bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of numerical methods in the prediction of polymer adsorption
Authors: Hoffman Robert F. , Forsman W. C. , Lovering Edward G.
Published: April 2003

Average polymer segment densities and thermodynamic properties of polymer adsorbed at liquid–solid interfaces were computed by extension of the polymer adsorption theory of Forsman and Hughes. Expressions were derived for the total free energy of adsorbed polymer chains by using the Flory‐Huggins theory to represent free energy of mixing. A square‐well potential was used to represent segment–surface interaction, and configurational entropy was calculated from the probability density function for the radius of gyration of random‐flight chains. For each specified amount of surface coverage the free energy of the adsorbed polymer was minimized by varying the density of segments normal to the adsorbing surface and using a modified gradient search algorithm on a digital computer. Two different segment densities were considered, and they both gave qualitatively the same results. The two densities were (1) the sum of two Gaussian distributions and (2) a two‐step density distribution. Isotherms were then calculated by equating the partial molal free energy of polymer at the surface to that of polymer in bulk solution for each specified amount of surface coverage. The results showed that for the initial region of the isotherms the distribution of polymer segments normal to the surface consisted of a high‐density layer adjacent to the surface and a low‐density “tail” extending far out into the solution. At higher amounts of adsorbed polymer, i.e., in the general concentration range of the pseudo‐plateau, the tail of the polymer density distribution was predicted to thicken, and a single Gaussian distribution best described the segment density. Predicted adsorptions were in good agreement with reported experimental values.
Use of numerical methods in the prediction of polymer adsorption
Authors: Hoffman Robert F. , Forsman W. C.
Published: April 2003

Average polymer segment densities and thermodynamic properties of polymer adsorbed at liquid–solid interfaces were computed by extension of the polymer adsorption theory of Forsman and Hughes. Expressions were derived for the total free energy of adsorbed polymer chains by using the Flory‐Huggins theory to represent free energy of mixing. A square‐well potential was used to represent segment–surface interaction, and configurational entropy was calculated from the probability density function for the radius of gyration of random‐flight chains. For each specified amount of surface coverage the free energy of the adsorbed polymer was minimized by varying the density of segments normal to the adsorbing surface and using a modified gradient search algorithm on a digital computer. Two different segment densities were considered, and they both gave qualitatively the same results. The two densities were (1) the sum of two Gaussian distributions and (2) a two‐step density distribution. Isotherms were then calculated by equating the partial molal free energy of polymer at the surface to that of polymer in bulk solution for each specified amount of surface coverage. The results showed that for the initial region of the isotherms the distribution of polymer segments normal to the surface consisted of a high‐density layer adjacent to the surface and a low‐density “tail” extending far out into the solution. At higher amounts of adsorbed polymer, i.e., in the general concentration range of the pseudo‐plateau, the tail of the polymer density distribution was predicted to thicken, and a single Gaussian distribution best described the segment density. Predicted adsorptions were in good agreement with reported experimental values.
Flow behavior of narrow‐distribution polydimethylsiloxane
Authors: Lee C. L. , Polmanteer K. E. , King E. G.
Published: April 2003

The flow behavior of α,ω‐dihydroxypolydimethylsiloxanes, having a weight‐average number‐average molecular weight ratio of 1.1–1.2, was studied with a Cannon‐Manning viscometer and an Instron rheometer. Comparison of the flow behavior of samples with narrow and broad molecular weight distributions indicated that the onset of non‐Newtonian behavior occurred at a much higher shear rate for narrow‐distribution polydimethylsiloxanes than for polydisperse polydimethylsiloxanes. A plot of reduced viscosity versus \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma \eta _0 {M \mathord{\left/ {\vphantom {M T}} \right. \kern-\nulldelimiterspace} T} $\end{document} gave two experimental master curves, one for polymer of narrow distribution and the other for polydisperse polymer. The experimental master curve obtained from the narrow‐distribution polymer was found to fit the theoretical master curve derived from Graessley's entanglement theory. The viscosity–molecular weight relationship for the higher molecular weight polydimethylsiloxanes was found to be the same for both hydroxydimethylsilyl‐ and trimethylsilyl‐endblocked polymers. However, at low molecular weight, the viscosity–molecular weight curve deviated from linearity because of the association of polydimethylsiloxanols, which apparently is not significant at higher molecular weights. The critical molecular weight of entanglement, Mc, was found to be about 30,000.
Dynamic mechanical properties of two copolymers of styrene and n‐hexyl methacrylate
Authors: Nigmankhodjaev Abralkhodja S. , Bi Le‐Khac , Wong Chiu‐Ping , Schrag John L. , Ferry John D.
Published: April 2003

The storage (J′) and loss (J″) shear compliances have been measured for two random copolymers of styrene and n‐hexyl methacrylate with styrene contents of 18% and 30% (by weight) in the frequency range 45–4400 Hz and the temperature range 31–107°C. The data at different temperatures were combined by the method of reduced variables, and the WLF coefficients were calculated from the temperature shift factors by the method of Pierson and Kovacs. The data were compared with earlier data for the two homopolymers. The thermal expansion coefficient of the fractional free volume, and the free volume at the glass transition temperature, varied monotonically with composition, but the fractional free volume at a reference temperature of 100°C appeared to pass through a maximum as a function of concentration. Comparison of isothermal plots of J′ at 100°C, plots of the relaxation spectrum at 100°C, the monomer friction coefficient and its temperature dependence, and isochronal plots of the storage shear moduls at 100 radians/see all show that the properties of poly(n‐hexyl methacrylate) are very slightly affected by incorporation of 18% styrene and only moderately affected by 30% styrene. By contrast, comparison of styrene–butadiene rubber with 1,4‐polybutadiene shows a very large effect of incorporation of 23.5% styrene. These differences may be associated with local packing relations of the comonomer residues and suggest that copolymer properties cannot be readily predicted from those of the component homopolymers.
Effect of birefringence on the scattering of light. II. Oriented polymers
Authors: Legrand D. G.
Published: April 2003

