bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of temperature on ozone cracking of rubbers
Authors: Gent A. N. , McGrath J. E.
Published: April 2003

The rates of growth of single ozone cracks have been measured for vulcanizates of a series of butadiene–styrene copolymers, over a temperature range from −5°C. to 95°C. The rates appear to be determined by two mechanisms. At low temperatures, near the glass transition temperature, they are quantitatively related to the segmental mobility of the polymer. The principal rate‐controlling step in this case is concluded to be movement of the polymer chains after scission to yield new surface. At high temperatures the rate approaches a limiting value of 10−3 cm./sec./mg. of ozone/l. This is about 1/1000 of the maximum possible value when instantaneous reaction of one incident ozone molecule causes scission of one network chain.
Poly(chloroaldehydes). I. Polychloral stabilization
Authors: Rosen Irving , Hudgin D. E. , Sturm C. L. , McCain G. H. , Wilhjelm R. M.
Published: April 2003

Polychloral diol, unlike polyoxymethylene diol, is not readily capped in the presence of alkali catalysts. Polychloral is capped under acid conditions by acid anhydrides and chlorides and does not appear to undergo degradation during the process. Evidence for end‐capping is provided by infrared analysis in the case of the low DP polychloral, metachloral. End‐capped polychlorals possess good stability towards hot dimethylformamide and good stability at elevated temperatures (255°C.). From the melting points of copolymers, polychloral itself is estimated to have a melting point of about 460°C. The high melting point is consistent with the rigidity of the polymer chain. A means of estimating the DP of the polymer is proposed, based on a form of endgroup analysis. By this technique, metachloral is estimated to have a DP of about 50.
Polybenzothiazoles. I. Synthesis and preliminary stability evaluation
Authors: Hergenrother Paul M. , Wrasidlo Wolfgang , Levine Harold H.
Published: April 2003

Completely aromatic polybenzothiazoles possessing superior oxidative and thermal stability have been prepared from aromatic bis(o‐mercaptoamines) and aromatic dicarboxylic acids and benzothiazole forming derivatives thereof. The condensations were performed in N,N‐diethylaniline and polyphosphoric acid. The former solvent gave meltable, low molecular weight prepolymers which were advanced to high molecular weight polybenzothiazoles by heating in the solid state. The course of the reaction was follwed by removing samples periodically and determining the polymer melt temperature, inherent viscosity, specific extinction coefficient and observing changes in the infrared spectrum. In polyphosphoric acid, relatively high molecular weight polybenzothiazoles were obtained after a short reaction period. The polybenzothiazoles exhibited average TGA weight losses of 6% to 600°C. in static air. The maximum glass transition temperature obtained for poly‐2,2′‐(m‐phenylene)‐6,6′‐bibenzothiazole was 910°C. Most of the polybenzothiazoles were soluble in concentrated sulfuric acid and 0.3% solutions exhibited inherent viscosities as high as 1.51.
Elemental organic compounds. Part XIV. Polymerization of diene with organotransition metals
Authors: Tsutsui Minoru , Ariyoshi Junji
Published: April 2003

The polymerization of 1,3‐butadiene by using organotitanium catalysts, e.g. tetramethyltitanium (classified as a radical‐type catalyst), gave rubberlike polybutadiene in low yield which was rich in the trans‐1,4‐stereoisomer, while the polymerization of 1,3‐butadiene by use of organotitanium catalysts, e.g., tetravinyltitanium and tetraphenyltitanium (classified as a π‐type catalyst) gave polybutadiene rich in the 1,2‐configuration in high yield. Titanocene dichloride and bisbenzenechromium iodide were each used individually to catalyze the polymerization of 1,3‐butadiene with methyl Grignard reagent. In both cases polybutadienes rich in the 1,4‐configuration were obtained in quite low yield. These results were interpreted to be due to the lack of availability of 3d orbitals in the above‐mentioned catalyst. Organic chromium, iron, cobalt, and nickel compounds were also investigated as catalysts for the polymerization of 1,3‐butadiene. Viscous, low molecular weight products were obtained in all cases. When the chromium catalysts were used, a mixture of polymers, namely 1,2‐and trans‐1,4‐polybutadiene, was obtained in high yield. On the other hand, low product yields were observed with the use of the other catalysts; however, trans,trans,trans‐1,5,9‐cyclododecatriene was found in each case. The configuration of polybutadiene was also dependent upon the number, odd or even, of organic groups on a transition metal atom.
Morphology of deformed polypropylene. Quantitative relations by combined x‐ray, optical, and sonic methods
Authors: Samuels Robert J.
Published: April 2003

The submicroscopic morphology of uniaxially deformed isotactic polypropylene films has been examined by x‐ray diffraction, infrared dichroism, birefringence, sonic modulus, small‐angle light scattering, density, and electron microscopic techniques. Several new theoretical relationships and techniques have been developed. These include (1) a two‐phase sonic modulus theory which makes possible the determination of the amorphous orientation function and the intrinsic sonic moduli of the polymer, (2) a general relationship for the quantitative determination of the infrared transition moment angle and for the quantitative determination of the crystal orientation function from infrared dichroism measurements only, (3) the determination of the extension ratio of spherulites from the small‐angle light‐scattering patterns of deformed films, (4) a technique for the experimental determination of the intrinsic birefringence of the crystal and amorphous regions of isotactic polypropylene, (5) correlation of the polarizability difference determined from solid‐state measurements with that determined from solution measurements, and (6) other techniques for the rapid determination of orientation functions. Morphological information about uniaxially deformed isotactic polypropylene films, obtained as a consequence of these developments, is reported.
Dynamic mechanical properties of poly(n‐butyl methacrylate) near its glass transition temperature
Authors: Meyer H. H. , Mangin P.‐M. F. , Ferry John D.
Published: April 2003

