bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthese eines gegenüber Nickel selektiven Ionenaustauschers
Authors: Štamberg J. , Seidl J. , Rahm J. 
Published: April 2003

AbstractEs wurde die Synthese eines gegenüber Nickel selektiven und 1,2‐Dioximgruppe als aktive Gruppe enthältenden Ionenaustauschers untersucht. Dieses Problem wurde schon früher von Kljatschko studiert, der die Darstellung eines Kunstharzionenaus‐tauschers durch die Einführung von Dimethylglyoxim in den Sulfo‐Resorcin‐Kationen austauscher im Stadium der Kondensation in kurzgefasster Form beschrieben hat. Bei der Anwendung seiner Methode wurde festgestellt, dass sie nicht zu positiven Resultaten führt. Dimethylglyoxim wird dabei aus dem Harze teilweise extrahiert, grösstenteils aber durch die Einwirkung von Formaldehyd zersetzt, und die komplexbildenden Eigenschaften eingebüsst werden. Die Elution von Dimethylglyoxim aus dem Harze kann durch die Einführung der 1,2‐Dioximgruppe in das Molekül beseitigt werden, das mit Formaldehyd in Polykondensation treten kann z. B. p, p′‐Dioxybenzildioxim; es wird dabei jedoch der destruktive Einfluss von Formaldehyd auf die Dioximgruppe nicht beseitigt. Eine andere Möglichkeit bietet eine geeignete Behandlung des Phenol‐Formaldehydharzes. So eignet sich z.B. für eine Nickelaufnahme das o‐2,3‐Dioximinobutylderivat des Resorcin‐Formaldehyd‐Harzes. Es besitzt jedoch eine geringe Stabilität, besonders bei erhöhten pH‐Werten. Harze mit erhöhter Beständigkeit wurden aus Polystyrol‐Harz hergestellt durch die aufeinander folgenden: Propionylierung, Nitrosierung und Oximierung. Das Studium über die Struktur des polymären Materials zeigte, dass die Einführung der Propionylgruppe p‐ständig verläuft, während in dem Styrolmonomeren die Propionylgruppe in die ω‐Stellung an der Seitenkette eintritt. Das Dioximderivat Polystyrols besitzt für Nickel eine Austauschkapazität von 2 meter/g und das Verfärben des Polymeren bei der Sorption entspricht dem Verfärben der niedermolekularen Dioxim–Nickel‐Komplexe. Die von linearen Polystyrol dargestellten Ionenaustauscher besassen nicht die erforderlichen mechanischen Eigenschaften; es wurden also Versuche ausgeführt mit einem Styrol‐Divinylbenzol Suspensionskopolymeren (0,3; 1.0% DVB). Es wurden dabei Bedingungen für das Erreichen des erforderten Umsetzungsgrades gefunden. Gegenwärtig wird der Einfluss von der Konzentration des primären Substituents auf die Reaktionsfähigkeit des Mischpolymerisats untersucht.
Lithium‐initiated copolymerization of styrene and methyl methacrylate. I
Authors: O'Driscoll K. F. , Boudreau R. J. , Tobolsky A. V. 
Published: April 2003

AbstractThe copolymerization of methyl methacrylate and styrene has been investigated using metallic lithium as an initiator. The unusual composition of the polymer produced does not permit description of lithium as either a classical ionic or radical initiator. A new concept must be adduced to explain the observed results.
Some special features of organic polymers containing phosphorus
Authors: Korshak V. V. 
Published: April 2003

AbstractResults obtained in the investigation of polymers containing pentavalent phosphorus in the main polymer chain are presented. A number of polyamides and polyesters derived from phosphorus‐containing dicarboxylic acids have been synthesized. Two types of dicarboxylic acids were used: alkyl‐ or aryl‐phosphinic acids (I) and bis‐carboxyphenyl‐phosphine oxides (II):
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their chloroanhydrides or esters being used in the reaction. To obtain polyesters, various glycols or dihydric phenols were used as the second component. For preparing polyamides, aliphatic diamines were used as the second component. The nature of the starting materials has a very marked effect on the properties of the polymers obtained. Polyesters with an aliphatic chain are viscous, thick oils or low‐melting resins. Polyesters with aromatic unit are high‐melting, solid elastic substances. Comparison of the properties of the polymers synthesized by us with the properties of polymers of related composition not containing phosphorus, shows that the introduction of phosphorus into the chain leads to molecules of much greater flexibility. For this reason the softening points of the phosphorus‐containing polymers are much lower than those of their carbon analogues.
Amines and carboxylic acids as initiators of polymerization in caprolactam
Authors: Majury T. G. 
Published: April 2003

