing at the time of crosslinking. The same samples were found to show more nearly Gaussian elastic behavior, which is attributed to the same cause.
Annealing and melting of poly‐4‐methylpentene‐1 single crystals
Authors: Morrow D. R. , Richardson G. C. , Kleinman L. , Woodward A. E.
Published: April 2003

The effects of thermal treatment at temperatures in the 177–250°C. range for 2 hr. on solution‐grown single crystals of poly‐4‐methylpentene‐1 have been studied by using electron microscopy. Crystals were grown both from 0.02% pentyl acetate solution at 110°C. and from 0.02% toluene solutions at temperatures less than 80°C. A number of distinct types of crystals have been obtained in the same or in separate solutions depending on the crystallization conditions. These crystals have some morphological characteristics in common such as a square outline with well‐defined faces. The contrasting features include such things as a marked difference in relative size, with the smaller crystals showing extensive overgrowth and collapse markings. Observations by means of differential scanning calorimetry (DSC) on the melting behavior of these various crystals show the presence of distinct and characteristic melting points. The effects of a given thermal treatment depend on the type of crystals used, with the larger crystals showing greater stability. The first effects are the appearance of lines, notches at the edges, and holes. An increase in temperature results in an increase in these effects with the formation of fibrillar structures. Consideration is given to the influence of molecular conformation and molecular chain folding on the observed results.
Temperature‐dependent x‐ray small‐angle scattering from melt‐crystallized polyethylene
Authors: Schultz J. M. , Robinson W. H. , Pound G. M.
Published: April 2003

The temperature dependence of x‐ray small‐angle scattering from fractionated linear polyethylene crystallized from the melt was determined experimentally over a range of temperatures from room temperature to the melting point. It was found in general that only the most intense of the several small‐angle peaks exhibited a thermally dependent behavior. Below the crystallization temperature this peak increased in intensity with temperature, at constant peak position. Recrystallization was manifest in a discontinuous shift of the peak. During isothermal crystallization, the peak intensity first increased, then decreased, with time. It is concluded from supplementary electron microscopy and from the behavior of the peak that its position reflects the period of stacking of lamellae and that its intensity is controlled primarily by the thickness of the layer separating lamellae. The reversible peak intensity effect is attributed to an entropydriven growth of the interlamellar layer at the expense of the crystalline lamellae. The intensity effects observed during crystallization are associated with the primary and secondary phases of crystallization. Lamellar surface free energies were computed from melting point observations and were found to increase with molecular weight.
Gel permeation chromatography of polyethylene: Effect of long‐chain branching
Authors: Wild L. , Guliana R.
Published: April 2003

The effect of long‐chain branching on the size of low‐density polyethylene molecules in solution is demonstrated through solution viscosity and molecular weight measurements on fractionated samples. These well‐characterized fractions are analyzed by gel permeation chromatography (GPC), and it is shown that the separation of the polymer molecules by this technique is sensitive to the presence of long‐chain branching. By using fractions of branched polyethylene possessing differing degrees of branching, one observes that a single curve is adequate in relating elution volume to molecular weight. This calibration curve is applied in the GPC analysis of a variety of commercial low‐density polyethylene resins and it is shown, by comparison with independent osmometric and gradient elution chromatographic data, that realistic values for molecular weight and molecular weight distribution are obtained. The replacement of molecular weight M by the parameter [η]M as a function of elution volume, leads to a single relationship for both linear and branched polyethylenes. This indicates that GPC separation takes place according to the hydrodynamic volumes of the polymer molecules. The comparison of data for polyethylene and polystyrene fractions suggests that this volume dependence of the separation will be observed for other polymer–solvent systems.
Melting temperature of trans‐polyoctenamer
Authors: Calderon Nissim , Morris Marion C.
Published: April 2003

The effect of microstructure on crystallizability of polyoctenamers prepared by R3Al‐WCl6 catalyst was studied. The results indicate that polyoctenamers with a broad range of trans‐vinylene content do crystallize. The measured melting points are dependent on the trans‐vinylene content. From the dependence of melting temperature on copolymer composition, a value of 73 ± 2°C. for the melting point and a molar heat of fusion ΔHu of 3520 cal./mole are calculated for 100% trans‐polyoctenamer. From the melting point depression in the presence of diluent, a value for ΔHu of 4800 cal./mole is obtained.
Light‐scattering study of polyacrylonitrile solution
Authors: Shibukawa Takashi , Sone Masao , Uchida Akiyoshi , Iwahori Kimihiko
Published: April 2003

