bluuebunny/crossref_metadata_2025 huggingface dataset:
Homopolymerization of N‐allylacetamide and N‐allylstearamide
Authors: Jordan Edmund F. , Wrigley Arthur N.
Published: April 2003

When benzoyl peroxide was decomposed at 90°C. in N‐allylacetamide and in N‐allylstearamide, d[M]/d[P] was about 2 and DP was between 9 and 10, because of a wastage of benzoyloxy radicals. These radicals formed benzoic acid and benzene as a consequence of hydrogen abstraction from the amide, and the resulting amide radicals became substituted with ester and phenyl groups from the initiator. N‐butylstearamide, a saturated model for N‐allylstearamide, gave corresponding products. Rates of peroxide decomposition indicated strong induced effects, decreasing in the order: N‐allylacetamide, N‐allylstearamide, N‐butylstearamide. Slopes of the linear plots of the four products (in moles per kilogram) against initiator (in equivalents per kilogram) in the three amides in the above order were: benzoic 0.521, 0.570, 0.575; benzene 0.027, 0.086, 0.168; amide substituted by benzoate 0.459, 0.320, 0.106; amide substituted by phenyl 0.087, 0.087, 0.142. Transfer, compared to substitution, increased with chain length and decrease in unsaturation, and induced peroxide decomposition was correspondingly lowered. Thus, kinetic chain decreased with acyl chain length and decrease in unsaturation. A mechanism that postulates polar species in the transition state when amides were solvents accounted for both transfer and aromatic substitution and helped explain the difference in behavior of N‐allylamides and allyl esters. Plots of amide entering polymer (in moles per kilogram) against initiator concentration (in equivalents per kilogram) were curves; plots of log (a – x) for amide disappearance against the same coordinate were linear. Slopes were: N‐allylacetamide −0.0742; N‐allylstearamide −0.1771.
Inadequacies in time–temperature equivalence
Authors: McCrum N. G.
Published: April 2003

The activation energy of the low temperature relaxation in polytetrafluoroethylene is obtained from creep experiments by using the analytical procedure known as time temperature superposition. The activation energy obtained is 25 kcal./mole which is rejected in favor of the value determined in internal friction experiments, 18 kcal./mole. The discrepancy is attributed to temperature variation of the limiting compliances which cause the value obtained using time–temperature superposition to be too high. Comparable discrepancies are anticipated for relaxations in crystalline polymers and amorphous polymers at temperatures below the glass transition.
Radiation‐induced polymerization of acrylonitrile in liquid ethylene
Authors: Tabata Yoneho , Hara Kiyoshi , Sobue Hiroshi
Published: April 2003

A mixed system of acrylonitrile and ethylene was irradiated with γ‐rays from a Co60 source at −78°C. In the mixed system, ethylene did not polymerize, and only acrylonitrile polymerized. It was found that polymerizations due to both CC double bond and the CN triple bond of acrylonitrile occurred in the mixed system. The ratio of one type of polymerization to the other varied continuously with concentration of the monomer; the polymerization of CC only occurs in bulk (100% monomer), as well known, but on the other hand, the polymerization of CN occurs predominantly in a dilute solution of the monomer. The polymerization due to CN triple bond would be by an ionic mechanism, probably an anionic. The experiments showed that the polymerization of acrylonitrile in the ethylene solution proceeds by a partial ionic mechanism at moderate concentrations of the monometer. The product obtained by the polymerization in such a mixed system is a mixture of polymers having the following structures:
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Free radical polymerization and copolymerization of bicyclo‐(2.2.1)‐hepta‐(2.5)‐diene (norbornadiene)
Authors: Pellon Joseph , Kugel Robert L. , Marcus Ruth , Rabinowitz Robert
Published: April 2003

A brief study of the homopolymerization of norbornadiene indicated that pre‐gel polymer is limited to product having reduced viscosities below 0.2 dl./g. Pre‐gel polymer of 17,000 molecular weight was isolated and characterized: pre‐gel polynorbornadiene is soluble in benzene or chloroform, softens at 220–240°C., is thermosetting and shows poor molding characteristics. A cast rod of polynorbornadiene was found to have a heat distortion temperature of 186°C. and a flexural strength of 13,300 psi. Copolymer reactivity ratios of norbornadiene (M1) determined with vinyl acetate were r1 = 1.3 and r2 = 0.8; with p‐chlorostyrene, r1 ≈ 0.01 and r2 ≈ 85. Thermal behavior of several copolymers was determined.
Refractive indices and compositions of crazes in several glassy polymers
Authors: Kambour Roger P.
Published: April 2003

The void contents of crazes in four glassy polymers have now been determined from measurements of craze refractive indices. The void contents of poly(methyl methacrylate), polystyrene, polycarbonate, and styrene‐acrylonitrile copolymer crazes are 40, 40, 45, and 60%, respectively. Available evidence suggests that craze void content does not depend on use of a crazing agent.
Refractive index and composition of poly(methyl methacrylate) fracture surface layers
Authors: Kambour Roger P.
Published: April 2003

By using the phenomenon of total internal reflection of light the refractive index of the thin layer present on fresh poly(methyl methacrylate) fracture surfaces has been measured. The fracture surface refractive index, 1.32, is the same as that of the craze in the same polymer. The fracture surface layer is accordingly thought to be craze like in structure.
Penultimate unit effects in terpolymerization
Authors: Ham George E.
Published: April 2003

