bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymers containing the 2,5‐diphenylthiazolo[5,4‐d]thiazole moiety
Authors: Fox Charles J. 
Published: April 2003

AbstractPolyearbonates, alternating copolycarbonates, and polyesters were prepared from bisphenols containing the 2,5‐diphenylthiazolo [5,4‐d]thiazole moiety. The bisphenols used were 2,5‐bis(4‐hydroxyphenyl)thiazolo [5,4‐d] thiazole, 2,5‐bis‐(3‐hydroxyphenyl)‐thiazolo [5,4‐d] thiazole, and 2,5‐bis(4‐hydroxy‐3‐methoxyphenyl) thiazolo [5,4‐d] thiazole. The relative degrees of crystallinity for these polymers were determined and are discussed in relation to some of the physical properties. The degree of crystallinity observed for the polycarbonates varied from low to high, depending on the position of substitution in the phenyl rings. The alternating copolycarbonates with neopentyl glycol were all of a low degree of crystallinity and increased solubility. The polyadipates and polysebacates prepared were of a relatively high degree of crystallinity in spite of the flexibility permitted by the aliphatic diacid linkage. The solubilities of these polyesters were appreciable, even though the crystallinity was high.
Calibration of light‐scattering instruments. II. The volume correction
Authors: Kerker Milton , Kratohvil Josip P. , Matijević Egon 
Published: April 2003

AbstractThe physical nature of the volume correction, Cv used in the determination of turbidity by light‐scattering measurements at 90° is reviewed, and errors and limitations in earlier formulations are pointed out. Formulations are given for three cases; viz., (I) when the height of the incident beam is within the central scattering volume, Vc; (II) when the field of view of the detector is completely within the beam: (III) the intermediate case when the vertical edges of the beam are in the excess volume, Ve. The volume correction is calculated for several geometries.
Detection of ethylene homopolymer in ethylene–propylene block copolymers
Authors: Lomonte John N. , Tirpak George A. 
Published: April 2003

AbstractA method has been developed for the determination of per cent ethylene incorporation in ethylene–propylene block copolymers by infrared spectroscopy. Standardization is done from mixtures of the homopolymers. Both standards and samples are scanned at 180°C. in a spring‐loaded demountable cell. The standardization was confirmed by the analysis of copolymers of known ethylene content prepared with C14‐labeled ethylene. By comparison of the infrared results from the analyses performed at 180°C. and also at room temperature, the presence of ethylene homopolymer can be detected. An equation has been derived for the quantitative estimation of per cent ethylene present as copolymer blocks.
Amylose “V” complexes: Low molecular weight primary alcohols
Authors: Valletta Robert M. , Germino Felix J. , Lang Robert E. , Moshy Raymond J. 
Published: April 2003

AbstractThe methanol‐, ethanol‐, and 1‐propanol‐amylose “V” complexes have been prepared and their unit cell dimensions calculated from their x‐ray powder patterns. The small unit cell (with 13.0 A. helix diameter), previously reported to occur only after the complete removal of water, has been observed for the wet methanol and ethanol complexes. In fact, a methanol complex containing as much as one mole of water per glucose residue had the small unit cell. Residual water and residual complexing agent analyses have shown that complexes dried to constant weight under stringent conditions retain as much as one mole of water and one‐quarter mole of complexing agent per helix turn. It has been concluded that the specific organic complexing agent plays an important role in dictating the unit cell size.
Poly(1,3,4‐oxadiazole) fibers: New fibers with superior high temperature resistance
Authors: Frazer A. H. , Wallenberger F. T. 
Published: April 2003

AbstractA polyoxidiazole fiber, alt. poly[1,3‐/1,4‐phenylene‐2,5‐(1,3,4‐oxadiazole)], with excellent thermal stability was prepared from poly(isophthalic‐terephthalic hydrazide) fiber by thermal cyclodehydration. Conversion of this polyhydrazide fiber proceeded at 280°C. in a muffle furance under positive nitrogen pressure and was completed in 48–72 hr., as evidenced by elemental analyses. The resulting polyoxadiazole fiber had the following typical fiber properties: T/E/Mi/den. = 2.6/3.1/124/3.1. It was thermally stable when exposed for prolonged periods of time at temperatures of 400°C. During heat treatment between 300 and 400°C. the initial polyoxadiazole fiber undergoes a structural change and final properties were: T/E/Mi/den. ∼ 1.5/1.5/90/3.0. The polyoxadiazole structure was found to degrade severely at 450°C.
1,5‐Hexadiene polymers. I. Structure and properties of poly‐1,5‐hexadiene
Authors: Makowski Henry S. , Shim Benjamin K. C. , Wilchinsky Zigmond W. 
Published: April 2003

