bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress‐cracking of polyethylene examined from the viewpoint of critical strain
Authors: Tung L. H.
Published: April 2003

Stress‐cracking in polyethylene has been examined from the viewpoint of critical strain based on a proposed theory for the formation of the cracks. Stress‐cracking under constant load and constant strain was determined experimentally at 60°C. on a 3.5 melt index high‐density polyethylene. A critical strain of 1.95% associated with a critical relaxation time of 90 min. was found for the sample. Good agreement was found between the theory and experiments made in Igepal CO 630. Some disagreements between the theory and experiments made in air were attributed to the rate of propagation of the cracks.
Rates of sulfonation of polystyrenes crosslinked with pure p‐, 2:1/m:p‐, and commercial divinylbenzenes
Authors: Wiley Richard H. , Venkatachalam T. K.
Published: April 2003

Data for the rates of sulfonation of polystyrene crosslinked with 2, 4, and 8% pure p‐, 2:1/m:p‐, and commercial divinylbenzenes at 60 and 80°C. have given activation energies varying from 11,520 to 40,190 cal./mole. Rates are lowest and activation energies highest for the p‐divinylbenzene crosslinked structures. This is attributed to differences in rates of diffusion through the different types of network structures and is consistent with previously noted decreased swelling ratios for the para crosslinked types.
Dye‐sensitized photopolymerization. III. Structural effects of thiazine dyes
Authors: Chen Catherines S. Hsia
Published: April 2003

Photopolymerization of aqueous acrylamide was investigated by use of mixtures of thiazine dyes with different structural features and triethanolamine as sensitizers. New methylene blue N (I), with two electron‐donating methyl group in the 2‐ and 10‐ positions, and methylene green (III), with an electron‐withdrawing nitro group in the 2‐position of methylene blue (II, 3,9‐bisdimethylaminophenazothionium chloride) were employed. Induction periods for polymerization were observed for both I and III: the kinetics thereafter were of similar nature to those reported for II.1 The lengths of the induction period were in the order of III > II > I. The rate of polymerization and the quantum yield were in the order of III > II > I. In combination with an anionic dye (eosin Y) in an equivalent ratio of 7:6, spectroscopy indicated interaction between both I and eosin Y and III and eosin Y, III–eosin Y interaction was of similar nature to II–eosin Y interactions, but to a lesser extent. Interaction between I and eosin Y, however, was of a different nature. Results in polymerization showed that enhancement in rate was observed for III–eosin Y but not for I–eosin Y. The order of enhancement was thus II > III > I.
Graft copolymerization onto cellulose by the ceric ion method
Authors: Iwakura Yoshio , Kurosaki Toshikazu , Imai Yohji
Published: April 2003

Styrene was polymerized in ceric salt–alcohol redox systems and hydroxyl endgroups on the polystyrene obtained were characterized quantitatively by the spectrophotometric determination of the polymer treated with p‐phenylazophenyl isocyanate. A series of polymerization of acrylamide initiated in redox systems of ceric salt and various alcohols was studied as a model system for graft copolymerization onto cellulose. From studies of the rate of polymerization it was shown that the grafting was likely to occur at hemiacetal and 1,2‐glycol units. The cellulose–styrene graft copolymer was isolated from the reaction products by a selective extraction technique and characterized by acetolysis of the cellulose backbone. The graft copolymers obtained were found to be a mixture of block and graft copolymers.
Study of hydrocarbon‐soluble organometallic catalysts. I. Correlations between catalytic activity and electric conductivity of Al(C2H5)3–Ti(OC4H9)4 catalysts in the synthesis of stereoregular polyacetylene
Authors: Nicolescu I. V. , Angelescu Em.
Published: April 2003

The correlation between the catalytic activity of the system Al(C2H5)3–Ti(OC4H9)4 and its electrical conductivity in stereospecific polymerization was investigated. The activity of the catalyst was evaluated for varying molar ratios of Al/Ti (in the range of 0.75–6) and reaction temperatures (in the range of −78 to +70°C.) by means of the velocity of absorption of the acetylene. The ionic state of the catalytic complex may be assessed on the basis of electrical conductivity measurements. The electrical conductivity of the pure state of the two catalyst components is in the range of 10−12 or 10−10 (ohm‐cm.)−1 while that for the catalyst complex is of the order of 10−8 (ohm‐cm.)−1. The experimental data prove the existence of a correlation between the velocity of reaction, the composition of the catalyst complex, and the electrical conductivity. The values obtained for the activation energy of the electrical conductivity correlate with the energy required to break the complex ion aggregate of the catalyst and therefore with the activity of the catalyst.
Branching in poly(butadiene‐co‐styrene). II. Radiation‐induced branching examined by viscometry
Authors: Blachford J. , Robertson R. F.
Published: April 2003

The dependence of intrinsic viscosity on radiation dose has been examined for poly(butadiene‐co‐styrene) irradiated in vacuo and for mixtures of this polymer and N‐phenyl‐β‐naphthylamine irradiated in air and in vacuo. If no correction is made for crosslinking in the unirradiated polymer, theories examined appear to overestimate the increase in intrinsic viscosity. However, if it is assumed that in the unirradiated polymer the number of crosslinked units per weight‐average primary molecule δ0 is 0.65, the results agree with the theory of Spiro which uses the Stockmayer‐Fixman relation between intrinsic viscosity and branching. The dose required for incipient gelation, Rg, was determined for the various samples. These results were used together with the number‐average molecular weight of the unirradiated polymer and with assumed values of δ0 to calculated values of Gx, the number of crosslinks formed per 100 e.v. of radiation energy absorbed by the sample. Good agreement with solubility and swelling results, reported elsewhere, was obtained if δ0 = 0.9.
Branching in poly(butadiene‐co‐styrene). III. Radiation‐induced branching examined by solubility and swelling
Authors: Blachford J. , Robertson R. F.
Published: April 2003

