bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coordinated radical polymerization and redox polymerization of acrylamide by ceric ammonium nitrate
Authors: Takahashi Toru , Hori Yasuhiko , Sato Ichiro 
Published: April 2003

AbstractThe ceric salt‐initiated polymerization on acrylamide and graft copolymerization of acrylamide onto cellulose were studied. The mechanism of the ceric salt‐initiated polymerization of acrylamide in the homopolymerization system can be explained by a radical mechanism based upon Ce4+‐coordinated acrylamide, and the mechanism of the ceric salt‐initiated graft copolymerization of acrylamide onto cellulose can be explained in two ways: a free‐radical mechanism with the ceric—cerous redox system, and a radical mechanism based upon Ce4+‐coordinated acrylamide. The velocities of initiation, propagation, and termination in the redox mechanism are quite different from those in the coordinated radical mechanism. From the infrared absorption and nuclear magnetic resonance spectra measurements it is concluded that the structure of the ceric‐coordinated acrylamide is the π‐complex.
Thermal stability of silicon‐containing amide benzimidazole, hydrazide, and oxadiazole polymers
Authors: Delman Alvin D. , Kovacs Hanna Nagy , Simms Bernard B. 
Published: April 2003

AbstractStudies were undertaken to ascertain the thermal stability of several types of silicon‐containing polymers. Results of thermal analysis investigations indicate that all of the polymers are unusually heat‐resistant when heated in air at elevated temperatures. Solution‐cast films of the polymers on aluminum showed excellent flexibility and adhesion characteristics after being heated in air for 100 hr. at 300°C. and then for 3.5 hr. at 400°C. Visual examination of the films after the heating sequence indicated that the silicon‐containing polyamides and polybenzimidazole had darkened slightly, while the polyoxadiazole appeared to be unaffected in this respect. Infrared spectroscopy studies showed that all of the polymers underwent only very minor structural changes during the prolonged heating process.
Polymerization of α‐piperidone with M–AlEt3, MAlEt4, or KAlEt3(piperidone) as catalysts and N‐acetyl‐α‐piperidone as initiator
Authors: Tani Hisaya , Konomi Tuyoshi 
Published: April 2003

AbstractLow‐temperature polymerization of α‐piperidone was carried out by using MAlEt4, KAlEt3(piperidone), and M–AlEt3 (where M is Li, Na, or K) as catalysts and N‐acetyl‐α‐piperidone as initiator. The behavior in polymerization of these catalysts was superior to alkali metal or aluminum triethyl, and a polymer having an intrinsic viscosity of 0.8 dl./g. was obtained. Polymerization results and infrared analyses of the metal salts of lactams suggest that a complex, the structure of which was analogous to the one formed from M–AlEt3, is formed in the case of the alkali metal piperidonate–ethyl aluminum dipiperidonate catalyst system and that it is changed to another complex having a different composition and lower catalytic activity by heat treatment. The infrared absorption band of the metal salts of lactams and of KAlEt3(piperidone) at 1570–1590 cm.−1, which is attributable to the CN group in enolate form, may be considered to be related to the catalytic activities of alkali metals and the polymerizabilities of lactams. Such special catalysts as MAlEt4, alkali metal–AlEt3, or KAlEt3(piperidone) are supposed to suppress the consumption, by alkali metal, of N‐acyl‐α‐piperidone group of growing polymer end. A prolonged polymerization required for obtaining a high molecular weight polymer, even when such catalysts are used, is ascribable to a greater difficulty in re‐forming lactam anion from α‐piperidone, the basicity of which is higher than that of the other lactams.
Polymerization of 2,5‐dimethyl‐3,4‐dihydro‐2H‐pyran‐2‐carboxyaldehyde (methacrolein dimer). Part II
Authors: Kitahama Yoshiharu 
Published: April 2003

