bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular interpretation of glass temperature depression by plasticizers
Authors: Dimarzio Edmund A. , Gibbs Julian H. 
Published: April 2003

AbstractThe view that the glass transition is basically thermodynamic in nature is used to derive an expression for glass temperature depression by plasticizers. The second‐order transition temperature is given as that temperature at which the configurational entropy first becomes zero as we cool the polymer–diluent system. The concentration of plasticizer, size of the plasticizing molecule, and its flexibility are found to be the main determinants of glass temperature depression. Available experimental data confirm the predictions of the theory, and it is thereby concluded that the thermodynamic view is sufficient to explain glass temperature depression. It is pointed out that data exist which contradict the free volume theory, as applied to glass temperature depression.
Dynamic shear behavior of poly(γ‐benzyl L‐glutamate), poly(D,L‐propylene oxide), and poly(ethyl vinyl ether)
Authors: Saba R. G. , Sauer J. A. , Woodward A. E. 
Published: April 2003

AbstractThe dynamic mechanical properties in shear have been studied for poly(γ‐benzyl‐L‐glutamate), poly(D,L‐propylene oxide), and poly(ethyl vinyl ether) in the 95–100° to 240–340°K. region by use of a torsional pendulum in free decay at frequencies of 0.05–1 cycles/sec. Poly (γ‐benzyl L‐glutamate) exhibits a prominent loss maximum at 288°K. (0.18 cycles/sec.) attributed to reorientational motions principally of the side chains. For poly(D,L‐propylene oxide) two loss peaks are found at ∼120°K. (0.59 cycles/sec.) and 211°K. (0.37 cycle/sec.), being attributed to motion in the amorphous regions of a small (3–4) and large number of segments, respectively. In the case of poly(ethyl vinyl ether) the principal dispersion region is found at ≳230°K., while a secondary loss maximum is located at ∼100°K. This behavior is similar to that reported for polypentene‐1 and polybutene‐1, except that the two motional processes are shifted to lower temperatures.
Thermodynamic properties of rodlike polyelectrolyte solutions in the presence of salts
Authors: Oosawa Fumio 
Published: April 2003

AbstractA theoretical foundation is given to the experimentally established relation called the additivity law, according to which the thermodynamic and transference properties of linear polyelectrolyte solutions with low molecular salts are described as a superposition of the effects of ions from polyelectrolytes and those from low molecular salts. By employing a cylindrical free volume model for a solution of thin and long rodlike polyelectrolytes and analyzing the Poisson‐Boltzmann equation it is found that the electrostatic free energy is expressed in a special form as a function of the geometry of the system. On the basis of this expression of the free energy, the additivity law is derived by a thermodynamic treatment without an approximate procedure to solve the Poisson‐Boltzmann equation. The additivity is a property not accidental but essential to rodlike polyelectrolytes. The same method is applicable to analysis of the interaction between two parallel rodlike polyions in the presence of low molecular salts.
Stereoregularity in polyvinyl alcohols and esters
Authors: Cooper W. , Johnston F. R. , Vaughan G. 
Published: April 2003

AbstractFrom solution properties and x‐ray crystallinities of polyvinyl esters and alcohols derived from several vinyl esters polymerized at different temperatures, it is considered that polyvinyl haloacetates are more regular in structure than polyvinyl acetate, but this regularity has not been proved to result from increased syndiotacticity. It has been found that the crystallinities of polyvinyl trifluoroacetates prepared from vinyl‐acetate via polyvinyl alcohols are comparable with those prepared directly from vinyl trifluoroacetate at similar polymerization temperatures. The x‐ray diffraction patterns of polyvinyl acetate prepared from the monomer and of acetylated polyvinyl alcohol obtained by hydrolysis of polyvinyl trifluoroacetate are identical. Likewise, those of polyvinyl alcohols derived from several different vinyl esters cannot be distinguished from one another. Polyvinyl acetates prepared at high and low temperatures and prepared from the trifluoroacetate all hydrolyze in alkaline solution at substantially the same rate. The significant finding in this investigation is that whereas polymerization temperature has a marked effect on the crystallinity of polyvinyl trifluoroacetate, it has little influence on the water solubility of the polyvinyl alcohols. Water solubility is determined by the structure of the monomer from which the polyvinyl alcohol was obtained.
Polybenzimidazoles. II
Authors: Vogel Herward , Marvel C. S. 
Published: April 2003

