bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of metal chelates in polymerization initiation. II. Cupric chelates
Authors: Bond Joan , Hobson D. B. 
Published: April 2003

AbstractThe polyaminocarboxylic acids, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), cyclohexanediaminetetraacetic acid (CDTA), and diethylenetriaminepentaacetic acid (DTPA) have been used to chelate the cupric ion when the system cupric ion—hydrogen peroxide is used as an initiator for the emulsion polymerization of styrene. The same maximum zero order rate of polymerization of approximately 60% conversion/hr. is obtained in all cases, although with NTA this occurs from pH 3–6 while with EDTA, CDTA, and DTPA the maximum occurs in the regions pH 4–7, pH 3–7, and pH 6.5–9.5, respectively.
Ebulliometric and endgroup molecular weights of polyoxypropylene and polyoxyethylene glycols
Authors: Havlik A. J. , Moacanin J. , Otterness I. 
Published: April 2003

AbstractA study was made of the number‐average molecular weights of a series of preparations of polyoxypropylene glycol (POPG) and polyoxyethylene glycol (POEG). The number average molecular weights of the POPG and POEG samples were determined by ebulliometry and compared to molecular weights estimated from functional endgroup analyses. Differences in results obtained with the two methods were noted and discussed in terms of the foreign functional group contents of the samples.
Copolymerization studies. IV. Transannular copolymerization of bicyclo[2.2.1] hepta‐2,5‐diene
Authors: Zutty N. L. 
Published: April 2003

AbstractBicyclo[2.2.1]hepta‐2,5‐diene, in the presence of free‐radical initiators, homopolymerizes to a low molecular weight, soluble polymer containing both 3,5‐disubstituted nortricyclene and 5,6‐disubstituted bicyclo [2.2.1] hept‐2‐ene units in the polymer backbone. When the bicycloheptadiene (M2) is copolymerized with vinyl chloride, vinylidene chloride, acrylonitrile, ethyl acrylate, and methyl methacrylate, only the transannular product, 3,5‐disubstituted nortricyclene, is found in the high molecular weight copolymers. Reactivity ratios for the above mentioned copolymerizations at 50°C. are: r1 = 0.74, r2 = 0.35; r1 = 1.41, r2 = 0.08; r1 = 0.67, r2 = 0.08; r1 = 3.05, r2 = 0.01; r1 =10.0, r2 = 0; respectively. From these data, the Q and e values for bicyclo[2.2.l]hepta‐2,5‐diene average 0.09 and −1.04, respectively.
Carbonium ion rearrangement in the cationic polymerization of branched alpha olefins
Authors: Edwards W. R. , Chamberlain N. F. 
Published: April 2003

AbstractThe polymerization of olefins of the series (n‐1)methyl‐1‐alkenes through carbonium ion intermediates appears to involve a rearrangement from a secondary to a tertiary carbonium ion. The structure of the final polymer, as determined by nuclear magnetic resonance, depends on the relative rates of rearrangement and polymerization. In the homogeneous aluminum chloride catalyzed systems investigated, the rate of rearrangement decreases with increasing length of the monomer and is comparable to the rate of polymerization for 4‐methyl‐1‐pentene. The activation energy for rearrangement is lower than that for polymerization.
Elution fractionation of crystalline polypropylene
Authors: Mendelson Robert A. 
Published: April 2003

AbstractA number of commercial and experimental samples of crystalline polypropylene were fractionated by sand column solvent gradient elution techniques. Two different solvent—nonsolvent systems were studied under several sets of experimental conditions. Deposition of polymer upon the sand from a thermodynamically poor solvent was found to be necessary to achieve selective fractionation according to molecular weights. Both selective and nonselective fractionation results are illustrated with the latter occurring whenever the polymer is deposited upon the substrate from a thermodynamically good solvent. Molecular weight distributions for ten samples are given as obtained from elution fractionation using o‐dichlorobenzene—diethylene glycol monomethyl ether as solvent—nonsolvent system at 168°C. These molecular weight distributions could be adequately described by the logarithmic‐normal probability distribution function found by Wesslau and others to be applicable for linear polyethylene and by Davis and Tobias for polypropylene. Many of the distributions observed in this work were found to be narrower than those previously reported in the literature.
On the polymer–solvent interaction in polymer solutions
Authors: Kuwahara Nobuhiro 
Published: April 2003