It has been considered for some time that the presence of birefringence in an oriented polymer must affect the light‐scattering behavior. Previous analyses of this phenomenon are restricted to single‐particle scattering. A more complete theory of the effect of birefringence on the scattering of light from correlated systems is presented. The measured scattering intensity is shown to be dependent upon the optical properties of the sample as well as the experimental technique and conditions.
The effect of interference between anisotropic scattering entities on the light scattering from polymer films. I. Case of no impingement
Authors: Stein Richard S. , Picot Claude
Published: April 2003

Equations are developed for describing the effect of interspherulitic interference on the scattering of light by anisotropic spherulites. These are used to account for the variation in VV and HH scattered intensity during the course of spherulitic crystallization. The scattering depends upon the number of spherulites, their size, their anisotropy, the difference between one of their polarizabilities and that of the surroundings, and the radial distribution function of spherulite centers.
Physical structure and properties of 3‐methylbutene‐1 polymer and fiber
Authors: Quynn R. G. , Sprague B. S.
Published: April 2003

Isotactic 3‐methylbutene homopolymers and copolymers (of low 1‐olefin content) exhibit a major transition between 50 and 100°C, which dilatometric, density, and NMR observations indicate is not a glass transition, but rather a crystal–crystal transition occurring within the crystalline phase, the only phase present in significant amount. Fibers prepared from these polymers show a very high degree of orientation and crystallinity, have measured densities close to the theoretical crystal densities, and exhibit abrasion debris and electron microscopic evidence of crystalline lamellae. The fibers have a quasistatic initial modulus equivalent to the sonic modulus and exhibit very low stress relaxation and very high elastic recovery from large extensions. The fact that the fiber is highly crystalline and fully oriented, with a comparatively low initial modulus, high elastic recovery, and an extensibility of about 40%, indicate that the crystalline lamellae themselves, joined together in stacks, are able to deform (probably bend) elastically, and that the aggregate is able to undergo large elastic deformations.
Isotope effect in gas transport. I. Measurement of the free volume element in four polymers above the glass transition temperature
Authors: Ziegel K. D. , Eirich F. R.
Published: April 2003

The experimental observation of an isotope effect in diffusive gas transport across polymeric films is reported. The differences in energies of transport between hydrogen and deuterium are used to estimate the effective dimensions of characteristic minima or “wells” in the potential energy surface of rubbery polymers. The size of a well, determined by assuming it to be a cubical cavity, is interpreted as the effective free volume element vf, as measured by the hydrogen molecule probe. Estimations are made of the entropy of activation and “jump distance” for the hydrogen diffusion process based on vf values and experimentally determined pre‐exponential factors.
Solution of Fujita's equation for equilibrium sedimentation by applying Tikhonov's regularizing functions
Authors: Gehatia Matatiahu , Wiff D. R.
Published: April 2003

The Fujita equation relating molecular weight distribution to concentration of solution subjected to centrifugal forces in equilibrium proved to be an improperly posed problem in the Hadamard sense. Application of Tikhonov's regularizing functions leads to a good approximate solution of Fujita's equation. Such functions have been applied to a monomodal and a bimodal molecular weight distribution, and approximate results have been computed.
Proton magnetic relaxation times and molecular motions in polydimethylsiloxane
Authors: Cuniberti Carla
Published: April 2003

The NMR relaxation times T1 and T2 have been measured for fractionated samples of polydimethylsiloxane with different molecular weights in the amorphous state and in tetrachloroethylene solutions. The results are interpreted on the basis of the anisotropic reorientation model proposed by Woessner for small molecules. A correlation time characteristic of the diffusional rotation of chain segments is calculated and shown to be proportional to the square root of the bulk viscosity.
Structure and properties of a styrene–butadiene–styrene block copolymer
Authors: Miyamoto T. , Kodama K. , Shibayama K.
Published: April 2003

Electron‐microscopic texture and physical properties of a styrene–butadiene–styrene (SBS) block copolymer obtained by casting from toluene, carbon tetrachloride, ethyl acetate, and methyl ethyl ketone are discussed. Two peaks are observed in the mechanical loss (tan delta;) curve at −70 and 100°C which are attributed to segmental motion of polybutadiene and polystyrene, respectively. The polybutadiene peak heights are in the order of solubility in the solvent used; the polystyrene peak heights are in converse order. In addition to these peaks, a third peak is observed at 10°C for specimens cast from ethyl acetate or methyl ethyl ketone. A transition corresponding to this peak is also noticed in thermal analysis. It is proposed that aggregation of styrene blocks is relatively incomplete in specimens cast from solution in poor solvents.
Molecular weights in polymerization as a function of conversion
Authors: Litt Morton
Published: April 2003

