bluuebunny/crossref_metadata_2025_split huggingface dataset:
Emulsion polymerization. III. Theoretical prediction of the effects of slow termination rate within latex particles
Authors: Gardon J. L. 
Published: April 2003

AbstractThe Smith‐Ewart theory predicts that there is an interval during an isothermal homopolymerization when the conversion varies linearly with time. This prediction rests on the assumptions that, during this interval II, the particle number is constant, the monomer concentration in the particles is constant, and the termination rate within the particles is instantaneous, so that the average number of radicals per particle Q is half. In this paper this latter assumption is abandoned. If the termination rate is slow, two or more radicals can coexist in a particle. The termination rate within a particle becomes a function of the particle size because of the decreased probability that two radicals meet for termination in a given time when the volume in which these radicals are located increases. It follows that with increasing conversion the termination rate decreases. Stockmayer's calculations based on this model neglected the variation of particle volume with time, and it was assumed that a steady state of radical concentration in particles exists. In the present calculations these restrictive assumptions were not used. Stockmayer calculated only how Q should vary with conversion. In the present paper several experimentally verifiable consequences of the model are shown. The new calculations show that the interval II conversion‐time curve can be represented by the formula At2 + Bt, where B is the Smith‐Ewart rate and is proportional to the particle number and the parameter A is independent of the particle number and depends mainly on initiation and termination rates. From A and B and propagation and termination rate constants can be calculated. With the aid of parameters A and B the conversion dependence of molecular weight and of Q can also be predicted for interval II. In the theoretical calculations the distribution of radicals among particles is established. It is shown that for a given value of Q this distribution is unique, independent of the experimental conditions leading to this Q. This distribution was derived solely from kinetic considerations and is analogous to the statistical Poisson distribution. With increasing Q, i.e., with increasing conversion, this distribution broadens. Since each particle grows proportionally to the number of radicals in it, particles must grow at greatly varying rates if there is broad distribution of radicals among them. It follows that the particle size distribution has to broaden with increasing conversion, contrary to predictions based upon the Smith‐Ewart model. At present it is not yet possible to predict quantitatively the shape of the conversion‐time curve in interval III, the interval following the disappearance of monomer droplets. The reason for this is that the functional dependence of the termination rate constant upon monomer concentration in the particles is not known. However, once the conversion‐time curve is experimentally determined, it is possible to calculate from it the interval III values of Q and of molecular weight.
Two‐stage irradiation study on propagation and termination in the γ‐radiation‐induced polymerization of ethylene in liquid carbon dioxide
Authors: Hagiwara Miyuki , Mitsui Hiroshi , Machi Sueo , Kagiya Tsutomu 
Published: April 2003

AbstractThe propagation and termination reaction in the γ‐radiation‐induced ethylene polymerization in liquid carbon dioxide were investigated by a two‐stage irradiation. After irradiation at high dose rate, the polymerization occured at a considerable rate under the extremely low dose rate without initiation. The absolute propagation rate was determined in the second stage to be proportional to the square of ethylene fugacity and depended slightly on dose rate. The apparent activation energy for the propagation reaction is −9 kcal./mole. From these observations which are the same as those in bulk polymerization, it is concluded that carbon dioxide acts as a diluent of ethylene monomer in the propagation reaction. Also, carbon dioxide was shown to be inactive to the growing radicals without irradiation, but oxygen which is produced by the radiolysis of carbon dioxide at high dose terminates the growing radicals with formation of carbonyl in the polymer.
Polyaryläther‐Kondensationsprodukte des 4,4′‐bis(chloromethylphenyl) äthers mit manchen diphenolen
Authors: Tokarzewska Maria 
Published: April 2003

AbstractPoly(aryl ethers) as products of the polycondensation of 4,4′‐bis(chloromethylphenyl) ether with sodium salts of various phenols have been prepared in the Williamson reaction. The reaction was carried out at three different temperatures (78, 140, and 185°C.) in ethanol, xylene, and tetralin, respectively. The effect of the polycondensation and the nature and composition of initial components on the properties of the products has been studied. The molecular weights and the melting temperature of the synthesized resins increased with increasing reaction temperature. The structure and molecular weight have a pronounced effect on the properties of the resins. Resins prepared from 4,4′‐dihydroxydinaphthyl had the highest melting temperature and were practically insoluble, while the resins prepared from 2,2′‐dihydroxydinaphthlmethane had the lowest melting temperature and were soluble in practically all organic solvents. On the basis of the experimental data a reaction scheme appropriate for the synthesis of poly(aryl ethers) from the phenolates as well as from the free phenols in the presence of NaOH has been proposed. Some thermal and mechanical properties of poly(aryl ethers) have been determined. Thermal treatment of the resins above theri softening temperature resulted in an elevated softening point too. This is explained by the supplementary condensation of both chlorine or hydroxyl endgroups in the molten resins.
Study of Ziegler‐Natta catalysts. Part III. Effect of the structure of titanium trichloride on the polymerization of propylene
Authors: Kollár L. , Simon A. , Kalló A. 
Published: April 2003

