bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature dependence of relative modulus in filled polymer systems
Authors: Nielsen Lawrence E. , Lewis Thomas B.
Published: April 2003

The temperature dependence of relative modulus observed in filled thermoset, thermoplastic, and polyelectrolyte salt matrices is explained on the basis of induced stresses produced by the differences in the thermal expansion coefficients of the constituent materials. The analysis is based on the assumption that the modulus of the matrix in a filled polymer is less than that of the unfilled polymer. The temperature dependence of relative modulus is expressed as a function of the difference in thermal expansion coefficients, the volume fraction, the relative modulus in the unstressed state, and mechanical properties of the phases. Agreement is good between the analysis and experimental results for three systems: epoxy and glass, polyethylene and wollastonite, and a polyelectrolyte salt with mica and asbestos.
Electron spin resonance study on homogeneous catalysts derived from n‐butyl titanate and triethylaluminum
Authors: Hirai Hidefumi , Hiraki Katsuma , Noguchi Isamu , Makishima Shoji
Published: April 2003

ESR spectra of homogeneous catalyst systems derived from n‐butyl titanate and triethylaluminum at Al/Ti molar ratios of 1.0–10 were observed in toluene solution at several temperatures from −78°C to +25°C. In the whole range of Al/Ti molar ratios, a single signal with a g value of 1.951 was observed at −78°C and was associated with the first reaction intermediate. With increasing temperature, the intensity of the signal decreased gradually, while two series of signals appeared, depending on the Al/Ti molar ratio. At an Al/Ti molar ratio of 1.7, seven kinds of signals with g values of 1.960, 1.946, 1.950, 1.959, 1.980, 1.977, and 1.978, respectively, were observed. On the other hand, four kinds of signals with g values of 1.934, 1.966, 1.952, and 1.979, respectively, were found at Al/Ti molar ratios larger than 3. The structures of the species corresponding to the signals were discussed on the basis of the ESR spectra, the order of their growth and their hyperfine structures being considered. Two series of ESR signal were correlated to two kinds of active species for polymerization of styrene and butadiene, respectively.
Hydrolytic polymerization of caprolactam. I. Hydrolysis—polycondensation kinetics
Authors: Giori C. , Hayes B. T.
Published: April 2003

In a study aimed at process optimization of caprolactam polymerization, particular reference has been paid to the competing role of water in caprolactam hydrolysis and endgroup polycondensation. The dependence of the apparent equilibrium constant for polycondensation on water concentration indicated that there is a strong effect of the medium on the activities of the reacting species which can not be neglected in a kinetic study of the polycondensation reaction. The effect of a variation of the medium was taken into account by using a polycondensation rate constant which included a function of the water present at any given time. With the aid of analog computer curve‐fitting techniques, good agreement with second‐order kinetics was found. The validity of a second‐order mechanism was confirmed in a kinetic study of the chain amide linkage hydrolysis. The hydrolysis of caprolactam follows substantially different kinetics, where the generation of carboxyl groups reduces the activation energy of the reaction, which follows predominantly a third‐order mechanism.
Poly(ester‐acetals) from geometric isomers of methyl azelaaldehydate glycerol acetal
Authors: Lenz Robert W. , Awl R. A. , Miller W. R. , Pryde E. H.
Published: April 2003

The glycerol acetal of methyl azelaaldehydate is an ω‐hydroxy ester that exists as a mixture of dioxolanyl and dioxanyl isomers, each having two geometric isomers. Each of the four isomers was isolated by chromatographic (gas–liquid and column) and fractionating (crystallization and distillation) methods. Structural assignments were made on the basis of nuclear magnetic resonance and infrared spectral data. Linear poly(ester‐acetals) were prepared from each of the cis and trans forms of the dioxanyl isomers and from a mixture of the dioxolanyl geometric isomers. Physical properties of these polymers were correlated with their structures. When prepared with basic condensation catalysts, the polymers retained the geometric configuration and structural identity of the monomer. When prepared with lead acetate, structural rearrangement as well as polycondensation occurred, resulting in an enrichment of the dioxolanyl isomer and simultaneous increase in polymer crystallinity. The enrichment took place at elevated temperatures and also, unexpectedly, at room temperature upon long standing of the polymer. Isomer redistribution at room temperature appears to be antithermodynamic in the reaction sense, yielding a polymer of unusually high dioxolanyl unit content. The driving force for this isomerization may be crystallization of these units by a phenomenon termed a “crystallization‐induced reaction.”
Phosphorus‐containing polyurethans
Authors: Dyer Elizabeth , Dunbar Richard A.
Published: April 2003

Phosphorus‐containing polyurethans of the formula
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were prepared by interfacial polymerization of 1,4‐butanebischloroformate and p‐xylylene‐α, α‐bischloroformate with bis(m‐aminophenyl)alkylphosphine oxides. The polymers had number average molecular weights up to 8600. A test of the stability to alkali of one of the polymers (RCH3, X1,4‐C6H4) showed it to be as resistant as nonphosphorus analogs, and a film of this polymer exhibited self‐extinguishing properties. Thermal degradation of the phosphorus polymers, which began at approximately 230°C, occurred by an initial first‐order process, releasing chiefly carbon dioxide. The energies of activation for the maximum rates of weight loss were 31–37 kcal/mole.
A proposal on the steric course of propagation in the homogeneous cationic polymerization of vinyl and related monomers
Authors: Kunitake Toyoki , Aso Chuji
Published: April 2003