AbstractOsmotic pressure and viscosity measurements afford mutually supplementary data for the thermodynamic parameters governing the interaction between polymer segments and solvent molecules. With the object of studying the effects of the structural characteristics of polymer and solvent on the interaction between polymer segments and solvent molecules, we have performed osmotic pressure and viscosity measurements at different temperatures. It appears that the ϑ temperature deduced from the intrinsic viscosity agrees with that obtained from the second virial coefficient. The entropy of dilution for the polyisobutylene–benzene system appears to be comparable to that found for polydimethylsiloxane in benzene. However, the entropy of dilution has been found to differ widely for a given polymer in different solvents. It appears that the entropy of dilution varies not only with the geometrical character of the solvent molecule in relation to the polymer segment, but also with the preferential ordering induced by the difference in the binding forces between the molecules solvent–solvent, solvent–solute, and solute–solute. A brief discussion is also given on the influence of hindrance to free rotation on the polymer configuration.
Polymerization of α‐methylstyrene with Al(C2H5)3‐TiCl4 catalyst
Authors: Sakurada Yutaka 
Published: April 2003

AbstractPolymerization of α‐methylstyrene was carried out in the presence of AlEt3‐TiCl4 at −78°C. The activity of the catalyst and the degree of polymerization were affected by the AlR3/TiCl4 molar ratio, the mixing and the aging conditions of catalyst, and the kinds of solvent. The advantageous AlR3/TiCl4 molar ratio was found to be between 1.0 and 1.2; at ratios higher than 2.0 the polymerization did not proceed. For this catalyst to have enough activity, the mixing and the aging of catalyst must be carried out below room temperature, and the valence state of titanium must be kept between IV and III after the reaction between AlEt3 and TiCl4. From comparison of the present results with other catalyst systems it is speculated that the polymerization reaction by this catalyst system is cationic, and that its active species are the intermediate complex [(TiCl3)+‐(AlEt3Cl)−] and the reaction product AlEt2Cl. This speculation is confirmed by the molecular weight distribution curves of the poly‐α‐methylstyrene obtained, measured by a column fractionation method. The distribution curves have two maxima, at molecular weights of about 5 × 104 and 65 × 104. This suggests that two kinds of active species are present, in agreement with the above hypothesis. The resultant poly‐α‐methylstyrene shows superior stereoregularity, compared with that prepared with other catalyst systems.
A comparison of dynamic methods for osmotic pressure measurements
Authors: Bruss D. B. , Stross F. H. 
Published: April 2003

AbstractA comparison of dynamic methods for osmotic pressure molecular weight determinations has been made between the authors' method, the recently published method of Elias, and two other commonly used procedures. Samples containing various amounts of membrane‐permeating solute were studied while using the same osmometer and gel‐cellophane membrane. Good agreement is shown between the authors' method and that of Elias for all of the samples. The Fuoss‐Mead technique and Philipp's method do not measure as much of the permeating solute when present in large amounts. The method of Elias is subject to continual calibration because of pore blockage and was found to be considerably more time‐consuming than the authors' method.
Unrestricted rotation in polymers with discrete rotational states
Authors: Carmichael Jack B. , Kinsinger Jack B. 
Published: April 2003

AbstractThe authors propose that a polymer chain with equally probable but discrete rotational states be called a chain with “unrestricted” rotation. This model is equivalent to the “freely rotating” model only under specific circumstances. At the present time, it is customary to compare unperturbed mean‐square end‐to‐end dimensions of polymers (r20/nl2) with the corresponding values calculated from the freely rotating model of a polymer chain. However, comparison of (r20/nl2) to the equivalent unrestricted rotation model dimensions (r2u/nl2) is an improved measure of chain stiffness or conformational order. Calculations are performed for polydimethylsiloxane, polyethylene, isotactic polypropylene, and polyisobutylene. The significance of r20/r2u for these polymers is discussed.
Behavior of polymer solutions in the velocity field with parallel gradient. III. Molecular orientation in dilute solutions containing flexible chain macromolecules
Authors: Takserman‐Krozer Rachela 
Published: April 2003