AbstractEvidence is presented for the initiation of polymerization in caprolactam by two primary amines and two carboxylic acids, with rigorous precautions to exclude water from the systems. The kinetics of the reactions have been studied dilatometrically and all are shown to share two major features: (1) the plot of conversion vs. time is characteristically sigmoid in shape, and (2) the maximum slope of this plot tends to be proprtional to the square root of the initiator concentration. The rate data show that acids induce rather more rapid polymerization than bases. When combined with data in the literature on the polymerization induced by aminocaproic acid or water, they indicate that reaction of lactam at the amino and carboxyl groups accounts for an appreciable but minor proportion of the observed reaction rate; the remainder is presumably attributable to the mechanism of alternate hydrolysis of lactam and condensation of terminal amino and carboxyl groups. The explanation of the precise mechanism by which amines and acids induce polymerization offers some difficulty. A molecular ring‐addition mechanism fails to account for the square root concentration dependence mentioned above. The hypothesis of ring‐insertion at chain amide linkages is capable of yielding a suitable rate dependence but is shown to be invalidated by other evidence. A tentative suggestion of an ionic ring‐addition process is made which is consistent with the major kinetic characteristics of these reactions.
Ion exchange resins as catalysts in the decomposition of sarin
Authors: Chasanov Martin G. , Epstein Joseph 
Published: April 2003

AbstractThe hydrolysis rate of the nerve gas Sarin in aqueous solution may be accelerated by strongly acidic and strongly basic ion exchange resins. Basic resins are more effective than acid resins. Depending on the resin type and internal structure, a diffusional process or the chemical reaction may be rate determining. In distilled water, cationic resins behave as true catalysts, whereas the products of decomposition of Sarin destroy the effectiveness of anion resins. Dissolved salts in the water lower the useful life of both types of resins by replacement of the active hydrogen or hydroxyl groups.
The kinetics of the heterogeneous hydrolysis of poly(vinyl formate) and of poly(vinyl formate‐co‐stearate)
Authors: Jordan Edmund F. , Port William S. 
Published: April 2003

AbstractThe rate of hydrolysis of formate and stearate segments from poly(vinyl formate) and from poly(vinyl formate‐co‐stearate) suspended in dilute aqueous hydrochloric acid was studied. Evidence was presented to show that the hydrolysis follows pseudo‐first‐order kinetics. The Arrhenius constants and the entropies and free energies of activation for the hydrolysis of formate and stearate groups from copolymers containing 0, 3, 5, and 10 mole‐% vinyl stearate were calculated from the partially reduced reaction rate constants at three temperatures. For the hydrolysis of formate segments, ΔS‡ is markedly affected by the stearate content, whereas the variation in ΔF‡ is small. Variations in vinyl formate content have smaller effects on the thermodynamic constants of the activated complex for the hydrolysis of the stearate segments. At approximately 95°C., some anomalous kinetic behavior was observed.
Tests on the hydrolysis of certain synthetic polymers
Authors: Bevington J. C. , Eaves D. E. , Vale R. L. 
Published: April 2003

AbstractPolymers of methyl methacrylate, methyl acrylate, vinyl acetate, and acrylonitrile labeled with carbon‐14 in the functional groups have been prepared. The labeled polymers have been subjected to hydrolysis, and the specific activities before and after treatment have been compared. Almost complete hydrolysis of polymethyl acrylate and polyvinyl alcohol is readily achieved. It has been confirmed that polymethyl methacrylate is rather resistant to hydrolysis, but ester endgroups in this polymer are easily detached. During treatment of polyacrylonitrile with acid or alkali, no carbon atoms are lost from the polymer.
The molecular weight of polyacrylonitrile
Authors: Krigbaum W. R. , Kotliar A. M. 
Published: April 2003

