bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermodynamic properties of solutions of cellulose triacetate
Authors: Moore W. R. , Shuttleworth R.
Published: April 2003

The lowering of vapor pressures of solutions containing 10–50% by weight of cellulose triacetate in chloroform and methylene chloride have been measured at several temperatures. Attempts made to obtain similar data for solutions in s‐tetrachlorethane failed apparently because of decomposition of solvent. Solvent activities, free energies, heats and entropies of dilution are obtained. Both systems become increasingly exothermal as the polymer concentration is increased. In the triacetate‐chloroform system, TΔS̄1 decreases from relatively large values at low concentrations as the concentration is increased resembling comparable secondary cellulose acetate systems with acetone and dioxan as solvents. In the methylene chloride system, TΔS̄1 increases with concentration as in comparable cellulose nitrate‐solvent systems. These results are interpreted in terms of solvation and chain stiffness. Values of the polymer‐solvent interaction parameter x1 increase with concentration and values of the entropy contribution to x1 are greater than those suggested by lattice theories. Expression of volume fraction of polymer in terms of solvated rather than dry polymer should lead to values of x1 and the entropy contribution which are more in keeping with the predictions of lattice theories.
Maximum relaxation time on polymers in the vicinity of critical molecular weight
Authors: Sobue Hiroshi , Murakami Kenkichi
Published: April 2003

It is a well‐known fact that the relaxation spectra in the rubbery region of linear amorphous polymers show “box‐type” functions which are characterized by three elements, τe τm and E0, the minimum relaxation time, maximum relaxation time, and height of the curve, respectively. The equation (τm − τe)/log (τm/τe) = 2.303 αM/Er(τe) can be derived by a simple treatment described in this paper. Then log τe = −log E0/α(1 −1/10K) + β log M̄w can be obtained from the above equation for the polymers synthesized by us. According to Fujita's results, however, τm is independent of molecular weight and τm becomes τ3 when M̄w conforms to Mc. For such a case the above equation is transformed into log (τm/τe − 1) − log log τm/τm = β log M̄w/Mc. On the other hand, log τm experimentally obtained was plotted against log M̄w for the same polymers and it was found that the results were raher on the straight line indicated by the former equation than on the curve shown by the latter. Also log (τm + 0.234) = —5.87 + 1.65 log M̄w was found to be suitable for the polymers in the vicinity of Mc.
Synthesis of styrene–methyl methacrylate nonrandom copolymers in emulsion systems with cobalt‐60 gamma radiation
Authors: Acres G. J. K. , Dalton F. L.
Published: April 2003

Graft copolymers have been prepared by the irradiation of polymer latices swollen with monomer. The latices used were prepared by radiation polymerization of emulsions to avoid the presence of initiator molecules in the second stage. Latices of polystyrene swollen with methyl methacrylate and polymethyl methacrylate swollen with styrene have been used. Polymerizations were followed dilatometrically and the dependence of polymerization rate on monomer concentration and radiation intensity obtained for both systems studied. Separation of copolymer from homopolymers has been attempted by thermal gradient elution chromatography; the method proved satisfactory when the solvent—nonsolvent system benzene—petroleum ether was used, but failed to give separations when benzene—methanol was used. This failure is thought to be due to cosolution phenomena.
The chemical and physicochemical properties of wheat starch mildly oxidized with alkaline sodium hypochlorite
Authors: Schmorak J. , Lewin M.
Published: April 2003

An attempt has been made to elucidate the nature of the reaction between alkaline hypochlorite and granular wheat starch. With this end in view various analytical determinations were carried out on starch samples oxidized under well‐determined conditions. The reaction was found to be nonspecific, its main results being the formation of functional groups and the scission of glucosidic bounds. The functional groups formed were mainly carboxyls, some carbonyl formation taking place at lower pH values. The consumption of about 0.05 atom of oxygen/AGU resulted in an extensive degradation of both starch components. There are indications to the effect that degradation is random in type. On that assumption, 0.5 to 1 glucosidic bonds in 100 were scinded, each scission being accompanied by the formation of about two carboxyl groups and by an overall consumption of 4–5 oxygen atoms. The reaction apparently took place in the amorphous part of the granule. The amylose‐amylopectin ratio, as well as the granule size remained unchanged. More than one‐quarter of the total oxygen consumed reacted with the dissolved portion of the starch as the result of the oxidation.
Polymerization of alicyclic epoxides with aluminum alkyl catalysts
Authors: Bacskai R.
Published: April 2003

