bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular weight distribution in emulsion polymerizations
Authors: Lichti Gottfried , Gilbert Robert G. , Napper Donald H.
Published: April 2003

A mathematical formulation is given which describes the evolution of the number distribution of the molecular weight (MWD) of linear polymer chains that grow in emulsion polymerization systems. The resulting set of coupled ordinary differential equations takes into account the microscopic events of free radical entry, exit, chain annihilation, bimolecular termination (by combination and disproportionation), and chain transfer in a mono‐ or polydisperse system. Simple analytic solutions are presented for systems in which the number of particles, as well as the average number of free radicals per particle, is constant and in which the rate coefficients are size independent. These solutions indicate that compartmentalization of the free radicals in the latex particles results in a significant increase in the polydispersity of the polymer produced by emulsion polymerization, compared with that in bulk systems. The theory shows that significant mechanistic information may be obtained from experimental MWDs and that, in principle, experimental conditions may be prescribed to grow a desired MWD. The MWDs are presented in a novel manner that facilitates the comparison of theory with experiment.
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

Radiation‐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

Small‐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

With 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

The 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

Simultaneous 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

The 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

The 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

The 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

The 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

Alkaline 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

Copolymers 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

A 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

Polyimides 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:
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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

In 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

Polystyryllithium 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

Improved 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

Kinetics 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

Degradation 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

A 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

The 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

The 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.
Studies of some new bioactive acrylic esters
Authors: Chengxun Lu , Xinde Feng , Chongqing Wang , Dechang Ll
Published: April 2003

Four typical bioactive esters of acrylic monomers, N‐p‐acryloxybenzoyloxysuccinimides, 3‐ac‐ryloxy‐4‐oxo‐3,4‐dihydro‐1,2,3‐benzotriazines, N‐acryloxy‐5‐norbornene‐2,3‐dicarboximides, and I‐p‐acryloxybenzoyloxybenzotriazoles, were Synthesized and polymerized as reactive polymers. Twelve new monomers were prepared by coupling acrylic acid, methacrylic acid, p‐acryloxybenzoic acid, or p‐methacryloxybenzoic acid with four N‐hydroxy compounds such as N‐hydroxysuccinimide (HOSu), 3‐hydroxy‐4‐oxo‐3,4‐dihydro‐1,2,3‐benzotriazine (HOObt), N‐hydroxy‐5‐norbornene‐2,3‐dicarboximide (HONB), and I ‐hydroxybenzotriazole (HOBT) in the presence of dicyclohexylcarbodimide. All monomers polymerized readily in solution with azobisisobutyronitrile (AIBN) as free radical initiator. The resulting reactive polymers with reactive OSu, OObt, ONB, or OBT group on the side chain are equally reactive toward n‐butylamine at room temperature in the formation of corresponding polyacrylamides. Reactive polymers were used to immobilizetrypsin. It has been found that poly(N‐p‐methacryloxybenzoyloxy‐5‐norbornene‐2,3‐dicarboximide)‐trypsin matrix had high activity around three times that of the poly(N‐methacryloxy‐5‐norbornene‐dicarboximide)‐trypsin matrix. It is proposed that this activity may be due to the presence of a long spacer arm with a hydrophobic and rigid benzene ring between the ligand and matrix. The reactive poly(N‐p‐methacryloxybenzoyloxysuccinimide‐p‐methacryloxybenzoic acid) copolymer was used to immobilize the serum protein. This immobilized protein was a hopeful bioactive solid immunoadsorbent.
Solid‐state polymerization of long‐chain vinyl compounds. IV. Effects of chain length on the polymorphic behavior and postpolymerization of n‐alkyl methacrylates
Authors: Shibasaki Yoshio , Fukuda Kiyoshige
Published: April 2003

