bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonclassical urea oligomers. I. Selective reactivity of 1‐(N‐substituted‐carbamyl)aziridine for ring‐transformation reactions and ring‐opening polymerization
Authors: Araki Takeo , Nogami Fumio , Tsukube Hiroshi , Nagata Koichi , Iyoshi Shuso 
Published: April 2003

AbstractThe reaction course of 1‐(N‐phenyl‐carbamyl)aziridine with NaI was found to be highly sensitive to the nature of solvent used; e.g., acetone preferentially gives 1‐phenyl‐2‐imidazolidinone, whereas dimethylformamide (DMF) gives 2‐anilino‐2‐oxazoline. Nuclear magnetic resonance (NMR) study of the solvent effect revealed the relation between the site in the aziridine compound, with which the solvents interact, and the reaction products. From the results obtained by these ring‐transformation studies, the use of diethyl sulfate, which is expected to solvate simultaneously at the carbonyl oxygen and the carbamyl–nitrogen atoms, resulted in polymerization of the monomer selectively to the oligomer of type—[CH2CH2N(CONHPh)]n—. The diethyl sulfate was shown to play dual roles as a solvating reagent and an initiator. The oligomer obtained includes relatively definite amount (one molecule per ca. four monomer units) of diethyl sulfate in the “washed” state. The absorbed diethyl sulfate can be removed by treating with aqueous NaOH solution or Amberlite‐400 column elution without altering the chemical constitution of the backbone in the polymer. Application of the polymerization procedure to several N‐alkyl substituted monomers resulted in oligomers of a similar type. The difference in the monomer reactivity depending on the nature of the substituent groups can be due mainly to steric factors.
Polymerization of allyl esters of unsaturated acids. I. Cyclopolymerization of methyl allyl maleate
Authors: Urushido Kunio , Matsumoto Akira , Oiwa Masayoshi 
Published: April 2003

AbstractRadical polymerization of methyl allyl maleate is kinetically discussed in terms of cyclopolymerization using 2,2′‐azobisisobutyronitrile (AIBN) as an initiator and benzene as a solvent at 60°C. The ratios of the rate constants of the unimolecular cyclization reaction to those of the bimolecular propagation reaction of the uncyclized allyl and vinyl radicals, KA and KV, are estimated to be 9.7 and 1.35 mole/liter by fitting the kinetic equations obtained here to the dependence of the degree of cyclization on monomer concentration, respectively; the large difference between KA and KV is also discussed in detail. On the basis of these results the formation mode and the sequence distribution of the structural units of the polymer produced are discussed in detail; thus, for the polymer obtained in the bulk polymerization, about 90% of the cyclic structures can be formed via the intramolecular attack of uncyclized allyl radical on maleic double bond and the probability of succession of the cyclic structural units in diad sequence is exemplified as 0.27.
Multichain copoly(α‐amino acid). I. Multichain copoly(α‐amino acid) prepared by reaction of copoly(L‐lysine γ‐methyl‐L‐glutamate) with N‐carboxy anhydride of Nϵ‐carbobenzyloxy‐L‐lysine
Authors: Sakamoto Munenori , Kuroyanagi Yoshimitsu 
Published: April 2003

AbstractPolymerization of the N‐carboxy anhydride of Nϵ‐carbobenzyloxy‐L‐lysine in the presence of multifunctional polymeric initiator, copoly(L‐lysine γ‐methyl‐L‐glutamate) was studied in N,N‐dimethylformamide containing 3% (v/v) of dimethyl sulfoxide. Multichain copoly(α‐amino acid), i.e., multi‐Nϵ‐poly(Nϵ‐carbobenzyloxy‐L‐lysine)copoly(L‐lysine γ‐methyl‐L‐glutamate), was obtained with linear poly(Nϵ‐carbobenzyloxy‐L‐lysine) as by‐product that could be removed by reprecipitation as was evidenced by gel‐permeation chromatography. The degree of polymerization of the branch polymer chains estimated by the osmometric molecular weight determination and amino acid analysis was between 20 and 60, which decreased with increasing lysine content of the polymeric initiator. The stability of α‐helical conformation of the multichain copoly(α‐amino acid) was studied in the chloroform–dichloroacetic acid system at 25°C by the ORD technique. The α‐helical conformation of poly(Nϵ‐carbobenzyloxy‐L‐lysine) branches was less stable than those of linear poly(Nϵ‐carbobenzyloxy‐L‐lysine) and the core molecular chains of the multichain copoly(α‐amino acid).
Role of monomer charge‐transfer complexes in the free‐radical copolymerization of styrene and fumarodinitrile
Authors: Karad P. , Schneider C. 
Published: April 2003