A relatively novel method of calculating molecular weight changes and broadening during a polymerization is proposed. It differs from others in that the distribution is considered implicitly rather than explicitly. This allows direct use of kinetic rate equations in the derivation of weight‐average and number‐average degree of polymerization etc.; the mathematics simplifies to simple integration rather than sums of complicated series. The method is illustrated by applying it to several cases. These range from various models where only monomer concentration changes, to where both monomer and initiator or monomer and chain transfer agent are changing. Cases previously unsolvable can now be handled.
Small‐angle light scattering by random assemblies of incomplete spherulites. I. Sheaflike textures
Authors: Picot C. , Stein R. S. , Motegi M. , Kawai H.
Published: April 2003

The calculation of the scattering from a sheaflike sector of a two‐dimensional spherulite has been carried out as a function of the apex angle of the sector. It is found that while for a complete spherulite the Hv scattered intensity is zero at zero scattering angle, there is an increasing intensity of scattering at 0° as the sector angle narrows. For very small values of the sector angle, the scattering becomes similar to that of a rod, with the exception that a scattering maximum is still seen at an angle close to that at which the spherulite scattering maximum occurs. The predictions of the model compare favorably with the scattering patterns observed for polymers in early stages of spherulitic growth.
Cleavage of branched polyethylene by chemical filling
Authors: Hoffman H. T.
Published: April 2003

Branched polyethylene, melt‐crystallized in commercial fabrication processes, cleaves into two layers when exposed to a prolonged “chemical filling” treatment (i.e., formation of filler in situ by interdiffusion of two reactive permeants). Cleavage has been observed in film and blown bottles. With film, progressive changes in experimental conditions from one sample to another, shifted the cleavage plane from near the surface to deeper lying planes. Separation of a thin surface layer requires more filler deposit than does separation into layers of more equal thickness. These observations suggest that a well defined layer structure may exist in branched polyethylene and that cohesive bonding is stronger between layers near the surface of the film than it is between deeper lying layers. Linear polyethylene showed slight layer separation after prolonged chemical filling, but clean cut separation of large areas was not achieved. This behavior may indicate that the cohesive bonding between layers is much stronger in linear polyethylene than in branched polyethylene.
Infrared photoelectric effects in polyethylene
Authors: Vermeulen L. A. , Wintle H. J.
Published: April 2003

We have observed a flow of charge on illumination of low‐density polyethylene with infrared light in the wavelength range 1.6–0.7 μ by using silver electrodes. This flow is reversed on removal of the light, is proportional to the light intensity, and varies little with wavelength in this spectral region. There is no significant response to light of visible wavelengths. The effect decreases as the temperature is increased up to 60°C, though the time constant remains fixed. There are qualitative differences between the responses obtained with gold and with silver electrodes, and quantitative changes when the ambient air pressure is altered. The behavior suggests that during illumination, the dynamic equilibrium between carriers in the electrodes and those in the material close to the electrodes undergoes a reversible adjustment.
Morphospecific polymerization: Polyoxymethylene copolymers
Authors: Chen Catherine S. H. , Wenger Franz
Published: April 2003

Homopolymerization and copolymerization of trioxane by use of various catalysts have been investigated. When MoO2(AcAc)2 is employed, crystalline homopolymers and copolymers as formed from polymerization exhibit significantly higher melting points than corresponding polymers prepared by use of ordinary cationic catalysts. The higher melting points are attributed to different morphology of the polymer chains formed during polymerization. We now call this phenomenon morphospecific polymerization. This communication describes our results in the copolymerization of trioxane and 1,3‐dioxolane and some outstanding properties of the copolymers. A polymerization mechanism is also proposed.
Polymerization of β‐cyanopropionaldehyde. X. Anionic copolymerization with methyl isocyanate
Authors: Hashimoto Kazuhiko , Sumitomo Hiroshi
Published: April 2003

Anionic copolymerization of β‐cyanopropionaldehyde (M1) with methyl isocyanate (MeI, M2) was studied with use of benzophenone–dilithium complex as initiator at −78°C. The values of monomer reactivity ratio were determined to be r1 = 8.3 ± 0.3 and r2 = 0.01 ± 0.01. The structure of resulting copolymer was investigated by means of NMR analysis. The MeI unit is presumed to enter the copolymer chain through its CN opening.
Utilization of oxygen difluoride for syntheses of fluoropolymers
Authors: Toy Madėline S.
Published: April 2003

The utilization of OF2, for chain extension of polyperfluoropolyenes, insertion of functional groups into the polymer structure and addition copolymerization with perfluorodiene is described. The results of reactions of OF2 and polyperfluoro‐1,2‐ and ‐1,4‐butadiene indicate that conditions can be selected either to extend the polymer chain or to insert acyl fluoride groups into the polymer structure. Ambient and higher temperatures favor insertion of acyl fluoride groups. At 0°C chain extension occurs without introduction of acyl fluoride groups. Preliminary results on the novel synthesis of perfluoroalkylene oxide polymer by addition copolymerization of perfluorobutadiene and OF2 is also reported.
Cationic copolymerization of tetrahydrofuran with epoxides. II. Characterization and gel‐permeation chromatography of by‐products formed during polymerization
Authors: Hammond J. M. , Hooper J. F. , Robertson W. G. P.
Published: April 2003

