bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of nucleation and growth of spherulites in homopolymers
Authors: Limbert Frank J. , Baer Eric
Published: April 2003

In order to check secondary nucleation theories previously proposed by various authors, spherulitic growth rates of polypropylene, high density polyethylene, and polyoxymethylene were measured at temperatures relatively close to their respective polymer melting points in an air circulating system with temperature fluctuations of less than ±0.05°C. Only partial agreement between theory and experiment was obtained. Interpretation of the experimental data using the similar theories of Burnett and McDevitt, and Barnes and co‐workers, gave melt‐spherulite interfacial energies which to date have not been checked by independent experiment. The critical surface tension of wetting as defined and measured by Zisman and co‐workers was compared with the melt‐spherulite interfacial energy and found in all cases to be substantially larger. The theory of Hirai, which is partially based on the absolute reaction rate theory of Eyring, was also tested, and heats of fusion which were about twice as large as values reported in the literature were found. A major shortcoming of all three nucleation theories is that the intercepts of the theoretical plots differed by many orders of magnitude for the various polymers tested. These theories do not give an adequate theoretical explanation of this fact. Thermal history of the melt was found to have a marked effect on the nucleation rate in polyoxymethylene. This implies that the overall rate constant in the Avrami theory is also strongly dependent on melt history. The data indicated that the rate constant can be decreased about five hundred times by increasing the melt temperature by 20°C.
Monomers containing phosphorus. Part I. Copolymerization of phosphonates with n‐lauryl methacrylate
Authors: Beynon K. I.
Published: April 2003

The reactivity ratios for the copolymerization of lauryl methacrylate (LMA) with diallyl phenylphosphonate (DAPP), diallyl butylphosphonate (DABP), and diethyl allylphosphonate (DEAP), respectively, have been measured at 80°.

None of the phosphonates are active for copolymerization with LMA but the DAPP and DABP have similar activities which are greater than that of DEAP. The variation with conversion in composition of the LMA‐DAPP copolymer formed at any instant has been calculated using Skiest's equation and the calculations have been extended to show the variation of the overall composition of the copolymer with conversion. Intrinsic viscosities and molecular weights have been measured for some LMA‐DAPP copolymers and these values are found to depend on the phosphorus contents of the copolymers.
Copolymerization of aldehydes
Authors: Mark H. F. , Ogata N.
Published: April 2003

Copolymerization of aldehydes has been carried out in the presence of anionic and cationic catalysts. Triisobutylaluminum gave an elastic copolymer of formaldehyde and acetaldehyde which did not melt until above 300°C. and did not dissolve in any organic solvents. The rate of the copolymerization of formaldehyde and acetaldehyde at −78°C. was very rapid, the reaction going to completion within 30 min. The thermal stability of the copolymer of formaldehyde and acetaldehyde was better than that of polyacetaldehyde but was inferior to that of polyformaldehyde; it reaches a minimum in the composition range of 40/60 to 60/40 of formaldehyde and acetaldehyde.
Molecular properties of amorphous high polymers. II. An interpretation of gaseous diffusion through polymers
Authors: DiBenedetto A. T.
Published: April 2003

A cell model is extended in order to interpret gaseous diffusion data through thin films of amorphous polymers. An amorphous polymer is again characterized as a homogeneous one component phase containing N identical n‐center polymer segments. A sorbed gas molecule is visualized as occupying an equilibrium position in a homogeneous lattice and behaving as a three dimensional harmonic oscillator trapped by surrounding bundles of parallel polymer segments. A diffusion “jump” is assumed to occur when four parallel polymer segments separate sufficiently to create a cylindrical void into which the gas molecule can move. Equations are developed which relate the activation energy for gaseous diffusion, the activation energy for self diffusion and the length of an average polymer segment to the molecular properties of the polymer. Gaseous diffusion data from various literature sources are successfully analyzed on this basis.
Thermodynamics of crystalline linear high polymers. III. Thermal breakdown of the crystalline lattice of polyethylene
Authors: Wunderlich Bernhard , Sullivan Peter , Arakawa Tamio , Dicyan A. B. , Flood J. F.
Published: April 2003

The thermal breakdown of the crystalline lattice of polyethylene grown by quenching from solution (dendrites) and by cooling slowly from solution (single crystals) and melt has been investigated as a function of heating rate. The dendrites showed strong reorganization at temperatures only little above the crystallization temperatures. Heating rates as fast as 20°C./min. could not avoid this reorganization. Heating rates between 10 and 20°C./min. were necessary to have a constant melting point for single crystals grown from solution. The measured melting points were proportional to the thickness and perhaps the density of the samples as determined by interference microscopy and by the density gradient column method. Surface free energy values calculated from the lowering of the melting points range from 81–96 ergs./cm.2. Literature values on specific heats and specific volumes of bulk samples allowed a discussion of the premelting behaviour of semicrystalline polyethylene. It is found that the defects frozen‐in below the glass transition temperature “grow” above 250°K. depending upon the overall crystallinity. This destroys the additivity of the specific heat as well as the specific volume. Correlation with NMR and dynamic mechanical loss measurements are attempted. The difference between melting and dissolution temperature in toluene (0.5–8.0 mg. polyethylene/g. toluene) for slowly cooled bulk as well as solution crystals was found to be 26°C., placing the maximum dissolution temperature of polyethylene crystals in toluene at 111°C.
Ionic polymerization of diphenylvinylphosphine oxide
Authors: Allcock H. R. , Kugel R. L.
Published: April 2003

