bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic mechanical behavior of some high polymers at temperatures from 6°K.: Polyethylene, nylon 66, polypropylene, poly(vinyl chloride), poly‐(d,l‐propylene oxide), polybutene‐1, poly(4‐methyl‐pentene‐1), poly(methyl methacrylate), poly(ethyl methacrylate), poly‐4‐methylpentene‐1 and poly(isobutyl methacrylate)
Authors: Crissman J. M. , Sauer J. A. , Woodward A. E. 
Published: April 2003

AbstractMeasurements of the dynamic mechanical properties of various polymers have been made in the 6–300°K. temperature range at resonant frequencies of about 104 cycles/sec. by using a longitudinal vibration apparatus. The polymers studied include polyethylene, nylon 66, three poly(methacrylate esters), and five poly‐α‐olefins and related polymers. Results for poly(methyl methacrylate) and poly(ethyl methacrylate) indicate the occurrence of low temperature relaxation processes (6°K. and 52°K., respectively) involving configurational rearrangements in the hydrocarbon portion of the ester side groups. The data provide no evidence for mechanical loss processes associated with hindered rotation of the main‐chain methyl groups in the poly(methacrylate esters) or polypropylene. Very weak relaxation processes or loss plateaus are observed in the 20°K. region for polypropylene, poly(vinyl chloride), poly(d,l‐propylene oxide), poly(isobutyl methacrylate) and possibly nylon 66, while for poly‐4‐methylpentene‐1 a sizeable loss peak is observed at 25°K. The mechanisms responsible for these loss peaks are not yet understood. No relaxation phenomenon is observed below 77°K. for either polyethylene or polybutene‐1. For poly(d,l‐propylene oxide) a loss maximum or shoulder appears at 70–120°K. which is possibly associated with chain motions accompanying the methyl reorientation process.
Cationic isomerization polymerization of β‐methylstyrene and allylbenzene
Authors: Kennedy J. P. 
Published: April 2003

AbstractThe structure of cationically obtained poly‐β‐methylstyrene and polyallylbenzene has been investigated by high resolution infrared spectroscopy. These studies indicate that under cationic conditions β‐methylstyrene polymerizes by a conventional 1,2 mechanism, whereas allylbenzene partly isomerizes to β‐methylstyrene prior to propagation and probably gives a “copolymer” of rearranged and unrearranged units.
Kishi lag times for O2 adsorption onto irradiated poly(bisphenol‐A carbonate) and poly(methyl methacrylate)
Authors: Barker R. E. 
Published: April 2003

AbstractRe‐examination of some data which were originally taken to determine diffusion coefficients and their variation with applied stress in electron irradiated poly(bisphenol‐A carbonate) and poly(methyl methacrylate) has verified the existence of Kishi induction periods ti for the initial stages of O2 sorption by these polymers. The data conform to the relation \documentclass{article}\pagestyle{empty}\begin{document}$ t_i = t_{i^0 } e^{{E \mathord{\left/ {\vphantom {E {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} e^{{{ - p} \mathord{\left/ {\vphantom {{ - p} {p1}}} \right. \kern-\nulldelimiterspace} {p1}}} $\end{document}. Some new gas sorption data for poly(bisphenol‐A carbonate) by Norton are utilized in conjunction with data and equations from our previous paper to estimate initial concentrations of the free radicals associated with the visually sharp diffusion boundary which was the major topic of our previous paper. The value G[oxygen‐bleached color‐centers/h.e.v.] obtained for these radicals is compared with recent viscometric determinations by Golden and Hazell.
Conformation of styrene–maleic acid copolymer in aqueous HCl solutions
Authors: Kuppers James R. 
Published: April 2003

AbstractThe properties of dilute aqueous solutions of styrene–maleic acid copolymer at low degrees of ionization are not compatible with a random coil model. Based upon a study of hydrodynamic and other solution properties of the copolymer, a model is proposed which considers intermolecular and intramolecular interactions of phenyl groups as well as forces of electrostatic repulsion of ionized carboxyl groups. Values of [η]/[η]θ less than unity are better explained by intermolecular aggregation than by a hypercoiled conformation of individual chains. Difficulties previously encountered in copolymer fractionation were resolved.
Interaction parameters and heats of dilution for ethylene–propylene rubber in various solvents
Authors: Holly Earl D. 
Published: April 2003

