bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermosetting polyimides
Authors: Bower G. M. , Freeman J. H. , Traynor E. J. , Frost L. W. , Burgman H. A. , Ruffing C. R.
Published: April 2003

Linear polyimides prepared from m‐phenylene diamine (MPD) and 3,4,3′,4′‐benzophenonetetracarboxylic dianhydride (BTDA) were modified so as to be thermosetting. This was done by replacing a portion of the MPD with either 2,4‐diaminoacetanilide or p‐(2,4‐diaminophenoxy) acetanilide and 3,5‐diaminobenzoic acid; it is thought that during final processing of the laminates the carboxyl group and the acetamido group react, forming amide crosslinks. Alternatively, excess anhydride was incorporated into the polymer to react with some of the attached acetamido groups; these would give imide crosslinks. A series of resins and glass‐reinforced laminates incorporating these resins was prepared. The laminates were aged and tested at 315°C. Flexural strength at 315°C. versus hours aged at 315°C. is presented. Flexural strength after 100 hr. at 315°C. for two of the better laminates from modified polymers was about 48,000 psi, compared to 24,000 psi for the straight linear polymer. The flexural strength of the modified polymers decreased more rapidly, however, and after 1000 hr. of aging at 315°C. the flexural strength of the best laminates, including the linear polymer, was 12,000 psi.
Part I. On the synthesis and pyrolysis of a tetrafluoroethylene–acrylonitrile graft copolymer
Authors: Fock J.
Published: April 2003

Radiation‐induced grafting of acrylonitrile onto films of polytetrafluoroethylene has been studied. Irradiation has been carried out in a 60Co gamma source at −78°C., and the graft polymerization was facilitated by being held at 100°C. for 150 hr. The amount of acrylonitrile grafted per unit surface area apparently increases with the thickness of the film. Grafting is also accompanied by slight swelling. This indicates that the reaction occurs in depth. The relative decrease of the amount of grafted acrylonitrile with thickness of the film, referred to the weight of the film, shows that grafting is controlled by the diffusion of the monomer. The rate of grafting was found to be lower in a material with a higher degree of crystallinity; i.e., grafting occurs faster in the amorphous areas of the polymer. The final yield of graft decreases with the temperature at which the reaction is carried out. This may be explained on the basis of kinetics or by assuming a simultaneous disappearance of free polymer radicals.
Structure and reactivity α,β‐unsaturated ethers. II. Cationic copolymerizations of propenyl isobutyl ether
Authors: Okuyama T. , Fueno T. , Furukawa J.
Published: April 2003

cis‐ and trans‐Propenyl isobutyl ethers were copolymerized with each other and each with vinyl isobutyl ether separately under various conditions. In homogeneous polymerizations a cis‐β‐methyl substitution on vinyl isobutyl ether apparently enhanced the reactivity, whereas the trans substitution tended to reduce it slightly. In heterogeneous catalysis, on the other hand, a β‐methyl group on the vinyl ether, whether cis or trans, greatly reduced the reactivity, probably because of the steric hindrance toward the adsorption of monomers on the catalyst surface. The relative reactivities of cis‐ and trans‐propenyl isobutyl ethers ranged from 2 to 20, depending on the polymerization conditions. The polymer end formed from the cis monomer exhibited special steric effects. It was concluded that even in homogeneous media the rotation of the polymer end around the terminal carbon–carbon bond is restricted.
Radiation‐induced, solid‐state polymerization of derivatives of methacrylic acid. I. Postirradiation polymerization of zinc methacrylate
Authors: O'Donnell J. H. , Sothman R. D.
Published: April 2003

The postirradiation polymerization of the crystalline, anhydrous, monohydrate, and dihydrate forms of zinc methacrylate was studied. The anhydrous salt polymerized readily in the temperature range 50–150°C., the monohydrate did not polymerize at all, and the dihydrate polymerized at about 100°C. Aging of the anhydrous salts greatly affected the rate of polymerization; this was shown to be due mainly to the formation of peroxides by reaction with air. Polymerization could be initiated thermally, without irradiation, in monomer which had been aged in contact with air, apparently by decomposition of the peroxides. The rate of the postirradiation polymerization was increased when air was present during irradiation and decreased when air was present during polymerization. The rate of polymerization increased with temperature, corresponding to an apparent activation energy of 10 kcal./mole. The dihydrate lost one molecule of water rapidly under vacuum at 20°C. and slowly on heating at 50°C. in a sealed vessel, forming a crystalline monohydrate. Slow thermal polymerization and rapid postirradiation polymerization occurred at 100°C. without the formation of any monohydrate, indicating that the polymerization was concurrent with the phase change.
Radiation‐induced polymerization of isoprene in aqueous solution of silver nitrate
Authors: Fujioka Syuji , Ichimura Tadao , Shinohara Yasuo , Hayashi Koichiro
Published: April 2003

The rate of radiation‐induced polymerization of isoprene in aqueous solution of silver nitrate is 20–50 times as fast as the rate of radiation‐induced polymerization of pure isoprene. The formation of a 1:2 complex of isoprene and silver nitrate was confirmed spectrometrically, and this complex seems to polymerize by attack of an active species. The equilibrium constant Kf and the extinction coefficient E of the complex were estimated to be 0.18 and 1.4, respectively. The polymerization mechanism was concluded to be a radical one, based on the effects of inhibitors. The polyisoprene obtained had a crosslinked structure, was insoluble, and did not give a distinct melting point. The 1,2 structure was the predominant polyisoprene configuration. This was interpreted on the basis of the frontier electron density of isoprene.
Hyperelectronic polarization in macromolecular solids
Authors: Hartman Roger D. , Pohl Herbert A.
Published: April 2003

