bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of the mechanism of synthesis of protein molecules
Authors: Goto Seichu 
Published: April 2003

AbstractGlutamic acid undergoes cyclization to form 2‐pyrrolidone‐5‐carboxylic acid as an intermediate cyclic monomer in some mechanisms of the synthesis of protein molecules. Two molecules of leucine undergo cyclization to form a dioxopiperazine derivative useful as an intermediate, closed ring dimer for some high protein copolymerization reactions. Leucyl‐leucine has also been cyclized by heating to obtain a similar six‐membered ring dimer as an intermediate. Glutamic acid (1 mole) with leucyl‐leucine (1 mole) react in the same way to form leucyl‐leucyl glutamate without cyclization. Glutamic acid (1 mole) with leucine (2 moles) interact to make α,β‐dileucyl‐glutamate as an intermediate useful for some high protein copolymerization reactions. These intermediates and almost all amino acids will copolymerize to form higher polymers by the method used in this fundamental research investigation.
Etching of polyethylene terephthalate
Authors: Baker William P. 
Published: April 2003

AbstractA degradative etching technique has been employed with polyethylene terephthalate films to demonstrate the existence of several different structures, the size of which vary from hundreds of microns to hundreds of Angstroms. The micron‐sized structures are a function of the processing and orientation of the film and occur in regular geometric patterns. Thus, parallel stretch‐direction lines are etched into one‐way stretched film, the number of lines being dependent upon film history. Etched, two‐way stretched films reveal a lamellate composition, each layer possessing a brick wall‐like structure. This general structural pattern has been found in other types of film by similar methods. Examination of the etched areas by electron microscopy demonstrates that the micron‐sized blocks are composed of spheres, 700 A. in diameter, which are aligned over moderate distances.
The Newtonian melt viscosity of polyethylene: An index of long‐chain branching
Authors: Schreiber H. P. , Bagley E. B. 
Published: April 2003

AbstractThe relationship at 190°C. between Newtonian melt viscosity η0 and the weight‐average molecular weight, M̄w for polyethylenes has been developed by use of melt viscosities obtained from capillary viscometry and molecular weights from intrinsic viscosity and bulk flow measurements in addition to the usual light‐scattering determinations. The same η0 vs. M̄w relationship is obeyed by whole and fractionated linear polyethylenes and also by ethylene–butene and ethylene–propylene copolymers. The Newtonian viscosity therefore seems virtually independent of molecular weight distribution and the influence of short (ethyl, methyl) chain branches. Low density polyethylenes have consistently lower Newtonian melt viscosities at given M̄w than their linear counterparts. At constant M̄w and temperature, therefore, η0 depends primarily on long‐chain branching. A viscosity index of long‐chain branching (v.b.i.) is defined by the ratio of Newtonian viscosities of a linear and a branched polyethylene of the same M̄w. The v.b.i. correlates well with an intrinsic viscosity branching index provided long branch incidence is high. The correlation breaks down otherwise, because the intrinsic viscosity is also sensitive to molecular weight distribution and the presence of short‐chain branches. The v.b.i. is therefore more useful as a long branching index. It is a comparative index, however, and not an absolute evaluation of the number of long branches per molecule. The η0 vs. M̄w relationship of linear polyethylenes does not obey the often reported 3.5 power law for linear polymers, but is well fitted by a 4.2 power factor. The present work indicates the necessity of using polyethylenes which have been stabilized against the effects of thermally induced changes if meaningful values of Newtonian viscosity are to be obtained.
Effect of molecular weight distribution and branching on the viscosity of polyethylene melts
Authors: Busse W. F. , Longworth R. 
Published: April 2003

AbstractThe effects of molecular weight distribution and branching on the viscosity of polyethylene melts were studied by making mixtures of paraffin wax with 0 to 100% of various types of high and low density polyethylenes of known weight‐average molecular weights, M̄w and measuring their Newtonian melt viscosity at 150°C. The range of molecular weights from about 400 to 106 gave about a billionfold range in the viscosities (10−2 to 10+7 poises). The results showed that the melt viscosity did not vary with M̄w3.4, since samples with the same M̄w might differ by up to 100,000‐fold in viscosity. An analysis of the flow process in melts suggested that the viscosity‐average molecular weight M̄v might be more significant than the M̄w. Within the accuracy of our knowledge of the initial molecular weight, the viscosities of all mixtures having viscosities above about 10 poises fit the equation

