bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of pH on the reactivity ratios in aqueous solution copolymerization of acrylic acid and N‐vinylpyrrolidone
Authors: Ponratnam S. , Kapur S. L.
Published: April 2003

Acrylic acid (AA) and N‐vinylpyrrolidone (NVP) were copolymerized in aqueous solution at 30°C in the pH range 4–9 and the monomer reactivity ratios (r1 for AA and r2 for NVP) were determined as a function of pH from the high conversion data by using both the differential (YBR) and the integrated copolymerization equations. The value of r1 decreased from 5.2 at pH 4 to a minimum of 1.3 at pH 5 and then increased to 8.1, 6.6, and 7.2 at pH 7, 8, and 9, respectively. Addition of 1M NaCl at pH 6.5 restored the r1 nearly to that at pH 4, the predominantly un‐ionized acid. The r2 values for NVP were nearly zero at all pH values except at pH 5. The variation of the reactivity ratios with pH was examined in terms of the electrostatic interactions between the ionized monomer molecules, the rate of homopolymerization of acrylic acid, and the cation binding to the poly(acrylic acid) molecules. The r2 values for NVP compared favorably with the literature values reported in bulk and organic solvent systems, although r1 values are much higher.
Polymerization of coordinated monomers. XII. Alternating copolymerization of γ‐crotonolactone with styrene with the use of stannic chloride
Authors: Komiyama Makoto , Hirai Hidefumi
Published: April 2003

γ‐Crotonolactone and styrene copolymerize alternately in the presence of stannic chloride at ‐10°C under photoirradiation. The intrinsic viscosity of the resulting copolymer is in the range of 0.6–0.8 dl/g at 30°C in chloroform. The equilibrium constants for the complex formation between stannic chloride and γ‐crotonolactone were determined in 1,2‐dichloroethane‐toluene solution at 0 and −20°C by use of absorption band at 350 nm. Continuous variation plots based on the 1H‐chemical shift show a 1:1 interaction between styrene and the γ‐crotonolactone coordinated to stannic chloride. The equilibrium constants for the ternary molecular complex formation between the coordinated γ‐crotonolactone and styrene were determined in 1,2‐dichloroethane in the temperature range from −20 to 0°C. The equilibrium constants, derived independently from the measurements of the nonequivalent protons in γ‐crotonolactone, are equal to each other within the experimental error. The mechanism of the alternating copolymerization of γ‐crotonolactone and styrene in the presence of stannic chloride is discussed in terms of the homopolymerization of the ternary molecular complex.
Oligomeric polyaromatic ether‐ketone‐sulfones with acetylenic end groups. IX.
Authors: Kellman Raymond , Marvel C. S.
Published: April 2003

Two oligomeric polyaryl ether‐ketone‐sulfones with acetylenic end groups have been prepared. These materials which are low melting and readily soluble in organic solvents on heating undergo reactions which are presumably trimerizations of the terminal acetylenic groups to give cured polymers which do not soften until about 200°C and which are stable in circulating air at 300°C with less than 10% weight loss in 10 days.
Solid‐state polymerization of N‐carboxy‐L‐leucine anhydride crystals in n‐hexane
Authors: Oya Masanao , Takahashi Tomoko , Katakai Ryoichi
Published: April 2003

4‐Isobutyloxazolidinedione, L‐leucine N‐carboxy anhydride, was polymerized to produce high molecular weight polymer with triethylamine in n‐hexane which is not a solvent for the N‐carboxy anhydride and poly‐L‐leucine. It was found that as the crystal size became smaller, the total surface area was increased, the initial rate of polymerization was increased, and inherent viscosity of the formed polymer was decreased.
1:1 alternating copolymer of acrylonitrile and vinyl acetate
Authors: Chen Catherine S. Hsia
Published: April 2003

Copolymerization of the acrylonitrile‐zinc chloride complex with excess vinyl acetate has been investigated. Alternating 1:1 copolymers of acrylonitrile and vinyl acetate of high molecular weights have been successfully prepared. The alternating structure has been ascertained by means of high‐resolution nuclear magnetic resonance spectroscopy. The copolymer is amorphous (Tg = 85°C) and has shown thermal and oxidative stability better than those of polyacrylonitrile. The copolymer is soluble in acetone as well as in more powerful solvents such as dimethylformamide, dimethyl sulfoxide, nitromethane, and N‐methylpyrrolidone. The copolymer has been processed into films and fibers from its acetone solutions. Films show tensile properties similar to those of cellulose acetate under ambient conditions; they suffer drastic loss in tensile properties at above 50°C and retain their good tensile properties at subzero temperatures (determined as low as −40°C). Fibers show tensile properties comparable to those of modacrylic fibers under ambient conditions but suffer marked loss in stiffness at 40°C in water and 60°C in air. The fibers also retain their good properties at subzero temperatures (measured down to −60°C).
Molecular weight determination of vinylidene chloride copolymers by gel‐permeation chromatography and viscometry
Authors: Revillon A. , Dumont B. , Guyot A.
Published: April 2003

This is the first report on the characterization of several pairs of random copolymers of vinylidene chloride by gel‐permeation chromatography in conjunction with viscometry. Such copolymers have not previously Received much attention, so we first determined the individual viscosity–molecular weight relationship. The K–a values were compared with known values for the parent homopolymers. We then derived calibration curves (different for each composition) and the calculation of the average molecular weight. These results are compared to those obtained by direct methods, without fractionation, and to kinetic observations. This method avoids misinterpretation of viscosity data and elution volume. Chromatograms may indicate heterogeneity of the compounds as related to polymerization conditions.
Polyimide structure–property relationships. II. Polymers from isomeric diamines
Authors: Bell Vernon L. , Stump Billy L. , Gager Helen
Published: April 2003