Hyperelectronic polarization may be viewed as the electrical polarization in external fields due to the pliant interaction with the charge pairs of excitons, in which the charges are molecularly separated and range over molecularly limited domains. It is particularly pronounced in molecular solids composed of long polymeric molecules having extensive regions of electronic orbital delocalization. Hyperelectronic polarization is regarded as the principal contributor to the high polarizabilities of the following five macromolecular solids: four polyacene quinone radical polymers formed by condensation of aromatic hydrocarbon derivatives with aromatic acids and poly(Cu(II)‐N,N′‐ dimethyl rebeanate). The first four polymers at 100 hz had dielectric constants of 1800–2400, decreasing to about 58–100 at 100,000 hz, with relaxation times of 10−3 to 10−4 sec. A sixth polymer, a Schiff‐base condensate of 1,4‐napthaquinone and p‐toluene diisocyanate, however, showed little hyperelectronic polarization, displaying a dielectric constant of 10, constant over 100–100,000 hz. By simple arguments it is shown that the relaxation times and the frequency response of conduction are consonant with the proposed model of charges roaming over long molecular domains (up to 4000 A.) but restricted by molecular boundaries.
Anion radicals of polyphenylsiloxanes
Authors: Eargle D. H. , Moniz W. B.
Published: April 2003

The anion radicals of a number of siloxanes bearing phenyl and methyl substituents have been prepared by metal reduction. The cleavage and reaction mechanisms of these radica s have been studied by ESR, and interpretations have been made regarding the structures of the radicals.
Room‐temperature polycondensation of β‐amino acid derivatives, I. Polyamide from amino alcohols and acrylates
Authors: Sanui Kohei , Asahara Tomohiko , Ogata Naoya
Published: April 2003

Acrylates, such as ethyl acrylate, add with amino alcohol to form N‐(hydroxyalkyl) β‐alanine ester and room‐temperature polycondensation follows, forming polyamide in the presence of a basic catalysts, such as alkali metal alkoxide. The reaction medium has an influence on the course of the polycondensation; that is, N‐(hydroxyalkyl) polyamide is formed in methanol solution and polyamide ether in other solvents, such as tetrahydrofuran. These two courses of the room‐temperature polycondensation have been studied, and the reaction mechanism is discussed in this paper.
Effect of urethane groups on the reaction of alcohols with isocyanates
Authors: Smith H. A.
Published: April 2003

Recently Reegen and Frisch reported the urethane catalysis of the alcohol–isocyanate reaction. We have made similar observations on a broader variety of reactants and catalysts including mono‐ and polyfunctional reactants, and tertiary amine, cobalt salt, and tin salt catalysts. We have found that the point in the reaction when urethane catalysis occurs is a function of the catalyst, the number of hydroxyl groups in the alcohol, and the effect of the interaction of the catalyst, alcohol, and isocyanate on the geometry of the reactive complex.
The radiation‐induced copolymerization of tetrafluoroethylene and 3,3,3‐trifluoropropene under pressure
Authors: Brown Daniel W. , Wall Leo A.
Published: April 2003

A study was made of the gamma‐ray‐induced copolymerization of tetrafluoroethylene and 3,3,3‐trifluoropropene. Copolymerizations were carried out at 100°C. and 5000 atm. pressure and at 21°C. and various pressures up to 8000 atm. The reactivity ratios calculated from the composition data indicate that the propagation rate constants favor addition of trifluoropropylene by a factor of 3–7; individual values depended little on the polymerization pressure and temperature. Polymerization rates changed little with monomer composition between 0 and 75% tetrafluoroethylene; between 75 and 95% tetrafluoroethylene they increased by a factor of 10. As many as 850,000 molecules were polymerized per 100 e.v. absorbed. The copolymers are soluble in hexafluorobenzene at 29.6°C. if they contain less than 70% tetrafluoroethylene. Intrinsic viscosities range from 0.1 to about 10 dl./g. From various considerations it appears likely that the degree of polymerization is about equal to the kinetic chain length in high‐pressure polymerizations at 21°C.; at autogenous pressure or at 5000 atm and 100°C., monomer transfer reduces the value considerably.
Alternating copolymerization through the complexes of conjugated vinyl monomers–alkylaluminum halides
Authors: Hirooka Masaaki , Yabuuchi Hiroshi , Iseki Jiro , Nakai Yasuto
Published: April 2003

A vinyl monomer that has the nitrile or carbonyl group conjugated to the CC double bond, such as acrylonitrile, methyl acrylate, and methyl methacrylate, forms a complex with an alkylaluminum halide, and the complex reacts spontaneously with a hydrocarbon monomer such as styrene, propylene, or ethylene, giving a high molecular weight copolymer. The copolymers always contain the two monomer units in 1:1 ratio. Thus styrene, copolymerized with methyl acrylate or methyl methacrylate in the presence of ethylaluminum sesquichloride in homogeneous toluene solution, gives such an equimolar copolymer regardless of the initial monomer compositions. The NMR spectra of these copolymers are distinctly different from those of the equimolar copolymers obtained with azobisisobutyronitrile as initiator and have simpler and well separated patterns. The copolymers and the corresponding radical copolymers appear to be amorphous, judged by their x‐ray diffraction patterns and their differential thermal analyses. Their infrared spectra resemble each other very closely. Hence, the difference in the NMR spectra may be ascribed to the matter of the sequence distribution. The infrared spectrum of ethylene–methyl acrylate copolymer shows no absorption near 720 cm.−1 due to the methylene sequence arising from ethylene–ethylene linkage. These experimental data lead to the inference that the equimolar copolymers obtained in this work may have an alternating sequence.
Radical grafting on lignin. Part I. Radiation‐induced grafting of styrene onto hydrochloric acid lignin
Authors: Koshijima Tetsuo , Muraki Einosuke
Published: April 2003

