bluuebunny/crossref_metadata_2025 huggingface dataset:
The reference point for liquid relaxation processes. I. Melt viscosity of polystyrene
Authors: Miller A. A.
Published: April 2003

Recent theories have suggested or implied that below the experimental glass temperature, Tg, there exists a temperature, T0, which governs the temperature dependence of relaxation processes in a liquid. In the “free‐volume” approach, T0 should be associated with an “occupied” volume, v0. In the present paper, published melt viscosity—temperature data for a series of polystyrene fractions (M = 1675–134,000) are shown to conform to a “modified” Arrhenius equation: η = A exp {B/(T ‐ T0)}. From this and from a previous free‐volume treatment of the same data, the reference point (T0, v0) is derived. Either or both of these approaches indicate that this reference point is situated on the liquid specific volume—temperature curve, extrapolated linearly into the glass region. In the series of polystyrene fractions for which Tg increases from 40 to 100°C., the corresponding T0 values increase from 5 to 50°C. Further relationships between the parameters in the modified Arrhenius, the Doolittle free‐volume, and the Williams‐Landel‐Ferry (WLF) equations, are expressed.
Hydrolysis of cellulose triacetate crystals
Authors: Manley R. St. John
Published: April 2003

Crystals of cellulose triacetate were hydrolyzed in an attempt to obtain single crystals of cellulose. The hydrolyzed material retains the morphology of the triacetate crystals, but its crystalline state depends upon the method of hydrolysis. In an aqueous medium, polycrystalline cellulose is formed, while a nonaqueous medium gives an amorphous cellulose. The results suggest that the hydrolysis is accompanied by a disruption of the lattice and that recrystallization of the resulting amorphous cellulose is caused by the water.
Polymerization studies on allylic compounds. I
Authors: Baldwin M. G. , Reed Samuel F.
Published: April 2003

The polymerization of a series of α‐(substituted methyl) acrylates was investigated. Polymerization rate measurements showed that each of the monomers, though containing allylic hydrogen atoms, polymerizes readily. Polymer viscosity data were obtained which indicate that appreciable nondegradative chain transfer occurs with several of the monomers. An explanation for the rapid polymerization of the monomers was proposed.
Polymerization of vinyl ethers with magnesium compounds. I. Catalytic reactivity of magnesium halides
Authors: Iwasaki K. , Fukutani H. , Nakano S.
Published: April 2003

An attempt was made to summarize the activity of magnesium halides in the polymerization of vinyl ethers. Bulk polymerization was carried out at temperatures of 0–80°C. Methyl, ethyl, isopropyl, and isobutyl vinyl ethers were used as monomers, and the relative reactivities of these monomers were compared. Except for the fluoride, magnesium halides had mild activity. Within a given group, the overall activation energies of polymerization decrease with increasing weight of halogen. On the other hand, the molecular weight of polyvinyl ethers obtained from this group of catalysts increases with decreasing weight of halogen. In addition, some differences were observed between the diethyl ether complex and the dioxane complex of magnesium bromide.
Bulk copolymerization of methyl methacrylate with phenyldichlorophosphine
Authors: Boryniec Atanazy , Łaszkiewicz Bogumił
Published: April 2003

Copolymers of methyl methacrylate with phenyldichlorophosphine were isolated as compact, incombustible, and colorless thermoplastic resins. The copolymerization was carried out at 60°C. by the standard bulk method, azobisisobutyronitrile being used as catalyst. The experiments indicate that in the investigated reaction there are concurrent processes which lead to degradation. The effect of duration of the copolymerization process and the content of phenyldichlorophosphine in the methyl methacrylate copolymer on the extent of reaction and on the intrinsic viscosity of copolymer has been investigated.
Enthalpy and free energy changes in some simple polymerization processes
Authors: Parks George S. , Mosher Helene P.
Published: April 2003

The heats of combustion of four polymers, viz., polyoxymethylene (Delrin), polymethylene, polyethylene (Marlex), and polypropylene, have been accurately measured. From these results the changes in enthalpy and free energy have been calculated for (a) the process of forming the respective polymer units from the elements and (b) the process of forming these polymers from their monomer building blocks.
Copolymerization of styrene and aliphatic olefins
Authors: Overberger C. G. , Miyamichi Kazuo
Published: April 2003

