bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron spin resonance study of polymerization of butadiene with tris(acetylacetonato)titanium and triethylaluminum
Authors: Hiraki Katsuma , Inoue Takeo , Hirai Hidefumi
Published: April 2003

ESR spectra of homogeneous catalyst derived from tris(acetylacetonato)titanium(III) and triethylaluminum were observed at several temperatures from −78°C, to +25°C, at molar ratios of aluminum to titanium of 1–108. At −78°C, this catalyst yields a violet complex which shows an ESR signal with a g value of 1.959 and is associated with the first intermediate. At −40°C to −30°C, this signal decreases, and two signals with g values of 1.947 and 1.960 are observed. The latter two signals diminish at −5°C to +10°C, while two kinds of new signals with g values of 1.965 and 1.969 appear overlapping each other. The structures of the species corresponding to these five signals are discussed on the basis of the ESR spectra, the intensity change, and the unpaired spin distribution. A new signal with a g value of 1.978 is found in the presence of butadiene at 25°C at Al/Ti > 8 and is assigned to a growing end of polybutadiene with this catalyst. The polymer yield increases remarkedly at Al/Ti molar ratios greater than 10. The microstructure of the resulting polymer consists almost completely of 1,2 units. The structure of the growing end is proposed to be a titanium (III) species containing two 1‐substituted allyl groups, by comparison with the structure ascribed to the growing end of polybutadiene with n‐butyl titanate‐triethylaluminum catalyst.
The reaction between diethyl succinylsuccinate (1,4‐diethoxycarbonyl‐2,5‐dihydroxy‐1,4‐cyclohexadiene) and amines and its application to polymer synthesis
Authors: Higashi Fukuji , Tai Akira , Adachi Kazuo
Published: April 2003

Polymers having polyamine structures were obtained by the condensation reaction between diethyl succinylsuccinate (1,4‐diethoxycarbonyl‐2,5‐dihydroxy‐1,4‐cyclohexadiene) and aliphatic diamines. The reactions were carried out in high polar solvents such as N‐methylpyrrolidone (NMP) and N,N‐dimethylformamide (DMF). The mode of the polymerization reaction and the structure of the polymers were verified by studies of model compounds. The polymers thus obtained were conveniently utilized as coating and adhesive materials and were able to be cast into films.
Polymerization and crosslinking of epoxides: Base‐catalyzed polymerization of phenyl glycidyl ether
Authors: Banks P. , Peters R. H.
Published: April 2003

The anionic polymerization of 2,3‐epoxypropyl phenyl ether initiated by sodium methoxide and dimsyl sodium in dioxane and in dimethyl sulfoxide has been studied. Kinetic and dielectric constant measurements have been recorded, and a mechanism for the initiation reaction with dimsyl sodium has been put forward. Polymerization initiated with dimsyl sodium revealed almost total absence of sulfur in the polymer by endgroup analysis. The reaction was shown to be inhibited by oxygen. Molecular weight determinations have indicated a reaction involving transfer to give polymers of lower than calculated M̄n and a ratio of kp/ktr ratio of approximately 73. Gel‐permeation chromatography suggests a narrow molecular weight distribution in the polymers prepared.
A study on the mechanism of polyvinyl chloride stabilization by lead salts
Authors: Zilberman E. N. , Kulikova A. E. , Meiman S. B. , Okladnov N. A. , Lebedev V. P.
Published: April 2003

Infrared spectroscopic and DTA measurements and chemical analysis have shown that during stabilization of PVC with organic and inorganic basic lead salts various reactions occur: (a) binding of the evolved HCl, by these salts with the formation of lead chloride and complexes, including HCl, which catalyze the PVC degradation; (b) complex‐forming reaction with the reactive PVC groups, which decreases the intensity of color of the polymer. In addition, with weak‐organic‐acid basic lead salts, exchange of labile Cl atoms for acid residues in PVC occurs, which results in an increase in inherent polymer stability.
Thermal degradation of copolymers of styrene and acrylonitrile. II. Reaction products
Authors: Grassie N. , Bain D. R.
Published: April 2003

Hydrogen cyanide is a minor product of degradation of copolymers of styrene and acrylonitrile. The liquid products have been separated and identified by combined gas chromatography and mass spectrometry (GC‐MS), as styrene, acrylonitrile, toluene, and benzene. The ratio of styrene to acrylonitrile monomers in the products is approximately twice that of the monomer units in the copolymers, and the ratios of styrene to toluene and benzene are the same as are obtained from pure polystyrene. These ratios were determined by using infrared spectral methods. The fraction of products volatile at the temperature of degradation but involatile at ambient temperature was also analyzed by using GC‐MS. A series of four dimers and four trimers were fairly reliably identified. The residual material from copolymers containing up to 33.4% acrylonitrile is always soluble in toluene. The 50/50 copolymer and its residues are insoluble in toluene. Yellow coloration develops in the residues from high acrylonitrile copolymers at advanced stages of degradation. Infrared and ultraviolet spectra suggest that this is due to conjugated unsaturation in the polymer chain backbone which may be associated with the liberation of hydrogen cyanide from the acrylonitrile units.
Thermal degradation of copolymers of styrene and acrylonitrile. III. Chain‐scission reaction
Authors: Grassie N. , Bain D. R.
Published: April 2003