where w1 and w2 are the weight fractions, and M1 and M2 are the molecular weights of the paraffin and polyethylene, respectively, and M̄v is a viscosity‐average molecular weight of the mixture. Theory and experiment show that the value of α may be obtained without any knowledge of the initial molecular weight, from the slope of the curve for log η0 versus log concentration at small concentrations of wax. Polyethylenes with large amounts of long‐chain branching had low values of α (down to about 0.25), while polymers with relatively little long‐chain branching had values of α up to about 0.8. Where the comparisons could be made, the value of α determined from a polymer melt was surprisingly close (∼ +0.15) to the value of α in the intrinsic viscosity equation for the same polyethylene dissolved in paraffin wax.
Determination of the mechanical properties of high polymers at high speeds of testing
Authors: Richard K. 
Published: April 2003

AbstractThree impact testing devices for different test purposes are described and the measuring, amplifying, and indicating equipment for the plotting of stress–strain curves is shown in diagrammatic form. The problem of evaluating the impact strength of high polymers for specified applications is discussed for the case of diverse semifinished and finished parts. In the case of safety belts for motor vehicles, the difference between plastic and elastic deformation energy for various belt materials is shown. With films, a distinction is made between the amount of energy used in deformation until the first tear and the total impact energy. For sheet specimens subject to tensile stress, the stress‐strain curves for slow and shock stresses are contrasted. Further experiments must show whether, with the help of the new testing equipment, the usability of high polymers for specified applications may also be forecast quantitatively.
Effects of cupric salts on the polymerization of acrylonitrile in aqueous solution
Authors: Watanabe Masamoto , Kiuchi Hiroshi 
Published: April 2003

AbstractThe polymerization of acrylonitrile in aqueous solution initiated by ammonium persulfate in the presence of cupric salts was studied by a dilatometric method. The presence of cupric sulfate, nitrate, or acetate has a pronounced effect on polymerization, leading to an increase in the rate, and both cupric chloride and bromide retard or inhibit polymerization beyond certain salt concentrations. The increased rate is explainable by the following reactions:

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The polymerization of acrylonitrile can be initiated by an oxidizing agent such as cupric sulfate, ferric sulfate, stannic chloride, nitric acid, or periodic acid. The decreased rate can be explained by assuming that the complexes of Cu+ ion with a halide ion X− such as CuX2−, CuX3=, CuX4≡, or Cu2X3− shows lower reactivity in the reaction with S2O8=. The cupric‐terminated reaction depends on the coexisting anion. The effect of sulfate, nitrate, acetate, phosphate, chlorate, or fluoride anions is negligible, while that of the chloride is marked, and that of the bromide is overwhelming. The CuX+(X = Cl, Br) ion appears to terminate polymer chains more efficiently than does Cuaq++. Apparent transfer constants of cupric sulfate in the presence of sodium chloride or bromide and the transfer constant of CuCl+ are given. It is suggested that the possibility of the termination reactions by halogen atom transfer is large under conditions of high halide ion concentration:
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and
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Behavior of primary radicals in vinyl polymerization
Authors: Manabe Tomonobu , Utsumi Tadashi , Okamura Seizo 
Published: April 2003

AbstractThe reciprocal of the viscosity‐average degree of polymerization (P̄v−1) vs. rate of polymerization (V) relation is expressed as:

