bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microstructure of polybutadiene catalyzed by alkali metal tert‐butoxides and n‐butylsodium. II.
Authors: Cheng Tai Chun , Halasa A. F. , Tate D. P. 
Published: April 2003

AbstractA polybutadiene of high molecular weight was prepared in hydrocarbon solvent by using n‐BuNa–tert‐BuOM (M = Li, K) as a polymerization initiator. The microstructure of this polymer varied from 35 to 76% of 1,2 content, depending on the type of modifiers. The kinetics of polymerization was not studied, primarily due to the heterogeneous nature of the catalyst. However, other variables, such as the catalyst concentration and temperature, have been studied. The results and mechanistic implications are discussed.
Aromatic polyethers, polysulfones, and polyketones as laminating resins
Authors: Verborgt J. , Marvel C. S. 
Published: April 2003

Abstractm‐Hexaphenyl ether, diphenyl ether, and 1,3‐bis(p‐phenoxybenzenesulfonyl)benzene were polymerized with isophthaloyl and terephthaloyl chloride in a Friedel‐Crafts type polymerization. The polymers were endcapped withp‐cyanobenzyl chloride or had units of 5‐cyanoisophthaloyl chloride in the backbone. They were crosslinked effectively, possibly by the trimerization of the nitrile groups to triazines. Model reactions were carried out for each type of polymer.
Copolymers and elastomers with alternating dioxysilphenylene and silane units
Authors: Burks Robert E. , Covington Edward R. , Jackson M. Virginia , Curry James E. 
Published: April 2003

AbstractCopolymers with alternating dioxysilphenylene and diorganosilane units were investigated as a source of high‐temperature elastomers for the aerospace industry. A copolymer with dimethylsilane units alternating with dioxysilphenylene had a glass transition temperature of −63°C and exceptional thermal stability; a polymer with diphenylsilane units alternating with dioxysilphenylene had a glass transition temperature of 0°C and slightly higher thermal stability. Both were cured to elastomers at room temperature with ethyl silicate in combination with dibutyltin diacetate. Both had tensile strengths (ultimate) above 4000 psi even without reinforcing fillers. Reinforced elastomers of the dimethyl copolymer had tensile strengths (ultimate) up to 16,000 psi.
Polymerization of styrene in N,N‐dimethylformamide
Authors: George M. H. , Ward J. R. 
Published: April 2003

AbstractThe polymerization of styrene in N,N‐dimethylformamide (DMF) at 60°C has been studied both in the presence and absence of 4,4′‐azobis‐4‐cyanopentanoic acid (ACV). Rates of polymerization were measured dilatometrically and gravimetrically, and degrees of polymerization were determined viscometrically. There was some discrepancy in the values of the transfer constant to DMF, Cs, obtained by analysis of the results. The most reliable value appeared to be 9.8 × 10−6, from experimental data obtained in the absence of added ACV.
Block copolymerization. VI. Polymerization of pivalolactone with macromolecular initiators from polystyrene and polytetrahydrofuran
Authors: Yamashita Yuya , Hane Toshioki 
Published: April 2003

AbstractPolymerization of pivalolactone with polystyryl sodium or polystyryl ethoxysodium in tetrahydrofuran resulted in homopolymer mixtures. Block copolymers of pivalolactone and styrene were obtained by the polymerization of pivalolactone with sodium polystyrene carboxylate in tetrahydrofuran containing dimethyl sulfoxide. Block copolymers of pivalolactone and tetrahydrofuran were obtained by the polymerization of pivalolactone with polytetrahydrofuran containing carboxylate endgroups. The mechanism of the initiation reaction and various factors affecting block efficiency are discussed.
Competitive growth of polystyrene latex particles: Theory and experiment
Authors: Poehlein Gary W. , Vanderhoff John W. 
Published: April 2003

