bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal degradation of polyquinoxalines
Authors: Wrasidlo W.
Published: April 2003

A systematic investigation of the thermal stability of nine structurally related polyquinoxalines has been conducted. The relative oxidation resistance of these polymers is controlled by two opposing structural effects. Phenyl sidegroup substitution in the heterocycle greatly improves oxidative stability, while the introduction of oxygen into the main polymer chain, in the form of ether groups, produces a negative effect of equal magnitude. These results are discussed from a mechanistic point of view. Simultaneous, dynamic thermal analysis in vacuum up to 1400°C and analysis of volatile and nonvolatile products indicates three major decomposition regions. Between 500 and 640°C, main polymer degradation takes place involving the heterocycle. This event is followed by dehydrogenation of a stable degradation product between 640 and 690°C. Above 1360°C an exothermic reaction takes place to yield highly condensed aromatic residues.
Synthetic thermally reversible gel systems. III
Authors: Haas Howard C. , Chiklis Charles K. , Moreau Robert D.
Published: April 2003

Polyacrylylglycinamide (PAG) and its thermally reversible aqueous gels have been investigated and comparisons made with gelatin. For unfractionated PAG homopolymers in 2M NaCNS at 25°C, the Mark‐Houwink‐Sakurada equation is [η] = 1.16 × 10−3 M̄n0.52. The Huggins k′ value is found to be about 0.9 and the Flory‐Huggins polymer‐solvent interaction parameter, 0.49. A theoretically calculated value of Kθ is very close to the experimental one and it is for this reason and the observed μ and M̄n exponent values that 2M NaCNS at 25°C approaches being a θ solvent for PAG. A thermodynamic approach based on equilibrium swelling and modulus measurements indicates that a single thermally reversible crosslink in a gelatin gel involves numerous peptide backbone units, whereas in PAG gels a crosslink perhaps involves only one residue from each of two chains. These results complement the very high exothermic heat of gelation crosslinking, δHc, for gelatin compared to PAG. ΔHc has been measured on PAG samples of different DP and found to be independent of chain length. Similar measurements on acrylylglycinamide copolymers and terpolymers containing basic and acidic groups produce no change in δHc so that coulombic forces do not appear to be significant. Data are also included relating to the density of PAG, its glass transition and thermal decomposition temperature, the tensile modulus of equilibrium‐swelled PAG films in water and the chain‐transfer constant of methanol with the acrylylglycinamide free radical.
Analysis of nonvolatile oxidation products of polypropylene. II. Process degradation
Authors: Adams J. H. , Goodrich J. E.
Published: April 2003

The nonvolatile products of polypropylene that has been process degraded in the melt by a Brabender torque rheometer have been quantitatively identified by infrared analysis and chemical reactions carried out on molded sheets. The molecular weight changes with degradation have been determined by gel‐permeation chromatography (GPC). It was determined that there is only one functional group per chain scission instead of the two groups previously found for thermal oxidation in the solid state. The molecular weight distribution is similar, but the functional groups and the general scheme of oxidation differ slightly from those previously found for polyolefin oxidation carried out below the melting point. The functional group distribution differs from that determined in a process‐degraded polyethylene sample.
Analysis of nonvolatile oxidation products of polypropylene. III. Photodegradation
Authors: Adams J. H.
Published: April 2003

The nonvolatile oxidation products of photodegraded polypropylene have been analyzed by infrared spectroscopy and chemical reactions. The major functional group is ester followed by vinyl alkene, then acid. In comparison, thermally oxidized polypropylene contains relatively more aldehyde, ketone, and γ‐lactone and much less ester and vinyl alkene. Photodegraded polyethylene contains mostly vinyl alkene followed by carboxylic acid. Gel‐permeation chromatography (GPC) determined the decrease in polypropylene molecular weights with exposure time. A calculation determined that there is one functional group formed per chain scission; in thermal oxidation there are two groups formed per scission.
Anionic graft polymerization and homopolymerization of phenyl glycidyl ether
Authors: Ezra Gabriel , Zilkha Albert
Published: April 2003

Phenyl glycidyl ether was found to react with potassium starch alkoxide in dimethyl sulfoxide (DMSO) to give graft polymers in almost quantitative yields, both the monomer and the starch being incorporated completely into the graft polymer. No transfer reactions to monomer or solvent leading to homopolymerization was found. For this reason this system was used as a model for the study of the rate of the graft polymerization of alkylene oxides on starch and other carbohydrates. Comparison of the rates of the graft polymerization of phenyl glycidyl ether on starch alkoxide with that of the homopolymerization by potassium naphthalene in DMSO under comparable conditions showed that the former reaction was much slower. Rates of the graft polymerizations on dextrin and sucrose under comparable conditions, were similar to those obtained with starch. On the other hand, the rates of polymerization on poly(ethylene oxide) alkoxides of different molecular weights were similar to those obtained in the corresponding homopolymerization by potassium naphthalene, showing that neither the molecular weight of the initiator nor the viscosity of the reaction medium were the governing factors. This suggested that the lower rates obtained by using the carbohydrate alkoxides as initiators were connected with the heterogeneity of these reaction systems, the polymeric alkoxide being insoluble in DMSO. The systematic study carried out on the homopolymerization by potassium naphthalene in DMSO showed that the effective initiator was dimsyl anion obtained by interaction of potassium naphthalene with DMSO. The reaction was bimolecular, being first order to monomer and to initiator. The molecular weights increased with increasing monomer concentration and decreasing catalyst concentration, in accordance with a “living” polymerization system.
Copolymerization of optically active N‐bornylmaleimide with vinyl monomers
Authors: Yamaguchi Hidemasa , Minoura Yuji
Published: April 2003