Although the effects of penultimate units in binary copolymerization have been extensively treated, the investigation of these effects in terpolymerization has been neglected. Undoubtedly, this neglect is attributable to the fact that possible effects arising from twenty‐seven different propagation possibilities must be considered. Fortunately, for practical purposes, it often occurs that only a few of the penultimate possibilities are important in determining copolymer composition, and that most of the propagating steps can be treated with regard to terminal unit effects alone. Simplified equations are presented which allow for such restrictions. These equations are applied to several experimental examples. In addition, simplified terpolymer equations are derived which allow for the circumstances where one or two homopropagation rate constants approach zero. Furthermore, methods are introduced for assessing K32/K31 where K33 approaches zero. These methods lead, in turn, to more precise assessments of Q and e for 1,2‐disubstituted olefins.
Free‐radical polymerization of olefins
Authors: Mortimer George A. , Arnold Lloyd C.
Published: April 2003

Propylene, butene‐1, isobutylene, 3,3‐dimethylbutene‐1, and tetradecene‐1 were polymerized at high pressures at 130–150°C. with dixy1tert‐butyl peroxide initiator to give low molecular weight polymers. Free radical copolymerization of propylene and isobutylene was also demonstrated. Facile chain transfer to give relatively stable radicals was blamed for the low rates and degrees of polymerization. The molecular weights were shown to be controlled by chain transfer.
Stereospecific polymerization of 2‐substituted‐1,3‐butadienes. I. Crystalline polymers of 2‐tert‐butyl‐1,3‐butadiene
Authors: Marconi W. , Mazzei A. , Cucinella S. , Cesari M.
Published: April 2003

Some results obtained in the stereospecific polymerization of 2‐tert‐butyl‐1,3‐butadiene are reported. The catalysts employed were prepared from TiCl4 and aluminum alkyls or soluble aluminum hydride derivatives. Polymers thus obtained were crystalline with a melting point of 106°C. and soluble in common solvents. X‐ray investigation shows the polymer to have a helical chain structure built on 11 monomeric units with cis configuration, distributed on three turns. The identity period along the chain axis is 15.3 A. A comparison of the infrared spectra of the crystalline and amorphous polymers is given. Attempts to obtain a crystalline 1,4‐trans polymer failed; this is in accord with the lower stability of such a configuration due to steric repulsion of the bulky group.
Polymerization in liquid sulfur dioxide. Part XXI. Effect of liquid sulfur dioxide concentration on cationic copolymerization of styrene with methyl acrylate in liquid sulfur dioxide
Authors: Matsuda Minoru , Ohshima Koichi , Tokura Niichiro
Published: April 2003

The effect of liquid sulfur dioxide concentration on cationic copolymerization of styrene (M1) with methyl acrylate (M2) was carried out with the use of boron trifluoride–ether complex as a catalyst. The reaction was carried out at 0°C. The monomer reactivity ratios r1 and r2 increased with increase in liquid sulfur dioxide concentration, and r1 was changed from r1 = 0.30 at [liq. SO2]0 = 6.58 mole/l., to r1 = 1.50 at [liq. SO2]0 = 13.16 mole/l., but r2 was not changed. These facts indicated that reactivity of carbonium ion of styrene in the propagation step was increased with increasing liquid sulfur dioxide concentration. The relation between the overall rate of copolymerization and liquid sulfur dioxide concentration is the same as in the case of the cationic homopolymerization of styrene, and polymolecular contribution of liquid sulfur dioxide on the overall copolymerization is shown from these observations.
A critical evaluation of mathematical molecular weight distribution models proposed for real polymer distributions. I. Effects of a low molecular weight cut‐off value
Authors: Kotliar A. M.
Published: April 2003

It is of considerable practical importance to be able to describe the distribution of molecular sizes of a polymeric material by a convenient mathematical expression. Since the various molecular averages of any distribution are obtained from a summation process, the general models require an analytical expression of the differential distribution and a corresponding definite integral generally having the integration limits of zero and infinity. In general, real polymer distributions do not fit these integration limits and an error, which can be very large, is therefore introduced. If the error in the various molecular weight averages due to changes in integration limits is of the order of or less than the error generally encountered in the experimental evaluation of the average, the distribution function can be considered to be applicable from a practical point of view. In addition, the selected model should fulfill the requirements of fitting known experimental facts such as: the polymerization kinetics, the effects of random degradation and crosslinking, fractionation data, and the effects of polymerization and processing on the differential distribution maxima. It should also conform to the rheological behavior based on current theoretical ideas. The integration limit criteria are applied to logarithmic normal type distributions, e.g., Wesslau, and generalized exponential type distributions, e.g., Schulz‐Zimm and Tung. The results show that logarithmic normal type distributions cannot be considered as useful models, while the generalized exponential type distributions can be valid and useful representations.
Applicability of polymer network theories to gels obtained by crosslinking a polymer in solution
Authors: Mukherji B. , Prins W.
Published: April 2003

