bluuebunny/crossref_metadata_2025 huggingface dataset:
Polypropylene oxidation kinetics
Authors: Goldfarb Louis , Foltz Carl R. , Messersmith David C.
Published: April 2003

Differential thermal analysis methods have been used to investigate the kinetics of oxidation of isotactic polypropylene. The interpretation of results is based on an oxidation mechanism that emphasizes the role of hydroperoxide production. The mechanism has been simulated by computer methods, and the rate constants for the abstraction of labile hydrogen atoms as well as an apparent energy of activation are obtained.
Preparation and polymerization of 3‐acrylamido‐3‐methylbutanoic acid
Authors: Hoke Donald I. , Robins Richard D.
Published: April 2003

The preparation of 3‐acrylamido‐3‐methylbutanoic acid by a haloform reaction on diacetone acrylamide and by a Ritter reaction between acrylonitrile and β,β‐dimethylacrylic acid is reported. The properties of this crystalline monomer and its homopolymer are also reported.
Sulfur‐containing polymers. VI. Preparation of poly[alkylene bis(oxycarbonyl) disulfides] and related polymers
Authors: Kobayashi Norio , Fujisawa Tamotsu
Published: April 2003

Poly[alkylene bis(oxycarbonyl) disulfides] have been prepared for the first time by the reductive coupling of alkylene bis(oxycarbonylsulfenyl chlorides). Potassium iodide and a variety of transition metals or their salts were employed as reducing agents. Of these potassium iodide and cuprous chloride gave the best results. Pyrolysis, desulfurization. and thiol‐induced fragmentation of the polymers have been studied. Homologous polymers, i.e., monosulfide polymer, trisulfide polymer, and tetrasulfide polymer, have been also synthesized. Monosulfide and disulfide polymers were highly crystalline solids. Trisulfide polymer was a white solid with a low degree of crystallinity. These polymers were soluble in chloroform and dichloromethane. Tetrasulfide polymer was a crystalline yellow solid and was soluble only in HMPA.
Polymer effect on electron‐donating character of polymeric donor. I. Formation of charge‐transfer complex between polymers containing N,N‐dimethylaniline group and maleic anhydride
Authors: Iwatsuki Shouji , Arai Kiyotaka
Published: April 2003

The difference in electron‐donating character between polymeric and monomeric donors in their charge‐transfer‐complex formation reactions was studied to clarify the so‐called polymer effect in such reactions. Systems containing maleic anhydride and copolymers of N,N‐dimethyl‐p‐aminostyrene (ASt) with styrene, which were prepared by a conventional free‐radical polymerization technique, were found to be suitable for this purpose. In correlations between the mean sequence length μASt of the ASt units in the copolymers and the lowest energy of their charge‐transfer transition (λmax) or the association constant of their complex formation KCT, a bathochromic shift in λmax and an increase in KCT with increasing μASt of copolymers are found. Moreover, there is a difference in their modes of μASt dependence. It was concluded from these results that the electron‐donating character of the dimethylaniline group increases with increasing number of groups attached on one polymer chain. Also, there is an interaction among neighboring functional groups on one polymer chain. The interaction may be regarded as a kind of polymer effect. In addition, the difference in μASt dependence between λmax and KCT and also thermodynamics of the complex formation are discussed.
Side‐chain crystallinity. V. Heats of fusion and melting temperatures on monomers whose homopolymers have long side chains
Authors: Jordan Edmund F.
Published: April 2003

Heats of fusion and melting temperatures were obtained for selected monomeric n‐alkyl acrylates, N‐n‐alkylacrylamides, and vinyl esters. The corresponding thermodynamic parameters for homopolymers, derived from these monomers, had been reported previously from this laboratory. The α‐hexagonal crystal modification was indicated near the melting point for the higher n‐alkyl acrylates, but a β form was stable at low temperatures for the entire series. The magnitude of the heats of fusion indicated β polymorphs for vinyl esters in support of x‐ray diffraction analysis from the literature. Because hexagonal crystal geometry prevailed in all reported homopolymers having long side chains, greater emphasis was placed on thermodynamic data for monomers exhibiting this crystal modification. Accordingly, a convergence temperature was estimated statistically for the α‐hexagonal crystal modification of these systems and appropriate literature values of the n‐alkanes and ethyl esters. The convergence temperature was computed to be 135°C, uncorrected for the entropy of disorientation. The anomalously large interfacial end‐packing‐defect energy of the poly(n‐alkyl acrylates) and the poly‐N‐n‐alkylacrylamides was shown to be associated with a high energy barrier to molecular transport in the melt as the vitreous state was approached. In support of this conclusion, similarity of the glass and melting transition temperatures of these homopolymer homologs occurred near their critical side‐chain lengths, below which the homopolymers are amorphous. A special critical requirement of nucleus length was not indicated from rough estimations of nucleation parameters for the poly(n‐alkyl acrylates). These findings lent increased, but still not unqualified, support to an x‐ray diffraction study from the literature. The latter had specified the inclusion of the entire side chain and the main‐chain units in the crystal lattices of the higher poly(n‐alkyl acrylates).
Self‐regulating polycondensations. IV. Ordered oxadiazole‐imide copolymers
Authors: Preston J.
Published: April 2003

