bluuebunny/crossref_metadata_2025_split huggingface dataset:
Initiation and termination mechanism in the cooligomerization of the styrene–methyl methacrylate–carbon tetrachloride system
Authors: Tsuchida Eishun , Yao Takamu , Kitamura Kiwamu , Shinohara Isao 
Published: April 2003

AbstractThe analysis of the endgroups of the oligomers produced in the styrene (A)–CCl4(S) system (system I), the methyl methacrylate(B)–CCl4 system (system II), and the styrene–methyl methacrylate–CCl4 system (system III) was carried out in order to clarify the mechanism of the initiation, transfer, and termination. In system I, the number of Cl atoms per oligomer molecule NCl increases with the molar ratio of [S]/[A] when the molar ratio of [S]/[A] is below unity and is about four when the molar ratio of [S]/[A] is above unity, and the number of initiator fragments per oligomer molecule NI decreases with the increase in the molar ratio of [S]/[A]. In system II, NCl is about 0.45 over a considerably wide range of the molar ratio of [S]/[B]. In system III, NCl increases and NI decreases with the increase in the molar ratios of [S]/([A] + [B]) and [A]/[B]. From the data of NCl and NI, the fraction ICC14 of the initiation by the tri‐chloromethyl radical in the overall initiation reactions and the fraction TCC14 of the chain transfer reaction of the growing radical of styrene in all the reactions which produce the cooligomer in the system III were calculated. ICCl3 and TCC14 both increase with the molar ratios [S]/([A] + [B]) and [A]/[B].
Structural studies of polyformals. II. Crystal structure of poly‐1,3‐dioxolane: Modification II1
Authors: Sasaki Shintaro , Takahashi Yasuhiro , Tadokoro Hiroyuki 
Published: April 2003

AbstractThe structure of poly‐1,3‐dioxolane, [OCH2O(CH2)2]n was studied by x‐ray diffraction and infrared spectroscopy. Three crystal modifications were found. The crystal structure of modification II was determined: four molecular chains of glide type pass through the orthorhombic unit cell; Pbca‐D2h15, a = 9.07 Å, b = 7.79 Å, and c (fiber axis) = 9.85Å. The molecular conformation is
magnified image
The molecular chain consists of regular head‐to‐tail sequences. This fact shows that the ring opening of 1,3‐dioxolane occurs exclusively at the same type of CO bond in the cationic polymerization, just as in the case of 1,3‐dioxepane.
Calibration of an optical self‐beating spectrometer by polystyrene latex spheres and confirmation of the stokes‐einstein formula
Authors: Lee S. P. , Tscharnuter W. , Chu B. 
Published: April 2003

AbstractThe Rayleigh linewidth Γ of light scattered by dilute aqueous solutions of polystyrene latex spheres has been measured by using time‐dependent photocurrent signal correlation with a precision typically of 0.5–1% over a range of scattering angles θ. With independent measurements of the diffusion coefficient D from D = lim K → 0 (Γ/K2), the diameter of the sphere d by means of electron microscopy, and the hydrodynamic shear viscosity η, we have confirmed the Stokes‐Einstein relation D = kT/3πηd to within 1% if we take into account the effect of polydispersity on our Rayleigh linewidth data. We also find that dEM = 907 ± 56 Å for sample LS‐1132‐B as reported by the Dow Chemical Company differs from our dSB = 847 (±1.6%) Å ≈ dEM = 851 (±2%) by about 7%, which is outside the limits of error of our experiments. The subscripts EM and SB denote electron microscope and self‐beating, respectively, while K ≡ (4π/λ)sin(θ/2) is the magnitude of the momentum transfer vector.
Polyamine polymers from pyrrole, formalin, and amines by use of the mannich reaction
Authors: Tsuchida Eishun , Tomono Tsugikazu 
Published: April 2003