AbstractThe equilibrium constant of the charge‐transfer complex of styrene and fumarodinitrile was determined by ultraviolet and NMR measurements. Information about the role of the complex in the copolymerization of the two monomers could be obtained from copolymerization experiments at different monomer concentrations and temperatures. In addition, the influence of a second donor, anisole, was studied. The results show that in the copolymerization of styrene with fumarodinitrile addition of charge‐transfer complexes has to be taken into account besides the addition of the free monomers.
Relationships on the effect of water on glass transition temperature and young's modulus of nylon 6
Authors: Reimschuessel H. K. 
Published: April 2003

AbstractThe glass transition temperature Tg of nylon 6 decreases monotonically toward a finite value Tgl upon increase of the moisture content. The mechanism of this decrease entails the reversible replacement of intercaternary hydrogen bonds in the accessible regions of the polyamide. The limiting glass transition temperature Tgl is approached when the moisture content approaches Wl, which corresponds to the amount of water required for complete interaction with all accessible amide groups. Denoting with Tg0 the glass transition temperature of the dry polymer, the effect of water on Tg is represented by the equation, Tg = (ΔTg)0 exp{−[ln(ΔTg)0]W/τWl} + Tgl, where (ΔTg)0 = Tg0 −Tgl, and τ = W(Tgl+1)/Wl. This equation appears to be generally applicable to hydrophilic polymers, since correspondingly calculated data are also in very good agreement with experimental data for polymers such as nylon 66, poly(vinyl alcohol), and polyN‐vinylpyrrolidone. The effect of water of Young's modulus E of nylon 6 is represented by an analogous relationship, and the quantity In[(E−El)/(Tg−Tgl)] is a linear function of the moisture content.
Mechanism of transition between cellulose I and cellulose II during mercerization
Authors: Takai Mitsuo , Colvin J. Ross 
Published: April 2003

AbstractIt is suggested that the transformation from cellulose I to cellulose II during mercerization is the result of a progressive shift of the sheets of cellulose chains within the crystallites of a microfibril from the quarter‐staggered relation in cellulose I to complete correspondence in cellulose II. Qualitatively, the results of such a shift would be consistent with the observed increases in lateral disorder, changes in cell dimensions, swelling, changes in infrared absorption, increases in reactivity of hydroxyl groups and especially with changes in the relative intensities of meridional, x‐ray diffraction reflections of cellulose fibers. The consequences of such a shift also include variations of the dihedral angle at the glycosidic linkage to provide an opportunity for the conformational changes which have been deduced from Raman and infrared spectra. Such a shift may take place in the transformation of native celluloses with antiparallel structure as well as those with parallel polarity. It is consistent with and is able to explain examples of “memory” of previous treatment in cellulose samples.
Selective initiation of nonconjugated dienes containing electron donor–electron acceptor systems. II. Polymerization studies of vinyl ether–β‐nitrostyrenes
Authors: Schweitert James W. , Butler George B. 
Published: April 2003

AbstractThe monomer series, o‐, m‐, and p‐(2‐vinyloxyethoxy)‐β‐nitrostyrenes, was studied. All three monomers were selectively polymerized through the electron‐donating vinyloxy group via cationic initiation. The linear polymers from the meta and para isomers containing the electron‐accepting nitrovinyl group were readily crosslinked via anionic initiation. The polymer derived from the ortho isomer was not crosslinked by this mechanism, an observation in accord with results previously reported from these laboratories in which it was shown that all o‐substituted‐β‐nitrostyrenes having ortho substituents larger than fluorine exhibited a sterically inhibited propagation step. The meta and para isomers of this series were selectively polymerized through the electron‐accepting nitrovinyl group via anionic initiation. Because of the fact that the resulting polymers were soluble only in highly polar solvents, subsequent crosslinking of these polymers via cationic initiation could not be accomplished. However, these polymers showed strong tendencies to undergo crosslinking upon long exposure to air. Because of the sterically induced ortho effect referred to above, no significant polymerization occurred in the case of the ortho isomer of this series via anionic initiation. However, it was shown in this case that initiation via the anion was rapid, and that the slow step was propagation.
High‐pressure polymerization of vinyl chloride
Authors: Ogo Yoshiaki , Yoshikawa Michio , Ohtani Satoshi , Imoto Tatsuya 
Published: April 2003