An extensive study of the effects of stereoisomeric variations in aromatic polyimide structures on polyimide properties was conducted. The structural variations were incorporated into the polyimides through the use of two complete series of isomeric aromatic diamine monomers, the diaminodiphenylmethanes and the diaminobenzophenones, as well as several pairs of diamine isomers. The ability of the diamines to polymerize was related to the basicities, and thus reactivities, of the amino groups. Diamines with an amino group located ortho to the group connecting the two aromatic rings were successfully polymerized with dianhydrides for the first time to high molecular weight poly(amic acids). The stereoisomeric polyimides were characterized by determining the glass transition temperatures Tg, mechanical properties, and thermooxidative stabilities of thin films of the polymers. The polymers prepared from p‐diamines were shown to have the highest softening points and thus, the most rigid molecular structures. Those synthesized from m‐diamines had the lowest Tg values, inferring the most flexible molecular backbone. With limited exceptions, the use of diamines with ortho‐oriented amine groups failed to improve the flexibility of the polyimides since their Tg values were usually as high as those of polymers made from p‐diamines. Only slight differences in mechanical properties of the isomeric polyimide films were attributable to the variations in isomeric structure, except for those properties dependent upon Tg changes, such as elevated temperature mechanical properties. A study of the thermooxidative stability of the polyimides showed little difference between the polymers prepared from the diaminobenzophenones, but marked differences were observed between the individual members of the diaminodiphenylmethane‐derived polyimides.
Characterization of novolac resins based on p‐tert‐butylphenol by PMR spectroscopy
Authors: Nowlin T. E. , Boyd W. H.
Published: April 2003

The direct silylation of tert‐butylphenol formaldehyde resins with N,O‐bis(trimethylsily)acetamide (BSA) has allowed a more complete analysis of these resins to be made with proton magnetic resonance (PMR) spectrometry. A quantitative determination of mixtures of the monomer, dimer, trimer, and tetramer may be carried out at 100 MHz.
EPR study of the photoinitiated polymerization of butadiene and of an isobutylene–butadiene mixture in the presence of VCl4
Authors: Pilař J. , Toman L. , Marek M.
Published: April 2003

The EPR spectra of butadiene and of a mixture of butadiene and isobutylene in the presence of VCl4 in the dark and with irradiation have been studied. The effect of light on butadiene leads to the formation of the radical‐cation of butadiene, similarly to isobutylene. In the mixture of both monomers, radical cations of isobutylene and butadiene are formed under the effect of light. Even if isobutylene is present in excess in the mixture compared to butadiene, the formation of the radical‐cation of butadiene still prevails. In presence of oxygen, with both butadiene and the isobutylene–butadiene mixture, peroxy radicals were detected. Cyclic polybutadiene was the main product of the photochemically initiated polymerization of butadiene.
Higher aliphatic polyaldehydes. II. Polymer structure and polymer stability of poly(n‐heptaldehyde)
Authors: Negulescu I. , Vogl O.
Published: April 2003

Poly(n‐heptaldehyde) has been prepared by anionic and cationic polymerization at −60°C in methyl cyclohexane. The anionic polymer is more crystalline and of a higher degree of isotactic structure than the somewhat rubbery but still crystalline cationic polymer. The polymers have been acetate‐endcapped to improve their thermal stability. Cationic polymer, when endcapped and purified, begins to degrade above room temperature; even crystalline anionic polymer degrades at a reasonable rate at 100°C. The crystallinity of poly(n‐heptaldehyde) is caused by crystallization of the acetalic main chain as well as the side chain. Two regions of melting have been recognized by DSC analysis and by microscopic observations. The low melting region between 80 and 100°C has been identified as the melting of the paraffinic side chains of poly(n‐heptaldehyde). It consists of three clearly definable endotherms at 78, 87, and 101°C.
Voltammetric behavior of poly(vinylferrocene)
Authors: Smith Thomas W. , Kuder James E. , Wychick Darlene
Published: April 2003

A voltammetric analysis of the electron‐transfer process in poly(vinylferrocene) (PVF) has been carried out; the results indicate that the electrochemical behavior of ferrocene and PVF are quite similar. The field effects in the macromolecular environment do, however, appear to influence the microscopic potential for oxidation of adjacent ferrocene residues in PVF. Analysis of the slopes of plots of limiting current versus the square root of the rotation speed indicate that only “isolated” ferrocene residues in the polymers are oxidized under the conditions of the rotating‐disk electrode experiment.