The polymerization of alicyclic epoxides with aluminum alkyls has been investigated. In many cases, fast polymerization rates were observed at −78°C., leading to high molecular weight compounds in good yield. The infrared spectra of the polymers are consistent with the proposed polyether structure. It was found that the molecular weight of the polymers obtained in these reactions is a function of the alicyclic ring size. This was interpreted by considering the variation of molecular strain during the polymer‐forming reaction. The following order of reactivity based on estimated propagation rates has been established for the monomers: cyclohexene oxide > cyclopentene oxide > cycloheptene oxide » cyclooctene oxide. A reaction mechanism is proposed where initiation occurs through coordination of the aluminum alkyl with the epoxide, followed by successive addition of monomers to the electrophilic centers. The absence of phenyl endgroups in a relatively low molecular weight polycyclohexene oxide, prepared with Al(C6H5)3 catalyst, precludes one of the possible alternative mechanisms. The proton magnetic resonance spectra of polycyclohexene oxide, cis‐1,2‐cyclohexanediol, and trans‐1,2‐cyclohexanediol were determined in dilute chloroform solution and suggest a stereoregular poly‐trans‐ether structure for the polymers.
Polymers containing the 2,5‐diphenylthiazolo[5,4‐d]thiazole moiety
Authors: Fox Charles J.
Published: April 2003

Polyearbonates, 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

The 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

A 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

The 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

A 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

1,5‐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

Poly‐(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

An 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

The 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

The 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

Although 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

The 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

The 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

The 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

The 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

A 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

The 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

The 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

Post‐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

β‐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

On 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.
Cyclopolymerization. IV. Structure of polymethacrylic anhydride and kinetics of polymerization of methacrylic anhydride
Authors: Smets G. , Hous P. , Deval N.
Published: April 2003

The cyclopolymerization of methacrylic anhydride at 36.6°C. produces a polymer whose structure has been examined by infrared spectrometry and bromometric analysis. This polymer contains mainly hexaatomic rings of the A type (absorption bands at 1800 and 1760 cm.−1) and open anhydride units with unsaturated side‐groups, the content of which varies only slightly with the monomer concentration. Polymerization at 100°C. produces some syndiotactic hexaatomic rings (1730 cm.−1). Chemical analysis of the polymers obtained at 36.6°C. for different monomer concentrations permitted the ratio of the rate constants of vinyl propagation to that of cyclization to be evaluated. This ratio is 0.022 l./mole, compared to 0.17 l./mole for acrylic anhydride. From a plot of the reciprocal of the degree of cyclization against the monomer concentration the values of the ordinate intercepts are interpreted on the basis of chain transfer reaction with monomer and intramolecular isomerization. From a kinetic point of view, the order of reaction at 36.6°C. with respect to the concentration of initiator varies from 0.66 to 0.58 for monomer concentrations of 0.656 and 3.282 mole/l., respectively. With respect to the monomer concentration, the order of reaction is one up to a concentration of 3 mole/l.; above this concentration, the order increases progressively. This behavior can be easily explained by the progressive insolubilization of the polymer and the increasing viscosity of the solution.
Cohesive energy density and internal pressure of high polymers
Authors: Voeks John F.
Published: April 2003

A method for estimating the intermolecular pair potential in high polymers from density data alone is illustrated. The cohesive energy density and internal pressure of several polymers are calculated in this way. The results agree satisfactorily with various other estimates.
Certain characteristics of the polymerization of butadiene‐1,3 in presence of soluble cobalt complex catalyst
Authors: Diaconescu A. I. , Medvedev S. S.
Published: April 2003

Studies were carried out on the kinetics of the process for producing 1,4‐cis‐polybutadiene in the presence of the catalytic system formed of monochlordiisobutylaluminum and the alcoholic complex of cobalt chloride. The experiments, carried out in homogenneous benzene solution at room temperature, pointed out the predominant role of water: when water is absent butadiene forms oligomers. Under the given conditions, the rate of polymerization of butadiene increases with the increase in the concentration of cobalt or aluminum compound and varies in a strange way when the water concentration changes. The dependence of the rate of polymerization on water concentration accounts for the difficulties in the reproductibility of experiments. The molecular weights of the polymers obtained increase linearly with the increase in water concentration and decrease with the decrease in the concentration of aluminum or cobalt compound. No dependence was noticed between the microstructure of polymers and the conditions of working.
Single crystals of poly(ethylene terephthalate)
Authors: Yamashita Yuhiko
Published: April 2003

