bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gelation in addition polymerization
Authors: Simpson W. , Holt T. 
Published: April 2003

AbstractRecent investigations have shown that cyclization or intramolecular crosslinking plays a major part in the polymerization of diallyl phthalate, and an extension of the network theory of gelation to allow for this led to satisfactory agreement between actual and predicted degrees of conversion at gelation for this monomer. It became important, therefore, to find whether satisfactory agreement could be obtained for other systems, and a detailed examination of the polymerization of the diallyl esters of isophthalic, terephthalic, oxalic, and sebacic acids has now been made. In all of these cases gelation occurs at a conversion higher than the predicted value, the discrepancy being considerably greater than can be accounted for by experimental error. Complicating factors in the interpretation of the experimental results are shown to be absent and it is concluded that cyclization in the poly(diallyl esters) does not affect gelation in the manner expected from theory, and that the satisfactory correlation in the case of diallyl phthalate is fortuitous. It is shown, in the case of the isomeric phthalates which are considered strictly comparable, that all three systems gel at the same degree of conversion, although the ortho ester polymer has considerably fewer pendent allyl groups available for crosslinking and is also of a lower chain length than the other two polymers. This fact seems irreconcilable with the network theory of the gel point as it exists at present. The results are discussed in relation to Walling's diffusion control theory, and although the constancy of conversion at gelation is consistent with the predictions of this theory, supporting evidence regarding molecular complexity is lacking.
Sedimentation and electrophoresis of porous spheres
Authors: Hermans J. J. 
Published: April 2003

AbstractAn approximate method is developed to calculate the velocity of a polymer molecule in a centrifugal and in an electric field. The model used is a porous sphere. The hydrodynamic interaction between the polymer segments is described by means of Oseen's equations. It is assumed that the force acting on the liquid has spherical symmetry and that the flow derived from this force may be replaced by its average over a spherical surface. The results of the calculation show that this approximation is legitimate. For the sedimentation velocity an equation is obtained which is similar to Debye's though somewhat simpler. In the theory of electrophoresis all relaxation effects are ignored, while for the charge density due to the small ions an expression is used that has been derived on the basis of the Debye‐Hückel approximation for electrolytes. The expression derived for the electrophoretic mobility is quite simple and leads to results almost identical with those obtained in previous work by a straightforward extension of the theories of Brinkman and Debye and Bueche.
A study of secondary scattering
Authors: Kraut J. , Dandliker W. B. 
Published: April 2003

AbstractA quantitative treatment of the influence of secondary scattering on light scattering is presented and experimentally verified. It is shown that secondary scattering accounts for the apparent shortening of the cell dimensions and for the large apparent depolarizations found previously by other workers when using highly turbid solutions as calibration standards. Methods for obtaining the correct calibration constant and depolarization are suggested.
The mode of peroxide‐catalyzed polymerization of vinyltriethoxysilane
Authors: Mixer R. Y. , Bailey D. L. 
Published: April 2003

AbstractIt has been qualitatively demonstrated the vinyltriethoxysilane is polymerized by a free radical process to clear, colorless, viscous liquid polymer of low molecular weight. The low molecular weight is the result of chain transfer with polymer and monomer. This chain transfer involves the abstraction of the alpha‐hydrogen of an ethoxysilyl group (CH3CH2OSi) of either the polymer or the monomer. The ratio of chain transfer with polymer to that with monomer for high conversions is at least 4.5.
Emulsion polymerization of butadiene and styrene in presence of carbon black. I. Persulfate initiation
Authors: Maron S. H. , Von Fischer W. , Ellslager W. M. , Sarvadi G. 
Published: April 2003

