bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nylon single crystals
Authors: Geil P. H. 
Published: April 2003

AbstractSeveral polyamides crystallize from dilute glycerin solution as single crystals and spherulites possessing a lamellar structure. The crystal of nylon 6 are rhombohedral and thicken by spiral growth of lamellae from screw dislocations. Electron diffraction patterns indicate that the molecules are folded within the lamellae, which are 50–100 A. thick. The single‐crystal electron diffraction spacings correspond to those of the high‐temperature crystalline modification as determined by x‐ray diffraction. The unit cell, however, does not show the hexagonal symmetry generally ascribed to the high‐temperature lattice. Spherulites of nylon 6 are composed of fragmented lamellae in which the molecules are folded and are in the low temperature crystalline lattice. Preparations of nylon 66 and 610 contain structures consisting of single‐crystal lamallae rolled or folded together. These structures also thicken by spiral growth of the lamallae from screw dislocations. The molecules are folded and are in the low‐temperature lattice, although there is some evidence of the high‐temperature modification with nylon 610.
The concentration dependence of the self‐diffusion coefficients of strontium ion in aqueous polystyrenesulfonic acid solutions
Authors: Hardy E. P. , Steigman J. 
Published: April 2003

AbstractThe diffusion coefficients of strontium in 10−4M aqueous solutions of polystyrenesulfonic acid were measured at 26°C. The coefficients were low, about 0.15 X 10−5 cm.2/sec., until strontium equivalent to one‐fifth of the sulfonates had been added. They then increased relatively rapidly, to about 0.7 X 10−5 cm.2/sec., as the concentration of strontium was increased to 10−4M. These results are interpreted to mean either that the binding of counterions to a polyelectrolyte is limited to parts of a chain and is not related to the chain as a whole, or else that there is a recurring regularity of structure in the atactic polystyrene sulfonic acid which limits binding of counterions to a fraction of the total charged sites.
The use of infrared spectra in the preparation and characterization of vinylcycloalkanes
Authors: Borchert A. E. , Overberger C. G. 
Published: April 2003

AbstractThe purpose of this paper is to report the application of infrared spectroscopy to the preparation and polymerization of vinylcyclopropane, vinylcyclopentane and vinylcyclohexane. Carbon‐hydrogen stretching frequencies in the 3005 and 3080‐cm. −1 regions were utilized in the evaluation of products and reactions. Precursors to vinylcyclopropane and these bands afforded independent evidence for the retention of the three‐membered ring in crystalline polyvinylcyclopropane. Absorptions characteristic of the cyclopentyl and the cyclohexyl groups were found to be of less utility in the analysis of processes leading to crystalline polyvinylcyclopentane and crystalline polyvinylcyclohexane, while bands in the 3020–3081‐cm. −1 region aided the establishment of type and location of unsaturation in several monomers.
Effect of type of catalyst on structure of poly(β‐vinyloxyethyl methacrylate)
Authors: Lal Joginder , Devlin E. F. , Trick G. S. 
Published: April 2003

AbstractInfrared analysis and glass transition temperature measurements on the polymers obtained from β‐vinyloxyethyl methacrylate with stannic chloride (cationic) and titanium tetrachloride–triisobutyl aluminum (Ziegler‐type) catalysts indicate that these polymers have essentially the same structure, comprising a polyvinyl ether backbone with pendant methacrylatoethyl groups. The polymer obtained with lithium–tributylamine (anionic) catalyst has a different structure involving a methacrylate backbone with vinyloxyethyl pendant groups. These data suggest that in the polymerization of this monomer with the Ziegler‐type catalyst the mechanism of polymerization is cationic. Polymerization with triethylboron gives a crosslinked material similar in structure to the peroxide‐catalyzed polymer.
Polymyrcene
Authors: Marvel C. S. , Hwa Charles C. L. 
Published: April 2003

AbstractMyrcene has been polymerized by treatment with triisobutylaluminum and titanium tetrachloride, triisobutylaluminum and vanadium trichloride, and by free radical initiation in emulsion systems. The polymers thus obtained vary in molecular weight range but all have a predominantly 1,4‐arrangement of the diene unit in the polymer chain. It is not possible to say whether this is a cis or trans structure on the basis of present information. Different samples of the polymyrcene obtained by the action of triioso‐butylaluminum and vanadium trichloride have inherent viscosities of 2 to 5.5. Myrcene polymerized by boron trifluoride etherate appears to have a cyclic recurring unit and is probably identical in structure with polymers prepared from β‐pinene by cationic initiation.
Polyurethanes. I. The solution polymerization of diisocyanates with ethylene glycol
Authors: Lyman Donald J. 
Published: April 2003