AbstractThe results of the competitive growth of monodisperse polystyrene latex particles reported earlier by Vanderhoff et al. are reconciled with the predictions of more recent particle‐growth theories. In these experiments, monomer was polymerized in a seed latex comprised of a mixture of two monodisperse latexes so that the particles of different size competed with one another for the available monomer and free radicals. The results were expressed in terms of the equation dV/dt = kDc, where V is the particle volume, D the diameter, and k and c constants. The value of c is zero for emulsion polymerizations obeying Smith‐Ewart Case II kinetics and 3 for polymerizations in homogeneous phase. Experimentally, for water‐soluble persulfate initiator, the value of c was 2.5 for particle sizes larger than about 1500 Å and decreased toward zero as the particle size was decreased below 1500 Å; for oil‐soluble benzoyl peroxide initiator, it was 2.5 until the larger particles reached the critical size needed to sustain two growing radicals (about 13,000 Å), after which it increased to 3. The present work uses more recent particle‐growth theories to demonstrate that these experimental values of 2.5 and 3 are consistent with the theoretical predictions for water‐soluble and oil‐soluble initiators, respectively.
Effects of solvent in photo‐induced graft copolymerization of vinyl monomers on cellulose
Authors: Kubota Hitoshi , Murata Yukitaka , Ogiwara Yoshitaka 
Published: April 2003

AbstractThe effects of swelling of the sample and polymerization solvents were studied for photo‐induced graft copolymerization of vinyl monomers on cellulose. The graft copolymerization of methyl methacrylate (MMA) was activated by swelling of the sample or organic solvent‐water solutions within a certain range of their concentrations. Though each organic solvent gave a maximum in per cent grafting and the number of grafts at about 25 vol‐% concentration, the initiation reaction scarcely took place at 100% concentration; thus, the solvent itself is considered to have a negative effect. The solvents used in the experiments were all hydrophilic, such as methanol, acetone, and dioxane. The average molecular weight of the grafted PMMA differed in each solvent, indicating a different characteristic effect of solvent on the growing grafted polymer radicals. The presence of ferric ion as a sensitizer stimulated further the contributions of the sample swelling and the organic solvents to the copolymerization reaction. A similar effect was observed for styrene as for MMA, but not for acrylic acid and methacrylic acid.
Dependence of the viscoelastic properties of cellulose on water content
Authors: Stratton Robert A. 
Published: April 2003

AbstractThe dynamic mechanical properties at about 1 Hz of a film of regenerated cellulose have been measured over a range of temperatures from −100 to +90°C and water contents from effectively zero to 3%. Three loss peaks were found which were attributed to molecular motions in the amorphous regions. One of these was postulated to involve motion of segments of two chains connected through hydrogen bonding via a “tightly bound” molecule of water. Viscoelastic measurements over a somewhat wider range of water contents at room temperature exhibited contradictory effects depending upon the amount of water. These results provide support for the concept of two types of water in cellulose: tightly bound and loosely bound.
Synthesis of ionic block polymers for desalination membranes
Authors: Kurihara M. , Kamachi M. , Stille J. K. 
Published: April 2003

AbstractCopolymer containing 2‐vinylpyridine–trimethylsilyl methacrylate, styrene–2‐vinylpyridine, and styrene–trimethylsilyl methacrylate blocks as well as terpolymers containing the styrene2–vinylpyridine–trimethylsilyl methacrylate blocks were synthesized by initiation of the appropriate monomers sequentially both with butyllithium and sodium. These polymers were subjected to hydrolysis by which the acrylate ester segment is converted to the free acid and to the reaction with methyl iodide, which quaternizes the pyridine segment; finally the hydrolyzed and quaternized polymers were subjected to dehydrohalogenation with external base. The properties of these block polymers and blends of the styrene‐containing block copolymers were examined, especially in regard to their suitability as reverse osmosis desalination membranes.
Random copolymer of butadiene and propylene prepared with TiCl4–Et3Al–phosgene catalyst
Authors: Furukawa Junji , Eiichikobayashi  , Haga Kazuo 
Published: April 2003

AbstractThe copolymerization of butadiene and propylene was investigated. It was found that the catalyst system of TiCl4–Et3Al–COCl2 yields a random copolymer of high molecular weight with a small amount of gel polymer above room temperature. Tetrachloroethylene was a good solvent for the production of high polymer containing a high proportion of propylene units in high yield. The fractionation and the analysis of degradation experiments of copolymer indicate that the copolymer is of random distribution of propylene units in the copolymer. However, the monomer reactivity ratios, rBD = 6.36 and rPr = 0.42, suggest some degree of blocked character. The properties of the copolymer were superior to those of cis‐1,4–polybutadiene, especially in resistance to thermal aging.
Thermoplastic polyurethanes containing 12‐hydroxymethylabietanol
Authors: Wells John A. , Hedrick Glen W. 
Published: April 2003