Optically active N‐bornylmaleimide (NBMI) was copolymerized with styrene, methyl methacrylate, and vinylidene chloride with a free‐radical catalyst to obtain optically active copolymers. The monomer reactivity ratios for the radical copolymerization of NBMI (M2) with styrene, methyl methacrylate, and vinylidene chloride were: ST‐NBMI, r1 = 0.13, r2 = 0.05; MMA‐NBMI, r1 = 2.02, r2 = 0.16; VCl2‐NBMI, r1 = 1.15, r2 = 0.47. The Q‐e values for NBMI were Q2 = 0.48 and e2 = +1.47. The specific rotation and optical rotatory dispersion of these copolymers were measured. The correlation between the specific rotation and composition of these copolymers was not linear. The value of λc for each copolymer was independent of the copolymer composition and the comonomer, being 260 mμ for the St‐NBMI system, 262 mμ for the MMA‐system, and 260 mμ for the VCl2‐NBMI system. The effects of solvents and temperature on the specific rotation of these copolymers were investigated.
Natural and synthetic polymers as reagents. I. Diazonium salt derivatives of polycarboxylic resins (insoluble diazonium salt chromogens)
Authors: Linoli Gianni , Mannucci Enzo , Bergonzi Carlo
Published: April 2003

A method is described for the preparation of insoluble polymeric diazonium‐salt chromogens which have a precise composition and well‐defined specific reactivity and which are capable of undergoing coupling reactions to produce highly colored azo derivatives. The technique involves reaction of the acid chloride of an acrylic or methacrylic acid polymer crosslinked with divinylbenzene with an aromatic diamine, followed by diazotization of the free amino groups of the resultant aminoarylamido resin to give an insoluble diazonium salt. The aminoarylamido derivatives, the corresponding diazonium salts, and colors of the azo derivatives obtained in coupling reactions are tabulated.
Comparison between theoretical and experimental values of the volume changes accompanying rubber extension
Authors: Christensen R. G. , Hoeve C. A. J.
Published: April 2003

The molecular theory of rubber elasticity assumes the free energy to consist of two parts: a liquidlike free energy that is governed by intermolecular interactions and is independent of strain at constant volume and an intramolecular interaction free energy equal to the sum of the free energies of the chains making up the network. The volume increases of rubber samples as a function of their length were found to be considerably larger than predicted by the molecular theory. Therefore, contrary to common belief, the values of (∂E/∂L)V,T might not be related solely to changes in intramolecular interactions with extension. Also, the usual procedure to obtain values of (∂E/∂L)V,T from measurements of (∂f/∂T)p,L with the aid of the molecular theory is not correct.
Chain transfer in ethylene polymerization. IV. Additional study at 1360 atm and 130°C
Authors: Mortimer George A.
Published: April 2003

The previously reported chain‐transfer studies were extended to include chain transfer to esters, amides, amines, phosphines, and other compounds containing functional groups. Phosphines are very reactive, amines are moderately reactive, and amides and esters are quite unreactive. Most other functional groups give moderate reactivity. Halogens and compounds containing a nitrogen‐oxygen bond were all found to be inhibitors for ethylene polymerization.
Chain transfer in ethylene polymerization. VI. The effect of pressure
Authors: Mortimer George A.
Published: April 2003

The chain‐transfer reaction, which controls the molecular weight level of the polymer, apparently has not been studied as a function of pressure for ethylene. Therefore, the chain‐transfer constants for eleven transfer agents were determined at 1360 and 2380 atm at 130°C. The results were interpreted according to transition‐state theory as the difference between the volumes of activation for the transfer and propagation steps. It was found that the effect of pressure on the transfer constant is small for most transfer agents, indicating that the volumes of activation for hydrogen abstraction and addition to the ethylene double bond are similar. Aralkanes, however, gave anomalous results.
Chain transfer in ethylene polymerization. III. An improved method of calculating polymerization chain‐transfer constants
Authors: Tidwell Paul W. , Mortimer George A.
Published: April 2003

The method of determining chain‐transfer constants in polymer systems, originally developed by Mayo, has been extended to the simultaneous determination of constants for several transfer agents. The validity of various calculation methods was examined. Particular attention was devoted to the question of how precisely chain‐transfer constants are known. This extended method was applied to the determination of chain‐transfer constants in ethylene polymerization under conditions where the limiting molecular weight in the absence of transfer agents cannot be directly measured, and it was shown that precision is improved (uncertanty reduced) by simultaneously determining more than one transfer constant.
Preparation, reaction, and polymerization of the nuclear chlorinated α,α′‐xylylene diallyl ethers
Authors: Stallings J. P.
Published: April 2003

A process has been developed in which the diallyl ethers of the tetrachloroxylenes are produced in 90–95% yield. The starting materials are the appropriate chlorinated xylene, sodium hydroxide, and allyl alcohol. Epoxidation of the diallyl ethers with perbenzoic acid gave the corresponding diepoxides. The above diallyl ethers are capable of entering into both homo‐ and copolymerization reactions in the presence of free‐radical initiators. With 2% tert‐butyl perbenzoate, the diallyl ethers are polymerized to soluble prepolymers at 130–138°C in about 1 hr. These prepolymers can be formulated with appropriate reinforcing materials and peroxide initiator to give hard, tough thermo‐setting resins. The optimization of various molding and formulation conditions is also described.
Melting behavior of ethylene copolymers and branched polyethylenes
Authors: Griskey Richard G. , Foster George N.
Published: April 2003