The dependence of solubility and swelling on radiation dose has been examined for pure polymer and polymer containing varying amounts of the antioxidant N‐phenyl‐β‐naphthylamine. Degradation did not occur when samples were irradiated in vacuo but in the presence of air degradation was initiated and crosslinking was retarded. During irradiation in vacuo the antioxidant interacted with the polymer and prevented the formation of a large number of crosslinks. An analysis of the solubility data indicated that there were 0.9 crosslinked units per weight‐average primary molecule in the unirradiated polymer, and that 1.59 crosslinks were formed in the pure polymer on the absorption of 100 e.v. of radiation energy (i.e., Gx = 1.59). These values are consistent with the swelling data but not with the experimentally determined molecular weight distribution.
Kinetics of polymerization of styrene initiated by substituted benzoyl peroxides. III. Induced decomposition
Authors: O'Driscoll K. F. , Lyons P. F. , Patsiga R.
Published: April 2003

The polymerization of styrene has been initiated by redox systems consisting of diethylaniline and symmetrically substituted benzoyl peroxides. Decomposition rate constants and efficiencies of initiation were determined by the dead‐end technique. Hammett plots of these rate constants and of those previously determined for polystyryl‐radical induced decomposition of substituted benzoyl peroxides have the same slope, suggesting that an SH2 mechanism is involved in the radical attack on peroxides just as in the radical attack on disulfides. The predictive ability of a combined Hammett‐type equation was shown to be excellent for the decomposition rate constants of initiating systems consisting of both substituted diethylaniline and substituted benzoyl peroxide. The effect of substituents on the efficiency of initiation remains unexplained.
Synthesis and polymerization of N[2‐(2‐methyl‐4‐oxopentyl)]‐acrylamide–A new reactive vinyl monomer
Authors: Coleman L. E. , Bork J. F. , Wyman D. P. , Hoke D. I.
Published: April 2003

The synthesis and polymerization reactivity of N[2‐(2‐methyl‐4‐oxopentyl)]‐acrylamide (diacetone acrylamide) is described. This reactive vinyl monomer is prepared in good yield from acetone, acrylonitrile and sulfuric acid. Diacetone acrylamide is a white crystalline solid with the water solubility characteristics of acrylamide and the organic solvent solubility of N‐alkyl acrylamides. Diacetone acrylamide readily homopolymerizes and forms copolymers with a wide variety of comonomers. Reactivity ratios in the copolymerization of diacetone acrylamide with styrene and methyl methacrylate are reported and the Alfrey‐Price Q and e values calculated. These results, along with data from the copolymerization of diacetone acrylamide with a group of typical vinyl monomers, are presented to indicate the high reactivity of this new monomer.
Glass temperatures of mixtures of compatible polymers
Authors: Krause Sonja , Roman Nicholas
Published: April 2003

Dilatometric glass transition temperatures were measured on mixtures of isotactic and syndiotactic poly(methyl methacrylate) and on mixtures of poly(isopropyl acrylate) with poly(isopropyl methacrylate). The glass temperatures of copolymers of isopropyl acrylate with isopropyl methacrylate fall on the same glass temperature versus composition curve as those of the homopolymer mixtures. The data are compared with theoretical predictions of Fox, Gordon and Taylor, and Kanig. None of these treatments can adequately explain the results.
Analysis of relaxation constants in polyurethanes
Authors: Singh Ajaib , Weissbein Leonard
Published: April 2003

A simple Maxwell model is shown to be inadequate in describing stress‐relaxation behavior of polyurethanes at 120°C. These data fit better to a multi‐Maxwell model. Various relaxation parameters contributing to the thermal degradation of polyurethanes have been resolved, and their significance is discussed.
A dye partition method for the determination of hydroxyl endgroups in polymers
Authors: Ghosh Premamoy , Sengupta Pranab K. , Pramanik Ananda
Published: April 2003

A dye partition method for the determination of hydroxyl endgroups in poly(methyl methacrylate) samples prepared in aqueous media with the use of hydrogen peroxide as the photoinitiator has been described. The dried polymers were treated with chlorosulfonic acid under suitable conditions whereby the hydroxyl endgroups present in them were transformed to sulfate endgroups. Spectrophotometric analysis of sulfate endgroups in the treated polymers was carried out by the application of the dye‐partition technique developed for the purpose, and thus a measure of hydroxyl endgroups in the original polymers was obtained. H2O2, in the concentration range of 0.004–0.1M, was found to incorporate an average of nearly 1 OH endgroup per polymer chain.
Free radical chain transfer to allyl monomers at low polymerization temperatures
Authors: Dawson T. L. , Lundberg R. D.
Published: April 2003