By irradiation with gamma rays styrene was grafted onto hydrochloric acid lignin. When the graft polymers were subjected to nitrobenzene oxidation, the vanillin yields indicated two kinds of reaction occurring in the grafting. Polystyrene branches were separated from the graft polymers, and their M̄n were determined osmometrically. At grafting ratios of up to 100 the vanillin yields diminished proportionately with increasing grafting, and the M̄n of the branches, 5000, was unchanged. At grafting ratios of more than 100 the vanillin yields were constant, independent of the ratios, but the M̄n values of the branches increased with grafting. Paper chromatography of the aromatic acids obtained by oxidation of methylated lignin and the graft polymer indicated that isohemipic and metahemipic acids were more abundant in the acid fraction of the graft polymer than in the lignin itself. A qualitative mass analysis of the gaseous products evolving from the irradiated lignin showed the presence of hydrogen molecules only. Gamma‐ray radiation brought about no change in the yields of vanillin. It was therefore concluded that radiation grafting on lignin at grafting ratios of less than 100 proceeded through the addition of the styrene polymer radicals to the aromatic nuclei of the lignin and that then branches propagated from the aliphatic part of the lignin, where CH bond scission had been caused by the irradiation. The grafting sites of lignin would be C‐5 and C‐6 of the guaiacyl nucleus and, probably the β and γ carbon atoms of the aliphatic side chain of the lignin.
Cationic polymerization of α‐methylstyrene catalyzed by boron trifluoride etherate in 1,2‐dichloroethane under an electric field
Authors: Sakurada Ichiro , Tanaka Yoshinobu , Ise Norio
Published: April 2003

The cationic polymerization of α‐methylstyrene with boron trifluoride etherate was studied in 1,2‐dichloroethane under an electric field. The electric field was again found to increase the polymerization rate. This field effect was independent of monomer concentration, as was found previously. The effect, however, became greater as the catalyst concentration was lowered, unlike previous findings with various cationic systems. Furthermore, the field effect became smaller with rising temperature, whereas it had been practically independent of temperature in previous studies. The field effect increased linearly with the field strength. At 2.7 kv./cm. the rate was almost tripled. The field effect was small at lower dielectric constants, as had been observed previously. The large field effects observed and their “exceptional” behavior led to the interpretation that “partial” desolvation of free, growing chain ends, in addition to the field‐facilitated dissociation, was responsible for the effect. Specific conductivities of polymerizing solutions and catalyst solutions were measured and are discussed.
Copolymerization of allyl esters of some fatty acids
Authors: Chow Roberta C. L. , Marvel C. S.
Published: April 2003

Attempts have been made unsuccessfully to homopolymerize a number of allyl esters of substituted fatty acids by radical initiation in emulsion systems. Copolymerizations of these allyl esters with styrene, methyl methacrylate, and vinyl chloride have been investigated. Of these comonomers, styrene and methyl methacrylate do not copolymerize well with the allyl esters, whereas vinyl chloride does. Reactivity ratios for the radical copolymerization of allyl 11‐iodoundecanoate, M1, and vinyl chloride, M2, determined at 60°C. in benzene, are r1 = 0.42 and r2 = 1.64. A copolymer of allyl 10, 11‐dibromoundecanoate and vinyl chloride was fractionated and found to be fairly homogeneous.
Determination of elementary rate constants of styrene polymerization catalyzed by rhenium pentachloride
Authors: Kamachi Mikiharu , Miyama Hajime
Published: April 2003

Rate constants of the propagation and transfer processes for the cationic polymerization of styrene catalyzed by rhenium pentachloride were obtained by kinetic analysis. Also, dependence of the propagation constant on the dielectric constant of the system was examined. Comparison of these data with those of the other systems with different catalysts suggests that the present catalyst is a strong Lewis acid and the size of the counterion is very large.
The interaction of ions with nylon. Part I. Absorption of simple acids
Authors: Marshall J.
Published: April 2003

The paper describes the titration relations for nylon 66 samples of different endgroup contents both for aqueous and alcohol solutions. The effect of temperature change is also considered. The results are consistent with a zwitterion structure of the nylon, carboxyl groups being protonated on acid titration. The acid groups are shown to be weaker than the corresponding monomeric acids in aqueous solution, owing to their environment inside the polymer. Individual ionic affinities are calculated from the experimental absorption isotherms and are in agreement with values obtained from a simple electrostatic theory. The low sulfate ion affinity can be explained by assuming interaction for this ion with single, fixed, isolated sites.
The polymerization of 1,4‐pentadiene to [3.3.1]bicyclo‐linked chains
Authors: Trifan Daniel S. , Shelden Ronald A. , Hoglen John J.
Published: April 2003

1, 4‐Pentadiene has been polymerized by Ziegler‐Natta catalysts to give amorphous polymers which are up to 64 wt.‐% soluble. The polymers all have residual unsaturation which is substantially less than one double bond per mer, some as low as 0.1 double bond per mer. The polymerizations proceed by an unusual double inter‐, double intramolecular cyclopolymerization mechanism leading to the formation of [3.3.1] bicyclic repeat units. Some main‐chain (internal) unsaturation as well as pendant‐group (external) unsaturation is observed. The latter results from incompletely cyclized 1,4‐pentadiene units. The former is due to some concurrent isomerization of 1,4‐ to 1,3 pentadiene, which then copolymerizes with the 1,4 diene. The extent of isomerization varied with the catalyst system used. The soluble polymer fractions were brittle for internal unsaturations of less than about 0.05 double bond per mer and were viscous for higher values. The insoluble fractions were brittle and are believed to be lightly crosslinked.
Preparation of polymers containing sugar residues
Authors: Iwakura Yoshio , Imai Yohji , Yagi Kohji
Published: April 2003

