bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiation‐induced post polymerization of trioxane in the solid state
Authors: Hayashi K. , Ochi H. , Okamura S.
Published: April 2003

Trioxane, the cyclic trimer of formaldehyde, is easily polymerized by ionizing radiation in the solid state at a temperature slightly below the melting point. It was found that this post‐polymerization is analogous to the in‐source polymerization, but its overall activation energy is more than 40 kcal./mole, which is much larger than for in‐source polymerization. A kinetic scheme is proposed for the post‐polymerization which accounts for the experimental results. In‐source polymerization probably occurs by an ionic mechanism, but three co‐exist two different mechanisms in the post‐polymerization. One is probably initiated by the decomposition of a product produced by the ionizing radiation in the presence of oxygen. The other has not yet been clarified, but it does not seem to be due to trapped radical or ionic species. The thermal decomposition of the polymer formed and the influence of additives, such as methanol, and benzene, on post‐polymerization were also studied.
Origins of x‐ray line broadening in polyethylene single crystals
Authors: Thielke H. G. , Billmeyer F. W.
Published: April 2003

If multiple orders of x‐ray diffraction can be observed, the origins of line broadening in the diffraction pattern can be unambiguously assigned. In the absence of such data, rare in polymers, firm conclusions cannot be drawn. Line broadening data for single crystals of polyethylene, where multiple orders of diffraction were not observed, are consistent with the following origins: for planes with indices (hk0), a size of 200 A. and 1.3% strain: for the (002) plane, a size of 105 A. (in good agreement with the lamellar thickness) if 1.3% strain is assumed, or 70A. (a lower limit) if no strain is assumed.
Carborane polymers. I. Polyesters
Authors: Green Joseph , Mayes Nathan , Cohen Murray S.
Published: April 2003

Polyesters containing a unique polycycloborane in the polymer structure have been prepared. The boron hydride moiety, C2B10H10, has been named carborane and approximates in size a sphere with an effective van der Waals radius of 4 A. Polyesters of 2000–3000 molecular weight were prepared by allowing carborane monomers to react with each other or with organic or fluorocarbon diols or diacids. A polyester of approximately 20,000 molecular weight was prepared and it was demonstrated that molecular weight obtainable was a function of monomer ratio and purity. It was demonstrated that polyesterification of adipic acid with a carborane diol was significantly slower than the analogous reaction with 1,4‐butanediol. Reactions of carborane diols with carborane diacids were shown to occur with difficulty or not at all. Transesterification of carborane malonates also occurred with difficulty. The inhibitions of carborane materials toward polyesterification was attributed to both steric and polar influences with the former being more significant. The effect of the bulky carborane group in the polyester chain on the properties of the polymer was demonstrated by the preparation of polyadipates from 1,2‐bis(hydroxymethyl)carborane, 1,4‐butanediol, and 1,4‐butynediol. The first product was a liquid which showed no tendency to crystallize. The noncarborane polyesters were crystalline waxes at equivalent chain length. The bulk of the carborane group apparently inhibited close packing and subsequent crystallization. A comparison of the carborane polyadipate and polysuccinate showed that the latter was a hard glass, apparently due to a decrease in chain flexibility.
Analytical and preparative vapor‐phase chromatographic separation of divinylbenzene mixtures
Authors: Wiley Richard H. , Dyer Rolla M.
Published: April 2003

The analytical vapor‐phase chromatographic separation of commercial divinylbenzene mixtures with a polypropylene glycol liquid phase on Chromosorb W support has been adapted to the preparative scale separation of a 2:1; 9:1 and 99.8+% pure mixtures of m‐ and p‐divinylbenzenes and to the purification of synthetic p‐divinylbenzene.
Polymerization in liquid sulfur dioxide. Part XVIII. Polymerization of p‐isopropylstyrene and its copolymerization with styrene in liquid sulfur dioxide
Authors: Tokura Niichiro , Matsuda Minoru , Arakawa Koji
Published: April 2003

When p‐isopropylstyrene was polymerized in liquid sulfur dioxide with a free radical initiator, simultaneous radical polysulfone formation and cationic homopolymerization of the olefin occurred. When dimethylformamide was added to the system, cationic polymerization was completely inhibited and only a polysulfone containing p‐isopropylstyrene and sulfur dioxide in the ratio 2:1 was obtained, similar to previously reported reactions with styrene, p‐bromostyrene, and p‐methylstyrene. The overall reaction rate of the radical polymerization was proportional to the initial concentration of the initiator to the order 0.62, indicating that both unimolecular and bimolecular termination was occurring. The radical polymerization of the three‐component mixture, styrene–p–isopropylstyrene–liquid sulfur dioxide, resulted in a copolysulfone which always contained about 33 mole‐% sulfur dioxide and could be considered a copolymer of three different 2:1 olefin : sulfur dioxide units.
Morphology of polyethylene crystallized from the melt under pressure
Authors: Geil Phillip H. , Anderson Franklin R. , Wunderlich Bernhard , Arakawa Tamio
Published: April 2003

The morphology of linear polyethylene crystallized under pressures up to 5300 atm. has been investigated. Electron micrographs of fracture surfaces obtained from these samples show that the majority of the polymer, at the highest pressures, crystallizes in the form of extended chain lamellae which can be as thick as 3 μ. Electron diffraction patterns show that the molecules are normal to the lamellae. At lower pressures part of the polymer crystallizes in the form of folded chain lamellae, the proportion increasing with decreasing pressure. Well defined kink bands can be observed in the thicker extended chain lamellae. It is suggested that either molecular weight fractionation or an end‐to‐end alignment of the molecules and subsequent folding takes place during the growth of the extended chain lamellae.
Diffusivities and solubilities of methane in linear polyethylene melts
Authors: Lundberg J. L.
Published: April 2003

