bluuebunny/crossref_metadata_2025 huggingface dataset:
Equilibrium anionic polymerization of β‐methoxycarbonylpropionaldehyde
Authors: Hashimoto Kazuhiko , Sumitomo Hiroshi
Published: April 2003

β‐Methoxycarbonylpropionaldehyde (MCPA) was polymerized in tetrahydrofuran (THF) with benzophenone–monolithium complex as the initiator. An equilibrium between the monomer and its polymer was observed in the temperature range of −96 to −78°C. MCPA had lower polymerizability than ether‐substituted aldehydes and their corresponding unsubstituted aliphatic aldehydes in the temperature range. The thermodynamic parameters were evaluated from the temperature dependence of the equilibrium monomer concentration: ΔHss = −4.3 ± 0.2 kcal/mole, ΔSss = −21.9 ± 1.0 cal/mole deg, Tcss = −76°C. Not only an ether substitution but also an ester substitution in propionaldehyde caused the decrease in the absolute values of the thermodynamic parameters for the aldehyde polymerization. These substituent effects may have been the result mainly of the strong intermolecular dipole–dipole interactions of polar groups in monomer states.
Investigation of polycarbodiimide additive effects on the acid‐catalyzed hydrolysis of PBT
Authors: Lum Richard M.
Published: April 2003

The effects of a polycarbodiimide additive on the thermal stability of PBT are investigated using evolved gas analysis techniques. Measurements of the dynamic variations in sample‐cell pressure during PBT pyrolysis indicate that the maximum decomposition rate for the sample containing the additive is shifted to higher temperatures. The low‐temperature evolution of tetrahydrofuran (THF) and CO2 is significantly reduced, suggesting that stabilization is achieved by increasing polymer resistance to acid‐catalyzed hydrolysis. A condensed‐phase mechanism is indicated, since volatile species characteristic of the additive compound are not observed.
Particle nucleation in emulsion polymerization. IV. Nucleation in monomer droplets
Authors: Hansen F. K. , Ugelstad J.
Published: April 2003

Nucleation in finely dispersed monomer emulsions in competition with homogeneous and micellar mechanism was studied. The emulsions were prepared with a high‐pressure homogenizer under varying homogenizing conditions and made stable by the addition of hexadecane to the monomer. Sodium dodecyl sulfate was used as emulsifer. The number of particles in latexes polymerized with potassium persulfate and benzoyl peroxide initiators was measured and plotted as a function of the free emulsifier concentrations. With persulfate initiator the particle number achieved a minimum in the transition region between droplet and water phase–micellar nucleation mechanisms. With very fine emulsions Smith–Ewart case II kinetics with n = 0.5 applied. The reaction rate, which differed from conventional emulsion polymerizations, decreased with time up to the point at which n began to increase. In these runs the particle size distribution became nearly monodisperse.
Study of physicochemical interactions in metal–polymer systems
Authors: Belyi V. A. , Goldade V. A. , Neverov A. S. , Pinchuk L. S.
Published: April 2003

This article deals with the investigation of adhesive joints of unlike metals separated by layers of thermoplastics. Experimental data are presented on electrical conductivity of polymers at temperatures of 333–573 K in the electric field of 1–102 V/cm. Infrared (IR) spectroscopy data have been used to establish correlation between the parameters of the voltage generated on the metal–polymer specimens and the existence of groups that can form hydrogen bonds. Adhesive strength of the adhesive joints is discussed in connection with the performance of a metal–polymer–metal voltaic couple when the adhesive joints are being formed. The results presented allow a conclusion that polymeric dielectrics exhibit properties of electrolytes when heated in contact with metals. Therefore electrochemical interactions between components of metal–polymer systems should be taken into consideration when predictions are made of performance characteristics of industrial materials based on polymers and metals.
Kinetics and mechanism of the formation of glycol esters: Benzoic acid–ethylene glycol system
Authors: Reimschuessel H. K. , Debona B. T. , Murthy A. K. S.
Published: April 2003

Esterification‐hydrolysis and condensation‐glycolysis are the principal equilibria entailed in a system comprised of benzoic acid, ethanediol, ethanediol monobenzoate, ethanediol dibenzoate, and water. These equilibria are characterized by three interrelated equilibrium constants that pertain to the hydrolysis of both ethanediol monobenzoate and ethanediol dibenzoate and to the condensation of ethanediol monobenzoate. The rate constants related to these reactions and to the corresponding reverse reactions were all found to be functions of the concentration of carboxy groups. Antimony triacetate, a well‐known transesterification catalyst, catalyzed the condensation reaction strongly but did not affect the esterification reaction. Based on a mechanism that entailed the considered three principal equilibrium reactions, a set of both the kinetic and thermodynamic parameters was obtained by a nonlinear regression procedure. With these parameters the nonlinear rate equations were integrated numerically, using the fourth‐order Runge‐Kutta method. Excellent agreement between the values thus calculated and the experimental data were obtained in all cases except when considerable concentrations of both benzoic acid and ethanediol dibenzoate were present in the system. It has been concluded that in these instances the formation of the dibenzoate is paralleled by a pyrolysis reaction that is strongly catalyzed by carboxy groups.
Terephthalic acid esterification kinetics: 2‐(2‐methoxyethoxy)ethyl terephthalates
Authors: Reimschuessel H. K. , Debona B. T.
Published: April 2003