The synthesis of five different polymers containing sugar residues on side chain is described. 1‐O‐Methacryloyltetra‐O‐acetyl‐D‐glucose, 1‐O‐methacryloyltetra‐O‐acetyl‐D‐galactose, and 6‐O‐methacryloyltetra‐O‐acetyl‐D‐glucose were prepared and polymerized. The polymethacrylates obtained were converted into water‐soluble polymers by removing the acetyl protective group with sodium methoxide. 6‐O‐Methacryloyldiisopropylidene‐D‐galactose was also prepared and polymerized. The isopropylidene protective group was removed by acid hydrolysis. Poly (N‐methacryloylglucosamine) was prepared directly by the polymerization of N‐methacryloyl‐D‐glucosamine without the use of any protective group.
Synthesis and thermogravimetric analysis of diol‐linked tetrameric hexaphenyldichlorophosphonitrile polymers
Authors: Bilbo A. J. , Douglas C. M. , Fetter N. R. , Herring D. L.
Published: April 2003

Several high molecular weight polymers have been prepared from the reactions of hexaphenyldichlorophosphonitrile tetramer with p,p′‐biphenol, 4,4′‐oxydiphenol, resorcinol, and benzidine. A simple fractionation procedure yielded samples of the biphenol‐linked polymer with molecular weights of approximately 500,000. DTA and TGA studies of this polymer in a variety of environments indicate thermal degradation is initiated in the phosphonitrile ring.
Solid‐state polymerization of maleimide by 2,2′‐azobisisobutyronitrile
Authors: Kagiya Tsutomu , Izu Masatsugu , Kawai Shunzo , Fukui Kenichi
Published: April 2003

The solid‐state polymerization of maleimide by 2,2′‐azobisisobutyronitrile was studied over the temperature range 65–85°C. The polymerization was carried out either by heating the solid mixture of maleimide and 2,2′‐azobisisobutyronitrile or by heating the two compounds separately in twin ampules. The results of the kinetic study showed that the lifetime of the propagating radicals was short and that the rate of termination was proportional to the mole amount of propagating radicals. The ESR spectrum showed that stable radicals that were not main propagating radicals were in the polymerizing system.
The composition of catalysts prepared from tri‐n‐propylaluminum, anisole, and titanium tetrachloride
Authors: Cunningham Robert E. , Dove Ray A.
Published: April 2003

Catalysts were prepared from titanium tetrachloride and tri‐n‐propylaluminum or tri‐n‐propylaluminum anisole at [Al]/[Ti] molar ratios of 0.20–1.10. They were aged and filtered, and the solid and liquid portions were analyzed for aluminum, titanium, chlorine, and certain organic constituents. The analyses indicate that the solid of the nonetherate catalyst is predominantly TiCl3, some AlCl3 or aluminum alkyl chlorides being included. Only at [Al]/[Ti] = 1.10 was any alkyl group found in the solid. The same general results were found for the etherate catalyst, but the solid had a somewhat lower [Cl]/[Ti] ratio, indicating greater reduction or alkylation, or both, of the titanium species than in the nonetherate catalyst. The solid also contained some anisole at the higher [Al]/[Ti] ratios. The results lend general support to proposed reactions for the catalyst formation. The main differences in the etherate catalysts relative to the non‐etherate system, particularly at the higher [Al]/[Ti] ratios, are the apparently greater reduction or alkylation of the titanium in the solids, the presence of anisole in the liquid and solid portions, and the presence of phenol in the liquid portion. The phenol presumably comes from cleavage of the anisole during the catalyst formation. Not all of the anisole has been accounted for in a materials balance, nor has all of the chlorine in the etherate catalysts. No propyl or isopropyl chloride was found in the catalysts; there is no significant amount of polypropylene in any of the catalyst solids. Hence the fate of the alkyl groups remains undetermined at present.
Anionic polymerization and copolymerization of acrylophenone
Authors: Mulvaney J. E. , Dillon J. G.
Published: April 2003

The n‐butyllithium‐initiated polymerization of a mixture of acrylophenone (AP) and styrene produces only poly(AP), indicating that a chain ending in an AP enolate ion is not sufficiently nucleophilic to add to styrene. Radical copolymerization of AP and styrene yields a polymer containing 65% AP (at 41% conversion). In contrast, lithium dispersion‐initiated polymerization of AP and styrene produces a product containing 50–99% AP, depending upon conversion. This observation is discussed in terms of current knowledge concerning alkali metal‐initiated polymerization.
Polyaddition reaction of pseudoxazolones with dimercaptans
Authors: Iwakura Yoshio , Toda Fujio , Torii Yoshinori , Sekii Reiko
Published: April 2003

Polymers having thioether, thiolester, and amide linkages in each repeating unit of a polymer main chain were prepared by the polyaddition reaction of pseudoxazolones (2‐isopropylidene‐4‐alkyl‐3‐oxazolin‐5‐ones) and dimercaptans. The polymers had inherent viscosities in a range of 0.08–0.22 and gave transparent films by solution casting.
Polymerization of cyclic iminoethers. V. 1,3‐oxazolines with hydroxy‐, acetoxy‐, and carboxymethyl‐alkyl groups in the 2 position and their polymers
Authors: Levy A. , Litt M.
Published: April 2003

Oxazolines containing carbomethoxy‐, acetoxy‐, and hydroxy‐alkyl groups on the side chain were prepared and polymerized. The properties of the polymers were investigated.
Polypyromellitimides: Details of pyrolysis
Authors: Gay F. P. , Berr C. E.
Published: April 2003