Diffusion coefficients of methane in linear polyethylene melts measured by simple sorption experiments are from 1.5 × 10−5 to 3.6 × 10−5 cm.2/sec. between 140.0 and 188.3°C. These diffusion coefficients are one‐third to one‐half those of methane in branched polyethylene melts at these temperatures. Solubilities of methane in branched and linear polyethylene melts are similar, approximately three molecules of methane per one hundred methylene units at 250 atm. partial pressure methane between 140.0 and 188.3°C. Temperature coefficients of solubilities of methane in branched and linear polyethylenes differ in that the solubility of methane in linear polyethylene melt appears to go through a minimum with temperature between 140.0 and 162.8°C. These differences in diffusion coefficients and temperature coefficients of solubilities are consistent with the presence of greater order in linear polyethylene melt than in branched polyethylene melt.
A contribution to the preparation of phenolic polynuclear compounds with sulfonyl bridges
Authors: Kämmerer H. , Harris M.
Published: April 2003

For the preparation of phenolic di‐ and tricyclic compounds with sulfonyl bridges the Fries rearrangement is suitable, and for the corresponding products with three and four benzene rings the Friedel‐Crafts reaction may be used. The exchange of sulfonyl bridges for methylene bridges produces a marked increase in the melting point.
Generality of product probability values in unifying and predicting relationships among monomers in copolymerization
Authors: Ham George E.
Published: April 2003

It is shown that a knowledge of the reactivity ratios for the binary systems A–B and B–C allows reactivity ratios for the copolymer system A–C to be calculated from the relationship: PabPbcPca = PacPcbPba = (a constant). The various probabilities include the possibilities of adding A, B, or C monomers to any of the corresponding radicals and can be expressed in terms of binary reactivity ratios. At equimolar concentrations it is shown that for systems of three conjugated or three unconjugated monomers approximates 0.037. Similarly, for systems of two conjugated and one unconjugated monomers or two unconjugated and one conjugated monomers approximates 0.006. Once the appropriateness of these constants is established, it is shown how the relationship may be used to assess the most probable values among widely varying reported reactivity ratios. It is shown that the values of the constant for different combinations of monomers allow the assessment of the reactivity of conjugated monomers compared with unconjugated monomers for conjugated or unconjugated radicals. It develops that the reactivity of unconjugated monomers is between 5 and 10% of that of conjugated monomers for unconjugated radicals. For more precise assessment of unknown reactivity ratios it is suggested that is a product function of unique reactivity parameters characteristic of the individual monomers involved.
Isomorphism in copolyamides containing the p‐phenylene linkage
Authors: Tranter T. C.
Published: April 2003

Since the observations of Edgar and Hill on polyhexamethylene adipamide/polyhexamethylene terephthalamide copolymers, a linear melting point/composition relationship has become widely accepted as a criterion for isomorphous replacement. In a series of binary copolymers based on homopolymers prepared from hexamethylene diamine and p‐phenylene dipropionic (3P3), 3‐(p‐carboxymethyl) phenyl butyric (2P4), 2‐(p‐carbomethoxy) phenyl propionic (3PO2), hydroquinone diacetic (2OPO2), terephthalic (T), adipic (6), or sebacic (10) acids, only the 6.3P3/6.3PO2 system showed a linear softening point/composition curve, although the differences in repeating unit length were certainly no greater and often much less than with adipic and terephthalic acids. X‐ray examination, however, revealed that all the systems behaved in the same basic manner, the second component dissolving in the lattice of the first until a certain critical concentration was reached when the lattice changed fairly abruptly to that of the second component in which the first component was now dissolved. The changeover point generally, but not always, coincided with the position of a minimum in the softening point/composition curve. Infrared and density measurements did not show any reduction in crystallinity at this point. These copolyamides, thus, afford no exception to the assumption that close similarity in length of repeating units is a necessary, but perhaps not the only, prerequisite for the occurrence of segmental change. The form of the softening point/composition curve is, therefore, not a reliable criterion for isomorphous replacement and it seems likely that this conclusion applies equally to the melting point/composition curve.
A critical evaluation of mathematical molecular weight distribution models proposed for real polymer distributions. II. Effects of a high molecular weight cut‐off value
Authors: Kotliar A. M.
Published: April 2003

It is shown that logarithmic normal type distributions, e.g., Wesslau, cannot describe real polymer distributions having low and high molecular weight cut‐off values. However, certain cases of the generalized exponential type distribution do appear to be useful and valid models.
On the relation between different morphological forms in high polymers
Authors: Keith H. D.
Published: April 2003

It is suggested that all of the morphological forms commonly observed in high polymers are closely related. These forms are considered to represent different stages in a development from single crystal into spherulite under the influence of species rejected by growing crystals. Single crystals undergo this transformation in habit when of a size roughly equal to δ = D/G, where D is the diffusion coefficient in the crystallizing medium and G is the rate of crystal growth. New experimental results show that when δ is unusually large, single crystals may be grown from polymer melts, and when δ is reduced by the use of high molecular weight polymer and/or viscous solvents, spherulites may be grown from polymer solutions. It is shown that single crystals of polyethylene crystallized from solution in paraffinic solvents exhibit a different habit from those crystallized under equivalent conditions from xylene. This affords a simple explanation for the radial b orientation found in spherulites of polyethylene.
Polyether‐ester copolymer prepared from p‐γ‐hydroxypropoxy benzoate and bis‐β‐hydroxyethyl terephthalate
Authors: Ishibashi Matahumi
Published: April 2003

