bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aromatic polymides. VII. Synthesis of sulfonated poly(para‐phenyleneterephthalamide): Polymerization of 1,4‐bis(trichloromethyl) benzene with para‐phenylenediamine sulfate in SO3
Authors: Silver Frank M. 
Published: April 2003

Abstractpara‐Phenylenediamine sulfate polymerized with 1,4‐bis(trichloromethyl)benzene in SO3 at > 20% polymer concentration to form highly anisotropic (liquid crystalline) sulfonated poly(para‐phenyleneterephthalamide) (S‐PPT) solutions with inherent viscosities as high as 1.2. Analogous to the polymerization of para‐phenylenediamine sulfate with terephthalic acid in SO3 reported previously, sulfonation of the aromatic diamine ring of S‐PPT was not competitive with the polymerization reaction, but it was a major side reaction.
On the reactivity of cellulose free radicals in graft copolymerization reactions
Authors: Hon David N. ‐S. 
Published: April 2003

AbstractThe formation and behavior of photo‐and mechanoinduced free radicals in cellulose were studied by ESR spectroscopy and the capability of these free radicals to initiate graft copolymerization reactions was demonstrated. Although an 11‐line ESR signal was detected from cellulose irradiated with ultraviolet (UV) light, a higher‐intensity ESR signal with a five‐line pattern was detected from a sample mechanically milled at 77 K. The decay of photoinduced free radicals when heated took place monotonously, whereas mechanoradicals exhibited an anomalous behavior with an increased signal intensity at 150 K before decaying at a higher temperature. Mechanoradicals have been found to react more efficiently and rapidly with oxygen and methyl methacrylate (MMA) than photoinduced free radicals. The peroxy mechanoradicals, however, were mobile and decayed more rapidly than the peroxy photoinduced radicals. Simultaneous graft copolymerizations of MMA to cellulose demonstrated that mechano‐and photoinduced free radicals are capable of initiating grafting reactions, but a higher degree of grafting efficiency was obtained from cellulose treated mechanically.
Effect of tin tetrachloride on thermal decompositions of α,α′‐azobisisobutyronitrile and dimethyl α,α′‐azobisisobutyrate
Authors: Yamada Bunchiro , Kamei Hiroaki , Otsu Takayuki 
Published: April 2003

AbstractThermal decomposition of α,α′‐azobisisobutyronitrile (AIBN) and dimethyl α,α′‐azobisisobutyrate (MAIB) in the presence of a large amount of tin tetrachloride was investigated to determine the effect of complex formation on the decomposition rates and yields of the recombination products. The addition of tin tetrachloride significantly increased the decomposition rates; the observed first‐order rate constant increased by factors of 4.5 and 17 at molar ratios of [SnCl4]/[AIBN] = 21.65 and [SnCl4]/[MAIB] = 19.53, respectively. It was found that the decomposition of these azo compounds was also accelerated by the addition of a comparable amount of donor solvent such as ethyl acetate or propionitrile to tin tetrachloride and that the enhancement in rate was accounted for by a larger frequency factor in the Arrhenius equation. Furthermore, the addition of tin tetrachloride seemed to suppress the formation of recombination products, tetramethyl succinonitrile and dimethyl tetramethylsuccinate, of the radicals produced by decomposition.
Kinetic features of cationic oligomerization of epoxides
Authors: Ivanchev S. S. , Pavlyuchenko V. N. , Khaikin S. Ya. , Vladimirova L. G. , Balaev G. A. , Shevchuk V. I. 
Published: April 2003

AbstractThe kinetic features of the cationic oligormerization of epoxides of various structures influenced by Lewis acids (BF3OEt2, SnCl4) were investigated. It was shown that the systems studied could he divided into three groups, based on the nature of conversion‐time kinetic curves of oligomerization: (1) (Epoxypropane‐BF3OEt2, 3,4‐epoxybutene‐1‐BF3OEt2) oligomerization stops before the monomer is exhausted completely. (2) (1‐Chloro‐2,3‐epoxypropane‐BF3OEt2 or SnCl4, 2‐methyl‐2,3‐epoxybutane‐BF3OEt2) oligomerization can be carried out almost up to complete conversion of the monomer. The reaction rate, however, decreases more rapidly than that expected from the kinetics of monomer consumption. (3) (1‐tert‐Butylperoxy‐2,3‐epoxypropane‐SnCI4) oligomerization kinetics are described by a simple exponential function with regard to monomer concentration. Determination of the propagating species concentration in the systems studied suggests that the initiation of cationic oligornerization of epoxides with Lewis acids is an instantaneous process and the discrepancy observed is a result of the different nature of kinetics of the active site destruction. In the first group of systems the rapid destruction of the propagating species prevents the oligomerization to complete conversion. In the second group a somewhat lower rate of decrease in concentration of the propagating species with time is explained by their regeneration during the process. In the third system, which is a unique case, the concentration of the propagating species remains constant with time. It is assumed that these features are the result of the stability or pseudostability of the active sites which depends on the nature of the epoxide and initiator.
C3 cyclopolymerization. I. Is the cyclopolymerization of 1,3‐bis(p‐vinylphenyl)‐propane by means of radical or anionic initiators possible?
Authors: Nishimura J. , Ishida Y. , Mimura M. , Nakazawa N. , Yamashita S. 
Published: April 2003

