bluuebunny/crossref_metadata_2025 huggingface dataset:
Dilute solution properties of poly(α‐methylstyrene–ethylene) “regular” sequence copolymers
Authors: Tanzawa Hiroshi , Tanaka Tatsundo , Soda Atsuhiko
Published: April 2003

“Regular” sequence copolymers having the structure {[CH2C(CH3)(C6H5)]m(CH2CH2)n}p with relatively small values of m and n were prepared by means of “living” polymerization techniques. The intrinsic viscosities of fractions of these copolymers were obtained in various solvents including a theta solvent. The molecular weights of these fractions were determined by the Archibald ultracentrifugal method. The results show that the intrinsic viscosity–molecular weight relations of the regular sequence copolymers are affected not only by the average composition of the copolymer, but also by the sequence length in the copolymer molecule. It is suggested that the effective conformation of a chain element in the copolymer is not always the same as that in the homopolymer.
Structural and steric isomerism of polypropylenes
Authors: Miyamoto Takeaki , Inagaki Hiroshi
Published: April 2003

The structural and steric isomerism of propylene polymers has been estimated on the basis of solution properties as well as infrared and high‐resolution nuclear magnetic resonance spectra. Three general types of polypropylenes were prepared: polymers prepared with the cationic catalytic system AlCl3–C2H5Cl, stereoblock polymers obtained by successive extraction from a commercial product and isotactic polymers of low molecular weight obtained by thermal degradation of a highly isotactic polymer followed by hydrogenation with Adam's catalyst in dioxane at 40°C. The characterization of all samples was accomplished by equilibrium ultracentrifugation, vapor‐pressure osmometry, viscometry, and gel‐permeation chromatography. It is found that the molecular chain of cationically prepared polymer is somewhat branched owing to structural isomerism during polymerization. Isoamyl acetate is found to be a theta solvent for stereo‐block as well as for atactic and syndiotactic polymers; the theta temperature is determined as the temperature at which the light‐scattering second virial coefficientA2vanishes. A close correlation is found between the theta temperature and stereoisomerism. The absorbances of the 1154 and 974 cm−1bands in the infrared spectra decrease with decreasing molecular weight; in addition to the mere existence of alternating CH2and CH(CH3) groups in the polymer chain, rather long sequences of this type are required for the appearance of these bands. Changes in the absorption band at 997 cm−1show that chains consisting of over ten isotactically connected monomer units can assume a helical conformation. From the high‐resolution NMR spectra of different polypropylenes, including isotactic polymers of low molecular weight, it is found that in estimating the microstructure, account must be taken of the effects of stereoisomerism within tetrads of monomer units on the apparent widths of the methylene proton resonances. If substantial concentrations of several of the possible types of tetrads are present (i.e., if the tactic sequence lengths are quite short), then it is difficult to determine the relative amounts of tactic dyads accurately from the 100 Mcps methylene proton resonances.
Birefringence of native cellulosic fibers. Part II. Spiral structure of cotton
Authors: Iyer K. R. Krishna , Neelakantan P. , Radhakrishnan T.
Published: April 2003

Interferometric studies have been made on cotton fibers as well as on twisted nylon filaments. The results so obtained provide strong evidence that the fibrils in the cotton fiber become less inclined to the fiber axis as one proceeds from the surface to the core. Also, studies on twisted nylon filaments by the fiber refractometer and Becke line techniques indicate that the latter, as practiced in this laboratory, does give values of refractive index which are heavily weighted towards the fiber periphery.
Spin lattice relaxation in linear polyethylene
Authors: Crist Buckley , Peterlin A.
Published: April 2003

The proton spin‐lattice relaxation times (T1) of linear polyethylenes (PE) of varying morphology were measured as a function of temperature. The T1 of oriented bulkcrystallized and solution‐crystallized material was isotropic, in disagreement with calculations based on a sample dipole pair model. Motion in the non‐crystalline regions of the samples is shown to be responsible for the T1 minimum occurring around −20°C. The dependence of T1 at the minimum on the long period reinforces the model of an amorphous fraction composed of disordered lamellar surface layers. The temperature of the T1 minimum and the dependence of T1 on the long period imply that the mobility of these amorphous regions is reduced in cold‐drawn and solution‐crystallized samples. This mobility irreversibly increases with annealing. In highly relaxed samples the motion of a small portion of the disordered regions is almost liquidlike, as indicated by the presence of a second shorter T1.
Spherulitic crystallization studies of poly(tetramethyl‐p‐silphenylene)–siloxane (TMPS). Part III
Authors: Magill J. H.
Published: April 2003

Extensive studies of the kinetics of spherulitic crystallization have been made on fractionated samples of TMPS. An analysis of these results reveals that a two‐dimensional growth rate mechanism is a more likely mode of growth than a three‐dimensional one. This conclusion is substantiated by experimental evidence from optical microscopy and light scattering from within spherulites. The crystallite end surface energy is found to increase as the molecular weight is raised.
Surface tension of polymer solutions. II. Poly‐isobutylenes in n‐heptane and tetralin
Authors: Gaines George L.
Published: April 2003

The surface tensions of solutions of polyisobutylene fluids in n‐heptane and tetralin have been measured at room temperature. The polyisobutylene samples studied range in molecular weight from 400 to 2800. The results conform closely to the predictions of equations previously developed from a simplified lattice theory calculation.
Polymer chain motion from viscosity and dielectric dispersion measurements
Authors: Bueche F. , Tokcan Güngüur
Published: April 2003

