bluuebunny/crossref_metadata_2025_split huggingface dataset:
Results of osmotic and of Donnan equilibria measurements in polymethacrylic acid–sodium bromide solutions. Part II
Authors: Alexandrowicz Z. 
Published: April 2003

AbstractThe osmotic and Donnan equilibria were measured in solutions of polymethacrylic acid in the presence of sodium bromide. The primary aim of these measurements was to apply a previously proposed thermodynamical interpretation of the experimental data. The Donnan distribution was determined by titration of the bromide, and was used to calculate the activity coefficient of the salt (in the presence of PMA). The osmotic equilibrium was determined by the previously described osmotic concentration method, and served to evaluate the osmotic coefficient of the solvent. The measurements were carried out at several degrees of ionization in solutions in which the concentration of both solutes was varied a thousandfold. The graphical differentiation of the above coefficients and the use of certain thermodynamical relations led to the calculation of the partial derivatives of the activity coefficients of the polyelectrolyte itself. The results obtained for the activity coefficients of salt, solvent, and polyelectrolyte could be described by equations of a very simple form, dependent only of the composition of the solution and on the experimentally determined osmotic coefficients of the pure solutions of the polyelectrolyte (i.e., with no salt added). These equations permit an unamiguous calculation of the activity of the various components in a salt‐containing polyelectrolyte solution of any given composition. Furthermore, their simple form should facilitate the theoretical interpretation of the properties of polyelectrolytes.
Heat of fusion of polyvinyl fluoride and its interaction with diluents
Authors: Sapper David I. 
Published: April 2003

AbstractBy employing a simple light‐scattering technique to obtain a higher order Tyndall spectrum in mixtures of polyvinyl fluoride with dimethyl sulfoxide, γ‐butyrolactone, and N‐methylpyrrolidone, melting point data were readily obtained. From these data the heat of fusion per crystalline unit of polymer was found to be about 1800 cal., and the entropy of fusion per unit per bond, 1.9 cal./deg. Of the solvents investigated, N‐methylpyrrolidone and dimethyl sulfoxide exhibited the most interaction with the polymer as indicated by interaction energy densities of −9.7 and −4.3 cal./cc., respectively.
Nitrogen‐containing monomers. II. Reactivity ratios of n‐vinyloxazolidone and N‐vinylpyrrolidone with vinyl monomers
Authors: Bork John F. , Coleman L. E. 
Published: April 2003

AbstractThe reactivity ratios in the copolymerization of N‐vinyloxazolidone with styrene, methyl methacrylate, decyl methacrylate, vinyl acetate, and vinyl chloride have been determined and the Alfrey‐Price Q and e values calculated. Reactivity ratios in the copolymerization of N‐vinylpyrrolidone with styrene, methyl methacrylate, and vinyl acetate have also been determined and the Q and e values determined. N‐Vinyloxazolidone was found to be similar but less reactive than N‐vinylpyrrolidone as a comonomer; however, the properties of the resultant copolymers differed appreciably.
A comparison of some physical properties of polyethylene–styrene graft copolymers prepared by the trapped free radical method and polyethylene–polystyrene blends
Authors: Anderson Leigh C. , Roper Don A. , Rieke James K. 
Published: April 2003

AbstractThe preparation and properties of polyethylene–styrene graft copolymers using trapped free radicals produced by gamma rays has been reported. When polystyrene branches are attached to the polyethylene chain there is reinforcement of the properties of polyethylene, whereas the corresponding physical blend of polystyrene and polyethylene has lowered physical properties.
Elution fractionation of crystalline and amorphous polymers
Authors: Kenyon A. S. , Salyer I. O. 
Published: April 2003