Grignard reagents, organolithium compounds, sodium naphthalene and aluminum alkyl—metal halide catalysts were examined as initiators for the polymerization of diphenylvinylphosphine oxide. The most effective catalysts studied were Grignard reagents and sodium naphthalene. With Grignard catalysis, polymers of molecular weight up to ∼10,000 were produced although the yield, molecular weight, and crystallinity of the products were influenced by the organic and halide components of the catalyst and by the reaction solvent. Copolymerization studies indicated that the anionic reactivity of diphenylvinylphosphine oxide is between those of styrene and methyl methacrylate. For Grignard catalysis an anionic‐type polymerization mechanism is proposed which requires the formation of polymer—organomagnesium halide adducts in the transition state.
Oxine–formaldehyde polymers and their metallic chelates
Authors: Horrocks Robert H. , Winslow Eugene C.
Published: April 2003

Sulfuric acid, sodium hydroxide, formic acid, and oxalic acid were investigated as catalysts for the condensation of oxine with formaldehyde. All were found to promote the condensation in aqueous solution under conditions of reflux, although a variation in the time required was found. The condensation was effected without catalyst between 200–240°C. in a sealed container by intimately mixing oxine with paraformaldehyde. Oxine–formaldehyde condensation polymers are soluble in phenol and acids stronger than acetic acid. Chelation is obtained by dissolving the polymer in acid, adding a solution containing the ion to be chelated, and adjusting the pH of the mixture to a value sufficiently high so as to favor chelation but not so high as to precipitate the metallic hydroxide. Heat stability was determined by thermogravimetry and differential thermal analysis. All samples degraded (began to lose weight) at 270°C. or below. The mode of decomposition of the polymer chelates appears to be independent of the metallic ion, but the free polymer is different. Its initial weight loss (between 270 and 320°C.) is very gradual compared to the chelates. At 320°C. it reverts to a form similar to that of the chelate. A second difference of the free polymer is that the rate of decomposition is a function of temperature, while that of the polymer chelates is not. The chelates may therefore hold interest in use as ablative materials. A third difference is that the free polymer melts beginning at about 190°C. The chelates do not melt.
Thermal degradation ofN‐substituted polycarbamates
Authors: Dyer Elizabeth , Hammond Richard J.
Published: April 2003

N‐substituted polycarbamates of relatively low molecular weight have been prepared from the condensation of 1,6‐hexanebischloroformate withN‐substituted diamines, both aliphatic and aromatic. The initial rates of thermal degradation of these polymers and of unsubstituted analogs have been determined at 230–285°C. by following the evolution of carbon dioxide. The results showed that the more thermally stable polymers were those derived from the substituted aliphatic diamines, having the formula [N(R)XN(R)COO(CH2)6OCO]nwhere X is (CH2)5or (CH2)6. When R was CH3and C6H5, the overallEAwas 31 and 46 kcal./mole, respectively. The polymers derived from aromatic diamines, where X was 4,′ 4‐C6H4CH2C6H4, showed low values forEA, approximately 15 kcal./mole, regardless of whether R was H or alkyl. This low thermal stability was shown to be caused by amine endgroups. Some evidence as to modes of thermal degradation was obtained from a study of volatile products.
Preparation and properties of poly(tetramethyl‐p‐silphenylene‐siloxane)
Authors: Merker Robert L. , Scott Mary Jane
Published: April 2003

Improved methods for the synthesis of p‐bis(dimethylhydroxysilyl)benzene are described. This useful monomer was prepared from p‐bis(dimethylhydrogensilyl)‐benzene which was obtained in 60–70% yields from p‐dibromobenzene and dimethyl chlorosilane by use of an in situ Grignard technique. The great reluctance due to steric factors of the p‐silphenylene‐siloxane configuration to form cyclic structures has been amply demonstrated. The condensation polymerization of p‐bis(dimethylhydroxysilyl)benzene in benzene solution has yielded high molecular weight, crystalline poly‐(tetramethyl‐p‐silphenylene‐siloxanes). The heat of fusion ΔHu of the tetramethyl‐p‐silphenylene‐siloxane was found to be 4350 cal./unit. The modified Staudinger equation relating intrinsic viscosity and weight‐average molecular weight was applicable over a range of 70,000–400,000. These results are summarized in the relationship, [η] = 1.12 × 10−4Mw0.75. Tetramethyl‐p‐silphenylene‐siloxanes were found to be more stable than dimethylsiloxanes both to atmospheric oxidation and degradation through volatile formation in the temperature range 200–305°C.
Preparation and polymerization of 1,5‐diamino‐2,4‐alkylenetrisilazanes
Authors: Breed L. W. , Elliott R. L. , Ferris A. F.
Published: April 2003

1,5‐Diamino‐2,4‐ethylenehexamethyltrisilazane and related compounds were prepared by treating the corresponding chlorosilane intermediates with ammonia or an amine. When these monomers were heated in xylene solution at 140°C. in the presence of ammonium sulfate, linear silicon‐nitrogen polymers were obtained with molecular weights in the range of 7,500–15,000. Elemental analyses, infrared spectra, and the physical properties of the polymers support the proposed structure and polymerization route.
Kinetics of the photopolymerization of tetraethylene glycol dimethacrylate in the bulk with the use of desyl aryl sulfides as photoinitiators
Authors: Petropoulos Constantine C.
Published: April 2003