AbstractThere is a surprising lack of agreement between the values which have been reported for both the number‐average and weight‐average molecular weights of polyacrylonitrile. We have undertaken an investigation of both whole polymers and polymer fractions to discover and eliminate the sources of systematic error which would lead to these differences, and thereby to develop procedures yielding reliable molecular weight values for this polymer. Our experience indicates that the procedure which must be followed to obtain reliable osmotic data depends upon the conditions under which the polymer was prepared, whether the sample is a whole polymer or a fraction, and the purity of the solvent. Designating solution polymers by S and those prepared in an aqueous system with a persulfate‐bisulfite initiator by A, we conclude that reliable M̄n values can be obtained for S polymers by using dimethylformaide (DMF) which has been purified by deionization or distillation, for fractions of A polymers by using deionized DMF, and for whole A polymers by performing the measurements upon DMF solutions which have been deionized by passage through a column of Amberlite MB‐3 resin. Fictitiously low M̄n values are observed for A polymers dissolved in distilled DMF. The value of the secon virial coefficient is very ensitive to the presence of traces of water. Turning to weight‐average molecular weights, a 60% discrepancy exists between the values obtained from light scattering by Stockmayer and Casassa and by Bisschops from sedimentationdiffusion. We believe the correct M̄w values lie midway between these. A part of the 60% difference is due to the omission of a correction to the sedimentation data for the effect of hydrostatic pressure. This correction was evaluated from sedimentation data by the procedure of Oth and Desreux and increases the molecular weight values deduced from sedimentation by 30%. The remainder of the difference appears to be due to the effects of depolarization and fluorescence upon the light scattering data. Thus, our data for two fractions which exhibited a limiting depolarization ρu = 0.09 yielded high M̄w values standing in agreement with the relation of Stockmayer and Casassa, while the result obtained for a whole polymer having a negligible limiting depolarization agrees with those obtained from the corrected sedimentation data. The latter polymer also exhibited a more normal scattering behavior. A comparison of the weight and number‐average values indicates that the M̄w/M̄n ratio is 2.1 ± 0.1 for the whole S polymers and 2.8 ± 0.3 for the whole A polymers. The broader distribution in the latter case suggests that termination occurs by both coupling and disproportionation in the aqueous polymerization.
Poly‐n‐octyl methacrylate. V. Dilute solution properties by viscosity and light scattering
Authors: Chinai S. N. , Resnick A. L. , Lee H. T. 
Published: April 2003

AbstractPoly‐n‐octyl methacrylate, prepared by the emulsion technique, was fractionated three times by the fractional precipitation procedure to obtain eight fractions. Relationships between viscosity and weight‐average molecular weight were obtained in both an ideal solvent, n‐butanol, and a nonideal solvent, methyl ethyl ketone. These relationships are represented by the equations, [η] = 2.68 × 10−4M [η]23 = 4.47 × 10−5M, respectively. The effect of the size of the pendant groups (‐methyl, ‐ethyl, n‐butyl, ‐n‐hexyl, and ‐n‐octyl ester) on the degree of extension of macromolecules in ideal solvents is discussed. It was found that, initially, as we progress from polymethyl to poly‐n‐butyl methacrylate, the degree of flexibility of the macromolecule increases as the size of the pendant group increases. These results are believed to be due to the short‐range interference effect of the solvent molecule on the degree of free rotation of the macromolecule. However, it was found that poly‐n‐hexyl methacrylate chains have considerably greater chain extension than any of the other three polymers. This expansion of poly‐n‐hexyl methacrylate chains is a result of the steric effect of large pendant units. From the results obtained for n‐octyl polymer, it is evident that, in spite of further increase in the size of the pendant group by (CH2)2, there is a substantial contraction in the n‐octyl polymer chain. The reason for this reversal in the polymer chain expansion is not clearly understood at present.
Polyethers. VII. Aluminum catalysts for polymerization of ethylene oxide
Authors: Miller Richard A. , Price Charles C. 
Published: April 2003

AbstractAluminum alkoxide and aluminum alkyl catalysts have been found to convert ethylene oxide to high molecular weight polymer. Examination of the polymer for hydroxyl and olefin end groups, wing phthalic anhydride and bromine, revealed approximately one double bond per molwule but no detectable hydroxyl groups.
Polyethers. VIII. Isotactic polymerization of phenyl glycidyl ether
Authors: Noshay Allen , Price Charles C. 
Published: April 2003

AbstractPhenyl glycidyl ether has been polymerized, using aluminum catalysts, to crystalline as well as amorphous polymers. The crystalline fraction is high melting (ca. 200°) and insoluble at room temperature. The amorphous fractions are soluble at room temperature and some show rubber‐like properties. The best yields of polymer were obtained when reactions were carried out in bulk, in open, stirred systems using aluminum isopropoxide and zinc chloride as cocatalysts.
Heterogeneous copolymerization of methacrylate esters with the methacrylate ion in aqueous media
Authors: Parsons R. J. , Warson H. 
Published: April 2003