An attempt has been made to study the composition of the products resulting from polymerization of equal molar amounts of styrene and 4‐methyl‐1‐pentene and styrene and 3‐methyl‐1‐butene with vanadium oxytrichloride and aluminum triisobutyl as the catalyst system. Fractionation of the products has revealed that some copolymers can be obtained with both olefins—a larger amount of copolymer being obtained with 4‐methyl‐1‐pentene. Homopolymerization of both styrene and the α‐olefin also occur. Qualitatively, in this catalyst system, the order of the polymerization rate is 4‐methyl‐1‐pentene‐1 > styrene > 3‐methyl‐1‐butene. The results again collaborate the authors' early work that the copolymers obtained are not of uniform composition.
Mechanism of secondary crystallization in polymers
Authors: Rybnik´ř F.
Published: April 2003

In isothermal crystallization of polymers, where the fusion preceding the crystallization process is conducted at relative low temperatures or in samples subjected to γ‐radiation, there is extensive secondary crystallization. Secondary crystallization, which has been found to start stepwise at a time equal to two half‐times of primary crystallization, represents a new process of crystallization following the Avrami equation with n = 1. In addition to this crystallization process a further slow increase of crystallinity with time takes place.
Some anomalous brittleness temperatures of polyethylene
Authors: Rudin A. , Mackie J. S.
Published: April 2003

Rabesiaka and Kovacs have reported experiments in which the shapes of crystallization isotherms of several polyethylenes depended on the sample history as well as the intrinsic properties of the polymers. The suggestion was made that, in general, molten polyethylene is not in a true thermodynamic equilibrium and includes some quasi‐indestructible clusters, which act as heterogeneous nuclei in the crystallization process. This paper reports anomalous brittleness temperature experiments on polyethylenes, the results of which are explainable in terms of quasi‐indestructible clusters. The data are consistent with the supposition that the crystalline embryos responsible for the observed behavior result from strong entanglements or cross‐linking in natural polyethylene and from binding to carbon black surfaces in black compounds. At the low, nonuniform shear rates in compression molding these clusters may survive relatively intact. If subsequent remelting is performed in the absence of shear, any ordered structure between entanglement points will expand but not break. Such configurations can contract to form crystalline embryos as the polymer is cooled.
Polycondensation of xylylene dibromides by transition metals in water suspension
Authors: Sisido Keiiti , Kusano Nobuo , Noyori Ryôzi , Nozaki Yôko , Simosaka Masatosi , Nozaki Hitosi
Published: April 2003

Treatment of benzyl chloride with iron powder in water suspension results in the formation of benzyl radicals, which are subsequently dimerized into bibenzyl. This reaction has now been extended to p‐xylylene dibromide under a set of conditions as summarized in Table I. High yields (70–80%) of poly‐p‐xylylene, which was identified by infrared spectrum, x‐ray diffraction pattern, and other properties, were obtained with reduced iron suspended in a mixture of xylene and water (50:50) or in dimethylformamide. Zinc powder coated with nickel (Urushibara nickel CB) gave comparable yields of poly‐p‐xylylene, while cobalt powder or zinc—cobalt couple afforded inferior yields. Similar reaction of o‐ and m‐xylylene dibromides gave soluble polymers. The presence of o‐xylylene as an unstable intermediate of the polymerization of o‐xylylene dibromide has been indicated by trapping this transitory hydrocarbon with acrylonitrile and with methyl acrylate as diene adducts.
Elektronenspinresonanz‐untersuchungen an peroxydradikalen in bestrahltem polypropylen
Authors: Fischer H. , Hellwege K.‐H. , Neudörfl P.
Published: April 2003

Peroxide radicals are formed by oxidation of carbon radicals in irradiated isotactic polypropylene. An interpretation of their ESR‐spectra is given. The recombination of the peroxide radicals follows a chain reaction mechanism, which is derived from the reversibility of formation of peroxide radicals, the time dependence of their concentration, and from the oxygen consumption of samples containing peroxide radicals. The reactions are discussed in view of the radiation induced oxidative degradation of polypropylene.
Crystallinity in ethylene—propylene copolymers
Authors: Jackson J. F.
Published: April 2003

A mathematical expression has been developed which treats crystalline content of ethylene—propylene copolymers as a function of monomer sequence length distribution in the copolymer chains. The model is based on the Goldfinger‐Kane mathematical relationship for sequence length distributions derived from the conventional copolymer equation. Use of the general Flory theory for depression of the crystalline melting point by copolymerization provides independent evidence in substantiation of the model.
Irradiation of polyethylene oxide and polypropylene
Authors: Salovey R. , Dammont F. R.
Published: April 2003

