bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiation‐induced terpolymerization of methyl α,β,β‐trifluoroacrylate with tetrafluoroethylene and α‐olefin
Authors: Matsuda Osamu , Watanbe Terutaka , Tabata Yoneho , Machi Sueo 
Published: April 2003

AbstractRadiation‐induced terpolymerizations of methyl α,β,β‐trifluoroacrylate (MTFA) with tetrafluoroethylene (TFE) and α‐olefins, such as ethylene, propylene, and isobutylene, were carried out in bulk at 25°C for the purpose of controlling the content of ester group in the MTFA‐α‐olefin alternating copolymers. These monomers polymerized to form alternating terpolymers which contained 50 mole % α‐olefin in a wide range of monomer composition. The content of MTFA, namely, the ester group in polymer, can be varied without destruction of the alternating structures between fluoroolefins (MTFA, TFE) and α‐olefin by changing the MTFA/TFE ratio in the monomer mixture. The relative reactivities of MTFA and TFE in the terpolymerization were discussed according to kinetic treatments by free propagating and complex mechanisms. The relation between the MTFA/TFE ratio in the monomer mixture and that in terpolymer was explained favourbly by the complex mechanism. It was also concluded that the relative reactivity of MTFA is larger than that of TFE in the terpolymerizations.
Small‐angle x‐ray investigation of a densely packed micelle system in agave hybrid
Authors: Misra T. , Patel A. , Patnaik J. 
Published: April 2003

AbstractSmall‐angle x‐ray scattering methods were applied to calculate macromolecular parameters like specific inner surface (O/V), length of coherence (lc), and the percentage of air present in agave hybrid, treating it as a densely packed colloidal system belonging to a general micelle system. The parameters were equal to O/V = 8.50 × 10−6 Å−1, lc = 150 Å, and the percentage of air = 0.03. The Kratky camera with latest design was used for the experimental measurement. Because the sample agave ybrid is a natural fiber and a highly oriented system that is celluosic in character, the theories of Kratky and Porod have been used to evaluate these parameters.
Structure of aromatic polyimides
Authors: Kumar Devendra 
Published: April 2003

AbstractWith a view to understanding the structure of aromatic polyimide backbone, model compound N,N‐bis(4‐phenoxyphenyl)‐1,2:4,5‐benzenetetracarboxdiimide was synthesized by the condensation of pyromellitic dianhydride and 4‐aminodiphenyl ether in solvent N,N‐dimethylacetamide or N,N‐dimethylformamide. Various side products formed during the reaction were isolated and identified by spectroscopical methods. This study reveals that the polymer backbone contains nearly 85% imide rings. The uncyclizable residues in the backbone are those derived by the chemical interaction of polymerization solvent or by the modification of intermediate orthoamido acid. The uncyclizable nature of the latter was explained in mass and infrared (IR) spectral studies. The role of the dipolar solvent appears to be vital to imidization.
Organometallic polymers. VI. Anchoring of arenechromium carbonyl complexes to macroreticular polymers
Authors: Tatarsky David , Kohn David H. , Cais Michael 
Published: April 2003

AbstractThe phenanthrenechromium dicarbonyl moiety was anchored by a photosubstitution reaction onto commercial resins substituted by diphenylphosphine groups. From scanning electron microscope photographs it was found that, whereas the chloromethylation reaction proceeded homogeneously throughout the polymer beads, the phosphination and photochemical reactions behaved differently, depending on the macrostructure and the morphology of the polymer beads. Large pore size dimensions (1300 Å) allowed the reagents (phosphine and chromium complex) to react throughout the polymer beads, whereas small pore sizes (< 50 Å) permitted penetration of the reagent only to a limited extent.
The effect of tin stabilizers on the thermal degradation of poly(vinyl chloride)
Authors: Gupta V. P. , St. Pierre L. E. 
Published: April 2003

AbstractSimultaneous HCl evolution and spin‐generation measurements were made on poly(vinyl chloride) (PVC) samples containing stabilizers of the type Rx Sn Y4‐x. It was found that tetrabutyltin and tributyltin laurate were better stabilizers than dibutyltin dilaurate. On the basis of the results, a mechanism for the stabilization of PVC by this class of compounds is proposed.
Reaction of crotonaldehyde with various ethyl aluminum chlorides in methylene chloride. A 1H‐NMR study
Authors: Nixon Alan , Childs Ronald F. 
Published: April 2003

