bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stereoregular polymerization of 1‐vinylnaphthalene, 2‐vinylnaphthalene, and 4‐vinylbiphenyl
Authors: Heller Jorge , Miller Donald B. 
Published: April 2003

Abstract1‐Vinylnaphthalene, 2‐vinylnaphthalene, 4‐vinylbiphenyl, and styrene were polymerized with Et3Al–TiCl4, Et2AlCl–TiCl3, and Et3Al–TiCl3 catalyst systems. The latter catalyst system gave polymers in 75–95% conversion which were at least 90% isotactic. Extraction with 2‐butanone (MEK) separated the atactic from the isotactic fractions. The polymers were characterized by infrared and nuclear magnetic resonance spectroscopy.
Cyclopolycondensations. VI. Fully aromatic polybenzoxazinones from aromatic poly(amic acids)
Authors: Yoda Naoya , Ikeda Kojuro , Kurihara Masaru , Tohyama Shunroku , Nakanishi Ryoji 
Published: April 2003

AbstractNew high temperature aromatic polybenzoxazinones of high molecular weight have been prepared by the cyclopolycondensation of 4,4′‐diaminobiphenyl‐3,3′‐dicarboxylic acid (I) with aromatic dicarboxylic acid halides (II). The low temperature solution polymerization techniques afforded poly(amic acid) (III) of high molecular weight in the first step. An open‐chain precursor subsequently underwent thermal cyclodehydration along the polymer chain at 200–350°C. in the second step, to give in quantitative yield a fully aromatic polybenzoxazinone (IV) of outstanding heat stability both in nitrogen and in air. The poly(amic acid) is soluble in N‐methyl‐2‐pyrrolidone, and tough, transparent films can be cast from solution. Insoluble aromatic polybenzoxazinone films which possess excellent oxidative and thermal stability were obtained by the heat treatment of the polyamic acid. A detailed account of polymerization conditions in the low temperature solution polymerization of polybenzoxazinones is given, and the reaction mechanisms of cyclopolycondensation of poly(amic acids) and the formation of polybenzoxazinones are discussed.
The formylation of cellulose
Authors: Heath J. E. , Jeffries R. 
Published: April 2003

AbstractThe reaction between formic acid and disordered cellulose is described. It is shown that a degree of substitution as high as 2.5 can be readily obtained without any catalyst. There is no evidence of any difference between the formylation behavior of this cellulose up to the monoformate level and that beyond this level. Formic acid produces ordered, inaccessible regions in disordered cellulose; this behavior reduces the value of the latter material as a calibration standard in formylation studies and also throws doubt on the basic value of formylation as a method of measuring disorder in cellulose. There is evidence that native celluloses formylate less rapidly per unit amount of hydrogenbond‐disordered material than do regenerated celluloses; this may be associated with the fibrillar nature of the native celluloses.
Solid‐state polymerization studies. I. 2‐vinylnaphthalene post‐polymerization initiated by 60Co γ‐irradiation
Authors: Parrish C. F. , Trinler W. A. , Burton C. K. 
Published: April 2003

Abstract60Co γ‐irradiated 2‐vinylnaphthalene was obsreved to post‐polymerize in the solid phase. Plots of conversion versus time indicated a 14% limiting conversion of monomer to polymer. The post‐polymerization was found to be first‐order in monomer with an Arrhenius activation energy of 19.0 kcal./mole.
Radical copolymerization of crotonyl compounds with styrene
Authors: Minoura Yuji , Tadokoro Toshio , Suzuki Yasuyuki 
Published: April 2003

AbstractThe monomer reactivity ratios for the radical copolymerization of crotononitrile (CN), methyl crotonate (MC), and n‐propenyl methyl ketone (PMK) with styrene (St) were measured at 60°C. in benzene and little penultimate unit effect was shown for these systems. The values obtained were: St–CN, r1 = 24.0, r2 = 0; St–MC, r1 = 26.0, r2 = 0.01; St–PMK, r1 = 13.7, r2 = 0.01. The rate of copolymerization and the viscosity of the copolymer decreased markedly as the molar fraction of the crotonyl compound in the monomer mixture increased. The Q–e values were also calculated to be as follows: CN, e = 1.13, Q = 0.009; MC, e = 0.36, Q = 0.015; PMK, e = 0.61, Q = 0.024. A linear relationship was obtained between the e values of the crotonyl compounds and their Hammett constants σm.
Graft polymers: Chain transfer and branching
Authors: Rao S. Prabhakara , Santappa M. 
Published: April 2003