Shear viscosity and dielectric dispersion measurements have been made on a series of concentrated solutions of poly‐p‐chlorostyrene in toluene, chlorobenzene, and diethylbenzene, as well as on the pure polymer. It is found that the product ηνm/T is nearly temperature‐independent in the present range of measurement (30 ≤ νm ≤ 30 ≤ 104 Hz), where νm is the frequency at which the dielectric loss maximum occurs. For the pure polymer, ηνm (200/T) is 1011.5 poise/sec. This leads to a segmental jump distance of 5 Å. Although the results in this range correspond quite well to the concept of a segmental friction constant determined by the matrix viscosity, deviations appear as the apparent energy of activation for viscous flow decreases below 13 kcal/mole. There is reason to believe that these deviations reflect the increasing importance of bond rotation barriers at low matrix viscosity. It is speculated that the damped torsional oscillator interpretation of f0 proposed by Tobolsky will become valid in systems still more fluid.
Conformation of polyisobutylene in dilute solution subjected to a hydrodynamic shear field
Authors: Cottrell F. R. , Merrill E. W. , Smith K. A.
Published: April 2003

A new light‐scattering experiment which allows a direct determination of the conformation of macromolecules deformed in flow is described. Light‐scattering relationships based on the interference function are developed, and results of an experimental study are detailed. The deformed conformation of high molecular weight polyisobutylene was determined in a Couette‐type shear field. Decalin was the solvent. Variables investigated were the shear rate (0 to 600 sec−1), the polymer molecular weight (1.0 × 107 to 1.6 × 107), and the polymer concentration (2.0 × 10−4 to 8.0 × 10−4 g/cc). Conformation variables determined were the orientation of the molecule in the shear field and its maximum and minimum extension ratios in the plane defined by the direction of flow and the direction of the shear rate. The deformation of the macromolecule was found to be markedly discrepant when compared to the dynamic macromolecular models which assume complete coil flexibility, and more closely in agreement with the recent theories of Cerf, developed for nonfree‐draining coils which exhibit a finite internal viscosity.
Melting behavior and morphology of drawn nylon 6
Authors: Arakawa Tamio , Nagatoshi Fumio , Arai Naoki
Published: April 2003

Thermal analysis has been carried out on drawn nylon 6 filaments annealed at various temperatures between 150 and 210°C and then methoxymethylated to various degrees. It is shown that the melting point inherent to the morphology of drawn nylon 6 can be obtained from samples in which the reorganization of defect crystallites in the course of thermal analysis is prevented by a proper degree of methoxymethylation of amorphous regions. The melting point thus obtained is in linear relation with the reciprocal crystallite size in the direction of fiber axis which has been obtained from small‐angle x‐ray data and crystallinity. The extrapolation and the slope of this linear relation give the equilibrium melting point of nylon 6 as 245°C and an end‐surface free energy of 42 erg/cm2. The results seem to provide strong support for the presence of chain‐fold surfaces in the drawn and annealed polymers.
Thermodynamics of polyether solutions
Authors: Malcolm G. N. , Baird C. E. , Bruce G. R. , Cheyne K. G. , Kershaw R. W. , Pratt M. C.
Published: April 2003

Measurements are reported of the vapor pressures and the heats and volumes of mixing of solutions of poly(ethylene glycol dimethyl ether) in chloroform and in carbon tetrachloride. The measurements have been used to calculate the thermodynamic mixing functions for mixing with zero volume change. These values have been compared with the predictions of the lattice theory of mixtures at three different levels of approximation, viz., the generalized “first approximation” theory of Barker, the “zeroth approximation” theory, and the Flory theory. In the hydrogen‐bonding chloroform solutions the Barker theory is more successful than the other forms of the lattice theory. The results have also been used, in conjunction with those for solutions of poly(propylene glycol dimethyl ether) in the same two solvents, to test the ability of the Barker theory to correlate the properties of related systems. Good correlation is found between the two carbon tetrachloride solutions but not between the chloroform solutions. It is probable that the side‐chain methyl groups in the propylene oxide repeating unit cause the hydrogen‐bonding interaction to be weaker in this polymer than it is in the polymer with the ethylene oxide repeating unit.
Scattering of light from assemblies of oriented rods
Authors: Rhodes M. B. , Stein R. S.
Published: April 2003

The scattering patterns are calculated from anisotropic rods having an arbitrary angle of the polarizability axis with respect to the rod axis. The effect of a distribution of orientation of the rods is explored. This leads to a change in scattering patterns produced by orienting the rods upon stretching the sample. The scattering patterns are affected by the relationship between the refractive indexes of the rods and that of the surroundings. The influence of the optic axis orientation angle changing upon orienting the rods is explored. Theoretical patterns are compared with experimental ones obtained upon stretching polytetrafluoroethylene (PTFE) films.
Random attack model for polyethylene degradation
Authors: Ward I. M. , Williams T.
Published: April 2003

A comparison is made between the experimentally obtained molecular weight distributions of nitric acid‐oxidized polyethylene with a wide range of initial morphologies and the predictions of a random attack model. Deviations from the theoretical expectations are explained.
Volume recovery of glassy poly‐α‐methylstyrene
Authors: Endo Hiroshi , Fujimoto Teruo , Nagasawa Mitsuru
Published: April 2003

