bluuebunny/crossref_metadata_2025 huggingface dataset:
Penultimate effect in stereospecific polymerization by ionic mechanism
Authors: Ohsumi Y. , Higashimura T. , Okamura S.
Published: April 2003

To clarify the penultimate effect in the stereospecific polymerization by ionic catalysts, the relationship between the steric structure of the polymer and polymerization conditions was studied for α‐methylstyrene (αMS), methyl vinyl ether (MVE), and methyl methacrylate (MMA) from our result and literature results. Two possible probabilities of an isotactic addition considering the penultimate effect, Pii and Psi, are compared. We define the α value as Psi = αPii. The greater the deviation of the α‐value is from unity, the greater the penultimate effect. It is shown that the α value in a given monomer is constant for a wide range of tacticity in the various conditions. In αMS, the α value is unity and there is no penultimate effect. Otherwise, in the MVE‐BF3.‐O(C2H5)2 system, α is 0.7 and the penultimate effect is present. When MMA is polymerized by alkali alkyl, the α value is changed by the kind of alkali metal, that is, α values in toluene solution are 0.45, 0.65, and 0.75 for Li, Na, and K, respectively.
Poly(chloroaldehydes). III. Poly(dichloroacetaldehyde)
Authors: Rosen Irving , Sturm C. L.
Published: April 2003

Although dichloroacetaldehyde has only one chlorine less than chloral, the polymerization and polymer characteristics are quite different. Dichloroacetaldehyde is readily polymerized by Lewis acid catalysts to polymer with terminal hydroxyl groups. The catalyst BF3·Et2O, at 0°C., produces very high molecular weight polymer, in bulk polymerization. A DPn of about 400 is readily attainable. The characteristics of the polymerization indicate a cationic type, with greater dependence of DP upon chain termination rather than chain transfer. The polymer is readily end‐capped by acetic anhydride, with a pyridine catalyst, to increase its thermal stability. Melting point, infrared spectra, and x‐ray diffraction measurements confirm that the polymer produced under these conditions is amorphous. Cast films of the polymer could be only partially oriented The polymer is soluble in many common organic solvents.
Polymerization and telomerization reaction of olefins with a tertiary amine‐coordinated lithiumalkyl catalyst
Authors: Eberhardt G. G. , Davis W. R.
Published: April 2003

Tertiary amine‐chelated alkyllithium compounds were investigated as catalyst systems for the reactions of olefinic hydrocarbons. Ethylene is polymerized in paraffinic hydrocarbon solution to a high‐melting, low molecular weight polyethylene wax having terminal olefinic unsaturation. A chain‐transfer reaction is interpreted in terms of an olefin displacement reaction. Other olefins with available allylic hydrogen are metallized in this position. The C4 olefins in conjunction with ethylene were found to undergo a telomerization reaction, involving the olefin as telogen and ethylene as taxogen. The structure and the mechanism of formation of these telomeric olefins are discussed.
Phase separation of some acrylonitrile—butadiene—styrene resins
Authors: Gesner B. D.
Published: April 2003

One model and two commercial ABS (acrylonitrile–butadiene–styrene) resins have been separated into three polymeric phases: polybutadiene, styrene–acrylonitrile copolymer, and styrene–acrylonitrile copolymer grafted onto polybutadiene. A third commercial ABS resin has been separated into two polymeric phases: styrene–acrylonitrile copolymer and butadiene–acrylonitrile copolymer.
Base‐catalyzed polymerization of p‐styrenesulfonamides. II. N‐methyl and N‐phenyl derivatives
Authors: Konishi A. , Yoda N. , Marvel C. S.
Published: April 2003

N‐Methyl‐ and N‐phenyl‐p‐styrenesulfonamides have been prepared, and they have been polymerized by basic and radical initiators. The polymers prepared by base catalysis contain units resulting from proton‐transfer polymerization and units of the vinyl type. The ratio of the two recurring units has been established by determining the NH absorption in the infrared. The polymers are completely soluble in strong alkali, which shows that they contain substantial numbers (60–80%) of vinyl‐type units, since a proton‐transfer unit would not have an acidic sulfonamide group to produce solubility.
Gas permeability of three isomeric polyhydroxyethers
Authors: Stenstrom J. A. , Hale W. F.
Published: April 2003

The gas permeation behavior of three isomeric polyhydroxyethers has been studied with the use of hydrogen, helium, oxygen, and carbon dioxide as the test gases. Amorphous polymers were prepared from epichlorohydrin and 1,8‐, 2,8‐, and 1,2‐bis(4‐hydroxyphenyl)menthane at equivalent molecular weight levels and therefore differed only in the position of substitution on the menthane unit. The permeabilities of the 1,8‐, 2,8‐, and 1,2‐isomers were in the approximate ratio of 1:2:4 for each gas at 23°C. Also, this ratio was observed to hold from 23 to 80°C. for carbon dioxide. Since the diffusion constants were found to be in the same ratio, the gas solubilities were essentially identical for the three isomeric polymers. Therefore, the permeability data could be related directly to the steric configurations of the polymers and were consistent with the hypothesis that the permeation process is controlled primarily by the degree of chain packing. Activation energy data were interpreted as an indication that the diffusion mechanism is similar for each of the isomers. In addition, the relationship of permeability, density, and glass transition temperature to steric configuration of the isomeric polymers was discussed.
Inorganic polymers. Part II. The thermal bulk condensation polymerization of P‐phenylphosphonic diamide
Authors: Shaw R. A. , Ogawa Takeshi
Published: April 2003