AbstractPolymerization of 1,3‐bis(p‐vinylphenyl) propane (St‐C3‐St) was investigated by using radical and anionic initiators. Radical polymerization yielded linear polymer with pendant styryl groups in pertinent conditions without gelation. Anionic polymerization with n‐butyllithium and sodium naphthalene produced insoluble polymers that, according to infrared (IR) spectroscopy, had no cyclized units. On the other hand, phenylmagnesium bromide gave soluble polymer in HMPA‐benzene mixed solvent. Zero‐valent nickel catalyst also gave soluble polymer. The soluble polymers could be analyzed by several spectroscopies, and it was confirmed that those obtained by anionic and coordination polymerization had no [3.3]paracyclophane units in the main chain. From these results it was concluded that cationic propagation could be assumed if the polymer Of St‐C3‐St contained [3.3]paracyclophane units in the main chain.
C3 cyclopolymerization. II. Charge‐transfer cyclopolymerization of 1,3‐bis(p‐vinylphenyl)‐propane
Authors: Nishimura J. , Mimura M. , Nakazawa N. , Yamashita S. 
Published: April 2003

AbstractThe thermal and photoinduced polymerization of 1,3‐bis(p‐vinylphenyl)propane was carried outby using tetracyanoethylene as a strong electron acceptor in several solvents. This cyclopolymerization produced polymer that contained [3.3]paracyclophane units in the main chain. The solvent and additive effect of polymerization inhibitors as well as the polymer structure suggest clearly that both polymerization proceeded in a cationic mechanism.
Trapping alloxan or ninhydrin radical anions with polymer cations
Authors: Endo Takeshi , Okawara Makoto 
Published: April 2003

AbstractAlloxan or ninhydrin radical anions which are obtained from alloxantin or hydrindantin, respectively, by treatment with triethylamine could be trapped in stable condition by polymer cations that contains 1‐benzyl‐3‐carbamoyl pyridinium or 1‐benzylpyridinium salts structure.
Grafting vinyl monomers onto silk fibers. IX. Graft copolymerization of methyl methacrylate onto silk using peroxydiphosphate‐thiourea redox system
Authors: Nayak Padma L. , Lenka Subasini , Mishra Munmaya K. 
Published: April 2003

AbstractThe graft copolymerization of methyl methacrylate (MMA) onto silk in aqueous media initiated by the potassium peroxydiphosphate‐thiourea redox system was studied at 50°C. The rate of grafting was determined by changing [monomerl], [thiourea], [initiator], acidity of the medium, reaction medium, and temperature. A significant increase percent of grafting was noticed with increasing monomer concentration to 84.49 × 10−2 mole/liter and the further increase is associated with the decrease of graft yield. The graft yield increases with an increase of thiourea (Tu) concentration to 25 × 10−5 mole/liter; then it decreases. A measurable increase in graft yield was observed with an increase in acidity of the medium. Graft yield increases to a certain temperature, i.e., 50°C, and then it decreases. The graft yield increases with an increase of initiator concentration to 60 × 10−4 mole/liter; then it decreases. The graft yield is medium dependent. A suitable kinetic path has been proposed and the rate equation has been derived.
Surface grafting of polyethylene by mutual irradiation in methyl acrylate vapor. IV. Kinetic analysis by quartz helix microbalances
Authors: Yamakawa Fumio , Yamakawa Shinzo 
Published: April 2003

