bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymers with a graphitic‐type structure. II
Authors: Kellman Raymond , Marvel C. S.
Published: April 2003

Further work has been done on the synthesis of a polymer from 1,4,5,8‐tetraaminoanthraquinone on 1,3,6,8‐tetraketo‐1,2,3,6,7,8‐hexahydropyrene which has a graphitic‐type structure. Improved purity of the starting materials, particularly of the tetraketone, has given a final product of better quality. The reaction conditions have been improved by lowering the temperature and increasing the time of the reaction.
Rigid rod‐random coil transformation, Mark‐Houwink constants, and Millich's intrinsic isoviscosity, [η]M, and isohydrodynamic volume, [η]MMM
Authors: Millich F. , Hellmuth E. W. , Huang S. Y.
Published: April 2003

On the basis of values of Mark–Houwink constants of rigid rod—polymer systems and their conformers a unique stage can be recognized which is common to all polymers of this type, independent of polymer conformation and solvent medium. The crude values derived for these polymer–solvent systems at 20–30°C. of Millich's intrinsic isoviscosity, [η]M, is 0.28 ± 0.04 dl/g, occurring at the coordinate molecular weight, MM, of 42,700, and produces a value of ca. 170 Å of Millich's isohydrodynamic polymer volume at this stage and temperature. Utility in the use of [η]MMM as a standard reference state, assuming reliable Mark–Houwink constants that obtain for strictly linear, monodisperse polymer samples, is indicated.
Thermal degradation of poly(tetramethyl‐p‐silphenylene) siloxane homopolymers and copolymers in nitrogen
Authors: Funt J. M. , Parekh R. D. , Magill J. H. , Shah Y. T.
Published: April 2003

The thermogravimetry (TGA) in nitrogen was measured for poly(tetramethyl‐p‐silphenylene)‐siloxane (TMPS) fractions with narrow molecular weight distributions and for block copolymers of TMPS and dimethyl siloxane (DMS) with varying composition. The measurements were made with the Perkin‐Elmer DCS IB‐TGA attachment which consists of a Cahn electrobalance and a wire‐wound furnace with programmable temperature controls. The weight loss curves for heating rates of 10, 20, and 40°C/min were analyzed using the method of Flynn and Wall. The analysis indicates that thermal degradation proceeds primarily by scission of the siloxane bond with an activation energy of 44 ± 3 kcal/mole for the uncatalyzed reaction and 13 ± 2 kcal/mole for the reaction occurring in the presence of residual catalyst. The thermal stability of the TMPS–DMS copolymer is impaired through increasing the concentration of the DMS component. Cyclic DMS trimer and TMPS monomer and dimer were observed by mass spectrometry which gave results consistent with the proposed mechanism of degradation.
Synthesis, characterization, and properties of block and bigraft copolymers
Authors: Kennedy Joseph P.
Published: April 2003

The syntheses of poly(styrene‐b‐isobutylene), poly[(ethylene‐co‐propylene‐co‐1,4‐hexadiene)‐g‐styrene‐g‐α‐methylstyrene], and poly[(ethylene‐co‐propylene‐co‐1,4‐hexadiene)‐g‐styrene‐g‐isobutylene] have been accomplished by using the principle of selective sequential initiation. This method makes use of the large differences in initiation rates that exist between labile organic chlorides and bromides when these halides interact with alkylaluminum compounds. Synthesis conditions have been worked out which allow composition control. These new AB blocks and bigrafts exhibit unusual mechanical and solubility properties, some of which will be described. For example, the Nordel‐g‐PSt‐g‐PIB bigraft exhibits only one low temperature transition (DSC, Rheovibron), suggesting an intimate aggregation of Nordel and polyisobutylene phases.
New developments in photochromic polymers
Authors: Smets G.
Published: April 2003

New developments on photochromic polymers have been obtained with systems containing spirobenzopyran derivatives. The importance of the chemical incorporation of the photochrome within the polymer backbone is stressed, and the influence of matrix orientation on the rate of fading is shown. Well known fatigue phenomena are illustrated on the basis of the changes of photostationary optical density on repeating the irradiation–dark recovery cycle. The photomechanical properties and characteristics of rubbery polyethylacrylates crosslinked with the photochrome bismethacrylate are considered in detail. Another principle of photochromism based on photodissociation phenomena is also discussed in the case of the photodissociation and photorecombination of anthracene derivatives and benzacridizinium tosylate, as well as in the case of the photodissociation and thermal recombination of benzpinacol groups incorporated in the polymer main chain. In these experiments in the solid state, it can be shown that the recombination involves always two successive steps: a rapid step corresponding to cage recombination and a second slow step related to diffusion and segment mobility (Tg) of the polymer.
Pyrolysis‐gas chromatography of polymers obtained by Friedel‐Crafts reactions of poly(vinyl chloride) with aromatic compounds
Authors: Cascaval C. N. , Schneider I. A. , Poinescu I. C.
Published: April 2003

Pyrolysis, in combination with gas‐chromatography technique, was used in the determination of the structure and study of the thermal degradation mechanism of the condensation polymers obtained by Friedel‐Crafts reactions of poly(vinyl chloride) with benzene, toluene, and naphthalene. The separation of the pyrolysis products was made using a column packed with chromosorb W (80–100 mesh) coated with 15% silicone SE‐52. The identification of the pyrolysis products resulted as a consequence of the thermal decomposition of condensation polymers and their semiquantitative estimation led to the final conclusion that the initial normal chlorine substitution in the macromolecular chain of poly(vinyl chloride) is followed by an important intramolecular cyclization reaction yielding 1,3‐methyleneindan units.
Block and graft copolymers by selective cationic initiation. IV. Physical properties of bigraft copolymers
Authors: Kennedy Joseph P. , Vidal Alain
Published: April 2003

