bluuebunny/crossref_metadata_2025 huggingface dataset:
Polyester formation by the free‐radical copolymerization of cyclohexene and formic acid
Authors: Gebelein Charles G.
Published: April 2003

Cyclohexene and formic acid have been copolymerized to an unsaturated polyester by a free‐radical‐initiated, step‐growth polymerization process. The polymerization system contains iodine and a hydroperoxide in addition to the cyclohexene and formic acid. No polymerization occurs if any one of these components is omitted. The polymerization process is rapid, and polymer yields as high as 95% have been obtained in less than 1 hr. The polymer is an unsaturated polyester and appears to be poly(oxy‐2‐cyclohexen‐1,4‐enylcarbonyl). A step‐growth polymerization mechanism involving formic acid radicals, iodine atoms, and cyclohexene allylic hydrogen atom abstraction has been proposed for this reaction.
Inhibited degradation of nylon 66 in presence of nitrogen dioxide, ozone, air, and near—ultraviolet radiation
Authors: Jellinek H. H. G. , Chaudhuri A. K.
Published: April 2003

Degradation of nylon 66 films of different morphologies was studied in the presence of nitrogen dioxide, ozone, oxygen, and near‐ultraviolet radiation (λ > 2900 Å). Films cast from formic acid solution showed normal random degradation, whereas films cast from benzyl alcohol solutions and dried at elevated temperatures under nitrogen showed very strongly inhibited random degradation. This inhibition may be due to protection of peptide groups by hydrogen bonding with benzaldehyde or benzoic acid or even to their chemical reactions at elevated temperatures. Oxygen was not rigorously excluded during preparation of the films. Degradation of nylon 66 films cast from formic acid solutions at room temperature containing benzaldehyde or benzoic acid, respectively, is also inhibited. The energy of activation for inhibited degradation in presence of nitrogen dioxide is relatively small, indicating that the process is either controlled by diffusion of polymer radicals from medium cages or by diffusion of gases into the polymer. The degradation kinetics can be expressed by “weak”‐link random degradation. The weak links are in the present case unprotected peptide groups. The functional relationship between chain scission rate constants and NO2 pressure is linear.
Perfluoroalkylene‐linked aromatic polyimides. II. Further property studies
Authors: Critchley J. P. , White Mary A.
Published: April 2003

The synthesis and general physical characteristics of the perfluoroalkylene‐linked aromatic polyimides have been discussed in Part I. In this paper the hydrolytic, oxidative, and thermal stabilities of these polymers are compared with those of certain wholly aromatic polyimides. Comparative studies are also made on the effect of the fluoroalkylene chain on the glass transition temperatures. The polymer from di‐(4‐aminophenyl) ether and 1,3‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride has been studied in most detail and various mechanical and electrical properties of this polymer in film and solid molded form are discussed.
NMR and ESR studies of the solid‐state polymerization of vinyl monomers. II. Acrylic acid
Authors: Forchioni A. , Chachaty C.
Published: April 2003

The post‐polymerization of acrylic acid, γ‐irradiated at 77°K, has been studied by broad‐line NMR and ESR between 240°K and 286°K (mp). The changes in the structure of NMR spectra during the polymerization has been related to the conversion yield checked by gravimetry of the polymer formed. The very fast reaction occurring above ⋍270°K has been followed simultaneously by NMR and thermal analysis. This last method indicates an activation energy of chain propagation of 18.6 ± 2 kcal/mole in satisfactory agreement with the value given by the initial slope of the conversion—time curves. ESR experiments show that, while the average radical concentration decays by a factor of about ten between 77°K and 240°K, the local concentration of radicals persisting after prolonged annealing at T > 240°K, remains the same as at 77°K, i.e., 1.4 × 1019 spins/g. A kinetic scheme, assuming an exponential decay of propagation and termination rate constants with chain length, has been proposed to explain the shape of conversion—time curves as well as the almost constancy of the local concentration of growing polymer chains.
Electron paramagnetic resonance spectroscopy of γ‐irradiated cellulose and related compounds
Authors: Ahmed A. U. , Rapson W. H.
Published: April 2003

EPR studies were carried out on different irradiated cellulosic materials. The shape of the EPR spectrum was found to depend upon the fine structure of cellulose. The peak‐to‐peak distances of the large peaks on the differential curves were found to be 23.3 and 24.8 gauss, respectively, for the amorphous and recrystallized cellulose. The number of free radicals present per unit weight in the recrystallized cellulose and in the amorphous cellulose were found to be in the ratio of 2.1:1. The EPR spectrum of a sample of irradiated cotton crystallites which was soaked in acetone before being dried was markedly symmetrical, in contrast to the EPR spectra of samples of cotton linters and of cotton crystallites dried from water, and was considered to be a reflection of the lower intermolecular bonding in the former. For corresponding doses, the free radicals on cotton crystallites have the highest g value, followed by cotton linters, followed by regenerated cellulose I. The g value decreased as the irradiation dose was increased.
1:1 alternating copolymers of 1‐bicyclobutanecarbonitrile with styrene
Authors: Hall H. K. , Rhoades J. W.
Published: April 2003

High molecular weight, 1:1 alternating copolymers of 1‐bicyclobutanecarbonitrile with styrene were prepared in tetramethylenesulfone solution by complexing the electron‐poor bicyclobutane monomer with zinc chloride. Methyl 1‐bicyclobutanecarboxylate under these conditions gave copolymers containing a slight excess of styrene units (ratio 1:1.3 to 1:1.8). High molecular weight homopolymers of 1‐bicyclobutanecarbonitrile and of methyl 1‐bicyclobutanecarboxylate were prepared similarly. The tendency of the bicyclobutane nitrile to form 1:1 alternating copolymers is as great as that of its vinyl analog, acrylonitrile, and the synthesis of other alternating copolymers from this monomer should be possible.
Studies on substituted lactams. II
Authors: Klein K. P. , Reimschuessel H. K.
Published: April 2003

