bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyisonitriles. II. Heterophasic catalytic synthesis of poly(α‐phenylethylisonitrile) and of poly(n‐hexylisonitrile)
Authors: Millich Frank , Sinclair R. G. 
Published: April 2003

AbstractA three‐component catalytic system has been discovered, which successfully polymerizes α‐phenylethylisonitrile to high polymer (DP = 200–900) and also polymerizes n‐hexylisonitrile. The catalyst components are a strong acid, a free‐radical source, and a heterophase and are all necessary in this system. The use of a liquid medium in which the polymer is insoluble promotes the rate of polymerization and total yield. Poly(α‐phenylethylisonitrile), formed from monomer in a presence of oxygen and finely ground glass coated with sulfuric acid, can itself serve, in the presence of monomer and oxygen, as a catalyst for this polymerization. Preparative details and discussion of these synthesis factors are given.
Linear polyhydrazides
Authors: Takahashi Hiroshi , Hasegawa Masaki 
Published: April 2003

AbstractLinear polyhydrazides have been obtained successfully by heating diphenyl dicarboxylate with 1,6‐dihydrazino hexane. The structure of the polymers was established by the N‐deuteration method. The resulting polymers have many remarkable characteristics, such as high water‐absorption ratio (20–100%), basic character (pKa = 3.15), the ability to form a metal complex, and the power to initiate vinyl polymerization as a cocatalyst with ferric ion.
The stereoregularity of polyacrylonitrile and its dependence on polymerization temperature
Authors: Matsuzaki Kei , Uryu Toshiyuki , Okada Munehisa , Shiroki Hiroyuki 
Published: April 2003

AbstractThe stereoregularity of polyacrylonitrile was studied by NMR spectroscopy. The methylene protons in isotactic configuration are equivalent in dimethylformamide‐d7 solution and are nonequivalent in dimethylsulfoxide‐d6 solution. In the case of the latter solution the difference in chemical shift between the isotactic methylene protons is 6.6 cps. The stereoregularity of polyacrylonitrile‐α‐d instead of polyacrylonitrile was determined on the dimethylformamide‐d7 solution. In the radical polymerization all the polyacrylonitrile‐α‐d's that polymerized at temperatures between 80 and −78°C. have a configuration consisting of about 50% of isotactic diads and, accordingly, the stereoregularity of polyacrylonitrile does not depend upon the polymerization temperature. Analysis of the NMR spectra of isotactic polyacrylonitrile prepared from acrylonitrile–urea canal complex was also carried out. The NMR spectra of meso‐ and dl‐2,4‐dicyanopentanes, dimer models of isotactic and syndiotactic polyacrylonitriles, respectively, were analyzed by a computer program proposed by Bothner‐By.
Determination of concentration of propagating species in cationic polymerization of tetrahydrofuran
Authors: Saegusa Takeo , Matsumoto Shu‐Ichi 
Published: April 2003

AbstractA spectroscopic method is described for the determination of the concentration of propagating species, [P*], in the polymerization of tetrahydrofuran catalyzed by a mixture of AlEt3−H2O (1:0.5) and epichlorohydrin. A phenyl ether group was introduced at the polymer chain end by the quantitative reaction of the propagating species with excess sodium phenoxide. From the amount of phenyl ether groups in the polymer and of the remaining sodium phenoxide, [P*] was determined by means of ultraviolet spectroscopy. The [P*] value so determined was found to be in good agreement with that calculated from the amount and molecular weight of polymer based on a stepwise addition mechanism without chain transfer or termination. The present method of [P*] determination was employed to examine the course of polymerization. It has now been found that [P*] increases progressively during an induction period and remains unchanged in the subsequent period of polymerization.
Relaxations of selenium in crystalline and amorphous states
Authors: Nishi Toshio , Wada Yasaku 
Published: April 2003

AbstractComplex shear modulus at 33 kc./sec. is measured at temperatures of −150–150°C. for amorphous selenium and crystalline selenium with different crystallinities. The dielectric relaxation at 10 kc./sec. to 3 kc./sec. to 3 Mc./sec. is observed at temperatures of −32–25°C. for iodine‐doped crystalline selenium. It is concluded from the results of this study and of others' that selenium exhibits four relaxations, α, β γ, and δ, in order of descending temperature. The β relaxation is observed only in the amorphous sample above the glass temperature and is assigned to the primary relaxation. The α, γ, and δ relaxations are found in the crystalline selenium. The α relaxation, which is prominent in a highly crystalline sample, is assigned to the crystalline relaxation. The γ and δ relaxations increase in peak height with decreasing crystallinity and are attributed to the disordered region in the crystalline selenium. The dispersion map (logarithm of frequency versus reciprocal absolute temperature of loss maximum) of selenium is presented.
Electrical conductivity of N‐substituted polyamides
Authors: Kasica H. , Kryszewski M. , Szymaniski A. , Włodarczyk M. 
Published: April 2003