Polyether‐ester copolymers were prepared from methyl p‐γ‐hydroxypropoxy benzoate and bis‐β‐hydroxyethyl terephthalate over the entire composition range by a condensation reaction. It was found by means of x‐ray diffraction that the copolymers showed high crystallinity over the entire range of copolymer composition. The melting point curve of the copolymers showed a eutectic type. The x‐ray diffraction patterns of the copolymers were different from both those of poly(ethylene terephthalate) and of poly(p‐1,3‐propylene oxybenzoate). These results showed that in each of the copolymers both the repeating units, the ethylene terephthalate unit and the p‐1,3‐propylene oxybenzoate unit, could be incorporated into the chain of a crystallizable polymer without hindering crystallization of the resulting copolymer, i.e., the copolymers were isomorphous over the entire composition range.
Diffraction study of crystallite orientation in a stretched polychloroprene vulcanizate
Authors: Krigbaum W. R. , Roe R.‐J.
Published: April 2003

Crosslinked polychloroprene samples were allowed to crystallize from the melt at various fixed elongations. X‐ray diffraction studies revealed that the c axis becomes oriented toward the stretching direction, while the a and b axes are randomly distributed about the c axis. The alignment of the crystallite c axes toward the drawing direction is much more perfect than that of the amorphous statistical chain segments prior to crystallization. This can be explained if we assume that the formation of a stable nucleus for crystallization requires the simultaneous alignment of v amorphous segments. Thus, such measurements offer a means by which the critical size of the crystallization nuclei can be determined. The sizes deduced for polychloroprene vary with elongation from a cube 30 A. on a side at relative elongation α = 1.45 to a 17 A. cube at α = 7.40. Although our samples were not crystallized isothermally, these results are in qualitative agreement with nucleation theory. If the variation of v can, indeed, be estimated theoretically, then it will be possible to predict the entire crystallite orientation distribution in materials of this type from first principles. The orientation of crystallites formed in a sample at relative elongation α = 2.92 was found to be essentially independent of temperature from 24° C. to the melting point. For low degrees crystallinity, ω it is shown that a plot of 1/T versus 1/(1 − ω)2 is linear, thus permitting an evaluation of the melting point by extrapolation. Finally, the crystallite orientations were compared for a sample crystallized from the melt at α = 2.86 and for the same sample after further drawing to α = 3.50 at room temperature. The distribution in the latter case was considerably broader, which demonstrates the primary role played by interactions between crystallites in the cold drawing of partially crystallized materials.
Synthesis of low molecular weight polystyrene by anionic techniques and intrinsic viscosity–molecular weight relations over a broad range in molecular weight
Authors: Altares T. , Wyman D. P. , Allen V. R.
Published: April 2003

Anionic polymerization techniques have been used to prepare low molecular weight (M ≤ 10,000) polystyrene of M̄w/M̄n ≤ 1.1. The preparation and characterization of polymers are described. Good agreement with results reported by others was obtained for the viscosity‐molecular weight relation in benzene at 25°C., viz. [η] = 1.0 × 10−3 M̄n0.5, for 500 < M̄n ≤ 10,000. For high molecular weight fractions (2.5 × 104 < M ≤ 1.5 × 106) of anionically prepared polystyrene, the expression, [η] benzene = 8.5 × 10−5M0.75, was found to be applicable and in agreement with relations given in the literature. Under theta conditions—cyclohexane as solvent at 34.5°C.—a single expression, [η] = 8.4 × 10−4M0.5, was found to apply over the entire molecular weight range, 500 < M ≤ 1.5 × 106.
Glass transformation temperatures of poly(vinyl alkyl ethers) and poly(vinyl alkyl sulfides)
Authors: Lal Joginder , Trick G. S.
Published: April 2003

A number of poly(vinyl alkyl ethers) and poly(vinyl alkyl sulfides) of reasonably high molecular weight were prepared. Glass transformation temperatures Tg of the various polymers were measured dilatometrically. In general, the Tg value decreased with increasing length of the n‐alkyl group. Data relating Tg values of poly(vinyl n‐alkyl ethers) with length of n‐alkyl group were treated in terms of free volume concepts of the liquid state. Branching on the alkyl group of the polymer increased the Tg value. Poly(vinyl n‐alkyl sulfides) had Tg values about 35°C. higher than their oxygen analogs. A comparison of poly(vinyl n‐alkyl ethers) and polymers of normal α‐olefins showed that the ether group and methylene group in side chains were equivalent in influencing the glass transformation temperatures. From a comparison of poly(vinyl n‐alkyl ethers) and poly(n‐alkyl methacrylates) it is concluded that the nature of the backbone is important in determining the ease with which side chain crystallization takes place.
Polymerization of higher aldehydes. V. End‐capped crystalline isotactic polyaldehydes: Characterization and properties
Authors: Vogl O.
Published: April 2003

End‐capped, isotactic polyaldehydes were characterized by the determination of the solution viscosities, melting points, the gel points and solubilities in a number of solvents. Relative endgroup molecular weights were estimated from infrared spectra. The stability of end‐capped polyaldehydes is discussed.
Effect of gamma radiation on the specific volume of polytetrafluoroethylene from −80°C. to +40°C
Authors: Licht W. R. , Kline D. E.
Published: April 2003

