bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of tacticity in poly(vinyl chloride) by infrared spectroscopy
Authors: Štokr J. , Schneider B. , Kolínský M. , Ryska M. , Lím D.
Published: April 2003

From the temperature dependence of infrared spectra of poly(vinyl chloride) samples prepared by different methods, the intensity of the band at 690 cm.1 (proportional to the number of isotactic diads in the sample), as well as that of the tacticity‐independent CH stretching band, was found to be independent of the crystallinity of the sample. These lines were therefore applied for the tacticity determination in poly(vinyl chloride), measured in the form of KBr pellets. The numerical tacticity value was obtained from the known values of absorbance coefficients of SCH and SHH type CCl stretching bands in solution, and from the shape of the spectrum.
Quantitative determination of short branches in high‐pressure polyethylene by gamma radiolysis
Authors: Kamath Pandurang M. , Barlow Anthony
Published: April 2003

A careful study of the radiolysis products of a series of ethylene α‐olefin copolymers and ethylene homopolymers has shown that if a correction is applied, to take into account the fragments arising from scission at chain ends, the remaining products can be quantitatively accounted for as entirely due to scission of side branches introduced onto the backbone chain by the α‐olefin comonomer. The cleavage of branches takes place, for all practical purposes, exclusively at the branch points at which the branches are attached to the backbone chain. The same data together with similar radiolysis data of poly(3‐methyl pentene‐1) and poly(4‐methyl pentene‐1) have further shown that all branches cleave with equal efficiency, regardless of their length. Radiolysis does, therefore, provide a reliable and convenient tool for the quantitative characterization of high‐pressure polyethylene with regard to the unique short‐chain branching distribution that is characteristic of each.
Radical‐initiated copolymerization of carbon monoxide and ethylenimine in the presence of ethylene
Authors: Kagiya Tsutomu , Ichida Taizo , Narisawa Shizuo , Fukui Kenichi
Published: April 2003

The radical‐initiated copolymerization of carbon monoxide and ethylenimine in the presence of ethylene was studied quantitatively. Carbon monoxide copolymerized with difficulty with ethylenimine with α,α′‐azobisisobutyronitrile as radical initiator. In the presence of a small amount of ethylene, however, a remarkable amount of crystalline powdery poly‐β‐alanine (nylon 3) was obtained. The crystalline copolymer, which mainly consists of nylon 3 and contains a small amount of nylon 5 and other substances of higher homologous nylon structure, was obtained in the presence of a large amount of ethylene. This copolymer scarcely contained any ketone structure. Increasing the total feed of the equimolar mixture of the monomers increased the conversion of total monomer and nylon 3 content in the copolymer formed. The effect of increasing carbon monoxide content in this system was to increase both the conversion and the nylon 3 content in the copolymer. In both cases the copolymers were almost identical with nylon 3. Increased ethylene content in the monomer feed, however, increased the conversion and the content of higher homologous nylon structures, such as nylon 5 and 7. From the results it was concluded that ethylene was involved not only in the propagation reaction but also particularly in the initiation reaction.
The determination of randomness in copolyesters by high resolution nuclear magnetic resonance
Authors: Yamadera Reizo , Murano Masao
Published: April 2003

High‐resolution nuclear magnetic resonance (NMR) spectra of several kinds of polyesters were measured. Proton signals due to heterolinkages could be observed in some copolyesters, and the average sequence length and the degree of randomness in the copolyester were calculated from the intensities of their signals. A process in the transesterification reaction between two kinds of homopolyester was pursued with the NMR spectra. Random copolyester is formed by the ordinary molten‐state copolycondensation and also during the transesterification reaction between two kinds of homopolyester.
Dehydrochlorination reactions in polymers. Part II. Chlorinated polystyrene
Authors: Haldon R. A. , Hay J. N.
Published: April 2003

The dehydrochlorination of chlorinated polystyrene was studied in the temperature range 120–220°C., when HCl was the sole volatile product. The dehydrochlorination was accompanied by the slow development of color and chain scission. The elimination rate fell too rapidly with reaction extent to be accounted for by reduction of reagent. Solution studies in o‐dichlorobenzene indicated that the reaction was initially first‐order in polymer concentration but was retarded by the polyene reaction products. The overall elimination was interpreted as a radical process in which the product was an active retarder. These observations are also valid for the elimination of HBr from brominated polystyrene.
Syntheses of polymerizable dyes and their graft copolymerization to cellulose and polypropylene fibers
Authors: Uno K. , Iwakura Y. , Makita M. , Ninomiya T.
Published: April 2003

Various methacrylic ester derivatives were synthesized from glycidyl methacrylate and aromatic amines or phenol. The homopolymerization and graft copolymerization of these compounds were carried out using azobisisobutyronitrile. These methacrylic derivatives reacted with diazonium salts to give azo compounds which have a double bond. These vinyl azo compounds gave homopolymer and graft copolymer with cellulose or polypropylene fibers.
Photochemistry of poly(tert‐butyl acrylate). Effect of ester spatial conformation on the cycloelimination process
Authors: Monahan Alan R.
Published: April 2003