AbstractThe vinyl monomers, methyl methacrylate, ethyl methacrylate, and methyl acrylate were polymerized in the presence of chlorinated rubber or poly(vinyl chloride) in homogeneous solution with benzoyl peroxide as catalyst. A graft polymer was formed by a chain‐transfer reaction involving the growing polymer radicals to the backbone of chlorinated rubber or poly(vinyl chloride), in addition to homopolymer from the monomer. The homopolymer was isolated from the polymer mixture by fractional precipitation from methyl ethyl ketone solution with methanol as precipitant. The chain‐transfer constants for the branching reactions were evaluated. The ratios kp/(kt)1/2 for the grafting reactions were obtained by a correlation of chain‐transfer constants with the extent of branching. The chain‐transfer data were correlated on the basis of an extension of the Q–e scheme of Alfrey and Price to polymer–polymer transfer reactions. Specific effects due to the backbone are found to have considerable influence on the course of the chaintransfer reactions and kp/(kt)1/2 of the grafting reactions.
α,ω‐diols from polymerization of ethylene
Authors: Anderson W. S. 
Published: April 2003

AbstractPolyethylene is prepared in silver perchlorate solution by initiation with dialkyl peroxydicarbonates at 0–40°C. Saponification of the polymer endgroups yields a product rich in α,ω‐diols. Well‐known reactions convert the hydroxyl groups to other functional groups. The diol may be condensed with phosgene so as to increase its molecular weight severalfold or crosslinked with silicon tetrachloride to form a network.
Synthesis of polyurethanes from fluorinated diisocyanates
Authors: Hollander Jerome , Trischler Floyd D. , Gosnell Rex B. 
Published: April 2003

AbstractA number of polyurethanes based on fluorinated aliphatic diisocyanates, perfluorinated aromatic diisocyanates, and chlorinated aromatic diisocyanates have been prepared. The polyurethane prepared from perfluorotrimethylene diisocyanate and hexafluoropentanediol was a rubbery solid which hydrolyzed readily in air to a liquid or sticky solid but was stable if protected from moisture. The products of hydrolysis were isolated and identified. Polyurethanes based on hexafluoropentamethylene diisocyanate were synthesized by reaction of hexafluoropentanediamine with hexafluoropentamethylene bischloroformate and with tetrafluoro‐p‐phenylene bischloroformate. Polyurethanes were synthesized by reaction of tetrafluoro‐p‐phenylene diisocyanate with hexafluoropentanediol and pentanediol. Other perfluoroaryl diisocyanate‐based polyurethanes were synthesized by reaction of tetrafluoro‐m‐phenylene diisocyanate with hexafluoropentanediol and with tetrafluoro‐p‐hydroquinone. Polyurethanes were also synthesized by reaction of tetrachloro‐p‐phenylene diisocyanate and 2,3,5,6‐tetrachloro‐p‐xylylene‐α,α′‐diisocyanate with hexafluoropentanediol.
Gel permeation chromatography: Effect of pore‐size distribution
Authors: Cantow Manfred J. R. , Johnson Julian F. 
Published: April 2003

AbstractThe pore‐size distributions of various grades of porous glass were determined by gas desorption and mercury porosimeter measurements. This allowed the calculation of elution volumes as a function of pore diameters. The coil sizes of polystyrenes in toluene were obtained for a series of molecular weights from hydrodynamic theory and matched with pore diameters. In this manner, expected calibration curves for gel permeation chromatography could be calculated. Good agreement was found with experimental data.
Homopolymers and vinyl chloride copolymers of vinyl esters of chlorinated fatty acids from umbelliferae and limnanthes douglasii
Authors: Liepins R. , Marvel C. S. , Magne F. C. 
Published: April 2003

AbstractHomopolymers and copolymers of vinyl esters of chlorinated C18, C20, and C22 fatty acids with vinyl chloride have been prepared and evaluated. The incorporation of the vinyl ester of chlorinated C18, C20, and C22 acids as comonomers with vinyl chloride produced more flexible copolymers than have other comonomers, yet none have imparted the plasticization that can be obtained by an equal amount of external plasticizer.
Organometallic polymers. I. Synthesis of ferrocene‐containing poly(phosphine oxides) and poly(phosphine sulfides)
Authors: Pittman Charles U. 
Published: April 2003