AbstractThe reactions of crotonaldehyde (CA) with ethyl aluminum chlorides have been examined using a titration technique at low temperature. The titrations were followed by 1H‐NMR spectroscopy. Evidence for complexes of the type (Et2AlCl)2CA and (Et2AlCl‐CA)2 has been obtained. Ethyl aluminum sesquichloride undergoes sequential addition of CA to the EtAlCl2 moiety, to the Et2AlCl moiety, and again to the EtAlCl2 moiety. Ethyl aluminum dichloride undergoes ligand redistribution, alternately disproportionating and reproportionating, the ultimate product being EtAlCl2‐CA2.
Metal complexes with ligand‐organic phosphites as polyolefin antioxidants. II. Kinetics and mechanism of synergism at oxidation inhibition by metal acetylacetonates and organic phosphites
Authors: Pobedimskii D. G. , Kirpichnikov P. A. 
Published: April 2003

AbstractThe widely known synergism of oxidation inhibitors with metals of transient valency is shown in the new process with organic phosphite participation. The effects of inadditive strengthening phosphite action by acetylacetonates of transient metals (Me) have been investigated in different oxidation systems (solid polymer, melt, and liquid phase). The kinetic interpretation of effects, their quantitative analysis, and mathematical modeling are given, and the general regularities governing the efficiency of Me + organic phosphite compositions in any oxidation mode in the presence of initiator and at polymer autoxidation are revealed.
Polymer effect in graft polymerizations of acrolein onto imidazole‐containing polymer
Authors: Morita Satoshi , Yamashita Natsuki , Maeshima Toshihisa 
Published: April 2003

AbstractThe graft polymerizations of acrolein (AL) onto an imidazole (Im)‐containing polymer, such as a homopolymer of 4(5)‐vinylimidazole (VIm) and several copolymers of VIm‐4‐vinylpyridine (VPy), VIm‐1‐vinyl‐2‐pyrrolidone (VPr), and VIm‐styrene (St), have been studied in ethanol at 0°C. The degree of polymerization (P̄n) of the resulting polyacrolein graft depended on the number of Im units in the Im‐containing polymer which produced a decrease in P̄n of grafted polyacrolein. The P̄n of the graft polyacrolein was determined to be in the range of 5‐23. The rate of polymerization (Rp) was expressed by Rp = k(PVIm) (AL)2. The graft polymerizability of the AL was influenced by the comonomer in the parent polymer, and was found to be in the order of VIm homopolymer > VIm‐VPr copolymer > VIm‐VPy copolymer > VIm‐St copolymer. Rp was affected by the functional group around the Im group in the Im‐containing polymer. These results were discussed by assuming the conformation of the parent polymer in ethanol.
Solid‐state polymerization of long‐chain vinyl compounds. III. Mechanism of γ‐ray‐initiated postpolymerization in layered structures of octadecyl methacrylate and acrylate
Authors: Shibasaki Yoshio 
Published: April 2003

AbstractThe mechanism and kinetics of the γ‐ray‐initiated postpolymerization of octadecyl methacrylate and acrylate in lamellar crystals were investigated by a simple model. This model assumes that the initiation points are distributed as in a checkerboard and that polymerization probability of the monomer molecules decreases conically around each initiation point. The two‐dimensional polymerization can be characterized in this cone model by two parameters, a and r; a represents the polymerizability of the monomer for a given condition, and r depends on the number of initiation points per unit area. G values for the initiation reaction of octadecyl methacrylate and acrylate were estimated as 0.8 and 1.6, respectively. The two‐dimensional postpolymerization of long‐chain compounds proceeds in two stages. The rate of polymerization is very high and zero order with respect to monomer concentration in the first stage. It is lower and obeys first‐order kinetics in the second stage. The rate constants of the zero‐and first‐order polymerizations were kp0 = 1.73 molecule sec‐1 and kp1 = 0.93 sec−1, respectively, for octadecyl acrylate at 20°C.
Catalytic effect of poly(4‐vinyl‐N‐alkylpyridinium) salts on the hydrolysis of ester‐ and amide‐containing indolyl groups
Authors: Ishiwatari Tsutomu , Okubo Tsuneo , Ise Norio 
Published: April 2003