The chain‐scission reaction which occurs in copolymers of styrene and acrylonitrile has been studied at temperatures of 262, 252, and 240°C. Under these conditions volatilization is negligible, and chain scission can be studied in virtual isolation. At 262°C three kinds of chain scission are discernible, namely, at weak links which are associated with styrene units, “normal” scission in styrene segments of the chain and scission associated with the acrylonitrile units. The rate constants for normal scission and scission associated with acrylonitrile units are in the ratio of approximately 1 to 30. The molecular weight of the copolymer has no effect on the rates of scission. At 252°C the same general behavior is observed for the copolymers containing up to 24.9% acrylonitrile. The 33.4% acrylonitrile copolymer is anomalous, however. At 240°C the trends observed at 262°C appear to break down completely although individual experiments are quite reproducible. This behavior at the lower temperatures is believed to be associated with the fact that the melting points of the various copolymers are in this temperature range. Thus the viscosity of the medium, which should be expected to have a strong influence on the chain scission reaction, will be changing rapidly with temperature, copolymer composition, and molecular weight in this temperature range.
Molecular weight development in constant‐rate styrene emulsion polymerization
Authors: Grancio M. R. , Williams D. J.
Published: April 2003

Continuously uniform latices were applied in an experimental study of molecular weight development in constant‐rate styrene emulsion polymerization. The formulation around which this study centered exhibited Smith‐Ewart, case II kinetics from zero to about 60% conversion with a constant conversion rate of 13 ± 2%/hr and a final particle diameter of 2300 Å. By utilizing an inhibitor perturbation technique, we directly confirmed that free radicals are generated from K2S2O8 by a first‐order process with 100% efficiency. We further confirmed that, in contrast to current theories for constant rate polymerization, both the instantaneous values of M̄n and M̄v may increase 6‐ to 9‐fold. Little or no chain branching is evidenced. We interpret these findings to mean that radicals are not utilized with 100% efficiency in emulsion polymerization.
Poly‐2‐oxazolidones: Preparation and characterization
Authors: Herweh J. E. , Whitmore W. Y.
Published: April 2003

Poly‐2‐oxazolidones were synthesized by the 1,3‐cycloaddition of bisglycidyl ethers to diisocyanates with the use of N,N‐dimethylformamide and lithium chloride as solvent and catalyst, respectively. A variety of arylene and alkylene diisocyanates and coreactant bisepoxides were used in the polymer‐forming reaction. The polymers, obtained in high yield, were generally soluble in methylene dichloride, chloroform, N,N‐dimethylformamide, and dimethyl sulfoxide. They had intrinsie viscosities up to 0.42 dl/g and could be cast into films. In several cases molecular weights were determined by vapor pressure osmometry. The poly‐2‐oxazolidone based upon 1,6‐hexamethylene diisocyanate and the bisglycidyl ether of isopropylidene diphenol gave the highest molecular weight. Confirmation that the base unit of the polymers contains the 2‐oxazolidone ring was obtained by elemental analysis, infrared and NMR spectroscopy. The poly‐2‐oxazolidones synthesized were found to be amorphous by x‐ray diffraction. Thermogravimetric analyses indicated that a majority of the poly‐2‐oxazolidones were stable in dry air up to 300°C. In a number of cases Tg's were also determined by using differential scanning calorimetry.
Polymerization of vinyl monomers by diphenylsulfone–potassium complexes
Authors: Hirahara Takuji , Sugimura Takaaki , Minoura Yuji
Published: April 2003

Diphenylsulfone (DPSO2) was found to react with an equimolar amount of potassium in tetrahydrofuran (THF), dimethoxyethane (DME), or diglyme (DG) at reflux or an elevated temperature to yield a reddish‐black solution, giving an electron spin resonance (ESR) signal. The signal was attributed to the formation of relatively labile DPSO2 anion radical. The apparent effects of solvents on the reactivity of DPSO2 with potassium depended on the polarities and the solvation powers: benzene ≅ toluene ≅ dioxane ≪ tetrahydrofuran < monoglyme < diglyme. The monopotassium complex was found to react further with another molecular amount of the metal to yield a dark blue solution giving no ESR signal.

The monopotassium complex initiated the polymerization of acrylonitrile (AN). It did not, however, initiate the polymerization of methyl methacrylate (MMA), styrene (St), or isoprene (IP). The active species of the monopotassium complex that initiated the polymerization of AN was found from analyses of the reaction products and the infrared spectrum of oily oligomer of AN obtained by the complex to be potassium benzenesulfinate. The dipotassium complex was found to initiate the polymerization of MMA, St, IP and AN. The active species of the dipotassium complex that initiated the polymerization of MMA, St, or IP was found from analyses of the reaction products and the infrared spectrum of the oily oligomer of MMA obtained by the complex to be phenyl potassium.
Calorimetric investigation of polymerization reactions. IV. Curing reaction of polyester fumarate with styrene
Authors: Horie Kazuyuki , Mita Itaru , Kambe Hirotaro
Published: April 2003

