bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystallizable elastomers by chemical modification of transtactic polydiolefins. Hydrochlorination
Authors: Bruzzone Mario , Carbonaro Antonio 
Published: April 2003

AbstractSolutions of crystalline, high‐melting trans‐1,4 polybutadiene (trans‐PB), trans‐1,4 mix 1,2 butadiene‐piperylene copolymer (BPC, low piperylene content), and isotactic trans‐1,4 piperylene (trans‐PP) were partly hydrochlorinated under mild conditions with gaseous HCl. Glass transition and melting temperatures were strongly affected by the addition of HCl. Several hydrochlorinated trans‐PB and ‐BPC were semicrystalline or amorphous elastomers, susceptible to reversible crystallization when stretched. The straininduced crystallinity was similar to that shown by trans‐polybutadiene sequences, particularly in the form that is unstable in bulk at room temperature (form II). The addition of HCl to the asymmetric double bond in trans‐PP occurs in a stereoselective way, according to 13C‐NMR. under the experimental conditions of the present study the occurrence of side reactions was observed; these reactions decrease the polymer unsaturation to a lower level than that calculated by the amount of HCl added to the polymer.
Epoxy functional copolymers as biospecific adsorbents for purification of enzymes
Authors: Dhal Pradeep K. , Babu G. N. , Sudhakaran S. , Borkar P. S. 
Published: April 2003

AbstractThe affinity chromatographic characteristics of some chemically modified copolymers based on glycidyl methacrylate have been evaluated. The copolymers were modified by means of reaction of suitable ligands with epoxy groups. Purification of pencillin acylase was carried out using these matrices as the stationary phase in the chromatographic column. Effect of the nature of the ligands and pH on the binding and desorption efficiency of the enzyme was evaluated.
Polymeric nucleophiles and cosolvents. The reactivity of poly(ethylene glycol) and its derivatives with benzyl bromide under solvolytic conditions
Authors: McManus Samuel P. , Yorks Kathy , Harris J. Milton 
Published: April 2003

AbstractPseudo first‐order rate constants for the solvolytic displacement of benzyl bromide in 100% ethanol and in 80 and 60% aqueous ethanol (v/v) are reported. The effect of adding poly(ethylene glycol) (PEG) and PEG dithiols and diamines to the solvolytic solutions has been studied. The solvolytic rates are mildly retarded on adding PEG, MW 950, or PEG dimercaptoacetate, MW 548 or 748 (at a concentration of about 8% of the polymer) to reactions in absolute ethanol. In 80% ethanol, however, a rate acceleration by the polymers was observed, with the thiols exhibiting the largest effects. PEG di(3‐mercaptopropionate) reacts slightly faster than the PEG dimercaptoacetates, but liberated acid affects the former's reaction. Three molecular weights of primary diamines structurally derived from propylene oxide‐capped PEG were evaluated and found to increase solvolytic rates of benzyl bromide significantly. Kinetic evaluation and comparisons with reactions containing equivalent amine groups per gram in an appropriate model (ethanolamine) revealed that the polymer's amine groups are actively involved nucleophilically. Grunwald‐Winstein plots and second‐order rate constants revealed that the polymeric diamines caused the benzyl bromide to undergo polymer‐assisted displacement in all solvent compositions. Since it was noted that the second‐order rates increased as the PEG amine molecular weight increased, it appears that the PEG framework may be assisting the reaction.
The influence of power and substrate temperature on chemical composition, determined by ESCA, of the inductively coupled RF plasma polymerization of acrylonitrile
Authors: Munro H. S. , Grünwald H. 
Published: April 2003