AbstractA polybenzimidazole has been prepared from 3,3′‐diaminobenzidine and phthalic anhydride which has a high molecular weight and very good heat stability. Replacement of the hydrogen atoms on the nitrogen of the imidazole nuclei in a polybenzimidazole does not improve the heat stability as indicated by the properties of poly‐2,6‐(m‐phenylene)‐3,5‐diphenyldiimidazobenzene. Polybenzimidazoles with aliphatic units have been prepared from 3,3′‐diaminobenzidine and the diphenyl ester of succinic and glutaric acids. The diphenyl esters of oxalic and malonic acids did not yield polymers presumably because cyclic amides were formed. Further hydrolytic stability tests on polybenzimidazoles have been reported. Some model compounds have been prepared for comparison of their melting points and absorption spectra with those of the corresponding polymer.
Reaction of polymeric radicals with organometallic compounds
Authors: Huff T. , Perry Eli 
Published: April 2003

AbstractThe reactivities of polystyryl, polymethyl methacrylyl and polyacrylonitryl radicals with thirteen organometallic substrates were measured and correlated at 60°C. The organometallics chosen were saturated, aliphatic derivatives of elements from Groups 2b, 3a, 4a, and 5a of the Periodic Table. Correlation was accomplished by the method proposed by Bamford, Jenkins, and Johnston. The correlation based on the above three monomers allowed the prediction of the chain transfer constant C of four of the tested substrates with an untested radical, the polymethyl acrylyl, with an accuracy of better than 101. Since the correlation was based on absolute values of C which covered the range of 106 and which were accurate to within 100.8, it was concluded that the correlation was a valid one and was useful for predictive purposes. Values of C for untested substrates can be predicted with only a low order of accuracy because data are not available on the polarizability of most compounds. The introduction of oxygen into the vicinity of the metal–carbon bond reduces the values of C drastically and confirms that C is very sensitive to polar factors. There appears to be a correlation between β (the polarizability of the substrate) and β (the intrinsic reactivity of the substrate) within a given group of the Periodic Table. The fact that there is not a general correlation between α and α for the whole Periodic Table suggests that the mechanism of the transfer reaction is different from group to group.
Apparatus for measuring the dynamic tensile modulus of thin polymeric films
Authors: Hansen Orin C. , Fabry Thomas L. , Marker Leon , Sweeting Orville J. 
Published: April 2003

AbstractA method and apparatus have been developed specifically for the determination of the dynamic tensile modulus of thin polymeric films. A weight is attached to a 2 × 60‐mm. strip of film, the upper end of which is clamped to a phonograph recording head. The recording head is used to set the system into either longitudinal or transverse vibration. The cross‐sectional area of the film is determined in place from the length, the density, and the transverse resonant frequency (the Vibroscope principle). The modulus is found from the dimensions of the specimen and the longitudinal resonant frequency. The apparatus has been used to study the moduli of a series of polymeric packaging films, the dependence of the modulus of polyethylene film on the angle between the long axis of the specimen and the machine direction, the gage dependence of the stiffness of polyolefin films, and the relationship between the modulus and the moisture and glycerol contents of cellophane.
High frequency titrations of polydicarboxylic acid copolymers: Polyitaconic acid‐Co‐styrene and polymaleic acid‐Co‐styrene
Authors: Drougas J. , Timnick A. , Guile R. L. 
Published: April 2003

AbstractA useful method, more rapid and more accurate than elemental analysis, has been developed to determine the composition of copolymers of itaconic anhydride and maleic anhydride with styrene. The method involves a high frequency titration of the sample. The method can also be used to detect traces of acidic impurities in polymers and in the identification of mixtures of similar acidic copolymers. Titration indicates that the acid segments in the copolymers of itaconic acid–styrene, maleic acid–styrene, and the homopolymer polyitaconic acid act as dibasic acids. The method appears to have a sensitivity that permits identification and approximate resolution of two carboxylate species in the same polymer.
Radiation degradation of polymethacrylates. Dose rate and medium effects
Authors: Shultz A. R. , Roth P. I. , Berge J. M. 
Published: April 2003

