bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress‐optical coefficients of swollen polymer networks
Authors: Gent A. N. , Kuan T. H.
Published: April 2003

Stress‐optical coefficients have been determined for crosslinked samples of polyethylen (PE) and polystyrene (PS) at high temperatures, i.e., in the rubberlike state, and when swollen in a variety of liquids. For PE, swelling liquids with long straight molecules gave large values of optical anisotropy whereas liquids with more symmetrical molecules gave minimum values, as found previously for cis‐ polyisoprene and trans‐polyisoprene. This solvent effect is attributed to short‐range orientational order in molecularly asymmetric media. Sizes of the equivalent random link for unperturbed molecules of these three polymers were deduced from the minimum values of optical anisotropy. Measures of shape asymmetry were also obtained by matching the optical anisotropy of samples when unswollen with that observed when swollen with a liquid of known molecular asymmetry. Reasonable agreement was found to hold between the two methods. In contrast, the optical anisotropy of swollen PS was found to be substantially independent of the swelling liquid. The apparent absence of a molecular ordering effect in this case is attributed to the bulky nature of the PS molecule. A marked reduction in optical anisotropy on swelling is ascribed to increased phenyl group motion.
New approach to the effects of pressure dependence on sedimentation velocity experiments
Authors: Dishon Menachem , Stroot Michael T. , Weiss George H. , Yphantis David A.
Published: April 2003

A theory is developed for sedimentation velocity experiments when the sedimentation coefficient sp depends on pressure P as sp/so = (1 + γP)−1, where γ is a constant. In contrast to the more usually analyzed from sp/so = 1 − γP, this model does not lead, in extreme cases, to a negative sedimentation rate. A theory is presented for homogeneous macromolecules sedimenting with no diffusion. It leads to estimations of so and γ from a knowledge of the point of maximum concentration gradient as a function of time. Results of these calculations are compared with accurate numerical solutions of the Lamm equation with diffusion included.
ESR study of radiation damage in TPX polymer (poly‐4‐methylpentene‐1)
Authors: Goodhead D. T.
Published: April 2003

Electron spin resonance spectroscopy has been used to study the effects of 15 MeV electrons, x‐rays, and ultraviolet radiation on poly‐4‐methylpentene‐1 (TPX) both at 77°K and at room temperature. At least seven identifiably different paramagnetic species are observable in unstabilized oxygen‐free TPX after irradiation, and additional species exist in the stabilized grades. The species which predominates under most conditions is interpreted as being due to the loss of hydrogen from a main‐chain tertiary carbon atom; interpretations of most of the other species are also given. Oxygen is found to diffuse rapidly into the polymer and to react with the free radicals to form peroxy species. In the absence of oxygen the radiation damage is expected to lead ultimately to crosslinking or double‐bond formation, or with oxygen to degradation. The general nature of the free radicals produced by electron or x‐ray irradiation is the same, but there are significant differences for ultraviolet irradiation. The observed spectra for irradiated TPX and their interpretations are in good agreement with the spectra and later interpretations for irradiated polypropylene, but are in less satisfactory agreement with the published papers on polybutene‐1 and poly‐3‐methylbutene‐1.
Redrawing of oriented polyethylene film
Authors: Yamada Mitsuo , Miyasaka Keizo , Ishikawa Kinzo
Published: April 2003

Drawn and subsequently annealed polyethylene film was restretched along the original draw axis at various temperatures. The internal deformation was analyzed in terms of the structural parameters of a simplified model. The elementary deformations are the rotation of crystals around the b axis and shear at the crystal interface. The rigidity of the crystal plays an important role during extension; and as a result, disorientation of chains in the crystal occurs at high strain. At the same time, crystals deform in such a way that the crystalline chains tilt about the b axis along the (h00) plane. This deformation of the crystal is affected by temperature. The increase in long spacing with extension can be interpreted roughly by the changes in structural parameters. The strain in amorphous region in also discussed in relation to these parameters.
Morphological effects on formation and behavior of radicals in γ‐irradiated polyethylene single crystals
Authors: Kusumoto Naoshi , Yamamoto Tateo , Takayanagi Motowo
Published: April 2003

Polyethylene single crystals differing in lamellar thickness, both as‐grown and annealed with different lamellar thickness, were irradiated by γ‐rays to a dose of about 107 rad at liquid nitrogen temperature in vacuo, and then ESR measurements were made. It was found for the as‐grown crystals that alkyl radicals were concentrated at the crystal surface. For the annealed crystals it was found that the radical concentration was greater than in the original crystals because of an increase in disorder with annealing. By assuming that the crystals form blocks upon annealing and that the surface and the interior of the blocks have the same trapping capacities for radicals as in the original crystals, the dependence of the size of the blocks upon variation in annealing temperature and the original lamellar thickness was estimated. This estimate is supported by the theory of the thickening process of single crystals. Two types of radical reactions with different reaction rates were found to occur simultaneously at room temperature. The rapid process was independent of lamellar thickness and was related to the reaction of radicals mainly in the surface region and the defects within the crystals. The slow process was strongly dependent on the lamellar thickness (i.e., the reaction rate was much depressed as the lamellar thickness was increased) and was inferred to be closely related to molecular motions manifested in viscoelastic measurements by the crystalline dispersion αc.
Infrared studies of drawn polyethylene. II. Orientation behavior of highly drawn linear and ethyl‐branched polyethylene
Authors: Glenz W. , Peterlin A.
Published: April 2003

