bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copolymerization of vinyl acetate with a homologous series of vinyl esters: A comparative study of vinyl acetate–vinyl ester and ethylene–vinyl ester copolymerization
Authors: van der Meer R. , German A. L. 
Published: April 2003

AbstractThe effect of the alkyl group on the relative reactivity of a homologous series of vinyl esters (M2) has been studied with vinyl acetate (M1) as reference monomer andtert‐butyl alcohol as solvent at 62°C and 35 kg/cm2. The description of the relative reactivities of the vinyl esters toward the vinyl acetate (VAc) macroradical in terms of the Taft relation is analogous to our previous findings in a similar study with ethylene (Eth) as reference radical. This implies that chiefly polar factors affect the relative reactivity, whereas from vinyl pivalate (VPV) on steric hindrance impairs the addition rate. The constancy of ther2values, also found in the series with Eth (M1) as reference monomer (viz.,r2= 1.50), appears to exist in the present investigation (r2= 1.04) but does not hold for the VAc–VPV combination. This can be interpreted in terms of steric hindrance. A combination of kinetic results indicates sterically hindered additions in all those reactions in the system Eth–VAc–VPV that involve at least one VPV unit as macroradical or monomer (except for the addition of Eth to a VPV macroradical). The monomer reactivity ratios that pertain to the Eth–VAc–vinyl ester systems are discussed in terms of theQ–escheme and the product relation postulated by Ham. The Ham relation does not hold for the latter systems.
Grafting vinyl monomers onto wool fibers. III. Graft copolymerization of methyl methacrylate onto wool using hexavalent chromium ion
Authors: Nayak Padma L. , Lenka Subasini , Pati Nrusingha C. 
Published: April 2003

AbstractThe use of hexavalent chromium to initiate graft copolymerization of methyl methacrylate onto wool fibers has been investigated. The rate of grafting was determined by varying monomer, chromium(VI), temperature, acidity of the medium, nature of wool, reaction medium, and redox system. The graft yield increases with increasing monomer concentration up to 0.65M, and, with further increase of monomer the graft yield decreases. The graft yield increases with increasing chromium(VI) concentration. The grafting is considerably influenced by chemical modification of wool prior to grafting. The effect of certain inorganic salt and anionic surfactant on the rate of grafting has been investigated. The graft yield is influenced by thiourea concentration; it decreases with increasing thiourea concentration.
Studies of the polymerization of diallyl compounds. XXVIII. Copolymerization of monoallyl phthalate with allyl benzoate and diallyl phthalate
Authors: Imai Itsuro , Matsumoto Akira , Oiwa Masayoshi 
Published: April 2003

AbstractThe bulk copolymerizations of monoallyl phthalate (MAP) with allyl benzoate (ABz) and diallyl phthalate (DAP) were conducted in the presence of benzoyl peroxide as an initiator at 70°C; copolymers containing allyl alcohol unit were obtained. The copolymer composition was reasonably interpreted in terms of polymerization kinetics, including the partial elimination of phthalic anhydride (PhA) from the MAP growing chain end in its propagation reaction with another monomer. Kinetics of the copolymerization of DAP with MAP were also discussed in detail, and the gel point was additionally evaluated. DAP–MAP copolymer was homogeneously reacted with zinc acetate to produce the polymer gel carrying ionic crosslinkages.
Aromatic polyamides. V. A general synthesis of polyamides from aromatic diacids and aromatic diamines in sulfur trioxide
Authors: Silver Frank M. 
Published: April 2003

AbstractThe reaction of terephthalic acid (TA) and para‐phenylenediamine sulfate (PPD‐S) in sulfur trioxide to form anisotropic, sulfonated poly(p‐phenyleneterephthalamide) (SPT) dopes was reported in Part IV of this series. We have found now that the TA/PPD‐S polymerization is only one example of a more general polyamide condensation reaction of aromatic diamines and aromatic diacids. Sulfonation of the aromatic diamine ring during TA/PPD‐S polymerization in SO3 was a major side reaction. Sulfonation was reduced or eliminated by aromatic diamine ring substitution with unreactive substituents, particularly chlorine and fluorine. Polymerization of 2,3,5,6‐tetrafluoro‐phenylenediamine with TA in SO3 at 80°C (18% concentration) produced unsulfonated poly(tetrafluoro‐para‐phenyleneterephthalamide) (F‐PPT) with an inherent viscosity of 2.2. The halogenated, all‐para aromatic polymers formed highly anisotropic (liquid crystalline) dopes. Monomers that formed polymers in which the chain bond angle deviated from 180° (e.g., meta‐oriented monomers) yielded only isotropic polymer solutions. The mechanism and rate of diamine–diacid reactivity in SO3 was related to diamine basicity. Whereas the less basic aromatic diamines (as sulfates) polymerized with aromatic diacids in SO3, the more basic aliphatic diamines (as sulfates) would not. Aliphatic, cycloaliphatic, and aryl‐aliphatic diacids were degraded by or reacted with the solvent (SO3). Thermogravimetric analyses of F‐PPT and monosulfonated poly(chloro‐para‐phenyleneterephthalamide) at 20°C/min showed weight loss only above 380 and 370°C, respectively.
1H‐NMR study of polyisoprenes
Authors: Sato Hisaya , Tanaka Yasuyuki 
Published: April 2003

