bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inorganic polymers. Part I. A solid inorganic foam
Authors: Shaw R. A. , Ogawa Takeshi 
Published: April 2003

AbstractThe preparation of a solid inorganic foam is reported. Hexaaminocyclotriphosphazatriene, N3P3(NH2)6, used either without purification, or when recrystallized from water, gives phospham as a dense powder. If, however, the starting material is precipitated from its aqueous solution by suitable organic solvents, a foamed material results. Possible reasons for this divergence in behavior are discussed. The ammonia evolved on thermal decomposition acts as a built‐in foaming agent.
Polymerization studies on methyl and ethyl α‐fluoromethylacrylate
Authors: Powell John A. , Graham Roger K. 
Published: April 2003

AbstractEthyl α‐fluoromethylacrylate was prepared from ethyl α‐chloromethylacrylate by reaction with potassium fluoride in sulfolane. The methyl ester was prepared by transesterification. The ethyl ester was found to be unexpectedly quite toxic. Homopolymers and copolymers of both monomers were found to have lower softening temperatures than polymers from the corresponding methacrylate monomers. Reactivity ratios were determined for ethyl α‐fluoromethylacrylate (M2) with styrene (r1= 0.34,r2= 0.09) and with methylmethacrylate (r1= 1.05,r2= 0.51).
Structural investigation of polyacrolein by fractional dehydration
Authors: Hunter L. , Forbes J. W. 
Published: April 2003

AbstractThe utilization of a specially developed technique for the low temperature pyrolysis of polyacrolein, and the accurate measurement of the waterr eleased thereby from the polymer have demonstrated the presence of well‐defined inflection points in the curve of water evolution versus dehydration (pyrolysis) temperature. These are postulated to indicate the presence of water in polyacrolein from a number of different sources, e.g., structural, hydrogen‐bonded, and free. A correlation of the measured water evolution between inflection point temperatures with the concurrently developing free carbonyl groups, measured by an infrared technique, has provided information on the type and proportion of various structural subunits in the polyacrolein molecule. This information has been used to construct a partial structural formula for the particular polyacrolein sample under examination. As a practical outgrowth of this work, the concept of the activation of polyacrolein by dehydration at elevated temperatures has proved useful in facilitating reaction of the polymer with a number of carbonyl reagents such as sodium bisulfite, SO2, etc.
Kinetics of polyacrylamide adsorption on calcium phosphate
Authors: Jankovics Lawrence 
Published: April 2003

AbstractAn extension of Langmuir's rate equation is obtained for polymeric adsorption when the initial concentrations of polymers differ significantly from the final or equilibrium concentrations. It is assumed that the equation developed has a general applicability for polymer adsorption whenever the experimentally determined equilibrium adsorption data can be represented by Langmuir's isotherm. Adsorption of high molecular weight polyacrylamides from aqueous solutions upon calcium phosphate is described at low concentration of the polymer. The rate of adsorption obeys a Langmuirian type equation.
Excluded volume effects in swollen polymeric networks
Authors: Rijke A. M. 
Published: April 2003

AbstractInformation on the parameters of polymeric networks obtained by crosslinking in solution can be provided by deswelling measurements in polymer solutions of different concentration. However, under these conditions, the existing theories describing the swelling behavior are conflicting and no definite conclusion on the network properties seems as yet justifiable. Moreover, excluded volume and chain connectivity effects are not accounted for in either of the theories. Thirdly, the effect of the presence of crosslinkis and the number of connected polymer segments in the network on the value of the Huggins' interaction parameter to be used in the expressions for the free energy of mixing is not clear. Nevertheless, the available experimental data have shown some preference for Hermans' theory over Flory's theory, whereas James and Guth's expression must be rejected altogether. A dependence of the degree of swelling q0, at which the partial molar free energy of elasticity equals zero, on solvent power of the swelling agent has been previously observed and has been further investigated in this study. To this end, methyl methacrylate was copolymerized with small amounts of divinylbenzene in dilute benzene solutions yielding six samples with different crosslink densities and q0 values. A large dependence of q0 on the osmotic second virial coefficient in four solvents was observed. The applicability of current theories for polymer–solvent interaction upon intramolecular chain dimensions to the chains in the networks has been investigated. Flory's expression for volume expansion of polymer chains falls short, but two other relations for the same initial effect show that the second virial coefficient dependence of q0 may be attributed to volume exclusion, similarly as in free chains. The validity of these relations, however, is expected to hold only for a rather limited range of the network parameters.
Polymers from ortho aromatic tetraamines and aromatic dianhydrides
Authors: Dawans F. , Marvel C. S. 
Published: April 2003