The curing reaction of polyester fumarate with styrene was investigated with a differential scanning calorimeter (DSC) operated isothermally. The change in rate of cure was followed over the whole range of conversion. The rate of cure is accelerated by the gel effect to about ten to fifty times the rate of model copolymerization of diethyl fumarate with styrene. This autoacceleration is much enhanced for systems with higher crosslinking densities and at lower temperatures. The results confirm that both termination and propagation steps of the curing reaction are controlled by diffusion of polymeric segments and monomer molecules over almost the whole range of conversion. The final extent of conversion is short of completion for isothermal cure and even for postcure of polyester fumarate with styrene because of crosslink formation. The final conversion of isothermal cure decreases with increasing crosslinking density and shows a maximum with increasing reaction temperature. This temperature dependency of the final conversion is caused by the difference in the activation energies for two propagation rate constants kpf and kps, which were evaluated to be 7–10 and 5–8 kcal/mole, respectively, for the intermediate stage of the curing reaction.
Studies on polyesterification reactions: Calculation of the rates of reverse reactions
Authors: Vancsó‐Szmercsányi I. , Makay‐Bödy E. , Szabó‐Réthy E. , Hirschberg P.
Published: April 2003

Reactions between dicarboxylic acids and diols in the melt and leading to an equilibrium yield quantitative results which may be applied to the kinetics of some partial reactions of polyesterification. The relationship of the rate constants of the forward and the reverse reaction as well as of the equilibrium constant furnish valid results both in the absence of catalyst and in the presence of acid or basic catalysts. The values obtained for the energy of activation of the forward and the reverse reaction and of the overall reaction (13 ± 1 kcal/mole) also are in good agreement.
Polymérisation et copolymérisation cationiques des methylindenes
Authors: Maréchal Ernest
Published: April 2003

A study of cationic polymerization and copolymerization of methylindenes has been carried out by experimental methods and by means of quantic chemistry. The study showed a great variation among initiators in efficiency for the various monomers. The study of the effect of temperature on polymerization was carried out for dimethyl‐5,7‐indene. Polymerization enthalpies and reactivity ratios were determined; the values that were obtained allowed a classification of methylindenes with regard to their reactivity toward a single cation. Total electron densities, free valences, and mobile bond orders, frontier electron densities, and superdelocalizabilities on position 1 and 2 were calculated for all methylindenes. In determining location energies of the electronic double bond in position 2 and the stabilization energies at the time of the attack by a cation, a theoretical classification of the monomers with respect to their reactivity in cationic polymerization was obtained. The agreement between calculation and experimental results is shown to be satisfactory.
Mechanism of the polymerization of trifluoroacetaldehyde initiated by azobisisobutyronitrile
Authors: Busfield W. K. , Humphrey R. W.
Published: April 2003

The polymerization of fluoral initiated by the photolyzed decomposition of azobisisobutyronitrile at low temperature has been studied. Up to 2% conversion, the effect of radical scavengers and the order with respect to initiator and light intensity indicate that the reaction occurs by a conventional radical polymerization mechanism. At about 2% conversion autoacceleration sets in and the rates become irreproducible. This is explained by typical occlusion phenomena. Tracer studies show that polymer prepared at high conversion contains initiator fragments indicating that primary propagation is by monomer addition to radicals. The reaction mechanism is discussed.
Prehump in the gel‐permeation chromatography fractionation of pulp cellulose acetate
Authors: Tanghe L. J. , Rebel W. J. , Brewer R. J.
Published: April 2003

GPC chromatograms of cellulose acetate made from wood pulp customarily show a shoulder or small separate peak at the high end of the DP distribution. Material isolated from this “prehump” area is considerably enriched in mannose and xylose, and the size of the prehump in acetates from different pulps correlates with the amount of hemicellulose in the pulp. Prehump is not ordinarily found in cellulose acetate made from linters but was induced by adding mannan at the start of the acetylation, or by prolonging the acetylation beyond the time when the cellulose acetate sulfate triester is first formed. Products of poor solubility, as indicated by increased haze and false viscosity, resulted in both cases. Prehump was reduced in pulp cellulose acetate by many of the steps which give products of improved solubility: mercerization of cellulose prior to acetylation, use of more sulfuric acid catalyst, replacement of part of the acetic acid with methylene chloride during acetylation, and by removal of a small amount of high viscosity or poorly soluble material by fractional precipitation.
Polymerization ofcis‐ andtrans‐cinnamonitriles by anionic catalysts
Authors: Kobuke Yoshiaki , Fueno Takayuki , Furukawa Junji
Published: April 2003

cis‐ andtrans‐cinnamonitriles were polymerized in the presence of various anionic catalysts such as Grignard reagent, alkali metal naphthalenes, and calcium zinc tetraethyl. It was found that both monomers undergo concurrent geometrical isomerization as well as polymerization. Investigation on the calcium zinc tetraethyl catalyst showed that thetrans‐nitrile had polymerizability noticeably greater than that of thecisisomer. Polymers resulting from these isomeric monomers had different microstructures. These results seem to be interpretable in terms of the four‐centered coordination model of the transition state.
Production of organometallic polymers by the interfacial technique. X. Influence of the nature of base employed on the synthesis of polysilylalkylene (arylene) diamines
Authors: Carraher Charles E.
Published: April 2003

The influence of base type on polymerization and on polymer properties in the synthesis of polysilylalkylene(arylene)diamines by a modified interfacial system was investigated. The modified system utilizes 2,5‐hexanedione or acetonitrile in place of the usual aqueous solvent. Protonation of both diamine and amine groups in the polymer chain is important when NaOH or diamine itself is employed as the base. Protonation is unimportant when triethylamine is used. In triethylamine systems the highest yield is formed with the silane containing the most electron‐deficient silicon, and the highest molecular weight products are formed with the least sterically hindered silane. When NaOH or diamine itself is employed there is no apparent correlation between silane and amine electronic or steric nature and any of the measured polymer properties. As diamine solubility decreases, polymer yield increases.
Self‐regulating polycondensations: Ordered aromatic polyamide‐esters
Authors: Preston J.
Published: April 2003