Light‐scattering measurements of polyacrylonitrile (PAN) prepared by aqueous suspension polymerization and solution polymerization were made in both dimethylformamide (DMF) and γ‐butyrolactone (γ‐BL). The following relations between the intrinsic viscosity [η] (in deciliters per gram) and the weight‐average molecular weight were obtained: [η] = 3.35 × 10−4 M̄w0.72 (in DMF at 30°C.) and [η] = 4.00 × 10−4 M̄w0.69 (in γ‐BL at 30°C.). The relation in DMF is in agreement with the results of many other researchers, but differs from the results of Bisschops et al. and Peebles. Analysis of the results by the recent viscosity theory reported by Inagaki et al. indicates that the steric factor σ is 2.17 on PAN in both DMF and γ‐BL. It is found that the root‐mean‐square radius of gyration of the chain measured by light scattering 〈S2〉w1/2 (LS) is in good agreement with the root‐mean‐square radius of gyration of the chain calculated by using the viscosity theory of Inagaki et al. 〈S2〉w1/2 (vis) in both DMF and γ‐BL.

Relations between the root‐mean‐square radius of gyration of the chain (in Angstroms) in DMF and γ‐BL and the molecular weight were obtained: 〈S2〉w1/2 = 7.94 × 10−2 M̄w0.66 (in DMF) and 〈S2〉w1/2 = 2.19 × 10−1 M̄w0.57 (in γ‐BL). From the estimation of the second virial coefficient A2 and the value of B obtained from viscosity theory, it is found that DMF is a better solvent than γ‐BL.
Morphological changes of twisted nylon 66 and poly(ethylene terephthalate) monofilaments
Authors: Cooper S. L. , McKinnon A. J. , Prevorsek D. C.
Published: April 2003

A comparison of the x‐ray diffraction from twisted nylon 66 and poly(ethyleneterephthalate) monofilaments is made with the scatter predicated by a model assuming an affine deformation of the fiber. The x‐ray diffraction of the model is characterized by an approximately constant intensity over the entire range of the azimuthal dispersion. With twisted nylon 66 fibers the (010) reflection is split into a bimodal intensity distribution about the equator, while the (100) reflection maintains a distinct maximum on the equator. It is proposed that this difference is due primarily to the fact that a plastic deformation involving rotation of crystal planes occurs more readily when the shear stress acts in [010] direction than in the case when it acts in the [100] direction. A similar behavior is found with poly(ethylene terephthalate) fiber.
Aminimides. IV. Homo‐ and copolymerization studies on trimethylamine methacrylimide
Authors: Culbertson B. M. , Slagel R. C.
Published: April 2003

Trimethylamine methacrylimide (TAMI) has been homo‐ and copolymerized with methyl methacrylate, vinyl acetate, vinyl chloride, hydroxypropyl methacrylate, and acrylonitrile by free‐radical initiators to soluble, low molecular weight polymers containing pendant aminimide groups along the backbone of the polymer chains. The reactivity ratios in the copolymerization of TAMI (M1) with acrylonitrile (M2) were determined: r1 = 0.10 ± 0.01, r2 = 0.37 ± 0.04. The Alfrey‐Price Q and e values for TAMI were also calculated: Q = 0.18, e = −0.60. This preliminary work indicates that TAMI has potential for the preparation of reactive polymers.
Solution properties of cellulose triacetate. II. Solubility and viscosity studies
Authors: Howard P. , Parikh R. S.
Published: April 2003

The solubility of cellulose triacetate in a range of solvents was measured, and the results for tetrachloroethane, chloroform, and acetic acid were compared with those from initial phase separation in solvent–nonsolvent mixtures and viscosity–concentration studies. The correlation found between solubilities, precipitation values, and values of the Huggins viscosity constant is discussed with reference to the type of polymer–solvent interaction proposed previously to explain fractionation behavior. A qualitative comparison of solubility–swelling behaviour was also made for a very low molecular weight cellulose triacetate sample in a wide range of solvents. Results are compared with those for higher molecular weight samples and discussed with regard to the cohesiveenergy densities of solvent and polymer. Some attempt has been made to predict suitable solvents for cellulose triacetate, based on consideration of their molecular structures.
Emulsion polymerization. IV. Experimental verification of the theory based on slow termination rate within latex particles
Authors: Gardon J. L.
Published: April 2003