Alkylboron–oxygen, an active, low‐temperature free radical initiator, has been employed to investigate the effects of very low polymerization temperatures on the free radical homopolymerization and copolymerization of allyl monomers. Unlike some polymerizations which have been reported to undergo dramatic changes in polymerization rates at very low polymerization temperatures, the allyl systems behaved in a like manner at high and low temperatures. Similar, low values of reduced viscosities were obtained for homopolymers of allyl monomers prepared over a 300°C. temperature range. An almost identical effect of allyl chloride concentration on the molecular weight of ethyl acrylate/allyl chloride copolymers was also observed for copolymerizations performed over a 100°C. temperature range. For solution homopolymerizations and copolymerizations the activation energy for free radical abstraction from the allyl monomer is, therefore, nearly equal to the activation energy for addition of that radical to the allyl double bond, even at temperatures down to the melting points of the monomers.
Hydrodynamic behavior of fully acetylated guaran. Test of the Eizner‐Ptitsyn theory for the semirigid macromolecule
Authors: Kurath Sheldon F. , Schmitt Charles A. , Bachhuber John J.
Published: April 2003

Previous results on the hydrodynamic and configurational properties of fully acetylated guaran in acetonitrile have been reexamined in light of the recent Eizner‐Ptitsyn theory for the intrinsic viscosity of the semirigid macromolecule. Numerical values for the hydrodynamic function arising in the theory were calculated by numerical summation on an electronic computer and are tabulated. The theory is found to remove some of the inconsistencies inherent in earlier hydrodynamic theories and leads to reasonable values of the persistence length and monomeric friction coefficient of guaran acetate. The persistence length calculated from viscosity data was 57.8 A., only slightly lower than the limiting value of 64 A. obtained from light scattering. The ratio of monomeric friction coefficient to solvent viscosity was ζ/η0 = 6πr0 = 57.3 A., from which a value of r0 = 3.04 A. was obtained for the hydrodynamic radius of the monomer unit.
Investigation of the elastic properties of the particle network in gelled solutions of hydrocolloids. I. Carboxymethyl cellulose
Authors: Hermans Jan
Published: April 2003

In order to obtain information on the structure of the particle network existing in gelled solutions of carboxymethyl cellulose, the elastic modulus was determined of series of dilutions of three samples of different molecular weight. It was found that these results could be accounted for reasonably well with the assumptions (1) that the crosslinking of molecules can be described as a reversible bimolecular aggregation between surface sites, (2) that the network formed may be described by Flory's theory of gelation and (3) that the network is deformed according to the theory of rubber elasticity.
Proton magnetic resonance spectra of variously treated nylon 66
Authors: Glick R. E. , Phillips R. C.
Published: April 2003

A proton NMR study on variously treated nylon 66 has been made to gain additional information on hydrogen bonding in solids. The nylon sample was found to be 48% amorphous based on the deuterium exchange of amide protons. The broad line NMR spectra of all samples consisted of a superposition of a broad and narrow component at all temperatures studied. Dried nylon and dried deuterated nylon afforded identical NMR spectra. This identity was interpreted as indicating a possible electrostatic rather than overlap description of hydrogen bonds in amorphous regions. Additives, such as water, deuterium oxide, methanol, and deuterium methoxide, lowered the temperature at which the narrow‐component line width was further reduced. Such effect was consistent with other studies that indicated such additives were associated with hydrogen bonds in amorphous regions of the polymer. This effect appeared to saturate at a concentration of additive equal to that for the amide functions in the amorphous regions. Contrary to our previous studies, little difference in spectra were found for proteo and the corresponding deutero additives.
Characterization of emulsion polyethylene
Authors: Kurz James E.
Published: April 2003

Polyethylene which was made by emulsion polymerization was characterized by means of osmometry, light scattering, and viscometry. The samples have unusually high weight‐ and number‐average molecular weights. Low molecular weight polymer which is usually present in commercial polyethylenes was not detected. The data indicate a compact, highly ramified molecular structure. The light‐scattering data suggest each latex particle is made up of essentially one giant molecule which swells but does not dissolve in organic solvents at 100°C. Swelling factors calculated from viscosity and lightscattering data indicate low degrees of crosslinking. A clear distinction cannot be made between a highly long‐chain branched structure and the crosslinked structure of microgels. Of the low‐density polyethylene, 1–2 wt.‐% is made up of molecules which have a comparable structure. In contrast, the greatest portion of the experimental samples is composed of the high molecular weight, highly ramified molecules.
Copolymerization of 2,6‐dimethyl‐4‐bromophenol with 2‐methyl‐4‐bromo‐6‐allylphenol and other p‐bromophenols
Authors: Tsou K. C. , Hoyt H. E. , Halpern B. D.
Published: April 2003

A series of poly(phenylene oxide) copolymers was prepared from 2,6‐dimethyl‐4‐bromophenol and 2‐methyl‐4‐bromo‐6‐allylphenol by the Price method of interfacial oxidative coupling. The physical and chemical properties of the copolymers were correlated with the molar proportions of the bromophenols. The thermosetting rates were proportional to the concentration of the allyl function and were of interest in the development of high‐temperature thermosetting resins and adhesives. The preparation and copolymerization of 2‐methyl‐6‐(α‐methallyl)‐4‐bromophenol were also investigated. Homopolymerization of 2‐methyl‐4‐bromophenol or 2,2′‐methylenebis‐(4‐bromo‐6‐methylphenol) under the same conditions did not occur to any significant degree. When these bromophenols were used in attempted copolymerizations with 2,6‐dimethyl‐4‐bromophenol, only low molecular weight homopolymers of the latter were obtained. The effect of these nonpolymerizing bromophenols as chain stoppers is discussed in connection with the mechanism for this type of polymerization.
Dissolution and crystallization temperatures of high polymers. II. New method of characterization of polyacrylonitrile
Authors: Chiang R.
Published: April 2003