Abstract1H‐NMR spectra of polyisoprene were assigned using polymers of isoprene‐1,1,4,4‐d4, isoprene‐1,1,5,5,5‐d5, and isoprene‐4,4‐d2 polymerized with various catalysts. The methylene‐proton signal at 2.1 ppm in cis‐1,4 ‐ and trans‐1,4‐polyisoprenes was divided into H4‐ and H1‐proton signals; H4 resonated at 2.21 ppm in both cis‐1,4 and trans‐1,4 units whereas H1 resonated at 2.05, 2.21, and 2.15 ppm. Splitting due to the dyad sequences of 1,4 and 3,4 units was apparent. The methine‐proton (H3) in a 3,4 unit showed a broad peak centered around 1.5 ppm in C6D6. The overlapping of this signal with the methyl‐proton signals at 1.73 and 1.63 ppm resulted in some uncertainty in the determination of the microstructure of polyisoprene which contained a considerable amount of 3,4 unit.
Polysiloxane dizwitterionomers. II. Morphology
Authors: Graiver D. , Litt M. , Baer E. 
Published: April 2003

AbstractSmall‐angle x‐ray and electron microscopy were used to study the morphology of polysiloxane dizwitterionomers. As in other polyelectrolytes, the zwitterions aggregate into ionic domains. In this case the domains are lamellar in nature and are in parallel arrays. The distance between these ionic regions is inversely proportional to the dizwitterion concentration in the polymer; their thickness is independent of the ionic concentration and is about 7 Å.
Polysiloxane dizwitterionomers. IV. Mechanical and dielectric relaxations
Authors: Graiver D. , Litt M. , Baer E. 
Published: April 2003

AbstractThe relaxation behavior of a series of polysiloxane dizwitterionomers has been studied by using dynamic mechanical and dielectric spectroscopy. The temperature range was 100–375 K and the frequency was ca. 1 Hz in the mechanical measurements and 50 Hz–50 kHz in the dielectric measurements. Three relaxation regions, labeled αs, β, αz in order of increasing temperature, were observed. The βs relaxation was assigned to the nonionic portion of the siloxane chain and correlated with the glass transition of polydimethylsiloxane. The β and αz processes are ionic‐related relaxations; β probably originated from the motion of a chain segment carrying a dizwitterion, and αz, from the collapse of the organization in the ionic domains. Absorbed water exerts a profound influence on relaxation behavior–primarily on αz ionic relaxation and the relative rigidity of the samples. The water molecules solvate the ions and thus shift the αz relaxation to lower temperatures.Some aspects of the effect of thermal history on the microphase separation into domains have also been investigated. The results indicate that the organization of the zwitterions in the ionic domains is improved at slow cooling rates.
Polysiloxane dizwitterionomers. V. Microstructure and mechanical properties
Authors: Graiver D. , Litt M. , Baer E. 
Published: April 2003

AbstractThe mechanical properties of the polysiloxane dizwitterionomers change dramatically with a tenfold increase in the ionic content, from soft, weak materials to hard, strong rubbers. The effects of the zwitterion concentration and the unique morphology on the elastic modulus can be explained by treating this series of ionomers as composites. Macro‐ and microfibrillation were observed in 1‐ and 2‐mole % zwitterion samples before the ultimate break and are probably due to reorientation of the ionic domains parallel to the stress direction so that cracks could propagate in the direction of the stress.
Solid‐state synthesis of a ladder polymer
Authors: Yee K. C. 
Published: April 2003