The process of esterification of terephthalic acid is characterized by a mechanism that involves three equilibrium reactions. Two are esterification‐hydrolysis equilibria entailing the reactions of the two terephthalic acid carboxyl groups with alcoholic hydroxyl groups, whereas the third one is a transesterification‐acidolysis equilibrium that is concerned with the reaction between two terminal terephthalic acid moieties. The products of these three interrelated equilibria are terephthalic acid, its monoester and diester, the particular alcohol, and water. The alcohol used in the present study was 2‐(2‐methoxyethoxy)ethanol. Equilibrium constants and rate constants were developed from experimental data obtained at 230°C. The esterification‐hydrolysis reactions were found to be catalyzed by carboxyl groups, and the rate of transesterification was found to be a function of the terephthalic acid concentration. With the constants developed, the system of nonlinear differential equations, as derived from the mechanism postulated, was integrated numerically using the Runge‐Kutta method. Good agreement between calculated and experimental values was observed.
The viscoelastic behavior of poly(isobutylene oxide) exposed to UV irradiation
Authors: Yoshinari Makoto , Murakami Kenkichi
Published: April 2003

The stress relaxation of poly(isobutylene oxide) in air was measured while it was exposed to UV irradiation. It was found that the relative stress increased markedly and the polymer degraded extensively with UV irradiation time. In other crystalline polymers that degrade easily, e.g., polyoxymethylene and polypropylene, the relative stress increased somewhat. However, such behavior was not found in another crystalline polymer that was difficult to degrade, polyethylene. It was also found that the increase in the relative stress depended on the strain imposed on the sample, exposure temperature, the degree of crystallinity of the sample, the degree of initial degradation of the sample, and the degree of orientation of the chain molecules in the sample. However, these changes were insignificant in experiments performed under N2.
Effect of the fine structure of viscose hydrocellulose on its adsorption properties
Authors: Shinouda H. G. , Abdel Moteleb M. M.
Published: April 2003

From the heat of wetting in water and the iodine adsorption measurements of certain hydrolytic residues prepared by the acid hydrolysis of viscose rayon in the absence and presence of FeCl3, a comparison was made between their water adsorption capacity and iodine molecules. The data obtained revealed first that in the initial stages of acid action of the fibers the adsorption cites accessible to water or iodine molecules decrease to some extent, depending on the hydrolytic condition. Second, in the inner fine structure of the various residues examined, there remains a high proportion of cites accessible to water molecules that are inaccessible to iodine. These results are explained by the fact that the water molecules can penetrate the submicroscopic structure of cellulose chains by molecular forces and the swelling effect.
Evaluation of monomer reactivity ratios of more complex copolymerization schemes, with application to the penultimate unit effect in methyl acrylate–butadiene copolymerization
Authors: van der Meer R. , Alberti J. M. , German A. L. , Linssen H. N.
Published: April 2003

A generally applicable computational procedure, which permits the accurate evaluation of the kinetic parameters of intricate and extended copolymerization schemes to be made, is described. This method is based on a numerical integration of the differential equation, and, according to the (improved) curve‐fitting I procedure, experimental errors in both measured variables are considered. Furthermore, a description is given of theFtest, in which a statistical comparison between the resulting residual sums of squares of two different schemes offers a possibility of selecting the most probable kinetic scheme for a given copolymerization system. The capability and applicability of the methods developed is demonstrated for the free radical copolymerization kinetics of methyl acrylate (MA) (M1) and butadiene (BD) (M2) with toluene as solvent. Here, the simple copolymer equation is unsatisfactory because a significant penultimate unit effect in BD macroradical reactivity shows up:k222/k221= 0.84, andk122/k121= 0.53, andk11/k12= 0.088. The microstructure of the copolymer samples, determined by infrared (IR) spectroscopy, shows a decreasing fraction of BD units in the vinyl configuration in favor of the fraction of BD units in thecis‐vinylene andtrans‐vinylene configuration at increasing MA (m) content. Statistical considerations indicate a strongly diminished probability of finding BD (b) in the vinyl configuration in ∼mb∼ transitions. Steric hindrance or polar repulsion of the ester side group of the penultimate MA unit probably account for the increased preference for monomer addition to the C4site over the C2site of the BD macroradical.
Coupling of acrylic polymers and collagen by use of a water‐soluble carbodiimide. I. Optimization of reaction conditions
Authors: Lloyd Douglas R. , Burns Charles M.
Published: April 2003

A means of coupling synthetic polymers of biomedical interest with collagen under mild conditions was investigated as a part of preliminary studies in the development of a biomedical adhesive. The coupling agent, 1‐cyclohexyl‐3‐[2‐morpholinyl‐(4)‐ethyl]carbodiimide, provides a covalent bond between the acrylic polymer and collagen. The variables affecting the establishment of this bond in solution are concentration of the carboxylic group on the acrylic polymer, concentration of the acid‐soluble collagen, concentration of the coupling agent, pH, and time of reaction. Optimum values of these variables have been obtained experimentally.
A new synthetic route to α‐alkylacrylic esters and α‐alkylacrylonitriles
Authors: Ponticello I. S.
Published: April 2003

α‐Alkylacrylic esters and α‐alkylacrylonitriles have been synthesized by cracking their cyclopentadiene adducts. The latter were derived by treatment of the lithium enolates of cyclopentadiene‐blocked acrylates or acrylonitriles with alkyl halides.
Crosslinking of polystyrene via pendant maleimide groups
Authors: Stevens Malcolm P. , Jenkins Aubrey D.
Published: April 2003