A method for evaluating the relaxation time as a function of both temperature and volume from volume contraction experiments, as proposed by Kovacs, was experimentally examined by using monodisperse poly‐α‐methylstyrene samples of various molecular weights and blends. It was concluded that his theory can be successfully applied to the present experimental data, though his two different approximations give somewhat different values of the shift factor for the time‐temperature superposition of volume contraction data. A difference was observed between the temperature dependence of the shift factor of monodisperse polymers and that of blends.
Vibrational analysis of molten poly(ethylene glycol)
Authors: Matsuura Hiroatsu , Miyazawa Tatsuo
Published: April 2003

The infrared absorption of poly(ethylene glycol) was measured in the molten state. Characteristic bands of the molten state were identified. Normal vibrations and frequency distributions were treated for various conformation models with CH2CH2O repeat units. The infrared absorption peaks of the molten state closely correspond to the frequency distribution peaks of the TGT conformation with gauche OCH2CH2O groups, although infrared bands due to trans OCH2CH2O groups are also observed. Vibrational assignments of the infrared bands and Raman lines were made on the basis of potential energy distributions.
Tensile yield‐stress behavior of poly(vinyl chloride) and polycarbonate in the glass transition region
Authors: Bauwens J. C. , Bauwens‐Crowet C. , Homès G.
Published: April 2003

The yield‐stress behavior of two glassy polymers is studied through the glass transition region over a wide range of strain rates. For temperatures below the glass transition temperature, the yield stress behavior could be described as a non‐Newtonian flow in agreement with Eyring's theory, if one excepts a narrow range relating to the slowest strain rates. For temperatures above Tg, the yield‐stress behavior is still nonlinear but fits the relations based on the concept of free volume.
A simple, sensitive graphical method of treating thermogravimetric analysis data
Authors: Broido A.
Published: April 2003

Thermogravimetric Analysis (TGA) is finding increasing utility in investigations of the pyrolysis and combustion behavior of materials. Although a theoretical treatment of the TGA behavior of an idealized reaction is relatively straight‐forward, major complications can be introduced when the reactions are complex, e.g., in the pyrolysis of cellulose, and when experimental imperfections arise. Consequently, a fairly large number of analytical methods have been proposed for obtaining kinetic parameters from TGA curves. Among the proposed methods are several graphical procedures, mostly involving relatively inaccurate tehniques, such as obtaining slopes on a rapidly changing curve. Included among the proposed procedures is one which permits a linear plot of TGA data. The sensitivity with which such a plot can be used to identify and correct for a variety of experimental complications seems to have escaped even the proponents of the techniques. This paper provides an illustration of the use of this graphical procedure in a hypothetical first‐order pyrolysis typical of those occurring in the TGA behavior of cellulose.
Effect of immobilizing adsorption on the diffusion time lag
Authors: Paul D. R.
Published: April 2003

A “dual sorption” model has been proposed by Michaels, Vieth, et al. to explain extensive equilibrium sorption data for several gases in some glassy polymers. To explain data on sorption kinetics, it was further postulated that one of the sorption modes immobilizes the gas molecules. Stated mathematically, this model leads to a modified form of Fick's second law. Both normal and desorption time lags for diffusion have been computed here for this model of diffusion in glassy polymers. The computed time lags are shown to be dependent on the boundary concentrations used in permeation. Experimental measurement of these time lags would be a sensitive and critical test to ascertain the validity of this theory.
GPC analysis of degraded annealed single crystals
Authors: Sadler D. M. , Williams T. , Keller A. , Ward I. M.
Published: April 2003

Annealed polyethylene single crystals have been degraded with fuming nitric acid, and the molecular weight distribution of the fragments determined by using a gel‐permeation chromatograph. Peaks due to chain folding were observed in these distributions as for unannealed single crystals. The peaks moved to lower molecular weight with increasing degradation time. Comparison of the lowest molecular weight peak length after a given degradation time with the low‐angle x‐ray periodicity before degradation gave information about a disordered surface layer. The thickness of this layer at early states of degradation was dependent solely on annealing temperature, though changes in the layer must have occurred with annealing time, since there was an increase in reaction rate with annealing time. At higher degradation states, the thickness of the layer was dependent solely on the original low‐angle periodicity. This has been related to the depth at which some folds are buried beneath the lamellar surfaces. The relevance of these observations to the structure of annealed single crystals is discussed.
Statistics of extreme values applied to the brittle fracture of poly(methyl methacrylate) containing polytetrafluoroethylene particles
Authors: Hansen K. E. , Forsman W. C.
Published: April 2003

Poly(methyl methacrylate) tensile bars were prepared containing nearly spherical polytetrafluoroethylene particles in concentrations from one to a thousand particles per gauge length of the bars. Particle diameters varied from 0.0035 to 0.018 in. Exhaustive tensile tests were performed at sufficiently high strain rate to assure brittle fracture and the results analyzed statistically by the theory of extreme values as proposed by Epstein. The results suggested that the polytetrafluoroethylene particles themselves did not act as flaws, but that they intensified the stress field on natural flaws which acted as the origin of fracture. Assuming a Laplace distribution as the underlying distribution of tensile strength (not to be confused with observed distribution of tensile strengths) gave predicted fracture statistics in good agreement with experiment.
Effect of molecular weight on the radial growth rates of polymer spherulites
Authors: Devoy C. , Mandelkern L.
Published: April 2003