AbstractSolid‐state synthesis of a cyclically bound ladder polymer from a cyclic tetradiyne (cyclodotriaconta‐1,3,9,11,17,19,25,27‐octayne) is described. Irradiation of the colorless, needlelike monomer crystals with interstitially incorporated chloroform with 50 Mrad of 60Co γ‐ray radiation results in red‐brown polymer fibers in nearly quantitative yield. Infrared, Raman, and x‐ray diffraction analyses of the polymer are consistent with polymerization by a 1,4‐addition reaction at each diacetylene linkage to produce four fully conjugated chains joined together in pairs by a total of four (CH2)4 interchain linkages per 4.8‐Å polymer repeat unit. Conformationally, it appears that the cyclic tetradiyne monomer polymerizes via a chair form. The results of the mechanical and thermal analyses indicate the presence of unreacted diacetylene functionality in the ladder polymer crystals.
Monomer‐isomerization polymerization. XX. Monomer‐isomerization polymerization of 2‐, 3‐, and 4‐octenes with Ziegler–Natta catalyst
Authors: Endo Kiyoshi , Nagahama Hiroharu , Otsu Takayuki 
Published: April 2003

AbstractA study of the monomer isomerization polymerization of 2‐, 3‐, and 4‐octenes has been made with TiCl3–(C2H5)3Al catalyst at 80°C in comparison with the ordinary polymerization of 1‐octene. It was found that all these octenes underwent monomer‐isomerization polymerization to give high‐molecular‐weight homopolymer consisting exclusively of the 1‐octene unit. The addition of an isomerization catalyst such as nickel acetylacetonate accelerated this polymerization. The rates of polymerization were found to decrease in the following order: 1‐octene > 2‐octene > 3‐octene > 4‐octene. These results indicate that the isomerization proceeded by a stepwise double‐bond migration. It was also found that the monomer‐isomerization copolymerization of 2‐octene and 2‐butene occurred under similar conditions and produced copolymers of both 1‐olefin units.
Preparation of polymers containing 1,4‐dihydronicotinamide structure and their use in the reduction of vicinal tricarbonyl compounds
Authors: Endo Takeshi , Okawara Makoto 
Published: April 2003

AbstractThe definite polymers containing 1,4‐dihydronicotinamide structure were prepared by reduction with sodium dithionite‐potassium carbonate in the presence of benzyltriethylammonium chloride. The reduction of vicinal tricarbonyl compounds such as alloxan and ninhydrin by polymers having the 1,4‐dihydronicotinamide moiety was performed to isolate the polymers' trapped radical anion of alloxan or ninhydrin.
Anionic polymerization and copolymerization of S‐methyl thiomethacrylate
Authors: Okamoto Yoshio , Toki Motoyuki , Yuki Heimei 
Published: April 2003

AbstractS‐Methyl thiomethacrylate (methyl thiolmethacrylate, MTMA) was polymerized with a variety of anionic initiators such as n‐BuLi, octylpotassium, PhMgBr, and Et2AlNPh2 in toluene and THF. Stereoregularity of the polymer (PMTMA) was determined from the 1H‐NMR spectrum of poly(methyl methacrylate), which had been derived from PMTMA, because the α‐methyl resonance in the 1H‐NMR spectrum of PMTMA was not satisfactorily solved owing to the overlap of pentad signals. The 13C‐NMR spectrum of PMTMA also showed the splitting due to pentad sequences. Stereoregularity of PMTMA was always low compared with that of poly(methyl methacrylate), which was prepared under the same reaction conditions. MTMA was much more reactive than methyl methacrylate and methacrylonitrile in the copolymerization with n‐BuLi in toluene and in THF at −78°C. The lower stereoregulation of the polymerization of MTMA and the higher reactivity of MTMA were mainly ascribed to the higher resonance effect of MTMA.
Polyaromatic ether‐ketone‐sulfones containing 1,3‐butadiene units
Authors: Sankaran V. , Marvel C. S. 
Published: April 2003

AbstractThe acid chloride of 1,4‐bis‐p‐carboxyphenyl‐1,3‐butadiene (XI) and isophthaloyl chloride (XIV) were polymerized with 4,4′‐diphenoxy‐diphenyl sulfone (XII) and diphenyl ether (XIII) in a Friedel‐Crafts type of polymerization. The polymers obtained, which contained 5–20 mole % of butadiene units, were insoluble in all solvents. The polyamides prepared from the acid chloride of 1,4‐bis‐p‐carboxyphenyl‐1,3‐butadiene (XI) and aromatic diamines were also insoluble in all solvents.
Radiation‐induced terpolymerization of tetrafluoroethylene with propylene and isobutylene in bulk
Authors: Kostov G. K. , Matsuda O. , Watanabe T. , Machi S. , Tabata Y. 
Published: April 2003

