bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic study of thermal dehydrochlorination of poly(vinyl chloride) in the presence of oxygen. I. Fundamental relations
Authors: Valko L.
Published: June 2010

Starting from the assumption that the mechanism of the elimination of the HCI molecule and of cleavage of the C–C bonds represents a monomolecular stochastic process, a differential equation has been constructed that describes the thermal destruction of PVC in oxygen. Here one has started from the step mechanism of destruction, this being associated with the formation of weak points in the polymer chain system. The influence of dissipative factors, which prevent transferring the system into a truly thermodynamic equilibrium, has been considered too. The introduced kinetic parameters and relations between them make it possible to evaluate quantitatively the kinetics of destruction of PVC in oxygen, treated to various degrees of reaction.
A new equation for polymer oxidation reactions
Authors: Kovarskaya B. M.
Published: June 2010

An empirical equation permitting the description of oxygen absorption as a function of time for all steps of oxidation of a number of heterochain polymers of linear and three‐dimensional structure: polycarbonate, polycaproamide, epoxy resin, etc., is proposed. A suggestion is made that a compound inhibiting oxidation is formed along with the oxidizing product.
Anionische Polymerisation in Schwach Solvatisierenden Lösungsmitteln
Authors: Figini R. V.
Published: June 2010

The anionic polymerization of styrene initiated by cumylsodium and carried out in cumyl methyl ether has been examined with use of conversion kinetics and molecular weight distribution. The solvent has a weaker solvation power than THF and THP, which have been studied with the same experimental technique. The polymerization rate is first order relative to monomer and the rate constant has a value of ca. 1 mole−1 1. sec.−1 at − 20.5°C. The constant is only slightly dependent on the initiator concentration, but the molecular weight distribution is broader than a Poisson function. Added electrolyte has little effect on the propagation constant but it greatly alters the molecular weight distribution. These experimental results are discussed in connection with two‐state polymerization.
Wechselwirkung Zwischen Chloriertem Polyolefin und Lösungsmittel. III. Einfluss von Bedingungen der Filmbildung auf die Eigenschaften von Chlorierten Niederdruckpolyäthylen‐Filmen
Authors: Kriston Pal , Dimitrov Miklos
Published: June 2010

The influence of film‐forming conditions on the properties of chlorinated low pressure polyethylene films has been examined. The film‐forming temperatures have been found to cause not too large but measurable differences in yield strength of the films. The concentration of the film‐forming solution has no important effect on the properties investigated. but the solvent‐diluent ratio markedly influences viscosity, tearing strength, and permeability. An inverse dependence of yield strength on solvent vapor permeability has been established.
Untersuchung der Kationischen Copolymerisation von Cyclischen Anhydriden mit Cyclischen Äthern
Authors: Habermeier J. , Reichert K.‐H. , Hamann K.
Published: June 2010

The preparation of linear polyesters by the well‐known base‐catalyzed copolymerization of carboxylic dianhydrides and cyclic ethers is possible only with epoxides or in the essentially slower reaction with 4‐membered cyclic ethers. It is not possible with higher cyclic ethers. The reaction of 5‐7‐membered cyclic ethers (tetrahydrofuran, tetrahydropyran, hexamethylene oxide) and succinic and phthalic anhydride can be carried out with varied reaction conditions. Using complex Lewis acid/co‐initiator type initiators, e.g., SbCl5‐MeCOCl or Et3O+BF4‐ producing reactive cations polyesters with molecular weights up to 3200 are formed within 3 hr. in the melt at 120°C. with 70‐95% yield. The products obtained contain ether bond units in the polymer chain. The ether content not only depends on the molar ratio of the reactants but is strongly influenced by the nature and especially by the concentration of initiator. On the basis of this fact a two‐step reaction mechanism is postulated: (1) polymerization of the cyclic ether to the corresponding poly(alkylene oxide); (2) subsequent transacylation inserting the anhydride between the polyether chain units. The occurrence of the secondary reaction could be confirmed by short‐time experiments. Similarly, polyethers and carboxylic dianhydrides are converted to the corresponding polyesters by complex cationic initiators. This further proves the two‐step mechanism postulated above.
The investigation of polymerization at high pressures
Authors: Zharov A. A. , Berlin Al. Al. , Enikolopyan N. S.
Published: June 2010

The polymerization kineties of three types was investigated under high pressure: redieal propylene polymerization, eationie styrene polymerization, and trioxane polymerization in the solid state. Two first rections are accelerated by pressure and the rate of solid‐state polymerization of trioxane is decreased by pressure. A kinetic scheme ac counting for the experimental results is suggested.
Zum Mechanismus der Thermische Abspaltung von Chlorwasserstoff aus Polyvinylchlorid. I. Mitteilung: Thermische Zersetzung von Copolymeren aus Vinylchlorid und Fumarsäurediäthylester, Isobutylen, Vinylbromid und 2‐Chlorpropen
Authors: Braun Dietrich , Thallmaier Manfred
Published: June 2010

