bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystallite orientation and spiral structure of cotton. Part I. Native cottons
Authors: DeLuca Lloyd B. , Orr Rollin S. 
Published: April 2003

AbstractA method is demonstrated by which both crystallite orientation and spiral angle can be directly determined from the x‐ray tracings of the 002 diffraction arcs of combed bundles of cotton fibers. Sisson has shown, qualitatively, that the 002 arcs displayed by fibers with a spiral structure can be explained by assuming two equal crystallite distributions separated by twice the spiral angle. If this distribution of crystallites is assumed to be Gaussian, the experimental are can be generated theoretically. Such an analysis is applied to several cottons of widely different orientations and the calculated parameters are compared with those of the gross arcs.
Effect of asymmetric centers on free radical polymerization and the properties of polymers: Methacrylyl alanine, methacrylyl glutamic acid, acrylyl glutamic acid, and their polymers
Authors: Kulkarni R. K. , Morawetz H. 
Published: April 2003

AbstractMethacrylyl‐D‐alanine, methacrylyl‐L‐glutamic acid, and acrylyl‐L‐glutamic acid were homopolymerized or copolymerized with their enantiomorphs in dioxane, aqueous 0.1N HCl, and in water at 90% neutralization of the monomer. The homopolymerization of the optical isomer and copolymerization of racemic mixtures proceeded at identical rates for the first two monomers at 90% neutralization and for methacrylalanine in 0.1N HCl and in butanol, while with methacrylyl glutamic acid in 0.1N HCl the racemic monomer polymerized slightly more slowly than the pure optical isomer. The optical activities of the homopolymers in water varied with the polymerization medium, probably because of differences in the degree of stereoregulation. Optical activities of copolymers prepared from a mixture of the enantiomorphic monomers containing 85% of L and 15% of D isomer were mostly lower than 70% of that of the L homopolymer, which suggests that the growing chain radical has a bias toward an alternation of the steric configurations of the monomer units. Changes in the optical activities of the homopolymers with degree of ionization were compared with the behavior of pivalyl‐L‐alanine, pivalyl‐L‐glutamic acid, and isobutyryl‐L‐glutamic acid. Poly(methacrylyl‐D‐alanine) behaved in a manner similar to that of its analogue, but the changes in the optical activities of the methacrylyl‐ and acrylyl glutamic acid polymers followed a complex pattern quite different from that of their analogues. The results were interpreted on the assumption that (1) in the polymer the intrinsically more weakly acidic γ carboxyls ionize first since their ionization leads to a lower charge density than the ionization of α‐carboxyl groups and (2) the extension of the polymer backbone affects the optical activity by modifying the conformational distribution in the side chains. It is not believed that, in the cases investigated, helix formation makes an appreciable contribution to the difference between the optical activities of the polymer and their analogues.
The polymerization of styrene sulfide
Authors: Noshay Allen , Price Charles C. 
Published: April 2003

AbstractStyrene sulfide autopolymerizes at room temperature to low molecular weight polymer. Considerably higher molecular weights are obtained with certain Lewis acid‐type catalysts, i.e., [η] = 2.05 with chlorocadmium butyl mercaptide. The molecular weight is inversely proportional to the polymerization temperature. Polystyrene sulfide is obtained in about 50% conversion as a soluble, amorphous, white solid which softens at about 50°C. and which forms fairly tough, rubbery films. Styrene sulfide dimerizes in the presence of dimethyl sulfate to 2,5‐diphenyl‐p‐dithiane. Oxidation of polystyrene sulfide gives polystyrene sulfone. Polystyrene sulfide is relatively unstable toward heat and ultraviolet light, both in the presence and absence of air. The cyclic dimer is one of the products obtained in the thermal degradation of the polymer prepared with chlorocadmium butyl mercaptide.
Indirect evaluation of orientation in polycrystalline materials
Authors: Sack R. A. 
Published: April 2003