AbstractAromatic heteropolymers were synthesized from aromatic tetraamines and dianhydrides; some of the polymers had a ladder‐type structure. The properties and thermal stability of the polymer were studied. The experimental conditions yielding the imidazolone structure were determined on model compounds. Polymers containing mixed aromatic units in the chain were prepared from pyromellitic anhydride or 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride, and 3,3′‐diaminobenzidine, 3,3′,4,4′‐tetraaminodiphenyl ether, 1,4,5,8‐tetraaminonaphthalene, or 1,2,4,5‐tetraaminobenzene. The polycondensations were carried out in melt and in solution (in melted phenol, pyridine, dimethylacetamide, 116% polyphosphoric acid). The inherent viscosities of a number of polymers synthesized by melt condensation were in the range of approximately 0.2–0.7; the higher polymers were obtained by carrying out the polycondensations in solution in 116% polyphosphoric acid; in this case, the intrinsic viscosities ranged from 1.1 to 1.8. Most of the polymers do not melt at 350°C. and are soluble in the usual organic solvents, but the ladder‐type structure polymers were soluble only in concentrated sulfuric acid.
Interaction between alkaline earth metal cations and poly(methacrylic acid) in dilute solutions. I. Viscometric and conductometric titrations
Authors: Wojtczak Zbigniew 
Published: April 2003

AbstractThe viscometric and conductometric behavior of poly(methacrylic acid) in dilute aqueous solutions over the whole range of neutralization with barium, strontium, and calcium hydroxides were studied. The results show minima in reduced viscosity and specific conductance near degrees of neutralization of 0.2 and 1.0. These minima do not appear with neutralization with monovalent bases and are more closely related to the higher degree of association of polyanions with divalent counterions than with monovalent ions. From the fractional charge of polyanions we may conclude that about 90% of the divalent counterions are associated with polyanions in almost the whole range of neutralization. The results show the specific influence of strontium cations on the behavior of PMA solutions.
High energy electron irradiation of trihydroperfluoroalkyl acrylate monomers: Statistical evaluation of factor interdependency
Authors: Degering Ed. F. , Caldarella Gerald J. , Haines George H. 
Published: April 2003

AbstractA 2,2,2,2‐factorial design was used for the irradiation‐induced polymerization of 1,1,3‐trihydroperfluoropropyl and 1,1,7‐trihydroperfluoroheptyl acrylates with a 2‐M.e.v. electron accelerator in order to more critically determine the effect of variables. From the data obtained, it is concluded that: (1) degassing, flame‐out, and time‐lapse are significant, dependent main effects for both monomers, and atmosphere is a significant, dependent main effect for the heptyl ester, (2) the atmosphere and flame‐out, degassing and time‐lapse, and flame‐out and time‐lapse interactions are independently significant for the propyl ester, whereas for the heptyl ester the atmosphere and flame‐out is independently significant, but degassing and flame‐out, degassing and time‐lapse, and flameout and time‐lapse are dependently significant, (3) the degassing, flame‐out and time‐lapse interaction is independently significant for the heptyl ester, and (4) experimental variables may be significantly interdependent.
Polycarbonate to polyether conversions
Authors: Stueben K. C. 
Published: April 2003

AbstractThe preparation of aromatic polycarbonates via the base‐catalyzed disproportionation of suitable alkyl‐aryl carbonates (AlkylOCOOArylOCOOAlkyl) was found to be accompanied by the formation of alkyl‐aryl ethers. Substitution of a poly(alkyl aryl carbonate) in place of the monomeric species resulted in the formation of a poly(alkyl aryl ether). Thus, it was possible to convert a copolymer of ethylene glycol and 2,2‐bis(4‐hydroxyphenyl)propane to the corresponding poly(alkyl aryl ether) with only slight loss of molecular weight. The structure of this polyether and a partially converted poly(carbonate ether) were established by analytical and degradative techniques. Conversions of other poly(alkyl aryl carbonates) were also achieved but with less success because of competing reactions. A possible mechanism for these conversions is presented.
Study of the orientation of light‐sensitive tetrazonium salt in poly(vinyl alcohol)
Authors: Tsunoda Takahiro , Yamaoka Tsuguo 
Published: April 2003

