bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐resolution proton magnetic resonance and infrared spectra of poly(vinyl formal) and its model compounds
Authors: Shibatani Kyoichiro , Fujiwara Yuzuru , Fujii Kiyoshi
Published: April 2003

High‐resolution proton magnetic resonance and infrared spectra of poly(vinyl formal) were studied in comparison with those of the model formals obtained from stereoisomers of pentane‐2,4‐diol and heptane‐2,4,6‐triol in order to learn spectral changes due to differences of the steric structures of the polymer. In the NMR spectrum of transformal obtained from dl diol or dl,dl (syndiotactic) triol, all proton signals were well interpreted by assuming a rapid chair‐chair inversion of the formal ring. On the other hand, no such inversion was observed spectroscopically in cis‐formal obtained from the meso diol or meso,meso (isotactic) triol, and the cis‐formal ring was supposed to take a diequatorial form preferentially. Consequently, dioxymethylene protons gave a single peak (equivalent) in trans‐formal and an AB quartet (nonequivalent) in cis‐formal. In the spectra of poly(vinyl formal), the dioxymethylene signal was an overlap of the singlet and quartet in dimethylsulfoxide solution. Observations of the spectra of various poly(vinyl formals) obtained from poly(vinyl alcohols) of different tacticities and study of temperature dependence of the signal have shown that the singlet and quartet are attributed to trans‐ and cis‐ formals, respectively, in the polymer spectrum also. In the infrared spectra of poly(vinyl formals), the 800 and 785 cm‐1 bands were found to be related to cis‐ and trans‐formal rings respectively. A linear relationship was confirmed between D785/D800 and trans/cis ratios determined from the peak intensities of the dioxymethylene proton signals.
Termination rate constants in radical polymerization
Authors: Ito Katsukiyo
Published: April 2003

A rate constant is generally derived by using Fick's equation corresponding to the spherical interdiffusion of particles. By using this rate constant, chain and primary radical termination rate constants can be approximated to rate constants for the bimolecular reactions between two radical chain ends, and primary radical and radical chain end, respectively. The former is given by ks = 8πNLDsLs exp { − Ls/Rs} × 10−3 1./mole‐sec. The latter is given by ksi = 4πNL(Ds + Di)Lsi exp { − Lsi/Rsi} × 10−3 1./mole‐sec. Here, NL is Avogadro's number; Ds and Di are the diffusion constants of radical chain end and primary radical, respectively; Ls and Lsi are, respectively, the distances between two radical chain ends and between a primary radical and a radical chain end at a thermal energy equal to the coulombic energy of interaction of the net charges; and Rs and Rsi are, respectively, the average distances between two radical chain ends and primary radical on a collision.
Electron spin resonance studies on graft copolymerization of gaseous styrene onto preirradiated polypropylene. I. Preirradiation in the presence of oxygen
Authors: Eda Bunzo , Nunome Keichi , Iwasaki Machio
Published: April 2003

Graft copolymerization of gaseous styrene was carried out onto polypropylene preirradiated in the presence of oxygen at −78°C and at room temperature, respectively. The origin of the graft initiation activities of these polymers was investigated by means of electron spin resonance (ESR) of trapped radicals. More grafting was found for the polymers irradiated at −78°C than for those irradiated at room temperature. The difference of grafting between polymers irradiated at −78°C and those irradiated at room temperature was not explained by the total amounts of trapped radicals, and it was found that all radicals are not effective in the grafting reaction. ESR measurements showed that there exist two kinds of peroxy radicals, one has more effective ability of abstracting hydrogen atoms from the surrounding polymer chains to form carbon radicals, and another is less effective at the temperature of grafting reaction (40°C). Although the samples irradiated at −78°C contain the both types of radicals, those irradiated at room temperature do not contain the former type of radicals. It was shown that the carbon radicals produced by such a hydrogen abstraction reaction are actually the effective centers in the grafting reaction of polymers irradiated in the presence of oxygen.
Studies on monomer reactivity ratios. III. Comparison of various mathematical models
Authors: Hoyland James R.
Published: April 2003

Seven mathematical models for the treatment of monomer reactivity ratios in free‐radical copolymerization are compared from the viewpoint of their relative simplicity, accuracy, and the number of parameters necessary for their use. It is concluded that the electronegativity and charge‐transfer models proposed in previous papers represent the best compromise for routine usage if quantitative accuracy is the primary concern.
High‐temperature pyrolysis of poly(vinyl chloride): Gas chromatographic‐mass spectrometric analysis of the pyrolysis products from PVC resin and plastisols
Authors: O'Mara Michael M.
Published: April 2003

A pyrolysis–gas chromatographic–mass spectrometric technique for analyzing the pyrolysis products from polymers in an inert atmosphere is described. Initial studies encompassing the pyrolysis of poly(vinyl chloride) homopolymer and a series of PVC plastisols (based on o‐phthalate esters) have provided a complete qualitative and semi‐quantitative analysis of the pyrolysis products from these materials. PVC resin yields a series of aliphatic and aromatic hydrocarbons when pyrolyzed at 600°C; the amount of aromatic products is greater than the amount of aliphatic products. Benzene is the major organic degradation product. A typical PVC plastisol [PVC/o‐dioctyl phthalate (100/60)] yields, upon pyrolysis, products that are characteristic of both the PVC matrix and the phthalate plasticizer. The pyrolysis products from the plasticizer dilute those from the PVC portion of the plastisol and are, in turn, the major degradation products. There are no degradation products resulting from an interaction of the PVC with the plastisol. The pyrograms resulting from pyrolysis of the various plastisols of PVC can be used for purposes of “fingerprinting.” Identification of the major peaks in a typical plastisol pyrogram provides information leading to a precise identification of the plasticizer. The pyrolysis data from this study were related to a special case of flammability and toxicity.
Polymerization of acrylonitrile catalyzed by methoxo‐β‐diketone nickel chelates
Authors: Shono T. , Mori M. , Shinra K.
Published: April 2003