Polyimide films from 4,4′‐diaminodiphenyl ether and pyromellitic dianhydride were pyrolyzed at 400–600°C. in non‐oxidative systems. Major gaseous products were carbon monoxide and carbon dioxide; hydrogen evolution occurred above 525°C. A mobile n‐imide‐isoimide equilibrium is in accord with the gas evolution data. Carbon dioxide arises from isoimide decomposition and carbon monoxide arises from the normal imide.
Charge transfer complexes of N‐ethylcarbazole and poly‐N‐vinylcarbazole
Authors: Rembaum A. , Hermann A. M. , Haack R.
Published: April 2003

Poly‐N‐vinylcarbazole and its monomeric analog, i.e., N‐ethylcarbazole, act as donors in charge transfer complexes with such electron acceptors as iodine, tetracyanoethylene, and tetracyanoquinodimethane. Poly‐N‐vinylcarbazole and N‐ethylcarbazole are also capable of accepting electrons from an alkali metal such as sodium. A study of the spectral properties of both types of complexes showed that the monomer can both accept and donate electrons to a greater extent than the corresponding unit segment of the polymer chain. Equilibrium constants are presented for both cases, and estimates of the ionization potential of N‐ethylcarbazole and related compounds are made from the characteristic charge transfer frequencies. Good agreement between these values and those calculated from molecular orbital theory is outlined.
Metal coordination polymers. I. Synthesis and thermogravimetric analysis of beryllium phosphinate polymers
Authors: Slota P. J. , Freeman L. P. , Fetter N. R.
Published: April 2003

The preparation, properties, infrared, DTA, and TGA data are given for beryllium dimethyl‐, tetramethylene‐, di‐n‐butyl‐, di‐n‐pentyl‐, di‐n‐heptyl‐, methylphenyl‐, diphenyl‐, and bispentafluorophenylphosphinates. Synthesis of dimeric beryllium acetylacetonyl phenyl‐[o‐methylcarboranyl (B10)] phosphinate is reported. The beryllium phosphinates were prepared by the reaction of beryllium acetylacetonate with the appropriate phosphinic acid.
Polymerization in the crystalline state. X. Solid‐state conversion of 6‐aminocaproic acid to oriented nylon 6
Authors: Macchi E. M. , Morosoff N. , Morawetz H.
Published: April 2003

When single crystals of 6‐aminocaproic acid (ACA) are heated about 30°C below their melting point, polycondensation to nylon 6 takes place. The polymer crystallites are biaxially oriented towards each other and the relation between their orientation and that of the parent monomer crystal has been clarified. The kinetics of the process are characterized by three stages, (a) an induction period, (b) a stage in which monomer disappears at a constant rate while polymer of relatively low molecular weight is formed, and (c) a slow polycondensation of the polyamide chains after exhaustion of the monomer. Oligomer concentrations were below detectable limits at all stages of the process. Addition of monomer to the polyamide was retarded when ACA was kept from reaching its equilibrium vapor pressure (0.12 mm Hg at 170°C) by condensation on a cool surface or when an inert gas was admitted to the system. This was interpreted as suggesting that ACA is transported through the vapor phase to the propagating polyamide. A number of surfaces catalyzed the polycondensation of ACA vapor, but nylon 6 formed in this way on KCl crystals exhibited no preferred orientation. The linear dimer and trimer of ACA were also found to condense to nylon 6 in the crystalline state, although at a slower rate than the monomer. The solid‐state polycondensation of these oligomers was accelerated when they were exposed to the vapor of the monomer. Solid‐state polycondensation of single crystals of the linear dimer led also to biaxially oriented nylon 6.
Thermal reactions of polyacrylonitrile
Authors: Hay J. N.
Published: April 2003

The exothermic process which occurs on heating polyacrylonitrile above 200°C. is studied with a differential scanning calorimeter and by following volatiles production. The process is associated with coloration of the polymer and the production of ammonia. It is not due to chain scission degradation, which occurs in this temperature range and also produces volatiles.
Polymerization of α‐amino acid N‐carboxy anhydrides. III. Mechanism of polymerization of L‐ and DL‐alanine NCA in acetonitrile
Authors: Iwakura Yoshio , Uno Kiekichi , Oya Masanao
Published: April 2003

The polymerization of L‐ and DL‐alanine NCA initiated with n‐butylamine was carried out in acetonitrile which is a nonsolvent for polypeptide. The initiation reaction was completed within 60 min.; there was about 10% of conversion of monomer. The number‐average degree of polymerization of the polymer obtained increased with the reaction period, and it was found to agree with value of W/I, where W is the weight of the monomer consumed by the polymerization and I is the weight of the initiator used. The initiation reaction of the polymerization was concluded as an attack of n‐butylamine on the C5 carbonyl carbon of NCA. The initiation, was followed by a propagation reaction, in which there was attack by an amino endgroup of the polymer on the C5 carbonyl carbon of NCA. The rate of polymerization was observed by measuring the CO2 evolved, and the activation energy was estimated as follows: 6.66 kcal./mole above 30°C. and 1.83 kcal./mole below 30°C. for L‐alanine NCA; 15.43 kcal./mole above 30°C., 2.77 kcal./mole below 30°C. for DL‐alanine NCA. The activation entropy was about −43 cal./mole‐°K. above 30°C. and −59 cal./mole‐°K. below 30°C. for L‐alanine NCA; it was about −14 cal./mole‐°K. above 30°C. and −56 cal./mole‐°K. below 30°C. for DL‐alanine NCA. From the polymerization parameters, x‐ray diffraction diagrams, infrared spectra, and solubility in water of the polymer, the poly‐DL‐alanine obtained here at a low temperature was assumed to have a block copolymer structure rather than being a random copolymer of D‐ and L‐alanine.
Evidence for several species of active sites in Ziegler‐Natta catalysts
Authors: Lovering Edward G. , Wright William B.
Published: April 2003