Abstractγ‐Irradiations of polymethyl methacrylate (PMMA) powders confirm observations in literature that air retards the radiation‐induced molecular weight lowering of this polymer. The energy absorptions per scission Ed are 91 e.v. in air at 0.117 Mreps/hr., 76 e.v. in air at 0.70 Mrep/hr., and 56 e.v. in vacuum at 0.117 Mrep/hr. γ‐Radiation degradation of PMMA solutions (5 gm. PMMA/100 ml. solvent) in butanone and in ethyl acetate gave apparent energies per scission of 63 e.v. and 26–30 e.v., respectively. The latter low value is not understood. Poly‐n‐butyl methacrylate (PNBMA) displays considerable sensitivity to air and dose‐rate effects during γ‐irradiation. Apparent energy absorptions per main‐chain scission observed for γ‐irradiated PNBMA powder are: Ed = 454 e.v. in air at 0.117 Mrep/hr. and Ed = 226 e.v. in vacuum at 0.117 Mrep/hr. The latter value is far above the Ed (146 e.v.) observed for electron‐irradiated PNBMA film. To decrease possible chain recombination and/or polymer–polymer crosslinking reactions degrassed solutions of 4.5, 10.0, and 55 wt.‐% PNBMA in ethyl acetate were γ‐irradiated. Apparent Ed values of 74 e.v., 74 e. v., and 226 e. v., respectively were found. Thus, the more dilute solutions give PNBMA scission energies near that of bulk PMMA. The 55 wt.‐% PNBMA solution gives a scission energy indistinguishable from that of bulk PNBMA under the same irradiation conditions. Competitive crosslinking and main‐chain scission are postulated for electron‐irradiated poly‐n‐alkyl methacrylates. The energy per main‐chain scission is assumed constant for all the homologes. The ratio of crosslinked units to chain scissions, α/β, is then found to increase linearly with (n−1), where n is the number of carbon atoms in n‐alkyl groups of the side chain. This scheme yields a consistent explanation of the radiation response of the lower members of the poly‐n‐alkyl methacrylate homologous series. A comparison of light‐scattering Mw and solution viscosity (Mw)v molecular weight changes did not reveal the concurrent crosslinking in PNBMA films undergoing chain scission by 1 m.e.v.‐peak electron irradiation. Some inquiry is made into the theoretical sensitivity of this comparison method.
Degradation of a polycarbonate by ionizing radiation
Authors: Golden J. H. , Hazell E. A. 
Published: April 2003

AbstractThe degradation of a polycarbonate by electron irradiation in oxygen and in vacuum has been examined. It was found that the polymer undergoes chain scission and that crosslinking apparently did not occur, the molecular weights of irradiated specimens were therefore determined from the intrinsic viscosity of methylene chloride solutions. From the relationship of molecular weight to radiation dose the value ofG(scissions per 100 e.v. of energy absorbed) was found to be 0.14 in oxygen and 0.09 in vacuum. The effect of both molecular weight and radiation dose on the mechanical properties of polycarbonate irradiated in vacuum was studied. Conventional tensile properties were examined, and fracture energies were also obtained by use of a tensile impact apparatus based on the flywheel principle which was used to strain the speciments at 340 in./sec. With increase in radiation dose the maximum yield strength and extension fall slowly at first and then rapidly at a dose of approximately 100 Mrad. The elastic modulus is, however, virtually unaffected by irradiation and the attendant changes in molecular weight. The fracture energy falls steadily with radiation dose, and from the results a linear relationship,F= 0.0044Mv− 59, between fracture energyFand molecular weightMvhas been obtained over the range examined, the energy, becoming immeasurably small at molecular weight below 13,500. The results suggested that in this case fracture energy was a better measure of residual strength after irradiation than other tensile properties. The chemical changes caused by radiation lead to greatly enhanced ultraviolet light absorption with a maximum at 305 mμ and a shoulder at 320 mμ. The absorption (E; 1%, 1 cm.), in oxygen and in vacuum was shown to be a linear function,E= 0.020R+ 0.32 of the radiation doseR. The changes in the infrared spectrum, in particular the carbonyl absorption, of irradiated specimens have been discussed. Mass spectrographic measurements showed that degradation proceeded with evolution of H2, CO, and CO2, both in oxygen and in vacuum.
Thermodynamic properties of polymethyl methacrylate and methyl methacrylate
Authors: Warfield R. W. , Petree M. C. 
Published: April 2003