Abstract2,5‐Dimethyl‐3,4‐dihydro‐2H‐pyran‐2‐carboxyaldehyde (methacrolein dimer) gave a polymer consisting of only recurring bicyclic structure of 1,4‐dimethyl‐6,8‐dioxa‐bicyclo‐[3,2,1] octane with the use of Lewis acid and protonic acid as catalyst at room temperature. On the other hand, the polymer obtained by using BF3·(C2H5)2O under −78°C. was found to have the structures produced by the aldehyde group polymerization as well as the bicyclic ones. The polymer obtained at −40°C. had a low decomposition temperature (164°C.) owing to the presence of polyacetal group, whereas the fully saturated bicyclic polymer had a considerably high one (346°C.). The main factors affecting the polymerization were polymerization temperature and catalyst. Lowering temperature increased the polymerization of the aldehyde group. Anionic catalysts and weak cationic catalyst such as Al(C2H5)3H2O, which were active catalysts for acrolein dimer, did not initiate the polymerization of methacrolein dimer. The fact that the relative viscosity of the polymer increased with polymerization time shows the polymerization of this monomer is a successive reaction.
Reactions of trifluoroacetic acid with poly(vinyl alcohol) and its model compounds. Effect of neighboring hydroxyl groups on the reaction
Authors: Fujii K. , Brownstein S. , Eastham A. M. 
Published: April 2003

AbstractReactions of trifluoroacetic acid with poly(vinyl alcohol) and various model alcohols were investigated by observing the fluorine and the proton magnetic resonance spectra of the reaction mixtures. At equilibrium the degree of conversion to ester under given conditions decreased in the order isopropanol, pentane‐2,4‐diol, heptane‐2,4,6‐triol and poly(vinyl alcohol). Therefore the equilibrium constant for esterfication of a hydroxyl group is depressed by the presence of neighboring hydroxyl groups. It was observed that the steric structures of the models and polymers also affect the equilibrium position of the reaction and this is mainly ascribable to the fact that meso (isotactic) molecules react more slowly with the acid than do racemic (syndiotactic) molecules. In acid‐catalyzed acetylation of the model alcohols with acetic acid no similar dependence on the steric configuration was found. Therefore trifluoroacetylation seems to be specific in this respect.
Salt effect in the base‐catalyzed polymerization of unsaturated amide compounds. III. Nature of the polymerization system
Authors: Asahara Tomohiko , Ikeda Kojuro , Yoda Naoya 
Published: April 2003

AbstractCoordination complexes of lithium chloride with polar solvents and monomers were isolated, and their physical properties were studied. The parallel between stabilities of isolated complexes and coordination function in the polymerization system is discussed. The increase of the Q and e values of p‐vinylbenzamide (VBA) supports the mechanism of vinyl‐type polymerization of VBA in the presence of the salt. The specific solvent effect of dimethyl sulfoxide was determined by measurement of electrical conductivity of a model system.
Relative reactivities of cyclic ethers in cationic copolymerizations: Effects of ring strain and basicity
Authors: Aoki Shuzo , Harita Yoshiyuki , Tanaka Yoshiaki , Mandai Hiroshi , Otsu Takayuki 
Published: April 2003

AbstractThe relative reactivities of α‐monosubstituted cyclic ethers having rings of three to six members toward a cation were estimated from their copolymerizations with 3,3‐bis‐(chloromethyl)oxetane (M1) catalyzed by boron trifluoride etherate in methylene chloride at 0°C. It was found that the reactivity of these cyclic ethers was dominated by both the ring strain and the basicity. The following empirical equation was derived to represent the relative reactivity of cyclic ethers: log (1/r1) = −0.086ΔRS − 0.31ΔB + 0.57, where ΔRS and ΔB are constants, characteristic of ring strain and basicity of the cyclic ethers and determined from the differences in free energy of polymerization of the corresponding cycloalkanes and in basicity between M1 and M2 monomers, respectively. A good linear correlation was observed between the reactivities calculated from this equation and those obtained from the experiments.
Electron‐transfer polymers. XXIX. Copolymerizability of vinylhydroquinone derivatives
Authors: Uno Keikichi , Ohara Mutsuko , Cassidy Harold G. 
Published: April 2003