Investigation of the thermal behavior of copolymers of vinyl chloride (VC) and diethylfumaric ester (FDE), isobutene (IBu), vinyl bromide (VBr), and 2‐chloropropene (2CP) gives an insight into the mechanism of thermal dehydrochlorination in an inert atmosphere. The rate of decomposition at 180°C. increases in the following order: VC‐homopolymer < VC–FDE‐copol. < VC‐IBu‐copol. < VC‐VBr‐copol. < VC‐2CP‐eopol. The thermal elimination of hydrogen chloride from the copolymers in a nitrogen atmosphere starts from the comonomer unit. The first step of the decomposition of the VC‐VBr and the VC‐2CP‐copolymers requires a sequence of at least two neighboring comonomer units. The behavior of the 2CP‐copolymers indicates that the thermal decomposition of PVC can start from branches. The growth of the forming polyene sequences is stopped at the FDE‐ or IBu‐units Thus shorter sequences result, in reference to the VC‐homopolymer. However, the length of the polyene sequences increases from PVC to VC‐VBr‐copolymers to VBr‐homopolymer. The activation energies of hydrogen halide elimination from VC–VBr‐ and VC–2CP‐copolymers are lower than that of PVC.
Cationic copolymerization of isobutene. IV. Copolymer degree of polymerization in cationic polymerization
Authors: Okamura Seizo , Higashimura Toshinobu , Imanishi Yukio , Yamaiamoto Ryuji , Kimura Kuninobu
Published: June 2010

The lowering of degree of polymerization in cationic copolymerization was investigated for the isobutene–styrene copolymerizations in particular. In this system the simultaneous presence of a reactive isobutene cation and reactive styrene monomer acting as a chain transfer agent, a situation which cannot be visualized in homopolymerization, was proved to be responsible for giving low molecular weight copolymers. The ratios of rate constant for the monomer transfer reaction from isobutene cation to styrene monomer, a cross–transfer reaction, were determined kinetically. Carrying out the copolymerizations in solvents of different dielectric constant, in solvents of similar dielectric constant but of different solvating power, and with the Wichterle catalyst, and comparing the results with those by homogeneous catalyst, the polar and the nonpolar, possibly solvation effects of the solvent, and the effect of a heterogenity of catalyst on the crosstransfer reaction were investigated. A mechanism for the reaction was proposed. The choice of a comonomer or reaction conditions to minimize the cross‐transfer reaction in isobutene copolymerization was discussed in the light of the information about the styrene‐type monomer transfer reaction which has been reported previously by the present authors.
Solid‐ and liquid‐states polymerization of tetrafluoroethylene induced by ionizing radiation
Authors: Tabata Yoneho , Shibano Hiroshi , Oshima Keichi , Sobue Hiroshi
Published: June 2010

Solid‐state polymerization of tetrafluoroethylene was carried out by initiating with γ‐rays from Co60 and electrons from a Van de Graaff generator. Apparent activation energy of the polymerization in the solid state was about 0.3 kcal./mole. The polytetrafluoroethylene which was obtained both in liquid‐ and solid‐state polymerizations was examined by the infrared and x‐ray diffraction methods. From these experiments it was clearly demonstrated that the crystalline structure is quite different between both polymers. It indicates that the polymerization in the solid state is strongly influenced by the crystal lattice of the monomers.
Conformation of methacrylic acid radicals in solid‐state polymerization
Authors: Bamford C. H. , Bibby A. , Eastmond G. C.
Published: June 2010

Recent work has shown that the familiar ESR spectrum of methacrylic acid radicals can be modified when the radicals are formed in the solid state by irradiation. For example, the conventional 9‐line spectrum may be replaced by one of 13 lines. The nature of the radicals depends critically on the conditions of irradiation and crystal formation. The factors influencing the structure and concentration of the radicals are discussed and correlated with broadline NMR observations in this paper.
New organic systems for the study of electrical conduction mechanisms
Authors: Andres Raymond J.
Published: June 2010

An organic structure embodying a π‐electron chain of carbon atoms which terminates in an electron‐bridging structure at each end is proposed as a promising class for evaluation as organic semiconductors. A quantum mechanical argument is presented on which is built a model simulating conduction electrons within a band and an energy gap between bands like that present in inorganic semiconductors. Results are reported on the polymerization of diamines and dibasic acids containing π‐electron structures. These polymers are of limited value in studying the mechanism of conduction since they are thermally intractable and are insoluble in useful solvents. Study of monomeric substances based on similar structures is now in progress and evaluation of electrical characteristics of well‐formed crystals is planned.
Charge‐transfer exciton and ionic levels in organic crystals
Authors: Pope Martin
Published: June 2010

By means of external photoelectric emission produced by double‐exciton annihilation within the crystal, a mobile charge‐transfer (CT) state consisting of a hole and an electron on adjoining lattice sites has been identified in tetracene and anthracene. The energy of this state is 2.9 e.v. in tetracene and 3.45 e.v. in anthracene; there can be no intrinsic charge‐carrier generation in these materials at energies less than these CT energies. A study of delayed electroluminescence in anthracene provides evidence for the existence of a broad, upper conductivity band; measurements of the efficiency of generating CT excitons as a function of the energy of the exciting light indicate that in anthracene, the broad upper conductivity level starts at about 4 e.v., and in tetracene, at about 3.5 e.v. From photoconductivity measurements made in the short ultraviolet region, it appears that the lowest, narrow‐band conductivity level in tetracene appears 3.1 e.v. above the ground state of the crystal, and at about 3.7 e.v. in anthracene. A maximum value for the CT exciton‐exciton recombination coefficient (β) in anthracene is estimated to be 10−9 cm.3 sec.−1. From an examination of the delayed fluorescence produced in anthracene by α‐particle bombardment, it is concluded that the lifetime of the CT exciton T(CT) is less than 10−6 sec. The efficiency of generating the CT exciton in anthracene using light of energy 4.4 e.v. is about 2%, based on the values for β(CT) and T(CT) given above.
The nature of the lamellar crystalline structure in branched polyethylenes as deduced from melting point and branching determinations
Authors: Knox Jack R.
Published: June 2010