Ordered oxadiazole‐imide copolymers are prepared from simple aminobenzhydrazide monomers by a step‐wise reaction which begins with the condensation of a diacid chloride to produce in situ a diamine containing hydrazide linkages. The in situ diamine is then reacted with a dianhydride to yield an ordered hydrazide‐amic‐acid copolymer; this precursor is converted by heating to the ordered heterocycle copolymer. Polymers prepared via this manner are identical in properties to those obtained by the reaction of a dianhydride with a diamine containing hydrazide linkages preformed by a straight forward synthesis from a dinitro precursor. Fibers spun from the soluble precursor polymers were converted via cyclodehydration to thermally stable fibers. Another polyoxadiazole‐imide was produced in similar fashion; e.g., an aminobenzhydrazide was reacted with the acid chloride of trimellitic anhydride to yield an in situ AB monomer which was polymerized to yield a precursor polyhydrazide‐amic‐acid, which in turn was converted by cyclodehydration to an AB type polyoxadiazole‐imide. Additional examples are cited of the formation of polymers from the in situ intermediates produced by the “self‐regulating” reaction of aminobenzhydrazides with acid chlorides followed by polycondensation with difunctional monomers.
Poly[bis(phosphinatoalanyl)phosphonates]
Authors: Flagg Edward E. , Schmidt Donald L.
Published: April 2003

A series of coordination polymers, poly[bis(phosphinatoalanyl)phosphonates], [X(Y)AlOP(R)(O)OAl(Y′)(X′)]n, were synthesized in which the terminal alanyl substituents (X,Y,X,′Y′) consisted of phosphinato (OPRR′O) or fluoro (F) moieties. The properties of the polymers were primarily dependent upon the type of terminal substituent and the hydrocarbon moieties (R,R′) on phosphorus. Polymers with four phosphinato moieties gave molecular weights M̄n to 120000 with intrinsic viscosities [η] from 1.5 to 18; the corresponding solids were partially crystalline, melted before decomposition, and were film‐forming when larger phosphorus substituents were incorporated. Sequential replacement of the phosphinato moieties with fluorine resulted in molecular weights below 10000 and low viscosities. The properties of the polymers are examined, and the roles of substituents on probable structures are discussed.
Polymerization of butadiene initiated by the 1:1 chelate of n‐butyllithium and N,N,N′,N′‐tetramethylethylenediamine
Authors: Hay J. N. , McCabe J. F.
Published: April 2003

Evidence is given for the species involved in the initiation and propagation steps in the polymerization of butadiene with n‐butyl lithium: tetramethylethylene diamine (TMEDA) as being the monomeric butyl lithium and the solvated ion pair, (A),
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respectively. Species A is also produced on the metalation of polybutadiene with butyl lithium: TMEDA.
Reaction of propylene sulfide with nitrogen‐containing polymers
Authors: Lautenschlaeger F. , Zeeman P.
Published: April 2003

A convenient route for the introduction of mercaptan groups into nitrogen‐containing polymers is provided by addition of propylene sulfide to such polymers. The reaction with polyethylenimine, Versamid 140, and nylon 11 was investigated. In contrast to the reaction of polyethylenimine with propylene oxide, only limited initiation of the grafting reaction on the polymeric amine is achieved, as evidenced by a low mercaptan functionality of the grafted products.
Thermal and autoxidation reactions of poly‐3‐methylenecyclobutene and poly‐1‐methyl‐3‐methylenecyclobutene
Authors: Wu Charles C. , Lenz Robert W.
Published: April 2003

The thermal ring‐opening reactions, autoxidation and hydrogenation of polymethy‐lenecyclobutene (PMCB) and poly‐1‐methyl‐3‐methylenecyclobutene (PMMCB), were investigated. Both polymers were prepared by cationic polymerization and consisted almost entirely of 1,5‐repeating units containing cyclobutene rings in the polymer backbone. Both polymers showed well behaved exothermic processes at elevated temperatures which apparently resulted in crosslinking. These processes were investigated by differential scanning calorimetry and interpreted to involve thermal ring‐opening reactions. Autoxidation occurred very rapidly in PMCB but much more slowly in PMMCB as predicted by Bolland's rules. Attempts to hydrogenate the cyclobutene rings in both polymers resulted in the occurrence of hydrogenolysis in PMCB and little or no reaction with PMMCB for a Pd‐catalyzed reaction and partial hydrogenation of the latter for a diimide reaction.
Block copolymerization. V. Block anionic polymerization of lactams
Authors: Yamashita Yuya , Matsui Hisashi , Ito Koichi
Published: April 2003

Bischloroformates of hydroxy‐terminated poly(tetramethylene glycol) (PTG) and polystyrene (PSt) were prepared and used as the initiators for the anionic polymerization of α‐pyrrolidone and ε‐caprolactam in bulk at 30°C and 80°C, respectively. Initiation efficiency was sufficiently high to give well‐defined nylon–PTG(or PSt)–nylon block copolymers. Both the yield and the viscosity of the block copolymer increased with polymerization time up to 50% conversion of the lactam.
γ‐Irradiation of polystyrene emulsions
Authors: Rudin Alfred , Chau T. C.
Published: April 2003