Polyacrylonitriles prepared under different conditions have similar infrared spectra, x‐ray diffraction patterns, and densities, but they show marked differences in dissolution and crystallization behavior. On the basis of the dissolution and crystallization behavior, a characterization method, sensitive enough to show a small difference in chain regularity in the polymer, yet independent of the physical state and previous history of the sample, has been developed. With this method, polyacrylonitriles with different chain regularities can be conveniently differentiated.
Polymerization of vinylphosphonium compounds
Authors: Rabinowitz Robert , Marcus Ruth
Published: April 2003

The mechanism of the ionizing radiation‐initiated polymerization of aqueous solutions of tributylvinylphosphonium bromide (TBVPB) to high molecular weight polymers was established to be free radical. Similar polymerization was observed in acetone, acetonitrile, and acetic acid. The failure of even high radiation doses to induce the polymerization of TBVPB when in chlorobenzene solution was explained on the basis of the interaction of chlorine atoms with bromide ions. Triethylvinylphosphonium bromide, tricyclohexylvinylphosphonium bromide, and dimethylphenylvinylphosphonium bromide gave little or no polymer using conditions which polymerized TBVPB almost completely. Conventional oxidizing peroxidic free radical catalysts failed to initiate the polymerization of TBVPB. Nonoxidizing materials like di‐tert‐butyl peroxide and azo compounds did catalyze the polymerization to give high molecular weight polymers. Apparently the oxidizing peroxides are quickly reduced by the bromide ion before any homolytic cleavage can occur. Tributylvinylphosphonium chloride was polymerized in aqueous solution using potassium persulfate, the homolytic cleavage of persulfate competing favorably with redox processes involving the chloride ion. Copolymerization of TBVPB with a series of common monomers resulted in copolymers containing varying amounts of phosphorus in the expected order.
Cyclo‐ and cyclized diene polymers. IV. Infrared spectra of cyclopolyisoprenes and cyclized polyisoprenes
Authors: Kössler I. , Vodehnal J. , Štolka M.
Published: April 2003

The infrared absorption bands which appear in cyclized polyisoprenes (cis‐1,4‐,trans‐1,4‐, and 3,4‐) and in ladder cyclopolyisoprenes have been divided into three groups: (1) absorption bands typical of six‐membered saturated rings, (2) bands characteristic of endgroups, and (3) absorption bands which have their origins in chemically bound solvent from transfer reactions. The assignment of these bands to probable modes of vibration has been made.
Aromatic polybenzoxazoles
Authors: Moyer W. W. , Cole Carl , Anyos T.
Published: April 2003

The polymerization of 3,3′‐dihydroxybenzidine with the phenyl esters of phthalic, isophthalic, terephthalic, and 5‐chloroisophthalic acids yielded a series of aromatic polybenzoxazoles exhibiting high thermal stability. Melt polymerization afforded these polymers in quantitative yield with inherent viscosities in the range of 0.20–1.04 and thermal stability very similar to those obtained with the aromatic polybenzimidazoles. Homopolymerization of 3‐amino‐4‐hydroxybenzoic acid and 4‐amino‐3‐hydroxybenzoic acid was achieved through the preparation of an intermediate poly(ester‐amide) followed by thermal cyclization (at 250–300°C.) to the benzoxazole unit. Six model compounds containing the benzoxazole unit were prepared for use as standards of reference. These were 2‐phenylbenzoxazole, 2,2′‐p‐phenylene‐bisbenzoxazole, 2,2′‐m‐phenylene‐bisbenzoxazole, 2,2′‐o‐phenylene‐bisbenzoxazole, 2,2′‐(5‐chloro‐1,2‐phenylene)‐bisbenzoxazole, and 2,2′‐(diphenyl)‐6,6′‐bibenzoxazole.
Interaction of ethylaluminum dichloride with organic nitrogen and phosphorus compounds in three‐component polyolefin catalysts
Authors: McConnell Richard L. , McCall Marvin A. , Cash G. O. , Joyner F. B. , Coover H. W.
Published: April 2003

The chemistry of three‐component coordination catalysts for the polymerization of α‐olefins is very complex. The present investigation was initiated to elucidate the chemistry involved in the interaction of third‐component compounds such as hexamethylphosphoric triamide, tributylamine, triphenylphosphine, or dimethylformamide with ethylaluminum dichloride. The present chemical and spectral data demonstrate that ethylaluminum dichloride and third‐component compounds form stable complexes even at temperatures up to 100°C. in the absence of solvents or in homogeneous solutions. These data are in agreement with the fact that organoaluminum compounds form stable complexes with a variety of electron‐donor compounds. The ethylaluminum dichloride third‐component complexes in combination with titanium(III) chloride produce highly stereospecific catalysts for the polymerization of α‐olefins.
Block copolymers based on 2,2‐bis(4‐hydroxyphenyl)propane polycarbonate. II. Effect of block length and composition on physical properties
Authors: Merrill Stewart H. , Petrie S. E.
Published: April 2003