Prior research on the melting behavior of ethylene copolymers and branched polyethylenes could not be effectively evaluated since there were large differences in the levels of comonomer contents. The present research was undertaken to determine additional data so that an overall evaluation could be made. A consideration of the experimental data of the present work and earlier research data showed that methyl side groups caused less diffuse melting and less melting point depression than either ethyl groups or polyethylene branches. In addition, it was found that the Flory equation can be used to describe the relation of melting point depression to foreign group concentration for propylene copolymers. The equation did not hold for 1‐butene‐ethylene copolymers or branched polyethylenes. For these materials the Wunderlich modification of the Flory equation applied. Activity values for both 1‐butene‐ethylene copolymers and branched polyethylenes gave a common correlation with foreign groups. Enthalpy and entropy fusion data for ethylene copolymers and branched polyethylenes were also determined. It was also shown that good agreement was found between crystallinities for these materials determined independently by differential thermal analysis and x‐ray analysis.
Crosslinking of starch xanthate. II. Reaction with polyacrolein
Authors: Maher G. G. , Douglas J. A. , Russell C. R. , Rist C. E.
Published: April 2003

The reaction between polyacrolein bisulfite adduct and sodium starch xanthate in aqueous alkali gives a rapid viscosity increase and subsequent gelation. The magnitude and pattern of the viscosity development depend on the degree of substitution of the starch xanthates in the range of 0.12 to 0.45, varying from around 5000 cP centipoises (nongelling) for the lowest to more than 100 000 cP for the highest. The viscosity patterns developed with the more highly substituted xanthates show a minimum valley after a 20‐30‐min reaction. Analytical and spectral analyses of solid materials obtained from the ethanol precipitation of the gels indicate that the product is a monothiocarbonate stemming from the elimination of sodium hydrogen sulfide between a xanthate group of the starch and a hydroxyl group of the polyacrolein adduct. A hydrated form of polyacrolein does not react with starch xanthate under the same aqueous alkaline conditions.
Radiation‐induced solution polymerization of styrene in an engineering flow system
Authors: Osborne F. T. , Omi S. , Stannett V. , Stahel E. P.
Published: April 2003

Radiation induced solution polymerization of styrene in methylene chloride in a small scale pilot plant utilizing a flow reactor is reported. Both conventional free radical and ionic polymerization have been achieved. With rigorous drying accomplished over molecular sieves the ionic mechanism predominates. Conclusive kinetic evidence as well as polymer properties substantiate radiation induced ionic polymerization for the first time in an engineering pilot plant. The validity of Williams' model is reinforced by this study and a survey of over 100 literature observations.
Copolymerization with depropagation. IV. Computer simulation of copolymerization with reversibility
Authors: Izu M. , O'Driscoll K. F.
Published: April 2003

The results of Monte Carlo computer simulations of vinyl copolymerizations with complete reversibility are described for a variety of hypothetical systems using values of thermodynamic quantities typically found. Composition of copolymer, sequence distributions, relative chain lengths and equilibrium behavior have all been investigated. The existence of thermodynamic control of copolymerization behavior becomes more obvious as temperature is increased in some systems but may be masked by kinetic factors in others.
Effect of high pressures on the cyclopolymerization of acrylic anhydride
Authors: Higgins J. P. J. , Weale K. E.
Published: April 2003

The effect of pressures up to 4000 atm on the free‐radical cyclopolymerization of acrylic anhydride in solution has been investigated. Both the molecular weight and degre of cyclization of the polymer are increased by pressure. The rate of polymerization at first decreases with increasing pressure, but above 2500 atm a normal acceleration occurs.
Substituent effects in free radical copolymerization of substituted styrenes with acrylates and methacrylates
Authors: Faber Jan W. H. , Fowler W. F.
Published: April 2003

Relative reactivity ratios have been determined for o‐chlorostyrene with five lower acrylates and methacrylates, respectively, and for methyl acrylate with a number of substituted styrenes in free‐radical copolymerization. Analysis of the data shows that: (a) acrylates are less reactive than methacrylates with o‐chlorostyrene; (b) length of the side chain has little or no effect in methacrylates, but its effect is pronounced in acrylates with respect to their reactivity ratios; (c) chlorine substitution in the side chain of either acrylates or methacrylates has a significant influence on the reactivity ratio; (d) relative reactivity ratio data for methyl acrylate with substituted styrenes fail to show the expected relationship between monomer structure and resonance theory, inductive effect and, consequently, the Hammett σ values.
Helix formation and formaldehyde crosslinking in gelatin solutions
Authors: Coopes I. H.
Published: April 2003

Optical rotation measurements on 5% gelatin solutions containing 0, 2, and 5% formaldehyde (w/w gelatin) are carried out at a series of temperatures between 20°C and 50°C. The solutions without formaldehyde show a diminished growth in rotation with rising temperatures, but even at 50°C there is still a steady rise in rotation with time. The addition of formaldehyde diminishes the optical rotation growth, and at 40°C and above solutions with 5% formaldehyde show no change in rotation at all. The specific rotation and time figures are fitted to a series of third‐degree polynomial equations. It is shown that the data do not conform to any pattern of simple reaction kinetics. The mechanism of the formaldehyde–gelatin interaction is discussed.
Stereospecific polymerization of methacrylonitrile. V. Formation of the carbonyl in the polymer
Authors: Joh Yasushi , Yoshihara Toshio , Kurihara Seiki , Sakurai Toshio , Tomita Tatsunori
Published: April 2003