AbstractIt was found that pyrrole, one of the active hydrogen compounds, easily condensed with formalin and amine in the presence of acid catalyst to yield a new type of polyamine polymer containing pyrrole nuclei in the main chain of the polymer. This polymerization method was also confirmed to be applicable to the other active hydrogen compounds, such as N‐methylaniline, acetone, malononitrile, and hydroquinone. The structures of the polymers obtained were determined by infrared NMR and elementary analyses.We named this reaction a Mannich polymerization and the polymers obtained the Mannich base polymer.
Heterotactic poly(vinyl alcohol)
Authors: Nozakura Shun‐Ichi , Ishihara Shigeichi , Inaba Yoshiaki , Matsumura Keiji , Murahashi Shunsuke 
Published: April 2003

AbstractBulky substituents in vinyl trialkylsilyl ethers and vinyl trialkylcarbinyl ethers led to heterotactic polymers (H = 66%). The polymers were converted into poly(vinyl alcohol) (PVA) and further to poly(vinyl acetate), and tacticity was determined as poly(vinyl acetate). Vinyl triisopropylsilyl ether in nonpolar solvents yielded a heterotactic polymer with a higher percentage of isotactic triads than syndiotactic triads (Hetero‐I). Vinyl trialkylcarbinyl ethers in polar solvents gave a heterotactic polymer with more syndiotactic triads than isotactic (Hetero‐II). Heterotactic PVA was soluble in water and showed characteristics infrared absorptions. Interestingly, Hetero‐I PVA showed no iodine color reaction, but Hetero‐II showed a much more intense color reaction than a commercial PVA. The mechanism of heterotactic propagation was discussed in terms of the Markóv chain model.
Polyaspartimides: Condensation of aromatic diamines and bismaleimide compounds
Authors: Crivello James V. 
Published: April 2003

AbstractA detailed investigation of the condensation of aromatic amines and maleimide compounds was conducted by the use of model compounds. Weak Brönsted acids were found to have a marked catalytic effect on the reaction. By using glacial acetic acid as the reaction medium, a number of model aspartimide compounds were prepared. Aromatic diamines and bismaleimide compounds were condensed to high polymers in cresol containing a small amount of a protonic acid catalyst. Polymers having a variety of novel backbone structures were prepared and their physical properties studied.
Kinetics of polymer decomposition
Authors: Danforth Joseph D. , Takeuchi Tsugio 
Published: April 2003

AbstractKinetic equations have been developed for polymers that decompose by the zipper mechanism. The usual assumption of steady state kinetics has not been made. Plots of the fraction decomposed α, as a function of time demonstrate a variety of patterns depending upon the relative values of the fraction k1, of chains becoming activated per second and the fraction k2 of an activated chain that decomposes per second.
Crystallization‐induced reactions of copolymers. II. Cis‐trans isomerization of 1,4‐poly‐1,3‐butadiene
Authors: Lenz R. W. , Ohata K. , Funt J. 
Published: April 2003

AbstractThe cis‐trans photoisomerization reaction of 1,4‐polybutadiene was carried out below the melting points on films of polymers containing high trans‐1,4 contents. Under the proper conditions of temperature and polymer composition, the reaction was observed to undergo an anti‐equilibrium behavior, which was attributed to an irreversible crystallization of repeating units after isomerization from cis to trans structure. As a result, the trans composition passed through a minimum with reaction time while crystallinity increased throughout the reaction, and unexpectedly the β crystalline form was observed well below the α–β transition temperature. The composition–time behavior observed was rationalized on the basis of incorporation of trans units into crystalline regions on the lamellar fold surfaces and discussed within the framework of the proposed requirements for crystallization‐induced reactions of copolymers.
Condensation polymers from 1,2,5‐thiadiazole‐3,4‐dicarboxylic acid
Authors: Macdonald Robert N. , Sharkey W. H. 
Published: April 2003