Single crystals of poly(ethylene terephthalate) were prepared by evaporating the solvent slowly from dilute solution at crystallization temperature. The single crystals are parallelograms in shape and thicken by spiral growths with screw dislocations at their center. In the electron microscope they are seen to consist of platelets about 100 A. in thickness. Low‐angle x‐ray measurements on the film obtained by filtering the crystal suspension reveal a long spacing in good agreement with that calculated from shadow lengths. Electron and x‐ray diffraction patterns show that the chain molecules are inclined at about 25–35° to the normal to the basal plane of the single crystals and sharply folded within the lamellae. Various morphological features and arrangement of the unit cell in the single crystal platelets are described and discussed.
Investigation of polyacetaldehyde structure by high resolution nuclear magnetic resonance
Authors: Goodman Murray , Brandrup Johannes
Published: April 2003

We examined the configurations of cationically produced amorphous polyacetaldehyde by high resolution NMR spectroscopy at high temperature in such solvents as dimethylformamide and aniline. Our results show that the polymer backbone is composed of heterotactic and isotactic triad sequences, the former predominating over the latter. Using a 60 Mcycle instrument with or without spin decoupling, we were unable to detect any syndiotactic triad sequences. In addition, the 60 Mcycle NMR spectrum of poly‐α‐deuteroacetaldehyde shows the presence of only the same two stereochemical triads as above. However, examination of polyacetaldehyde with a 100‐Mcycle instrument indicated that a small shoulder exists on the low field side of the heterotactic peak which is probably caused by a small syndiotactic triad content. We used these findings to propose a mechanism for the cationic polymerization of acetaldehyde. We suggest that acetaldehyde may exist in a dimeric form under polymerization conditions leading to a preferred incorporation of mesodimeric units into the propagating chain. Model compound studies involving α,α′‐dimethoxyethyl ether are consistent with this postulate.
Photoyellowing of poly(4,4′‐diphenylolpropane isophthalate): A novel polymer photorearrangement
Authors: Maerov S. B.
Published: April 2003

The photoyellowing of 4,4′‐diphenylolpropane isophthalate (DPP‐I) was attributed to a photochemical rearrangement resulting in a polymer containing o‐hydroxybenzophenones as part of the chain structure. Chain cleavage by photolysis was an accompanying side reaction. o‐Hydroxybenzophenone derivatives of DPP were prepared to serve as model compounds to confirm the structure of the photorearrangement product. Additional confirmation of the mechanism was obtained by solid phase or solution photorearrangement of the model ester, DPP dibenzoate to its monohydroxybenzophenone derivative. Kinetics of the DPP‐I photorearrangement exposed to a xenon high pressure lamp and a carbon are lamp gave rates of 3.9 × 10−2 and 3.8 × 10−3 mole/1.‐hr., respectively. The rate of yellowing in Florida sunlight, open exposure in April, was 1.5 × 10−2 mole/1.‐hr.
Some statistical properties of flexible ring polymers
Authors: Casassa Edward F.
Published: April 2003

The conventional “string‐of‐beads” statistical model for flexible chain polymers is modified for derivation of configurational and thermodynamic properties of long‐chain ring molecules (i.e., flexible linear chains with ends joined) in dilute solution near the Flory temperature. The effect of the intramolecular excluded volume on the meansquare molecular radius is obtained to the first order of approximation; the second virial coefficient is given to the “double contact” approximation; and the angular intensity distribution for Rayleigh scattering is determined for the unperturbed molecule. Qualitatively, all these properties, in comparison to those for linear chains of the same mass, are affected as anticipated from the more compact nature of the ring model.
Localized deformation of lamellar polyethylene crystals
Authors: Reneker D. H.
Published: April 2003

The mechanical and morphological properties of lamellar crystals of polyethylene were studied by deliberately deforming the crystals with a localized strain of known direction and amplitude. In most of the experiments the deformation was achieved by placing the polymer crystals on a thin, brittle, electron‐transparent substrate which was supported by a plastic film. Elongation of the plastic film cracked the brittle substrate, and the polyethylene crystals either broke or were converted into fibers and drawn across the cracks. The breaking and drawing properties of the crystal are related to the orientation of the crystal with respect to the crack and to the intersection of fold domains by the crack. Localized deformation of crystals in suspension by ultrasonic irradiation and by other means is discussed.
Probabilistic considerations of the tacticity of optically active polymers
Authors: Fueno Takayuki , Shelden Ronald A. , Furukawa Junji
Published: April 2003