The isotactic polymethacrylonitrile prepared by the organometallic catalysts has carbonyl groups in the polymer. Thus, the carbonyl formation during the polymerization by diethylmagnesium was carefully studied by infrared spectrometry. It was found that the imino anion formed by monomolecular termination of the propagating chain end in the cyclization reaction successively attacks the vicinal pendent nitriles in the polymer so as to form the conjugated cyclic imines, which are hydrolyzed to acid amines during the catalyst decomposition with acidic methanol.
Thermal analyses of polymers. III. Influence of isocyanate structure on the molecular interactions in segmented polyurethanes,
Authors: Miller G. W. , Saunders J. H.
Published: April 2003

The thermal responses of various polyurethane elastomers in the form of changes in heat capacity, linear expansion, and tensile strain have been examined. Most of the change which can be attributed to the backbone of polyethylene adipate, found in several modes of thermal analysis, are still apparent, though shifted somewhat, among most of the diisocyanate extended elastomers used in this study. Tolylene diisocyanate extension changes the modulus properties markedly, low modulus properties being observed at ambient temperatures. Both hydrogenated MDI and MDI elastomers show comparable expansion and modulus response, whereas the hydrogenated TDI elastomer does not have the same characteristics as TDI‐based elastomers. The thermal properties of the hydrogenated TDI elastomer resemble more those exhibited by the polyol mixture extended with hexamethylene diisocyanate, and in addition this latter elastomer exhibits more crystallinity, as shown by the large endotherm in the specific heat measurement. The structure of the diisocyanate naturally changes the behavior of the hard segment.
Polymerization and processability of poly(vinyl chloride),
Authors: Deanin Rudolph D. , Somers Roger E.
Published: April 2003

The processability of rigid poly(vinyl chloride) can be improved by adding trichloroethylene as chain‐transfer agent, increasing the polymerization temperature, and especially by combining the two effects together. The resulting synergistic interaction is best expressed by an equation of the form, P = (A + B[TCE])eC/T, where P is thermal plasticity, AeC/T is the combined effect of chain transfer to initiator and monomer and termination through combination and disproportionation, and B[TCE]eC/T represents the chain‐transfer action of trichloroethylene.
Radical polymerizations and copolymerizations of dimethylstannyl dimethacrylate and trimethylstannyl methacrylate
Authors: Yamada Bunichiro , Yoneno Hiroshi , Otsu Takayuki
Published: April 2003

The radical polymerizations and copolymerizations of dimethylstannyl dimethacrylate (DSM) and trimethylstannyl methacrylate (TSM) in dimethylformamide (DMF) were studied. These monomers did not polymerize thermally, but easily underwent polymerization in the presence of α,α′‐azobisisobutyronitrile and on irradiation with ultraviolet light. The polymer obtained from TSM was soluble in DMF and methanol, but that from DSM was insoluble in any organic solvents; this polymer probably consists of a network structure. These polymers were converted to poly(methyl methacrylate) (PMMA) by means of acid hydrolysis and then methylation with diazomethane. The content of syndiotactic triad was determined from infrared spectra of PMMA derived from the polymers of DSM and TSM. It was noted that the content of syndiotactic triad was greater in the radical polymerization of TSM than those of DSM at every temperature investigated. The differences in the activation enthalpy (ΔΔH‡) and in the activation entropy (ΔΔS‡) between isotactic and syndiotactic additions were determined as follows: for DSM, ΔΔH‡ = ∼0 cal/mole, ΔΔS‡ = −0.856 eu; for TSM, ΔΔH‡ = 229 cal/mole, ΔΔ = −1.09 eu. From the radical copolymerizations of DSM and TSM with styrene at 60°C, the copolymerization parameters, Q and e, were evaluated as follows: for DSM, Q = 1.36, e = 0.41; for TSM, Q = 0.45, e = −0.37. These results were compared with the reported effects of stannic chloride and zinc chloride on the radical polymerization of methyl methacrylate.
Polyarylsulfones, synthesis and properties,
Authors: Vogel H. A.
Published: April 2003

A new class of high molecular weight polyarylsulfones is described. Polymer synthesis and structure–property relationships are discussed. The polymers are prepared by Friedel‐Crafts type polycondensation of aromatic sulfonyl chlorides with aromatic hydrocarbons. A number of Lewis acids in small quantities are useful as catalysts for the polymerization. The polymerization reaction is carried out at elevated temperatures in the melt or in solution. Inert, nonbasic solvents which are compatible with the Lewis acid catalysts such as nitrobenzene and dimethyl sulfone are useful for conducting the polymerization. Many of the polyarylsulfones are amorphous, rigid thermoplastics with unusually high softening points, having glass transition temperatures in the range of 200–350°C. Outstanding resistance to air oxidation at high temperatures is derived from incorporation of the deactivating sulfone groups in the aromatic polymer backbone. Melt stability and solubility in selected solvents are emphasized as basis for processibility by conventional solution casting and molding techniques. The combination of properties, which in addition to thermal stability includes a high level of mechanical and electrical properties, chemical inertness, and hydrolysis resistance makes these new arylsulfone polymers useful over a wide temperature range and in severe and corrosive environments.
Synthesis and polymerization studies of 1,2‐dimethyleneoctafluorocyclohexane
Authors: Blomquist A. T. , Durandetta Donald W. , Robinson Gordon B.
Published: April 2003