Synthesis and reactions of 4‐carboxy‐6‐alkyl‐2‐piperidones and 4‐carboxyl‐6‐alkyl‐2‐pyrrolidones are described. Upon heating, the substituted 4‐carboxy‐2‐piperidones underwent both polymerization to polysuccinimides and isomerization to pyrrolidone derivatives. No polymerization but isomerization to ethylidene succinimide was observed upon heating the substituted 4‐carboxy‐2‐pyrrolidone. Both polymerization and isomerization can be explained by mechanisms discussed previously.
Gas‐phase copolymerization of sulfur dioxide and butene‐1
Authors: Brown J. R. , O'Donnell J. H.
Published: April 2003

Mixtures of sulphur dioxide and butene‐1 have been polymerized in the gas phase to the 1:1 alternating copolymer by electron irradiation. The rate of polymerization, measured by the decrease in gas pressure, decreased with increase in temperature over the range −20 to +30°C. The initial G(‐monomer) values decreased from 500 to 50 giving an Arrhenius activation energy of −30 kJ mol−1. These results are consistent with a ceiling temperature‐pressure relationship. The ceiling temperature is about 60°C lower than that observed previously in the liquid phase in accord with thermo‐dynamic prediction.
Stereoregularity of poly(methyl α‐chloroacrylate)
Authors: Uryu Toshiyuki , Ito Katsuhiko , Matsuzaki Kei
Published: April 2003

Triad and tetrad tacticities of poly(methyl α‐chloroacrylate) and poly(methyl α‐chloroacrylate‐β‐d1) were determined by nuclear magnetic resonance (NMR) spectroscopy. Methyl α‐chloroacrylate‐β‐d1 and its polymer were first synthesized. Isotactic poly(methyl α‐chloroacrylate) was prepared with ethylmagnesium chloride‐benzal‐acetophenone in combination as catalyst. The syndiotacticity of radically polymerized polymers increased with decreasing polymerization temperature. For radical polymerization, enthalpy and entropy differences between isotactic and syndiotactic additions were calculated to give ΔH − ΔH = 850 cal/mole and ΔS − ΔS = 0.93 eu. The stereoregularity of the polymer prepared with phenylmagnesium bromide catalyst was analyzed in fairly good agreement with first‐order Markov statistics, while polymerization with fluorenyllithium seems predominantly to proceed by a mechanism similar to free‐radical mechanism. Stereoregularity‐controlling power for individual substituents is briefly discussed.
Telechelic diene prepolymers. V. Copolymers with 4‐chlorostyrene
Authors: Reed Samuel F.
Published: April 2003

Copolymers of butadiene, isoprene, and chloroprene with 4‐chlorostyrene have been prepared with hydroxyl and carboxyl terminal groups, 4,4′‐azobis(4‐cyano‐n‐pentanol) and 4,4′‐azobis(4‐cyanovaleric acid), respectively, being used as the initiators. The copolymerizations were carried out in dioxane solution to give liquid prepolymers of low molecular weight capable of undergoing conventional chain‐extension reactions and suitable for utilization as encapsulating resins. Preparative and prepolymer characterization properties are described.
A new simple synthesis of soluble high molecular weight polyphenylenes by the cotrimerization of mono‐ and bifunctional terminal acetylenes
Authors: Chalk A. J. , Gilbert A. R.
Published: April 2003

The monofunctional acetylenes, phenylacetylene and m‐ethynyltoluene, were each copolymerized with diethynylbenzene in a 1:1 mole ratio by using TiCl4/3AlEt2Cl as cyclotrimerization catalyst. The aromatic polymers which were produced were polydisperse with a molecular weight of ∼10,000. Variation of catalyst concentration had no effect on the molecular weight profile. An excess of bifunctional acetylene produced some insoluble gel but when some of the monofunctional acetylene was withheld and added only after an initial molecular weight build‐up by the excess bifunctional acetylene, soluble polymers with molecular weights of approximately 50,000 were obtained in high yield, provided the overall ratio of mono‐ to bifunctional acetylene was maintained at 1:1. The resulting polyphenylenes were highly soluble in benzene and chlorinated solvents but gave brittle films. This was attributed to a highly branched structure resulting from a lack of specificity by the catalyst. Thermogravimetric analysis showed the polymers to have high thermal stability.
Strahlenchemische pfropfung aus der monomerdampfphase von polymeren an der oberfläche von füllstoffen als methode ihrer aktivierung
Authors: Taubman A. B. , Yanova L. P. , Blyskosch G. S. , Ryabchikova G. G. , Glasunov P. Y.
Published: April 2003

The vapor‐phase radiation graft polymerization of styrene, methyl methacrylate, and acrylonitrile on surface of dispersed filler (magnesium oxide) was studied. It was established that the polymer graft films are irreversibly chemically bound to the surface, cover it with a discontinuous layer which leaves a part of the surface free from polymer in the form of a mosaic. The grafting modifies the surface and increases the compatibility of filler with the polymer medium.
Preparation of polyimides from pyromellitic dithioanhydride and aromatic diamines
Authors: Imai Yoshio , Kojima Katsunori
Published: April 2003