Polymorphic behavior and γ‐ray‐initiated postpolymerization of the even‐numbered long‐chain Methacrylates (C18‐C12) have been investigated. Phase transition behaviors of octadecyl, hexadecyl, tetradecyl, and dodecyl methacrylates are
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respectively, which become simpler with shortening of the chain length. The methacrylate monomers with sufficiently long hydrocarbon chains, such as octadecyl and hexadecyl, can be polymerized rapidly in the α‐form crystal (hexagonal packing) by a fully two‐dimensional mechanism, whereas in the β‐form crystal (triclinic packing), polymerization can hardly occur. In the case of dodecyl methacrylate, however, an accelerated polymerization in the β form occurs after an induction period of several hours and the resultant polymer is gel‐like. This can be interpreted by the propagation reaction across the polymer chain already formed. It has been found that the solid‐state post‐polymerization of n‐alkyl methacrylates is affected by the chain length through the packing mode of the monomer molecules and also by the aggregation state of side chains in the resultant comblike polymer.
Kinetics of polymerization of acrylic acid initiated by Mn3+–isobutyric acid redox system. II
Authors: Elayaperumal P. , Balakrishnan T. , Santappa M. , Lenz R. W.
Published: April 2003

The kinetics of redox ‐initiated polymerization of acrylic acid (AA) by the systerm Mn3+‐isobutyric acid (IBA) in sulfuric acid was studied in the temperature range of 35–50°C. The overall rates of polymerization (Rp), disappearance of manganic ion (−Rm), and degree of polymerization (Xn), were measured with variation in [monomer], [Mn3+], [IBA], H+, μ, [Mn2+], and temperature. The polymerization is initiated by the organic free radical that develops from the Mn3+‐isobutyric acid oxidation reaction. Two types of termination reactions, one by the metal ion (Mn3+) and the other by the MN3+‐isobutyric acid complex are proposed to explain the kinetic results. The various rate parameters were evaluated an discussed.
Polymerization and copolymerization of 2‐phthalimidomethyl 1,3‐butadiene. I. Preliminary studies of free radical polymerization and polymerizations initiated by various transition metal allyl complexes
Authors: Borg‐Visse F. , Dawans F. , Maréchal E.
Published: April 2003

2‐Phthalimidomethyl 1,3‐butadiene was homopolymerized and copolymerized with butadiene by free radical initiators; r1 and r2 were close to 1. All the attempts to polymerize 2PMB anionically have been unsuccessful. Preliminary studies of various η3‐allylic catalysts showed that η3‐allyl M0(CO)3OOCCF3 initiates the polymerization of butadiene and is not sensitive to N‐methyl phthalimide (NMP); neither does it initiate the copolymerization of butadiene and 2PMB. On the other hand, a catalyst that results from the reaction of allyl trifluoroacetate with nickel tetracarbonyl is efficient for the copolymerization of butadiene and 2PMB. η3‐Allyl nickel trifluoroacetate was prepared in heptane or benzene and used in benzene or methylene chloride. In all cases it initiated the copolymerization of butadiene with 2PMB
Glass transitions of epoxide prepolymers
Authors: Aleman Jose V.
Published: April 2003

Glass transitions of four solid epoxide prepolymers are described. The rigidity of their molecular chains are measured. With them an equation is developed which relates the glass transition temperatures to the molecular parameters of these polymers.
Microstructural order in cotton fibers by relative availability of O(3)H: Never‐dried fibers
Authors: Rowland Stanley P. , Wade Clinton P.
Published: April 2003

Availabilities of O(3)H relative to O(2)H (that is, [O(3)H]a/[O(2)H]a) on accessible surfaces of microstructural units of cotton fibers were measured by chemical microstructural analysis (CMA). CMA involves a mild chemical reaction with N,N‐diethylaziridinium chloride, determination of substituent distribution for this product and a corresponding product from decrystallized cellulose, and simple computations. Measurements for fibers in commercial cotton fabric, for field‐dried fibers, and for never‐dried fibers are reported. The [O(3)H]a/[O(2)H]a, an inverse measure of intact O(3)H ·· O(5′) bonds, decreased in the stated order; thus, intact O(3)H ·· O(5′) hydrogen bonding increased in this same order. Results indicate a high degree of order in intramolecular bonding in the never‐dried fiber and an increasing disruption of this bonding as the never‐dried fiber is dried and processed.
Polymerization in lyotropic liquid crystals. I. Change of structure during polymerization
Authors: Thundathil Raju , Stoffer James O. , Friberg Stig E.
Published: April 2003