AbstractTerpolymerization of tetrafluoroethylene (TFE) with propylene (P) and isobutylene (iB) by γ radiation at temperatures of −78 to 40°C, a dose rate of 5 × 104−5 × 105 rad/hr, and an iB/P molar ratio of 40/10−5/45 in the monomer mixture was carried out. Alternating copolymers of TFE and α‐olefins, that is, P and iB, were formed at various monomer compositions. No crystalline structure was observed in the terpolymer obtained below an iB/P molar ratio of 15/35 in the monomer mixture but a partly crystalline order increased with the amounts of iB in terpolymer. The crystal lattice of the TFE–iB copolymer was affected by the introduction of P. The dose rate dependencies of the polymerization rate and inherent viscosity were 0.8 and −0.2, respectively. The activation energy of polymerization was 2.4 kcal/mole, and the relative reactivity ratio of iB and P for a TFE radical chain end was estimated as 4.50 by the treatment of the free propagating mechanism.
A two‐stage stress‐dependent creep mechanism in plasticized poly(vinyl chloride) (PVC)
Authors: Kamel R. , Najeeb E. , Badr Y. A. , Semary M. A. , Hadhoud M. A. 
Published: April 2003

AbstractThe temperature dependence of tensile creep of plasticized poly(vinyl chloride) (PVC) was tested under differently applied stresses. The steady creep rate showed two distinct stages, depending on stress and temperature. At relatively low stresses the activation energy (0.2 eV) which characterized the steady creep mechanism of stage I, showed no stress sensitivity. Under high stresses (stage II) the energy‐activating steady creep was of the order of 1 eV and increased excessively with increasing stress. The model for plastic flow of PVC suggested here assigns the extension of the twisted zigzag molecular conformation to creep in stage I. In stage II creep is controlled by the reorientation of molecular segments by rotation from initially random orientations in a direction parallel to the principal tensile axis. γ Irradiation of the samples before testing increased the steady creep rate and reduced the creep lifetime. This was attributed to chain scission and greater mobility of the molecular segments.
Application of environmental relaxation model to the transport behavior of glass‐forming melts
Authors: Islam N. , Kochi Ismail 
Published: April 2003

AbstractThe environmental relaxation model was applied successfully to explain the temperature dependence of viscosity, conductance, and the Walden product of molten Ca(NO3)2.3.91H2O + NiCl2 system in the non‐Arrhenius region. This model was applied to pure melts, binary molten salt systems with ideal solutions marked by the absence of complex ions, and systems in which octahedral or tetrahedral complexes are formed. The values of the glass transition temperature obtained from the free volume and environmental relaxation models are in good agreement. The values of apparent activation energies for viscous and conductance flows derived from these two models are also comparable.
Crosslinking and scission yields for polystyrene subjected to γ irradiation in vacuo
Authors: O'donnell J. H. , Rahman N. P. , Smith C. A. , Winzor D. J. 
Published: April 2003

AbstractMeasurements of molecular weight averages and distributions have been made on three samples of narrow molecular size distribution polystyrene with molecular weights from 100, 000 to 400, 000 subjected to 60Co γ irradiation in vacuo for various doses within the pregel region+ G(X), the radiation chemical yield of crosslinking, has been determined as 0.043 ± 0.002 and G(S)/G(X), the ratio of scission to crosslinking, as 0.02; no effect of molecular weight was observed. By comparison with previous experimental results for polystyrene irradiated in air it has been established unequivocally that an oxygen environment leads to enhanced scission at the expense of crosslinking. Literature values of G(X) and G(S)/G(X) are reviewed in the light of these results and explanations are offered to account for major discrepancies.
Polymerization of allyl esters of unsaturated acids. IV. Cyclopolymerization of diallyl maleate
Authors: Urushido Kunio , Matsumoto Akira , Oiwa Masayoshi 
Published: April 2003

AbstractRadical polymerization of diallyl maleate is kinetically discussed in terms of cyclopolymerization using 2,2′‐azobisisobutyronitrile as an initiator and benzene as a solvent at 60°C. Thus, the kinetic equations involving bicyclo‐intramolecular cyclization are derived by assuming steady‐state conditions for the different types of radicals, and various parameters involved in the equations are then estimated approximately from an extension of the corresponding model experimental results. The validity of these treatments is confirmed from the comparison with the experimental data including the relationships between the contents of the unreacted allylic and maleic double bonds and the monomer concentrations. In addition, the sequence distribution of the structural units of the polymer produced is discussed; for example, the content of the bicyclic structural units is estimated to be 47.2% at a 10% dilution of the pure monomer.
Kinetics of polymerization initiated by Mn3+–substrate redox system. I
Authors: Elayaperumal P. , Balakrishnan T. , Santappa M. , Lenz R. W. 
Published: April 2003