AbstractAlkaline hydrolyses of p‐nitrophenyl‐3‐indoleacetate (p‐NPIA) and N‐(indole‐3‐acryloyl)imidazole (IAI) were studied in the presence of poly(4‐vinyl‐N‐propylpyridinium bromide) (C3PVP), poly(4‐vinyl‐N‐benzylpyridinium chloride) (BzPVP), and copolymers of 4‐vinyl‐N‐benzylpyridinium chloride and 4‐vinyl‐N‐cetylpyridinium bromide (C16BzPVP). The hydrolyses were enhanced by the addition of these cationic polyelectrolytes. The magnitudes of the enhancement were in the order C16BzPVP > BzPVP > C3PVP, which is explainable in terms of the hydrophobicity of the polymers. The result and activation parameters obtained indicated that the substrates bound to polymers were more reactive than free substrates. The association constants obtained from the kinetic measurements (K) increased in the order BzPVP < C3PVP < C16BzPVP, which may suggest an important contribution of charge transfer interaction, in addition to electrostatic and hydrophobic interactions, between the polymers and the substrates. The association constants between the polymers and IAI were also obtained independently from the spectrophotometric measurements (K*) with the charge transfer absorption bands. The lack of a satisfactory agreement between K and K* is discussed.
Polymers containing fluorinated ketone groups. III. Synthesis of styrene/p‐vinyltrifluoroacetophenone copolymers by modification of polystyrene and the copolymerization of monomers
Authors: Cheng C. H. , Pearce E. M. 
Published: April 2003

AbstractCopolymers of styrene/p‐vinyltrifluoroacetophenone were prepared by two different reaction routes: (1) modification of polystyrene with trifluoroacetyl chloride and (2) copolymerization of styrene and p‐vinyltrifluoroacetophenone (VTFA). There appears to be a limit to the modification method because only a maximum content of 14.5 mole % trifluoroacetyl functionality could be attached to the polymer before the onset of crosslinking. Differential scanning calorimetry (DSC) was used to determine their Tg's. In addition, the reactivity ratios of styrene and VTFA were investigated. The reactivity ratios and Q and e values were r1 = 0.30 ± 0.09 (styrene) and r2 = 1.3 ± 0.3 (VTFA); Q1 = 1.0 and e1 = −0.8 (styrene); Q2 = 0.44 and e2 = 1.93 (VTFA).
Polymers containing fluorinated ketone groups. IV. Syntheses and characterization of new fluorinated ketone‐containing polymer‐substituted polystyrenes
Authors: Cheng C. H. , Pearce E. M. 
Published: April 2003

AbstractA series of new fluorinated ketone‐containing polymers, poly(p‐vinyltrifluoroacetophenone) (PVTFA), poly(p‐vinyldifluoroacetophenone) (PVDFA), poly(p‐vinylphenylheptafluoropropyl ketone) (PVHFK), and poly(o‐and p‐vinylbenzyltrifluoromethyl ketone) (PVTFK), were prepared by the free radical polymerization of the corresponding monomers. The monomers, p‐vinyltrifluoroacetophenone (VTFA), p‐vinyldifluoroacetophenone (VDFA), p‐vinylphenylheptafluoropropyl ketone (VHFK), and o‐and p‐vinylbenzyltrifluoromethyl ketone (VTFK), were prepared by the reaction of Grignard reagent with the corresponding perfluoroacid or its lithium salt. Polymerization was a competitive side reaction during monomer preparation. Reduced side reaction and higher yields of monomer (based on the Grignard reagent) were obtained from the lithium salt of the perfluoroacid, compared with the perfluoroacid itself. These new substituted polystyrenes which contain fluorinated ketone functionality were characterized by their ability to (1) react with active hydrogen compounds such as alcohols or water; (2) have high glass transition temperatures and decreased solubility in nonpolar solvents (e. g., benzene) compared with polystyrene; and (3) be converted into other functional groups such as alcohols or acids by treatment with the appropriate chemical reagents. Beads of a styrene (ST) terpolymer with 2% divinylbenzene (DVB), which contained the CF3COCH2 function, were prepared by suspension polymerization of ST, VTFK, and DVB. The terpolymer, which contains 15‐17% mole (or 0.70–0.71 meg/g) of CF3COCH2 swollen with a solvent, were shown to chemisorb alcohols.
Polyimides from diisocyanates and dianhydride
Authors: Ghatge N. D. , Mulik U. P. 
Published: April 2003

