bluuebunny/crossref_metadata_2025 huggingface dataset:
Methods of single fiber evaluation
Authors: Schulman Stanley
Published: June 2010

Research and development directed at improved fibers and fibrous materials normally utilizes relatively conventional apparatus for fiber, yarn, and fabric characterization. When desired, material properties are dictated by end‐use requirements which represent extremes in temperature resistance, strength‐to‐weight ratio, high impact velocities, etc.; novel equipment and techniques are likely to be necessary for such research. This is the case with the Air Force's effort in the area of materials evaluation. Techniques now in use are, for the most part, suitable for materials being researched, but improvements must be made for the next generation of fibrous materials. New methods of characterization will be needed to overcome shortcomings of present techniques and to adapt to an ever‐increasing requirement for the properties of all types of materials. For example, evaluation of thermally stable abrasion‐resistant finishes will require long‐term, high temperature flex testing. The laboratory equipment herein described represents a small fraction of the total in‐house capability of the Air Force Materials Laboratory for conducting exploratory research and development on advanced fibrous materials for aerospace systems.
Continuous filament ceramic fibers via the viscose process
Authors: Wizon I. , Robertson J. A.
Published: June 2010

The process for making AVCERAM (FMC Corporation) fibers involves incorporation of lattice‐forming inorganic materials, molecularly dispersed in a viscose batch, spinning, weaving, or winding the resultant fiber on conventional, production‐type machinery, and firing the fiber or fabric so as to retain the unique, single, or multicomponent continuous filament structure. The versatility and practicality of the process give promise for new and unusual fiber compositions and fabric constructions in quantities and at prices attractive to the ultimate consumer. Of particular interest is the indication that in composite applications the carbon‐silica fabric exhibits some advantages of both carbon and silica reinforcemeuts which may be partly due to in situ conversion to silicon carbide.
Gel permeation chromatography: Its inception
Authors: Moore J. C.
Published: June 2010

The early history of the author's contributions to the origin and development of gel permeation chromatography is recounted. Previous experiences with chromatography and with polymer characterization were of value at the inception. Early problems involved the control of gel structure and particle size, column‐packing techniques, design, and test methods for the instrumentation. Aid from co‐workers is acknowledged.
A method for high‐temperature exclusion chromatography of polyethylenes
Authors: Ross J. H. , Casto M. E.
Published: June 2010

Soft polystyrene gels compact and degrade at high temperatures. Therefore, recalibration at frequent intervals is required. Suitable solvents for swelling the gel appropriately are needed. Although the universal applicability of differential refractometry as a detector for exclusion chromatography is desirable, in certain instances, when demands are high, it has several drawbacks. Among these are its extreme sensitivity to temperature changes, the variation of refractive index with molecular weight, and the lack of sufficient sensitivity to certain polymers. The system described herein, employing infrared spectrophotometric monitoring and porous glass beads as column packing, was developed to circumvent the problems inherent in the commercially available gel permeation chromatograph.
Application of gel permeation chromatography to crosslinking in irradiated paraffins
Authors: Salovey R. , Falconer W. E. , Hellman M. Y.
Published: June 2010

Gel permeation chromatography is shown to be a feasible technique for the absolute measurement of crosslinking yields in irradiated, high molecular weight paraffins. For solid n‐eicosane (n‐C20 paraffin) the yield of radiation‐induced crosslinking is independent of dose with a G value of 1.0 ± 0.1, derived from gel permeation chromatography, and of 0.9, from gas chromatography. A radiolytic yield of dimer in liquid n‐eicosane of 1.5 ± 0.1 with no evidence of dose dependence is derived from gas chromatography. However, an increase in crosslinking yield with dose for irradiated liquid n‐eicosane is inferred from gel permeation studies. The yield of radiation‐induced crosslinking in solid n‐hexatriacontane (n‐C36 paraffin) is about 0.8, with little dose dependence, from gel permeation chromatography.
The investigation of parallel‐column systems in gel permeation chromatography
Authors: Alliet David F. , Pacco Jeanne M.
Published: June 2010

Gel permeation chromatography (GPC) is a new technique for characterizing the molecular weight distribution of polymeric materials. The separation of species is based upon the depth to which each molecular species in a polymer will diffuse into a crosslinked polystyrene gel. The selection of the proper gel to use for separating molecular species depends upon the degree of homogeneity in a polymer. For a better understanding of the separating ability of the various gels an investigation was carried out, to establish the molecular weight limitations of gel porosities in the 105, 104, and 103 A. ranges. The study was carried out with a series of anionically polymerized, narrow molecular weight, standard polystyrenes, which have been characterized by light scattering and membrane and vapor‐pressure osmometry. Molecular weight distribution curves, called chromatograms, are characteristically described in terms of average molecular weights: weight‐average molecular weight Mw and number‐average molecular weight Mn. The range of distribution ratios Mw/Mn is quite large in synthetic polymers. To give the weight average or number average from a GPC chromatogram, the average chain lengths have to be multiplied by a Q factor, the molecular weight per angstrom of equivalent straight‐chain length. The results for narrow molecular weight distributions show that the separating ability of the 105, 104, and 103 A. gels is limited to specific ranges of molecular weight. The 104 A. column system gave the best correlation of results between GPC and the absolute methods.
Characterization of HB polymer with gel permeation chromatography
Authors: Law Ronald D.
Published: June 2010