AbstractIt is known from the Patent literature that many water‐soluble salts of copolymerizable acids can be copolymerized with water in soluble, polymerizable esters when the latter are dispersed as an aqueous emulsion. We have studied the copolymerization of methacrylate esters, especially methyl methacrylate, with sodium, methacrylate, the former being maintained in a fine particle size with the aid of a water‐soluble colloid and rapid stirring. Results have been reproducible. Analytical methods have been worked out for each monomer in the presence of the other, in order to follow the course of the reaction. Several ratios of methyl methacrylate and sodium methacrylate have been investigated under semi‐adiabatic conditions, using a persulfate as polymerization initiator. When the two monomers are polymerized together equimolecular ratios, there is a period of inhibition or retardation only in respect of the sodium methacrylate, but this can be avoided by adding methyl methacrylate to sodium methacrylate at incipient polymerization of the latter. It has been possible to deduce a general picture of polymerization, which is as follow: The polymerization of methyl methacrylate follows zero‐order kinetics for a large part of the reaction, while that of sodium methacrylate follows first‐order kinetics. On increased dilution of the system, the rate of polymerization of methyl methacrylate is increased. On the one hand, increase of methyl methacrylate keeping water and sodium methacrylate constant results in little difference in the rate of polymerization of sodium methacrylate or on the proportional rate of polymerization of methyl methacrylate. On the other hand, the actual rate of polymerization of methyl methacrylate is doubled. β‐Ethoxy ethyl methacrylate and ethyl methacrylate copolymerize to a lesser extent with sodium methacrylate in the examined ratios. In these cases a larger proportion of the sodium methacrylate remains unpolymerized when polymerized of the ester is virtually complete. Copolymerization is virtually nil between butyl and sodium methacrylates. The possible mechanism of the copolymerization is discussed.
The preparation and properties of grafts of polycaprolactam on vinyl copolymers
Authors: Chapman C. B. , Valentine L. 
Published: April 2003

AbstractThe reaction between vinyl polymers bearing reactive function (e.g., COOMe, COOH, NH2) and caprolactam should lead to the formation of grafted side chains of nylon 6 on a backbone of vinyl polymer. With styrene‐methyl acrylate (S/MA) co‐polymers in particular, the reaction initiated by water by 220–250°C. has been followed by measuring the melt viscosity, and the resultant polymers have been characterized. Combination takes place, but complication limit the extent of reation,e.g., loss of amino groups, crosslinking, inhomogeneity of the reaction melt. Soluble graft copolymers are formed only if the D.P. of the vinyl polymer is low, and the methyl acrylate content is high,e.g., 1:1 S/MA copolymers of D.P. 60 and 2:1 copolymer of D.P. 150 both give homogeneous graft copolymers. All other 1:1 and 2:1 copolymers of higher D.P. give insoluble products, because of crosslinking. For all copolymers in which the S/MA ratio is > 2:1, very little reaction occurs, and the products can be separated by solvent extraction into three fractions,viz.nylon 6, unchanged S/MA copolymer, and a graft copolymer. At high S/MA ratios, irrespective of the D.P., the two polymers are incompatible, and reaction is confined to the polyamide‐copolymer interfaces. The soluble graft copolymers were characterized by elemental and endgroup analysis, melting points, melt viscosity, soluble viscosity, and infrared spectoscopy. The interaction of styrene‐maleic anhydride and styrene‐acrylic acid copolymers with nylon 6 leads invariably to insoluble products.
A non‐hydrolytic polymerization of ϵ‐caprolactam. The polymerization initiated by hydrogen chloride
Authors: Van der Want G. M. , Kruissink Ch. A. 
Published: April 2003