The storage and loss shear compliances (J′, J″) of poly(n‐butyl methacrylate) (number‐average molecular weight 320,000) were measured at frequencies between 0.08 and 1.0 cycle/sec. in the temperature range of 18–33°C., encompassing the glass transition. Data were obtained both at voluminal equilibrium and as a function of time during the slow isothermal contraction which follows a quench to a temperature near the transition. The latter data were supplemented by dilatometric measurements on similar samples to determine the magnitude of the volume contraction. Correlation of the dependences of J′ and J″ on temperature and on elapsed time (at constant frequency) indicated that the relaxation mechanisms are controlled primarily by free volume. The method of reduced variables was successfully applied to the dependence of J′ on temperature and elapsed time using shift factors aT,t calculated from the modified Doolittle equation and the magnitudes of volume contraction measured dilatometrically. The dependence of J″ on both temperature and elapsed time was more complicated, indicating a change in the shape of the retardation spectrum with free volume. The behavior is qualitatively very similar to that of poly(vinyl acetate), previously studied, except that the magnitudes of J′ are considerably larger and the thermal expansion coefficient of the free volume is smaller.
Copolymerization of allylureas with lauryl methacrylate
Authors: Beynon K. I. , Hayward E. J.
Published: April 2003

Monomer reactivity ratios have been measured for the copolymerization of lauryl methacrylate and allylureas at 100°C., benzoyl peroxide being used as catalyst: lauryl methacrylate–monoallylurea, r1 = 29.9 ± 1.2, r2 = −0.22 ± 0.06; lauryl methacrylate–N,N‐diallylurea, r1 = 27.4 ± 0.8, r2 = 0.014 ± 0.05; lauryl methacrylate–N,N′‐diallylurea; r1 = 14.5 ± 0.7, r2 = −0.12 ± 0.04. The reactivity ratio r1 is of lauryl methacrylate relative to the allylurea molecule as a whole and the monomer reactivity ratio r2 is of the allylurea molecule relative to lauryl methacrylate. The values of the monomer reactivity ratios of lauryl methacrylate relative to a single allyl group in each of the allylureas have been calculated. It appears that the allyl groups in all of these molecules have similar reactivity for copolymerization with lauryl methacrylate. The monomer reactivity ratios provide evidence for cyclic propagation reactions in the copolymerization involving N,N‐diallylurea.
Dye‐sensitized photopolymerization. V. Polymerization of acrylamide in deaerated systems
Authors: Chen Catherine S. Hsia
Published: April 2003

The photopolymerizations of acrylamide sensitized by thiazine dyes and eosin Y in deaerated aqueous and ethylene glycol systems were investigated. The removal of most of the dissolved oxygen resulted in higher rates and higher quantum yields of polymerization. Linear per cent polymerization–time relationships were obtained. The induction period was eliminated or reduced, depending on the structure of the dye. The rate of polymerization and the molecular weight of the polymers were proportional to the 1.5 power of the monomer concentration in water and to the first power in ethylene glycol. The presence of an appropriate reducing agent was essential. In the absence of an added reducing agent, no polymerization took place in ethylene glycol and in aqueous solutions of pH ≤7. At pH >7, when hydroxyl or other anions were present as the reducing species, polymerizations took place at lower rates than in systems where a reducing agent was added. The polymerization was dependent on the nature of the buffer as well as the pH of the solution. The effectiveness of the reducing agent was also pH‐dependent. In aqueous polymerization, no enhancement in rate was observed when an appropriate combination of a cationic and an anionic dye was used as the sensitizer. The initiation mechanisms were probably different for deaerated systems and for systems under ambient atmospheric conditions. In anaerobic polymerizations, where oxygen was completely removed, enhanced rates were observed when both methylene blue and triethanolamine were used as the sensitizer. In the absence of triethanolamine polymerization took place at pH >7 but only very slowly.
Stress crazing of transparent plastics. Computed stresses at a nonvoid craze mark
Authors: Knight Alan C.
Published: April 2003

The mechanism of the stress crazing of transparent plastics is discussed in terms of a model suggested by recent publications in which the interior of the craze mark contains tenacious, elongated fibrils connecting the parallel faces. Internal and external stress distributions have been computed for a two‐dimensional model of equilibrium crazes. Three shape parameters are used; the length of a uniform section, the thickness of the uniform section, and the length of a tapered tip section. The configuration of the tapered tip is determined in the model by the requirement that stresses remain finite. Stabilization of the craze is attributed to reduction of stress intensity by an increase in the ratio of tip length to thickness as the craze propagates. Two conditions are noted where craze stability is not predicted. Qualitative agreement was found between the model and growth kinetics reported in the literature, but the simple equilibrium model does not provide a basis for explaining the effects of stress level and temperature on the size of craze marks. The occurrence of crazing rather than general elongation is explained in this model by the stress intensification which occurs when the fibrils of the craze materials are elongated.
Polyamides via the ritter reaction
Authors: Ramp Floyd L.
Published: April 2003