A low molecular weight liquid polymer, polybutadiene‐acrylic acid‐acrylonitrile (HB), is used as a binder‐fuel fraction in solid composite propellants. The molecular weight distribution of this polymer, previously undetermined and uncontrolled, is being determined routinely with gel permeation chromatography (GPC). Analytical conditions are described and the precision and accuracy of the determination are discussed. Correlation of GPC determinations of low molecular weight materials in HB polymer (100 through 500 molecular weight range) with final propellant physical properties is statistically significant. These low molecular weight materials are being characterized, and studies of their role in determining propellant mechanical properties are being conducted. Use of a Waters Model 100 instrument for fractionating and isolating low molecular weight species in the molecular weight range of 100–500 yielded milligram quantities. Analysis of these materials with semimicrotechniques has permitted tentative indentification of the molecular species present.
Analysis of carboxy‐terminated polybutadienes by GPC: A preliminary investigation
Authors: Screaton R. M. , Seemann R. W.
Published: June 2010

The use of gel permeation chromatography (GPC) for the rapid determination of molecular weight distributions of carboxy‐terminated polybutadienes is demonstrated. Whole polymer samples and fractions prepared by elution fractionation were characterized by GPC and viscosity measurements with two different solvents for each method. Variable functionality (COOH group) dependence of the polystyrene gel columns is shown. Thus there is a need to pretest the columns for COOH absorption before use with materials containing carboxylic acid. Effects of sample size and also of carboxy termination as compared with hydrogen termination are discussed. Correlations between tetrahydrofuran and CHCl3 chromatograms are given. As a first approximation the Q factor of 16 is indicated for molecular weight determination from a standard polystyrene calibration in both tetrahydrofuran and CHCl3.
Préparation de Macromolécules à Structure en Etoile, par Copolymerisation Anionique
Authors: Zilliox Jean‐Georges , Rempp Paul , Parrod Jacques
Published: June 2010

Star‐shaped macromolecules have been obtained by anionic block copolymerization of a monofunctional monomer and a divinyl compound with cumylpotassium or butyllithium as initiator. The polymer molecule is a crosslinked nodulus, to which n linear, solvated chains are attached. The shielding effect of these chains is such that more than 40% difunctional monomer is necessary to induce gel formation in the reaction medium. Star‐shaped polystyrenes, polyisoprenes, polyvinylpyridines and poly(methyl methacrylate) were obtained by this method, the crosslinking agent being divinylbenzene or glycol dimethacrylate. The individual branches of the star molecules may be considered identical, but a polydispersity arises from the fact that within a sample the number of branches of the star molecules fluctuates appreciably. Fractionation remains possible, though it is not very easy to get monodispersed samples. The molecular dimensions of the star‐shaped polymers, as determined from their intrinsic viscosities or from their radii of gyration, are smaller than those of the corresponding linear polymers, and this may be considered a proof of their highly branched structure.
The numerical evaluation of the composition of products in polymer analogous reactions
Authors: Szántó J. I.
Published: June 2010

In chemical reactions of polymers the functional groups on the chains are gradually converted, and so the eventual structure of the products depends on the degree of conversion. The conversion of polymer analogous reactions is generally not complete, and so copolymers are formed from homopolymers (as well as from copolymers) by chemical transformations. The elementary analysis of products obtained by polymer analogous reactions gives useful information primarily on the conversions in the reactions. In a set of consecutive reactions the conversion in a given reaction depends on the degrees of conversion in the previous steps. In the numerical evaluation of analytical results mathematical formulae based on stoichiometric principles have been used. In some instances theoretical elementary compositions were computed on the basis of a known degree of conversion and the results compared with the measured values. The degrees of conversions in simultaneous polymer analogous reactions may be characterized by a matrix equation having the form Aa = c, where the values of a, a vector characterizing the conversion, may be computed from the elementary compositions and from the initial conditions. By a comparison of computed and measured values some conclusions on the direction of the reactions may be drawn.
Relative reactivity of initiator radicals in polymerization of vinyl monomers
Authors: Pavlinec J. , Lazár M.
Published: June 2010

Relative reactivities of primary initiator radicals in substitution reactions with an atactic polypropylene are compared with their reactivities in additions to styrene and methyl mechacrylate in the system monomer–polymer–initiator. For calculations the results of a kinetic analysis of reactions in the system were used. The calculations were made from determination of the weight fraction of grafted branches per total amount of newly formed polymer and from kinetic constants of polymerization of the monomer. It was possible to determine the relative reactivities of different monomers in relation to radicals of the same initiator. The relative reactivities of styrene and methyl methacrylate to benzoyloxy radical were 1:0.125 at 50°C. The ratio of the reactivities of the same monomers to a cumyloxy radical was 1:0.04 at 130°C. The transfer constant of polystyrene and poly(methyl methacrylate) radicals with atactic polypropylene at 50°C. were C = 2.5 × 10−6 and C = 4 ×; 10−6, respectively, and at 130°C. they were C = 3 × 10−5 and C = 4.2 × 10−5, respectively.
Sur un Cas Particulier de Réarrangement Intramoléculaire des Copolymères Séquencés en Solution
Authors: Brendle M. , Koeppel R. , Banderet A.
Published: June 2010