AbstractIn addition to differences among the various modifications of TiCl3there may be certain structural differences even among α‐TiCl3samples prepared by differences methods. Electron microscopic examination of two samples has revealed widely different free surfaces, in spite of the fact that both the specific surfaces (measured by adsorption) and the polymerization activities were identical. This might be explained by the finding that the surfaces of the free lateral planes and the quantities of the free edges are the same. This explanation is in agreement with the assumption of Rodriguez and his co‐workers that the active centers of polymerization are situated on the lateral planes and edges of the TiCl3crystals.
Physicochemical and macromolecular properties of sodium amylose xanthate in dilute solution
Authors: Pramanik A. G. , Choudhury P. K. 
Published: April 2003

AbstractSodium amylose xanthate has been studied in dilute solution. Potato starch was fractionated for this purpose into amylose and amylopectin fractions. Amylose was xanthated in solution under alkaline conditions and the Na amylose xanthate was then characterized by reaction with I2 solution and ultraviolet spectra of the xanthate groups determined. Stability of the xanthate in alkaline condition under both oxygen and nitrogen atmospheres was also investigated. From light scattering measurements of dilute salt solutions of Na amylose xanthate, the weight‐average molecular weight Mw as well as the molecular dimensions were determined. In 0.11M NaCl, which conforms to the θ solvent, Na amylose xanthate molecules appear to have a random‐coil configuration. Two other configurational parameters, such as the effective bond length b, and the steric factor σ, i.e., (R02)1/2/(Rf2)1/2, where (R02)1/2 is the Root‐mean‐square end‐to‐end distance in the unperturbed state and (Rf2)1/2 is the unperturbed value calculated on the assumption of free rotation about each intermonomer CO bond of the amylose chain were also calculated and found to be 6.24 and 1.020, respectively. It is thus concluded that the amylose chain in Na amylose xanthate behaves as a typical flexible coil in dilute salt solution.
The thermal degradation of acrylic acid–ethylene polymers
Authors: McGaugh M. C. , Kottle Sherman 
Published: April 2003

AbstractA Study of the thermal degradation of a copolymer of ethylene and acrylic acid is presented. The degradation mechanism of the acrylic acid portion of the polymer was found to be dehydration of the acid, forming anhydride, and decarboxylation of the anhydride, forming unsaturation. The resultant unsaturation reduces the copolymer‐s stability to both thermal and oxidative degradation.
Polymers with quinoxaline units. III. Polymers with quinoxaline and thiazine recurring units
Authors: Okada Masahiko , Marvel C. S. 
Published: April 2003

AbstractSix ladder or partly ladder polymers have been prepared by the condensation reactions of combinations of two diaminodithiophenols, 4,6‐diamino‐1,3‐dithiophenol and 3,3′‐dimercaptobenzidine, with three tetrachloroquinoxaline derivatives, 2,3,7,8‐tetrachloro‐1,4,6,9‐tetraazaanthracene, 2,2′,3,3′‐tetrachloro‐6,6′‐bisquinoxaline, and 2,2′,3,3′‐tetrachloro‐6,6′‐diquinoxalyl ether, with the use of dimethylacetamide, hexamethylphos phoramide, and polyphosphoric acid as reaction media. The polymers thus obtained are highly colored, powedery materials which are slightly soluble in methanesulfonic acid and concentrated sulfuric acid. These polymers (ηinh > 1) show good thermal stability.
Inorganic coordination polymers. X. Observations on the formation and nature of poly(di‐μ‐diphenylphosphinato‐hydroxyaquochromium (III)),{Cr(H2O)(OH)‐[OP(C6H5)2O]2}x
Authors: Maguire K. D. , Block B. P. 
Published: April 2003