Diffusion coefficients were determined experimentally for ferrocene and its macromolecular analogs were quite close to those simply calculated from the Stokes‐Einstein relationship. Further, it was demonstrated that the molecular weight, which is inversely proportional to the diffusion coefficient, could be determined by voltammetric techniques.
Determination of branching in polyethylene and poly(vinyl chloride) using pyrolysis gas chromatography
Authors: Ahlstrom David H. , Liebman Shirley A. , Abbås Kent B.
Published: April 2003

A series of polyethylenes (PE), reduced poly(vinyl chlorides), and precursor poly(vinyl chloride) (PVC) systems were studied by pyrolysis–gas chromatography (PGC) and by pyrolysis–hydrogenation–gas chromatography (PHGC). The branch content of these polymers has been interpreted on the basis of previously established literature information. Low‐density PE (LDPE) was found to contain a significant number of ethyl branches. The pyrolysis results on an LAH‐reduced PVC series gave significant insight on PVC microstructure. It was determined that the short‐chain branches in PVC are mainly one carbon long. Some ethyl side chains and virtually no butyl branches were found in this experimental PVC series. The effect of chain branching on the pyrolysis of PVC is to increase fragmentation. The benzene/toluene ratio, along with relative amounts of benzene and naphthalene formed, may be used to indicate the relative degree of branching in this system. The application of PGC and PHGC have thus been shown to successfully extend analytical work on PE and PVC and to provide microstructural information.
Radiation‐induced polymerization of sodium allylsulfonate at high pressure
Authors: Sasuga Tsuneo , Morishita Norio , Udagawa Akira , Kusama Yasuo , Takehisa Masaaki
Published: April 2003

Irradiation of sodium allylsulfonate in aqueous solution at high pressure (up to 9000 kg/cm2) gave a deliquescent white powder which is insoluble in organic solvent. The product was addition polymer of allylsulfonate from the high‐resolution NMR and infrared spectra. The rate of polymerization was proportional to the third and second powers of monomer concentration in the initial and later stages, respectively. From the high dependence of the rate on monomer concentration, the reaction was deduced to proceed in an associated monomer or micelle. The rate of polymerization was increased by addition of sodium chloride. The G value for monomer consumption was about 104 at high pressure, which suggests that the degradative chain transfer is not important in the polymerization. Overall activation volumes were −7 and −5 ml/mole in the initial and later stages, respectively.
Alternating copolymerization of the styrene–methyl methacrylate system complexed with diethylaluminum chloride
Authors: Funt B. Lionel , Pawelchak Gordon A.
Published: April 2003

The rate and molecular weight profiles were obtained for the spontaneous alternating copolymerizations conducted with diethylaluminum chloride. The rate formally fitted an expression, R = kp[MMA][Sty], and the rate constant was established by two distinct methods: (1) from the yield versus time data and (2) from initial rate over a range of initial concentrations; it was determined as 5.4 × 10−6 l./mole‐sec with Ea = 4.2 kcal/mole. Molecular weights were determined by gel‐permeation chromatography. No increase in molecular weight was observed with increased reaction time. Thus living centers or diradicals are not involved in the process. The M̄n shows a steady decrease with increase in monomer‐diethylaluminum chloride concentration but the rate is maximum at equimolar monomer concentrations. The data are interpreted on a chain‐transfer mechanism and show close agreement to a model in which the excess complexed acceptor monomer is the transfer agent. The chain‐transfer constant of 7.1 × 10−4 l./mole‐sec is several orders of magnitude greater than for uncomplexed systems.
Synthesis of polyamides from active 1‐benzotriazolyl diesters and diamines under mild conditions
Authors: Ueda Mitsuru , Okada Kohji , Imai Yoshio
Published: April 2003

The effect of the solvent on the inherent viscosity of polyamides was investigated in the polycondensation of new active 1‐benzotriazolyl diesters, such as 1,1′‐(adipolydioxy)bisbenzotriazole and 1,1′‐(isophthaloyldioxy)bisbenzotriazole, with diamines. The preferred polymerization media were polar aprotic solvents, including N‐methyl‐2‐pyrrolidone and hexamethylphosphoramide. The solution polycondensation at room temperature afforded a series of polyamides having inherent viscosities as high as 1.8 from both aliphatic and aromatic diamines. The 1‐benzotriazolyl diesters were more reactive than di(2,4‐dinitrophenyl) isophthalate toward diamines. Prior to polymer synthesis, the aminolysis of some active monoesters was carried out as a model compound study.
ESR and NMR study of the γ‐ray‐induced postpolymerization of vinyl monomers adsorbed on zeolite
Authors: Quaegebeur Jean Pierre , Seguchi Tadao , Bail Henri Le , Chachaty Claude
Published: April 2003

The γ‐ray‐induced postpolymerization of acrylonitrile and methyl methacrylate adsorbed on Linde zeolite 13X irradiated at 77°K has been studied between 303 and 343°K as a function of the amount of adsorbed monomer and of the irradiation dose. The change in the nature and the concentration of free radical with temperature and duration of the postpolymerization was followed by the ESR method, whereas the formation of polymer was monitored continuously by the decay of the 1H‐NMR absorption line of the monomer under high‐resolution conditions. It was found that the overall postpolymerization kinetics may be accounted for by assuming an exponential decay of radical propagation and recombination reactions with chain length. The tacticity of the polymer recovered by destroying the matrix in hydrofluoric acid was determined by 13C‐NMR. The probability of isotactic addition of AN and MMA is larger than in the radical polymerization in solution owing likely to the association of adsorbed monomer molecules in pairs preforming an isotactic diad.
Functional polymers. II. Preparation and polymerization of methyl 5‐vinylsalicylate, methyl 5‐vinylacetylsalicylate, 5‐vinylsalicylic acid, and 5‐vinylacetylsalicylic acid
Authors: Bailey D. , Tirrell D. , Vogl O.
Published: April 2003