The thermal bulk condensation polymerization of P‐phenylphosphonic diamide under a variety of conditions is described. Polymerization and degradation processes were observed. The maximum molecular weights attained were about 3000. These polymers, soluble in most organic solvents, are hydrolytically unstable, giving low molecular weight products soluble only in hydroxylic solvents.
Anionic polymerization of ω‐lactam. Part II. Polymerization of ε‐caprolactam by alkali metal and imino chlorides
Authors: Yasumoto Takaya
Published: April 2003

It has been found that imino chlorides may be used as cocatalysts for the alkaline polymerization of ε‐caprolactam. Addition of an imino chloride shortens the induction period before polymerization, and the polymerization proceeds rapidly at a low temperature below the melting point of the polymer. A mechanism is proposed for the anionic polymerization of ε‐caprolactam with alkali metal and an imino chloride. It involves the formation of a reactive N‐imidoyl lactam and chain propagation by the stepwise addition of anionic lactams at the end of a molecule. The conditions for the polymerization have been carefully investigated. As the concentration of imino chloride increases, the conversion and relative viscosity increase slightly, but ε‐caprolactam is unpolymerizable when equimolar quantities of imino chloride and alkali metal are present, or when there is a higher concentration of imino chloride than of alkali metal.
Determination of degree of crosslinking in natural rubber vulcanizates. Part VII. Crosslinking efficiencies of di‐tert‐butyl and dicumyl peroxides in the vulcanization of natural rubber and their dependence on the type of natural rubber
Authors: Bristow G. M. , Moore C. G. , Russell R. M.
Published: April 2003

The efficiency with which di‐tert‐butyl peroxide and dicumyl peroxide vulcanize (crosslink) natural rubber depends on the type of natural rubber. Crosslinking efficiencies of the peroxides are increased by acetone extraction of the rubber and by increasing the concentration of peroxide but in no case studied was either peroxide 100% efficient. These findings indicate that the natural rubber samples contain non rubber compounds which compete with the rubber hydrocarbon for reaction with the peroxide. The implications of these findings are: (1) that the values of chemical crosslinks determined by Moore and Watson from the yields of tert‐butyl alcohol and methane formed when an unextracted deproteinized pale crêpe is crosslinked with di‐tert‐butyl peroxide may be overestimated; and, thus, (2) the calibration of Mullins which relates the number of chemical crosslinks in a natural rubber–peroxide vulcanizate to the number of physically manifested crosslinks may require revision.
Aromatic poly(phenylene)4‐phenyl‐1,2,4‐triazoles
Authors: Holsten J. R. , Lilyquist M. R.
Published: April 2003

High molecular weight poly(m‐,p‐phenylene)4‐phenyl‐1,2,4‐triazole has been prepared by the cyclocondensation reaction of aniline with high molecular weight poly(m‐,p‐phenylene) hydrazide in polyphosphoric acid (PPA). It is proposed that the cyclocondensation reaction proceeds through the attack of “free” aniline on either or both of two intermediate substrate polymers (a polyhydrazide phosphate and/or a protonated polyoxadiazole) to provide the desired polytriazole composition. The nature of the intermediate substrate polymer is determined primarily by the reaction temperature. Known model compounds containing the 4‐phenyl‐1,2,4‐triazole ring were prepared from model hydrazide compounds under cyclocondensation reaction conditions to demonstrate the validity of this synthesis approach to the polytriazoles. Thermally stable fibers and films having maximum zero strength temperatures of 465 and 490°C., respectively, have been prepared from formic acid solutions of poly(m‐,p‐phenylene)4‐phenyl‐1,2,4‐triazole. Thermogravimetric and differential thermal analyses of this polymer showed that the polymer was stable in nitrogen up to 512°C.
NMR study of vinyl chloride–vinylidene chloride copolymer
Authors: McClanahan J. L. , Previtera S. A.
Published: April 2003

A study of the proton magnetic resonance spectra of poly(vinyl chloride) (PVC), poly(vinylidene chloride) (PVDC), and vinyl chloride–vinylidene chloride (VC–VDC) copolymer has resulted in a clearer understanding of the copolymer NMR spectra. Comparison of the homopolymer spectra with the copolymer spectra, including information obtained from decoupling experiments, indicated that the chain structure of the eight copolymers studied were of two different types. The simplest type copolymer chain contained head‐to‐tail VDC sequences, head‐to‐head or tail‐to‐tail VDC sequences, and VC‐VDC sequences. The second type copolymer contained all of the sequences of type I copolymers and, in addition, contained VC sequences. The average length of these VC sequences was less than four VC units. The composition of seven of the copolymers was determined by chlorine analysis and by an NMR method of analysis which was based on the above conclusions. The agreement between the results of the two methods of analysis was quite good.
Thermochemistry of polymerization part III. Thermochemical aspects of propagation of polymerization
Authors: Sawada Hideo
Published: April 2003

A statistical thermodynamic method of treating propagation of polymerization is developed. The effect of temperature on the sequence distribution of syndiotactic and isotactic units in free‐radical polymerization is discussed. This theory applies to the problem of probabilities of various possible modes of addition, namely head‐to‐head and head‐to‐tail addition, 1–2 and 1–4 addition, and formation of cis and trans configurations.
Contribution à l'étude de l'ionisation des polyelectrolytes à l'interface air–eau
Authors: Jaffe J. , Ruysschaert J.‐M.
Published: April 2003