Data existing in the literature for the spherulitic growth rate of molecular weight fractions of linear polyethylene, poly‐(tetramethyl‐p‐silphenylene)siloxane, and trans‐1,4‐polyisoprene have been analyzed according to nucleation theory on taking into account the influence of chain length on the free energy of fusion. All three polymers display very similar behavior in that the interfacial free energy reaches an asymptotic value at high molecular weights, decreases as the molecular weight is lowered, and appears to also reach an asymptotic value at low molecular weights. Although the changes in the interfacial energy with molecular weight are quite distinct, the relative change is much less than has been previously reported when a molecular crystal analysis is used. The same general behavior observed points out the dominating influence of the chain‐like character of the molecules in governing the growth rate.
Diffuse interphase layer in microheterogeneous polymer mixtures
Authors: Letz Ján
Published: April 2003

The thickness of the interphase layer as a function of time at 160°C has been determined directly in a microheterogeneous polymer mixture, and the layer thickness between two bonded sheets has also been measured by phase‐contrast microscopy. Two mixtures of polymers, isotatic polypropylene with polyethylene and poly(vinyl chloride) with polyethylene, were prepared by mixing size‐sorted powders in suspension, followed by evaporating the suspension medium and compacting the powdered mixtures. The mutual penetration initially obeyed Fick's second law; then diffusion was retarded and stopped after 15–20 min. An equilibrium state was reached which did not correspond to the classical thermodynamic equilibrium, at which the so‐called equilibrium thickness of the interphase layer for the pair isotactic polypropylene‐polyethylene was about 28,000 Å and for the pair poly(vinyl chloride)‐polyethylene was about 89,600 Å. The equilibrium values can be used as a quantitative criterion for the compatibility of the polymer pairs.
Polyimide solution properties
Authors: Wallach M. L.
Published: April 2003

Solution characterization measurements indicate that cylization of the polyamic acid from 2,4‐diaminoisopropylbenzene and pyromellitic dianhydride (PMDA) to the polyimide can be effected with small change in number‐average degree of polymerization. An increase in weight‐average molecular weight on conversion to polyimide is attributed to branching side reactions. Inherent viscosities of polyimides from 4,4′‐diaminodiphenyl ether and PMDA decreased slowly with time in concentrated (97%) sulfuric acid, probably as a result of hydrolytic cleavage. The zero‐time viscosity intercepts were related to both the precursor and the estimated polyimide molecular weight. The latter gave ηinh (c = 0.5% solids) = 2.76 × 10−3M̄0.53w for 60,000 < Mw < 300,000. The exponent is near the lower limit of 0.5 found in theta solvents. The characteristic ratio of the root‐mean‐square end‐to‐end distance of a chain to the square root of its molecular weight is 1.1 Å and the steric factor is 1.1; these results suggest that the unperturbed polyimide chain is almost as extended as an equivalent freely rotating chain, a general feature of long‐bonded polymers with p‐phenylene rings in the chain backbone.
General dynamic theory of macromolecular networks. I. Definitions and classification
Authors: Ziabicki Andrzej , Takserman‐Krozer R.
Published: April 2003

The problem of the structural theory of macromolecular networks is formulated and discussed in general terms. The conditions required for a system to become a homogeneous macromolecular network are defined and discussed. Networks are divided according to the nature of their junctions into three classes: energetic (with chemical or quasi‐chemical crosslinks), topological (with entangled chains), and contact (with frictional interactions). The main features of these three classes are discussed. A distribution density function ψ describing the configurations of macromolecules in network systems is introduced. The phase space of variables is 4(N + 1)‐dimensional and includes the coordinates of (N + 1) vectors hi joining the adjacent network junctions and (N + 1) contour lengths li of the network chains. The system of simultaneous equations required for the determination of the function ψ includes the equation of continuity, kinematic equations for the deformation velocity of the individual junctions, the force balance equation needed for the determination of sliding rates li, kinetic equations for the processes of junction breakage and reformation, and the equilibrium distribution of network junctions defining the initial conditions for the distribution function ψ.
Diffusion in glassy polymers. III
Authors: Wang T. T. , Kwei T. K. , Frisch H. L.
Published: April 2003

The diffusion studies of several solvents in epoxy polymer reported by Kewi and Zupko in Part I of this series are explained with the solution obtained from the generalized diffusion equation which includes the internal stress contribution. The rate of permeation of a penetrant through a polymer film and the time lag needed to reach steady state are also given for the generalized diffusion equation.
Gel‐permeation chromatography and cellulose. I. Effect of degree of nitration of cellulose on molecular weight distribution data
Authors: Segal Leon , Timpa J. D. , Wadsworth J. I.
Published: April 2003

Consideration is given to the effect on gel‐permeation chromatographic (GPC) data of the extent of substitution in nitrated cellulose. GPC parameters for samples containing 13.55–13.81% nitrogen (14.14% corresponds to complete substitution, DS = 3) were hardly affected by this variation in substitution. Variations that were observed are considered to arise within the samples themselves. Experiments with low molecular weight organic iodides, nitrates, and hydroxyl compounds indicate longer chain lengths than actual; this is attributed to extensive solvation of the substituent groups. The very long chain lengths obtained for cellulose nitrate by the present GPC procedure may arise from such an affect.
Molecular weight distributions in radiation‐induced polymerization. III. γ‐Ray‐induced polymerization of styrene at low temperatures
Authors: Huang Robert Y. M. , Westlake John F.
Published: April 2003