AbstractPoly(phosphine oxides) and poly(phosphine sulfides) of ferrocene were synthesized in the melt phase. The resulting ferrocene polymers, linked by phosphorus bridges, were thermally stable and infusible solids, of low molecular weight (M̄n < 4000). Phenyldichlorophosphine, phenyldichlorophosphonate, and phenylphosphonothioic dichloride were copolymerized with ferrocene in the melt phase (80–110°C.) with ZnCl2 as a catalyst. As the polymerization temperature was raised, cleavage of cyclopentadiene rings from iron became more pronounced, and cyclopentane‐bridged polymers of ferrocene were produced in competition with the ferrocene–phosphorus polymers. The cleavage‐polymerization process became predominant at 140°C. The structures of poly(phosphine oxides) (and sulfides) of ferrocene were verified by infrared and nuclear magnetic resonance spectroscopy.
Di‐isotacticity of poly(methyl propenyl ether) and double‐bond opening of methyl propenyl ether in cationic polymerization
Authors: Ohsumi Y. , Higashimura T. , Okamura S. , Chujo R. , Kuroda T. 
Published: April 2003

AbstractThe di‐isotacticity of poly(methylpropenyl ether) obtained by the cationic polymerization has been studied by NMR spectra. The NMR spectra of β‐methyl protons of the polymer are decoupled from the β‐methine proton spectra to determine the di‐isotactic fraction in a polymer. The signals of β‐methyl protons at 8.78 and 8.89 τ are estimated as spectra based on threo‐ and erythro‐di‐isotactic diads, respectively. With BF3·O(C2H5)2 as a catalyst, the trans monomer yields a crystalline polymer and its structure is threo‐di‐isotactic. Otherwise, cis monomer produces an amorphous polymer, and it is a mixture of threo‐ and erythro‐di‐isotactic structure. From these results, it is concluded that the double bond in trans monomer is opened exclusively in the cis type, and in cis monomer cis‐ and trans‐openings take place at almost the same rate.
Kinetics of bulk polymerization of trimeric phosphonitrilic chloride
Authors: MacCallum J. R. , Werninck A. 
Published: April 2003

AbstractThe kinetics of the pure bulk polymerization of trimeric phosphonitrilic chloride were investigated in the temperature range 240–255°C. The reaction was found to be secondorder with an activation energy of 57 kcal./mole. Polymerization catalyzed by benzoic acid was first‐order, and the reactivities of benzoic acid and sodium benzoate at 235°C. were found to be about similar. The volatile decomposition products for the benzoic acid reaction were identified. Mechanisms are postulated for the catalyzed and uncatalyzed reactions.
Polymer reactions. V. Kinetics of autoxidation of polypropylene
Authors: Chien James C. W. , Boss C. R. 
Published: April 2003

AbstractThe rate constants for the autoxidation of polypropylene were determined by a combined ESR, volumetric, and chemical method. The values of ki, kp, and kt at 110°C. are 3 × 10−4 sec.−1, 1.9 l./mole‐sec., and 3 × 106 l./mole‐sec., respectively. The values of ki and its activation energy are the same as those for the decomposition of polypropylene hydroperoxide, thus identifying the latter as the principal initiation process. The values of the temperature‐independent kt suggest that secondary peroxy radicals are the terminating species. The rate constants are compared with rate constant ratios for initiated autoxidations of squalane and other related systems.
Retardation of spontaneous polymerization of formaldehyde by acidic substances
Authors: Yokota Hisao , Kondo Masatsune , Kagiya Tsutomu , Fukui Kenichi 
Published: April 2003