A stereochemical scheme of propagation was proposed for polymerizations of vinyl and related monomers by Friedel‐Crafts catalysts. For the cationic propagation proceeding via the simple carbonium ion pair, the following two factors were considered to be of primary importance in determining the steric course of propagation: (1) the conformation of the last two units of the propagating polymer segment and the direction of approach of the incoming monomer; (2) the tightness of the growing ion pair. Thus, the front‐side (less hindered site) attack to the carbonium ion gives rise to a syndiotactic placement and the back‐side attack an isotactic placement. The present model can satisfactorily explain the effects of substituents, catalysts, polymerization media, and polymerization temperature on the steric structure of polymers in cationic polymerization of vinyl ethers. Extension of the scheme to polymerization of the β‐substituted vinyl ethers in nonpolar solvents predicts formation of the diisotactic structures consistent with the experimental result. The influences of the polymerization condition on the steric structure of polymer were studied for cationic polymerizations of α‐methylstyrene at low temperatures. Highly syndiotactic polymers were obtained for homogeneous reactions in toluene‐rich media. The isotactic unit increased by increasing the content of methylcyclohexane in the solvent mixture. The effect of catalysts, though insignificant in toluene‐rich media, was clearly noted in methylcyclohexane‐rich media, less active catalysts (e.g., SnCl4) yielding higher amounts of the isotactic unit than more active catalysts (e.g., AlCl3). These results can be readily accommodated in the present model.
Copolymerization with depropagation. III. Composition and sequence distribution from probability considerations
Authors: Howell John A. , Izu Masatsugu , O'Driscoll Kenneth F.
Published: April 2003

Elementary probability considerations have been used to derive completely general equations which describe both the sequence distributions and compositions to be expected for copolymerizations which follow kinetic models having complete reversibility for all propagation steps. It is shown that previously derived composition equations for both reversible and irreversible systems are special cases of the general equations derived herein.
Polymerization of vinylcyclopropanes. V. Radical copolymerization of 1, 1‐dichloro‐2‐vinylcyclopropane with monosubstituted ethylenes
Authors: Takahashi Takako
Published: April 2003

A peculiar copolymer composition equation applicable to the radical copolymerization of 1,1‐dichloro‐2‐vinylcyclopropane with monosubstituted ethylenes was developed. The theory was applied to such ethylenes as methyl acrylate, methyl methacrylate, and styrene. The reactivity ratio parameters which give the best fit to the experimental data were determined.
Endgroup analysis of isolated poly(methyl methacrylate) from graft copolymers of wool
Authors: Arai Kozo , Komine Shigeo , Negishi Michiharu
Published: April 2003

In order to elucidate the termination mechanism in the graft copolymerization of methyl methacrylate to unreduced and reduced wool fibers, graft copolymers were prepared by means of the LiBr–K2S2O8 redox sytem without homopolymer or with K2S2O8 only with homopolymer at 30°C. The graft polymers (PMMA) were isolated almost completely from the wool trunk by an HCI‐digestion method, leaving a few amino acid residues on the end of the graft polymers. Dinitrophenylation of the isolated polymer was carried out by various methods. The spectral features were almost the same as for dinitrophenylated amino acids of the usual type such as valine, leucine, and methionine, with a maximum in ultraviolet light at 340–345 mμ. From colorimetric analysis of the number of dinitrophenylated amino acid endgroups and the measurement of the average molecular weight of the isolated polymers, the number of amino acid endgroups linked to the graft polymers was calculated to be about one and two per polymer chain in reduced and unreduced wool, respectively, independent of the reaction system, graft‐on, and molecular weight of graft polymers. From these facts, it was suggested that the most of isolated polymers are the truly grafted polymers. Also, the termination reactions have been explained as follows. In the unreduced wool, the restriction of mobility of the radical end might be expected, for the confinement of growing chains in wool fibers. This would be favorable to termination by recombination rather than by the disproportionation, since the former has a lower activation energy than the latter. Thus, the formation of intra‐ or intermolecular crosslinks might be considered between polypeptide chains. On the other hand, in the reduced wool, the mobility of graft polymers might be considered to be greater than that of unreduced wool because of its open structure. Therefore, termination would be principally by disproportionation between graft polymer radicals.
Production of organometallic polymers by the interfacial technique. V. Partial mechanistic study of the production of poly[alkyl(aryl)oxysilances]
Authors: Carraher Charles E. , Klimiuk George H.
Published: April 2003

A modified interfacial polymerization system capable of producing poly[alkyl(aryl)oxysilanes] consisting of a dichlorosilane in an organic solvent as octane and a diol in 2,5‐hexanedione is presented. It is believed that polymerization occurs near the interface in the dione phase. The products are low to intermediate in molecular weight. As the nature of silane is varied, the rate of polymer formation varies, the silane with the most electron‐deficient silicon giving the greatest rate. Molecular weight is constant as diol is changed but varies when the silane is changed so that the silane with the most bulky substitutes will give polymer with the lowest molecular weight. The results are consistant with a SN2 type reaction mechanism.
Structure of branching in PVC
Authors: Caraculacu A. A. , Bezdadea E. C. , Istrate Gabriela
Published: April 2003

A new macromolecular model for branched PVC was synthesized by copolymerization of vinyl chloride with 2,4‐dichloropentene‐1. The composition and the properties of this new copolymer were studied and the phenolysis reaction to determine the content of chlorine atom bound to the tertiary carbon atom (ClT) was carried out. The presence of a longer branch, of PVC type, does not impede the reaction. It is concluded that there are no chlorine atoms at the branching sites in PVC.
Copolymers of vinyl chloride with the vinyl esters and acrylates of low molecular weight polyesters of hydroxyacids
Authors: Chow Roberta C. L. , Marvel C. S. , Magne Frank C.
Published: April 2003