AbstractButadiene and butadiene‐styrene have been emulsion polymerized in the presence of carbon black and by use of persulfate initiation. The recipe developed gives 50% conversion of butadiene in about 16 hours, and produces polymers which are superior to conventional ones in processability, ultimate tensile, and elongation. The compounded tensiles are about 1000 p.s.i. higher, while the elongations are higher by 60‐100%. The rates of polymerization at 50°C. are dependent on the type of black used, the type and amount of soap, and the method of preparation of the black dispersion, but they are insensitive to molecular oxygen. However, even the “optimum” persulfate recipe suffers from two serious drawbacks: (1) above 50% conversion the rate of polymerization becomes extremely slow, and (2) the stability of the carbon black in the latex decreases rapidly above conversions of 30%. Even though the precipitated carbon black is easily redispersed by agitation, it is inconvenient to work with latices which are so unstable colloidally. These difficulties could not be circumvented in polymerization systems containing persulfate as the initiator.
The copolymer of 2‐methyl‐3‐n‐butyl‐1,3‐butadiene and styrene
Authors: Marvel C. S. , Nowak Robert M. , Passer Moses , Taft W. K. , Labbe B. G. 
Published: April 2003

AbstractHomopolymers of 2‐methyl‐3‐n‐butyl‐1,3‐butadiene having inherent viscosities of 0.63 to 0.77 have been prepared. These contain 97% of the diene in the 1,4 structure based on perbenzoic acid titration. A compounded and cured 75/25 copolymer of this diene with styrene was found to have very poor properties as an elastomer.
Anomalous relation of apparent viscosity to temperature in high molecular weight polyisobutylene under shear in a capillary viscometer
Authors: Bestul A. B. , Bryant C. B. 
Published: April 2003

AbstractThe apparent viscosities of polyisobutylenes of high molecular weights show extremely high temperature sensitivities in narrow temperature ranges when measured in a capillary viscometer. The temperature at which this anomaly occurs increases as the molecular weight of the polyisobutylene increases. It is higher for a GR‐I rubber than for a polyisobutylene of comparable molecular weight. It decreases with decreasing nominal rate of shear and with increasing radius of the capillary tubes through which the polymer is made to flow at a given average linear velocity. It increases with increasing isotropic pressure on the polymer. This effect is similar to one reported previously for colloidal solutions, and discussed by some investigators as “structure turbulence” occurring at Reynolds' numbers as low as one. It is not caused by crystallization or glass transition. An alternative explanation is that on cooling some relaxation time in the polymer molecules become so long that the molecules cannot orient appreciably in the time they take to pass through the capillaries. The relation between the pertinent relaxation time and the transit time cannot be a simple numerical proportion however.
A compact osmometer
Authors: Yanko John A. 
Published: April 2003

AbstractA small compact stainless steel osmometer is described that is inexpensive, easy to construct, employs a small quantity of solution, and is capable of producing accurate osmotic pressure data. The capillary tube units are attached to the osmometer by means of leaded threads that give leakproof seals which are reusable. Membrane preparation and osmotic pressure measurements are described. A typical osmotic pressure experiment is illustrated by measurements on dimethyl formamide solutions of a copolymer of vinylidene cyanide/vinyl acetate. The copolymer yielded a number‐average molecular weight of 134,000 and a μ1 value of 0.35 in DMF at 25.00°C.
A solid state polymerization initiated by high‐energy electrons
Authors: Lawton E. J. , Grubb W. T. , Balwit J. S. 
Published: April 2003

AbstractHexamethylcyclotrisiloxane monomer polymerizes when exposed to high‐energy electrons. The greatest yield of polymer occurs when the monomer is irradiated in the solid state. Above the crystal melting temperature, the yield of polymer is almost zero for equal irradiation. The polymer obtained is crosslinked. This is unlike the polymerization of acrylamide in which there is extensive polymerization both in the solid and in the liquid state by high‐energy electrons.
The sorption of water by rubber
Authors: Tester D. A. 
Published: April 2003