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where [η] = K′P̄vα, β = ktd/kt, k = rate of primary radical formation out of cages/concentration of initiator, \documentclass{article}\pagestyle{empty}\begin{document}$ \sum {_i k'} _{pi} [R_i \cdot][{\rm M}] = {\rm rate of initiation of polymerization} $\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}$ \sum {_i k'} _{ti} [R_i \cdot][{\rm M} \cdot] $\end{document} = rate of termination of growing chains M· by reaction with primary radicals Ri·. From this equation, several, important constants can be determined. In the polymerization of styrene at 60°C. with 2,2′‐azobisisobutyronitrile, the results obtained are as follows: kp2/kt = 5.52 × 10−4 (or 5.86 × 10−4) l.‐mole.−1‐sec.−1. ktrM/kp = 6 × 10−5, ktrS/kp 1.1 × 10−2 (carbon tetrachloride as solvent), k = 1.57 × 10−5 (or 1.48 × 10−5) sec.−1, \documentclass{article}\pagestyle{empty}\begin{document}$ \sum {_i k'} _{pi} [R_i \cdot]/\sum {_i k'} _{ti} [R_i \cdot] = 1.20 \times 10^{- 7} $\end{document}. These values agree well with those obtained by the other authors. The rate of initiation \documentclass{article}\pagestyle{empty}\begin{document}$ \sum {_i k'} _{pi} [R_i \cdot]{\rm -}[{\rm M}] $\end{document} and the rate of termination \documentclass{article}\pagestyle{empty}\begin{document}$ \sum {_i k'} _{ti} [R_i \cdot][{\rm M} \cdot] $\end{document} between the growing chains and primary radicals are calculated, respectively, from the equations:

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The rate of disappearance of the primary radicals through the reaction among themselves is negligible in comparison with the other termination rates in the usual conditions. The ratio of concentrations of the primary radicals R· and growing chains M· is expressed under an ordinary condition as:

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where VR is the rate of primary radical formation and k′p the rate constant of initiation.
The behavior of polysilicic acid. I. Surface charge effects
Authors: Greenberg S. A. , Chang T. N. , Jarnutowski R. 
Published: April 2003

AbstractThe influences of surface charges on polysilicic acid on light‐scattering, electrokinetic, viscosity, and emf measurements were examined. It was substantiated that the potential‐determining ions are hydrogen and hydroxyl, which control the dissociation of the acidic silanol groups, SiOH → SiO− + H+. The zeta potentials are also influenced by the ionic strength of the solutions. The effect of cations on the surface charges increase with valence: Na < Ca < Al. Molecular weights of silica solutions can be determined by light scattering or viscosity measurements. In order to obtain reliable measurements an ionic strength of 0.1 is recommended to suppress the influence of surface charges.
Emulsion polymerization of vinyl acetate
Authors: Okamura Seizo , Motoyama Takuhiko 
Published: April 2003

AbstractIt is generally admitted that the Smith‐Ewart equation is not applicable to the emulsion polymerization of vinyl acetate. This is considered to be due to two factors, namely, (1) the great solubility in water of vinyl acetate and (2) the fact that vinyl acetate is easily subject to the influences of retarders or chain transfer agents. However, examination of the polymerization of vinyl caproate and of styrene leads to the conclusion that the special features pertaining to the polymerization of vinyl acetate are to be attributed to its solubility in water. The reason is that vinyl caproate, which is less soluble in water but subject to the influences of retarders or chain transfer agents in the same degree as vinyl acetate, follows the Smith‐Ewart equation in emulsion polymerization, and styrene, when polymerized in aqueous methanol, in which the solubility of styrene increases, shows a diminished Smith‐Ewart exponent.
Packing of aliphatic molecules
Authors: Ivanovszky Leo 
Published: April 2003

AbstractIt is generally not appreciated that almost all physical properties of solids depend primarily on the shape of the molecule, which controls regularity and density of packing and thus such properties as melting point, specific gravity, hardness, etc. The melting point is of special interest; it characterizes the solid → melt transition.This contribution follows a novel method of assessing shape and packing arrangement of molecules, based on four considerations: (1) common‐sense probability, (2) packing characteristics, relative to compactness and balance of structure, (3) comparative studies of the melting‐point/chain‐length curves of a number of related series of homologous compounds of known and unknown configuration, and finally (4) actual packing experiments with different types of molecular models. The data so gained should also agree with known x‐ray measurements.Of importance and comparatively widely studied is the configuration of the fatty acid glycerides. For triglycerides, two (principal) arrangements have been proposed so far, namely, the “tuning fork” and the “chair” structures; these are assumed to be universally accepted. An unnamed third arrangement, not unlike a capital letter E might be regarded the basic shape. The symmetrical one‐acid diglycerides are thought to form a U‐type structure.It is shown that none of the arrangements named above is really the most probable. The symmetrical or more generally all 1,3‐diglycerides take the shape of straight‐axis molecules which form twin molecules held together by hydrogen bonds. The triglycerides also form straight‐axis molecules; the chain of the acid‐radical in the 2‐position runs parallel to the axis. The composite chain of all the glycerides can be regarded as truly planar, since it shows one negligible deviation only. The twin diglyceride molecules constitute ideal packing units with respect to both closeness and regularity. The packing structure of the triglycerides, particularly of the one‐acid type, is not much less ideal. The latter can form two kinds of twin molecule, i.e., one molecule and one‐and‐one‐half molecules long, as well as multiple (in particular eightfold molecules) two molecules long. The importance of hydrogen bonding is discussed in connection with all types of glycerides. Reference is also made to the packing of ringmolecules of planar symmetry and of aliphatics of spherical symmetry. It is pointed out that the concept of the unit cell offers little advantage in discussion of packing properties of molecular crystals, in particular in the case of long‐chain compounds; rather, it complicates the issue.
Copolymerization studies of radiation‐induced polymerization at low temperature
Authors: Tsuda Yoshizo 
Published: April 2003