In a semicrystalline polymer chain, if n is the total number of backbone units and a is the number of nonlattice backbone units, then the per cent crystallinity is (n – a)/n. By an empirical approach it is found that if a is set equal to ca. 40 for branched polyethylenes and n is determined from a melting point‐fold length relationship that the calculated values of per cent crystallinity are in good agreement with experiment. It is also shown that 100/(n – a) is equivalent to the total number of branches per 100 methylenes for branched polyethylene. A sinusoidal random coil is postulated for the melt state in order to rationalize why chain folding with adjacent reentry should occur if as many as 40 methylenes per fold are noncrystalline.
Fractions of linear polyethylene as moleculary dispersed eutectic systems
Authors: Asbach G. I. , Kilian H. G. , Müller F. H.
Published: June 2010

A thermodynamic theory of melting for linear stereoregular homopolymer systems with a molecular weight distribution has been derived. The homopolymer system is regarded as a eutectic multicomponent system. The components of the system are the molecules themselves. Under conditions of thermodynamic equilibrium the molecules of different lengths should crystallize as extended‐chain crystals. The thickness of the crystals equals the molecular length. During crystallization of stereoregular homopolymer systems the molecular weight fractionation is usually not completely established. This can be described by only one additional internal parameter in the theory. To test the theory, fractions of linear polyethylene as the simplest examples of regular homopolymers were investigated by means of DTA and low‐angle x‐ray diffraction methods. The maximum melting points, the molar mass fractions of crystals as a function of temperature, and the long periods depend on the data of the molecular weight distribution, as predicted by the theory. Both the theory and the experiment agree quantitatively provided that only extended‐chain crystals exist. Under normal pressure conditions molecular folding processes occur, beginning above a critical molecular length. This critical molecular length is determined by kinetic factors.
Military applications of high temperature fibers
Authors: Gloor W. H.
Published: June 2010

The interest of the Air Force and other military organizations in high temperature fibers spans a broad range of fiber types and applications. Fibers and yarns with a high degree of flexibility and good thermal capabilities are required for flexible fibrous materials for use in decelerators and expandable and/or rigidizable structures. High temperature fibers with outstanding modulus‐to‐weight ratio are needed for reinforcement of composite structural materials. In most instances, a high strength‐to‐weight ratio, at temperature, is desirable. To meet these space‐age requirements, research is being conducted by the Air Force Materials Laboratory on a wide variety of fiber types, including polymeric, metallic, graphite, glass, and ceramic. The results of this, and similar research being conducted by industry, while maintaining our military superiority, will, in many instances, also be felt in the commercial world.
Aromatic ordered copolyamides for temperature‐resistant fibers
Authors: Preston J. , Smith R. W. , Stehman C. J.
Published: June 2010

Fibers were spun from five different wholly aromatic ordered copolyamides. Each polymer contained units derived from aminobenzoic acids, arylene diamines, and arylene diacids. Structural differences in the ordered copolyamides were made by variations in combinations of para‐ and meta‐phenylene units, 2,6‐naphthalene units, and 4,4′‐bi‐phenylene units. Tensile properties of the fibers were obtained at standard conditions, at elevated temperatures, and after heating at 300°C. in air. All of the fibers had tenacities of about 6 g./den. and all were crystalline after drawing. Easy of crystallization, initial modulus, elongation, and retention of tensile properties at elevated temperatures in air were, in general, consistent with variations in the structure of the polymers. Fiber properties were retained to a high degree at temperatures up to 400°C., and fibers heat aged at 300°C. showed remarkable retention of tensile properties. Radiation resistance (γ source, 2.92 × 105 rads/hr.) of these fibers was good and resistance to ultraviolet light appeared to be better than that of unstabilized nylon 66.
Aspects of the structure of α‐Keratin derived from mechanical properties
Authors: Chapman B. M. , Feughelman M.
Published: June 2010

α‐Keratin fibers such as wool and hair may be considered in terms of the two‐phase model of organized microfibrils arranged parallel to the fiber direction and embedded in a disorganized matrix. The microfibrils contain α‐helices responsible for the crystalline x‐ray diffraction pattern of α‐keratin; the length stability of the microfibrils depends on the stability of α‐helices. Modifications to the matrix in parallel with the microfibrils are masked by this lengthwise stabilization but can be revealed by placing the fibers in 98% formic acid. In this medium a large proportion of the α‐helices are randomized and much of the stabilization due to the microfibrils is removed. Wool fibers in which portions of the microfibrils were modified by different levels of extension in boiling water were also examined by mechanical properties in concentrated formic acid. The results are considered in terms of relationships between mechanical properties and molecular structures already proposed.
Reshaping: A computational method of resolving gel permeation chromatograms
Authors: Pickett Harry E. , Cantow Manfred J. R. , Johnson Julian F.
Published: June 2010