Block copolymers of 2,2‐bis(4‐hydroxyphenyl)propane (BPA) polycarbonate and poly(ethylene oxide) (PEG) were used in a study of the influence of composition and block size on the thermal and mechanical properties of block copolymers. By copolymerizing polycarbonates of controlled molecular weight with similarly characterized poly(ethylene oxide) glycols, it was found feasible to alter the size of each type of block independently of the other. To complement this investigation, the effect of varying the concentration of a compatible plasticizer on the physical properties of the BPA polycarbonate was also studied. The BPA polycarbonate was rendered thermally crystallizable and flexible either by the copolymerization with PEG or by the addition of low molecular weight plasticizer. Degradation of tensile modulus and strength was observed with increased PEG content but was less for the copolymers with the longer blocks.
Alkyl‐free cobalt catalyst for the stereospecific polymerization of butadiene
Authors: Balas J. G. , De La Mare H. E. , Schissler D. O.
Published: April 2003

The stereoselective polymerization of butadiene to a predominantly cis polymer has been carried out with complex cobaltous halide catalysts, e.g., CoCl2·AlCl3. The unique features of such polymerizations are the homogeneous nature of the catalysis and the activity of such catalysts in the absence of any added reducing agent. The composition and spectroscopy of some of these catalyst solutions have been studied and possible structures proposed. The present status of the work does not permit a conclusive report on the mechanism of this polymerization, but some results of termination with tritiated methanol (CH3OH3) are described. Unfortunately, these experiments do not define the nature of the propagating end of the polymer chain.
Raman spectra of polyethers
Authors: Matsui Yoshiki , Kubota Tanekazu , Tadokoro Hiroyuki , Yoshihara Toshio
Published: April 2003

Experimental techniques for the measurements of the Raman spectra of crystalline high polymers have been developed. The preparation of samples and a procedure for the measurements are described in some detail. The Raman spectra of polyoxymethylene (CH2O)n, deuterated polyoxymethylene (CD2O)n, poly(ethylene oxide) (CH2CH2O)n, and polytetrahydrofuran (CH2CH2CH2CH2O)n have been obtained. These results as well as the infrared data are interpreted on the basis of the factor group analyses and the normal coordinate treatments. The experimental results are in fairly good agreement with the results of the theoretical treatments for these polyethers.
Electron spin resonance studies on oriented polyoxymethylene
Authors: Yoshida Hiroshi , Rånby Bengt
Published: April 2003

Electron spin resonance spectra of stretched polyoxymethylene irradiated with γ‐rays from a Co60 source were studied. With suitable treatment three kinds of spectra were selectively observed: doublet with irradiation and measurement at room temperature; singlet with irradiation and measurement at about −180°C.; triplet with the irradiation at about −180°C. and the measurement at −102°C. The doublet and the triplet spectra showed anisotropy, while the singlet did not. These observations confirm the assignment of the spectra so far reported with unoriented polyoxymethylene, i.e., CH2O, OĊHO, OĊH2 for the singlet, doublet, and triplet, respectively. The doublet spectrum is treated as related to the anisotropic hyperfine coupling tensor, the anisotropic g value and the chain conformation in crystalline polyoxymethylene. A rather small value, p≈0.45, was obtained for the spin density at the central carbon atom.
1‐Fluorovinyl methyl ketone: Preparation and polymerization
Authors: Sedlak John A. , Matsuda Ken
Published: April 2003

1‐Fluorovinyl methyl ketone, a new vinyl monomer, was prepared by dehydration of 1‐fluoro‐2‐hydroxyethyl methyl ketone with phosphoric acid or boric anhydride. The monomer was stabilized with anhydrous ammonia during preparation and storage. Homopolymers of 1‐fluorovinyl methyl ketone were prepared with free‐radical initiators in bulk, in solution, and in buffered emulsions.
A generalization of the debye light‐scattering equation
Authors: Heller Wilfried
Published: April 2003

The Debye light‐scattering equation is generalized by making allowance for the variation of (dn/dc)and therefore of Hwith the concentration of the solute. This should allow one to use it with more concentrated solutions provided light scattering is weak enough (oligomer solutions) so that multiple scattering does not exclude such a procedure.
Radiation polymerization of crystalline trithiane
Authors: Lando J. B. , Stannett V.
Published: April 2003

The polymerization of single crystals and finely powdered samples of trithiane (m.p. 215–216°C.) was accomplished by irradiation of the samples at room temperature with Co60 γ‐radiation to doses of 1–10 Mrad. Polymerization occurred during subsequent heating of the samples at 180°C. The conversion to polythiomethylene after a given time of heating at 180°C. is dependent on radiation dose, the G values for conversion being higher at lower doses. Purified polymer samples were studied by means of differential thermal analysis. Polymerized single crystals of trithiane were found to retain their orientation in three dimensions, although the polymer samples were systematically twinned. The directions of greatest chain growth were along the diagonals in the (ab) plane of the monomer. This reaction can be classified as topotactic; that is, the molecular orientations of the product are correlated with the molecular orientation in the reactant crystal. The relationship between the polymer structure and that of the monomer is evaluated.
Stereospecific polymerization of α‐olefins with three‐component catalyst systems
Authors: Coover H. W. , Joyner F. B.
Published: April 2003