AbstractCopolymerization of acrylonitrile with styrene or methyl methacrylate was performed by gamma‐irradiation at low temperatures in various solvents. Both an anionic copolymerization and a free‐radical reaction were observed to proceed simultaneously. However, when water, alcohol, or ester is present, the anionic polymerization is inhibited. On the other hand, when the content of styrene increases, the free‐radical polymerization is retarded. From results of the fractionation of styrene–acrylonitrile copolymer obtained it was concluded that an anion‐radical of acrylonitrile formed by irradiation at low temperatures initiates both an anionic and a free‐radical copolymerization. The resultant copolymer consists of a block of anionic copolymer attached to a block of free‐radical copolymer.
Röntgenographische Strukturanalyse von amorphem Polystyrol. VI
Authors: Kilian H.‐G. , Boueke K. 
Published: April 2003

AbstractEs wurden Rötgenaufnahmen von amorphem Polysryrol VI zwischen 20 und 160°C mit monochromatischer Cu Kα‐Strahlung ausgeführt. Das Beugungsbild bei 160°C wurde nach einem bekannten Verfahren, der Fourieranalyse unterworfen, und so die radiale Verteilungsfunktion des amorphen Polymeren ermittelt. Die Berechnung des Beugungsbildes, das von den intramolekularen Interferenzen herrührt, führt auf die Bestimmung einer effektiven permanenten Gruppe. Diese stellt ein Mass für die mittlere statistische Reichweite dar, über die die Lage benachbarter Atome im Makromolekül durch gegenseitige Korrelation bestimmt wird. Es ergeben sich für die Länge der effektiven permanenten Gruppe 11 Å. Über diese Länge stellt sich im Mittel dieselbe Molekülspirale ein, die von der Struktur des isotaktischen Kristalls bekannt ist. Die Struktur bestimmende Bedeutung des Benzolkerns im Polystyrol wird anhand der Streudiagramme bei verschiedenen Temperaturen diskutiert. Nach demselben Analysenverfahren wurde amorphes Phenolphtalein untersucht. Am Beispiel dieses niedrigmolekularen Glases sollten Methode und Ergebnis der Untersuchung am hochpolymeren Polystyrol indirekt überprüft werden.
Graft copolymerization to cellulose by sodium periodate
Authors: Toda Takao 
Published: April 2003

AbstractIt has been shown that acrylic monomer is easily grafted to cellulose by sodium periodate. The apparent activation energy of graft copolymerization is found to be 10.5 Kcal./mole, which indicates that polymer radicals formed by the attack of sodium periodate on cellulose initiate the graft copolymerization. The rate of the reaction increases with increasing reagent concentration of the reagent up to a certain concentration. At higher concentrations, sodium periodate produces more aldehyde groups in the graft copolymer and the grafted chains become shorter. The apparent number of graft‐initiating points is almost constant and independent of the sodium periodate concentration. Studies of homogeneous polymerization indicate that sodium periodate seems not to terminate the reaction of growing polymer radicals. On the other hand, when dialdehyde cellulose prepared previously by sodium periodate oxidation is grafted with methyl methacrylate, the grafted chain is shorter in the range of high content of aldehyde. The above observation indicates that the aldehyde groups formed in cellulose during the grafting reaction are likely to terminate the growing graft chains. The chain transfer constants for several sugars and alcohols with acrylonitrile as monomer were measured. The constants for sugars were found to be always higher than those for alcohols. The x‐ray diffraction patterns of the grafted cellulose with acrylonitrile give, in addition to the typical patterns of crystalline cellulose, lattice distances of 5.2 and about 3 A. which are attributed to the grafted polyacrylonitrile. The intensity distribution curve along the Debye‐Scherrer ring at the lattice distance of 5.2 A. leads to the conclusion that the crystallites of grafted polyacrylonitrile might be oriented along the direction of the fiber axis of the preexisting stock polymer. Studies on samples of cellulose of different fine structure would support the inference that, in the range of relatively low per cent grating the growing grafted chains on the surface of cellulose crystallites are oriented with the formation of crystallites along the lamellar plane of cellulose crystallites.
Polymerization by oxidative coupling. IV. Polymerization of 4‐bromo‐ and 4‐chloro‐2,6‐dimethylphenol and preparation and decomposition of the silver and copper salts of certain other phenols
Authors: Blanchard H. S. , Finkbeiner H. L. , Russell G. A. 
Published: April 2003