1,2‐Dimethyleneoctafluorocyclohexane has been prepared by the pyrolysis of 2‐chloro‐methyl‐1‐methyloctafluorocyclohexane. Free radicals initiate the polymerization of the diene in both bulk and emulsion systems to give a highly crystalline (mp 214–218°C) polymer that has an all‐cis 1,4‐structure. The polymer is insoluble in common laboratory solvents, but will dissolve in perfluorokerosene above 175°C and in 2,5‐dichlorobenzo‐trifluoride above 150°C. This diene is not polymerized by cationic, anionic, or Ziegler‐Natta catalysts. The diene is readily copolymerized with many common monomers to give soluble, high molecular weight polymers. Relative reactivity ratios have been measured with styrene by the Fineman and Ross method and Q–e parameters for the diene have been calculated.
Cyclopolymerization: Cyclization of diallylcyanamide to pyrrolidine derivatives
Authors: Brace Neal O.
Published: April 2003

Free‐radical addition of perfluoroalkyl iodides (RFI) to diallylcyanamide gave cis‐ and trans‐1‐cyano‐3‐iodomethyl‐4‐(perfluoroalkyl)methylpyrrolidine (Ia,b). Five‐membered ring products were preferentially formed in this reaction by other 1,6‐dienes having terminal vinyl groups. This strongly suggests that cyclopolymerization of such monomers occurs in analogous fashion, instead of leading to 6‐membered rings as has been previously understood. Dehydrohalogenation of Ia,b gave 3‐methylenepyrrolidine derivatives as expected. Infrared and NMR spectra clearly show the exocyclic CH2 group. The influence of reaction conditions on the yield of cyclization product Ia,b and certain side products was investigated.
Quaternary ammonium and sulfonium derivatives of 2‐chloromethylbutadiene and poly‐2‐chloromethylbutadiene
Authors: Jones Giffin D. , Meyer W. C. , Tefertiller N. B. , MacWilliams D. C.
Published: April 2003

2‐Chloromethylbutadiene has been converted to quaternary ammonium and sulfonium monomers which have been polymerized at room temperature. They show a very great tendency to dimerize on heating in water solution. The aqueous quaternary monomer dimerized 25 times as fast as the aqueous sulfonium monomer and nearly 105 times as fast as neat isoprene at 50°C. The quaternary monomer dimerized with itself in a water solution to which 2‐hydroxymethylbutadiene has been added as an example of a nonionic diene. The latter monomer did not dimerize rapidly in water, nor did 2‐aminomethylbutadiene. The hydrochlorides of 2‐aminomethylbutadiene and 2‐dimethylaminomethylbutadiene dimerized at rates comparable to that of the sulfonium monomer. Poly 2‐chloromethylbutadiene contains reactive chlorine except for the structure resulting from the minor extent of 1,2 addition. Water‐soluble derivatives have been made from it with nucleophilic tertiary amines and sulfides. Cationic polymers are substantive to paper pulp, and the sulfonium polymers can be cured in paper to give improved wet strength.
Design of active‐site‐directed fluorescent probes and their reactions with biopolymers
Authors: Himel Chester M. , Mayer Richard T. , Cook Larry L.
Published: April 2003

Fluorescent probes which are active‐site‐directed, reversible, competitive inhibitors of serum cholinesterase (ChE) enzymes have been designed and synthesized. Reversible inhibitors of enzyme active sites have a unique importance when they act as fluorescent probes, allowing fluorescence spectroscopic detection of conformation changes and activesite dynamics. 5‐Dimethylamino‐naphthalene‐1‐sulfonamido‐N,N‐dimethyl‐n‐propyl‐amine and its aliphatic quaternary derivative are fluorescent probes for serum cholinesterase. The quaternary probe forms complexes with acetylcholinesterase (AChE). The dissociation constants Kd for the two probes with serum ChE are 6.0 × 10−7 and 6.5 × 10−7M. The inhibition constants Ki are 3.1 × 10−6 and 6.3 × 10−6M from the slopes of Lineweaver‐Burk plots. The Michelis constant Km for the enzyme was 8.8 × 10−4M.
Preparation of some new polybenzimidazoquinazolines
Authors: Saga M. , Hachihama M. , Shono T.
Published: April 2003

Several new types of polybenzimidazoquinazolines with a different recurring unit have been prepared by solution polycondensation in polyphosphoric acid followed by heating at elevated temperature under reduced pressure. The polymers thus obtained were light yellow to brown powdery materials hardly soluble in common organic solvents and soluble in concentrated sulfuric acid. The inherent viscosity of the polymers ranged from 0.1 to 0.58 and showed good thermal stability.
An optically active vinyl sulfoxide copolymer and the configuration of sulfoxide adjacent to radical or anionic sites
Authors: Mulvaney J. E. , Ottaviani R. A.
Published: April 2003

Optically active vinyl p‐tolyl sulfoxide was synthesized and copolymerized with styrene to produce an optically active copolymer. The question of the configuration of sulfur in a sulfoxide when adjacent to a radical site is discussed. The configuration of sulfur in a sulfoxide is proven to be nonplanar when adjacent to an anionic site.
Glass transformation temperatures of polymers of olefin oxides and olefin sulfides
Authors: Lai Joginder , Trick G. S.
Published: April 2003