A preferred geometric isomer was found to exist for the Norrish type II photocycloelimination of isobutene from poly(tert–butyl acrylate). A detailed analysis of infrared spectroscopic and kinetic data under thin film conditions is consistent with the mechanism:
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i.e., a photoinduced rotational equilibrium is established between the cis and trans ester spatial conformations, with isobutene elimination occurring from the cis form. In the glassy state of the polymer, an activation energy of 3.0 kcal./mole was obtained for the elimination step. Energy transfer experiments with naphthalene, benzophenone, and oxygen resulted in a significant decrease in the isobutene yield. This indicates that reaction occurs at least in part from a triplet state of the carbonyl group in the polymer.
Preparation of fluorine‐containing polyethers
Authors: Trischler Floyd D. , Hollander Jerome
Published: April 2003

Polyethers were prepared from 3,3,3‐trifluoro‐1,2‐epoxypropane by using both cationic and anionic initiators. Aluminum chloride and boron trifluoride were the two cationic initiators investigated. The polymer obtained with the use of aluminum chloride contained no functional endgroups other than hydroxyl, while the polymer prepared with boron trifluoride contained some terminal unsaturation. Potassium hydroxide and the monosodium salt of hexafluoropentanediol were investigated as anionic initiators. The polymer obtained by using potassium hydroxide also contained terminal unsaturation, while the polymer prepared with the monosodium salt of hexafluoropentanediol was terminated with primary hydroxyl groups capable of being used in polyurethanes. All polymers had molecular weights in the range from 970 to 4300. A fluorine‐containing polyformal was prepared in high yield by the reaction of hexafluoropentanediol with trioxane. The same polymer was obtained in poor yield by the reaction of hexafluoropentanediol with dibutyl formal. Ring‐opening polymerizations were attempted on two fluorinated cyclic ethers, 2,2,3,3,4,4‐hexafluoropentamethylene oxide and 3,3,4,4‐tetrafluorotetramethylene oxide. There was no reaction with anionic initiators. With most of the cationic initiators, there was no reaction. Boron trifluoride and phosphorus pentafluoride formed complexes with the ether, but would not cause ring opening.
Poly(aryl ethers) by nucleophilic aromatic substitution. I. Synthesis and properties
Authors: Johnson R. N. , Farnham A. G. , Clendinning R. A. , Hale W. F. , Merriam C. N.
Published: April 2003

A series of new aromatic polyethers have been prepared by solution condensation polymerization. The synthesis involves the condensation of a dialkali metal salt of a dihydric phenol with an “activated” or negatively substituted aromatic dihalide in an anhydrous dipolar aprotic solvent at elevated temperatures. The reaction is rapid, free of side reactions, and yields polymers of excellent color. Bakelite polysulfone can be prepared in this manner by reaction of the disodium salt of bisphenol A with 4,4′‐dichlorodiphenyl sulfone in dimethyl sulfoxide (DMSO). Only dipolar aprotic solvents are useful for conducting the polymerization. Of these, DMSO and Sulfolane (tetrahydrothiophene 1,1‐dioxide) are the most effective. Water or other competing nucleophiles must be absent if high molecular weight is to be obtained. Besides providing the necessary solubility, this highly polar solvent is believed to be essential in providing the rapid polymerization rates observed. The rates are further found to depend on the basicity of the bisphenol salt and upon the electron‐withdrawing power of the activating group in the dihalide. As is usual for this type of reaction, the difluorides are found to be more reactive than the corresponding dichlorides. Most of the polyethers are amorphous, rigid, tough thermoplastics with high second‐order transitions (Tg). Thermal stability and electrical properties are noteworthy. These and other properties are described for polysulfone, and glass transitions are given for a selected list of the other polyethers.
Poly(aryl ethers) by nucleophilic aromatic substitution. III. Hydrolytic side reactions
Authors: Johnson R. N. , Farnham A. G.
Published: April 2003

The molecular weight of polysulfone, i.e., the aryl polyether that is prepared by the reaction of the disodium salt of bisphenol A with 4,4′‐dichlorodiphenyl sulfone in dimethyl sulfoxide (DMSO) solvent is shown to depend, among other things, on the moisture content of the polymerizing system. In the presence of water, hydrolysis of the sulfone monomer occurs concomitant with the polymerization. This leads to a deviation from the desired 1:1 ratio of coreactant groupings and therefore in attendant reduction in possible molecular weight. The hydrolysis is shown to lead to the formation of the sodium salt of 4‐chloro‐4′‐hydroxydiphenyl sulfone and to a lesser extent polymer derived from self‐condensation of this salt. At low levels this salt is essentially inert towards the principal polymerization at hand but in somewhat greater amounts functions as an effective chain terminator. Similar hydrolysis of polysulfone chloro endgroups is believed to occur under the aqueous conditions of polymerization but to a lesser extent than for the sulfone monomer. It is shown that polysulfone or similar polyethers are subject to chain cleavage by bases in DMSO solvent. The base attacks the activated position para to the sulfonyl group with the formation of a chain terminating in a bisphenol A type phenolic group and a chain terminating in a phenolic group of the bisphenol S (p‐hydroxyphenyl sulfonyl) type. It is shown that cleavage is probably not important under normal conditions of polymer formation. The effect of these hydrolytic side reactions on the attainment of high molecular weight under conditions of imperfect reaction stoichiometry is shown to be consistent with the above conclusions.
Syntheses of optically active polymers by condensation polymerization of d‐tartaric acid with some diamines
Authors: Minoura Yuji , Urayama Shigeru , Noda Yuzuru
Published: April 2003