AbstractAn equation is derived from the consideration of an osmotic mechanism of absorption to represent the absorption–time relationship for a vulcanized rubber immersed in water. The dependence of absorption equilibrium on the relative humidity is also expressed quantitatively. These theoretical relationships are tested for a vulcanized crepe immersed in water and in salt solutions of various concentrations. Good agreement between experiment and theory is obtained for absorption in the absence of air. Divergence from an equilibrium type absorption–time curve in the case in which air is present is shown to be due to aging of the rubber, brought about by oxygen dissolved in the absorbed water. Accelerated aging is shown to be responsible for the marked increase in the rate of absorption brought about by an elevation of temperature, the effect being slight in the absence of air.
Emulsion polymerization of chloroprene. I. Mechanism
Authors: Morton Maurice , Cala J. A. , Altier Mary W. 
Published: April 2003

AbstractThe mechanism of emulsion polymerization of chloroprene has been found to differ considerably from that of other monomers such as styrene or butadiene, apparently due to its exceptional reactivity. Whereas the formation of polymer particles from monomers of low water solubility usually depends largely on the solubilizing effect of detergent micelles, this is not the case for chloroprene. It has been found that dissolved chloroprene and the chloroprene‐water interface may both be active loci for the initiation of polymer particles, depending upon the conditions of the polymerization reaction. It has also been found that chloroprene does not obey the “ideal” kinetics as proposed by the Smith‐Ewart theory, since the rate of particle is not independent of the type and amount of initiator present. Possible reasons for this deviation are suggested.
Copolymerization of trialkyl aconitates with butadiene and some vinyl monomers
Authors: Marvel C. S. , Johnson John W. , Economy James , Scott George P. , Taft W. K. , Labbe B. G. 
Published: April 2003

AbstractReactivity ratios have been determined for the copolymerization of trimethyl aconitate with butadiene, styrene, acrylonitrile, and vinyl chloride, and for triethyl aconitate with butadiene and styrene. The values obtained indicate that trialkyl aconitates are very reactive in free radical initiated copolymerizations. No copolymerizations of aconitic acid were realized. A copolymer of butadiene and trimethyl aconitate has been prepared in a modified Mutual recipe at 50°C. The copolymer shows fair oil resistance and tensile properties but the low‐temperature properties are poor. The temperature rise of trimethyl aconitate copolymer is possibly better than that of standard GR‐S made at 50°C.
Some experiments on sulfur as inhibitor for the polymerization of styrene
Authors: Bartlett Paul D. , Trifan Daniel S. 
Published: April 2003

AbstractThe rate of thermal polymerization of styrene in the presence of sulfur has been followed viscometrically and dilatometrically and the product has been examined as to its molecular weight, content of total and mercury‐extractable sulfur, and its effect on the polymerization of fresh styrene.Polymer isolated during the inhibition period by methanol precipitation contains close to eight atoms of sulfur per molecule of polymer, and these sulfur atoms are so located that complete desulforization by Raney nickel reduces the molecular weight of the polymer by not more than a factor of 2–3. The number of sulfur atoms per molecule decreases during the progress of the polymerization. The polysulfides formed at first are inhibitors, as in the case of vinyl acetate polymerization. As the size of the polysulfide units and the inhibitory power decrease, the activity of the polysulfides as chain transfer agents persists and there appears a mild initiatory reaction such that the eventual rate of polymerization is almost twice the normal thermal rate. This acceleration can be produced by adding the precipitated polymer from a sulfur‐inhibited polymerization to fresh styrene.Judged by the composition of the methanol‐insoluble polymer, the inhibitory constant (kt/kp) of sulfur for styrene is of the order of 52. During the first 24 hours of a sulfurinhibited polymerization at 80–89° sulfur molecules were consumed 22 times as fast as the presumed rate of thermal initiation of pairs of polymerization chains. One‐third of this sulfur was in polymer of too high molecular weight to be the result of diradical initiation intercepted by sulfur. The mechanisms involved are discussed.
Nuclear magnetic resonance absorption in polymethyl methacrylate and polymethyl α‐chloroacrylate
Authors: Powles J. G. 
Published: April 2003