Four new derivatives of 5‐vinylsalicylic acid were prepared and their homopolymerization and copolymerization with acrylic acid and methacrylic acid investigated. Methyl 5‐vinylsalicylate was prepared in a six‐step synthesis from methyl salicylate in an overall yield of 35%. Acetylation in the last step yielded methyl 5‐vinylacetylsalicylate. Hydrolysis of methyl 5‐vinylsalicylate gave 5‐vinylsalicylic acid which was acetylated to 5‐vinylacetylsalicylic acid (5‐vinyl aspirin). The 5‐vinyl‐substituted salicylic acid derivatives could be readily homopolymerized and copolymerized with acrylic acid and methacrylic acid to give various compositions of copolymers. It is worth noting that even the monomers with free phenol groups could be readily polymerized with azobisisobutyronitrile as radical initiator to high molecular weight polymers without interference of the phenolic OH group.
Synthesis of polypyridazinophthalazinediones from dibenzoylphthalic acids and aromatic dihydrazines
Authors: Imai Yoshio , Ueda Mitsuru , Aizawa Tatsuo
Published: April 2003

A novel class of polypyridazinophthalazinediones has been synthesized by the solution cyclopolycondensation in m‐cresol of dibenzoylphthalic acids with aromatic dihydrazines such as bis(4‐hydrazinophenyl)methane and bis(4‐hydrazinophenyl) sulfone. The polyheterocycles derived from 4,6‐dibenzoylisophthalic acid, which had inherent viscosities of up to 0.5, were soluble in m‐cresol and hot dichloroacetic acid, whereas the polymers from 2,5‐dibenzoylterephthalic acid were practically insoluble in organic solvents. Thermogravimetric analyses showed that all the polymers underwent weight losses of 10% at 490–520°C in both air and nitrogen.
Reactivity ratios for acrylic acid–methyl acrylate copolymerization in 1,4‐dioxane
Authors: Eldridge R. J. , Treloar F. E.
Published: April 2003

We report values of reactivity ratios for the copolymerization in 1,4‐dioxane of acrylic acid (AA) and methyl acrylate (MA), measured as part of work on ion‐binding to polyelectrolytes at different charge densities. Ryabov et al.1 have shown the reactivity ratios for this and similar systems to depend on the nature and amount of the solvent used.
Triphenylmethyl hexafluoroarsinate‐initiated polymerization of 1,2‐butylene oxide
Authors: Leborgne Alain , Malhotra Shadi Lal , Blanchard Louis‐Philippe
Published: April 2003

The polymerization of 1,2‐butylene oxide initiated with triphenylmethyl hexafluoroarsinate in the −20 to +25°C temperature range with 1,2‐dichloroethane as solvent is characterized by a rapid nonstationary initial stage. This is followed by a second slower stage, during which the disappearance of monomer is first‐order with respect to its concentration. The conversion of monomer at the end of the first stage is related to the initial catalyst concentration but not to the initial monomer concentration. Invoking the hypothesis of an instantaneous initiation reaction, the experimental results lead to the conclusion of the existence of a unimolecular termination step. Propagation‐to‐termination rate constant ratios yield a propagation–termination activation energy difference of 5.9 kcal/mole. The termination step proposed is thought to involve the formation of stable macrocyclic oxonium ions. These, in turn, can reactivate the polymerization by an intramolecular reaction leading to the formation of new active centers. An energy of activation of 8.7 kcal/mole was calculated for this reactivation. GPC analyses of the reaction products recovered at the end of the first stage revealed the presence of large proportions of oligomers. Based on kinetic data, the formation of oligomers is explained by a backbiting process similar to the reactivation reaction suggested for the initiation of the second stage.
Diffusion control in radiation graft polymerization with varying dependence of rate on monomer concentration
Authors: Imre Kaya , Odian George , Rabie Abdelgewad
Published: April 2003

The quantitative effect of diffusion control on the rate of radiation‐initiated graft polymerization has been studied theoretically for systems in which the diffusion‐free reaction may show various dependencies of rate on monomer concentration other than the usual first‐order dependence. The study is also very general in that it can be applied to systems involving a variety of different modes of initiation and termination. Whether the grafting process is diffusion‐free or diffusion‐controlled has been analyzed in terms of the interaction of the initiation rate Ri, the propagation and termination rate constants kp and kt, the equilibrium solubility M of the monomer in the polymer, the polymer film thickness L, the diffusivity D of the monomer in the polymer, and the diffusion‐free kinetic order of dependence v of the grafting rate on monomer concentration. The dependence of the grafting rate for both the diffusion‐free and diffusion‐controlled reactions on these parameters is expressed both by mathematical experssions and graphically. Diffusion control is shown to occur at a critical value of the parameter A which is proportional to L(kpRiw/ktzD)1/2M(ε−1)/2 where w, z, and v have different values depending on the specific modes of initiation, propagation and termination in a particular grafting system. The grafting rate is shown to vary with the value of A according to specific mathematical expressions. In comparing diffusion‐free to diffusion‐controlled reaction, it is shown that the former is independent of L and D while the latter is directly dependent on L and inversely on D1/2. Further, the change from diffusion‐free to diffusion‐controlled reaction involves a change in the dependence of rate on monomer from v‐order to [(v − 1)/2]‐order. The nonsteady‐state as well as the steady‐state reaction rates have been analyzed.
Study of radiation‐induced polymerization of vinyl monomers adsorbed on inorganic substances. X. Influence of H2O on the styrene–silica gel system
Authors: Fukano Kazuyuki , Kageyama Eiichi
Published: April 2003