In order to synthesize optically active polymers which have asymmetric carbon atoms in the polymer main chain, polyamides were synthesized at high temperatures by the condensation of the salt prepared from d‐tartaric acid with diamines, such as hexamethylenediamine, o‐, m‐, and p‐phenylenediamine. Effects of the solvent, polymerization time, intrinsic viscosity, and pH on the degree of the specific rotation of polyhexamethylene‐d‐tartaramide, were investigated. From the results of hydrolyses of the polymers, it was found that d‐tartaric acid is not racemized during condensation polymerization.
Anionic graft polymerization of methyl acrylate to protein functional groups
Authors: Krull L. H. , Friedman Mendel
Published: April 2003

Graft polymerization of methyl acrylate to functional groups in proteins was studied with model compounds and with whole gluten proteins. Polymerization was carried out in the presence of sodium hydride or sodium in dimethyl sulfoxide. Initiation proceeds by an anionic mechanism, and the rate‐determining step is the production of the initially formed carbanion. The rate of disappearance of methyl acrylate was followed via gas chromatography. Amino acid analyses indicated that the functional groups of the amino acids, as well as the peptide bonds, were acting as the initiation sites in proteins. Reaction rates of the functional groups were determined on model compounds in the presence of sodium and sodium hydride. With both the model compounds and the proteins, polymerization was initially rapid and then leveled off, although rates depended on the concentration of activator and acrylate. Methoxyl group analyses of modified model compounds and proteins indicated that from 5 to 10 methyl acrylate residues were introduced per reactive site.
Effect of chemical reagents on the fine structure of cellulose. Part IV. Action of caustic soda on the fine structure of cotton and ramie
Authors: Warwicker J. O.
Published: April 2003

An x‐ray study has been made of the changes in lateral order that take place on the treatment of cotton and ramie with different concentrations of caustic soda at 0 and 20°C. When mercerization conditions are reached it is found that there is an increase in lateral disorder in the fibrils. The x‐ray diagrams from samples treated in the higher concentrations of caustic soda reveal a residual diffraction effect that can be interpreted in terms of a special type of cellulose sheet. This result implies one extreme of lateral disorder that is present in the fine structure of these materials. Indication is given how these lateral disorder phenomena can affect reactivity.
Post‐lactonization of vinyl polymers containing pendent ester and hydroxymethyl groups
Authors: Powell John A. , Whang Jong J. , Owens Frederick H. , Graham Roger K.
Published: April 2003

Copolymers of methyl methacrylate with methyl and ethyl α‐hydroxymethylacrylate and with α‐hydroxymethylstyrene have been prepared with free‐radical initiators at temperatures below 80°C. At higher reaction temperatures or under extrusion conditions, alcohol was eliminated and the free hydroxyl content was greatly decreased. All evidence indicates the formation of six‐membered lactone groups in this post‐polymerization reaction: direct evidence for their formation is lacking, however, since neither infrared nor nuclear magnetic resonance spectra could be used to detect lactonization in this system. The loss of activity from 14C ester‐labeled methyl methacrylate copolymer on heating could be correlated with the extent of lactonization. The degree of lactonization is relatively less with copolymers containing higher amounts of hydroxymethyl groups. The resulting polymers exhibit higher heat distortion temperatures and decreased impact resistance when compared to poly(methyl methacrylate). Attempts were made to incorporate similar lactone structures by cyclocopolymerization with methyl methacrylate of α‐methacryloxymethylstyrene or ethyl α‐methacryloxymethylacrylate, but only crosslinked polymers or polymers with pendent unsaturation were found.
Emulsion polymerization of vinyl stearate
Authors: Moore D. E.
Published: April 2003

The polymerization of vinyl stearate in aqueous emulsions with a non‐ionic emulsifying agent and potassium peroxydisulfate as initiator has been investigated by use of a dilatometric method to follow the reaction. In general, the reaction kinetics do not follow the pattern established for styrene. Variation of initiator concentration produced latices containing approximately equal numbers of latex particles, even though the rate of reaction was almost directly proportional to the peroxydisulfate concentration. For a given initiator and monomer concentration polymerization occurs very slowly when the monomer is completely solubilized but as the number of micelles is reduced and the number of emulsion droplets increased, the rate increases to an optimum value, whereafter it decreases. A mechanism is proposed by which the sparsely soluble vinyl stearate reacts and redistributes itself into latex particles of a different size range from the micelles and emulsion droplets originally present.
Polymerization initiated by an electron donor–acceptor complex. Part I. Polymerization of methyl methacrylate initiated by liquid sulfur dioxide–pyridine complex in the presence of carbon tetrachloride
Authors: Matsuda Minoru , Hirayama Takeshi
Published: April 2003