Monolayers of poly‐2‐vinylpyridine (2‐PVP), of poly(methacrylic acid) (PMA), as well as of a polyampholyte containing definite proportions of 2‐vinylpyridine and acrylic acid were investigated at the air–water interface. We studied particularly the ionization of the film. The variation of surface pressure with respect to the nature of the ionic subsolution was analyzed. At constant degree of ionization, two factors determine the surface pressure: the valence and the dimension of the counterion. The polyampholyte may be considered alternatively as a polycation or a polyanion depending on the pH value of the support. The small concentration of dipolar ions permits the presence in the same macromolecule of the properties of the poly‐2‐vinylpyridine and of the poly(methacrylic acid). Qualitatively, the influence of the counterions is reproduced for the three polyelectrolytes. With monovalent ions, a quantitative approach is possible. The surface pressure is analyzed in terms of current theories of the ionic double layer. The application of the Gouy‐Chapman model gives satisfactory results at different polymer and ionic concentrations. The theory has been extended with success to completely and incompletely ionized monolayers. However, there is evidence that the Gouy‐Chapman theory is obeyed only at high areas. For denser films, the discrepancy between the calculated and experimental pressure is often quite large. The inclusion of a “fluctuation potential” contribution to the surface pressure permits a good agreement between the theory and the experiments.
Melting point and heat of fusion of poly(vinyl alcohol)
Authors: Tubbs Robert K.
Published: April 2003

Differential thermal analysis was used to study the effect of a diluent, glycerol, and copolymer units, acetate groups, on the melting point of poly(vinyl alcohol) (PVA). The melting point of PVA was found to be 228°C. and the heat of fusion by the diluent and copolymer methods was 1.64 and 0.56 kcal./mole, respectively, based on vinyl alcohol units. Flory's theory was used as a basis for analysis. The results are compared with literature values for the heat and entropy of fusion of polyethylene, and the differences briefly discussed.
Polydisperse polymers with random trifunctional branching. I. Evaluation of the extent of branching
Authors: Shultz A. R.
Published: April 2003

The relation of intrinsic viscosity of weight‐average molecular weight and branch density is derived for polydisperse polymers having randomly distributed trifunctional branch points. The results are obtained by specializing and approximating a general molecular distribution function derived by Stockmayer and incorporating this function into the polymer solution viscosity treatment of Zimm and Kilb. Numerical values of the molecular size distribution function and of the intrinsic viscosity functions are tabulated for selected branch densities.
Fractionation of cellulose trinitrates by gel permeation chromatography
Authors: Segal Leon
Published: April 2003

Samples of the four polymorphic forms of cellulose (I, II, III, and IV) have been nitrated and examined by means of gel permeation chromatography (GPC). Shifts in the differential and integral distribution curves indicate that the processes for lattice conversion affect the molecular weight distribution of the cellulose molecules in the samples. Weight‐average and number‐average degrees of polymerization for the four samples exhibit trends parallel to those observed in the average degrees of polymerization of the initial celluloses measured viscometrically where the celluloses were dissolved in cupriethylene diamine and in cadmium ethylene diamine hydroxide solutions. The weight‐ and number‐average values, however, are markedly greater than the viscosity values. The order of magnitude of the GPC data, however, was similar to average degrees of polymerization of cellulose reported in the literature which were obtained by other methods.
Co60 γ‐radiation‐induced copolymerization of ethylene and carbon monoxide
Authors: Colombo P. , Kukacka L. E. , Fontana J. , Chapman R. N. , Steinberg M.
Published: April 2003

The γ‐radiation‐induced free‐radical copolymerization of ethylene and CO has been investigated over a wide range of pressure, initial gas composition, radiation intensity, and temperature. At 20°C., concentrations of CO up to 1% retard the polymerization of ethylene. Above this concentration the rate reaches a maximum between 27.5 and 39.2% CO and then decreases. The copolymer composition increases only from 40 to 50% CO when the gas mixture is varied from 5 to 90% CO. A relatively constant reactivity ratio is obtained at 20°C., indicating that CO adds 23.6 times as fast as an ethylene monomer to an ethylene free‐radical chain end. For a 50% CO gas mixture, the above value of 23.6 and the copolymerization rate decrease with increasing temperature to 200°C. The kinetic data indicate a temperature‐dependent depropagation reaction. Infrared examination of copolymers indicates a polyketone structure containing CH2CH2 and CO units. The crystalline melting point increases rapidly from 111 to 242°C., as the CO concentration in the copolymer increases from 27 to 50%. Molecular weight of copolymer formed at 20°C. increased with increasing CO, indicating M̄n values >20,000. Increasing reaction temperature results in decreasing molecular weight. Onset of decomposition for a 50% CO copolymer was measured at ≈250°C.
Radiation‐induced graft polymerization of styrene to poly(vinyl chloride)
Authors: Takamatsu Toshiaki , Shinohara Kenichi
Published: April 2003

The radiation‐induced graft polymerization of styrene to poly(vinyl chloride) (PVC) was investigated. Relations between the rate of grafting and the dose rate when the polymer is irradiated in liquid monomer or in monomer vapor, and between the rate of grafting and monomer concentration absorbed in the polymer have been investigated. The rate of grafting in monomer vapor was found to be far larger than that in liquid monomer. A high rate of grafting in monomer vapor was thought to result from a lower concentration of monomer in PVC during irradiation. An experiment carried out on PVC containing the monomer at various concentrations showed that the rate is largest at a monomer concentration of about 3.5 mole/l. and is smaller for higher and lower concentrations. On the assumption that the theory of homogeneous homopolymerization can be applied to this grafting reaction, the value of kp2/kt has been obtained, where kp and kt are propagation constant and termination constant, respectively. The value of kt greatly increases when the monomer concentration exceeds 3.5 mole/l. This increase of kt can be accounted for if it is assumed that the monomer absorbed in the polymer works as a plasticizer and increases the molecular motion of the polymer. A measurement of the elastic modulus of PVC containing the monomer at various concentrations showed that this is, in fact, the case.
NMR study of model compounds of vinyl polymers
Authors: Fujiwara Yuzuru , Fujiwara Shizuo , Fujii Kiyoshi
Published: April 2003