The polycondensation of aminophenols with diacid chlorides was examined to determine if the amide‐ester polymers obtained are random or ordered. All of the evidence obtained points to the conclusion that ordered copolymers indeed are prepared and that a “self‐regulating” polymerization process is operating by virtue of the considerably greater reactivity of aromatic amino groups relative to phenol groups. The first step of the reaction involves the in situ preparation of a diphenol‐amide which undergoes further condensation. The diphenol‐amide intermediate may be isolated or reacted in situ. In addition to the ordered polymer from a given aminophenol and a single diacid chloride, ordered copolymers from two different diacid chlorides were prepared in which the diacid moieties appear in an alternating fashion; the structure of such polymers depends on the order of addition of the diacid chlorides. Corresponding polymers also may be prepared from the preformed diphenol‐amide monomers. The molecular weights of certain of the polymers were sufficient for the preparation of films which could be hot‐stretched severalfold. Interfacial polycondensations gave polymers of higher inherent viscosities than did solution polymerizations when aminophenols or diphenol‐amide monomers were condensed with diacid chlorides.
Photo‐oxidation of polymers without light: Oxidation of polybutadiene and an ABS polyblend with singlet oxygen
Authors: Kaplan M. L. , Kelleher P. G.
Published: April 2003

In recent years much evidence has been accumulated to implicate electronically excited oxygen (1Δg) molecules as the agent responsible in photosensitized oxidations for the formation of allylic hydroperoxides from olefins and of endoperoxides from 1,3‐dienes. Little regarding the mechanistic aspects of the photo‐oxidative degradation of polybutadiene (PBD) is known, however. To determine if electronically excited oxygen (1Δg) molecules can oxidize PBD, the ABS polyblend and standard samples of PBD's containing high trans, high cis, and high vinyl content were treated in homogeneous solution at low temperature with chemically produced singlet oxygen in situ. The source of the singlet oxygen was the triphenylphosphite‐ozone adduct. Studies by spectroscopy, elemental analysis, viscosity determinations, and gel measurements showed only the cis‐ and the trans‐PBD were susceptible to oxidation; no chain scission was involved in the attack of cis‐ and trans‐PBD by singlet oxygen; the oxidation of the cis PBD involved the initial formation of hydroperoxides which on thermal decomposition yielded gel. The trans‐PBD was found to oxidize but apparently by a mechanism different from that of cis‐PBD. Initial singlet oxygen attack of ABS proceeds by oxidation of the PBD portion of the polyblend. It was also observed that when only a small amount of the double bonds in the cis‐PBD polymer had been oxidized to hydroperoxides, subsequent thermal treatment of this sample resulted in gross structural changes in the whole polymer.
Polymers containing anthraquinone units: Polycondensations 1,2,5,6‐tetraaminoanthraquinone with some tetrachloroquinoxaline compounds
Authors: Banihashemi A. , Marvel C. S.
Published: April 2003

New ladder and partial ladder aromatic heteropolymers have been synthesized from 1,2,5,6‐tetraaminoanthraquinone, 2,3,7,8‐tetrachloro‐1,4,6,9‐tetraazaanthracene, 2,2′‐3,3′‐tetrachloro‐6,6′‐diquinoxaline, 2,2′,3,3′‐tetracholoro‐6,6′‐diquinoxalyl ether and 2,2′,3,3′‐tetrachloro‐6,6′‐diquinoxalyl sulfone. The polycondensations were carried out in solution and in melt. The inherent viscosities of polymers were in the range of 0.1‐0.44. These polymers were highly colored, showed good thermal stability and were soluble in concentrated sulfuric acid and methanesulfonic acid. The structures of the polymers were established by comparison with model compounds.
Copolymerization of aryldiazomethanes
Authors: Smets G. , Bourtembourg A.
Published: April 2003

Several aryldiazoalkanes (M2) have been copolymerized with phenyldiazomethane (M1) in toluene‐methanol solution at 40°C, namely, the p‐chloro‐, p‐methoxy‐, p‐mesyl‐o and ‐p‐methyl‐, 2,4‐ and 3,4‐dichlorophenyldiazoalkanes, and the α‐ and β‐ naphthyl‐diazoalkanes. The copolymerization parameters r1 and r2 have been evaluated. By plotting 1/r1 against the Hammett σ values a negative ρ values was found equal to −0.88. From cationic copolymerizations carried out at −78°C in the presence of boron trifluoride‐diethyl ether as catalyst a similar plot of 1/r1 against σ gives a value of ρ equal to −0.82. The negative sign and the agreement between these ρ values demonstrates the cationie mechanism of the methanol polymerization and copolymerization of aryldiazoalkanes.
Effect of swelling on radiation‐induced grafting of styrene to polyethylene
Authors: Machi Sueo , Kamel Ihab , Silverman Joseph
Published: April 2003