Polymerization was made at 60°C in a lyotropic liquid crystal of sodium undecenoate and water. The liquid crystalline structure prior to polymerization was identified by optical microscopy and low‐angle x‐ray diffraction as an array of hexagonal closely packed cylinders with the hydrophobic part of the soap in the center of the cylinders. During polymerization the structure became isotropic at 60°C. Cooling to 20°C transformed the structure to a lamellar liquid crystal–a reversible transition. The structure of the lamellar phase was interpreted as a polyethylene backbone from which deformed decanoate chains reached toward the aqueous layer. Molecular models showed the model to accept head‐tail, head‐head, and tail‐tail configurations in cis and trans conformations with the exception of the cis tail‐tail configuration.
Polymerization in water‐in‐oil microemulsion systems. I
Authors: Stoffer J. O. , Bone T.
Published: April 2003

Phase diagrams for monomer (methyl acrylate containing microemulsions) are shown and described. Polymerizations of a series of microemulsified monomer reveals the expected linear dependence of 1/DS vs. [S]/[M] for pentanol acting as a chain transfer agent and giving a value of 5.1 × 10−4 for Cs. No break in molecular weight behavior was shown as a result of micellization at higher water contents. A comparison of molecular weights obtained by various classical methods (solution, emulsion, bulk) are also given.
Pyrolysis mass spectrometry and gas chromatography of plasma‐polymerized benzene and xylene
Authors: Venugopalan M. , Lin I.‐Sioun , Grenda M. S.
Published: April 2003

Pyrolysis mass spectra and gas chromatograms of plasma‐polymerized benzene (PPB) and p‐xylene (PPX) have been studied. Both polymers gave mass spectra that indicated the presence of disubstitution in an aromatic ring and of product molecules, such as biphenyl and ethylbenzene, trapped in the polymer matrix. The PPB spectrum showed fragments originating from C6H4n structures and the PPX spectrum fragments originated from CH2C6H4CH2n structures. Both the pyrolysis mass spectrum and chromatogram contained peaks that distinguished PPX from commercial polystyrene samples. A chain mechanism which involves H abstraction reactions under plasma activation is proposed. The highly crosslinked structures of the polymers are attributed to the subsequent addition of free radicals to the double bonds of a fragmented chain formed as a result of the scission of the CC aromatic bond(s).
Functional polymers. VI. Preparation and polymerization of methyl 3‐vinylsalicylate, methyl 3‐vinylacetylsalicylate, 3‐vinylsalicylic acid, and 3‐vinylacetylsalicylic acid
Authors: Iwasaki M. , Tirrell D. , Vogl O.
Published: April 2003

The title compounds were synthesized and their homopolymerizations and copolymerizations with styrene and a number of acrylic monomers were investigated. Methyl 3‐vinylacetylsalicylate was prepared in a five‐step synthesis from 2‐ethylphenol in an overall yield of 40%. Methanolysis of this compound gave methyl 5‐vinylsalicylate in 63% yield. Hydrolysis of methyl 3‐vinylsalicylate gave a nearly quantitative yield of 3‐vinylsalicylic acid which could be acetylated to 3‐vinylacetylsalicyclic acid (3‐vinyl aspirin). 3‐Vinylsalicylic acid derivatives were readily homopolymerized and copolymerized with styrene, methyl methacrylate, and methacrylic acid, and 3‐vinylsalicyclic acid was copolymerized with a number of vinyl and acrylic monomers. Copolymer compositions were determined by examination of 1H‐NMR spectra.
The effect of solvents on the radiation‐induced polymerization of ethyl and isopropyl vinyl ethers
Authors: Hsieh W. C. , Kubota H. , Squire D. R. , Stannett V.
Published: April 2003

The radiation‐induced cationic polymerization of ethyl and isopropyl vinyl ethers was studied in a variety of solvents. The propagation rate constants were estimated and found to vary widely with the nature of the solvent. In particular, a good linear relationship existed between the logarithms of the rate constants and the reciprocal of the dielectric constants. The lowest rates were those of the highest dielectric constant solvents. These results have been interpreted in terms of the Laidler and Eyring theory of ion‐molecule reactions. Isopropyl vinyl ether polymerizes much faster than ethyl vinvl ether, although the rates approach the same value at infinite dielectric constant. In contrast, “free” carbenium ion polymerizations initiated by stable carbenium ion salts in methylene chloride solution had similar values for both monomers. A comparison is made between the rate constants obtained with both methods of initiation.
Cyclization and crosslinking of polybutadiene in solution by electron beam irradiation
Authors: Hayashi Kanae , Tachibana Michinori , Okamura Seizo
Published: April 2003