Five desyl aryl sulfides were prepared for use as photoinitiators in the determination of the bulk polymerization rates of tetraethylene glycol dimethacrylate at 25°C. As a first approximation, the initial rates were first‐order with respect to monomer and one half‐order with respect to initiator. From this, approximate initial overall rate constants were determined. The data indicate that resonance stabilization of the dissociated radical seem to affect the polymerization rate. Complications arising from the auto catalytic gel effect were discussed.
Photolysis of cellulose in a vacuum with 2537 A. Light
Authors: Flynn Joseph H. , Morrow William L.
Published: April 2003

Cotton sliver, cotton linters, periodate‐chlorite‐oxidized cellulose, and several regenerated celluloses were photolyzed by 2537 A. ultraviolet light in a vacuum at 40°C. The changes in quantum yields of hydrogen, carbon monoxide, carbon dioxide, hydrocarbons, aldehyde groups, carboxyl groups, and chain scissions with respect to quanta of light absorbed and initial functional group concentration indicated that photolysis of alcohol groups plays a dominant role in the complex of interdependent primary and secondary reactions taking place. Periodate‐chlorite‐oxidized cellulose is much more suceptible to photochemical degradation than is unoxidized cellulose. Neutralization with very dilute sodium hydroxide solution reduced the quantum yields of the oxycellulose to values similar to those obtained with the unoxidized material.
Effects of deuteration and temperature upon the photolysis of cellulose in a vacuum with 2537 A. Light
Authors: Flynn Joseph H. , Morrow William L.
Published: April 2003

The effects of the exchange of deuterium for hydrogen in the hydroxyl groups on the composition of products and the kinetics of their formation during the irradiation of cellulose by 2537 A. in a vacuum at 77, 313, and 365°K. are described. About 50–70% of the total hydrogen evolved was HD. Little D2 was formed. Total HD evolution was independent of temperature. Disproportionation, rather than atom abstraction or atom combination, was likely to be the dominant mechanism of hydrogen production. Much of the aldehyde group formation takes place during the photolysis and probably results directly from secondary photolysis or disproportionation of radicals. H2, CO, and CO2 evolutions increase with temperature and result from both functional group photolysis and radical depropagation. Chain scission and carboxyl group formation take place to a large extent during the post‐irradiative oxidation of long‐lived oxygencontaining radicals.
Covalent acid‐labile crosslinkages in wool
Authors: Crewther W. G.
Published: April 2003

The extent of the first stage of supercontraction of wool fibers in 8M LiBr (20°C.) was unaltered by the incorporation of 1N HCl in the solutions, whereas the extent of total supercontraction (98.5°C.) was greatly increased by the presence of HCl in the LiBr solutions. Likewise, with reduced and methylated wool, the relationship between the extent of the first stage of supercontraction and the content of residual disulfide was not affected by the presence of HCl in the solutions. When reduced and methylated wool fibers containing few residual disulfide groups were allowed to supercontract in solutions containing 8M LiBr and varying concentrations of HCl, the fibers contracted rapidly until the extent of total supercontraction in neutral solutions was approached. The rate then changed suddenly and became directly proportional to the concentration of acid in the solutions. Extensive supercontraction was observed also in alkaline solutions of LiBr if carboxyl groups of the reduced and methylated fibers were first ethylated to decrease the solubility of the wool proteins. Cortical cells, which were prepared by digesting reduced and methylated wool with crude trypsin, resembled whole wool in their behavior. It was concluded that wool contains covalent crosslinkages which are hydrolyzed by acids and alkalies. Evidence is presented that these bonds are stabilized by disulfide crosslinkages. The possiblity that disulfide interchange takes place during supercontraction in solutions of LiBr‐HCl is discussed.
A scattered‐light study of linear polyethylenes
Authors: Stacy Carl J. , Arnett Raymond L.
Published: April 2003

A scattered‐light photometer particularly adapted to high temperature work has been designed and constructed. Among the desirable features are constant monitoring of the primary beam, placement of photodetectors outside the heated zone, output proportional to ratio of outputs of matched detectors, thus to Rayleigh's ratio, insensitivity of output readings to light absorption by the solution, temperature control from room temperature to 150°C. The geometrical factors affecting output readings have been analyzed and the instrument calibrated using several standards. Techniques developed for hot solution clarification and the measurement with good precision of weight‐average molecular weights of ethylene polymers are described. The results for several typical unbranched Marlex polyethylenes are given covering the range 80,000–170,000. Depending on the polymer, the ratio weight‐average to number‐average varies from 10 to 16 for whole Polymer. The z‐average molecular weights estimated from the mean‐square molecular radii are used to estimate Mz/Mw ratios.
Emulsion polymerization of vinyl monomers by transition metal compounds
Authors: Berger Richard S. , Youngman E. A.
Published: April 2003