Current polymer network theories exhibit inconsistencies which show up particularly clearly when one considers the three‐dimensional deformation (swelling) of networks which are prepared by crosslinking a polymer in solution. A check on the theories can only be obtained if one knows precisely the number of crosslinks in the network and if a range of deformations (range of swelling ratios) is imposed on the network. To this end a series of seven gels was prepared by crosslinking secondary cellulose acetate (D.S. = 2.42) in dioxane solution (5–10%) with dianisidine diisocyanate. The number of chemical crosslinks was determined by reacting unused isocyanate groups with C14‐labeled methanol. Subsequently, changes in the degree of swelling of the gel, induced by increasing concentrations of cellulose acetate in dioxane and methyl acetate solutions around the gel, were followed by measuring accurately the changes in length of 2‐cm. strips under a travelling microscope. At equilibrium swelling the activities of the solvent inside and outside the gel are equal. For the outside solutions the activities were derived from osmometry. The inside activities derive from a mixing term and an elastic deformation term. The mixing term was approximated by using the Flory‐Huggins expression with an interaction parameter, as obtained from osmometry on a derivative, which was prepared by reacting cellulose acetate with an excess of diisocyanate, thus avoiding network formation. By means of the various known theoretical expressions for the elastic deformation term, the swelling data allow the calculation of the number of crosslinks in the gels. All theories lead to far fewer crosslinks than are known to be there on the basis of the chemical analysis. This has never been observed to the same extent before, but may be specific for gels obtained by crosslinking in solution. One is forced to conclude that none of the existing theories are applicable. The data can be explained, however, by postulating that the configurations of the chains between crosslinks do not follow a Gaussian distribution, but are instead given by ω(r)dr = ωx(x)‐ωy(y)ωz(z) dxdydz, where ωx(x) = C|x|n exp { −bx2}. Such a non‐Gaussian distribution might arise because of topological restrictions, possibly including those due to the excluded volume. For the free energy of elastic deformation we find, following James and Guth's reasoning but using the new distribution function:

where v is the number of chains in the network and λx, λy, and λz are the deformation ratios with respect to the unstrained state. In the well known Gaussian theories, the term n + 1 is absent and in front of the logarithm instead of n either 0, 2/f, or 1 (f = functionality of the crosslink) is found, depending on whether the result of James and Guth, Flory and Wall, or Hermans is used, respectively.
Epoxidation of poly‐2‐methyl‐6‐allyl‐1,4‐phenylene oxide and copolymer of 2‐methyl‐6‐allyl‐4‐bromophenol and 2,6‐dimethyl‐4‐bromophenol
Authors: Tsou K. C. , Hoyt H. E. , Halpern B. D.
Published: April 2003

Epoxidized homopolymer of 2‐methyl‐6‐allyl‐4‐bromophenol and its copolymers with 2,6‐dimethyl‐4‐bromophenol have been prepared. When more than theoretical amount of peracetic acid was used, chain degradation occurred. This chain degradation was also demonstrated by the reduction in viscosity of poly‐(2,6‐dimethyl)‐1,4‐phenylene oxide when treated with peracetic acid under similar conditions.
Endgroup studies in persulfate‐initiated vinyl polymer by dye techniques. Part II. Initiation by redox persulfate systems
Authors: Ghosh Premamoy , Chadha Subhash Chander , Palit Santi R.
Published: April 2003

Poly(methyl methacrylate) samples obtained by aqueous redox initiation with persulfate in conjuction with reducing sulfoxy compounds such as HSO3−, SO3−, S2O3−S2O4−, and S2O5− are found by dye techniques to contain both hydrolyzable sulfate endgroups (derived from persulfate) and nonhydrolyzable sulfonate endgroups or the like (derived from the activator) to an average total of about 2 endgroups per polymer molecule. Sulfide (S−) is unique as an activator, as only sulfate endgroups ( no sulfonate or hydroxyl) have been found in the polymers. Persulfate used in conjunction with other activators (such as Ag+, Fe++ hydrazine and hydroxylamine, aliphatic amines, alcohols, reducing acids and their salts, etc.) produce polymers with both sulfate and hydroxyl endgroups. Incorporation of sulfate endgroups is favored under basic conditions and tends to be suppressed under acid conditions.
Polymers containing the cyclopentyl and cyclohexyl groups
Authors: Ketley A. D. , Ehrig R. J.
Published: April 2003

Polymers have been prepared from a group of monomers containing the cyclohexyl and cyclopentyl groups. These monomers were of the type (C6H11)(CH2)nCHCH2, (where n = 0–3) and (C5H9)(CH2)nCHCH2 (where n = 0−1). Both Ziegler‐Natta and Friedel‐Crafts catalysts were used. By comparison of the infrared spectra of corresponding polymers prepared with the two types of catalysts, it has been shown, for the cyclohexyl compounds, that intramolecular hydride transfers take place to a significant extent during the propagation step of the Friedel‐Crafts polymerizations. These hydride transfers result in the formation of a tertiary carbonium‐ion end which, on propagation, leads to a polymer in which cyclohexyl groups are part of the main chain. The cyclopentyl compounds, however, do not behave in this way. In this case, the relative reactivities of the tertiary and secondary carbonium ions are such that propagation through the latter is favored. Attempts to polymerize 2,4‐spiroheptane and 2,5‐spirooctane to give model compounds for the “rearranged” polymers are also reported.
Reaction of polystyryllithium with carbon dioxide
Authors: Wyman D. P. , Allen V. R. , Altares T.
Published: April 2003

A benzene solution of polystyryllithium of narrow chain length distribution was found to react with carbon dioxide to form (upon acidification) not only the corresponding polystyrene carboxylic acid but also significant amounts of di‐polystyryl ketone and tri‐polystyryl carbinol. The amounts of the latter two products were somewhat dependent on the rate at which carbon dioxide could be added to the system. Thus, the yields of di‐polystyryl ketone and tri‐polystyryl carbinol were 28% and 12% respectively, if termination was accomplished by allowing gaseous carbon dioxide to diffuse into the system, but the total yield of these products was only 22% if the termination was carried out by pouring the polystyryllithium solution onto crushed, solid Dry Ice. Lithium polystyrene carboxylate was found to be partly associated in benzene and cyclohexane, but the free acid was not.
Polymerization of tert‐butyl crotonate
Authors: Miller M. L. , Skogman J.
Published: April 2003