AbstractUnder different conditions two products, one green and one brown, were obtained by the air oxidation of chromium(II) diphenylphosphinate. Air oxidation of an aqueous suspension of the phosphinate apparently yields a mixture in which the green form predominates. As initially isolated, the green form is a low molecular weight polymer corresponding to {Cr(H2O)(OH)[OP(C6H5)2O]2}n, with n approximately 11. It spontaneously polymerizes further in organic solvents to high molecular weight polymers of the same composition, with n in the range 150–200. This polymerization reaction in volves the elimination of water and is probably a reaction between endgroups resulting in a basically linear polymer. The brown product, corresponding to low molecular weight {Cr2(H2O)(OH)2[OP(C6H5)2O]4}p, also polymerizes spontaneously but at a faster rate and to a gel. The polymer so produced is less soluble than that produced from the low molecular weight green product and is probably crosslinked.
Polymerization initiated by the charge‐transfer complex of styrene and maleic anhydride in the presence of cumene and of cumene and liquid sulfur dioxide
Authors: Matsuda Minoru , Abe Katsuhiro 
Published: April 2003

AbstractA polymerization was induced with a charge‐transfer type of complex consisting of styrene and maleic anhydride in the presence a solvent such as ethyl benzene, cumene, or p‐cymene. No polymer was obtained either when the solvent was missing from the polymerization system or when benzene, toluene, or xylene, which are relatively stable to hydrogen abstraction, was added to the polymerization system. An effective initiation, however, took place when cumene or p‐cymene, each of which has a labile hydrogen on an α carbon, was added. On the basis of elementary analysis and infrared spectroscopy the formation of copolymer containing substantially equimolar amounts of styrene and maleic anhydride was ascertained. This polymerization was inhibited by the addition of DPPH, suggesting that the system styrene–maleic anhydride–cumene functions much as a conventional free‐radical initiator. On the other hand, when a solution of cumene and liquid sulfur dioxide was added to the polymerization system, polystyrene was obtained. This polymerization was inhibited by the addition of a base such as dimethyl‐formamide or dimethyl sulfoxide, indicating that the polymerization proceeds through carbonium ion intermediates. The addition of ethyl benzene or of p‐cymene brought about the same result as cumene. It is conceivable that the polymerization is induced by the abstraction of hydrogen attached at the α position of cumene by means of the charge‐transfer complex of styrene and maleic anhydride.
Polymers with quinoxaline units. IV. Polymers with quinoxaline and oxazine units
Authors: Wolf Rainer , Okada Masahiko , Marvel C. S. 
Published: April 2003

AbstractSix ladder or partly ladder polymers have been prepared by the condensation of diaminodiphenols with tetrachloro‐ or terahydroxyquinoxaline derivatives with the use of poly (phosphoric acid), pyridine, and naphthalene as reaction media. The polymers thus obtained are highly colored powdery materials which are slightly soluble in concentrated sulfuric acid and methanesulfonic acid. These polymers show good thermal stability.
On the heat of solution of polymer with solvent: Polydimethylsiloxane–solvent systems
Authors: Morimoto Satoshi 
Published: April 2003

AbstractHeats of mixing and excess volumes at infinite dilution have been obtained at 25°C. for polydimethylsiloxane or its lower oligomers in various solvents by using a twin conduction microcalorimeter and from the pycnometric specific volumes. From those values, excess energies ΔEMv at constant volume have been determined. The prediction on intramolecular conformation contributions to the heat of solution as proposed by Bianchi has been evaluated by the values of ΔEMv. The heat of solution in the polymer–solvent systems was interpreted by the expression for ΔEMv derived from the Van Laar‐Hildebrand work on simple liquid mixtures with the solubility parameters of polymers obtained from indirect measurements. The values of conformational intramolecular energy change calculated from dilute solution properties were difficult to rationalize with our results. Our present results suggest that systems in a nonideal state can not be distinguished for certain from those in the ideal state. This conclusion based on apparent values does not deny the possible effect of the conformational energy change.
Polycarboxyhydrazides with ferrocenylene groups in the main chain
Authors: Neuse Eberhard W. , Rosenberg Harold 
Published: April 2003