AbstractElution fractionation has been applied to crystalline and amorphous polymers. Variables such as the method of polymer deposition, elution rate, and temperature have been studied. Atactic polystyrene can be fractionated successfully by either selective or nonselective deposition of the polymer onto the sand column support. However, only polymers having a sufficiently high diffusion rate can be fractionated by nonselective deposition methods. Other polymers with low diffusion rates, such as polyethylene, must be selectively deposited by precipitating the high molecular species first. The fractionation, in this case, is done during the deposition step. The reliability of the fractionation has been checked by additional measurements on the fractions with light scattering, osmotic pressure, and sedimentation. Reproducibility was checked by repeated fractionation of the same polymer, by a blend of two polymers with previously determined molecular weight distributions, and by comparison of calculated and observed molecular weight distribution curves. Intergral and differential molecular curves have also been compared to theoretical logarithmic distributions with good agreement. The paper describes some of the limitations of the elution method such as high molecular weight, highly branched polyethylenes. The elution fractionation has been shown to be a reliable method for establishing molecular weight distributions.
Two different polymerization mechanisms of acrylonitrile initiated by γ‐irradiation
Authors: Sobue Hiroshi , Tabata Yoneho 
Published: April 2003

AbstractThe polymerization of acrylonitrile induced by ionizing radiation was investigated in bulk in the temperature range 15 to −196°C. It was found from this investigation that two different mechanisms could exist in the polymerization under the same conditions in different temperature regions. The two polymerization phenomena at room and at very low temperatures were studied from the point of view of radical and ionic polymerization mechanisms. It has been well known that the polymerization at room temperature proceeds by radical mechanism. In the solid state polymerization at very low temperatures the following results were obtained: first, the activation energy is very low, i.e., ca. 0.4 kcal./mole; second, an induction period was not observed under various conditions; third, the monomer containing a radical scavenger was easily polymerized. The authors believe that the facts described above indicate that polymerization in the solid state should proceed by an ionic mechanism.
Chain transfer constants of polyethylene glycol and its dodecyl ether in radical polymerization
Authors: Okamura S. , Katagiri K. , Motoyama T. 
Published: April 2003

AbstractChain transfer constants of the end groups (CE) and of the middle portions (CM) of the polymer chain of polyethylene glycol and its dodecyl ether were determined at 60°C. in vinyl acetate polymerization. In the case of polyethylene glycol, CE and CM represent the chain transfer constants of (HOC2H4) and that of (CH2CH2O) which were estimated as 0.004 and 0.0017 respectively, and were compared with the chain transfer constants of propanol and ethanol. The chain transfer constant of the dodecyl radical in polyethylene glycol dodecyl ether is estimated as 0.001, which is in fairly good agreement with that obtained theoretically from the chain transfer constant of the methylene group in acetic esters, but not from that in alcohols. This situation may be attributed to the inhibition of resonance energy transfer by the etherlike oxygen atom.
Phosphines: Chain transfer studies with styrene and methyl methacrylate
Authors: Pellon Joseph 
Published: April 2003

AbstractThe nature of the trivalent phosphorus radical (R2P) was explored through chain transfer studies. The chain transfer constants with styrene and methyl methacrylate were determined at 60°C. for a series of phosphines; namely, the phenyl‐, 2‐cyanoethyl‐, bis(2‐cyanoethyl)‐, and octyl‐compounds. The transfer constants were all greater than one and comparable to those for thiols. The Qtr–etr constants (Alfrey‐Price scheme extended to chain transfer) were calculated and used to discuss structural effects on reactivity. The Qtr–etr parameters for several thiols were also calculated here for the first time and provide additional information concerning their utility. The Qtr–etr values allow the thiols to be compared directly with the phosphines. Comparison indicates that in radical displacements, while both classes are electron acceptors, the phosphines are generally less “electrophilic” than the thiols. The Qtr–etr values for these two important classes of transfer agents permit the transfer constants for these compounds to be calculated with any monomer for which Q–e values are available.
Vinylmercaptobenzothiazole and its polymers
Authors: Kern R. J. 
Published: April 2003

Abstract2‐Vinylmercaptobenzothiazole (VMBT) may be polymerized to a low molecular weight polymer by using an azo catalyst. Conventional peroxide initiators attack the monomer in nonpolymer forming reactions. VMBT copolymerizes with styrene, acrylonitrile, and methyl methacrylate. Reactivity ratios for VMBT/methyl acrylate were determined to be 1.0 and 0.1. Monomer and polymer were compared in reactions involving oxidation, nitration, nitrogen quaternization, and rearrangement of substituents from sulfur to nitrogen.
Nuclear magnetic resonance spectra of some fluorine‐containing polymers
Authors: Naylor R. E. , Lasoski S. W. 
Published: April 2003