AbstractContrary to statements in the literature, it was found that useful polyurethanes could be prepared by the reaction of a diisocyanate with ethylene glycol. In this investigation m‐phenylene diisocyanate, p‐phenylene diisocyanate, 2, 4‐toluene diisocyanate, methylene bis(4‐phenyl isocyanate), durene diisocyanate, biphenylene diisocyanate, bis(4‐isocyanatophenyl) sulfone, 4,4′‐diisocyanatodiphenyl ether, 3,3′‐dimethyl‐4,4′‐biphenylene diisocyanate, and 1,5‐naphthalene diisocyanate reacted with ethylene glycol in solution to give the corresponding polyurethanes. The reaction of methylene bis(4‐phenyl isocyanate) with ethylene glycol in dimethyl sulfoxide/4‐methylpentanone‐2 (50/50) gave a high molecular weight, linear polyurethane that could be solvent‐cast into films and dry‐spun into fibers. These films and fibers showed properties similar to those of existing commercial films and fibers.
The polymerization of allylbenzene with heterogeneous catalysts
Authors: D'Alelio G. F. , Finestone A. B. , Taft L. , Miranda T. J. 
Published: April 2003

AbstractData are presented for the preparation of high molecular weight and crystalline polymers of allylbenzene. With specific cationic catalysts, low molecular oligomers of β‐methylstyrene are produced. With anionic catalysts, such as sodium and cesium, nonpolymerizable metallates are obtained from which the monomer may be regenerated. Stereospecific catalysts, prepared from triethylaluminum and titanium halides have been investigated as catalysts for allylbenzene. Solid polymers of allylbenzene have been obtained only under very specific catalytic conditions.
Polyethylene crystallinity from x‐ray studies
Authors: Kakudo M. , Ullman R. 
Published: April 2003

AbstractAn x‐ray determination of crystallinity of polyethylene has been carried out. The emphasis in this investigation has been on setting up an experimental procedure which is both theoretically sound and experimentally feasible. It has been shown that the per cent crystallinity is best determined by determining the percentage of amorphous material and subtracting this from one hundred. The importance of monochromatization has been discussed, as well as the need for various corrections arising from incoherent scattering, absorption of x‐rays, and sample expansion. A few numerical results are reported.
Polymerization of methacrylonitrile with potassium in ammonia
Authors: Overberger C. G. , Yuki H. , Urakawa N. 
Published: April 2003

AbstractThe polymerization of methacrylonitrile with potassium and potassium amide in liquid ammonia has been investigated. The results indicated that the degree of polymerization was approximately independent of the monomer and the catalyst concentrations. Furthermore, unlike lithium amide catalysts, potassium amide in ammonia initiates the polymerization of methacrylonitrile as rapidly as potassium does. The results with potassium amide catalysis were similar to those in potassium catalysis. When methacrylonitrile was reacted with potassium in ammonia, small amounts of isobutyronitrile could be detected in the reaction product. On the basis of these results, it is suggested that part of the initiator system in the methacrylonitrile—potassium—ammonia system is potassium amide produced in situ. This is similar to the styrene—potassium—ammonia system studied by Wooding and Higginson. The major termination reaction proposed is a transfer to monomer and to a small extent to the solvent ammonia. Methacrylonitrile was polymerized rapidly to a colorless polymer by initiation by potassium hydroxide. The reaction appears to be slower than that with potassium and potassium amide as catalysts and is retarded by trace amounts of water.
Determination of polycaprolactam fiber crystallinity by x‐ray differential‐filtration method
Authors: Urbańczyk G. W. 
Published: April 2003

AbstractAn x‐ray method for determination of polycaprolactam fiber crystallinity is described. The basis of the method is the differential filtration of the radiation diffracted by the specimen. The use of method is illustrated by a determination of crystallinity of two fiber samples.
Application of an expanded copolymerization theory to systems involving α‐methylstyrene
Authors: Ham George E. 
Published: April 2003