Complicated NMR spectra of vinyl polymers provide conformational and configurational knowledge of the polymers in solution. Explicit expressions for the spectral frequencies and intensities are obtained by the analysis of vinyl polymers and their model compounds as weakly coupled systems. The classified spectra expected for common vinyl polymers are presented by using the results of the analysis. The analysis is applied to model compounds of poly(vinyl alcohol) and poly(vinyl acetate) in solution. The results show that conformations of poly(vinyl alcohol) are determined by the intramolecular hydrogen bonding so that the syndiotactic isomer forms a helical structure, the isotactic one a planar zigzag structure. The poly(vinyl acetate) produces a helical structure for isotactic isomer by the repulsion of side chains and a planar zigzag for the syndiotactic isomer.
Polymerization with organoboron compounds
Authors: Arimoto F. S.
Published: April 2003

In the presence of organoboron compounds, free‐radical polymerization of vinyl monomers can proceed in spite of the presence of excess of typical radical inhibitors. The concept of free radical–organoboron complex formation is introduced to explain the unique role of organoboron compounds in such a polymerization system.
Polymerization of five‐, six‐, and seven‐membered ring lactams by using metallic potassium or metallic aluminum alkylate as catalyst and certain N‐acyl lactams or diphenyl ketene as initiator
Authors: Tani Hisaya , Konomi Tuyoshi
Published: April 2003

Polymerization of five‐, six‐, and seven‐membered lactams by metallic potassium or MAlEt4 (where M is Li, Na, or K) as a catalyst and N‐acyl lactam or diphenylketene as an initiator was carried out at temperatures below 80°C. By using MAlEt4 instead of a metallic potassium catalyst in the polymerization of α‐piperidone the propagation was continued until the reduced viscosity of polymer reached a value of 0.9. The polymer obtained has a film‐forming ability. The experimental results obtained in the gasometry suggest that MAlEt4 reacts with lactam to form such a complex of the type
magnified image
(where M is Li, Na, or K and X is an ethyl or 2‐oxo‐alkylene‐imine group). The resulting complexes are considered to increase the solubility of catalyst and also to protect the polymer endgroups from side reactions by stabilizing the alkali metal as the complex. In addition, the mode of action of diphenylketene as an initiator was revealed by the facts that the corresponding N‐diphenylacetyl lactam was obtained from the reaction of diphenyl ketene with lactam and N‐diphenylacetyl lactam itself was useful for the polymerization of α‐piperidone.
The role of diffusion in propylene polymerization
Authors: Begley J. W.
Published: April 2003

The role of monomer diffusion in the polymerization of propylene by organometallic catalysis was examined by use of mathematical models which couple the rate of diffusion through the polymer film surrounding the catalyst with the rate of surface reaction. An approximate form of a second‐order, integrated rate equation was used to describe the disappearance of active sites on the surface. For the most conservative model conceivable, it was estimated that the particle size would have to be 10–100 times the size for the catalysts presently in use before diffusion time would be significant. The size of the catalysts was determined by photomicrographs and nitrogen adsorption surface areas. The surface areas for three different catalysts were 7, 20–21 and 35 m.2/g., respectively. The kinetic model without the diffusion term was used satisfactorily to correlate productivity data. The characteristic decline in reaction rate was examined in terms of the decay of active sites on the surface of the catalyst. The rate of decay was determined to be second order with respect to the site concentration. The kinetic model indicates that the total polymerization time for a specified productivity is the sum of the monomer diffusion time and the surface reaction time. The model derived by use of an approximate second‐order decay function is unique because of the additivity of diffusion and reaction times, which is not the case when the second‐order function is used rigorously.
Pyrolysis of vinyl and vinylidene fluoride polymers: Influence of prior γ‐irradiation
Authors: Wall L. A. , Straus S. , Florin R. E.
Published: April 2003

Quantitative comparisons were made between the rates of thermal volatilization of several fluoropolymers before and after exposure to γ‐radiation. The effects of γ‐irradiation on poly(vinyl fluoride) and poly(vinylidene fluoride) were also investigated by swelling and sol‐gel ratios. With both polymers as well as with polytrifluoroethylene, crosslinks occur predominantly, though there is an appreciable number of scissions. The rates of volatilization and char formation were enhanced by γ‐radiation, whereas the previously studied polytrifluoroethylene did not produce more char upon irradiation, although radiation did accelerate its volatilization. It is believed that in polytrifluoroethylene the enhanced rates of volatilization occur by a different mechanism than in the case of the vinyl and vinylidene fluoride polymers.
γ‐Radiation‐induced ionic polymerization of pure liquid styrene
Authors: Potter R. C. , Johnson C. L. , Metz D. J. , Bretton R. H.
Published: April 2003

Pure liquid styrene, carefully purified and exhaustively dried, exhibits kinetic behavior under γ‐irradiation that can best be described in terms of an ionic mechanism. This is based on the observed linear dependence of the rate of polymerization on the dose rate, the independence of molecular weight on the same parameter, and comparison with the thermal and ultraviolet initiated polymerization of monomer prepared under the same stringent conditions. The highest rate of conversion to polymer is 400%/hr. at a dose rate of 106 rads/hr., corresponding to a G(‐monomer) ≈ 40,000.
Kinetics of heterogeneous cellulose reactions. I. Cyanoethylation of cotton cellulose
Authors: Chatterjee Pronoy K. , Conrad Carl M.
Published: April 2003