Lithium alkyls and phenylmagnesium bromide, in toluene, and lithium‐naphthalene, in dimethoxyethane, polymerize tert‐butyl crotonate. Sodium naphthalene produces only low polymer (Mn <3000), and potassium naphthalene gives no polymer. Even lithium naphthalene, which polymerized tert‐butyl crotonate readily, fails to polymerize tert‐butyl tiglate. Free radicals polymerize neither tert‐butyl crotonate nor tert‐butyl tiglate. Poly(tert‐butyl crotonate) formed in the presence of lithium naphthalene is noncrystalline, in the presence of lithium alkyls, either noncrystalline or partly crystalline, and in the presence of phenylmagnesium bromide, highly crystalline. Poly(crotonic acid) was prepared from poly(tert‐butyl crotonate).
A study of the statistical character of anionic polymers
Authors: Nanda V. S. , Jain R. K.
Published: April 2003

The effect of initiation and propagation rate constant ratio on the statistical character of termination‐free anionic polymers is discussed. For obtaining the expressions for the size distribution and the averages, we have followed a mathematical procedure which might prove useful in the treatment of more complicated problems. The conditions under which the ultimate polymer has an appreciable or negligible inhomogeneity are clearly stated.
Polymerization of higher aldehydes. III. Elastomeric polyacetaldehyde
Authors: Vogl O.
Published: April 2003

Amorphous elastomeric polyacetaldehyde was prepared in bulk and in solution using cationic initiators. This polymer is the same as Letort's polyacetaldehyde. The acetaldehyde polymerization must be conducted at −40°C. or lower in order to overcome the competitive trimerization or tetramerization. The reactivity of a number of initiators can be modified by using different solvents. The influence of temperature and type of initiator and solvent on the polymerization was studied.
Adsorption of poly(vinyl acetate‐C14) on smooth, geometrically simple surfaces
Authors: Weatherwax R. C. , Tarkow Harold
Published: April 2003

Poly(vinyl acetate‐C14)(PVA) was adsorbed from a variety of benzene and carbon tetrachloride solutions on swollen and shrunken cellophane film, on glass, and on cellulose acetate film. The surfaces were geometrically simple, permitting mechanical measurements of the areas. Glass, shrunken cellophane, and cellulose triacetate adsorbed equal amounts of PVA. Swollen cellophane, however, adsorbed 40 times as much PVA as shrunken cellophane. Desorption experiments indicated that the high PVA adsorption on swollen cellophane showed the high reactivity of the surface rather than the diffusion of PVA into the cellophane.
Synthesis and electrical conductivity measurements on semiconducting organic polymers derived from nitriles
Authors: Wildi B. S. , Katon J. E.
Published: April 2003

A number of polymeric organic semiconductive materials derived from low molecular weight nitriles are described. These infusible, insoluble materials possess electrical resistivity values which are remarkably low for organic materials. The synthesis and resistivity–temperature behavior of these materials is described and their probable structures discussed.
Thermal degradation of ethylene bis(N‐phenylcarbamate)
Authors: Beachell H. C. , Son C. P. Ngoc
Published: April 2003

The pyrolysis of ethylene bis(N‐phenolcarbamate) was studied as the simplest model of a polyurethane. The degradation occurs by a double process of decomposition involving the simultaneous formation of 3‐phenyl‐2‐oxazolidone, carbon dioxide, and aniline and a partial dissociation into monocarbamate and phenyl isocyanate. Further reaction produces ethylene oxide, N,N′‐diphenylethylenediamine, N,N′‐diphenyl‐2‐imidazolidone, and N,N′‐diphenylurea.
Polybenzimidazoles. I. Reaction mechanism and kinetics
Authors: Wrasidlo Wolfgang , Levine Harold H.
Published: April 2003

Poly‐2,2′‐(m‐phenylene)‐5,5′‐bibenzimidazole forms, via two or three intermediates, when 3,3′‐diaminobenzidine and diphenyl isophthalate are condensed. Kinetic data indicate rapid consumption of 3,3′‐diaminobenzidine to form an aldol type intermediate which evolves water to form a Schiff base which in turn evolves phenol to form the final polymer. Phenol evolution is the rate‐determining step. The postulated Schiff base can possess stereoisomerism. Intramolecular hydrogen bonding which can occur in the syn‐isomer offers an explanation why the condensation affords a linear polymer. The combined effects of intramolecular hydrogen bonding and added resonance stabilization in the Schiff base are possible reasons why phenol evolution is the rate‐determining step and why the condensation requires high reaction temperatures.
Mechanism of alternating inter‐intramolecular propagation. II. General kinetics
Authors: Gibbs William E.
Published: April 2003

The general kinetics of alternating inter‐intramolecular propagation are presented and discussed. The major factor which determines the microstructure of the polymer, the relative rates of the intramolecular and intermolecular reactions is examined. From the general kinetics methods are proposed for the determination of the ratio of rate constants for these reactions. A simple method utilizes the equation: [m1]/[M3] = 1 + (kc/k11)(1/[M1]0), where [m1] is the concentration of monomer units in the polymer, [M3] is the concentration of uncyclized units, [M1] is a parameter related to monomer concentration, kc is the rate constant for cyclization and k11 the rate constant for linear propagation. Other methods which may give information on the nature of the termination reaction are discussed.
Study of the hexamethylenediamine–cellulose complex
Authors: Segal Leon , Eggerton F. V.
Published: April 2003