Maleimide groups were incorporated into polystyrene by a mild Friedel–Crafts procedure using N‐chloromethylmaleimide. Films and solutions of the modified polymer underwent photocrosslinking at a rate that was not appreciably affected by addition of photosensitizer. Free radical, thermal, and Diels–Alder crosslinking were also investigated.
Photooxidation of polyolefins and their light stability
Authors: Karpukhin O. N. , Slobodetskaya E. M.
Published: April 2003

It is shown that all peculiarities of polypropylene photooxidation and alteration of its mechanical properties in this process are a process of second‐order termination reaction. The influence of natural conditions (varied temperature and light intensity) on this process are considered.
Photochemistry of ring‐substituted polystyrenes. II. Photolyses of poly(p‐fluoro‐, p‐chloro‐, and p‐bromostyrene)s
Authors: Weir N. A. , Milkie T. H.
Published: April 2003

The photodegradation of thin films of p‐fluoro (PPFS), p‐chloro (PPCS), and p‐bromo (PPBS) styrenes brought about by exposure to 254‐nm radiation under high vacuum was studied. Mass spectroscopic measurements indicated that hydrogen and hydrogen halides were the only gaseous products because yields of H2 and HF from poly(p‐fluorostyrene) were much smaller than the corresponding yields of chloro‐ and bromo‐substituted polymers. UV and visible spectra of degraded films indicated the presence of unsaturated species, for the initial rates of formation were comparable in PPFS and PS but considerably greater in PPCS and PPBS. Solubility and molecular weight data indicated simultaneous crosslinking and chain scission; both PPCS and PPBS showed an inordinately high susceptibility to crosslinking. These observations can be rationalized in terms of the energetics of abstraction reactions by H and halogen atoms and in terms of scission of the Ph–Br and Ph–Cl bonds which lead to the participation of radicals in the para position in crosslinking. Some qualitative correspondence between the Hammett parameters of the p‐substituents and rates of H2 formation in the substituted polymers was observed. Quantum yields of gaseous product formation and probabilities of crosslinking and chain scission were also determined for the three polymers. Mechanisms of the various reactions are discussed.
Singlet oxygenation of 1,2‐poly(1,4‐hexadiene)s
Authors: Golub Morton A. , Rosenberg Mark L. , Gemmer Robert V.
Published: April 2003

The microstructural changes that occur in cis and trans forms of 1,2‐poly(1,4‐hexadiene) during methylene blue‐photosensitized oxidation were examined by infrared (IR) and 13C‐NMR spec‐troscopy. The singlet oxygenation of these polymers yielded the expected allylic hydroperoxides accompanied by double bond shifts to new vinyl and trans‐vinylene double bonds. The photosensitized oxidation exhibited zero‐order kinetics; the relative rates for the cis‐ and trans‐1,2‐poly(1,4‐hexadiene)s were approximately 3.8:1.0.
Substituent parameters for radical reactions: Cerium(IV)‐substituted acetophenones–acrylonitrile system
Authors: Rout Swoyam P. , Mallick Nigamananda , Rout Anuradha , Rout M. K.
Published: April 2003

The present investigation describes a new approach for the determination of radical substituent parameters σ. The technique has been developed by an ingenious combination of two equations, one proposed by Yamamoto and Otsu and the other by Streitwieser and Perrin. The σ values for different substituents were first evaluated by application of this newly developed technique to the Ce(IV)‐substituted toluenes–acrylonitrile system. The validity of these values was then tested by application to another system, the Ce(IV)‐substituted acetophenones–acrylonitrile system, which is the subject of the present study.
Poly(β‐Amino acids). VI. Synthesis and conformational properties of poly[(r)‐3‐pyrrolidinecarboxylic acid]
Authors: Yuki Heimei , Okamoto Yoshio , Kobayashi Yoshiko
Published: April 2003

Racemic and optically active 3‐pyrrolidinecarboxylic acids (β‐proline) were synthesized, and their polymers, poly[(RS)‐β‐proline] and poly[(R)‐β‐proline], were prepared by the polycondensation reaction of the p‐nitrophenyl esters. Model compounds, N‐cyclopentylcarboxylic acid pyrrolidide and N‐cyclopentylcarbonyl‐(R)‐3‐pyrrolidinecarboxylic acid pyrrolidide, were synthesized to elucidate the conformation of the polymer. The solution properties of poly[(R)‐β‐proline] and the model compounds were investigated by means of circular dichroism (CD) and NMR spectroscopy. The spectral patterns of the polymer and model compounds were similar in various solvents. Poly[(R)‐β‐proline] and poly[(RS)‐β‐proline] showed identical NMR spectra. These results suggest that poly[(R)‐β‐proline] may exist in a random conformation consisting of mixtures of cis and trans amide bonds. The conformational study of cyclopentanecarboxylic acid pyrrolidide by NMR spectroscopy with a shift reagent, Eu(fod)3, in CDCl3 implied that the plane containing the amide group bisects the cyclopentane ring. This suggests that each amide plane in the polymer in chloroform may also bisect the pyrrolidine ring.
Cyclic acetal‐photosensitized polymerization. VIII. Photopolymerizations of diallylidene pentaerythritol and its derivatives
Authors: Ouchi Tatsuro , Tatsumi Masakazu , Oiwa Masayoshi
Published: April 2003