The probability theory of Markov chains used in the characterization of stereoregular polymers is extended to optically active high polymers. The degree of tacticity is expressed in terms of the transition probabilities for chain growth which is asymmetric with respect to selection of monomer unit configurations. The variation of the Bovey tacticities with the probability parameters is illustrated for the case of asymmetric, simple Markov chains. The relations between tacticity and configurational asymmetry of optically active polymers are discussed.
Aromatic polypyromellitimides from aromatic polyamic acids
Authors: Sroog C. E. , Endrey A. L. , Abramo S. V. , Berr C. E. , Edwards W. M. , Olivier K. L.
Published: April 2003

Aromatic diamines react with pyromellitic dianhydride in solvents such as dimethyl‐acetamide to form solutions of high molecular weight polyamic acids. These soluble polymers can be converted to insoluble aromatic polyimides. The aromatic polyimides exhibit zero strength temperatures above 700°C. and possess excellent thermal and oxidative stability. The stability characteristics of films and the relation of chemical structure to thermal and hydrolytic stability and to polymer properties such as crystallinity are described.
Base‐catalyzed polymerization of aromatic sulfonamides with an activated double bond. I
Authors: Yoda Naoya , Marvel C. S.
Published: April 2003

The base‐catalyzed polymerization of p‐styrenesulfonamide has given a product with mixed recurring units, some produced by anionic‐initiated vinyl polymerization and some by proton‐transfer polymerization. The products are high softening but yield brittle films. Some preliminary results have been obtained for the polymerization of p‐acryl‐amidobenzenesulfonamide and the related crotonyl and cinnamoyl derivatives. Synthetic methods for the monomers are described.
Polymerization of trioxane by crystallization on activated seeds from cyclohexane solutions
Authors: Morelli F. , Masetti G. , Butta E. , Baccaredda M.
Published: April 2003

The preparation of polyoxymethylene of high molecular weight by polymerization of trioxane, starting from concentrated solutions in hydrocarbon solvents (cyclohexane) initiated by addition of a cationic catalyst (BF3 etherate) and inducing the crystallization of trioxane by cooling the system from the initial to room temperature, is investigated. The success of the method depends largely on the time of permanence of the solution at the initial temperature after the induction period (activation time) the initial solution, which can be controlled by following the temperature variations of the system during this stage. The cooling of the activated solution may be performed either continuously, in which case it may be varied from 15 to 200°C./hr., or in two stages: quenching from the initial temperature to the precipitation point followed by controlled cooling at a lower rate from this point to room temperature. The latter method is preferable when initial temperatures higher than the melting point of the pure trioxane are chosen. Products having inherent viscosities ranging from 2.0 to 3.0 dl./g. (in 0.5% solutions in p‐chlorophenol at 60°C.) are obtained.
Fractionation of polydienes by means of precipitation chromatography
Authors: Poláček J. , Kössler I. , Vodehnal J.
Published: April 2003

The fractionation of polychloroprene, polyisoprene, and polybutadiene was carried out by a modified Baker‐Williams chromatographic precipitation technique. The anomalous decrease of molecular weights of last fractions is explained as a result of oxidation processes leading to formation of peroxide bonds in the polymer. A correlation between the CO group content and the value of the constant, k′, of the Schulz‐Blaschke equation was found. The advantage of maintaining a relatively low temperature during the precipitation process and the influence of the method of preparation of the polymer film on the molecular weight distribution curve has been demonstrated.
Electron spin resonance of heat‐treated poly(vinyl chloride)
Authors: Ouchi Isuke
Published: April 2003

Poly(vinyl chloride) was heat‐treated, in most cases below 400°C., either in air or in a vacuum and examined by ESR by means of a spectrometer with modified microwave circuit. The ESR signals are first observed at an early stage of degradation and increase with heating time. In the case of heat treatment in a vacuum, the ESR stops increasing when dehydrochlorination is nearly finished, while in the case of the treatment in air, the signal continues to increase after dehydrochlorination is finished. The effects of oxygen and the saturation characteristics of the ESR are quite different for the chars heat‐treated below 400°C. and those heat‐treated above 400°C. Below 400°C., the signal shows strong saturation in a vacuum but not in air. Oxygen easily affects the signal, shortening the spin‐lattice relaxation time. For the char treated above 400°C., the signal does not saturate as strongly and is quenched by oxygen.
Absorption spectra of poly‐p‐iodostyrene
Authors: Luongo J. P. , Salovey R.
Published: April 2003