Vinyl esters and acrylates of polyesters derived from C10−C18 hydroxyacids have been synthesized and copolymerized with vinyl chloride with the hope of achieving an internally plasticized poly(vinyl chloride). Copolymers containing 10–30% polyester are film‐forming materials, and the films cast from THF solutions are generally flexible. A number of these vinyl chloride copolymers with polyesters at approximately 15 and 25% level have been tested for various properties. The internal plasticization is not extensive.
Metal coordination polymers. III. Molecular weights of beryllium phosphinate polymers in chloroform
Authors: Fetter N. R. , Grieve C. M.
Published: April 2003

Vapor‐phase osmometric molecular weight measurements on beryllium di‐n‐butyl‐phosphinate are in general agreement with the results obtained in chloroform by Ripamonti and co‐workers. The degree of polymer association in anhydrous chloroform is approximately twice that obtained in reagent‐grade chloroform, and the values obtained in both types of chloroform are higher than those obtained by Ripamonti. Membrane osmometric molecular weight measurements on beryllium 4‐biphenyl (phenyl)‐phosphinate in chloroform indicate a reversible degradation exists between a number‐average molecular weight of 170 000 and 30 000, with the value dependent upon the polymer concentration. Treatment of chloroform solutions of this polymer with ammonia prevents reassembly of the polymer from 30 000 to higher values. To explain this and other solution properties of this polymer, a structure is proposed which involves endgroup hydrogen bonding of phosphinate‐bonded aggregates containing approximately 50 monomer units (Mn = 30 000). Under certain conditions, the hydrogen‐bonded aggregates may contain up to 300 monomer units, but in polar solvents such as water or chloroform they are rapidly degraded.
Poly(4,4′‐dipiperidyl)amides
Authors: Preston J. , Smith R. W.
Published: April 2003

Polyamides from 4,4′‐dipiperidyl, 1,2‐ethylene‐, and 1,3‐propylene‐ bridged dipiperidyls were prepared via solution and interfacial polycondensation techniques. In sharp contrast to the polyamides from N,N′‐alkyl‐substituted alkylene diamines and aromatic diacids, the polyamides from 4,4′‐dipiperidyls are high‐melting (up to 455°C) and alcohol‐insoluble. Tough films were cast from formic acid solutions of the polymers; fiber of good physical properties was prepared from a formic acid solution of the polyterephthalamide of 1,2‐di(4‐piperidyl)ethane.
Photocycloaddition polymerization. I. Preparation and characterization of poly‐N,N′‐polymethylenebisdichloromaleimides
Authors: De Schryver F. C. , Feast W. J. , Smets G.
Published: April 2003

The benzophenone‐sensitized solution‐phase photocycloaddition polymerization of N,N′‐polymethylenebisdichloromaleimides has been investigated. It is shown that a polymer can be obtained by repeated 2π + 2π photocycloaddition process. The intrinsic viscosity of the products varies from 0.1 to 0.6 when the link between the two maleimide moieties contains more than six and simultaneously an uneven number of methylene units. The polymeric materials form transparent, flexible, noninflammable films and decompose at 310°C.
Synthesis and preliminary evaluation of ordered aliphatic poly(benzoxazole amides),
Authors: De Winter Walter , Stein Ralph , Uwents Henri , Masquelier Camille
Published: April 2003

Slightly modified conventional techniques were successfully applied to prepare aliphatic benzoxazolediamines and the corresponding high molecular weight polyamides, which could be spun into excellent fibers. Compared to regular aliphatic polyamides, these products showed higher transition temperatures, improved thermal and light stability, and increased affinity for acid dyes. In addition—quite unexpectedly—these fibers were highly crystalline and oriented after drawing at elevated temperatures.
N,N′‐(disubstitutedmethylene)bisacrylamides: Preparation and polymerization
Authors: Murfin Donald L. , Hayashi Katsumi , Miller Leonard E.
Published: April 2003

Preparative methods for the previously unreported N,N′‐(disubstitutedmethylene)‐bisacrylamides are presented. The solubility and thermal stability of these new bisamides are compared to the well known N,N′‐methylenebisacrylamide. N,N′‐Isopropyl‐idenebisacrylamide, one of these new compounds, readily copolymerizes with a variety of vinyl monomers. It forms high molecular weight copolymers by the conjugate polyaddition of alkanedithiols or piperazine.
Equimolecular binary polydines. V. Equibinary poly(cis‐1,4–trans‐1,4)butadiene from bis(π‐allyl nickel trifluoroacetate)
Authors: Marechal J. C. , Dawans F. , Teyssie Ph.
Published: April 2003

The preparation of equibinary poly(cis‐1,4–trans‐1,4)butadiene was investigated in the presence of bis(π‐allyl nickel trifluoroacetate) modified with suitable additional ligands. The behavior of the catalytic species in the polymerization reaction as well as the specific basic properties of the equibinary polybutadiene produced support obviously a regular distribution of the cis and trans isomers in the polymer chains.
N‐vinylthiopyrrolidinone
Authors: Coleman L. E. , Bork J. F.
Published: April 2003