It is well known that mixtures of alkylaluminum dihalides and transition metal halides, such as titanium(III) chloride, are ineffective as catalysts for the stereospecific polymerization of α‐olefins. It has been discovered that the addition of a third compound, derived from one or more of the strongly complexing ligand elements such as nitrogen oxygen, and phosphorus, to such mixtures leads to catalysts having the highest stereospecificities known. In the present work, studies were made of the effect of various third components on the activity and stereospecificity of these catalysts in the polymerization of propylene. The stereospecificity and activity of three‐component catalysts of this type were dependent upon the ratio of the third component to the alkyaluminum dihalide. Optimum stereospecificity and activity were usually obtained at ratios in the range of 0.5–0.7. In general, catalytic activity increased with increasing basicity of the third component. Both stereospecificity and activity were influenced by the nature of the halogen atoms in the alkylaluminum dihalide, whereas the nature of the alkyl group affected only the activity, with the ethyl group providing the most active catalysts. The most stereospecific catalyst was made from a mixture of ethylaluminum diiodide, hexamethylphosphoric triamide, and violet titanium(III) chloride.
Solid‐state polymerization of trioxane
Authors: Rao H. , Ballantine D. S.
Published: April 2003

Trioxane has been polymerized by irradiation with Co60 γ‐rays in the temperature range 45–55°C. The data are extremely difficult to reproduce in spite of great precautions in sample preparation. The reaction reaches a limiting conversion, generally about 40%, but conversions as high as 96% have been observed. The viscosity of the polymer decreases with increasing conversion. Post‐irradiation heating of monomer irradiated at low temperature (<30°C.) also leads to limiting conversions but much higher viscosity products. The polymerization has also been studied under pressure. Pressure applied to monomer prior to irradiation leads to higher conversions and higher viscosity polymers. In the post‐irradiation polymerization technique, application of pressure after irradiation reduces the polymer yield to zero in almost every instance.
Polymer production from aqueous solutions of D‐glucose by high‐energy radiation
Authors: Snell John B.
Published: April 2003

Polymeric material was produced by passing aqueous glucose solutions under a beam of high energy electrons. The yield of polymer increased with dose and dose rate. The weight‐average molecular weights of polymers formed at 40 Mrad, measured by light scattering, ranged from 9,800 to 5,000,000. The polymers exhibited very low intrinsic viscosities in water, and are therefore though to be highly branched. Measurement of the number‐average molecular weight of one of the polymers by osmometry established an Mw/Mn ratio of 4.9, indicating a fairly broad distribution of molecular weights within the polymer. One polymer was fractionated on Sephadex and the chemical composition of the fractions compared. The carboxyl content increased regularly with molecular weight, suggesting that the carboxyl groups were the result of secondary oxidative attack. Hydrogen and oxygen contents decreased with increasing molecular weight. Elemental analysis and infrared spectral data on the fractions were consistent with the hypothesis that gluconolactone was incorporated into the polymer in the early stages of formation. Chromophoric groups, perhaps of the endiol type, were formed, and oxygen‐rich fragments were apparently lost as the molecular weight of the polymer increased. Oxygen contents, on the other hand, decreased with increasing molecular weight. The regularity observed in the fraction analyses suggested that the polymerization followed a pattern, and was not the result of the random joining of unlike fragments. Elemental analysis and infrared spectral data on the fractions were consistent with the hypothesis that gluconolactone was incorporated into the polymer in the early stages of formation. Chromophoric groups, perhaps of the enediol type, were formed, and oxygen‐rich fragments were apparently lost as the molecular weight of the polymer increased.
Chemical scission of poly(methyl acrylate)
Authors: Hwa Jesse C. H. , Miller Leon
Published: April 2003

By copolymerizing methyl acrylate with methyl α‐chloroacrylate at various ratios, the resulting poly(methyl acrylate) backbone had reactive chlorine sites. The poly(methyl acrylate‐co‐methyl α‐chloroacrylate) was dehydrochlorinated by amine. After hydrolysis to convert methyl ester to sodium salt of the acid, the unsaturated bonds introduced by dehydrochlorination were oxidized to glycol by potassium permanganate and cleaved by periodic acid. The resulting poly(sodium acrylate) was converted to the free acid by ion exchange and reesterified with diazomethane. Degraded fragments having number‐average molecular weights of 5,000–12,000 were obtained at 83% polymer recovery. Based on the original chlorine content, the efficiency of overall degradation was 20–26% and perhaps somewhat higher.
Polyphenylene‐s‐triazinyl ethers by interfacial polycondensation
Authors: Picklesimer Lewellyn G. , Saunders Thomas F.
Published: April 2003

Polyphenylene–s‐triazinyl ethers of apparently high molecular weight have been prepared by the interfacial polycondensation of s‐triazinyl chlorides and sodium bisphenoxides. The polymers are characterized by good thermal stability, insolubility, and infusibility. The polymers can be varied by altering the reaction conditions. A long residence time at the reactive interface leads to a polymer of low residual chlorine and thus highly crosslinked. Reduction of the contact time at the reactive interface leads to polymers containing a greater amount of chlorine and consequently some linearity.
NMR study of polymers of ethyl, isopropyl, and tert‐butyl vinyl ethers
Authors: Ramey Kermit C. , Field Nathan D. , Borchert Alfred E.
Published: April 2003

The high resolution NMR spectra of poly(vinyl ethyl, isopropyl, isobutyl, and tert‐butyl ethers), yields, upon examination at 60 and 100 Mcycles/sec., and under the conditions of decoupling, information concerning the various tactic forms present. The spectra are complicated by the number of overlapping resonances to the extent that an unambiguous assignment of the three triad forms could not be made. For poly(vinyl isobutyl ether) the resonances of the α proton decoupled from the β protons exhibits three components which are tentatively assigned to the central monomer units in heterotactic, isotactic, and syndiotactic configurations, with increasing field strength, respectively.
Studies of variations in the properties of ion‐exchange resin particles
Authors: Freeman David H. , Patel Vithal C. , Smith Mary E.
Published: April 2003