AbstractThe stability of liquid formaldehyde produced by pyrolysis of α‐polyoxymethylene was studied in connection with the presence of impurities in the monomer. Liquid monomer was divided into several fractions by means of the distillation. The stability of each fraction for polymerization is dependent on the order of fraction, that is, the monomer obtained in the early fractions of distillation was much more stable with regard to polymerization than later distillate. Analyses of the monomer fractions indicated that various impurities such as carbon dioxide, water, methanol, and methyl formate were present in the early monomer distillates. From the influence of these impurities on the stability of liquid formaldehyde, it was found that small amounts of carbon dioxide and hydrogen cyanide noticeably depressed the polymerization, and that with acetic acid and maleic anhydride the rate of polymerization decreased with small amounts of these compounds but increased with an excess of additive. On the other hand, the addition of these acidic substances did not affect the molecular weight of the polymer produced. From the fact that the acidic substance retards only the initiation of polymerization, it has been concluded that the spontaneous polymerization of formaldehyde in bulk or in toluene solution is initiated by an anionic species.
Depolarized light and differential thermal analyses of some polyolefin transitions
Authors: Barrall Edward M. , Gallegos Emilio J. 
Published: April 2003

AbstractThe depolarized light intensity (DLI) technique detec's transitions in birefringent materials by simultaneously measuring sample temperature and intensity of polarized light roatated by the sample. Most polyolefins in the solid state rotate 30–40% of the polarized light. At any temperature at which the sample exhibits an ordered state, some rotation occurs. Temperatures of transitions and changes in refractive index can be determined in this way. Many of these transitions can also be followed by the well‐known method of differential thermal analysis (DTA). A comparison of DLI and DTA curves of polyethylene, polypropylene, mixtures of these polymers, and block copolymers of ethylene and propylene shows the two techniques to be complementary and of use in determining the physical behavior of these polymers. Instrumentation and system variables of the DLI technique are discussed.
Effect of temperature on the ozone cracking of butyl rubbers
Authors: Gent A. N. , Hirakawa H. 
Published: April 2003

AbstractThe rates of growth of single ozone cracks have been measured for vulcanizates of two butyl rubbers over the temperature range of 20–160°C. Over most of this range the rates are quantitatively related to the segmental mobility of the polymer and depend upon temperature in accord with the appropriate from of the WLF relation. The rates are also proportional to the concentration of ozone. It is therefore concluded that diffusion of ozone into the polymer before reaction is the rate‐controlling step. This is contrasted with the behavior of butadiene–styrene copolymers, for which the rates of crack growth are also quantitatively related to the segmental mobility, but the rates are somewhat larger at equivalent mobilities and the dependence upon ozone concentration is smaller. The difference is attributed to different penetration distances before reaction in polymers containing low and high densities of reactive sites.
Dielectric relaxation in the paracrystalline phase in polyacrylonitrile
Authors: Hayakawa Reinosuke , Nishi Toshio , Arisawa Kunio , Wada Yasaku 
Published: April 2003

AbstractThermal expansion and dielectric relaxation of polyacrylonitrile were measured in the temperature range from −75 to 152°C. at frequencies from 30 cps to 3 Mc./sec. The thermal expansion curve and the temperature dependence of logarithmic relaxation time both show an inflection at 85°C. An x‐ray study by Bohn reveals that this inflection comes from the thermal expansion of the paracrystalline phase of this polymer, and consequently the transition at 85°C. and the associated relaxation are ascribed to molecular motion in the paracrystalline phase. The relaxation strength increases with increasing temperature above this point. The transition is caused by freezing of the bending vibration of chains whereas the relaxation results from rotational vibration. The length of segments in this phase is roughly estimated to be ca. 100 A. by comparing the observed relaxation strength with the theory developed on the basis of the above considerations.
Frequency dependence of intrinsic viscosity of macromolecules with finite internal viscosity
Authors: Peterlin A. 
Published: April 2003

AbstractIn order to explain the observed nonvanishing limiting value of dynamic intrinsic viscosity of polymer solutions at ω = ∞ one has considered the necklace model with finite resistance to the rate of coil deformation introduced long ago by Cerf for the study of gradient dependence of intrinsic viscosity and streaming birefringence. The calculation need not take into account change of hydrodynamic interaction as a consequence of coil deformation because the experimental data are always either obtained at very low gradient or extrapolated to zero gradient so that in the experiment the macromolecule has the same conformation as in the solution at rest. The model indeed yields a finite [η]′ω = ∞ in good agreement with experiments on polystyrene in Aroclor. According to the theory [η]′ω = ∞/[η]0 decreases with increasing molecular weight as M−1 and M−1/2 for the free‐draining and impermeable coil, respectively. The absolute limiting value [η]∞′, therefore turns out to be nearly independent of M, at least for small values of internal viscosity. From the observed value [η]∞′/[η0] one can obtain the coefficient of internal viscosity of the macromolecule. The value for polystyrene in Aroclor calculated from dynamic experiments on rather concentrated solutions is close to that derived by Cerf from streaming birefringence observations of polystyrene in a series of solvents of widely differing viscosity.
Dynamic mechanical properties of a gel of cellulose nitrate in diethyl phthalate: Reduced variable analysis in terms of amorphous and crystalline phases
Authors: Ninomiya Kazuhiko , Ferry John D. 
Published: April 2003