The cyclic oligomers formed as by‐products in the polymerization of propylene oxide. 1,2‐butylene oxide, and n‐propyl glycidyl ether, and in the copolymerization of these monomers with tetrahydrofuran have been studied by gel‐permeation chromatography and otherwise and their structures have been determined. Some of the physical properties of the cyclic oligomers are described.
Cationic copolymerization of tetrahydrofuran with epoxides. III. Synthesis of block copolymers
Authors: Hammond J. M. , Hooper J. F. , Robertson W. G. P.
Published: April 2003

Polymerization of various cyclic ethers by BF3·O(C2H5)2 in the presence of polymeric glycol leads to the formation of hydroxyl terminated block copolymers. Where poly(oxyethylene glycol) is used as the polymeric glycol, fission of the poly(oxyethylene glycol) chain occurs, and block copolymers, containing shorter ethylene oxide unit sequences are obtained. With poly(oxypropylene glycol), on the other hand, the polymer chain remains intact. This may be due to the steric influence of the pendant methyl groups. The cyclic oligomers formed as by‐products in the polymerizations are easily removed.
Transient analysis of a viscoelastic torsion pendulum: Error analysis
Authors: Glauz R. D.
Published: April 2003

The error analysis for the transient torsion pendulum test is developed based on a linearized approximation. Tables are given for the efficient utilization of the equations in evaluating the accuracy range of the test data.
Thermal reactions of N,N′ bis(p‐nitrophenyl)sulfamide and p‐benzoquinone dioxime–acid mixtures
Authors: Riccitiello S. R. , Fohlen G. M. , Parker J. A.
Published: April 2003

N,N′ Bis(p‐nitrophenyl)sulfamide and p‐benzoquinone dioxime–acid mixtures were found to undergo an abrupt reaction when heated to give a black polymeric material. These polymeric materials exhibited thermal stability (TGA in N2) up to 500°C and were insoluble in all solvents including hot concentrated sulfuric acid. From analytical data, structural formulae have been assigned to the polymeric materials that are logically derivable from the starting materials.
Structure of polymers obtained from sulfur monochloride and olefins containing sulfonium salt structures
Authors: Lautenschlaeger F.
Published: April 2003

Reactions of sulfur monochloride with diolefins lead to polymeric products which can be reduced to diepisulfides in low yield. In reactions with cyclic triolefins, polymers containing tricyclic sulfonium structures are obtained as a results of transannular additions and subsequent transannular displacements. Due to the insolubility and reactivity of these ionic structures, only incomplete structural assignements could be made, but the reactions are studied on similar cyclic structures which provide model systems.
Partial ladder polymers with anthraquinone units. Reaction of 1,2,5,6‐tetraaminoanthraquinone with p‐benzoquinone derivatives
Authors: Szita J. , Marvel C. S.
Published: April 2003

1,2,5,6‐Tetraaminoanthraquinone has been condensed with 2,5‐diaminobenzoquinone, 2,5‐diaminobenzoquinone diimide, and 2,5‐diaminohydroquinone to give partial ladder polymers which are only slightly soluble in sulfuric acid and do not produce soluble products on reduction with sodium dithionite in alkaline media.
Ziegler polymerization of olefins. IX. Donor effects in metal alkyl‐free and Ziegler‐type stereospecific catalysts
Authors: Boor J.
Published: April 2003

Electron donors, especially trialkylamines and azulene, have been examined in aluminum alkyl‐, CH3TiCl3‐ and hydrogen‐activated TiCl3 catalysts for the polymerization of propylene to isotactic polymer. A comparison and an evaluation were made with findings which were established earlier with zinc alkyl‐based TiCl3 catalysts. We find that the donor, when it is present in low concentrations in all of the above catalysts, can inactivate preferentially the less stereoregulating sites. In this way the isotactic content and the molecular weight of the polymer are increased, but only at the expense of a lower catalyst activity. The addition of hydrogen to the TiCl3–donor catalyst at −78°C produced a threefold effect: (1) the activity of the catalyst was increased about 5 to 15 times and higher, (2) the polypropylene formed with this more active catalyst was more isotactic (ca. 10–15%), and (3) the polymer had a lower molecular weight. It is proposed that the increase in catalyst activity was due to the generation of Ti‐H bonds to which propylene molecules then added, the Ti‐H bonds thus being transformed into active Ti‐C centers.
Structure and reactivity of α,β‐unsaturated ethers. XIII. Cationic copolymerization and acid‐catalyzed hydrolysis of 1,2‐dialkoxyethylenes
Authors: Okuyama Tadashi , Fueno Takayuki
Published: April 2003

The cationic copolymerizations of geometrical isomers of 1,2‐dimethoxy‐ and 1,2‐diethoxyethylenes with vinyl isobutyl ether as a reference monomer have been carried out in methylene chloride at −70° using boron trifluoride etherate as catalyst. The kinetics of the acid‐catalyzed hydrolysis of these ethers has also been investigated in 80% aqueous dioxane, in order to compare the results with the polymerizabilities. It has been found that the cis ethers are ca. four times as reactive as their trans isomers in both reactions. On the other hand, it has been proved that a β‐alkoxyl substitution reduces the hydrolysis reactivity of vinyl alkyl ethers by a factor of ca. 10−3 while it even enchances the cationic polymerizability. These contrasting results are interpretable from the nature of the transition states which are different for the two reactions.
Modification of poly(vinyl chloride). XIII. Crosslinking of poly(vinyl chloride) with dithiols and properties of the crosslinked products
Authors: Mori Kunio , Nakamura Yoshiro
Published: April 2003