AbstractIn the present paper it has been shown that the 4‐halo‐2,6‐dimethylphenols can be polymerized to high molecular weight poly‐2,6‐dimethylphenylene ethers by the action of cupric ions, providing pyridine is also present. This reaction requires a stoichiometric amount of cupric ions and probably proceeds through complexed phenoxy radicals. Although the polymerization cannot be initiated by catalytic quantities of cupric ions, the same cupric salts which are active in the stoichiometric reaction will initiate the polymerization of the 4‐halo‐2,6‐dimethylphenols in basic solution. Here too, the products are high molecular weight polyarylethers and this reaction probably involves the displacement of halide ions by phenoxy radicals. The presumed di‐2,4,6‐trihalophenolate–bispyridine–copper(II) complexes were prepared and characterized. These complexes were decomposed under a variety of conditions, yielding polyhalophenylene ethers, which are highly branched as evidenced by their low intrinsic viscosities. Moreover, they are also terminated, probably through dioxin formation, since they show little or no residual hydroxyl in the infrared. Similarly, the polyhalophenylene ethers prepared by decomposition of the silver salts are also branched and terminated. In this connection, however, silver 4‐chloro‐ and silver 4‐bromo‐2,6‐dimethylphenolates were prepared and decomposed to a poly‐2,6‐dimethylphenylene ether of molecular weight 1800–2200 possessing one halogen and one hydroxyl per polymer chain. The infrared spectrum of this polymer, with the exception of the hydroxyl region, agrees in detail with the infrared spectrum of high molecular weight poly‐2,6‐dimethylphenylene ether prepared by oxidation of 2,6‐dimethylphenol and thus provides a proof for the gross structure of the polymer. Finally, it was found that the blue to blue‐green solutions produced from the decomposition of certain of the copper complexes and the silver salts, respectively, are diamagnetic. This finding mitigates against the participation of phenoxy radicals as the active species in these polymerizations.
Complex metaphosphate polymers
Authors: Mehrotra R. C. , Gupta V. S. 
Published: April 2003

AbstractThe complexation reaction of the polymeric metaphosphate ions has been studied with copper, calcium, barium, zinc, lead, and iron ions by physicochemical measurements indicating the formation of complex derivatives of the type (NaxM1−x/aPO3)n where a is the valency of the metal ion complexed. It has been possible to synthesize a large number of derivatives for the first time by the reactions of the following type:

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The progress of the reaction has been studied on a Stanton Thermogravimetric balance and the properties (composition, viscosity, molecular weight, and conductivity) of the transparent glassy complex metaphosphates have been studied in detail throwing fresh light on Graham's salt itself as well as these new derivatives.
Polymerization by oxidative coupling. II. Oxidation of 2,6‐disubstituted phenols
Authors: Hay Allan S. 
Published: April 2003

AbstractMany 2,6‐disubstituted phenols are readily oxidized with oxygen, a tertiary amine and a copper (I) salt being used as catalyst. The products are diphenoquinones (I) or 1,4‐polyphenylene ethers (II):
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The effect of variation of the substituents on the phenol and the infrared spectra of the polymers is discussed. Amine complexes of copper salts are the only effective catalysts found for the polymer‐forming reaction. The effect on the catalyst of varying the copper salt and the ligand is discussed.