Measurements of the swelling ratio and exchange capacity of individual ion‐exchange resin beads are used to compare resin samples, to study interparticle differences, and to help characterize resin degradation. Heterogeneous resin samples were found, along with those of apparent homogeneity. In one extreme case of the former, inert particle cores were found.
Flow behavior of polydimethylsiloxane
Authors: Kataoka Tadao , Ueda Shigeyuki
Published: April 2003

Viscosities of polydimethylsiloxane were measured over a wide range of shear rates and molecular weights to clarify the flow behavior of bulk polymers. It was observed that each flow curve for high molecular weight samples had an inflection point, and at high shear rates all curves tended to converge. The relationship between viscosities and molecular weights at various shear rates showed the following features: no sharp inflection in the zero shear relation and non‐Newtonian properties below Mc. It is suggested that viscosities of high molecular weight samples become almost the same, irrespective of molecular weight, at very high shear rates.
Thermostatted cell for a Brice‐Phoenix light‐scattering photometer
Authors: Smart C.
Published: April 2003

A thermostat jacket is described for a Brice‐Phoenix light‐scattering photometer which allows accurate temperature control of the scattering medium over a wide range of temperatures. Modifications to the electronic system of the photometer have increased its sensitivity so that more accurate measurements can be made for low Rayleigh ratios. By using a circulating liquid of the same refractive index as the Pyrex glass cell, stray light within the cell has been reduced to a very low level. Some results for the Rayleigh ratios of water and benzene are presented.
A phenomenological theory of spherulitic crystallization: Primary and secondary crystallization processes
Authors: Price Fraser P.
Published: April 2003

A theory is presented that takes into account the two stages occurring during the crystallization of bulk polymers. The theory assumes that all the crystallization occurs within the spherulites but that the amount of crystallinity at any particular point within a spherulite depends upon the age of that particular point. It is shown that these assumptions lead to transformation curves that look like those in actual polymer crystallizations.
Reaction of α, α‐diphenyl‐β‐picrylhydrazyl with acids
Authors: Solomon D. H. , Swift Jean D.
Published: April 2003

The action of dilute aqueous mineral acids on α,α‐diphenyl‐β‐picryl hydrazyl (DPPH) has been studied and shown to result in the rapid loss of the characteristic color of the radical. Hydrobromic and hydrochloric acids yield α,α‐diphenyl‐β‐picryl hydrazine (DPPH‐H) and the corresponding halogen‐substituted α,α‐diphenyl‐β‐picryl hydrazine. Hydroiodic acid gives DPPH‐H, iodine, and a small quantity of DPPH. A number of organic acids cause similar reactions. Kinetic studies on the hydrobromic acid system indicate that the reaction is first‐order with respect to: hydrogen ion concentration, DPPH concentration, and anion concentration. The ability of the anion to undergo one‐electron transfer and to dimerize are also important, and the strongest nucleophile gives the fastest reaction. A mechanism which involves ionic attack is proposed to account for the reaction of DPPH with acid. The limitations of DPPH in studying reaction mechanisms are then discussed in relation to the proposed ionic mechanism.
Average lifetime of growing chain in propylene polymerization
Authors: Tanaka Sanae , Morikawa Hiroyuki
Published: April 2003

The value of the active lifetime of the growing chain of propylene polymer obtained with TiCl3Al(C2H5)2Cl as catalyst was determined to be 33–40 min. by the method of calculating changes of number‐average molecular weight from measurements of molecular weight distribution. In addition, the influence of reaction conditions (reaction temperature, monomer concentration, catalyst concentration, reaction time, terminating agent) upon the active lifetime was examined. The data obtained support the theory of the occurrence of chain transfer. An expression was obtained for the lifetime distribution of the polymer.
Aliphatic poly‐1,3,4‐oxadiazoles
Authors: Unishi Terunobu , Hasegawa Masaki
Published: April 2003

Three high molecular weight aliphatic polyoxadiazoles have been prepared by a new route from equimolar amounts of a diphenyl ester of dicarboxylic acid and an anhydrous hydrazine (or a dihydrazide). The resulting polymers have been characterized by microanalysis, intrinsic viscosity, x‐ray diffraction patterns, infrared absorption spectra, and by differential thermal analysis. Such polymers are soluble in several solvents and show very low melting temperature and high crystallinity.
Effects of rate of shear on the viscosity of polymer solutions
Authors: Fujishige Shoei
Published: April 2003

Viscosities of dilute solutions of poly(methyl methacrylate) in toluene and in chloroform were measured with a modified capillary viscometer. By tilting the viscometer one can control the solvent flow time to any desired condition, and by use of this technique it was possible to determine the extent to which such variables affect the resulting rate of shear if one measures the viscosities with two or more viscometers of the same type having different flow times of solvent. The reduced viscosities measured with the modified capillary viscometer at several tilting angles were plotted in the usual way against the polymer concentrations, and values of the intrinsic viscosity for a given solution at each tilting angle were thus obtained for both of the solutions studied. For a rather high molecular weight polymer fraction, the maximum variation in the molecular weight estimated from the intrinsic viscosity by the Mark‐Houwink relation was of the order of 20% between the values obtained with the viscometer fixed at a vertical and at another extreme angle. All the experimental data are also reproduced as a function of the rate of shear, and reliable values for the intrinsic viscosity at zero rate of shear and hence for the molecular weight are obtained. Other possible differences noted in the determination of such molecular characteristics as the Huggins′ constant which could be attributed to this kind of experimental condition were discussed.
Single crystals of amylose V complexes
Authors: Yamashita Yuhiko
Published: April 2003