In this paper we present a rigorous argument for the validity of a new technique for obtaining greatly increased resolution of the chromatograms of a gel permeation chromatograph. The method is phenomenological in that no assumptions are made about the separation process, although certain simple assumptions are made about the characteristics of this process. Instead, the method makes use of the observable behavior of narrow polymer fractions of presumably known composition. From a pragmatic point of view, this is an important aspect of the method, since the results predicted by the method depend only upon what the chromatograph is observed to do, and not upon what it is assumed to do. This method has been implemented in FORTRAN IV for the IBM 7094 computer.
Elution behavior of model compounds in gel permeation chromatography
Authors: Edwards G. D. , Ng Q. Y.
Published: June 2010

Although gel permeation chromatography (GPC) was developed primarily for measuring the molecular size distribution of polymers, it has been extremely useful for analyzing materials of intermediate and low molecular weight. It is also in this range that properties of compounds other than molecular size appear to have the greatest effect on the elution characteristics of solutes. Therefore, in order to increase the effectiveness of GPC as an analytical tool, the elution behavior of about 100 model compounds was studied and this information used to assist in the interpretation of chromatograms.
Gel permeation chromotography: New applications and techniques
Authors: Bombaugh K. J. , Dark W. A. , King R. N.
Published: June 2010

Recent advances in GPC technology are described. These advances include the development of column packings which are compatible with aqueous systems and permit the fractionation of water‐soluble materials such as dextrans, polyphosphates, and lignin sulfonates. Small molecule separation capability in both aqueous and organic systems is also demonstrated. New equipment is described which is capable of both analytical and preparative scale separations. Utilizing 2½‐in. ID columns 1.5‐g. sample loads were fractionated with resolution comparable to the analytical system.
Unsaturation changes and other radiolytic reactions in polyethylene. II. An examination of crosslinking with gel permeation chromatography
Authors: Lyons Bernard J. , Fox Adrian S.
Published: June 2010

A simple method of determining crosslink yields and examining crosslink statistics in polymers is described. In this method the soluble fraction of materials crosslinked to well above their gel point is examined with gel permeation chromatography and compared with the original material. The results of such an examination of the soluble fractions of irradiated polyolefins indicate that the random statistical crosslinking mechanism first suggested by Charlesby is followed closely by low‐density polyethylenes. The high‐density polyethylenes examined show deviations from statistical behavior, which may be attributed to dimerization or endlinking through vinyl decay. However, other factors may also be involved. The results suggest that G (crosslinks) does not change significantly with dose and that the ratio of chain scission to crosslinks is less than 0.03 in the range up to 80 Mrad in a low‐density polyethylene.
The use of gel permeation chromatography in guiding polymer syntheses
Authors: Pavelich William A. , Livigni Russell A.
Published: June 2010

Gel permeation chromatography can contribute significantly to the guidance of polymer synthesis activities. Qualitative information about the effect of reaction variables on molecular weight distribution is satisfactory for such studies. Reaction mixtures can be analyzed without isolating the products of interest. Data are available soon after the reaction is completed, enabling future work to benefit from the information generated. The polymerization of propylene oxide in the presence of 1,5‐pentanediol and hydrocarbon solvent was shown to proceed in two steps. All the diol first reacted with propylene oxide to form an adduct at each hydroxyl function. Propagation with propylene oxide then proceeded with no further initiation and no termination reactions. Attempts to synthesize block copolymers in hydrocarbon solvent at 50°C. by the addition of a second monomer to polystyryl anions gave binodal molecular weight distributions. Polystyryl anions were shown to form species inactive toward further polymerization. Gel permeation chromatography also demonstrated the presence of a chemical composition heterogeneity in these products.
The structure of the highly conjugated polymers of dichloroprotoanemonin
Authors: Winston Anthony , Chapman David A.
Published: June 2010

The copolymerization of dichloroprotoanemonin with methyl methacrylate is accompanied by the elimination of half of the chlorine that originally entered the copolymer. This result is consistent with a 1,4‐addition mechanism, the product of which would readily eliminate hydrogen chloride. A strong infrared band at 1770 cm.−1 and a weak band at 1810 cm.−1 indicates that the loss of hydrogen chloride proceeds primarily by 1,4‐elimination but to a small extent by 1,2‐elimination. The copolymerization of dichloroprotoanemonin with styrene results in the elimination of 10 to 20% of the total chlorine that entered the copolymer. Infrared bands at 1765 and 1800 cm.−1 reveal the presence of both conjugated and nonconjugated lactone carbonyl groups. Treatment of the copolymer with hot pyridine resulted in further elimination, up to about 30% of the total chlorine. The decrease in the intensity of the 1800 cm.−1 band relative to the 1765 cm.−1 band as a result of the pyridine treatment confirmed the conversion of the nonconjugated structure into the conjugated one. The failure to achieve 50% elimination indicates that in the styrene case copolymerization may have occurred in part by 1,2‐addition, the product of which would not be expected to lose hydrogen chloride. These results suggest that the ratio of 1,4‐ to 1,2‐addition may depend in part upon the nature of the comonomer. Thermal homopolymerization of dichloroprotoanemonin at 210°C. results in a solid, black polymer, insoluble in the common solvents. The elimination of 76% of the total chlorine suggests that under the conditions of the polymerization the lactone ring opens, giving an α‐chloroketone, which then undergoes further elimination.
Polymerization of methyl methacrylate initiated by a photosensitive complex of tetrahydrofuran‐maleic anhydride in paraffin mixture
Authors: Berger J. , Lazár M.
Published: June 2010