Abstract1,5‐Hexadiene has been polymerized with a number of modified alkyl metal coordination catalysts to crystalline polymers having an unusual combination of properties. These polymers are crystalline, have high tensile strengths, high melting points, high densities, and yet are very flexible. Poly‐1,5‐hexadiene has a chain identity period of 4.80 A., and is best difined as consisting primarily of 1‐methylene‐3‐cyclopentyl units in which the substituents are cis and the cyclopentane ring is in an envelope conformation. Since not all the monomer units incorporated into the chain are cyclized, the polymer more closely resembles an interpolymer than a homopolymer.
Stereoregulated polydideuteroethylene. II. Infrared spectra and normal vibration analysis
Authors: Tasumi Mitsuo , Shimanouchi Takehiko , Tanaka Hiroshi , Ikeda Sakuji 
Published: April 2003

AbstractPoly‐(trans‐CHDCHD) and poly‐(cis‐CHDCHD) have been obtained with [Al(Et)3 + TiCl4] and with [Al(i‐Bu)3 + TiCl4]. Poly‐(trans‐CHDCHD) and poly‐(cis‐CHDCHD) obtained with [Al(Et)3 + TiCl4] give mutually different infrared spectra. The characteristic absorption bands of the former are found at 1335, 1288, and 594, and 586 cm.−1, and those of the latter at 1306, 597, and 590 cm.−1. In order to interpret these spectra, the normal vibration frequencies of the model structures, namely, erythro‐diisotactic and threo‐diisotactic structures, have been calculated. From the comparison of the observed and calculated frequencies, it has been concluded that poly‐(trans‐CHDCHD) obtained with [Al(Et)3 + TiCl4] consists mainly of the threo‐diisotactic and disyndiotactic portions and poly‐(cis‐CHDCHD) obtained with the same catalyst consists mainly of the erythro‐diisotactic and disyndiotactic portions. The relation between the type of double bond opening and the structure of the resultant polymer has been discussed, and it has been concluded that the cis‐opening of the double bond occurs in the polymerization reaction with [Al(Et)3 + TiCl4]. The spectra of poly‐(trans‐CHDCHD) and poly‐(cis‐CHDCHD) obtained with [Al(i‐Bu)3 + TiCl4] are not so different from each other, but they are different from the spectra of the polymers obtained with [Al(Et)3 + TiCl4]. The polymers obtained with [Al(i‐Bu)3 + TiCl4] show characteristic bands at 2919, 2850, 2176, 2095, 1453, 660, 623, 600, 593, 581, 566, and 545 cm.−1. These bands give evidence of the presence of isolated CH2 and CD2 groups. This fact indicates that the hydrogen–deuterium exchange reaction in monomers as well as the polymerization is promoted by [Al(i‐Bu)3 + TiCl4].
The distinction between terminal and penultimate copolymerization models
Authors: Berger M. , Kuntz Irving 
Published: April 2003

AbstractAn examination of the usual terminal and penultimate mechanisms of copolymerization shows that, for a great many comonomer pairs, copolymer composition data are not sufficient to choose one model over the other. The reactivity ratios based on one copolymerization model can be derived from the reactivity ratios of the other model. Predicted copolymer composition, based on both models, will agree with the observed experimental data within the precision of the usual methods used for copolymer analysis. Hypothetical cases and examples from the literature all show this behavior. The literature comonomer systems were α‐methylstyrene–acrylonitrile, and styrene with maleic anhydride, citraconic anhydride, and acrylonitrile. Polymer structure, however, predicted by the two mechanisms do differ appreciably in detail. In particular, predictions of the sequential arrangements of the monomers in the copolymers produced are different for the terminal and penultimate mechanisms. It would seem that the development of experimental procedures for determining the sequential arrangement of the comonomers will be necessary before one can easily and definitely distinguish between terminal and penultimate copolymerization models for a particular system.
Permanganate–oxalic acid as a redox initiator of acrylonitrile polymerization in aqueous media. Part III. Kinetics and DP
Authors: Konar Ranjit S. , Palit Santi R. 
Published: April 2003