Complete conversion of the cellulose crystal lattice to that of the hexamethylene diamine–cellulose complex was attained with diamine solutions of 75% and greater. Solutions of 70% or less produced only partial conversion, although the samples contained high diamine contents. Evaporation temperatures over 90°C. reduced these diamine contents and resulted in partial lattice conversion. Neither this effect nor those following have been observed in the ethylenediamine–cellulose complex. The complex did not change while held in vacuum over sodium hydroxide pellets but gained weight when held in air. After long exposure the yarn was stiff and coated with white powder believed to be hexamethylenediamine carbamate. Attempts to react the complex with cellulose and diamine reactants were not successful. Evidence could not be found for a 2:1 molecular ratio between anhydroglucose units and diamine. Extent of fiber swelling was related to diamine content of the fiber and not to distention of the unit cell. Differences were observed in the intensities of the 101 and 101 x‐ray interferences of the cellulose I and cellulose II complexes.
Glass transitions of polyoxetanes
Authors: Stratta J. J. , Reding F. P. , Faucher J. A.
Published: April 2003

Glass transition data of polyexetanes suggest that the responsible segmental chain motions are rather short range in nature. The incorporation of three different structural features within the repeat unit of a polyoxetane results in three separate and independent transition temperatures. The temperature positions of the transitions arising from different structures within the chain are essentially the same as observed in other polymers with a similar structural element. Structural groups and their corresponding transitions which were studied in combination are: CH2CH2CH2 at −125°C., CH2OCH2 at −50 to −70°C., and CH2CHCH3CH2 or OCHCH3CH2 at −20 to −30°C.
Polymers and copolymers of vinyl pinolate and some reactions with isocyanates
Authors: Malzahn R. A. , Griffith J. H. , Marvel C. S. , Hedrick Glen W. , Lewis J. B. , Mobley Carolyn R. , Magne F. C.
Published: April 2003

Vinyl pinolate has been synthesized, and its homopolymers and copolymers with vinyl chloride and vinyl acetate have been prepared. The reactions of copolymers of vinyl pinolate with vinyl acetate and vinyl chloride with some isocyanates were investigated. The emulsion copolymer of vinyl pinolate and vinyl chloride has been evaluated as a nonrigid plastic.
Processus de l'ecoulement visqueux des hauts polymères
Authors: Bauwens Jean‐Claude
Published: April 2003

Two recent theories concerning the viscosity of high polymers are summarized: the first one, by Bueche, is based on a complex activation process; the other one, established by Cohen and Turnbull to explain the empirical equation of Williams, Landel, and Ferry, is based on the value of the free volume. The discrepancies with the experimental values are emphasized. A mechanism of deformation is proposed which implies that the displacement of a segment of a macromolecule requires the localization of no holes, at least, in a volume which contains No segments Then, the variation of the number of holes with the temperature is computed, with account of the flex energy of the backbone chain and the formation energy of holes (like Flory, and Gibbs and di Marzio). The theoretical results are in good agreement with the experimental values of the variation of the viscosity with the temperature, the second‐order transitions (thermal expansion and heat capacity), and the variation of the glass temperature with the molecular weight. A simple activation process can also produce the deformation and has the most important contribution at low temperature. It is believed that similar mechanism of diffusion of holes can also explain the viscosity of mineral glasses.
Synthesis and cyclopolymerization of 4,4‐dimethyl‐1,6‐heptadiene‐3,5‐dione
Authors: De Winter W. , Marvel C. S.
Published: April 2003

Dimethyldiacrylylmethane has been synthesized and polymerized to yield a soluble polymer which has the cyclic 1,3‐diketone structure. It has not been possible to prepare a polydioxime of this polyketone, but a monooxime with only 90% oximated structure was obtained. This monooxime underwent the Knoevenagel reaction to yield a partial ladder polymer which had interesting thermal stability.
Study of the preparations of a piperazine polyurea and polyamide by low temperature solution polymerization
Authors: Kwolek Stephanie L.
Published: April 2003

The preparations of two condensation polymers by low temperature solution polymerization are compared for the effect of reactant imbalance upon molecular weight. In addition, other variables, such as solvent selection, reaction time, and stirring rate are examined. The polymers are the polyamide from trans‐2,5‐dimethylpiperazine and terephthaloyl chloride and the alternating polyurea from trans‐2,5‐dimethylpiperazine and methylene bis(4‐phenyl isocyanate). In contrast to the polyamide‐forming reaction, the polyurea polymerization does not require acid acceptors and produces no by‐products. The investigation led to the preparation of extremely high molecular weight polyureas by use of the inert solvent mixture, tetramethylene sulfone–chloroform. Poly(N,N,‐terephthaloyl‐trans‐2,5‐dimethylpiperazine) was previously shown to have an unusual lack of sensitivity to reactant imbalance as compared to melt polycondensation when excess diamine was used as the acid acceptor. Similar behavior is found for the polyurea as well as the polyamide when tertiary amine is used as the acid acceptor. However, under certain conditions, side reactions can cause the formation of polyamides with lower inherent viscosity values than calculated. In both cases the insensitivity to reactant imbalance is ascribed to an extremely fast reaction.
Dependence of the glass transition temperature of polyacrylonitrile on molecular weight
Authors: Beevers R. B.
Published: April 2003