AbstractNuclear magnetic resonance absorption measurements on polymethyl methacrylate and polymethyl α‐chloroacrylate in the temperature range −196 to 200°C. are reported. An interpretation of the results is given and a fairly complete correlation is found between the results of the present measurements and the known dielectric and mechanical properties of the materials. The main reduction in line width, in polymethyl methacrylate above 70°C., occurs in two stages corresponding to the two dielectric and mechanical absorption regions, the so‐called α and β processes. The results are not inconsistent with the identification of the β process with motion of the carbomethoxy group and of the α process with chain motion. The results on polymethyl α‐chloroacrylate are unsatisfactory in the low temperature region. Anomalous behavior in the region of −100°C. may be due to a hitherto unnoticed solid state transition. The main line narrowing above 100°C. is correlated satisfactorily with the dielectric and mechanical properties of the material but the α and β processes then fall so close together that rather less detailed information is obtained than with polymethyl methacrylate. A comparison of the behavior of polymethyl methacrylate and polymethyl α‐chloroacrylate provide an interesting example of the way in which nuclear resonance measurements are valuable in the interpretation of the behavior of polymer materials.
Effect of drawing on the infrared dichroism of nylon 66 filaments
Authors: Caroti Gino , Dusenbury Joseph H. 
Published: April 2003

AbstractInfrared absorption measurements in the 3‐micron region, using polarized radiation, have been made for a series of nylon 66 filaments, ranging in draw ratio from one (undrawn) to four. From consideration of the dichroic ratios obtained, it is suggested that there is a random arrangement of nylon 66 polymer chains at draw ratio one, with these chains becoming increasingly aligned with respect to the filament axis as the drawing increases. The method used to prepare a filament for infrared examination is particularly important, since it has been found that improper preparative procedures may induce orientation in a filament. This effect of specimen preparation is greatest at draw ratio one and becomes less important at higher draw ratios. The results of x‐ray diffraction studies carried out on the same series of filaments are consistent with the infrared findings.
An osmometer with an ideal semipermeable boundary
Authors: Pals D. T. F. , Staverman A. J. 
Published: April 2003

AbstractAn osmometer has been constructed in which the only possible transition from one cell to the other is through the vapor phase. In this way the problem of passage of solute is completely eliminated. In order to obtain a sufficient rate of transition of solvent, the distance between the cells has been made as small as possible. An osmometer with a vapor “membrane” of 0.05 mm. thickness is described and measurements with this osmometer are reported.
Fiber formation from concentrated polymer solutions and the possible origin of long‐range periodicity in synthetic fibers
Authors: Nishijima Yasunori , Oster Gerald 
Published: April 2003

AbstractA theory of fiber formation from concentrated polymer solutions is presented which is based on the overlap of polymer molecules. The extent of overlapping is estimated from our diffusion measurements (J. Polymer Sci., 19, 337 (1956)). Above a certain concentration, which is lower the greater the size of the individual molecules, the polymer molecules lose their identity and the solution becomes a continuous network. Under these conditions the solution is spinnable and the structure of the network is independent of the molecular weight but depends on the flexibility of the chains. Calculations show that the drawn‐out network which forms the fiber has long‐range periodicity (100–500 A.) and is in agreement with the order of magnitude observed in smallangle x‐ray diffraction of synthetic fibers.
Light scattering by linear macromolecules oriented in laminar flow. II. Determination of the main gyration radii
Authors: Peterlin Anton 
Published: April 2003

AbstractIn laminar flow, polymer molecules are deformed and oriented. The effect is generally observed by investigating the resulting streaming birefringence. From the measurement of the magnitude of the effect, not only the optical anisotropy of the monomer unit, and its dependence on the solvent, but also the uncoiling of the linear macromolecule in the flow can be determined. From the extinction angle, information about the size and flexibility of the coil can be obtained. Since evaluation of the experimental data depends on the special model and on the statistics of the chain elements, an independent check is highly desireble. Light scattering yields such additional information on the size and shape of the deformed macromolecule, information which is less influenced by the special assumptions of the individual models. The pertinent scattering functions are calculated for the freely draining Gaussian coil and for the optically isotropic monomer unit, which in turn allows the determination of molecular parameters i.e., of the main gyration radii from the measurement of the angular dependence of the scattered light.
Effect of x‐rays and γ‐rays on synthetic polymers in aqueous solution
Authors: Alexander Peter , Charlesby Arthur 
Published: April 2003