AbstractTen vinylhydroquinone and one vinyl resorcinol derivatives are compared, particularly with respect to NMR spectra and copolymerizability with styrene. They are vinylhydroquinone dimethyl ether (I), vinyl‐O,O′‐bis(1‐ethoxyethyl)hydroquinone (II), vinylhydroquinone di(2‐pentyl)ether (III), 4‐vinyl resorcinol bismethoxymethyl ether (IV), 2‐vinyl‐5‐methylhydroquinone dimethyl ether (V), 2‐vinyl‐5‐methyl‐O,O′‐bis(1‐ethoxyethyl)hydroquinone (VI), 2‐vinyl‐6‐methylhydroquinone dimethyl ether (VII), 2‐vinyl‐5‐tert‐butylhydroquinone dimethyl ether (VIII), 2‐vinyl‐5‐chlorohydroquinone dimethyl ether (IX), 2‐vinyl‐3,6‐dimethylhydroquinone dimethyl ether (X), and 2‐vinyl‐3,5,6‐trimethylhydroquinone dimethyl ether (XI). All the vinyl protons have almost the same coupling constants. Though subtle distinctions are found among all the spectra, they can in general be put into two groups on the basis of the chemical shifts. Let the hydrogen on carbon‐1 of the vinyl group be A, the hydrogen cis to A be B the hydrogen trans to A be C, then in the first group, (I) through (IX), the chemical shifts (τ) are (A) 3.02 ± 0.08, (C) 4.41 ± 0.05, and (B) 4.87 ± 0.07, and in the second group, (X) and (XI), they are (A) 3.30 ± 0.03, (C) 4.49 ± 0.01, and (B) 4.59 ± 0.03. It is supposed that in (X) and (XI) the vinyl group is out of the plane of the ring, because of the two ortho substituents, and this conformation is reflected in the NMR data. Ultraviolet spectra are consonant with this interpretation, since the λmax of (X) and (XI) correspond closely with those of nonvinyl reference compounds, while those of (II), (V), and (VIII) are shifted to longer wavelengths. When these compounds are copolymerized separately with styrene, the behaviors are classifiable into the following three groups, where r1 and r2 are monomer reactivity ratios with styrene as the first monomer: (i) r1 < 1 and r2 < 1 for compounds (II) and (III) and the reference compound O,O′‐dibenzoylvinylhydroquinone, (ii) r1 < 1 and r2 > 1 for compounds (I), (V), (VII), (VIII), (IX), and (iii) r1 > 1 and r2 = 0 for compounds (X) and (XI). These behaviors are correlated with the effect of electronegativity of groups on the stability of the radical at the growing end of the chain and with the simultaneous effects of steric hindrance.
Optically active imidazole‐containing polymers
Authors: Overberger C. G. , Cho Iwhan 
Published: April 2003

AbstractIn order to investigate the stereospecificity of enzyme‐catalyzed reactions, an optically active copolymer of 4(5)‐vinylimidazole and 2,5(S)‐dimethyl‐1‐hepten‐3‐one was synthesized, and its effects on the solvolytic rates, in ethanol‐water, of the p‐nitrophenyl and 4‐carboxy‐2‐nitrophenyl esters of 3(R)‐ and 3(S)‐methylpentanoic acid and of the commercially available N‐carbobenzoxy‐(R)‐ and (S)‐phenylalanine p‐nitrophenyl esters were investigated. The optically active comonomer was prepared by thermal decomposition of solid (+)‐1‐piperidino‐2,5(S)‐dimethylheptan‐3‐one hydrochloride, which was obtained from the reaction of 2(S)‐methylbutyllithium with 3‐piperidino‐2‐methylpropionitrile. The 3(R)‐methylpentanoic acid was prepared in 92% optical purity from L‐alloisoleucine via diazotization in concentrated hydrobromic acid and subsequent reductive debromination with zinc amalgam in dilute hydrochloric acid. In the optically active copolymer‐catalyzed solvolyses of the optically active esters performed at pH values of 6–8 no significant differences between the solvolytic rates of (R) and (S) isomers of substrates were observed. Poly‐L‐histidine was also employed as a catalyst for the solvolyses of these substrates. At pH 6.0 in ethanol–water the latter catalyst also failed to exhibit specificity towards (R) and (S) substrates.
Photodegradation of polyethylene film
Authors: Heacock James F. , Mallory Frank B. , Gay Frank P. 
Published: April 2003