The polymerization of methyl methacrylate can be initiated by a charge‐transfer complex of liquid sulfur dioxide and pyridine in the presence of carbon tetrachloride. The molar ratio of sulfur dioxide and pyridine which participated in the complex was found from a spectrophotometric study to be 2:1. The polymerization proceeds through free‐radical intermediates. The overall rate of polymerization is proportional to the square root of the concentration of the complex, and the values of kp/kt1/2 under the various polymerization conditions were satisfactorily consistent with the literature value. For the activation energy of the overall reaction, 8.2 kcal./mole was obtained, and for initiation, 9.7 kcal./mole was evaluated from the values of kp/kt1/2. It was deduced from a kinetic mechanism for the initiation that a primary radical may be produced from the reduction of carbon tetrachloride by an associated complex consisting of liquid sulfur dioxide–pyridine complex and the monomer.
Anionic copolymerization of styrene and isoprene in cyclohexane
Authors: Worsfold D. J.
Published: April 2003

The copolymerization of isoprene with styrene initiated with sec‐butyllithium in cyclohexane solution has been studied by kinetic methods. The rates of the homopolymerization have been measured by normal methods. The rates of the cross‐propagation reactions were measured by the rate of appearance or disappearance of the ultraviolet absorption of polystyryllithium when the individual chain ends were reacted with the opposite monomer in the absence of the first. The rates of some of the reactions were also measured in the presence of the other monomer. It was found that polyisoprenyllithium reacted with both monomers with a one quarter‐order dependence, and the polystyryllithium with a one half‐order dependence. It was found possible to describe the copolymerization in terms of the four individual rate constants and to predict the initial copolymer composition. It was not found necessary to resort to explanations based on preferential absorption of isoprene around the chain ends to explain the high isoprene content of the copolymer.
Influence of SeOCl2 on the polymerization of propylene by TiCl3–Al(C2H5)3
Authors: Soga Kazuo , Takano Yoshiji , Go Shigeo , Keii Tominaga
Published: April 2003

The influence of SeOCl2 on the polymerization of propylene by TiCl3–Al(C2H5)3, and the temperature dependence of the stereospecificity of the catalyst, TiCl3–Al(C2H5)3, have been investigated. SeOCl2 decreases the rate of polymerization and increase the stereospecificity of the catalyst, which could be explained on the basis of a decrease of the concentration of Al(C2H5)3 accompanied by a reaction between Al(C2H5)3 and SeOCl2. On the other hand, the stereospecificity of the catalyst, TiCl3–Al(C2H5)3, increases gradually with a decrease in polymerization temperature from 40 to 0°C. From these results, we conclude that SeOCl2 exerts no essential influence on the polymerization of propylene by TiCl3–Al(C2H5)3, and that the stereospecificity of the catalyst is attributed mainly to the reducing ability of the organometallic compound.
Synthesis of poly‐3,3‐bis(chloromethyl)‐oxacyclobutane (penton) derivatives
Authors: Minoura Yuji , Shiina Kyo , Yoshikawa Keizo
Published: April 2003

The derivatives of poly‐3,3‐bis(chloromethyl)oxacyclobutane were prepared by the reaction of the chloromethyl group with organic alkali salts at 100–130°C. in dimethyl sulfoxide. Various reagents were used, including sodium cyanide, sodium acetate, sodium thiophenolate, sodium phenolate, sodium methoxide, sodium diethyl malonate, and potassium phthalimide. For all the substitution reactions, the infrared spectra and elementary analyses substantiated the structures of the designated products. The intrinsic viscosities of the derivatives decreased with increasing the reaction time. It was found that the ions of these salts are strong nucleophiles in dimethyl sulfoxide.
Polymerization of vinylbenzamides
Authors: Negishi Sutemi , Tamura Yorikazu
Published: April 2003

In the base‐catalyzed polymerization of p‐vinylbenzamide, hydrogen‐transfer polymerization occurs. The structure of the new polymer was identified. Various effects on the hydrogen‐transfer polymerization of p‐vinylbenzamide were studied. The infrared spectrum of the oligomer has characteristic absorptions of secondary amide, as well as weak absorption of the vinyl group. The oligomer also gives a hydrogen‐migrated polymer with anionic catalysts. From these facts a possible polymerization mechanism was proposed. The hydrogen‐transfer polymerization occurred most readily with the p‐vinylbenzamide, next and to a small extent with the meta‐substituted isomer, and hardly with the o‐substituted isomer. o‐Vinylbenzamide gives 3,4‐dihydroisocarbostyril.
Polymerization of tetraoxane at low concentration catalyzed by BF3·O(C2H5)2
Authors: Miki T. , Higashimura T. , Okamura S.
Published: April 2003

In the solution polymerization of tetraoxane catalyzed by BF3·O(C2H5)2, trioxane and methanol‐insoluble polymer were produced. However, the amounts of these products depend on the nature of solvent used. A critical concentration of tetraoxane is observed for the formation of methanol‐insoluble polymer; at less than this critical concentration of tetraoxane no methanol‐insoluble polymer is obtained, but trioxane is preferentially produced. This critical concentration of tetraoxane is higher in a more polar solvent, so the amount of methanol‐insoluble polymer produced decreases and the amount of trioxane produced increases with increasing the polarity of solvent used. These results may be explained in terms of a stabilization of the active center leading to formation of trioxane by a solvation with solvent.
Mechanisms of propagation, transfer, and short‐chain branching reactions in the free‐radical polymerization of ethylene
Authors: Machi Sueo , Kise Seiichi , Hagiwara Miyuki , Kagiya Tsutomu
Published: April 2003