The kinetics of isoprene polymerization catalyzed by VCl3 and Et3Al were studied by measuring fractional conversions, polymer composition, and molecular weight distributions at a series of reaction times and temperatures. The rate of polymerization plotted against temperature shows an inflection point with a minimum and maximum in the 60–90°C range. The isomeric composition of the polymer changes with temperature but not with reaction time, while the molecular weight distribution undergoes substantial change with both of these variables. The rate of polymerization at sites producing low molecular weight polymers was measured, and the activation energy calculated to be about 10 kcal/mole. The active sites were found to deactivate at different rates. The results support the hypothesis that several species of active sites are present in the system and that these exhibit characteristic polymerization behavior.
Reduction of disulfide bonds in keratin with 1,4‐dithiothreitol. I. Kinetic investigation
Authors: Weigmann Hans‐Dietrich
Published: April 2003

The kinetics of the reduction of disulfide groups in wool fibers with dithiothreitol has been investigated. The rate‐controlling process appears to depend on the pH of the reducing solution and changes from diffusion control to reaction rate control as the pH is decreased from neutral to pH 3.50. Pseudo second‐order kinetics, second‐order with respect to the concentration of the disulfide groups in keratin, has been found to describe the experimental data at pH 3.50. An activation energy of 25 kcal/mole has been determined for the rate‐controlling step at that pH value, as opposed to an activation energy of 13.4 kcal/mole for the diffusion‐controlled process at neutral pH. Only about 85% of the disulfide groups are accessible to dithiothreitol under the conditions which were investigated.
Grafting of monosaccharide derivatives to cellulose acetate
Authors: Whistler Roy L. , Ruffini Guglielmo , Pyler Richard E.
Published: April 2003

Grafting of 1,2‐O‐isopropylidene‐α‐D‐xylofuranose to commercial cellulose diacetate has been accomplished by using a boron trifluoride catalyst. The reaction proceeds quickly at 25 and 40°C, resulting in degrees of molar substitution (MS) of 0.37 and 0.34, respectively. If monomer and catalyst are added over an extended period of time to maintain low concentrations, MS values as high as 0.89 and 0.85 are obtained at 25 and 40°C, respectively. Major side reactions are depolymerization of the cellulose acetate backbone and grafted D‐xylose and the homopolymerization of the monomer. These side reactions may be minimized by conducting the reaction at 40°C for a short time or by adding monomer and catalyst over an extended period of time. Grafting has also been accomplished by using D‐xylose derivatives with various reactive groups at the anomeric carbon atom. The grafted material of MS greater than 0.7 is insoluble in acetone and after deacetylation is soluble in water under alkaline, neutral and acidic conditions. Oxalic acid hydrolysis of the deacetylated material indicates that most of the grafted D‐xylose units are in the furanose form. Methylation and hydrolysis of the methylated material shows that 75% of the D‐xylose residues are terminal units and indicates the presence of many singly grafted D‐xylose residues and a few di‐and trisaccharide grafts.
Formaldehyde equilibria: Their effect on the kinetics of the reaction with phenol
Authors: Zavitsas Andreas A.
Published: April 2003

The kinetics of the base catalyzed hydroxymethylation of phenol by aqueous formaldehyde are influenced strongly by the equilibria among the hydrated forms of formaldehyde, and among the hydrates and the alcoholic function of the products. Apparent peculiarities in the kinetics of the system and seemingly anomalous solvent effects are shown to be due to erroneous formulation of the previously accepted rate expression. The correct expression is: Rate = k[Pi−] [F]m, where Pi− is phenoxide ion, F is unreacted formaldehyde, and m is the fraction of formaldehyde in the form of monomeric hydrate. Formaldehyde tied up in equilibria as αω‐poly(oxymethylene) diols, and hemiformals of the hydroxymethylphenols, constitutes a potential source of formaldehyde and is detected by the usual analytical procedures, but does not contribute to the rate of the hydroxymethylation reaction.
Autoxidation of polypropylene catalyzed by cobalt salt in the liquid phase
Authors: Kamiya Yoshio
Published: April 2003

The autoxidation of isotactic polypropylene suspended in the organic solvent was found to proceed very rapidly in the presence of cobalt salts. The rate of oxidation increases and the induction period decreases as the concentration of the cobalt is increased. The rate of oxidation depends on solvent and is quite fast in fatty acids. Polypropylene has shown a rapid decrease in molecular weight at the initial stage of oxidation, and the volatile products were mainly composed of carbon dioxide and small amount of carbon monoxide. Other oxidation products were acetic acid‐soluble resinous materials, having molecular weights of 250–730, with a molar ratio of carbon to oxygen of 3.0–5.4. Atactic polypropylene, relatively stable against oxidation, was oxidized easily in the presence of cobalt and bromide ion. The difference in the rate of oxidation depending on the tacticity of polypropylene is attributed primarily to steric hindrance to the intramolecular hydrogen abstraction step.
Polymerization of isocyanates. V. Thermal degradation of polyisocyanates
Authors: Iwakura Yoshio , Uno Keikichi , Kobayashi Norio
Published: April 2003

Thermal degradation of polyisocyanates was investigated. The only degradation products were monomer and trimer. The main product was trimer for most aliphatic polymers, and monomer for aromatic polymers. Poly(cyclohexyl isocyanate) gave only its monomer on account of steric requirements. The apparent activation energy was calculated for aromatic polymers by using TGA and DTA curves.
Polymerization of ethylene catalyzed by diethylaluminum chloride and titanium (III) acetylacetonate
Authors: Watt W. R. , Fry F. H. , Pobiner H.
Published: April 2003