AbstractThe radical polymerization of vinyl chloride was investigated at 60°C under high pressure up to 5000 bar in benzaldehyde, benzonitrile, toluene, heptane, cyclohexane, and dioxane as solvent. In benzaldehyde and benzonitrile, the polymerizations were depressed by increased pressure. This unusual behavior was explained by the solvent participation and the effect of pressure on the propagating radicals. The crystallinities of polymer obtained in all solvents decreased with increasing pressure, as judged by the absorbance ratio of the infrared spectra. However the effects of pressure on the absorbance ratio of the polymer obtained in benzaldehyde and benzonitrile were not identical with those in the other solvents. These facts also suggest that both solvents play a special role for the solvent participation in the propagating step.
Some electrical properties of wood pulp
Authors: Boutros S. , Hanna A. A. 
Published: April 2003

AbstractThe variation with temperature and frequency of the dielectric constant ε′ and the dielectric loss ε″ for sheet wood pulp and ground wood pulp were measured. Also, the effect of the relative humidity on the dielectric behavior was measured for the ground sample at 25°C. For the dry ground wood pulp, the dielectric constant is larger than that for the dry sheet sample. This may be a result of the increase in the surface area, of the decrease in the size of crystals and/or of the decrease in the degree of crystallinity on grinding of the sheet sample. The variation of ε″ with frequency passes through a maximum. From the shift of this maximum with temperature, it is found that the apparent activation energy ΔH for this relaxation is equal to 7.06 kcal/mole and it is attributed to the polarization of the OH groups in the cellulose molecule. From the relation between the dielectric constant and the specific resistivity Rs, the dissociation energy U0 for the ground wood pulp was calculated. U0 for this sample below and above 52% RH is 0.315 and 5.13 × 10−12 erg, respectively. Also, the dissociation energy of Egyptian Ashmouny cotton was calculated. The variation of the electrical conductivity σ with humidity for different types of cellulosic materials is represented graphically.
Solute radical ion yields of γ‐irradiated aromatic compounds in poly(methyl methacrylate) at 77°K
Authors: Torikai Ayako , Kato Ryuzo 
Published: April 2003

AbstractIonic species in γ‐irradiated poly(methyl methacrylate) (PMMA) matrices were investigated. γ‐Irradiation of several aromatic solutes in PMMA gave rise to the radical cations and anions of the solutes. The limiting yields of radical cation and anion were determined to be 1.0–1.5 and 0.7–0.9, depending on the characteristics of the solutes, respectively. These values were compared with those in low‐molecular‐weight matrices. The distance of positive charge migration was estimated. The experimental results show that the charge transfer from PMMA to the solutes may be responsible for the formation of the radical cations and anions.
Thermal degradation of polybis(p‐isopropylphenoxy)‐phosphazene
Authors: Goldfarb Louis , Hann Nancy D. , Dieck Ronald L. , Messersmith David C. 
Published: April 2003

AbstractPolybis(p‐isopropylphenoxy)phosphazene was treated thermally at 100, 135, 200, and 300°C. The resulting reductions in weight‐average molecular weights were monitored by gel‐permeation chromatography, and the experimental observations led to the adoption of a random chain‐scission model. An effective energy of activation and entropy of activation were calculated for the degradation process, and these values were found to be consistent with a random‐scission model. The analysis was, in part, based on a computer‐simulated first‐order degradation model. This polymer showed higher thermal stability than previously reported polyaryloxyphosphazenes.
Donor–acceptor complexes in copolymerization. LVIII. Alternating diene–dienophile copolymers. 12. Structure of furan–maleic anhydride copolymers prepared from the monomers and the diels‐Alder adduct
Authors: Gaylord Norman G. , Martan Michael , Deshpande Achyut B. 
Published: April 2003

AbstractThe copolymerization of furan with maleic anhydride in the presence of a perester or azobisiso‐butyronitrile at 50 or 70°C yields an unsaturated equimolar, alternating copolymer in which the furan units have 3,4 unsaturation and 2,5 linkages. The furan–maleic anhydride Diels‐Alder adduct undergoes retrograde dissociation in solution at 70°C and, in the presence of radical catalysts, yields the same unsaturated alternating copolymer as is obtained from the monomers. The adduct undergoes homopolymerization in the presence of a rapidly decomposing perester at 50°C to yield a saturated polymer having a rearranged structure containing 3‐oxabicyclo[2.2.1]heptane‐5,6‐dicarboxylic anhydride repeating units with 2,7 linkages.
Kinetic approach to radiation‐induced grafting in the polyethylene–styrene system. III
Authors: Imai Masahiko 
Published: April 2003