AbstractThe electrical volume and surface resistivity of some poly(N‐chloroalkoxylmethyl caproamides) were measured as a function of voltage at 39% R. H. and under vacuum. The results were compared with non‐N‐substituted polycaproamide. Polarization and depolarization phenomena were observed. The mechanism of conduction is discussed, and important deviations from Ohm's law, observed in dry samples, suggest that charge carriers are injected from the electrodes and that the current–voltage characteristics may be interpreted on the assumption of space‐charge‐limited current theory.
Reaction between ethanol and silicon–hydrogen of poly(p‐vinylphenyldimethylsilane)
Authors: Iwakura Yoshio , Toda Fujio , Hattori Kenjiro 
Published: April 2003

AbstractA kinetic approach to the polymer reaction, with KOH as catalyst, between ethanol and poly(p‐vinylphenyldimethylsilane) containing silicon–hydrogen as a functional group on the side chain was carried out. The rate equation was obtained by measuring the initial rate of the model reaction as v = k[KOH] [SiH] [EtOH] in benzene and v = k[KOH] [SiH] in methyl ethyl ketone. It was observed that the rate of reaction was affected by the polarity of the solvents. In the polymer reaction the rate constant decreased markedly with increasing ethanol concentration. A change of viscosity of the polymer in various solvents was observed to have a good correlation with the decrease in reaction rate in corresponding solvents. In mixed solvents, consisting of both good and poor solvents for the polymers, the reaction rate depended upon two factors, the entanglement of the polymer chain and the polarity of the solvents. The equivalent globular model of the polymer chain is suggested for study of the polymer reaction. A schematic local‐distribution curve of the reaction species is proposed.
Solvent effect on NMR spectra of poly(methyl methacrylate)
Authors: Nagai Makoto , Nishioka Atsuo 
Published: April 2003

AbstractThe NMR spectra of stereoblock poly(methyl methacrylate) in several solvents were measured. It is concluded from the following experimental results that the solute–solvent complexes are formed in benzene solution: the chemical shifts measured in C6H6 go to a lower field than do those in CDCl3, except those of the ester methyl group, which splits into three resonances, and the shifts in the aromatic solvents are so different from those in the aliphatic solvents that Buckingham's theory cannot be applied to the results. The analysis of the temperature dependence of the chemical shifts of PMMA in benzene solution gave the heat of formation of the complex: ΔH = 2.8 ± 0.5 kcal./mole.
Study of the substitution pattern of hydroxyethylcellulose and its relationship to enzymic degradation
Authors: Wirick M. G. 
Published: April 2003

AbstractThe concentration of completely unsubstituted anhydroglucose (AHG) units in hydroxyethylcellulose (HEC) at varying average number of moles of substituent (MS) is in accord with a reaction rate ratio of 3:1:10:10 for the etherification of the C2, C3, C6, and side chain hydroxyls. Assuming random substitution along the cellulose chain at these relative reaction rates, the degree of substitution (DS), average poly(ethylene oxide) side‐chain length, and probably frequency of isolated and multiple adjacent unsubstituted AHG units have been projected as functions of MS. Such estimates of DS and side‐chain length compare favorably with actual measurements made on a variety of samples by other investigators below a substitution level of 2.0 MS. Reducing end, intrinsic viscosity, and ultracentrifuge data on enzymically hydrolyzed HEC's varying from 1.9 to 3.7 in MS indicate resistance to chain scission is a function of substitution, best expressed in terms of a proposed substitution index, the percentage of substituted AHG units. The rate of chain scission under carefully controlled conditions is initially rapid, tapering to a very slow, essentially steady level. On relating the frequency of chain breaks to the predicted substitution pattern of these samples, this behavior is interpreted to mean that scission occurs relatively rapidly at multiple contiguous unsubstituted sequences, but much more slowly adjacent to isolated unsubstituted AHG units. A possible mechanism of enzyme attack, correlating molecular chain breaks with glucose released, has been developed.
Thermally stable polymers from 1,4,5,8‐naphthalenetetracarboxylic acid and aromatic tetraamines
Authors: Van Deusen R. L. , Goins O. K. , Sicree A. J. 
Published: April 2003