AbstractPolycarboxyhydrazides essentially of the type \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm C}_{10} {\rm H}_8 {\rm Fe}\hbox{---}{\rm CONHNHCO}\rlap{--}]_n $\end{document} are synthesized by low‐temperature solution condensation of 1,1′‐di(chlorocarbonyl) ferrocene with hydrazine or 1, 1′‐ferrocenedicarboxyhydrazide and hexamethylphosphoramide as solvent. In an analogous manner the polycondensation of 1, 1′‐di(chlorocarbonyl)ferrocene with oxalyldihydrazide leads to polyhydrazides essentially possessing the structure \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm C}_{10} {\rm H}_8 {\rm Fe}\hbox{---}{\rm CONHNHCO}\hbox{---}{\rm CONHNHCO}\rlap{--}]_n $\end{document}. Both polymer types exhibit inherent viscosities (0.08–0.19 dl./g.) considerably lower than reported for analogous aliphatic or benzene‐aromatic polyhydrazides. This behavior points to premature chain termination via heterobridging imide groups as a result of the welldocumented tendency of appropriately substituted ferrocene compounds to undergo intramolecular cyclization. In addition, elemental analytical and spectroscopic evidence, coupled with the failure of both polymer types to undergo cyclodehydration to the corresponding 1,3,4‐oxadiazole polymers upon heat treatment, suggests some structural irregularities in the aliphatic connecting segments arising from ferrocenoylation of secondary amino groups with resultant branching. With the polyhydrazide prepared from 1, 1′‐di(chlorocarbonyl)ferrocene and 1, 1′‐ferrocenedicarboxyhydrazide it is shown spectroscopically that treatment with alkali results in conversation of the nonconjugated hydrazide structure of the connecting segments into the polyconjugated tautomeric enol form comprising azine groups.
Copolymerization of vinylsilanes with styrene
Authors: Iwakura Yoshio , Toda Fujio , Hattori Kenjiro 
Published: April 2003

AbstractNew vinylsilanes (M2), i. e. phenylvinylsilane (I), allylmethylsilane (II), allylphenylsilane (III), and p‐vinylphenylmethylsilane (IV), were prepared and copolymerized with styrene (M1). The monomer reactivity ratios were r1 = 5.7 and r2 = 0, r1 = 36 and r2 = 0, r1 = 29 and r2 = 01, and r1 = 0.91 and r2 = 1.1, respectively. From the results of infrared and NMR spectra it was indicated that the vinylsilanes participated in copolymerization in the form of a vinyl type of polymerization and not in the form of a hydrogen‐transfer type of polymerization. The reaction of copolymer with alcohols and methyl methacrylate and appropriate catalysts was investigated.
Ferrocene‐containing polyesters and polyamides
Authors: Pittman Charles U. 
Published: April 2003

AbstractA series of ferrocene‐containing polyesters and polyamides were prepared by refluxing 1,1′‐dichlorocarbonylferrocene with various diols and primary diamines in xylene–pyridine solvent. The polyamides were all solids, but some of the polyesters were liquids. Reported are the infrared spectra and solubility characteristics of all the polymers and, where possible, the molecular weight and molecular weight distributions. In general, these polyamides and polyesters were of relatively low molecular weight (below 4000), but the polyesters were readily chain extended and crosslinked by di‐ and triisocyanates. Elemental analyses are reported for all the polymers prepared.
Polymers derived from fluoroketones. II. Wetting properties of fluoroalkyl acrylates and methacrylates
Authors: Pittman Allen G. , Sharp Dennis L. , Ludwig Barbara A. 
Published: April 2003

AbstractThe critical surface tension of wetting (γc) for certain branched‐chain polymeric fluoroalkyl acrylates and methacrylates was obtained. Polymeric materials utilized in this study can be represented by the repeating units

, where R is H or CH3, R′ is H or F, and X is F or Cl, by \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm CH}_2\hbox{---}{\rm CH}({\rm COO}({\rm CH}_2)_n {\rm OCF -}({\rm CF}_3)_2)\rlap{--}] $\end{document}, where n is 2, 5, or 11, and by \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm CH}_2 \hbox{---}{\rm C}({\rm R})({\rm COOCH}_2 ({\rm CF}_2)n'{\rm CF}_3)\rlap{--}] $\end{document}, where R is H or CH3 and n′ is 2 or 6. Monomer synthesis involved either the direct acylation of a fluoroketone–metal fluoride adduct or a fluoroalcohol with acryloyl or methacryloyl chloride or a displacement reaction between a fluoroketone–metal fluoride adduct and an ω‐bromoester. In general, modifications in the pendent fluoroalkyl group affected γc in a manner predictable from previous work by Zisman et al.; e.g., γc was increased when either H or Cl was substituted for F in the side chain. In polymeric alkyl acrylates containing a heptafluoroisopropyl side chain γc increased as the fluorocarbon group was removed from the proximity of the polymer backbone by intervening methylene groups. A comparison of the wetting properties of polyacrylates containing either a perfluoroisopropyl or n‐perfluoropropyl group showed that the polymer containing the isopropyl group had a lower γc.
Polymers derived from fluoroketones. III. Monomer synthesis, polymerization, and wetting properties of poly(allyl ether) and poly(vinyl ether)
Authors: Pittman Allen G. , Ludwig Barbara A. , Sharp Dennis L. 
Published: April 2003