AbstractHigh resolution nuclear magnetic resonance spectra have been measured for the F19 resonance in some fluorine‐containing polymers. These data have shown that the F19 resonance frequency depends on the electronegativity of the other substituents on the carbon atom, in a manner similar to that found for small molecules. The resonance frequency also is dependent on substituents attached to adjacent carbons in a way not easily explained by inductive effects. It is hypothesized that these latter shifts may be due to direct potential interaction. The above generalizations, together with other supporting evidence, were utilized to assign a small peak in the spectrum of polyvinylidene fluoride to a head‐to‐head structure. This structure is present to the extent of 8–10%.
The effect of temperature on the equilibrium state of actin solutions
Authors: Asakura Sho , Kasai Michiki , Oosawa Fumio 
Published: April 2003

AbstractThe effect of temperature on the equilibrium level of the G–F transformation of actin was investigated in solutions containing very low concentrations of salts. It is shown by physical methods that the G–F transformation is favored by higher temperatures and the F–G transformation by lower temperatures within the range 0–20°. On the basis of the assumption that the transformation is a reversible condensation, the critical actin concentration was obtained was a function of temperature in a given solvent. Analysis of results by a conventional method gives a positive enthalpy change of the order of 10 kcal./mole actin for the GF transformation. The overall reaction of the GF transformation is postulated as a transition of hydrated G–actin into dehydrated F–actin plus free water, with net increases in enthalpy and entropy. A chemical method is employed for determining G–actin concentration in equilibrium solutions. Almost all actin other than F–actin filaments must be G–actin (ATP‐actin).
Structure of F–actin solutions
Authors: Kasai Michiki , Kawashima Hirotaka , Oosawa Fumio 
Published: April 2003

AbstractFor the purpose of investigating the structure of solutions of muscle protein F–actin and the effect of external force on this structure, simultaneous measurements of rigidity, viscosity, and birefringence were made under rotation and oscillation at very low rates of shear, and as a result a consistent picture of F–actin solutions has been obtained. The F–actin solutions of various concentrations are made by adding a small amount of magnesium ions to a salt‐free G–actin solution. Rigidity, viscosity, and degree of flow birefringence all increase in proportion to the F–actin concentration. Even at very low concentrations, F–actin solutions have a large rigidity. This rigidity is found to be due to a network structure of semiflexible F–actin filaments composed of very many G–actin molecules. The linkage‐to‐linkage length and the flexibility of filaments are estimated from experimental data. Rotation at very low rate of shear causes rigidity and viscosity to decrease rapidly. All results are reasonably explained by assuming that the filaments are elongated and then linkages are detached by shear of rotation. With a decrease in the number of linkages, F–actin filaments are completely oriented. Once attained as a result of shear, the orientation decreases very slowly on standing and gives an anomalous decay curve, probably as a result of setting of the network structure of oriented filaments. At high concentrations of F–actin, a spontaneous orientation occurs. Hysteresis phenomena of F–actin solutions observed under various mechanical treatments are all attributable to formation and detachment of linkages between semiflexible F–actin filaments.
Flow orientation and fracture strength of a model linear hard polymer solid
Authors: Hsiao C. C. 
Published: April 2003

AbstractA mathematical analysis is given to describe the effect of prior large flow orientation on the variation of the fracture strength of a model linear hard polymer solid. For the simple state of uniaxial orientation, the fracture strengths in the direction of orientation and that perpendicular to the direction of orientation are evaluated as functions of the strain change and the strength of the unoriented material. The results indicate an increase of strength in the direction of orientation and a decrease of strength perpendicular to the direction of orientation as the degree of orientation increases.
Measurement of internal stresses by radiofrequency spectroscopy
Authors: Gutowsky H. S. , Bernheim Robert A. , Tarkow Harold 
Published: April 2003