The physical properties of bigraft copolymers, i.e., Nordel‐g‐polystyrene‐g‐poly(α‐methylstyrene) and Nordel‐g‐polystyrene‐g‐polyisobutylene, have been studied in terms of stress strain behavior, glass transition temperature, dynamic mechanical data, intrinsic viscosity versus temperature profile and solubility properties. These products are thermoplastic elastomers and show the presence of incompatible domains. Tg and dynamic‐mechanical data indicate an aggregation of the polystyrene and poly(α‐methylstyrene) phases.
Gamma‐ray induced polymerization of styrene in the presence of methanol
Authors: Beach T. J. , Burns C. M. , Huang R. Y. M.
Published: April 2003

The kinetics and molecular weight distributions (MWD) of the gamma‐ray induced polymerization of styrene in methanol were studied at 35°C, at low conversions and over a dose rate range of 2.76 × 103 to 2.74 × 104 rad/hr. The data obtained at low initial methanol content agreed with previously obtained results and the MWD of the polystyrene formed yielded a single unimodal peak with M̄n in the range of 35,000–480,000. However, at high initial methanol content and low dose rates, at least three peaks were clearly discernible over wide molecular weight distributions. The existence of these peaks is related to the kinetic data and the formation of three distinguishable regions in the polymerization system.
Maleimide polymers. III. Color reactions and kinetics
Authors: Haas Howard C. , Moreau Robert D.
Published: April 2003

We have shown previously that the free‐radical polymerization kinetics of maleimide can be explained by a scheme for retarded polymerization. The steps involve tautomerization of a growing maleimidyl chain to succinimidyl, the retarded addition of maleimide to the latter, and termination solely by resonance‐stabilized succinimidyl radicals. Combination termination is preferred, since this yields a very stable N,N′‐bisuccinimidyl structure. Other authors also invoke tautomerization to succinimidyl radicals which they believe terminate by disproportionation with growing maleimidyl chains to generate polymer with unsaturated endgroups. Free‐radical‐initiated polymaleimides are colored in the presence of base. Our measurements of the absorbance of polymaleimides at 387 and 500 nm in the presence of excess strong organic base show there is essentially no dependence on molecular weight. This suggests that the chromophoric groups are intramolecular and that color does not arise from the ionization of allylic protons associated with terminal double bonds. The near‐ultraviolet spectra of polymaleimides in slightly acidic media contain absorption bands at about 288, 320, and 360 nm. The structural impurities that account for these bands cannot be terminal unsaturation. We propose that the origin of these bands is pyrrolinone type structures which are formed by a retarded polymerization step through succinimidyl oxygen.
Synthesis of polypyrimidoquinazolinetetraones from N,N′‐bis(mesyloxy)pyromellitimide and aromatic diamines
Authors: Imai Yoshio , Ueda Mitsuru , Ishimori Motokazu
Published: April 2003

A novel class of polypyrimidoquinazolinetetraones was synthesized by the polymerization of N,N′‐bis(mesyloxy)pyromellitimide with aromatic diamines in N‐methyl‐2‐pyrrolidone in the presence of triethylamine as an acid acceptor. The polymerization proceeded probably through the formation of ring‐opened adducts, followed by elimination and rearrangement yielding polyamide‐isocyanates, which in turn were cyclized to give polypyrimidoquinazolinetetraones. These polymers, which were soluble in strong acids, had inherent viscosities in the range of 0.17–0.27. Thermogravimetric analyses indicated that they began to decompose at around 450°C in air.
Polymerization of coordinated monomers VII. A kinetic study on the alternating copolymerization of methyl methacrylate with styrene using stannic chloride
Authors: Hirai Hidefumi , Komiyama Makoto
Published: April 2003

The alternating copolymerization of methyl methacrylate with styrene in the presence of stannic chloride at −50°C in toluene was kinetically investigated both under photoirradiation and with the tri‐n‐butylboron‐benzoyl peroxide initiator. The concentrations of the binary and ternary molecular complexes in the copolymerization solution were estimated by use of the equilibrium constants. The rates are found to be proportional to the 1.5th and 1.0th orders of the concentration of the ternary molecular complex composed of stannic chloride, methyl methacrylate, and styrene, under photoirradiation and with initiator, respectively. The conversion increases proportionally with the polymerization time, while the degree of polymerization is constant irrespective of the time. The rates depend linearly upon the square root of the intensity of the incident light and upon the concentration of tri‐n‐butylboron, respectively. The alternating copolymerization is confirmed experimentally to precede the homopolymerization of the monomer charged in large excess both under photoirradiation and with initiator. The kinetic results indicate consistently that the alternating copolymerization proceeds through the homopolymerization of the ternary molecular complex in the steady state with a bimolecular termination. Both the conventional radical mechanism and the double complex mechanism are unsuitable for the present alternating copolymerization.
Coupling reaction of poly(α‐methylstyryl) anion with (MMA–α‐methylstyrene) block copolymer
Authors: Ishizu Koji , Fukutomi Takashi , Kakurai Toshio
Published: April 2003

(MMA–α‐methylstyrene)block copolymer was reacted with poly(α‐methylstyryl)anion at −78°C in a mixture of good tetrahydrofuran (THF) and poor methylcyclohexane solvents. The reaction conditions were chosen so as to produce graft copolymers made up of a backbone (AB‐type block copolymer) and a single branched chain (1:2 graft copolymer). Gel permeation chromatograph (GPC), osmotic pressure measurement, and elemental analysis were used for the characterization of 1:2 graft copolymer. It appeared that poly(α‐methylstyryl)anion reacted with the end pendant groups located farthest away from the branched point of AB‐type block copolymer, when the dimensions of AB‐type block copolymer molecule are small.
Emulsion polymerization of tetrafluoroethylene and isobutylene
Authors: Coker James N.
Published: April 2003