Aqueous polystyrene emulsions were subjected to γ‐irradiation at 30°C and 0.6 Mrad/hr dose rate. Analogy with water‐soluble systems suggests that such conditions might suppress chain scission and favor crosslinking. The (extrapolated) infinite‐dose gel content and gel‐permeation analysis of the polymer in the pre‐gel region indicate that the extent of chain scission was negligible. The G (crosslink) value obtained from the dose for incipient gelation and molecular weight variations in the pre‐gel region is 0.051. Charlesby‐Pinner plots were linear, but linearity cannot be construed as indicating that chain scission has produced an effective random molecular weight distribution. Our results are consistent with the conclusions that crosslinking events are random and directly proportional to dose. The probability that a given crosslink is effective in increasing the gel content decreases with dose past the incipient gel point, however, because of cyclization on preformed gel. The crosslink density/dose ratio is a decreasing function of dose in this range. Attempts to predict dose–gel relations with assumptions of various initial molecular weight distributions were unsuccessful, possibly because of the neglected influence of cyclization on the measured gel content.
Computer simulation for the cooligomerization system
Authors: Tsuchida Eishun , Mishima Kunio , Kitamura Kiwamu , Shinohara Isao , Mimashi Setsuo
Published: April 2003

In order to clarify the kinetic features of the styrene (A)–methyl methacrylate (B)–CCl4(S) cooligomerization system, a computer simulation was carried out. The experimental data on the degree of polymerization and the deviation of the cooligomer composition from the statistical steady‐state composition were comparatively well explained by calculations based on the kinetic equations derived from the assumed reaction scheme and the values of the velocity coefficients, although the values of the four velocity coefficients in the initiation step and the velocity coefficient of the termination by the coupling of two solvent radicals were estimated. The results of the calculation of the rate of each component reaction show that the following two reactions are the most important in the initiation and in the transfer and termination steps when the [S]/([A] + [B]) ratio is large:

where, A, A*, and P are styrene, polystyryl radical, and the cooligomer, respectively. Moreover, it was concluded that the deviation of the cooligomer composition from the statistical steady‐state composition was caused by these two reactions.
Simplified treatment of cooligomerization kinetics
Authors: Tsuchida Eishun , Kitamura Kiwamu , Shinohara Isao
Published: April 2003

Equations for the degree of polymerization and the cooligomer composition in the styrene (A)–methyl methacrylate (B)–CCl4(S) system were derived from the assumed reaction scheme by the use of some assumptions for simplification, and their appropriateness was examined. The chain transfer constants of the growing radicals of styrene (CSA) and methyl methacrylate (CSB) to CCl4, which were estimated from the apparent chain transfer constants CSAB in the cooligomerization system, agreed with the homooligomerization values. This means that the degree of the polymerization of the cooligomer can be expressed by the equation:

where Pn is the degree of polymerization of the cooligomer and PnO is that when no chain transfer agent (CCl4) is added; rA and rB are the monomer reactivity ratios of monomers A and B in this system. The cooligomer composition deviated from the statistical steady‐state composition on the low molecular weight side, and this deviation was explained by the equation:
Effect of molecular weight on conformation of poly(β‐benzyl L‐aspartate) in films
Authors: Kyotani Hiroko , Kanetsuna Hisaaki
Published: April 2003

In order to study the effect of the molecular weight on the crystallinity and conformational changes of poly(β‐benzyl L aspartate) in films, a previous study on high molecular weight samples has been extended to included polymers of low molecular weight, about 3.3 × 103. Films were prepared from chloroform solution by quick or slow evaporation at room temperature. The conformation and the thermal behavior were studied by means of infrared spectroscopy and differential scanning calorimetry. All films dried quickly are composed of polymer in the left‐handed α‐helical form. All samples studied which have molecular weights above 2.3 × 104 are similar in crystallinity and the left‐handed α‐helices in them crystallize to ω‐helices during slow evaporation. In the low molecular weight region, however, the left‐handed α‐helices reverse to right‐handed α‐helices during slow evaporation, and the right‐handed α‐helices, in turn, reverse and crystallize to highly ordered ω‐helices upon heat treatment, although there is some simultaneous conversion to the β‐form. The transition temperatures of the quick‐dried films for conversion from the left‐handed α‐helix to the ω‐helix and from the ω‐helix to the β‐form increase linearly with increasing molecular weight up to about 2 × 104, but no large molecular weight dependence is observed beyond that region.
Breakdown of equivalent‐model theory in nonisothermal relaxation
Authors: Gross Bernhard
Published: April 2003

The behavior of Maxwell and of Wagner models with temperature‐dependent elements is discussed. It is shown that these models can not be equivalent under nonisothermal conditions. It follows that the theory of equivalence of models does not apply to temperature‐induced transients.
Thermoluminescence and thermally stimulated conductivity in polymers
Authors: Ranicar J. H. , Fleming R. J.
Published: April 2003

Thermoluminescence (TL) and thermally stimulated conductivity (TSC) glow curves in poly(vinyl chloride), polyethylene, polystyrene, polytetrafluoroethylene, and polyimide have been compared, and many similarities have been observed. Comparison with available NMR, dynamic mechanical loss, and dielectric loss, molecular mobility data shows that most TL and TSC peaks occur at temperatures similar to those assigned to the onset of specific molecular motions, suggesting that the peaks are due to the liberation of electrons from traps formed by the polymer chains themselves, e.g., potential wells or cavities due to chain entanglement in amorphous regions, or main‐chain branching points. Peaks for which correlation with molecular motion is not apparent are tentatively assigned to liberation of electrons from traps centered on impurities. The TSC peak temperatures in PVC were not affected in any consistent fashion by the application of high‐strength electric fields during the warming process, indicating that the electron traps are electrically neutral when empty and charged when filled; the direction of the TSC currents appears to be determined by temperature gradients existing within the samples. The TL glow‐curves are generally in good agreement with the results of other workers. The dark dc conductivity of PVC not exposed to ionizing radiation rises sharply in the temperature region assigned to the β‐relaxation process, suggesting that the electron mobility in that polymer is dominated by molecular chain motion, i.e., the interchain charge transport process is probably best described in terms of a hopping process.
Surface tension of polymers with long unbranched side chains
Authors: Schwarcz Andor , Farinato R. S.
Published: April 2003