Sakurada's equation and fundamental kinetic laws were applied to the heterogeneous cyanoethylation of cellulose, performed by reacting fiber with liquid acrylonitrile, with sodium hydroxide as the catalyst. The data fit Sakurada's equation better at higher temperatures; deviation occurs at the initial stage, and the rate of reaction falls abruptly at a later stage. The degree of substitution at which the abrupt rate change occurred decreased as the temperature increased from 31 to 60°C. and also as the crystallinity of the fiber decreased. Diluting the reagent with different solvents decreased the rate of reaction and changed its transition points, but did not change the essential nature of the reaction, each segment of which fits Sakurada's equation very well. A uniform distribution of the catalyst (sodium hydroxide) throughout the fiber was attempted, and then the reaction was studied at 50°C. Diffractograms of the samples provided further evidence that the position of the rate change is associated with the change of cellulose (I) crystalline structure. Approximate energy of activation has been calculated, from the specific rate constants, between 31 and 40°C. as 10.6 kcal. and between 45 and 50°C. as 16.7 kcal. At other temperatures the determination was handicapped, due to temperature dependence of the order of reaction. An empirical relation between the constants of Sakurada's equation and the reaction temperature has been sought and correlated with the Arrhenius equation. Energies of activation, determined from this relationship, have been found to be very close to the above values. The change of order of reaction with temperature suggests that the reaction is affected by diffusion and the mechanism is interpreted as a diffusion‐controlled reaction where hydrogen bonds play a significant role in diffusion.
Increased rates of initiation of polymerization by 4‐4′‐dicyano‐4‐4′‐azopentanoic acid in the presence of ferric salts
Authors: Cavell E. A. S. , Gilson I. T.
Published: April 2003

The initiation of the polymerization of acrylamide by 4‐4′‐dicyano‐4‐4′‐azopentanoic acid in aqueous solution has been studied kinetically at 25°C. Ferric chloride and ferric sulfate were used to terminate polymerization so that rates of initiation could be calculated from the rates of production of ferrous iron. Velocity coefficients at 25°C. for the initiation reaction were found to be (25.7 ± 2.8) × 10−7 sec.−1 for the ferric chloride terminated reaction and (73.6 ± 0.6) × 10−7 sec.−1 for the ferric sulfate‐terminated polymerization. The value reported for the initiation reaction when acrylamide is polymerized in the absence of metal salts is 1.29 × 10−7 sec.−1. Velocity coefficients for the termination reaction have been calculated from the overall rates of polymerization obtained with ferric salts present. In the case of the ferric chloride‐terminated reaction, it has been shown that the rate of polymerization is reduced by increasing the total concentration of chloride ions. Termination velocity coefficients at 25°C. for the inner sphere complexes FeCl2+·5H2O and FeSO4+·4H2O have been calculated to be 18.9 × 104 and 7.98 × 104 l./mole‐sec., respectively. The dependence on the concentration of ferric chloride of the molecular weights of the polymers produced has also been considered.
Polyquinoxalines. III
Authors: Stille J. K. , Arnold F. E.
Published: April 2003

Six thermally stable polyquinoxalines have been prepared by the reactions of combinations of three tetraamines, 3,3′,4,4′‐tetraaminodiphenyl sulfone (II), and 3,3′,4,4′‐tetraaminodiphenyl ether (V), with two bisglyoxals, 4,4′‐diglyoxalyldiphenyl sulfide dihydrate (III) and 4,4′‐diglyoxalyldiphenyl sulfone dihydrate (IV). The polymers were prepared from polymerization in two stages. The first stage, a solution polymerization, produces an initially low or moderate molecular weight material, which is advanced to a high molecular weight (ηinh > 1.0) by heating at 375°C. under reduced pressure. All the polyquinoxalines have excellent thermal stability both in nitrogen and in air and improved solubility.
Inorganic coordination polymers. VII. Zinc(II) dimethyl‐, methylphenyl‐, and diphenylphosphinates
Authors: Rose Selwyn H. , Block B. P.
Published: April 2003

Zinc dimethyl‐, methylphenyl‐, and diphenylphosphinate have been prepared by the reaction of Zn(C2H3O2)2·2H2O with the appropriate acid or salt and found to exist in amorphous and crystalline forms. Zinc methylphenylphosphinate, the most tractable, exhibits many of the physical attributes of polymeric materials, both in solution and bulk form, supporting our earlier suggestion that these compounds are double‐bridged coordination polymers. Thermogravimetric analysis indicates initial decomposition temperatures of 440, 425, and 490°C., respectively, for the three polymers, but long‐term studies show initiation of decomposition at somewhat lower temperatures.
Promotion of base‐catalyzed siloxane rearrangements by dimethyl sulfoxide
Authors: Cooper Glenn D. , Elliott John R.
Published: April 2003

