bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absorption and fluorescence of a nonionic detergent in aqueous solution
Authors: Ikeda Shoichi , Fasman Gerald D. 
Published: April 2003

AbstractThe absorption and fluorescence spectra of a detergent, polyoxyethylene octylphenyl ether, were measured in water at different concentrations. The absorption spectra had a peak at 275 mμ and a shoulder at 281 mμ. The spectra were independent of concentration below the critical micelle concentration, but the molar extinction coefficients of the peak and the shoulder increased with concentration above the critical micelle concentration. The critical micelle concentration value derived from the absorption data was in good agreement with those obtained by other methods. The fluorescence spectra of the detergent in water were independent of concentration in dilute solutions, if the intensities of the spectra were normalized at the peak at 302 mμ. At higher concentrations, a weak excimer band appeared at 345 mμ, whose intensity increased with concentration. The excimer band manifested itself at a concentration slightly lower than the critical micelle concentration. The main band decreased and the excimer band increased, as the temperature was raised. An excimer band was observed in the same region of the spectra for the pure detergent, either in the solid or liquid state. The equilibrium solid spectra exhibited a very strong excimer emission. It was concluded that the excimers were formed within micelles in the case of aqueous solutions.
A particle growth theory for heterogeneous Ziegler polymerization
Authors: Buls V. W. , Higgins T. L. 
Published: April 2003

AbstractSamples of “as produced” polypropylene particles at progressively higher yield levels (grams polymer/gram catalyst) were sliced and examined by electron microscopy. In the polymerization of propylene with the TiCl3–(C2H5)2AlCl catalyst system the catalyst breaks up immediately into basic 100–1000 Å particles. As the yield increases, the catalyst particles gradually disappear and finally become completely dispersed in the polymer particle. These results are compatible with a theory which views the catalyst as a porous crystal containing a single species of active sites uniformly distributed. As polymerization progresses, all sites should eventually initiate a polymer chain whose length should be inversely proportional to the depth of the site below the surface of the particle. Two apparently equivalent statistical models were developed on the basis of this concept. Both models predict a slow increase in the X̄w/X̄n ration (Q) with increasing molecular weight, after an initial rapid increase. The most useful of these models states that Q is equal to the sum of X̄w terms of the simple harmonic series, and that a complete spectrum of x‐mers should be present in the product. This agrees satisfactorily with analytically determined values.
Graft copolymerization to cellulose by the metallic ion–hydrogen peroxide initiator system
Authors: Ogiwara Yoshitaka , Kubota Hitoshi 
Published: April 2003

AbstractThe decomposition of hydrogen peroxide and the graft copolymerization of methyl methacrylate has been investigated by use of cellulose samples adsorbing various metallicions. Metallic ions generally accelerate the decomposition of hydrogen peroxide, increase the number of grafts, and lower the average molecular weight. However their effects are much influenced by the range of pH values. It is clear that the amount of grafts formed is not necessarily proportional to the amount of decomposed hydrogen peroxide and is dependent upon a function peculiar to each metallic ion. The effective metallic ions in the neutral system were Cu2+, Ag+, Fe2+, Co2+, Cr3+, and Zn2+. The effects of Ce3+, Mg2+, Hg3+, Cd2+, Ni2+ and Mn2+ were either negligible or negative. Comparative studies on various conditions confirmed that Fe2+ in the neutral system gives graft copolymer having a minimum average molecular weight and the greatest number of grafts.
Thermal degradation of polyquinoxalines
Authors: Wrasidlo W. 
Published: April 2003

AbstractA 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

AbstractPolyacrylylglycinamide (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

AbstractThe 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

AbstractThe 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

AbstractPhenyl 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

AbstractOptically 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

AbstractA 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractPrior 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

AbstractThe 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

AbstractRadiation 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

AbstractThe 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

AbstractThe 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

AbstractRelative 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

AbstractOptical 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

AbstractThe 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.