AbstractPolyimides soluble in polar solvents such as dimethylacetamide (DMAC) and dimethylformamide (DMF) were synthesized by reacting 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) and three different diisocyanates with the following general structure:
magnified image
where R is ethyl, propyl, or phenyl. Thermal properties of these polymides have been compared with that obtained by reacting 2,2‐bis(4‐isocyanatophenyl)propane and BTDA.
Grafting onto wool. VIII. Graft copolymerization of methyl methacrylate (MMA) by use of Ce4+ ‐amine system as redox initiator
Authors: Misra B. N. , Mehta I. K. 
Published: April 2003

AbstractIn an attempt to determine the role of a variety of amines in ceric‐ion‐initiated grafting, poly‐(methyl methacrylate) was graft copolymerized onto Himachali wool in the presence of a variety of amines that included ammonia, diethylamine (DEA), dipropylamine (DPA), triethylamine (TEA), triethanol amine, and pyridine. All amines (with the exception of DEA) reduced the percent grafting. The reactivity of various amines toward graft copolymerization followed the order: DEA > DPA > NH3 > TEA > triethanol amine > Py. An explanation based on the basicity, nucleophilicity, and steric requirement of amines is given to explain the observed reactivity order shown by the various amines toward graft copolymerization.
Reactions of polystyryl anions with carbon dioxide and oxygen. Analysis of products by silica gel chromatography
Authors: Månsson Per 
Published: April 2003

AbstractPolystyryllithium was prepared by anionic polymerization. This “living polymer” and the polystyrylmagnesium bromide derived from it were treated with carbon dioxide (solid or gas). The highest yields of carboxylic acid were obtained when solid carbon dioxide was used with polystyryllithium or by treatment of polystyrylmagnesium bromide with gaseous carbon dioxide. The products from the reaction of polystyryllithium with oxygen were polymeric ketone X, the alcohols IXa and IXb, and coupling products (e. g., XI). The various functionalized and unfunctionalized polystyrene products were isolated by chromatography on silica gel and were characterized by gel permeation chromatography (GPC), thin layer chromatography (TLC), and high‐performance liquid chromatography (HPLC) in combination with chemical transformations.
Reactivity of 4‐halogeno 1‐vinyl naphthalenes in cationic polymerization
Authors: Cho Won Jei , Bunel Claude , Maréchal Ernest 
Published: April 2003

AbstractImproved methods for the synthesis of 4‐halogeno 1‐vinylnaphthalenes are proposed. Reactivity ratios are determined for the following systems: 4‐fluoro‐1‐vinyl naphthalene‐styrene, 4‐chloro‐1‐vinyl naphthalene‐styrene, and 4‐bromo‐1‐vinyl naphthalene‐styrene. The determinations are performed at various specific temperatures and the relative activation parameters are obtained. It appears that the reactivity of 1‐vinyl naphthalene is drastically decreased when substituted by a halogen. In the case of 1‐vinyl naphthalene the selection is enthalpically controlled.
Kinetics of polymerization of acrylonitrile initiated by the Mn3+‐thioacetamide redox system
Authors: Samal Rajani K. , Nayak Padma L. , Nayak Mohan C. , Dhal Akshaya K. 
Published: April 2003

AbstractKinetics of the polymerization of acrylonitrile has been investigated in aqueous sulfuric acid in a temperature range of 25–45°C. The rate of polymerization (Rp) and the rate of managanic ion disappearance, etc., have been measured. The effect of the various additives, such as water‐miscible organic solvents, neutral electrolytes, complexing agents, and surfactants, on the rate has been thoroughly studied. A mechanism that involves the initial complex formation between the thiol form of the thioamide and Mn3+, whose decomposition yields the initiating free radical with the polymer chain terminated by mutual combination of growing radicals, has been suggested.
Thermal degradation of poly(vinyl bromide), vinyl bromide‐methyl methacrylate copolymers, and poly(vinyl bromide)‐poly(methyl methacrylate) blends
Authors: McNeill I. C. , Straiton T. , Anderson P. 
Published: April 2003