The effect of small amounts (0.01%–1%) of dimethyl sulfoxide on base‐catalyzed polymerization and equilibration of methylsiloxanes has been examined. The addition of 0.5% of the sulfoxide increases the rate of potassium hydroxide‐catalyzed polymerization of octamethylcyclotetrasiloxane by factors of 100–1000 and amounts as low as 0.01% have a large effect when low (12 ppm) catalyst concentrations are used. The rate of basecatalyzed equilibration of hexamethyl disiloxane with octamethylcyclotetrasiloxane is similarly enhanced by dimethyl sulfoxide. The equilibration occurs rapidly at 80°C. with 0.01% of potassium hydroxide and 1% of dimethyl sulfoxide, but does not proceed at a measurable rate with potassium hydroxide alone. The combination of 0.01% potassium hydroxide and 1% dimethyl sulfoxide is more effective than 0.1% of tetramethylammonium hydroxide. The large accelerating effect of the sulfoxide is believed to be due to solvation of the cation, which promotes ionization of the metal silanolate, increasing the concentration of silanolate anions.
γ‐Irradiation of poly(ethylene terephthalate). I. Yields of gas and carboxyl groups
Authors: Burow S. D. , Turner D. T. , Pezdirtz George F. , Sands George D.
Published: April 2003

Poly(ethylene terephthalate) was exposed in vacuo γ‐radiation from a Co60 source at a dose rate of 0.02 Mrad/min., and an ambient temperature of 47°C. Gaseous products were analyzed in a mass spectrometer and carboxyl groups estimated by titration with NaOH and by infrared analysis. Initial G values were COOH = 0.77, CO2 = 0.17, CO = 0.11, H2 = 0.015, and CH4 = 0.003. All these values decreased markedly with increasing dose except G(CO)2, which, roughly, was maintained up to 5000 Mrad. It was considered whether the dependence on dose of the yields of the major reaction products could be accounted for by the following set of first‐order reactions:
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It was found that the rate of formation of COOH groups at low doses was much too high to fit this simple reaction scheme. However, a better fit was obtained over a range of higher doses (ca. 100–5000 Mrad). A final conclusion could not be reached concerning the validity of the above reaction scheme.
Structure–property relationships of poly(vinyl alcohol). II. The influence of molecular regularity on the crystallization–dissolution temperature relationships of poly(vinyl alcohol)
Authors: Harris H. E. , Kenney J. F. , Willcockson G. W. , Chiang R. , Friedlander H. N.
Published: April 2003

Dissolution temperatures Ts have been determined for poly(vinyl alcohol) (PVA) samples of varying tacticity as a function of crystallization temperatures Tc. From the values of Ts and Tc, one can obtain values of (Tm)∞, the dissolution temperature of crystals of infinite stepheight. (Tm)∞ is a characteristic property of a given sample. This method of characterization is very sensitive and reliable for detecting differences in molecular regularity among PVA samples. The variation of (Tm)∞ with stereoregularity is attributed in part to differences in hydrogen‐bonding characteristics. Determinations of the crystallinities of solution‐crystallized PVA have shown that stereoregularity in PVA does not result in higher crystallizability.
Crystallization and dissolution temperatures of poly(vinyl alcohol) crystal lamellae
Authors: Kenney J. F. , Holland V. F.
Published: April 2003

Poly(vinyl alcohol) single crystal platelets having a stepheight of approximately 100 A. were obtained by isothermal crystallization from dilute triethylene glycol solution. Material crystallized at temperature Tc redissolved in the same solvent at a higher temperature Ts. A plot of Tc versus Ts gave a straight line of slope 0.47. Extrapolation of this line to Tc = Ts gave (Tm)∞, which may be regarded as the dissolution temperature of the crystal of infinite stepheight. (Tm)∞ for this sample in triethylene glycol was 220°C. The crystalline nature of the platelets was established by electron and x‐ray diffraction techniques. A total of three Bragg d spacings having the values of 3.9, 4.4, and 4.6 A. (±0.05 A.) were measured. These spacings were indexed as the (200), (101), and (101) reflections, respectively, of the monoclinic unit cell of Bunn. The x‐ray diffractogram exhibits sharp intensities of the (101) and (101) reflections. The crystallinity calculated from the density of the poly(vinyl alcohol) precipitated from dilute solutions in triethylene glycol was 42%. Although the overall degree of crystalline perfection of this poly(vinyl alcohol) is low, the linear relationship between Ts and Tc and the formation of definite shaped single crystals when crystallized from dilute solution suggest that poly(vinyl alcohol) crystallizes in the same manner as other semicrystalline polymers.
Polyoxazolidones prepared from bisurethans and bisepoxides
Authors: Iwakura Yoshio , Izawa Shin‐Ichi , Hayano Fusakazu
Published: April 2003

Linear polymers containing oxazolidone rings in the main chain were prepared from difunctional urethans and epoxides by the synthetic method previously used for reaction of monofunctional urethans and epoxides. The similarity of the infrared spectra of polymers and model compounds, bisoxazolidones, showed the presence of oxazolidone rings in a polymer chain. The solubility and softening temperatures of the polymers varied with the urethan unit but not with the bisepoxide structure. Polymers prepared from p‐phenylenedimethylurethan and variable bisepoxides were insoluble or partially soluble in dimethylformamide, dimethyl sulfoxide, and m‐cresol and had higher softening temperatures. Polymers from m‐phenylenediethylurethan or toluenediethylurethan and bisepoxides were soluble in the organic solvents mentioned above, and had lower softening temperatures.
Enhanced x‐ray diffraction patterns from oriented fibers
Authors: Milberg M. E.
Published: April 2003