The polymerization reactivity of N‐vinylthipyrrolidinone is described. This monomer readily homopolymerizes and forms copolymers with a wide variety of vinyl monomers. Reactivity ratios in the copolymerization of N‐vinylthiopyrrolidinone with styrene and methyl methacrylate are reported and the Alfrey‐Price Q and e values calculated. These results indicate the high copolymerization reactivity of this monomer in comparison with the oxo‐analog, N‐vinylpyrrolidinone. Some of the results are in conflict with previously reported data.
Irradiation of terephthalophenone in isopropyl alcohol
Authors: Pearson D. E. , Thiemann P. D.
Published: April 2003

Irradiation of terephthalophenone in isopropyl alcohol gave a bright yellow‐colored intermediate which decayed rather rapidly. The products were complex and depended upon the mode of irradiation. They ranged from a mixed polymer I to a dimer II. I consisted of about 5 terephthalophenone units capped with hydrogen or isopropyl alcohol radicals or terminated by cyclization. II, the dimer, was capped by hydrogen atoms.
Reversible crosslinking in cellulose. III. Factors controlling the oxidation behavior of mercapto groups in cotton derivatives
Authors: Sakamoto Munenori , Takeda Junichi , Yamada Yoshio , Tonami Hiroaki
Published: April 2003

The oxidation behavior of mercaptocellulose prepared from tosylated cotton and of cellulose β‐mercaptoethylaminocarboxylate (RDTC), which was prepared by reduction of a cotton derivative made by the reaction with bis‐β‐isocyanatoethyl disulfide, was studied, and the factors controlling the oxidation behaviors of solid polymeric mercaptans were discussed. RDTC was converted quantitatively to the corresponding disulfide by oxidation under mild conditions. Repeated oxidation–reduction cycles were applied to RDTC to demonstrate complete reversibility of disulfide crosslinking. On the other hand, only a portion of the mercaptan in mercaptocellulose could form disulfide by oxidation. It is considered that the mobility of the mercapto groups necessary for the oxidation coupling is restricted because they are attached directly to rigid cellulose chains. The oxidation of RDTC with air in alkaline medium was studied kinetically. It was found that the oxidation of the mercaptan in paired placement in the cellulose matrix proceeded more than ten times faster than that of the randomly placed mercaptan.
Polymerization of complexed monomers. I. Alternating copolymers from cyclopentene and complexed polar monomers
Authors: Hecht Jeffrey K.
Published: April 2003

Alternating equimolar copolymers of cyclopentene with acrylonitrile and methyl acrylate were prepared in the presence of ethylaluminum sesquichloride. Varying conditions of monomer ratio, temperature, light, and reaction time were studied. The structures of the polymers and mechanistic implications are discussed.
Telomerization by free‐radical mercaptan chain transfer. IV. Effects of structure, solvent and initiator variation on the stereochemistry of acrylate ester–mercaptan telomers
Authors: Scott George P. , Elghoul Abdelaziz M. R.
Published: April 2003

Chain‐transfer constants for radicals one to five units in length were determined for the methyl acrylate–isopropanethiol system. Effects of varying ester alkyl group, mercaptan solvent and initiator on three‐unit diastereomer ratio were also investigated. It was found that the proportion of syndiotactic isomer increased as the size of either the ester alkyl group or the mercaptan increased, the latter result being equivalent to a penultimate effect. Polar solvents, on the other hand, favored the formation of the isotactic form. This effect was observed in the free‐radical telomerization and to an even greater degree in the base‐initiated anionic telomerization. Possible reasons for solvent effects are discussed.
Cyclocopolymerization of p‐chlorostyrene with 4‐vinylcyclohexene
Authors: Kawai Wasaburo , Katsuta Shigeru
Published: April 2003

4‐Vinylcyclohexene was polymerized by triethyl‐aluminum–titanium tetrachloride catalyst (mole ratio 5.4:1). Copolymerization of 4‐vinylcyclohexene with p‐chlorostyrene by the same catalyst was also carried out. For these polymerization results, the Roovers‐Smets equation was applied and the reactivity ratio parameters, Kc, Kc′, r2 and r3 were determined as follows: Kc = Kc/k11 = 9.1; Kc′ = kc/k12 ∼ ∞; r2 = k22/k21 = 1.45; r3 = k31/k32 ∼ 0, where subscripts 1, 2 and 3 indicate 4‐vinylcyclohexene, p‐chlorostyrene, and cyclized polymer anion, respectively.
Radiation‐induced copolymerization of tetrafluoroethylene and 3,3,4,4,5,5,5‐heptafluoropentene‐1 under pressure
Authors: Brown Daniel W. , Lowry Robert E. , Wall Leo A.
Published: April 2003

An investigation was made of the γ‐ray‐induced copolymerization of tetrafluoroethylene and 3,3,4,4,5,5,5‐heptafluoropentene‐1. At 22°C at 5000 and 10 000 atm the polymerization rate changes little between 0 and 75 mole‐% tetrafluoroethylene. Above 90 mole‐% the rate increases greatly. Molecular weights vary with composition in a fashion similar to the variation of the rates. Crystallization occurs in the bulk pentene at 13 500 atm at 24°C. The polymerization rate is very low in the solid state. Under some conditions polymerization continues long after irradiation is ended. Both reactivity ratios favor the pentene. Several copolymer properties were studied. The polymers are amorphous and soluble in perfluoro ethers, perfluoro alkanes, and perfluoroaromatics if they contain less than 80% tetrafluoroethylene. The glass temperatures of the amorphous polymers decrease and the thermal and radiation stability increases as the tetrafluoroethylene content increases.
Polymerization studies on allylic compounds. IV. Methallylic compounds
Authors: Harville R. L. , Reed Samuel F.
Published: April 2003