Abstractv(NN) band of the diazo or tetrazonium salt, derived from p‐methoxyaniline, p‐hydroxyaniline, benzidine, or o‐dianisidine shows perpendicular dicroism in the stretched poly(vinyl alcohol) film. This means that these salts are directing their longer axes perpendicularly to the direction of the stretching. However, that of the diazonium salt from p‐aminodiphenyl or o‐anisidine shows no dichroism. From the above facts, it is concluded that the interactions between the polar groups of poly(vinyl alcohol) and those on the both ends of the diazo or tetrazonium salt such as diazo, methoxy, and hydroxy group result in the perpendicular orientation of the diazo or tetrazonium molecule.
Crosslinking of dialdehyde starches with wheat proteins
Authors: Chatterji Arun K. , Arnold Lionel K. 
Published: April 2003

AbstractA quantitative and degradative study on the gluten–dialdehyde starch reaction product is made, and the possible reaction mechanisms during the degradation reactions are discussed rigorously. The structure of the gluten–DAS reaction product is arrived at by designating a generic protein structure for gluten. This study has produced new evidence regarding crosslinking sites of dialdehyde starches when they react with proteins in general.
Interactions in binary polymer systems
Authors: Williamson G. R. , Wright B. 
Published: April 2003

AbstractDilute solution viscosity measurements have been made on eleven ternary polymer systems (two polymers, one solvent). Calculation of the polymer‐polymer interaction coefficient between unlike polymer molecules by the Krigbaum and Wall treatment is not generally applicable. The empirical relationship derived by Catsiff and Hewitt has been used, and the interaction between polymers in these systems has been qualitatively interpreted on this basis.
Fracture properties of carboxylic rubbers
Authors: Halpin J. C. , Bueche F. 
Published: April 2003

AbstractRupture properties of sulfur and zinc oxide vulcanizates of a carboxylic rubber have been experimentally determined. When the logarithm of the strength at break is plotted against the logarithm of the strain at break, failure envelopes are obtained for the two vulcanizates which diverge at long times or high temperatures. As a consequence of this experimental fact it is apparent that, while there exists a failure envelope which uniquely describes a given viscoelastic system, there is no general shape of the failure envelope representative of all the rupture properties of an elastomer through all degrees of vulcanization. It is shown that the molecular fracture theory of Bueche and Halpin provides a quantitative basis for the analysis of the strength properties of elastomers through a wide range of vulcanizate quality, provided the specific character of the network structure is taken into account. It is suggested that the so‐called “unique” strength properties of metal oxide vulcanizates are in reality a natural reflection of a sparse network crosslinkage concentration.
Note on the calculation of molecular weight averages of polymers from fractionation data
Authors: Bohdanecký M. , Kratochvíl P. , Šolc K. 
Published: April 2003

AbstractIt has been shown that in calculating Mw, Mn, and Mv values of a nonfractionated polymer from the weights and molecular weights of fractions, corresponding averages for the individual fractions should be used. In calculating higher averages (Mz and Mz+1), the values of lower averages are also required. An analysis of errors which appear on neglecting these requirements, has been given.
Crystallite orientation in regenerated cellulose filaments. III. Crystallite orientation in viscose monofilaments
Authors: Warwicker J. O. , Ellis K. C. 
Published: April 2003

AbstractThree sets of regenerated cellulose monofilaments have been prepared from viscose. Two were stretched while still in the xanthate form and the third was stretched after regeneration to cellulose. X‐ray orientation measurements were taken around the 101 equatorial arc of x‐ray orientation measurements were taken around the 101 equatorial arc of x‐ray diagrams of filaments with different degrees of stretch. By plotting the orientation parameter, defined as the reciprocal of the angle at half the maximum intensity, against stretch, it was found that those filaments in which strong intermolecular bonding forces existed during the application of stretch reacted differently from those in which these forces were small. The presence of a well‐developed system of intermolecular bonds during stretch is found to prevent the attainment of the maximum theoretical orientation with high stretching forces. The Kratky rodlet theory is found to fit the results, and good fits are obtained for the theoretical intensity‐distribution curves predicted from it and those found experimentally. The Hermans x‐ray orientation factor fx was calculated from theoretical distribution curves, and the results plotted against stretch confirm those obtained from the orientation parameter.
Studies in cyclocopolymerization. II. Relative rates of addition in the copolymerization of acrylonitrile with certain 1,4‐dienes
Authors: Butler George B. , Kasat Radhakrishna B. 
Published: April 2003