AbstractThe kinetics of the aqueous polymerization of acrylonitrile initiated by the permanganate–oxalic acid redox pair have been studied gravimetrically at 32 ± 0.2°C. The rate of polymerization is independent of oxalic acid concentration over a small range. The catalyst exponent varies continuously with the catalyst concentration, being 0.9 at low catalyst concentration and 0.27 at high catalyst concentration at a monomer concentration of 0.30M. The monomer exponent is nearly unity in the concentration range 0.30M and above. The molecular weight of the polymer is independent of oxalic acid concentration in the range where the rate of polymerization is independent of the oxalic acid concentration but decreases at higher concentration of oxalic acid with increasing concentration of catalyst and temperature. The overall activation energy was found to be 8.6 kcal./mole. Addition of salts such as Na2SO4 depresses the rate of polymerization, but the addition of MnSO4 at low concentrations increases the rate, whereas at higher concentration the initial rate falls. It has been suggested that hydrated Mn3+ ions cause oxidative chain termination of polyacrylonitrile radicals. Complexing agents, such as fluoride ions, ethylene‐diaminetetraacetic acid, etc., decrease the rate of polymerization, whereas addition of detergents enhances it.
Rubber elasticity of preswollen polymer networks: Lightly crosslinked vinyl‐divinyl systems
Authors: Shen M. C. , Tobolsky A. V. 
Published: April 2003

AbstractThe rubber elasticity of lightly crosslinked, preswollen polymers is studied by both stress‐relaxation and torsion measurements. The equation of state of rubber elasticity is applied to evaluate their front factors. It is found that both elastic moduli and front factors decrease linearly as the diluent content increases. This relationship is independent of the type of crosslink and the diluent used. Properties of deswollen polymer networks are also investigated. No significant change in front factor is apparent before and after deswelling. All these observations are attributed to the network topology. One factor is that effective chemical crosslinks may be decreased by the formation of intramolecular loops. Also, trapped entanglements become less significant at higher diluent concentrations.
General relationships among monomers in copolymerization
Authors: Ham George E. 
Published: April 2003

AbstractAlthough there is general recognition of the value of the Alfrey‐Price relationship, controversy has not abated concerning the theoretical basis for the equations and the accuracy of the monomer reactivity ratios predicted. A heretofore unrecognized possibility for approaching the problem of general monomer reactivity relationships appears to lie in the consideration of terpolymers. The relationship between monomer and terpolymer compositions is given by the equations

A more general and yet simplified relationship underlying terpolymers which has not been previously recognized is derived. This relationship is shown to hold for a wide range of monomer types and concentrations. The overall probability of initiating a, c, and b sequences immediately preceded by b, a, and c, respectively, and of undefined terminating units is equal to the probability of terminating a, c, and b sequences with b, a, and c units, respectively, but of undefined initiating units. This relationship of product probabilities is as follows:

and is shown to hold for numerous terpolymer and related copolymer systems. It follows that

Methods are presented for predicting the behavior of monomers A and C in copolymerization when the behaviors of A‐B and B‐C are known. Furthermore, it is shown that the value of eq. (3) is frequently in the range of 0.02–0.06. This result is probably related to the fact that terpolymerization of monomers of equal reactivity in equimolar concentrations will yield product probabilities equal to 0.037. Variations in individual probabilities require compensating changes in the other related probabilities. Application of this relationship allows the calculation of r13 and r31 where r23, r32, r12, and r21 are known.
Tracer diffusion, electrical conductivity, and viscosity of aqueous solutions of polystyrenesulfonates
Authors: Prini R. Fernandez , Lagos A. E. 
Published: April 2003