Catalysts for the polymerization of ethylene were prepared from titanium (III) acetylacetonate and diethylaluminum chloride. Titanium (III) acetylacetonate is of interest because it is soluble in hydrocarbon solvents used as polymerization media. As its oxidation product oxobisacetylacetonatotitanium (IV) is also hydrocarbon‐soluble, this system provides a vehicle for studying the effects of a change in valence on catalyst activity without an accompanying change of state, as occurs with titanium halides. Relatively high molar ratios (>20:1) of aluminum alkyl to titanium compound were required to give active catalysts. Precipitates generally formed in the catalyst mixtures, although dilute catalyst solutions in which no precipitate was visible still initiated polymerization. Catalyst mixtures were observed to undergo certain changes on standing. Light‐scattering studies indicated an increase in catalyst particle size, and a gas identified as ethane was evolved. These changes were accompanied by a reduction in activity of the catalyst. Parallel polymerization tests were run for a comparison of catalysts prepared from titanium(III) acetylacetonate and catalysts prepared from oxobisacetylacetonatotitanium(IV). There was essentially no difference in yield or properties of polymer prepared using the two catalyst systems. The evidence suggests that both the trivalent and tetravalent titanium compounds yield the same catalytic intermediate when reacting with diethylaluminum chloride.
The structure and transport properties of poly(methacrylic acid) in aqueous solution
Authors: Kern E. E. , Anderson D. K.
Published: April 2003

Diffusion and anisotropic electrical conductivity measurements have been used to investigate the structure of poly(methacrylic acid) in aqueous solution at various degrees of neutralization. Both kinds of measurement indicate that the polyion chain opens from a coiled to an extended configuration as the chain is neutralized. In addition it was found that, at low concentrations, the opening of the chain is a two‐step process, whereas at higher concentrations the mechanism involves a single step.
Reaction of chlorine‐containing polymers with living polymers
Authors: Minoura Yuji , Hironaka Hisashi , Kasabo Toshiyuki , Ueno Yukio
Published: April 2003

A graft polymer was prepared by means of the coupling reaction of chlorinated ethylene–propylene terpolymer with living polystyrene, obtained with a sodium–naphthalene complex as initiator, under various conditions; the grafting efficiency and the percentage of grafting are discussed. Poly(chloroprene), chlorinated butyl rubber, poly(vinyl chloride), poly(epichlorohydrin), and epichlorohydrin–ethylene oxide copolymer were also used as chlorine‐containing polymers. The grafting efficiencies were found to be in the following order: chlorinated butyl rubber > poly(epichlorohydrin) > epichlorohydrin‐ethylene oxide copolymer > chlorinated ethylene‐propylene terpolymer > poly(chloroprene) > poly(vinyl chloride). A graft polymer was obtained from the reaction between chlorinated ethylene–propylene terpolymer and living poly(isoprene), with butyllithium in benzene. The undesirable metal–halogen interchange reaction was considerable.
Effect of acetylene on the γ‐radiation‐induced polymerization of ethylene
Authors: Mitsui Hiroshi , Hosoi Fumio , Hagiwara Miyuki , Kagiya Tsutomu
Published: April 2003

The effects of acetylene on the γ‐radiation‐induced polymerization of ethylene were studied from the viewpoint of the gaseous products and polymer structure. The experiments were carried out under a pressure of 400 kg/cm2; the temperature was 30°C; the does rate was 1.1 × 105 rad/hr; and the acetylene content was 0–20%. The solid polymer was obtained in the polymerization of ethylene containing 2.2% acetylene, while the monomer containing 19.7% acetylene gave a yellowish viscous oil. The polymer yield and molecular weight decreased remarkably with acetylene content. The main gaseous product was hydrogen, and trace amounts of butane, butene‐1, butadiene‐1,3, and benzene and its derivatives were also observed. The rate of formation of hydrogen was almost independent of acetylene content and there was no difference in acetylene contents before and after the irradiation was found. The infrared spectra of the polymers showed the presence of vinylidene, trans‐vinylene, and terminal vinyl unsaturations, 1,4‐disubstituted benzene, and carbonyl groups. The contents of trans‐vinylene, terminal vinyl, and methyl groups increased with acetylene content, and that of vinylidene was independent of acetylene content. The monomer reactivity ratios of ethylene and acetylene were evaluated as 45.5 and 66.0, respectively. On the basis of the results, the effects of acetylene on the γ‐radiation‐induced polymerization of ethylene were discussed.
Photo and thermal polymerization sensitized by donor–acceptor interaction. I.N‐vinyl‐carbazole–acrylonitrile and related systems
Authors: Tazuke Shigeo , Okamura Seizo
Published: April 2003

Spontaneous photo and thermal polymerization ofN‐vinylcarbazole (VCZ)–acrylonitrile (AN), VCZ–acetonitrile, AN‐N‐ethylcarbazole, and AN‐ferrocene were studied. These combinations of electron donor with acceptor were thermally rather stable but showed prominent photopolymerizability when the systems were irradiated by near ultraviolet light. The VCZ–AN system showed multireactivity producing VCZ polymer and a copolymer of VCZ with AN. The composition of copolymer was approximately the same as that of polymer produced in radical copolymerization. The effects of additives (DPPH, NH3, H2O, air) indicated simultaneous occurrence of cationic and radical polymerization in the AN–VCZ and acetonitrile–VCZ systems. The results were interpreted on the assumption of initial formation of a cation radical–anion radical pair. The ratio of cationic to radical polymerization differed for photo and thermal polymerization. In no case was anionic polymerization detected.
Polymerization of allyl(vinyl phenyl) ethers and reactions of the resulting polymers
Authors: Kato Masao , Kamogawa Hiroyoshi
Published: April 2003