Infrared dichroism is employed to study the orientation of chain molecules in linear and ethyl‐branched polyethylene in the crystalline and noncrystalline regions during drawing and subsequent annealing. A crystalline (1894 cm−1) and a noncrystalline (1368 cm−1) band, as well as the bands at 909 cm−1 and 1375 cm−1 resulting from vinyl endgroups and methyl endgroups and sidegroups, are studied. For these bands relative orientation functions are derived and compared as a function of draw ratio and annealing temperature. It is shown that the relative orientation functions as derived from the dichroism of the noncrystalline, vinyl and methyl bands follow the same curve while the orientation function for the crystalline bands does not. These results support a two‐phase model for partially crystalline polyethylene and additionally favor segregation of the endgroups and sidegroups in the noncrystalline component during crystallization. It is further shown that shrinkage occurs at the temperature at which the noncrystalline chain molecules start to disorient. From the dichroism of the methyl groups in ethyl‐branched polyethylene, a value for the mean orientation of the noncrystalline chain molecules is calculated. We obtain for the orientation function of the noncrystalline regions at highest draw ratios (λ = 15–20), f = 0.35–0.57, while the chain molecules in the crystallites are nearly perfectly oriented (f ≈ 1.0). On the assumption that the noncrystalline component consists of folds, tie molecules, and chain ends, the different contributions of these components to the overall orientation are estimated. From these the relative number of CH2 groups incorporated into folds, tie molecules, and cilia can be derived. Further, on the basis of a simple structural model, the relative number of chains on the crystal surface contributing to the different noncrystalline components and their average length are estimated.
Properties of ethylene–propylene–vinyl chloride graft copolymers. I. Viscoelasticity of ethylene–propylene copolymers
Authors: Bares J.
Published: April 2003

The viscoelastic behavior of two different ethylene–propylene copolymers was studied as a function of the molar ratios of the components and the distribution of the lengths of the ethylene and propylene sequences. The glass transition temperatures Tg agree with the values calculated from relations between Tg and component ratio established by other authors. The copolymer with longer ethylene and propylene sequences was found to exhibit a relaxation spectrum with a slope less steep than −0.5. This broadening is explained by the broader distribution of friction factors of the statistical segments in this copolymer and by differences in crystallike nearest‐neighbor packing.
Glass transition in partially sulfonated polystyrene
Authors: Wallace Richard A.
Published: April 2003

The glass transition temperature Tg of partially sulfonated polystyrene has been measured dilatometrically as a function of degree of sulfonation. A semitheoretical relationship between Tg and degree of sulfonation has been derived by treating the strong‐acid polymer as a highly polar copolymer of styrene and styrenesulfonic acid. The Tg of copolymer has been found to increase linearly up to 0.15 weight fraction of styrene‐sulfonic acid wA as given by:

where TgB is the glass transition temperature of loosely crosslined (1%) polystyrene matrix. Our experimental results agree well with theoretical relations developed on the basis of the iso‐free‐volume state of glass transition applied to sulfonated polystyrene. The marked linear increase in copolymer Tg with the styrenesulfonic acid is accounted for by the effect of progressively higher intermolecular forces due to the highly polar sulfonic acid substituents.
A new relaxation process in the high‐elastic state at low temperatures
Authors: Bartenev G. M.
Published: April 2003

A new relaxation process, explaining the change of elasticity in rubberlike polymers at critical stress (0.1−0.5 kgf/cm2) has been discovered. This process is characterized by the low value of activation energy (weak temperature dependence of relaxation times) and large sizes of kinetic units (strong dependence of relaxation time on stress). Critical stress depend on temperature and for rubberlike polymers turns to zero at 40°−60°C. Mechanism of the phenomena can be explained by the existence of the ordered molecular microregions, creating additional crosslinking points of nonchemical nature with free chains of the network, breaking up at critical stress. Observed phenomena is analogous to the process of forced rubber elasticity of those polymers in glassy state. Critical stress is analogous to the limit of forced rubber elasticity below glass transition temperature.
Sedimentation equilibrium in nonideal heterogeneous systems. I. Fundamental equations for heterogeneous solute systems and some preliminary results
Authors: Kotaka Tadao , Donkai Nobuo , Inagaki Hiroshi
Published: April 2003

The sedimentation‐equilibrium method is extended to treat nonideal solutions of heterogeneous macromolecules. The solute is assumed to be heterogeneous not only in molecular weight but also in other quantities such as partial specific volume, second virial coefficient and specific refractive increment. General expressions for various observable molecular weights, especially for weight‐average, z‐average, and number‐average molecular weights, are derived. Their dependences on sedimentation parameter and solute concentration are discussed in detail. For the extrapolation of observable molecular weights, giving a type of weight‐average, and z‐average, to infinite dilution to estimate the molecular weight and the second virial coefficient, average concentration is superior as a concentration variable to original concentration. The plots of observable molecular weight versus average concentration are usually less influenced by the choice of the sedimentation parameter, especially of rotor speed. The general expressions are applied to a few special cases; monodisperse polymer, polydisperse homologous polymer, and polymer blend. The results are compared with experiments on a monodisperse, polystyrene, a polydisperse poly(methyl methacrylate), and a mixture of the two polymers, all in 2‐butanone at 25°C. The agreement between the theory and experiments is satisfactory.
Theory of deformation and strain‐induced crystallization of an elastomeric network polymer
Authors: Yamamoto Misazo , White James L.
Published: April 2003