AbstractThe influence of power and substrate temperature on the chemical composition of inductively coupled RF plasma‐polymerized films of acrylonitrile was monitored by ESCA. At a substrate temperature of 20°C a minimum in nitrogen content as a function of power was observed for films deposited in the coil region. A maximum was observed for a substrate temperature of 150°C. When power was increased from 1 to ∼50 W a linear increase in nitrogen content was observed in the tail region at both substrate temperatures. A step function observed in the C1s and N1s core‐level spectra is discussed in terms of extensive unsaturation being present in the films.
Sulfonated polystyrene ionomers prepared by emulsion copolymerization of styrene and sodium styrene sulfonate
Authors: Weiss R. A. , Turner S. R. , Lundberg R. D. 
Published: April 2003

AbstractSulfonated polystyrene (S–PS), which is of considerable scientific and technological interest, has been traditionally prepared by the sulfonation of preformed polystyrene. This report describes the preparation and properties of S–PS prepared by emulsion copolymerization of styrene and sodium styrene sulfonate. S–PS prepared by copolymerization gave solubility, solution behavior and thermal characteristics that are consistent with an ionomeric structure. The solubility characteristics indicated some chain‐to‐chain sulfonate heterogeneity. Thermal analysis studies indicated that the glass transition does not increase with increasing sulfonate content. This is contrary to what has been observed for S–PS prepared by sulfonation and suggests that the S–PS prepared by copolymerization is fundamentally different in structure than S–PS prepared by sulfonation of polystyrene.
The emulsion copolymerization of styrene and sodium styrene sulfonate
Authors: Turner S. Richard , Weiss R. A. , Lundberg Robert D. 
Published: April 2003

AbstractThe emulsion copolymerization of styrene and sodium styrene sulfonate has been shown to be a feasible preparative route to ionomeric sulfonated polystyrene. The properties of these copolymers are reported elsewhere. The copolymerization rate was found to be dramatically enhanced when compared to that for the emulsion copolymerization of styrene under identical conditions. This copolymerization was studied in detail and two mechanisms were proposed to account for these rate differences. An increase in the number of polymerizing particles in the copolymerization with consequent rate enhancement was substantiated by electron microscopy. However, the data indicate that the rate differences cannot be fully accounted for by this effect. In addition, a gel effect is proposed as a second contributor to the enhanced rate. This gel effect is believed to result from the intermolecular association of the incorporated metal sulfonate units in the growing polymer particles. When a third monomer that plasticizes the ionic interactions is used the polymerization rate decreases. This supports the gel effect hypothesis.
Comparisons of styrene ionomers prepared by sulfonating polystyrene and copolymerizing styrene with styrene sulfonate
Authors: Weiss R. A. , Lundberg R. D. , Turner S. R. 
Published: April 2003

AbstractAs part of a continuing study of ion‐containing polymers, a comparison has been made on styrene‐based sulfonate ionomers obtained by two different processes. Copolymers of styrene with sodium styrene sulfonate (SSS) have been compared with corresponding polymers obtained by the sulfonation/neutralization of preformed polystyrene (S–PS). The former system covered a range of sulfonate level from 1 to 30 mol %, while the latter ranged from about 1 to 7 mol %. The characterization of these materials has been conducted using solubility behavior, dilute solution viscometry, thermal mechanical analysis, density measurements, and water adsorption studies. At low (ca. 1%) levels the solubility behavior of the SSS copolymers and the sulfonated polystyrenes were similar. However, at higher sulfonate levels the solubility behavior in different solvents and the dilute solution viscometry were significantly different for the two systems. Similarly, thermal analysis studies (DSC) showed that the glass transition of the sulfonated polystyrene increased linearly with sulfonate level, while the Tg for the SSS copolymer increased modestly, up to about 7 mol % sulfonate content, and then remained constant. Significant differences in the softening behavior and water absorption characteristics were also observed for these two classes of ionomers. Although molecular weights and molecular weight distributions are not now available for these ionomers, the differences in their behavior does not appear to be due simply to differences in molecular weight. It is postulated that the differences in the copolymer and the S–PS ionomers may originate with differences in sulfonate distribution. It is suggested that the SSS monomer units are incorporated as blocks in the copolymer as opposed to a more random distribution in the S–PS ionomer. Indirect evidence in support of his argument is found, for example, in the case of the copolymer in the solubility behavior, the relative independence of Tg on sulfonate concentration and the apparent existence of a second, high temperature transition tentatively attributable to an ion‐rich phase. Additional studies are required to confirm this hypothesis.
Magnesium chloride supported high mileage catalyst for olefin polymerization. VI. Definitive evidence against diffusion limitation
Authors: Chien James C. W. , Kuo Chi‐I , Ang Tsunle 
Published: April 2003