The photopolymerization of diallylidene pentaerythritol (DAPE) was carried out in benzene at 40°C without the use of the usual initiator. DAPE was polymerized with the ester radical generated from DAPE by photoirradiation. To investigate the effect of dimethyl groups at the α,α‐ or β,β‐positions of vinyl groups on the polymerization, photopolymerizations of dimethallylidene pentaerythritol (DMPE) and dicrotylidene pentaerythritol (DCPE) were carried out and kinetically studied from the standpoint of the degradative chain transfer by the allylidene group and cyclization by two double bonds. The results can be summarized as follows: (1) The relation between the rate of polymerization, Rp, and the monomer concentration [M] can be expressed as [M]/Rp = (A[M] + B)/(2[M] + C), where A, B, and C are constants. (2) The ratios of the rate constant of unimolecular cyclization to the total rate constants of bimolecular propagation and the chain transfer of uncyclized radical were estimated as 1.12, 0.26, and 0.16 mole dm−3 for DAPE, DMPE, and DCPE, respectively; the cyclizations hardly took place. (3) The rate of polymerization and the molecular weight of the polymer were small because of the degradative chain transfer by the allylidene group.
Effect of polyion conformation on dye binding. IV. Fluorescence of auramine O in relation to its binding to synthetic polyacids
Authors: Erny B. , Muller G.
Published: April 2003

The effect of polymer conformation, polymer concentration, and added salt concentration on the quantum yield ϕ of Auramine O (AuO) is discussed in connection with dialysis equilibrium data. The quantum yield per bound dye molecule (ϕ/q) assumes different values which are related principally to solvation changes in the environment of the binding sites. Binding to globular compact a states results in high ϕ/q, whereas low ϕ/q (of the order of magnitude of ϕ of free AuO) are observed for the binding to expanded solvated b states. The quantum yield of bound AuO is therefore affected by the organic nature of the environment, but shows little or no relation to the amount of bound dye molecules.
Effect of inititiator on the molecular weight distribution in dispersion polymerization of styrene
Authors: Almog Yaacov , Levy Moshe
Published: April 2003

Dispersion polymerization of styrene in the particle size range of 10 μ with lauroyl peroxide as initiator results in a double‐peak molecular weight (MW) distribution. The high‐MW fraction was due to emulsion polymerization. The same phenomenon also exists in AIBN and benzoyl peroxide initiation, although it is less obvious. The kinetics of the reaction for dispersion polymerization was dependent on the concentration of the dispersing agent and the nature of the initiator.
Distribution and catalytic activity of sulfonic acid groups in organic ion exchangers
Authors: JeřáBek K.
Published: April 2003

The existence of inhomogeneities in the polymer structure of ion exchangers was demonstrated and their influence on catalytic properties was shown. The results are based on the differences in catalytic activity of two ion exchangers with low degrees of sulfonation differing in the distribution of active groups within the polymer particles.
Synthesis of highly branched perfluoroethers by direct fluorination, promising new materials based on the hexafluoroacetone–ethylene copolymer
Authors: Gerhardt G. E. , Dumitru E. T. , Lagow R. J.
Published: April 2003

Direct fluorination of the hexafluoroacetone‐ethylene copolymer, [CH2CH2OC(CF3)2]n, under conditions designed to promote fragmentation of the polymer chain has led to the synthesis of a number of structurally unusual branched perfluoropolyethers [CF2CF2O‐C(CF3)2]n. These new perfluoropolyethers have been characterized by 19F‐NMR, and their physical properties are reported. Direct fluorination under milder conditions yields a high‐molecular‐weight perfluoropolyether.
Radiation‐induced polymerization at high dose rate. II. α‐Methylstyrene in bulk
Authors: Hayashi Kanae , Kotani Noritaka
Published: April 2003

Bulk polymerization of α‐methylstyrene was carried out in a wide dose rate range, 7.6–256 rad/sec by γ rays and 8.5 × 103–2.1 × 105 rad/sec by electron beams. At high dose rate by electron beams, cationic polymerization took place along with formation of oligomeric product of DPn = ∼4. At low dose rate by γ rays, radical polymerization was found to occur in water‐saturated monomer. The cationic polymerization at high dose rate proceeds with essentially the same mechanism as was already known in γ‐ray polymerization of dry monomers. Relatively low reaction rate of the cationic polymerization compared with that of styrene is explained with the fact that the propagation of α‐methylstyrene is much more easily inhibited by a slight amount of water.
Polymerization of coordinated monomers. XVI. Stereoregulation in the alternating copolymerization of methyl methacrylate with styrene in the presence of metal halides
Authors: Hirai Hidefumi , Tanabe Tsuneaki , Koinuma Hideomi
Published: April 2003

Triad cotacticities of alternating copolymers of methyl methacrylate with styrene prepared in the presence of zinc chloride, ethylaluminium sesquichloride, and ethylboron dichloride are investigated from the mechanistic point of view by means of 1H‐ and 13C‐NMR. The cotacticities from 1H‐NMR spectra are obtained accurately by using α‐d‐styrene in the place of styrene and by measuring the spectra on the copolymer in o‐dichlorobenzene at 170°C. The relative intensities of three peaks of the splitting signal for the methoxy protons in the nonalternating copolymers obtained by the use of benzoyl peroxide in the absence of metal halides agree well with the cotacticity distribution calculated theoretically by the Lewis‐Mayo mechanism with the stereoregulation following Bernoullian statistics. The splitting signals in the 1H‐ and 13C‐NMR spectra of the alternating copolymers prepared in the presence of metal halides cannot be explained by the same mechanism. The relative intensities of three peaks of the splitting signals for the methoxy protons and for the carbonyl carbon in the methyl methacrylate unit (the contents of cotactic triads centered by the methyl methacrylate unit) are not equal to those for the aromatic C1 carbon in the styrene unit (the contents of cotactic triads centered by styrene unit). The value of f2Y ‐ 4fxfz is not equal to zero, where fx, fy, and fz are the cosyndiotactic, coheterotactic, and coisotactic triad contents, respectively, in the alternating copolymer. Copolymers obtained in the presence of zinc chloride are not exactly equimolar alternating but always contain a methyl methacrylate unit in excess, and the relative intensities of the three peaks for the aromatic C1 carbon change with the copolymer composition. These results are explained by a proposed mechanism: the alternating copolymerization proceeds through the homopolymerization of a ternary molecular complex composed of a metal halide, methyl methacrylate, and styrene, accompanied with the stereoregulation following first‐order Markovian statistics; the increase of methyl methacrylate content in the copolymer prepared in the presence of zinc chloride is caused by the participation of the binary molecular complex composed of a metal halide and methyl methacrylate in addition to the ternary molecular complex.
Functional polymers. II. Synthesis and properties of new polymeric cinchona alkaloids
Authors: Kobayashi Norio , Iwai Kiyoko
Published: April 2003