AbstractFor a polycrystalline material with partial orientation, relations are established between the mean square cosines of the angles ρ between the axis of orientation and lines fixed with the lattice. Experimentally, the mean orientation f = <3/2 cos2ρ−1/2> for the normal to a lattice plane can be determined from the intensity distribution of the corresponding Debye‐Scherrer ring. As already shown by Wilchinsky, the mean orientation for any line can, in general, be expressed as a linear function of the values of f for five other lines, with coefficient depending on the directions of the lines within the lattice, but not on the degree of orientation of the material. For crystallites with monoclinic or higher symmetry or lamellar shape, or if all the lines considered lie within one lattice plane or along its normal, the number of independent determinations reduces to 3 or 2, for needle‐shaped crystallites even to 1.The same number of measurements are needed if the rings contain several unresolved reflections. If more than the minimum number of observations are available, more accurate results can be obtained by a least square formalism; with composite rings the strongest reflections do not necessarily possess the highest statistical weight. The accuracy of the calculated results is estimated in terms of the errors of the experimental data.The new formalism is applied to a fresh analysis of the measurements by J. J. Hermans, P. H. Hermans, Vermaas, and Weidinger on regenerated cellulose.
Molecular weight distribution of graham salt
Authors: Martens William S. , Rieman Wm. 
Published: April 2003

AbstractA method is described for determining the molecular weight distribution of Graham salt (sodium polyphosphate) by fractional precipitation with acetone. The method differs from that of Van Wazer4 in the following respects. (1) The use of smaller samples permits the fractionation to be performed in less time with consequent less hydrolytic degradation during the process. (2) Fractions are refrigerated from the moment of separation until the analysis; this further decreases degradation. (3) Homogeneous precipitation gives a smoother curve of molecular weight distribution. (4) More fractions are obtained. (5) Cyclic compounds are determined both in the original sample and in those fractions where they occur in significant quantity, and corrections for their presence are applied.
Studies in condensed phosphates. Part I. Sodium metaphosphates and their derivatives with calcium, barium, and zinc salts
Authors: Mehrotra R. C. , Gupta V. S. 
Published: April 2003

AbstractDerivatives with the formulas [Na4Ca(PO3)6]n, [Na4Ba(PO3)6]n, and [Na4Zn(PO3)6]n have been prepared by heating together mixtures of NaH2PO4.2H2O, CaO (or Ba(OH)2.‐8H2O or ZnO), and (NH4)2HPO4 in the molar ratios of 4:1:2 at 700 and 800°C. for 1 hr. The number‐average molecular weights of these derivatives have been measured by the endgroup titration method. Their conductance has been measured in aqueous solution of varying concentration, and their properties compared with those of Graham's salt (NaPO3)n prepared under similar conditions.
Preparation of polymeric materials with semiconductor properties
Authors: Geĭderikh M. A. , Davydov B. E. , Krentsel' B. A. , Kustanovich I. M. , Polak L. S. , Topchiev A. V. , Voĭtenko R. M. 
Published: April 2003

AbstractThermal treatment of polyacrylonitrile synthesized by means of ionic polymerization, radiation polymerization, or redox initiation yielded substances giving signals in the EPR spectrum and possessing semiconductor properties. From the temperature dependence of the electroconductivity the activation energy was determined, and from the data on the EPR spectra the number of unpaired electrons (1018–5 × 1019/g.) was calculated. The thermoelectromotive force was determined and the existence of a Hall effect established. Addition of copper, iron, and chromium ions to the initial polymer lowers the activation energy and increases the width of the EPR signal. On dehydrobromination of natural rubber bromides and dehydrochlorination of polyvinyl chloride, conjugated double bond polymers were obtained, and their electrical properties were determined. Semiconductor properties were found in condensation products of phthalic anhydride with hydroquinone and the activation energy of these compounds was determined.
Chlorination of phenol‐aldehyde resins
Authors: Rabek T. I. , Kosmider J. 
Published: April 2003

AbstractThe chlorination of phenol formaldehyde and cresol‐formaldehyde resins has been carried out with sulfuryl chloride in the presence of free radical catalyst (benzoyl peroxide azobisisobutyronitrile). Independently of the amount of sulfuryl chloride and of the reaction conditions, some aromatic substitution occurs besides the introduction of labile chlorine in the methyl group. The chlorinated novolacs are unable to react with hexanemethylenetetramine. In the chlorination, 33.4% chlorine participates, i.e., 1.7 chlorine atoms per structural unit of cresol novolac, of which 16.2% (0.82 chlorine/unit) was bounded as aliphatic chlorine. The corresponding values for phenol novolac were: 20.4% chlorine (0.78 atom/unit) and 2.7% aliphatic (0.1 atom/unit). The synthesis of phenolic and cresolic resites, at different ratios of phenol/formaldehyde and in the presence of different amounts of catalyst, has been carried out. Resites obtained at a ratio of 1 mole NaOH and 1.5 moles formaldehyde for 1 mole phenol, and submitted to a post‐heating at 100–110°C., show the strongest swelling in such solvents as benzene, dioxane and chloroform; this fact is essential for the efficiency of the chlorination. During the reaction in benzene, 7% of labile chlorine is introduced in the cresolic resite. Phenolic resites, chlorinated in the same conditions, show no labile chlorine in agreement with the results obtained during the chlorination of the novolacs. By chlorination of a resite, strongly swollen in dioxane (100%), 12% mobile chlorine is incorporated, i.e., 1 chlorine atom for two rings. During the chlorination in benzene as well as in dioxane an appreciable degradation of the resite was observed; 40 to 50% of the resite become soluble, and this solution gives on precitation a resin which is analogous to the chlorinated novolaces. The degree of degradation depends on the resite type; for example, the degradation is particularly pronounced during the chlorination of ammoniacal resins. The resites obtained without excess of formaldehyde and in the presence of small amounts of a strong base as catalyst are the chemically most stable substances.
Condensation polymers of ferrocene derivatives
Authors: Knobloch F. W. , Rauscher W. H. 
Published: April 2003