We investigated the polymerization of methyl methacrylate, initiated by decay products of the complex formed by maleic anhydride and tetrahydrofuran and by the action of visible light. The polymerizations were effected in solid and melted paraffin at temperatures of 6 to 60°C., mostly with an 80% paraffin content. The solid‐paraffin mixtures showed high polymerization rates, a higher efficiency of photoinitiated polymerization, and an entire lack of thermal polymerization.
Polymérisation de la 4‐Vinylpiridine sur les “Matrices” Polyacides
Authors: Kargina O. V. , Kabanov V. A. , Kargin V. A.
Published: June 2010

La polymérisation de la 4‐vinylpyridine (VP) dans des solutions aqueuses d'un acide polymérique faible – l'acide polyacrylique (PAA) – a été étudiée. On a démontré que lors de l'interaction de la VP avec le PAA une polymérisation spontanée de la VP a lieu. Suite à une extraction on a réussi à séparer la poly‐4‐vinylpyridine obtenue sur PAA. La polymérisation de la VP sur le PAA se produit avec une grande vitesse (le temps de demi‐transformation est de 17 min.). La vitesse de polymérisation Vp de la VP dans les solutions d'acide acétique, qu'on peut considérer comme un modèle de bas poids moléculaire du PAA, est très petite. La Vp de la VP montre une grande dépendance de la grandeur de pH du milieu, pareille au cas de la polymérisation de la VP sur les acides polymériques forts, ce qui peut témoigner de la similitude des mécanismes de ces processus. La polymérisation de la VP dans les solutions aqueuses est accompagnée d'un accroissement du pH du milieu. Empiriquement, il a été établi que la relation entre le degré de conversion et la concentration des ions [H3O+] est donnée par l'expression suivante:

où [H3O+]0 est la concentration des ions [H3O+] au moment initial. On a étudié la polymérisation de la VP sur le PAA partiellement titré par une base non‐polymérisable. On en déduit une conclusion sur le mécanisme de polymérisation de la VP sur le PAA.
Oligoestermaleinates containing isocyanuric rings
Authors: Alaminov H. , Michailov M. , Damianova I.
Published: June 2010

A method of preparing oligoestermaleinates containing isocyanuric rings by copolycondensation of 3‐(N‐2‐hydroxy‐3‐chloropropyl)isocyanurate, compound (II), and of 3‐(N‐2‐hydroxy‐3‐phenoxypropyl)isocyanurate, compound (III), with maleic anhydride alone or in mixtures with aliphatic or aromatic monocarbonic and dicarbonic acids has been developed. The copolycondensations were made with maleic anhydride, with maleic and phthalic anhydride, with maleic anhydride and adipinic acid, with maleic anhydride and oleic acid, and with maleic anhydride and stearic acid and were examined systematically. Oligoestermaleinates obtained from compound (III) have a higher temperature of dropping(dropping point) and a considerably higher thermostability than those obtained from compound (II). The oligoestermaleinates obtained from compound (II) with maleic anhydride and stearic or oleic acids are soluble in styrene and aromatic hydrocarbons; those obtained with the other substances are partially soluble in styrene. All those obtained from compound (III) are soluble in styrene. The isocyanuric oligoestermaleinates synthesized are compatible with the commercial oligoestermaleinates, such as those from ethylene glycol, diethylene glycol, and propylene glycol, and with their styrene solutions. The hardened isocyanuric oligoestermaleinates have a considerably greater thermostability than commercial oligomers hardened under the same conditions on an ethylene glycol, diethylene glycol, propylene glycol, or maleic anhydride base. The crosslinked polymers are flame‐resistant.
Obtention de membranes semi‐perméables à propriétés remarquables par le greffage radiochimique de films de polytetrafluoroéthylène
Authors: Bex G. , Chapiro A. , Huglin M. B. , Jendrychowska‐Bonamour A. M. , O'Neill T.
Published: June 2010

Semipermeable membranes were prepared by grafting in the bulk Teflon films with acrylic acid, 4‐vinyl pyridine, and both monomers together by a method of successive grafting. Some kinetic features of these reactions are described. The swelling of the grafted membranes was investigated. In the case of vinylpyridine grafts the swelling properties were also examined after quaternization of the pyridine groups by HCl. A wide variety of membranes can be prepared by the methods described. These membranes exhibit excellent mechanical properties, even in the swollen state, and withstand remarkably well various corrosive media.
Thermodestruction and thermooxidative destruction of polyurethanes
Authors: Tarakanov O. G. , Orlov V. A. , Beljakov V. K.
Published: June 2010

It has been shown that the mechanism of destruction of the urethane group is determined by the structure of the starting components. The electron‐donating properties of the radical attached to the isocyanate group favor dissociation of the urethane group into isocyanate and alcohol, and electron‐accepting ones favor splitting of the urethane group into CO2 and amines. The effect of the alcohol radical is quite contrary to the effect of the isocyanate radical: the electron‐donating properties of the radical favor splitting into CO2 and amines, and the electron‐accepting ones favor dissociation of the urethane group into isocyanate and alcohol. The study of the effect of the foam‐forming catalysts on polyurethane destruction has shown that triethylenediamine and stannous dioctoate slightly accelerate the destruction processes. Being the catalyzer of the hydrolytic splitting, tin diethyl dicaprilate greatly accelerates the destruction in the presence of moisture only. It has been shown that urethane and urea groups of toluene diisocyanate polyurethanes improve the polymer stability toward thermooxidative destruction. In the course of the thermooxidative destruction of polyurethanes based on poly(oxypropylene) glycol the chain‐radical process of oxidation of the polyether unit of a macromolecule occurs.
Thermodynamic equilibrium in the system macromolecular coil–binary solvent
Authors: Pouchlý Julius , živný Antonín , Šolc Karel
Published: June 2010