Interpolymers of tetrafluoroethylene and isobutylene containing approximately equimolar amounts of each monomer have been prepared by emulsion polymerization. Also prepared were compositions containing small amounts of other monomers such as acrylic acid. The characterization of these products is discussed, as is the preparation of both “ionomer” and iminated derivatives of the carboxylated terpolymers.
Molecular weight distribution and stereoregularity of polypropylenes produced with VCl4–AlEt2Cl catalyst
Authors: Doi Yoshiharu , Kinoshita Jiro , Morinaga Akio , Keii Tominaga
Published: April 2003

Dependences of the molecular weight distribution and stereochemical regulation of the polypropylenes produced with VCl4–AlEt2Cl catalyst on the polymerization temperature were examined. The molecular weight distributions of the polymers obtained at temperatures below −40°C were unimodal and narrow (Mw/Mn ≤ 2). The molecular weight distributions obtained at higher temperatures (above −21°C) were bimodal with one narrow distribution and one wide one (Mw/Mn > 2), and the polymer fraction of the wide distribution increased with the polymerization temperature. The fractional amount of (CH2)2 groups in the polymers, which corresponds to tail‐to‐tail linkage of two propylene units, increased to a maximum at −21°C followed by a gradual decrease with the polymerization temperature. The production of isotactic polymers was confirmed at temperatures above −21°C. From these data, it is concluded that only the homogeneous form of the catalyst system is responsible for the polymerization at temperatures below about −21°C while the heterogeneous form appears and catalyzes the polymerization together with the homogeneous one at temperatures above −21°C.
Equilibrium anionic polymerization of β‐methoxypropionaldehyde
Authors: Hashimoto Kazuhiko , Sumitomo Hiroshi , Ohsawa Shinji
Published: April 2003

Anionic polymerization of β‐methoxypropionaldehyde (MPA) was carried out in tetrahydrofuran (THF) by using benzophenone–monolithium complex as an initiator. An equilibrium between polymerization and depolymerization was observed at a temperature range of −90 to −70°C. From the temperature dependence of the equilibrium monomer concentration, thermodynamic parameters for the polymerization of MPA in THF were evaluated as follows: ΔHss = −4.8 ± 0.2 kcal/mole, ΔHSS = −22.4 ± 1.3 cal/mole‐deg, and (Tc)ss = −59°C. The thermodynamic change upon the conversion of liquid monomer to condensed polymer was computed from both the partial mixing energy of MPA with THF and the linear relationship between the equilibrium volume fraction of MPA monomer and that of the resulting polymer: ΔH1c = −4.7 ± 0.2 kcal/mole, ΔS1c = −19.5 ± 1.3 cal/mole‐deg, and (Tc)1c = −35°C.
Alternating copolymerization of styrene and methyl α‐chloroacrylate with diethylaluminum chloride
Authors: Hirabayashi Tadamichi , Yokota Kenji
Published: April 2003

The alternating copolymerization of styrene and methyl α‐chloroacrylate (MCA) with diethylaluminum chloride (Et2AlCl) in benzene at 0°C has been investigated. The copolymer has an equimolar composition irrespective of the feed monomer composition, the copolymer yield and the amount of Et2AlCl used. The copolymerization proceeds first very rapidly and then rather slowly after attaining a certain yield which varies proportionally to the amount of Et2AlCl used. A maximum copolymer yield is observed at about 60% MCA feed composition. The 1H‐NMR analyses of dyad, triad, and pentad of the alternating deuterated α‐d‐St‐MCA copolymer indicate that the configuration of this copolymer can be explained by a single parameter, coisotacticity σ(σ = 0.69). A favorable mechanism of the alternating propagation as well as of the stereoregularity control is discussed.
Sequence distribution of 1,4 and 3,4 units in polyisoprenes
Authors: Tanaka Yasuyuki , Sato Hisaya , Ogura Atsuko , Nagoya Ichiro
Published: April 2003

The 13C‐NMR spectra of hydrogenated polyisoprenes were investigated. Polyisoprenes containing various ratios of 1,4 and 3,4 units were prepared with n‐BuLi/Et2O and were hydrogenated by using p‐toluenesulfonylhydrazide. 13C‐NMR signals of the hydrogenated polymers were assigned for the triad sequences
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arising respectively from the 1, 4 and 3, 4 units of polyisoprenes. On the basis of these assignments it was confirmed that 1,4 and 3,4 units were randomly distributed in the polyisoprenes prepared with n‐BuLi and that these polymers did not contain appreciable amounts of head‐to‐head or tail‐to‐tail 1,4 linkages.
Monomer sequence distribution in α‐methylstyrene–methacrylonitrile copolymer
Authors: Kenney James F.
Published: April 2003

The sequence distributions of α‐methylstyrene‐methacrylonitrile copolymers have been determined quantitatively as a function of monomer feed composition and conversion at 60°C by use of the run‐number concept. The azeotropic copolymer was found to be highly alternating. For this copolymer the data showed that 83% of the diad placements took the form of an AMS unit followed by a MAN unit, or vice versa. The triad sequence in which an AMS unit is centered between two MAN units was 92%. It was found that the AMS‐AMS diad sequence is only 2%, and there were no AMS‐AMS‐AMS triad sequences in the copolymer. The sequence distributions were correlated with Izod impact strength and heat‐deflection temperature properties.
Homogeneous polyblend of poly(vinyl chloride) with α‐methylstyrene–methacrylonitrile–ethyl acrylate terpolymer
Authors: Kenney James F.
Published: April 2003