A number of polymers belonging to poly(olefin oxide) and poly(olefin sulfide) series have been prepared and their glass transformation temperatures determined by dilatometry and differential thermal analysis. In the poly(olefin oxide) series, theTgremained practically unchanged as the length of the pendent alkyl group was increased from methyl ton‐hexyl. However, a 20°C decrease inTgwas observed when the pendent group was changed from ethoxymethyl ton‐hexoxymethyl. In the poly‐(olefin sulfide) series, theTgvalue decreased as the pendent alkyl group changes from methyl to ethyl. Replacement of ether oxygen in the polymer main chain by sulfide sulfur increased theTgvalue. In some polymers, first‐order transitions were observed, but their significance has not been assessed.
Electron spin resonance study on polymerization of conjugated dienes by homogeneous catalyst derived from n‐butyl titanate and triethylaluminum
Authors: Hirai Hidefumi , Hiraki Katsuma , Noguchi Isamu , Inoue Takeo , Makishima Shoji
Published: April 2003

Polymerizations of butadiene, penta‐1,3‐diene, and isoprene with n‐butyl titanate–triethylaluminum catalyst are examined by ESR measurements on the polymerization state. At Al/Ti molar ratios greater than 2.9 where the conjugated dienes are polymerized, the polymerization system of butadiene always gives an ESR signal with a g value of 1.983 and with a hyperfine structure of about 19 components. This signal does not appear at all, even in the presence of the monomer, at Al/Ti molar ratios smaller than two where butadiene is not polymerized. The absorption intensity of the signal coincides fairly well with the concentration of polymer chain calculated from polymer yield and the molecular weight. On the basis of these facts, the signal is assigned to the growing end of polybutadiene with this catalyst. The structure of the growing end is proposed to have both two substituted π‐allyl groups and an alkoxy group in coordination to titanium (III), by analysis of the hyperfine structure. The polymerization system of penta‐1,3‐diene and that of isoprene respectively, give a new signal with a g value of 1.983, although the signal for the former monomer has a hyperfine structure of 11 components and that for the latter monomer has no hyperfine structure. A structure for the growing end in the polymerization of each of these two monomers analogous to that of the growing end of polybutadiene is proposed.
Polyhydrazides. IV. Preparation and properties of poly‐N‐ethyl‐ and isopropylhydrazide oxadiazoles
Authors: Iwakura Yoshio , Uno Keikichi , Kurosawa Shigeru
Published: April 2003

High molecular weight poly‐N‐alkylhydrazide‐oxadiazoles have been prepared in poly‐phosphoric acid by alkylation of poly‐1,3,4‐oxadiazole which was synthesized from terephthalic acid and hydrazine sulfate. Various kinds of reagents having an alkoxy group were used as alkylating agent, and N‐ethylated and N‐propylated polyhydrazides containing oxadiazole units were obtained. The thermal properties of the polymers obtained were investigated by using infrared spectroscopy, viscometry, differential thermometric and thermogravimetric techniques. Soluble poly‐N‐alkylhydrazide‐oxadiazole are thermally cyclized to poly‐1,3,4‐oxadiazole with elimination of olefins and water at 226–330°C for propylated polydrazide and at 240–360°C for ethylated polyhydrazide. For both, weight loss in polyhydrazides occurs in two distinct stages corresponding, respectively, to cyclization and decomposition of the poly‐1,3,4‐oxadiazole formed in situ.
Chain transfer with siloxanes during free‐radical polymerization
Authors: Saam John C. , Gordon David J.
Published: April 2003

Chain transfer constants (Cs) for a number of substrates containing the silicon‐oxygen bond are measured in polymerizing methyl methacrylate. Additionally, a few measurements are run in styrene in order to estimate the influence of polar factors on chain transfer. The methylsiloxanes studied all show very low values of Cs (10−5 to 10−6). The chain transfer constants of a number of propylsiloxane derivatives are negligibly influenced by the presence of silicon. Thus, (Me3SiO)2MeSiCH2MeCH(C6H5) shows a value of Cs nearly that reported for cumene, and (MeO)3SiCH2CH2CH2SH shows values of Cs close to those reported for alkyl mercaptans.
Polymerization of unsaturated episulfides
Authors: Lautenschlaeger F. , Schnecko H.
Published: April 2003

The polymerization of four unsaturated episulfides, vinylthiirane, endo‐2,3‐thioepoxy‐norbornene, cyclooctadiene‐1,5‐monoepisulfide and allyloxymethylthiirane can be affected by various ionic catalysts, BuLi, ZnEt2.H2O, BF3.Et2O, etc. In case of conjugated functional groups, some catalysts afford isomeric structures resulting from participation of both the olefinic and the episulfide group; the latter can also be opened separately, but even for radical initiation of vinylthiirane no 1,2‐structure of a pure vinyl polymer was obtained. A rearrangement of 1,3‐ to 1,5‐polymer has been observed in some cases by post treatment.
Treatments of cross‐termination rate constants in radical copolymerization
Authors: Ito Katsukiyo
Published: April 2003

In copolymerization, Arlman's equation was modified towherektabis an apparent cross‐termination rate constant depending on a ratiof1= [A]/[B], andKz(x= 1, 2, 3, 4) is the ratio of each cross‐termination rate constant depending on the penultimate unit to the geometric meanK̄tabof two termination rate constants in homopolymerizations. The calculated values of (K1+K2/r1r2) by using this equation were related toK1+K2/r1r2= 18/r1r2.
Étude de la cotacticité des copolymères acrylonitrile‐méthacrylate de methyle par resonance magnetique nucléaire—haute resolution
Authors: Pham‐Quang‐Tho  , Guillot Jean
Published: April 2003