A number of transition metal ions and complexes of the type which effect the stereospecific polymerization of butadiene in aqueous emulsion catalyze the polymerization of other vinyl monomers as well. In contrast to experience with butadiene, the structure of all products was typical of free‐radical propagation reactions. The catalysis was somewhat selective, a given transition metal compound being active for some monomers but not for others. A mechanism involving coordinate complex formation between catalyst and monomer, generation of a free‐radical initiator by redox reaction within the complex, and noncoordinated free‐radical propagation is postulated. Copolymerization studies support such a mechanism; copolymer compositions were always typical of free‐radical catalysis, even when the catalyst was active in homopolymerization of only one member of the monomer pair. Butadiene polymerizations using many of the same catalysts clearly proceed by different, little understood mechanisms. Attempted copolymerizations with butadiene gave only polybutadiene; the comonomers had no effect on polymer microstructure but generally reduced polymerization rate.
Cationic polymerization of 3‐methylbutene‐1. I. Polymerizations at moderately low temperatures
Authors: Kennedy J. P. , Minckler L. S. , Thomas R. M.
Published: April 2003

The cationic polymerization of 3‐methylbutene‐1 was investigated with the use of aluminum chloride and aluminum bromide initiators in the temperature range of −62 to −102°C. Polymerizations are homogeneous in the presence of pentane, and above −50°C. in methyl chloride. However, the polymer tends to precipitate below −50°C. in methyl chloride. The molecular weight of poly‐3‐methylbutene‐1 increases with decreasing temperatures at the same conversion level. Significantly, the molecular weights increase with conversion and seem to reach their maximum at high conversions. Higher molecular weights were obtained in n‐pentane‐alkyl chloride mixtures than in methyl chloride solution alone. The molecular weights are independent of catalyst concentrations in the range investigated (31.8–7.97 × 10−4 mole/l. AlBr3 and 57.6–28.8 × 10−4 mole/l. AlCl3). The rate of homogeneous polymerization with aluminum bromide in propane solvent was studied. The rate is first order in monomer concentration and catalyst concentration and the rate constant is 0.610 l./mole sec. The apparent activation energy calculated from the Arrhenius plot is 6.57 kcal./mole. In methyl bromide the rate of polymerization increases significantly (effect of the dielectric constant). In toluene the molecular weight as well as the rate is strongly depressed indicating the preponderance of a chain breaking mechanism involving this solvent.
Anionic block polymerization. II. Preparation and properties of block copolymers
Authors: Baer M.
Published: April 2003

Block copolymers were prepared by anionic polymerization and their dynamic mechanical properties and thermal stability were compared with those of random copolymers and mechanical blends of similar composition. The block copolymers were prepared by means of Na‐naphthalene as the initiator, under conditions leading in most cases to almost complete absence of contaminating homopolymers. The composition, structure, and molecular weight of the block copolymers were determined by (a) molecular weight determinations of the polymers before and after addition of the second monomer to the preformed polymeric anions, and (b) by fractionation and chemical analysis of the resulting fractions. The block copolymers prepared were of the type: poly(α‐methyl styrene) ‐ polystyrene ‐ poly(α‐methylstyrene), polystyrene ‐ poly(α‐methylstyrene)‐polystyrene, poly(methyl methacrylate)‐polystyrene‐poly(α‐methyl methacrylate), and poly(ethylene oxide)‐polystyrene‐poly(ethylene oxide). The various block copolymer systems showed considerable differences in dynamic mechanical properties among themselves; they also had properties differing from those of copolymers and blends.
Infrared studies of conformational changes in polyvinyl chloride
Authors: Krimm S. , Enomoto S.
Published: April 2003

Analysis of the infrared spectrum of polyvinyl chloride has permitted the identification, from the frequencies of the several CCl stretching bands, of the chain conformations which are associated with particular chlorine pair configurations. These results have made it possible to establish that changes in conformational structure accompany certain changes in physical state of the polymer. Possible interpretations of the origins of these structural changes are considered.
Effect of film thickness upon the sorption of organic vapors in polymers slightly above their glass transition temperatures
Authors: Kishimoto A. , Matsumoto K.
Published: April 2003

Absorption and desorption of organic vapors in amorphous polymers in the temperature region slightly above Tg were studied as a function of film thickness. The systems chosen for this study were polyvinyl acetate (PVAc)–allyl chloride at 40°C. and polymethyl acrylate (PMA)–methyl acetate at 15 and 35°C. In PVAc studies reduced adsorption curves for different film thicknesses at relatively high equilibrium concentrations were apparently normal, but the initial slopes of the plots increased with increasing film thickness X and appeared to approach certain limiting values at the limit of infinite X. At lower equilibrium concentration two‐stage absorption curves appeared, and the variation of absorption curve with film thickness was too complicated to be interpreted in terms of the theory proposed by Crank and Long and Richman. The desorption curve was at all concentrations studied, almost normal and the initial slopes increased with increasing X. By assuming that the hypothetical sorption curve with the initial slope extrapolated to infinite X is controlled by a purely Fickian diffusion mechanism, we calculated the mutual diffusion coefficient D for this system and compared it with that derived by Meares from steady‐state permeation measurements. Both results agreed quite well, suggesting that the method presented here is effective for obtaining D. Absorption and desorption of methyl acetate by PMA at 15°C. were entirely similar to those obtained by PVAc in the corresponding region of equilibrium concentration. At 35°C. reduced sorption curves were independent of X and were purely Fickian. Following the analysis in PVAc, we predicted D for PMA at 15°C. as a function of methyl acetate concentration.
Polymer degradation. I. Column elution fractionation and thermal degradation of polyoxypropylene glycol–toluene diisocyanate (PPG‐TDI) polymers
Authors: Rapp Neville Sue , Ingham John D.
Published: April 2003