AbstractPolycondensations of 1,4,5,8‐naphthalenetetracarboxylic acid (NTCA) with both 3,3′‐diaminobenzidine (DAB) and 1,2,4,5‐tetraaminobenzene tetrahydrochloride (TAB) in polyphosphoric acid (PPA) were found to produce soluble polymers which exhibit excellent thermal stabilities. Polymer structures were deduced from infrared, thermal, and elemental analyses of model compounds and polymers. Polymer derived from TAB had a ladder‐type structure. Polymers with solution viscosities near 1 or above (determined in H2SO4) were obtained from polymerizations near 200°C., and analysis showed these to possess a very high degree of completely cyclized benzimidazobenzophenanthroline structure. Less vigorous reaction conditions gave polymers with lower solution viscosities which appeared to be less highly cyclized. Low‐viscosity polymer was also prepared from DAB and NTCA by solid‐phase polycondensation. Some advancements in the solution viscosities of polymers synthesized from DAB in PPA were caused by second staging in the solid phase.
Retardation of discoloration of poly(vinyl chloride) and decolorization of discolored poly(vinyl chloride) with diimide
Authors: Nakagawa Tsutomu , Okawara Makoto 
Published: April 2003

AbstractRetardation of discoloration of poly(vinyl chloride) with diimide was studied in dimethylformamide at 130°C. with the use of p‐toluenesulfonylhydrazide (PSH) as a source of diimide. A process was proposed that involved prolonging the induction periods of discoloration by inhibiting the development of conjugated polyene structure. The optimum proportion of PSH was one fourth of the poly(vinyl chloride), the best results. Furthermore, poly(vinyl chloride) discolored by thermal degradation in o‐dichlorobenzene or gamma‐ray irradiation under vacuum was decolorized in solution at 130°C. by addition of PSH. The decolorized poly(vinyl chloride) thus obtained was thermally stable compared with that obtained by oxidative methods.
Effects of metal salts on polymerization. Part V: Polymerization of N‐vinylcarbazole initiated by sodium chloroaurate
Authors: Tazuke Shigeo , Asai Michihiko , Okamura Seizo 
Published: April 2003

AbstractThe polymerization of N‐vinylcarbazole (VCZ) initiated by sodium chloroaurate (NaAuCl4·2H2O) in nitrobenzene was studied at 30°C. The rate of polymerization (Rp) is proportional to [AuIII] [VCZ] after a short induction period. When reducing agents (ascorbic acid, ferrocene, or mercury metal) are added to the system, the rate of polymerization in the dark increases. The Rp is relatively unaffected by addition of water and N‐ethylcarbazole, but the polymerization is completely inhibited in the presence of ammonia. Oxygen and DPPH act as neither inhibitors nor retarders. Kinetic treatments based on the assumption that the active initiating species is AuII produced by reduction of AuIII by VCZ and other reducing agents explain the experimental results very well.
Polymerization and copolymerization of α‐methacrylophenone
Authors: Mulvaney J. E. , Dillon J. G. , Laverty J. L. 
Published: April 2003

AbstractUnder a variety of conditions it has not been possible to induce the free‐radical‐initiated homopolymerization of α‐methacrylophenone (α‐MAP). The only product isolated from such efforts was the Diels‐Alder dimer of the monomer. A Mayo‐Lewis plot of the free‐radical copolymerization of α‐MAP and styrene shows considerable scatter but the copolymer composition indicates that an α‐MAP unit can add to itself. These results have been ascribed to a penultimate effect. α‐MAP is homopolymerized by dimsylsodium or n‐butyllithium. Attempted copolymerization of α‐map and styrene with n‐butyllithium produces >95% α‐MAP. Unexpectedly, α‐MAP does not homopolymerize with lithium dispersion, but does react in the presence of styrene to give product containing a relatively small amount of α‐MAP.
A new transition point of polyacrylonitrile
Authors: Okajima Saburo , Ikeda Morio , Takeuchi Akio 
Published: April 2003