The reaction of phthalic thioanhydride and aniline yielded N‐phenylphthalimide quite readily. The reaction was strongly dependent on solvent and temperature. Various additives tried as a reaction promoter were almost ineffective. By the extension of the model reaction, polyimides were prepared in a simple one‐step synthesis from pyromellitic dithioanhydride and aromatic diamines in dimethylacetamide or other solvents. Polymers with inherent viscosity up to 0.3 in concentrated sulfuric acid were obtained in approximately quantitative yield.
Kinetics of transesterification in the formation of polyesters
Authors: Utracki L. A.
Published: April 2003

The overall third‐order transesterification reaction, comprising one order each with respect to hydroxyl group, ester group, and catalyst, was considered on assuming a varying reactivity of OH group. The integrated expression for the catalyzed (constant catalyst concentration) reaction predicts an apparent order of reaction n dependent on the extent of reaction p: for p → 0, n = 2; whereas p → 1, n = 5/4. For practical reasons the order of reaction was redefined in terms of (1 − p) ∝ P, (where Pn is the number‐average degree of polycondensation). The integrated expression was compared with published experimental results of diphenyl carbonate transesterification by 4,4,‐isopropylidene diphenol. At T < 200°C, the expression was well obeyed, at 200 < T < 230°C the reaction showed an intermediate behavior, whereas at still higher temperatures the third‐order reaction was found. It is proposed that these changes are due to variations in the chemical nature of the zinc catalyst, resulting in the difference in the transesterification mechanism. A convenient approximate relation for calculating Pn from measured viscosity‐average degree of polymerization Pv is also proposed.
Fluorination of polyhydrofluoroethylenes. I. Direct fluorination of poly(vinyl fluoride) film
Authors: Shinohara H. , Iwasaki M. , Tsujimura S. , Watanabe K. , Okazaki S.
Published: April 2003

It has been demonstrated that the poly(vinyl fluoride) film can be fluorinated by exposing the polymer to an environment of fluorine under atmospheric pressure and at ambient temperature. Fluorine content, infrared spectra, thermal properties, and solubilities in the polar solvents were investigated for the fluorinated products and the following results were obtained. In the case of films less than 10 μ in thickness, the fluorination appeared to proceed homogeneously. Under any fluorinating conditions applied, i.e., fluorine pressure of up to 800 mm Hg and temperatures of up to 90°C, the fluorine content never exceeded 65% which corresponds to a composition of C2F2.5H1.5. The activation energy of the reaction was calculated to be 6.8 kcal/mole. The polymer reacted with a small amount of oxygen contained in the fluorine to form acyl fluoride groups. The fluorinated films became insoluble in boiling N,N‐dimethylformamide, N,N‐dimethylacetamide, and dimethyl sulfoxide, but colored gradually to a dark brown. The occurrence of some crosslinking in the products was revealed.
Alternating copolymer of butadiene and propylene. IV. Studies on the catalysts for alternating copolymerization
Authors: Furukawa Junji , Hirai Ryuichi
Published: April 2003

The catalysts for alternating copolymerization of butadiene and propylene were investigated by means of ESR technique and potentiometric titration. It was found that several kinds of active species for the production of alternating copolymer, 1,2‐polybutadiene, and trans‐1,4‐polybutadiene are formed, depending upon the catalyst composition of VO(acac)2Et3AlEt2AlCl. ESR and potential titration studies suggest that the active species for alternating copolymerization is a divalent vanadium compound existing in an associated form.
Gel‐permeation chromatography. VII. Molecular weight detection of GPC effluents
Authors: Ouano A. C.
Published: April 2003

A detector system for GPC has been built consisting of a pressure cell and capillary viscometer, a constant‐flow‐rate pumping system, a concentration detector, and a computer interfacing system. This detector system provides two chromatograms; pressure drop (ΔP) versus retention volume and concentration (C) versus retention volume. Since at constant flow rate ΔP is proportional to the effluent viscosity η, the intrinsic viscosity of any effluent fraction can be computed from the equation,

where subscripts 1 and 0 refer to the solution and solvent, respectively. The precision and accuracy of the above technique were evaluated using well characterized broad and narrow molecular weight distribution polymers. Both the precision and accuracy were found to be comparable to light scattering and other classical molecular weight measurement techniques. In its present form, the molecular weight detector system was found to be very sensitive to polymers with very high molecular weights, as expected, and also useful for molecular weights less than 50,000.
Radiation‐induced polymerization of glass‐forming systems. I. Effect of temperature on the initial polymerization rate
Authors: Kaetsu Isao , Okubo Hiroshi , Ito Akihiko , Hayashi Koichiro
Published: April 2003

Radiation‐induced polymerization of hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) was investigated. HEMA and GMA formed a stable supercooled or glassy phase by themselves at low temperatures. It was found that the initial polymerization rate was proportional to ca.0.5 power of the dose rate in the region of relatively high temperatures and the dose rate exponent changed sharply to 1.0 at a temperature Tr, at which the viscosity of monomeric systems reached ca. 103 cP as the temperature decreased. Moreover, a maximum in the polymerization rate–temperature curve occurred at Tv. It was deduced that the polymerization mechanism changed from the stationary to the nonstationary at Tv. The temperature at which a minimum of the polymerization rate occurred could be calculated kinetically considering the viscosity dependency of termination rate, and it agreed well with that obtained experimentally. It was deduced that occurrence of the minimum polymerization rate above Tv was attributable mainly to the decrease in termination rate due to diffusion control.
Radiation‐induced polymerization of glass‐forming systems. II. Effect of temperature on the polymerization rate at higher conversion
Authors: Kaetsu Isao , Okubo Hiroshi , Ito Akihiko , Hayashi Koichiro
Published: April 2003