Blends of poly(vinyl chloride) (PVC) and α‐methylstyrene–methacrylonitrile–ethyl acrylate (AMS‐MAN‐EA) terpolymer have been prepared and properties studied. The polyblends are unusual inasmuch as they are transparent and possess a single glass transition; therefore, they are homogeneous. The single Tg suggests a single‐phase system. The polyblends exhibit rarely observed polymer–polymer compatibility.
Chemorheology of linear polymers
Authors: Murakami Kenkichi , Nakanishi Hiromasa
Published: April 2003

The structural changes brought about by chemical reactions are reflected in the viscoelastic behavior of polymers. Viscoelastic behavior induced by such chemical reactions is called chemorheology. This phenomenon is not readily observed in linear polymers, because molecular flow by diffusion is generally much more rapid than relaxation or flow caused by chemical reaction. It has become possible, however, to treat chemorheology of linear polymers theoretically by taking such physical flow into consideration. The experimental results for linear polystyrene compared with the theoretical ones are described in this paper. Good agreement between theoretical results and experimental ones is obtained for monodisperse polystyrene with low concentration of accelerators.
Determination of molecular weight distribution of cellulose by conversion into tricarbanilate and fractionation
Authors: Daňhelka J. , Kössler I. , Boháčková V.
Published: April 2003

Two samples of cellulose (molecular weight 2.97 × 105 and 1.25 × 105) were transformed into carbanilates (CTC) which were then fractionated by the elution method at a constant composition of the acetone‐water elution mixture with the column temperature gradually increasing from −30°C to 30°C, and by the GPC method in acetone and tetrahydrofuran. Tetrahydrofuran appeared to be a more suitable solvent. The molecular weights of fractions obtained by the elution fractionation were determined by the light‐scattering method in tetrahydrofuran. The width of fractions was determined by the GPC method (average Mw/Mn = 1.37); the [η] values and the Mark‐Houwink constants (K = 5.3 × 10‐3, a = 0.84) for tetrahydrofuran at 25°C were determined. The calibration curve for the GP method was constructed by means of the fractions thus obtained; it was demonstrated that the universal calibration curve according to Benoit can also be used. It was demonstrated that the molecular weight distribution of cellulose can be conveniently determined by conversion into CTC followed either by the elution fractionation (for preparative purposes) or by fractionation by the GPC method (for analytical purposes).
Photopolymerization via the Paterno‐Büchi reaction. II. Reaction of aromatic diketones with furans
Authors: Andrews D. J. , Feast W. J.
Published: April 2003

Attempts to photopolymerize 1:1 mixtures of furan and aromatic diketones of the benzophenone type by irradiation of benzene solutions at 350 nm were unsuccessful. An alternative route via furan‐diketone 2:1 adducts was more successful but was complicated by the intervention of hydrogen abstraction reactions in competition with oxetane formation, leading to crosslinking and insolubilization in some cases.
Polyfluoreoethers from 1,1,5,5‐tetrahydryl‐F‐1,5‐pentanediol and polyfluoroaromatic and polyfluoroheteroaromatic compounds
Authors: Johncock Peter , Hewins Maurice A. H. , Cunliffe Anthony V.
Published: April 2003

The use of the Williamson reaction to prepare polyfluoroethers, [OArOCH2(CF2)3CH2]n from 1,1,5,5‐tetrahydryl‐F‐1,5‐pentanediol and polyfluoroaromatic and polyfluoroheteroaromatic compounds was investigated. Fluorine NMR spectroscopy was used to determine the structures of the resultant polymers. F‐Biphenyl and 1,5‐bis(F‐2‐pyridyloxy)‐1,1,5,5‐tetrahydryl‐F‐pentane (BPFP) afforded the polymers where Ar is 4,4′‐C6F4C6F4 and
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respectively. The polymer prepared from F‐pyridine differed from that obtained from BPFP in that it had an irregular structure and contained 2,4′‐ as well as 2,2′ ‐ and 4,4′‐linked rings. F‐Benzene, 4‐(1,1‐dihydryl‐F‐butoxy)‐F‐pyridine, and F‐pyrimidine each gave materials having copolymer structures. The inherent viscosities of the polymers depended on the polyfluorocyclic compound used and ranged from 0.05 to 0.2 dl/g. The heterocyclic polymers were elastomeric. The polymers from F‐pyridine and BPFP had the lowest glass transition temperatures (∼−10°C), and started to lose weight (by thermogravimetry) at ∼300°C in oxygen and at ∼350°C in nitrogen.
Effects of diethylzinc in alkyllithium‐initiated polymerizations
Authors: Hsieh H. L.
Published: April 2003

In an alkyllithium‐initiated polymerization of butadiene or styrene, dialkylzinc complexed with the initiator and effectively increased the initiation rate. This is particularly true with initiator of low solubility due to its very high state of aggregation. Dialkylzinc also complexes with the aggregated polymer‐lithium molecules to give a lower apparent solution viscosity. In the presence of a base such as tetrahydrofuran, diethylzinc served as chain‐transfer agent.
Reactivity changes during polyimide formation
Authors: Hodgkin J. H.
Published: April 2003

The raactivity changes which occur in diamine monomers during polymide formation were investigated. A series of aromatic diamines were reacted with three aromatic anhydrides (including 1,4,5,8‐naphthalene tetracarboxylic dianhydride) under different conditions and the products isolated and identified. There was a great range of reactivity changes depending on the conjugation between the two amino groups of the diamine monomer. For highly conjugated groups, imide formation at one group can prevent any reaction at the other, and hence polymer formation is curtailed.
Ferric oxide‐catalyzed polymerization of methyl methacrylate
Authors: Moustafa A. B. , Abd‐El‐Hakim A. A.
Published: April 2003