AbstractA series of polyamides was prepared by interfacial polymerization of diamines with 1,2,5‐thiadiazole‐3,4‐dicarbonyl chloride. Polyamides from secondary cycloaliphatic diamines and aromatic diamines have high softening points, high glass transition temperatures, and good thermal stability. Secondary amines, in particular cycloaliphatic secondary amines, form very high molecular weight polyamides. The polyamide from trans‐2,5‐dimethylpiperazine and 1,2,5‐thiadiazole‐3,4‐dicarbonyl chloride is soluble in chloroform and 1,1,2‐trichloroethane and has been cast into films and spun into fibers from those solvents. Fibers of this polymer are strong and have very high work recovery from small strains. In addition, these fibers show good retention of strength and work recovery over a range of temperatures and humidities.
Evaluation of the crystallinity of copolyamide fibers
Authors: Włochowicz Andrzej , Jeziorny Andrzej 
Published: April 2003

AbstractDensity and x‐ray diffraction measurements of the degree of crystallinity have been made on copolymers of polyamide 6 PA‐6 with hexamethylenediamine terephthalate and ethylenediamine terephthalate ranging composition from 4 to 35 mole‐% of the terephthalates. The degree of crystallinity can be determined from the ratio of the sum of mass contribution products of the crystalline regions for each of the comonomers to the total copolymer mass. Such a procedure can be used when the molar fractions of comonomers in copolymer are known. The results obtained are in agreement with the theoretical values.
Poly(arylene sulfides) with pendant cyano groups as high‐temperature laminating resins
Authors: Haddad Ibrahim , Hurley Shaun , Marvel C. S. 
Published: April 2003

AbstractPoly(phenylene sulfides) were synthesized from m‐benzenedithiol and aromatic dibromides in a basic medium of potassium carbonate in dimethylformamide or dimethylacetamide. The products obtained were slightly off‐white with relatively low melting ranges and had inherent viscosities in the 0.2–0.4 dl/g range in hexamethylphosphoric triamide. Similar poly(phenylene sulfides) containing pendant cyano groups along the polymer chains were obtained by the use of 5 mole‐% of either 2,4‐dichlorobenzonitrile or 3,5‐dichlorobenzonitrile. The products were similar to the pure polyphenylene sulfides, except that they showed lower melting ranges and gave insoluble products when heated alone or in the presence of zinc chloride.
Aging and degradation of polyolefins. II. γ‐initiated oxidations of atactic polypropylene
Authors: Decker Christian , Mayo Frank R. 
Published: April 2003

AbstractOxidations of bulk atactic polypropylene (PP) have been carried out at 22 and 45°C, and the dependence of rate of formation of each product on rate of initiation has been determined. The principal product is PP hydroperoxide, formed in a half‐order reaction. One termination product is polymeric dialkyl peroxide, formed in a first‐order reaction. Other termination and propagation products, alcohols and carbonyl compounds, are formed in reactions that are mostly first‐order in initiation. At 22°C, G is 9–63. G is about three times as great at 45°C as at 22°C. Experiments with 2,6‐di‐tert‐butyl‐p‐cresol shows that it can inhibit all non‐cage propagation and all formation of PP hydroperoxide, but that it does not affect cage reactions of initiating radicals and their successors. Only about 16% of the initiating PPO2· radicals escape the cage at 45°C. Oxidations of PP, n‐hexane, and their mixture with both peroxide and γ‐ray initiation show that nearly all the initiating radicals escape the cage in solution but that the concentration of PPO2· radicals is much less than in bulk because of a much faster chain termination. Both the propagation and termination constants for PP oxidation are much faster in solution, but the changes compensate so that kp/(2kt)½ is about the same in solution as in bulk.
Etude de copolymères ABS (acrylonitrile–butadiène–styrène): Solvatation préférentielle du polybutadiène par les promoteurs
Authors: Locatelli J. L. , Riess G. 
Published: April 2003