AbstractThe copolymerizations of 3,3‐dimethyl‐1,4‐pentadiene with acrylonitrile (system A) and divinyl sulfone with acrylonitrile (system B) were carried out, azobisisobutyronitrile being used as the initiator. The polymers obtained were soluble in dimethylformamide in every case. The infrared spectra of the polymers indicate there was little unsaturation. This evidence supports the theory of intra–intermolecular polymerization. The reactivity ratio parameters were determined for the above systems. For system A, r1 ≃ rc ≃ 0, r2 = 3.31. For system B, r1 = 0.364, r2 = 1.94, and rc = 0.067. These results further support the general copolymer composition equation derived by Barton, Butler, and Chapin. The intrinsic viscosities of the copolymers of divinyl sulfone with acrylonitrile indicate that divinyl sulfone acts as a chain transfer agent.
Polydisperse polymers with random trifunctional branching. II. Weight‐averaging of chosen molecular size‐dependent functions and a restatement of the approximate distribution function
Authors: Berger H. L. , Shultz A. R. 
Published: April 2003

AbstractThe product gzbZa is weight‐averaged over the distribution of molecular species in a polydisperse polymer possessing randomly distributed trifunctional branch points. This permits comparison between branched and nonbranched polydisperse polymers of certain physical properties that depend upon the relative degree of polymerization, z, and upon the ratio of branched to nonbranched molecule mean‐square radii, g = Rbr2/Rl2. Values of a, b, and γ (a branching index) are chosen for specific physical reasons and the computed ratios,
\documentclass{article}\pagestyle{empty}\begin{document}$ (1 - \gamma )^a \int_0^\infty {g_z ^b z^a } W_z dz/\int_0^\infty {z^{a + 1} e^{ - z} dz} $\end{document}
are tabulated. The distribution function for the polydisperse polymer possessing randomly distributed trifunctional branch points is restated in terms of a modified Bessel function of the first kind. This form is of use since properties of the Bessel function are known and the tabulated values of this function are generally available.
Proton magnetic resonance of poly(ethyl acrylate), poly(butyl acrylate), poly(ethyl vinyl ether), poly(vinyl propionate), poly(vinyl stearate), and vinyl stearate from 77°K
Authors: Merrill L. J. , Sauer J. A. , Woodward A. E. 
Published: April 2003

AbstractMolecular motion in one monomeric and five polymeric materials was investigated by means of broad line nuclear magnetic resonance (NMR) measurements, the widths and second moments of the resonant absorption lines being obtained at temperatures from 77 to 280–340°K. The materials investigated were: poly(ethyl vinyl ether), poly(ethyl acrylate), poly(vinyl propionate), poly(butyl acrylate), vinyl stearate, and poly(vinyl stearate).
Application of thermogravimetric techniques to reaction kinetics
Authors: Chatterjee Pronoy K. 
Published: April 2003

AbstractAn easier technique for the determination of reaction constants such as order, energy of activation, and frequency factor from the thermogravimetric data has been described. The method requires two TGA curves obtained with different sample weights under similar reaction conditions. Applicability of the method to complex reactions, where simultaneous decomposition occurs, has been discussed. Reaction constants for different steps of the decomposition of calcium oxalate monohydrate are evaluated.
Isomorphism phenomena in systems containing fluorinated polymers and in new fluorinated copolymers
Authors: Natta G. , Allegra G. , Bassi I. W. , Sianesi D. , Caporiccio G. , Torti E. 
Published: April 2003