For some polystyrene–poly(methyl methacrylate) block copolymers whose second blocks are prepared in a free‐radical reaction, a decrease in intrinsic viscosity appears by simple heating in a solvent. Contrary to our previous explanation, this decrease is now explained as related, not to a cleavage of a covalent bond, but to an intramolecular rearrangement of the structure. This was shown by viscosity light‐scattering and gel chromatography measurements. It seems that the free‐radical polymerization leads to an unstable structure, which is transformed into a more stable one during the heating. It is possible that in the first form the different blocks are intermingled and that they become segregated in the stable form. Under the same conditions no variation appears when the block copolymers are entirely formed by an ionic mechanism. In this case we may believe that they are already formed in the stable structure.
Polyaniline compounds. II. The linear oligoaniline derivatives tri‐, tetra‐, and hexaanilinobenzene and their conductive complexes
Authors: Honzl J. , Tlusťáková M.
Published: June 2010

Oligomeric oligoaniline derivatives of diethyl Δ1,4‐dihydroterephthalate (V–VIb–d) of diethyl terephthalate (VIIb–d) and linear oligoanilines (Ib–d) were synthesized. Ultraviolet spectra and polarographic half‐wave potentials corresponding to the first degree of oxidation of linear oligoanilines of type (I) were studied, their iodine complexes prepared, and their electric and magnetic properties studied. Increase of chain length of the base causes increase of λmax of ultraviolet bands, decrease of ionization potential, and increase of electric conductivity of iodine complexes in solid state. The properties of the five‐membered oligomer (Ic) differ only slightly from analogous properties of the seven‐membered oligomer (Id); the same holds in the case of their iodine complexes. Such substances may be regarded as in some respects models of a linear polyaniline polymer or its complexes.
Influence of the structure of polypropylene fibers on the rate of grafting and the structural changes caused by grafting
Authors: Odor Louise
Published: June 2010

An investigation of the relation between the structure of polypropylene fibers and grafting shows that the grafting process takes place in the amorphous phase of the fiber up to 50% grafted polymer content and that the crystals are destroyed only above 75%. This is proved by the diffusion constant of the monomer in the grafted fibers and also by x‐ray diffraction. The studies of grafting rates and diffusion rates of monomers show that the differences in diffusion rate of monomer in fibers of different structures do not affect the rate of chain growth but do affect that of chain termination. The initial rate of grafting is affected by the amount, orientation, and segment mobility of the amorphous part. The chains of the basic polymer are disoriented by grafting, which is indicated by the sudden decrease of birefringence and crystalline orientation. The tensile strength of grafted fiber decreases as the structure changes.
Macropolymerization of Polyethylene by Anhydrous Alkalis and Effective Inhibition of Polyethylene Destruction at High Temperatures
Authors: Paushkin J. M. , Losev G. P.
Published: June 2010

The polyolefin transformation at 200 to 450°C. in the presence of alkali metals and their hydroxides is described. A twofold to fourfold increase of the molecular weight of polyethylene in contact with alkali melts is observed at 200 to 300°C. This phenomenon was given the name “macropolymerization” of polyolefin. At 350 to 450°C. a high retarding action of polyolefin destruction is observed.
On the structure and solution properties of radically polymerized poly(vinyl chloride). III. Discussion of some anomalies
Authors: Kratochvíl P. , Bohdanecký M. , Šolc K. , Kolínský M. , Ryska M. , Lím D.
Published: June 2010

Dilute poly(vinyl chloride) solutions exhibit a number of anomalies, such as dependence of solution properties on polymerization conditions, strong aggregation in some solvents, low solubility of the fraction with the highest molecular weight, and considerable polydispersity of fractions with higher molecular weights. On the basis of the authors' work and the literature data a survey of these anomalies is given, followed by an attempt to explain them from a unitary viewpoint. Most of the phenomena mentioned can be ascribed to the enhanced crystallization capability of syndiotactic sequences in the chain.
Polymerization of methyl methacrylate by alkali metal compounds
Authors: Lím D. , Čoupek J. , Jůzl K. , Báča J. , Sýkora S. , Schneider B.
Published: June 2010

The structure of poly(methyl methacrylate) prepared by anionic polymerization was followed. Compounds of lithium, sodium, and potassium were used as initiators. The influence of the structure of the initiator and its amount and of the monomer concentration, conversion, and temperature on the structure of the polymer in the polymerization without the presence of complexing solvents was studied. By analysis of NMR spectra tacticity and stereoblock structure, characterized by the parameter η = pis/(pis + pss), was determined. The results made possible the conclusions concerning the factors controlling the growth reaction.
Influence of branching length on structuration and crystallization of stereoregular and irregular polymers
Authors: Platé N. A. , Shibaev V. P. , Petrukhin B. S. , Kargin V. A.
Published: June 2010

Stereoregular and irregular long‐side‐chain poly(alkyl acrylates) and poly(vinyl esters) have been obtained. A study of the structure these polymers showed that their crystallization took place as hexagonal cells, regardless of the stereoregularity. Studies of the effect of polymer branching length on supermolecular structure have shown that the minimal length of side chain required for crystallization probably is 10 carbon atoms, regardless of the stereoregularity of the backbone chains.
Amine salts of polypyromellitamic acids
Authors: Reynolds R. J. W. , Seddon J. D.
Published: June 2010