AbstractExperimental details are given for the preparation of 1,1′‐ferrocenedicarboxylic acid and 1,1′‐ferrocenedicarbonyl chloride. Ferrocenedicarbonyl chloride was used to prepare novel condensation polymers containing the ferrocene nucleus as part of the main polymer chain. Interfacial polycondensation was used for the preparation of polyamides from ethylenediamine, hexamethylenediamine, piperazine, and p‐phenylenediamine. The polyamide from piperazine was obtained in crystalline form from tetrachloroethane. Polyesters were prepared from 4,4′‐ isopropylidinediphenol and hydroquinone. The polyester from ethylene glycol was prepared in low molecular weight from 1,1′‐dicarbomethoxyferrocene by transesterification.
Preparation and crosslinking properties of silicon tetrachloride‐tetramethyldisiloxane diol condensation products
Authors: Mayo Frank R. 
Published: April 2003

AbstractBenzene‐soluble copolymers have been produced in high yields by the reaction of silicon tetrachloride with tetramethyldisiloxane diol and pyridine in very dilute solution in benzene. These copolymers average one to four dimethylsiloxane units per SiO2 unit. The copolymers have been equilibrated to insoluble resins by the action of heat alone or a basic catalyst. They also will effect crosslinking of silicone gum rubbers by equilibration. An improved preparation of octamethylspiro[5.5]pentasiloxane is described.
Studies in condensed phosphates. Part II. Viscosities of simple and complex sodium metaphosphate solutions
Authors: Mehrotra R. C. , Gupta V. S. 
Published: April 2003

AbstractThe viscosity‐average molecular weights M̄w of [Na4Ca(PO3)6]n and [Na4Ba(PO3)6]n polymers determined by Staudinger's equation in 0.0035N NaCl solution were found to be lower than their number‐average molecular weights M̄n determined by endgroup titration. The above anomaly has been shown to be owing to the effect of bivalent cations liberated in equilibria of the type:

This has been further confirmed by measurments of M̄w by the light scattering method. In aqueous solutions the greater change in viscosity of [Na4Ca(PO3)6]n solution with dilution is also ascribed to the secondary dissociation of the polymeric anions at lower concentrations.
A study of vinylidene chloride‐ vinyl chloride copolymers
Authors: Enomoto Satoru 
Published: April 2003

AbstractVinylidene chloride (VDC) and vinyl chloride (VC) copolymers were prepared in various feed ratios. A composition equation given by Mayo and Lewis was discussed in respect to the feed ratios and the corresponding composition ratios of the copolymers. Three kinds of CH deformation modes, assigned respectively to VC in the three combinations of monomer units, VDC‐VC*‐VDC, VDC‐VC*‐VC, and VC‐VC*‐VC, were deduced from their infrared spectra. The assignments were confirmed with the infrared spectra of copolymers of 80:20 feed ratio at various conversions. The CH deformation mode of VC* in the VDC‐VC*‐VDC part appears at 1197 cm. −1 (λ1 band), in the VDC‐VC*‐VC part, at 1235 cm. −1 (λ2 band), and in the VC‐VC*‐VC part, at 1247 cm.−1 (λ3 band). These bands became strong as the conversion increased, and this agreed with the variation of the chlorine contents of the copolymers at 80:20 feed ratio. A new method of obtaining the distribution of the composition of VDC‐VC copolymer and the lengths of their sequences was established. The monomer reactivity ratios obtained with the new method are r1 = 3.15 and r2 = 0.23.
The adsorption of polymethyl methacrylate from solution
Authors: Ellerstein Stuart , Ullman Robert 
Published: April 2003