AbstractA study has been made of the effect of ionizing radiation (x‐ and γ‐rays) on aqueous solution of the following vinyl polymers: polymethacrylic acid, polyacrylic acid, polyacrylamide, polystyrene sulfonate, polyvinylpyrrolidone, and polyvinyl alcohol. In dilute solutions (<0.3% for the samples of polymer used) all the polymers are degraded by main chain fracture although in some cases dissolved oxygen has to be present. In others, degradation occurs in carefully deoxygenated solution but is increased by the presence of oxygen. The breakdown of polystyrene sulfonate is independent of oxygen. At higher concentration, crosslinking becomes the dominant action for all the polymers studied with the exception of polymethacrylic acid and ionized polyacrylic acid, which degrade at all concentrations. The dose of radiation necessary to produce a gel has been studied as a function of concentration and passes through a minimum. No gel formation occurs below a minimum polymer concentration of about 0.4%. The results cannot be explained on the basis that indirect action by the free radicals formed in the water leads to degradation while direct energy uptake by the polymer itself produces crosslinking. Other possible mechanisms are examined. The manner by which added substances reduce the effectiveness of irradiation (i.e., protect) is discussed briefly.
Mean square length and mean square radius of gyration of 1,4′‐polysaccharides and of polybutadienes
Authors: Eliezer I. , Hayman H. J. G. 
Published: April 2003

AbstractThe mean square length and mean square radius of gyration of 1,4′‐polysaccharides and of cis‐ and trans‐polybutadiene were calculated by an extension of the method of Eyring and Benoit, the results being expressed in terms of the degree of polymerization and of certain parameters of physical significance connected with the rotations about the various single bonds in these molecules. The calculations were based on the simplifying assumptions that no correlation exists between rotations about bonds separated by at least one pyranose ring or double bond and that the polysaccharide molecules are made up of pyranose rings in the “chair” form. The excluded volume effect was neglected throughout. The results obtained show that, if the mean square length is plotted against the degree of polymerization, n, then the deviations for small n from the limiting straight line obtained for larger n will have the form of a damped vibration, n appearing instead of the time. In certain cases, however, the results for odd and even n fall on different curves.
Light scattering of polyphosphates of high molecular weight
Authors: Saini Guido , Trossarelli Luigi 
Published: April 2003

AbstractThis paper reports light scattering and viscosity data concerning a fraction of lithium polyphosphate of high molecular weight (1.0 × 106) dissolved in LiCl solutions whose concentration varied from 0.025 to 0.4 M. The lithium polyphosphate was obtained by adding a cation exchanger (Dowex 50, lithium form) to an aqueous suspension of insoluble potassium Kurrol's salt. The higher fraction of the dissolved product was then precipitated by adding an alcoholic solution of LiCl. The root mean square end‐to‐end distance of the polyelectrolyte molecule, (r2), as obtained from the angular dependence of the scattered light, is as much greater as the ionic strength lowers. The Fox‐Flory relation can be applied in the above range of ionic strength. The second virial coefficient becomes zero at a ionic strength of about 0.4, and the ratio (r/M)1/2 = 1.24 × 10−8cm. shows that the molecule has a low flexibility. The dependence of the expansion coefficients and of the second virial coefficients on ionic strength is discussed, use being made of the theories concerning polyelectrolyte behavior.
Hydrolysis and optical rotation of cellulose, starch, and cycloglucans
Authors: Freudenberg K. 
Published: April 2003

AbstractUnder the title “Contributions to the Chemistry of High Molecular Natural Substances” (J. Polymer Sci., 16, 155 (1955)) a short survey of the author's work on cellulose, starch, catechintannins, and lignin is given. The present paper gives a detailed derivation of the kinetic and preparative evidence for the structure of cellulose, starch, and the Schardinger dextrins (cycloglucans).