The pyromellitamic acid prepared from pyromellitic anhydride and p:p′‐diamino‐diphenyl ether (the precursor of the heat‐resistant polyimide) can be dissolved in aqueous organic bases to form solutions which, unlike those of the free acid dissolved in highly polar organic solvents, are resistant to hydrolytic degradation. These solutions on drying and heating evolve the base to yield the pyromellitimide polymer and can be employed in fabrication processes, particularly for the formation of films and surface coatings. Data are presented on the properties of the solutions and derived films.
The influence of complexing agents on the polymerization of vinyl and allyl monomers
Authors: Zubov V. P. , Lachinov M. B. , Golubev V. B. , Kulikova V. F. , Kabanov V. A. , Polak L. S. , Kargin V. A.
Published: June 2010

Acceleration of photo‐induced polymerization of methyl methacrylate (MMA) has been found in the presence of AlCl3 and AlBr3. On the basis of the kinetic data it has been supposed that at lower concentrations of AlX3 ([AlX3]/[MMA] ≤ 0.1) the role of the complexing agent is reduced to acceleration of propagation with complexed radicals. The peculiar behavior of these radicals has been revealed by ESR. We have proposed that the mechanism of activation of propagation by the complexing agent consists of electron transfer from the radical to the adding monomer molecule through the metal atom of the complexing agent. At higher concentrations of the complexing agent its role is also reduced to ordering of the monomer molecules into mobile organized arrays. Acceleration of radical polymerization of allyl acetate and allyl alcohol has also been found in the presence of ZnCl2. The mechanism of acceleration involves activation of allyl radicals of chain transfer and formation of mobile, organized arrays of the monomer molecules.
Alkaline polymerization of caprolactam. XXIX. Mechanism of chain growth in anionic lactam polymerization
Authors: Šebenda J.
Published: June 2010

When butyrylenantholactam is used as acyllactam and sodium caprolactam as the source of lactam anions, the position of the lactam anion incorporated in the first chain‐growth step may be determined. To avoid the interference of transacylation leading to butyrylcaprolactam and sodium enantholactam the reaction was stopped at very low extents. Determination of the structure of the reaction products revealed that the incorporated caprolactam anion is present as the end‐standing acylated lactam unit and the enantholactam unit is inside the chain. This position of monomer units proves that the chain‐growth reaction consists of acylation of lactam anions by the cyclic carbonyl group of an acylated lactam and not by insertion into imide or β‐ketoamide groups. At 50°C. the rate of transacylation was found to proceed 5 times faster than the chain growth; the rate of condensation reactions of imide groups amounts to 20% of the rate of the chain‐growth reaction.
Some new redox resins
Authors: Manecke Georg , Bourweig Gerhard , Creutzburg Klaus , Ramlow Gerhard
Published: June 2010

With the aim to synthesize chemically stable redox polymers the following investigations have been performed. Homopolymerization investigations of nucleus‐methylated 1‐vinyl‐3,6‐diacetoxybenzenes showed that a methyl group in the 5 position seems to have a severe negative effect on the polymerizability of vinyl hydroquinone compounds. Sulfonated copolymers of the vinyl hydroquinone derivatives with styrene and DVB having ion exchange capacities of 3.4 meq./g., redox capacities of 2.1 meq./g., and midpoint potentials of 520 mv. (pH 0.36) were prepared. 2,3‐Dimethyl‐2,3‐epoxy‐5‐vinyl naphthoquinone‐(1,4) is the only polymerizable derivative of this naphthoquinone. A copolymer of epoxide, methacrylic acid, and DVB was converted to the quinone by reaction with KJ, yielding a redox copolymer with a redox capacity of 2.3 meq./g. Oxidative degradation experiments on sulfonated styrene–DVB cation exchange resins, wherein styrene and DVB are partially replaced by α‐methylstyrene and diisopropenyl‐benzene, showed that the resins become more stable as more tertiary H atoms are substituted by methyl groups. Bead‐shaped and macroreticular redox copolymers of 2‐isopropenyl‐anthraquinone‐(9,10), styrene, or methacrylic acid and DVB were prepared having redox capacities of 2–4 meq./g., ion exchange capacities of 1–4 meq./g., and midpoint potentials of 170 mv. (pH 0.2). Oxidative degradation investigations on the bases of capacity decrease and swelling increase measurements generally showed that these resins can be stabilized if a major portion of tertiary H atoms is replaced by methyl groups.
The dependence of the isotacticity of polypropylene on polymerization conditions
Authors: Keii Tominaga , Soga Kazuo , Go Shigeo , Takahashi Atsushi , Kojima Akira
Published: June 2010

To clarify the stereospecificity of Natta‐type catalysts, the temperature dependence of the isotacticity of a polypropylene has been investigated by using H‐type or A‐type TiCl3 with Al(C2H5)3 or Al(C2H5)2Cl in a study of the kinetic behavior of the polymerization under the conditions T = 30–75°C., P ≈︁ 1 atm., and [Al]/[Ti] = 1. With the use of Al(C2H5)3 the isotacticity increases with a rise in polymerization temperature, and it approaches that of Al(C2H5)2Cl, which is almost independent of the polymerization temperature. On the other hand, with the use of Al(C2H5)3 the number of the polymerization centers decreases with a rise in temperature, while that with Al(C2H5)2Cl remains unchanged. To explain these results, two kinds of polymerization center have been proposed; one is stable at any temperature and produces a higher‐isotacticity polymer, and the other is stable at the higher temperatures and produces a lowerisotacticity polymer. Some solvent effect of the isotacticity has been observed with the use of A‐TiCl3. The isotacticity with A‐TiCl3 decreases by several per cent when n‐heptane is used instead of toluene. This solvent effect has been explained on the basis of the existence of a considerable amount of AlCl3 in A‐TiCl3.
Tear resistance of vulcanized rubber
Authors: Furukawa Junji , Kotani Teizo , Yamashita Shinzo
Published: June 2010