AbstractPolymethyl methacrylate has been adsorbed from solution onto glass and iron (oxide coated) surfaces. The adsorption isotherms have been studied as a function of solvent, molecular weight of polymer, and temperature. The solvent effect is significant and complicated depending on the interactions between polymer and solvent, polymer and surface, and solvent and surface. The amount of polymer adsorbed is relatively independent of molecular weight, and in all cases studied the amount adsorbed decreased with increasing temperature. It was found that the adsorption process was often not reversible in the usual time scale of an experiment. It was emphasized that thermodynamic and statistical thermodynamic arguments are not valid in these cases where adsorption is reversible.
Polymerization of vinyl monomers containing boron. I. B‐trivinyl‐N‐triphenylborazine and B‐triallyl‐N‐triphenylborazine
Authors: Pellon Joseph , Deichert W. G. , Thomas W. M. 
Published: April 2003

AbstractSynthesis of B‐trivinyl‐N‐triphenylborazine is reported. Polymerization of this compound and of B‐triallyl‐N‐triphenylborazine is discussed. The vinyl derivative does not homopolymerize, but the allyl compound polymerizes with difficulty, yielding a gel. Both of these borazines copolymerize with styrene and with methyl methacylate. The vinyl compound is comparable to these reference monomers in reactivity toward their radicals. These results are explained by assuming that the steric effect of phenyl groups makes adjacent vinyl groups inaccessible to hindered reactants. This steric effect prevents an assessment of stabilization of vinyl radicals by resonance and polarity in the borazine ring.
Chlorinated isotactic polyhydrocarbons
Authors: Campbell Tod W. , Lyman Donald J. 
Published: April 2003

AbstractChlorinated polyethylene has been known for some time, but is too low melting for many uses. Chlorination of high‐melting isotactic polyhydrocarbons by techniques similar to those used on polyethylene has given similar products, but with higher melting points. Flame‐resistant films and fibers have been prepared by conventional techniques.
Molecular vibrations and structure of high polymers. II. Helical parameters of infinite polymer chains as functions of bond lengths, bond angles, and internal rotation angles
Authors: Miyazawa Tatsuo 
Published: April 2003

AbstractHelical conformations of infinite polymer chains may be described by the helical parameters including ρi (the distance of the ith atom from the helix axis), dij (the translation along the axis), and θij (the angle of rotation about the axis on passing from the ith atom to the jth). For the polymer main chain (M)∞, (M1M2)∞, (M1M2M3)∞, (M1M2M3M4)∞, (M1M2M3M4M5)∞, (M1M2M3M4M5M6)∞ concise mathematical equations for the helical parameters are given in terms of the internal coordinates, such as the bond lengths, the bond angles, and the internal rotation angles. These equations are useful in calculating the internal coordinates and in selecting likely structure models from the helical parameters experimentally determined. The internal coordinates and helical parameters of polyethylene, polytetrafluoroethylene, sulfur, selenium, tellurium, isotactic polypropylene, poly‐4‐methyl‐1‐pentene, poly‐m‐methylstyrene, poly‐o‐methylstyrene, polyoxymethylene, polyisobutylene, polypeptides (α helix, parallel‐chain, or antiparallel‐chain extended form), polyglycine II, polyethylene glycol, and syndiotactic polypropylene were calculated and were used for discussing the structure of these helical polymers.
The preparation of membrances
Authors: Carnell Paul H. , Cassidy Harold G. 
Published: April 2003

AbstractA membrane is defined as a solid, porous sheet which, when placed between two phases, may allow the passage of small particles but hinder or prevent the passage of large particles. With this definition as a basis a review is given of methods employed to prepare membranes, with special emphasis on the preparation of organic membranes. Directions are then given for the preparation of thin, uniform membranes 100 to 1500 A. or thicker. Membranes of 500 or 600 A., in thickness with a variation of less than 25 A. across a section as large as 3.5 cm. sq. are described, together with evidence for physical and chemical stability. These are prepared from pyroxylin. Thin membranes were also prepared from Formvar 15/95 E (polyvinylformal from Shawinigan Resins Corp.) and VYDR, blend 7 (a high molecular weight vinylchloride‐acetate resin containing approximately 96% vinylchloride and 4% vinylacetate, from Bakelite). No success was achieved with DYNH (a polythylene from Bakelite); and polyisobutylmethacrylate (Monomer‐Polymer).
Infrared spectra of cis and trans isomers of poly(1,4‐cyclohexylenedimethylene terephthalate)
Authors: Boye C. A. 
Published: April 2003