The glass transition temperature of polyacrylonitrile has been determined for polymer varying in molecular weight from 8 × 103 to 3 × 106. Results could be represented by Tg = (96.5 ± 1.0) − (2.8 ± 0.1) × 105/M̄n, giving for the glass temperature of a polymer of infinite chain length, 96.5 ± 1.0°C. Specimens showing coloration gave enhanced glass temperatures attributable to the stiffening effect of conjugated ring structures, and were excluded from consideration of the effect of molecular weight. Determination of Tg were made on films prepared from solutions of polymer in dimethylacetamide, butyrolactone, and dimethyl sulfoxide in addition to dimethylformamide. Dependence on weight percentage of polymer, w2, for the range 90 < w2 < 100 was given by Tg = (3.19 ± 0.03)w2 − (232 ± 4), no specific solvent effect being observed.
Polymerization of conjugated trienes
Authors: Bell Vernon L.
Published: April 2003

The polymerization of 1,3,5‐hexatriene, 1,3,5‐heptatriene, and 2,4,6‐octatriene with a variety of catalysts established the trienes as a distinct class of monomers which lead to unique unsaturated polyolefins. Soluble, high molecular weight polymers with predominantly 1,6‐enchainment were prepared with a soluble coordination catalyst system; this mode of polymerization resulted in 1,3‐dienyl groups in the polymer backbone. A stereospecific 1,6‐polyhexatriene, with a novel type of crystallinity based on trans, trans‐1,3‐diene repeat units, was prepared by low temperature polymerization with a vanadyl trichloride–triisobutylauminum catalyst.
Studies of the reduction of titanates and alkoxytitanium(IV) chlorides by alkylaluminum chlorides
Authors: Moyer Patricia H.
Published: April 2003

Replacement of up to two of the chloride ligands on titanium tetrachloride with isopropoxy or butoxy groups results in an increase in the rate of reduction by alkylaluminum chlorides. The final product is still a titanium(III) compound. A decrease in rate results from replacement of more than two of the chloride ligands by alkoxy, or of the chloride ligands on aluminum by alkoxy. Exchange of alkoxy between titanium and aluminum occurs concurrently with reduction. These observations are explained in terms of the relative ease of replacement of a ligand on titanium by alkyl and the relative stability of the alkyltitanium compounds formed.
Rheo‐optical properties of polymers. VII. On time‐dependent infrared absorbance in polymer films
Authors: LeGrand D. G.
Published: April 2003

A theory is developed to show the use of infrared spectroscopy in the study of response of polymers to dynamic mechanical stress or strain. Preliminary experimental results are presented.
An infrared structural study of fluorocarbon polymers
Authors: White Horace F.
Published: April 2003

The 3μ infrared spectra of copolymers of ethylene and 1,1‐difluoroethylene with chlorotrifluoroethylene have been investigated. By applying “dilute solution” techniques, models for head‐to‐head and head‐to‐tail polymers have been prepared and spectrally characterized. The model spectra have been used to explain the polymerization of homopolymers and copolymers of halogenated ethylenes.
Polyacrylonitrile prepared in ethylene carbonate solution. I. Kinetics at low conversion
Authors: Peebles L. H.
Published: April 2003

The kinetics of acrylonitrile polymerization initiated by azobisisobutyronitrile in ethylene carbonate solution were studied at 50 and 60°C. Under these conditions simple solution polymerization kinetics should apply. The initial rate of polymerization was determined by varying the amount of initiator and the monomer concentration. The reaction is found to be first‐order in monomer concentration and approximately 0.6‐order in initiator concentration. The free radical derived from ethylene carbonate (by abstraction of a proton by a growing chain) apparently can only react with a monomer to start another polymer chain. It does not enter into termination reactions. That is, the solvent acts only as a transfer agent and a diluent and does not affect the rate of polymerization by entering into other reactions. The transfer reactions are relatively unimportant (transfer to monomer is negligible: transfer to solvent is small) as indicated by a study of the degree of polymerization calculated from the intrinsic viscosity. Thus, quite high molecular weight polymer can be obtained. The reaction is first‐order to high conversion and is independent of the viscosity of the medium.
Polyacrylonitrile prepared in ethylene carbonate solution. II. Kinetics at high conversion
Authors: Peebles L. H.
Published: April 2003

The first paper in this series has shown that when acrylonitrile is polymerized in ethylene carbonate, the transfer‐to‐monomer reaction is negligible, and the solvent acts only as a diluent and as a transfer agent. Furthermore, the rate of polymerization is first‐order to quite high conversions, even though there is a concomitant high viscosity of the polymerization media. These observations permit calculation of the effect of conversion on the average molecular weight of the polymer. The constants of this calculation were evaluated from low conversion polymerizations and applied to the case of high conversion. The measured weight‐average molecular weights as a function of conversion agree with the calculation and indicate that transfer‐to‐polymer reactions are probably very small. Hence, the extent of branching in polyacrylonitrile prepared in solution is also very small even at high conversions.
Probabilistic model for the structure of the microfibril of cellulose
Authors: Mejzler D.
Published: April 2003

A probabilistic model is presented for the structure of an “ideal” microfibril of cellulose and the distribution of weak bonds along this microfibril is calculated. Exact and asymptotic formulas are derived for the number and weight distributions and for the corresponding averages. The relationship is examined between the model of Kuhn, accepted in theory of random degradation of chain polymers, and the probabilistic model which describes the structure of the ideal microfibril of cellulose.
Crystallization kinetics of high polymers: Isotactic polystyrene
Authors: Hay J. N.
Published: April 2003