To elucidate the reaction mechanism of radiation‐induced polymerization of the styrene—silica gel system, the influence of H2O as adsorbed water and inhibitor of cationic polymerization was investigated by two methods. Monomer conversion decreased as H2O increased. In general, percent grafting decreased as H2O increased, but the presence of a small amount of H2O increased the percent grafting. Grafting at 16 Mrad has a maximum value at a water content of about 0.2%. This seems to be due to two effects of H2O: percent grafting increases due to restraint of cationic polymerization by H2O, but the percent grafting decreases due to adsorption water which interrupts the contact of styrene with silica gel. In GPC spectra, the low molecular weight peaks of both graft polymers and homopolymers decreased when H2O was added. The GPC results suggest that the number of positive holes which initiate cationic polymerization is very large.
Some aspects of plasma polymerization investigated by pulsed R.F. discharge
Authors: Yasuda H. , Hsu T.
Published: April 2003

The polymerization of organic compounds in glow discharge (plasma polymerization) was investigated by using pulsed R.F. discharge (100 μsec on, 900 μsec off). The effects of pulsed discharge on polymer deposition rate, pressure change in plasma, ESR signals of free spins in both plasma polymer and substrate, and the contact angle of water on the plasma polymer surface were investigated for various organic compounds. The results are correlated to the mechanisms of polymer formation in plasma (plasma polymerization) which has been postulated as repeating processes of stepwise (propagation) reactions. The effect of the pulse is different from one group of organic compounds to another depending on whether or not they contain an olefinic double bond and/or a triple bond. The main difference seems to be the addition polymerization which can occur exclusively during the off‐period of pulsed discharge. Ultraviolet emission from pulsed discharge is much less than from continuous discharge. Consequently, the fragmentation of the monomer and the free‐radical formation in the substrate are less with the pulsed discharge. Properties of polymers from some organic compounds formed in continuous and in pulsed discharge were found to be significantly different, and the differences were postulated from the changes of polymerization mechanisms in the pulsed discharge.
Studies on never‐dried cotton
Authors: Kulshreshtha A. K. , Patel A. R. , Baddi N. T. , Srivastava H. C.
Published: April 2003

The differences in the porous and crystalline structure of cell walls in never‐dried and nature‐dried cottons have been examined by measurements of dye adsorption and desorption, centrifugal liquid retention, and decrystallization due to swelling in sodium hydroxide. Equilibrium dyeings of these two cottons have been carried out at 50 and 60°C with two direct dyes, Chlorazol Sky Blue FF and Chrysophenine G, and the adsorption isotherms obtained. The dye uptake at limiting saturation is found to be quite large for never‐dried cotton as compared to nature‐dried cotton, indicating a larger number of sites available to dye molecules in the former sample. However, dyeing parameters such as affinity and differential heat of dyeing are found to have lower values for never‐dried cotton. This is attributed to the “frozen” structure of a large amount of water held by never‐dried cotton, which retards the adsorption of dye molecules. Studies on retention of liquids (glycerol and water) by cotton by use of centrifugation techniques reveal a larger amount of pore volume in never‐dried cotton than in nature‐dried cotton. X‐Ray studies on decrystallization of cotton by swelling in NaOH indicate that the phase transformation to cellulose II in never‐dried cotton is complete at 25% (w/w) concentration of NaOH, whereas under identical swelling conditions about 10% residual, unconverted cellulose I is found in the case of nature‐dried cotton. A somewhat similar anomaly is found in the dye desorption measurements. Under conditions when the dye can be completely stripped from nature‐dried cotton, the never‐dried cotton has been shown to retain about 50% to 80% of the adsorbed dye. These observations are attributed to irreversible pore closure during drying of never‐dried cotton. Structural collapse occurring during drying of never‐dried cotton, after subjecting it to solvent exchange with a large number of organic liquids, was studied by x‐ray diffraction, optical microscopy, and centrifugal liquid retention techniques. It was demonstrated that the structural collapse is proportional to the polarity of the organic solvent employed in the final exchange of never‐dried cotton, prior to drying. It is concluded that the structural collapse and the development of inaccessible zones in fiber during drying can be reduced if the water in never‐dried cotton is exchanged with a nonpolar solvent.
Reactivity of polymer substituents. Aminolysis of p‐nitrophenyl ester residues attached to various polymer backbones
Authors: Su Chin‐Pao , Morawetz Herbert
Published: April 2003

Styrene, methyl acrylate, and N,N‐dimethylacrylamide were copolymerized with small proportions of p‐nitrophenyl acrylate or p‐nitrophenyl esters of CH2CHCONH(CH2)nCOOH (n = 1,3,5). The aminolysis of these copolymers in dioxane and chlorobenzene solution was compared with the corresponding reaction of low molecular weight analogs. The ratio of the reactivity of the polymer substituent and its analog was found to be insensitive to the nature of the amine but strongly dependent on the nature of the polymer backbone. Poly(dimethylacrylamide) chains carrying active ester substituents were in some cases much more reactive than their analogs due to the activating effect of the dimethylamide groups. In the case of the p‐nitrophenyl acrylate–styrene copolymer, the aminolysis exhibited a dispersion of the rate constant due to its sensitivity to stereoisomerism in the vicinity of the active ester, but no similar effects were observed with the other copolymers.
Polymerization of propylene carbonate
Authors: Soga Kazuo , Tazuke Yutaka , Hosoda Satoru , Ikeda Sakuji
Published: April 2003