AbstractThere has been continuing interest in the possible role of insoluble polymer products forming a barrier reducing rate of diffusion of monomer to the active site to cause decrease in rate of polymerization and broadening of molecular weight distribution. This possibility is more acute the higher the catalytic activity. We have now shown that diffusion limitation is unimportant for the MgCl2 support high activity Ziegler–Natta catalyst by comparing its polymerization of propylene to isotactic insoluble polypropylene and of decene‐1 to isotactic soluble polydecene. The rate constant of propagation is about eight times greater for propylene while the rate constants of termination, i.e, decay of Rp, are comparable for the two monomers.
13C‐NMR spectral studies on the distribution of substituents in water‐soluble cellulose acetate
Authors: Miyamoto Takeaki , Sato Yukiko , Shibata Toru , Tanahashi Mitsuhiko , Inagaki Hiroshi 
Published: April 2003

AbstractThe degree of substitution (DS) and distribution of O‐acetyl groups of water‐soluble cellulose acetate (CA) were investigated by 13C‐NMR. For this purpose, three different series of CA samples with low DS were prepared by respective homogeneous reaction, i.e., (1) deacetylation of cellulose triacetate (CTA) in acetic acid—water solution (D‐series), (2) reaction of CTA with hydrazine (H‐series), and (3) acetylation of cellulose with acetic anhydride in a 10% LiCl‐dimethylacetamide solution (A‐series). It was found that (i) water‐soluble CA can be obtained only from D‐series products, (ii) the DS value of water‐soluble CA ranges from 0.5 to 1.1, (iii) the D‐series products exhibit little difference between the relative DS values at C‐2, C‐3 and C‐6 hydroxyl groups, and (iv) the relative DS at C‐6 hydroxyl groups is very high compared to those at C‐2 and C‐3 hydroxyl groups in H‐ and A‐series products. Aqueous solution of water‐soluble CA (D‐series sample) showed no gel—sol transition, even when the temperature was raised to 95°C. X‐ray diffraction observations revealed that the water‐soluble D‐series samples were essentially noncrystalline, but the water‐insoluble A‐series samples were crystalline. It was also found that the relative ease of acetylation is C‐6 > C‐2 > C‐3.
Ring‐opening polymerization of 2‐azabicyclo‐[2,2,1]‐hept‐5‐en‐3‐one using metathesis catalysts
Authors: Cho Hyun‐Nam , Choi Sam‐Kwon 
Published: April 2003

AbstractThe ring‐opening polymerization of an unsaturated bicyclic lactam, 2‐azabicyclo‐[2,2,1]‐hept‐5‐en‐3‐one (ABHEO), was carried out using metathesis catalysts under various reaction conditions. It is observed that the best results (34% conversion and ηinh: 0.18 dL/g) were obtained when the mole ratios of ABHEO to WCl6 as a catalyst and WCl6 to AlEt3 as a cocatalyst were 200 and 4, respectively. The infrared (IR) and nuclear magnetic resonance (1H‐ and 13C‐NMR) spectra of the polymer obtained indicated that the ABHEO was transformed to the ring‐opened polymer, poly(2‐pyrrolidone‐3,5‐diylvinylene) [poly(ABHEO)]. The resulting polymer was amorphous as determined by DSC analysis, which showed only secondary transition at 100°C.
Inhibition of acrylic acid polymerization by phenothiazine and p‐methoxyphenol
Authors: Levy Leon B. 
Published: April 2003