AbstractThe method of investigation reported in previous papers was applied to preirradiation methods of reaction in vapor and in liquid. The absorption dose was varied from 2 to 0.1 Mrad. The monomer concentrations during reactions were determined gravimetrically. The patterns of increase of the degree of grafting did not change as the dose was varied in the liquid but changed considerably with dose in the vapor. The monomer concentration during the reaction did not vary with dose in the liquid but did so in the vapor. A model calculation was applied and improved to make the monomer concentration agree with that in the experiment. An attempt was made to describe the mechanism involved. There were some differences between the calculated values and the experimentally obtained ones, but the outline of the reaction mechanism was explained satisfactorily.
Das Monte Carlo‐studium der verteilung der sequenzen in den copolymeren des methylmethacrylats mit chloropren und des 2‐hydroxyäthyl‐methacrylats mit alkylacrylaten
Authors: Motoc I. , Holban St. , Vancea R. 
Published: April 2003

AbstractUsing our Monte Carlo model of binary copolymerization, one studies the sequence distribution in methyl methacrylate/chloroprene and 2‐hydroxyethyl methacrylate/alkyl acrylate copolymers. Our study points out incontestably that the copolymerization of methyl methacrylate is explainable through ultimate group effect (Ebdon has stated a penultimate group effect). In the case of 2‐hydroxyethyl methacrylate/alkyl acrylate copolymers the agreement between computed and experimental data is satisfactory.
Interaction of polyesters with epoxy polymers: Insertion of oxirane rings into ester bonds
Authors: Komarova L. I. , Salazkin S. N. , Bulgakova I. A. , Malaniya M. I. , Vinogradova S. V. , Korshak V. V. 
Published: April 2003

AbstractEpoxy oligomers readily interact (hardening) with polyesters of different structures (heterochain, carbochain, aliphatic, aromatic), as indicated by the change of properties and infrared spectra of an epoxy polymer–polyester composition on heating. The curing is caused by the reaction of the oxirane ring with ester groups and proceeds by the mechanism of “insertion” of the fragment of the oxirane cycle into the ester bond without scission of the molecular chain of polyesters. This mechanism of interaction is confirmed by study of a model reaction of phenyl benzoate with phenylglycide ether to lead to the formation of 1,3‐diphenyl ether of 2‐benzoyl glycerine. The latter was also produced by another way. The reaction of polyarylate with phenylglycide ether confirmed also that interaction of the ester group with the oxirane ring proceeds by the mechanism of “insertion.” This interaction proceeds with a high conversion and without rupture of the macromolecules (molecular weight does not decrease). The reaction of the oxirane ring with the ester group is accelerated in the presence of sodium salts of carboxylic acids, carbonic acid, and sodium phenolates.
Syntheses of polyamides and polybenzodipyrrolediones from pseudo diacetylphthaloyl chlorides and diamines
Authors: Ueda Mitsuru , Takahashi Takeyoshi , Imai Yoshio 
Published: April 2003

AbstractNovel diacetylphthalic acids, 2,5‐diacetylterephthalic and 4,6‐diacetylisophthalic acids, were synthesized starting from pyromellitic dianhydride. These diacids were subsequently converted to the corresponding pseudo diacetylphthaloyl chlorides. The ring‐opening polyaddition, followed by dehydrochlorination, of the pseudo diacetylphthaloyl chlorides with aliphatic diamines in a polar aprotic solvent afforded almost quantitatively polyamides having inherent viscosities of 0.3–0.7. The solution polymerization was almost completed within 1 hr at room temperature. These polyamides were soluble in acidic solvents like m‐cresol. Subsequent cyclodehydration of the polyamides by heating at 200°C gave insoluble polybenzodipyrrolediones, which underwent weight losses of 10% at around 400°C under nitrogen.
Poly[2,2‐dimethyl‐4‐(methoxylcarbonyl) butylene]: Synthesis with an ethylaluminum sesquichloride–peroxide initiator and NMR characterization
Authors: Kuntz I. , Chamberlain N. F. , Stehling F. J. 
Published: April 2003