Polymerization of propylene carbonate was carried out at 120–180°C mainly with the use of diethylzinc catalyst. The polymer was a pale‐yellow, viscous material of relatively low molecular weight (1000–4000). From the spectroscopic analysis of the polymer and its hydrolyzed product, the polymer was determined to have the structure
magnified image
where x ⋍ 0.50, y ⋍ 0.25, and z ⋍ 0.25. This strongly suggested that the polymerization of propylene carbonate proceeded via 2,7‐dimethyl‐1,4,6,9‐tetraoxaspiro[4,4]nonane (DTN) as an intermediate compound. Hence, DTN was synthesized and polymerized with the use of diethylzinc catalyst. The structure of the polymer thus prepared coincided exactly with that of the polymer from propylene carbonate. From these, a plausible mechanism of the polymerization was developed.
Termination rate constant in free‐radical polymerization
Authors: Mahabadi H. K. , O'Driscoll K. F.
Published: April 2003

The specific rate constant for the termination reaction between two flexible polymer molecules with active chain ends has been considered in relation to the segmental diffusion of chain ends in solution. The probability of reaction between two chain ends per unit time when the centers of gravity of two polymer molecules are at a distance of separation has been calculated by using the Smoluchowski equation and a Gaussian distribution of chain ends. The time during which two polymer molecules are in contact has also been calculated by using the diffusion equation and the potential energy function for intermolecular interaction. The rate constant may then be completely expressed as a complex function of the intramolecular linear expansion factor, molecular weight, and the frictional properties of the reacting polymers' segment. This expression predicts that the rate constant is inversely proportional to solvent viscosity, decreasing with increasing molecular weight to some extent, and is affected by the excluded volume effect and chain flexibility. The complete expression for the rate constant has been simplified and the result compared with experimental data. Close agreement is found between the calculated rate constants and those experimentally obtained.
Reaction of poly(vinyl alcohol) with tetravalent ceric ion
Authors: Ikada Yoshito , Nishizaki Yasuko , Iwata Hiroo , Sakurada Ichiro
Published: April 2003

Poly(vinyl alcohol) (PVAI) was oxidized by ceric ion, Ce(IV), in aqueous HNO3 medium at different temperatures and found to be degraded as a result of selective cleavage of the 1,2‐glycol unit existing in PVAl. The rate of oxidation increased with increasing temperature. The aldehyde groups formed at the ends of the degraded polymer upon oxidation were relatively stable at 0°C. With rise of temperature, the aldehyde groups reacted either with excess of Ce(IV) to carboxylic acids or with hydroxyl groups of PVAl molecules to give acetal linkage. When the acetalization predominated over the oxidation to carboxyl group, gelation of the reaction mixture was observed. Based on these results, a plausible mechanism of oxidation of PVAl with Ce(IV) and the subsequent reactions is discussed.
Vinyl polymerization. 351. Polymerization of methyl methacrylate initiated with α‐amylase and copper(II) ion in water
Authors: Imoto Minoru , Sakade Naoya , Ouchi Tatsuro
Published: April 2003

The polymerization of MMA initiated by a system of α‐amylase, cupric chloride, and water was carried out. The effects of the amounts of water, copper(II) ion, and MMA on the conversion of MMA were studied. The overall activation energy was estimated to be 55 kJ/mole. Urea, known as a denaturing agent for protein, was found to increase the rate of polymerization and efficiency of grafting onto α‐amylase.
Molecular weight distribution in thermal polymerization of styrene
Authors: Ito Katsukiyo
Published: April 2003

The molecular weight distribution in thermal polymerization, for which the termination rate is comparable with the transfer rate, is analyzed by assuming that (1) the termination rate is independent of chain length; (2) the rate is translational diffusion‐controlled; and (3) the rate is influenced by the excluded volume. The theoretical distribution, based on the assumption that the rate is translational diffusion‐controlled, is the best fit to the experimental data at high temperature. The dependence of the rate on chain length is stronger at higher temperature (>80°C). The ratio of the termination rate to the transfer rate increases with increasing temperature.
Reduction of poly(4‐vinylpyridine)‐coordinated ferriprotoporphyrin IX by N‐benzyl‐1,4‐dihydronicotinamide in N,N‐dimethylformamide
Authors: Tsuchida Eishun , Hasegawa Etsuo , Ohno Hiroyuki
Published: April 2003

The reduction of a ferriprotoporphyrin IX–pyridine or poly(4‐vinylpyridine) complex by N‐benzyl‐1,4‐dihydronicotinamide in N,N‐dimethylformamide to yield a corresponding ferro complex was studied kinetically and thermodynamically by spectral measurements. The reduction was confirmed to proceed via the intermediate. The rate of the reduction of the ferric iron was faster in the poly(4‐vinylpyridine) complex than in the pyridine complex. This was caused by the adsorption of the reductant to the polymer ligand, causing the increase in the frequency factor of the reaction.
Acceleration of aminolysis of nitrophenyl esters by quaternized modifications of polyethylenimine
Authors: Spetnagel Wayne J. , Klotz Irving M.
Published: April 2003