AbstractSome experiments are described which show that the polymerization of ϵ‐caprolactam (CL) can be accomplished by heating the lactam under anhydrous conditions in the presence of hydrogen chloride or of salts of strong acids and ammonia or amines at temperatures of 220–260°C. To study this type of polymerization more closely, two series of kinetic experiments with the sytem CL–HCl hae been performed (254°C.; initial molar ratios of HCl to CL, 0.025 and 0.0125). The progress of the reaction, characterized by the degree of conversion (determined by extraction of the unconverted lactam with water), is compared with the polymerization of CL initiated by corresponding amounts of water or of ϵ‐aminocaproic acid. The products obtained have been characterized by endgroup titration values and intrinsic viscosity. Some additional data have been obtained by chromatography and IR investigations. The titrations show that the molecules bear an amino group at one end of the chain; the nature of the other endgroup is still obscure. Reaction constants calculated for an uncatalyzed additon of CL to amino groups prove to be of about the same magnitude as those of the water‐initiated polymerization without additional HCl. At the same time some kinetic experiments with the system CLH2OHCl are presented. Both systems have some striking features in common. The catalytic effect of the HCl present in this system can be attributed to the rapid formation of amino groups in the very first moments of the reaction, thus leading to an enhanced rate of polymerization by addition of CL to amino groups.
Molecular weights and molecular dimensions of linear and branched polyethylenes
Authors: Trementozzi Q. A. 
Published: April 2003

AbstractThe behavior of linear polyethylene in various solvents has been investigated by the light scattering, osmotic pressure and viscosity methods. It is shown that polyethylene associates in α‐chloronaphthalene solution. The degree of association increases with molecular weight, but, at low molecular weights, it essentially vanishes. A comparison of molecular weights obtained from light scattering and osmotic pressure studies of solutions of polyethylene fractions in tetralin and‐p‐xylene yields no evidence of association over a broad range of molecular weights. The unperturbed molecular dimensions are shown to be considerably greater than those of polystyrene at the same degree of polymerization. In terms of Flory's theory of chain stiffness, linear polyethylene becomes competitive in stiffness with some cellulose derivatives of comparable temperatures. At a sufficiently high degree of polymerization, the Fox‐Flory equation is obeyed.
Relations among melt viscosity, solution viscosity, molecular weight, and long‐chain branching in polyethylene
Authors: Moore Louis D. 
Published: April 2003

AbstractAccording to the segmental theory of flow, the viscosity ηm of a polymer melt should be given by

where the jump frequency J is a function of temperature and free volume, and a statistical factor F, depending on chain length, expresses the requirement that the motions of the segments be coordinated. Peticolas and Watkins found that, at the same weight‐average molecular weight, branched polyethylenes have considerably lower viscosities than linear polyethylenes. They attributed this reduction in viscosity to an increased free volume (which would increase the jump frequency) brought about by short‐chain branches. Marshall, however, pointed out that the required increase in free volume is not found by experiment. This paper presents an alternative theory whereby the reduction in viscosity is attributed to the presence of long‐chain branches which help coordinate the movement of the various segments and thereby reduce the coordination factor F. As a result of certain theoretical considerations, a linear relation is predicted between the log of the melt index and the intrinsic viscosity in an ideal or Θ‐solvent. This relation is confirmed by a plot of data from 27 samples of polyethylene obtained from four commercial sources and having melt indices ranging from 0.12 to 26.6. Bis(2‐ethvlhexyl) adipate at 145°C. was used as the ideal solvent. Further insight into the viscous and viscoelastic behavior of polyethylene samples was obtained when it was observed that detailed interpretation of light‐scattering data explained the fact that samples with practically the same melt indices had different solution viscosities in a good solvent such as Tetralin at 100°C. These variations were attributed to differences in the expansion factor α. This factor depends on molecular weight, long‐chain branching, and solvent power and probably reflects the ease with which a molecule may be deformed. This α‐factor then should probably be related to the spectrum of relaxation times which would influence such important processing variables as melt elasticity and non‐Newtonian flow.
The copolymerization of silicon‐substituted styrenes
Authors: Lewis Charles W. , Lewis Daniel W. 
Published: April 2003

AbstractThe monomer reactivities of p‐trimethylsilylstyrene and p‐trimethoxysilylstyrene have been invertigated. In both cases e is equal to the e of styrene. The former has a Q equal to that of styrene but the Q of the latter substituted styrene is about 40% greater.
Fractionation of chlorotrifluoroethylene polymer
Authors: Okamoto H. 
Published: April 2003

AbstractChlorotrifluoroethylene polymers were fractionated with the use of a fractionation apparatus designed for use at high temperatures. The solvent and the nonsolvent were the same as those used by Kaufman and Solomon. The relationship of specific viscosity and concentration was established in trifluoropentachloropropane by Schulz's formula. The differential distribution curves of Kel‐F and Daiflon‐B have maxima at lower viscosities and decrease more slowly than those of Daiflon‐A. This accords qualitatively with melt index data.