Stress‐strain distributions in the test specimens of various transparent rubber vulcanizates were measured by photoelastic and microscopical techniques. The test specimens were of the size specified in JIS‐K‐6301‐b, which was identical with ASTMD‐624‐54‐C and DIN 53515. The tear resistances of the vulcanizates were calculated by a semitheoretical equation derived by taking the measured strain distributions into consideration. The values thus calculated were found to agree with the experimental data obtained for various vulcanizates except for some of natural rubber compounds.
Chemistry of isocyanic acid and its derivatives. I. Preparation, polymerization, and decomposition of 3,4,5,6‐tetrahydro‐2,4‐dioxo‐2H‐1,3‐oxazines
Authors: Ozaki Shoichiro , Kato Takazo
Published: June 2010

3,4,5,6‐Tetrahydro‐2,4‐dioxo‐2H‐1,3‐oxazine (I) was prepared from isocyanic acid and β‐propiolactone. Its structure was determined by elemental analysis and infrared, NMR, and mass spectroscopy. On heating it gave polyacrylamide with evolution of carbon dioxide. In the presence of sodium t‐butoxide, it gave poly(β‐alanine), acrylamide, and carbon dioxide. The possible mechanism of these reactions is shown by the fact that compound (I) first decomposed, giving acrylamide, and then acrylamide polymerized, giving polyacrylamide in the absence of sodium t‐butoxide or poly(β‐alanine) in the presence of sodium t‐butoxide. 3,4,5,6‐Tetrahydro‐2,4‐dioxo‐3‐phenyl‐2H‐1,3‐oxazine also was obtained from phenyl isocyanate and β‐propiolactone under the same conditions by which compound (I) was obtained.
Studies of the thermosetting reactions of condensation‐type resins
Authors: Ishida Shinichiro , Kaneko Katsumasa
Published: June 2010

The mechanism of the thermosetting reactions of phenol and urea resins was investigated by studying the viscosity of the reaction solution, and the molecular weight, and its distribution during the intermediate stages of the reaction. In the case of phenol resin the viscosity of the reaction solution increased steadily, and the viscosity‐diffusion average molecular weight increased to about 3000 but, after the insoluble fraction was formed, it decreased. On the other hand, in the case of urea resin the variations of the viscosity were strongly dependent on the mole ratio of urea to formaldehyde. That is, if the quantity of formaldehyde was less than 1.6 mole per mole of urea, the viscosity did not increase so much, and a white precipitate was formed, with 2.0 mole of formaldehyde the viscosity increased exponentially, and with 3.0 mole of formaldehyde the viscosity increased just a little and then was constant. Because of the unavailability of suitable solvent the molecular weights were determined only with the water‐soluble fraction.
Stereoregulation in N‐carboxy anhydride polymerization
Authors: Inoue Shohei , Matsuura Kazuo , Tsuruta Teiji
Published: June 2010

Copolymerization of N‐carboxy‐γ‐benzyl‐D‐ and L‐glutamate anhydride was examined in N,N‐dimethylformamide with n‐hexylamine as initiator. Rate increase was observed in the initial stage of polymerization of monomers with 55% and 87% L composition. The occurrence of asymmetric selection of monomer antipode was confirmed by optical‐rotation measurement of the polymers in trifluoroacetic acid as well as by optical rotatory‐dispersion measurement. Observed asymmetric selection and rate increase were discussed in relation to stereoregularity and to helix content of the polymer.
Generation of free radicals at subzero temperatures. II. Polymerization of vinyl chloride with thionyl chloride and hydroperoxides
Authors: Minato H. , Iwai H. , Hashimoto K. , Yasui T.
Published: June 2010

A system consisting of thionyl chloride, t‐butyl hydroperoxide, and methanol generated free radicals near −20°C., and the polymerization of vinyl chloride was initiated efficiently by this system. Various peroxyesters were effective, but di‐t‐butyl peroxide was ineffective. On the basis of the experimental results, the most plausible reaction steps yielding free radicals were the following: (1) thionyl chloride reacts with methanol to yield methyl chlorosulfite, (2) peroxyesters are solvolyzed to produce methyl esters and t‐butyl hydroperoxides, (3) t‐butyl hydroperoxide reacts with methyl chlorosulfite to yield methylt‐butylperoxy sulfite, which decomposes to yield free radicals.
Studies of thermosetting resin. II. Pyrolysis of aromatic amine‐cured epoxy resins
Authors: Sugita Tadao
Published: June 2010