A study of the NMR spectra of acrylonitrile–methyl methacrylate copolymers (PAM) with very low percentages of methyl methacrylate (M) allows quantitative determinations of AMA, and MMA or AMM triad sequences from the methoxy resonances. The resolution of the complex α‐methyl resonances of the isolated M units in seven components has been attempted. If our assignments are correct, the analysis of the cotactic pentad sequences (with a M in central position) has revealed that the configurations of the copolymer chain do not follow the Bernouillian or the first‐order Markoffian statistics.
Mechanism of the thermal stabilization of poly(vinyl chloride) with metal carboxylates and epoxy plasticizers
Authors: Anderson Donald F. , McKenzie D. A.
Published: April 2003

The chemical reactions responsible for the retardation of thermal discoloration in poly(vinyl chloride) (PVC) stabilized with a combination of an epoxy plasticizer and a heavy metal soap mixture of Group IIa and IIb metals have been studied. Allylic chlorides (a mixture of 4‐chlorohexene‐2 and 2‐chlorohexene‐3) are used as prototypes for the degrading segment of the polymer chain. The results confirm earlier reports that, when a mixture of a covalent and ionic metal soap is used as the stabilizer, the covalent moiety (e.g., Cd and Zn soaps) functions to esterify the allylic site of the degrading PVC model. A synergistic effect displayed by the ionic soap (e.g., Ca or Ba) is caused by a transfer of carboxylate ligands from the ionic soap to the depleting covalent species, which has been largely converted to the corresponding chloride. When an epoxy plasticizer model (cyclohexene oxide) is used in conjunction with the metal soap stabilizer, the preferred reaction is esterification. After a considerable build‐up of ester, an α‐chloroether, 2‐hexenyl 4‐(2‐chlorocyclohexyl) ether, is formed by the reaction of cyclohexene oxide with the PVC model. This reaction was found to be catalyzed by cadmium chloride. The esterification and etherification reactions provide an explanation for the synergism observed in the stabilization of PVC containing a combination of an epoxy plasticizer with a covalent and an ionic metal soap.
Relationship between membrane potential and electrolyte uptake by ion‐exchange membranes
Authors: Lakshminarayanaiah N. , Siddiqi Fasih A.
Published: April 2003

Electrical potentials arising across three cation‐selective membranes of low water content when they separate solutions of different concentration of the same NaCl electrolyte have been measured at 25°C. Also, electrolyte uptake by these membranes when they are in equilibrium with different solutions of NaCl has been estimated. These data together with the apparent membrane transport number derived from membrane potential have been used to check a simple relation given by Lakshminarayanaih.
Mobility of the ring structure and the characteristics of crosslinked polymers: The structural effect of the eleven‐membered ring and its homologs upon the dynamic mechanical properties and glass transition temperature of crosslinked diallyl succinate polymers
Authors: Isaoka Shinichi , Mori Makihiko , Mori Akio , Kumanotani Ju
Published: April 2003

Dynamic mechanical properties and glass transition temperatures were measured for crosslinked polymers derived from diallyl succinate monomers. The mobility of the diester having an eleven‐membered ring and of homologous structures which are introduced in the crosslinked polymer system, is discussed on the basis of the parameter for cyclization polymerization of a monomer, dynamic mechanical properties, and glass transition temperature. Control of the mobility of the ring structure and its homologous structures involved in the crosslinked polymers was attempted by modification of the substituent at the 1‐ or 1,2‐position of diallyl succinate, and the diallyl succinate monomers were derived from the succinic acid and its derivatives: succinic acid, methyl succinic, ethyl succinic, and chlorosuccinic acids; cis‐1,2‐dicarboxylic acids of cyclopropane, cyclobutane, cyclopentane, and cyclohexane; cis‐1,3‐ and 1,4‐dicarboxylic acids of cyclohexane, and phthalic acid. The results obtained are explained well on the basis of the mobility of the ring and homologous structures.
Influence of mass transfer at the monomer‐water interface on polymerization emulsion
Authors: Nikitina S. A. , Spiridonova V. A. , Taubmann A. B.
Published: April 2003

A quasi‐spontaneous process of mass transfer takes place at the interface of a monomer and water in the presence of surface‐active substances soluble in both phases as a result of their diffusion through the interfacial boundary. This process is accompanied by the formation of a microemulsion whose particle size depends on the emulsifier concentration and its molecular structure. While investigating various nonionic surface‐active substances as emulsifiers in the emulsion polymerization of vinyl acetate, it was established that polymerization occurs in droplets of the monomer microemulsion in water, which are formed as a result of mass transfer at the interface.
Investigation of the mechanism of chlorination of poly(vinyl chloride) as influenced by chain microstructure
Authors: Allen V. R. , Young R. D.
Published: April 2003