A new series of polyamides has been prepared by the condensation of dinitriles with bis(acetoxymethyl)durene in sulfuric acid.
Concentration dependence of the reduced viscosity of dilute aqueous polyelectrolyte solutions
Authors: Darskus R. L. , Jordan D. O. , Kurucsev T. , Martin M. L.
Published: April 2003

The concentration dependence of the reduced viscosity has been studied for several polyelectrolytes in conductivity water. It is shown that the viscosity maximum previously reported for polyelectrolyte solutions without added electrolyte can be explained either by the presence of ionic impurities in the solvent or by the contamination of the solutions. It is concluded that the folding chain theory of polyelectrolyte solutions requires amendment to account for the experimental results on counterion association. A suggested amendment to the theory implies that the application of the Huggins equation to the concentration dependence of polyelectrolyte solutions in the presence of added electrolyte may not lead to information concerning the interactions between the polyions in solution.
Temperature dependence of dye diffusion
Authors: Rosenbaum Shlomo
Published: April 2003

The temperature dependence of the diffusion of cationic dyes in polyacrylonitrile fibers has been examined over a wide range of temperatures. The results were found to accord well with a free volume model of dye diffusion. Apparent activation energies increased with decreasing temperature above the glass transition temperature Tg, and became extremely high near Tg. The course of the dependence could be described by a relation of the form of the Williams, Landel, and Ferry equation.
Contribution à l'etude de la cinétique de formation de polymères séquencés par voie radicalaire
Authors: Vuillemenot Jacques , Barbier Bernard , Riess Gérard , Banderet Albert
Published: April 2003

In order to study some aspects of radical polymerization initiated by a polymer, hexanediol sebacates in different degrees of polymerization were prepared. The endgroup was the tert‐butyl perester which was used to polymerize the styrene. With such compounds, it is easy after the polymerization to take off the polyester backbone by hydrolysis. One can then study the mixture of polystyrene sequences and homopolystyrene made at the same time. It appears that if the speed of thermal decomposition of the tert‐butyl perester group on the polyester is of the same order as that of the tert‐butyl perbenzoate, the efficiency factor, i.e., the fraction of free radicals which effectively initiates the polymerization, is much smaller with a polymeric initiator. Moreover, the average degree of polymerization is much smaller in this case (even in the presence of a nonperoxidized polyester). It is believed that these two results can be explained by assuming each polyester backbone to act as a cage for the free radicals produced by its own perester group which aids their recombination and intramolecular transfer.
Fracture processes in polymeric materials. VII. The nature of local inelastic processes in glassy polymers
Authors: Berry J. P.
Published: April 2003

The nature of the response to the local stress in the vicinity of a flaw in a glassy polymer is considered in the light of recent work on the nature and structure of craze marks. It is concluded that the response is similar to that which gives rise to a craze mark and that the structure of the layer at the fracture plane responsible for optical effects is likewise similar to that of a craze mark. This hypothesis resolves some of the inconsistencies in the earlier concept of the layer structure as a domain of oriented molecules.
Test of theories of flory, ptitsyn, and kurata for dilute polymer solutions
Authors: Patel R. S. , Patel R. D.
Published: April 2003

The linear expansion factor α for the fractions of amylose acetate in various solvent–nonsolvent mixtures at different temperatures have been determined using Kurata's relationship. The validity of the Flory, Kurata, and Ptitsyn theories has been tested in terms of the dependence of the function of α on molecular weight. It has been found that Flory's theory is not applicable while the Kurata and Ptitsyn theories are in good agreement.
Kinetic study of cyclopolymerization
Authors: Minoura Yuji , Mitoh Motonori
Published: April 2003

Kinetic studies of cyclopolymerization have been reported in several papers to date, but the overall kinetics is not yet established. Therefore, divinylformal was synthesized and polymerized as a difunctional monomer, and the overall rate equation, Rp = k[I]3/4[M]3/2−2, was obtained. To interpret this irregular rate equation, elementary reactions were considered and the theoretical rate equation, Rp = k[I]1/2−1[M]2−1, was obtained. The overall activation energy of polymerization was 27.7 kcal./mole, and this value, together with the result of the measurement of residual unsaturation in the polymer, yielded a value for the difference of activation energy between cyclization and propagation reaction of 2.6 kcal./mole. The results of measurements of intrinsic viscosities and residual unsaturation in the polymer at various conversions suggest that the branching reaction occurs to some extent during polymerization. The polydivinylformal was hydrolyzed to poly(vinyl alcohol) with hydroxylamine hydrochloride, and the 1,2‐glycol structures in the poly(vinyl alcohol) were determined. The result showed a higher content of 1,2‐glycol structures than that in commercial poly(vinyl alcohol).
Effect of atomic oxygen on polymers
Authors: Hansen R. H. , Pascale J. V. , De Benedictis T. , Rentzepis P. M.
Published: April 2003