AbstractCrosslinked ethylene–propylene rubber gels were swollen in five solvents at 25–100°C. The solvent–polymer interaction parameter μ for each system was determined as a function of temperature and polymer concentration. A thermodynamic criterion of the sign of the heat of dilution, ΔH̄1, was pointed out. For three of the systems ΔH̄1 was negative. The entropy contribution to the interaction parameter was found to be smaller than usual for systems having a temperature‐dependent heat of dilution. The heats of dilution and the entropy terms may be consistently interpreted in terms of Prigogine's theory of solutions.
Post‐modification of conjugated triene polymers via the Diels‐Alder reaction
Authors: Bell Vernon L. 
Published: April 2003

AbstractPolymers from 1,3,5‐hexatriene, 1,3,5‐heptatriene, and 2,4,6‐octatriene were modified by means of the Diels‐Alder reaction. Several dienophilic agents were reacted with the polytrienes containing conjugated diene groups to yield cyclic structures incorporated into, and appended to, the polymer backbone. The mild conditions of the post‐reactions proved to be convenient for the conversion of highly unsaturated polyhydrocarbons into unique polymers bearing functional substituents. It was proposed that the incomplete reaction of tetracyanoethylene with the 1,3‐dienyl groups of the polymer substrates was a result of steric hindrance of the ring structures of the polymer adducts.
Kinetics of sorption of water vapor by hydrophilic polymers. Potassium and lithium forms of poly(vinyl methyl ether–maleic acid)
Authors: Spencer H. G. , Hunt O. L. 
Published: April 2003

AbstractThe rates of desorption of water vapor from the lithium and potassium forms of poly(vinyl methyl ether–maleic acid) were measured at several initial concentrations and temperatures. A few absorption experiments were performed, and the resulting curves were anomalous. The sorption rates were slower for the lithium form than for the potassium form and the rates for both forms were dependent upon the penetrant concentration. Sorption coefficients, defined by analogy with diffusion coefficients, were determined from the initial rates of desorption and were used to characterize the desorption rates. Limiting‐sorption coefficients were determined and found to be much smaller than the diffusion coefficients for water vapor in polymers which are more hydrophobic.
Polymerization of higher aldehydes. VII. Tacticity of elastomeric polyacetaldehyde,
Authors: Brame E. G. , Sudol R. S. , Vogl O. 
Published: April 2003

AbstractHigh resolution NMR spectroscopy was used to determine the tacticity of elastomeric polyacetaldehyde. Spectra obtained at elevated temperatures and in solutions of carbon tetrachloride and tetrachloroethylene showed a weak line on the high field side of a strong line in both the methyl group and the CH group regions. Comparison of these results with those obtained on related model compounds indicated that the weak lines can be attributed to the isotactic structure and that the strong lines can be assigned to the heterotactic structure. After the lines were narrowed by spin‐decoupling procedures, the area measurement results suggested that polyacetaldehyde is a highly random polymer.
Poly‐1,3,4‐oxadiazoles. I. Polyphenylene‐1,3,4‐oxadiazoles
Authors: Iwakura Yoshio , Uno Keikichi , Hara Shigeyoshi 
Published: April 2003

AbstractPolyphenylene‐1,3,4‐oxadiazoles have been prepared from benzenedicarboxylic acids or their derivatives and hydrazine by solution polycondensation in fuming sulfuric acid or polyphosphoric acid. These polymers were characterized by good thermal stability, and the molecular weights attained were high enough for the products to exhibit fiber‐or‐film‐forming properties. Concentrated sulfuric acid and polyphosphoric acid were the only solvents for these polymers.
Study of phenolic resins by PMR spectroscopy with arsenic trichloride as a solvent
Authors: Szymanski Herman A. , Bluemle Albert 
Published: April 2003

AbstractThe PMR spectra of several phenolic resins and model compounds related to these resins are reported. Arsenic trichloride as a PMR solvent for the resins is suggested. The PMR spectra of a resin which is linked in the ortho position only is compared to that of a resin where both ortho and para linkages occur. It is shown that the completely ortho‐linked resin gives a phenolic OH signal which does not shift when HCl gas is added, while it does shift if the resin has both ortho and para linkages. This observation is explained by assigning a strong intramolecular hydrogen bond to the ortho‐linked resin. The behavior of the phenolic OH signal when HCl is added can therefore be used to distinguish between ortho and ortho,para‐linked resins. A semiquantitative approach to obtaining average molecular weights is also presented. By integrating the PMR signals of various structural units of the resin it is possible to estimate the relative number and therefore the total number of units of this type in a molecule. The total number is a measure of the molecular weight. Spectral assignments are given for the various types of structural units present in the resins.
Radical displacement in allyl ester polymerization. I. Allyl acetate; evidence from gas‐phase kinetics
Authors: James D. G. L. , Troughton G. E. 
Published: April 2003

