bluuebunny/crossref_metadata_2025_split huggingface dataset:
The dependence of the isotacticity of polypropylene on polymerization conditions
Authors: Keii Tominaga , Soga Kazuo , Go Shigeo , Takahashi Atsushi , Kojima Akira 
Published: June 2010

AbstractTo 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

AbstractStress‐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

Abstract3,4,5,6‐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

AbstractThe 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

AbstractCopolymerization 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

AbstractA 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

AbstractThe 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

AbstractTensile 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

AbstractBisphenol 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

AbstractThe 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

AbstractChemically 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

AbstractThe 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

AbstractThe 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

AbstractComputer 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

AbstractExact 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

AbstractThe 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

AbstractMicrophase 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

AbstractEmulsion 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

AbstractThe 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

AbstractWe 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

AbstractAn 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

AbstractCopper 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.