A new theory of deformation and strain induced crystallization of network polymers has been developed. The effects of lattice vacancies, variation in distribution of trans and gauche bond conformations in stretched amorphous polymers, and the crystallite orientation in the partially crystalline stretched vulcanizate were considered in the evaluation of their partition functions. Stress‐extension ratio relationships were evaluated for the amorphous and semicrystalline polymers. The rise in melting temperature due to strain induced crystallization is discussed. The new theory seems to be in closer agreement with the actual strain‐induced crystallization process than earlier research.
Stress‐optical coefficient of poly‐1,4‐butadienes
Authors: Fukuda M. , Wilkes G. L. , Stein R. S.
Published: April 2003

The stress‐optical coefficient of poly‐1,4‐butadiene is measured as a function of strain, cis/trans ratio, and degree of swelling. Deviations from the Kuhn‐Grün theory are found which are reduced upon swelling. Results are interpreted in terms of the Shindo‐Stein theory of birefringence of polymers containing statistical segments of different sizes. This interpretation for the unswollen polymer leads to the unreasonable conclusion that the cis segment is considerably longer than the trans. Reinterpretation for the swollen polymer leads to the more reasonable conclusion that the trans segment is slightly longer than the cis. The dependence of the stress‐optical coefficient on the nature of the swelling solvent is similar to the observations of Gent and Nagai and is believed to result from the effect of internal field from anisotropic solvent molecules. It is felt that the value of the stress‐optical coefficient for the dry rubber is modified by the internal field from somewhat locally ordered neighboring polymer molecules.
NMR observations of drawn polymers. VII. Nylon 66 fibers
Authors: Olf Heinz G. , Peterlin A.
Published: April 2003

Wide‐line NMR spectra have been obtained on an oriented sample of drawn nylon 66 fibers at temperatures between −196°C and 200°C and at alignment angles between the fiber axis and the magnetic field of 0°, 45°, and 90°. At −196°C, 20°C, and 180°C, the complete angle dependence of the NMR spectrum has been measured. The second moments of these spectra have been compared to theoretical second moments calculated for various models of chain segmental motion in an attempt to elucidate the mechanisms involved in the low‐temperature segmental motion (γ process) and the high‐temperature segmental motion (αc process). In agreement with earlier suggestions, the present results indicate that the γ process consists of segmental motion in noncrystalline regions. The overall decrease in second moment caused by the γ process is consistent with a model in which all noncrystalline segments rotate around axes nearly fixed in space. Furthermore, this decrease shows a pronounced dependence on the alignment angle. It is believed that this is due to tie molecules which become highly oriented along the fiber axis during drawing; their axes of rotation will therefore be nearly parallel to the fiber axis. The segments in noncrystalline entities such as chain folds and chain ends are less well oriented along the fiber axis and make an essentially isotropic contribution to the second moment decrease. The second moment at 180°C indicates the presence of considerable motion in the crystalline regions, and this motion is denoted the αc process. The second moment Sc of the crystalline regions is strongly dependent on the alignment angle, the predominant feature being a relatively high value of the second moment when the fiber axis is directed parallel to the magnetic field. This is in qualitative, but not quantitative, agreement with the motional model recently advanced by McMahon, which assumes full rotation of the chains around their axes. Excellent quantitative agreement with experiment has been obtained by superimposition of rotational oscillation around the chain axis of amplitude roughtly 50°, and torsion of the chains with neighboring CH2 groups oscillating around the CC bond with a relative amplitude of about 40°. A model in which the chains perform rotational jumps of 60° between two equilibrium sites has also been considered (60° flip‐flop motion). A distinction between this model and rotational oscillation has not been possible.
Single crystals of amylose V complexes. III. Crystals with 81 helical configuration
Authors: Yamashita Yuhiko , Monobe Kazuo
Published: April 2003

Single crystals of amylose V complexes with the 81 helical configuration can be obtained from aqueous solutions of amylose by using α‐naphthol as a complexing agent. Morphological observations suggest that the differences in crystallization behavior among the α‐naphthol complex and other complexes with alcohols are due to differences in solubility of the complexes in water. Electron diffraction studies indicate a two‐dimensional tetragonal unit cell with a = b = 22.9 Å. It is deduced that the space group providing a satisfactory arrangement of two helices is one of the enantiomorphs P41212 and P43212. From x‐ray diffraction it was found that the c axis spacing of the α‐naphthol complex is equivalent to that in 61 and 71 helical amylose crystals. Consequently, the geometry of the helical configuration requires an integral number of glucose residues per turn. The true helical diameters of the n‐butanol, isopropanol, and α‐naphthol complexes were calculated from experimental data. The ratio was 6:7:8 and indicated that the helix of the α‐naphthol complex has eight glucose residues per turn. The diversity of helical configurations in V amylose crystals is discussed.
Vibrational analysis of poly(vinylidene fluoride)
Authors: Boerio F. J. , Koenig J. L.
Published: April 2003