The surface tension of polymers having long unbranched side chains was measured by a contact‐angle technique. It ranges between 20–29 dynes/cm and is almost entirely due to dispersion forces. At the lower end of this range the side chains are attached to every other carbon atom of the main chain and the structure is characterized by extended alkyl side chains at right angles to the main chain with methyl groups forming the interface. As the spacing frequency of the side chains increases and the main chain becomes the site of other bulky groups, this structure becomes less ordered and the surface tension increases to the high twenties. The same effect, to a lesser extent, is observed when the length of the side chains is gradually diminished to 12 carbon atoms from 21. A sudden increase of the polar force contribution of the surface tension at 10–12 carbon atoms indicates collapse of the ordered side‐chain structure.
Broad‐line NMR of aromatic polyamides
Authors: Woodward A. E. , Landis J. , Frosini V.
Published: April 2003

Broad‐line NMR spectra have been obtained at 90 MHz in the temperature region 140–530°K for four aromatic polyamides: poly(1,3‐phenylene isophthalamide), poly(1,4‐phenylene terephthalamide), poly(4,4,‐diphenylene terephthalamide), and poly(4,4,‐diphenylene isophthalamide). For the latter three materials, a broad‐line narrowing process occurs in the 210–370°K region. At temperatures above 340°K a complex line shape is observed for all samples. Possible causes of these processes are discussed, and comparison made with dynamic mechanical results.
Effect of domain morphology of butadiene—styrene block copolymers on viscoelastic properties and in tension shear
Authors: Kraus Gerard , Rollmann K. W. , Gardner J. O.
Published: April 2003

Dynamic viscoelastic properties of S—B—S block copolymers were measured in the tensile and shear deformation modes. Between the glass transitions of the polybutadiene and polystyrene domains the ratio of storage moduli E'/G' in tension and in shear for the same polymer varied from 3 to more than 30, depending on sample preparation. For films cast from good solvents this ratio was near 3; large ratios resulted from deposition from poor polybutadiene solvents or from compression molding. Above the polystyrene glass transition, E'/G' approached 3 for all samples. The effect is ascribed to various degrees of polystyrene domain connectivity. Electron micrographs confirm this interpretation. For morphologies of high polystyrene domain connectivity, the loss tangent in tension is heavily weighted by mechanical losses in the polystyrene phase; the loss tangent in shear is affected only moderately by differences in domain morphology.
Aging of quenched polypropylene
Authors: Kapur Sudhir , Rogers C. E.
Published: April 2003

Structural changes occurring during the aging of polypropylene quenched from the melt have been investigated by measurements of gas transport parameters and mechanical properties. Major changes in diffusion and sorption behavior during the first 30 hr of aging at room temperature were found to be strongly dependent on the atomic size of the inert gas penetrants. Tensile mechanical properties increased with aging time, while resilience and mechanical damping showed more complex behavior. The interpretation of the combined results suggests that the aging process may involve molecular rearrangements generally comparable to those for secondary crystallization processes, but within domains comparable in size to that of the smaller penetrant species. The relaxation of a residual stress distribution related to nonuniform plastic flow during quenching may be superimposed on the rearrangement phenomena.
Molecular reorientation in polypropylene
Authors: Duckett R. A. , Goswami B. C. , Ward I. M.
Published: April 2003

The molecular reorientation occurring within deformation bands in one‐way drawn polypropylene films has been studied by optical microscopy. The deformation bands formed at the yield stress in tension tests on specimens cut at various angles to the initial drawing direction. It is shown that the principal axes of the refractive index ellipsoid in the deformation band coincide with the principal axes of the plastic strain ellipsoid, provided that the strains are referred to the initial isotropic state, i.e., prior to the initial drawing process. This result is similar to the results obtained previously for poly(ethylene terephthalate), but differes somewhat from the results obtained by other workers for poly(vinyl chloride). A possible reason for these differences is discussed.
Polymerization in catalyst particles: Calculation of molecular weight distribution
Authors: Schmeal W. R. , Street J. R.
Published: April 2003

Factors which affect and broaden molecular weight distributions are investigated for polymerizations in catalyst particles which are accumulating polymer, such as Ziegler polymerizations of olefins. Expressions for the Q value, or ratio of weight‐average to number‐average molecular weight, are derived for simple, but important linear models. These expressions are of the form Q = FSX for a kinetic scheme in which polymer chains have an infinite growing lifetime, and Q = 2FGSX for a kinetic scheme in which termination by hydrogen is dominant and each site produces many chains. The factors F, G, S, and X are equal to or greater than unity: F depends on particle geometry and the nature of diffusion and reaction; G depends on environmental history of the particle; S depends on the distribution of site activities; and X depends on the distribution of particle sizes. Effects of reactor type are also studied quantitatively.
Specific heats of poly(vinyl chloride) compositions
Authors: Dunlap L. H. , Foltz C. R. , Mitchell A. G.
Published: April 2003