The polymerization of acrylonitrile initiated by methoxo‐β‐diketone nickel chelates of the [Ni(L)(CH3O)(CH3OH)]n type and pyridine was studied. Chelating agents L employed included acetylacetone, ethylacetoacetate, and salicylaldehyde. These systems could initiate the polymerization of acrylonitrile at −40°C. The polymerization is thought to occur by an anionic coordination mechanism.
1,2‐dinitrile polymers. III. Number‐average molecular weight by pulsed NMR technique
Authors: Liepins R. , Crist B. , Olf H. G.
Published: April 2003

In studies of various polymers in the solid state by pulsed and wide‐line NMR, a relationship between the spin‐lattice relaxation time and the fraction of mobile protons in the polymer sample was observed. This effect has been used to determine the degree of polymerization of a series of fumaronitrile homopolymers. The technique should have wide applicability in the direct determination of the number‐average molecular weight M̄n, especially for polymers that may be insoluble and/or infusible though not crosslinked.
Ladder polymers from tetraaminodiquinoxalpyrene
Authors: Arnold F. E.
Published: April 2003

A new fused aromatic heterocyclic tetraamine 2,3,11,12‐tetraaminodiquinoxal [2,3‐e,2′,3′‐1] pyrene has been prepared and polymerized with 1,4,5,8‐naphthalenetetracarboxylic acid and pyromellitic dianhydride. The resulting ladder polymers with inherent viscosities ranging from 0.5 to 1.0 dl/g in methanesulfonic acid exhibited thermal stabilities near 600°C in nitrogen and near 450°C in air.
Synthesis of spiro polymers,
Authors: Bailey William J. , Volpe Angelo A.
Published: April 2003

Synthesis of the first totally organic spiro polymer was accomplished by the reaction of 1,4‐cyclohexanedione and pentaerythritol in benzene plus a trace of p‐toluenesulfonic acid to produce the polyspiroketal. The polymer did not melt, but began to decompose at 350°C. Although it was insoluble in most common solvents, it was found to be soluble in hexafluoroisopropanol. The x‐ray diffraction indicated the polymer was very highly crystalline. A series of lower molecular weight related polymers were prepared by carrying out a similar condensation with a mixture of 1,4‐cyclohexanedione containing 5–50 mole‐% of cyclohexanone. In order to prepare a material with greater solubility, a polyspiroketal was prepared from 1,10‐cyclooctadecanedione plus pentaerythritol. This polymer was soluble not only in hexafluoroisopropanol, but to a limited extent in dimethyl sulfoxide.
Cyclic amine initiation of polypivalolactone
Authors: Wilson D. R. , Beaman R. G.
Published: April 2003

Certain monocyclic and polycyclic tertiary amines initiate polymerization of, and copolymerize with, pivalolactone. These comprise three‐, four‐, and five‐membered monocyclic amines and 1‐azapolycyclic amines. The polymerization proceeds in three steps: (a) initiation to form a cyclic amine/pivalate betaine, (b) propagation to yield a polylactone zwitterion by an anionic mechanism, and (c) interlinking by a carboxylate end attacking a cyclic amine end to incorporate amine as a comonomer in the chain. When polymerization is carried out at low temperatures, the more stable cyclic amine ring systems yield isolatable step b polymers. These polymeric zwitterions undergo step c by heating, even in the solid state. The mechanism suggests that, for the more labile cyclic amines, a lactone could be the initiator for polyamine formation by a cationic mechanism. Interlinking would lead to incorporation of lactone initiator. In intermediate cases, block copolymers would result. With a proper balance of reactivities, 1:1 alternating copolymers would be possible.
Block copolymer from α,ω‐dihydroxyl polystyrene and polyethylene glycol
Authors: Shimura Yukio , Lin Wen‐Shi
Published: April 2003

α,ω‐Dihydroxyl polystyrene was synthesized by the addition of styrene oxide to polystyryl dianion initiated with sodium naphthalene. Diglyme was found to be an unsuitable solvent for the preparation of low molecular weight compounds. Block copolymerization of the α,ω‐dihydroxyl polystyrenes (M̄n = 2250, 3140, and 6200) with poly(ethylene glycols) (M̄n = 404, 1960, and 5650) was pursued by introducing urethane linkages with 4,4′‐diphenylmethane diisocyanate. The mechanical, thermal, and viscoelastic properties, solution viscosity, molecular weight distribution, and moisture absorption of the block copolymers obtained were examined. Incorporation of styrene blocks was found to disturb the crystallization and fusion of poly(ethylene glycol) blocks. Films cast from benzene solution were soft and elastic and absorbed up to 5.8% moisture.
Hydrocarbon ladder aromatics from a Diels‐Alder reaction
Authors: Stille J. K. , Noren G. K. , Green L.
Published: April 2003

The Diels‐Alder homopolycycloaddition of 2,5‐diphenyl‐3,4‐(5,6‐acenaphthylenylene)‐cyclopentadienone (VIII) affords a low molecular weight soluble ladder polymer having reduced specific viscosities between 0.17 and 0.25 dl/g in benzene and an insoluble fraction of higher molecular weight. The ladder polymers exhibited a major TGA break at 450°C in an air atmosphere and lost approximately 30% of their weight at 700°C in a nitrogen atmosphere.
Synthesis of inherently dissymmetric polyamides,
Authors: Overberger C. G. , Yoshimura T. , Ohnishi A. , Gomes A. S.
Published: April 2003