The free‐radical polymerization of a series of 2‐methyl‐3‐substituted propenes was investigated. These compounds were found to homopolymerize with difficulty to give low molecular weight polymers. Their effect upon the polymerization of methyl methacrylate and styrene was investigated by rate and viscosity measurements. Copolymerizations occurred with a retarding action attributed to pronounced chain transfer reactions.
Alkyl chain branching in ethylene–vinyl acetate copolymer
Authors: Saito Mitsutaka , Tada Hideo , Kosaka Yujiro
Published: April 2003

Ethylene–vinyl acetate copolymers contain two kinds of side chains: acetoxy branches originating from incorporated vinyl acetate and alkyl branches. The alkyl branching was determined by infrared analysis after converting the ethylene–vinyl acetate copolymer to a hydrocarbon polymer by three steps: hydrolysis, iodation with hydriodic acid containing red phosphorus, and reductive hydrogenation with lithium aluminum hydride. It was found that physical properties such as stiffness were dependent both on the degree of alkyl chain branching and on vinyl acetate content.
Polymerization of acrylamide initiated with pinacol–ceric ion redox system
Authors: Narita Hiroshi , Okimoto Tomoyuki , Machida Seishi
Published: April 2003

Polymerization of acrylamide initiated with a pinacol–ceric ion redox system was investigated. The polymer obtained was found to contain one cerium atom in a polymer molecule. It was considered that the cerium atom was introduced into the polymer molecule by the termination reaction as there is no cerium atom in the initiating radical in the present system. A similar termination reaction was attained by ferric ion but not by cerous ion. The metal ion was considered to terminate the polymerization to form a stable polymer. Some considerations on the structure of the reaction product relating to the polymerization mechanism were discussed.
Stereospecific polymerization of isobutyl vinyl ether by AlR3–VCln catalysts. I. Influence of preparative conditions of the catalysts
Authors: Joh Yasushi , Yuki Heimei , Murahashi Shunsuke
Published: April 2003

The polymerization of isobutyl vinyl ether by the VCln–AIR3 system was carefully studied. The vanadium components were prepared by the reaction between VCl4 and AlEt3 or n‐BuLi as a reducing agent. VCl3·LiCl and VCl2·2LiCl are the effective catalysts for the stereospecific polymerization of isobutyl vinyl ether. When VCl3·LiCl is combined with AlR3, a new catalytic system is formed. The effect of the preparative conditions of the various vanadium component in the AlR3–VCln system shows that the effective vanadium component is trivalent. In the polymerization by VCl3·LiCl–Al (i‐Bu)3 system, a change of the polymerization mechanism may occur at Al(i‐Bu)3/VCl3·LiCl ratio at around 5. When the ratio is lower than 5, a cationic polymerization by VCl3·LiCl takes place predominantly, while at ratios higher than 5, it is suggested that the polymerization proceeds by means of a VCl3·LiClA–Al(i‐Bu)3 complex by a coordinated anionic mechanism. The polymers obtained by these catalysts are highly crystalline. Styrene was also polymerized by using the same catalysts. VCl3·LiCl and VCl3·LiCl–THF complex yielded amorphous polymer by cationic polymerization. When VCl3·LiCl was combined with 6 mole‐eq of Al(i‐Bu)3, the resulting polystyrene was highly crystalline and had an isotactic structure, while the VCl2·2LiCl–Al(i‐Bu)3 (1:6) system yielded traces of polymer of extremely low stereoregularity. The results indicate that the effective vanadium component at Al/V ≧ 6 is trivalent and that the mechanism is a coordinated anionic one.
Salt‐catalyzed reaction between styrene oxide and silk fibroin
Authors: Shiozaki Hideki , Tanaka Yoshio
Published: April 2003

The addition reaction of styrene oxide (StO) with silk fibroin was studied in the presence of various salts in different solvents at 45–75°C. Some water was required to make StO react with silk padded with various salt solutions. The reaction rate increased with the salt concentration and reached a maximum value at a certain concentration of the salt. Padding with solutions of thiosulfate, cyanide, thiocyanate, bicarbonate, or carbonate resulted in high add‐ons (to 65 mole/105 g) and low solubilities in HCl and NaOH aqueous solutions. The weight gains increased with the epoxide concentration and reached a constant value at a certain concentration of StO solution in ethanol, while they decreased slightly with epoxide concentration over 10% of StO solution in n‐hexane. Histidine, lysine, arginine, tyrosine, and aspartic and glutamic acids were found to react. The reaction rate decreased with increasing solubility parameter of the solvent used, reached a minimum value about at 10 or at the solubility parameter of the epoxide, and then increased with the parameter. The StO–silk reaction may depend on the distribution of StO between aqueous salt and an organic solvent phases, and on the swelling of silk fiber in different aqueous salt solutions or in various organic solvents. The mechanism for this epoxide‐silk reaction and the reactivity difference between StO and phenyl glycidyl ether toward silk fibroin are discussed in the light of the observed phenomena.
Isocyanate–catalyst and hydroxyl–catalyst complex formation
Authors: Reegen S. L. , Frisch K. C.
Published: April 2003