The kinetics of the γ‐radiation‐induced polymerization of styrene was studied at radiation intensities of 8 × 104, 2.4 × 105, 3.1 × 105, and 8.3 × 105 rad/hr over a temperature range of −10°C to 30°C. The water content of the irradiated samples varied from 1.0 × 10−3 to 7.5 × 10−3 mole/l. The power dependence of the rate of polymerization on the dose rate at −10°C varied from 0.53 to 0.71 as the water content of the sample varied from 7.5 × 10−3 to 1.0 × 10−3 mole/l. A value of 3.1 kcal/mole was determined for the overall activation energy. Molecular weight distribution studies by gel‐permeation chromatography indicated the presence of two distinct peaks. The contribution of each peak was dependent on specific experimental parameters. Kinetic data and molecular weight distribution data indicate the coexistence of two propagating species. Analysis of the data strongly suggests that a free‐radical mechanism and a cationic mechanism are involved.
Synthesis of a spirobenzothiazoline polymer and its thermal rearrangement to a polydihydrobenzothiazine
Authors: Augl J. M. , Wrasidlo W. J.
Published: April 2003

The reaction of 3,3′‐dimercaptobenzidine with 1,4‐cyclohexanedione leads to a soluble, high molecular weight, spirobenzothiazoline polymer. Above 200°C the spirolinks of this polymer rearrange into a ladder structure leading to a polydihydrobenzothiazine.
Reformulation of the general theory of ionic polymerization. II. Rate of change of degree of polymerization with time
Authors: Deleanu Th. , Dimonie M.
Published: April 2003

By means of the kinetic equations of polymerization some approximate relations were deduced by using the concomitant rate of change of intrinsic viscosity in many concrete cases. These relations were easy to handle and were sufficiently precise for direct calculation of the rate constants of polymerization.

A detailed mathematical study was carried out to improve the suggested approximations as well as the extension of these considerations.
Polymerization of vinyl monomers by alkali metal–thiobenzophenone complexes
Authors: Minoura Yuji , Tsubio Sadao
Published: April 2003

The polymerization of vinyl monomers by use of alkali metal (Li, Na, K)–thiobenzophenone complexes was studied. Monoalkali metal complexes of thiobenzophenone (thioketyls) induced the polymerization of vinyl monomers such as acrylonitrile (AN) and methyl methacrylate (MMA), and dialkali metal complexes of thiobenzophenone (dianion) induced the polymerization of styrene (St), butadiene (Bd), and isoprene (Ip) as well as AN and MMA. The polymerization of MMA with the dianion was initiated by both the mercaptide and the carbanion of the dianion, but that of styrene was initiated by the carbanion alone. In the case of polymerization of MMA by the thioketyl, the initial rate of polymerization depended on the catalyst concentration and the square of the monomer concentration. Similar results were obtained in the case of the dianion. The polymer yield increased with increasng polarity of sovents. In the copolymerization of AN with MMA, the copolymer obtained consisted almost of AN units. From these results, it was concluded that the polymerization proceeded by anionic mechanisms.
Kinetics of high‐intensity electron‐beam copolymerization of a divinyl urethane and 2‐hydroxyethyl methacrylate
Authors: Labana S. S.
Published: April 2003

The kinetics of the electron‐beam‐induced copolymerization of di(2′‐methacryloxyethyl)‐4‐methyl‐m‐phenylenediurethane (DVU) with 2‐hydroxyethyl methacrylate (HEMA) were studied. Monomer mixtures containing 1.96–82.8% DVU have been described at dose rates of 1.7–17 Mrad/sec with the use of 270‐kV electrons. Based on rates of conversion, gel formation, and intensity‐rate data, a kinetic scheme is proposed in accord with a model which undergoes unimolecular termination and for which the copolymerization and gel formation take place in a crosslinked network swollen with monomers. The rate of gel formation is: In[(1 + g)/(1 − M2g)] = A (1 + M2)t, where g is the gel fraction, M2 is the mole fraction of DVU in the monomer charge, and A is kpki/kt. Up to 55% conversion, the rate of disappearance of unsaturation for concentrated DVU solutions (M2 > 0.03) is: In[Mo/M(1 − M2g)] = A (1 + M2t), where M is the total unsaturation. For dilute solutions of DVU, the rate expression for pregel copolymerization simplifies to: In(Mo/M) = A (1 + M2)t. These results show that at a certain optimum concentration of monovinyl monomer—70% in the present system—both rapid reaction rates and complete copolymerization occur. Because of the inability of gel bonds to undergo polymerization, a limiting conversion is reached for copolymerizing mixtures containing insufficient monovinyl monomer.
Radiolysis of poly(vinyl chloride)
Authors: Salovey R. , Luongo J. P.
Published: April 2003

Allyl free‐radical intermediates are detected by ultraviolet absorption at 255 mu in poly(vinyl chloride) irradiated at −196°C and stored at 25°C. In vacuum at 25°C, allyl radicals are converted into polyenyl free radicals and polyenes. From the nature of allyl radical decay in vacuum, radical chain transfer between polyenyl radicals and poly(vinyl chloride) is inferred. Allyl and polyenyl free radicals are scavenged by oxygen on post‐irradiation storage in air.
Radiation chemistry of aqueous poly(ethylene oxide) solutions. I
Authors: King P. A. , Ward J. A.
Published: April 2003

The γ radiolysis of aqueous high molecular weight poly(ethylene oxide) solutions has been studied. The crosslinking and eventual gelation of these solutions appears to occur via an indirect effect. Solubility measurements on the gelled solutions showed that the ratio of crosslinking to degradation is about four. G(H2) increased from 1.3 in neutral solutions to 3.5 in 0.1N HCl solutions. In heavy water solutions, HD is the major gaseous product. Solvated electrons are not important precursors to hydrogen at neutral pH. Intramolecular crosslinking appears to be an important phenomenon in solutions of high molecular weight polymers.
Chain twisting in long‐chain aliphatic compounds and polyethylene
Authors: Welsh H. K.
Published: April 2003