The solubility behavior of electron‐irradiated (in vacuo) polyethylene oxide indicates a ratio of main‐chain scission density to the density of crosslinked units of 0.6, independent of molecular weight. This value, derived from measurements at high doses, correlates well with the observed increase in intrinsic viscosity and invariance of number‐average molecular weight at low irradiation doses. Analogous measurements on polypropylene indicate a linear dependence of S + S1/2 (where S is the sol fraction of the irradiated polymer) on the reciprocal irradiation dose. This treatment leads to a ratio of scission‐to‐crosslinking of 0.8. Increased scission in polypropylene as compared to polyethylene oxide is evidenced by a gradual decrease in the intrinsic viscosity as a function of dose. This decrease is not indicative of an initial irradiation degradation of the polymer, because the number‐average molecular weight is relatively unaffected by irradiation until quite close to the gel point. The intrinsic viscosity of the progressively crosslinked polymer is apparently depressed by branching. Direct comparison of the results on polypropylene with theory is uncertain because of a nonrandom initial molecular weight distribution. It is reemphasized that the intrinsic viscosity is not a simple indication of molecular weight changes in crosslinking polymers.
The role of metal chelates in polymerization initiation. I. Chromous chelates
Authors: Bond Joan , Hobson D. B.
Published: April 2003

The polyaminocarboxylic acids, ethylenediaminetetraacetic acid (EDTA), cyclohexanediaminetetraacetic acid (CDTA), and diethylenetriaminepentaacetic acid (DTPA) have been used to chelate the chromous and chromic ions when the system chromous ion—hydrogen peroxide is being used as an initiator for the emulsion polymerization of styrene. With CDTA and DTPA the zero‐order rates of polymerization increase continuously with increasing pH but with EDTA the zero‐order rate is constant over the range pH 5–7 and increases rapidly above pH 7. These results are to be anticipated from the variation of the redox potential of the chromous ion‐chromic ion‐chelating agent system with pH, since with CDTA and DTPA the redox potential decreases continuously with pH while with EDTA the redox potential varies only slightly over the range pH 5–7.
The role of metal chelates in polymerization initiation. II. Cupric chelates
Authors: Bond Joan , Hobson D. B.
Published: April 2003

The 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.
Polymerization of acrylonitrile in dimethylsulfoxide
Authors: White E. F. T. , Zissell M. J.
Published: April 2003

Kinetic constants for the polymerization of acrylonitrile in dimethylsuifoxide have been measured and compared with those for dimethylformamide solution.
Ebulliometric and endgroup molecular weights of polyoxypropylene and polyoxyethylene glycols
Authors: Havlik A. J. , Moacanin J. , Otterness I.
Published: April 2003

A 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

Bicyclo[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

The 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.
Graft copolymers of polyacrylic acid with desoxyribonucleic acid (DNA)
Authors: Kwei Kwei‐Ping Shen
Published: April 2003

Graft copolymers of polyacrylic acid with DNA were prepared and isolated. The grafted DNA copolymers had different solubility behaviors and ultraviolet absorption characteristics than those of the DNA.
Elution fractionation of crystalline polypropylene
Authors: Mendelson Robert A.
Published: April 2003

A 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

Osmotic 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

Polymerization 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

A 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

The 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

The 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

Plasticized 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

A 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

Differential 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

The 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

Polyethylene, 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

Isotactic 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

A 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

Birefringence 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

A 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

The 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

The 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

Polydideuteroethylenes 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.
Structure effects and related polymer properties in polybutadiene. I. Preparation and characterization
Authors: Berger M. , Buckley D. J.
Published: April 2003