A stream of atomic oxygen, produced by passing oxygen at low pressure through a radio‐frequency coil, was allowed to impinge on films prepared from several dozen different polymers. The flow of oxygen radicals was regulated so that the reaction temperatures were between 40 and 70°C. The rapid reactions which occurred at the polymer film–oxygen radical interface were essentially unaffected by the presence of phenolic antioxidants over a wide range of concentrations but rate of reaction was greatly affected by the structure of the polymer. Bulk properties of the polymers were unchanged because the attack by atomic oxygen is limited to the surface of the polymer. In many instances a simple ablation of the surface was observed, but in some cases, especially polyethylene and polypropylene, a highly oxidized surface layer was created. These oxidized surface layers had remarkably low contact angles with water and should be of great interest in improving adhesion and other surface‐dependent properties of polymers.
Solvent effects in anionic copolymerization. III. Reactivity of dienes
Authors: O'Driscoll K. F.
Published: April 2003

The effect of monomer configurations (s‐cis or s‐trans) on the observed rate of propagation of butadiene, isoprene and 2,3‐dimethylbutadiene is considered. It is shown that this effect can be separated from the electronic effect of methyl substitution. Equations and numerical values are derived which can serve as a basis for quantitative treatment of the effect of solvent on diene reactivity and microstructure.
Effect of film thickness on the dynamic elastic modulus of cellophane
Authors: Gipstein Edward , Marker Leon , Wellisch Eric , Sweeting Orville J.
Published: April 2003

The effect of film thickness on the dynamic modulus of cellophane has been investigated to inquire into structural differences that may exist in cellophane, resulting from different conditions of regeneration. Modulus measurements on different types of platecast and commercial films at first indicated a decrease in modulus with an increase in film thickness. For all films a limiting stiffness was approached with increasing thickness which appeared to be independent of the type of film. This result, however, was proved to be an artifact introduced by an instrumental effect; the dynamic modulus apparatus was found to behave as a spring in series with the film. The moduli of all films were corrected for this effect and the mean values of the moduli in the machine and transverse directions were averaged for all films separately by types and by thicknesses. The values were found to be independent of film thickness, for all types of cellophane. Cellophane by this method of study shows no indication of a point‐to‐point variation in structure in the thickness dimension. Differences in modulus do exist among different types of cellophanes, however, and are undoubtedly the result of structural differences that arise during different methods of preparation.
Cationic copolymerization of isobutene. III. Solvent effect in cationic copolymerization of isobutene with styrene in mixed solvents
Authors: Imanishi Yukio , Higashimura Toshinobu , Okamura Seizo
Published: April 2003

Copolymerizations of isobutene (M1) and styrene (M2) were carried out at −78°C. with the use of titanium tetrachloride as the catalyst in n‐hexane‐methylene chloride mixed solvents of various compositions. A great variation of r1, r2 was observed. In n‐hexane r1 < 1 and r2 > 1, in methylene chloride r1 > 1 and r2 ≃ 1, and in the mixed solvents both r1 and r2 were greater than unity. These experimental facts were interpreted on the basis of a large difference between the reactivities of isobutene cation and styrene cation. A values, on which the discussion of the decrease in the degree of copolymer polymerization can be based, were maximal in n‐hexane and decreased with increasing ratio of methylene chloride in the mixed solvent. This is characteristic of the styrenetype monomer transfer reaction.
Relaxation response of polyurethane elastomers
Authors: Theocaris P. S.
Published: April 2003

The transient extension relaxation modulus E(t) and the lateral contraction ratio vr(t) for a polyurethane elastomer have been simultaneously measured in the transition region from the glassy to the rubbery consistencies of the material. The differential moiré method was used in these measurements and yielded simultaneous values of the longitudinal extension and the lateral contraction principal strains of the tension specimen. Composite curves of E(t) and vr(t) reduced to a standard temperature were obtained by applying the method of reduced variables. The time factors KT in both curves were coincident and they followed the WLF equation. The shear and bulk modulus characteristic functions were determined from the extension modulus and lateral contraction ratio functions. The values of the lateral contraction ratio in relaxation were determined by using data of the extension relaxation modulus along the whole viscoelastic range and the initial value of the lateral contraction ratio at the rubbery state and applying an indirect method. The results obtained by the indirect method coincided with the experimental values. The shear modulus function was evaluated from the extension relaxation modulus and the lateral contraction ratio functions and compared with the shear dynamic compliance determined by Landel. The experimental data indicated that a linear relationship holds between the lateral contraction ratio in relaxation and the bulk modulus along the whole response spectrum. The same relationship was previously shown to hold for a series of various polymeric substances.
Polymerization of adsorbed monolayers. I. Preparation of the clay–polymer complex
Authors: Blumstein Alexandre
Published: April 2003

Monomolecular layers of methyl methacrylate adsorbed on the surface of sodium montmorillonite clay were prepared by saturation of the clay with the monomer, followed by desorption of the excess monomer by means of repeated washings with nonpolar hydrocarbons. No spontaneous polymerization was observed. The polymerization of these monolayers was initiated with γ‐ray irradiation or by free radical catalysts. The doses of γ‐rays and the concentration of free radical catalysts required to initiate polymerization are much higher than for the polymerization of methyl methacrylate in bulk. Complexes containing 25% MMA gave inserted polymer only; complexes containing more than 25% of MMA gave inserted and external polymer. The yields of polymerization of the inserted polymer were found to be below 50%. The inserted polymer is strongly retained by the surface of the clay. X‐ray data show that its segments are oriented horizontally (lying flat) on the surface.
Synthesis of condensation polyesters containing the bis(halomethyl) group
Authors: Miyake Hideo , Hayashi Koichiro , Okamura Seizo
Published: April 2003