AbstractPhotolysis of diethyl ketone in the presence of allyl acetate in the range 35–175°C. leads to the addition and dismutation reactions:

The proposed reaction scheme is supported by the values: R(CO2)/[R(C5H10) + R(C4H8)] = 1.02 ± 0.03, and R(C5H10)/[R(CH4) + R(C3H8)] = 1.01 ± 0.03, and allows the evaluation of k7 and k8:

where k2 refers to: 2CH3CH·2 → C4H10 and k7a to: CH3CH·2 + ·C5H10OCOCH3 → C7H15OCOCH3. These results are discussed in relation to the radical displacement mechanism of effective chain transfer in the polymerization of allylic monomers.
Rheological properties of multichain polybutadienes
Authors: Kraus Gerard , Gruver J. T. 
Published: April 2003

AbstractThe introduction of one or two long chain branches into a polybutadiene molecule to form trichain or tetrachain molecules, respectively, leads to profound changes in rheological behavior. At low molecular weights the Newtonian (zero shear) viscosity is decreased relative to a linear polymer of the same molecular weight. At molecular weights exceeding 60,000 (trichain) or 100,000 (tetrachain), the Newtonian viscosity rises rapidly above the corresponding value for a linear polybutadiene. However, non‐Newtonian behavior of the branched polymers becomes more pronounced the higher the molecular weight, so that at moderate to high shear rates the viscosity of the branched polymers is uniformly lower than that of linear polymers of identical molecular weight.
Phase equilibria of polymer–solvent systems at high pressures near their critical loci. II. Polyethylene–ethylene
Authors: Ehrlich Paul 
Published: April 2003

AbstractThe system polyethylene–ethylene exhibits the same type of phase behavior as that described earlier for polyethylene‐n‐alkane systems well above the boiling points, or above the critical points of the solvents. In this case, the solvent is always above its critical temperature in the region investigated, and one has here another case of infinite polymer‐gas miscibility. The critical locus was determined, from its intersection with the crystallization surface at about 115 to 200°C., and the three‐dimensional phase model in (P, T, composition) space is visualized.
Polymerization of N‐methyl‐β‐propiolactam with ionic catalysts
Authors: Kagiya Tsutomu , Kishimoto Hiroshi , Narisawa Shizuo , Fukui Kenichi 
Published: April 2003

AbstractThe polymerization of N‐methyl‐β‐propiolactam with various ionic catalysts in bulk was carried out at 140–190°C. Organic compounds containing a carboxyl group have a high catalytic activity for the polymerization and gave crystalline polymer melting at 180–225°C. No polymer of N‐methyl‐β‐propiolactam was formed at 140°C., but the polymerization of N‐methylacrylamide took place. The polymer of N‐methylacrylamide was amorphous and its infrared spectrum was quite different from that of poly‐N‐methyl‐β‐propiolactam. The infrared spectrum of poly‐N‐methyl‐β‐propiolactam showed a major absorption peak characteristic of a polyamide structure. On the basis of the infrared spectrum of an equimolar mixture of monomer and catalyst heated at 130°C., a mechanism was proposed.
Kinetics of polymerization of butadiene, isoprene, and styrene with alkyllithiums. Part I. Rate of polymerization
Authors: Hsieh Henry L. 
Published: April 2003

AbstractThe kinetics were determined for the polymerization of butadiene, isoprene, and styrene with n‐, sec‐, and tert‐BuLi in hydrocarbon solvents. Polymerization has the mechanism of a homogeneous, “intermittent” stepwise addition reaction with no true termination reaction. In cyclohexane, n‐hexane or toluene at 5–50°C. there is no chain transfer. When n‐BuLi was used, the rate of polymerization was a combined rate of initiation and propagation. It was proportional to [M]2 and dependent on [n‐BuLi] at low initiator concentration and almost independent at high concentration. The limits are established and discussed. The rate constants calculated for the monomers were in the order styrene > isoprene ≫ butadiene. For the solvents the order was toluene ≫ cyclohexane > n‐hexane.
Kinetics of polymerization of butadiene, isoprene, and styrene with alkyllithiums. Part II. Rate of initiation
Authors: Hsieh Henry L. 
Published: April 2003