Derivatives of polyethylenimine, containing free primary amines but with secondary and tertiary amines fully quaternized, were prepared. The residual primary amines of the polymer markedly accentuated the rates of cleavage of nitrophenyl esters. This modified polymer exhibits a pKa, determined from kinetics of its reactions, close to that for small molecules with a primary amine adjacent to a charged aminoethyl group. Thus, the primary amine group of the polymer stays relatively distant from all charged nitrogens on the macromolecule except its immediately adjacent neighbor on the chain.
Cyclopolymerization of diallylsilanes
Authors: Billingham N. C. , Jenkins A. D. , Kronfli E. B. , Walton D. R. M.
Published: April 2003

A survey has been made of the polymerizability of diallysilanes, including a number of new compounds. Rates of polymerization are generally low with radical or Ziegler‐Natta techniques, but excellent yields are often obtained when the initiator is aluminum bromide.
Polymerizations of chloral, styrene oxide, and methyl methacrylate initiated by the binary system of bis(acetylacetonato)metal(II) and chloral
Authors: Uehara Kaku , Ohashi Yoshiyuki , Tanaka Makoto
Published: April 2003

The binary system of bis(acetylacetonato)metal(II) [M(acac)2] and chloral induced the polymerization of chloral [M = Mn(II), Co(II), Mg(II), and Cu(II)], the ring‐opening polymerization of styrene oxide [M = Co(II) and Mg(II)], and the radical polymerization of methyl methacrylate [M = Mn(II) and Co(II)]. The similar order of activity of M(acac)2 as the catalyst for the polymerization of chloral and for the aldol reaction of chloral with acetylacetone, the deactivation of the catalyst by the introduction of a substituent at the 3‐position of M(acac)2, the presence of saturated β‐diketone at the end of the polymer of chloral and that of styrene oxide, and the visible light spectral data supporting the formation of the β‐ketoalcoholate intermediate in the binary system of Co(acac)2 and chloral are all experimental findings which suggest that M(acac)2 is subject to the aldol addition by chloral at the 3‐position of the chelated acetylacetone and that the resultant β‐ketoalcoholate is a common active species for these polymerizations.
Effect of acid hydrolysis on accessibility of micropores and thermal transition of viscose rayon
Authors: Shinouda H. G. , Moteleb M. M. Abdel
Published: April 2003

The changes in micropores accessible to toluene but inaccessible to decalin taking place during acid hydrolysis of viscose rayon were followed by specific volume measurements. The results show that these changes at the different stages of hydrolysis are of different order and dependent on the hydrolytic conditions. Also, it was found that the decalin molecules, which are larger than toluene molecules, could not follow the gradual disappearance of the thermal transition of viscose rayon with the progress of hydrolysis.
Radical polymerization of methyl methacrylate in the presence of stereoregular poly(methyl methacrylate). VI. Kinetic template effects at higher conversion
Authors: Gons J. , Slagter W. O. , Challa G.
Published: April 2003

The kinetics of radical template polymerization of methyl methacrylate along isotactic poly(methyl methacrylate) as polymer template was studied. It appeared that in addition to a rate increase at low conversions, a second rate enhancement can take place at higher conversion, depending on the nature of the solvent and temperature. While the initial template effect was previously mainly ascribed to hindered segmental motion of propagation chain radicals, the second rate effect is thought to be caused by hindered translational motion of growing chains in a physical network built up during polymerization. The observed second effect is strong in the weakly complexing and network‐promoting solvent toluene, but it is less pronounced in the strongly complexing solvent dimethylformamide. In acetone, also a strongly complexing solvent, the formed stereocomplexes crystallize at low conversions. Due to this crystallization the propagating chains become immobilized, which also results in a strong second rate enhancement. The observed effects are dependent on temperature, but hardly depend on template molecular weight. The influence of the template is further demonstrated by varying its concentration and by the disappearance of the rate enhancement at higher conversion, when the templates become fully covered.
Radiation‐induced oxidation of solid poly(ethylene oxide). II. Mechanism
Authors: Decker Christian
Published: April 2003

The mechanism of γ‐initiated oxidation of solid poly(ethylene oxide) (PEO) has been investigated, and an overall reaction scheme has been developed which accounts for most of the experimental observations. Data are correlated on the basis that the oxidation process is the sum of two reactions that are first‐order and half‐order in rate of initiation. They provide evidence that a significant fraction of the interactions of α‐alkoxyalkylperoxy radicals is nonterminating at ambient temperature and yield free alkoxy radicals that are very subject to β scission. The unimolecular decomposition of secondary peroxy radicals, which has been invoked previously for the oxidation of PEO in solution, is not needed to explain the products of the oxidation of PEO in the solid phase. Approximately 90% of the total oxygen consumption has been accounted for by the observed products of oxidation. The radiochemical yield for backbone radical formation in irradiated PEO was estimated to be 6.5 ± 1.5.
Oligomérisation anionique de l'ethylène. II. Etude des paramètres thermodynamiques
Authors: Magnin Henri , Rodriguez Firmin , Abadie Marc , Schué François
Published: April 2003

A kinetic study, as a function of temperature, of ethylene oligomerization by the n‐BuLi–TMEDA complex allowed us to evaluate the thermodynamic parameters (ΔS‡ < −23.7 u.e.) and thus to support a transition state where the ethylene is coordinated to the lithium atom.
Polymerization and properties of optically active α‐(p‐substituted benzenesulfonamido)‐β‐lactones
Authors: Jarm V. , Fleš D.
Published: April 2003