The propagation, transfer, and short‐chain branching reactions in the free‐radical polymerization of ethylene were studied at temperatures of 20–80°C. under pressures of 160–400 kg. cm.2 by means of two‐stage polymerization with the use of a specially designed reaction vessel. In the first stage, the polymerization was carried out in the presence of AIBN as the initiator, and in the second stage, the propagation occurred with living radicals in the absence of the initiator. In the second stage the polymer yield is shown to increase with reaction temperature and pressure, and the molecular weight of the polymer reached constant values which were dependent upon the temperature when the contribution of the polymer formed in the first stage was very small. It is shown that in the second stage the rate of propagation, transfer, and short‐chain branching are all proportional to the second power of ethylene fugacity, and that the activation energies of these reactions are 5.7, 23.4, and 10.9 kcal./mole, respectively. The polymer has no terminal vinyl group. The mechanism of these reactions is discussed on the basis of kinetic and energetic results.
Polymerization of alkylene oxides by dialkylzinc–lewis base systems
Authors: Furukawa Junji , Kawabata Nariyoshi , Kato Akira
Published: April 2003

Dialkylzinc–Lewis base systems are found to be active catalysts for the polymerization of alkylene oxides. The diethylzinc–dimethyl sulfoxide system is especially effective in the preparation of high polymers of ethylene oxide and propylene oxide. Diethylzine does not react with dimethyl sulfoxide, but there is strong association between the compounds. The proton magnetic resonance spectrum of a poly(ethylene oxide) prepared by the catalyst system suggests that the n‐butoxyl group is attached to the end of the polymer chain. Polymerization of ethylene oxide seems to be initiated by the ethyl–zinc bond. The active species of the system seems to be diethylzinc coordinated with dimethyl sulfoxide. The efficiency of the catalyst system for the formation of high molecular weight polymer is 10−1−10−2. The other part of the catalyst is responsible for the formation of low polymers.
Persulfate‐initiated polymerization of acrylamide
Authors: Riggs J. P. , Rodriguez F.
Published: April 2003

A dilatometric technique was used to obtain conversion–time data for the polymerization of acrylamide initiated by potassium persulfate in water. The results are summarized by the empirical rate expression, −d[M1]/dt = Rp = k1.25[K2S2O8]0.5[M1]1.25, and k1.25 = 1.70 × 1011 exp {−16,900/RT} 1.0.75/mole−0.75‐min. Persulfate was varied over the range 9.5 × 10−4 to 5.2 × 10×2 mole/l., and initial monomer concentration [M1] was varied from 0.05 to 0.4 mole/l. The temperature range was 30−50°C. Results of analysis of the kinetics and energetics of the polymerization favor a cage‐effect theory rather than a complex‐formation theory to explain the order with respect to monomer.
Studies of micro‐brownian motion of a polymer chain by the fluorescence polarization method. I. Fluorescent conjugates of polyacrylamide
Authors: Nishijima Yasunori , Teramoto Akio , Yamamoto Mashide , Hiratsuka Shozaburo
Published: April 2003

Polyacrylamide having a fluorescent residue at the chain end was prepared by polymerization of acrylamide in the presence of a fluorescent dye. The segmental motion of the chain end in dilute solution was studied by the fluorescence polarization method on the fluorescent polyacrylamide conjugates thus obtained. The linear relation between 1/p and T/η0 held for every sample studied in aqueous media, where p is the degree of polarization of the fluorescence, T is the absolute temperature, and η0 is the viscosity of the medium. The mean relaxation time 〈ρ〉 of the conjugate was evaluated from these data as a function of the molecular weight of the conjugate. The value of 〈ρ〉 increased slightly with molecular weight, varying from 3.3 × 10−9 to 7 × 10−9 sec. The absolute values of 〈ρ〉 and its molecular weight dependence suggest that 〈ρ〉 represents the mean rotational relaxation time for the cooperative motion of about ten monomeric units at the chain end. The effect of the mean extension of polymer chain on the segmental motion was found to be negligible.
Studies of micro‐brownian motion of a polymer chain by the fluorescence polarization method. II. Segmental motions in concentrated polymer solutions
Authors: Teramoto Akio , Hiratsuka Shozaburo , Nishijima Yasunori
Published: April 2003

The fluorescence polarization method has been used to study the micro‐Brownian motion of a terminal segement of a polymer chain in concentrated solutions. A new apparatus for determining the fluorescence intensity and its polarization degree was designed. By using this apparatus, the rotational relaxation time 〈ρ〉 of the terminal segment of the fluorescent conjugates of polyacrylamide in aqueous polyacrylamide solutions was obtained as a function of polymer concentration from 0 to 65%, molecular weight of the conjugate from 3.5 × 104 to 3 × 105, and temperature from 10 to 30°C. The logarithm of 〈ρ〉 increased approximately linearly with increasing polymer concentration. This increase in 〈ρ〉, amounting to a factor of 20 times, was less marked than that in macroscopic viscosity. At concentrations less than 30%, 〈ρ〉 depended appreciably on the molecular weight of the conjugate.
Structural studies of polyethers. IV. Structure analysis of the polyoxymethylene molecule by three‐dimensional fourier syntheses
Authors: Uchida Toshio , Tadokoro Hiroyuki
Published: April 2003