A large body of data shows that the time dependence of conversion fits the equation P = At2 + Bt in the interval where, according to the Smith‐Ewart model, the relationship should be linear. For latexes of very small particle size the Smith‐Ewart linear relationship (P = Bt) is often observed, and for latexes of very large particle size the conversion was found to be proportional to t2. The experimental value of parameter B was in good agreement with independent theoretical predictions. From A and B the ratio between termination and propagation constants was calculated and was in the 5–200 range. Independent estimates of this ratio give the same order of magnitude. These independent estimates are from the literature and are obtained from the increase in conversion rate at catalyst post‐addition during emulsion polymerization or from emulsion polymerization initiated by intermittent irradiation or from homogeneous polymerization in the presence of inert polymers of high viscosity. The conversion–time curves describing the whole conversion process generally have sigmoid shape. The molecular weight is often found to pass through a maximum as the conversion increases. In one experiment this maximum coincided with the calculated maximum in the average number of radicals per particle Q. The variation of experimental molecular weights with conversion accurately followed the theoretical predictions. The deviation from the Smith‐Ewart model was often significant. The value of Q was not 0.5, as the Smith‐Ewart model requires it to be, but often reached values much larger, as large as 10. The particle size distribution broadened with increasing conversion and became increasingly skew. Numerous data taken from the literature are in good quantitative or qualitative agreement with the theory proposed in Part III and for these data the observed deviations from the Smith‐Ewart theory are readily explainable. The new data obtained with styrene, n‐butyl methacrylate, and methyl methacrylate are also in quantitative agreement with the new theory. One experiment involving methyl methacrylate is analyzed in great detail. The variation of time, of Q, of molecular weight, of average particle size, and of particle size distribution with conversion are reported. The molecular weight distribution is also calculated from the conversion dependence of molecular weight.
Polymerization of isocyanates. IV. Polymerization by aqueous initiator systems
Authors: Iwakura Yoshio , Uno Keikichi , Kobayashi Norio
Published: April 2003

Isocyanates were polymerized by aqueous solutions of numerous alkali salts at a low temperature. Polymer could be obtained even in the presence of a large excess of water to monomer in the polymerization system. The initiating species was proposed to be hydroxide ion.
Polymerization of D‐α‐methylbenzyl methacrylate by n‐butyllithium and the tacticity and optical rotation of the polymer
Authors: Yuki Heimei , Ohta Koji , Uno Katsuhiro , Murahashi Shunsuke
Published: April 2003

D‐α‐Methylbenzyl methacrylate, [α] = +51.3° (neat), was polymerized by n‐butyllithium in toluene–tetrahydrofuran mixtures of various solvent ratios at −78°C. The polymers obtained were converted into poly(methyl methacrylate)s, which were analyzed for tacticity by high resolution NMR spectroscopy. A linear relationship was obtained between the optical rotation and the isotacticity of poly(D‐α‐methylbenzyl methacrylate). The extrapolation of the data gave +120° and +99° for [α] of the fully isotactic and syndiotactic polymers, respectively. The copolymerization of the D‐ and L‐isomers in toluene gave copolymers which were less isotactic than the homopolymer of the D‐isomer. The optical rotation of the copolymer was proportional to the excess of one isomer in the polymer.
Studies on the tacticity of polyacrylonitrile. III. NMR spectra of stereoisomers of 2,4,6‐tricyanoheptane as model compounds of polyacrylonitrile
Authors: Murano Masao , Yamadera Reizo
Published: April 2003

The three stereoisomers of 2,4,6‐tricyanoheptane were separated and their NMR spectra were studied as the three‐unit model compounds of polyacrylonitrile. The chemical shifts and coupling constants obtained from the NMR spectra were compared to those of the two‐units model compounds. The geminal protons for the isotactic methylene are not equivalent, but the difference of the chemical shifts is smaller than that in the meso two‐unit model. The racemic methylene signals appear at higher field than the meso methylene in the heterotactic three‐unit model as in the case of the racemic and the meso two‐unit models. The signals of the methinic protons in triads appear in the order: isotactic CH, heterotactic CH, and syndiotactic CH from the high field. From the observed values of the vicinal coupling constants, the chain conformations of the model compounds are also discussed.
Structure and reactivity of α,β‐unsaturated ethers. III. Cationic copolymerizations of alkenyl alkyl ethers
Authors: Okuyama T. , Fueno T. , Furukawa J. , Uyeo K.
Published: April 2003