Rate parameters for dielectric relaxation and the thermal properties of long‐chain molecular systems are shown to provide evidence for chain twisting at chain lengths shorter than previously suggested. Comparison of the temperatures of maximum absorption at 1 Hz for mechanical and dielectric relaxation suggests that the underlying motion is not the same for the two observed quanties. The evidence for relaxation in polyethylene is shown to be compatible with this suggestion.
Mechanism of cerium (IV) oxidation of glucose and cellulose
Authors: Pottenger Charles R. , Johnson Donald C.
Published: April 2003

Cerium (IV) oxidations of model compounds for the hydroxylic functional groups of cellulose were conducted in 1.0M perchloric acid. Glucose, the model selected for the reducing end group, was oxidized 360 times faster than Schardinger β‐dextrin, the model for anhydro‐D‐glucose repeating units. In the presence of a fourfold excess of glucose, stoichiometry indicated specific conversion to arabinose; the competitive oxidation of arabinose produced is insignificant. Specific C1–C2 bond cleavage was also indicated for 2‐O‐methyl‐D‐glucose, galactose, 2‐O‐methyl‐D‐galactose, and cellobiose. Anhydro‐D‐glucose units were oxidized predominantly by C2–C3 bond cleavage as shown by the identification of erythrose and glyoxal in hydrolyzates of cerium (IV) oxidized Schardinger β‐dextrin and cellulose. Kinetic studies showed that chelate complexes were involved in oxidations of glucose, methyl β‐D‐glucopyranoside, 1,5‐anhydro‐D‐glucitol, and Sahardinger β‐dextrin. The oxidations of glucose derivatives which differed with respect to substituents on C1 and C2 demonstrated the importance of the hemiacetal group and the presence of oxygen on C2. For example, the relative rates of oxidation at 15°C for methyl β‐D‐glucopyranoside, 1,5‐anhydro‐D‐glucitol, 2‐deoxy‐D‐glucose, glucose, and 2‐O‐methyl‐D‐glucose are 1:1:12:360:1860, respectively. The mechanism of glucose oxidation is thought to involve formation of a chelate complex, disproportionation of the complex to form a free radical at either C1 or C2 and further rapid oxidation to 4‐O‐formyl‐D‐arabinose which is hydrolyzed in the reaction medium. General implications of the experimental results pertaining to initiation of vinyl graft polymerization on cellulose are discussed.
Stereospecific polymerization of methacrylonitrile. IV. Polymerization by ate complex‐type catalysts
Authors: Joh Yasushi , Kurihara Seiki , Sakurai Toshio , Imai Yoshikatsu , Yoshihara Toshio , Tomita Tatsunori
Published: April 2003

Methacrylonitrile was polymerized by a number of ate‐complex catalysts. The catalysts used were NaAlR4, LiAlR4, LiZnR3, Li2ZnR4, RMg[AlR4], and Mg[AlR4]2. It was found that the ate‐complex catalysts in which one of the alkyls is replaced by a diphenylamino group are capable of producing polymers with higher degrees of crystallinity than those of polymers obtained by unmodified catalysts. It was shown that the diphenylamide linkage in these catalytic systems must play an important role in the steric control in the propagation steps of this type of polymerization, although the mechanism is not clear at present. The crystallinity index used in this research gave a linear relation against I measured by NMR, and can be used as a measure of the stereo‐regularity of the polymer.
Radiation‐induced postpolymerization of nitroethylene
Authors: Yamaoka Hitoshi , Obama Isamu , Hayashi Koichiro , Okamura Seizo
Published: April 2003

Radiation‐induced postpolymerization of nitroethylene in 2‐methyltetrahydrofuran glass has been studied and discussed in reference to the results obtained from ESR measurements. No postpolymerization occurred at the temperature below −150°C. In the temperature range between −135°C and −78°C, the polymer yield decreased with increasing postpolymerization temperature. The polymer yield increased linearly with the increase of the preirradiation dose in the range below 0.9 × 106 r. The mean value for chain initiation was estimated to be about 1.3. The following correlations were observed between the results of the postpolymerization and ESR measurements. The postpolymerization started in the temperature range between −140°C and −135°C, where the ESR spectrum due to the anion radicals of nitroethylene disappeared. The polymer yield of the postpolymerization decreased with the photoirradiation at −196°C before warming the samples in parallel with the photobleachability of the anion radicals observed in the glassy mixture by the ESR method. It was concluded from these results that the radiation‐induced postpolymerization was initiated by the anion radicals of nitroethylene formed by the capture of electons.
Studies in cyclocopolymerization. V. Further evidence for charge‐transfer complexes in cyclocopolymerization
Authors: Butler George B. , Campus Alfred F.
Published: April 2003