AbstractThermoplastic polyurethane elastomers incorporating the resin acid‐derived 12‐hydroxymethylabietanol (12‐HMA) were prepared, and some physical properties are reported. A polyester macroglycol was prepared from 12‐HMA, adipic acid, and ethylene glycol. This macroglycol then was combined with either poly(tetramethylene adipate) glycol (PTAd) or poly(ethylene adipate) glycol (PEAd) and 1,4‐butanediol to give a glycol blend of 300 average hydroxyl equivalent weight (OHE). The glycol mixture then was combined with diphenylmethane 4,4′‐diisocyanate (MDI) (NCO/OH = 1.0) to give urethane polymers soluble in tetrahydrofuran. Polymers were prepared with 0, 5, 10, 15, 20, and 25%, by weight, 12‐HMA with PTAd as the other macroglycol and with 0, 10, 15, and 20% 12‐HMA with PEAd as the other macroglycol. At 15% 12‐HMA, polymers were made from glycol mixtures having 275 and 350 average OHE to demonstrate the effect of changing the hard‐segment concentration. The presence of 12‐HMA is shown to have its maximum effect on tensile properties at 15–20% in the PTAd series and at 10% in the PEAd series. In general, this effect is an increase in tensile strength and modulus and a decrease in elongation when compared with a similar polymer without the 12‐HMA.
Ethylaluminum oxide catalysts from Et2AlOLi–Et2AlCl binary system in relation to species of AlEt3–water catalyst
Authors: Araki Takeo , Aoyagi Takanobu , Ueyama Norikadzu , Aoyama Tadashi , Tani Hisaya 
Published: April 2003

AbstractEquimolar reaction of Et2AlOLi and Et2AlCl gave Et2AlOAlEt2. The catalyst behavior for polymerization of acetaldehyde, propylene oxide, and epichlorohydrin was compared with that of the AlEt3–H2O (1:0.5) catalyst system. The thermal disproportionation product of Et2AlOAlEt2 derived from Et2AlOLi–Et2AlCl had the structure, (EtAlO)n, and it showed catalyst behavior quite similar to that of the product obtained by the same treatment of AlEt3–H2O (1:0.5). These ethylaluminum oxides can be regarded as species predominating in AlEt3–H2O (1:0.5) and AlEt3–H2O (1:1), respectively. Stereospecific or high molecular weight polymerizations of these species were investigated.
Aqueous polymerization of acrylamide initiated by acidic potassium permanganate–ascorbic acid redox system
Authors: Shukla J. S. , Misra D. C. 
Published: April 2003

AbstractThe polymerization of acrylamide initiated by the acidic permanganate–ascorbic acid redox pair has been studied in aqueous media at 30 ± 0.2°C in nitrogen atmosphere. The initial rate of polymerization has been found to be proportional to nearly the first power of the catalyst KMnO4 concentration within the range 6.0 × 10−3–14.0 × 10−3 mole/l. The rate is proportional to the first power of the monomer concentration within the range 4.00 × 10−2–12.0 × 10−2 mole/l. However, the rate of polymerization is independent of ascorbic acid concentration within the range 3.0 × 10−3–6.0 × 10−3 mole/l., but the further increase of the concentration depresses the rate of polymerization as well as maximum conversion. The initial rate increases but the maximum conversion decreases as the temperature is increased within the range 20–35°C. The overall energy of activation has been found to be 9.8 kcal/mole. The optimum amount of sulfuric acid is essential to initiate the polymerization but its presence in excess produces no effect either on the rate of reaction or the maximum conversion. Water‐miscible organic solvents and salts, e.g., CH3OH, C2H5OH, (CH3)2CHOH, KCl, and Na2SO4, depress the rate. Slight amounts of MnSO4 · H2O and a complexing agent NaF increase the rate of polymerization. Cationic and anionic detergents have been found to decrease and increase the rate, respectively, while nonionic surfactants have no effect on the rate of polymerization.
Interfacial condensation polymerization of d,l‐1,2‐propylenediamine and camphoryl dichloride
Authors: Yamaguchi Hidemasa , Minoura Yuji 
Published: April 2003

AbstractThe interfacial condensation polymerization of optically active camphoryl dichloride and d,l‐1,2‐propylenediamine gave benzene‐soluble and benzene‐insoluble optically active polyamides. However, the recovered unreacted 1,2‐propylenediamine was not optically active, and the selective condensation polymerization of 1,2‐propylenediamine did not occur. The specific rotation of the benzene‐soluble polyamide was positive, while that of the benzene‐insoluble polyamide was negative. The results of proton magnetic resonance spectra suggested that the benzene‐insoluble polyamide contained predominantly trans‐camphoryl residues, while the benzene‐soluble polyamide had predominantly cis‐camphoryl residues. The difference in the specific rotation is believed to reflect the difference in relative reactivity between cis‐camphoryl and the trans camphoryl residues. It was found that poly(l‐methylethylene camphoramide) did not have a helical conformation in solution.
Effect of electrostatic field on the polymer chain in the quaternized reaction of polyvinylpyridine with alkyl halides
Authors: Tsuchida Eishun , Irie Shinichi 
Published: April 2003