Specific volume vs. temperature relationships for γ‐irradiated polytetrafluoroethylene (PTFE) samples (1/2 in. diameter rods) have been studied over the −80 to +40°C. temperature range for radiation doses up to 890 Mrads. At low doses, the overall specific volume decreases with increasing dose. Between 100 and 300 Mrads the effect reverses, and the specific volume increases with dose up to 890 Mrads. As reported in the literature, an inflection point associated with the first‐order crystalline transition appears in the specific volume curve near 19°C. for unirradiated PTFE. This inflection point loses definition and shifts to lower temperatures with increasing radiation dose. At 890 Mrads the inflection point has decreased about 50°C. to near −33°C. Effects noted in irradiated PTFE are attributed to chain scission, changes in per cent crystallinity, and eventual disordering of the crystallites with increasing radiation dose. No significant difference in results are detected between samples irradiated in air and samples irradiated in vacuum‐sealed containers.
Copolymerization of divinylbenzene with monovinyl monomers
Authors: Gibbs William E.
Published: April 2003

Composition relations for the copolymerization of vinyl monomers with divinyl monomers incapable of undergoing short‐range cyclization or alternating inter‐intramolecular propagation have been derived both for the general case, including crosslinking reactions, and for the approximate case where the concentration of pendant unsaturation may be assumed unaffected by crosslinking reactions. The general case composition equation has a complexity similar to that for the ternary polymerization of three vinyl monomers. The approximate case closely resembles the usual binary copolymerization relationship:

where r1 = k11/k14, r2 = k44/k41, [M4] is the molar concentration of vinyl comonomer, but where [M1] is the molar concentration of divinyl monomer double bonds, i.e., twice the molar concentration of divinyl monomer.
An infrared study of polyhydroxymethylene and deuterated polyhydroxymethylene
Authors: Schaefgen J. R. , Zbinden R.
Published: April 2003

The polarized infrared spectra of oriented polyhydroxymethylene films were determined in the range 5000–500 cm.−1. The films then were deuterated and the spectra again recorded. A tentative assignment of the major abosrption bands is proposed on the basis of a simple zigzag chain model with a 2.5 A. repeat distance. The rate of hydrogen–deuterium exchange of a \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} ({\rm CHOD}\rlap{--} )_n $\end{document} film with atmospheric water vapor was measured and found to be diffusion‐controlled.
Comparison of polyethylene molecular weights determined by light‐scattering measurements in 1‐chloronaphthalene and 1,2,3,4‐tetrahydronaphthalene
Authors: Tung L. H.
Published: April 2003

Polyethylene molecular weights were determined by light‐scattering measurements in 1‐chloronapthalene and 1,2,3,4‐tetrahydronaphthalene at 125°C. Both high density and low density polyethylene fractions were used. The results show that at 125°C. polyethylene molecules do not associate in 1‐chloronaphthalene. The disagreement of molecular weights of polyethylene determined in the two solvents is traced to the uncertainty of refractive index increment of polyethylene in 1,2,3,4‐tetrahydronaphthalene and to possible oxidation of the polymer in 1‐chloronaphthalene.
Intramolecular hydride shift polymerization by cationic mechanism. IV. Cationic isomerization polymerization of vinylcyclohexane
Authors: Kennedy J. P. , Elliott J. J. , Naegele W.
Published: April 2003

The cationic polymerization of vinylcyclohexane was investigated with the use of AlCl3 catalyst at temperatures ranging from −144 to +7°C. The structure of the polymer was elucidated by NMR and infrared spectroscopy. These studies indicate that cationically synthesized polyvinylcyclohexane contains predominantly repeat units of the type:
magnified image
which suggests hydride shift isomerization polymerization.
Rubber elasticity: Thermodynamic properties of deformed networks
Authors: Bianchi Umberto , Pedemonte Enrico
Published: April 2003

Some recent measurements on internal pressure Pi of two elastomers, a silicone rubber and an ethylene–propylene copolymer, at various elongation ratios λ are reported. Results so far obtained show that Pi varies with λ; this behavior is discussed in the light of recent theories of rubber elasticity.
Polymerization of styrene with TiCl3–Al(C2H5)3 and VCl3–Al(C2H5)3 catalysts
Authors: Otto F. D. , Parravano G.
Published: April 2003

The polymerization of styrene was studied in benzene solution with two catalyst systems: TiCl3–Al(C2H5)3 and VCl3–Al(C2H5)3. The reaction was carried out at atmospheric pressure, temperatures of 40–70°C., [monomer] = 0.695–5.75 moles/l., [TiCl3] = 0.12–1.2 g./l., and [alkyl] = 0.001–0.016 mole/l. For polymerizations with TiCl3–Al(C2H5)3 catalyst, the rate of polymerization was found to be first‐order with respect to TiCl3, proportional to [monomer]1.5 and for [Al(C2H5)3] > 0.002 mole/l., proportional to [Al(C2H5)3]−1/2. For [Al(C2H5)3] < 0.002 mole/l., the rate passed through a maximum and decreased rapidly to a negligible value as the alkyl concentration decreased. The apparent activation energy was 8.1 kcal./mole. The rate of polymerization with VCl3 as catalyst component was generally faster than the rate obtained with TiCl3. A reaction scheme has been postulated to account for the influence of monomer and catalyst on the steady state rate. The model suggests that TiCl3 activation consists of surface alkylation and removal of Cl− ions by reaction with Al(C2H5)3. Monomer adsorption occurs on vacant sites, neighboring alkylated surface sites, in competition with the adsorption of metal alkyl. Vacant and alkylated sites partake in the first coordination sphere of Ti+3 ions in TiCl3. Polymerization follows by monomer insertion into the TiC bond at the alkylated site.
Deuteration of proteins and polyamides in deuterium oxide vapor
Authors: Jeffries R.
Published: April 2003