AbstractA structure occurs in radical‐polymerized polyethylene which leads to formation of a triene on ultraviolet radiation. An inhibition of oxidative processes is observed while the triene or its precursor are being consumed. Subsequent formation of oxygenated products—hydroxyl, carbonyl, and carboxyl—is well behaved and arises from short wavelenght light. A crosslinking reaction is initiated by light of ∼4000 Å wavelength.
Syntheses and properties of photochromic polymers of the azobenzene and thiazine series
Authors: Kamogawa Hiroyoshi , Kato Masao , Sugiyama Hiroko 
Published: April 2003

AbstractPhotochromic polymers of the azobenzene and thiazine series were synthesized via two routes: (1) synthesis of vinyl photochromic monomers and subsequent polymerization and (2) chemical reactions of the substrate polymers with photochromic components. Polyvinylaminoazobenzenes, polyvinylhydroxyazobenzenes, polyacrylamidomethylaminoazobenzenes, and polyacrylamidomethylthionine were thus prepared and their photochromic behavior investigated. In the case of azobenzene polymers, irradiations from a 100‐W projection lamp are enough to induced reversible changes in absorption spectra both in benzene solutions and film states, their absorption maxima being located around 400 mμ in the dark. Better results are obtained for some polymers as compared with the corresponding low molecular weight compounds; in the case of the thionine polymer (absorption maximum, ca. 600 mμ), the presence of ferrous ion remarkably enhances the photosensitivity in aqueous solutions, but incorporation of some polymers containing hydroxyl groups, such as poly(vinyl alcohol), are preferable for film states.
Cationic polymerization of α,β‐disubstituted olefins. VI. Steric structure of poly(methyl propenyl ether) obtained by cationic catalysts
Authors: Ohsumi Y. , Higashimura T. , Okamura S. , Chûjô R. , Kuroda T. 
Published: April 2003

AbstractThe steric structure of poly(methyl propenyl ether) obtained by cationic polymerization was studied by NMR spectra. From the analysis of β‐methyl and α‐methoxyal spectra, it was found that the tacticities of the α‐carbon were different from those of the β‐carbon in all polymers obtained. In the crystalline polymers obtained from the trans isomer by homogeneous catalysts, BF3·O(C2H5)2 or Al(C2H5)Cl2, and from the cis isomer by a heterogeneous catalyst, Al2(SO4)3–H2SO4 complex, the structure of polymers was threo‐di‐isotactic. Though the configurations of all α‐carbons were isotactic, a small amount of syndiotactic structure was observed in the β‐carbon. On the other hand, in the amorphous polymer obtained from cis isomer by the homogeneous catalyst, the configuration of the α‐carbon was isotactic, but that of the β‐carbon was atactic. These facts suggest that the type of opening of a monomeric double bond is complicated, or that carbon–carbon double bond in an incoming monomer rotates in the transition state. From these experimental results, a probability treatment was proposed from the diad tacticity of α,β‐disubstituted polymers. It shows that the tacticity is decided by a polymerization mechanism different from that proposed by Bovey.
Solution polymerization of trioxane catalyzed by stannic chloride
Authors: Miki T. , Higashimura T. , Okamura S. 
Published: April 2003