Specific heats of a series of plasticized and unplasticized poly(vinyl chloride) compositions have been determined by a differential scanning calorimeter over the temperature range 200–400°K. The glass temperatures were higher and the specific heat values at 300°K lower with phthalate esters then with esters of aliphatic acids; those values were also higher and lower, respectively, with benzyl‐containing esters than with the methyl or octyl esters. The data were treated by a computer technique and plotted. A mathematical expression was developed which would describe the curves obtained when specific heat was plotted against temperature, and provided values in each case for the glass temperature and the specific heat at the glass temperature and at 300°K, as well as other descriptive parameters.
Estimation of parameters of the scattering particles in horn keratin by low‐angle X‐ray scattering
Authors: Ratho T. , Torasia S.
Published: April 2003

Low‐angle x‐ray scattering methods have been applied to determine the parameters of the scattering materials in horn keratin. A low‐angle camera of Kratky's latest design has been used for the experimental measurements. By treating the substance as a densely packed system, the evaluation of the parameters has been made after theories of Porod and Kratky. Pore analysis of the substance yields a specific inner surface of 4.7 × 10−1m2/cm3, a heterogeneity distance lc = 290.2Å and a reduced inhomogeneity length lr = 99.4Å. The volume of the pores has also been determined approximately.
Critical molecular weight for onset of non‐newtonian flow and upper newtonian viscosity of polydimethylsiloxane
Authors: Ito Yoshio , Shishido Shunsuke
Published: April 2003

The flow curves of fractionated polydimethylsiloxanes of different molecular weights were obtained over a wide range of shear rates, from 3 × 10−1 to 4.3 × 106 sec−1, by use of a gas‐driven capillary viscometer designed to decrease the experimental error in high shear rate region. Non‐Newtonian flow can occur at molecular weights below the critical molecular weight Mc for the entanglement of polymer chain. The critical molecular weight M′c for the onset of the non‐Newtonian flow is identical with that of the segment of viscous flow. For the polymer of molecular weights from M′c to Mc, the upper Newtonian viscosity increases with an increase in molecular weight. Above Mc, the upper Newtonian viscosity is almost independent of the molecular weight.
Electron paramagnetic resonance study of mechanically degraded poly(ethylene terephthalate) and nylon 6 fibers
Authors: Chiang T. C. , Sibilia J. P.
Published: April 2003

Peroxide radical concentrations were measured from both PET and nylon 6 fibers mechanically stretched in air at room temperature and quickly quenched into liquid nitrogen. The radical concentrations depend on degree of stretching as well as conditions under which the fibers were made, i.e., morphology. Drawn fibers of PET and nylon 6 produced peroxide radical concentrations of the same order of magnitude at the breaking points. These results indicate that chain scissions occur both in PET and nylon 6 under mechanical stretching.
Rigidity of polycarbonate in the presence of sulfur dioxide
Authors: Davis E. G. , Rooney M. L.
Published: April 2003

A torsional pendulum method was used to study the transient effects of sulfur dioxide at pressures up to 700 torr on the rigidity of Bisphenol‐A polycarbonate at 25°C. Incremental increases in pressure led to a decrease and then to an increase in rigidity. Removal of sulfur dioxide at the rigidity minimum led to a rapid recovery in rigidity, but after apparent equilibrium had been reached the rigidity was not fully reversible. These observations provide evidence that sorption of sulfur dioxide results in structural reorganization of the polymer. A qualitative discussion of the data is presented.
Study of the influence of concentration on the time for first appearance of crystallization of polyethylene from xylene
Authors: Cryer N. B. , Zajícová V.
Published: April 2003

An experiment is reported in which a simple laser light‐scattering technique is used to measure the time for a critical turbidity to appear during the crystallization of polyethylene in xylene. The effect is examined over the entire range of solution concentration, and it is found that the relation between this concentration and temperature is linear for all solutions, provided that the time for turbidity to develop is arranged to be the same in all cases. In the appendix it is reasoned that similar results could have been obtained if, instead, times had been measured to a given degree of crystallinity rather than of turbidity. Departures from this linearity at low concentrations are taken as indicating multimolecular nucleation for all concentrations greater than about 1%.
Band structure and limiting behavior of linear polyanilines
Authors: Zach P.
Published: April 2003

The band structure of an infinite linear polyaniline is investigated by using the HCO approximation. The degree of modelling of the limiting structure for the series by the linear oligomers so far synthesized is investigated. The upper bound of the wave‐length of the long‐wave ultraviolet absorption band for the limit is found, and the possibility of estimation of the conduction properties of its complex with iodine is indicated. The problem of replacement of the NH group in the chains by a more general group X is dealt with, and the dependence of the energy gap between the highest occupied and the lowest unoccupied band on the parameters of this group is determined.
Investigation of mechanism of initiation of polymerization of cyclic acetals by protic and aprotic acids
Authors: Rozenberg B. A. , Komarov B. A. , Ponomareva T. I. , Enikolopyan N. S.
Published: April 2003