This paper describes the H → D exchange reaction in proteins and polyamides immersed in saturated deuterium oxide vapor. Ten proteins (seven silk fibroins, wool, byssus, and Fibrolane BX) and the nylons 66, 6, and 11 were studied. With all the samples there was an initial rapid exchange followed by a slower exchange, this slow change gradually levelling off to give “equilibrium” values. The extent of the H → D exchange is discussed in relation to order and disorder in the polymer structures. The extent of exchange is shown to be related to the proportions of large side chains in the samples and also to the water sorption values. It is shown that the decrease in the absorbance of the 3300 cm.−1 band of the polyamide films is a reasonably satisfactory measure of the extent of the H → D exchange in these films, provided that changes in band width are taken into account.
Preparation and structure of some carbon monoxide—formaldehyde copolymers
Authors: Ragazzini Mario , Modena Mario , Gallinella Enzo , Cevidalli Guidobaldo
Published: April 2003

Polymers obtained by reaction between formaldehyde and carbon monoxide under anhydrous conditions in presence of Lewis acids are described. Mass balance and elemental analysis show that the CO/CH2O molar ratio in the polymers can reach unity as maximum value. Ammonolysis of the products (A) having a CO/CH2O molar ratio less than 1 gives glycolamide, diglycolamide, and hexamethylenetetramine. Ammonolysis of the products (B) having a CO/CH2O molar ratio about 1 gives glycolamide, diglycolamide, and traces of hexamethylenetetramine. These results show that the chain of polymer A contains the structural units: COCH2O, COCH2OCH2COO, and CH2O, while polymer B contains almost exclusively the structural units COCH2O and COCH2OCH2COO. Infrared spectra of the products are in good agreement with these results and show the presence of ester, ether, and acetal bands in the main chain of the polymers. The polymer structure is described, and a reaction mechanism is proposed.
Undecoupled and decoupled high resolution nuclear magnetic resonance study of poly(vinyl chloride)
Authors: Satoh Shiroh
Published: April 2003

High resolution nuclear magnetic resonance spectra of two kinds of poly(vinyl chloride) and the model compounds, meso and racemic 2,4‐dichloropentane were studied by normal and spin decoupling technique to elucidate the polymer structure. Unlike the methylene resonance of meso 2,4‐dichloropentane which has been observed as an AB type quartet, only a singlet has been observed as the methylene resonance in isotactic sequences of poly(vinyl chloride) in spin‐decoupled spectra. Two peaks of decoupled spectra of the polymer at 7.76 and 7.96 τ are due to methylene protons in isotactic and syndiotactic sequences in the diad, respectively, and the other three peaks at 5.43, 5.53, and 5.69τ correspond, respectively, to syndiotactic, heterotactic, and isotactic units in the triad. By analyzing decoupled spectra of the two kinds of polymer, parameters of local regularity have been determined. A theoretical treatment for the spectrum for four nuclei ABX2 has been applied to analysis of the methylene resonance of meso 2,4‐dichloropentane.
Polymerization of 2‐nitroolefins
Authors: Sovish R. C. , Boettcher W.
Published: April 2003

A series of 2‐nitroolefins was synthesized and polymerized, with particular attention given to 2‐nitrobutene. Several catalysts were compared, and the sodium cyanidedimethylformamide system studied in detail. Monomer aging had a pronounced effect on the polymerization of the nitromonomers. The polymerization under ideal conditions is exceedingly fast, and evidence favors chain termination by chain transfer to monomer. Molecular weights, even under optimum conditions, were low, and solvents with high dielectric constants were ordinarily necessary for polymer formation. The effect of chain length on polymer properties was also determined.
Kinetics of the γ‐radiation‐induced low temperature polymerization of methyl methacrylate
Authors: Lipscomb N. Thornton , Weber Edwin C.
Published: April 2003

Studies have been made of the rates of γ‐radiation‐initiated polymerization of methyl methacrylate in bulk between the temperatures of −19 and −49°C. and at radiation intensities from 3.77 × 105 to 1.35 × 105 rad/hr. The activation energy over this temperature range was found to be 3.85 kcal./mole at 3.77 × 105 rad/hr. The rate of the reaction was found to be proportional to the intensity to the 0.33 power at both −19°C. and −49°C. Molecular weight information showed that transfer to monomer was unimportant in the polymerization. Nuclear magnetic resonance studies showed that the amount of syndiotacticity in the polymer increases with decreasing temperature.
Electron spin resonance spectra of poly(methyl methacrylate) irradiated at 77°K
Authors: Hajimoto Yoshioki , Tamura Naoyuki , Okamoto Shigeharu
Published: April 2003

It is shown that there exists a difference in the electron spin resonance spectrum of poly(methyl methacrylate) irradiated with electrons and observed at 77°K. and that at room temperature. One of the radicals trapped at 77°K. is probably ·COOCH3, which gives the spectrum of a single line, and the others giving triplet and quartet are perhaps ·CHO and ·CH3, the splitting of which are 132 gauss and 23 gauss, respectively. With the elevation of the annealing temperature the unstable radicals recombine or convert to the stable radicals; near room temperature they are completely replaced by the stable radical which gives the nine‐line spectrum.
Crystal structure of the γ‐form of nylon 6
Authors: Arimoto H. , Ishibashi M. , Hirai M. , Chatani Y.
Published: April 2003