AbstractThe shift with pressure of the Cu63 pure quadrupole resonance frequency in Cu2O has been used to measure the stress developed within a resin due to curing. The method has possibilities for general use in the measurement of internal pressure. It involves the incorporation within a sample of an inert, insulating powder containing nuclei from which a pressure‐sensitive pure quadrupole resonance frequency may be detected. For sample of Epon 828 cured at 80°C for 1½ hr., a stress corresponding to an internal pressure of 2300 ± 400 psi was detected. In addition to the frequency shift of the Cu63 resonance observed in the resin, the absorption was broadened, indicating that a distribution of internal pressures existed.
Polymer NSR spectroscopy. II. The high resolution spectra of methyl methacrylate polymers prepared with free radical and anionic initiators
Authors: Bovey F. A. , Tiers G. V. D. 
Published: April 2003

AbstractSpectra of methyl methacrylate polymers in chloroform solution at 90° show three α‐methyl proton peaks. Measurements of their areas in spectra of polymers prepared with free radical and anionic initiators indicate that these may be attributed to (1) isotactic sequences (ddd or lll), (2) syndiotactic sequences (ldl or dld), and (3) heterotactic sequences (ldd, dll, ddl, or lld). The conformation and stereochemical configuration of the chains may thus be examined with considerable discrimination; degrees of regularity, block sizes, etc. appear to be determinable. Free radical polymers of methyl methacrylate are found to be predominantly syndiotactic, whereas those produced with anionic initiators. such as n‐butyllithium, are shown to be predominantly isotactic, in agreement with the findings of others. The backbone methylene resonance also shows striking changes with chain stereochemical configuration, such as to provide absolute, independent confirmation of the assigned structures.
Thermodiffusion distribution curve of polychloroprene
Authors: Kössler Ivo , Štolka Milan 
Published: April 2003

AbstractThermodiffusion distribution curves of polychloroprene have a characteristic course with two inflection points and are similar to distribution curves obtained by fractional precipitation. By use of an apparatus with a series of sampling holes along a continuous diffusion chamber, more homogeneous fractions were obtained rapidly than by use of the cascade method in a five‐reservoir apparatus. In the fractionation of polychloroprene, a vertical temperature gradient in the apparatus and an additional separation of the fractions of higher molecular weight which is based on the “extraction” of the polymer into the pure solvent aided separations and yielded a better distribution curve. Additional separation can be carried out in the apparatus without taking out the sample if the part the apparatus filled with the solvent has no horizontal temperature gradient in the first hours of the separation process.
Infrared spectra and crystal structures of polyamides
Authors: Miyake Akihisa 
Published: April 2003

AbstractInfrared spectra and x‐ray diffractions of 24 nylons were investigated. The positions of the NH stretching and the amide I bands indicate that the amide groups form hydrogen bonds almost completely, irrespective of the number of CH2 groups. The position of the amide V band has been correlated with the crystal structure. Nylons characterized by a predominant peak at 725 cm.−1 show only one reflection in the x‐ray photograph. Odd‐odd nylons belong to this type (γ form). Even‐odd and odd‐even nylons also take this γ form when prepared from the melt through quenching. When cast from solution, they seem to take a new form. Amino acid nylons with an odd number of CH2 groups have a tendency to take the γ form. Three bands closely related with the position of the amide V band are found.
Stepwise and catalytic polymerization of butadiene by organosodium reagents
Authors: Morton Avery A. , Lanpher Edward J. 
Published: April 2003

AbstractA comparison of the addition of organosodium reagents to 1,1‐diphenylethylene with their polymerization of butadiene helps to distinguish between stepwise and catalytic polymerization. In the best example of the latter, the failure to isolate intermediate steps and the high proportion of 1,4‐unions, (as much as is found in free radical polymerizations) are contrary to the established reaction as described in the literature on the behavior of these reagents. The process is reexamined in the light of present information and ideas. Initiation is the result of bond stretching, which can be far enough to produce radicals. Adsorption on solid surfaces seems to control polymer growth. Details are suggested for all operations in the alfin catalytic process, and a connection with stepwise polymerization is shown.
Polymerization reactions of the acrylate and methacrylate esters of alcohols from jojoba oil
Authors: Marvel C. S. , Paisley David M. , Khattab Ghazi M. A. , Bickford W. G. , Fore Sara P. 
Published: April 2003

AbstractThe acrylic and methacrylic acid esters of the mixed alcohols of jojoba oil have been prepared. These esters polymerize and copolymerize in the pattern of other acrylate and methacrylate esters. All are somewhat soft and show some promise as adhesives. The polymers crosslink and become insoluble on exposure to air.
The polymerization of propylene oxide
Authors: Simons Donald M. , Verbanc John J. 
Published: April 2003