AbstractThe polymerization of trioxane catalyzed by stannic chloride (SnCl4) in ethylene dichloride was studied and compared with the results obtained with boron trifluoride etherate, BF3·O(C2H5)2, as catalyst. Under the same conditions, the polymerization rate was larger with SnCl4 than with BF3·O(C2H5)2, while at a fixed polymer yield the molecular weight of the polymer obtained by SnCl4 was lower than with the BF3·O(C2H5)2 catalyzed reaction. The overall activation energy of trioxane polymerization with SnCl4 was 11.0 ± 0.8 kcal/mole. The kinetic orders of catalyst and monomer were determined to be close to 2 and 4, respectively. A certain amount of tetraoxane was also produced in an early stage of the polymerization with SnCl4 similar to BF3·O(C2H5)2‐catalyzed reaction. However, the maximum amount of tetraoxane produced at 30°C was larger with SnCl4 than with BF3·O(C2H5)2. In addition, a ten‐membered ring compound (pentoxane) was isolated in the solution polymerization of trioxane catalyzed by both SnCl4 and BF3·O(C2H5)2. The confirmation of pentoxane formation is strong evidence for the back‐biting reaction mechanism.
Preparation of poly(diphenyl phosphazene)
Authors: MacCallum J. R. , Tanner J. 
Published: April 2003

AbstractThe preparation of substituted polyphosphazenes has been briefly surveyed. A method of synthesis of a fully substituted poly(diphenyl phosphazene) has been investigated. The product has been characterized and thermogravimetric analysis carried out. The volative products of pyrolysis have been identified and the hydrolytic stability of the polymer tested.
Preparation and properties of poly(phosphonatoalanes)
Authors: Schmidt Donald L. , Flagg Edward E. 
Published: April 2003

AbstractTwo general types of poly(phosphonatoalanes), [Al(X)OP(O)(R)O]n (X = Cl or F, R = alkyl or aryl) and [Al(OP(O)R2)OP(O)(R′)O]n, were prepared and studied. Poly[chloro(phosphonato)alanes] are influsible and have low molecular weights (n = 4–11). Polyfluoro(phosphonato)alanes are fusible and also have low molecular weights, but under certain conditions grow to higher polymers (n = 30–45). Poly[phosphinato(phosphonato)alanes] are fusible and are prepared with high molecular weights (n = 83–340).
Modification of poly(vinyl chloride). X. Crosslinking of poly(vinyl chloride) with a soft segment of an elastomer containing thiol groups
Authors: Nakamura Yoshiro , Mori Kunio 
Published: April 2003

AbstractTo obtain poly(vinyl chloride) (PVC) of excellent toughness, a new method of crosslinking PVC is proposed in which PVC is crosslinked with the soft segment in an elastomer such as liquid Thiokol. The reaction can be accomplished by immersing PVC–Thiokol blends in liquid ammonia at 20–30°C. A similar reaction occurs in aqueous ammonia when hexamethylphosphoramide is used as an activator. Characteristics of the crosslinked PVC thus obtained and of the controls of a similar uncrosslinked composition (PVC–Thiokol LP‐8, 100:5 by weight) were as follows: tensile strength, 7.3 and 4.8 kg/mm2; elongation at break, 30 and 2.5%; Young's modulus, 3.5 × 104 and 2.9 × 104 kg/cm2; tensile impact, 88 and 15 kg‐cm/cm3, respectively. The crosslinked PVC as plasticized with dioctyl phthalate (DOP) and the control blend (PVC–Thiokol LP‐8–DOP, 100:10:10 by weight), respectively, showed tensile strengths of 5.9 and 4.8 kg/mm2, elongations at break of 44 and 24%, Young's moduli of 2.5 × 104 and 1.6 × 104 kg/cm2, and tensile impact strengths of 62 and 120 kg‐cm/cm3. As the crosslinkage through the soft segments increases up to about 5%, the elongation at break, Young's modulus, and tensile impact, in addition to the tensile strength, are improved. This is different from the results so far observed with the crosslinked amorphous polymers and is characteristic of the products of crosslinking through the soft segment. The experimental results are discussed in this paper.
Polyhydrazides. III. N‐methylated polyhydrazides by ring‐opening of poly‐p‐phenylene‐1,3,4‐oxadiazole
Authors: Iwakura Yoshio , Uno Keikichi , Hara Shigeyoshi , Kurosawa Shigeru 
Published: April 2003