AbstractIt was shown that the copolymer system α‐methylstyrene—acrylonitrile conforms to the equation:

where r1 = K—aaaa/K—aaab = 0, r1′ = K—baaa/K—baab = 0.05, r1″ = K—baa/K—bab = 0.13, and r2 = K—bb/K—ba = 0.06. The system α‐methylstyrene—fumaronitrile was found to obey the equation:

where r1 = K—aaaa/K—aaab = 0, r1′ = K—baaa/K—baab = 0.05, r1″ = K—baabaa/K—baabab = 0.12, and r1‴ = K—babaa/K—babab = 0.17. These results demonstrated the inability of α‐methylstyrene to add to a sequence of three α‐methylstyrene units.
Polycondensation of alkylene dichlorides with alkylene polyamines
Authors: Suen T. J. , Senior A. , Swanson D. L. , Jen Y. 
Published: April 2003

AbstractPolycondensation of ethylene dichloride and 3,3′‐iminobis(propylamine) resulted in high molecular weight soluble polymers or insoluble gels, depending on the ratio of the reactants and the extent of reaction. It is shown that the functionality of a polyfunctional compound containing groups of unequal reactivities can be determined experimentally. The effective functionality of 3,3′‐iminobis(propylamine) was found to be 2.9 from gelation studies and 3.5 based on the relative reaction rates of the primary and secondary amino groups. By using the effective functionality value, the reaction kinetics can be treated in a simple manner. A typical soluble polymer formed has a low intrinsic viscosity and a very high M̄w/M̄n ratio. Condensations of other alkylene dichlorides and alkylene polyamines demonstrated the validity of Carothers' rule that high polymers will not result if formation of 5‐ or 6‐membered rings is possible.
A theory of gel formation with terfunctional interunit junction
Authors: Fukui Kenichi , Yamabe Tokio 
Published: April 2003

AbstractA theory related to the molecular size distribution and gel point in the polymerization by successive formation of terfunctional interunit junctions is presented. This type of polymerization may be realized in three‐dimensional networks containing isocyanuric and s‐triazine rings from polyisocyanate and polynitrile compounds, respectively. The gel point is obtained as αcrit equals; 1/2(f − 1), while in the polymerization due to bifunctional interunit junction it had been given by Flory and Stockmayer as αcrit equals; 1/(f − 1), where αcrit is the fraction of reacted groups at the gel point and f is the number of functional groups borne by a monomeric unit.
Poly(4′‐vinyl‐cis‐benzalacetophenone)
Authors: Unruh C. C. 
Published: April 2003

AbstractThe trans isomers of both poly(4′‐vinylbenzalacetophenone) and a model compound, 4′‐ethylbenzalacetophenone, readily form the corresponding cis isomers on exposure of their solutions to ultraviolet radiation. The cis isomers can be isolated and, in the case of the nonpolymeric material, the cis form reverts readily to the trans form upon addition of a trace of hydrogen chloride. The polymer, however, only partially reverts to the trans form. An explanation is offered to account for this, namely, that, even in dilute solution, intramolecular dimerization occurs in the coiled polymer. These tie points in the polymer chain prevent complete reversion to the trans form.
Mechanism of amine crosslinking of fluoroelastomers. I. Solution studies
Authors: Paciorek K. L. , Mitchell L. C. , Lenk C. T. 
Published: April 2003

AbstractSolution studies of Kel‐F elastomer and Viton A with various amines have shown that dehydrohalogenation is the primary step in crosslinking and usually proceeds at temperatures lower than those required for gelation. There is a difference in the reactivity between the two polymers; dehydrohalogenation and gelation occur more readily with Kel‐F elastomer than with Viton A. The rate of reaction and temperature at which gelation is observed depend upon the type of amine. Mechanisms of crosslinking are proposed and discussed.
On the mechanism of ozone degradation of SBR
Authors: Delman A. D. , Simms B. B. , Ruff A. E. 
Published: April 2003

AbstractThe reaction mechanism of the ozone attack of SBR copolymers was studied to obtain information for use in the development of elastomeric materials having improved resistance to deterioration in service. Techniques of ultracentrifugation and viscometry were utilized to follow molecular changes induced by ozone. Chemical changes were investigated by measuring variations in active oxygen group concentration. Results suggest that the autocatalytic degradation of uninhibited SBR was initiated by a random ozone attack at a double bond on the unozonized chain, producing an ozonide which decomposed spontaneously, forming small segments with activated chain‐ends. This primary reaction, in the presence of oxygen, activated an α‐methylenic chain cleavage process which was terminated when the molecules were degraded to a limiting size, where no more R. radicals were formed from α‐methylenic groups. The reaction was also terminated when oxygen was removed from the system.
Hydrogen and deuterium exchange of polypropylene
Authors: Case L. C. , Atlas J. D. 
Published: April 2003