AbstractThe orientation of flexible, coiled, chain macromolecules in the velocity field with parallel gradient has been analyzed on the basis of the subchain model. It has been found that the axial orientation factor in the steady state depends only on the velocity gradient q, diffusion constant D, and molecular dimensions. The internal viscosity of macromolecule has no influence upon the steady‐state orientation factor. The relation describing the time dependence of the orientation factor have also been derived.
Viscoelastic behavior of plasticized polyvinyl chloride at large deformations. II. Creep
Authors: Sabia Raffaele , Eirich F. R. 
Published: April 2003

AbstractPlasticized polyvinyl chloride has been found to undergo a permanent deformation when strained past 100%. At the same strains, internal energy effects become pronounced as reflected in the stress‐strain curves. Plasticizer efficiency has been evaluated in several respects, namely rubber‐like behavior, recovery, glass transition, set, and stress‐strain at break. While no single plasticizer stands out, the following sequence has been established with respect to the first four aspects listed above: DOA ≥ TCP > DPP ≥ ARO.
An interpretation of ethylene polymerization with alkyl‐promoted transition‐metal catalysts
Authors: Smith Wayne E. , Zelmer Ralph G. 
Published: April 2003

AbstractA concept has been developed to explain the kinetic behavior of six transition‐metal catalyst systems for ethylene polymerization: CrO3 · SiO2 and V2O5 · SiO2 promoted by (i‐C4H10)3Al; VOCl3 promoted by (C2H5)2AlCl; TiCl4 promoted by (C2H5)3Al or (i‐C4H10)3Al; and (C5H5)2TiCl2 promoted by (CH3)2AlCl. Despite obvious differences in the chemical nature of their active species and known behavioral differences, all of these systems show a second‐order deactivation of active species with time. Production of polymer in batch polymerizations has been shown to obey an equation relating propagation and deactivation constants, monomer concentration, reaction time, and initial number of active sites. This equation has been extended to fit batch runs with continuous catalyst addition. One possible reaction mechanism has been proposed. Qualitative steps are: (1) complex formation between the transition‐metal complex and alkyl, (2) alkylation of the complex, (3) polymerization by the alkylated species, and (4) second‐order decay of active species.
Studies on crystallization of high polymers by differential thermal analysis
Authors: Inoue Masakazu 
Published: April 2003

AbstractDifferential thermal analysis was applied for the investigation of melting and crystallization behavior of high polymers. The heats of fusion of crystalline regions were obtained as follows: 45.6 cal./g. for nylon 6, 46.8 cal./g. for nylon 66, 47.9 cal./g. for nylon 610, 54.1 cal./g. for nylon 11, 58.7 cal./g. for polyoxymethylene, 64.8 cal./g. for high density polyethylene, 15.9 cal./g. for polypropylene, and 35.4 cal./g. for poly(3,3‐bischloromethyl oxacyclobutane). In the course of crystallization, the exothermic peak appears in the temperature range of 20 to 100°C. below the melting point. The effect of melting temperature and molecular weight on the thermograms of crystallization of nylon 6 and polyoxymethylene was discussed and compared with the results obtained by dilatometry. For polymers such as nylon 6 with higher molecular weight and polyoxymethylene, two exothermic peaks of crystallization were observed, and it was found that the peak shape depends on the molecular weight. Nylon 6 containing nucleating agent shows only one exothermic peak independent on the molecular weight. It is presumed that the discontinuity of the growth rate of crystals is responsible for the thermograms having two peaks.
Photochlorination of poly(methyl methacrylate) in aqueous suspension
Authors: Owens F. H. , Zimmerman F. E. 
Published: April 2003

AbstractThe aqueous suspension chlorination of poly(methyl methacrylate) using incandescent light produces polymer having up to one chlorine atom per monomer unit. The mechanism of aqueous suspension chlorination is the same as that for solution chlorination, i.e., free radical substitution; the rate of chlorination at constant chlorine flow rate depends on the time, the concentration of the polymer, and the size or porosity of the polymer particles. The structures of suspension and solution chlorinated poly(methyl methacrylate) were established by comparison of their NMR spectra with those of poly(methyl methacrylate), poly(chloromethyl methacrylate), and a copolymer of methyl β‐chloromethylacrylate with methyl methacrylate. In chlorinated poly(methyl methacrylate) having 0.5 chlorine atoms per monomer unit, half of the chlorine is on the ester methyl group and half is on the β‐carbon atom. In the suspension chlorinated sample containing one chlorine per monomer unit, 20% of the chlorine is present as OCHCl2 groups, 40% as OCH2Cl groups, 30% as CHCl groups, and 10% as CCH2Cl groups. In a solution chlorinated sample containing two chlorine atoms per monomer unit, the chlorine is distributed: 40% as OCH2Cl, 40% as CHCl and/or CCH2Cl, and 20% as OCHCl2.
Ultraviolet irradiation of plastics. IV. Further studies of environmental effects on films and fibers
Authors: Stephenson C. V. , Wilcox W. S. 
Published: April 2003