Thermodynamic conditions of an equilibrium between a swollen coil and a solvent outside the coil, established in a dilute solution of a polymer in a binary solvent, are expressed in terms of quantities related to the unit volume. The impossibility to correlate unambiguously preferential sorption with the concentration change of overall sorption is discussed by means of an analogy of Gibbs adsorption equation. Equations expressing the preferential sorption of one of the components in the coil and the overall swelling of the coil in terms of partial derivatives of the free enthalpy of mixing with respect to composition are derived. These equations facilitate the calculation of preferential and overall sorption from theoretical or semiempirical relations expressing the composition dependence of ΔGM, the free enthalpy of mixing. The application is shown on a treatment of data obtained by the measurement of dialysis equilibrium and intrinsic viscosity in the system polymethylmethacrylate–benzene–methanol. The possibility of generalization of the equations derived to the case of osmotic and vapor‐pressure equilibrium in dilute solutions of a polymer in a binary solvent is pointed out. The relation of the equations for osmotic equilibrium to the Scatchard equations is discussed as well.
An estimation of the polydispersity of fractions by means of the mathematical fractionation method
Authors: Bohdanecký Miloslav
Published: June 2010

The method of mathematical fractionation was used to estimate the values of the polydispersity index (u = Mw/Mn) of the fractions obtained from a polymer with the Schulz‐Zimm distribution of molecular weights. A general correlation of u values with the fraction size and phase volume ratio was established. A minimum was found in the dependence of the polydispersity index on the fraction size (at about 30–40%). On the basis of these calculations conditions could have been predicted for fractions with u = 1.1 to be obtained in a larger amount (20–30% by weight of the original polymer).
The effect of excluded volume on chain dimensions
Authors: Alexandrowicz Z.
Published: June 2010

Excluded volume‐interactions are treated in terms of the Gaussian probabilities for intersegmental contacts, as obtaining in equivalent chains consisting of links expanded by the interactions but otherwise obeying the random‐flight statistics. The linear development of the interaction energy exponent into the contact probabilities is (a) conducted sequentially segment by segment, so that the “chain connectivity” is duly preserved (difference from Flory), and (b) cast into a formula that uses Gaussian expressions only for the contact probabilities; the use of the Gaussian expression for the distribution of the end‐to‐end distance, which is known to be non‐Gaussian, is, however, avoided (difference from Fixman). An integral equation is derived, describing α(z) by a line which initially, up to α2 < 4, closely resembles the line derived by Fixman but thereafter diverges increasingly, the asymptotic result being α ≈︁ z5½−2 = z0.236….
Grafting acrylic acid to starch by preirradiation
Authors: Reyes Zoila , Syz Martin G. , Huggins Maurice L. , Russell C. R.
Published: June 2010

The grafting of acrylic acid (AAc) to starch was investigated with gamma‐pre‐irradiated starch and aqueous solutions of AAc. The rate of grafting increased initially with time, then decreased, and approached zero when the percentage grafting reached a maximum value. At a given radiation dose the rate of grafting was proportional to the first power of the concentration of irradiated starch and to the 1.5 power of the initial concentration of AAc. Solvent effects on degree of grafting, molecular weight, and number of grafted branches were evaluated. Higher degrees of grafting were achieved with electron‐irradiated starch at radiation doses lower than those used with gamma rays.
A new technique for polymer grafting
Authors: Bamford C. H. , Duncan F. J. , Reynolds R. J. W. , Seddon J. D.
Published: June 2010

Initiation of free‐radical polymerization by metal carbonyl–organic halide systems has been extended to the case in which the halide component is a N‐halogenated amide or alkylamide. Evidence is presented to show that the nitrogen atom becomes attached as a terminal group to the polymer chain. The halogenated amide group may form an integral part of a polymer. Thus, N‐halogenated polymers may be used with metal carbonyls as initiating systems, so that this technique provides a new means of grafting vinyl polymers on to preformed chains containing CONH groups. Data presented for the grafting of a number of vinyl monomers on to polyamides, polypeptides, and natural proteins enable a detailed mechanism of grafting to be deduced.
Thermally stable amide–bithiazole ordered copolymers
Authors: Preston J. , Black W. B.
Published: June 2010

Several thermostable ordered amide–bithiazole copolymers were prepared by low‐temperature solution polycondensation of aromatic diacid chlorides with bis(aminophenyl)bithiazoles. Films were readily prepared from all of these polymers, and a fiber was prepared from one of them. The polymer from isophthaloyl chloride and 4,4′‐bis(4‐aminophenyl)‐2,2′‐bithiazole was studied in the most detail. Unlike arylene–bithiazole polymers, which are soluble only in concentrated sulfuric acid and the like, this polymer is readily soluble in dimethylacetamide containing 5% dissolved lithium chloride, giving solutions suitable for film and fiber formation. The facile solubility of this amide–bithiazole polymer is attributed to the presence of the amide bonds. Crystalline fibers were spun from the dimethylacetamide–lithium chloride solution of this polymer; they had a tenacity of 140,000 psi (7.8 g./den.) at room temperature and a tenacity of 38,000 psi (2.1 g./den.) when measured at 450°C. The fiber undergoes a weight loss of only 10% on heating up to 490°C. in nitrogen at a rate of 15° C./min. All of the ordered amide–bithiazole copolymers developed a pink‐brown color upon exposure to light.
Study of wall effect in flow of polymer solution in capillary
Authors: Mineshita Takeshi , Watanabe Takehiko , Ono Sǒzaburo
Published: June 2010