AbstractA detailed kinetic study of the γ‐ray‐induced surface grafting of methyl acrylate (MA) onto polyethylene (PE) has been investigated by using quartz helix microbalances. Under typical graft conditions, the grafting rate increases, levels off, and then accelerates with irradiation time; i.e., the typical growth process of the surface grafting consists of an initial stage having an increasing rate of grafting, an intermediate stage having a constant rate, and an advanced stage having an accelerated rate. A homopolymer layer (consisting only of an MA component) begins to be formed on the inner graft copolymer layer (consisting both of MA and PE components) at the transition zone in grafting rate after a duration of a constant rate of grafting. Therefore, the increasing rate in increasing rate in the intial stage of grafting reflects the graft copolymerization in the graft copolymer layer (inside the PE sheet), and the increasing rate in the advanced stage reflects the growth of the homopolymer layer. Under grafting reflects the graft tage reflects the growth of the homopolymer layer. Under grafting conditions by which the homolymer layer is not formed throughout the whole grafting process, the surface grafting remains remains in the initial stage. On the order hand, under grafting conditions by which the homopolymer layer begins to be formed from an early stage of grafting, the surface grafting proceeds rapidly from the initial stage to the advanced stage and thus skips the intermediate stage.
Studies on the graft polymerization of carbon fibers. I. The graft polymerization of acrylate monomers and their properties
Authors: Tanaka Akira , Fujisawa Takao , Yosomiya Ryutoku 
Published: April 2003

AbstractGraft polymerization was carried out on carbon fibers subjected to various types of oxidation treatment and on acrylate (methyl, ethyl, andn‐butyl) with benzene solvent and mainly benzoyl peroxide as initiator according to the nitrogen‐displacement sealed‐tube polymerization method. In comparison with carbon fibers subjected to air oxidation treatment, carbon fibers subjected to nitric acid oxidation treatment showed easier graft polymerization, and grafting became easier with increasing degree of nitric acid oxidation. The following relationship is established between the graft reaction ratio (a) and the polymerization time (t):da/dt=K(100−a). For graft polymerization with lauroyl peroxide (LPO), benzoyl peroxide (BPO), and α,α′‐azobisisobutyronitrile (AIBN) as initiator, LPO showed the largest transfer reaction constant, followed by BPO; AIBN showed the smallest value. Grafting showed a tendency to become easier for monomers with a larger displacement radical group. For the graft polymerization reported in this article, it was believed that the affinity between carbon fibers subjected to oxidation treatment and to monomer influenced the result. For graft polymerization using acrylic acid as the comonomer, percent grafting increased notably. It is believed that, in this, in this case, apparent grafting by dipole‐dipole interaction of the COOH group of the carbon fiber subjected to oxidation treatment and the COOH group of the polymer occurs according to the theory of Riess et al. Tensile strength and breaking elongation of graft carbon fibers showed a tendency to increase with an increase in percent grafting, whereas Young's modulus showed a tendency to decrease. The contact angle with water showed a tendency to increase with increasing percent, whereas the contact angle with ethylene glycol and phenylglycidilethyl showed a tendency to decreasing percent grafting.
The preparation of 1,4‐dicarbonyl, 4‐oxo nitrile, furan, and pyrrole monomers
Authors: Ponticello I. S. , Pastor P. C. 
Published: April 2003

AbstractTreatment of cyclopentadiene‐blocked acrolein with α,β‐unsaturated ketones, esters, and nitriles in the presence of a thiazoliurn salt under basic conditions led to a simple method for the preparation of acetonylmethyl Vinyl ketone, 2‐carboxymethylethyl vinyl ketone, and 2‐cyanoethyl vinyl ketone. In addition, the cyclopentadiene‐blocked acetonylmethyl vinyl Ketone was converted to heterocyclic furan and pyrrole monomers.
Photochemistry of polymeric systems. I. Photocrosslinking of polymers and copolymers containing pyridine N‐oxide groups
Authors: Decout Jean‐Luc , Lablache‐Combier Alain , Loucheux Claude 
Published: April 2003

AbstractVinylpyridine‐N‐oxide units were introduced in polymeric chains in order to study their photocrosslinking. Copolymers of styrene and 4‐vinylpyridine‐N‐oxide were especially synthesized and studied. The methods used for characterization of photocrosslinked films were a “photoresist test” or the measurement of the insolubility and of the swelling ratio. The Cleavage of the N‐oxide bond was responsible for the photocrosslinking. The competitive formation of carbonyl compounds took place and decreased the rate of photocrosslinking. This last reaction is favored by triplet‐state quenchers. The photosensitivity of the copolymers was determined as a function of the wavelength of the radiation used. When the photocrosslinking proceeded, a film of the copolymeric material became transparent in the 280–320‐nm range. Thick films could therefore be completely photocrosslinked when irradiated in this range of wavelength.
Stabilization at high temperatures
Authors: Brun E. B. , Shustova O. A. , Kuchanov S. I. , Gladyshev G. P. 
Published: April 2003