AbstractPolyethylene, nylon, Mylar, Teflon, and Dacron all deteriorated more rapidly during ultraviolet irradiation when irradiated in oxygen than when irradiated in nitrogen. Deterioration during vacuum irradiation is less rapid than it is during oxygen or nitrogen irradiations for all of these polymers except Teflon, in which case it is more rapid. Environmental effects were not evident during the irradiation of HT‐1. A scission‐to‐crosslinking ratio of 0.93 has been determined for ultraviolet‐irradiated polyethylene.
Effects of high energy irradiation on polypropylene
Authors: Chappell S. E. , Sauer J. A. , Woodward A. E. 
Published: April 2003

AbstractIsotactic polypropylene (Profax) film samples irradiated in the Pennsylvania State University (PSU) reactor at ambient temperatures were examined by solvent extraction and infrared absorption techniques. At low irradiation doses, samples annealed (density = 0.909 g./cc. at 24°C.) prior to irradiation were found to have a lower gel content and a higher concentration of oxidation products than quenched samples (density = 0.899 g./cc. at 24°C.) irradiated under identical conditions. Similar gel fraction results were obtained for electron irradiated samples of polypropylene. These effects are believed to arise from the accumulation of a greater concentration of free macroradicals in the higher density samples. At higher reactor dosages the irradiation effects in the annealed and quenched films appear to be about the same. The gel content as a function of dose was found to be independent of the irradiation intensity level over a twofold range. Irradiations in the PSU reactor were also carried out on high density polyethylene (Marlex 50) pellets at two temperatures, viz., 40 ± 10°C. and 150°C. Irradiation at 150°C. led to a greater gel content at any given dose, a result in agreement with that reported by Lawton, Balwit, and Powell for electron‐irradiated specimens. Nuclear magnetic resonance spectra were obtained for molded annealed samples of partially isotactic polypropylene, irradiated in the Brookhaven reactor, at temperatures of 90–330°K. The observed shifts in the line narrowing process that occur in the 270–330°K. region are explained in terms of the decrease in crystallinity and the increasing density of crosslinks that accompany irradiation.
The preparation and polymerization of suberaldehyde
Authors: Koral Jerry N. , Smolin Edwin M. 
Published: April 2003

AbstractA study of the controlled polymerization of suberaldehyde has been carried out. The monomer was prepared by a new route, the catalytic reduction of the ozonate of cyclooctene. By the proper choice of catalyst and conditions, three different types of polymers could be prepared from suberaldehyde. A Tischenko condensation resulted in a pure linear polyester. The sodium hydroxide‐catalyzed polymerization of the aldehyde produced an aldol condensation polymer that was partially crosslinked through hemiacetal groups. The use of carbonyl polymerization catalysts such as triethylaluminum and boron trifluoride etherate, resulted in a polyacetal type of polymer containing free pendent carbonyl groups.
The effect of molecular weight distribution on the optical properties of polystyrene in the transition region
Authors: Rudd J. F. , Gurnee E. F. 
Published: April 2003

AbstractBirefringence measurements during relaxation of stress have been made on five narrow molecular weight distribution (anionic) polystyrenes at temperatures of 91.5, 95.0, and 98.5°C. One broad distribution (isothermal) polystyrene was measured at 91.5°C. The birefringence vs. log time curves obtained are observed to pass through a maximum, the magnitude of the maximum being independent of molecular weight above M̄w = 154,000 and increasing with temperature at constant M̄w. Increasing molecular weight heterogeneity causes the birefringence decay curves to shift to later times and broaden slightly, and the magnitude of their maxima to decrease. Decay data previously obtained on a plasticized commercial polystyrene are presented and shown to be in agreement with present findings. No substantial change in energy of activation associated with the decay process (Ea = 150 kcal./mole) is observed with either broadening of molecular weight distribution or with plasticization.
Long‐chain branching frequency in polyethylene
Authors: Guillet J. E. 
Published: April 2003