AbstractA polyacrylonitrile sample of molecular weight 78,000 was dissolved into a 15% solution in 70% aqueous HNO3, spun into an undrawn model filament with diameter 0.3 mm. using a 30% aqueous HNO3 as the coagulation bath. The fresh filament was drawn 4–16× in water at various temperatures (40, 65, and 75°C.) and then steamed at 90–180°C. Dynamic mechanical tests were carried out on these filaments at 138 cps and it was found that the steamed filaments had a new transition at about 160°C. in addition to the two well‐known transitions at 60–70°C. (β) and 110°C. (αa), although the unsteamed samples had only the two absorptions, αa and β. This newly found transition was designated αx. The αx was measured at 3.5, 11, and 110 cps from which the activation energy of this relaxational motion was estimated to be 95 kcal./mole. The αx peak height was lowered by stretching and recovered on resteaming; the change in the peak height was paralleled by the changes in the x‐ray crystallinity produced by the stretching and the resteaming. These phenomena lead us to a conclusion that the region contributing to the αx absorption is of considerably higher order than that of the αa transition with an activation energy about 50 kcal./mole and intimately related to the crystallinity, although it cannot be connected directly to the crystalline region itself because a single crystal mat did not show the αx.
Inorganic esters of novolacs
Authors: Dannels B. F. , Shepard A. F. 
Published: April 2003

AbstractReaction of conventional novolacs with polyfunctional materials is known to yield crosslinked infusible products. Surprisingly, high proportions of polyfunctional phosphorus derivatives can be esterfied with o,o′‐linked novolacs without encountering gelation. Soluble, fusible resins of high phosphate content, which possess improved flame retardance, are conveniently obtained. We attribute this result to the formation of cyclic esters in preference to crosslinking, as evidenced by the formation, in good yield, of the eight‐membered heterocyclic compound C27H31O4P from o,o′‐methylenebis(p‐tert‐butylphenol) and phenyl phosphorodichloridate. Relatively large amounts of polyfunctional derivatives of boron and silicon can also be reacted with o,o′‐linked novolacs, presumably in a similar manner. Novolacs partially reacted with phosphorus, boron, or silicon derivatives and retaining some phenolic hydroxyl cure readily with hexamethylenetetramine, yielding products exceptionally low in volatile loss at 400°C.
Determination of theoretical plates in gel permeation chromatography by using polydisperse materials (polymers)
Authors: Bly Donald D. 
Published: April 2003

AbstractThe need for an improved method of expressing performance of GPC columns and operating conditions is discussed. It is shown that theoretical plates can be calculated from chromatograms of high molecular weight materials (polymers) if the curve widths are normalized for polydispersity. The resulting value N, where N = 16d2(v/W)2, is a useful measure of the real plate count afforded by the columns to polymers and is useful for comparison purposes. Since N does not provide absolute data on separation, it is better to use formulas for resolution and fractionation when such data are needed.
Silicon‐containing amide, benzimidazole, hydrazide, and oxadiazole polymers
Authors: Kovacs Hanna Nagy , Delman Alvin D. , Simms Bernard B. 
Published: April 2003

AbstractThis study reports the synthesis of new silicon‐containing amide, benzimidazole hydrazide, and oxadiazole polymers. Procedures are described for the preparation of several intermediate compounds. The silicon‐containing polymers are soluble in organic solvents. Solution‐cast films from the polymers generally are flexible and exhibit good adhesion to glass and metal surfaces. Preliminary examination indicates that the polymers are heat‐stable at elevated temperatures.
Effects of methyl sidegroup on the extent of hydrogen bonding and modulus of polyurethane elastomers
Authors: Tanaka Takehide , Yokoyama Tetsuo , Yamaguchi Yukio 
Published: April 2003

AbstractThe effects of methyl sidegroup on the properties of polyurethane elastomers, mainly hydrogen bonding and elastic properties, were studied. Polyurethanes of almost equal crosslinking density and urethane group concentration, but with different side methyl groups, were prepared by a prepolymer method. The extent of hydrogen bonding was determined by an infrared technique. The density and Young's modulus are decreased by the introduction of methyl sidegroup, swelling ratio and Tg are increased, but the extent of hydrogen bonding is not affected.
Aminimides. V. Preparation and polymerization studies of trimethylamine‐4‐vinylbenzimide
Authors: Culbertson B. M. , Sedor E. A. , Dietz S. , Freis R. E. 
Published: April 2003

AbstractTrimethylamine‐4‐vinylbenzimide (TAVBI) has been homo‐ and copolymerized with styrene, methyl methacrylate, and hydroxypropyl methacrylate by free‐radical initiators to soluble, low molecular weight polymers containing pendant aminimide groups along the backbone of the polymer molecules. The reactivity ratios in the copolymerization of TAVBI (M1) with styrene (M2) were determined: r1 = 0.63 ± 0.07, r2 = 0.47 ± 0.05. The Alfrey‐Price Q and e values for TAVBI were also calculated: Q = 0.88, e = 0.31. This introductory work indicates that TAVBI has potential for the preparation of a wide variety of reactive polymers.
The emulsion polymerization of vinyl acetate. Factors controlling particle surface area and rate of polymerization
Authors: Gulbekian E. V. 
Published: April 2003