As part of an investigation for evidence of isocyanate–catalyst and alcohol–catalyst complex formations, determinations of molecular weights were made by means of the freezing point depression of benzene solutions. Mixtures of 1‐methoxy‐2‐propanol and dibutyltin dilaurate and mixtures of 1‐methoxy‐2‐propanol and triethylamine both gave strong evidence of the formation of complexes. Complex formations were also detected when the alcohol was replaced by phenyl isocyanate. Significantly larger concentrations of the catalyst were involved in isocyanate complexes than were shown to be the case with the alcohol complexes. These results appear to be experimental evidence for the previously proposed ternary complex as an intermediate in the metal‐catalyzed formation of urethanes.
Catalytic action of metallic salts in autoxidation and polymerization. IV. Polymerization of methyl methacrylate by cobalt(II) or (III) acetylacetonate–tert‐butyl hydroperoxide or dioxane hydroperoxide
Authors: Osawa Zenjiro , Shibamiya Tetsuaki , Kawamata Toshio
Published: April 2003

Polymerization of methyl methacrylate was carried out by four initiating systems, namely, cobalt(II) or (III) acetylacetonate–tert‐butyl hydroperoxide (t‐Bu HPO) or dioxane hydroperoxide (DOX HPO). Dioxane hydroperoxide systems were much more effective for the polymerization of methyl methacrylate than tert‐butyl hydroperoxide systems, and cobaltous acetylacetonate was more effective than cobaltic acetylacetonate in both hydroperoxides. The initiating activity order and activation energy for the polymerization were as follows: Co(acac)2–DOX HPO (Ea‐9.3 kcal/mole) > Co (acac)3–DOX HPO (Ea = 12.4 kcal/mole) > Co(acac)2–t‐Bu HPO (Ea = 15.1 kcal/mole) > Co(acac)3–t‐Bu HPO (Ea‐18.5 kcal/mole). The effects of conversion and hydroperoxide concentration on the degree of polymerization were also examined. The kinetic data on the decomposition of hydroperoxides catalyzed by cobalt salts gave a little information for the interpretation of polymerization process.
Radiation‐induced polymerization of isobutylene oxide
Authors: Bauer R. S. , Spooncer W. W.
Published: April 2003

In the absence of oxygen, liquid isobutylene oxide is polymerized by high energy radiation. The resultant polyethers may possess the same gross structures as those prepared by Lewis acid catalysis:
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The reaction is characterized by (1) a small, apparent activation energy (2.7 kcal/mole), (2) a polymerization rate proportional to the first power of the dose rate, (3) inhibition by Lewis bases, and (4) moderate inhibition by free‐radical scavengers. The molecular weights of the polymers increase with decreasing temperatures of polymerizations. These results will be discussed in terms of a cationic propagation mechanism.
Studies on the polymerization of ethyl acrylate. III. Effect of temperature on the solvent‐transfer reaction
Authors: Raghuram P. V. T. , Nandi U. S.
Published: April 2003

The effect of temperature on transfer constants for different solvents in the polymerization of ethyl acrylate was observed. Activation energy differences (EtrS − Ep) and frequency factors were computed. It is observed that high frequency factors are associated with high activation energies. Values of EtrS were calculated by an approximate method and were compared with the available data on methyl methacrylate, isobutyl methacrylate, and styrene.
Structure–property relationships of ring‐containing nylon 66 copolyamides
Authors: Ridgway James S.
Published: April 2003

Several series of nylon 66 copolyamides were prepared with up to 30 mole‐% substitution of ringed comonomers of the type X‐(CH2)n‐R‐(CH2)n‐X, wheren= 0, 1, or 2; X = −NH2or CO2H; and R = phenylene, cyclohexylene, or naphthyle. The ring structure was correlated with glass transition temperature and melting point. The important features of ring structure fall into the following categories: ring isomerism, aromaticity, diamine vs. diacid substitution, chain length, and ring substitution. Proper “fit” (isomorphism) of the comonomer into the nylon 66 chain appears to be the main criterion for ringed copolymers of highTgand high melting point.
Reactivity ratios and copolymerization parameters for copolymers incorporating n‐octadecyl acrylate and N‐n‐octadecylacrylamide
Authors: Jordan Edmund F. , Bennett Richard , Shuman Andrea C. , Wrigley A. N.
Published: April 2003

Monomer reactivity ratios and copolymerization parameters were determined for n‐octadecyl acrylate and N‐n‐octadecylacrylamide with several monomers not previously reported. Values of Q and e for the long‐chain acrylate now agreed more closely than before with the average of values for the lower acrylate homologs. The average polarity parameter for N‐n‐octadecylacrylamide still showed more electron withdrawal from the double bond (e = 0.42) than was expressed by the average literature value (e = −0.10) for N‐n‐octylacrylamide. Because penultimate effects were absent in this work, the reason for the discrepancy seems to reside in the copolymer analysis. Reactivity ratios for oleyl and octadecyl acrylate with methyl methacrylate were similar. Coefficients for the relation between overall rates of copolymerization and composition were obtained on some systems by curve fitting with a computer. They generally showed a slight minimum.
Polymers containing anthraquinone units: Polymers from 1,2,5,6‐tetraaminoanthraquinone
Authors: Bracke William , Marvel C. S.
Published: April 2003

A preparation for 1,2,5,6‐tetraaminoanthraquinone was worked out. The reactivity of this compound in nucleophilie substitutions and nucleophilic additions was studied. Polymers were made by condensation with pyromellitic anhydride, terephthaloyl chloride, and isophthaloyl chloride. The synthesis and properties of the corresponding model compounds are also reported. After reduction with sodium dithionite, the polymers are soluble in dimethylformamide–water mixtures.
Benzimidazole, benzothiazole, and benzoxazole polymers with anthracene recurring units
Authors: Kokelenberg Hendrik , Marvel C. S.
Published: April 2003