AbstractThe synthesis and polymerization of a series of perhaloalkyl allyl and vinyl ethers derived from perhaloketones is described. Data on the critical surface tension of wetting (γc) for high molecular weight polymers of heptafluoroisopropyl vinyl ether and low molecular weight poly(heptafluoroisopropyl allyl ether) is also presented. Preparation of the allyl ethers is a one‐step, high‐yield displacement reaction between the potassium fluoride–perhaloacetone adduct and an allyl halide, such as allyl bromide. The vinyl ethersare prepared by a two‐step process which involves displacement of halide from a 1,2‐dihaloethane with a KF–perhaloacetone adduct and dehydrohalogenation of the 1‐halo‐2‐perhaloalkoxyethane to a vinyl ether. Low molecular weight polymers were obtained with heptafluoroisopropyl allyl ether by using a high concentration of a free‐radical initiator. The low molecular weight poly(heptafluoroisopropyl allyl ether) had a γc of 21 dyne/cm. No polymer was obtained with tributylborane–oxygen or with VCl3–AIR3, with gamma radiation, or by exposure to ultraviolet light. High molecular weight polymers were obtained from heptafluoroisopropyl vinyl either by using either lauryl peroxide or ultraviolet light but not by exposure to BF3–etherate. The γc for poly(heptafluoroisopropyl vinyl ether) ranged from 14.2 to 14.6 dyne/cm., and the significance of this value is discussed in relation to the γc for poly(heptafluoroisopropyl acrylate).
Effect of surfactants on the polymerization of acrylamide in aqueous solutions
Authors: Friend J. P. , Alexander A. E. 
Published: April 2003

AbstractThe polymerization of acrylamide in aqueous surfactant solutions, initiated by potassium persulfate, has been investigated, dilatometry being used to follow the conversion. It has been shown that below the critical micellar concentration (CMC), cationic, anionic and non‐ionic surfactants have no effect, while above the CMC only cationic soaps have an effect, lowering both the rate of polymerization and the molecular weight of the resultant polymer.
Copolymerization of 4‐methyl‐1,3‐dioxene‐4 with maleic anhydride and terpolymerization with styrene as the third component
Authors: Kawai Wasaburo 
Published: April 2003

AbstractCopolymerization of 4‐methyl‐1,3‐dioxene‐4 with maleic anhydride was carried out. The monomer reactivity ratio was determined to be r1 = 0.18, r2 ∼ 0 in terminal model and r1 = 0.015, r1′ = 0.224, r2′ = r2′ = 0 in the penultimate model.Calculations of run number, linkage probabilities, and number‐average chain length in the terminal model and comparison of n (mole ratio of each monomer unit content in copolymer) in each model with the experimental value was made. From these results, the obtained polymer was confirmed to be alternating. Terpolymerization of 4‐methyl‐1,3‐dioxene‐4 with maleic anhydride and styrene was also carried out. The agreement of the experimental value (titration by indicator or electroconductivity) of maleic anhydride content with the theoretical value confirms that the terpolymer has a DMS triad sequence.
Synthesis of ordered copolyamides by the interfacial polycondensation of the hydrolyzate of bisimidazoline with diacid chloride
Authors: Kagiya Tsutomu , Izu Masatsugu , Matsuda Takehisa , Matsuda Moriyasu , Fukui Kenichi 
Published: April 2003

AbstractOrdered copolyamides were prepared by the interfacial polycondensation of the hydrolyzate of bisimidazoline in the aqueous solution with diacid chloride in chloroform solution; bisimidazolines used were 1,4‐bis(imidazoline‐2‐yl)butane and 1,4‐bis(imidazoline‐2‐yl)‐octane; diacid chlorides used were adipoyl chloride, sebacoyl chloride, and terephthaloyl chloride. The aqueous solutions of the hydrolyzates of bisimidazolines were prepared by heating the aqueous solutions of imidazolines at 70°C. It was shown by infrared spectra and paper electrophoresis of the hydrolyzates that bisimidazolines were hydrolyzed to give quantitatively diamines containing amides linkages of the type H2N(CH2)2NH‐CORCONH(CH2)2NH2. The regularity in the sequence of the copolyamide of nylon 26 and nylon 2T prepared from the hydrolyzate of 1,4‐bis(imidazoline‐2‐yl)butane and terephthaloyl chloride was studied by NMR spectrometry: it was concluded that the copolyamide was highly ordered.