AbstractThe variation of counterion mobilities in aqueous solutions of linear sodium polystyrenesulfonic acid over wide range of concentrations (10−2–0.7N) was studied. The viscosities of these solutions were measured in order to calculate the reduced viscosities at different concentrations. From the data obtained it was possible to conclude that in the range of concentrations 0.08–0.45N, an increase in D was observed. The enhancement of mobilities was attributed to an increase in the degree of apparent dissociation due to purely electrostatic interactions among neighboring chains. As concentration increased and chains approached each other, the above interactions should be accompained by short‐range interactions which would produce entanglements among neighbouring chains. This may be responsible for the appearance of a maximum in mobilities as the concentration increased. Evidence was found for a decrease of DNa in solution when N > 0.45. The appearance of entanglements must produce an increase in the reduced viscosity which was observed. Tracer diffusion coefficients and reduced viscosities of the counterions Cs+, Ag+, and Ca++ in the corresponding salts of polystyrenesulfonic acid all at the same normalities were also measured. It was observed that the counterions Cs+ had a slightly larger degree of association than Na+. The behavior of Ca++ could be explained by the very strong association due to its double charge and for silver as partially due to the presence of complexes. For both counterions the reduced viscosity was much smaller than for the sodium salt.
Stereoregularity of polymethacrylonitrile
Authors: Sobue H. , Uryu T. , Matsuzaki K. , Tabata Y. 
Published: April 2003

AbstractThe stereoregularity of polymethacrylonitrile was determined by examining the infrared and NMR spectra of poly(methyl methacrylate) derived from polymethacrylonitrile. Methacrylonitrile was polymerized by n‐butyllithium, azobisisobutyronitrile, benzoyl peroxide, and γ‐ray irradiation. The J values of the derived poly(methyl methacrylate) are in a range of 56–59, indicating a stereoblock structure. The NMR spectra of the derived poly(methyl methacrylate) showed that the polymers are composed mainly of isotactic‐heterotactic structures.
Optically active polymers: Cyclopolymerization of the divinylacetal of (R) (+)‐3,7‐dimethyloctanal
Authors: Abe Akihiro , Goodman Murray 
Published: April 2003

AbstractThe divinylacetal of (R)(+)‐3,7‐dimethyloctanal was polymerized by radical and cationic initiators. Radical initiation gave only viscous liquid polymers, while cationic systems gave solid products. Optical rotatory dispersions of these polymers fit simple Drude plots. The polymer prepared by boron trifluoride etherate exhibits negative optical rotations, while both the polymer obtained by azobisisobutyronitrile and the model compound show positive rotations. From these observations, it is suggested that the polymers might differ from each other in stereoregularity.
Thermal decomposition of model compounds of polyvinyl chloride. I. Gaseous thermal decomposition of model compounds having secondary and tertiary chlorine
Authors: Asahina Mitsuo , Onozuka Mitsuo 
Published: April 2003

AbstractThe thermal stabilities of branched model compounds of poly(vinyl chloride) are studied in the gaseous state. The compounds containing tertiary chlorine, i.e., 2‐methyl‐2‐chloropropane and 3‐ethyl‐3‐chloropentane, are compared with those containing a secondary chlorine, i.e., 2‐chloropropane and 2,4‐dichloropentane. The results of gaseous thermal decomposition show that the tendency of C‐Cl cleavage depends on the electronegativity of carbon bonded chloride. The decomposition temperature TD can be used for the evaluation of the thermal stabilities of various model compounds.
Extractability of homopolymer of methyl methacrylate from, its graft copolymers with starch
Authors: Brockway C. E. 
Published: April 2003

AbstractA study has been made of factors which influence the efficiency of extraction of homopolymer of methyl methyacrylate from its graft copolymers with granular corn starch. The moisture content plays a significant role in the extractability of homopolymer; about 25% moisture seems optimum for many samples, with extractability of homopolymer falling sharply at lower moisture levels. In a series of solvents, the efficiency of removal of ungrafted homopolymer varies in a manner roughly paralleling the relative solvating efficiencies of the various solvents for the homopolymers, as indicated by the reported values of appropriate parameters for polymer solutions. For the starch/PMMA system, chloroform and dichloroethane are about equally efficient, and either is superior to benzene, which in turn is better than toluene, methyl ethyl ketone, or acetone. Soxhlet extraction, though commonly used for graft copolymers, is not as effective for the granular starch/PMMA system as is tumbling the heated mixture of solvent and polymer in a closed container. This is probably due to inefficient percolation of the solvent through the swollen syrupy mass of graft copolymer in the Soxhlet thimble.
Dilute solution properties of polyamides in formic acid. Part I. Repression of polyelectrolyte effects by means of excess counterions
Authors: Saunders P. R. 
Published: April 2003