The difference x‐ray diffraction pattern can reveal the presence of oriented, ordered material whose conventional diffraction pattern is masked by that of unoriented, disordered material. It is shown that this enhancement results from the fact that scattering from only oriented material contributes to the difference intensity, defined as the difference between the scattered intensity and its average over the polar angle in intensity space. Difference patterns of lightly crosslinked natural rubber, obtained as a function of elongation, show the development of crystallinity at smaller elongations than do the corresponding conventional patterns and indicate that nearly all the oriented material is crystalline. The difference and conventional patterns were obtained from the same diffractometer data. Photographically recorded diffraction patterns are intermediate between the conventional and difference diffractometer patterns in sensitivity to crystallinity. The difference diffraction pattern of a highly oriented atactic polystyrene fiber shows no evidence of crystallinity, the halos on the difference pattern being just as broad as those on the conventional pattern with no apparent tendency to break up into crystalline lines.
Alternating copolymerization of ethylene with maleic anhydride
Authors: Machi Sueo , Sakai Takashi , Gotoda Masao , Kagiya Tsutomu
Published: April 2003

The copolymerization of ethylene with maleic anhydride was carried out with γ‐radiation and a radical initiator, i.e., 2,2′‐azobisisobutyronitrile and diisopropyl peroxydicarbonate under pressure at various reaction conditions. The homopolymerization of neither monomer was observed in this system. In the γ‐ray‐initiated copolymerization the G value (polymerized monomer molecules per 100 e.v.) was shown to be between 103 and 104. It was found that the dose rate exponent of the rate is approximately unity, and the rate is proportional to the amount of ethylene monomer. Apparent activation energies of 1.8 and 27.5 kcal./mole were obtained for γ‐ray‐initiated and AIBN‐initiated copolymerization, respectively. Since the composition of copolymer is independent of monomer molar ratio and the molar ratio of ethylene to maleic anhydride in the polymer is approximately unity, the monomer reactivity ratios were obtained as rE ≃ 0 and rM ≃ 0 for γ‐ray‐initiated polymerization at 40°C. Alternating copolymerization was, therefore, concluded to occur. Infrared analysis of the copolymer is almost consistent with this. The copolymer in the solid state is amorphous. It is soluble in water, cyclohexane, and dimethylformamide and insoluble in lower alcohols, ether, and aromatic hydrocarbons. The aqueous solution of polymer gave a strong acid.
Chain transfer in ethylene polymerization
Authors: Mortimer George A.
Published: April 2003

Chain transfer constants in the homogeneous free‐radical polymerization of ethylene at 1360 atm. and 130°C. have been determined for over 50 compounds, including nearly 300 hydrocarbons. The effects of substitution, unsaturation, and ring strain in the transfer agent molecule on the reactivity of its CH bonds in chain‐transfer reactions with a polyethylene growing chain are analyzed. Qualitatively, these trends parallel those found for simple radicals attacking simple molecules. However, the principle that the reactivity of a compound is the sum of the reactivities of all reactive bonds, which is well established for simple radicals and transfer agents, is found not to be true in ethylene polymerization. It is postulated that the deviations from this principle are due to steric factors which become very important when the free radical is bulky. The transfer constants measured in ethylene polymerization are also compared with transfer constants in other systems. A strong correlation is found between the transfer constants in ethylene and published data on rates of abstraction of hydrogen atoms by methyl radicals.
Studies on some radical transfer reactions. Part I. Hydrogen atom abstraction from some organic substrates by ȮH radicals
Authors: Mitra Bhairab Chandra , Chadha Subhash Chander , Ghosh Premamoy , Palit Santi R.
Published: April 2003

Polymerization of methyl methacrylate was carried out in aqueous and nonaqueous media in the presence of some sulfonated and carboxylic organic compounds, hydroxyl radicals generated from hydrogen peroxide being used as initiators of polymerization. The occurrence of radical transfer reactions by way of hydrogen atom abstraction from the organic substrates by the ȮH radicals was demonstrated by the detection of sulfonate and carboxyl endgroups in the respective polymers. It was found that the radical transfer reactions were more favored in aqueous media than in nonaqueous systems.
Stereospecific polymerization of α‐methylstyrene by friedel‐crafts catalysts
Authors: Oh Sumi Y. , Higashimura T. , Okamura S.
Published: April 2003

The relationship between stereoregularity and polymerization conditions of α‐methylstyrene has been studied by means of NMR spectra. The effects of solvents and various Freidel‐Crafts catalysts have been investigated. The stereoregularity of poly‐α‐methylstyrene increased with increased polymer solubility in the solvent used and with decreasing polymerization temperature. This behavior is completely different from the stereospecific polymerization of vinyl ethers and methyl methacrylate in homogeneous systems. This may be due to the strong steric repulsion exerted by the two substituents in the α‐position of α‐methylstyrene. For example, with BF3 · O(C2H5)2 as catalyst at −78°C., atactic polymer is obtained in n‐hexane, a nonsolvent for α‐methylstyrene, whereas highly stereoregular polymer is produced in toluene or methylene chloride, good solvents for the polymer. However, the polarity of the solvent and the nature of the catalyst hardly affect the stereoregularity of the polymer.
Nuclear magnetic resonance and x‐ray determination of the structure of poly(vinylidene fluoride)
Authors: Lando J. B. , Olf H. G. , Peterlin A.
Published: April 2003