Methods of preparing polyesters from 2,2‐bis(halomethyl)‐propanediols were investigated. Linear solid polyesters were obtained by the reaction with dicarboxylic acid chlorides, and this was the most suitable method of preparing polyesters from these diols. The polyoxalate, polysuccinate, and polyadipate of 2,2‐bis(chloromethyl)‐1,3‐propanediol were crystalline, but the poly(o‐, m‐, p‐)phthalates were amorphous. Polyadipates of 2,2‐bis(bromomethyl)‐and 2‐chloromethyl‐2‐bromomethyl‐propanediol were also crystalline, and polyadipates of 2,2‐bis(iodomethyl)‐ and 2‐chloromethyl‐2‐iodomethylpropanediols were amorphous.
Raman spectra of polymers in solution
Authors: Yoshino Tsuneo , Shinomiya Masayasu
Published: April 2003

The intensity and the depolarization ratio of a Raman line measured on a turbid polymer solution were related to the true intensity and the depolarization ratio, and the relations were confirmed by experiments. Apparent depolarization ratios measured on a polymer rod or solution are different from the corrected values obtained by using these relations, especially for polarized lines. The intensity per monomer unit of a polymer Raman line is equal to the intensity of the corresponding line of a model compound. No effect of polymer tacticity on Raman spectra was found.
Preparation and polymerization of vinyl esters of nonhydroxy carnuba wax acids and acrylic esters of carnuba wax alcohols
Authors: Marvel C. S. , Griffith J. H. , Comp J. L. , Cowan J. C. , O'Donnel J. L.
Published: April 2003

The acrylic esters of carnuba wax alcohols and the vinyl esters of nonhydroxy carnuba wax acids have been synthesized. The acrylic and vinyl esters have been homopolymerized and copolymerized with vinyl chloride. Acrylonitrile–acrylic ester copolymers also have been prepared. The copolymers were quite brittle when molding was attempted.
Polymerization of vinyl monomers by organoaluminum initiators
Authors: Wexler Herman , Manson John A.
Published: April 2003

Triethyl aluminum, triisobutylaluminum, and diisobutylaluminum hydride have been utilized to polymerize vinyl acetate, methyl methacrylate, and styrene at temperatures from −80 to 25°C. Linear high polymers were obtained in reasonable yields. Based on kinetic experiments studied in dilatometers, it was possible to observe: (a) the rate decreased steadily with time from an initially high value; (b) the initial rate depended upon catalyst concentration and upon the square of the monomer concentration; (c) the overall energy of activation was 13 kcal./mole, and the energy of activation for the degree of polymerization was about 2 kcal./mole. The copolymerization of methyl methacrylate and styrene produced a polymer that was rich in methyl methacrylate. The polymerization is not clearly free‐radical nor ionic, and some form of coordination may take place.
Poly(vinylene fluoride), synthesis and properties
Authors: Durrell W. S. , Westmoreland G. , Moshonas M. G.
Published: April 2003

A new synthesis of vinylene fluoride by means of the dehalogenation of 1,2‐dichloro‐1,2‐difluoroethane is reported. Both the pure cis and pure trans isomers of vinylene fluoride were found to polymerize quite readily. This polymer differs from the known polyfluoroolefins in having little crystallinity and fair solubility in a number of common solvents. While it is not markedly unstable thermally, it is the least stable of the polyfluoroethylenes in this respect. Several copolymers were prepared to further elucidate the polymerization behavior of vinylene fluoride, and some of the properties of these copolymers were examined.
Surface energetics, adhesion, and adhesive joints. IV. Joints between epoxy adhesives and chlorotrifluoroethylene copolymer and terpolymer (aclar)
Authors: Schonhorn H. , Sharpe L. H.
Published: April 2003

It is shown that structural joints can be formed between conventional epoxy adhesives and copolymer and terpolymer of chlorotrifluoroethylene, at temperatures well below the softening points of these polymers, without their prior surface treatment. An explanation of this low temperature behavior is given in terms of the surface tension of the adhesive, surface roughness, and the micro‐Brownian motion of the polymers associated with the glass transition.
Anionic polymerization of vinylmesitylene
Authors: Bhattacharyya D. N. , Smid J. , Szwarc M.
Published: April 2003

Anionic polymerization of vinylmesitylene was investigated in THF (counterion Na+) at temperatures ranging from +25° to −70°C. The homopropagation is slow (kp ∼ 11./mole‐sec. at 25°C.), indicating the basically low reactivity of the monomer. Studies of conductivity and the retardation of the polymerization by the addition of Na+BPh4− demonstrate that free ions and ion pairs participate in the process. At 25°C. the kp of the free ion appears to be about 1000 times greater than that of ion pair. The outstanding feature of the polymerization is the proton transfer from the monomer to living end, producing an inert ion

(or its isomer) which does not propagate. This reaction leads to retardation of the polymerization. Its contribution decreases on lowering the temperature, and the effect of Na+BPh4− indicates that the free ion, and not the ion‐pair, acts as a base in the proton transfer.
Catalyst and solvent effects in the terpolymerization of ethylene, propylene, and dicyclopentadiene
Authors: Cunningham Robert E.
Published: April 2003