The effect of temperature and conversion on the polymerization rate at higher conversion was investigated with regard to the γ‐ray‐induced polymerization of hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) in the supercooled phase. The polymerization rate changed from acceleration to depression at various conversions, depending on the polymerization temperature. It was found that Tv at which the viscosity of the system became ca. 103 cpoise influenced the shape of the polymerization time–conversion curve. The experimentally obtained conversion reflection point in the polymerization time–conversion curve agreed with the conversion where the polymerization temperature is the same as the calculated Tv of the system. When the polymerization temperature was lower than Tv of the monomer, no acceleration of the polymerization occurred. When the polymerization temperature was higher than Tv of the polymer, no depression of the polymerization rate was observed. The effect of temperature on the saturated conversion (final conversion) was also examined in terms of Tg of the polymerization system. The experimentally obtained saturated conversion agreed with the conversion where the polymerization temperature is the same as the calculated Tg of the system.
Copolymerization of N‐ethylmaleimide with stilbenes
Authors: Yamakita Hiromi , Hayakawa Kiyoshi
Published: April 2003

Charge‐transfer complexes in solutions of ethylmaleimide and stilbenes have been characterized by spectroscopy. The stoichiometric compositions of these complexes have been shown by Job's method to be 1:1 molar complexes. The value of the equilibrium constant K for complex formation of ethylmaleimide with stilbene derivative increases in the following probable order: ethylmaleimide–stilbene ≪ ethylmaleimide–dimethylaminostilbene (DMAS) < ethylmaleimide–aminodimethylaminostilbene (ADMAS). From the calculations of the electron density of the highest occupied level for the stilbenes, the charge transfer in ethylmaleimide–DMAS and ethylmaleimide–ADMAS is attributed to n → π transition, while the charge transfer in ethylmaleimide‐stilbene is attributed to n → π transition. Copolymerization was carried out by γ‐irradiation in benzene or THF solutions of the comonomer pairs. The alternating tendency of copolymerization was larger in the ethylmaleimide–DMAS system than in the ethylmaleimide–stilbene system. This can be explained by assuming resonance structures in the transition state of addition reaction of DMAS to the propagating ethylmaleimide unit. In the copolymerization of ethylmaleimide with ADMAS, the effect of the penultimate unit was more important than in that with DMAS.
Preparation and properties of polyamide‐sulfonamides
Authors: Imai Yoshio , Okunoyama Hikaru
Published: April 2003

A series of polyamide‐sulfonamides was synthesized by the interfacial polycondensation of m‐ and p‐chlorosulfonylbenzoyl chlorides with aliphatic and aromatic diamines at room temperature. Most of the polymers obtained were high molecular weight, film‐forming materials. They were all amorphous and were soluble in a wide range of acidic and basic solvents. Both aliphatic and wholly aromatic polyamide‐sulfonamides showed initial breakdown in the range of 320–360°C under thermogravimetric analysis in a nitrogen atmosphere.
Synthesis of aryleneisopropylidene polymers
Authors: Fritz A. , Rees R. W.
Published: April 2003

Linear, high molecular weight aryleneisopropylidene (AIP) polymers have been synthesized via Friedel‐Crafts alkylation reactions. Monomers such as p‐bis‐2‐chloroiso‐propylbenzene condense readily with arylene compounds of high electron density such as naphthalene and diphenyl ether. Catalytic amounts of tritylhexafluoroarsenate catalysts in combination with aluminum chloride and nitrobenzene direct the synthetic reactions towards a pure AIP structure. Side reactions which give polyindane structures through dimerization of p‐bis(2‐chloroisopropyl)benzene are eliminated when the polymerization temperature is kept below −20°C. The preferred solvents are chlorinated compounds. A wide range of structural modifications and properties can be obtained by varying the monomer combinations. Desirable physical properties of AIP polymers include clarity, rigidity, impact toughness, oxidative stability, and resistance to stress cracking.
Photosensitivity and photochemical reactions of poly(vinyl p‐azidocinnamate)
Authors: Yabe Akira , Tsuda Minoru , Honda Koichi , Tanaka Hideaki
Published: April 2003

The spectral sensitivity of poly(vinyl p‐azidocinnamate)(PVACi) was discussed by comparison with poly(vinyl cinnamate)(PVCi) and poly(vinyl p‐azidobenzoate). The photochemical reaction of PVACi was investigated with respect to the reactivity of two functional groups, namely, azido and cinnamoyl groups. It was found that cinnamoyl groups dimerized like PVCi and azido groups did not add to double bonds appreciably. The quantum yield of photolysis of azido groups was two times that of dimerization of cinnamoyl groups. A marked wavelength dependence of π–π* and n–π* absorption was observed in both the reactions of azido and cinnamoyl groups.
Electrocondensation polymers: Electrochemical condensation of aromatic diacetyl compounds
Authors: Laube Bruce L. , Higgins Jerry
Published: April 2003

Electrochemical reduction of 4,4′,‐diacetyldiphenylethane at mercury in 80% ethanol/1M potassium acetate produced the pinacols in high yield by the one‐electron/one proton reduction of the carbonyl groups. Although polarographic analysis indicated essentially complete conversion to pinacol, the low inherent viscosities of 0.03–0.06 of the polypinacols implied the presence primarily of oligomers.
The nature of accessible surfaces in the microstructure of cotton cellulose
Authors: Rowland Stanley P. , Roberts Earl J.
Published: April 2003