A procedure has been worked out for the column elution fractionation of polyoxypropylene glycol–toluene diisocyanate (PPG‐TDI) polymers of molecular weight ∼100,000; by decreasing the column temperature from 34 to 7°C. the method was extended to degraded polymer of molecular weight ∼25,000. Graphical differentiation of the integral curves was eliminated by using Tung's empirical equations. The results for both degraded and undegraded polymer agreed with the theoretical most probable distributions; therefore, a random scission process of degradation is indicated.
Synthesis of crystalline polyvinylcyclobutane and polyvinylcycloheptane
Authors: Overberger C. G. , Kaye H. , Walsh G.
Published: April 2003

The synthesis of vinylcyclobutane and vinylcycloheptane is described. These compounds were polymerized to crystalline polyvinylcyclobutane and polyvinylcycloheptane with a triisobutyl aluminum–titanium tetrachloride catalyst system.
Mechanism of film formation from latices. Phenomenon of flocculation
Authors: Hwa Jesse C. H.
Published: April 2003

The mechanism of film formation was studied with respect to the flocculation phenomenon. It was observed that almost all latices would air‐dry to a point at which coagulation of the latex particles had just occurred and beyond which the wet film was no longer redispersible in water. This flocculation point was sharp and could be detected visually or by immersing the film in water. Two methods have been devised to measure the solids at which incipient flocculation occurred: cross‐section method, and cone method. The floc point was found to be about 50–60% for a model acrylic latex depending on the soap present in the dispersion. After flocculation had occurred, further drying would lead to different film properties depending on the hardness of the particles, the rate of drying, the substrate, and the degree of crosslinking.
Polymer–solvent interaction parameters and creep behavior of ethylene–propylene rubbers
Authors: Dudek T. J. , Bueche F.
Published: April 2003

The polymer–solvent interaction parameter for an ethylene–propylene terpolymer containing 53 mole‐% ethylene was determined as a function of degree of crosslinking in n‐heptane and benzene. A well characterized EPR gum vulcanizate was used to obtain the polymer–solvent interaction parameter in fourteen solvents, and the cohesive energy density of the terpolymer was evaluated. The composite tensile creep curves for gum and filled EPR vulcanizates were obtained and compared with SBR creep curves.
Some factors affecting the molecular association of poly(ethylene oxide) and poly(acrylic acid) in aqueous solution
Authors: Bailey F. E. , Lundberg R. D. , Callard R. W.
Published: April 2003

Investigations of the properties of very high molecular weight polymers of ethylene oxide have shown that, while this polymer structure is relatively nonpolar, it displays a high degree of polymer solvent interaction in aqueous systems. A unique application of the hydrogen bonding affinity of the ether oxygens in the poly(ethylene oxide) chain has been found in the molecular association complexes formed between this polyether and polymeric acids such as poly(acrylic acid). Interest in the properties of these complexes has prompted a more detailed study of the mechanism of association which occurs in solution. In this study the effects of pH, of composition and concentration, and of temperature on solution viscosity are examined in order to define the stoichiometry of the intermolecular association. A wide range of polymer molecular weights has been studied, ranging in the case of poly(ethylene oxide) from low molecular weight waxes to very high molecular weight polymers. The molecular complex of poly(ethylene oxide) and poly(acrylic acid) appears to be an association between ether oxygens and carboxyl groups through hydrogen bonding which approaches 1:1 stoichiometry. While at low pH this association is sufficient to cause phase separation, at higher pH the complex exists in solution. In neutral solution there also appears to be an interaction between the two polymer species.
Compositions in equilibrium two phases of polymer–solvent mixture systems
Authors: Yoshino Tsuneo , Fujisawa Kenji
Published: April 2003

The compositions in equilibrium two‐liquid phases of polymer–solvent mixture systems have been studied from the standpoint of preferential adsorption of one solvent component by measuring φout, νv, and V/m for toluene–isobutanol–polystyrene systems. Here φout is the volume fraction of toluene in the solvent mixture outside the adsorbed regions surrounding polymer molecules; ν′ is the volume of hypothetical toluene layers per unit weight of polymer substance, when the adsorbed regions are divided into pure toluene layers and the remaining parts with solvent composition equal to φout, keeping the amount of toluene in the adsorbed regions unchanged; and V/m is the volume of solvent per unit weight of polymer substance. ν′ is observed to be equal for both the polymer‐poor and polymer‐rich phases and independent of polymer concentration, so far as the polymer concentration in the latter phase is smaller than 0.2 g./cc. solvent, φout is found to be also equal for the both phases. These observations show that the ternary system at a temperature is approximated by a binary system consisting of polymer molecules which are composed of true polymer molecules and the toluene layers surrounding them, and solvent mixture outside the toluene layers. When V/m and ν′ in the polymer‐rich phase are plotted against decreasing φout, ν′ begins to decrease at φout = 0.6, where the change of V/m along a steep curve for φout > 0.6 is slowed down. This suggests that after the polymer‐rich phase is deprived of most of the solvent outside the adsorbed regions the adsorbed regions begin to lose solvent. The magnitude of the adsorbed regions per unit weight of polystyrene in a dilute solution with φout > 0.6 is estimated to be about 5 cc./g. from V/m of a polymer‐rich phase with φout = 0.6.
An interpretation of gaseous diffusion through polymers using fluctuation theory
Authors: DiBenedetto A. T. , Paul D. R.
Published: April 2003