Ethylene, propylene, and dicyclopentadiene were terpolymerized to form unsaturated, sulfur‐curable elastomers, by use of catalysts of VCl4 or VOCl3 (with Al2Et3Cl3 cocatalyst) and polymerization solvents of heptane, benzene, or tetrachloroethylene. Of the various possible catalyst–solvent combinations, best overall balance of results was given by VOCl3 catalyst in benzene solvent. All other combinations, except one, also gave good results, however, with some having special points of merit. The exception was VOCl3 in heptane solvent, which produced erratic yields of highly gelled polymer. A limited study was made of the effect of the dicyclopentadiene concentration on polymerization. Increasing the diene concentration decreased polymer yield but increased its unsaturation; it had no gross effect on the inherent viscosities of the polymers. Terpolymers containing more than about 0.30 mole CC/kg. can be cured tightly with sulfur‐based vulcanizing recipe.
Adsorption of poly‐4‐vinylpyridine onto glass surfaces
Authors: Peyser Paul , Ullman Robert
Published: April 2003

Some data on the adsorption of poly‐4‐vinylpyridine on a glass surface are presented. The results on the un‐ionized polymer are characteristic of the adsorption of organic polymers; the adsorption isotherm has a flat top and the amount adsorbed depends on the solvent used. The adsorption of ionized poly‐4‐vinylpyridine decreases with increasing ionization and increases with increasing ionic strength. The effect of increased ionic strength is presumably associated with the greater tendency of an ionized polymer to coil in the presence of excess salt. These results tend to confirm the general hypothesis that the coiling of a polymer molecule at a liquid–solid interface reflects the tendency of the polymer to coil in solution.
Silver perchlorate‐initiated polymerization of vinyl monomers
Authors: Hermans J. P. , Smets G.
Published: April 2003

The polymerization of vinyl compounds can be initiated by soluble silver salts. In this paper, the kinetics of the silver perchlorate‐initiated polymerization of styrene and methyl methacrylate in organic solution has been examined. The rates were measured dilatometrically at 70°C.; the solutions were prepared by a high vacuum technique. With respect to the monomer, either styrene or methyl methacrylate, the order of reaction is equal to two. In the case of styrene, the rate of polymerization is proportional to the silver perchlorate concentration when this concentration is ≤ 102 mole/l. Above this value, the rate becomes proportional to the square of the silver perchlorate concentration. For methyl methacrylate, the order with respect to the silver salt concentration varies from 0.5 to 1, depending on the concentration range. These kinetic results are interpreted on the basis of the assumption that a silver perchlorate–monomer complex, instead of a silver perchlorate molecule, participates in the polymerization. Moreover, the examination of styrene and benzene solutions of silver perchlorate indicates a formation of silver salt–aromatic hydrocarbon complexes of the 1:1 and 2:1 types. Consequently, good agreement is found between the kinetics of those two different initiator systems. A coordination polymerization mechanism is proposed, in which hydrogen transfer alternates with each propagation step. The mechanism is corroborated by an isotope effect equal to two, when dideuterostyrene is compared to styrene. The internal structure of the poly(methylmethacrylate) obtained with AgClO4, corresponds to that of a conventional polymer. The presence of traces of water inhibits the polymerization.
Copolymerization of p‐triphenyltinstyrene and p‐triphenylleadstyrene with styrene or vinyltoluene
Authors: Sandler Stanley R. , Dannin J. , Tsou K. C.
Published: April 2003

The reactivity ratios for the copolymerization of p‐triphenyltinstyrene (M1) and styrene (M2) have been determined by the Fineman and Ross method to be r1 = 2.55 and r2 = 0.93. The values for vinyltoluene copolymerization are r1 = 3, and r2 = 0.60. The latter values indicate that p‐triphenyltinstyrene‐copolymers with styrene or vinyl‐toluene contain blocks of the former monomer unit. The rate of homopolymerization of p‐triphenyltinstyrene and p‐triphenylleadstyrene in toluene was shown to be the same at 50°C.
Inorganic polymers. Part I. A solid inorganic foam
Authors: Shaw R. A. , Ogawa Takeshi
Published: April 2003

The preparation of a solid inorganic foam is reported. Hexaaminocyclotriphosphazatriene, N3P3(NH2)6, used either without purification, or when recrystallized from water, gives phospham as a dense powder. If, however, the starting material is precipitated from its aqueous solution by suitable organic solvents, a foamed material results. Possible reasons for this divergence in behavior are discussed. The ammonia evolved on thermal decomposition acts as a built‐in foaming agent.
Polymerization studies on methyl and ethyl α‐fluoromethylacrylate
Authors: Powell John A. , Graham Roger K.
Published: April 2003

Ethyl α‐fluoromethylacrylate was prepared from ethyl α‐chloromethylacrylate by reaction with potassium fluoride in sulfolane. The methyl ester was prepared by transesterification. The ethyl ester was found to be unexpectedly quite toxic. Homopolymers and copolymers of both monomers were found to have lower softening temperatures than polymers from the corresponding methacrylate monomers. Reactivity ratios were determined for ethyl α‐fluoromethylacrylate (M2) with styrene (r1= 0.34,r2= 0.09) and with methylmethacrylate (r1= 1.05,r2= 0.51).
Structural investigation of polyacrolein by fractional dehydration
Authors: Hunter L. , Forbes J. W.
Published: April 2003