The thermal degradation of bisphenol‐A and three kinds of epoxy resins cured with aromatic amines were studied. The aromatic amine curing agents were m‐phenyl‐enediamine, p,p′‐diaminodiphenylmethane and p,p′‐diaminodiphenyl sulfone. As epoxy resin Epon 828 was used. The sample was pyrolyzed at 500°C. in an electric furnace, and pyrolyzate was examined by gas chromatography and infrared spectroscopy.
Studies of tensile strength, heat‐shrinkage force, and crystallinity of nylon 6 tire cords and nylon 6 films at elevated temperatures
Authors: Fukuhara Setsuo , Suzuki Yasuo , Omote Shigeo
Published: June 2010

Tensile strength and heat‐shrinkage force of nylon 6 tire cords at elevated temperatures were measured. Infrared absorption spectra of nylon 6 films at elevated temperatures were also measured, and the change of the hydrogen‐bonding force was estimated from the shift of the NH absorption band. (1) Increase of heat‐shrinkage force of nylon 6 tire cord at elevated temperatures was related to decrease of hydrogen‐bonding force, which restricted energetic and entropic elasticity. (2) Decrease of tensile strength of nylon 6 tire cords at elevated temperatures was related to decrease of infrared crystallinity and hydrogen‐bonding force. (3) Nylon 6 film with N‐deuterated crystalline regions was prepared and heat‐treated. The shift of the NH band in the amorphous region on elevating of the temperature was greater than that of the ND band in the crystalline region.
Surface treatment of polycarbonate films with amines
Authors: Caldwell J. R. , Jackson W. J.
Published: June 2010

Bisphenol polycarbonates react with primary and secondary amines to form urethane groups by cleaving the molecular chain. The urethane group remains attached to a segment of the polymer molecule. If a diamine or polyamine is used, the polarity of the polycarbonate surface is appreciably increased. The increased polarity imparts new surface properties such as wettability, dyeability, improved adhesion, and increased conductivity.
Poly(vinyl chloroformate) and derivatives: Preparation and properties
Authors: Schaefgen J. R.
Published: June 2010

The polymerization and copolymerization of vinyl chloroformate is described. Polymerization is initiated at 0 and −80°C. with boron alkyls, yielding high molecular weight poly(vinyl chloroformate). The polymer prepared at −80°C. is laterally ordered. The homopolymer is soluble and surprisingly stable to water and can be oriented in fiber or film form. Films of poly(vinyl chloroformate) undergo facile postreaction with compounds with labile hydrogen atoms such as alcohols, amines, and phenols. Aqueous ammonium hydroxide gives a copolymer containing approximately equal numbers of hydroxyl and urethane side groups. With gaseous ammonia a quantitative yield of poly(vinyl urethane) is obtained. Diamines react to give crosslinked polymers. Products are described briefly. The related derivatives of vinyl chloroformate (vinyl cyanoformate, vinyl t‐butyl carbonate, and vinyl urethane) were prepared from vinyl chloroformate. Polymerization of the first two monomers is initiated by tri‐n‐butyl boron; the vinyl urethane polymerizes spontaneously at 100°C. Poly(vinyl t‐butyl carbonate) is crystalline; poly(vinyl cyanoformate) and poly(vinyl urethane) are amorphous.
Chemical modification of cotton with chloroacetamide
Authors: Pierce A. G. , Reinhardt Robert M.
Published: June 2010

Chemically modified cellulosic textile materials have been prepared by treatment of cotton with chloroacetamide in the presence of strong alkali by a variety of techniques. Ether groups bearing carboxyl and amide functions were attached to the cellulose. The effects of process variables on the chemical and physical properties of the products are discussed. These variables include time and temperature of reaction, concentration of reactants, choice of solvent, and method of application. Nucleophilic reaction of cellulose with chloroacetamide introduces carbamoylmethyl ether groups along the polymer chain. In the alkaline reaction media employed the hydrolysis of these substituents proceeds with loss of ammonia, yielding carboxymethyl ether groups. The amount and ratio of the carboxymethyl and carbamoylmethyl substituents introduced can be altered by varying the reaction conditions. In general, low temperature and a high ratio of chloroacetamide to alkali in the reaction medium favor carbamoylmethylation, whereas at higher temperatures the overall reaction kinetics favor amide hydrolysis, and carboxymethylation predominates. Chloroacetamide is an excellent carboxymethylating agent for cellulose; in some instances greater carboxymethyl substitution was achieved with this agent than with chloroacetic acid. Degrees of substitution can be attained that render the cotton soluble in dilute aqueous alkali. However, the original fibrous nature of the cotton was retained even in products with relatively high degrees of substitution.
Reaction of living polystyrene with some natural polymers and their analogs
Authors: O'Malley J. J. , Marchessault R. H.
Published: June 2010

The preparation and characterization of graft polymers of methylated xylan and polystyrene are described. The copolymers were prepared anionically by reaction of polystyrylpotassium with the methyl glucuronate moiety, to give well‐defined comblike structures. Polystyrenes of molecular weight 1,100 and 4,700 were used. The reaction takes place by attack of the polymeric anion at the ester function, which converts it into a ketone. Infrared analysis has confirmed this, since only a ketone absorption band is observed in the grafted products. Evaluation of intrinsic viscosity measurements on well‐defined copolymer fractions was made in terms of branch density, branch length, and backbone molecular weight. These parameters generally affected the viscosity in the manner predicted for homopolymer branched structures. Reactions of the polystyryl anion with a polyester and a polypeptide were also considered. In general, unwanted side reactions were predominant in these systems. However, in the case of one polyester, polypropiolactone, indications are that block copolymers with polystyrene were prepared, but isolation and characterization of the products was not attempted, because of the low molecular weights involved.
Cyclo and cyclized diene polymers. XVII. Styrene–isoprene block and graft cyclopolymers
Authors: Gaylord N. G. , Matyska B. , Kössler I. , Krauserova H.
Published: June 2010