AbstractThe major features of polymerization induction periods for acrylic acid inhibited with phenothiazine and p‐methoxyphenol have been characterized at 100°C, including duration of the induction periods, and rates of inhibitor disappearance, molecular oxygen absorption, and peroxide formation. Surprisingly, thermally produced radicals react more rapidly with phenothiazine than with oxygen since there is no detectable oxygen absorption or peroxide for mation during phenothiazine‐induced induction periods. Thus, phenothiazine has been used to estimate the thermal rate of radical formation. Phenothiazine's effectiveness as an inhibitor is not directly affected by oxygen, although it does undergo oxygen‐promoted, noninhibition‐related side reactions. p‐Methoxyphenol, on the other hand, depends entirely on the presence of oxygen to function as an inhibitor. Compared with equivalent concentrations of p‐methoxyphenol, induction periods obtained with phenothiazine are very long, and the rate of inhibitor disappearance is slower by at least an order of magnitude. The characteristics of p‐methoxyphenol inhibition reflect a greater radical flux deriving from the significant rates of oligomeric peroxide formation and decomposition which we measured during p‐methoxyphenol‐induced induction periods at 100°C. MEHQ is an effective inhibitor at ambient temperatures in part because of the greater stability of the peroxides at these lower temperatures.
The synthesis and some properties of nylon 4,T
Authors: Gaymans R. J. 
Published: April 2003

AbstractThe synthesis of nylon 4,T from tetramethylenediamine and a terephthalic acid derivative was studied in a two step‐process: prepolymerization, followed by postcondensation in the solid state (4 h, 290°C). The prepolymers were prepared by the nylon salt method, ester polymerization method, interfacial method, and a low temperature solution method. A maximum ηinh of 1.52 was obtained. From a solution in trifluoroacetic acid, films were cast and on these films we studied its IR spectrum, WAXS, and melting behavior with DSC. A boiled up sample had a double melting transition at 434 and 475°C and a ΔH0 of 130 J/g.
Synthesis of polyamides by direct polycondensation with (1,2‐benzisoxazol‐3‐yl) diphenyl phosphate as a new activating agent
Authors: Ueda Mitsuru , Oikawa Hideaki 
Published: April 2003

AbstractA new activating agent for amide condensations, (1,2‐benzisoxazol‐3‐yl) diphenyl phosphate (1), was readily prepared in high yield by the reaction of 1,2‐benzisoxazol‐3‐ol (2) with diphenyl phosphorochloridate (3) in the presence of triethylamine in benzene. The new activating agent 1 was found to be very useful for the preparation of amides from carboxylic acids and amines. The direct polycondensation of several dicarboxylic acids with aromatic diamines using the activating agent 1 in the presence of triethylamine proceeded slowly at room temperature to produce polyamides with inherent viscosities up to 1.2 dL g−1.
Polybismaleimide containing tetrakisphenoxycyclotriphosphazenes
Authors: Kumar Devendra 
Published: April 2003

AbstractA heat‐resistant polybismaleimide was obtained by the thermal polymerization of bis(maleimidophenoxy)‐ tetrakis(phenoxy)cyclotriphosphazene. The thermal stabilities of the polybismaleimide were evaluated in nitrogen and in air by thermogravimetric analysis. The polybismaleimide was stable to 340°C and has char yield of 70% at 800°C in nitrogen and of 60% at 700°C in air. The monomer bismaleimide was obtained by the reaction of bis(4‐aminophenoxy)tetrakis(phenoxy)cyclotriphosphazene with maleic anhydride. The diamine was synthesized by a stepwise reaction of hexachlorocyclotriphosphazene with phenol and 4‐nitrophenol to give bis(4‐nitrophenoxy)tetrakis(phenoxy)cyclotriphosphazene and reducing the nitro groups. The structure of the cyclotriphosphazenes were characterized using Fourier transform infrared (IR), proton nuclear magnetic resonance (1H‐NMR) spectroscopy, and elemental analysis.
Synthesis and characterization of the new thermosetting monomers and phthalocyanine polymers with ester—imide linkages
Authors: Achar B. N. , Fohlen G. M. , Parker J. A. 
Published: April 2003