The accessible regions in cotton cellulose were tagged by the introduction of diethyl‐aminoethyl (DEAE) substituents at DS = 0.034 without other substantial changes in structure. Evidence from rates of hydrolysis of this DEAE cotton to hydrocelluloses and from the composition and structure of the solubilized and insoluble fractions provides the basis for considerable detail regarding two types of accessible regions in the cotton fiber; these are identified as accessible surfaces of elementary fibrils. One type of accessible surface is characterized by molecular chain segments which are distorted and disordered by tilt/twist strain that is concentrated in this segment of the elementary fibril; the second type of accessible surface is characterized by a relatively high degree of order which reflects the high level of crystallinity within the interior of this unstrained segment of the elementary fibril. Substantial differences between these accessible surfaces are discussed. It is estimated that chain segments on accessible surfaces of the first type are substantially disordered, i.e., approximately 60–90% of the D‐glucopyranosyl units are dislocated from positions of perfect crystalline order. Accessible surfaces of the second type are quite highly ordered, i.e., only 5–30% of the D‐glucopyranosyl units dislocated.
Effect of pressure on the radiation‐induced polymerization of ethylene in tert‐butyl alcohol
Authors: Wada Takeshi , Watanabe Terutaka , Takehisa Masaaki
Published: April 2003

The effects of pressure of the radiation‐induced polymerization of ethylene in tert‐butyl alcohol were studied. The reaction was carried out by use of a reactor with a capacity of 100 ml under the following conditions; pressure, 60–400 kg/cm2; temperature, 24 ± 3°C; dose rate, 2.0 × 104−1.6 × 105 rad/hr; amount of medium (tert‐butyl alcohol containing 5 vol‐% water), 70 ml. The results of polymerization were analyzed by a kinetical treatment based on a reaction mechanism with both first‐ and second‐order terminations for the concentration of propagating, radical. On the basis of the kinetical treatment the rate constants of each elementary reaction at several pressures were determined, and the activation volumes of elementary reactions were obtained and are discussed in connection with the reaction mechanism. Consequently, the rate constants of propagation, first‐order termination, and second‐order termination at pressure p and at 24°C were expressed by,
Synthesis of new ordered aromatic polyester copolymers
Authors: Stevenson D. R. , Mulvaney J. E.
Published: April 2003

Aromatic polyesters of 3,5‐di‐tert‐butyl‐4‐hydroxybenzoic acid and 3,5‐diisopropyl‐4‐hydroxybenzoic acid were prepared. The polymers were found to be high‐melting but largely insoluble in organic solvents. The polymer based on 3,5‐di‐tert‐butyl‐4‐hydroxy‐benzoic acid was not degraded to monomer by sulfuric acid. A number of new aromatic polyesters were also prepared. Several new monomers for aromatic polyesters were synthesized, including bis(2,5‐di‐tert‐butyl‐4‐carbophenoxyphenyl)terephthalate, m‐ and p‐phenylene bis(3,5‐di‐tert‐butyl‐4‐hydroxybenzoate), bis(2,6‐di‐tert‐butyl‐4‐chlorocarboxyphenyl)terephthalate, and m‐phenylene bis(3,5‐diisopropyl‐4‐hydroxybenzoate). An aromatic polyester prepared from bis(2,6‐di‐tert‐butyl‐4‐chlorocarboxyphenyl) terephthalate and resorcinol had a ηinh (trichloroethylene) of 1.05 (0.5%, 30°C) and a possible melting point of 330°C (DSC). Tough, creasable films could be cast from trichloroethylene solution of this polymer. Attempts to observe or to trap the keto‐ketene that might result when 3,5‐di‐tert‐butyl‐4‐hydroxybenzoyl chloride is treated with base were unsuccessful.
Long branching in poly(vinyl acetate) and poly(vinyl alcohol). I. Crosslinking and crosslinking cleavage of poly(vinyl acetate)
Authors: Nozakura Shun‐Ichi , Morishima Yotaro , Murahashi Shunsuke
Published: April 2003

A crosslinked network was formed by the reaction of partially saponified poly(vinyl acetate) and toluylene diisocyanate in benzene. The yield of gel was markedly dependent on the degree of saponification and the concentrations of polymer and diisocyanate. Crosslinked poly(vinyl alcohol) was obtained by treating the poly(vinyl acetate) with a catalytic amount of sodium hydroxide in methanol without any change of the urethane crosslinks. The crosslink based on the urethane linkage was quantitatively cleaved by acids, especially by hydrobromic acid, releasing polymers of the same molecular weight as the original.
Correlations to evaluate permeation of vapor and liquid hydrocarbons through polymer membranes
Authors: Leitão Dorodame Moura , Santos Marcos Luiz Dos
Published: April 2003

It has been shown in this investigation that the permeation of propane and propylene through polyethylene membranes exhibit a generalized behavior in the vicinity of the condensation point of the penetrant. Correlations to evaluate the permeation flux are presented.
Excluded‐volume effects in dilute polymer solutions. IV. Polyisobutylene
Authors: Matsumoto T. , Nishioka N. , Fujita H.
Published: April 2003

Statistical radii of gyration, second virial coefficients, and intrinsic viscosities of sharp fractions (M̄w/M̄n ≈ 1.1) of polyisobutylene (PIB) covering a wide range of molecular weight (1.6 × 105 to 4.7 × 106) were determined in isoamyl isovalerate (IAIV) at a number of temperatures ranging from 20 to 60°C, in n‐heptane at 25°C, and in cyclohexane at 25°C by light‐scattering and viscosity measurements. It was found that IAIV at 22.1°C is a theta solvent for PIB. Analysis of the data by the methods described in preceding papers of this series indicated that, except for minor differences, the conclusions derived from similar studies with polychloroprene, polystyrene, and poly‐p‐methylstyrene hold equally for solutions of the typical linear polymer investigated here. In particular, no decisive evidence for the drainage effect was found.
Computerized measurement of viscoelastic properties of macromolecular solutions: Frequency dependence over and extended range of solvent viscosity
Authors: Massa Dennis J. , Schrag John L.
Published: April 2003