The preparation of polyamides from derivatives of optically active biphenic acid is described. The diacid chlorides chosen were 2,2′‐dinitro‐6,6′‐dimethylbiphenyl‐4,4′‐dicarbonyl chloride and 2,2′‐dichloro‐6,6′‐dimethylbiphenyl‐4,4′‐dicarbonyl chloride, the diamines were phenyldiamines (o‐, m‐, p‐) piperazine, trans‐2,5‐dimethylpiperazine, and 1,2‐piperaazolidine. Polymerization was carried out by the method of interfacial polycondensation. The polymers of aromatic diamines were insoluble in common organic solvents but soluble in dimethylformamide containing 5% lithium chloride, triesters of phosphoric acid, and methanesulfonic acid. The polymers of aliphatic diamines were also insoluble in common organic solvents but soluble in trifluoroethanol. All polymers had melting points higher than 280°C.
Transformations of chloroethylenes in the presence of aprotonic acids
Authors: Zilberman E. N. , Kulikova A. E. , Pinchuk N. M. , Taikova N. K. , Okladnov N. A.
Published: April 2003

The cationic polymerization of vinyl chloride, vinylidene chloride, and cis‐ and trans‐ 1,2‐dichloroethylenes with the use of Lewis acid‐type catalysts has been studied. Vinylidene chloride is smoothly polymerized in the presence of ZnCl2 at 40°C to form the dimer, 1,1,3,3‐tetrachlorobutene‐1, and poly(vinylidene chloride) having somewhat increased crystallinity (45%). Vinyl chloride is polymerized very slowly in the presence of AlCl3 and TiCl4 to give dimeric, trimeric, tetrameric, and low molecular weight polymer products. The polymerization is followed by carbonium ion isomerization that leads to reaction products of branched structure. The cis‐ and trans‐1,2‐dichloroethylenes react in the presence of AlCl3 only at 50–60°C, and their polymerization is terminated at the stage of dimer and cyclic trimer formation. A mechanism of carbonium ion‐initiated polymerization of chloroethylenes is proposed, and the causes which lead to early termination of polymerization are discussed.
Photochromic polypeptides
Authors: Vandewyer P. H. , Smets G.
Published: April 2003

Two photochromic polypeptides were synthesized by reaction of 1‐(4‐iodobutyl)‐3,3‐ dimethylindolindolino‐6′‐nitrobenzospiropyran with poly‐L‐tyrosine; their molar contents on photochromic units were 27.3 and 44.7%. The spectra of the photo‐induced merocyanines and their decoloration kinetics were compared with these of the monomeric model compound, obtained by reaction of the same N‐(4‐iodobutyl)‐indolinospiropyran derivative with N‐acetyltyrosine methyl ester. Different types of solvents have been examined, mainly dimethylformamide and pyridine, acetone and tetrahydrofuran, and methanol and ethylene glycol. The polypeptides showed a much less pronounced solvatochromism than their model; on the other hand, their absorption spectra presented two absorption maxima instead of one for the model. These differences in photochromic behavior were interpreted on the basis of the solvatation of the polymeric chain. Inverse photochromism was observed for polypeptide P2 as well as for the model in ethylene glycol solution; this effect is due to a higher merocyanine content at the thermal equilibrium spiropyran ⇌ merocyanine in high polar solvent.
Kinetics of thermal and acidic degradation of poly‐1,3‐dioxolane
Authors: Kumpanenko E. N. , Varshavskaya A. I. , Karmilova L. V. , Enikolopyan N. S.
Published: April 2003

The kinetics and parameters of thermal and acidic degradation of poly‐1,3‐dioxolane were investigated in order to elucidate the mechanism of degradation and to obtain information on the nature of active centers. Both homolytic and heterolytic breaking of a macromolecule were shown to be random and occur at the acetal bond. Thermal degradation was found to proceed in two stages, depending on temperature and involving active centers of a different nature, i.e., macroions and macroradicals. The rate‐determining step of thermal degradation appears to be one involving the radical component, similarly to thermal degradation of olefin polyoxides. Acidic degradation occurs solely by the depolymerization mechanism, as in the case of polyaldehydes. It was concluded that the degradation mechanism depends not only on the chain structure and the thermodynamic properties of the system, but also on the nature of active centers.
Polymerization of coordinated monomers. V. Polymerization of methyl methacrylate–Lewis acid complexes
Authors: Hirai Hidefumi , Ikegami Tadashi
Published: April 2003

The polymerization of the complex of methyl methacrylate with stannic chloride, aluminum trichloride, or boron trifluoride was carried out in toluene solution at several temperatures in the range of 60° to −78°C by initiation of α,α′‐azobisisobutyronicrile or by irradiation with ultraviolet rays. The tacticities of the resulting polymers were determined by NMR spectroscopy. Both the 1:1 and the 2:1 methyl methacrylate–SnCl4 complexes gave polymers with similar tacticities at the polymerization temperatures above −60°C. With decreasing temperature below −60°C, the isotacticity was more favored for the 2:1 complex, whereas the tacticities did not change for the 1:1 complex. On the ESR spectroscopy of the polymerization solution under the irradiation of ultraviolet rays at −120°C, the 1:1 SnCl4 complex gave a quintet, while the 2:1 SnCl4 complex gave both a quintet and a sextet. The sextet became weaker with increasing temperature and disappeared at −60°C. This behavior of the sextet corresponds to the change of the tacticities of polymer for the 2:1 SnCl4 complex. An intra–intercomplex addition was suggested for the polymerization of the 2:1 complex, which took a cis‐configuration on the basis of its infrared spectra. The sextet can be ascribed to the radical formed by the intracomplex addition reaction, while the quintet can correspond to that formed by the intercomplex addition reaction. The proportion of the intracomplex reaction was estimated to be about 0.25 at −75°C, and the calculated value of the probability of isotactic diad addition of the intracomplex reaction was found to be almost unity.
Synthesis and properties of some linear oligobenzyls and polybenzyls
Authors: Montaudo G. , Bottino F. , Caccamese S. , Finocchiaro P. , Bruno G.
Published: April 2003