PVC was crosslinked by immersing PVC–dithiol blends in ethylenediamine at 30°C. Properties of the products depended on the chain length and chemical structure of the crosslinkage and on the molecular weight of the polymer chain between crosslinks Mc. Crosslinking by the agent of soft structure and long molecular chain resulted in high tensile strength at break and impact strength and low brittle temperature. The use of the crosslinking agent of short molecular chain gave high yield strength, Young's modulus, and heat distortion temperature. The relation of Mc and the chemical structure of the crosslinks to the properties of the crosslinked rigid polymer was discussed in regard to the crosslinking effect and plasticizing effect.
Use of phosphite amides in the synthesis of polyamides
Authors: Overberger C. G. , Veneski R. A. , Šebenda Jan
Published: April 2003

The preparation of polyamides by the phosphite amide procedure was investigated. The yield of amidation was determined in the reaction of diethyl‐ or o‐phenylenephosphite derivatives of piperidine, piperazine, or trans‐2,5‐dimethylpiperazine with either mono‐ or dicarboxylic acids. Higher yields were obtained by using diethyl phosphite derivatives; however, for both types of derivatives the yields were never greater than 90%. Only low molecular weight polymers could be obtained under optimum reaction conditions. In the polycondensation of (+)‐trans‐1,3‐cyclohexanedicarboxylic acid or (+)‐trans‐1,2‐cyclohexanedicarboxylic acid with phosphite derivatives of either piperazine or trans‐2,5‐dimethylpiperazine, the optical rotation of the polymers was lower than the rotation of the corresponding polyamides prepared by the interfacial condensation procedure with dicarboxylic acid chlorides. It was shown that an intermediate mixed anhydride was formed during the amidation reaction. This may account for the observed racemization.
NMR identification of C11 to C40 branched hydrocarbons derived from the decomposition of polyisobutylene
Authors: Warren R. W. , Gates D. S. , Driscoll G. L.
Published: April 2003

The composition of nonvolatile fluids obtained from thermally cracking and hydrogenating polyisobutylene was determined by using a combination of gas chromatography and nuclear magnetic resonance spectroscopy (NMR). This work involved the separation and characterization of a homologous series, C11–C40, of sixteen branched hydrocarbon species consisting of repeating isobutylene structures. As a result of this investigation, useful correlations between NMR spectra and molecular structure for highly branched hydrocarbons were developed. The data demonstrate that these hydrocarbons are unique species characterized by “crowded” and sterically hindered geminal methyl and isolated methylene groups. NMR solvent shift studies in benzene solutions indicate that it is possible to differentiate between maximally crowded geminal methyl groups and between maximally crowded methylene groups in these structures. Results of the benzene‐induced solvent effects are discussed with respect to the stereochemistry of these molecules and related to existing solvent shift data. These results suggest that these hydrocarbons are polar or nearly polar materials. Successive losses of isobutylene units from stabilized tertiary radicals can account for the formation of the major species identified in these fluids. Higher carbon numbered species have lower refractive indices and densities and higher molal volumes than predicted by calculations.
Propagation rate constant in cationic polymerization of cyclic dienes. I. Polymerization of cyclopentadiene with titanium tetrachloride–trichloroacetic acid
Authors: Kohjiya S. , Imanishi Y. , Higashimura T.
Published: April 2003

Cationic polymerization of cyclopentadiene induced by titanium tetrachloride–trichloroacetic acid was investigated in a toluene solution at −69 to −77°C. All manipulations were handled under vacuum conditions. Time–conversion curves were determined accurately by following the exothermicity of the fast reaction in an adiabatic system. The polymerization kinetics were developed on the basis of a fast initiation reaction and a nonstationary‐state concentration (diminishing concentration) of active species, and the propagation rate constant k2 was determined by substituting either an initial rate of polymerization or a final conversion for the kinetic equations. k2 for the present system was determined to be 350 l./mole‐sec, which is larger than those so far reported for some vinyl monomers in cationic polymerization. The present method can be commonly applied to reactive monomers for the determination of k2. The nature of termination reaction is discussed in connection with the determination of k2.
Effects of complexing agents in radical copolymerization
Authors: Zubov V. P. , Valuev L. I. , Kabanov V. A. , Kargin V. A.
Published: April 2003

Radical copolymerization of methyl methacrylate (MMA, M1) with various monomers has been studied in presence of modifiers, i.e., complexing agents (CA): ZnCl2, AlCl3, AlBr3, Al(C2H5)2Cl, forming coordinate complexes with ester group of the monomer and of the propagating radical. The comonomers of the first group form complexes of similar structure and stability as MMA, methyl acrylate, or butyl acrylate. The comonomers of the second group do not form complexes with the modifiers (vinylidene chloride, 2,6‐dichlorostyrene, p‐chlorostyrene, styrene). For all systems studied the copolymer composition follows the Mayo‐Lewis equation. In the first group of the systems the effective reactivity ratios (r1, r2) approach unity with increase of the CA molar content (r1 = r2 ≃ 1 at [(CA)/MMA] + [MA] ≥ 0,3) In the second group of the systems the values of r1 either increase to a limit value (at [CA]/[MMA] ≥ 0.3), pass through maximum, or decrease to a limiting value with the CA molar content. The values of r2 decrease in all systems. The character of variation of r1 and r2 has been explained in terms of effects of the CA's on reactivity of MMA and PMMA radical. The equations for the copolymer compositions in these systems have been derived.
Cross‐termination rate constants in copolymerizations of some methacrylates and styrene
Authors: Ito Katsukiyo
Published: April 2003