New polymeric cinchona alkaloids having favorable structures and properties for asymmetric catalysts have been prepared by radical copolymerization of the alkaloids with acrylonitrile using azobisisobutyronitrile (AIBN) as an initiator. Of the many reaction solvents tried, dimethylformamide (DMF) was found to be the solvent of choice especially for a large‐scale synthesis. Alkaloid monomers employed were free dalkaloids, such as quinine, quinidine, cinchonidine, and cinchonine, and modified ones including 9‐O‐ethoxycarbonylquinine and quinine salts. The copolymers were thermally stable powders, soluble in DMF and DMSO, and insoluble in common organic solvents. They were found to be converted into water‐soluble polymeric alkaloids by hydrolysis with alkaline hydrogen peroxide.
High conversion polymerization. VI. Detailed examination of the kinetic model
Authors: Dionisio Jose M. , O'driscoll Kenneth F.
Published: April 2003

A previously developed model which has been used to describe the kinetic behavior of free radical polymerization in the region of the gel effect is here subjected to a detailed quantitative examination. It is shown, using data for the polymerization of methyl methacrylate, that the quasi‐steady‐state assumption is valid during the gel effect, and that the model provides a good description of the chain lengths and concentrations of different species present in the reaction. The postulate that primary radical termination becomes important as the gel effect advances is tested and found to be true.
Comparison of the precision of estimation of copolymerization reactivity ratios by current methods
Authors: McFarlane Randall C. , Reilly Park M. , O'driscoll Kenneth F.
Published: April 2003

Six recently proposed methods for analyzing copolymerization composition data have been compared to a nonlinear least‐squares analysis to ascertain the precision of the six methods in determining reactivity ratios. Data used were simulated for five hypothetical monomer pairs with three different types of experiment design and contained error structures similar to those observed experimentally. The results of the comparisons suggest that retrospective analyses of existing copolymerization data should only be done with a nonlinear least‐squares analysis. For new data, the design of experiments is of great importance, and when done properly allows the use of some of the linear least‐squares methods of analysis.
Effect of pyridine on the kinetics of polymerization of methyl methacrylate initiated by benzoyl peroxide and azobisisobutyronitrile at 60°C
Authors: Ghosh P. , Mukhopadhyay G.
Published: April 2003

Solution polymerization of MMA, with pyridine as the solvent and BZ2O2 and AIBN as thermal initiators, was studied kinetically at 60°C. The monomer exponent varied from 0.45 to 0.91 as [BZ2O2] was increased from 1 × 10−2 to 30 × 10−2 mole/liter in a concentration range of 8.3‐4.6 mole/liter for MMA. For AIBN‐initiated polymerization the monomer exponent remained constant at 0.69 as [AIBN] varied from 0.4 × 10−2 to 1.0 × 10−2 mole/liter in the same concentration range for MMA. The k2p/kt Value increased in both cases with an increase in pyridine concentration in the system. This was explained in terms of an increase in the kp value, which was due presumably to the increased reactivity of the chain radicals by donor‐acceptor interaction between the molecules of solvent pyridine and propagating PMMA radicals and in terms of lowering the kt value for the diffusion‐controlled termination reaction due to an increase in the medium viscosity and pyridine content.
Reaction of polyurethane foam with dry steam: Kinetics and mechanism of reactions
Authors: Gerlock J. L. , Braslaw J. , Mahoney L. R. , Ferris F. C.
Published: April 2003

The reaction of a polyether‐based polyurethane foam with dry atmospheric pressure steam was examined as one approach to waste polyurethane foam recovery. Complete reaction at temperatures between 190 and 230°C yielded high‐quality polyol, isomeric toluenediamines, and carbon dioxide as primary products. Kinetic analysis of toluenediamine yields versus time suggested the occurrence of a parallel first‐order reaction scheme wherein urethane linkages react up to 50 times faster than urea linkages. The results derived from kinetic experiments and ancillary thermochemical and spectroscopic studies indicated that urethane linkages are broken by direct hydrolysis, whereas urea linkages undergo thermal dissociation to parent isocyanate and amine. Subsequent rapid hydrolysis of the isocyanate produced was necessary to obtain high yields of toluenediamine products. The rate of the slower reaction, dissociation of urea linkages, can be enhanced by a factor of 20 by the addition of trace amounts of sodium hydroxide to the foam.
An analysis of the substitution effects involved in diepoxide‐diamine copolymerization reactions
Authors: Charlesworth John
Published: April 2003