AbstractAn emulsion polymerization system with uniform continuous addition of vinyl acetate monomer, Pluronic F68 surfactant, and persulfate initiator has been examined with variation of the surfactant concentration over a tenfold range. The particle surface area per unit weight of emulsion was found to vary directly as the surfactant/monomer ratio, as also did the emulsion viscosity. At constant polymer/emulsion weight the number of particles per unit emulsion weight varied directly as the cube of the surfactant concentration. It is shown that these relationships apply also to other monomers, such as styrene and methacrylate esters. The solubility of vinyl acetate in a range of Pluronic F68 aqueous solutions was determined, and it was shown that the rate of polymerization is dependent on the solubility of the monomer in the surfactant solution. It is concluded that when a water‐soluble initiator is used, polymerization proceeds in the aqueous phase. The principal factors controlling the rate of polymerization in the emulsion polymerization of vinyl acetate are, consequently, the initiating system and the concentration of monomer in the aqueous phase. Solubilization characteristics indicate that the surfactant concentration will have a much greater effect on the less water‐soluble monomers, such as styrene, than on the more soluble ones, such as vinyl acetate.
Some properties of poly‐α‐piperidone
Authors: Tani Hisaya , Konomi Tuyoshi 
Published: April 2003

AbstractThe high molecular weight polymer of α‐piperidone, which had been unobtainable with the use of alkali metal, trialkyl aluminum, or Grignard reagent as catalyst, was prepared with M–AlEt3, (where M is alkali metal), MAlEt4 or KAlEt3 (piperidone) as catalyst and N‐acyl‐α‐piperidone as initiator. From the determination of the behavior of the solution viscosity of poly‐α‐piperidone in m‐cresol at 30°C. the value of 0.27 for the Huggins constant was obtained. Examination of the correlation between the number‐average molecular weight, determined by endgroup titration, and the intrinsic viscosity gave a somewhat small value for the endgroup COOH. This may be considered due to the consumption of N‐acyl‐α‐piperidone by a propagating polymer in the course of polymerization. The thermal stabilities of the polyamides, nylons 4, 5, and 6, was in the order nylons 6 > 5 > 4 according to differential thermal and thermogravimetric analyses, Poly‐α‐piperidone, which has a reduced viscosity of 0.7, shows a melting point of 270°C.. which was expected from the zigzag pattern of the correlation between melting points and numbers of CH2 groups for polyamino‐acid polymers.
Polymers from 1,3‐dipole addition reactions: The sydnone dipole
Authors: Stille J. K. , Bedford M. A. 
Published: April 2003

AbstractAn investigation of the suitability of certain 1,3 dipole addition reactions as polymerization reactions was carried out. Reaction of p‐phenylene‐3,3′‐disydnone and N,N′‐hexamethylenedisydnone with the dipolarophiles m‐ and p‐diethynylbenzene, m‐divinylbenzene, and p‐benzoquinone gave moderate molecular weight polymers containing pyrazole or pyrazoline units along the polymer backbone. The polymers are crystalline and have inherent viscosities of 0.4–0.6. The thermogravimetric analyses of the finely powdered polyprazoles showed breaks near 420°C. in air and 500°C. in nitrogen atmospheres.
Polycondensation equilibrium and the kinetics of the catalyzed transesterfication in the formation of polyethylene terephthalate
Authors: Fontana C. M. 
Published: April 2003

AbstractThe polycondensation equilibrium constant for bis(β‐hydroxyethyl) terephthalate was found to be 0.50. By means of this value for determining the relative reactivity of two kinds of hydroxyl groups, the kinetic data were found to fit a third‐order reaction for the transesterification: one order each with respect to hydroxyl group, methoxy group, and catalyst. An order with respect to hydroxyl group, which had previously been in doubt, was proved in a series of experiments in which the concentration of ethylene glycol was varied. Third‐order rate constants were determined for the reactions catalyzed by lead, zinc, and calcium salts, and the activation energies were found to be 12.5, 15.0, and 14.5 kcal./mole, respectively. The results are consistent with the author's theory of aromatic transition states and are difficult to explain on the basis of ionic theories of reaction mechanism.