The relative cationic polymerizabilities of the geometrical isomers of various alkenyl alkyl ethers were studied both in copolymerizations with each other and in their respective copolymerizations with vinyl isobutyl ether as standard. Copolymerizations were carried out in methylene dichloride at −78°C. with boron trifluoride etherate as catalyst. The cis isomers have been found to be more reactive than the corresponding trans isomers. A primary alkyl substituent on the β‐cis position of vinyl ethyl ether enhances the reactivity. Yet the steric effect is noticeable when the substituents are bulky. Compounds substituted with cis‐β‐isobutyl and with β‐dimethyl showed little tendency to homopolymerization. It was proved that the polymer ends derived from cis and from trans monomers are respectively different in character because of the restricted rotation of the end unit around the terminal carbon–carbon bond. The alternation tendency, remarkable in the copolymerization of cis monomers with vinyl ether, was explained in terms of the cis‐opening mechanism.
Homopolymers and copolymers of vinyl ethers of rosin‐derived alcohols
Authors: Fukuda Wakichi , Saga Motoo , Marvel C. S.
Published: April 2003

Two vinyl ethers of rosin‐derived alcohols were homopolymerized with free‐radical and cationic initiators. A polymer was obtained from the vinyl ether of the alcohol from Foral in good conversion by free‐radical initiators but it was not a high molecular weight product. Cationic initiators were more effective; boron trifluoride etherate proved to be best. All of the homopolymers were obtained as white powders with high crystallinity. Copolymerizations of the vinyl ethers and vinyl chloride have been studied with the use of free‐radical initiators. Cationic‐initiated copolymers of the vinyl ethers and isobutyl vinyl ether were studied. Those containing less than 20% of the rosin vinyl ethers were rubbery, of high molecular weight, and could be crosslinked with peroxide.
Radiation grafting of vinyl monomers to wool. III. Location of the grafted polymer
Authors: Ingram P. , Williams J. L. , Stannett V. , Andrews M. W.
Published: April 2003

Studies of properties such as water sorption of grafted wool have shown the importance of the location of the polymer in the fiber. Electron microscopy and low‐angle x‐ray diffraction studies have been used to determine the location of grafted polystyrene in wool. Samples grafted from 15 to 800% (dry weight increase) all exhibit a large increase in contrast in the cell membranes (IR) and nuclear‐remnant regions (NR) in the electron micrographs. This is considered to be due in part to an unevenness in mechanical response to sectioning and in part to the deposition of ungrafted homopolymer in IR and NR, particularly at grafts of greater than about 100%. Analysis of the change in the 83 A. equatorial x‐ray reflection suggests that most of the grafted polymer resides in the keratinous matrix regions between the microfibrils within the cortical cells. At larger grafts the wool still retains its basic histological character, but the increase in this spacing is no longer proportional to the amount of graft, and the desposition of polymer becomes very inhomogeneous.
A tracer study of the hydrolysis of methyl methacrylate and methyl acrylate units in homopolymers and copolymers
Authors: Baines F. C. , Bevington J. C.
Published: April 2003

Homopolymers and copolymers were prepared from methyl methacrylate, methyl acrylate, and styrene by radical reactions at 60°C. Monomers suitably labeled with carbon‐14 were used so that it was possible to monitor the hydrolysis of ester groups in the polymers during treatment under alkaline conditions. It was found that methyl acrylate units were hydrolyzed completely whatever their environment in a polymer chain. Under the same conditions only about 9% of the ester groups in a homopolymer of methyl methacrylate reacted; the proportion was increased by the introduction of comonomer units into the polymer chain. For copolymers of methyl methacrylate with methyl acrylate the extent of reaction may be correlated with the lengths of the sequences of methyl methacrylate units.
Studies on the charge transfer complex and polymerization. XVI. Spontaneous copolymerization of cyclopentene and sulfur dioxide
Authors: Iwatsuki Shouji , Okada Tsuneyoshi , Yamashita Yuya
Published: April 2003

The alternating copolymerization of cyclopentene and sulfur dioxide was studied. It takes place spontaneously at −15°C. The rate of copolymerization in toluene was found to be proportional to [CPT]3 and [SO2]2 with the overall activation energy of 16.5 kcal/mole. Terpolymerizations with eight different third monomers were carried out to examine the character and behavior of the copolymerization system of CPT and SO2. However, the polymerizations with styrene and methyl methacrylate as the third monomers were found to be extraordinary, in that all the three components are not incorporated into the polymer chain.