Detailed structure analysis of the polyoxymethylene molecule was carried out by the method of three‐dimensional Fourier synthesis. The diffraction data were measured on a highly ordered polyoxymethylene sample prepared from a single crystal of tetraoxane by solid‐state radiation polymerization. By assuming the anisotropic thermal factors for the oxygen and carbon atoms and taking into account the contribution of the hydrogen atoms, good agreement between the observed and calculated structure factors was obtained; the R factor is 8.8%. The distance between the oxygen atom and the helix axis r(O) = 0.671 A. is slightly shorter than r(C) = 0.691 A. The bond distance CO = 1.421 A., the angle ∠COC = 112°24′, and ∠OCO = 110°49′. All the internal rotation angles of the skeletal bonds are 78°13′. It is deduced from the experimental results that each crystallite of polyoxymethylene is composed of only one type of helix, right‐handed or left‐handed.
On the predictability of the high‐frequency elastic modulus of semicrystalline polymers as function of crystallinity
Authors: Bondi A.
Published: April 2003

The relation of the high‐frequency elastic moduli of semicrystalline polymers to volume fraction crystallinity is correctly described by the Hashin‐Shtrikman theory, without any disposable constants, as a function of the ratio of the modulus of the amorphous to that of the crystalline phase. Hence the (high‐frequency) reduced modulus of semicrystalline polymers is largely a function of the temperature T/Tg. The importance of T/Tm for the modulus of the crystalline phase precludes the existence of a single universal reduced modulus versus temperature curve.
Crystallization of poly(tetramethyl‐p‐silphenylene)‐siloxane (TMPS) polymers. Part II
Authors: Magill J. H.
Published: April 2003

The crystallization kinetics and morphology of poly(tetramethyl‐p‐silphenylene)siloxane spherulites have been investigated over a temperature range of 25–130°C. The effect of molecular weight on the spherulitic growth rates, ranging from the monomer to molecular weights about 106, is discussed in terms of conventional rate theory. Surface free energies of crystal growth are computed on the basis of a spherulitic model in which the polymer chains are presumed to be incorporated within the lamellar crystallites which are comprised in the spherulites. Mention is made of the change in mechanical properties with molecular weight.
Radiation‐induced catalytic polymerization. I. Theory
Authors: Temkin A. Ya.
Published: April 2003

The kinetics of radiation polymerization on a solid catalyst is discussed, under the condition that only linear termination of the chain takes place. All the kinetic equations are balance equations of particles of each type adsorbed by unit mass of the catalyst, and this makes it possible to account for the effect on the kinetics of the time dependence of the magnitude of the part of its surface on which the reactions we are considering may take place. Integro‐differential equations are used for calculating the molecular weight distribution of the resulting polymer; this ensures higher accuracy of the formulas obtained than when differential equations are used and makes it possible to eliminate a number of limitations generally involved in the transition to differential equations. An expression has been found for the molecular weight distribution of the polymer product which allows for the possibility of radiation‐induced catalytic polymerization on the resulting adsorbed polymer. Expressions have been derived for the average molecular weight and yield (weight and molecular) of the polymer formed. Asymptotic formulas have been obtained (for large irradiation times) for all the above values. The conclusions that can be drawn concerning the mechanism of the process based on a comparison of the formulas obtained with kinetic curves plotted from experimental data are given. It is shown how such a comparison can be utilized for calculating the rate constants for polymerization and chain termination reactions.
Wideline NMR studies of polyacrylonitrile
Authors: McMahon P. E.
Published: April 2003

NMR linewidth studies of molecular motion in several polyacrylonitrile samples have been carried out. The motional transition temperature is found in the 105–124°C. range and depends upon polymerization conditions. In addition, the thermal activation energy for the motional process underlying this transition was evaluated at 16.4 kcal./mole. Finally, measurement of the transition temperature for one of the specimens in three different physical states (bulk, spun only, and spun and drawn with a ratio of 3:1), revealed that no change in the transition temperature was effected by either spinning or drawing.
Infrared technique for the measurement of structural changes during the orientation process in polymers
Authors: Koenig J. L. , Cornell S. W. , Witenhafer D. E.
Published: April 2003

Polarized infrared measurements were made on polymer samples to obtain the structural changes occurring during the orientation process. The absorbances of the infrared bands were measured by determining the three components of the absorbance. Two components were obtained directly with plane‐polarized light while the third is obtained by tilting the sample and extrapolating. Corrections were made for machine optics polarization, sample birefringence, polarizer inefficiency, anisotropy of the index of refraction, and scattering from the film surface. Data are reported for polyethylene obtained from cold‐drawn specimens as a function of draw temperature. Polyethylene exhibits no strain‐induced crystallization as a result of the chain‐alignment process. Annealing of the drawn samples reperfects the distorted crystals.
Effect of polydispersity on liquid–liquid phase equilibrium
Authors: Baysal B. M. , Stockmayer W. H.
Published: April 2003

The effect of polydispersity on liquid–liquid phase equilibrium in systems containing polymer, solvent, and nonsolvent is investigated numerically in the Flory‐Huggins approximation for several special cases. The resulting phase diagrams indicate that, except in the immediate vicinity of the critical region, the degree of swelling of a polymer precipitate phase with a given number‐average molecular weight is essentially independent of polydispersity.
Gel permeation chromatography of branched polyethylene
Authors: Salovey R. , Hellman M. Y.
Published: April 2003