A vibrational analysis has been carried out for the two crystalline forms of poly(vinylidene fluoride) (PVF2). The Raman spectrum of the planar form of PVF2 is also reported. The band assignments are made on the basis of the spectral properties including the infrared dichroism and Raman intensities. A force field is derived based on a force constant refinement procedure utilizing the frequency data for both crystal forms.
Salt rejection by polymer membranes in reverse osmosis. I. Nonionic polymers
Authors: Yasuda H. , Lamaze C. E.
Published: April 2003

An attempt is made to analyze the relationship between salt rejection and water flux of nonionic polymer membranes in reverse osmosis on the basis of the movement of water in the membranes. The salt rejection Rs is a consequence of transport depletion of salt in relation to water flux. The transport depletion can be quantitatively expressed through knowledge of the mode of water transport and by application of free‐volume theory to membrane transport phenomena. Water permeation can be characterized by a parameter ω = RTK1/P1v1, K1 denoting hydraulic permeability, P1 diffusive water permeability, v1 the molar volume of water. Thus polymer membranes can be classified in three categories: ω = 1 (diffusion membranes); ω > 1 (diffusion‐flow membranes); and ω ≫ 1 (flow membranes). Salt rejection Rs can be expressed in terms of P1, the diffusive salt permeability P2, and the effective pressure (Δp − Δπ):

Experimental results obtained with various hydrophilic polymers are presented as the dependence of Rs on the logarithm of water flux. Good agreement was found between the experimental data and the calculated curve. Excessive swelling of membranes results in bulk flow of water (high ω) with coupled transport of salt. Hence the salt rejection decreases quickly as water flux in creases beyond a threshold value above which water flux can be characterized as bulk flow.
Sorption properties of polypropylene
Authors: Ochiai Hiroshi , Gekko Kunihiko , Yamamura Hitoshi
Published: April 2003

The sorption properties of atactic polypropylene (APP) and isotactic polypropylene (IPP) were studied by equilibrium sorption of various organic solvents. The variation of the Flory‐Huggins interaction parameter χ for the APP‐CCl4 system at 25°C was expressed as a function of the volume fraction v2 of polymer by the relation: x = 0.113 exp {1.879 v2}. The average molecular weight Mc of the polymer chains between successive crystallites for IPP subjected to different thermal treatments was calculated to be 250 to 350 by the equation of Flory and Rehner. From the variation of Mc with solvent concentration, we estimated the number fraction of polymer chains actually contributing to elastic deformation. The clustering function for solvent in the polymer calculated by the method of Zimm and Lundberg decreased linearly from a positive value to −1 with increasing solvent concentration. Clustering of solvent molecules was found to occur more easily in APP than in IPP.
Catalysis of ionic reactions by polyelectrolytes. IV. Quenching of the quinine cation fluorescence by Fe++, Ag+, and Br− in solutions of poly(vinylsulfonic acid)
Authors: Taha Issam A. , Morawetz Herbert
Published: April 2003

The fluorescence quenching of the doubly charged quinine cation by Fe++, Ag+, and Br− was studied in the presence and absence of polyvinylsulfonate (PVS). The quenching by cationic species was greatly enhanced by PVS at low polyion concentrations; at higher concentrations of PVS, the fluorescence intensity increased owing to displacement of the quinine cations from the polyion domain. Quenching of quinine fluorescence by Br− was repressed by PVS. Interpretation of the data with the use of Fe++ as the quenching agent led to “effective concentrations” of counterions in the polyion domain similar to those calculated from the catalysis of the redox reaction of Co(NH3)5Cl++ with Fe++. This may indicate that the reagent ions are not rigidly bound to the polyion chain, since such binding would affect differently processes with high and low activation energies. The Stern‐Volmer constant for self‐quenching of the quinine fluorescence can also be obtained from fluorescence intensity data in PVS solution.
Crystal orientation in a semicrystalline polymer in relation to deformation of spherulites
Authors: Nomura Shunji , Asanuma Akira , Suehiro Shoji , Kawai Hiromichi
Published: April 2003

A mathematical development interrelating the orientation distribution functions of three kinds of orientation units for a polymer spherulite (i.e., a crystal lamella, a crystallite, and a given reciprocal lattice vector of the crystallite) is formulated on the basis of series expansions of the distribution functions in generalized spherical harmonies. Two types of uniaxial deformation models of a polyethylene spherulite, taking account of micronecking and untwisting of crystal lamellae, and of chain tilting and untwisting of crystal lamellae, respectively, both in addition to affine deformation of the lamellae are discussed. The models are tested by comparison of the theoretical orientation distribution functions of some reciprocal lattice vectors of the crystallite with the results of x‐ray diffraction experiments.
Piezoelectricity in oriented films of poly(γ‐benzyl‐L‐glutamate)
Authors: Konaga Toshiyoshi , Fukada Eiichi
Published: April 2003

Oriented films of poly(γ‐benzyl L‐glutamate) (PBLG) were prepared by two methods. Films of PBLG cast from chloroform solutions were elongated by rolling at 70°C. A solution of PBLG in methylene bromide was placed in a magnetic field of about 7000 gauss and the solvent was slowly evaporated for a few days until an oriented film was obtained. The real and imaginary components of the complex piezoelectric strainconstant d25* = d25′ − jd25″ were determined over the temperature range from −180°C to +180°C at a frequency of 20 Hz. The constants showed dispersions at about 20°C and about 100°C, where dynamic viscoelastic dispersions were also observed. Degree of crystallinity Xc and degree of orientation IIa of crystallites were determined from x‐ray diffraction diagrams. The product XcIIα and the value of d25′ at room temperature were found to be linearly related, and both showed a maximum at an elongation ratio of 1.5 (the ratio of the final to initial length) for roll‐oriented films and at an initial solution concentration of 15% by weight for magnetically oriented films. The largest values of d25′ were approximately 2 × 10−12 and 4 × 10−12 coulomb/newton, respectively, at room temperature.
Terephthalamide‐nylon single crystals isolated from dilute solutions of hexafluoro‐2,2‐propandiol
Authors: Livingston H. K. , Gregory R. L.
Published: April 2003