AbstractPolypropylene ether glycol synthesized by the base‐catalyzed polymerization of propylene oxide contains two monofunctional species: one is acetoxyl‐terminated, the other allyl or propenyl ether‐terminated. The presence of ester function is indicated by a sharp absorption peak at 5.75 μ, characteristic of ester carbonyl, in the infrared spectra of the glycols. The ester is readily removed by alkaline hydrolysis. It was identified as an acetoxyl endgroup, arising from anionic attack on vinylidene chloride, a minor impurity in the propylene oxide from which the glycols were prepared. The unsaturated ether functions result from two base‐catalyzed rearrangements. Propylene oxide is converted to allyl alcohol which, in the polymerization system, initiates polyether chains bearing allyl ether groups on one end. Some of these are subsequently rearranged to propenyl ethers in the basic medium. This latter reaction is an equilibrium in which the propenyl ether is the favored specie.
Halobenzenes as sensitizers for the radiation‐induced polymerization of styrene
Authors: Brown Daniel W. , Wall Leo A. 
Published: April 2003

AbstractHalogenated benzenes, carbon tetrachloride, and other compounds have been used to sensitize the gamma‐ray‐induced polymerization of styrene. Benzene and fluorobenzenes are about equally effective, while the data from solutions of mono‐ and dihalogenated benzenes indicate that the order of increasing sensitivity to radiation is: fluorobenzenes < chlorobenzenes < bromobenzenes < iodobenzenes. One halogen is less effective than two, and the ortho isomers are more effective than the meta and para. The relations between the G values for radical production in the solutions and the electron fractions of solvent are linear only for benzene and the monohalogenated aromatics. With very highly halogenated benzenes and carbon tetrachloride, the departure from linearity is very marked. Significant sensitization is observed at very low electron fractions with the highly halogenated materials, except with hexafluorobenzene, which appears to be very stable to radiation. The generalizations concerning the effects of the kind and number of substituents in mono‐ and dihalogenated benzenes are not valid for more highly halogenated benzenes. Much of the curvature observed at high concentrations of carbon tetrachloride is apparently due to changes in the rate constants as the monomer concentration is changed. At low concentrations this is not the case with carbon tetrachloride and presumably also with the other highly halogenated materials. Various reaction mechanisms are considered, and one is advanced that reproduces many of the important features of the observed data.
Nonterminated polymeric anions: The initiation of polymerization of certain polar monomers
Authors: Graham Roger K. , Panchak John R. , Kampf Mary J. 
Published: April 2003

AbstractThe use of nonterminated polymeric anions in tetrahydrofuran solution at low temperatures to initiate the polymerization of a second monomer to form block copolymer has been extended to several polar monomers. Anions of polystyrene and of poly‐(methyl methacrylate) have been shown to initiate the polymerization of alkyl methacrylates, isopropyl acrylate, methacrylonitrile, and acrylonitrile. Isopropyl acrylate when initiated with sodium naphthalene under similar conditions gives some nonterminated polymeric anions, but nonpolymeric or low‐polymeric initiator is also present. The criteria for order of addition of monomers and proof of block copolymer formation are discussed.
Isophasic transitions in polytrifluorochloroethylene
Authors: Baccaredda M. , Butta E. 
Published: April 2003

AbstractThrough determination of dynamic mechanical properties (sound velocity and damping factor) over the temperature range from −160 to 200°C. and frequency range from 4 to 16 kcycles/sec. evidence is found for the existence of two isophasic transition temperatures in polytrifluorochloroethylene: one at −58°C. and the other at 50°C. Both transitions are associated with motion in the main chain of the polymer, which is first excited at −58°C. for the molecular segments which are more freely rotating (because they are located near network defects) and at 50°C. for the majority of the chain elements in the amorphous regions. The transition point at −58°C. is regarded as the glass transition temperature for polytrifluorochloroethylene. The experimental results are discussed on the basis of the structure of the polymer examined, and a comparison is made between dynamic mechanical data and data obtained by measurements of specific volume, nuclear magnetic resonance, and dielectric losses.