The cationic polymerization of isoprene in n‐heptane at 20°C. with ethylaluminum dichloride as catalyst gave cyclopolyisoprene in low conversion in equilibrium with unreacted monomer and catalyst. The addition of monomer resulted in renewed polymerization and re‐establishment of the equilibrium. Addition of styrene to the dormant polymerization system gave block copolymers and reinitiated isoprene polymerization. The second‐stage isoprene polymerization curve duplicated the initial curve, and an equilibrium was again established. The isoprene units in the block copolymer with styrene contained no linear forms and were present as saturated cyclic segments. The polymerization of isoprene in cyclohexane at 20°C. in the presence of polystyrene, with ethylaluminum dichloride–titanium tetrachloride as catalyst, resulted in cross‐linking of the polystyrene, the formation of isoprene–styrene graft copolymers, a decrease in the molecular weight, and an increase in the branching of the ungrafted polystyrene. The isoprene units in the graft copolymers were present as cyclic segments.
Computer calculations concerning copolymerization, terpolymerization, and the chemical reactions of copolymers and terpolymers
Authors: Harwood H. James , Johnston N. W. , Piotrowski H.
Published: June 2010

Computer programs we have developed during the course of studies on copolymerization, on terpolymerization, and on the chemical reactions of polymers are described. The programs are useful for (a) evaluating monomer reactivity ratios from either copolymerization or terpolymerization data, (b) for predicting the compositions of copolymers and terpolymers from monomer reactivity ratios and monomer feed composition data, (c) for calculating the extents of cyclization to be expected when inter‐sequence cyclizations occur in copolymers and terpolymers, and (d) for calculating the yields of products obtained when copolymers are degraded selectively.
Configurational distributions for finite chain molecules
Authors: Jernigan Robert L. , Flory Paul J.
Published: June 2010

Exact functions expressing the distribution of the end‐to‐end vector for real chains of finite length are unknown. Moments of the distribution can be calculated, however, for linear chains unperturbed by excluded‐volume effects. Thus, second and fourth moments for real chains with interdependent bond rotational potentials, in the rotational isomeric state approximation, can be computed as a function of chain length by methods developed recently. These moments are here compared with those calculated for hypothetical models, e.g., for the Gaussian distribution (to which all distributions converge in the limit of infinite chain length), for the freely jointed chain, for the distribution involving the inverted Langevin function, for the freely rotating chain, for the Porod “wormlike” chain, and for the chain with independent bond rotations that have a symmetrical hindrance potential. The convergence of the series expansion for the distribution function in terms of its even moments obtained by Nagai is investigated for the freely jointed chain (for which any number of moments may be readily calculated). Application of this series to the model with interdependent bond rotations is also considered.
Computer analysis of polymer cooling curves in a dta experiment. I. Self‐heating effects
Authors: Gornick Fred
Published: June 2010

The peak height and shape of a cooling curve obtained in a differential thermal analysis experiment is governed by the transient balance between heat gained as a result of release of the latent heat of fusion of the polymer and heat lost in consequence of the resulting temperature gradient between the polymer and the thermal sink surrounding it. If Δθ is the observed height of the thermogram above its baseline, then it can be shown that to a good approximation

where β is proportional to the ratio of the heat of fusion and the specific heat of the polymer, and γ is a constant determined by the thermal conductivity and geometry of the sample and its container. The rate of crystallization, w̄(t), appearing in the integral is a sensitive function of both t and Δθ. A closed‐form solution of this integral is not possible, but numerical results may be obtained by computer methods.
Theory of block copolymers. I. Domain formation in A‐B block copolymers
Authors: Meier D. J.
Published: June 2010

Microphase separation occurs in many block copolymers to give domain structures. In this first paper in a series dealing with domain formation and the consequences thereof, a theory is presented for the formation of spherical domains in A‐B block copolymers. The theory establishes criteria for the formation of domains and their size in terms of molecular and thermodynamic variables. It is shown that the considerable loss in configurational entropy due to the constraints on the spacial placement of chains in a domain structure requires that the critical block molecular weights required for domain formation are many‐fold greater than required for phase separation of a simple mixture of the component blocks. The relation between domain radius R and molecular dimensions is obtained from the requirement that space in the domain must be filled with a constant density of segments. Segment densities are evaluated from solutions of the diffusion equation, treating the constraints on chain placement as boundary value problems. This gives the relationship R = 4/3 < L2>1/2, where < L2>1/2 is the root‐mean‐square end‐to‐end chain length. Because of chain perturbations in a domain system, < L2 >1/2 is larger than the unperturbed value < L2>01/2 normally expected for bulk polymers. A means to evaluate the perturbations is shown. The agreement between the predictions of the present theory and the limited published experimental information appears quite satisfactory.
The relationship between emulsion freeze‐thaw stability and polymer glass transition temperature. I. A study of the polymers and copolymers of methyl methacrylate and ethyl acrylate
Authors: King Alice P. , Naidus Harold
Published: June 2010