The kinetics of polymerization of 1,3‐dioxolan and degradation of polydioxolan catalyzed by boron trifluoride etherate have been studied in methylene chloride solution. The S‐shape kinetic curves is found to be due to the autocatalytic action of the macromolecules formed. Effective participation of macromolecules in the initiation process has been confirmed on the basis of the relationship of the rate constants of boron trifluoride etherate reactions with cyclic monomer and with the polymer chain as well as by the decrease of the induction period on addition of the polymer or its low molecular weight analog, methylal, to the polymerization system.
Effect of graft copolymer on demixing of immiscible polymers in solution
Authors: Horii Fumitaka , Ikada Yoshito , Sakurada Ichiro
Published: April 2003

The effect of graft copolymer on the demixing of solutions of two immiscible homopolymers and critical conditions for emulsion formation were studied. The graft copolymer used in the present work consists of one backbone poly(vinyl acetate) (PVAc) and one branch polystyrene (PS). PVAc and PS of various degrees of polymerization were used as immiscible homopolymers. The common solvent was benzene. When the concentration of homopolymer blend was not sufficiently higher than the critical concentration for demixing of the blend solution, no stable emulsion was formed, even when a considerable amount of graft copolymer was present, and the added graft copolymer merely reduced the demixing rate. However, as the blend concentration was increased, a stable emulsion could readily be obtained by addition of rather small amounts of graft copolymer. The radius of emulsion droplets was inversely proportional to the weight ratio of the graft copolymer to the dispersed component polymer, in accordance with the theoretical prediction. It was concluded that the emulsions were stabilized against coagulation by graft copolymer molecules fixed strongly as a monolayer on the interface of the emulsion.
Structure of the tetramer of α‐methylstyrene
Authors: Richards D. H. , Williams R. L.
Published: April 2003

The structure of the tetrameric dianion formed by α‐methylstyrene in tetrahydrofuran by reaction with sodium has been examined. Mass spectral, NMR, infrared, and kinetic data all indicate that the structure is
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rather than the structure
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which had previously been assumed for this species.
Photodecomposition of polystyrene on long‐wave ultraviolet irradiation: A possible mechanism of initiation of photooxidation
Authors: Lawrence J. B. , Weir N. A.
Published: April 2003

The long‐wave (λ < 3000 Å) photo‐oxidation of polystyrene in solution at 25°C has been studied osmometrically. Two types of chain scission have been observed: a purely photo process which occurs completely independently of oxygen and which is attributed to fission of photolabile groups in the polymer, and another process associated with random photolyses of the products of oxidation Scavenger experiments with 131I2 have shown that approximately two iodine atoms are incorporated per chain scission when photolysis is carried out in solution (benzene, hexafluorobenzene, methylene chloride) under high vacuum conditions in the presence of 131I2. No iodine incorporation or chain scission occurs when ionically prepared polystyrenes are treated similarly. The nature of the photolabile bond has been discussed, and there is some evidence for a peroxidic linkage arising from oxygen copolymerization in the chains. It is suggested that fission of the photolabile groups contributes to the initiation of the long‐wave photooxidation of the polymer.
Polymerization of olefin oxides with zinc n‐butyl xanthate and zinc dimethyldithiocarbamate catalysts: Mechanism of initiation
Authors: Lal Joginder , Devlin Edward F.
Published: April 2003

Xanthates and dithiocarbamates of metals have been reported to be effective as catalysts for the polymerization of olefin oxides. To investigate the mechanism of initiation, the bulk polymerization at 50°C of 1,2‐butene oxide with zinc n‐butyl xanthate (ZBX) at a monomer: ZBX molar ratio of 584: 1 was studied by ultraviolet and infrared spectroscopy. There is a rapid conversion of the sulfur–zinc bond in the metal xanthate to a structure
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containing sulfur–carbon and oxygen–zinc bonds, the latter acting as the site of the propagation step during polymerization. The xanthate ester moiety is subsequently converted to the oxygenated analogs, namely, O,O‐dialkylthiocarbonate and dialkyl carbonate. These changes are independent of the propagation step. The changes observed in the polymerization of butene oxide with zinc dimethyldithiocarbamate are similar, but much slower than in the case of ZBX. The presence of the carbonate ester moiety was also shown in the benzene‐insoluble, catalytically active fraction isolated from seeded catalyst, i.e., from the reaction product of propylene oxide and ZBX at a molar ratio of 8:1 or lower. This fraction also contained ionic sulfur.
Synthesis of an essentially alternating, aliphatic copolyamide
Authors: Pisanchyn John
Published: April 2003

An essentially alternating copolyamide of 6‐aminohexanoic acid and 11‐aminoundecanoic acid was obtained by the condensation polymerization of methyl 11‐(6‐aminohexanamido)undecanoate. The monomer was synthesized by the following reaction steps: (1) nitration of cyclohexanone to α‐nitrocyclohexanone; (2) cleavage of α‐nitrocyclohexanone by methyl 11‐aminoundecanoate to obtain methyl 11‐(6‐nitrohexanamido)undecanoate; (3) hydrogenation of the nitro group of the cleavage product. The polymer was characterized by its melting and crystallization behavior as determined by differential scanning calorimetry, by x‐ray analysis, and by comparison with an equimolar, random copolyamide of the two amino acids.
Equilibrium encapsulation of polystyrene latex particles
Authors: Keusch Preston , Williams David J.
Published: April 2003