The modified Birnboim transducer and a computerized data acquisition and processing system (DAPS) for the measurement of viscoelastic properties of macromolecular solutions are described. The apparatus has a continuous frequency range from 0.01 to ca. 700 Hz and a viscosity range from 2 to ca. 30,000 poise (sample volume 1 to 1.5 cm2). Sample temperature is controlled to within 0.002°C from −30°C to +80°C. Working displacements are 102 to 104 Å. The DAPS is designed for precise determinations of the magnitudes and relative phasing of two sinusoidally time‐varying electrical signals (0.02%, 0.02°, respectively, for signals > 2 V peak) from 10−2 to 105 Hz. Cross‐correlation techniques are used for noise rejection. For frequencies below 30 Hz values of the storage (G') and loss (G″) components of the complex shear modulus (G*) of 1 dyne/cm2 are determined to within 10% and 4%, respectively, for liquids of moderately low viscosity. Proportionately higher measurement accuracies for typical values of G' and G″ and the wide frequency and viscosity ranges permit extrapolation to infinite dilution and studies of limited molecular flexibility for many polymer—solvent systems.
Kinetics of the dissociation of nonionic detergent micelles by a temperature‐jump technique
Authors: Lang Jacques , Eyring Edward M.
Published: April 2003

The rate of dissociation of a nonionic detergent, octylphenyl polyoxyethylene ether, was studied by a temperature‐jump technique. A relaxation process which is concentration‐dependent was observed. A linear relation between the reciprocal relaxation time and the detergent concentration above the critical micelle concentration was obtained, from which the rate constant of dissociation kn,n–1 of one molecule of detergent from the micelle has been determined. Values of kn,n–1 equal to 0.4 ± 0.05 and 73 ± 5 sec−1 at 24.8°C were obtained for detergents with 16 and 30 ethylene oxide units per molecule of surfactant, respectively, showing and increase of the rate constant of dissociation with the length of the hydrophilic‐head chain.
Ultimate tensile properties of elastomers. VII. Effect of crosslink density on time–temperature dependence
Authors: Smith Thor L. , Chu W. H.
Published: April 2003

Data on tensile strength and elongation at break for a series of Viton A‐HV vulcanizates are discussed. The data were obtained at various extension rates at temperatures from −5 to 230°C (25 ≲ T — Tg ≲ 260°C) on seven vulcanizates having crosslink densities ve (estimated from C1 in the Mooney‐Rivlin equation) from 0.46 × 10−5 to 24.4 × 10−5 mole/cm3. At an extension rate of 1 min−1, an increase in ve affects the tensile strength σb (based on the undeformed cross‐sectional area) and the true tensile strength σbσb (based on the cross‐sectional area of a deformed specimen) as follows: σb is essentially constant at a low temperature; it passes through a decided maximum at intermediate temperatures; and it increases to a plateau at elevated temperatures. In contrast, λbσb decreases markedly at all temperatures, an exception being the most lightly crosslinked vulcanizate(s). Application of time—temperature superposition to the ultimate‐property data gave log aT; its temperature dependence is that typical of nonpolar rubbery polymers. Data on the vulcanizates were compared in corresponding temperature states by plotting log 273σb/T, log 273λbσb/T, and (λb — 1)/(λb — 1)max against logtb/(tb)max, where tb is the temperature‐reduced time to break and (tb)max is the value at which the ultimate extension ratio λb attains its maximum, (λb)max. Except for the most lightly crosslink vulcanizate, the comparison shows that 273λbσb/T and (λb — 1)/(λb — 1)max are substantially independent of (or only weakly dependent on) crosslink density, that 273λb/T increases with ve, and that 273λb/T ∝︁ ve0.6 and λb ∝︁ ve−0.4 at a large value of tb/(tb)max.
Incompatibility of blocks in an isolated molecule of A‐B block copolymer
Authors: Pouchlý J. , Živný A. , Sikora A.
Published: April 2003

The problem of the segregation of subchains in an isolated molecule of an A‐B block copolymer is closely related to that of the mutually excluded volume of two chemically differing macromolecules. Therefore, by resorting to the “segment cloud” model used by Flory and Krigbaum to calculate the excluded volume, it was possible to derive an expression for the number of contacts between the two blocks in the same molecule. From the results of the calculation it follows that only partial block segregation can be expected unless the condensation of one of the subcoils to a dense globule occurs, owing to the effect of a poor solvent quality.
A semi‐empirical approach to the viscosities of polyelectrolyte solutions
Authors: Yuan L. , Dougherty T. J. , Stivala S. S.
Published: April 2003

The concentration dependence of the reduced viscosity of a number of polyelectrolytes was found to be adequately described by the equation

as long as the concentration is not too low. The parameter [η]∞ represents the intrinsic viscosity of the well‐shielded polyion and corresponds to values of [η] determined in salt solutions and may possibly correspond to the theory of Harris and Rice on polyion expansion. Heuristic arguments based in part on the work of Katchalsky et al. lead to a definite expression for the parameter k in terms of molecular properties. This result shows that the above equation is valid only for strong polyelectrolytes with constant activity coefficients of counterion. The calculated values of k agree well with experiment except when specific intramolecular interactions (e.g., internal hydrogen bonding) occur. For highly charged polyions we find, surprisingly, that k depends only on the properties of the polymer backbone and not on electrical properties.
Effect of pressure on gas permeability coefficients. A new application of “free volume” theory
Authors: Stern S. A. , Fang S.‐M. , Frisch H. L.
Published: April 2003