Terephthalamide nylons with two to five carbon atoms in the aliphatic portion of the chain have been crystallized from aqueous solutions of hexafluoro‐2,2‐propandiol. The 3T and 4T nylons in particular form rodlike crystals. Indications are that these are bundles of cylindrical structures about 50 nm in diameter. Electron diffraction shows the symmetry to be C2v. Films of the nylons were drawn with great difficulty. The x‐ray diffraction on the films is consistent with a monoclinic structure, though the crystal structure could not be positively established. There is some evidence for a polymer chain alignment perpendicular to the long axis of the rods.
Electron spin resonance of γ‐irradiated poly(ethylene 2,6‐naphthalene dicarboxylate)
Authors: Rogowski R. S. , Pezdirtz G. F.
Published: April 2003

The two types of radicals trapped in γ‐irradiated poly(ethylene 2,6‐naphthalene dicarboxylate) (PEN 2,6) have been identified by ESR as OCHCH2O (radical I) and a radical located on the naphthalene ring (radical II). The relative concentrations of radicals in the gross polymer are 10–20% radical I and 80–90% radical II. Similar trapped radicals have been identified in γ‐irradiated poly(ethylene terephthalate) (PET), a structurally related polymer which differs only in the aromatic moiety, but the relative radical concentrations are quite different. These results are discussed in relation to the radiation resistance of the two polymers.
Apparatus for instantaneously measuring ultraviolet, visible, or infrared dichroism from thin polymer during high‐speed stretching
Authors: Wilkes Garth L. , Uemura Y. , Stein Richard S.
Published: April 2003

An apparatus has been constructed for following changes in the dichroism of a polymer film undergoing rapid elongation. By means of a rapidly rotating mirror with evenly spaced open sectors, a beam of radiation is passed through the sample and then alternately polarized in the horizontal and vertical direction so that the horizontal and vertical absorbances may be rapidly compared in time as compared with the time of sample elongation (a few milliseconds). The apparatus utilizes reflection optics and a grating monochromator so that measurements may be made by using ultraviolet, visible, or infrared radiation. The transmitted intensity is detected by a photomultiplier or semiconductor infrared device, the output of which is amplified and displayed on an oscilloscope. A temperature‐controlled sample chamber is provided. The operation of the apparatus is illustrated by following the change in dichroism of a sample of dehydrohalogenated poly(vinyl chloride) with visible radiation during rapid extension.
Mechanism aspects of th e ring‐opening polymerization of the episulfides compared to epoxides
Authors: Vandenberg E. J.
Published: April 2003

The cis‐ and trans‐2‐butene episulfides polymerize with cationic catalyts differently than reported for the corresponding oxides. Where the cis‐oxide gave amorphous disyndiotactic polymer, the cis‐sulfide gives crystalline racemic diisotactic polymer since this polymer could be asymmetrically synthesized in optically active form. Also the same crystalline polymer was obtained with coordination catalysts. Where the trans‐oxide gave only crystalline, meso‐diisotactic polymer, the trans‐sulfide gives mainly amorphous polymer which, in one case, did slowly crystallize. The difference between the trans forms appears due to the longer CS bond which lowers steric hindrance and thus isomer selection in the attack of episulfide on the growing sulfonium ion to give less steroregular polymer. The difference in the cis forms may result from the sulfur atom in the last chain unit coordinating with the counterion. The greater hindrance around oxygen in the comparable oxide polymers may prevent the same mechanism from being utilized. The cationic polymerization of isobutylene sulfide gives both crystalline and amorphous polymer. NMR evidence indicates that the amorphous polymer results from substantial head‐to‐head, tail‐to‐tail polymerization, along with the expected head‐to‐tail polymerization. The same phenomenon occurs, but to a lesser extent, in cationic isobutylene oxide polymerizations. The preparation and properties of high molecular weight, head‐to‐tail isobutylene oxide and sulfide polymers from R2Mg‐NH3 coordination catalysis are described.
Comparative synthesis of oligomeric group IV polyesters
Authors: Carraher Charles E. , Dammeier Roger L.
Published: April 2003

Oligomeric group IV polyesters of the form: magnified image have been synthesized by using the interfacial technique. Polymerization rate follows the order Sn > Ge > Si as M is varied. Aliphatic‐substituted organometallic compounds exhibit higher polymerization rates than do aromatic‐substituted organometallic compounds. This may be the result of (p → d)π bonding between the vacant d orbitals of the metal and the p electrons of the phenyl rings.
Anionic polymerization of a fluorinated butadiene
Authors: Kaufman Martin H.
Published: April 2003