Stereoregular polybutadienes, of both high trans and high cis contents, were isomerized to provide polymers of varying cis‐trans content. These isomerizates were used to study structural effects on physical properties. The isomerizations were carried out under photosensitized conditions in benzene solution at 25°C. The reaction was controlled to deliver polymers over the range 0–95% trans content. This range was selected to provide crystalline and semicrystalline polymers whose structures could be examined in terms of sequencing or blocking by established x‐ray techniques. Isomer contents were measured accurately by infrared traces. Isomerizations reached an equilibrium of 77% trans regardless of whether the reaction started with high trans or high cis polybutadienes. Intrinsic viscosity was found to increase regularly with trans content in conformity with the larger size of the trans unit. ηsp/c versus c relations were observed to give a complicated form and this subject was deferred for further study. Crystallinity decreased regularly with reduced trans content as the equilibrium of 77% trans was approached. Continued isomerization at the point of equilibrium produced a completely amorphous polymer. The melting temperatures of the crystalline polymers were studied in detail by x‐ray camera and counting techniques. These polymers exhibited two crystal forms. One form was stable up to 60°C. and invariant with cis‐trans content in the range 80–95% trans. Below 80% trans the melting point of this form decreased with further reduction in trans content. The melting temperature of the other crystal form was dependent on trans content and decreased with decreased trans content until it coincided with the melting temperature of the other form. The distributions of trans and cis units and sequences of them were calculated through construction of matrices of transition probabilities. Copolymer theory was invoked to calculate pseudo reactivity ratios for the trans and cis forms. The melting temperatures of the two crystals were found to follow the predicted curves for random copolymers, although not simultaneously. This behavior is discussed. The crystallinity of the isomerizates of high trans content was found to be similar to block copolymers in spite of the fact that the method of their preparation would require that they be characterized as random. The importance of a crystal transition in this case is stressed along with the general effects due to the amount and type of the noncrystallizable unit.
Swelling of highly crosslinked network structure
Authors: Kwei T. K.
Published: April 2003

The swelling of highly crosslinked epoxy polymer films by organic vapor was investigated. The molecular weight per crosslinked unit obtained by applying the equation of rubber elasticity to sorption isotherms is in good agreement with the value estimated from chemical considerations. Thermodynamic functions of solvent—polymer mixing are also presented.
Etude dela polyméarisation des oléafines catalysee par les oxydes méatalliques. I. Méathodes expéarimentales d'etude cinéatique; réasultats préaliminaires sur la polymégrisation du propylégne par le systégme catalytique phillips
Authors: Guyot Alain , Daniel Jean‐Claude
Published: April 2003

The kinetics of propylene polymerization catalyzed by chromium oxide on an aluminium silicate carrier was studied by a new method involving use of gas chromatographic analysis of samples removed from the monophase fluid medium surrounding solid catalyst and containing monomer and propane, without any other solvents. The apparatus and experimental methods are described in detail. The reaction is first‐order with respect to monomer, and also to catalyst if its concentration is high enough. Between 80 and 120°C, the activation energy is 16 kcal./mole. The polymerization rate depends on pressure only with respect to monomer concentration, but, when the pressure is low and the temperature high enough, a second process occurs which causes formation of volatile oligomers and retardation of normal polymerization process. The influence of catalyst and carrier structure and texture will be the subject of a subsequent study.
On Co60 gamma ray‐initiated emulsion polymerization
Authors: Acres G. J. K. , Dalton F. L.
Published: April 2003

A study has been made of the Co60 γ‐ray‐initiated polymerization of methyl methacrylate and styrene; conversion rates have been measured by a dilatometric method. The dependence of polymerization rate on monomer concentration and radiation intensity has been determined for each monomer. It has been shown that the emulsion polymerization of methyl methacrylate can be described by accepted theories of emulsion polymerization; in the case of styrene a dependence of intensity exponent on monomer concentration has been found. Such a dependence does not occur when conventional initiating systems are used, and cannot be explained without some modification of theory.
Some viscoelastic studies on penton
Authors: Sharma M. G. , Haas T. W.
Published: April 2003

Stress relaxation tests on Penton polymer were conducted at various initial strain rates and initial strains. The data indicates that Penton is a nonlinearly viscoelastic material for the range of values of stresses and strains considered. It is found that the course of the relaxation depends considerably on the initial strains rates employed to attain a particular initial strain in a relaxation test. For the range of initial strain rates considered, the relaxation function can be represented as a function of the time ϕ(t) and by a power function of the strain rate ε0 of the type Ψ(t,ε0) = ϕ(t)(ε0)n. From the relaxation tests conducted at the same initial strain rate and for various initial strains, the relaxation stress σ for Penton can be expressed by the relation: σ = σ0 (1 − k log t), where σ0 is the stress at 1 min., t is the time, and k is a material constant.
The diffusion of chrysophenine G into viscose sheet
Authors: Warwicker J. O.
Published: April 2003