AbstractA new ring‐opening reaction of 1,3,4‐oxadiazole by methylating reagents was developed in fuming sulfuric acid or polyphosphoric acid and then, by applying this reaction to poly‐p‐phenylene‐1,3,4‐oxadiazole, a high molecular weight poly‐N‐methylterephthalylhydrazide was obtained. Various methylating reagents were investigated as ring‐opening reagents. The degrees of ring‐opening in polymers were estimated and related to the properties of the polymers.
Transition temperatures and crystallinity in polyoctadecene‐1
Authors: Aubrey D. W. , Barnatt A. 
Published: April 2003

AbstractPolyoctadecene‐1, as isolated from a Ziegler‐type polymerization, was examined by density and refractive index measurements and by differential thermal analysis. Two main transitions were observed, their sharpness suggesting that they are both first‐order. Extraction with n‐hexane at 25°C. separated the polymer into two almost equal fractions, each showing essentially one of these transitions. Transition temperatures were compared with those of certain other polymers having long n‐alkyl side chains. From this comparison, and from the findings of other workers, it was concluded that the polymer of lower transition temperature is atactic polyoctadecene, in which the side chains only participate in crystallization, whereas the polymer of higher transition temperature is tactic polyoctadecene, in which crystallization involves both the main chain and side chains.
Determination of orientation of the crystalline and amorphous phases in polyethylene by X‐ray diffraction
Authors: Wilchinsky Zigmond W. 
Published: April 2003

AbstractFor polyethylene fibers, orientation parameters of the form 〈cos2 ϕ〉 were calculated from traces obtained with an x‐ray diffractometer equipped with an orientation integrator. The angle ϕ is that which a crystal or molecular axis makes with the fiber axis. Traces over a continuous range of diffraction angle were obtained for (2/π)Iav, and also the weighted averages (2/π)Iav 〈cos2ϕ〉 and (2/π)Iav 〈sin2ϕ〉, where Iav is the intensity averaged over all orientations. The orientation for the crystal a, b, and c axes were determined from area measurements of the {110} and {200} lines, and the orientation parameter for the molecular axis in the amorphous phase was determined from area measurements of the amorphous halos. An undrawn fiber showed a slight a and c axis orientation along the fiber axis, and a slight transverse orientation of the b axis and the molecular axis. For a highly drawn fiber the orientation parameter for the c axis was 0.98 and for the molecular axis 0.65. The degree of crystallinity, measured from the (2/π)Iav versus 2θ traces, were 66.1% and 73.3% for the undrawn and drawn fiber, respectively.
Polymer fractionation. I. The preparative problem
Authors: Koningsveld R. , Staverman A. J. 
Published: April 2003

AbstractThe molecular weight distributions of the fractions in the two liquid phases which, in preparative fractionation, form upon a change in temperature, have been calculated for various initial concentrations and model distributions differing widely in shape and width. It was found that the normally recommended conditions do not always lead to the result desired, i.e., to a fraction with a narrow distribution. Under these conditions (dilute solution; large phase‐volume ratio; small fraction, i.e., little polymer in the concentrated phase) it may even happen that the fraction has a relatively wider distribution than the parent polymer. Treatment of a single‐peaked distribution will then be liable to yield a two‐peak fraction distribution. These unwanted phenomena do not occur in Staverman and Overbeek's variant of the extraction fractionation method. Here, the bulk of the polymer goes into the concentrated phase, and the macromolecules left in the dilute phase constitute the fraction to be isolated. In this way, relatively narrow distributions can be obtained in one step, even at high concentrations. Moreover, the method is very well suited for use in large‐scale fractionation. Fraction distribution wider than the initial distribution were found experimentally in the systems polyethylene–diphenyl ether and polystyrene–cyclohexane.