The polymerization of methyl methacrylate was carried out in water at various concentrations of sodium bisulfite, ferric oxide, and methyl methacrylate at 30, 40, and 50°C. The effect of ferric oxide on the rate of polymerization was studied at 50°C. Rates of polymerization increased in the presence of ferric oxide. For example, the rate of polymerization increased from 3.4 × 10−5 mole/l.‐sec to 11.8 × 10−5 mole/l.‐sec when the ferric oxide concentration was varied from 0 to 15 g/l. water. The molecular weight of the polymer decreased from an average of 1.4 × 106 in the absence of ferric oxide to 2.8 × 105 when the ferric oxide was present. The variation of molecular weight of the polymers with temperature and conversion was studied. At a fixed conversion of 80%, the average molecular weight decreased from 3.4 × 105 at 30°C to 2.2 × 105 at 50°C. The average molecular weight was also found to increase with increasing monomer and initiator concentrations. It increased from 8.1 × 104 to 5.3 × 105 and from 3.4 × 105 to 8.9 × 105 as the initiator and monomer concentrations increased from 0.01 to 0.05 mole/l. and from 0.235 to 0.705 mole/l., respectively. The apparent energy of activation for the polymerization was found to be 15.6 and 9.7 kcal/mole in absence and in presence of ferric oxide, respectively.
Poly(vinyl alcohol) hydrogels: Reinforcement of radiation‐crosslinked networks by crystallization
Authors: Peppas Nikolaos A. , Merrill Edward W.
Published: April 2003

Aqueous poly(vinyl alcohol) solutions were crosslinked via electron‐beam irradiation to form transparent hydrogels of varying crosslinking densities. Typical crosslinked hydrogels with Mc between 3500 and 8000 were weak, easily shattered, nonextensible materials with very low tensile moduli (up to 70 psi) and tensile strengths at break (less than 10 psi). Reinforcement by induction of partial crystallization was accomplished by a two‐stage drying process, consisting of a slow dehydration stage at room temperature and an annealing stage at elevated temperatures, which was mainly responsible for the introduction of the crystallites. The swollen hydrogels after the annealing process had crystallinities widely varying between 30 and 65% and polymer volume fractions between 30 and 60%, depending on the temperature‐time history of the specimen. These materials showed greatly improved mechanical properties (modulus, ultimate tensile strength, tear strength), as compared to the uncrystallized hydrogels.
Metalation of unsaturated polymers by using activated organolithium compounds and the formation of graft copolymers. II
Authors: Halasa A. F. , Mitchell G. B. , Stayer M. , Tate D. P. , Oberster A. E. , Koch R. W.
Published: April 2003

Polybutadiene was successfully metalated by use of tert‐butyllithium activated with alkoxides of Group I metals without chain degradation. The metalated polymer was grafted with styrene and 1,3‐butadiene to give novel graft copolymers of varying microstructure. This metalating system was found to be highly efficient; however, its catalyst effectiveness is less than that of organolithium‐TMEDA metalation agent.
Effect of evolved hydrogen fluoride on radiation‐induced crosslinking and dehydrofluorination of poly(vinylidene fluoride)
Authors: Makuuchi Keizo , Asano Masaharu , Abe Toshihiko
Published: April 2003

Poly(vinylidene fluoride) (PVdF) was irradiated by 60Co γ‐rays with and without potassium hydroxide (KOH) under vacum. KOH tablets were added to absorb completely hydrogen fluoride (HF) which is the main volatile product of radiolysis of PVdF in the irradiation cell. In the presence of HF, the rates of radiation‐induced crosslinking and dehydrofluorination of PVdF were lower than those in the absence of HF. The experimental results are discussed from the standpoint of stabilization of alkyl free radicals in PVdF by reaction with hydrogen fluoride.
Copolymerization of ethylene sulfide and carbon disulfide
Authors: Soga Kazuo , Imamura Hayao , Sato Masaru , Ikeda Sakuji
Published: April 2003

Ethylene sulfide was found to copolymerize with carbon disulfide to give poly(ethylene trithiocarbonate) in the presence of Hg(SC4H9)2, Zn(C2H5)2, or Cd(C2H5)2, which are well known as the effective catalysts for the coordinated anionic copolymerization of episulfides. The structure and the composition of the copolymer was determined by the infrared and NMR spectra. To establishe the mechanism of the copolymerization, the reaction of carbon disulfide and Hg(SC4H9)2, and also the ring‐opening polymerization of ethylene trithiocarbonate were examined. Carbon disulfide was found to insert easily into the metal‐sulfur bond of Hg(SC4H9)2 under the experimental conditions of the copolymerization. On the other hand, the ring‐opening polymerization of ethylene trithiocarbonate did not take place with these catalysts, occurring only with the use of sulfuric acid. From these results, the mechanism of the copolymerization was discussed.
Radical polymerization of butadiene‐1‐carboxylic acid
Authors: Bando Yoshihumi , Minoura Yuji
Published: April 2003

The homopolymerization and copolymerization of butadiene‐1‐carboxylic acid (Bu‐1‐Acid) (M1) were studied in tetrahydrofuran at 50°C with azobisisobutyronitrile as an initiator. The initial rate of polymerization was proportional to [AIBN]1/2 and [Bu‐1‐Acid]1. The overall activation energy for the polymerization was 22.87 kcal/mole. For copolymerization with styrene (M2) and acrylonitrile (M2), the monomer reactivity ratios r1, r2 were determined by the Fineman‐Ross method, as follows; r1 = 5.55, r2 = 0.08 (M2 = styrene); r1 = 11.0, r2 = 0.03 (M2 = acrylonitrile). Alfrey‐Price Q‐e values calculated from these values were 6.0 and +0.11, respectively. The Bu‐1‐Acid unit in the copolymer as well as the homopolymer was found from infrared and NMR spectral analyses to be composed of a trans‐1,4 bond. The hydrogen‐transfer polymerization of Bu‐1‐Acid leading to polyester was attempted with triphenylphosphine as initiator, but did not occur.
Effects of molecular weight distribution in drag reduction and shear degradation
Authors: Hunston Donald L.
Published: April 2003