Properties of some linear oligobenzyls corresponding to polybenzyl, poly(2,5‐dimethylbenzyl), and poly(2,3,5,6‐tetramethyl‐benzyl) systems are correlated to those of relative polymers. From infrared and x‐ray diffraction data, evidence is found that
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oligomers tend to assume the same crystal structure of the polymer as early as teh tetramer or pentamer stage. Syntheses of oligomers are described. Linear, crystalline polymers, necessary for comparison with oligomers, have been prepared and characterized. Polymerization conditions have been explored to some extent; relevant data are tabulated and discussed.
The role of solvent polarity and cocatalyst structure in the cationic polymerization of 3,3‐bis(chloromethyl) oxetane
Authors: Penczek I. , Penczek St.
Published: April 2003

In the cationic polymerization of 3,3‐bis(chloromethyl)oxetane induced by BF3 the solvent polarity (toluene, methylene chloride, ethylene chloride, nitrobenzene, and nitromethane) does not influence the ktr/kp ratio, where ktr stands for the rate constant of chain transfer to polymer. Increase of the overall polymerization rate is due mainly to the increase of ki. The application of the steady‐state conditions in which the slow formation of the active centers is compensated by the unimolecular chain transfer to polymer allowed the determination of ktr/kp ratios for several chain‐transfer agents of low molecular weight. Alcohols and ethers of different basicities were used. It was established that the ktr/kp ratio is a linear function of −pKa of the chain‐transfer agents.
Use of carbon suboxide to obtain block and graft copolymers. I. Grafting of carbon suboxide on polyamide 6
Authors: Bukowski Andrzej , Porejko Stanislaw
Published: April 2003

Polyamide 6 in the form of film was grafted by gaseous carbon suboxide in the form of toluene solutions. The influence of temperature on the extent of grafting was studied. It was concluded that in a sufficiently high temperature a copolymer of high structure appears. The influence of substances that initiate homopolymerization of suboxide upon the course of grafting reaction was studied. It was found that the substances do not increase the effectiveness of grafting. However a significant increase of effectiveness of grafting is produced by introducing into the reaction environment some small quantities of methanol. By the addition of methanol a graft copolymer of a maximum effectiveness of 43.1% was obtained. The copolymer was subjected to further tests and appeared to be c.l. poly(amide‐6–g‐carbon suboxide). Additional tests indicated that the polyamide film graft with carbon suboxide shows some interesting properties.
A polyamide from anthraquinonediketene
Authors: Dutt Prabir K. , Marvel C. S.
Published: April 2003

A polyamide has been synthesized by condensing anthraquinonediketene with m‐phenylenediamine (η = 0.62; 0.5% concentration in dimethylacetamide, 30°C). The polymer was not thermostable but decomposed rapidly above 275°C.
The morphology of the monomer–polymer particle in styrene emulsion polymerization
Authors: Grancio M. R. , Williams D. J.
Published: April 2003

A heterogeneous model for the monomer–polymer particle in styrene emulsion polymerization is presented. In this model, the growing particle consists of an expanding polymer‐rich core surrounded by a monomer‐rich shell which serves as the major locus of polymerization. This core‐shell model was suggested by kinetic studies with continuously uniform latices which showed that the systems of interest were of the Smith‐Ewart case II type but that the dynamic—as opposed to equilibrium swelling—particle monomer concentrations were continuously variable. Supporting evidence for the suggested morphology was obtained by electron microscope observation of ultrathin sections of latex particles.
Ethylene polymerization catalysis over chromium oxide
Authors: Hogan J. P.
Published: April 2003

A study of the nature of polymerization catalysis over CrO3–silica and of the nature of the polyethylene obtained is presented. A fixed surface chromate (or possibly dichromate) species was shown to be activated for polymerization by an oxidation–reduction reaction with the monomer or with other reactive compounds such as CO. A change in catalyst color from orange to blue occurred simultaneously, and an indigoblue color was present only during ethylene addition, indicating involvement of Cr d orbitals. A spectacular chemiluminescence, due to excitation of oxygen, occurred when CO‐treated catalyst was exposed to air. Active site population and the rate at which each site produced polymer molecules were calculated. A reaction mechanism compatible with the experimental data is depicted.
Double‐bond isomerization and hydrogenation in polyethylene with soluble nickel catalysts
Authors: Witt D. R. , Hogan J. P.
Published: April 2003

Polyethylene exhibits an increase in melt viscosity (melt index drop‐off) when subjected to extreme thermal treatment. Although stabilizers and antioxidants do not prevent this change it has been possible to stabilize high‐density polyethylene by isomerization or hydrogenation of the polymer unsaturation. A soluble nickel octoate–triethylauminum complex was an active catalyst system for these reactions. A triethyl‐aluminum/nickel ratio of three appeared optimum for maximum activity. Of particular interest regarding this catalyst system was the fact that the terminal vinyl unsaturation of the polymer had to be isomerized to some internal position before hydrogenation commenced. However, when this catalyst system was impregnated on a predried silica or when butyllithium was substituted for triethylaluminum, both isomerization and hydrogenation occurred simultaneously. The addition of a light olefin such as ethylene to the reaction mixture slowed the overall reaction until most of the ethylene had been hydrogenated. At this point the isomerization–hydrogenation reaction path previously mentioned commenced.
Post‐irradiation free‐radical reactions in poly(ethylene terephthalate)
Authors: Campbell D. , Monteith L. K. , Turner D. T.
Published: April 2003