An amorphous polymer is visualized as an ensemble of N independent, n‐center polymer segments. An ergodic hypothesis and a canonical ensemble are utilized in determining the probability of a given volume fluetuation within the polymer. The thermal energy change associated with a given volume fluctuation is calculated and related to the activation energy for gaseous diffusion. Polymer segment lengths were in the range of 6–20 A. and appeared to decrease with increasing temperature in the case of natural rubber. The results were interpreted to show that the activation energy for gaseous diffusion in rubbery polymers went into the breaking of cohesive bonds between parallel polymer segments while in glassy polymers it went into both the breaking of cohesive bonds and the compressing of the surrounding segments. It is felt that it may be possible to relate gaseous diffusion, self‐diffusion, and viscous flow to the thermodynamic and molecular properties of an amorphous polymer.
Evaluation of molecular weight averages resulting from random chain scission process for wide distributions as in polyolefins
Authors: Kotliar A. M.
Published: April 2003

The effects of random degradation on the molecular weight averages for broad Schulz‐Zimm and Wesslau type distributions are evaluated by blending two most probable Flory type distributions so that the Mn:Mw:Mz ratios of the blend were equal to that of the distribution models for any particular Mw/Mn ratio. The results indicate a rather extreme sensitivity of broad Wesslau distributions to small degrees of degradation and suggest that this function is not a good description for polyolefins.
Polymerization of butyl esters of methacrylic acid and hydrolysis of the polymers
Authors: Matsuzaki Kei , Okamoto Takehiko , Ishida Akira , Sobue Hiroshi
Published: April 2003

tert‐Butyl methacrylate was polymerized with Grignard reagent, benzoyl peroxide, and gamma rays as initiator. The infrared spectra of the polymers indicated that the polymer polymerized with Grignard reagent had an isotactic stsucture and those polymerized with benzoyl peroxide and gamma rays had syndiotactic structures. Hydrolysis of polymethyl methacrylates and poly‐tert‐butyl methacrylates with hydroiodic acid was attempted, and differences in the infrared spectra of the polymethacrylic acids obtained due to stereoregularity were discussed. No difference in the demethylation behavior due to stereoregularity of polymethyl methacrylates was observed. Heat treatment of polymethacrylic acids and poly‐tert‐butyl methacrylates showed that isotactic polymers form polymer anhydride faster than syndiotactic polymers.
Molecular weight distributions in equilibrium polymerizations
Authors: Lundberg J. L.
Published: April 2003

Molecular weight distributions at polymerization equilibria appear to fall between two limiting cases, one which gives a “most probable” distribution and one which gives a very broad distribution. The difference between the two results depends on whether entropies of pure, crystalline homopolymers or pure, unoriented liquid homopolymers are proportional to molecular size. The free energies of polymerization of liquid homopolymers of ethylene can be estimated from published thermodynamic data if the entropies of pure, disoriented, liquid homopolymers are assumed to be proportional to molecular size. This leads to the expectation that molecular weight distributions are very broad for equilibrium polymers. For polyethylenes at polymerization equilibria, weight‐average/number‐average degree of polymerization ratios of 6 to 33, high weight‐average degrees of polymerization (102 ≤ nw ≥ 1014), and equilibrium monomer fugacities from 10−10 to 102 atm. are predicted at temperatures of 300–600°K. and at total pressures in the 1–104 atm. range. These results are consistent with molecular weights and molecular weight distributions found for nonequilibrium polyethylenes. This agreement indicates that ethylene polymerizations might be controlled in part by energetics and not by kinetics alone.
Aromatic polyhydrazides: A new class of highly bonded, stiff polymers
Authors: Frazer A. H. , Wallenberger F. T.
Published: April 2003

High‐molecular weight aromatic polyhydrazides have been prepared by using isophthalic, terephthalic, isocinchomeronic, dipicolinic, 5‐chloroisophthalic, 2,5‐dichloroterephthalic, 5‐tert‐butylisophthalic, phenyl ether‐4,4′‐dicarboxylic, pyrazine‐2,5‐dicarboxylic, and thiophene‐2,5‐dicarboxylic acid as polymer intermediates. The polyhydrazides were prepared from equimolar amounts of diacid chloride and dihydrazide (or hydrazine) in hexamethylphosphoramide at room temperature. By contrast to aliphatic polyhydrazides, aromatic polyhydrazides were soluble in dimethyl sulfoxide and with few exceptions had polymer melt temperatures in the range of 350–400°C. Inherent viscosities ranged from 0.30 to 1.00 (in dimethyl sulfoxide). Tough films and strong fibers of these polymers could be fabricated.
Thiaalkyl polyacrylates: The influence of sulfur in the side chain
Authors: McCurdy Richard M. , Prager Julianne H.
Published: April 2003

A series of acrylic esters containing a thio ether atom in the side chain has been prepared and polymerized. The glass transition temperatures and swelling volumes are reported as follows: 3‐thiabutyl polyacrylate, Tg −60°C., 9% volume swell in 70:30 isooctane‐toluene; 3‐thiapentyl polyacrylate, −71°C., 31% 4‐thiapentyl polyacrylate, −65°C., 32% 4‐thiahexyl polyacrylate, −76°C., 36% 5‐thiahexyl polyacrylate, −70°C., 36%. These data are compared with those for certain other polyacrylates; the relation between the structure and the properties of these materials is discussed.
Water cocatalysis in the polymerization of benzene by ferric chloride
Authors: Kovacic Peter , Koch Fred W. , Stephan Charles E.
Published: April 2003