AbstractA phenomenological theory is presented to extend the method of reduced variables for the effects of both temperature and changing degree of crystallinity on the linear viscoelastic properties of solutions of crystalline polymers. The vertical and the horizontal shift factors, which are both obtainable in the course of analysis of the experimental data, are correlated with the concentration of the solution and the volume fraction of the crystalline phase, and the fractional free volume of the system, respectively. Dynamic mechanical properties of a gel of cellulose nitrate (nitrogen content, 12.6%) in diethyl phthalate with a nominal concentration of 18% by weight were obtained in the transition region from glasslike to rubberlike consistency and also in the rubbery plateau region by employing the Fitzgerald apparatus and a freely oscillating torsion pendulum over the temperature range from −49 to 65°C. Application of the new reduction method to the experimental data was found to be quite successful, and it was shown that in general the degree of crystallinity in the system (and hence also the concentration of polymer in the amorphous phase) can depend on both temperature and thermal history. The dynamic mechanical data of a gel of different nominal concentration (23% by weight) previously obtained by Plazek were reanalyzed in terms of the method herein given.
Ultracentrifugal equilibrium measurement of high polymer solutions at elevated temperatures
Authors: Kotera Akira , Iso Naomichi , Senuma Akitaka , Hamada Takeshi 
Published: April 2003

AbstractTo investigate the solution properties of polyethylene, which has the simplest structure of the vinyl polymers, experiments were made with a magnetically suspended equilibrium ultracentrifuge. Preliminary studies were carried out with a polystyrene–chloroform system at 25°C. and a polystyrene–methylcyclohexane system at 68°C. (which is close to the theta temperature) in order to check the difficulties involved in the flotation equilibrium in the former case and the high temperature measurement in the latter. However, no trouble was encountered in either system, and the results were discussed and compared with earlier results for polystyrene solutions. It was found that chloroform is a good solvent for polystyrene, and the measured weight‐average molecular weight is somewhat smaller than the value obtained in a theta solvent. After overcoming some technical difficulties involved in studies at higher temperatures, we carried out experiments on polyethylene in α‐chloronaphthalene at 130°C. The results are considered reasonable by comparison with results obtained by other methods. The sample employed, Marlex 50 of melt index 0.7, has a wide molecular weight distribution: i.e., Mz/Mw = 5.2 and Mz+1/Mz = 2.4.
Diffusion coefficients in a halocarbon–polybutene system
Authors: Secor R. M. 
Published: April 2003

AbstractThe diffusion coefficient of 1,1,2‐trichlorotrifluoroethane (TTE) in a liquid polybutene was determined at 25°C. as a function of concentration over the range 1.0–19.5 g. TTE/100 cc. The diffusion coefficient increase with increasing TTE concentration, rising continuously from 3 × 10−8 cm.2/sec. at the lowest concentration to 15 × 10−8 cm.2/sec. at the highest. The magnitudes of the diffusion coefficients indicate that the diffusion mechanism for small molecules in polymeric media must afford vastly greater opportunities for diffusion than the Stokes‐Einstein relation allows. Similarly, self‐diffusion coefficients for the liquid polymer are much lower than the observed mutual diffusion coefficients. An explanation for this behavior is presented.
Structure and solution properties of radical‐initiated poly(vinyl chloride). II. Correlation of solution properties
Authors: Bohdanecký M. , Šolc K. , Kratochvíl P. , Kolínský M. , Ryska M. , Lím D. 
Published: April 2003

AbstractThe results of detailed measurements of osmotic pressure, light scattering, and viscosity of poly(vinyl chloride) solutions are used to establish the molecular weight dependence of [η] and A2, to estimate the unperturbed dimensions of the poly(vinyl chloride) molecule, and to analyze critically the [η]–M correlations published hitherto.