In this study, wide‐line NMR and x‐ray diffraction have been used in conjunction to study the crystal structure of poly(vinylidene fluoride). Drawn poly(vinylidene fluoride) film was found to contain two crystal phases, the relative amounts of each depending on the draw temperature. Drawing at 50°C. yields a single phase, designated as phase I, while drawing at temperatures between 120 and 160°C. yields a mixture of phase I and a second phase (phase II). The fraction of phase II increases with increasing draw temperature, but this phase was never obtained without some phase I. A tentative orthorhombic unit cell is proposed for phase II. The structure of phase I has been determined from x‐ray data. The unit cell is orthorhombic, space group Cm2m, having lattice constants a = 8.47, b = 4.90, and c (chain axis) = 2.56 A. There are two polymer chains in this unit cell. The conformation of the polymer chains is planar zigzag. The details of this structure have been confirmed by experimentally determining at −196°C. the change in the NMR second moment with the angle between the magnetic field and the draw direction of phase I (drawn at 50°C.), and by comparing these results with a theoretical calculation of the second moments, based on the atomic positions obtained from the proposed structure.
X‐ray and NMR measurements on irradiated polytetrafluoroethylene and polychlorotrifluoroethylene
Authors: Peffley W. M. , Honnold V. R. , Binder D.
Published: April 2003

The effects of 60Co γ‐radiation on polytetrafluoroethylene (PTFE) and polychlorotri‐fluoroethylene (PCTFE) have been studied for radiation doses up to 940 Mrad. The dependence of per cent crystallinity upon irradiation level has been determined from x‐ray analysis. An initial increase in crystallinity in PTFE, attributable to chain scission in the amorphous phase of the material, was found, followed (above 300 Mrad) by a gradual decrease associated with a disordering of the crystallites. No initial increase was observed for annealed samples of PCTFE due to the large initial value of the per cent crystallinity. Above 200 Mrad the crystallinity was found to decrease with accumulated dose. Nuclear magnetic resonance measurements on PTFE have indicated a radiation‐induced broadening of the amorphous component of the NMR line appearing to maximize above 700 Mrad. Similar measurements of PCTFE have shown a narrowing of the crystalline component of the NMR line and subsequent appearance of the amorphous component at approximately 200 Mrad. The data indicate that the radiation‐induced behavior of PTFE and PCTFE is similar above 200 Mrad.
Polymerization of methyl acrylate in aqueous media
Authors: Morris Carolyn E. M. , Alexander A. E. , Parts A. G.
Published: April 2003

The polymerization of methyl acrylate in water and in dilute, aqueous, soap solutions, initiated by potassium peroxydisulfate, has been investigated, a dilatometric method being used to follow the conversion. It has been shown that small amounts of an anionic soap increase the rate of reaction while a cationic soap has the reverse effect. The change of molecular weight with conversion has also been examined as well as the effect of the exclusion of oxygen from the system.
Non‐newtonian behavior of polymers with log‐normal molecular weight distribution
Authors: Conti W. , Gigli I.
Published: April 2003

By choosing suitable approximations to Bueche's function, it is possible to calculate the viscosity versus shear stress for log‐normal molecularly distributed linear polymers. For bulk polymers the mixing rules M̄w, M̄w, M̄z are considered. For values of η/η0 > 0.1 and heterogeneities with M̄w/M̄n > 1.5 the result obtained with any mixing rule is η/η0 = erfc [(1/delta;) log (M0Qh/aK)], where a = π2/6pRT and where the δ and K values are dependent on the heterogeneity ratio Q = M̄w/M̄n and on the type of mixing rule; on the other hand, the h value is independent of the heterogeneity, but depends on the mixing rule. Most experimental data should fit the M̄w mixing rule as one would expect from the zero shear stress mixing rule. Experimental data are compared with the theoretical results.
Oleophilic ion‐exchange resins. IV. Swelling of quaternary ammonium polymers in mixed solvents
Authors: Shida Mitsuzo , Gregor Harry P.
Published: April 2003

The swelling characteristics of an oleophilic anion‐exchange resin in methanol–benzene and ethanol–chloroform mixed solvent systems were compared with those of a conventional anion‐exchange resin. The oleophilic resin was prepared by amination of chloromethylated polystyrene 1% DVB with N,N‐dimethyldodecylamine. It showed a large shift of the swelling peak from polar to less polar solution compositions in both methanol–benzene and ethanol–chloroform systems as compared with the swelling of conventional resins. Total solvent uptake and solvent distribution between resin and solvent phases were also determined. The less polar solvent (benzene or chloroform) was sorbed preferentially by the oleophilic resin over a wide range of composition, while preference for the more polar solvent (methanol or ethanol) by the conventional resin was shown over the entire composition of the mixed solvent systems. The Newman‐Krigbaum treatment of mixed solvents was applied to swelling data on the ethanol–chloroform–oleophilic resin system, where the volume of the gel network plus the solvent imbibed was relatively constant over the entire range of composition. The result suggests a strong similarity of the liquid–liquid interaction terms in this gel phase compared with those in the pure binary liquid phase.
Polymerizations of some diene monomers. Preparations and polymerizations of vinyl methacrylate, allyl methacrylate, N‐allylacrylamide, and N‐allylmethacrylamide
Authors: Kawai Wasaburo
Published: April 2003

Vinyl methacrylate, allyl methacrylate, N‐allylacrylamide, and N‐allylmethacrylamide were prepared, and these monomers were polymerized in toluene by α,α‐azobisisobutyronitrile catalyst. Cyclization content of poly(vinyl methacrylate) was estimated by infrared spectroscopy to be 50–60% at low conversions, but at the high conversions, due to gelation the polymers were insoluble in the usual organic solvents. Allyl methacrylate did not produce any soluble polymer, even at a low conversion, in contrast with poly‐(vinyl methacrylate). Poly‐N‐allylacrylamide and poly‐N‐allylmethacrylamide were also insoluble in common solvents. It was assumed that the polymers from monomers containing the allyl group might form crosslinks as a result of allyl resonance stabilization.