Effects of electron beam irradiation on liquid polybutadiene in n‐hexane solution were studied at −10°C. With irradiation, crosslinking of the polymer and loss of double bond by cyclization took place at the same time. These reactions were retarded by the addition of DPPH or triethylamine which indicated that both radical and cationic mechanisms contributed to this system.
Synthesis of polymer containing lipoic acid as a polymeric reagent for acyl transfer
Authors: Nambu Yoko , Endo Takeshi , Okawara Makoto
Published: April 2003

Lipoic acid was immobilized on crosslinked polystyrene beads to generate a polymeric reagent. The acyl transfer reaction of the p‐nitrobenzoyl group from the polymer‐bound lipoic acid to cyclohexylamine was investigated spectrophotometrically and was compared with a monomeric model compound. The acceleration effect of silver ion on the acyl transfer reaction also was studied.
Polymers containing crown ethers: Polyureas from diisocyanates and 1,10‐diaza‐18‐crown‐6
Authors: Mathias Lon J. , Al‐Jumah Kusay
Published: April 2003

A new class of polyureas are reported which contain a crown ether analog in the backbone. Synthesis involves condensation of 1,10‐diaza‐4,7,13,16‐tetraoxacyclooctadecane with either 2,4‐toluene diisocyanate or hexamethylene diisocyanate in dichloromethane. The former gives tough, flexible polymers and the latter tacky, hygroscopic products. The infrared (IR) and proton nuclear magnetic resonance (NMR) spectra of these materials are given along with those of the polyurea from piperazine and hexamethylene diisocyanate. The carbon NMR chemical shifts and spin‐lattice relaxation times are also reported. Comparison is made with monomer, other crown ethers, polyoxyethylene, and a model compound prepared from the diaza monomer and phenylisocyanate. The T1 values indicate a greater degree of backbone and macrocycle flexibility for the hexamethylene‐containing polyurea than for the toluene analog.
Kinetic studies of rigid copolymers containing 3,3′‐substituted biphenyls and vinylimidazole
Authors: Hayama Shigeru , Takeishi Makoto , Niino Shogo , Okamura Toshiaki
Published: April 2003

Kinetic studies were investigated with rigid copolymers composed of vinylimidazole (VIm) and 3,3′‐substituted biphenyls. For neutral substrates, two different kinetic figures were observed by the influence of 3,3′‐substituents. The second‐order rate constants kinetically determined were largely enhanced by the reduction of ethanol content less than 30 vol % in contrast to the rapid decrease in viscosities of catalyst solutions. A parameter concerning the polymer conformation and the effect of hydrophobic interaction was obtained using a relationship between the kinetic constants with ethanol content. Maximum kinetic effect of electrostatic interaction appeared at about 50 mole % VIm content by attracting cationic substrates towards the COO− group of the polymer catalyst. This maximum rate profile was nearly coincident with a curve derived by calculating the sequence distribution of the (VImCOOH) linkage unit.
Thermal properties of wholly aromatic polyamides
Authors: Chaudhuri Ajit K. , Min B. Y. , Pearce Eli M.
Published: April 2003

Various wholly aromatic polyamides based on m‐and p‐phenylene diamines and isophthaloyl and terephthaloyl chloride have been synthesized and their thermal properties and oxygen index values have been studied. The effect of different substituents on the aromatic ring of the diamine have been explored by comparing their differential thermal analysis (DTA) and thermogravimetric analysis (TGA) behavior, their relative char yields at 700°C, and their oxygen indices. The Cl, NO2, and OH substituted polyamides have been found to produce the highest char yields. The high char yields are probably associated with crosslinking occurring at high temperatures. Attempts at correlating char yield with oxygen index indicated enhancement for the chlorosubstituted aramids.
Ampholytic polystyrene ionomers from cationic–anionic monomer pairs
Authors: Salamone J. C. , Tsai C. C. , Olson A. P. , Watterson A. C.
Published: April 2003