The radiation‐induced grafting of low‐density polyethylene in contact with styrene solution was studied. The effect of the degree of swelling of the polymer on the rate of grafting was investigated by diluting the styrene with methanol and with n‐octane. For styrene‐methanol solution, the rate of grafting was found to increase with degree of swelling, passing through a maximum when the sorbed solvent reaches 6.2 wt‐% (70 vol‐% methanol in the outside solution) and decreasing therafter. The methanol fraction of the sorbed liquid is far too small to cause precipitation of the grafted chains and inhibition of their termination rate. The dilution of styrene by octane has no effect on the swelling of polyethylene, but it decreases the grafting rate over the entire concentration range. The results are explained in terms of the concentration of sorbed monomer and the viscosity of the amorphous region of the polyethylene swollen by nonpolar liquids. Supporting evidence for the mechanism is presented in the form of grafting kinetic data as a function of dose rate (2.8 × 102−9.5 × 104 rad/hr), and post‐irradiation grafting measurements for polyethylene in methanol‐styrene (70/30, v/v). The data indicate that at the maximum grafting rate an optimum is achieved between a high concentration of sorbed monomer and a low viscosity for the poorly swelled polymer matrix.
Synthetic thermally reversible gel systems. VI
Authors: Haas Howard C. , MacDonald Ruby L. , Schuler Alan N.
Published: April 2003

Forming and conditioning thermally reversible aqueous gels of polyacrylyglycinamide (PAG) at various temperatures has little effect on either the melting point (Tm) of the gels or the heat of crosslinking (ΔHc) except at temperatures where partial hydrolysis can occur. This is added evidence that unlike with gelatin, crystallite formation does not play a role in gel formation. For unfractioned PAG, the linear relationship between the logarithm of molecular weight and 1/Tm predicted and observed for gelatin gels, does not hold. With mixed gelatin‐PAG gels, a gelatin/PAG ratio of ≥4 completely inhibits the formation of a PAG gel network. At lower gelatin/PAG ratios, the PAG network forms, and if gelatin is considered as an inert diluent, normal values for the melting points and ΔHc for PAG gels are observed. At a gelatin/PAG ratio of 4, the presence of PAG reduces the ΔHc for the gelatin gel by inhibiting the formation of as large or as ordered crystallite crosslinks. To reconcile the problem of aggregation preceding gelation one can assume that M̄w of an aggregate is a linear function of C2. If this is done, the same relationship which normally relates C with Tm is obtained. The equilibrium swelling of PAG films in water at 25°C is markedly molecular weight‐de‐pendent and can vary from below 5 to about 40 wt‐% polymer at equilibrium. It has been found that long‐term dark storage of dry samples of PAG under ambient temperature conditions results in pronounced decreases in the intrinsic viscosities of their aqueous solutions. It is speculated that this results from weak links, perhaps peroxy, in the polymer backbone. The possible relationship of this phenomenon to the slow stage of the viscosity deterioration of aqueous polyacrylamide solutions is pointed out. The higher viscosity of low DP PAG in 2M NaCNS compared to H2O and the larger percentage increse of [η] with increasing temperature in the latter, verify the greater solvent power of 2M aqueous thiocyanate for PAG. At a concentration level of 3%, aqueous PAG solutions are almost Newtonian whereas at higher concentrations (5%), the viscosity decreases appreciably with increasing rates of shear. The copolymerization of AG with isopropylacrylamide has been studied and the somewhat unusual results discussed. Copolymers containing an AG mole fraction greater than 0.40 do not exhibit a cloud point up to 100°C. If the isopropylacrylamide mole fraction approaches 0.60, the solutions do not gel down to 0°C. This ability to prepare copolymers over a narrow composition range that neither gel or undergo phase separation in the temperature range 0–100°C is probably related to the random distribution of monomer units in the copolymer backbone.
Radiation‐induced polymerization of 3,3,4,4,5,5,5‐heptafluoropentene‐1 at high pressure
Authors: Brown Daniel W. , Lowry Robert E. , Wall Leo A.
Published: April 2003

A study was made of the radiation‐induced polymerization under pressure of 3,3,4,4,5,5,5‐heptafluoropentene‐1. Polymerization rates increase with pressure (activation volume equals − 11 cc/mole) and temperature (activation enthalpy equals 6.5 kcal/mole) in liquid phase. At 13800 atm and 25°C, freezing occurs; the polymerization rate in the solid is very small. In liquid phase polymerization can continue for many hours after the irradiation is terminated. An active species is formed by radiation which initiates polymerization in the dark period.
Quaternary ammonium polymers from 1,4‐diaza[2.2.2]bicyclooctane
Authors: Salamone J. C. , Snider B.
Published: April 2003

Menschutkin reactions of 1,4‐diaza[2.2.2]bicyclooctane with various α,α‐dibromoalkanes and α,α′‐dibromoxylenes have been studied in two solvent systems and at different temperatures. It was found that quaternary ammonium polymers could easily be prepared from this rigid, bicyclic, ditertiary amine.
Catalysis of olefin isomerizations by boron trifluoride
Authors: Roberts J. M. , Katovic Z. , Eastham A. M.
Published: April 2003

The kinetics of isomerization of butenes by boron trifluoride with acetic acid or methanol as cocatalysts have been re‐examined. The results, over a wide concentration range, and at temperatures from −20 to +20°C, are consistent with previous data, but it is shown that the previously suggested mechanism cannot apply. By using deuterated acetic acid as cocatalyst it has been found that isomerization exactly parallels protonation, which is consistent with a mechanism involving a classical carbonium ion.
Mechanical properties of radiation‐induced graft copolymers of styrene to polyethylene
Authors: Machi Sueo , Silverman Joseph
Published: April 2003