The crystallization kinetics of a sample of isotactic polystyrene have been measured at various temperatures. Despite the presence of secondary crystallization sufficient accuracy can be attained to enable an Avrami relationship with a constant integral value of n to be assigned to most of the rate curves. The interpretation of the Avrami constants in terms of crystallization by growth of spherical entities, produced at fixed sites, is verified by microscope observations.
Correct determination of Staudinger's index (intrinsic viscosity) and of Huggins' constant
Authors: Ibrahim Fadel W.
Published: April 2003

Intrinsic viscosities [η] and Huggins' constants k are generally determined by means of one of the following equations:

It was proven in an earlier paper that eq. (1) is an insufficient approximation of eq. (2) in the usual range ηr = 1.2–2.0. In this paper it is shown that eqs. (2) and (3) can lead to different Staudinger indexes (difference up to 30%). Huggins' constant k can vary from one equation to the other by as much as 300%. The experimental test of theoretical relationships between [η], k, and other molecular constants can lead to errors of the same magnitude. Values of [η] and k in pure and mixed theta solvents are discussed. It is moreover shown that eq. (2) is an inadequate approximation of eq. (3). Therefore eq. (3) is the only one which should be used.
Stress relaxation studies of chemically crosslinked gelatin films
Authors: Jopling D. W.
Published: April 2003

Stress relaxation, carried out in 85 : 15 methyl alcohol–water mixture at 60°C., of gelatin films crosslinked with oxystarch or difluorodinitrobenzene may be represented by the sum of three exponential rates of stress decay. Fresh formaldehyde‐crosslinked films relax rapidly and only require two such terms. The second term is shown to be due to the breaking of crosslinks. All excepting 10% of the broken crosslinks do not re‐form in unstressed positions as the formaldehyde is easily able to diffuse out of the layer. This 10% is suggested as being due to crosslinks involving a histidine residue. A large percentage of the broken oxystarch crosslinks do re‐form because the oxystarch is not easily able to diffuse out of the layer.
Polymerization of 1‐methylene‐4‐vinylcyclohexane by a cyclic polymerization mechanism,
Authors: Butler George B. , Miles Marion L. , Brey Wallace S.
Published: April 2003

1‐Methylene‐4‐vinylcyclohexane was prepared by the following reaction sequence: (1) conversion of 4‐methylene‐cyclohexane methanol to the tosylate, (2) oxidation of the tosylate to 4‐methylenecyclohexane carboaldehyde by the method of Kornblum, and (3) reaction of the aldehyde with the ylide from triphenylmethylphosphonium bromide in a Wittig reaction to produce the diene. Polymerization of 1‐methylene‐4‐vinylcyclohexane was attempted with the use of free radical, anionic, cationic, and Ziegler‐type initiators. Polymers were obtained from the cationic (boron trifluoride) and Ziegler (titanium tetrachloride and triethylaluminum complex)‐initiated reactions. The polymer obtained by polymerization of this monomer with gaseous boron trifluoride as the initiator led to a solid polymer which was soluble in a number of organic solvents and had a softening temperature of 150°C. The infrared spectrum of this polymer gave absorption bands for terminal unsaturation. NMR analysis indicated that the unsaturation ratio was one double bond per two monomer units. The NMR analysis also indicated that this unsaturation was due to vinyl rather than methylene groups. Polymerization of this monomer by use of a Ziegler catalyst (titanium tetrachloride and triethylaluminum) led to a solid polymer of which 10% was soluble in a number of organic solvents. Although the infrared spectrum of this polymer indicated the presence of some terminal unsaturation, an NMR analysis indicated only an extremely small amount of residual unsaturation. The essential absence of unsaturation in this linear polymer supports an intramolecular interaction in this monomer, since Ziegler‐type initiators do not ordinarily initiate polymerization of the isobutylene type. These results can be interpreted as additional evidence for the nonbonded interaction concept as a driving force to cyclic polymer.
Properties of semicrystalline polyolefins. III. Plasticization and crystallization phenomena in sterically hindered polyolefins
Authors: Kirshenbaum I. , Isaacson R. B. , Feist W. C.
Published: April 2003

Increasing crystallinity and spherulite growth in rigid polymers can lead to increased resistance to deformation. Crystallization is facilitated by plasticization which, by increasing chain or segmental mobility, may promote both nucleation and the rate of crystal growth. Evidence points to the latter effect of increased rate of crystal growth being the more important when the plasticization is effected via sequential copolymerization techniques. In a number of copolymer systems, the increased extent of crystal growth more than compensates for the plasticization effects on molecular mobility and as a result, the “copolymers” show higher crystalline melting points, higher heat distortion temperatures, and increased modulus.
Field strength dependence of the electric birefringence of potassium polystyrenesulfonate solutions
Authors: Nakayama Haruo , Yoshioka Koshiro
Published: April 2003