In an attempt to prepare polymers which might be oxidized to compounds soluble in alkali diphenyl 1,5‐anthracenedicarboxylate was reacted with diaminobenzidine, dimercaptobenzidine, and diaminobiphenol in the melt and with dimercaptobenzidine dihydrochloride in polyphosphoric acid. Compounds of high molecular weight were obtained and their thermal and oxidative stability evaluated. Model compounds were prepared and their ultraviolet spectra compared with those of the polymers. Oxidation with nitric acid or chromium trioxide yielded some anthraquinone derivatives, but side reactions prevented the formation of useful products.
Depolymerization of polysulfide polymers by dithionite ions
Authors: Rekalic Vladimir J. , Radosavljević Slobodan D. , Tenc‐Popović Mirjana E.
Published: April 2003

The action of sodium dithionite, Na2S2O4 on desulfurized tetrasulfide polymers leads to their depolymerization. Our studies showed that successful depolymerization can be initiated only in an alkali medium when 1.9–3.2 mole of sodium hydroxide per mole of dithionite is used, and that this leads to the cleavage of disulfide bonds and the formation of polymers of lower molecular weight with SH end groups. Liquid polymers of 1000–5000 molecular weight are obtained when 0.388–0.155 mole sodium dithionite per segment of polymer is used for depolymerization in the presence of the above‐mentioned quantity of sodium hydroxide per mole of dithionite. The depolymerization of poly‐sulfide polymers with sodium dithionite in the presence of sodium hydroxide was followed by determination of the molecular weight and sulfur content of the polymer and analysis of the mother liquid.
Participation of an excited monomer in the propagation reaction of the γ‐ray induced polymerization of ethylene
Authors: Hagiwara Miyuki , Okamoto Hidemasa , Kagiya Tsutomu
Published: April 2003

In the polymerization of ethylene, the reactivity of the growing radical produced by γ‐radiation was compared with that of the radical from 2,2′‐azobisisobutyronitrile. The radicals produced in the polymerization at around room temperature were long‐lived irrespective of the method of initiation. However, it was found that the radical produced by γ‐radiation became unreactive to ethylene when the reaction system was not exposed to γ‐rays. Irradiation with γ‐rays or ultraviolet light in a region below about 3900 Å was required for its chain growth. On the other hand, the radical from AIBN was always reactive, and the reactivity was little changed by γ‐radiation or by the presence of a trace amount of radiolysis products of ethylene. In explaining of these characteristic differences between the nature of these radicals produced by two different methods of initiation, some other information on their reactivity was reviewed, and the participation of an excited ethylene in a dimer form was proposed, as for the propagation reaction of the γ‐ray‐induced polymerization.
Electroinitiated cationic polymerization of styrene
Authors: Funt B. L. , Blain T. J.
Published: April 2003

A constant controlled current was passed through a solution of styrene in methylene chloride containing a tetraalkylammonium salt as supporting electrolyte. Reproducible rates of polymerization were initiated by the electrochemical techniques employed and the kinetics of the reaction were investigated. Sigmoidal curves of conversion versus time were observed. A kinetic relationship of the form In ([M0]/[M]) = ½ Kt2 was derived on the basis of simple assumptions regarding the mechanism and fitted the data accurately. The rate constants obtained were compared to others reported, and the influences of ion association on the values of the rate constants obtained are discussed. The reactions were decreased in rate by a reversal of polarity of the electrodes. However, the stoichiometry of the production of active centers and of their destruction was not ideal, in that each electron did not result in the initiation of a polymer chain.
Mechanism of charge–transfer polymerization. II. Propagation mechanism of the polymerization of N‐vinylcarbazole with organic electron acceptors
Authors: Fujimatsu Masaaki , Natsuume Tadao , Hirata Hirotaka , Shirota Yasuhiko , Kusabayashi Shigekazu , Mikawa Hiroshi
Published: April 2003

Copolymerizations of N‐vinylcarbazole with both isobutyl vinyl ether and N‐vinyl‐pyrrolidone initiated by some organic electron acceptors have been investigated for the purpose of elucidating the propagation mechanism in the charge‐transfer polymerization. Copolymerizations of the same system catalyzed by authentic cationic catalysts have also been made for comparison. The results indicate that the propagation mechanism of the charge‐transfer polymerization studied is catio ie.
Copolymerization of styrene and butadiene in emulsion. I. Composition of the latex particles
Authors: Burnett G. M. , Cameron G. G. , Thorat P. L.
Published: April 2003

The composition of the latex particles during intervals I and II of the emulsion polymerization of styrene and butadiene (initial weight ratio 71 parts butadiene:29 parts styrene) has been determined at 5, 15, and 25°C. The monomer content of the latex particles diminishes linearly with conversion. The composition ratio (weight styrene: weight butadiene inside the particles divided by weight styrene:weight butadiene in the binary phase) also decreases with conversion, the decrease being particularly marked as the end of interval II is approached. It is shown that the assumptions embodied in the theory of Medvedev et al. are incorrect. The results are compared with the recent theories of Gardon.
Isomorphic interactions of ethylenic polymers and paraffin wax
Authors: Tordella J. P. , Dunion P. F.
Published: April 2003