Previous work from this laboratory has shown that certain 1,4‐dienes which readily undergo cyclocopolymerization with certain alkenes also form charge‐transfer complexes with the same alkenes. The results observed and the proposed cyclocopolymerization mechanism are consistent with participation of the charge‐transfer complex as a distinct species in the copolymerization. It was the purpose of this investigation to determine whether there was a dilution effect on the relative reactivities of the monomers in support of the charge‐transfer participation concept, and whether the results of a suitable terpolymerization study would also support this postulate. In the divinyl ether–fumaronitrile system, the maximum rate of copolymerization occurred at a monomer feed ratio of 1:2 and the composition of the copolymer was also 1:2 at a total monomer concentration of 3 mole/l. However, when the concentration was progressively lowered to 0.5 mole/l. at the same monomer feed ratio, the fumaronitrile content of the copolymer decreased in a linear manner. In a series of terpolymerization experiments with the divinyl ether–maleic anhydride–acrylonitrile system, it was shown that the divinyl ether–maleic anhydride ratio in the terpolymer was always less than 1:1 and had an upper limit of 1:2, regardless of the feed ratio of the termonomers. These results are consistent with the participation of the charge‐transfer complex of divinyl ether and maleic anhydride in a copolymerization process with either maleic anhydride or acrylonitrile as the comonomer.
Cationic polymerization of α‐methylstyrene oxide
Authors: Pasika Wallace M. , Chen Shu‐Pin
Published: April 2003

The polymerization of α‐Methyl Styrene Oxide initiated by trityl hexachloroantimonate is reported upon. Data is presented on side reactions, percent yield and molecular weight of polymer produced in the polymerization.
Electron spin resonance study of poly‐3,3‐bis(chloromethyl) oxetane irradiated with electron beams and ultraviolet light
Authors: Tsuji Kozo , Hayashi Koichiro , Okamura Seizo
Published: April 2003

Poly‐3,3‐bis(chloromethyl)oxetane (poly‐BCMO) was irradiated at −196°C with electron beams and ultraviolet light, and observed ESR spectra were compared. A three‐line spectrum (coupling constant of about 21 gauss) and a two‐line spectrum (coupling constant of about 18 gauss) were observed after irradiation with electron beams in vacuo. They were attributed to free radicals and respectively. On the other hand, a three‐line spectrum (coupling constant of about 20 gauss) and an asymmetric singlet spectrum were observed after ultraviolet irradiation in vacuum. They were assigned to free radicals and CH2O·, respectively. Mechanisms of radical formation were discussed in each case. When poly‐BCMO was irradiated with electron beams at −196°C in the presence of air, peroxy radicals were produced after subsequent treatment at −78°C. The reaction between alkyl radicals and oxygen molecules was found to be diffusion‐controlled.
Polymerization of vinylcyclopropanes. IV. Radical copolymerization of 1,1‐dichloro‐2‐vinylcyclopropane with maleic anhydride
Authors: Takahashi Takako
Published: April 2003

Radical copolymerization between 1,1‐dichloro‐2‐vinylcyclopropane (M1) and maleic anhydride (M2) was studied. Rearrangement of the radical caused from monomer M1 and cyclization of growing chain, which was suggested from a consideration of composition and structure of the obtained copolymer, complicate the propagation step in this system. A peculiar copolymer composition equation containing four reactivity ratio parameters was developed, and these parameters were determined.
Electron spin resonance studies of polycarbonate irradiated by γ‐rays and ultraviolet light
Authors: Hama Yoshimasa , Shinohara Kenichi
Published: April 2003

Paramagnetic species produced in polycarbonate (PC) by γ‐ or ultraviolet irradiation were investigated by ESR. In γ‐irradiation, scissions of carbonate groups in the main chain occur. ESR spectra (g = 2.0034) composed of a sharp singlet, some broad singlets, and a small signal with hyperfine structure are obtained, and they are assigned to trapped electrons, positive radical ions, phenoxy‐type free radicals, phenyl radicals, and OC6H4C(CH3)2 radicals. The G value for total yields of paramagnetic species at 77°K is 1.8. The percentage of CO and CO2, the dominant gases evolved, is 65.4 and 33.8%, respectively. In ultraviolet irradiation, energy is absorbed selectively at the surface region. The surface region becomes insoluble in methylene chloride because of crosslinking of phenyl groups. The ESR spectrum obtained at 77°K is a broad singlet and assigned to phenoxy‐type free radicals, phenyl radicals, and polyenyl‐type free radicals. Some differences in effects of γ‐ and ultraviolet irradiation of PC are discussed.
NMR study of poly(vinyl chloride)‐β,β‐d2
Authors: Cavalli L. , Borsini G. C. , Carraro G. , Confalonieri G.
Published: April 2003

The high‐resolution NMR spectra at 60 and 100 Mcps of poly(vinyl chloride)‐β,β‐d2 in o‐dichlorobenzene, pyridine, and C2HCl5 solutions are reported. The use of low molecular weight samples and of {D} spin‐decoupling experiments, which yield higher resolution spectra, results in the observation of a number of additional resonances for the α‐proton. These can be interpreted in terms of pentad configurational sequences of monomer units. It is found that, whereas the S syndiotactic pentads cannot be resolved, two components of the H heterotactic and all of the possible I isotactic pentads are clearly discernible. From the tacticity values of polymers prepared at +40, 0, and −40°C, enthalpy and entropy of activation for isotactic and syndiotactic monomer placement are found to be 630 cal/mole and 1.5 eu, respectively.
Crosslinking, filler, or transition constraint of polymer networks. II
Authors: Blanchard A. F.
Published: April 2003