Cross‐termination rate constants in the copolymerization of some methacrylates with styrene were determined. The rate constants obtained decrease with increasing r1 and increase with decreasing r2. The relationship between the cross‐termination and propagation rate constants was discussed on theoretical and experimental bases.
Optically active copolyamides by melt and solution condensation polymerization
Authors: Yamaguchi Hidemasa , Ueno Hiroshi , Minoura Yuji
Published: April 2003

The melt and solution condensation copolymerization of nylon salts which were prepared from d‐camphoric acid and adipic acid with hexamethylenediamine were carried out, and optically active copolyamides were obtained. The copolyamides obtained had a positive specific rotation. The specific rotations for the copolyamides increased with increasing content of d‐camphoryl units in the copolymers. The optical rotatory dispersion of the copolyamides had positive curves and were found to fit the simple Drude equation. The λc values of the polymers obtained by the melt and solution condensation polymerization were 241 mμ and 245 mμ, respectively.
Optically active copolyamides by interfacial condensation polymerization
Authors: Yamaguchi Hidemasa , Ueno Hiroshi , Minoura Yuji
Published: April 2003

The polymerization of d‐camphoryl dichloride with polymethylenediamines (n = 2, 3, 5, 6, 7, 9) and copolymerization of hexamethylenediamine with d‐camphoryl dichloride and adipyl dichloride were carried out by the interfacial condensation method, and optically active copolyamides were obtained. The specific rotation of poly(hexamethylene camphoramide) obtained increased markedly with increasing intrinsic viscosity over the range of 0.05–0.10. The specific rotation for the copoyamides increased linearly with increasing content of d‐camphoryl units in the polymers. The optical rotatory dispersion of the polyamides and copolyamides had a negative curve which fit the simple Drude equation. The λc values of the polyamides and the copolymers obtained were 265 and 273–285 mμ, respectively. In order to investigate the conformation of the polyamides, the effects of solvent on the specific rotation of the polymers were studied.
γ‐Ray‐induced polymerization of α‐haloacrylic acids
Authors: Watanabe Haruhiko , Murano Masao
Published: April 2003

The γ‐ray induced polymerizations of α‐chloroacrylic acid, mp 66°C, and α‐bromo‐acrylic acid, mp 72°C, were investigated in the temperature range from 35°C to 85°C. An analysis of polymerization kinetics was made, and results were similar to those reported in the literature for other vinyl monomers. On heating of the polymer obtained, elimination of hydrogen halide takes place, and intramolecular lactone formation is observed. The rate of lactone formation of poly(α‐chloroacrylic acid) obtained in the solid‐state polymerization was found to be higher than that in the liquid state, because a highly isotactic configuration of polymers, tends to be formed in the solid‐state polymerization, and elimination of hydrogen chloride is facilitated with an isotactic 52 helix structure.
Thermal degradation of poly(alkyl acrylates). I. Preliminary investigations
Authors: Grassie N. , Speakman J. G.
Published: April 2003

A qualitative survey of the thermal degradation reactions which occur in poly(ethyl acrylate), poly(n‐propyl acrylate), poly(isopropyl acrylate), poly(n‐butyl acrylate) and poly(2‐ethylhexyl acrylate) has been made by using three thermal analytical methods: thermogravimetric analysis (TGA), thermal volatilization analysis (TVA), and the dynamic molecular still (DMS), all combined with infrared and mass spectrometry. Degradation in poly(isopropyl acrylate), which is a secondary ester, becomes discernible at 260°C and proceeds in two stages. The other four polymers, which are all primary esters, are more stable. They degrade in a single‐stage process starting at 300°C. The principal volatile products from the primary esters are carbon dioxide and the olefin and alcohol corresponding to the alkyl group. A roughly equivalent quantity of short‐chain fragments is also formed. From poly(isopropyl acrylate), carbon dioxide and propylene are the only volatile products in the first phase of the reaction.
Modification of poly(vinyl alcohol) through reaction with phosphorus‐containing reactants
Authors: Carraher Charles E. , Torre Larry
Published: April 2003

Crosslinked products of the form:
magnified image
and
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have been formed from the interfacial condensation of phosphorus diacid halides with poly(vinyl alcohol). Product yield and amounts of phosphorus reactant included in the product increases as the amount of base increases. Product stability in aqueous systems decreases in the order neutral > base > acid.
Stereospecific polymerization of isobutyl vinyl ether. III. Polymerization with VCl3 • LiCl
Authors: Joh Yasushi , Harada Koichi , Yuki Heimei , Murahashi Shunsuke
Published: April 2003

The polymerization of isobutyl vinyl ether by vanadium trichloride in n‐heptane was studied. VCl3 • LiCl was prepared by the reduction of VCl4 with stoichiometric amounts of BuLi. This type of catalyst induces stereospecific polymerization of isobutyl vinyl ether without the action of trialkyl aluminum to an isotactic polymer when a rise in temperature during the polymerization was depressed by cooling. It is suggested that the cause of the stereospecific polymerization might be due to the catalyst structure in which LiCl coexists with VCl3, namely, VCl3 • LiCl or VCl2 • 2LiCl as a solid solution in the crystalline lattice, since VCl3 prepared by thermal decomposition of VCl4 and a commercial VCl3 did not produce the crystalline polymer and soluble catalysts such as VCl4 in heptane and VCl3 • LiCl in ether solution did not yield the stereospecific polymer. It was found that some additives, such as tetrahydrofuran or ethylene glycol diphenyl ether, to the catalyst increased the stereospecific polymerization activity of the catalysts. Influence of the polymerization conditions such as temperature, time, monomer and catalyst concentrations, and the kind of solvent on the formed polymer was also examined.
Polyimides based on pyrazinetetracarboxylic dianhydride and some related model compounds
Authors: Vaughan George B. , Rose Jerry C. , Brown G. P.
Published: April 2003