The utilization of a specially developed technique for the low temperature pyrolysis of polyacrolein, and the accurate measurement of the waterr eleased thereby from the polymer have demonstrated the presence of well‐defined inflection points in the curve of water evolution versus dehydration (pyrolysis) temperature. These are postulated to indicate the presence of water in polyacrolein from a number of different sources, e.g., structural, hydrogen‐bonded, and free. A correlation of the measured water evolution between inflection point temperatures with the concurrently developing free carbonyl groups, measured by an infrared technique, has provided information on the type and proportion of various structural subunits in the polyacrolein molecule. This information has been used to construct a partial structural formula for the particular polyacrolein sample under examination. As a practical outgrowth of this work, the concept of the activation of polyacrolein by dehydration at elevated temperatures has proved useful in facilitating reaction of the polymer with a number of carbonyl reagents such as sodium bisulfite, SO2, etc.
Kinetics of polyacrylamide adsorption on calcium phosphate
Authors: Jankovics Lawrence
Published: April 2003

An extension of Langmuir's rate equation is obtained for polymeric adsorption when the initial concentrations of polymers differ significantly from the final or equilibrium concentrations. It is assumed that the equation developed has a general applicability for polymer adsorption whenever the experimentally determined equilibrium adsorption data can be represented by Langmuir's isotherm. Adsorption of high molecular weight polyacrylamides from aqueous solutions upon calcium phosphate is described at low concentration of the polymer. The rate of adsorption obeys a Langmuirian type equation.
Excluded volume effects in swollen polymeric networks
Authors: Rijke A. M.
Published: April 2003

Information on the parameters of polymeric networks obtained by crosslinking in solution can be provided by deswelling measurements in polymer solutions of different concentration. However, under these conditions, the existing theories describing the swelling behavior are conflicting and no definite conclusion on the network properties seems as yet justifiable. Moreover, excluded volume and chain connectivity effects are not accounted for in either of the theories. Thirdly, the effect of the presence of crosslinkis and the number of connected polymer segments in the network on the value of the Huggins' interaction parameter to be used in the expressions for the free energy of mixing is not clear. Nevertheless, the available experimental data have shown some preference for Hermans' theory over Flory's theory, whereas James and Guth's expression must be rejected altogether. A dependence of the degree of swelling q0, at which the partial molar free energy of elasticity equals zero, on solvent power of the swelling agent has been previously observed and has been further investigated in this study. To this end, methyl methacrylate was copolymerized with small amounts of divinylbenzene in dilute benzene solutions yielding six samples with different crosslink densities and q0 values. A large dependence of q0 on the osmotic second virial coefficient in four solvents was observed. The applicability of current theories for polymer–solvent interaction upon intramolecular chain dimensions to the chains in the networks has been investigated. Flory's expression for volume expansion of polymer chains falls short, but two other relations for the same initial effect show that the second virial coefficient dependence of q0 may be attributed to volume exclusion, similarly as in free chains. The validity of these relations, however, is expected to hold only for a rather limited range of the network parameters.
Polymers from ortho aromatic tetraamines and aromatic dianhydrides
Authors: Dawans F. , Marvel C. S.
Published: April 2003

Aromatic heteropolymers were synthesized from aromatic tetraamines and dianhydrides; some of the polymers had a ladder‐type structure. The properties and thermal stability of the polymer were studied. The experimental conditions yielding the imidazolone structure were determined on model compounds. Polymers containing mixed aromatic units in the chain were prepared from pyromellitic anhydride or 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride, and 3,3′‐diaminobenzidine, 3,3′,4,4′‐tetraaminodiphenyl ether, 1,4,5,8‐tetraaminonaphthalene, or 1,2,4,5‐tetraaminobenzene. The polycondensations were carried out in melt and in solution (in melted phenol, pyridine, dimethylacetamide, 116% polyphosphoric acid). The inherent viscosities of a number of polymers synthesized by melt condensation were in the range of approximately 0.2–0.7; the higher polymers were obtained by carrying out the polycondensations in solution in 116% polyphosphoric acid; in this case, the intrinsic viscosities ranged from 1.1 to 1.8. Most of the polymers do not melt at 350°C. and are soluble in the usual organic solvents, but the ladder‐type structure polymers were soluble only in concentrated sulfuric acid.
Interaction between alkaline earth metal cations and poly(methacrylic acid) in dilute solutions. I. Viscometric and conductometric titrations
Authors: Wojtczak Zbigniew
Published: April 2003

The viscometric and conductometric behavior of poly(methacrylic acid) in dilute aqueous solutions over the whole range of neutralization with barium, strontium, and calcium hydroxides were studied. The results show minima in reduced viscosity and specific conductance near degrees of neutralization of 0.2 and 1.0. These minima do not appear with neutralization with monovalent bases and are more closely related to the higher degree of association of polyanions with divalent counterions than with monovalent ions. From the fractional charge of polyanions we may conclude that about 90% of the divalent counterions are associated with polyanions in almost the whole range of neutralization. The results show the specific influence of strontium cations on the behavior of PMA solutions.
High energy electron irradiation of trihydroperfluoroalkyl acrylate monomers: Statistical evaluation of factor interdependency
Authors: Degering Ed. F. , Caldarella Gerald J. , Haines George H.
Published: April 2003