The crystal structure of the γ‐form of nylon 6 (polycaproamide) obtained by the iodine treatment of the α‐from of nylon 6 has been determined by x‐ray diffraction. The unit cell contains four repeating units \documentclass{article}\pagestyle{empty}\begin{document}$ [\rlap{--} ({\rm CH}_2 \rlap{--})_5 {\rm CONH \hbox{---}}] $\end{document} and is monoclinic with a = 9.33 A., b = 16.88 A. (fiber axis), c = 4.78 A., β = 121°. The space group is P21/a. There is considerable deviation from the planar configuration in the amide group of the chain. The plane of the CH2 chain zigzag lies nearly parallel to the (001) plane. The crystal is composed of the pleated sheets of the parallel chains joined by hydrogen bond between the adjacent chains. The chain directions are opposite in alternating sheets. The hydrogen‐bond length is 2.83 A., a reasonable figure for an NH·. O chains joined by a hydrogen bond between the adjacent chains. The direction of the hydrogen bond makes an angle of 12° with the (100) plane, and the CO and NH bonds are nearly colinear. The amide groups lie at the same level in the cell.
An improved method of calculating copolymerization reactivity ratios
Authors: Tidwell Paul W. , Mortimer George A.
Published: April 2003

A nonlinear least‐squares method for solving forr1andr2the copolymerization reactivity ratios, is explained. This new method is superior to all other methods that have been used heretofore in the following ways: (1) a unique pair of values is obtained which does not depend on the judgment of the person examining the data; (2) this pair of values can be shown mathematically to be the best pair obtainable from the data at hand; (3) the errors are quantitatively defined in meaningful terms: and (4) the data are checked to see how well they fit the copolymer equation. A basis for selecting experimental conditions which will provide data from which precise values of the reactivity ratios can be obtained is explained, and experimental conditions appropriate for obtaining these precise values over a wide range ofr1,r2values are presented in tabular form.
Polybenzimidazoles. IV. Polybenzimidazoles containing aryl ether linkages
Authors: Foster Robbie T. , Marvel C. S.
Published: April 2003

Some polybenzimidazole polymers which have aryl ether linkages between the recurring units have been prepared in order to study their thermal stability and their film‐ and fiber‐forming properties. All of the polymers prepared were soluble, high molecular weight materials with very good thermal stability.
Thermal oxidation of deuterated polypropylenes
Authors: Beachell H. C. , Beck D. L.
Published: April 2003

This paper describes some of the aspects of the thermal oxidation of deuterated isotactic polypropylenes. Several polymers of propylene, deuterated at different sites along the polymer chain, were subjected to a kinetic treatment designed to establish the comparative rates of oxidation at different temperatures. Infrared spectroscopy was used to follow the kinetics over the temperature interval 100–130°C. These experiments have shown the existence of a deuterium isotope effect for the thermal oxidation of polypropylene.
Thermal conductivity of high polymers
Authors: Hansen David , Ho Chong C.
Published: April 2003

The thermal conductivities of linear high polymers were studied experimentally and theoretically. A theory of thermal conductivity in linear amorphous high polymers was derived based on a simple model of molecular structure. Predictions on the effects of molecular weight and molecular orientation on thermal conductivity taken from the theory agree with available experimental data. New data on the thermal conductivity of linear polyethylene and some polyethylene–wax blends are presented. Temperature dependence of the thermal conductivity in polyethylene was analyzed by the per cent crystallinity concept to obtain results which are in accord with the phonon theory of thermal conductivity in dielectric crystals.
Gel formation in polyolefins exposed to ionizing radiation
Authors: Lyons B. J.
Published: April 2003

It is shown that a reasonable value for the ratio of main chain scission to crosslinking rates in a number of polyolefins at infinite dose is close to zero. Moreover, the sum of the sol fraction (s) and its square root \documentclass{article}\pagestyle{empty}\begin{document}$ (\sqrt s) $\end{document} in almost all of the polymers studied is proportional to some fractional power of reciprocal dose. There is some slight evidence to suggest that \documentclass{article}\pagestyle{empty}\begin{document}$ s + \sqrt s $\end{document} in relatively low molecular weight polyolefins, which initially contain small amounts of reactive carbon–carbon unsaturation and have random distributions, may be proportional to the square root of the reciprocal dose. There is already good evidence that main chain scission rates in polypropylene and poly‐1‐pentene decrease with increasing dose: such a variation may account for the observed relationship in these polymers and presumably also in polyethylene. Another possible explanation is that the chance of a molecule becoming attached to the crosslinked network depends not only on the number of monomer units it contains, but also on the chance that a previous radiation event (such as trans‐vinylene formation) has already occurred in that molecule.
Dye‐sensitized photopolymerization. II. Enhanced sensitization by combination of a cationic and an anionic dye
Authors: Chen Catherine S. Hsia
Published: April 2003

In dye‐sensitized photopolymerization of the redox type, enhanced rates and quantum yields of polymerization were achieved by employing suitable combinations of a cationic and an anionic dye. The enhancement could be attributed to the more reactive new species of the sensitizing dye molecules produced as a result of an interaction between the cationic and the anionic dyes. In a combination of two cationic dyes where practically no interaction between the dyes was indicated, essentially no effect on the polymerization was observed.
Dye‐sensitized photopolymerization. IV. Enhanced rates of polymerization of acrylamide in ethylene glycol, sensitized by thiazine dyes with triethanolamine
Authors: Chen Catherine S. Hsia
Published: April 2003