The theory of Part I is developed by application to filler reinforcement of NR and SBR. For unswollen but prestretched networks it quantifies entire stress–strain curves and applies new concepts of extensibility and strain hardening. Constraint of swelling is expressed by a constant φ, termed linkage reinforcement, and by an effective hard fraction Ch per cubic centimeter of compound. For rubber–filler swelling vc the modified Flory functions F(vc) in part 1 need 3% correction. Then, relative to gum fix points 1/F0(vr):

where Ch ≤ 1.15C for filler concentrations C per cubic centimeter of compound. The effective Ch comprises the volume fraction C* of bonded particles and 5–10 Å of surface–bound rubber that has been stretched hard by swelling. When needed, the actual crosslink density and intrinsic linkage reinforcement φ0 can be obtained by dividing by (1 + 2.5Cφ) where Cφ = (C ln φ)/(1 + 2.5C). The case Ch ≤ 1.15C with Graphon or inert fillers is identified and assessed by equations:

Results Ch > 1.15C are invalid, but then Ch ≈ 1.15C* ≈ 1.15C, e.g., for carbon blacks. Even Graphon is distinguished from inert fillers at low concentrations C by substantial constraint reinforcement F0(vr)/F(vc) > 1. For prestressed dry rubber a modulus G, network extensibility αb − 1, and upturn coefficient μh express the whole curve; G and μh show identical constraint strength distributions. Network extensibility αb − 1 is the microbreaking strain (prestretch); for pure elastomer it is elongation at break. The relation of stress F to extension ratio α is:

where C2* = 0.7 and j = 0.4 from NR/MPC data. Strain‐hardening coefficients h are obtained from μh by the theory given in Part I. Hard modulus components Gh = 0.7 ln (h/h0) vanish as h → h0 (gum) = 110. After high prestresses the residual ln‐(h*/h0) due to strong carbon‐rubber linkages implies Gh* = 0.42 kg/cm2, i.e., ca. 10% of the normal cure crosslinks.
Studies on monomer reactivity ratios. I. An electronegativity model
Authors: Hoyland James R.
Published: April 2003

A model based on an electronegativity scheme is proposed for treatment of monomer reactivity ratios in free‐radical bulk copolymerization. Values for each monomer are assigned to three parameters: a relative localization (or resonance stabilization) energy, a radical electronegativity, and a monomer electronegativity. Parameters for 17 monomers are given and calculated reactivity ratios are tabulated for a large number of copolymerizations. Agreement with experiment is usually obtained to within experimental error except for systems involving acrylonitrile. Computed parameters are rationalized on the basis of molecular orbital theory.
Absorption and fluorescence of a nonionic detergent in aqueous solution
Authors: Ikeda Shoichi , Fasman Gerald D.
Published: April 2003

The absorption and fluorescence spectra of a detergent, polyoxyethylene octylphenyl ether, were measured in water at different concentrations. The absorption spectra had a peak at 275 mμ and a shoulder at 281 mμ. The spectra were independent of concentration below the critical micelle concentration, but the molar extinction coefficients of the peak and the shoulder increased with concentration above the critical micelle concentration. The critical micelle concentration value derived from the absorption data was in good agreement with those obtained by other methods. The fluorescence spectra of the detergent in water were independent of concentration in dilute solutions, if the intensities of the spectra were normalized at the peak at 302 mμ. At higher concentrations, a weak excimer band appeared at 345 mμ, whose intensity increased with concentration. The excimer band manifested itself at a concentration slightly lower than the critical micelle concentration. The main band decreased and the excimer band increased, as the temperature was raised. An excimer band was observed in the same region of the spectra for the pure detergent, either in the solid or liquid state. The equilibrium solid spectra exhibited a very strong excimer emission. It was concluded that the excimers were formed within micelles in the case of aqueous solutions.
A particle growth theory for heterogeneous Ziegler polymerization
Authors: Buls V. W. , Higgins T. L.
Published: April 2003

Samples of “as produced” polypropylene particles at progressively higher yield levels (grams polymer/gram catalyst) were sliced and examined by electron microscopy. In the polymerization of propylene with the TiCl3–(C2H5)2AlCl catalyst system the catalyst breaks up immediately into basic 100–1000 Å particles. As the yield increases, the catalyst particles gradually disappear and finally become completely dispersed in the polymer particle. These results are compatible with a theory which views the catalyst as a porous crystal containing a single species of active sites uniformly distributed. As polymerization progresses, all sites should eventually initiate a polymer chain whose length should be inversely proportional to the depth of the site below the surface of the particle. Two apparently equivalent statistical models were developed on the basis of this concept. Both models predict a slow increase in the X̄w/X̄n ration (Q) with increasing molecular weight, after an initial rapid increase. The most useful of these models states that Q is equal to the sum of X̄w terms of the simple harmonic series, and that a complete spectrum of x‐mers should be present in the product. This agrees satisfactorily with analytically determined values.
Graft copolymerization to cellulose by the metallic ion–hydrogen peroxide initiator system
Authors: Ogiwara Yoshitaka , Kubota Hitoshi
Published: April 2003

The decomposition of hydrogen peroxide and the graft copolymerization of methyl methacrylate has been investigated by use of cellulose samples adsorbing various metallicions. Metallic ions generally accelerate the decomposition of hydrogen peroxide, increase the number of grafts, and lower the average molecular weight. However their effects are much influenced by the range of pH values. It is clear that the amount of grafts formed is not necessarily proportional to the amount of decomposed hydrogen peroxide and is dependent upon a function peculiar to each metallic ion. The effective metallic ions in the neutral system were Cu2+, Ag+, Fe2+, Co2+, Cr3+, and Zn2+. The effects of Ce3+, Mg2+, Hg3+, Cd2+, Ni2+ and Mn2+ were either negligible or negative. Comparative studies on various conditions confirmed that Fe2+ in the neutral system gives graft copolymer having a minimum average molecular weight and the greatest number of grafts.