A 2,2,2,2‐factorial design was used for the irradiation‐induced polymerization of 1,1,3‐trihydroperfluoropropyl and 1,1,7‐trihydroperfluoroheptyl acrylates with a 2‐M.e.v. electron accelerator in order to more critically determine the effect of variables. From the data obtained, it is concluded that: (1) degassing, flame‐out, and time‐lapse are significant, dependent main effects for both monomers, and atmosphere is a significant, dependent main effect for the heptyl ester, (2) the atmosphere and flame‐out, degassing and time‐lapse, and flame‐out and time‐lapse interactions are independently significant for the propyl ester, whereas for the heptyl ester the atmosphere and flame‐out is independently significant, but degassing and flame‐out, degassing and time‐lapse, and flameout and time‐lapse are dependently significant, (3) the degassing, flame‐out and time‐lapse interaction is independently significant for the heptyl ester, and (4) experimental variables may be significantly interdependent.
Polycarbonate to polyether conversions
Authors: Stueben K. C.
Published: April 2003

The preparation of aromatic polycarbonates via the base‐catalyzed disproportionation of suitable alkyl‐aryl carbonates (AlkylOCOOArylOCOOAlkyl) was found to be accompanied by the formation of alkyl‐aryl ethers. Substitution of a poly(alkyl aryl carbonate) in place of the monomeric species resulted in the formation of a poly(alkyl aryl ether). Thus, it was possible to convert a copolymer of ethylene glycol and 2,2‐bis(4‐hydroxyphenyl)propane to the corresponding poly(alkyl aryl ether) with only slight loss of molecular weight. The structure of this polyether and a partially converted poly(carbonate ether) were established by analytical and degradative techniques. Conversions of other poly(alkyl aryl carbonates) were also achieved but with less success because of competing reactions. A possible mechanism for these conversions is presented.
Study of the orientation of light‐sensitive tetrazonium salt in poly(vinyl alcohol)
Authors: Tsunoda Takahiro , Yamaoka Tsuguo
Published: April 2003

v(NN) band of the diazo or tetrazonium salt, derived from p‐methoxyaniline, p‐hydroxyaniline, benzidine, or o‐dianisidine shows perpendicular dicroism in the stretched poly(vinyl alcohol) film. This means that these salts are directing their longer axes perpendicularly to the direction of the stretching. However, that of the diazonium salt from p‐aminodiphenyl or o‐anisidine shows no dichroism. From the above facts, it is concluded that the interactions between the polar groups of poly(vinyl alcohol) and those on the both ends of the diazo or tetrazonium salt such as diazo, methoxy, and hydroxy group result in the perpendicular orientation of the diazo or tetrazonium molecule.
Crosslinking of dialdehyde starches with wheat proteins
Authors: Chatterji Arun K. , Arnold Lionel K.
Published: April 2003

A quantitative and degradative study on the gluten–dialdehyde starch reaction product is made, and the possible reaction mechanisms during the degradation reactions are discussed rigorously. The structure of the gluten–DAS reaction product is arrived at by designating a generic protein structure for gluten. This study has produced new evidence regarding crosslinking sites of dialdehyde starches when they react with proteins in general.
Interactions in binary polymer systems
Authors: Williamson G. R. , Wright B.
Published: April 2003

Dilute solution viscosity measurements have been made on eleven ternary polymer systems (two polymers, one solvent). Calculation of the polymer‐polymer interaction coefficient between unlike polymer molecules by the Krigbaum and Wall treatment is not generally applicable. The empirical relationship derived by Catsiff and Hewitt has been used, and the interaction between polymers in these systems has been qualitatively interpreted on this basis.
Fracture properties of carboxylic rubbers
Authors: Halpin J. C. , Bueche F.
Published: April 2003

Rupture properties of sulfur and zinc oxide vulcanizates of a carboxylic rubber have been experimentally determined. When the logarithm of the strength at break is plotted against the logarithm of the strain at break, failure envelopes are obtained for the two vulcanizates which diverge at long times or high temperatures. As a consequence of this experimental fact it is apparent that, while there exists a failure envelope which uniquely describes a given viscoelastic system, there is no general shape of the failure envelope representative of all the rupture properties of an elastomer through all degrees of vulcanization. It is shown that the molecular fracture theory of Bueche and Halpin provides a quantitative basis for the analysis of the strength properties of elastomers through a wide range of vulcanizate quality, provided the specific character of the network structure is taken into account. It is suggested that the so‐called “unique” strength properties of metal oxide vulcanizates are in reality a natural reflection of a sparse network crosslinkage concentration.
Note on the calculation of molecular weight averages of polymers from fractionation data
Authors: Bohdanecký M. , Kratochvíl P. , Šolc K.
Published: April 2003

It has been shown that in calculating Mw, Mn, and Mv values of a nonfractionated polymer from the weights and molecular weights of fractions, corresponding averages for the individual fractions should be used. In calculating higher averages (Mz and Mz+1), the values of lower averages are also required. An analysis of errors which appear on neglecting these requirements, has been given.