The polymerization of acrylamide, in ethylene glycol, induced by visible light, with methylene blue–triethanolamine as the sensitizing system, was found to follow a steadystate kinetic scheme after an induction period. The rate was proportional to the half power of the absorbed light intensity and to the second power of the initial monomer concentration. In an experimentally convenient range of dye concentration the rate increased with the dye concentration. The molecular weights of the polymers were in the range of 3.0 × 104–2.5 × 105; they were insensitive to the absorbed light intensity; they increased with the initial monomer concentration and decreased with the initial dye concentration. The induction period was inversely proportional to the first power of the light intensity. Polymerization in the ethylene glycol systems was found to proceed at considerably faster speed than in the aqueous systems. The faster polymerization was attributed primarily to the fact that methylene blue at all concentrations employed existed principally in the monomeric form in the ethylene glycol systems. New methylene blue N–triethanolamine and methylene green–triethanolamine also were investigated as the sensitizing systems for the polymerization of acrylamide in ethylene glycol. Similar results as with methylene blue–triethanolamine were obtained.
Thermal degradation of poly(methyl methacrylate) in a closed system
Authors: Clark J. E. , Jellinek H. H. G.
Published: April 2003

The thermal degradation of poly(methyl methacrylate) has been studied with unfractionated and fractionated polymer samples over a temperature range of 275–400°C. in a closed system by a new technique. Kinetic data have been obtained at temperatures about 100°C. higher than was possible previously. The results are compared with those obtained in open systems. Two main degradation reactions are operative. It is shown that the energies of activation for these reactions do not vary with polymer chain length in accordance with what is to be expected from the usually assumed depolymerization mechanisms. The termination reactions are diffusion‐controlled. Hydrogenation by Adam's catalyst and bromination of the polymers have only moderate effects on the rate of degradation.
Shear dependence of viscosity–molecular weight transitions. A study of entanglement effects
Authors: Chinai Suresh N. , Schneider William C.
Published: April 2003

The flow behavior of concentrated polymer solutions covering molecular weights up to 150,000 were examined at shear rates up to 200,000 sec.−1. The viscosity–molecular weight–shear rate results of previous workers recognizing only single critical molecular weight M*, above which ordinary Bueche entanglements dominated the flow, were compared with our findings in which two distinct critical molecular weights, upper M* and lower M** exist. These results are compared with the theory, and new interpretations are presented.
Analysis of oligomerization kinetics of styrene on the electronic digital computer
Authors: Tsuchida Eishun , Mimashi Setsuo
Published: April 2003

The mechanism of radical oligomerization by chain transfer reaction was studied in connection with the distribution of molecular weight of the obtained oligostyrene. In this case, the styrene–CCl4 system was selected as model for this purpose. The kinetics of the chain transfer reaction is difficult to analyze because the concentrations of components in the system varies along with oligomerization. The rates of component reactions expressed by the simultaneous differential equations were solved by utilizing an electronic digital computer (IBM 650). Consequently, the analytical values and the experimental data showed good agreement, and the correlation among the coefficients of kinetic velocity in the system was clarified, yielding much information regarding the control of oligomerization.
Scission reactions in some vinyl and vinylidene polymers
Authors: Tobolsky Arthur V. , Norling Parry M.
Published: April 2003

Rates of autocatalyzed oxygen absorption and chain scission were measured at 160°C. and 1 atm. oxygen pressure for copolymers of ethyl acrylate–methyl methacrylate and ethyl acrylate–methyl α‐chloroacrylate. The crosslinked homopolymers of both the vinylidene‐type monomers were very resistant to oxygen uptake and oxidative scission. Increasing amounts of ethyl acrylate in the copolymer systems increased the rate of oxygen absorption and chain scission. Slightly crosslinked poly(methyl methacrylate) containing 5% of dicumyl peroxide showed rapid chain scission at 140°C. in the absence of oxygen and negligible chain scission in the presence of oxygen. The same experiment carried out with poly(ethyl acrylate) shows the reverse behavior: crosslinking and little scission in the absence of oxygen and efficient chain scission in the presence of oxygen. Chemical mechanisms are presented to account for these results.
Kinetic study of the polymerization of α‐d‐styrene and/or styrene by homogeneous catalysis. Part II
Authors: Overberger C. G. , Jarovitzky P. A.
Published: April 2003

Initial rates of polymerization using the (C5H5)2TiCl2Al(C2H5)2Cl homogeneous catalyst system, were determined for homo and copolymerizations of styrene, styrene‐α‐C14, α‐d‐styrene, p‐methylstyrene, and m‐methylstyrene. Homopolymerization rates of styrene as a function of Al/Ti ratio indicate three rate maxima of apparently equal magnitude near Al/Ti ratios of 3.0, 11.0, and 16.0. Copolymerizations of gE; 97.5% α‐d‐styrene and styrene as a function of Al/Ti ratio yielded no rate maxima but appeared to be a linear function of the Al/Ti ratio employed. α‐d‐Styrene yielded higher initial polymerization rates than styrene under all tested experimental conditions. These rate increases as a function of monomer deuteration at the α position are related to a higher concentration of active centers. A reaction scheme is proposed in which the predominant mode of formation of active centers occurs via alkylation of titanium but by a cationic mechanism. The observed isotope effect with the use of α‐d‐styrene is related to the stability of the cationically formed active centers. Destruction of these active centers is is suggested to result in either an α‐alkylated new monomer and/or low molecular weight oligomers. An isotopically controlled unimolecular decomposition step is suggested as a mode of termination and/or destruction of potential active centers resulting in divalent titanium; probably (C2H5)2Ti. The predominant mode of termination and/or destruction of active centers appears to occur by a bimolecular mechanism which is related to the experimentally observed monomer dependence of the initial rate of polymerization.
Hydrodynamic friction coefficients for cellodextrins in water
Authors: Kurath Sheldon F. , Bump Donald D.
Published: April 2003