Solution polymerizations of allyl(o‐vinyl phenyl)ether and allyl(p‐vinyl phenyl)ether with cationic and radical initiators were investigated. Soluble polymers were formed in polymerizations with boron trifluoride etherate and with benzoyl peroxide. In polymerization with azobisisobutyronitrile the polymerization in dilute solution gave a soluble polymer, whereas that in concentrated solution gave a crosslinked, insoluble one. For informationon the polymerization behavior some infrared and ultraviolet spectroscopic investigations of the soluble polymers were made. From these results it appears that polymers with pendant allyl groups are formed in polymerization with boron trifluoride etherate at low temperature, and polymers containing pendant vinyl groups and allyl groups are obtained with the two types of radical initiator. Copolymerizations of these monomers with ethyl vinyl ether and styrene with the use of boron trifluoride etherate were sucessfully effected. Such reactions as Claisen rearrangement, crosslinking induced with radical initiators, and epoxidation with perbenzoic acid were examined for the polymers prepared in the polymerization with boron trifluoride etherate. Good results were obtained for the former two reactions. However, the latter was unsuccessful.
Mechanism of three‐dimensional polymerization of the system methyl methacrylate–glycol dimethacrylate. I. Determination of the structure of the three‐dimensional product
Authors: Jokl J. , Kopeček J. , Lím D.
Published: April 2003

A method has been developed for determinationof structure of a three‐dimensional methyl methacrylate–glycol dimethacrylate copolymer by using NIR absorption spectrometry. The results show that it is possible to determine the content of pendant vinyl groups in the range of approximately 0.5–18% of the crosslinking agent in the monomer.
On the blue‐colored species, possibly assignable to a radical cation, formed by the aromatic hydrocarbon–sulfur dioxide–oxygen system: The polymerization of olefins initiated by aromatic hydrocarbons–oxygen in liquid sulfur dioxide
Authors: Nagai Toshikazu , Miyazaki Tetsuo , Sonoyama Yuzo , Tokura Niichiro
Published: April 2003

It was found that styrene in liquid sulfur dioxide polymerizes, giving polystyrene readily and quantitatively by addition of such aromatic hydrocarbons as anthracene and trans‐ or cis‐stilbene in the presence of oxygen, and the polymerization proceeds via a cationic process. The observations on the electronic spectra and kinetics in the system suggested that the polymerization was initiated by an electron transfer from the aromatic hydrocarbon to oxygen, followed by the formation of styrene radical cation. Supporting evidence of the radical cation is that 1,1‐diphenylethylene in liquid sulfur dioxide in the presence of oxygen shows a peak at λmax = 605 mμ and reacts to give benzophenone and 1,1,3,3‐tetraphenyl‐butene‐1, which are eliminated by addition of a radical or cation inhibitor.
Polymerization of methyl methacrylate in a tetrahydrofuran–maleic anhydride system. Part II
Authors: Berger Jozef , Lazár Milan
Published: April 2003

A donor–acceptor complex consisting of tetrahydrofuran and maleic anhydride initiates photochemical and thermal polymerization of methyl methacrylate. The mechanism of the transformation of this complex was investigated by studying changes in its electrical conductivity, its chemiluminescence, and various influences on its initiating capability (water, air, DPPH, substitution of styrene for methyl methacrylate and of 1,4‐dioxane for tetrahydrofuran). It has been shown that initiation by radicals cannot be clearly excluded and that ionic radicals form in the system and can initiate the anionic growth of the chain.
Studies of the graft copolymerization of methyl methacrylate by means of the photochemical reduction of ceric ion adsorbed on cellulosic materials
Authors: Ogiwara Yoshitaka , Kubota Hitoshi , Ogiwara Yukie
Published: April 2003

It was observed that the rate of reduction of ceric ion adsorbed on cellulose was remarkably accelerated by irradiation with ultraviolet light, and this behavior depended upon the kind of cellulose. When the graft copolymerization of methyl methacrylate on cellulose with adsorbed ceric ion was carried out by irradiation with ultraviolet light, the percent grafting decreased for softwood, bleached sulfite pulp and increased for hardwood semichemical pulp. The average molecular weight of the grafts was observed generally to decrease. If it is assumed that the ceric ions, which are reduced at an accelerated rate in the early stages of reaction with SCP, do not participate in the graft formation, a relation is observed between the modified amount of reduced ceric ion and the number of grafted chains formed, and the molar ratios of these quantities are 12:1 without irradiation and 75:1 to 100:1 with irradiation. Even when the rate of reduction of ceric ion is accelerated, the increase in the number of grafted chains is found to be very small.
Kinetics of the gamma‐radiation‐induced polymerization of ethylene in tert‐butyl alcohol
Authors: Suganuma Fujio , Mitsui Hiroshi , Machi Sueo , Hagiwara Miyki , Kagiya Tsutomu
Published: April 2003

The gamma‐radiation‐induced polymerization of ethylene in the presence of 13–30 ml of tert‐butyl alcohol was carried out under a pressure of 120–400 kg/cm2 at a dose rate of 1 × 103 to 2.5 × 104 rad/hr at 30°C with a 100 ml reactor. The polymerization rate and the molecular weight of the polymer increased with reaction time and pressure and decreased with amount of tert‐butyl alcohol. The polymer yield increased almost proportionally with the dose rate, while the molecular weight was almost independent of it. These results were graphically evaluated, and the rate constants of initiation, propagation, and termination for various conditions were determined. No transfer was observed. On the basis of these results the role of tert‐butyl alcohol in the polymerization is discussed.