The preparation of a new form of ionomer is described. This class of material is based on the polymerization of a neutral monomer with a small amount of a cationic–anionic monomer pair. The resulting ionomers are ampholytic in character and contain no inorganic ions. In this investigation, the polymerization of styrene with 3‐methacrylamidopropyldimethylammonium and trimethylammonium 2‐acrylamido‐2‐methylpropanesulfonate in a variety of solvents is described.
Magnetic circular dichroism studies of aromatic polymers
Authors: Kaye H. , Hwang J. S.
Published: April 2003

The magnetic circular dichroism (MCD) spectra of syndiotactic and isotactic polymers which contain aromatic chromophores have been found to be sensitive to configurational and conformational differences. For isotactic polymers it was determined that as the aromatic ring moved farther from the main chain the ration of B terms of the polymers to those of their model compounds reached a minimum but increased significantly when the aromatic ring was separated from the main chain by four atoms. This enhancement of MCD is believed to be caused by the alignment of the more flexible side chains which would allow the interaction of the aromatic rings with neighboring groups and could result in a favorable mixing of the ester electronic transition with the aromatic 1A1g−1B2u transition. This effect was not felt to any great extent by the syndiotactic polymers because the necessary nearest‐neighbor interaction was sterically unfavorable. The ratio of the B terms of isotactic poly(phenyl methacrylate) to its model compound decreased as the polymer coil expanded, whereas it increased for the syndiotactic polymer. This effect reflects the different changes that the side chain interaction and orientations undergo in these polymers during coil expansion. The MCD ratios for iso‐ and syndiotactic poly(phenylethyl methacrylate) were not so sensitive during coil expansion. The ratio of the dipole strengths of the polymers and model compounds paralleled the MCD results, but the ultraviolet (UV) technique was less sensitive than MCD to subtle conformational differences. Poly(benzyl methacrylate) and benzyl pivalate were unsuitable systems for studying the MCD effect because the B terms of these materials approached zero.
Polyenaminoesters from α,α′‐bis(carbomethoxy)diacetylbenzenes and phenylene diamines
Authors: Moore J. A. , Mitchell T. D.
Published: April 2003

Polyenaminoesters are prepared by condensation of α,α′‐bis(carbomethoxy)diacetylbenzenes with phenylene diamines in the presence of N,N‐dimethylaniline hydrochloride. Thermogravimetric analysis allowed the determination of the optimum temperature at which to conduct cyclization of the polymers to form thermally stable polypyridoquinolones. The structures of the polymers were assigned by spectroscopic comparisons with appropriate model compounds.
Polymer syntheses via aromatic nitro displacement reaction
Authors: Takekoshi T. , Wirth J. G. , Heath D. R. , Kochanowski J. E. , Manello J. S. , Webber M. J.
Published: April 2003

Nucleophilic displacement of activated aromatic nitro groups with aryloxy anion is a versatile and useful reaction for the synthesis of aromatic ethers. Preparation of various aromatic monomers and polymers containing ether linkages is described.
Configurational rules governing the stereochemical control of chiral initiators in ring‐opening polymerizations of heterocyclic monomers
Authors: Spassky Nicolas , Leborgne Alain , Momtaz Ardèchir , Sepulchre Maurice
Published: April 2003

Configuration rules were established for the polymerization of cyclic monomers with chiral initiators. The latter recognize in the monomer an asymmetric carbon of homochiral configuration. The chirality of the initiator is defined by the “local” asymmetry of the ligand and by the overall asymmetry of the particular arrangement of catalytic aggregates. Two types of process called “homosteric” and “antisteric,” which apply to the polymerization of resolvable monomers and achiral monomers of meso structure, are defined. These configurational rules have a general character and are verified in many examples of differently substituted three‐ or four‐membered cyclic monomers (oxiranes, thiiranes, β‐lactones). Stereoelective polymerization appears to be an original method for the determination of the absolute configuration of some monomers of unknown chirality.
Effect of metal oxides on the evolution of aromatic hydrocarbons in the thermal decomposition of PVC
Authors: Ballistreri Alberto , Foti Salvatore , Maravigna Pietro , Montaudo Giorgio , Scamporrino Emilio
Published: April 2003