The present work is a continuation of a general study of the effect of pressure on gas and vapor permeation through nonporous polymeric membranes. Permeability coefficients have been measured for 1,1‐difluoroethylene (C2H2F2) and fluoroform (CHF3) in polyethylene at penetrant pressures up to 35 atm and at temperatures between ‐18 and 70°C. The permeability coefficient P̄ for the 1,1‐difluoroethylene—polyethylene system was found to increase with increasing pressure differential Δp across the membrane. Isothermal plots of log ΔP versus Δp are generally linear and can be represented by empirical relations of the form ΔP = P(0)exp{m Δp}, where P(0) and m are constants. The slope m of these isotherms decreases with increasing temperature. Plots of log P̄ versus Δp for the fluoroform—polyethylene system are also linear, but exhibit negative slopes, i.e., P̄ decreases with increasing Δp. An extension of Fujita's “free volume” theory of diffusion in polymers shows that the dependence of P̄ on pressure reflects how the free volume of the polymer is affected by this pressure. An increase in the penetrant pressure may result in two opposing effects: (a) the concentration of the penetrant dissolved in the membrane is increased, thereby increasing the free volume, and (b) the hydrostatic pressure on the membrane is also increased, which causes a decrease in the free volume. If the overall effect is an increase in the free volume of the polymer, then P̄ will also increase, and vice versa.
Crystallization of short aliphatic polymer chains. I. General chain‐folding behavior
Authors: Keller A. , Udagawa Y.
Published: April 2003

Short aliphatic polymer chains of different lengths were prepared by degrading polyethylene samples of appropriately chosen initial fold lengths to the chain lengths which correspond to a single chain traverse through the lamella. The resulting dicarboxylic acids were either used as such for further crystallization experiments or were first converted into diiodides to remove polar endgroups. The resulting short polymers all crystallized by chain folding even if the chains (peak of distribution) were only 1.5–4 times the length of a traverse through the lamella. In the diiodides the fold length varied continuously with crystallization temperature, as is usual in high molecular weight material, but with the dicarboxylic acids such variation, while observable, was only small. The effect of the molecular weight on the fold length due to its influence on supercooling at a given crystallization temperature has become apparent. Renewed degradation with nitric acid and subsequent GPC analysis of the degradation products confirmed the folded nature of the chains in the above crystals. This analysis combined with experiments on the reactivity of chain ends has led to the picture that each chain folds completely, once, twice etc. so that both folds and ends are in the surface zone but are located at varying heights, as appropriate to the overall layer thickness for the molecular weight distribution in question. This picture is consistent with other concurrent work.
Effect of iodine on small‐angle X‐ray diffraction from drawn poly(ethylene terephthalate) film
Authors: Sakai Toyoko , Miyasaka Keizo , Ishikawa Kinzo
Published: April 2003

The effect of iodine sorption on the small‐angle x‐ray diffraction intensity is discussed in terms of the distribution of iodine sorbed in the amorphous regions of polymers. The change in the intensity of the peak corresponding to long periods is measured as a function of the iodine uptake in drawn, and annealed poly(ethylene terephthalate) films. A linear relation with slope K is observed between the square root of relative intensity and iodine uptake. The slope K varies with annealing conditions. Theoretical values calculated for models of the distribution of iodine in amorphous regions, are compared with the observed K. Results can be interpreted on the basis of a “concave” distribution of iodine, i.e., with sorption sites more numerous near a crystal surface than in the interior of an amorphous region.
Effect of aging on flow birefringence of poly(vinyl alcohol) and methyl cellulose solutions
Authors: Fujishige Shoei
Published: April 2003

Flow birefringence experiments on aqueous solutions of poly(vinyl alcohol) and of methyl cellulose show that the optical anisotropy changes markedly during aging of the solution. The same effect can be obtained by adding alcohol to fresh aqueous methyl cellulose solutions. The flow birefringence was measured as a function of the velocity gradient on solutions with and without alcohol during the course of aging. The phenomena are attributed to intermolecular and intramolecular interactions between exposed hydroxyl groups of the polymer chains, as these are affected by a change in the degree of hydration during aging or by the addition of a strong hydrophilic agent such as an alcohol. Association or crystallization of the ordered polymer chains may occur and lead to a supermolecular structure in the solutions. By following Sadron's theory and making use of a polar diagram, it was concluded that, after aging or mixing with the additive, the solutions become optically heterogeneous and contain two different components with optical polarizabilities of the same [in poly (vinyl alcohol) solutions] or opposite (in methyl cellulose solutions) sign.
Poly(2,6‐diphenyl‐1,4‐phenyl oxide): Characterization by gel‐permeation chromatography, light scattering, and solution viscosity
Authors: Shultz A. R. , Bridgman A. L. , Hadsell E. M. , McCullough C. R.
Published: April 2003