Measurements were made of the tensile properties polyethylene‐styrene grafts prepared by irradiating polyethylene films in liquid styrene. The films contained true graft and occluded styrene homopolymer. It was shown that yield strength, tensile strength, and initial modulus of elasticity increase while elongation decreases with increasing polystyrene content. The tensile strength and elongation were reduced when the grafted film was soaked in benzene more than 15 hr. The film prepared by a post‐irradiation graft gave higher tensile strength and elongation than those of grafts formed by simultaneous irradiation of the film and the monomer. These results indicate that radiation‐induced grafting makes the system of polyethylene and polystyrene compatible and potentially useful, provided the samples are not subjected to drastic solvent extraction procedures for the removal of homopolymer.
Copolymerization of 2‐sulfoethyl methacrylate
Authors: Kangas Donald A. , Pelletier Ronald R.
Published: April 2003

Copolymers of 2‐sulfoethyl methacrylate, (SEM) were prepared with ethyl methacrylate, ethyl acrylate, vinylidene chloride, and styrene in 1,2‐dimethoxyethane solution with N,N′‐azobisisobutyronitrile as initiator. The monomer reactivity ratios with SEM (M1) were: vinylidene chloride, r1 = 3.6 ± 0.5, r2 = 0.22 ± 0.03; ethyl acrylate, r1 = 3.2 ± 0.6, r2 = 0.30 ± 0.05; ethyl methacrylate, r1 = 2.0 ± 0.4, r2 = 1.0 ± 0.1; styrene, r1 = 0.6 ± 0.2, r2 = 0.37 ± 0.03. The values of the copolymerization parameters calculated from the monomer reactivity ratios were e = +0.6 and Q = 1.4. Comparison of the monomer reactivities indicates that SEM is similar to ethyl methacrylate with regard to copolymerization reactivity in 1,2‐dimethoxyethane solution. The sodium salt of 2‐sulfoethyl methacrylate, SEM⊖Na⊕, was copolymerized with 2‐hydroxyethyl methacrylate (M2) in water solution. Reactivity ratios of r1 = 0.7 ± 0.1 and r2 = 1.6 ± 0.1 were obtained, indicating a lower reactivity of SEM⊖Na⊕ in water as compared to SEM in 1,2‐dimethoxyethane. This decreased reactivity was attributed to greater ionic repulsion between reacting species in the aqueous medium.
Studies in ring‐opening polymerization. I. 5,5‐diethyl‐1,3,2‐dioxathiolan‐4‐one‐2‐oxide
Authors: Blackbourn G. P. , Tighe B. J.
Published: April 2003

The polymerization of 5,5‐diethyl‐1,3,2‐dioxathiolan‐4‐one‐2‐oxide has been examined in various solvents at 60–100°C. Kinetic studies have shown that steric hindrance by the C5 ethyl substituents prevents the occurrence of a bimolecular propagation reaction involving direct attack by a terminal hydroxyl group on the ring. In dry, nonhydroxylic solvents, the first‐order rate‐determining step in the sequence of reactions leading to polymer formation is a primary ring scission reaction in which a reactive intermediate is formed and sulfur dioxide eliminated. This intermediate, which is formally depicted as an α‐lactone, then takes part in a very rapid chain‐propagation process, the individual steps of which govern the molecular weight distribution of the polymer. The values of the activation energy (25–30 kcal/mole) and frequency factor (1011−1013 sec−1) for this polymerization reaction are, therefore, those associated with monomer decomposition and not the chain growth process. The molecular weight of the resultant polymer, poly‐(3‐pentylidene carboxylate) is controlled by adventitious traces of water which produce one carboxyl and one hydroxyl group per chain. Polymers having M̄n ∼ 20,000 are readily obtained; these are materials of moderately high melting point (Tm ≃ 200°C) which crystallize from the melt into a banded spherulitic structure.
Preparation of long‐chain paraffins from nitric acid degradation products of polyethylene; some consequences for polymer crystal structure studies
Authors: Keller A. , Udagawa Y.
Published: April 2003

It is demonstrated that dicarboxylic acids of uniform lengths, obtained by degrading chain‐folded polyethylene single crystals, can be converted to paraffins via the intermediate diiodide by means of the procedure of Barton et al. Thus we are now in the position of obtaining uniform paraffins of chain lengths longer than hitherto available for the study of the crystallization of oligomeric chains. Measurements of melting points and heats of fusion revealed major differences between the paraffins and the corresponding parent dicarboxylic acids. It follows that such measurements on the unmodified products of the nitric acid degradation cannot be used directly for the assessment of the chain traverse length and the degree of crystallinity. It was found further, that the intermediate diiodide is a sufficiently close approximation to the paraffin for the purposes just quoted.
Conformational characteristics of polymorphous optically active macromolecules: A statistical zigzag model
Authors: Birshtein T. M. , Zubkov V. A. , Volkenstein M. V.
Published: April 2003