AbstractBy gas chromatographic analysis of the hydrolyzed polymerization solutions, the per cent of BuLi unreacted was measured at various conversions. The effects of BuLi concentration, the structure of the butyl group, and the solvent type were studied. The rates of initiation (Ri) for butadiene, isoprene, and styrene were determined. For dienes, the order was sec‐BuLI > i‐PrLi > tert‐BuLi > i‐BuLi > n‐BuLi. For styrene, it was sec‐BuLi > i‐PrLi > i‐BuLi > n‐BuLI > tert‐BuLi. With n‐BuLi, the order was styrene > butadiene > isoprene. For any particular monomer–initiator combination, the order was toluene ≫ n‐hexane > cyclohexane. The results obtained here proved that Ri = ki [RLi] [M] for all three monomers.
Molecular weight and molecular weight distribution of polymers prepared from butyllithiums
Authors: Hsieh Henry L. 
Published: April 2003

AbstractThe calculated kinetic molecular weight Mk was compared with experimentally determined viscosity molecular weight Mv of polybutadiene, polyisoprene, and polystyrene initiated with n‐BuLi, sec‐BuLi, and tert‐BuLi. The discrepancy between Mk and Mv depends on the ratio of rates of initiation Ri and propagation Rp, which in turn depends on initiator structure and monomer. In the alkyllithium‐initiated polymerization system, Mk based on the [RLi] consumed rather than charged, is almost equal to the actual molecular weight. The ratio of Ri and Rp also affects the molecular weight distribution. The order of monodispersity for polydienes is sec‐BuLi ≅ tert‐BuLi > n‐BuLi. For styrene, it is sec‐BuLi ≫ n‐BuLi ≫ tert‐BuLi. The fractionation data are in perfect agreement with the predictions of the kinetic data. The ideal conditions for the preparation of monodispersed polymer by means of anionic polymerization are also discussed.
Reactions of titanium tetrachloride (tetraiodide, dichlorodiiodide) with alkylaluminum compounds
Authors: Moyer Patricia H. 
Published: April 2003

AbstractTitanium tetraiodide and titanium dichlorodiiodide are reduced by triisobutylaluminum or diisobutylaluminum iodide to form products analogous to those obtained with titanium tetrachloride. In the reaction products, the preferred site for iodide ligands is titanium, that for chloride ligands, aluminum.
Studies of the polymerization of butadiene by titanium(IV) compounds with alkylaluminums
Authors: Moyer Patricia H. , Lehr Marvin H. 
Published: April 2003

AbstractCatalysts for the polymerization of butadiene consisting of an alkylaluminum compound with a titanium(IV) compound show variations in reactivity with Al/Ti ratio. The ratio at which maximum reactivity is obtained increases as the electronegativity of the ligands bound to titanium decreases. This is observed on replacement of the chloride ligands of titanium tetrachloride by either iodide or isopropoxy ligands. Catalysts prepared from titanium dichlorodiiodide or titanium chlorotriiodide behave like those from titanium tetraiodide, as would be expected from the previous observation that titanium is the preferred site of attachment for iodide in the reduction products of mixed salts. The cis content of the polymers obtained with the iodide‐containing salts can be 90% or more, but decreases with increasing titanium concentration, whereas the structure of polymers obtained with titanium tetrachloride is independent of catalyst concentration. Polymerization is not induced by either the soluble alkylaluminum compounds or the insoluble reduced titanium iodides which are produced by the reaction of triisobutylaluminum with titanium tetraiodide. The insoluble material can be activated by triisobutylaluminum or, less readily, by diisobutylaluminum iodide.
Viscosities of concentrated polymer solutions
Authors: Nishimura Norio 
Published: April 2003

AbstractA general relationship between the viscosity and the concentration of polymer solutions has been derived for relatively low concentration regions by means of the method which was proposed by Brinkman. The relationship was extended so as to be applicable for extremely concentrated solutions by allowing for the volume shrinkage of polymers. With increasing concentration, the apparent volume which a polymer in solution occupies above some critical volume fraction ϕc, is assumed to be given by Ω = sv0ϕ−β, where s is the swelling factor at ϕ = 1 and β is a constant which measures a reluctance against the intermolecular permeation; v0 and ϕ are the net volume of the polymer molecule and the volume fraction of the polymer, respectively. The dependence of η on ϕ is given by the equation d log η/dϕ = C/ϕγ (1 − ϕ), where C and γ are constants to be determined empirically. In order to test the validity of the equation, our experimental and some other available data were used. Although neither temperature nor molecular weight factor is involved in this equation, it accounts well for the dependence of the viscosity on the concentration of polymers over a wide range of concentration, and fairly satisfactory agreement was found between theory and experiment.
Copolymerization of styrene and p‐divinylbenzene. Initial rates and gel points
Authors: Storey Bayard T. 
Published: April 2003