The influence of change in water cocatalyst concentration on polymer yield and composition, and on reaction rate was investigated in the benzene‐ferric chloride system. For short reaction times, polymer yield passes through a maximum at a H2O/FeCl3 molar ratio of 1. The most rapid rate of hydrogen chloride evolution was observed at this same ratio. The data suggest that ferric chloride monohydrate constitutes the active catalyst‐cocatalyst complex. With more prolonged reaction times, the yield maximum shifted to lower values of H2O/FeCl3, accompanied by a progressive increase in polymer yield. As evidenced by the C/(H + Cl) atomic ratio, p‐polyphenyl formation is favored by short reaction times at H2O/FeCl3 ratios of 0, 1, and 2. Longer reaction times, gave C/(H + Cl) ratios greater than 1.5 for the polymer, indicating the presence of polynuclear structures. An increase in chlorine content attended the rise in C/(H + Cl) ratio. Interpretations of the data are presented.
Light‐scattering study of the oxidative degradation of polystyrene
Authors: Spitsbergen James C. , Beachell Harold C.
Published: April 2003

An investigation into the nature of the structural and molecular changes during the bulk oxidation of polystyrene has been conducted by light‐scattering and viscometric methods. Oxidations were conducted on films in an air oven at 0, 2, 4, and 5 hr. at 200°C. The oxidized films were dissolved and various parameters obtained on the resulting solutions. Fractionation of unoxidized and oxidized thermally polymerized polystyrene showed a narrowing of the molecular weight distribution during oxidation. The weight‐average molecular weight decreased from 1,090,000 to 33,000. That of an unfractionated commercial polystyrene, Styron 683K, decreased from 281,000 to 16,000. These results show that random chain scission of oxidize polymer occurs along with the formation of carbonyl groups giving polymer molecules of shorter chain length most of which probably retain the initial linear random coil structure. In addition to the chain scission, branching and crosslinking are indicated by the distortion of Zimm plots by microgel.
Polysulfones of norbornene and derivatives
Authors: Hill Edward H. , Caldwell John R.
Published: April 2003

Norbornene and some of its monosubstituted and disubstituted derivatives reacted with sulfur dioxide to give polysulfones. These polysulfones are very stable thermally, compared to those of 1‐butene and cyclohexene. Their stability can be further improved by using tin(II) oxide or thioacetamide as stabilizers. The polysulfones of norbornene and its derivatives have very high polymer melt temperatures.
Electron spin resonance studies of irradiated polypropylene
Authors: Forrestal Lloyd J. , Hodgson William G.
Published: April 2003

Polypropylene has been irradiated at −196°C. and its electron spin resonance spectra studied at temperatures between −196°C. and room temperature. The intensity of the eight‐line spectrum observed at −196°C. corresponded to a G for radical production of 3.3. The spectrum could be reconstructed from theoretical curves assuming equal concentrations of radicals with four‐ and eight‐line spectra. On warming to room temperature the radical concentration was reduced to 30% of the initial concentration. In experiments in which the sample was warmed to −100°C. no change in radical concentration was observed. Annealing experiments at temperatures between −100°C. and the glass transition temperature showed that at each temperature there was a rapid decay of radicals after which no further change in radical concentration took place. Above the glass transition temperature a continuous decay occurred. The onset of decay above −100°C. may be associated with the onset of segmental motion in the amorphous regions of the polymer. The rapid decay of the radicals suggests that they are formed near each other as the results of hot hydrogen atom reactions.
Nature of the price‐alfrey q and ε parameters
Authors: Charton Marvin , Capato Anthony J.
Published: April 2003

The equation, εX = mεX + c, has been derived from the Price‐Alfrey and Hammett equations. The σp constants give the best correlation. With multiple substituted monomers, the equation εX,Z = m (σX + σZ) + c has been found to be applicable. Thus the ε parameter is found to be a function of both inductive and resonance effects. The equation qX = nσX + d has been derived from the Price‐Alfrey and Hammett equations. Correlations of qx have been attempted with a number of substituent constants. The correlation, though generally best with σp and related constants, remains poor, even in series in which steric effects should be constant.
Rapid characterization of ion‐exchange resins by NMR
Authors: de Villiers J. P. , Parrish J. R.
Published: April 2003

The proton magnetic resonance spectrum of an ion‐exchange resin is often characteristic of that type of resin. It has been shown that the internal molality of a strongly acidic or strongly basic polystyrene resin can be determined from its NMR spectrum.
Intramolecular hydride shift polymerization by cationic mechanism. I. Introduction and structure analysis of poly‐3‐methylbutene‐1
Authors: Kennedy J. P. , Minckler L. S. , Wanless G. G. , Thomas R. M.
Published: April 2003

The low temperature cationic polymerization of 3‐methylbutene‐1 proceeds by intramolecular hydride shift mechanism. The secondary carbonium ion
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rearranges to a tertiary one
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prior to propagation. Thus the repeat unit of cationically obtained poly‐3‐methylbutene‐1 is not the expected
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or 1,2 structure but an α,α′‐dimethylpropane‐type 1,3 unit, e.g.,
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A novel diels‐alder polymerization
Authors: Stille J. K. , Anyos T.
Published: April 2003