1,1‐Bis(trifluoromethyl)‐1,3‐butadiene (I) is cleanly prepared in three steps. I produces an amorphous polymer by free‐radical catalysis. Crystalline poly‐I is produced by butyllithium catalysis in tetrahydrofuran at −78°C. Qualitative kinetic experiments indicate that the anionic polymerization proceeds by a “living polymer” process. An AB block copolymer may be formed by adding I to anionically propagating butadiene; however, the reverse does not occur.
Preparation of polyethylene in solution
Authors: Christman Donald L.
Published: April 2003

Polyethylene was prepared in a homogeneous system at 120°C. Several catalytic systems were employed, all using a soluble vanadium compound. The first consisted of an alkylaluminum compound in conjunction with the vanadium compound and a “promoter.” This promoter, which is believed to act as an oxidizing agent to reactivate dead catalyst sites, was a polyhalo compound with esters of trichloroacetic acid preferred. The promoter was added continuously throughout the polymerization. Polyethylene so produced had a narrow M̄w/M̄n ratio close to the theoretical ratio of 2.0 for a single catalyst site. Up to 266 polymer chains were produced per vanadium atom. In the second system, the cocatalyst was an AlBr3(AlCl3)–(C6H5)4Sn[(C6H5)3Bi] combination. The continuous addition of a promoter such as methyl trichloroacetate was necessary, presumably to reactivate dead catalytic sites. By this procedure, yields up to 6.6 kg of polymer per millimole of vanadium and 30–60 chains per vanadium atom were achieved. The product had a narrow M̄w/M̄n ratio of 2.4 by gel‐permeation chromatography (GPC). A study of the interactions of the catalyst compounds indicated that CCl3COOR does oxidize di‐ and trivalent vanadium.
Synthesis of titanium polythioethers
Authors: Carraher Charles E. , Nordin Robert J.
Published: April 2003

The synthesis of polythioethers of the form magnified image was effected, where Cp denotes cyclopentadienyl. Four reaction systems were studied and evaluated. Two proved to be undesirable (the “reverse” interfacial and organic solution methods), while two proved acceptable (the “normal” interfacial and aqueous solution methods). A number of added bases were evaluated. Et3N and NaOH were found to be acceptable. Yield increases with reaction time for aqueous solution syntheses, while yield remains constant with reaction time for synthesis via the normal interfacial method.
Oxidative polymerization of aromatic hydrocarbons: A study of kinetics and mechanism
Authors: Mano Eloisa B. , Alves Luiz A.
Published: April 2003

Aromatic hydrocarbons were homopolymerized by means of an oxidative polymerization reaction with the use of the catalyst system anhydrous aluminum chloride–cupric chloride. The kinetics of the benzene homopolymerization carried out under different experimental conditions was followed by the determination of the amounts of cuprous ion and polymeric product formed in the reaction. Cuprous ion was spectrophotometrically titrated in the form of its complex with 2,2′‐biquinolyl (cuproine). The experimental results do not agree with cationic mechanism for this reaction previously proposed in the literature. Ethylbenzene was kinetically studied under the same experimental conditions. In view of the experimental evidences obtained in this work and on some literature data, a mechanism based on formation of cation‐radicals is proposed for the oxidative polymerization reaction when carried out under the studied conditions.
Cationic polymerization of α,β‐disubstituted olefins. XV. Stereospecific polymerization of butenyl ethers by cationic catalysts
Authors: Higashimura T. , Hoshino M.
Published: April 2003

Methyl, ethyl, and isopropyl butenyl ethers, CH3CH2CHCHOR, were polymerized with homogeneous catalysts at −78°C. Toluene, methylene chloride, and nitroethane were used as solvents, and BF3O(C2H5)2 and SnCl4·CCl3CO2H were used as catalysts. The stereoregularity of the polymers were compared by x‐ray diagrams and infrared absorption ratios. The stereoregularity of polymers increased with increasing content of the trans isomer in the monomer and with increasing polarity of the solvent. In the polymerization of methyl and ethyl butenyl ethers, crystalline polymers were obtained from both the trans and cis isomers. The crystalline polymer prepared from the trans isomer and that from the cis isomer had the same steric structure. This behavior is quite different from that observed in the polymerization of propenyl ethers. It is concluded that the bulkiness of the group on the olefinic β‐carbon plays an important role in the stereospecific polymerization of α,β‐disubstituted olefins.
Theory of titration curves. VIII. A new interpretation of acid‐base titration curves for polymeric acids. The significance of the Kern‐equation parameters pKa and n
Authors: Meites Louis
Published: April 2003

The Kern equation, pH = pKa + n logf/(1 − f), has been widely used in interpreting the potentiometric titration curves obtained on titrating polymeric acids with bases, and various interpretations of its empirical parameters pKa and n have been advanced. Values of n similar to those generally obtained for polymeric acids are also obtained for dibasic and other monomeric polybasic acids for which the ratios of successive dissociation constants, Ki/K(i+1), exceed the corresponding statistical values by a constant factor. The dependences of n on this factor and on the basicity of the acid are described. It is argued that the traditional picture of a dissociation constant varying continuously with the fraction titrated cannot be correct, and that the data can be more properly interpreted in terms of a constant non‐statistical free‐energy contribution to the successive values of Ki/K(i+1).
Preparation and polymerization of a diisocyanate from the Diels‐Alder adduct of levopimaric acid and acrylic acid
Authors: Bingham John F. , Marvel C. S.
Published: April 2003