A study was made of polyimides based on pyrazinetetracarboxylic dianhydride (PTDA) plus heterocyclic diamines different from the one previously reported by Hirsch. It was postulated that thermal properties might be improved if the diamine portion did not contain the N–N linkage. The results indicate that these heterocyclic‐based polyimides are in fact of lower thermal stability and of less molecular weight buildup than their corresponding polypyromellitimides. Thermal failure, outlined by their TGA curves, is shown not to be due to an inherent lack of stability for such polymers, but rather, to synthesis problems arising from both the anhydride and amine precursors. The synthetic problems are twofold: (1) the heterocyclic diamines used in this study display low reactivity; (2) pyrazinecarboxylic acids readily decarboxylate. These conclusions were drawn from a correlation of the relative basicity values of the diamines of consideration and from study of a series of model compounds prepared from an appropriate amine or diamine with PDTA, pyrazinedicarboxylic anhydride, phthalic anhydride, or pyromellitic dianhydride. An accumulation of infrared and mass spectra data for these models relate that the proposed pyrazine polyimides are not of complete polyimide structure, but rather resemble recurring amide‐imide units.
Kinetics of vinyl acetate emulsion polymerization
Authors: Harriott Peter
Published: April 2003

The emulsion polymerization of vinyl acetate has generally been considered a special type of reaction that is not covered by the Smith‐Ewart theory. Although the number of particles depends on coalescence rates and can not be predicted by this theory, the polymerization rate data are consistent with the general concepts of Smith and Ewart, including reaction primarily inside swollen polymer particles, escape of radicals from particles, and termination of chains inside the particles. Allowing for rapid exchange of radicals following chain transfer leads to a simple equation which fits much of the published data for cases of both very low and very high values of n, the average number of radicals per particle.
Polymerization of acrylonitrile with VCl4–Al(C2H5)3 catalyst system in presence of acetonitrile
Authors: Dixit Sunit S. , Deshpande A. B. , Kapur S. L.
Published: April 2003

The polymerization of acrylonitrile with the homogeneous catalyst system of VCl4–AlEt3 in acetonitrile at 40°C has been investigated. The rate of polymerization is found to be first‐order with respect to monomer and inversely proportional to the catalyst concentration. The overall activation energy for this catalyst system is 10.97 kcal/mole. The inverse proportionality of rate of polymerization with the catalyst concentration is attributed to the permanent complex formation between the catalyst complex and acrylonitrile, and a reaction scheme is proposed.
Polyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings
Authors: Taimr Ludek , Smith James G.
Published: April 2003

Polyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings are prepared from 1,4‐bis(carboethoxy)bicyclo[2.2.2]octane, 1,4‐bis(hydroxymethyl)bicyclo[2.2.2]‐octane and the 1,5‐disubstituted bicyclo[3.2.2]nonane analogs. These polyesters are compared to the related polymers containing 1,4‐phenylene and trans‐1,4‐cyclohexylene rings in terms of their melting point, thermal stabilities and oxidative stabilities. The lower symmetry of the bicyclo[3.2.2]nonane ring produces lower‐melting polymers than the other ring systems. The remaining three rings are approximately equivalent in their effect on the melting point of a polymer provided that no more than one bicyclo[2.2.2]octane ring is present per polymer repeat unit. Two such rings produce a highermelting polymer than any other combination. Both the thermal and oxidative stabilities of the polyesters is improved by the presence of the bicyclo rings. This is attributed to the rings providing an approximation of a ladder polymer.
Dissociation‐association sorption on ion exchangers. I. Experimental study of dependence of equilibrium function of acidity in ion exchanger on activity of hydrogen ions in aqueous phase
Authors: Novák Milan
Published: April 2003

Equilibrium coloring of crystal violet, methyl violet, and dimethyl yellow sorbed on ion exchanger Dowex‐50‐WX4 was studied by a spectrophotometric method as a function of the pH of the aqueous phase. From the data obtained, the function of acidity in a ion exchanger was calculated corresponding to individual equilibriums of the exchange reaction. A simple relationship between H̄0′ in a ion exchanger and the pH of the aqueous phase was found.
ESR study of free radicals produced in polyethylene irradiated by ultraviolet light
Authors: Hama Yoshimasa , Hosono Kazuya , Furui Yasuro , Shinohara Kenichi
Published: April 2003

ESR studies of ultraviolet‐irradiated polyethylene (PE) were carried out. Irradiation effects different from those of high‐energy radiation are observed. Ultraviolet radiation is absorbed selectively, and especially in carbonyl groups in PE produced by oxidation. Radicals produced were identified as \documentclass{article}\pagestyle{empty}\begin{document}$ \hbox{---} {\rm CH}_2 \hbox{---} {\dot {\rm C}} {\rm H} \hbox{---}{\rm CHO}$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ \hbox{---} {\rm CH}_2 \hbox{---} {\dot {\rm C}} {\rm H} \hbox{---}{\rm CH}_2 \hbox{---}$\end{document}. Some radicals giving a quintet signal stable at room temperature were also observed but remained unidentified. The radical \documentclass{article}\pagestyle{empty}\begin{document}$ \hbox{---} {\rm CH}_2 \hbox{---} {\dot {\rm C}} {\rm H} \hbox{---}{\rm CHO}$\end{document} undergoes a mutual conversion with the acyl radical:
Cationic polymerization of isobutene initiated by stannic chloride and phenols: Polymer endgroup studies
Authors: Bauer R. F. , Russell K. E.
Published: April 2003