The thermal decomposition of poly(vinyl chloride) (PVC) mixed with several metal oxides was investigated by direct pyrolysis in a mass spectrometer (MS) and flash pyrolysis–gas chromatography. Our results show that the thermal decomposition of PVC occurs in two stages. Unsubstituted aromatic hydrocarbons (benzene, naphthalene, and anthracene) are evolved mainly in the first stage, alkyl‐aromatics (e.g., toluene) in the second. Although the addition of some metal oxides results in an overall suppression of aromatic hydrocarbons, the unsubstituted aromatics are much more suppressed with respect to alkyl‐aromatics. Furthermore, the formation of ZnCl2 and SnCl4 was revealed by the mass spectra of PVC–metal oxide pyrolysates. This suggests that, at least in these two cases, metal chlorides are responsible for aromatic hydrocarbon suppression. With this information a detailed reaction mechanism could be formulated for the thermal degradation of PVC.
Some contributions to the characterization of active sites in Mg‐supported Ziegler–Natta catalysts
Authors: Simon A. , Gröbler A.
Published: April 2003

The contribution of different MgO supports to the coordination polymerization of ethylene was studied by x‐ray diffractometry and infrared (IR) and electron spin resonance (ESR) spectroscopy of the supports and their products after treatment with TiCl4. It was concluded that TiCl4 was bonded on the surface OH groups of MgO mainly in inactive form, whereas the majority of the active sites was associated with the coordinatively unsaturated O2− ions.
A microcalorimetric study of complex formation between alkaline sodium tartrate and iron(III)
Authors: Dale Bruce E. , Tsao George T.
Published: April 2003

The structure of the cellulose solvent ferric sodium tartrate (FeTNa) was studied using a sensitive adiabatic calorimeter. FeTNa was found to be a typical transition metal complex in which three tartrate ligands add in a stepwise fashion to iron. The structure of FeTNa first proposed by Franke is thus confirmed. The equilibrium constant for the addition of the third tartrate ligand to iron is approximately 100, a value typical of those for other cellulose‐dissolving metal complexes. There is no calorimetric evidence for addition of more than three tartrate molecules to iron. The increase in molar heats of reaction with increasing ionic strength is consistent with dilute electrolyte solution theory. Based on these data, the probable reaction between FeTNa and cellulose has been postulated.
Fillers in polypropylene. II
Authors: Hancock M. , Tremayne P. , Rosevear J.
Published: April 2003

Part I showed that significant differences exist between calcium carbonate and silicate minerals when incorporated into polypropylene (three grades). It showed further that an ultrafine calcium carbonate, when coated with stearic acid, gives significantly better impact properties to the composite than a coated ground whiting but with no significant effect on its tensile properties. This article examines the effect of particle size and surface coating of chalk‐based calcium carbonate on the physical properties of GWE 21 Propathene homopolymer. The effect of variation in filler level was also investigated.
Synthesis of novel poly(xylylenyl benzimidazole)s
Authors: Ibrahim A. Mahammad , Mahadevan V. , Srinavasan M.
Published: April 2003

Novel poly(xylylenyl benzimidazole)s (PXBI) with methyl substituents on the xylylene units were synthesized by high‐temperature polycondensation techniques. Two different tetraamine hydrochlorides were condensed independently with 2,5‐dimethyl‐1,4‐benzene diacetic acid and 2,4‐dimethyl‐1,5‐benzene diacetic acid in polyphosphoric acid (PPA) to yield different poly(xylylenyl benzimidazole)s. Their syntheses, characterization, and properties such as density, viscosity, solubility, crystallinity, and thermal stability were described. Two model benzimidazoles (MBI) were also synthesized from o‐phenylene diamine (OPDA) and the above two diacetic acids to confirm the formation of polymers from the tetraamines. The polymers thus obtained had high intrinsic viscosities in the range of 0.67‐0.94 dl/g and were stable up to 450°C.