Exposure of poly(ethylene terephthalate) to γ‐rays results in the formation of radical I, radical II (tentatively), and to an unassigned radical (III) which is responsible for a
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central peak in the ESR spectrum. It is believed that completely amorphous samples of polymer contain radicals II and III. On heating, the radicals decay, and the relative proportion of radical III increases. The kinetics of the overall decay process were followed by measuring the decrease in peak height with time. After an initially rapid reaction the decay of the radical population conformed to second order kinetics. An Arrhenius plot of the logarithm of specific rate versus 1/T indicated two lines which intersected at 72°C, which is close to the glass transition temperature. The activation energies were 112 kcal/mole above 72° and roughly 25 kcal/mole below 72°C. Reference to reports in the literature suggests that this decay can be explained by long‐range movement of the polymer molecules, even in the glassy solid. The decay of radical I in the crystalline regions of an oriented sample was shown to follow first‐order kinetics. As the decay occurs at temperatures as low as 100°C (the melting point is about 260°C), it seems that decay by normal physical movement is unlikely. The results might be explained by invoking the hypothesis of chemical migration of free radical sites by hydrogen atom hopping.
A convenient technique for determination of reactivity ratios
Authors: Mano Eloisa B. , De Almeida Roberto Riva
Published: April 2003

A new technique to determine the reactivity ratios for monomers is described. It is based on vapor‐phase chromatography and can be used for any volatile monomer. A new simplified equation was deduced which permits the direct use of the retention times to obtain the pair r1r2. The method is suggested for use in determination of the molar ratios of the chemical units in the polymer chain, regardless of chemical composition or constitution. The simplicity of this technique allows its use for monomer–polymer systems composed of any number of volatile monomers. The validity of this method was checked by using the pair methyl methacrylate–styrene. This technique is also being applied to the study of kinetics in polymerizations, since it allows the measurements of several samples taken from a single experiment.
Charge‐transfer complexing in polymer mixtures. IV. Acceptor polymers from nitrophthalic acids and their mixtures with donor polymers from aryliminodiethanols
Authors: Sulzberg Theodore , Cotter Robert J.
Published: April 2003

A series of electron acceptor polyesters was prepared from 5‐nitroisophthalic, nitroterephthalic, and 4,6‐dinitroisophthalic acids. Those polymers prepared at high molecular weight were tough, soluble, linear materials of well‐defined structure. These materials were mixed with electron‐donor polymers based on aryliminodiethanols where the aryl group was phenyl, p‐anisyl, 2,5‐dimethoxyphenyl, and 3,4,5‐trimethoxyphenyl. The effects of the mixtures on the mechanical, spectral, viscometric, and conductive properties were studied and compared to the component polymers.
Polymerization of monolayers of vinyl and divinyl monomers
Authors: Beredjick N. , Burlant W. J.
Published: April 2003

Monolayer balance techniques have been used to study “two‐dimensional” polymerization of monomolecular films of octadecyl methacrylate and a divinyl ester. Polymerizations were initiated with ultraviolet radiation, and reaction rates and properties of the product evaluated from surface pressure–area isotherms. The polymerization rate of the acrylate in argon is linear up to 70% conversion; the product obtained in this way exhibits an isotherm which may reflect the packing and orientation of the starting monolayer. Rate data for the divinyl system—the product of which should be a sheet‐like, two‐dimensional analog of a network system—exhibit no unusual features.
Syntheses and reactions of ferrocene‐containing polymers. III. Cyclopolymerization of 1,1′‐divinylferrocene
Authors: Kunitake Toyoki , Nakashima Toshihide , Aso Chuji
Published: April 2003

1,1′‐Divinylferrocene was polymerized with BF3OEt2 and AIBN initiators. Polymers were separated into benzene‐soluble and benzene‐insoluble fractions, the latter probably being crosslinked. The polymers obtained with BF3OEt2 were shown by infrared and NMR spectroscopy to contain both cyclized (70–80%) and uncyclized units, whereas the radical polymer consisted of more than 96% cyclized units. The benzene‐soluble fraction of the cationically obtained polymer softened at temperatures below 150°C, but the insoluble fraction decomposed at 240°C. The radical polymers were stable up to 250–280°C (dec).
Number of crosslinked monomer units per weight‐average primary chain at the gel point in the emulsion polymerization of 1,3‐dienes
Authors: Dannals L. E.
Published: April 2003

Without new assumptions, it is demonstrated that at the gel point in mercaptanregulated, 1,3‐diene emulsion polymerizations, the number of crosslinked monomer units per weight‐average primary chain is larger than one. The divergence of this number from one increases as the nonrandomness of the crosslinked monomer units distribution and the heterogeneity of primary chain size increase. According to the available experimental data, this number ranges from 1.11 to 1.29. Crosslink density values and rate constants of crosslinking to propagation, which were calculated assuming this number to be one, are consequently increased. It is also demonstrated, for postulated systems, that this number may be larger or smaller than one, depending on the type of nonrandomness of the crosslinked monomer units distribution. In either case, the divergence of this number from one also increases as the nonrandomness of the crosslinked monomer units distribution and the heterogeneity of primary chain size increase.
Studies on the polymerization of methyl methacrylate activated by azobisisobutyramidine
Authors: Gupta Satyendra Nath , Nandi Uma Shankar
Published: April 2003