The relative reactivity of the functional groups present in aromatic amine and diepoxide monomers has been investigated by gel permeation chromatography. The ratio of rate constants for the consumption of the secondary and primary amine hydrogens involved in the reaction between aniline and phenyl glycidyl ether has been calculated to equal approximately 0.5. In the case of the reaction between N‐methy aniline and diglycidyl ether of bisphenol A (DGEBA) the rate constant ratio for the consumption of the first and second epoxide groups in the DGEBA molecule is also approximately 0.5. In contradiction to previously published data these results suggest that substitution effects are unimportant for aromatic amines as well as DGEBA. Furthermore, etherification side reactions, consuming epoxide groups at the expense of the amine–epoxide reaction, also appear to be insignificant.
Anionic polymerization with alkaline earth counterion. III. Aging of oligo‐ and polystyryl‐barium and ‐strontium in THF
Authors: Mathis Claude , Christmann‐Lamande Lydia , Francois Bernard
Published: April 2003

The self‐deactivation of polystyryl‐barium and polystyryl‐strontium in tetrahydrofuran (THF) results essentially from protonation by the solvent. The deactivation constant kd of this reaction is independent of carbanion concentration, length, and functionality of chains. Relations of kd with temperature are: polystyryl‐barium: kd = 6.25 × 107 exp(‐18,900/RT) sec−1; polystyryl‐strontium: kd = 4.1 × 106 exp(−16,000/RT) sec−1. The self‐deactivation of α,ω‐dicarbanionic oligostyryl‐barium is a nonrandomlike reaction. Residual living oligomers are left dicarbanionic even if an important deactivation occurs.
The transacetalization reaction during the etherification of poly(oxymethylene)diol [α‐hydro‐ω‐hydroxypoly(oxymethylene)] with orthoesters in the presence of lewis acids
Authors: Colombo Paolo , Custro Sergio , Radici Pierino
Published: April 2003

A transacetalization reaction occurs during the etherification of poly(oxymethylene)diol [α‐hydro‐ω‐hydroxypoly(oxymethylene)] with orthoesters and an important modification of molecular structure takes place. The intermediates formed during the transacetalization reaction are emphasized. The connection between this reaction and the other reactions during the etherification of poly(oxymethylene)diols is discussed.
Evaluation of polymerization rate by chain length dependence on polymer–polymer termination and primary radical termination in radical polymerization
Authors: Ito Katsukiyo
Published: April 2003

In order to analyze the polymerization rate at high initiation rate and/or low monomer concentration, the rate equations are derived by a rate formulated previously for polymer–polymer termination and another rate for primary radical termination, which is formulated here (both rates depend on chain length of polymer radical). Such equations would be applicable to the kinetic data in the polymerizations of styrene and methyl methacrylate. This shows that the assumption that both rates are independent of chain length overestimates the rate of primary radical termination.
Investigation of cationic copolymerization of styrene with p‐benzoquinone
Authors: Ragimov A. V. , Nagiev A. Yu. , Liogonky B. I. , Berlin A. A.
Published: April 2003

The kinetics of copolymerization of styrene with p‐benzoquinone in the presence of BF3OEt2 is investigated. The rate constants and activation energy of the copolymerization process are determined. The reaction orders for monomer and catalyst are estimated. It is found that the rate of styrene and quinone copolymerization increase and the induction period decreases owing to addition of the latter. It is shown that the copolymerization rate achieves its maximum at an equimolal ratio of monomers. This phenomenon is explained by formation of active molecular complex between styrene and p‐benzoquinone. On the basis of obtained data the course of copolymerization is interpreted and the cationic mechanism of copolymerization process is proposed.
Polymerization of methyl methacrylate initiated by oligoglycine, water, cupric ion, and carbon tetrachloride
Authors: Ree Keiu , Kawasaki Hiroshi , Minoura Yuji
Published: April 2003

The polymerization of methyl methacrylate (MMA) was carried out in the presence of oligoglycines (glycine, its dimer, trimer, tetramer, etc.), water, cupric ions, and carbon tetrachloride. It was found that poly‐MMA is formed in the water layer and that the system using triglycine gives the maximum polymer yield. On the effect of pH of water layer, the rate of polymerization is faster in the alkalic condition (pH 8–10) than in normal condition (pH 3.8), while in the acidic media (pH 2–3), the rate is not accelerated. From the results of kinetic studies, the polymerization rate is dependent on the 0.5 power of the amount of diglycine or cupric ion, and it is independent of the amount of MMA. The polymerization mechanism was discussed.
Effect of sovents on radiation‐induced ionic graft polymerization
Authors: Kabanov V. Ya. , Aliev R. E. , Sidorova L. P.
Published: April 2003

The influence of various solvents on radiation‐induced cationic (grafting of vinyl‐n‐butyl ether onto polyethylene) and anionic (grafting of 2‐methyl‐5‐vinylpyridine onto polyethylene) graft polymerization was studied. This ionic grafting was performed in thoroughly dried systems at room temperature. It was established that electron‐acceptor solvents promote cationic grafting but that electron‐donor solvents promote the anionic. A clear correlation between the donor number of solvents and grafting value by the anionic mechanism was shown. There was no correlation between dielectric constants and grafting values. The reaction orders, according to monomer concentration by 2‐methyl‐5‐vinylpyridine grafting in various solvents, were equal to approximately 1.5 and 2 for the radical and anionic mechanisms, respectively. The effect of solvents on radiation‐induced ionic graft polymerization is discussed. The results of this study indicate the correct choice of solvents for radiation‐induced ionic grafting.
Functional polymers. III. Asymmetric Michael reactions catalyzed by cinchona alkaloid–acrylonitrile copolymers
Authors: Kobayashi Norio , Iwai Kiyoko
Published: April 2003