The conformational properties of optically active macromolecules are considered. A statistical zigzag model is used for the calculation of averaged physical properties. The macromolecule is considered to consist of segments of two different types with a statistical distribution of lengths. The expressions for the mean square of the end‐to‐end vector h2 and the dipole moment μ2 and also of the mean optical anisotropy ΔA and the anisotropy of the optical rotation tensor ΔG were obtained in the cases of freely jointed and freely rotating segments. The equations obtained were applied to the problem of the helix–coil transition. In the case of poly‐α‐olefins the values of h2, μ2, and ΔA, are larger than corresponding values for typical optically inactive macromolecules. The anisotropies ΔA and ΔG of two poly‐α‐olefins of similar structures were calculated. The polarizability theory of optical activity was used for the calculations of ΔG. The values obtained for ΔA are similar, but the values of ΔG differ markedly. The possibility of obtaining valuable information about the structure of optically active macromolecules in solution by a study of anisotropy of the optical rotation tensor is considered.
Nuclear relaxation in atactic polystyrenes: T1 and T1ρ measurements
Authors: Connor T. M.
Published: April 2003

Measurements have been made on a series of linear atactic polystyrenes whose molecular weights range from 900 to 1.8 × 106, where Mw/Mn ≪ 1.2. Spin lattice relaxation times have been measured in the laboratory frame (T1) and in the rotating frame (T1ρ) in the temperature range 90–500°K. Two major relaxation minima were observed in both sets of measurements. The high temperature process corresponds to the glass transition (α process), the position of the minimum depending on the chain length. The low temperature process appears to originate from the n‐butyl endgroups in the polymer, its position being independent of chain length while its intensity is inversely proportional to molecular weight. No other minima were observed, in contrast to some other observations made by broadline and pulsed NMR techniques. Relaxation was exponential in all cases except in the region of the high temperature T1ρ minimum and above. This nonexponential behavior is possibly connected with the transition at T > Tg observed by a number of other techniques and which is thought to correspond to a transition between two types of liquid state. A correlation frequency diagram has been drawn for all the processes observed in polystyrene by other techniques, (α, β, αβ, γ, and δ) which shows that the T1 and T1ρ minimum positions correlate well with the α process and that there is a possible contribution to the relaxation due to the γ process on the low temperature side of the α process. At these measurement frequencies the α and β processes are merged into an αβ process. There is no evidence for a contribution from the mechanical δ process. The effect of the endgroups is observed to very high molecular weights (4.98 × 105), and it seems that a three‐dimensional diffusion model would be more adequate than the one‐dimensional model used to interpret similar behavior of paraffins and polyethylenes. Measurements of T1 in the low‐temperature region would constitute a method for a rough measurement of the molecular weight of these polymers.
Precipitation chromatography theory
Authors: Smith W. V.
Published: April 2003

A discussion is given of the behavior of a mathematical model chosen to approximate conditions during precipitation chromatographic fractionation of polymer (Baker Williams fractionation). With only one molecular weight species of polymer a complete solution of the mathematical model was obtained. With more than one species it was necessary to use a computer solution. Curves showing the movement of polymer containing one and two species of polymer are given for a variety of conditions of operation. It was found that the degree of fractionation of polymer approaches a limiting value with increasing length of column. Under some conditions the degree of fractionation may go through a maximum with length of column. The equilibrating distance (distance of travel of the liquid phase required to establish equilibrium of polymer between the liquid and the bed) was found to be very important in determining the fractionation.
Intrinsic viscosity and axial extension ratio of random‐coiling macromolecules in a hydrodynamic shear field
Authors: Cottrell F. R. , Merrill E. W. , Smith K. A.
Published: April 2003

The shear dependence of the intrinsic viscosity and the conformation of high molecular weight polyisobutylene in dilute solutions of decahydronaphthalene under shear were determined simultaneously. Experimental variables investigated were the shear rate (0 to 2 × 103 sec−1), the molecular weight (1.0 × 107 to 1.7 × 107) and the polymer concentration (1.8 × 10−4 to 8.4 × 10−4 g/cc). Correlations allowing concentration and shear rate normalization for any one sample are described. Conformational extention ratios along the orientation direction of the deformed molecule to 1.42 and intrinsic viscosity ratios (sheared to zero shear) to 0.5 were observed.
Effect of diluents on the melt viscosity of branched polybutadienes
Authors: Kraus Gerard , Gruver J. T.
Published: April 2003

The enchanced low‐shear melt viscosity of branched polybutadienes is shown to be sensitive to dilution with low molecular compounds. The viscosity of branched polymers falls more rapidly with dilution than that of linear polymers, i.e., branched polymers show increased response to plasticization. At least one instance is demonstrated in which the viscosity ratio ηbr/ηlin reverses from a value greater than unity to less than one in passing from dry polymer to rubber extended with relatively large quantities of oil.
Microstructure and rheological properties of polybutadienes
Authors: Vinogradov G. V. , Malkin A. Ya. , Kulichikhin V. G.
Published: April 2003