The electric birefringence of potassium polystyrenesulfonate (KPSS) in water and dioxane–water mixtures is proportional to the square of the field strength for limiting low fields. Saturation of the birefringence is observed at higher field strength. This effect is the more pronounced, the lower the polyelectrolyte concentration. The specific Kerr constant decreases with increasing polyelectrolyte concentration and with increasing dioxane content. On the other hand, the electric birefringence of KPSS in glycerol–water and ethylene glycol–water mixtures is related to the field strength E by the equation, Δn/c = KEn, where c is the polyelectrolyte concentration, and K and n are constants. The exponent n changes from 1.05 to 1.70 in the range of the concentration studied (1.71 × 10−4−1.01 × 10−3 g./cm.3) in 50.9% glycerol–water. The deviation from the Kerr law is the more marked, the larger the fraction of glycerol. Alternatively the two‐term equation, Δn/c = AE + BE2, reproduces the data fairly well. The coefficient A decreases with increasing polyelectrolyte concentration in 50.9% glycerol–water, whereas B initially increases, reaches a maximum, and then decreases. The appearance of the first‐power term can not be explained by any existing theories of electric birefringence.
Coordinated polymerization of the bicyclo‐[2.2.1]‐heptene‐2 ring system (norbornene) in polar media
Authors: Michelotti Francis W. , Keaveney William P.
Published: April 2003

Norbornene and a derivative have been polymerized to high molecular weight materials by use of the hydrated trichlorides of ruthenium, osmium, and iridium in alcoholic solvents. Structural studies on these polymers indicate that a major portion of the polymer repeating unit consists of cyclopentane rings linked in cis‐1,3 configuration with a predominance of trans double bonds.
Some low molecular weight polymers of d‐limonene and related terpenes obtained by Ziegler‐type catalysts
Authors: Modena Mario , Bates R. B. , Marvel C. S.
Published: April 2003

d‐Limonene has been polymerized by use of Ziegler‐type catalysts to give a low molecular weight polymer which is identical in structure with those prepared by cationic initiation. The evidence indicates that the polymer has more than one type of recurring unit, at least one of which is bicyclic. α‐ and β‐pinene have also been polymerized by these catalysts. Data on optical activity and NMR spectra for all of the polymers are reported.
Unperturbed dimensions of polystyrene derivatives
Authors: Kuwahara Nobuhiro , Ogino Kazuyoshi , Kasai Akira , Ueno Susumu , Kaneko Motozo
Published: April 2003

Several methods have been developed for estimating the unperturbed dimensions of polymer chains without measurements under theta conditions. Osmotic pressure and viscosity measurements have been performed to test the applicability of the methods of estimating the unperturbed dimensions. It has been observed that the Kurata‐Stockmayer and Stockmayer‐Fixman methods are applicable to poly‐p‐methylstyrene and poly‐p‐chlorostyrene in nonpolar and polar solvents. The effect of halogenation at the para position to internal rotation has been given by a comparison of the unperturbed dimensions for poly‐p‐methylstyrene and poly‐p‐chlorostyrene.
Solvent effects in anionic copolymerization
Authors: O'driscoll Kenneth , Patsiga Robert
Published: April 2003

The monomer pair styrene–p‐methylstyrene has been anionically copolymerized in the presence of benzene and tetrahydrofuran. The results of these copolymerizations lead to the proposal of a comprehensive mechanism which is consistent with these and other known facts of anionic propagation in both vinyl and diene polymerizations. The essence of the proposed mechanism is that solvent or monomer can complex the positive counterion. Another monomer can then add to the complex or, in the case of the monomer‐complexed counterion, a rearrangement can occur which incorporates the complexed monomer into the chain as the last unit.
Spherulitic crystallization. Part I. “odd‐even” polyamides: Nylon 56 and nylon 96
Authors: Magill J. H.
Published: April 2003

Nylon 56 and nylon 96 polymers have been shown to crystallize in a number of spherulitic forms which are primarily dependent on the crystallization temperature. A variety of structural types have been reconciled within a general pattern of spherulitic crystallization behavior peculiar to “odd‐even” polyamides. Spherulite growth rates and spherulite morphology presented for most of these structures follow a consistent pattern. Crystalline platelets exhibiting single‐crystal properties have been grown from the melts of these polymers. The morphology of these platelets and spherulites is discussed in relation to the “transition stage” between single crystals and spherulites.
Branching in poly(butadiene‐co‐styrene). I. Branching determined by viscometry and ultracentrifugation
Authors: Blachford J. , Robertson R. F.
Published: April 2003

A sample of poly(butadiene‐co‐styrene), SBR, was divided into twelve fractions by precipitation from a dilute benzene solution. The intrinsic viscosities [η] and weights of all the fractions were measured, and the sedimentation coefficients s0 were determined for the nine fractions of highest molecular weight. From the values of [η] and s0 the number of crosslinks per molecule m, was calculated for each fraction. The results indicated that only the four fractions of highest molecular weight contained crosslinked molecules. The number of crosslinks per weight‐average primary (prior to crosslinking) molecule for the entire sample, δ0, was obtained from the weights of the fractions and the values of m. By use of various theories, values of δ0 of 0.78, 0.56, and 0.38 were obtained. From the values obtained for [η] and s0 and the pycnometric partial specific volume of the polymer in benzene, the molecular weights M of the nine fractions of highest [η] were calculated. The molecular weights of the remaining fractions were calculated from the relation between M and [η] obtained by others. A molecular weight distribution curve was established and used to obtain δ0 ≤ 0.36.
Kinetics of styrene polymerization catalyzed by rhenium pentachloride
Authors: Kamachi Mikiharu , Miyama Hajime
Published: April 2003

Polystyrene of high molecular weight was obtained in a good yield by the polymerization of styrene catalyzed by rhenium pentachloride in benzene or benzene—ethylene dichloride solution. The mechanism of this polymerization reaction was studied by kinetic and spectroscopic measurements. Experimental results were well explained by assuming that a π‐complex between rhenium pentachloride and monomer initiates the cationic polymerization in the case of benzene solution and that +CH2CH2Cl initiates the cationic polymerization in the presence of ethylene dichloride.