AbstractThe alternating copolymer of isobutylene and methyl acrylate (the polymer of the title) has been obtained by using ethylaluminum sesquichloride (AlEt1.5Cl1.5) and 2‐methylpentanoyl peroxide as the initiating system in benzene solution. The alternating copolymer is obtained at an acrylate/Al molar ratio of 17. Higher ratios increase the level of acrylate residues in the copolymer isolated; in the absence of AlEt1.5Cl1.5, an equal molar feed gives a copolymer with 75 mole % acrylate units. 1H‐ and 13C‐NMR spectra have been used to study the details of polymer structure and support the equal molar, alternating nature of the macromolecule. The details of the methoxy and gem‐dimethyl peaks in the PMR spectra are consistent with a Bernoullian process determining the polymer configurational sequences, with Pm = 0.55–0.60.
Grafting onto wool. III. Graft copolymerization of poly(vinyl acetate) by use of fenton's reagent as initiator
Authors: Misra B. N. , Chandel P. S. , Dogra Ramesh 
Published: April 2003

AbstractIn an attempt to modify fibrous protein, poly(vinyl acetate) has been graft copolymerized onto Himachali wool in an aqueous medium by using Fenton's reagent as redox initiator. Graft copolymerizations were carried out at 25, 30, 35, 40, and 45°C for a period of 3 hr. Percentage grafting was found to be dependent upon reaction temperature, concentration of monomers, and the molar ratio of [H2O2]/[Fe+2]. Maximum grafting occurred at 45°C with a molar ratio of [H2O2]/[Fe+2] = 1.43. A small amount of grafting (2.6–2.8%) occurred when grafting was effected at 45°C in the presence of Fe+2 alone.
Sequence distribution of repeating units of copolyamides by interfacial or solution methods
Authors: Ogata Naoya , Sanui Kohei , Kamiyama Shiro 
Published: April 2003

AbstractThe sequence distribution of repeating units of copolyamides from different diamines with isophthaloyl or terephthaloyl chlorides and dithiophenyl adipate have been investigated either by interfacial or solution methods to aim at the sequence control of the copolyamides by solvents.Copolycondensation of dithiophenyl adipate and isophthaloyl chloride with m‐xylylenediamine in various solvents yielded copolyamides having different compositions of repeating units. Aprotic polar solvents produced random copolyamides having the same compositions as feed ratios of the comonomers, while nonpolar solvents yielded copolyamides rich in isophthaloyl units. Also the sequence distribution of the copolyamides from m‐ and p‐phenylenediamines with isophthaloyl chloride was affected by solvents; nonpolar solvents produced copolyamides having a less‐random and block character of the repeating units either by interfacial or solution methods.
Dielectric study of viscose rayon and viscose hydrocelluloses. II
Authors: Shinouda H. G. , Hanna A. A. , Kinawi A. 
Published: April 2003

AbstractThe effect of temperature on the dielectric properties of viscose fibers as well as of some of its acid‐modified residues was investigated. The results obtained show that: first, the change in the fine structure accompanying the acid degradation of the fibers has little, if any, effect on the location of the β peaks at any given temperature; second, the thermal transition of viscose fibers disappears with the late hydrolyzed vacuum‐dried residues. These results are discussed in the light of infrared spectra of the OH stretching vibration as well as specific volume data.
New polyphenylquinoxalines linked by m‐terphenyl flexibilizing groups
Authors: Rabilloud Guy , Sillion Bernard 
Published: April 2003

AbstractThree new monomers with phenylglyoxyloyl groups fixed on the 4,4′‐, 4,6′‐, and 4,4″‐positions of m‐terphenyl were synthesized by different pathways. They were used to prepare a series of polyphenylquinoxalines by solution polycondensation with 3,3′‐diaminobenzidine and 3,3′,4,4′‐tetraaminodiphenyl ether. These polymers exhibited excellent oxidative and thermal stability as shown by thermogravimetric analysis and isothermal aging in circulating air between 300 and 450°C. Clear yellow films, cast from m‐cresol solution, were used to measure their softening temperature by thermomechanical analysis (TMA). Numerical data thus obtained, indicated a thermoplastic behavior in the temperature range 300 ± 15°C. Crosslinking of the linear polymers by isothermal heat exposure under argon between 300 and 500°C was investigated by means of TMA. Molded materials were fabricated under constant pressure (996 psi) at 500–525°C with an Instron testing machine. These polymers were also used for preliminary evaluation as matrices for 181‐E glass reinforced composites. Flexural values obtained after isothermal aging in air up to 400°C indicated a potential use varying from 150 hr at 350°C to 24 hr at 400°C.