An experimental investigation into the diffusion of a direct dye into the edges of a viscose sheet is described. The results of these experiments are used to test the diffusion‐adsorption theory of Standing, Warwicker, and Willis. It is shown how this theory can be extended to allow for the effect of sodium chloride concentration on the diffusion coefficients.
Evaluation of molecular weight averages resulting from random crosslinking and chain scission processes for wide schulz‐zimm distributions
Authors: Kotliar A. M.
Published: April 2003

The Monte Carlo sampling technique was used to evaluate the resulting molecular weight averages and the intrinsic viscosity for wide Schulz‐Zimm distribution polymers, in the range P̄w/P̄n ≦ 11, undergoing random chain scission and crosslinking processes. The results may also be used to evaluate the initial distribution and are generally more reliable than the use of fractionation data.
General theory of stationary random sequences with applications to the tacticity of polymers
Authors: Coleman Bernard D. , Fox Thomas G
Published: April 2003

When, in a poly‐α‐olefin, the probability that a given placement be isotactic depends upon the tacticity of only a finite number of immediate predecessors, the resulting diastereosequence distribution obeys the theory of Markoff chains. When this is not the case, one says that the resulting diastereosequence distribution is non‐Markoffian. A special case of a Markoffian distribution is given by a simple Markoff chain in which the tacticity of a given placement is assumed to be affected by only the tacticity of the immediately preceding placement. Another special case is, of course, the Bernoulli trial distribution in which the probability that a given placement be isotactic is independent of the tacticity of all other placements. A high resolution NMR spectrum can sometimes yield a quantitative determination of the concentrations of isotactic and syndiotactic placements and the concentrations of the three types of possible adjacent pairs of such placements (i.e., isotactic, syndiotactic, and heterotactic pairs). When this is the case, the spectrum can be used to determine whether or not a given diastereosequence distribution is Bernoullian. However, because the longest diastereosequences whose concentration can be measured by NMR spectroscopy involve only two placements, an NMR spectrum cannot check whether a given non‐Bernoullian distribution be simple Markoffian or Markoffian in general. In fact, non‐Markoffian distributions are compatible with existing NMR spectra on polymers prepared by anionic polymerizations. In this paper we work within the framework of Kac's theory of stationary statistical processes and point out some general results which are valid for both Markoffian and non‐Markoffian processes. The results are applied to NMR spectroscopy and it is pointed out which calculations used to check the self‐consistency of NMR data and to obtain the mean length of closed diastereosequences are valid for both Markoffian and non‐Markoffian distributions.
Colligative properties of polyelectrolyte solutions in excess of salt
Authors: Alexandrowicz Z. , Katchalsky A.
Published: April 2003

This work treats the equilibrium properties of polyelectrolyte solutions containing an excess of low molecular salt. In this case the simple rule of additivity, dealt with previously, fails to describe the experimental results. A detailed treatment, based on an approximate solution of the Poisson‐Boltzmann equation, was therefore undertaken. The calculation is based on a subdivision of the electrostatic potential into two parts corresponding to two regions: (1) an inner region in the close neighborhood of the polyion, free of coions and described by the Poisson‐Boltzmann equation in the salt‐free case, and (2) an outer region screened off from the central macroion and adequately treated by a Debyean approximation. An analytical solution for the electrostatic potential was obtained and used for the theoretical description of potentiometric behavior, Donnan distribution of salt, and Donnan osmotic pressure. The predicted values compare favorably with the measured results in a wide range of experimental conditions.
Interpretation of the intrinsic viscosity of polymers undergoing simultaneous degradation and crosslinking
Authors: Inokuti Mitio , Dole Malcolm
Published: April 2003

An attempt is made in this paper to calculate G values for simultaneous crosslinking and degradation during irradiation of polymers with side chains. Equations are given for the change in the weight‐average to number‐average molecular weight ratio as a function of dose for the case of degradation only. It is shown that the change in the logarithm of this ratio with the square root of the dose goes through a broad maximum over a certain dose range. This result coupled with estimates of Katsuura of the effect of branching on the intrinsic viscosity is used to explain the relationship discovered by Keyser, Clegg, and Dole between the logarithm of the intrinsic viscosity and the square root of the dose. It is concluded that the G value for degradation must change with dose; in the case of poly‐1‐hexene, for example, it is believed that G(S) falls from an initial value of about 0.15 to about 0.04 at high doses. Similar conclusions result from an application of the equations to polypropylene, but with higher values of G(S), about 1.1 initially and dropping about tenfold at doses above the gel point.