The effect of long‐chain branching must be considered in gel permeation chromatography to evaluate the molecular weight polydispersity of branched polyethylenes. Osmotic molecular weights of fractions of branched polyethylene were correlated with elution volumes; weight‐average and number‐average molecular weights of a branched polyethylene were determined. Molecular weight changes on crosslinking polyethylene by ionizing radiation are accompanied by branching and cannot be simply interpreted by gel permeation chromatography.
Transient analysis of a vibrating reed: Error analysis
Authors: Glauz R. D.
Published: April 2003

The error analysis for the transient vibrating reed test is developed based on a linearized approximation. Tables are given for the efficient utilization of the equations in evaluating the accuracy range of test data.
Intrinsic viscosity of polydisperse branched polymers
Authors: Graessley William W. , Mittelhauser Henry M.
Published: April 2003

The relationships between molecular weight distribution and structure in polymerizations with long‐chain branching were reviewed and extended. Results were applied to an experimental examination of intrinsic viscosity in polydisperse, trifunctionally branched systems. Several samples of poly(vinyl acetate) were prepared by bulk polymerization under conditions of very low radical concentration. The relative rate constants for monomer transfer, polymer transfer, and terminal double‐bond polymerization were established from the variation of Mn and Mw with the extent of conversion. Average branching densities were then calculated for each sample and ranged as high as 1.5 branch points/molecule. Intrinsic viscosities [η]B were measured in three systems: a theta‐solvent, a good solvent, and one that was intermediate in solvent interaction. These results were compared with calculated viscosities, [η]L, which would have been observed if all the molecules had been linear. The values of [η]B/[η]L were substantially the same in all three solvents. The variation of this ratio with branching density was compared with the theory of Zimm and Kilb as adapted to polydisperse systems. Discrepancies were noted, and the adequacy of present model distribution functions for branched polymers was questioned.
Experimental anomalies and the conformational theory of polymers
Authors: Majerus John N.
Published: April 2003

The influence of the size and shape of the torsional potential upon the theoretical temperature coefficient (T∂ ln 〈r02〉/∂T) of a polymeric chain was studied. The uncorrelated end‐to‐end distance equations for isotactic, syndiotactic, and completely atactic chains were differentiated with respect to temperature and the integrals in the resulting equations were evaluated by the method of Gaussian quadrature. The calculated coefficients were found to be nonlinear functions of the energy ratio Umax/KT, where Umax is the maximum potential barrier and possess real roots which critically depend upon the size and shape of the potential. Qualitative anomalies between experiment and theory disappeared when the entire torsional potential was used in the conformational theory. It appears that quantitative agreement between theory and experiment can be established for polymeric materials if the entire potential is used, rotations within bulky side groups are included, and the potential is determined by the method of minimum conformational energy.
Gel permeation chromatography: On the shape of the calibration plot and molecular size separability
Authors: Osterhoudt H. W. , Ray L. N.
Published: April 2003

Data obtained from the calibration of GPC columns of different permeabilities with standard polystyrenes are reported. For single columns the logarithm molecular weight–elution volume plot is linear for approximately one and one‐half decades in molecular weight. GPC separations are such that the separability of two samples of similar molecular weight improves as their mean molecular weight decreases. Because of this the analysis of high molecular weight polymers can best be accomplished on a series of columns in which each column has a high permeability limit. The elution volume for columns in series is shown to be the sum of the elution volumes of the individual columns. As higher molecular weights are eluted a pronounced tailing effect is observed.
Some optical and mechanical properties of poly(vinyl chloride)
Authors: Utsuo A. , Stein R. S.
Published: April 2003

The optical and mechanical properties of poly(vinyl chloride) film were examined by observing both the stress and birefringence during stretching at constant rate, during relaxation at constant length and during a dynamic birefringence experiment. Experiments were also done by varying the temperature at constant length. The changes in birefringence are interpreted in terms of changes in negative distortional birefringence, changes in positive orientation birefringence, and possible reversible changes in birefringence with temperature arising from conformational changes in the polymer chain and changes in the contribution of birefringent crystals.
Morphology of polypropylene crystals. II. Twinning of lamellar crystals
Authors: Kojima Morio
Published: April 2003

Twinned crystals were obtained from fractionated isotactic polypropylene of M̄w = 600,000 by isothermal crystallization at 130°C. for 20 hr. from dilute α‐chloronaphthalene solution (0.005 wt.‐%). Electron microscopic observations confirm that the molecular chains of polypropylene lamellar crystals extend along the [100] direction while the folding itself occurs within the (010) planes in the monoclinic crystal form. On this basis it is shown that polypropylene forms twinned crystals in which the composition plane is the (1k0) planes. It can be deduced that the formation of twin nucleus occurs before twinning, and then growth occurs from the neighboring region of the crystal boundary by chain folding along the [100] direction.
Diffusion theory of the post‐irradiation oxidation of polyethylene
Authors: Böhm Georg G. A.
Published: April 2003

The primary reaction of oxygen with irradiated polyethylene has been followed by observing the rapid disappearance of the ultraviolet absorption bands at 258 and 285 mμ, bands attributed to the allyl and dienyl free radicals. A mathematical theory based on diffusion equations has been developed by means of which a quantitative estimate of the total initial free‐radical concentration can be made. From the shape of the free‐radical decay curve it can be concluded that the initial oxygen–free‐radical reactions occur about three times as frequently in the amorphous regions as in the crystalline.
Selective polymeric effects on solvent NMR relaxations
Authors: Liu Kang‐Jen
Published: April 2003