The enantio‐differentiating abilities of cinchona alkaloid–acrylonitrile copolymers (AN–CA) in the Michael reactions were studied. The reaction of methyl indan‐1‐one‐2‐carboxylate (I) with methyl vinyl ketone in toluene at room temperature yielded product (II) in 24–42% optical yield, depending on the type and frequency of the alkaloid units on the polymeric skeleton. The catalysts were recovered from the reaction mixture by filtration and with retention of their stereoselectivities. Modification of the amino or hydroxyl group of the alkaloid moiety greatly reduced the reaction rate and optical yield. The asymmetric reactions of other donors (III–VII) with methyl vinyl ketone were also studied.
Effect of cyclobutane carbonitrile rings on the glass transition temperature of vinyl copolymers
Authors: Collette J. W. , Gale D. M. , Belletete M. G.
Published: April 2003

A wide compositional range of copolymers of 1‐cyclobutene carbonitrile (CBCN) and 1‐bicyclobutance carbonitrile (BBCN) with common vinyl monomers was prepared in order to study systematically the effect of cyclobutane carbonitrile ring incorporation on the glass transition temperature (Tg). In general, the Tg's of the copolymers are increased in proportion to the weight percent of the small‐ring monomer incorporated, but the 1,2‐mode of incorporation raises Tg more than the 1,3‐mode. Attempts were made to correlate data with quantitative Tg–composition relationships (Fox–Johnston equations). Prediction for nitrile homopolymer Tg's are compared with literature values.
Reactions of stabilizer compounds. III. Oxidative reactions of some 2′‐hydroxy‐2‐phenylbenzotriazole light stabilizers in the AIBN‐initiated autoxidation of cumene
Authors: Hodgeman Daryl K. C. , Gellert Evan P.
Published: April 2003

Oxidative decay of number of commercially important 2′‐hydroxy‐2‐phenylbenzotriazole light stabilizers during the AIBN‐initiated autoxidation of cumene at 65°C is described. The reactivity of the hydroxyphenylbenzotriazoles studied increased in the order 2‐(2′‐hydroxy‐5′‐methyl)phenylbenzotriazole (Ia) < 2‐(2′‐hydroxy‐3′,5′ ‐di‐tert‐pentyl)phenylbenzotriazole (Ie) < 5‐chloro‐2‐(3′,5′‐di‐tert‐butyl‐2′‐hydroxy)phenylbenzotriazole (Ic) < 5‐chloro‐2‐(3′‐tert‐butyl‐2′‐hydroxy‐5′‐methyl)phenylbenzotriazole (Ib). The major product from the reaction of Ib was identified as the cumylperoxycyclohexa‐2,5‐dienone (III). The possible occurrence of these reactions during the degradation of stabilized polymers is discussed.
Determination of initiation rate of copolymerization of acrylonitrile with p‐bromophenyl acrylate carried out in N,N‐dimethylformamide
Authors: Miller Andrzej , Szafko Jerzy
Published: April 2003

Studies of the initiation rate of the copolymerization reaction of acrylonitrile with p‐bromophenyl acrylate initiated by azobisisobutyronitrile in dimethylformamide at 60°C are reported. The inhibition method involved use of stable Banfield's radical (N‐[1,1‐dimethyl 3‐(N‐oxidophenylimine)butyl]‐N‐phenylaminyl oxide). In the case of acrylonitrile, a side reaction effect of the initiation with the stable radical was observed along with a retarding effect resulting from inhibition reaction products (2kdf) = 8.2 × 10−4 min−1. During the inhibited homopolymerization of p‐bromophenyl acrylate a very strong side initiation reaction effect results from the Banfield radical; the inhibition reaction products do not influence the further course of the polymerization reaction. Side initiation effects of the Banfield radical (BR) increase with increasing concentration of p‐bromophenyl acrylate. The overall contribution of the side initiation reaction changes for different comonomer mixtures; with their compositions the actual changes are nonadditive. The inhibition reaction products do not influence the further course of copolymerization. The initiation rate in monomer mixtures depends on their composition and may be described by the following relation:
Model for predicting the composition of copolyesters: Polymerization of terephthalic acid, 2,2′‐oxydiethanol, and 2,2‐dimethyl‐1,3‐propanediol
Authors: Sandhu M. A. , Fields R. D.
Published: April 2003

Copolyesters of two glycols and a dicarboxylic acid moiety are frequently made to obtain specific physical properties. In the synthesis of these polymers an excess of glycol is used in the ester‐exchange reaction and then removed during the polycondensation reaction to form a high‐molecular‐weight product. A model has been developed to predict the final polymer composition. The derivation is based on equilibria of reaction species (free glycol, polymer chain ends, and ester links) and the relative vapor pressures of the two reacting glycols. Calculated results are compared with experimental results of poly(2,2′‐oxydiethylene: 2,2‐dimethyl‐1,3‐propylene terephthalate)s. There is good agreement between calculated and experimental compositions. The model can be used to calculate the glycol concentrations that must be used to make a specific polymer composition. This model should also be useful in the calculation of other mole ratios of glycol to dicarboxylic acid that will make the same composition.
Kinetics of radical polymerization. XXX. Polymerization of styrene in solution
Authors: Földes‐Berezsnich T. , Szesztay M. , Boros‐Gyevi E. , TüdöS F.
Published: April 2003