Abstract“Isotactic” and “atactic” polypropylenes in cyclohexane solution have been exchanged with hydrogen and deuterium in the presence of a large‐pore‐size nickel—kieselguhr catalyst. The resulting polymers were freed from catalyst, precipitated, pressed into films, and the density and stiffness determined. If the “isotactic” polymer were actually stereoregular, it would be expected from studies of model compounds that racemization of the tertiary carbon atoms in the chain would occur upon exchange. The racemization of the polymer would lead to a less “isotactic” polymer, and a drop in density and stiffness. The deuterium content of the polymer was determined by the refractive index of the water of combustion. The exchange values were as high as 3.0%. If all this deuterium were in the tertiary positions, about 18% of the tertiary carbons in the chain would be racemized. However, no detectable loss of stiffness or density occurred. This work failed to confirm the theory of isotacticity. The results, although no conclusive, seem to cast doubt on the theory.
The oxidative degradation of polyethylene. II
Authors: Beachell Harold C. , Tarbet G. Wilfrid 
Published: April 2003

AbstractThe nature and extent of the atmospheric oxidation at elevated temperatures of various polyethylenes in the form of thin films has been studied. A grating spectrophotometer covering the 5–7 μ region was used to follow the production of carbonyl groups during the oxidation. The use of deuterated polyethylenes supports the formation of aldehydes, in addition to ketones, in the primary oxidation step after the production of hydroperoxides. Normally the aldehydes and some of the ketones are oxidized to acids, which react with hydroxyl groups produced in other reactions to give esters. The branched polymers start to oxidize sooner than the linear ones, but when the latter do start to oxidize the rate and extent are greater. None of the accepted mechanisms suggest that linear chains should oxidize rapidly, so it is probable that the high crystallinity or degree of order provides the resistance to oxygen; when this order is lost, oxidation takes place and the fast reaction ensues. This also occurs in the branched materials, but since they have already partially oxidized and have a lower crystallinity, the effect is not so marked.
Polymerization of methacrylonitrile induced by ionizing radiation
Authors: Tabata Yoneho , Oda Eisuke , Sobue Hiroshi 
Published: April 2003

AbstractThe polymerization of methacrylonitrile induced by ionizing radiation was investigated in bulk in the temperature range of 40 to −196°C. It was found from this investigation that two different polymerization mechanisms can exist in the polymerization under the same conditions at different temperature regions. The two different polymerization phenomena at room and at low temperature regions proceed by two different mechanisms: ionic and radical. It was found that the apparent activation energy in bulk polymerization is 6.3 kcal./mole in the 40 to −10°C. range and ca. 0.3 kcal./mole for polymerization initiated by high energy radiation in the −40 to −196°C. range. The effects of additives in the polymerization at both temperature regions were investigated. The viscosity of the polymer was measured in acetone solution at 25°C. and the infrared spectrum of the polymer was also measured. The authors believe from these experiments that the polymerization at room temperature proceeds by a radical mechanism and that the polymerization in the solid state at low temperature proceeds by an ionic mechanism. An important possibility was emphasized that a stereoregular ionic polymerization would be possible even in solid state of monomer by ionizing radiation.
Ziegler polymerization of 4‐methyl‐1‐pentene
Authors: Watt William R. 
Published: April 2003

AbstractPolymerization of 4‐methyl‐1‐pentene was carried out at 40°C. in n‐heptane with the use of catalysts prepared from TiCl4 and triethylaluminum or triisobutylaluminum. Yield of polymer at the end of a fixed time (4 hr.) was used as a measure of catalyst activity. Solubility of the polymer in boiling heptane was used as a measure of stereospecificity. Both activity and stereospecificity are strongly affected by the ratio of aluminum alkyl to titanium tetrachloride in the catalyst. Yield was greatest for catalysts in which Al/Ti was between 1.2 and 2.0. Highest percentage of heptane‐insoluble polymer was obtained at Al/Ti equals; 1. Stereospecificity was little affected by the monomer/catalyst ratio in the ranges studied. Catalysts prepared from triethylaluminum gave slightly higher percentages of heptane‐insoluble polymer than did triisobutylaluminum.
The glass temperature of semicrystalline polymers
Authors: Newman S. , Cox W. P. 
Published: April 2003