Kinetic studies on methyl methacrylate polymerization were carried out with watersoluble 2,2′‐azobisisobutyramidine (ABA). The rate of polymerization was proportional to the square root of the initiator concentration in the solvents chloroform, methanol, and dimethyl sulfoxide (DMSO), which confirms the bimolecular nature of the termination reaction. The monomer exponent was unity in chloroform but in methanol and DMSO the rate of polymerization passed through a maximum when plotted against the monmer concentration. This behavior in methanol has been attributed to be due to the enhanced rate of production of radical with increasing proportion of methanol. The rate of decomposition of the ABA has been observed to be faster in methanol than in chloroform. The situation becomes more complicated with DMSO, which was found to reduce the value of δ = (2kt)1/2/kp in methyl methacrylate polymerization. The rate of polymerization was observed to be highly dependent on the nature of the solvent, the rate increasing with increased electrophilicity of the solvent. The dependence of Rp on the solvent has been explained in the light of the stabilization of the transition state due to increased solvation of the basic amidine group of the initiator with the increased electrophilicity of the solvent.
Radiation‐induced postpolymerization of trioxane in the solid state. II. Kinetic study of radiation‐induced postpolymerization of trioxane in dry and high‐vacuum system
Authors: Ishigaki Isao , Ito Akihiko , Iwai Tadashi , Hayashi Koichiro
Published: April 2003

A kinetic study of the radiation‐induced postpolymerization of trioxane in the solid state has been made. Trioxane was purified by sublimation through Ag2O and Na–K alloy in vacuo and was both irradiated and polymerized in a super‐dry system under high vacuum. In the present study it was found that the initial rate of polymerization is larger than that reported previously. It is reasonably suggested that the postpolymerization of trioxane consists of two stages, i.e., a very large rate at the first stage and a relatively small one at the second stage. By using the kinetic scheme proposed previously kinetic parameters at the second stage were determined. It was found that trioxane can be postpolymerized even at a temperature below 30°C with good reproducibility and that the overall activation energy of the polymerization was less than 15 kcal/mole. No chain‐transfer reaction seems to occur except at low temperatures. These results have been discussed in comparison with data reported previously.
Phenylated imide–quinoxaline copolymers
Authors: Augl J. M.
Published: April 2003

Phenylated, ordered imide–quinoxaline copolymers of high oxidative‐thermal stability were prepared by one‐step solution condensation of aromatic tetraamines with N,N′‐bis(4‐benzilyl)pyromellitimide. Polymerization in m‐cresol leads to high molecular weight polymers that remain soluble. Thermal gravimetric analysis and isothermal decomposition at 400°C shows that these polymers are as stable as polyimides or polyquinoxalines. The polymer decomposition temperatures range between 495 and 550°C, depending upon structure. Also, the rate of isothermal decomposition at 400°C in air showed a strong dependency of weight loss on structure. Tough films were cast from solution.
Polymers containing anthraquinone units: Benzimidazole and benzothiazole polymers
Authors: Kokelenberg Hendrik , Marvel C. S.
Published: April 2003

In an attempt to synthesize soluble polymers, diphenyl 1,5‐anthraquinonedicarboxylate was treated with 3,3′‐dimercaptobenzidine and 3,3′‐diaminobenzidine under various conditions. Although the ester reacted readily, side reactions prevented the formation of high molecular weight compounds. It was thought that at the elevated temperatures required for reaction, the quinone group was involved in a type of Schiff's base formation. The thermal stability of the polymers was evaluated. Model compounds were prepared and their absorption spectra were compared with those of the polymers. It was observed that 1,5‐anthraquinonebibenzimidazole‐2 formed a stable product with acetic acid. Some of the polymers could be solubilized by reduction with sodium dithionite in alkali, but no useful fibers were produced from these solutions.
Polyamides: Decarboxylation and desamination in nylon 6 equilibrium polymer
Authors: Reimschuessel H. K. , Dege G. J.
Published: April 2003

Rate and extent of both decarboxylation and desamination in the temperature range of 250–290°C were studied on equilibrium polymers obtained by the hydrolytic polymerization of ε‐caprolactam. Mechanisms have been proposed that are characterized by the participation of the equilibrium monomer in the considered decomposition reactions. The mechanisms suggested accommodate both the experimental results of this study and findings of previous investigations as reported in the literature.
Synthesis of homologous monomers and polymers of carbazole, phenothiazine and dibenzazepine
Authors: Gipstein Edward , Hewett William A. , Need Omar U.
Published: April 2003

Monomers and polymers of 3‐vinyl‐N‐ethylcarbazole, 3‐vinyl‐N‐methylphenothiazine, 3,7‐divinyl‐N‐methylphenothiazine, N‐acrylylcarbazole, N‐acrylylphenothiazine, and N‐acrylyl‐ and N‐methacrylyldibenzazepine have been synthesized. The synthetic procedures for preparing the monomers and polymers are described.
Importance of the singlet–triplet transition of ethylene in its photopolymerization in the presence of oxygen
Authors: Hagiwara Miyuki , Okamoto Hidemasa , Kagiya Tsukasa , Kagiya Tsutomu
Published: April 2003