AbstractThe study described here deals with the methods of synthesis of two new bisphthalonitrile derivatives with ester—imide linkages and their polymerization. Optimum conditions for the synthesis and characterization of the bisphthalic anhydrides, bisphthalonitriles, and polymers are developed using IR spectral, differential scanning calorimetric, dynamic thermogravimetric analytical, and mass spectral studies. These new polymers showed good thermal stability and chemical inertness. The polymers showed char yield of 50% at 800°C in nitrogen atmosphere. These thermosetting phthalocyanine polymers are expected to be useful in various applications such as the production of moulded articles and laminates.
The cationic polymerization and copolymerization of isopropenylmetallocene monomers
Authors: Gonsalves Kenneth , Zhan‐Ru Lin , Lenz Robert W. , Rausch Marvin D. 
Published: April 2003

AbstractThree types of isopropenylmetallocene monomers were synthesized and subjected to polymerization and copolymerization by cationic initiators; (1) isopropenylferrocene (IF); (2) (η5‐isopropenylcyclopentadienyl)dicarbonylnitrosylmolybdenum (IDM); and (3) 1,1′‐diisopropenylcyclopentadienylstannocene (DIS), and related derivatives of each. IF was synthesized by a three‐step procedure involving the acetylation of ferrocene, conversion of the latter to 2‐ferrocenyl‐2‐propanol, and dehydration of the carbinol. IF was homopolymerized under various cationic initiation conditions, but only low molecular weight homopolymers were obtained. Copolymerization of IF with styrene and with p‐methoxy‐α‐methylstyrene also gave only low molecular weight products. The formation of only low molecular weight polymers in all polymerization reactions is believed to result from the effect of the unusually high stability of ferrocenyl carbenium ions on its propagation reaction. The observed polymerization behavior of α‐trifluoromethylvinylferrocene is in accord with this conclusion. IDM and DIS did not form polymeric products under cationic conditions, although copolymers could be obtained for each of these monomers and styrene with a free radical polymerization initiator (AIBN).
Ethylene—polyethylene mixture: Saturated liquid densities and bubble pressures up to 26.1 MPa and 493.1 K
Authors: Rousseaux P. , Richon D. , Renon H. 
Published: April 2003

AbstractMeasurements of saturated liquid densities and ethylene solubilities in ethylene—polyethylene systems up to 26.1 MPa and 493.1 K were obtained using a new variable‐volume static cell after a careful investigation of the influence of inhibitors of polymerization of ethylene under experimental conditions.
Synthesis and characterization of soluble aromatic polyamides from 2,5‐bis(4‐aminophenyl)—3,4‐diphenylthiophene and aromatic diacid chlorides
Authors: Imai Yoshio , Maldar N. N. , Kakimoto Masa‐Aki 
Published: April 2003

AbstractNew soluble aromatic polyamides with inherent viscosities of 1.0–1.7 dL/g were prepared by the low temperature solution polycondensation of 2,5‐bis(4‐aminophenyl)—3,4‐diphenylthiophene, bis(4‐aminophenyl) ether, and aromatic diacid chlorides in N,N‐dimethylacetamide. The polyamides and copolyamides are generally soluble in amide‐type solvents. They have glass transition temperatures in the range of 280–325°C and showed no weight loss below 390°C on thermogravimetry curves in both air and nitrogen atmospheres.
Copolymers of 2‐hydroxyethyl methacrylate and alkyl methacrylates. I. Synthesis and characterization
Authors: Choudhary Manjeet S. , Varma Indra K. 
Published: April 2003