We have performed a series of seeded styrene emulsion polymerizations in which the second stage of growth was initiated only after the second‐stage monomer charge had achieved equilibrium saturation with the seed particles. The final particles were observed in the electron microscope by using two means of distinguishing between the first‐ and second‐generation polymer: (a) butadiene tagging and osmium tetroxide staining coupled with ultramicrotomy and (b) tritiated‐styrene tagging coupled with autoradiographic detection. We find that the first‐ and second‐generation polymer chains are not uniformly mixed throughout the final latex product; rather, the second‐generation polymer overcoats the seed polymer in a core–shell fashion. In order to explain these results, we present the viewpoint that monomer actually concentrates at the periphery of the swollen particle to form a monomer‐encapsulated structure, rather than swelling the particle uniformly as has always been envisioned. We believe the encapsulation phenomena to be governed by the microscopic thermodynamic environment of the latex particles which has, in turn, a profound effect upon the conformational behavior of the long‐chain polymer molecules as they interact with the particle–water interface.
Evidence for and against concentration gradients in polymerizing latex particles
Authors: Gardon J. L.
Published: April 2003

A single‐charge emulsion polymerization involving a monomer which is a good solvent for its polymer is considered. It is shown to be unlikely that within the polymerizing latex particles there are concentration gradients large enough measurably to affect the kinetics of the reaction. The average displacement of monomers due to Brownian motion within the latex particles and in the absence of concentration gradients is calculated. This diffusive mean free path, corresponding to an interval involving less than 1% change in conversion, is shown to be much longer than the radius of the latex particle. Consequently, loci where monomer concentration is perturbed by conversion to polymer are immediately swamped by unreacted monomer. Also, direct experimental evidence exists showing that the monomer concentration in latex particles is about the same when nonpolymerizing latex particles are saturated or during polymerization in the presence of monomer excess. The thermodynamics of saturation swelling preclude the possibility of the existence of large concentration gradients. The arguments that have been advocated in the literature for core–skin separation within polymerizing latex particles were based on conversion data which were thought to be linear with time, while a reexamination indicates that they were not. The observed core–skin separation obtained when butadiene or tritiated styrene were copolymerized with styrene in the presence of a polystyrene homopolymer seed latex has questionable relevance to single‐charge homopolymerization. There are reasons to doubt that the distribution of co‐monomers within latex particles can be frozen by their conversion to polymers in a two‐stage emulsion polymerization.
Microstructure of polybutadiene catalyzed by alkali metal tert‐butoxides and n‐butylsodium. II.
Authors: Cheng Tai Chun , Halasa A. F. , Tate D. P.
Published: April 2003

A polybutadiene of high molecular weight was prepared in hydrocarbon solvent by using n‐BuNa–tert‐BuOM (M = Li, K) as a polymerization initiator. The microstructure of this polymer varied from 35 to 76% of 1,2 content, depending on the type of modifiers. The kinetics of polymerization was not studied, primarily due to the heterogeneous nature of the catalyst. However, other variables, such as the catalyst concentration and temperature, have been studied. The results and mechanistic implications are discussed.
Aromatic polyethers, polysulfones, and polyketones as laminating resins
Authors: Verborgt J. , Marvel C. S.
Published: April 2003

m‐Hexaphenyl ether, diphenyl ether, and 1,3‐bis(p‐phenoxybenzenesulfonyl)benzene were polymerized with isophthaloyl and terephthaloyl chloride in a Friedel‐Crafts type polymerization. The polymers were endcapped withp‐cyanobenzyl chloride or had units of 5‐cyanoisophthaloyl chloride in the backbone. They were crosslinked effectively, possibly by the trimerization of the nitrile groups to triazines. Model reactions were carried out for each type of polymer.
Copolymers and elastomers with alternating dioxysilphenylene and silane units
Authors: Burks Robert E. , Covington Edward R. , Jackson M. Virginia , Curry James E.
Published: April 2003

Copolymers with alternating dioxysilphenylene and diorganosilane units were investigated as a source of high‐temperature elastomers for the aerospace industry. A copolymer with dimethylsilane units alternating with dioxysilphenylene had a glass transition temperature of −63°C and exceptional thermal stability; a polymer with diphenylsilane units alternating with dioxysilphenylene had a glass transition temperature of 0°C and slightly higher thermal stability. Both were cured to elastomers at room temperature with ethyl silicate in combination with dibutyltin diacetate. Both had tensile strengths (ultimate) above 4000 psi even without reinforcing fillers. Reinforced elastomers of the dimethyl copolymer had tensile strengths (ultimate) up to 16,000 psi.
Polymerization of styrene in N,N‐dimethylformamide
Authors: George M. H. , Ward J. R.
Published: April 2003

The polymerization of styrene in N,N‐dimethylformamide (DMF) at 60°C has been studied both in the presence and absence of 4,4′‐azobis‐4‐cyanopentanoic acid (ACV). Rates of polymerization were measured dilatometrically and gravimetrically, and degrees of polymerization were determined viscometrically. There was some discrepancy in the values of the transfer constant to DMF, Cs, obtained by analysis of the results. The most reliable value appeared to be 9.8 × 10−6, from experimental data obtained in the absence of added ACV.
Block copolymerization. VI. Polymerization of pivalolactone with macromolecular initiators from polystyrene and polytetrahydrofuran
Authors: Yamashita Yuya , Hane Toshioki
Published: April 2003