AbstractA study was made of the long‐chain branching frequency of polyethylene by using data on polyethylene fractions reported by Moore and co‐workers. It was found that the frequency of long‐chain branching does not increase with increasing molecular weight, as predicted by Beasley's theory, but remains relatively constant. This means that molecular weight distributions calculated by assuming the validity of the Beasley relations will be broader than those determined experimentally. It was also found that the viscosity—molecular weight relation for branched fractions can be constructed from a knowledge of g, a parameter related to the mean square radius of gyration of the molecules, assuming only the validity of the relation g3/2 = [η]br/[η]lin. A method was developed for determining γ*, which is the frequency of long‐chain branches corrected for short‐chain branching. Since the value of γ* is nearly constant throughout the distribution, determination of γ* for a high molecular weight fraction allows the construction of the complete viscosity—molecular weight relation for all fractions of the same polymer. This relation can then be used to characterize the molecular weights of the fractions and hence the shape of the actual molecular weight distribution curve.
Acid behavior of carboxylic derivatives of cellulose. Part I. Carboxymethylcellulose
Authors: Chowdhury F. H. , Neale S. M. 
Published: April 2003

AbstractThe potentiometric and viscometric behavior of carboxymethylcellulose have been studied with solutions containing potassium chloride. It has been found that the titration results can be described by the modified form of the Henderson equation pH = pKm + nlog α/(1 — α), the values of pKm and n being dependent on the concentration of both carboxymethylcellulose and the concentration of potassium chloride in the system. Extrapolation of the straight‐line pK versus α to α = 0 yields a value of 3.42 for pK0 which is identical with the pK value of galacturonic acid. The concentration dependence of pH for any given value of α can be described by the equation [pH]cα = [pH]0α – 0.52√c where [pH]0α is the pH at a concentration c and degree of dissociation α, and [pH]0α is the corresponding value extrapolated to infinite dilution. Both the viscosity and the potentiometric results show that the carboxyl groups in CMC are not free from electrostatic interactions but that at a salt concentration of 1M electrostatic effects almost disappear.
Acid behavior of carboxylic derivatives of cellulose. Part II. Oxycellulose
Authors: Chowdhury F. H. , Neale S. M. 
Published: April 2003

AbstractThe acid behavior of nitrogen dioxide, periodate—chlorite, and alkaline hypobromite oxycelluloses in presence of potassium chloride solutions of different concentrations has been studied. Experimental results indicate that the carboxylic groups in oxycelluloses are not free from mutual electrostatic interactions. In agreement with the behavior of carboxymethylcellulose and other soluble polyelectrolytes, the pK values increase with increasing degree of dissociation and decrease with increasing concentration of potassium chloride in the system. The titration results can be described by the modified from of the Henderson equation pH = pKm + n log α/(1 – α), the value of n being always greater than unity. Experimental results have also been treated in an entirely new way, that of splitting the system into two equipotential phases: (1) the internal phase consisting of both the oxycellulose and its imbibed solution and (2) the external fluid phase. The Donnan theory of membrane equilibrium has been applied in calculating the internal pH values. It has been found that although the measured external pH values decrease considerably with increasing salt concentration, the calculated internal pH values are independent of salt concentration.
Stereoregulated poly‐dideuteroethylene I. Polymers of trans‐1,2‐dideuteroethylene and cis‐1,2‐dideuteroethylene by a ziegler catalyst
Authors: Ikeda Sakuji , Yamamoto Akio , Tanaka Hiroshi 
Published: April 2003

AbstractPolydideuteroethylenes having some stereoregulated structure were prepared by polymerizing trans‐ and cis‐1,2‐dideuteroethylene using a Ziegler catalyst. trans and cis‐dideuteroethylene were prepared by reducing dideuteroacetylene with chromous chloride solution and copper activated zinc dust, respectively. Infrared spectra of the two polymers obtained showed significant differences particularly in the bending vibration bands of CHD groups. Bands at 1335 and 1288 cm.‐1 were observed only in polymers of the trans isomer, and a band at 1305 cm.‐1 was observed only in polymers of the cis isomer. Densities, melting points, intrinsic viscosities, and crystallinities of the polymers were measured and compared with those of normal polyethylene. The x‐ray diffraction patterns of the polydideuteroethylenes were almost identical with that of normal polyethylene.