A study was made on the AIBN‐initiated polymerization of styrene in benzene and dimethyl formamide at 50°C. The overall rate and the rate of initiation of the polymerization were determined and the number‐average and weight‐average molecular weights of the polymers formed were measured. The decrease in the rate and degree of polymerization with the decrease in styrene concentration was caused by the corresponding decreases in the rate constants of chain propagation and initiation steps. In the systems studied no chain transfer process occurred with an experimentally measurable rate.
Determination of sulfate and similar end groups in polymers [poly(methyl methacrylate) and polystyrene] by an improved dye interaction method
Authors: Chaudhuri Arindam , Palit Santi R.
Published: April 2003

It has been observed that in a benzene medium the carbinol base of a cationic dye reacts with a polymer with SO3 Na and similar end groups that give rise to a reversible color formation of the dye cation. This reaction can be pushed to completion and consequent intensification of color by adding a benzene‐insoluble acid such as citric acid. This principle has been applied to develop an improved dye interaction method of determining such end groups. The end groups values thus obtained by this method for different poly(methyl methacrylate) and polystyrene samples were found to be in fairly good agreement with those obtained by the dye partition (extrapolation) method.
Photosensitized degradation of polyethylene glycols in aqueous solutions. I. Viscosimetric measurements
Authors: Augustyniak Wlodzimierz , Wojtczak Jan
Published: April 2003

Investigations were performed on acetone and benzene‐sensitized degradation of triethylene glycol (TEG), polyethylene glycol 400 (PEG 400), and polyethylene glycol 4000 (PEG 4000) in aqueous solutions exposed to irradiation at λ = 254 nm and λ ∼ 313 nm. The systems investigated were exposed at 20°C (±1°C) in both deaerated and undeaerated solutions. The course of the photosensitized degradation was examined viscosimetrically. The determined quantum yield (ϕ) of chain scission decreases distinctly as the molecular weight of the polymer rises, irrespective of the wavelength of the light absorbed and deaeration of system exposed.
Effect of solvent on the copolymerization of ethylene and vinyl acetate
Authors: Van Der Meer R. , Aarts M. W. A. M. , German A. L.
Published: April 2003

The ethylene (M1)–vinyl acetate (M2) copolymerization at 62°C and 35 kg/cm2 with α,α′‐azo‐bisisobutyronitrile as initiator has been studied in four different solvents, viz., tert‐butyl alcohol, isopropyl alcohol, benzene, and N,N‐dimethylformamide. The experimental method used was based on frequent measurement of the composition of the reaction mixture throughout the copolymerization reaction by means of quantitative gas chromatographic analysis. Highly accurate monomer reactivity ratios have been calculated by means of the curve‐fitting I procedure. The observed dependence of the r values on the nature of the solvent is surprisingly large and can be correlated with the volume changes (= excess volumes) observed on mixing vinyl acetate (VAc) with the relevant solvent. An increased hydrogen bonding or dipole–dipole interaction through the carbonyl moiety of the acetate side group of VAc, induces a decreased electron density on the vinyl group of VAc, which in turn leads to a decreased VAc reactivity. The differences among the overall rates of copolymerization in the various solvents can be interpreted in terms of a variable chain transfer to solvent and the rate of the subsequent reinitiation by the solvent radical. In the case of benzene, complex formation is believed to play an important part.
Effect of polyion conformation on dye binding. V. Induced optical activity of acridine orange bound to a synthetic nonstereoregular polyelectrolyte
Authors: Beaumais J. , Fenyo J. C. , Muller G.
Published: April 2003

It is shown that the induced Cotton effects in the visible region of the absorption bands of acridine orange in the presence of a nonstereoregular α‐carboxylic polysulfonamide (PLL) can be attributed to stacked bound dye molecules, irrespective of the conformation of the polymer. The existence of an ordered structure seems to be unnecessary for such an induction.
The study of macronet isoporous styrene polymers by gel permeation chromatography
Authors: Tsyurupa M. P. , Davankov V. A.
Published: April 2003

Gel permeation chromatography was used for studying the structure of macronet isoporous styrene polymers swollen in chloroform. The polymers were obtained by crosslinking polystyrene either in a solution or in a swollen state using monochlorodimethyl ether and p‐xylylenedichloride via the Friedel–Crafts reaction. It is shown that the networks obtained by structurization of concentrated polystyrene solution in a good solvent are characterized by loose structure, fine pores (ca. 10 Å), and narrow pore distribution. In poor solvents or in strong dilution of polystyrene and at the instant of net formation, the polymers that are obtained contain, in addition to fine pores, large pores with diameters up to 300 Å.
Fibrillar aggregation in cotton cellulose subjected to multiple swelling treatments with alkali
Authors: Manjunath B. R. , Venkataraman A.
Published: April 2003

The role of aqueous alkali solutions as swelling agents of cotton cellulose has been studied by various workers and these reagents have been invariably considered to cause lattice disorder in cellulose. The effect of multiple swelling treatments on the cotton cellulose structure has not been studied hitherto. The present study on cotton demonstrates that is the concentration of the swelling agents and the conditions at the time of treatment which determine the resultant order in the final product. The resultant lattice order so attained is shown to be far in excess of any observed in either native or regenerated celluloses or even their hydrolyzed products, with complete retention of their fibrous form. X‐ray diffraction and electron microscopy data show conclusively that fibrillar “aggregation” or their “dispersion” can be effectively controlled and are the results of the soda cellulose complexes which form upon alkali treatments. The role of water vis‐á‐vis the formation of cellulose II is extensively discussed. Studies on sorption and tensile properties of the treated samples lend support to the phenomenon of fibrillar aggregation in cellulosic fibers.