AbstractThe polyelectrolyte effects of nylon 66 have been studied as a function of the composition of the solvent system formic acid–water–sodium formate by means of viscometry and light scattering. The intrinsic viscosity and light‐scattering second virial coefficient of nylon 66 in 90% formic acid decrease rapidly with addition of sodium formate. The apparent weight‐average molecular weight increases initially and then becomes constant at salt concentrations greater than 0.025 mole/l. The changes in intrinsic viscosity and second virial coefficient are relatively small for changes in salt concentration above 0.2 mole/l. In the presence of 0.5 mole/l. of sodium formate, the polyelectrolyte effects are completely repressed and the polymer solvent interaction can be varied independently by adjustment of the quantity of water in the solvent. In these circumstances, there is a linear relation between intrinsic viscosity and second virial coefficient. Extrapolation yields a value of the intrinsic viscosity in an ideal solvent and an estimate of the unperturbed dimensions of nylon 66, (r02/M)1/2 = 9 × 10−9 cm. mole1/2 · g.−1/2. These results lead to a value for Flory's universal constant for randomly coiled chain molecules, Φ = 2.5 × 1021.
Interaction of polymethacrylic acid and bivalent counterions. II
Authors: Mandel M. , Leyte J. C. 
Published: April 2003

AbstractThe Cu(II) chelate of polymethacrylic acid was investigated. Viscometric, electrophoretic, and spectrophotometric evidence is shown to confirm the potentiometric results reported previously which indicated the binding of two carboxylic groups by one Cu(II) ion.
Radiation chemistry of iodine‐octamethylcyclotetrasiloxane solutions
Authors: Wolf Clarence J. , Stewart A. C. 
Published: April 2003

AbstractPost‐irradiation polymerization of γ‐ray‐irradiated liquid octamethylcyclotetrasiloxane containing a small amount of iodine was observed. The effect occurs at room temperature without an additional stimulus, and we conclude that it results from catalysis by HI3, i.e., a complex of HI + I2. Hydrogen triiodide is produced when iodine‐octamethylcyclotetrasiloxane solutions are irradiated with γ‐rays from Co60. HI3 is a good rearrangement catalyst for siloxane bonds. The dose is critical; short irradiations do not produce enough HI, while longer irradiations consume most of the I2. The triiodide complex dissociates at temperatures equal to or greater than 60°C.; thus, the polymerization stops as the temperature is raised, but contrary to usual post‐irradiation polymerization processes, resumes when the sample cools. Pure irradiated octamethylcyclotetrasiloxane polymerizes upon the addition of iodine. We assume that the irradiation produces silicon‐hydrogen bonds which react with iodine yielding the catalyst HI3. In all systems the HI3 was identified spectrophotometrically. However, its role in the polymerization was established directly when it was determined that an unirradiated iodine‐octamethylcyclotetrasiloxane solution polymerized upon the addition of HI.
Kinetics of ring‐scission copolymerization
Authors: Dermer O. C. , Ames W. A. 
Published: April 2003

Abstractβ‐Propiolactone and propylene sulfide with triethylamine catalyst produced only polypropiolactone, but the lactone and DL‐valine N‐carboxy anhydride gave a copolymer of low molecular weight. Neither the classical copolymer equation nor the relationship pointed out by O'Driscoll applies to this copolymerization, but the valine N‐carboxy anhydride was obviously the much more reactive. The rate of acid‐catalyzed copolymerization of N‐(2‐hydroxyethyl)aziridine and N‐(2‐hydroxy‐n‐propyl)aziridine was essentially equal to the sum of the rates of the homopolymerizations of the two monomers, as was found by Shalitin and Katchalski for several pairs of N‐carboxy‐α‐amino acid anhydrides. A mixture of propylene oxide and epichlorohydrin did not exhibit this ideal behavior and was polymerized very little more rapidly than propylene oxide alone.
Polymerization of higher aldehydes. VI. Mechanism of aldehyde polymerization
Authors: Vogl O. , Bryant W. M. D. 
Published: April 2003

AbstractOn the basis of results presented in previous papers possible mechanisms of polymerization of higher aldehydes are considered. The influence of solvents, temperature, initiator, and monomer upon the polymerization is discussed with particular emphasis on the stereoregularity of the resulting polymer. It is proposed that more than one monomer unit is involved in the propagation step. Both the stereoselective addition of monomer to the growing chain and the chain transfer reaction are thought to take place in a concerted manner. Chain transfer results in termination with the formation of hydroxyl, ester and probably ether end groups; growing chains which do not undergo transfer remain as “living” ends after the monomer supply is exhausted. Some thermodynamic values for carbonyl polymerizations are estimated.