AbstractIn order to discuss the electrostatic‐field effect on a polymer reaction, the quaternization of poly‐4‐vinylpyridine–benzyl chloride (system I) was compared to that of poly‐γ‐chloromethylstyrene–γ‐picoline (system II). In these two systems, the reaction initially proceeded according to the simple second‐order kinetics. However, after the degree of quaternization exceeded 20–30 mole‐%, a deviation from simple second‐order kinetics occurred. In system I negative deviation occurred, while in system II positive deviation occurred. These phenomena occurred even though the solvent or the initial concentrations of the reactants were changed. The reasons for these phenomena are given below. In system I, the quaternized pyridine nitrogens prevented the benzyl chloride from approaching the unquaternized pyridine nitrogens. However, in system II the free γ‐picoline was attracted by the quaternized chloro‐γ‐methyl site. Furthermore, the point at which the deviation occurred was determined by the degree of chloromethylation. All these results suggest that the effect of an electrostatic field must be presumed in these two systems.
Synthesis and polymerization of various vinyl‐type monomers containing the pyrrole ring
Authors: Tsuchida Eishun , Tomono Tsugikazu , Honda Kenji 
Published: April 2003

AbstractVinyl‐type monomers containing the pyrrole ring, such as 2‐vinylpyrrole (2‐VPyrr), N‐(pyrrol‐2‐yl)methylacrylamide (PMA), N‐methyl, N‐(pyrrol‐2‐yl)methylacrylamide (MPMA), 2‐allylpyrrole (2‐AP), β‐(pyrrol‐1‐yl)ethyl vinyl ether (PEVE), 2‐diallyl‐aminomethylpyrrole (DAMP), and 3‐(2‐pyrrolylmethyleneimino)propene‐1 (PIP) were synthesized by various reactions involving characteristic properties of the pyrrole ring. Radical homopolymerizations and copolymerizations of these monomers were studied. In the homopolymerization of conjugated monomers such as 2‐VPyrr and PMA, chain transfer to the pyrrole‐containing monomer was remarkable but not degradative. The copolymerization parameters, that is, the values of r1, r2, Q1, and e1 of 2‐VPyrr, were determined to be 0.066, 0.69, 5.53, and −1.36, respectively in the copolymerization of 2‐VPyrr (M1) with MMA (M2). The Q and e values of the monomers containing a heteroaromatic ring such as 2‐vinylpyrrole, 2‐vinylfuran, and 2‐vinylthiophene were evaluated by the molecular orbital theory. The e value of PMA was found to be negative (−0.64) in the copolymerization with styrene, although e for acrylamide derivatives is generally positive. This may be explained by the intermolecular hydrogen bonding between the carbonyl group and NH group of PMA. That is, attraction or polarization of π‐electrons in the vinyl group of PMA is weakened by such hydrogen bonding. From the results of copolymerization of 2‐AP with various comonomers, the comonomers could be classified into three categories: class a monomers, in which both Q and e values are largely positive, can copolymerize with 2‐AP; class b monomers, having small e values, homopolymerize and can not copolymerize with 2‐AP; class c monomers, in which both Q and e values are small. The Q and e values of the comonomer must be largely positive in order to permit copolymerization with an allyl‐type monomer.
Cationic polymerization of 6,8‐dioxabicyclo‐[3.2.1]octane and 3,6,8‐trioxabicyclo[3.2.1]octane
Authors: Hall H. K. , Steuck M. J. 
Published: April 2003

Abstract6,8‐Dioxabicyclooctane (DBO) and 3,6,8‐trioxabicyclooctane (TBO) underwent ring‐opening polymerization when treated with PF5 in dichloromethane at −78°C. These conditions were outstandingly effective for the polymerization of these bicyclic monomers, as shown by systematic variation of catalyst, solvent, and temperature. Best results were 68–84% yields of poly‐DBO, ηinh 0.26–0.33 dl/g, and ∼100% yield of poly‐TBO, ηinh 0.56–0.80 dl/g. The relationship of these results to those of previous investigators of DBO discussed.
Synthesis and polymerization of vinyl esters and vinyl ethers having bulky substituents
Authors: Nozakura Shun‐Ichi , Okamoto Takehiko , Toyora Kunimitsu , Murahashi Shunsuke 
Published: April 2003