AbstractInitial rates of polymerization were measured at 70.0 and 89.7°C. for styrene, p‐divinylbenzene, and mixtures of the two monomers initiated with 1% benzoyl peroxide. The rates relative to styrene increased linearly with mole fraction of p‐divinylbenzene: the latter monomer polymerized faster than styrene by a factor of 2.50 at 70.0°C. and 3.54 at 89.7°C. Times to gelation were also measured for those samples containing p‐divinylbenzene, and from these times the corresponding fractional conversion at the gel point was calculated. The conversion at the gel point passed through a minimum with increasing content of p‐divinylbenzene. The gelation behavior is explained by concurrent interchain crosslinking to give a network and intrachain crosslinking to give microgels which accumulate to give macrogel, the latter process being dominant at all but low concentrations of p‐divinylbenzene. The higher the content of crosslinker, the less swollen the microgels, and the greater the conversion required to give gelation by this process. The linear increase in rate with increasing p‐divinylbenzene content was also explained by intrachain crosslinking: growing polymer radicals which undergo this process have a reduced rate of termination. The factor by which the termination rate constant is reduced with increasing divinylbenzene content is the same factor as that by which the conversion required to give gelation by accumulation of microgels is increased.
Kinetics of polymerization of styrene initiated by substituted peroxides. II. Decomposition rate constants and efficiencies
Authors: O'Driscoll K. F. , White P. J. 
Published: April 2003

AbstractThe following bis‐substituted benzoyl peroxides were used as initiators for the polymerization of bulk styrene monomer at 90°C.: p‐methoxy‐, p‐methyl‐, p‐chloro‐, m‐bromo‐, 3,4‐dichloro‐, p‐cyano‐, and p‐nitro‐; in addition, unsubstituted benzoyl peroxide was also studied. From the observed rates of polymerization the rate constants for the unimolecular decomposition and for the radical‐induced decomposition of the peroxides were obtained, as well as the efficiency of initiation of polymerization. It was observed that substituents more electron‐withdrawing than p‐chloro did not change the unimolecular rate constant. Conversely, substituents less electron‐releasing than p‐chloro had little effect on the efficiency of initiation. The induced decomposition rate constant gave a simple linear Hammett plot with positive slope.
Studies of structure formation in poly(vinyl alcohol) solutions
Authors: Zubov P. I. , Osipov E. A. 
Published: April 2003

AbstractAcetalation of PVA in aqueous solution with succinaldehyde yields a gel or globular structures with strong chemical intermolecular or intramolecular bonds, depending on the solution concentration. Similar structures formed by localized physical bonds may be obtained by cooling the PVA solutions in DMF–water mixtures of certain compositions or in anhydrous DMF. Comparison of the viscosity data for the solutions with turbidity of these systems and electron microscopy leads to the conclusion that globular particles obtained by cooling the PVA solutions in anhydrous DMF are super molecular structures of colloidal size. The diameter of these particles depends not only on the solution concentration but also on the temperature to which the PVA solutions are cooled. The dimensions of the particles decrease with the temperature at which the cooled solution is kept. The globular structures are stable in anhydrous DMF and are destroyed only at 120°C. In the presence of water a redistribution of intramolecular and intermolecular bonds proceeds at room temperature and results in the formation of a thixotropic structure. The structure formation influences considerably the mechanical and adhesion properties of PVA films prepared on solid surfaces.
Turbidimetric titration method for determining solubility distributions of polymers
Authors: Beattie W. H. 
Published: April 2003

AbstractA turbidimetric titration method for determining solubility distributions (which are closely related to molecular weight distributions) has been developed. In this method, polymer is precipitated from its solution by addition of a nonsolvent of the same refractive index as that of the solvent. The precipitating particles of swollen polymer are allowed to agglomerate until the turbidity reaches a maximum. It is shown by the use of light‐scattering theory that under these conditions the concentration of polymer which is precipitated can be calculated from the maximum turbidity on an absolute basis. The effects of particle size and particle size distribution are discussed. The method was tested by using polystyrene, and is shown to be accurate. In principle the method is applicable to most kinds of polymers.