In the present paper our previous results and Manley's results for single crystals of amylose V complexes are confirmed. A reasonable interpretation of electron diffraction patterns from lamellar crystals of the monohydrated complex and of the anhydrous complex is presented. It is concluded that the longer side of rectangular lamellae corresponds to the a axis of the unit cell of the wet complex, and that the crystal structure does not have hexagonal symmetry at the time when the lamellar crystals are formed in the supercooled solution. The mode of chain packing in the single crystals is described and discussed.
Carborane polymers. III. Vinyl carboranes
Authors: Green Joseph , Mayes Nathan , Cohen Murray S.
Published: April 2003

Isopropenylcarborane could not be polymerized by conventional radical and ionic methods. A low molecular weight polymer of DP = 10 was obtained by the use of aluminum chloride as catalyst at 150–170°C. Carboranylmethyl acrylate was homopolymerized and copolymerized with fluoroacrylates by using benzoyl peroxide as catalyst. The Tg of the homopolymer was about 165°C. The difficulty in polymerizing the isopropenylcarborane and the high Tg value for carboranylmethyl acrylate polymer have been partially attributed to the steric requirements of the carborane group.
Energetic and entropic components of tension in elastomeric wool fibers
Authors: Haly A. R.
Published: April 2003

Tension against temperature data were obtained for both unreduced wool fibers and fibers in which some of the disulfide bonds had been reduced by a thiol. The measurements were done while the fibers contained a diluent. Coefficients of volume thermal expansion were also measured. From the results the ratio of the energetic component of tension to the total tension (fe/f) was calculated. Most values of fe/f were within the range ± 0.20. In the case of unreduced wool fe/f changed from negative to positive as the extension increased. With a reduced sample containing 8% of the native disulfide, fe/f was negative and nearly constant over the range of extension employed. The change for unreduced wool follows from extension‐dependent interactions between polypeptide chains. The results indicate that, for unperturbed polypeptide chains from wool taken into solution following disulfide reduction, the end‐to‐end distance will decrease with increase of temperature, a partially extended form being the lower energy state.
Preparation and properties of crystalline, low molecular weight poly(vinyl chloride)
Authors: Böckman Oluf Chr.
Published: April 2003

The preparation of low molecular weight (DP < 52) poly(vinyl chloride) by free radical solution polymerization in chain transfer agents, e.g., butyraldehyde, chloroform, tetrahydronaphthalene, and tetrahydrofuran, is described. It is found that such polymers are crystalline and that the degree of crystallinity increases with decreasing molecular weight.
Radiation crosslinking of nylon 66 and poly(vinyl alcohol)
Authors: Bernstein Bruce S. , Odian George , Orban Gyula , Tirelli Sebastian
Published: April 2003

Low dose Co60 radiation of nylon 66 and poly(vinyl alcohol) in the presence of methanol–water–allyl methacrylate (AMA) mixtures allows crosslinking of the polymers. In both cases, crosslinking is facilitated by the presence of the polyfunctional monomer and does not occur in its absence. Nylon gel fractions of 40% have been obtained after a dose of 3 Mrad; poly(vinyl alcohol) gel fractions of over 75% have been obtained after 5 Mrad. With both polymers, the gel fraction is dependent upon the radiation dose, AMA level, and water level during radiation.
Probability of cyclopolymerization
Authors: Butler George B. , Raymond Maurice A.
Published: April 2003

A statistical approach to the mechanistic problem of cyclopolymerization was taken. The model for this calculation was based on a stepwise mechanism for polymerization of 1,6‐dienes. The assumption was made that a reaction site was formed at the second carbon of the chain C2, and the probability of C7 being in a volume element surrounding this position was calculated. The results, which indicate that on a statistical basis only, monomer concentrations must be reduced to <0.10 mole/l. in order to attain >95% cyclization, were compared with numerous experimental results in which 95–100% cyclization was obtained at monomer concentrations of 1.9–8.0 mole/l.
Polymerization of acrolein by redox initiation
Authors: Ryder E. E. , Pezzaglia P.
Published: April 2003

The kinetics of the free‐radical‐catalyzed redox polymerization of aqueous acrolein have been examined. The reaction was found to be second‐order in acrolein, half‐order in instantaneous concentration of reducing agent, and independent of peroxide as long as sufficient amount was present. The reaction has a negative temperature coefficient, decreasing in rate as the temperature is raised. The redox system used was tert‐butyl hydroperoxide–polyacrolein hydroxysulfonic acid, and the rate of initiation was observed to vary directly with the pH and the temperature. Polymer molecular weight varied directly with acrolein concentration and indirectly with polyacrolein hydroxysulfonic acid concentration and the temperature. An empirical relationship may be represented as: [η] = K[M0]/[C0]1/4, where [η] is intrinsic viscosity (in deciliters per gram), [M0] is the initial acrolein concentration, [C0] is the initial reducing agent concentration; and K is a temperature‐dependent variable. The effect of trace impurities in acrolein on polyacrolein preparation was examined. Acetaldehyde and propionaldehyde had a retarding effect on polymerization rate. The effect of these components in reducing the molecular weight of the product increased in the order: acetaldehyde, propionaldehyde, and acetone.