Measurements of the spin‐lattice relaxation times (T1) of solvent protons have been performed on systems containing mixed solvents with and without polymer. It has been found that the motion of solvent is selectively affected by polymers present in the system. Polyisobutylene (10%) in mixed solvents of carbon tetrachloride (or cyclohexane) and dichloromethane at various proportions produces little effect on T1 values of dichloromethane, but it affects significantly the T1 values of cyclohexane; whereas poly(methyl methacrylate) (10%) in carbon tetrachloride and dichloromethane (or acetone) selectively associates with dichloromethane (or acetone), resulting in an approximate 50% reduction of the T1 values for dichloromethane (or acetone). In systems of poly(methyl methacrylate) and three mixed solvents of carbon tetrachloride, dichloromethane, and cyclohexane, the polymer (10%) has a negligible effect on the T1 values of cyclohexane, but brings about a 50% reduction of the T1 values of dichloromethane. These phenomena are discussed in terms of local selective interactions between the solvent molecules and the polymeric chain segments.
Influence of stereoregularity on binding of counterions by poly(methacrylic acid)
Authors: Costantino L. , Crescenzi V. , Quadrifoglio F. , Vitagliano V.
Published: April 2003

The activity coefficient γ, of sodium ion, in aqueous solutions of both isotactic and conventional poly(methacrylic acid) (PMA) has been studies throughout the whole range of degree of neutralization α with a Beckman Na electrode and membrane electrodes. The results show that the fraction of sodium ions bound to isotactic PMA is higher than that bound to conventional (or syndiotactic) PMA over the entire range of α. The binding of divalent counterions (Mg+2, Cu+2, Co+2, and Ni+2) by the two forms of PMA (at α = 0.95) has been evaluated from the release of Na+ ions with the Beckman Na electrode. Turbidimetric determinations of the critical amount of various divalent cation chlorides necessary to bring about precipitation of both isotactic and conventional PMA (at α = 0.95) have also been carried out.
Measurement of concentration gradients in swelling crosslinked polymer beads
Authors: Gurnee Edward F.
Published: April 2003

The concentration of solvent in the gel phase of a swelling polystyrene–divinylbenzene copolymer bead has been measured as a function of the radius by optical interference techniques. It is found that an appreciable gradient exists even shortly after the core disappears. Results are presented for two cases: a very lightly crosslinked bead that exhibits negligible birefringence while swelling, and a more tightly crosslinked network in which the birefringence must be considered. It is also found that the refractive index of the unswollen bead is considerably less than that found by extrapolation from the swollen state; this effect is reasonable when the “free volume” in the bulk polymer is considered.
Network behavior of polyurethane elastomers
Authors: Puett D.
Published: April 2003

The present study is concerned with some network properties of polyurethane elastomers in which stability is acheived via physical crosslinkages such as microcrystallites or secondary bonding. The techniques of isothermal, thermo‐, and photoelasticity have been used to gain better insight into the mechanisms which occur during the deformation of these materials. It was found that stable networks are obtained only after mechanical and thermal conditioning. The well‐known stress lowering which is observed during the second deformation is manifested primarily in the entropy component of the retractive force. This implies that the stress lowering results from a reduction in the number of effective network chains and not from time‐dependent effects or crystallinity changes. Depending upon the chemical structure of the material, both positive and negative energy components of the force have been found.
Investigation of the viscosity of solutions of graft copolymers
Authors: Połowinski S.
Published: April 2003

Living polystyrene was grafted on fractions of poly(methyl methacrylate) by an anionic grafting reaction. Unreacted polystyrene was separated by fractional precipitation. The composition of copolymer, i.e., the molecular weight of main chains and side chains, was determined. The influence of molecular weight and structure of graft copolymers on the intrinsic viscosity of solutions was examined. This may be expressed in the form [η] = KMagn. The dependence between a and n in this equation was established.
Adhesion of high polymers. II. Wettability of elastomers
Authors: Lee Lieng‐Huang
Published: April 2003

Data on wettability of elastomers should be considered basic to the understanding of all phases of elastomer adhesion. However, no such data in the form of critical surface tensions were available for elastomers other than polydimethylsiloxane. For this study, 18 elastomers were selected to determine the effects of functional groups, of geometrical and structural isomerisms, of copolymerization, and of the induced orientation upon wettability. Most results support the constitutive law of wettability established by Shafrin and Zisman. The effect of structural isomerisms in the form of a vinyl side group and cyclization is discussed. An equation for the calculation of critical surface tension of a copolymer or of a mixture of isomers is proposed as follows:

where Ni is the mole‐fraction of the individual monomer in the copolymer and \documentclass{article}\pagestyle{empty}\begin{document}$ \gamma _{c_i } $\end{document} is the critical surface tension of each homopolymer. Most elastomer adhesion studies conducted in the past were concerned with the diffusion theory of adhesion. This study further supports the conclusion on the role of diffusion and adsorption in adhesion advanced in Part I, especially with respect to the physical state of polymer at the time of application. The wettability data in this study could shed some light upon major basic mechanisms involved in elastomer reinforcement.