The viscosities, rubbery deformations, densities, and their dependence on temperature have been measured for several series of polybutadienes with molecular weights ranging from 5,000 to 400,000 and differing in proportions of cis and trans structures (cis content from 40 to 95%). On the basis of the viscosity measurements the critical molecular weight Mc has been determined, corresponding to a sharp change in the nature of the viscosity versus molecular weight dependence. Rubbery deformations are displayed pronouncedly in specimens with M > Mc and are closely related to the appearance of non‐Newtonian flow. The value of Mc depends on the relative content of cis and trans forms. When M > Mc, the initial viscosity is a parameter sensitive to the microstructure of polybutadienes, so that with at a single molecular weight, depending on the ratio of cis and trans units, the viscosity may vary over a more than tenfold range. The glass transition temperature and activation energy of viscous flow rise regularly with increasing trans content in the polymer chain, these parameters becoming independent of the molecular weight for specimens with M > Mc within a series of polybutadienes of equal microtacticity. Thermomechanical investigations of polybutadienes also made it possible to define more accurately the boundaries of the crystallization region and the dependence of the melting point on the microtacticity. The results obtained are discussed on the basis of modern ideas of polymer structure.
Properties and structures of films drawn from polyethylene single‐crystal mats
Authors: Maeda Masahiko , Miyasaka Keizo , Ishikawa Kinzo
Published: April 2003

The properties and structures of polyethylene films drawn from mats of single crystals were investigated in comparison with films drawn from bulk polymer. The most important result obtained is that the structural reorganization stimulated by mechanical stress and annealing occurs with much greater difficulty in the mat‐drawn film. The chief mechanical characteristics of the film are a very low extensibility and a very high modulus. Structural characteristics, such as the double‐orientation of the crystalline region and the morphology of the crystals, do suffer no substantial changes during annealing at high temperatures. This stability of the structure can be related to the characteristic fine structure of the mat‐drawn film in which there are a much larger number of tie chains, connecting neighboring crystals, than in the bulk‐drawn specimen. Relaxation of the amorphous region and a notable increase in long spacing take place in the mat‐drawn sample as in ordinary bulk‐drawn samples. However, the morphological changes of the crystals accompanied by the folding back of chains seem to take place with great difficulty during annealing even in the vicinity of the melting point.
Relation between the network structure and dynamic mechanical properties of a typical amine‐cured epoxy polymer
Authors: Murayama T. , Bell J. P.
Published: April 2003

The dynamic mechanical properties of a series of epoxy polymers of known network structure have been investigated. It was shown that the distance between crosslinks could be predicted from either the shift in the glass transition temperature Tg or by use of the dynamic modulus above Tg. The front factor in the equation of state for rubber elasticity was near unity for stoichiometric equivalence of epoxy and amine and increased slowly with excess of either component.
Effect of birefringence on low‐angle light‐scattering patterns from oriented polymer films. II
Authors: Chu W. , Stein R. S.
Published: April 2003

A quantitative theoretical calculation is made of the effect of birefringence of the surrounding medium on the light‐scattering pattern from a two‐dimensional anisotropic spherulite. The calculated modification of the light‐scattering pattern is in accord with the prediction previously made on the basis of qualitative considerations and model experiments.
Thermodynamic properties of some monomeric compounds in the standard ideal gas state
Authors: Joshi R. M.
Published: April 2003

Thermodynamic functions of ten monomeric compounds have been calculated for three temperatures by the statistical method using molecular structural data and vibrational assignments. The ideal gas state entropies at 298.15°K are: maleic anhydride, 71.9; β‐propiolactone, 69.1; vinylene carbonate, 70.1; cyclopentadiene, 65.3; diketene, 72.3; cyclopropene, 58.7, vinyl fluoride, 60.4; ethyleneimine, 62.8; butatriene, 71.7; and carbon suboxide, 66.0 cal./deg‐mole. The standard free energies and equilibrium constants of formation are also derived by using mostly the published data on the heats of formation of these monomers.
Nature of DC conductivity in polyamides
Authors: Baird M. E.
Published: April 2003

The dc conductivity of poly(sebacyl piperazine), a polyamide prepared from the secondary diamine piperazine, in which no NH groups are present and no hydrogen bonding can occur, has been examined and compared with that of a normal 610 polyamide. The results obtained point clearly to the conduction in the 610 polyamide being electronic below about 100°C but probably involving protons as well as electrons above this temperature. This is largely consistent with the findings of earlier work and clarifies the nature of conduction below about 80°C as being almost certainly electronic where previously it was in doubt. A definite and sometimes marked hysteresis in the conductivity was observed with regard to raising and lowering the temperature of the polyamides. This is explained in terms of the space‐charge polarization developed in the materials at higher temperatures and which becomes clearly evident in their dielectric behavior. This shows the importance of discharging specimens at a sufficiently high temperature before making conductivity measurements. The polarization is a bulk and not an electrode effect, and it will probably depend to a marked extent on the morphology of the polyamides.
Effect of molecular weight on the growth rates of low melting spherulites of trans‐1,4‐polyisoprene
Authors: Lovering Edward G.
Published: April 2003

Growth rates of G of low‐melting spherulites in fractions of trans‐1,4‐polyisoprene have been measured. The data were analyzed by use of an equation, ln G = ln G0 − ΔF*/RTc, valid at temperatures close to the equilibrium melting point. Plots of ln G against a function of the critical free energy of nucleation ΔF* result in a family of straight lines having a common intercept, ln G0, which is independent of molecular weight. The slope of these lines is a measure of the interfacial free energy of the crystallites and increases with the molecular weight, reflecting increasing irregularity in the structure of the semicrystalline mass. Comparison of growth rates of low‐melting and high‐melting trans‐1,4‐polyisoprene indicates that G0 does not, to a first approximation, depend on the nature of the crystals growing from the melt. The temperature at which spherulites of the two crystalline forms grow at equal rates has been calculated.