Polymerization of pivalolactone with polystyryl sodium or polystyryl ethoxysodium in tetrahydrofuran resulted in homopolymer mixtures. Block copolymers of pivalolactone and styrene were obtained by the polymerization of pivalolactone with sodium polystyrene carboxylate in tetrahydrofuran containing dimethyl sulfoxide. Block copolymers of pivalolactone and tetrahydrofuran were obtained by the polymerization of pivalolactone with polytetrahydrofuran containing carboxylate endgroups. The mechanism of the initiation reaction and various factors affecting block efficiency are discussed.
Competitive growth of polystyrene latex particles: Theory and experiment
Authors: Poehlein Gary W. , Vanderhoff John W.
Published: April 2003

The results of the competitive growth of monodisperse polystyrene latex particles reported earlier by Vanderhoff et al. are reconciled with the predictions of more recent particle‐growth theories. In these experiments, monomer was polymerized in a seed latex comprised of a mixture of two monodisperse latexes so that the particles of different size competed with one another for the available monomer and free radicals. The results were expressed in terms of the equation dV/dt = kDc, where V is the particle volume, D the diameter, and k and c constants. The value of c is zero for emulsion polymerizations obeying Smith‐Ewart Case II kinetics and 3 for polymerizations in homogeneous phase. Experimentally, for water‐soluble persulfate initiator, the value of c was 2.5 for particle sizes larger than about 1500 Å and decreased toward zero as the particle size was decreased below 1500 Å; for oil‐soluble benzoyl peroxide initiator, it was 2.5 until the larger particles reached the critical size needed to sustain two growing radicals (about 13,000 Å), after which it increased to 3. The present work uses more recent particle‐growth theories to demonstrate that these experimental values of 2.5 and 3 are consistent with the theoretical predictions for water‐soluble and oil‐soluble initiators, respectively.
Effects of solvent in photo‐induced graft copolymerization of vinyl monomers on cellulose
Authors: Kubota Hitoshi , Murata Yukitaka , Ogiwara Yoshitaka
Published: April 2003

The effects of swelling of the sample and polymerization solvents were studied for photo‐induced graft copolymerization of vinyl monomers on cellulose. The graft copolymerization of methyl methacrylate (MMA) was activated by swelling of the sample or organic solvent‐water solutions within a certain range of their concentrations. Though each organic solvent gave a maximum in per cent grafting and the number of grafts at about 25 vol‐% concentration, the initiation reaction scarcely took place at 100% concentration; thus, the solvent itself is considered to have a negative effect. The solvents used in the experiments were all hydrophilic, such as methanol, acetone, and dioxane. The average molecular weight of the grafted PMMA differed in each solvent, indicating a different characteristic effect of solvent on the growing grafted polymer radicals. The presence of ferric ion as a sensitizer stimulated further the contributions of the sample swelling and the organic solvents to the copolymerization reaction. A similar effect was observed for styrene as for MMA, but not for acrylic acid and methacrylic acid.
Dependence of the viscoelastic properties of cellulose on water content
Authors: Stratton Robert A.
Published: April 2003

The dynamic mechanical properties at about 1 Hz of a film of regenerated cellulose have been measured over a range of temperatures from −100 to +90°C and water contents from effectively zero to 3%. Three loss peaks were found which were attributed to molecular motions in the amorphous regions. One of these was postulated to involve motion of segments of two chains connected through hydrogen bonding via a “tightly bound” molecule of water. Viscoelastic measurements over a somewhat wider range of water contents at room temperature exhibited contradictory effects depending upon the amount of water. These results provide support for the concept of two types of water in cellulose: tightly bound and loosely bound.
Synthesis of ionic block polymers for desalination membranes
Authors: Kurihara M. , Kamachi M. , Stille J. K.
Published: April 2003

Copolymer containing 2‐vinylpyridine–trimethylsilyl methacrylate, styrene–2‐vinylpyridine, and styrene–trimethylsilyl methacrylate blocks as well as terpolymers containing the styrene2–vinylpyridine–trimethylsilyl methacrylate blocks were synthesized by initiation of the appropriate monomers sequentially both with butyllithium and sodium. These polymers were subjected to hydrolysis by which the acrylate ester segment is converted to the free acid and to the reaction with methyl iodide, which quaternizes the pyridine segment; finally the hydrolyzed and quaternized polymers were subjected to dehydrohalogenation with external base. The properties of these block polymers and blends of the styrene‐containing block copolymers were examined, especially in regard to their suitability as reverse osmosis desalination membranes.
Random copolymer of butadiene and propylene prepared with TiCl4–Et3Al–phosgene catalyst
Authors: Furukawa Junji , Eiichikobayashi  , Haga Kazuo
Published: April 2003

The copolymerization of butadiene and propylene was investigated. It was found that the catalyst system of TiCl4–Et3Al–COCl2 yields a random copolymer of high molecular weight with a small amount of gel polymer above room temperature. Tetrachloroethylene was a good solvent for the production of high polymer containing a high proportion of propylene units in high yield. The fractionation and the analysis of degradation experiments of copolymer indicate that the copolymer is of random distribution of propylene units in the copolymer. However, the monomer reactivity ratios, rBD = 6.36 and rPr = 0.42, suggest some degree of blocked character. The properties of the copolymer were superior to those of cis‐1,4–polybutadiene, especially in resistance to thermal aging.