Optically active α‐(p‐substituted benzenesulfonamido)‐β‐lactones having as para substituents OMe, Me, H, and Cl were polymerized in bulk, in ethyl acetate solution with triethylamine or betaine, and in dioxane with butyllithium as initiators. The rate of polymerization was followed by the change of specific rotation with time and was decreasing in following order of para substituents: OMe > Me > H > Cl. The relative reactivity in logarithmic form was plotted against Hammett's σ functions showing a linear relationship with reaction constant ρ = −0.57.
Thermosetting acetylene‐terminated polyphenylquinoxalines
Authors: Kovar Robert F. , Ehlers Gerhard F. L. , Arnold Fred E.
Published: April 2003

A series of acetylene‐terminated phenylquinoxaline oligomers have been prepared which cure by addition, without the evolution of volatiles. The synthesis utilized the novel terminal acetylene end‐capping reagent, 3‐(3,4‐diaminophenoxy)phenylacetylene. The end‐capped oligomers were soluble (20–30%) in low‐boiling organic solvents and exhibited a high degree of flow at their softening temperatures. Thermal analytical data obtained on the oligomers indicated initial softening in the vicinity of 160°C and a strong polymerization exotherm reaching a maximum at 274°C. Cured samples (8 hr at 280°C) exhibited Tg values of approximately 320°C. Mass spectrometry–thermogravimetric analysis of the polymers demonstrated that no volatiles were emitted during cure, and that decomposition of the resins initiated at 465°C. Synthetic routes to the acetylene terminated phenylquinoxaline oligomers and the end‐capping reagent are discussed as well as the physical properties of the oligomer and cured system.
Mass spectral and pyrolysis/gas‐chromatographic studies of the monomer and polymer of bis(p‐toluenesulfonate) of 2,4‐hexadiyne‐1,6‐diol
Authors: Ghotra J. S. , Stevens G. C. , Bloor D.
Published: April 2003

The thermal degradation of the monomer and polymer of bis(p‐toluenesulfonate) of 2,4‐hexadiyne‐1,6‐diol has been investigated. Decomposition during the latter stages of solid‐state thermal polymerization at 80°C and of 100% polymer at 112°C was observed by mass spectrometry and the decomposition fragments identified. Mechanisms for this low‐temperature degradation are suggested. Pyrolysis of the monomer and polymer between 400 and 1000°C was studied by gas chromatography and mass spectrometry. The principal pyrolysis products are triacetylene and p‐toluenesulfonic acid. The fragmentation routes leading to and derived from these products are discussed.
Polyarylaminophosphazene copolymers
Authors: White Jerry E. , Singler Robert E.
Published: April 2003

A series of polyarylaminophosphazene copolymers have been prepared and are described. In each preparation, two arylamines were allowed to competitively react with polydichlorophosphazene, and the substituent ratios of the resulting copolymers, determined by high‐temperature 1H‐NMR spectroscopy, generally reflect expected steric and electronic effects on the relative reactivities of the arylamines studied. The copolymers have intrinsic viscosities of 0.64–1.25 dl/g, glass transition temperatures of 75–104°C, and decomposition temperatures of 220–260°C. These properties, which are comparable to those of polyarylaminophosphazene homopolymers, are discussed in regard to what they may reflect about the structure of the polymers.
Thermal decyanation, a new organic reaction. II
Authors: Haas Howard C. , Moreau Robert D.
Published: April 2003

When heated in solution at about 160°C, pyridine quaternary salts of bromomalonamides lose 1 mole of cyanic or isocyanic acid almost quantitatively in a manner quite analogous to the decarboxylation of an acid. By DTA and DSC, the crystalline salts are stable up to their melting points (>220°C) at which temperatures concurrent fusion and decyanation processes occur (endotherm); these are immediately followed by an exotherm related to the trimerization of cyanic acid. TGA measurements on the solid salts do not clearly define the loss of 1 mole of cyanic acid because in the solid state, thermal decyanation is accompanied to some extent by other pyrolytic reactions. Preparative methods for quaternizing poly(4‐vinylpyridine) with bromomalonamide are described and two polymeric quaternary salts (33 and 100% substituted) were prepared and analyzed. These polyelectrolytes are water soluble and upon the addition of base the yellow polymeric nitrogen ylids are generated. Infrared spectra on the polymeric quaternary salts and visible spectra on the polymeric ylids are included. The ylid chromophore has an ε = 1800 at λmax = 415 nm. The dilute solution viscosity behavior of these polymers in H2O and in 0.05N KBr is typical of polyelectrolytes. Both polymers in dilute solution show a maximum in ηsp versus pH plots. In water, the viscosity of these polymers decreases with time, and it is proven that this results from a conformational change which accompanies amide hydrolysis rather than polymer backbone degradation. Glass transitions are not detectable by DTA but both polymers show well‐defined trimerization exotherms for cyanic acid starting at 170–175°C. Thus, decyanation of the solid polymeric quaternary salts is more analogous to decyanation of the crystalline quaternarys in solution than as solids. TGA measurements on the polymers show weight losses which are of the correct order of magnitude and in the correct temperature range for monodecyanation. Some data are presented which suggest that perhaps a second mole of cyanic acid is lost at about 250°C. Quaternization of poly(4‐vinylpyridine) with bromomalonamide reduces its gross decomposition temperature from 385°C to about 285–317°C. It is demonstrated how thermal decyanation can be used for the in situ generation of cyanic acid for the modification of organic compounds. The preparation of a partial urethane of poly(vinyl alcohol) using this method is described. We have also shown that aliphatic quaternary salts can be prepared and that they too undergo the decyanation reaction.