A reduction of frictional drag in turbulent flow was obtained in benzene by using three monodisperse polystyrene samples having weight‐average molecular weights of 1.8, 4.1 and 7.1 × 106. By testing these polymers individually and in mixtures, data were obtained for samples with known molecular weight distributions. The drag reduction of these samples was studied as a function of polymer concentration and flow rate so that a generalized picture of the effects of polydispersity could be obtained. These results are used to help explain much of the behavior that was observed for polystyrene and other polymers. This includes the fact that the polystyrene samples exhibit a remarkably high resistance to the loss of drag reduction via degradation in turbulent flow. Such experiments indicate that drag reduction and degradation depend strongly on molecular weight distribution. Thus a molecular level interpretation of experimental results cannot be made unless the effects of the distribution are considered.
Polymerization of hexamethylcyclotrisiloxane with a biscatecholsiliconate. II. Kinetics of polymerization
Authors: Lee C. L. , Marko O. W. , Johannson O. K.
Published: April 2003

The kinetics of polymerization were investigated for the polymerization of hexamethylcyclotrisiloxane (D3) in toluene with methanol or water as an initiator, benzyltrimethylammonium bis(o‐phenylenedioxy)phenylsiliconate as a catalyst, and dimethyl sulfoxide (DMSO) as a promoter. The rate of initiation was found to be comparable with both water and methanol. Addition of catechol drastically reduces the rate of initiation. The rate of propagation was found to be dependent upon the catalyst, DMSO, catechol and the aging of the catalyst solution. Two types of functional groups were postulated to be present during the propagation reaction, i.e., SiOH (dormant form) and SiONR4 (living form). The former can be converted to the latter by R4NOH derived from hydrolysis of catalyst. A postulated mechanism of polymerization with biscatecholsiliconate is presented.
Short branching in poly(vinyl alcohol). II. NMR spectroscopy of model polymers of short‐branched poly(vinyl alcohol)
Authors: Nozakura Shun‐Ichi , Morishima Yotaro , Iimuro Hiroyuki , Irie Yoshio
Published: April 2003

In order to develop a method of measuring the amounts of short branches in PVA, an NMR study was made of a model poly(vinyl alcohol) having short branches, one or two monomer units in length. Detection and estimation of the short branches were shown to be possible by using the 13C‐NMR spectra of PVA and the 1H‐NMR of acetylated PVA. In the 19F‐NMR spectra of trifluoroacetylated model PVA, the resonance peaks of primary and tertiary alcohols in the branching structure were not well resolved from that of secondary alcohol of the main chain.
Active polycondensation of diethyl 2,3,4,5‐tetrahydroxyadipate with diamines
Authors: Ogata Naoya , Sanui Kohei , Hosoda Yoshikazu , Nakamura Hiroyuki
Published: April 2003

Polycondensation of diethyl 2,3,4,5‐tetrahydroxyadipate with various diamines was carried out in solutions under mild conditions. The polycondensation reaction occurred rapidly even at room temperature in polar solvents such as alcohols, and in aqueous solution a cyclic product was obtained instead of linear polymers although the reaction with diamines was completed within several minutes. Polymers obtained from diethyl 2,3,4,5‐tetrahydroxyadipate were a linear polyamide having pendant hydroxyl groups, which decomposed on heating at around 200°C. A solid‐phase polycondensation of the precursor polyamide yielded a high molecular weight polyamide.
High‐conversion polymerization. I. Theory and application to methyl methacrylate
Authors: Cardenas J. N. , O'Driscoll K. F.
Published: April 2003

The concept of polymer entanglements has been applied in conjunction with classical free‐radical kinetics to describe vinyl polymerizations carried to high conversion. A kinetic model has been developed on the assumption that two populations of radicals exist in a high‐conversion polymerization system: those radicals whose chain lengths are long enough to become entangled with neighboring molecules and have, therefore, a restricted mobility; and those shorter radicals whose mobilities are not strongly affected by diffusional effects. It has also been assumed that the kinetic rate constant for the termination step between entangled radicals is inversely proportional to the mean entanglement density. The model contains only two parameters in addition to the kinetic rate constants required to describe low‐conversion polymerizations. One of these parameters can be determined, at least in principle, from measurements of solution properties of the polymer‐monomer mixtures. The model so developed has been tested against experimental data obtained from the literature on the bulk polymerization of methyl methacrylate. The agreement between predicted and experimental monomer conversions and molecular weight averages is found to be satisfactory.
Polymerization of pyridazine and pyridazinone derivatives. XIV. Effects of solvent, concentration, and temperature on radical copolymerizability of 3(2‐methyl)6‐methylpyridazinone with styrene
Authors: Matsubara Yoshio , Yoshihara Masakuni , Maeshima Toshihisa
Published: April 2003

The free‐radical copolymerizability of 3(2‐methyl)6‐methylpyridazinone (I) with styrene (St)(M1) has been reinvestigated at varying reaction conditions (solvent, monomer concentration, and reaction temperature). The copolymerization rates in protic solvents were not proportional to the monomer concentration. The overall activation energies in protic solvents were much affected by the monomer concentration. The results might be ascribed to the viscosity effect on the termination reaction, because the protic solvent was found to interact with I through hydrogen bonding to form a 1:1 complex which changed the viscosity of the reaction mixture. The monomer reactivity ratios were strongly affected by the reaction conditions. This might be explained by taking account of the solvation to the carbonyl group of I in the transition state, because clear relationships were not obtained by plots of log 1/r1 against the values of both vCO and vCC stretching frequencies of I, but the values of both ΔΔH‡(ΔH‡11 − ΔH‡12) and ΔΔS‡(ΔS‡11 − ΔS‡12) decreased linearly with a decrease of the monomer concentration in order of benzene ∼ dimethylformamide < ethanol < phenol < acetic acid systems.
Role of polymer ligands in the oxygenation of metal chlorophyllins
Authors: Tsuchida Eishun , Shigehara Kiyotaka , Miyamoto Ken
Published: April 2003