Starting from tetrahydroabietic acid the model compounds tetrahydroabietoyl chloride, 2‐aminoethyltetrahydroabietate hydrochloride, and 2‐isocyanatoethyltetrahydroabietate have been prepared. Carbamate and urea derivatives of the isocyanate have been prepared. A Diels‐Alder adduct of levopimaric acid and acrylic acid has been prepared and converted to its diacid chloride. The β‐aminoethyl ester hydrochloride has been synthesized and converted to a diisocyanate which has been polymerized with poly(tetramethylene glycol) and also with p‐phenylenediamine. Dimerex resin, a technical polymerized rosin, has been similarly converted to a diisocyanate. This isocyanate has not proven to be useful as a polymer‐forming intermediate.
Aromatization of polydiethynylbenzene
Authors: Bracke W.
Published: April 2003

The reactions of polydiethynylbenzene with hydrogen sulfide or primary amines are described. The properties of the resulting fully aromatic polymers are reported.
Polypyrazoles and polyisoxazole from polydiethynylbenzene
Authors: Bracke W.
Published: April 2003

The reaction of polydiethynylbenzene with hydrazine is described. The resulting polypyrazole has good tensile properties and good thermal stability. N‐Methylhydrazine and hydroxylamine react in a similar way but product properties are inferior. Polypyrazole polymers can easily be modified with acid chlorides or isocyanates.
Desorption reaction of ferric ions adsorbed on cellulosic materials by acids
Authors: Ogiwara Yoshitaka , Kubota Hitoshi
Published: April 2003

Factors affecting the desorption reaction of ferric ions adsorbed on cellulose and oxidized poly(vinyl alcohol) fibers by acids were investigated. The desorbing effect generally increased with increasing acid concentration, treating temperature, and treating time, although the magnitude of this effect varied somewhat from one acid to another. Oxalic acid, hydrochloric acid, sulfuric acid, sulfurous acid, and phosphoric acid are examples of those acids which show large desorbing effects. Scission of the cellulose chain was also observed under the desorption conditions used for such acids. The desorption reaction may be divided into two stages, an initial fast reaction and a subsequent slow reaction; the activation energies were calculated for each reaction, and values of 7–10 kcal/mole and 5–6 kcal/mole were obtained for cellulose and oxidized poly(vinyl alcohol) fibers, respectively.
Study of the effect of stabilizer on the degradation of poly(vinyl chloride) by pyrolysis–gas chromatography
Authors: Suzuki Mikio , Tsuge Shin , Takeuchi Tsugio
Published: April 2003

The effect of stabilizer on the thermal degradation of poly(vinyl chloride) was studied by means of pyrolysis–gas chromatography. The stabilizers used in this study were dibutyltin dilaurate, dibutyltin bis(n‐dodecyl mercaptide), barium stearate, and zinc stearate. PVC containing these stabilizers was degraded in a stream of nitrogen at temperatures ranging from 350 to 570°C. It was found that observed drastic reduction of benzene yield from the PVC containing zinc stearate had a close correlation with the formation of crosslinking structures.
Synthesis and polymerization of heteroaromatic vinyl monomers
Authors: Iwakura Yoshio , Toda Fujio , Suzuki Hideaki , Kusakawa Norihisa , Yagi Kohji
Published: April 2003

Methods of preparing new monomers, 2‐vinyl and 2‐isopropenyloxazoles and 2‐isopropenyl‐1,3,4‐oxadiazoles are described. New methods were developed to synthesize monomers containing an isoxazole or a thiazole ring. Radical homopolymerization and copolymerization with styrene of these monomers were carried out by using AIBN as an initiator. Monomer reactivity ratios r1, r2 and Alfrey‐Price Q–e values were determined by the Fineman‐Ross and the Mayo‐Lewis methods. The localization energy of the β‐carbon was calculated by a HITAC‐5020 computer, and the monomer reactivity is discussed in terms of Lβ.
Stereoregularity of poly(isopropyl acrylate) and its racemization during hydrolysis
Authors: Matsuzaki Kei , Okada Munehisa , Hosonuma Kunihiko
Published: April 2003

The diad tacticity of poly(isopropyl acrylate) was measured from the β‐proton absorptions of poly(isopropyl acrylate‐α,β‐d2) obtained with a 100 MHz NMR spectrometer, and temperature dependence of the tacticity of the polymers obtained by radical polymerization was determined. Enthalpy and entropy differences between isotactic and syndiotactic addition for poly(isopropyl acrylate) were calculated to give the following values: Δ(ΔS) = 0.7 eu; Δ(ΔH) = 0.51 kcal/mole. In the hydrolysis of poly(isopropyl acrylate‐α,β‐d2), it was found that the rate of hydrolysis of poly(isopropyl acrylate) was dependent on the molecular weight rather than on the tacticity. As for the rate of racemization during hydrolysis, the rate for syndiotactic polymer was much faster than that for the isotactic polymer. The exchange reaction of deuterium at α‐position with hydrogen occurred in all the polymers during hydrolysis reaction.
Catalysis of novolacs by p‐phenolsulfonic acid
Authors: Wagner E. R. , Greff R. J.
Published: April 2003