AbstractFrom published data the entropy, enthalpy, and Gibbs free energy of polymethyl methacrylate (PMMA) have been calculated over the temperature range 0–260°K. These functions have also been calculated for methyl methacrylate over the range 0–210°K. The entropy of polymerization at 210°K. was found to be 9.63 cal./mole°K. and the free energy of polymerization was found to be −11.8 kcal./mole. The thermodynamic function Cp/T versus T as calculated for PMMA exhibits a maximum at 70–100°K. The number of classically vibrating units per repeating unit of PMMA at 260°K. is 6.38, and the difference Cp–Cv is found to be 0.014 cal./g.°K.
Diffusion of benzene in polyacrylates
Authors: Kishimoto A. , Enda Y. 
Published: April 2003

AbstractAn investigation has been made of the sorption and permeation of benzene vapor in polymethyl acrylate and polyethyl acrylate over relatively wide ranges of temperature and concentration. The mutual diffusion coefficients were estimated from the rates of absorption and desorption, and the steady‐state permeability. The diffusion coefficients determined by the different methods agreed within experimental error, suggesting that the sorption processes for these systems are controlled by truly Fickian diffusion mechanism. By using the equations of Frisch, the time lags for permeation have been calculated as a function of concentration from the diffusion coefficient data, and compared with the observed values. The calculated values agreed with the observed ones, indicating that the nonstationary state of permeation is controlled by a purely Fickian diffusion mechanism. Experimental data for the thermodynamic diffusion coefficients DT of benzene in PMA and PEA have been analyzed in terms of a simple free volume theory previously developed. It is found that, in all cases examined, the derived relation fits well experimental data. Three temperature‐dependent parameters involved in the theory are evaluated, and their variation with temperature are discussed.
Growth and morphology of single crystals of cellulose triacetate
Authors: Manley R. St. John 
Published: April 2003

AbstractSingle crystals of cellulose triacetate were prepared by supercooling dilute solutions in mixtures of nitromethane and n‐butanol. The crystals are approximately square in shape and thicken by spiral growths centered on screw dislocations. The chain molecules are perpendicular to the lamellae which are about 180 A. thick. In spite of their stiffness the molecules appear to assume folded configurations in the lamellae. Various morphological features of the crystals are described and discussed.
The temperature dependence of magnesium chloride interaction with polyacrylic acid
Authors: Jacobson Ada L. 
Published: April 2003

AbstractThe effect of temperature on a modified pH “titration” of polyacrylic acid is reported. The extent of acid ionization was varied by pretitration to various degrees with the strong base of a weak counterion binder, tetra‐n‐propyl ammonium hydroxide. The effect of subsequent additions of magnesium chloride to these pretitrated solutions at 15, 25, and 38°C. is reported. The release of hydrogen ions caused by this neutral salt addition varied with both degree of pretitration and temperature. The displacement caused by temperature on the maxima and minima behavior of hydrogen ions released as a function of degree of preionization can be explained by the effects of temperature on polymer configuration. The increased release of hydrogen ions at higher temperature can be explained by the combined effects of temperature on the polymer configuration and on the binding equilibria. The acid dissociation constants at 15, 25, and 38°C. have been obtained by titration with tetra‐n‐propyl ammonium hydroxide.
Theory of the modulus of crystalline polymers
Authors: Nielsen Lawrence E. , Stockton Fred D. 
Published: April 2003

AbstractA new theory for the elastic modulus of crystalline polymers has been developed for temperatures above the glass transition. The theory is based upon the assumption that crystallites behave as crosslinks and as a rigid filler. The shear modulus G is given by G = (dRT/M̄c)F, where F is a factor giving the relative increase in modulus due to the volume of the rigid crystallites. The number‐average molecular weight M̄c of the amorphous sequences is calculated as a function of degree of crystallinity from copolymer theory. The theoretical values of the modulus as a function of degree of crystallinity agree reasonably well with experimental values over a wide range.
Changes in the stereospecificity of a ziegler catalyst used in the polymerization of butadiene
Authors: McIntosh Charles R. , Stephens William D. , Taylor Curtis O. 
Published: April 2003