In order to obtain information about the characteristics of polymer‐(metal chlorophyllins), their redox and oxygenation reactions were studied. Complexes composed of metal chlorophyllins (MChn) and partially quaternized poly(4‐vinylpyridine) (QPVP) exhibited an increased stability due to electrostatic interaction between polymer cation and carboxylate anions of side groups in the MChn. The reduction of these polymer complexes by S2O42‐ occurred easily with an decrease in their apparent reduction potentials. The resulting low‐valence complexes had an ability to absorb molecular oxygen. The oxygenation of these polymer complexes was not completely reversible; however the rate of the irreversible reoxidation was less by a factor of 1010 for the polymeric complex than that for the monomeric MChn‐pyridine complex. The stability of these oxygen complexes is discussed in relation to the hydrophobicity of QPVPs.
Interaction of poly(vinylpyrrolidone) with methyl orange and its homologs in aqueous solution over the temperature range 60–90°c
Authors: Takagishi Toru , Nakagami Kimio , Imajo Koichi , Kuroki Nobuhiko
Published: April 2003

The binding of methyl orange, ethyl orange, propyl orange, and butyl orange by poly(vinylpyrrolidone) has been examined by a technique of equilibrium dialysis over a high temperature range (60–90°C). The first binding constants and the thermodynamic parameters in the course of the binding were evaluated. The results obtained at these temperatures were compared to those at lower ones (5–35°C) described previously in order to estimate the contribution of hydrophobic bonds to the binding. It was found that at the 60–90°C range complex formation between the dye and the macromolecule is associated with an exothermic enthalpy change and a positive entropy change. The enthalpy and entropy changes of the binding are of the order of −4.5 kcal/mole and 6 eu, respectively, for each dye measured. Thus the binding is mainly enthalpy‐controlled. Furthermore the effect of the alkyl chain length of the dye on both the ΔH° and ΔS° values is not pronounced. Also temperature dependences of the ΔH° and ΔS° terms were not observed. All these observations in the higher temperature range can be explained as a result of the disruption of water structure in the binding environment and hence a decrease in hydrophobic bond formation between the dye and the polymer.
Graft copolymerization of styrene on rubber containing halogen by chromous acetate
Authors: Lee Munam , Nakamura Hironobu , Minoura Yuji
Published: April 2003

Graft copolymerization of styrene on rubber containing chlorine, e.g., chloroprene rubber (CR) and chlorosulfonated polyethylene (Hypalon), with chromous acetate (Cr2+) was carried out in DMF–THF mixed solvent at 50°C. From the kinetic study, the normal kinetic orders with respect to the concentration of initiator and monomer were obtained at low concentrations of CR, but the deviation from conventional first‐order to second‐order kinetics with respect to the monomer concentration was observed at high CR concentrations: Rp ∝ [CR]1/2 [Cr2+]1/2[styrene]1 (at low CR concentration); Rp ∝ [CR]1/2 [Cr2+]1/2[styrene]1 (at high CR concentration). This result was explained in terms of the high viscosity of the reaction medium due to the rubber contained in solution. An initiation site along the polymer chain was assumed from the graft copolymerization with three kinds of CR having different microstructures. The results of fractionation of obtained polymer showed that the graft efficiency was high but a large amount of gel was formed.
Photopolymerization of methyl methacrylate and some other vinyl monomers with the use of a pyridine–bromine charge‐transfer complex as photoinitiator
Authors: Ghosh Premamoy , Mitra Partha Sarathi
Published: April 2003

Polymerization of MMA was carried out under visible light (440 nm) with the use of pyridine–bromine (Py–Br2) charge‐transfer (CT) complex as the photoinitiator. Initiator exponent and intensity exponent were 0.5 and 0.43, respectively, and the monomer exponent was found to be dependent on the nature of the solvent or diluent used. The Polymerization was inhibited in the presence of hydroquinone, but oxygen had very little inhibitory effect. An average value of kp2/kt for this polymerization system was 1.19 × 10−2, and the activation energy of photopolymerization was 4.95 kcal/mole. Kinetic data and other evidence indicate that the overall polymerization takes place by a radical mechanism. With Py–Br2 complex as the photoinitiator, the order of polymerizability at 40°C was found to be MMA, EMA ≫ Sty, MA.
Photopolymerization of methyl methacrylate and other vinyl monomers with the use of N‐bromosuccinimide as photoinitiator
Authors: Ghosh Premamoy , Mitra Partha Sarathi
Published: April 2003

Polymerization of MMA was done in the presence of visible light (440 nm) with the use of N‐bromosuccinimide (NBS) as the photoinitiator. The initiator exponent and intensity exponent were 0.5, and the monomer exponent was found to be unity. The polymerization was inhibited in the presence of hydroquinone. The average kp2/kt for this photopolymerization system was found to be 0.296 × 10−2 and the activation energy of photopolymerization was 4.67 kcal/mole. Kinetic and other evidence indicate that the overall polymerization takes place by a radical mechanism. With NBS as the photoinitiator, the order of polymerizability at 40°C was MMA, EMA ≫ MA ≃ VA, and styrene could not be polymerized under similar conditions.
Aspects of plastics scintillators. I. Behavior of fluorescent molecules in polymerizing medium
Authors: Neilson R. D. M. , Soutar I. , Steedman W.
Published: April 2003