AbstractIn order to clarify the effect of bulky substituents on the stereoregulation of vinyl monomers, vinyl‐1‐adamantanecarboxylate and vinyl 1‐adamantyl ether were synthesized and polymerized by radical and cationic mechanisms, respectively. As open‐chain models of the adamantyl group, vinyl trialkylacetate (alkyl = ethyl, n‐propyl, and n‐butyl) and vinyl tri‐n‐propylcarbinyl ether were also synthesized and polymerized. The adamantly group in the vinyl ester favored syndiotactic propagation in a manner similar to the trimethylcarbinyl group. Higher homologs of tri‐n‐alkylcarbinyl group showed higher syndiotacticity but this effect was saturated in higher members of the series. The effect of the adamantyl group in vinyl ether was similar to that of the tert‐butyl group, leading to high isotacticity on cationic polymerizations in nonpolar solvents and to atactic polymers in polar solvents, but the tri‐n‐propylcarbinyl group was found unique in leading to what was assumed to be a heterotactic polymer. Polymers with the adamantyl group showed much higher softening points than polymers of the corresponding open‐chain groups.
Poly‐α‐ester degradation studies. I. Introduction: Design and construction of equipment
Authors: Sutton G. J. , Tighe B. J. 
Published: April 2003

AbstractThe various types of polyester degradation known to occur at elevated temperature are briefly summarized with particular reference to features of potential diagnostic value. Although little is known of poly‐α‐ester degradation in particular, examination of work on other linear polyesters indicates the spectrum of analytical and kinetic information that will be needed to characterize the degradation of poly‐α‐esters of various structures. On the basis of this review, an apparatus has been designed which enables kinetic information to be simultaneously obtained by thermogravimetry, gas evolution analysis, and rheological studies of the residual polymer melt. In addition a gas sampling procedure enables twin‐column gas‐liquid chromatographic analysis to be carried out on the degradation products. Samples of the chromatographically separated degradation products are collected in a microcollector cell for infrared and mass spectrometric analysis. Other refinements include in‐line filament and Curie‐point pyrolysis techniques.
Synthesis of polyamides through active diesters
Authors: Ogata N. , Sanui K. , Iijima K. 
Published: April 2003

AbstractPolycondensation reactions of active diesters including several aromatic or heterocyclic nuclei with hexamethylenediamine were carried out in order to investigate the enhancement of reactivity of active diesters for nucleophilic replacement to form polyamide for synthesis of polyamides under moderate condition. These active diesters easily induce polycondensation reaction in solutions, forming polyamides at room temperature. Solvents have a considerable influence on the rate of the polycondensation. The reactivity of these active diesters toward aminolysis is strongly controlled by the structure of the alcohol formed. The reactivity enhancement of active ester group toward amine could be attributed either to the polarization of carbonyl group or to the resonance effect of the alkoxy group.
Effect of tacticity and morphology on the formation of persistent electrical polarization in polar polymer membranes
Authors: Linder Charles , Miller Irving F. 
Published: April 2003

AbstractPersistent electrical polarization (heterocharged electret formation) has been studied as a function of stereotacticity, crystallinity, and molecular weight in membranes of poly(vinyl alcohol) (PVA) prepared via different synthetic routes. Membranes of PVA–sodium polystyrenesulfonate (PSSNa) and PVA–poly(vinyl acetate) (PVAc) copolymers and PVA–PVAc–PSSNa were also investigated. The degree of persistent polarization a pure PVA membrane can support, was found to vary according to isotactic > syndiotactic > heterotactic triad concentrations. Increases in crystallinity tend to decrease persistent polarization, and such changes in crystallinity are probably responsible for the above observed order, since measurements of persistent polarization on noncrystalline PVA–PSSNa membranes were found to vary according to syndiotactic > heterotactic > isotactic with regard to the PVA. Within PVA–PSSNa membranes the presence of acetate groups reverses the behavior of PSSNa from anhancer to an inhibitor of electret formation. The results all support a model in which heterocharged electret formation involves an ion displacement in the direction of the applied field and stabilization of this ion displacement by local hydrogen bonding.