The rate of the photopolymerization of ethylene initiated by a mercury are lamp was investigated under a pressure of 400 kg/cm2 at 30 ± 5°C by varying the wavelength of incident light. Ethylene was found to polymerize by ultraviolet light below about 3500 Å. The yield decreased gradually as the wavelength became longer, and no polymer was obtained at wavelength greater than 3900 Å. The addition of a small amounr (<100 ppm) of oxygen promoted the polymerization. Ultraviolet absorption spectat measured for the mixture of ethylene and a small amount of oxygen displayed several absorption peaks in the region 2700–3500 Å. The absorption began at about 3680 Å and became stronger with the concentration of oxygen. The average separation between the peaks was about 1000 cm−1. The spectra were also measured for oxygen containing a small amount of ethylene. Similar absorption peaks with those described above were observed. On the basis of these results, it was pointed out that an excited triplet ethylene is formed under the irradiation of light due to a perturbing effect of oxygen contained in ethylene monomer and the reaction between the excited ethylene and oxygen is important in initiating the polymerization.
Stereospecific polymerization of isobutyl vinyl ether by AIR3–VCl3·LiCl catalyst. II. Effects of polymerization conditions on polymerization
Authors: Joh Yasuhi , Yuki Heimei , Murahashi Shunsuke
Published: April 2003

The effect of polymerization conditions such as aging time of the catalyst, polymerization temperature, polymerization time, monomer concentration, and catalyst concentration on the polymerization of isobutyl vinyl ether was intensively studied by using the VCI3·LiCl–Al(i‐Bu)3 system at an Al(i‐Bu)/VCl3·LiCl ratio of 6 at which the cationic polymerization by VCl3·LiCl is sufficiently depressed. About 10 min aging of the catalyst in the presence of monomer yields a fairly stable catalytie system. The optimum polymerization temperature is around 30°C. The conversion increased with increasing monomer concentration, whereas the stereospecificity of polymerization decreased. Unexpectedly, the conversion decreased as total catalyst concentration increased. This phenomenon is explained by considering the deactivation of catalytic sites by the excess of Al(i‐Bu)3. A reasonable mechanism from kinetic considerations is that two molecules of Al(i‐Bu)3 deactivate the catalytic site in an equilibrium reaction. This deactivation is understandable by considering that the coordination of two molecules of Al(i‐Bu)3 will occupy all the coordination positions of vanadium, so that there is no room for coordination of monomer coming to the catalytic site.
Effects of mercaptides on anionic polymerization. II. Polymerization of acrylonitrile initiated by mercaptides
Authors: Hirahara Takuji , Minoura Yuji
Published: April 2003

The polymerization of acrylonitrile by the several alkali metal mercaptides was investigated. The initiation reaction was found spectroscopically and by the sodium fusion method to proceed in a Michael‐like form similar to a cyanoethylation reaction. From the results of the copolymerization of acrylonitrile and methyl methacrylate by the mercaptides, it was found that the mercaptides behaved as the anionic initiators. The effects of the counterions on the rate of polymerization were found to increase with increasing the electropositivites in the order of Li < Na < K. A negative overall activation energy was obtained, −2.2 kcal/mole, in the temperature region of −30°C to +20°C. The catalytic reactivities of the mercaptides were smaller than those of the corresponding oxygen analogs, except in the case of the phenyl substituent. Only in the case of the phenyl substituent, thiophenoxide was found to be much more effective than phenoxide, phenyl‐SNa ≫ phenyl‐ONa. The catalytic reactivities of the various sodium mercaptides were also determined to follow not only the basicities of the nucleophiles, but also the polarizabilities as follows: tert‐butyl‐SNa ≈ n‐dodecyl‐SNa > phenyl‐SNa > n‐octyl‐SNa > isopropyl‐SNa > n‐propyl‐SNa > ethyl‐SNa. The enhanced reactivity of thiphenoxide in spite of the low pKa value was attributed to the higher polarizability based on the low α effect.
Copolymerization of styrene and butadiene in emulsion. II. Relative rates of crosslinking and propagation
Authors: Burnett G. M. , Cameron G. G. , Thorat P. L.
Published: April 2003

For the styrene–butadiene emulsion copolymerization (71 parts butadiene:29 parts styrene) the ratio of the rate coefficients for crosslinking, kx, and propagation, kp, have been determined at 5, 15, and 25°C by using an adaption of the method of Morton and co‐workers. These ratios yield a value of 4.85 kcal/mole for the difference in activation energy between crosslinking and propagation, Ex − Ep. Since the relative frequency of crosslinking and propagation depends upon the copolymer composition, and hence upon the free monomer ratio and the temperature, the range of application of these data is more limited than in a simple homopolymerization.
Thermal degradation of polymers with phenylene units in the chain. IV. Aromatic polyamides and polyimides
Authors: Ehlers G. F. L. , Fisch K. R. , Powell W. R.
Published: April 2003

The breakdown mechanism of an aromatic polyamide and four polyimides has been studied under vacuum in the temperature range of 375–620°C, by using techniques described earlier, involving collection and analysis of volatile products as well as analyses of residues at different temperatures. The decomposition of the polyamide up to 375°C yielded predominantly carbon dioxide, while between 375 and 450°C about equal amounts of carbon dioxide and carbon monoxide formed. Hydrogen is the major product between 450 and 550°C, along with hydrogen cyanide, methane, and carbon monoxide. The major reaction at the lower temperatures seems to be the cleavage of the linkage between the carbonyl group and the ring, with subsequent formation of a carbodiimide linkage via isocyanate intermediates, and liberation of carbon dioxide. Alternatively, cleavage between the carboxyl and the NH‐group leads to the formation of carbon monoxide. Carbon dioxide and carbon monoxide are also the major volatile decomposition products of the polyimides at the lower temperatures. The primary cleavage reaction is believed to be the rupture of the imide ring between a carbonyl and nitrogen, with subsequent formation of isocyanate groups. The latter react with each other to form carbodiimide linkages and carbon dioxide, while the remaining benzoyl radical is the source for carbon monoxide.
Isomorphous replacement in nylon 6 by 4‐aminomethylcyclohexanecarboxylic acid
Authors: Prince Frank R. , Pearce Eli M. , Fredericks Robert J.
Published: April 2003