The flow behavior of a solution of poly(vinyl pyrrolidone) (Mv, 1.0 × 104−9.0 × 105) has been studied at 35°C. in pure water, in 0.25M MgCl2 aqueous solution, in n‐propanol, and in water‐n‐propanol at various concentrations (0.5‐1.5 g. per 100 ml.). The measurements were carried out with a Maron‐Belner low‐shear capillary viscometer with various capillary bore sizes (radius R, 0.0190–0.0761 cm.) within the range of shear stress, 0.2–20 dynes/cm.2 at the capillary wall. The viscosity is 10–30% lower in the smallest capillary bore than in the largest one at the same shear stress. This phenomenon may be attributed to a steric hindrance of the capillary wall to the thermal motion of the polymer molecules near the wall. The results are represented by the modified Ree‐Eyring generalized flow formula, for a flow system containing one Newtonian flow unit and one non‐Newtonian unit, which includes the new additional terms dependent on the capillary bore size. Furthermore, by assuming the existence of wall layer (of thickness d) in the liquid flowing in the capillary tube an equation of the viscosity was derived, and by combining this equation with the aforementioned equation a calculation of the thickness d, where the rate of shear tends to infinity, was attempted.
Elastomers based on cellulose fibers
Authors: Nakamura Yoshio , Negishi Michiharu , Kakinuma Toshiko
Published: June 2010

To synthesize a new type of elastomer based on cellulose fiber, the introduction of intermolecular crosslinkage with formaldehyde, decrystallization or disorder with ZnCl2 swelling, and grafting with acrylate having a homopolymer second‐order transition temperature below room temperature were tried on the viscose rayon fiber. First, graft copolymerization with MA, EA, and BA was carried out in an aqueous emulsion system by the ceric ion method. It was found that the breaking elongation and elastic recovery of EA‐grafted fibers were remarkably superior to those of fibers grafted with the other monomers. Grafting with EA was carried out on formalized fibers with and without preswelling by concentrated ZnCl2 solution. The grafted fibers after formalization revealed typical rubber elastic behavior over several hundred per cent graft‐on. Breaking elongation was much increased by the swelling treatment after formalization. The crystallinity of the cellulose parts in the grafted fibers was decreased by the swelling pretreatment, being hardly changed by increasing the extent of grafting. The degree of orientation of the cellulose parts was decreased by increasing the extent of grafting, especially in the case of swelling before grafting. From these results it was concluded that the flexible graft parts correspond to soft segments and the rigid cellulose parts reinforced by crosslinkage correspond to hard segments, and that in this way elastomeric behaviors is developed.
Solid‐state polymerization in glassy state at low temperature
Authors: Tabata Yoneho , Ishigure Kenkichi , Fujita Yoshio , Oshima Keichi
Published: June 2010

The polymerization of various monomers in the glassy state was investigated at low temperatures and compared with polymerization in the crystalline state. It was found that acrylonitrile can polymerize in the glassy state in 2‐methyltetrahydrofuran via an anionic mechanism, and the rate of polymerization is much faster in the glassy state than in the crystalline. On the other hand, it was observed that acrylonitrile can be copolymerized with vinyl acetate in glassy mixtures of the two monomers over a wide range of monomer concentrations at low temperatures, below about −160°C. From the monomer reactivity ratio of two monomers in the two component system the polymerization is believed to proceed via a radical mechanism. It was also found that propylene oxide can polymerize only in the glassy state, and the rate of polymerization is quite rapid in matrices of methylene chloride. It was suggested from the effect of various additives on the polymerization that the polymerization proceeds via a cationic mechanism.
Synthesis of poly(ethylene 1,2‐diphenoxyethane‐p,p′‐dicarboxylate) and its properties as a fiber
Authors: Morita Minoru , Yamada Tsuyoshi , Kubo Teruo , Mihara Shigeru , Okajima Saburo
Published: June 2010

The synthesis of poly(ethylene 1,2‐diphenoxyethane‐p,p′‐dicarboxylate) and its properties as a fiber is reported. The polycondensation and properties of polyester (polyethylene terephthalate) and polyetherester (PEBC; half the ester linkage of the original polyester was replaced by ether linkage) were compared. It was concluded that (1) polycondensation reaction of both polyester and polyetherester proceeds under the same conditions, and polyetherester is not easily stained on account of its good thermal stability, (2) almost the same values were obtained for heat of fusion and fusion entropy of each polymer, (3) polyetherester is highly superior to polyester in stability to hydrolysis, (4) there is not much difference between the two fibers in crystallinity, (5) low elongation and high Young's modulus filament was obtained from polyether at high draw ratios, and (6) polyetherester is highly superior to polyester in dyeing affinity. These characteristics of polyetherester were considered to be based on the fact that half the ester linkage of polyethylene terephthalate was replaced by ether linkage.
The diethylzinc–L‐α‐amino acid systems as catalysts for the asymmetric‐selection polymerization of propylene oxide
Authors: Furukawa Junji , Kumata Yoshiyuki , Yamada Koji , Fueno Takayuki
Published: June 2010

