bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusivities and solubilities of methane in linear polyethylene melts
Authors: Lundberg J. L. 
Published: April 2003

AbstractDiffusion 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

AbstractFor 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

AbstractIt 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

AbstractSince 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

AbstractIt 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

AbstractIt 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

AbstractPolyether‐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

AbstractCrosslinked 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

AbstractAnionic 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

AbstractA 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

AbstractEnd‐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

AbstractSpecific 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

AbstractComposition 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

AbstractThe 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

AbstractPolyethylene 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

AbstractThe 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

AbstractSome 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

AbstractThe 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

AbstractThis 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

AbstractPolymers 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

AbstractHigh 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

AbstractA 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

AbstractStudies 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

AbstractIt 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.