It was desired to determine the effect of geometric configuration on the ability of 4‐aminomethylcyclohexanecarboxylic acid (AMCC) to “isomorphously” replace ε‐aminocaproic acid residues in nylon 6. However, we found that cis‐AMCC isomerized to the more thermodynamically stable trans isomer during copolymerization with caprolactam (CL) and also during homopolymerization. A 20/80 cis/trans ratio of AMCC residues was found in the 50:50 copolyamides regardless of whether a high‐cis (72/28) or high‐trans (15/85) AMCC was used. Powder x‐ray diagrams showed similar interplanar spacings for the copolyamides made from both high‐cis and high‐trans AMCC. The x‐ray study also showed that the nylon 6 lattice can accommodate less than 30 mole‐% AMCC residues before a new structure appears. DTA and TGA data of the CL:AMCC copolyamide showed that AMCC raised the melting point, Tg, Tc, and stability of nylon 6.
Polymerization studies on allylic compounds. V. 2‐chloropropenes
Authors: Reed Samuel F.
Published: April 2003

The free‐radical polymerization of three 2‐chloro‐3‐substituted propenes have been investigated. Compounds studied were 2,3‐dichloropropane, 2‐chloro‐3‐hydroxypropene, and 2‐chloro‐3‐acetoxypropene. These compounds were found to homopolymerize with difficulty to give low molecular weight polymers. Their effect upon the polymerization of methyl methacrylate and styrene was investigated by rate and viscosity measurements. Copolymerization occurred with a retarding action attributed to significant chain transfer processes and differences in monomer reactivities.
Gel permeation chromatography and cellulose. II. Application of universal calibration
Authors: Segal L. , Timpa J. D. , Wadsworth J. I.
Published: April 2003

In previously reported work concerning the chain‐length distributions obtained by gel permeation chromatography (GPC) in celluloses, degrees of polymerization (DP) of unusually high magnitude were reported. Later work in GPC has shown that the concept of relating extended nolecular chain length of different polymers to elution volume for obtaining molecular weight is not theoretically sound. Correlation of molecular hydrodynamic volume (indicated by the product of intrinsic viscosity and molecular weight) with elution volume has been found to place polymers of vastly different natures on a single curve, such is now designated universal calibration. Application of universal calibration to the determination of DP distributions in celluloses required a different method of converting counts to DP. This new procedure is described in detail. Weight‐average DP's given by the procedure for samples of cellulose I, II, III, and IV were 5190, 4520, 4795, and 3390, respectively. These are decreases of 74–75% from the results obtained by the extended‐chain procedure. The results compare favorably with the viscosity‐DP's of the samples. Number‐average DP's were 1580, 1040, 1140, and 490 for the four samples, respectively, these being decreases of 87–93% from the values formerly reported. The polymolecularity ratios for the samples are now unusually large, being 3.4, 4.7, 4.2, and 7.1, respectively.
Extension of elastic liquids: Polyisobutylene
Authors: Vinogradov G. V. , Radushkevich B. V. , Fikhman V. D.
Published: April 2003

An apparatus is described and a method discussed for determining the rheological characteristics of elastic liquids during extension at constant rates of deformation and extension. The material studied was polyisobutylene of molecular weight 7 × 104. At low constant deformation rates steady‐flow regimes were achieved, with corresponding equilibrium high elastic strains. A detailed study has been made of the process of attainment of steady‐flow regimes and it is shown that before steady flow is reached the curve of longitudinal viscosity versus strain passes through a maximum. As the rate of deformation rises, the strains at which steady–state flow regimes are achieved increase, and the time required to reach these regimes decreases. Qualitatively this occurs in the same way as upon shear. The dependence of equilibrium high‐elastic strains (under steady‐flow regimes) on the rate of deformation has been determined. At steady‐flow regimes the stress depends linearly on the rate of deformation at low values of the stress. Under such conditions Trouton's formula is valid. At constant rates of extension the stress versus time curve passes through a maximum which becomes higher with increasing extension rates.
Determination of the molecular weight spread of narrow peaks in the gel‐permeation chromatograms of nitric acid‐degraded polyethylene
Authors: Williams T. , Udagawa Y. , Keller A. , Ward I. M.
Published: April 2003

A method for the determination of the molecular weight spread in the narrow peaks in the GPC chromatograms of nitric acid‐degraded polyethylene is presented. It is found that polar endgroups added to the polymer chains during scission cause the peaks to be broader than those of paraffins with the same molecular weight spread. After allowing for this extra instrumental broadening, estimates are made of the molecular weight spread for unannealed and annealed single crystals of polyethylene and bulk polyethylene as a function of degradation time. It is proposed that after long degradation times the molecular weight spread is a measure of fluctuations in the original crystalline lamellar thickness.
Single crystals of high polymers by film formation
Authors: Patel G. N. , Patel R. D.
Published: April 2003

A simple method of preparing thin uniform films of high polymers has been examined for growing single crystals from solution. Single crystals of polyethylene, polypropylene, polybutene‐1, polyacrylonitrile, and cellulose triacetate have been obtained by this method. Different stages of growth reveal different growth features that are also obtained from solutions of these polymers by changing temperature and concentration.