From the infrared and ultraviolet spectra of iodinated polystyrene, the location and amount of the iodine substitution in the polystyrene molecule can be determined. In addition, when isotactic polystyrene is iodinated, the tacticity is retained but the helical conformation of the carbon backbone, both in solution and in the solid state, has been modified. Comparison of the atactic, helical isotactic, and nonhelical iodinated isotactic spectra show that bands at 1297, 585, and 558 cm.−1 and particularly the 1080/1055 cm.−1 doublet can be attributed to the helical conformation of the carbon backbone of isotactic polystyrene.
Epoxide–alcohol reaction catalyzed by boron trifluoride. Part I. Phenyl glycidyl ether–alcohol reaction in dioxane
Authors: Lee Lieng‐Huang , Pankey John W. , Heeschen J. P.
Published: April 2003

Phenyl glycidyl ether, a model compound for bisphenol‐A type epoxy resins, was reacted with alcohols in dioxane in the presence of boron trifluoride etherate. For isobutyl, sec‐butyl, and n‐butyl alcohols the reaction paths were similar and found to be: (1) epoxide–alcohol 1:1 addition, (2) epoxide–alcohol–dioxane addition, and (3) homopolymerization of the expoxide. With excess alcohol, homopolymerization could be minimized. In all cases, the predominant 1:1 adduct was shown to be 1‐butoxy‐3‐phenoxy‐2‐propanol. There was indication that a small amount of the 1:1 adduct containing primary hydroxyl group was formed also. With tert‐butyl alcohol, 3‐phenoxy‐1,2‐propanediol was obtained as well. With phenol, the main reaction was homopolymerization of phenyl glycidyl ether.
Critical conditions for formation of infinite networks in branched‐chain polymers
Authors: Tanaka Yoshio , Kakiuchi Hiroshi
Published: April 2003

The conditions necessary for infinite network formation due to the bifunctional inter‐unit junction were reinvestigated, and the difference in theories between Flory and Case or Kahn was mentioned. The theory is extended to a more general case than those of Flory and of Case or Kahn. It also deals with the critical point in the condensation reaction between mixtures of two types of functional groups containing one or more functionalities. It is shown that at the critical point,
\documentclass{article}\pagestyle{empty}\begin{document}$ P_A P_B \left( {1 - \rho _1 } \right)\left( {1 - \sigma _1 } \right)\sum\limits_{}^n {_{\rho i} \left( {fi - 1} \right)} \sum\limits_{}^n {_{\sigma i} \left( {gi - 1} \right)} = 1 $\end{document}
and/or
\documentclass{article}\pagestyle{empty}\begin{document}$ \left[ {{1 \mathord{\left/ {\vphantom {1 {\left( {1 + r} \right)}}} \right. \kern-\nulldelimiterspace} {\left( {1 + r} \right)}}} \right]\left[ {rP_A \sum\limits_{}^n {_{\sigma i} \left( {gi - 1} \right) + P_B \sum\limits_{}^n {_{\rho i} \left( {fi - 1} \right)} } } \right] = 1$\end{document}
where PA and PB are the respective probabilities that an A or B group has reacted, fi and gi are the functionalities of Ai and Bi monomers, r is the ratio of A groups to B groups at the initial state, and ρi, σi, are the molar fractions of Ai and Bi, respectively.
Crystallization in stretched polymer networks. I. trans‐polychloroprene
Authors: Gent A. N.
Published: April 2003

Measurements are described of the rates of crystallization of uncrosslinked trans‐polychloroprene over a range of temperature and of three crosslinked samples over a wide range of extension and temperature. The large increases in rate with extension are attributed to corresponding increases in the equilibrium melting temperature and hence degree of supercooling. The rise in melting temperature has been measured and is found (1) to account satisfactorily for the observed changes in rate, and (2) to be in good agreement with Flory's treatment of oriented crystallization in stretched networks. The form and magnitude of the changes in tensile stress are also in accord with the formation of oriented crystallites, and seem incompatible with folded‐chain crystallization. When reduced to a condition of constant segmental mobility, the rates of crystallization are shown to follow a common dependence upon the degree of supercooling. This relation is compared with the predictions of nucleation theory.
Dilute solution properties of high molecular weight poly(isobutyl methacrylate). II. Light scattering
Authors: Valles Richard J.
Published: April 2003

A high molecular weight linear sample of poly(isobutyl methacrylate) was fractionated from an acetone–methanol mixture. An adaptation on a Brice‐Phoenix photometer made it possible to run light‐scattering measurements at angles of 15, 20, and 25°, in addition to the usual angles. The addition of the low angles made the angular extrapolations more accurate. The parameters in the Mark‐Houwink equation are reported at several temperatures. The molecular weight range studied was 3 × 106 to 11 × 106.