The reaction rate of phenol and aqueous formaldehyde in the presence of p‐phenolsulfonic acid has been studied. The increase in pH during the reaction, which decreases the reaction rate, can be correlated with the disappearance of polyoxymethylene (formaldehyde), but not as previously supposed solely with the dilution effect of the water formed from the reaction. Gel‐permeation chromatography was used to monitor the consumption of phenol and the growth of polymeric species. It has been demonstrated that the formation of a second liquid phase during the novolac process is independent of the amount of catalyst. The liquid two‐phase system and its relation to the reaction rate have been examined. The final molecular weight distribution of novolacs is dependent not only on the initial pH of the system, but also on the pH at the onset of devolatilization.
New thermally stable polymer with a graphite‐type structure
Authors: Hurley S. A. , Dutt Prabir K. , Marvel C. S.
Published: April 2003

A new thermally stable polymer with a structure resembling that of graphite has been synthesized by the condensation of 1,4,5,8‐tetraaminoanthraquinone and 1,3,6,8‐tetraketo‐1,2,3,6,7,8‐hexahydropyrene (naphthalene‐1,8,4,5‐diindandione). Prepolymers, with an open structure, were soluble to some extent in concentrated sulfuric acid but were more completely solubilized by methanesulfonic acid. The final polymer with a closed‐ring structure, which was obtained by heating the prepolymer having an inherent viscosity of 0.4, was completely insoluble in these acids. Elemental analysis indicated that a high degree of cyclization was achieved, and the final polymer showed good thermal stability. Prepolymers with inherent viscosities in the range 0.11–1.58 have been obtained but, usually, a high viscosity was accompanied by a low acid solubility. Prepolymers with an inherent viscosity of 0.4, which were very soluble (>90%) in strong acids, were solubilized to a high degree by reduction with sodium dithionite in alkaline, aqueous dimethylacetamide. The highest molecular weight prepolymer (inherent viscosity of 1.30–1.58) was solubilized to a greater extent in this base mixture than in methanesulfonic acid. However, it was not completely soluble, under the conditions employed. The propolymers of higher molecular weight showed some fiber‐ and film‐forming properties.
Temperature and concentration effects on polar‐modified alkyllithium polymerizations and copolymerizations
Authors: Antkowiak T. A. , Oberster A. E. , Halasa A. F. , Tate D. P.
Published: April 2003

Addition of polar modifiers to alkyllithium‐initiated homopolymerizations of butadiene causes substantial changes in the microstructure of the polymers produced. These changes are shown to depend not only on the concentration of modifier, but also on the polymerization temperature. The combined effects of modifier concentration and reaction temperature have been considered, and a method is presented for quickly determining the proper conditions for preparation of a polybutadiene of any 1,2‐microstructure within a range of 10–80%. It is also shown that in anionic polar‐modified copolymerizations of butadiene–styrene, the reaction temperature is again critical. Within a certain concentration range of modifier, the temperature will influence the rate of styrene incorporation or the randomness of styrene units in the resulting copolymers.
Syntheses of vinyl polymers containing a large π‐electron cloud in the side chain
Authors: Kamogawa Hiroyoshi
Published: April 2003

Several novel vinyl polymers containing five fused benzene rings in side chains were synthesized either by polymerization of the appropriate vinyl monomers or by chemical modification of the appropriate polymer. Thus, 3‐(α‐acryloyloxy)ethylperylene was prepared from perylene by Friedel‐Crafts acylation with acetyl chloride and subsequent hydrogenation, followed by the reaction of the resulting alcohol with acryloyl chloride. 3‐Acrylamido‐ or methacrylaminoperylene was prepared by the nitration of perylene, reduction of the resulting 3‐nitroperylene, and the reaction with acryloyl or methacryloyl chloride. p‐Vinylbenzal‐3‐acetylperylene was prepared by the condensation and dehydration reaction between p‐vinylbenzaldehyde and 3‐acetylperylene under alkaline medium, and, in the same manner, p‐vinylbenzal‐3‐aminoperylene was prepared from p‐vinyl benzaldehyde and 3‐aminoperylene. All these monomers were polymerized with α,α′‐azobisisobutyronitrile as catalyst in solution to afford the corresponding vinyl polymers. A vinyl polymer containing perylene‐3‐acetyl side chain was also prepared by the acetalization of poly(vinyl alcohol) with 3‐formylperylene.
γ‐ and ultraviolet‐radiation‐induced solid‐state polymerization of maleimide in a few binary systems
Authors: Hayakawa Kiyoshi , Yamakita Hiromi , Kawase Kaoru
Published: April 2003

The solid‐state polymerization of maleimide by γ‐ and ultraviolet irradiation was carried out in binary systems with succinimide, maleic anhydride, and acenaphthylene. Polymaleimide obtained from the solid‐state polymerization of maleimide by γ‐rays was amorphous, while that obtained from the solid‐state polymerization by ultraviolet rays was highly crystalline. In the maleimide–succinimide system the rate of polymerization reached a maximum nearly at the eutectic composition when the polymerization was carried out by γ‐irradiation. With ultraviolet irradiation the rate of polymerization became higher with increasing content of succinimide in the feed. In the maleimide–maleic anhydride system a copolymer of both constituents was formed by γ‐irradiation, but almost no homopolymer was produced. On the other hand, two kinds of polymers, a crystalline copolymer and an amorphous one, were produced by ultraviolet irradiation. The results were compared with those obtained from the copolymerization in solution. In the maleimide‐acenaphthylene system the main products with ultraviolet irradiation was the dimer of acenaphthylene.