Emulsion polymers and copolymers of ethyl acrylate‐methyl methacrylate containing varying amounts of methacrylic acid were subjected to three freeze‐thaw cycles, following adjustment to a pH of about 9.5 with NH3. The minimum amount of acid required to obtain resistance to freezing and thawing was determined. Values for the glass temperature, (Tg) and minimum film formation temperature (MFT) of the polymer were correlated with the minimum required acid content, indicating that more acid is required as the glass temperature decreases. If a polymer is exceptionally hard so that its particles resist irreversible contact under large forces, it would be expected that little or no acid would be required to obtain freeze‐thaw stability. On the other hand, if the polymer particle is so soft (low Tg) as to readily form aggregates, then very high acid amounts would be required. A plot of minimum weight per cent of acid versus Tg or MFT should, therefore, be hyperbolic approaching zero acid at very high Tg values and approaching very high acid levels at very low Tg values. This is indeed the characteristic of the plot of the experimental data.
The catalyzed polymerization of 1,2‐anhydro‐3,4,6‐tri‐O‐acetyl‐α‐D‐glucopyranose
Authors: Zachoval Jaromir , Schuerch Conrad
Published: June 2010

The polymerization of Brigl's anhydride, 1,2‐anhydro‐3,4,6‐tri‐O‐acetyl‐α‐D‐glucopyranose, proceeds readily at temperatures from −100 to +25°C when catalyzed or initiated by Lewis acids or carbonium ions. The products generally consist of a sol fraction of number average degree of polymerization three to five and sometimes a gel fraction. The latter appears to be crosslinked through ortho acetate structures. Usually the soluble products exhibit a high positive optical rotation indicating a predominance of α linkages. The product with highest optical rotation, [α] + 186.5°, was obtained by catalysis with BF3 etherate in methylene chloride at 0°C. In most systems the molecular weight and the optical activity of products showed variations but no significant trends with changes in temperature of polymerization. Reaction probably proceeds by growth on a carbonium ion in an ion pair.
Enzymatic degradation of cellulosic fibers
Authors: Rinaudo M. , Barnoud F. , Merle J. P.
Published: June 2010

We compared the enzymatic attack by an active cellulase preparation on native cotton, swollen cotton, and regenerated cellulose. At various time intervals the residual cellulose was analyzed for: weight loss, number‐average degree of polymerization, weight‐average degree of polymerization, water retention value, and the biometric length distribution of the fibers; morphologic aspects were analyzed at various intervals of time. On the solubilized part glucose and reducing sugars were estimated. All the data obtained at the supramolecular and macromolecular level were consistent with the existence of several enzymic factors responsible for the hydrolysis of these different substrates.
Biological degradation of cellulose acetate reverse‐osmosis membranes
Authors: Cantor P. A. , Mechalas B. J.
Published: June 2010

An investigation has been carried out with the objective of relating losses in semipermeability of cellulose acetate (DS 2.5) reverse‐osmosis membranes to microbiological degradation (enzymic hydrolysis). Three sources of potentially destructive organisms were selected for study. One source was a set of degraded cellulose acetate reverse‐osmosis membranes; the other two sources were a surface soil sample and a lake bottom mud. From these, a total of 23 microbial isolates were obtained by culturing and enrichment. The isolates were characterized by staining and microscopic examination. Sterilized membranes were shaken continuously with sterile broths containing each isolate. In addition, membranes were placed on sterile agar and streaked with each isolate. Reverse‐osmosis testing of the membranes shaken in broth revealed losses in salt rejection of certain samples after 2 months. Visual observation of agar‐plated membranes showed complete degradation of several samples from each of the three sources of microorganisms. Infrared examination of degraded membranes showed up to 50% loss of acetyl content from the desalinating surface. No salt‐rejecting capability remained in these membranes. Cellulose triacetate membranes were resistant to degradation under conditions identical to those causing degradation of membranes having acetate DS of 2.3–2.5.
Exciton interaction between cyanine dyes and porphin
Authors: Kampas Frank J.
Published: June 2010

Copper porphins with cyanine dyes on the methine bridges show shifts compared to unsubstituted copper porphin of up to 0.5 electron volts of the near ultraviolet “Soret” absorption band. They show smaller shifts of the weaker visible band. This effect is explained as being due to an excitonic interaction with the cyanine dyes rather than the electron attracting or withdrawing effect of the dyes.
Possibility of superconductive‐type enhanced conductivity in dna at room temperature
Authors: Ladik J. , Biczo G. , Redly J.
Published: June 2010

Applying Little's formalism to investigate the possibility of superconductive regions at room temperature in organic polymers, we have calculated the Coulomb and effective attractive terms for the polycytosine homopoly‐nucleotide. Little's original idea that the effective interaction between the mobile electrons of the spine is due to the polarization of the side‐chain electrons has been extended to take into account the polarization of the σ electrons of the same systems which provide the mobile electrons.

According to the results obtained for many intraband and interband scattering processes, the absolute value of the attractive term is larger than, or about the same as, that of the Coulomb term. Therefore, we cannot exclude the possibility of superconductive‐type enhanced conductivity in some regions of DNA. Finally, the effects of the finite dimensions of a cytosine molecule are discussed from the point of view of screening and thermodynamic fluctuations.