AbstractA general detailed model of polymer oxidative degradation in the presence of a stabilizer‐oxygen acceptor was considered. The motion of the degradation zone boundary and the sample lifetime were obtained for various conditions of the process. In particular, it is shown that within the given concentration immobile oxygen acceptor has the best stabilizing properties. The theoretical results are compared with the experimental data obtained by using two independent methods: polymer sample cracking and a change in the ESR signal. Good agreement between theory and experiment was obtained.
Synthesis of 1,1‐dichloro‐2,2‐bis(4‐hydroxyphenyl)‐ethylene via ammonia or methylamine dehydrochlorination. A bisphenol for the preparation of highly flame‐resistant polycarbonates
Authors: MacLaury M. R. , Chan A. D. , Colley A. M. , Saracino A. , Toothaker A. M. 
Published: April 2003

AbstractAmmonia used as both reactant and solvent has been shown to dehydrochlorinate 1,1,1‐tri‐chloro‐2,2‐bis(4‐hydroxyphenyl)ethane smoothly to 1,1‐dichloro‐2,2‐bis(4‐hydroxyphenyl)ethylene. The reaction is complete in 1 hr at 100°C, and after two crystallizations from methanol/water affords polymerizable quality monomer for the synthesis of highly flame‐resistant polycarbonates. The use of organic solvents in combination with ammonia does not offer any rate advantages over pure ammonia. Primary and secondary amines also can be used to effect the dehydrochlorination but, except for the methylamine, are significantly less reactive and lead to less pure product than amonia.
Polymeric p‐benzoquinone‐tin derivatives as thermal stabilizers for rigid poly(vinyl chloride). I. Preparation of the stabilizers
Authors: Yassin Ahmady A. , Sabaa Magdy W. 
Published: April 2003

AbstractThe reaction of p‐benzoquinone with tin tetrachloride in the absence of solvents was investigated by isolation and identification of the reaction products. This reaction leads to the formation of polymeric quinone‐tin derivatives free from combined chlorine, chlorinated quinones, quinhydrone, and minute amounts of CI2 and HCI gases. The tin content varies accroding to the molar ratios of the reactants and reaches its maximum (72%) at the smallest SnCI4 ratio. The existence of the Sn‐Sn bond in the polymeric derivatives was confirmed chemically and spectroscopically. A mechanism based on the formation of radical intermediates which can account for the reaction products was developed. In view of their quinonoid nature, high thermal stability, and the presence of Sn‐Sn bonds, the polytin derivatives are to be investigated as radical traps in the stabilization of polymeric arcticles against radical degradation process.
Photorearrangements of hydrocarbon polymers with pendant double bonds
Authors: Golub Morton A. , Rosenberg Mark L. 
Published: April 2003

AbstractA study was made of the microstructural changes that occur in ultraviolet irradiation under vacuum of thin films of 1,2‐poly(cis‐1,4‐hexadiene) (CHD), 1,2‐poly(trans‐1,4‐hexadiene) (THD), 1,2‐poly(trans‐1,3‐pentadiene) (TPD), equibinary (1,2,‐1,4) polybutadiene (EB), and equibinary (3,4‐1,4) polyisoprene (EI). These polymers—all containing pendant double bonds—undergo important photoinduced loss of unsaturation, presumably through cyclization of the double bonds, by analogy to the previously reported photocyclization of 1,2‐polybutadiene (VB) and 3,4‐polyisoprene (VI)films. For the equibinary polymers, which contain internal as well as external (or pendant) double bonds, the loss of unsaturation is considered to involve photocyclization of 1,2‐1,4 and 1,2‐1,2 dyads in EB and of 3,4‐1,4 and 3,4‐3,4 dyads in EI. Accompanying thecyclization process in CHD, THD, and TPD is a direct photochemical cis‐trans isomerization of CHCHdouble bonds analogous to that originally noted for 1,4‐polybutadiene. The photorearrangements in the above polymers with pendant double bonds were compared to the corresponding thermally induced rearrangements reported previoulsy;for VB and VI, in particular, the thermal, photo‐and radiation‐induced cycli‐zations were found to be very similar, possibly having a common nonradical, nonionic mechanism involving excited double bonds.
Mössbauer study of the γ‐induced polymerization of iron methacrylate
Authors: Sarma P. R. , Tripathi K. C. , Gupta H. M. 
Published: April 2003