The high degree of flexibility of blends containing minor amounts of partly crystalline copolymers of ethylene and vinyl acetate in paraffin wax seems to be a manifestation of some type of interaction. Low‐angle x‐ray diffraction of such blends showed a new long spacing intermediate in length between the polymer long spacing and the c axis length of the wax unit cell. This new long spacing appears to be a consequence of isomorphism involving cocrystallization of polymeric ethylene sequences and wax molecules. A lesser type of isomorphic interaction, epitaxy, occurs in polyethylene–wax blends: wax overgrows crystals of already crystallized polyethylene in the same orientation without a change in its c axial dimension.
Effect of molecular structure on polyethylene melt rheology. II. Shear‐dependent viscosity
Authors: Mendelson R. A. , Bowles W. A. , Finger F. L.
Published: April 2003

The investigation of the effect of molecular structural variables on the melt viscosity of polyethylene was extended to the shear dependent region by application of a reduced variables treatment following, in a formal sense, that of Bueche. Viscosity–shear rate data were obtained for a series of experimentally polymerized linear polyethylene samples having a range of molecular weights and molecular weight distributions as characterized primarily by gel permeation chromatography. These data could be superimposed on a single reduced variables flow curve using parameters which were a function only of temperature, limiting Newtonian viscosity, M̄w, and M̄w/M̄n. The same treatment was successfully applied also to branched (low‐density) fraction data discussed in a previous paper, with additional correction for long‐chain branching. However, different reduced variables curves were obtained for the branched and linear cases.
Melting behavior of linear polyethylene crystallized by solution stirring
Authors: Rijke A. M. , Mandelkern L.
Published: April 2003

Calorimetric and dilatometric studies have been made of the fusion process of linear polyethylene crystals precipitated by high speed stirring from solution. It is shown that long‐time annealing at elevated temperatures alleviates the superheating observed when rapid heating rates are employed. By the annealing procedures that have been adopted, a small but demonstrable fraction of high melting material can be produced whose melting temperature depends on the crystallization temperature. For crystallization at 105°C, followed by annealing at 142°C, a melting temperature of 146.0 ± 0.5°C is observed. The dissolution temperature in xylene, determined for the same sample, is consistent with the high melting temperature observed for the pure polymer. It is recognized that a state of high axial orientation need not necessarily be identified with extended chain crystals. Consequently, the increased melting temperature can result from either an increase in the crystallite size or a reduced interfacial free energy relative to crystallites produced by the more conventional mode of crystallization.
Tensile properties and equilibrium swelling of plasticized amorphous polyurethane rubbers
Authors: Oberth Adolf E. , Bruenner Rolf S.
Published: April 2003

Incorporation of plasticizers or other inert, liquid diluents causes a profound weakening of rubbers. The modulus of elasticity and tensile strength decrease approximately with the square of the gel fraction v0 of rubber which was present at the time of formation of the three‐dimensional network. Equlibrium swelling of plasticized rubbers is well represented by v2m = kv0, where v2m is the volume fraction of rubber network in the swollen state, at equlibrium, and k a constant equal to v2m for the unplasticized rubber. This swelling law is independent of the way in which v0 is obtained; inert liquid diluents, comprising molecularly dispersed compounds, as well as suspensions of insoluble liquids, gases, and chemically inert, solid fillers yield the same relation. Further, it is independent of the chemical nature of solvent and rubber. It appears that also the mechanical properties of foams, liquid‐filled foams, and plasticized elastomers containing the same volume fraction of network rubber are very similar.
Contribution à l'étude de l'ionisation des films insolubles de polyélectrolytes stéréoréguliers
Authors: Jaffé J. , Ruysschaert J. M. , Bricman G.
Published: April 2003

The surface potentials of monolayers of poly(methacrylic acid) (PMA) have been studied as a function of the pH of the subsolution. The influence of the macromolecular configuration on the properties of the ionizable groups was more particularly investigated. Orientation of molecules in the monolayer may be imposed by the stereoregularity of PMA (isotactic, atactic) and by the nature of the interface (air–water, cyclohexane–water). The results are analyzed in terms of theories of the ionic double layer (Gouy model, Donnan equilibrium) which permit the determination of the degree of ionization α of the film. The value of α gives indications about the orientation of specific groups of the macromolecular chain, i.e., of the ionized monomer units. Indeed, at the air–water interface, the film of isotactic PMA is more acid than that of the atactic sample, and at the cyclohexane–water interface, the degree of ionization is greater than at the air–water interface. These properties are the consequence of a modification of orientation of the hydrophilic groups with respect to the aqueous phase as a function of the stereoregularity of the sample and the nature of the interface. The variation of α with the pH of the substrate phase may be used to calculate an intrinsic dissociation constant Ks° of the molecules in the film. The value of Ks° is not modified by spreading conditions and remains very similar to that obtained in solution.
Relation of initial supermolecular organization in crystalline polymer systems to the organization produced by stretching
Authors: Baranov V. G. , Gasparyan K. A.
Published: April 2003

An investigation of small‐angle scattering produced by polarized light from stretched and annealed polymer systems containing spherulites yields information on the supermolecular transitions that occur during such treatment. A series of semicrystalline polymer systems (films, fibers) show that stretching leads to deformation of spherulites and subsequent transformation to an orientational supermolecular order. The size of the single element C2 of the supermolecular order in the direction of stretching, determined from the distance between the layer lines of the scattering pattern, is related to the diameter D0 of the initial spherulites by the relation C2 = KD0λs, where λ, is the draw ratio of the macrosystem and K is a parameter determining the deformability of the spherulites. For polyethylene at room temperature K is unity and for polychloroprene it is 1.2. Changes of C2 after annealing and restretching of the systems also obey this ratio.