The diffusion coefficients for the cellobiose through cellohexaose members of the cellodextrin series were determined in water. The molecular friction coefficients calculated on the basis of the Einstein diffusion equation can be represented by, ζN = N ζa + 2ζe, where ζa is the monomeric friction coefficient of an anhydroglucose unit, ζe is a friction coefficient assigned to a terminal monomer unit due to its additional hydrodynamic surface, and N is the degree of polymerization. For the cellodextrins, ζa is 1.25 × 10−9 dyne‐sec./cm., and ζe is 2.42 × 10−9 dyne‐sec./cm. The monomeric friction coefficient of the anhydroglucose unit was found to agree with the value calculated from literature data on the diffusion of cellulose in cadoxen. The calculations were based on the Ptitsyn‐Eizner theory for the hydrodynamic behavior of the “wormlike” chain. The partial specific volumes of the cellodextrins were found to decrease from glucose to cellotriose and then to increase from cellotriose to cellohexaose.
Poly(chloroaldehydes). II. Polymerization of chloral
Authors: Rosen Irving , Sturm C. L. , McCain G. H. , Wilhjelm R. M. , Hudgin D. E.
Published: April 2003

Chloral was polymerized by means of cationic and anionic initiators and the products compared. Anionic catalysts readily produce high molecular weight polymer (DP ∼ 300–600), but a DP of only 200 could be produced with cationic catalysts. The anionic system apparently initiates and propagates polymerization much more readily than the cationic system. This effect is attributed to the inductive effects of the chlorine atoms on the chloral. Little difference was found when products of similar DP were compared as to x‐ray diffraction pattern, infrared spectrum and tractability. This is believed due to the single type of structure which is sterically favored. Various cyclic compounds of chloral could not be made to undergo polymerization under cationic initiation. The conditions required to effect ring opening were too rigorous to enable polymerization to take place.
Infrared spectra of polybutadienes
Authors: Binder John L.
Published: April 2003

It is shown, by analytical resolutions of the spectra of isomerized cis‐1,4‐polybutadienes, that the band due to hydrogen out‐of‐plane vibrations of cis‐CHCH groups appears at 740 cm.−1 and that the apparent shift of this band to lower frequencies, as the amount of cis‐CHCH decrease in a polybutadiene, is due to the presence of other bands in this region. Some possibilities as to the origins of these other bands are discussed. It is also shown that there are some bands in the 10–11 μ region of polybutadiene spectra which are probably connected with vibrations of cis‐CHCH groups and that there probably are others which are not due to either cis‐CHCH or trans‐CHCH or CH2CH. Some possibilities regarding the origins of these bands are discussed. The bands found here explain in large measure the appearance of polarization spectra of high‐cis 1,4‐polybutadienes.
Polymerization of 4‐vinylcyclohexene by the cyclic polymerization mechanism
Authors: Butler George B. , Miles Marion L.
Published: April 2003

4‐Vinylcyclohexene is an example of a 1,5‐diene and is functionally capable of under‐going cyclic polymerization. Polymerization to soluble polymers was accomplished by cationic and Ziegler‐type initiators. Cationic initiation resulted in 28% conversion to polymer, of which 85% was soluble, having intrinsic viscosity of 0.11 dl./g. Infrared and nuclear magnetic resonance analyses led to the conclusion that cyclization of the monomer occurred to the extent of almost 50%. Ziegler‐type initiation resulted in 20% conversion to polymer of which 45% was soluble, essentially saturated, and having intrinsic viscosity of 0.04 dl./g. X‐ray diffraction studies on these polymers indicated no appreciable degree of crystallinity.
Radiation‐induced polymerization and other reactions of n‐perfluoropentadiene‐1,4 at high temperature and pressure
Authors: Brown D. W. , Fearn J. E. , Lowry R. E.
Published: April 2003

The radiation‐induced polymerization of n‐perfluoropentadiene‐1,4 was studied at temperatures of 100–170°C. and pressures of 8,000–15,000 atm. Kinetic evidence indicates that polymerization occurs by a free radical reaction; the activation energy is between 14 and 17 kcal./mole and the activation entropy is −8 ± 5 e.u./mole. Transfer with monomer limits the number‐average degree of polymerization to values of 40 or less except in special circumstances. Dimerization and double bond migration occur to some extent; n‐perfluoropentadiene‐1,3 is formed in the latter process. It and the 1,4‐diene copolymerize; the latter undergoes cyclic addition so that the polymers are soluble and have little perfluorovinyl unsaturation. The polymers are brittle if the fraction of 1,3‐diene in the polymer is less than 0.1. They are rubbery and of considerably higher molecular weight if the fraction of 1,3‐diene is greater than 0.4. The thermal stability of the polymers decreases as the content of 1,3‐diene increases.