AbstractAs a part of a program involving synthesis of various rubbers, the stereospecific polymerization of butadiene was studied. A Ziegler catalyst composed of cobaltous chloride, triethyl aluminum and aluminum chloride in benzene was used. The effect of catalyst age on stereospecificity of the polymers produced was observed over a period of nearly two years. Freshly prepared catalyst appears as a straw‐yellow liquid over black insoluble solids. Within a few weeks a black separate liquid phase begins to form at the bottom of the catalyst. The amount of the dark lower layer increases on standing until all of the solids have been dissolved. Polymers prepared from the upper layer of catalyst showed decreasing percentages of cis‐double bonds, an effect which was linear up to approximately one year. From one to two years, the upper layer produced polymers which were essentially constant at 70% cis‐olefinic bonds. In contrast, the dark lower layer of catalyst yielded polymers which were high in cis‐content (greater than 95% cis‐bonds) over the entire period of the study.
Nucleating effect on the kinetics of crystallization and the spherulites of nylon 6
Authors: Inoue Masakazu 
Published: April 2003

AbstractThe kinetics of isothermal crystallization and morphology of spherulites of nylon 6 nucleated by additives were discussed. Nylon 66, polyethylene terephthalate, and some inorganic phosphor compounds were used as nucleating agents. At crystallization temperatures in the range of 205 to 180°C., crystallization occurs through one‐ or two‐ dimensional growth and heterogeneous nucleation. The rate of crystallization increases by adding nucleating agents, followed by the decrease of the induction period of crystallization. Maximum crystallinity was not always obtained by the additives used for the present study. By adding nucleating agents, the size of spherulites decreases and the distribution becomes homogeneous, independent of the crystallization temperature.
A thermodynamic study of viton elastomer
Authors: Roe Ryong‐Joon , Krigbaum William R. 
Published: April 2003

AbstractThe temperature coefficients of the retractive force at successive fixed lengths were measured for a Viton fluoroelastomer sample. At each elongation the sample was held for at least 40 hr. before the tension measurement in order to minimize the relaxation effect. The range of elongations covered was confined to α values smaller than 1.65 because of the limited tensile strength of the sample. The results show departures from the predictions of simple gaussian theory of rubber elasticity in two respects. First, the tension f at 45°C. follows the Mooney equation with nonvanishing C2 values (2C1 = 3.324 kg./cm.2 and 2C2 = 2.865 kg./cm.2). Secondly, the internal energy makes a negative contribution to the elastic force, and moreover the ratio of the internal energy component to the total tension fe/f decreases with increasing α. The thermodynamic behavior of the Viton sample is thus qualitatively similar to that observed previously with a natural rubber network, except that the internal energy makes positive contribution in the latter. The experimental results were also compared with recent theories which purport to improve upon the simple Gaussian theory of rubber elasticity, but it is found that none of them can explain the results in satisfactory detail.
Preparation and aromatization of poly‐1,3‐cyclohexadiene. II
Authors: Frey D. A. , Hasegawa Masaki , Marvel C. S. 
Published: April 2003

AbstractFurther work on the polymerization of 1,3‐cyclohexadiene by the action of Zieglertype catalysis and by cationic initiation has been carried out and polymers with an inherent viscosity of 0.1–0.19 have been obtained consistently. Dehydrogenation of the poly‐1,3‐cyclohexadiene by halogenation followed by pyrolysis has given good conversion to a polyphenyl which has some units which are incompletely aromatized. This polymer has very good heat stability but is not a useful polymer for plastic purposes.
Preparation and polymerization of vinyl 12‐hydroxystearate
Authors: Shono Toshiyuki , Marvel C. S. 
Published: April 2003

AbstractVinyl 12‐hydroxystearate was prepared from 12‐hydroxystearic acid by vinyl interchange procedure with vinyl acetate. In the reaction, no products having a free hydroxyl group were obtained. The main addition product had the 1‐alkoxyethyl acetate structure. Vinyl 12‐hydroxystearate was obtained by the treatment of this addition product with acid washed activated alumina in ether solution. Vinyl 12‐hydroxystearate polymerized in an emulsion system at a pH of 7–8.5 with standard free radical initiation to give a colorless solid polymer (softening range was 71–75°C.). Vinyl 12‐hydroxystearate was copolymerized with vinyl acetate, vinyl stearate and vinyl chloride and the copolymers thus obtained have been characterized.