Low molecular weight polymers of isobutene produced with stannic chloride as catalyst and phenols as cocatalysts have been subjected to ultraviolet and NMR analysis. A high proportion of the endgroups are derived from the phenol cocatalyst when the concentration of free phenol in the reaction mixture at −78.5°C is fairly large. At low concentrations of free phenol, termination to give vinylidene endgroups becomes more significant. The results lend support to the suggestion that an important mode of termination in this polymerization system involves the reaction between a growing carbonium ion and the phenol cocatalyst.
Effect of amines on the ceric ion‐initiated polymerization of vinyl monomers. I. Polymerization of acrylonitrile by ceric ion–triethylamine catalyst system
Authors: Saha Sisir K. , Chaudhuri Ajit K.
Published: April 2003

The polymerization of acrylonitrile was studied in aqueous solution with ceric ammonium sulfate in the presence of triethylamine as initiator at 30, 40, and 50°C. The rate of polymerization was found to be linear with the concentration of the amine and independent of ceric ion concentration. A reaction scheme involving initial complex formation between ceric ion and the amine and subsequent disproportionation of the conplex to produce free radicals is proposed for the initiation reaction. The termination step is postulated as involving oxidation of the polymer chains by ceric ions. The results have been explained in the light of the proposed reaction scheme.
Spectroscopy of irradiated vinyl chloride–propylene copolymers
Authors: Albarino R. V. , Otocka E. P. , Luongo J. P.
Published: April 2003

Spectra of vinyl chloride—propylene copolymers irradiated at low temperature in vacuum have been obtained at selected temperatures in the range 130–335°K. Copolymers and PVC homopolymer pass through identical intermediate states of dehydrochlorination in which alkyl, allyl, and polyenyl radicals are observed. Substantial spectral differences between copolymers and PVC appearing in the final states of dehydrochlorination after warming above room temperature are consistent with shorter average polyene lengths in the copolymers. This probably results from termination of polyene growth by propylene comonomer. Spectral differences at long wavelength between copolymers with varying amounts of propylene are minor compared to the basic changes between copolymer and homopolymer.
Mechanism of stabilization of polypropylene by ultraviolet absorbers
Authors: Guillory J. P. , Cook C. F.
Published: April 2003

The ultraviolet screening properties of 2‐hydroxyphenylbenzotriazoles and 2‐hydroxybenzophenones in polypropylene film were investigated by using photochemical and spectroscopic techniques. The effect of light screening on polymer photostability was examined by using filter solutions, and the fraction of ultraviolet light absorbed by stabilized film was calculated and compared to flexural failure times. It was found that the 2‐hydroxyphenylbenzotriazoles behave primarily as screeners of ultraviolet light whereas the 2‐hydroxybenzophenones are both screeners and excited‐state quenchers. The quenching characteristics of the latter have not been isolated and mechanistically examined, but it is probably similar in nature to that of the nickel chelate stabilizers.
Synthesis of poly(arylene ethylene) oligomeric hydroperoxides and their use as initiating agents of radical polymerization
Authors: Chuchin A. E.
Published: April 2003

The oxidation to hydroperoxide of poly(arylene ethylenes) (PAE) by oxygen carried out in solutions at 80–110°C. The effect of initiating additions and the nature of solvent relative to the content of hydroperoxide groups in oxidized PAE were investigated. The oxidation to hydroperoxides in PAE occurs at the methylene groups, and the synthesized hydroperoxides are secondary peroxides. The decomposition of PAE hydroperoxides in toluene and chlorobenzene at concentrations of 0.006–0.03 mole/l. for hydroperoxide in the presence and absence of N‐phenyl‐α‐naphthylamine (PNA) was studied. The decomposition of one hydroperoxide has been studied in the presence of cobaltous and manganese resinates and of PNA in chlorobenzene at 30–50°C. The addition of PNA to a chlorobenzene solution of PAE hydroperoxide containing cobaltous or manganese resinate accelerates the hydroperoxide decomposition, reduces the activation energy, and changes the reaction order from the second‐order to first‐order. The synthesized hydroperoxides initiate the radical polymerization of styrene and methyl methacrylate. The initiating activity of one of the synthesized hydroperoxides of PAE for polymerization of styrene (60°C) in the presence and absence of activating addition of manganese resinate was also evaluated.
Criticisms of claims in the field of isomerization polymerization. II. Polymerization of o‐isopropylstryene
Authors: Kennedy J. P. , Magagnini P. L. , Plesch P. H.
Published: April 2003

The polymerization of o‐isopropylstyrene with free radical (benzoylperoxide, heat) and cationic (AlCl3, AlBr3) initiators has been investigated. It is concluded that, contrary to an earlier prediction and to a claim by Aso et al., both the radical and carbonium ion polymerizations of o‐isopropylstyrene proceed by conventional mechanisms which give the same 1,2 repeat unit.