The double dienophilesN,N′‐hexamethylene‐bismaleimide and theo‐,m‐, andp‐phenylene‐bismaleimides were prepared and copolymerized with benzalazine by the Diels‐Alder reaction. Melt polymerization afforded these polymers in high yields with inherent viscosities in the range 0.13 to 0.30 and softening temperatures from 238 to 325°. Solution polymerization gave no polymers and only starting materials were isolated. Benzalazine in this reaction behaves as a double diene and undergoes a 1,3‐addition with the bismaleimides to form these polymers. That this 1,3‐addition occurs in the polymer formation is further verified by the basic hydrolysis of the model compounds, 4,8‐diphenyl‐1,5‐diazabicyclo[3.3.0]octane‐2,3,6,7‐tetracarboxylic acid bisanhydride (I) and 4,8‐diphenyl‐1,5‐diazabicyclo[3.3.0]octane‐2,3,6,7‐bis‐n‐butylamide (II) and one of the polymers to give 4,8‐diphenyl‐1,5‐diazabicyclo[3.3.0]octane‐2,3,6,7‐tetracarboxylic acid in each case.
Catalytic polymerization of glycine ethyl ester
Authors: Carter Mary E. , Carlson O. K.
Published: April 2003

Polyglycines have been prepared in good yields from glgcine ethyl ester with a new catalyst system, aluminurn isopropoxide and/or diisopropoxide aluminum chloride. A random sttitisticsl experiment was pcrfornied to optimize the bulk stage polymerization conditions. The reaction mechanism proposed hegins as in the Meerwein‐Ponn‐dorf‐Verley reduction with an attack by the aluminum on the carbonyl oxygen and is dependent on an arnintrcsrbonyl entity which allows the romplexcd aluminurn to approach a eeeond carbonyl.
Determination of molecular weights of polymers by procedure X in stress relaxation
Authors: Sobue Hiroshi , Murakami Kenkichi , Hoshino Hiroyuki
Published: April 2003

τm, defined as the maximum relaxation time, was shown in previous papers to be one of the elements characterizing the “box” type curve in the rubbery region of a linear amorphous polymer, and a new procedure called procedure X was proposed to obtain τm. The relation among τm, weight‐average chain length nw, temperature T, and characterized temperature Ti (glass transition temperature Tg, WLF temperature Ts, or Tobolsky's temperature Td) was indicated by an equation, with which constant values of log A depending on the kind of polymer were obtained for several polymers in the regions of M ≫ Mc. For polymers in the vicinity of Mc, another set of constant values of log A′ was obtained. Finally, the effect of τm on temperatures for a polymer was studied.
Rubber elasticity in highly crosslinked polyethyl acrylate
Authors: Katz Dov , Tobolsky Arthur V.
Published: April 2003

Copolymers of ethyl acrylate with three different dimethacrylates were prepared over the complete range of copolymer composition. Modulus temperature curves of these polymers were constructed and contrasted with the modulus temperature curves of phenol–formaldehyde type polymers. The ethyl acrylate–dimethacrylate polymers appeared to have rubbery plateau regions at high temperatures, even for very high mole percentages of dimethacrylate. This was especially true if the dimethacrylate molecule had a long flexible chain within it, as in tetraethylene glycol dimethacrylate. On the other hand the phenol–formaldehyde type polymers and polyethylene glycol dimethacrylate did not appear to have rubbery plateau regions. Up to 12 mole‐% of dimethacrylate the shear moduli of the ethyl acrylate copolymers in the rubbery plateau region were independent of the structure of the dimethacrylate at equivalent crosslink concentrations. Furthermore these polymers appear to obey the laws of ideal rubber elasticity with a front factor of unity.
Structures of vinylidene chloride–vinyl chloride copolymers
Authors: Okuda Kensuke
Published: April 2003

The relationships between composition and structure of vinylidene chloride (VDC)–vinyl chloride (VC) copolymer were investigated by various methods such as x‐ray wide‐angle and small‐angle scattering, electron diffraction and microscopy, thermal analysis, and high resolution nuclear magnetic resonance. The copolymers used were made by suspension copolymerization below 5% conversion. The crystalline regions are fundamentally ismorphous to polyvinylidene chloride (PVDC) for the VDC–VC copolymers in the composition range from 1 to 0.560 in terms of the molar fraction of VDC (0.560 VDC). In the composition range below 0.145 VDC, the copolymers form crystallites isomorphous to polyvinyl chloride. The copolymers having the intermediate compositions are amorphous. In the composition range above 0.560 VDC, the average crystallite sizes of the uniaxially oriented specimens are almost constant; on the contrary, the long periods increase with decrease of the molar fraction of VDC. The intensities of the long‐period diffraction peaks show a maximum for the copolymer in which the molar fraction of VDC is 0.685. The crystallinities, which were estimated from the x‐ray method, decrease with decrease of the VDC fraction. The melting point depression is so small that it cannot be explained by Flory's equation. The results of NMR indicate that a large percentage of VC monomer units exists as sequences even in VDC‐rich copolymers. PVDC and the VDC–VC copolymers higher than 0.745 VDC crystallize in the form of layer crystal aggregates from monochlorobenzene solutions. The molecules are sharply folded within these layers. The average crystallite sizes and long periods of the solution growth crystals are almost constant. These experimental facts cannot be interpreted in the terms of the structure which is expected by the copolymerization theory, but may be explained only on the basis of the molecular structure model which means the copolymer has a kind of block‐type structure.