Ten unfractionated poly(2,6‐diphenyl‐1,4‐phenylene oxide) samples were examined by gel permeation chromatography (GPC) and intrinsic viscosity [η] at 50°C in benzene, by intrinsic viscosity at 25°C in chloroform, and by light scattering at 30°C in chloroform. The GPC column was calibrated with ten narrow‐distribution polystyrenes and styrene monomer to yield a “universal” relation of log ([η]M) versus elution volume. GPC‐average molecular weights, defined as M̄gpc = \documentclass{article}\pagestyle{empty}\begin{document}$\Sigma w_i [\eta ]_i M_i /\Sigma w_i [\eta ]_i$\end{document}, wi denoting the weight fraction of polymer of molecular weight Mi, were computed from the GPC and [η] data on the polyethers. The M̄GPC were then compared with the weight‐average M̄w from light scattering. The intrinsic viscosity (dl/g) versus molecular weight relations for the unfractionated poly(2,6‐diphenyl‐1,4‐phenylene oxides) determined over the molecular weight range 14,000 ≤ M̄w ≤ 1,145,000 are log [η] = −3.494 + 0.609 log M̄w (chloroform, 25°C) and log [η] = −3.705 + 0.638 log M̄w (benzene, 50°C). The M̄w(GPC)/M̄n(GPC) ratios for the polymers in the molecular weight range 14,000 ≤ M̄w ≤ 123,000 approximate 1.5 according to computer integrations of the GPC curves with the use of the “universal” calibration and the measured log [η] versus log M̄w relation. The higher molecular weight polymers (326,000 ≤ M̄w ≤ 1,145,000) show slightly broadened distributions.
Permeation of dimethyl sulfoxide through polyethylene membraness
Authors: Stern S. A. , Britton G. W.
Published: April 2003

Permeability and diffusion coefficients for dimethyl sulfoxide (DMSO) in polyethylene have been measured by the “time‐lag” technique and found to be affected by the adsorption of DMSO vapor in the low‐pressure side of the apparatus. An analytical method is described for correcting the apparent permeability coefficients for such adsorption effects. “True” permeability coefficients for DMSO in polyethylene, expressed in units of cm3(STP) – cm/(sec‐cm2‐cmHg), vary from 0.92 X 10‐7 at 30°C to 1.7 X 10‐7 at 45°C, and their dependence on relative DMSO pressure appears to be small. The energy of activation for the permeation process is 7.1 kcal/mole. The described correction method is also applicable to the permeation of water vapor through polyethylene and poly‐(phenylene oxide). The apparent diffusion coefficients could not be corrected by this method. The solubility of DMSO in polyethylene was measured with a Bakr‐McBain balance and found to be very small; solubility coefficients are less than 0.8 cm3(STP) DMSO/(cm3 polymer‐cmHg). It is concluded that the transport and solution behavior of DMSO in polyethylene is more similar to that of water vapor than to the corresponding behavior of organic vapors.
Crystallization and melting of poly(2,6‐dimethyl‐1,4‐phenylene oxide) in ternary mixtures with toluene and polystyrene
Authors: Shultz A. R. , McCullough C. R.
Published: April 2003

The crystallization and melting temperatures of an unfractionated poly(2,6‐dimethyl 1,4‐phenylene oxide) (PPO) sample, PM2, were determined at 0.25°C/min cooling and heating rates in five binary toluene—PM2 and fifteen ternary toluene—polystyrene—PM2 solutions. The total polymer weight fraction range studied was 0.12–0.40 and the PM2 weight fraction range was 0.026–0.40. The heat of fusion Hf of the PM2 was computed to be 10.1 cal/g from the melting point depressions. A toluene—PM2 pair interaction parameter χ13 = 0.890 – 223.5/T was found. Although a reliable polystyrene–PM2 interaction parameter could not be computed, the data are consistent with χ23 = 0. Setting χ23 = 0 we calculate the toluene—polystyrene interaction parameter to be χ12 = 0.495 – 15.46/T. This χ12 is in remarkable agreement with values reported in osmotic pressure studies.
Laser‐raman study of crystallinity changes in poly(ethylene terephthalate)
Authors: Melveger A. J.
Published: April 2003

The bandwidth at one‐half maximum intensity of the Raman‐active CO stretching vibration was found to correlate with density in poly(ethylene terephthalate). This correlation is valid for unoriented as well as highly oriented materials. It is suggested that a number of rotational states of the terephthalate segment occur in the amorphous polymer. Crystallization causes a resonance‐stabilized planar conformation.
Relation between the refractive index increment and the density increment of binary mixtures: Application to the determination of partial specific volumes of polymers in solution
Authors: Scholte Th. G.
Published: April 2003

Starting from the Lorentz‐Lorenz equation, Heller, a few years ago, advanced a method for calculating the partial specific volume of a substance in a dilute solution from the refractive index increment of the solution and the specific refraction of the solute. It is shown that this method, based on graphical extrapolation, can be considerably simplified. Further, a method is indicated by which the partial specific volume of a substance over the whole range of concentrations can be calculated in an analogous manner. The method is checked and elucidated with reference to some experimental examples.
Molecular fracture in natural rubber during tensile testing at low temperatures
Authors: Natarajan R. , Reed P. E.
Published: April 2003

Sulfur‐cured natural rubber and other elastomers subjected to tensile tests at low temperatures and low strain rates are found to swell and “foam” after testing when brought to room temperature. The conditions under which this phenomenon can occur are established and related to load‐extension curves. Free radicals formed during tensile testing are studied by electron spin resonance (ESR) techniques. It is found that the free radicals observed at the low temperatures are stable below the glass transition temperature of the material, and it is suggested that these radicals arise from mainchain fracture occurring during yielding of the material. The subsequent swelling at higher temperatures is found to be due to the expansion of environmental gases absorbed during tensile testing and to the release of hydrogen in certain cases from the materials tested. It is also suggested that yielding of the material which gives rise to these characteristics occurs by crazing of the material; the voids in the craze bands absorbing the environmental gases which subsequently cause the foaming at higher temperatures.
Empirical probability‐density functions for the radii of gyration of linear random‐flight chains
Authors: Hoffman Robert F. , Forsman W. C.
Published: April 2003

A number of empirical equations are presented that are good approximations to computed probability density functions of the one, two and three‐dimentional radii of gyration of linear random‐flight chains. Equations are given that are in good agreement with the distributions over the range of the radii of most physical interest. Alternative equations are presented that give especially good fit for small values of the one and two‐di‐mensional radii.