The interaction between a number of organic fluors and vinyltoluene during thermally induced polymerization has been investigated by using kinetic and fluorescence techniques. It has been confirmed that 2,5‐diphenyloxazole, bis‐2(5‐phenyloxazoyl)benzene and p‐terphenyl do not react in the polymerizing medium and are present in the final product as solute in a solid solution. However, 1,1′4,4′‐tetraphenyl‐1,3‐butadiene and 9‐methylanthrancene do react, via chain‐transfer steps. The diene is concentrated in the low molecular weight tail of a polymer of broad molecular weight distribution and can be removed by further fractionation. The anthrancene species undergoes structural rearrangement with accompanying loss of fluorescence activity during reaction with the growing polymer chains.
Étude des irregularités observées dans la polymérisation du (−) sulfure de propylene amorcée par le triethylaluminium et ses derivés
Authors: Dumas Philippe , Spassky Nicolas , Sigwalt Pierre
Published: April 2003

Polymerization of propylene sulfide by use of triethylaluminum derivatives as initiators leads to low molecular weight polymers with irregularities in the chain, e.g. head‐to‐head units and disulfide bonds. Abnormal chiroptical properties due to the presence of these linkages were observed on polymerizing a levorotatory enantiomer. The formation of irregularities may be explained by the simultaneous presence of anionic and cationic mechanism and gives polymers without irregularities.
Radiation copolymerization of vinylene carbonate with isobutyl vinyl ether
Authors: Schnautz N. G.
Published: April 2003

The radiation‐induced copolymerization of vinylene carbonate (M1) with isobutyl vinyl ether (M2) has been investigated over the temperature range of 40–80°C. The monomer reactivity ratios r1 and r2 were determined to be 0.118 and 0.148, respectively, and an activation energy of 7.6 kcal/mole (31.8 kJ/mole) was calculated for the copolymerization process.
Bimolecular reaction of 2,4,6‐tri‐tert‐butylphenoxyl with hydroperoxide group in a solid polymer matrix
Authors: Griva A. P. , Denisov E. T.
Published: April 2003

2,4,6‐Tri‐tert‐butylphenoxyl (TBP) is dissolved and reacted with hydroperoxide groups of polyethylene and polypropylene in the amorphous phase. The reaction is not limited by diffusion, and unlike the case in the liquid phase, the concentration of TBP is not zero at the end of the reaction time, even though hydroperoxide groups are in excess. The biomolecular rate constant is smaller in the solid than it is in the liquid phase and depends on molecular motion. A linear relationship between the rate constant and frequency of rotation of radicals in polymers is observed.
Glass transitions of polyolefins by inverse gas chromatography
Authors: Braun J.‐M. , Guillet J. E.
Published: April 2003

The glass transition temperatures of polypropylene, poly‐1‐butene, polyisobutylene, and an ethylene‐propylene (EP) copolymer have been determined by inverse gas chromatography. The results are consistent with those determined by other procedures. When applied to low‐, medium‐ and high‐density polyethylene, values of −35, −25, and −18°C, respectively, were obtained. Because of the fact that the chromatographic technique involves essentially a sensitive detection of free volume in a polymer, it is suggested that these values represent Tg if it is defined as an iso‐free volume state of the amorphous phase of the polyethylene.
Studies on propagating species in cationic polymerization of styrene derivatives by acetyl perchlorate or iodine. I. Bimodal molecular weight distribution of polymers produced by acetyl perchlorate or iodine
Authors: Higashimura Toshinobu , Kishiro Osamu , Takeda Takashi
Published: April 2003

To investigate the nature of the propagating species in cationic polymerization of para‐substituted styrenes, p‐chlorostyrene (pCIS), p‐methylstyrene (pMS), and p‐methoxystyrene (pMOS), were polymerized with acetyl perchlorate or iodine in various solvents at 0°C, and the molecular weight distribution (MWD) of the polymers was measured by means of gel‐permeation chromatography. When ClO4− was a counterion, poly(pCIS) having a bimodal MWD was produced, while polymers of pMOS and pMS possessed a unimodal MWD, regardless of the solvent polarity. When more nucleophilic I− (or I3−) was a counterion, however, polymers having a bimodal MWD were produced from pMOS and pMS. These results showed that either dissociated or nondissociated propagating species existed in the cationic polymerization of styrene derivatives with acetyl perchlorate or iodine, and that the type of MWD was strongly dependent on the stability of the growing cation and the nucleophilicity of the counterion.
Anionic polymerization of styrene in the presence of pyridine
Authors: Yagi Koji , Tsuyama Shigeo , Toda Fujio , Iwakura Yoshio
Published: April 2003

An interesting effect of pyridine on the anionic polymerization of styrene in THF is described. Pyridine forms a complex with living polystyrene and greatly slows the polymerization rate without changing the degree of polymerization. From kinetic and spectroscopic studies, it was clear that there exist two active species in this system and the complex between living polystyrene and pyridine was of the 1:1 type, which itself had a weak ability to grow. The formation constant of the complex K was found to be about 4 × 105 l./mole. The effect of substituted pyridine was also studied and the nature of the complex was discussed.
Electropolymerization of aminophthalic acids. II. Polymerization of 4‐(4′‐aminobenzamido)‐, 4‐(2′‐aminobenzoyl)‐, and 4‐(3′‐aminobenzoyl) phthalic acid
Authors: Phillips D. Colin , Alvino William M.
Published: April 2003

The electrochemical polymerization of the amino phthalic acid series has been extended to the following derivatives: 4‐(4′‐aminobenzamido), 4‐(2′‐aminobenzoyl), and 4‐(3′‐aminobenzoyl)phthalic acid. Reactions were performed in both dimethylacetamide and ethanol. Both systems produced a film deposit at the anode which was identified as the amide acid of the starting material. Conversion by heat to the imide produced a brittle coating. Inherent viscosity measurements indicate that only low molecular weight material was formed.