AbstractThis study focuses attention on the relation between the glass transition temperature, Tg, of the amorphous phase of semicrystalline polymers and the morphological state of the polymer. By use of dynamic mechanical and thermal distortion tests, the influence of stereospecificity; crystallinity; and, orientation in the absence and presence of crystallinity, has been assessed for crystallizable polystyrene (CPS). These results, together with some analogous data on crystallizable polypropylene (CPP), are compared to published information on other polymers. Studies of quenched, oriented CPS by thermal distortion tests under load indicate that the retractive stress and external load are the prime factors in determining the glass temperature as measured by this type of test. The influence of Tg of the configurational state, sorted out from the other two factors, is shown to be small. For CPS, an increase in Tg of 5–15°C., depending on the method of test, is observed to accompany crystallization. An increase of 15–25°C. in Tg, relative to amorphous CPS, is noted for samples annealed in the stretched condition. The combined effect of crystallinity and orientation is significantly greater than the sum of the individual effects; a mechanism is postulated for this synergistic behavior. The breadth of the transition of oriented, annealed samples appears to depend on the direction of test relative to the direction of stretch. Stereo‐specificity in polystyrene and polypropylene appears to have a negligible influence on Tg.
Degradation of poly(ethylene oxide)
Authors: McGary C. W. 
Published: April 2003

AbstractThe degradation of high polymers of ethylene oxide in aqueous and organic solutions is accelerated by strong acids, certain oxidizing agents, ultraviolet light, and certain heavy metal ions. The effectiveness of the latter two components is related to the solution stability of various polymer samples upon long‐term, natural aging. These facts are interpreted by assuming that poly(ethylene oxide) degrades primarily by autoxidation, giving hydroperoxides which decompose by polymer chain cleavage. Certain oxidizable materials and compounds which form stable free radicals are effective in retarding the solution viscosity decrease. Aqueous polymer solutions containing alcohols, such as isopropyl alcohol, are very stable to all of the normally detrimental aging conditions. The effectiveness of the alcohol is related to the theoretical ease with which the α‐hydrogen atom is extracted, and, consequently, these effects are interpreted in view of the selective autoxidation of the alcohol present. Other types of stabilizers were investigated.
Isolation of high molecular weight amylose by dimethylsulfoxide dispersion
Authors: Killion Philip J. , Foster Joseph F. 
Published: April 2003

AbstractThe problem of the isolation of the amylose component of starch under conditions of minimal degradation has been re‐examined. It is confirmed that aqueous leaching of granules under anaerobic conditions as advocated by Gilbert and co‐workers leads to amylose of high intrinsic viscosity and very high molecular weight (M̄w > 1 × 106), and of high degree of digestion by crystalline β‐amylase (∼95%). However, yields are poor under practical conditions. An alternative procedure is described based on the fact that fresh undried potato starch can be quantitatively dispersed in dimethylsulfoxide by prolonged contact at room temperature. Addition of butanol to this solution results in precipitation of both amylose and amylopectin components. This precipitate can, however, be redissolved in water and the amylose component separated in the customary manner by butanol complexing (following a brief heating of the aqueous solution to 70°C). After one recrystallization a product has been attained which possesses an iodine binding capacity of 18.9 mg./100 mg., and intrinsic viscosity and M̄w even higher than in case of the material leached by water under anaerobic conditions. Further, the high degree of digestibility by crystalline β‐amylase (>95%) indicates negligible chemical alteration of the normal linkages under the preparative conditions.
Studies on polyoxypropylene glycols. Part III. Equilibrium swelling of crosslinked polyurethane elastomers
Authors: Conway B. E. , Tong S. C. 
Published: April 2003

AbstractSwelling equilibrium measurements on three polyurethane elastomers prepared from a polyoxypropylene glycol are reported. Values of the equilibrium swelling volume v2 have been obtained by determinations of both weight and dimensional changes. The solvents used were methanol, 1,4‐dioxane, benzene, and water. In the case of methanol, the temperature coefficients of swelling volumes were derived. Values of the polymer‐solvent interaction constant χ are obtained from dv2/dT and v2 and also from v2 and measurements of elasticity described in Part IV. The relationship between the swelling volume and the elastic retractile force in extended samples of the elastomers is discussed.