The binary systems consisting of equimolar amounts of diethylzinc and L‐α‐amino acids were found to be effective as catalysts for the asymmetric‐selection polymerization of propylene oxides. Various L‐α‐amino acids were compared, in order to investigate the influence of the spatial character of the asymmetric center of catalysts on their efficiencies for asymmetric selection. It was found that all the L‐α‐amino acids investigated allow ( – )‐propylene oxide to polymerize preferentially over the (+) enantiomer, irrespective of the sign of their specific rotations, [α]D. For each amino acid the [α]D value of recovered monomer was proportional to –1n (1 – x), where x is the extent of polymerization. The proportionality factor, which may be regarded as a measure of the relative asymmetric‐selection efficiencies of catalysts, was found to parallel the bulkiness of the alkyl group attached to the asymmetric carbon atom of the amino acids used.
Stereoregular polymerization of optically active monomers with optically active and inactive catalysts
Authors: Matsuzaki Kei , Tateno Noriaki
Published: June 2010

Mixtures of l‐ and dl‐menthyl methacrylates were polymerized with phenylmagnesium bromide coordinated with l‐menthyl ethyl ether, and l‐ and dl‐amylmagnesium bromide as catalysts. The isotacticity of the polymers was decreased by the addition of dl‐monomer into l‐monomer. From the relationship between the decrease of isotacticity and the increase of heterotacticity and syndiotacticity it is deduced that the isotactic sequences in the polymers are composed of either D or L configurations and not mixtures of D and L sequences. The optical activity of the monomer recovered and that of the polymers showed that the preference of one of the enantiomeric monomers over the other in the polymerization did not occur. The polymers prepared with l‐ and dl‐amylmagnesium bromide had the same stereoregularity.
Studies on the charge‐transfer complex and polymerization. XI. Donor‐acceptor interaction in alternating radical copolymerization
Authors: Yamashita Yuya , Iwatsuki Shouji , Kokubo Takashi
Published: June 2010

The microstructure of the copolymer of butadiene with maleic anhydride has been shown by IR spectra to be rich in cis‐1,4 structure (about 70% at 60°C.), whereas the butadiene homopolymer by radical mechanism is rich in trans‐1,4 structure. The copolymer rich in cis‐1,4 structure was also observed in the copolymerization of butadiene with sulfur dioxide, but the copolymers of butadiene with styrene, acrylonitrile, dimethyl maleate, diethyl fumarate, or fumaronitrile were rich in trans‐1,4 structure. Because the free butadiene monomer exists as the transoid structure, the activation of butadiene through the cisoid complex is assumed in the copolymerization with maleic anhydride. This shows that the donor‐acceptor interaction between butadiene and maleic anhydride or sulfur dioxide participates in this alternating radical copolymerization, and the small alternating tendency observed between butadiene and acrylonitrile, maleate, or fumarate comes from the stabilization of the transition state by electrostatic interaction or electron transfer.
Structure and physical properties of polyurethanes
Authors: Tanaka Takehide , Yokoyama Tetsuo
Published: June 2010

The relations between structure and physical properties of polyurethane elastomers, particularly elastic properties, were studied. Polyurethanes with various structures were prepared by a prepolymer technique. Among the conceivable structural factors the substituted urea group, which was introduced by the use of a diamine‐type curing agent, had a remarkable reinforcing effect. This was attributed to the strong hydrogen‐bonding effect between urea groups. In this connection, softening occurred during repeated deformation of diamine‐cured polyurethane elastomers. It was proved that this is due not to the melting of crystallite but to the slip of hydrogen bonding between urea groups. On the other hand, urea groups did not have much influence on equilibrium rubber elasticity. The contribution of the force caused by the internal energy to the total force was independent of curing agents, being determined by the principal segments of network chains.
Rheo‐optical behavior of isotactic and linear atactic poly‐alpha‐olefins in solution
Authors: Philippoff W. , Tornqvist E. G. M.
Published: June 2010

The influence of the stereochemistry of the monomer on the optical properties, namely the stress optical coefficient C of polymer solutions has been investigated by using polymers of α‐olefins in solution. Polymers of α‐olefins up to and including polyoctadecene were used. The experimental results are shown in Figure 1 on the example of a 5% solution of Poly(Decene‐1). The three properties, the degree of birefringence Δn, the extinction angle χ and the viscosity η were measured over a range of rates of shear D. These measurements are then combined to the stress optical coefficient C: C = Δn sin 2x/2τ, which, as is well known, is independent of the molecular weight, concentration, and rate of shear (τ shear stress = η.D). For Poly(Decene‐1) the results are shown in Figure 2. All the results obtained are shown in Figure 3 where C is plotted versus n, the number of carbon atoms in the side chain for two main‐chain C atoms. The result is a linear relationship between C and n giving an isotropic polymer at n = 4. This means that the side chain atoms contribute only 1/2 the value of the main‐chain atoms towards the anisotropy of the molecule. This is believed to be the result of the free rotation of the molecular units against each other and allows a number of polymers including polyisobutylene to be discussed in a uniform manner. Equally the influence of the tacticity was established, that is, a maximum occurs for polypropylene and it becomes nearly negligible for polyhexene‐1 and higher polymers. Having now a well‐established series of poly‐α‐olefins, and corresponding C values, one can use these data to check the stereochemistry of further polymers.