AbstractHigh molecular weight vinyl fluoride (VF)–vinylidene fluoride (VF2) and vinyl fluoride (VF)–tetrafluoroethylene (TFE) copolymers in a wide range of compositions have been synthesized at low pressure at 25°C. with the aid of a catalytic system consisting of triisobutyl boron activated with molecular oxygen. With the same catalytic system, highly crystalline homopolymers of VF and VF2, melting above the usually reported temperatures, have been obtained. The x‐ray and thermal analyses of crystalline molecular mixtures of PVF and PVF2, as well as of VF–VF2 copolymers, have shown that in both cases the monomeric units of the two types may be present in the same crystallites, giving rise to a phenomenon very similar to the isomorphism in the case of low molecular weight substances; an analogous phenomenon was already described by some of us1 for other polymeric systems. In the actual case we have observed the isomorphism between the VF and VF2 monomeric units in all the range of compositions, both for the homopolymer mixtures and for the copolymers. The VF–TFE copolymer samples, in the range of compositions examined (0–75% in TFE) show a crystal structure essentially similar to that of PVF. Due to the fact that the crystal structure of PVF is not strictly analogous to that of PVFE, in the compositions containing 75–100% TFE units a phenomenon of isodimorphism, or isopolymorphism, probably takes place. Over a wide range of compositions of the monomeric reactant mixture, a marked tendency for formation of alternating (...ABAB...)sequences within the copolymer chains has been observed.
Polybenzoylenebenzimidazoles
Authors: Colson J. G. , Michel R. H. , Paufler R. M. 
Published: April 2003

AbstractA polyamide amino acid was prepared by the solution condensation of 3,3′‐diaminobenzidine and pyromellitic dianhydride. This polymer was cast as a film and converted to a polybenzoylenebenzimidazole. The gross conversion path was elucidated by spectroscopy and was substantiated by model compound studies. A novel ladder polymer was prepared from 1,2,4,5‐tetraaminobenzene and pyromellitic dianhydride.
Effect of metal salts on polymerization. Part I. Polymerization of vinylpyridine initiated with cupric acetate
Authors: Tazuke Shigeo , Okamura Seizo 
Published: April 2003

AbstractThe polymerization of vinylpyridine initiated by cupric acetate has been studied. The rate of polymerization was greatly affected by the nature of the solvent. In general polar solvents increased the rate of polymerization. Polymerization was particularly rapid in water, acetone, and methanol. The initial rate of polymerization of 4‐vinylpyridine (4‐VP) in a methanol–pyridine mixture at 50°C. is Rp = 6.95 × 10−6[Cu11]1/2 [4‐VP]2 l./mole‐sec. The activation energy of initiation by cupric acetate is 5.4 ± 1.6 kcal./mole. Polymerization of 2‐vinylpyridine and 2‐methyl‐5‐vinylpyridine with the same initiator was much slower than that of 4‐VP. Dependence of Rp on monomer structure and solvent is discussed. Kinetic and spectroscopic studies led to the conclusion that the polymerization of 4‐VP is initiated by one electron transfer from the monomer to cupric acetate in a complex having the structure, (4‐VP)2Cu(CH3COO)2.
Gel permeation chromatography. III. Molecular shape versus elution
Authors: Hendrickson J. G. , Moore J. C. 
Published: April 2003

AbstractRules were evolved to predict elution of linear, branched, and polar compounds in GPC, based on testing of 130 compounds. With these rules and in tetrahydrofuran solvent, data for all but a few compounds correlated onto a single calibration line. With small molecules, elution often changed, due to hydrogen bonding to the solvent; this occurred with alcohols, acids, and some chlorinated compounds, but not with mercaptans. Branched and linear isomers usually eluted at about the same point. One may conclude that structural elements were additive in their effect on elution volume in this study.
Precise molecular weight distributions of high polymers by semiautomatic solvent extraction
Authors: Harrington Rodney E. , Pecoraro P. Garth 
Published: April 2003

AbstractIt has been found practical to fractionate relatively monodisperse polystyrenes of molecular weights up to 4 × 106 by using a semiautomatic solvent extraction procedure. The fractionators consist of flow‐through mixing chambers provided with settling regions for the removal of finely suspended solid material. Provision is made for accurate control of both temperature and solvent–nonsolvent ratio. Two such apparatus, operated in tandem, were used in the present work; in principle, several more stages could be employed if desired for most polymer systems. Results on polystyrenes prepared in well defined ways appear to be in good agreement with predicted distributions. Applicability to other polymer systems is discussed.