AbstractInfrared spectra have been recorded for cis and trans isomers of poly (1,4‐cyclohexylenedimethylene terephthalate) (PCHDT). Infrared dichroisms were determined and band assignments were made. From spectra of polymers in both the crystalline and amorphous phases it was determined that the crystalline bands for trans‐PCHDT are virtually the same as those for poly(ethylene terephthalate) (PET), while cis‐PCHDT showed very little change in its spectrum upon a change in phase. The same was found to be true of model compounds of PCHDT and PET. Of the series of compounds—ethylene glycol dibenzoate, 1,3‐propanediol dibenzoate, and 1,6‐hexanediol dibenzoate— the first two compounds exhibited the same crystalline bands as the PET and trans‐PCHDT polymers, but 1,6‐hexanediol dibenzoate showed that the crystalline bands were shifted for the longer glycol chain. It was concluded that not only are the crystalline bands associated with the ‐OCC6H4CO‐ framework of these molecules but they also depend on the rigidity of the esterifying groups or glycol chain segments.
X‐Ray diffraction studies of poly(1,4‐cyclohexylenedimethylene terephthalate)
Authors: Boye C. A. 
Published: April 2003

AbstractX‐ray diffraction methods were employed to determine a‐triclinic unit cell that describes the crystal lattice of poly (trans‐1,4‐cyclohexylenedimethylene terephthalate) (PCHDT). The crystal density was calculated as 1.265 g./cc., assuming one polymer repeat unit per unit cell. The fiber repeat period. 14.2 A., of the trans polymer was compared with the calculated length, 14.7 A., of the fully extended repeating unit. From this comparison, it was concluded that the trans‐PCHDT had the equatorally substituted chair form of the cyclohexane ring, and that the contraction of 0.5 A. Was probably due to toration about the O—CH2—CH bond. The repeat period that and the dimensions of a section of the unit cell, taken normal to the repeat period direction, were determined for cis‐PCHDT. These values give a crystal volume of 346 cu. A. and a true crystal density of 1.313 g./cc. for one polymer repeat per unit cell. A tentative triclinic unit cell was also determined for cis‐PCHDT that accounts for all but three of the diffraction maxima observed. These might be accounted for by another crystal species. X‐ray diffractometer traces were obtained on samples of PCHDT that had varying cis/trans rations. These curves indicated that there is a continuous deformation of the crystal lattice between 15 and 100% trans concentration. It was determined that cross‐stretching and heat‐setting of films of trans‐PCHDT tend to produce alignment of the crystallites such that the 100 planes are roughly parallel to the plane of the film. Low‐angle x‐ray diffraction patterns were obtained and indicated a repeated crystallike structure with a period of 154 A. for cis‐PCHDT and 145 A. for the corresponding trans isomer. Diffraction broadening calculations indicated a crystallite size of 6.3 A. for the trans isomer. This value corresponds to about one‐half the repeat period calculated from the low‐angle x‐ray diffraction pattern. Thus, the repeat period probable corresponds to the length of one crystallite and an adjecent amorphous region of nearly equal size. If the size of the crystallite determined for the trans Polymer is representative, the Polymer molecular weight of 10,000 might paprticipate in as many as five crystallites, while molecules in the prepolymer state with viscosities near 0.3 could participate in only one crystallite.
Polymerization of 2,4‐dimethyl‐6‐vinyl‐s‐triazine
Authors: Coscia Anthony T. , Kugel Robert L. , Pellon Joseph 
Published: April 2003

Abstract2,4‐Dimethyl‐6‐vinyl‐s‐triazine (A) is readily polymerized by free radical initiators to a high molecular weight product. Copolymerization studies with reference monomers

(M1), styrene and methyl methacrylate, gave reactivity ratios with styrene: r1 = 0.12, r2 = 0.92; with methyl methacrylate: r1 = 0.37, r2 = 1.75. The following Q−e values were calculated: with styrene Q2 = 12, e2 = +0.92; with methyl methacrylate Q2 = 2.6, e2 = +1.09. These values indicate that the dimethyl triazinyl moiety is a radical stabilizing and electronegative substituent. Poly(2,4‐dimethyl‐6‐vinyl‐s‐triazine) (PDMVT) is soluble in water and in all the common organic solvents with the exception of aliphatic hydrocarbons. Poly(isopropenyl‐s‐triazine) (PIT) is soluble only in dimethylformamide and chloroform. The latter also softened at a much higher temperature than PDMVT. These differences were considered a result of hydrogen bonding between chains in PIT.