Samples of poly(vinyl chloride) polymerized at different temperatures (+30, 0, −30, and −78°C) and a commercial sample were chlorinated by a photoinitiated, free‐radical method in o‐dichlorobenzene at ambient temperature. The chlorine content was determined by difference by using a carbon‐hydrogen analyzer. High‐resolution infrared analysis revealed a selective attack on the methylene hydrogens along with a concomitant decrease in intensity of the isotactic methylene deformation band and the syndiotactic carbon‐chlorine stretching band. Graphical representation of the relative intensities of the v(CH), δ(CH2), and v(CCI) modes indicate that the chlorine radical preferentially attacks the middle carbon of the heterotactic triad. The increased “stiffness” of this unit causes the rotational energy of the system to be transferred to the syndiotactic portion of the chain. It is proposed that this additional energy causes the TTTT conformer of the syndiotactic unit to rotate into the less‐preferred TTGG conformation, which would be more reactive. Facile chlorination of this latter conformer is predicted. This mechanism is in accord with the reported equilibrium composition of the different conformers.
Effects of substituents on the anionic copolymerization of ring‐substituted cinnamonitriles
Authors: Kobuke Yoshiaki , Fukui Yoshio , Furukawa Junji , Fueno Takayuki
Published: April 2003

trans‐Cinnamonitrile (M1) was copolymerized with several of its ring‐substituted derivatives (M2) in toluene at 25°C, calcium zinc tetraethyl being used as catalyst. The ring substituents investigated include H,p‐CH3O,m‐CH3O,p‐CH3,m‐CH3,p‐Cl, andm‐Cl. It was found that the values of log (1/r1) are linearly correlated with Hammett's σ constants with the reaction constant σ ρ 0.7. The effects of coordination between monomer and catalyst sites upon the Hammett relation are discussed.
Polymers containing anthraquinone units: Polyimidazoles and polypyrrolones from 1,2,5,6‐tetraaminoanthraquinone
Authors: Pense Rolf , Marvel C. S.
Published: April 2003

1,2,5,6‐Tetraaminoanthraquinone has been condensed with isophthalaldehyde and terephthalaldehyde and their bisulfite addition compounds to yield new heat‐stable polymers. It has also been condensed with pyromellitic anhydride to give the pyrrolone. The highest viscosities were obtained in polymers prepared with acid catalysts. The polymers were nearly all soluble in concentrated sulfuric acid but not in organic solvents. Those soluble in sulfuric acid could also be solubilized by reduction with sodium dithionite and potassium hydroxide in aqueous organic solutions. A few polymers were apparently crosslinked, since they would not dissolve in either sulfuric acid or in base on reduction. Weak fibers were obtained by spinning the reduced alkaline solutions of the polymers into aqueous acid.
Polymers containing anthraquinone and quinoxaline units: Polypyrrolones
Authors: Dutt Prabir K. , Marvel C. S.
Published: April 2003

Four ladder or partial ladder polypyrrolones containing anthraquinone recurring units have been synthesized by condensing the dianhydride of 1,2,5,6‐bis(α,β‐dicarboxyl‐pyrazino)anthraquinone with four different tetraamines, 1,2,4,5‐tetraaminobenzene tetrahydrochloride, 3,3′,4,4′‐tetraaminodiphenyl, 3,3′,4,4′‐tetraaminodiphenyl ether, and 1,2,5,6‐tetraaminoanthraquinone in dimethylacetamide and tetramethylene sulfone as reaction media. A prepolymer with an open structure was first formed which on further heating gave a closed‐ring structure. These polymers which were highly colored, powdery materials, were insoluble in common organic solvents and slightly soluble only in concentrated H2SO4. They could, however, be solubilized in alkali by reduction with sodium dithionite. These polymers with an inherent viscosity in the range of 0.2–0.5, showed good thermal stability.
Viscous flow and structure of linear polymers
Authors: Bartenev G. M.
Published: April 2003

The viscosity of linear polymers obeys the logarithmic additivity rule. This is associated with the fact that the activation energy of the viscous flow within certain limits of parameters changes does not depend on temperature, stress, molecular weight, and content of active filler. The mechanism of viscous flow of linear polymers is associated with the reversible destruction of an unstable supramolecular structure typical of the polymers in the state of viscous flow. The effect of shear stress on the viscosity of linear polymers does not obey the Eyring equation. It is supposed that the effect of shear stress on viscosity is associated with the peculiar mechanism of the destruction of the supramolecular structure. At higher rates of viscous flow of the polymer, the activation energy can decrease as a result of the deep destruction of the supramolecular structure. This is a reversible process, as after removal of stress the supramolecular structure slowly reverts to its original state.
Photosensitization of vinyl polymerization by uranyl ions
Authors: Venkatarao K. , Santappa M.
Published: April 2003

Monomer acrylamide was used as quencher of uranyl ion fluorescence and Stern‐Volmer plots were constructed at three monochromatic wavelengths of exciting radiation. The results indicated that the reaction between excited uranyl ion and monomer is one of energy transfer. The rate parameters kp/kp½ and kd′/ki were calculated from the polymerization kinetics at high monomer concentrations. A general mechanism for the photopolymerization of vinyl monomers sensitized by uranyl ions is proposed and discussed.
Copolymerization of styrene and butadiene in emulsion. III. Crosslinking studies by partial conversion properties
Authors: Burnett G. M. , Cameron G. G. , Thorat P. L.
Published: April 2003

Crosslinking in the styrene–butadiene emulsion copolymerization (21 parts styrene:79 parts butadiene) prior to gelation has been studied by means of partial conversion number‐average molecular weights at 5, 15, and 25°C. It is shown that the macromolecular population begins to diminish at progressively lower conversions as the reaction temperature is increased. This is attributed to the relative increase in crosslinking over propagation as the reaction temperature is increased and also to the decrease in mercaptan regulating index with increasing temperature.