AbstractCopolymerization of 2‐hydroxyethyl methacrylate (HEMA) with ethyl methacrylate (EMA) and n‐butyl methacrylate (BMA) was carried out in bulk at 70°C ± 1°C using 0.2% benzoyl peroxide as initiator in nitrogen atmosphere. Number average molecular weight (Mn) of the copolymers was determined by dynamic osmometry. Intrinsic viscosity [η] of HEMA‐BMA copolymers was evaluated at 35°C in dimethyl formamide. These copolymers were also characterized by infrared spectroscopy and density measurements. Cohesive energy densities (CED) of these polymers were determined by observing their swelling behavior in different solvents. It was found that a decrease in alkyl methacrylate content resulted in an increase in the CED values of the copolymers.
Synthesis of polyamides from active N,N′‐diacylbis [1,2‐benzisothiazol‐3(2h)‐one]s and 4,4′‐oxydianiline under mild conditions
Authors: Ueda Mitsuru , Mochizuki Amane 
Published: April 2003

AbstractThe aminolysis of 3‐benzoyloxy‐1,2‐benzisothiazole and N‐benzoyl[1,2‐benzisothiazol‐3(2H)‐one] derived from 1,2‐benzisothiazol‐3‐ol was studied in model systems and was found to give good yields of N‐substituted benzamides at room temperature. Solution polycondensation of new bisamides, N,N′‐isophthaloyldi[1,2‐benzisothiazol‐3(2H)‐one], and N,N′‐adipoyldi[1,2‐benzisothiazol‐3(2H)‐one], proceeded slowly to give polyamides with moderate molecular weights. The chloroform–triethylamine · hydrochloride system was the best polycondensation medium compared with some polar aprotic solvents for the formation of higher‐molecular‐weight polyamides.
Kinetics and mechanism for the phase transfer catalyzed cycloaddition of dichlorocarbene to cis‐1,4‐polybutadiene
Authors: Huvard Gary S. , Nicholas Paul P. , Horne Samuel E. 
Published: April 2003

AbstractThe kinetics for the cycloaddition of dichlorocarbene to cis‐1,4‐polybutadiene (BR) have been examined for aqueous and solid sodium hydroxide–chloroform mixtures containing 350 molecular weight α‐methyl‐ω‐hydroxy‐poly(oxy‐1,2‐ethanediyl) (Carbowax 350) as a phase transfer catalyst. This study describes the influence of reaction variables on rate and the partitioning of dichlorocarbene between dichlorocyclopropanation and hydrolysis. The results are consistent with a kinetic model derived for the case where mass transfer is not rate limiting. However, this does not apply at high conversions where mass transfer control occurs due to large increases in viscosity. Higher BR concentrations can be achieved by replacing chloroform with methylene chloride containing stoichiometric amounts of chloroform. This mass action effect causes more favorable partitioning toward cyclopropanation; otherwise, chloroform and methylene chloride behave similarly as solvents. Water is an essential component in this reaction because it greatly increases the ability of the catalyst to extract sodium hydroxide into the organic phase.
Organogermane homopolymers and copolymers with organosilane
Authors: Trefonas P. , West R. 
Published: April 2003

AbstractThe first high molecular weight soluble, formable organogermane homopolymer (n‐Bu2Ge)n was synthesized by the sodium coupling of n‐Bu2GeCl2 in toluene. Soluble organogermane/organosilane copolymers [(X2Ge)x(YZSi)y]n were prepared by sodium coupling of X2GeCl2 and YZSiCl2 in different molar ratios (X = n‐bu, Ph; Y = n‐hexyl, cyclohexyl; Z = Me). Germanium‐containing polymers and copolymers with organosilanes are highly absorbing between 300–360 nm, with the absorption maxima dependent on the nature of the substituent and the ratio of X2Ge:YZSi in the polymer. These polymers are photoactive and display bleaching behavior with photoscission.