AbstractDegradation behavior has been compared for PVB, five VB‐MMA copolymers which span the composition range, PMMA, and PVC by using thermogravimetry in dynamic nitrogen and thermal volatilization analysis (TVA) under vacuum for programmed heating at 10°C/min. Volatile products have been separated by subambient TVA and identified. PVB is substantially less stable than PVC but shows inmost respects analogous degradation behavior. The introduction of VB into the PMMA chain leads to intramolecular lactonization with release of methyl bromide at temperatures a little above 100°C; after this reaction is complete, however, the polymer is more stable toward volatilization than PMMA. Copolymers with moderate and high VB contents also lose hydrogen bromide. Carbon dioxide is a significant product at intermediate compositions. The variation of product distribution with copolymer composition is discussed in relation to the several reactions involved and comparisons are made with VC‐MMA copolymers. PVB‐PMMA blends snow some features of degradation behavior in common with the PVC‐PMMA system but also very important differences. The effect of PVB is only to stabilize the PMMA; the mechanism is discussed. The role of PVB as an additive and VB as a comonomer for fire‐retardant PMMA compositions is briefly considered in relation to earlier studies.
Model simulation studies of complex free radical reactions: The graft copolymerization of styrene and acrylonitrile onto ethylene‐propylene‐isopropylidendicyclopentadiene terpolymer
Authors: Faucitano A. , Atarot H. , Martinotti F. Faucitano , Comincioli V. , Cesca S. , Arrighetti S. 
Published: April 2003

AbstractA kinetic analysis without steady approximation of the graft copolymerization of styrene‐acrylonitrile onto ethylene‐ propylene‐isopropylidendicyclopentadiene terpolymer (EP‐IPDCP) is described. Some of the kinetic constants were experimentally determined. The grafting process is interpreted mainly in terms of the attack on EP‐IPDCP by benzoyloxy radicals; phenyl radicals play a minor negative role by enhancing the rate of homopolymerization. A major contribution to the grafting yield is made by the propagation steps in graft polymerization and by crossed termination between grafted and ungrafted chains; of minor importance are the cross terminations between ungrafted growing chains and rubber radicals. The ole played by the solvent (benzene) and by saturated and unsaturated units in the EP‐IPDCP chains is analyzed. Diffusion effects caused by the poor solvent compatibility of grafted and ungrafted chains were taken into account by allowing the termination and propagation rate constants to change in a controlled way during the reaction. The trapping of EP‐IPDCP units caused by the aggregation of polymer particles seems to be indispensable to explain the decreasing trend of the grafting efficiency curve. Other information of interest pertains to the distribution of initiating radicals among the various competing reactions in the process and to the data of concentrations versus reaction time for reactants, products, and free radical intermediates. The results of a sensitivity analysis and the rate constants used in the calculations are given.
Molecular defects of polyacrylonitrile formed in aqueous medium
Authors: Minagawa Masatomo 
Published: April 2003

AbstractThe various kinds of molecular defect that are related to the thermal property of polyacrylonitrile (PAN) are studied in detail in relation to the polymerization mechanism in an aqueous medium. The existence of two different kinds of polymer radical is pointed out and the significance of polarity of radical species is emphasized. It is shown that the structural irregularity along the main chain is surely present but has little effect on the thermal property of PAN. It is estimated that one of the most significant defects relating to the thermal property is the main‐chian type of branching the occurs predominantly in hydrogen on a polymer backbone. The relationship between activator (i.e., NaHSO3) incorporation and branch inhibition mechanisms is discussed. The optimum polymerization condition, under which the highest thermal quality of molecules is obtained, is found empirically within a limited experimental range, for an aqueous heterogeneous system.
Cationic polyelectrolytes. II. Amination of chloromethylated polystyrene with hydroxyalkylic secondary amines
Authors: Drăgan Stela , Petrartu I. , Dima M. 
Published: April 2003

AbstractThe reaction of chloromethylated polystyrene with methyl(2‐ hydroxyethyl)amine and butyle (2‐hydroxyethyl)amine was studied kinetically. The reaction of benzyl chloride with these amines was also investigated for comparison. N,N‐dimethylformamide and dioxane were used as solvents. The reactions of benzyl chloride with the two amines in these solvents took place according to normal kinetics of the second order. Reaction kinetics depend on the nature of the amine and solvent in Chloromethylated polystyrene reactions. In dioxane the self‐accelerating effect of the reaction for β ≃ 0.5 is apparent. Steric hindrance of the reaction, beginning with a conversion degree of about 75%, wss observed for butyl(2‐hydroxyethyl)amine in N,N‐dimethylformamide. This self‐accelerating effect is observed in dioxane at the same reaction degree. The activation energies and frequency factors were calculated for the amination of benzyl chloride and chloromethylated polystyrene with the two amines in N,N‐dimethylformamide and dioxane.