AbstractThe kinetics and mechanism of polymerization of acrylamide (AM) initiated by manganese (III) acetate (MTA)–diglycolic acid (DGA) redox system in aqueous sulfuric acid were studied in the temperature range 20‐35°C. The overall rates of polymerization and the disappearance of Mn3+ and the kinetic chain lengths of polyacrylamide were determined. The polymerization reaction is initiated by the organic free radical arising from the Mn3+–diglycolic acid reaction and the termination is by the metal ions. The rate of polymerization of acrylamide was found to be proportional to the first power of monomer and diglycolic acid and independent of manganese(III) acetate. The various rate parameters were evaluated.
Cellulose organic solutions: A nuclear magnetic resonance investigation
Authors: Gagnaire Didier , Mancier Daniel , Vincendon Marc 
Published: April 2003

AbstractFour solvents of cellulose have been studied by using 13C‐NMR spectroscopy. All these solvents, N‐methyl morpholine‐N‐oxide, methylamine, hydrazine, and paraformaldehyde (PF), contained dimethyl sulfoxide (DMSO) as a cosolvent. Oligomers of cellulose of DP = 10 soluble in hot DMSO have been used as model compounds. 13C chemical shifts and line shapes show that three of the mentioned solvents are “true solvents” of cellulose. On the other hand, dissolution of cellulose in DMSO‐PF system occurs by the formation of a statistical derivative of cellulose. Enriched 13C bacterial cellulose on C‐1 and C‐6 positions have been used to identify the 13C positions mainly in DMSO‐N‐methyl morpholine‐N‐oxide system. This solvent has been found to be degradative for the macromolecule when the solution is kept at 100°C over a long period. Viscosity measurements show a reduction of the molecular weight in these conditions. Polarimetry indicates that no glucose is present in solution and hence there is a statistical break of the chain. Enriched cellulose solution in DMSO–N‐methyl morpholine‐N‐oxide has been also used for relaxation time (T1) determination both of the solvent and of the enriched carbons of the polymer. Nuclear Overhauser enhancement (NOE) was found to be 1.8 for C‐1 and 2.1 for C‐6 showing that relaxation phenomenon is not purely dipolar. T1 values of 97 and 65 msec are found for C‐1 and C‐6 of cellulose, in good agreement with the values known for polysaccharides. Determination of T1 for the different carbon atoms of the solvent DMSO‐N‐methyl morpholine‐N‐oxide with and without cellulose shows a large reduction of T1 for N‐methyl morpholine‐N‐oxide molecule. This denotes a slower molecular motion of this molecule and a preferential interaction with the cellulose macromolecule.
Plasma polymerization. II. An ESCA investigation of polymers synthesized by excitation of inductively coupled RF plasma in perfluorobenzene and perfluorocyclohexane
Authors: Clark D. T. , Shuttleworth D. 
Published: April 2003

AbstractThe plasma polymers formed in glow and nonglow regions of an inductively coupled RF plasma with perfluorobenzene and perfluorocyclohexane are discussed as a function of operating conditions of the plasma by means of ESCA. The core levels of the plasma polymers are shown to be strikingly different but characteristic of a well‐defined but complex polymerization scheme. For the nonglow regions fluorine incorporation is shown to be greater than for polymers prepared in the glow regions and a preponderance of CF2 features is apparent. Perfluorobenzene deposits polymer faster than perfluorocyclohexane and changes in component composition of the C1s profile are studied as a function of operating conditions of the gas plasma.
Substituent effects in polymerization reactions in terms of generalized substituent constants F and R and generalized weighting factors f and r
Authors: Patnaik Lalit N. , Rout M. K. , Rout Anuradha , Rout Swoyam P. 
Published: April 2003

AbstractIn this investigation an approach to correlate the composite rate constants of some redox polymerization reactions [acrylonitrile‐Ce(IV)‐organic substrate] with a new type of multiparameter equation is described. The multiparameter equation is based on Swain and Lupton's F and R, the field and resonance components of the substituents, respectively, and the unique positional weighting factors f and r suggested by Williams and Norrington. The statistical parameters of the correlation involving the substituent constants (fF and rR) and the rate data have been found to be quite satisfactory, the average coefficient of determination being 0.91. The significance levels of the correlation also indicate that the present model is applicable to the kinetics of redox polymerization. The sign and magnitude of the reaction‐dependent regression constants α and β suggest that three different types of reaction mechanisms are operative for the substrates benzaldehyde, phenylthiourea, acetophenone, and toluene.