AbstractA Mössbauer spectroscopic study of the γ‐induced polymerization of iron methacrylate has been made. Iron‐methacrylate is a solid monomer. This monomer, in a powdered form, was polymerized by irradiating with γ rays from a 60Co source. A number of Mössbauer spectra were taken after subjecting the sample to different cumulative doses of γ rays. The spectra were asymmetric doublets and the asymmetry changed as the polymerization proceeded. The changes in asymmetry have been correlated with the percentages of polymerization which were determined by two different methods, viz., chemical analysis and resistivity measurement.
The topochemistry of the catalytic systems on the surface of polymer supports
Authors: Dyachkovskii F. S. , Pomogailo A. D. , Bravaya N. M. 
Published: April 2003

AbstractThe method of spin labels based on stable iminoxyl radicals has been applied to the investigation of the topochemistry of polymer‐supported polyethylene‐grafting diallylamine (PE‐gr‐PDAA)and ofimmobilized catalytic systetms. The effective distances between fixed radicals are comparatively large (r̄ ∼ 25‐35Å for the case of functional groups of PE‐gr‐PDAA and r̄ ≥ 35Å for the case of fixed components of the catalytic systems). The demonstration of step‐by‐step penetration of the label into the functional cover (100‐300 Å) has been made. Correlation times were calculated in the temperature range 290‐440K. The dependence of log τc on 1/T shows two linear parts to the curve.The activation energies in the α region for PE‐gr‐PDAA and for the product of its interaction with TiCl4. Ti(OC4H9)4, and Al(C2H5)2Cl are equal to 13, 14, 24, and 13 Kcal/mole, respectively. The method has been applied to the investigation of Ziegler‐Natta immobilized catalytic systems. It has been noted that the labels are fixed not far from each other (r̄ ≤ 12Å) after the interaction of the catalytic components.
Tricarbonylchromium‐complexed phenylsiloxane polymers as stereoselective hydrogenation catalysts: Preparation and properties
Authors: Awl R. A. , Frankel E. N. , Friedrich J. P. , Swanson C. L. 
Published: April 2003

AbstractSoluble tricarbonylchromium complexes were made by reacting Cr(CO)6 with a ladder polyphenylsilsesquioxane and a linear polydiphenylsiloxane. These new polymer Cr(CO)3 complexes were characterized by elemental Cr, infrared (IR), gel permeation chromatography (GPC), viscosity, and thermal analyses and were evaluated as stereoselective hydrogenation catalysts. Thermogravimetry studies demonstrated that the new complexes were more stable at 180–200°C in N2 than the corresponding complex from crosslinked polystyrene. These silicone polymer complexes catalyzed stereoselective hydrogenation of methyl sorbate to cis‐3‐hexenoate in cyclohexane and tetrahydrofuran (THF) and could be recovered from THF for recycling by precipitation‐fiItration. Catalytic activity and recyclability, however, were highly influenced by the solvent. Loss of catalytic activity associated with loss of Cr(CO)3 was observed on recycling. These results support a mechanisim that involves dissociation of Cr(CO)3, a significant portion of which cannot become reassociated with the polymer phenyl groups.
A molecular approach to flavor synthesis. I. Menthol esters of varying size and polarity
Authors: Jabloner H. , Dunbar B. I. , Hopfinger A. J. 
Published: April 2003

AbstractFor a series of menthol esters of increasing size and polarity, “mintyness” decreased rapidly as molecular weight increased. For molecular weights above about 700, the compounds were tasteless to a significant proportion of the taste panel. As polarity increased, the “sweet minty” taste of hydrophobic menthol esters became increasingly bitter, until water‐soluble menthol esters were strongly bitter. Bitterness was still apparent in quite high‐molecular‐weight water‐soluble esters; a different receptor may be involved for bitterness than for mint. An overall hypothesis relating flavor to molecular solubility parameters is proposed.
Polymerization of substituted cyclopropanes. III. Anionic polymerizations of 2‐substituted cyclopropane‐1,1‐dicarbonitriles
Authors: Cho Iwhan , Kim Jin‐Bong 
Published: April 2003

AbstractTo investigate further the anionic ring‐opening polymerization of substituted cyclopropane 2‐phenylcyclopropane‐1,1‐dicarbonitrile (I), 2‐ethylcyclopropane‐1,1‐dicarbonitrile (II), and 2,2‐dimethylcyclopropane‐1,1‐dicarbonitrile (III) were prepared and polymerized with sodium cyanide in N,N‐dimethylformamide. Under these conditions only I polymerized well. The polymer in I was soluble in hot sulfolane and the inherent viscosity was 0.5 dl/g (conc. 0.5 g in 100 ml). This result supports the previously postulated mechanism that a cyclopropane ring with properly positioned electron‐donating and electron‐withdrawing substituents can polymerize by opening the bond activated by a “push–pull” system.