AbstractABS resins formed by copolymerization of styrene and acrylonitrile (AN) in presence of polybutadiene, consist of a mixture of SAN graft copolymer on polybutadiene (PBut) and of ungrafted SAN copolymer (styrene‐co‐acrylonitrile). The kinetic study was completed by showing a preferential solvation of polybutadiene by the initiator. This solvation effect was studied as a function of the concentration ratio SAN/PBut and in relation with the type of initiator. The adsorption of initiator appeared to be maximum when its solubility parameter (σ) is close to that of polybutadiene. As a function of the polybutadiene characteristics, this selective adsorption can be given by

where I1 is the quantity of initiator in the polybutadiene medium, I is the total amount of peroxide, [PBut] is the concentration of polybutadiene, and M̄n its molecular weight. It has been shown furthermore that the preferential solvation of polybutadiene by the benzoyl peroxide can be increased by addition of SAN or acrylonitrile. The consequences of this solvation effect on the characteristics of the grafting reaction, more precisely on the molecular weight of grafted and ungrafted SAN and on the rate of polymerization, were examined.
Some comments on domain structures in block copolymers
Authors: Krigbaum W. R. , Yazgan S. , Tolbert W. R. 
Published: April 2003

AbstractAlthough samples of amorphous polymers cast from solution are usually assumed to be isotropic, they may, in fact, have some anisotropy due to the Bénard effect, in which the convection currents produced by evaporation are organized into a regular arrangement of cells. A pattern of hexagonal convection cell is easily visible during casting of SBS triblock copolymers. The anisotropy is demonstrated by comparing the small‐angle x‐ray diffraction diagrams taken through the face and edge of the films. The domain structures in two SBS copolymers are characterized by diffraction measurements. The smallangle diagram of a triblock polymer containing 50% styrene indicated a lamellar structure, while that from a 28% styrene copolymer is interpreted as arising from a hexagonal array of polystyrene cylinders dispersed in a continuous polybutadiene phase. Published diffraction data for block copolymers and other amphiphiles are surveyed in an attempt to place some limitations on the composition ranges over which the various types of domain structure exist. The factors which determine the dimensions of the two domains in lamellar phases formed from diblock copolymers are examined theoretically, and the predicted dimensions are compared with experimental results.
Structure of some ethylene–phosphonic acid copolymers
Authors: Johnson R. G. L. , Delf B. W. , MacKnight W. J. 
Published: April 2003

AbstractAn x‐ray study has been made of the structure of a series of ethylene–phosphonic acid copolymers and the parent low‐density polyethylene from which they were derived. The phosphonic acid contents (groups per 100 carbon atoms) of the copolymers were: A, 0.8; B, 1.8; C, 2.8; and D, 8.0. Small‐angle x‐ray scattering (SAXS) results show that the phosphonic acid substituents do not incorporate into the crystal lattice to any appreciable extent, that the substituents have the effect of decreasing the average thickness of the crystal lamellae and increasing the breadth of the size distribution of thicknesses, and that a two‐phase model does not adequately account for the observed SAXS invariant. Wide‐angle x‐ray scattering (WAXS) results show that specimens, A, B, and C are partially crystalline with the polyethylene crystal structure and that D is amorphous. The observed broadenings of the 110 and 200 crystal reflections in the copolymers indicate that the substituents decrease the lateral dimensions of the crystalline lamellae and/or increase the deformation of the lattice due to external strain. Specimen D, completely amorphous according to the WAXS criterion, exhibits the largest value of the SAXS invariant of all the copolymers studied and must thus possess a multiphase structure consisting of small ordered regions and a disordered phase. The results of the study show the structure of the copolymers to be consistent with the fringe‐micelle model but do not rule out the folded‐chain model, although a regular fold surface is unlikely.
Effect of water on the mechanical properties of collagen films
Authors: Tanioka Akhiko , Jojima Eiichiro , Miyasaka Keizo , Ishikawa Kinzo 
Published: April 2003

AbstractThe effect on water on mechanical properties of collagen films has been studied. The S‐shaped sorption isotherm is separated into an adsorption curve C1 and a solution curve C2. From the C2 curve, a value of 0.8 is calculated for the Flory‐Huggins interaction parameter χ1. The dynamic shear modulus G′, loss modulus G″, and loss tangent tan δ determined as functions of water content indicate two dispersions at low and at high water content. The region of water content from about 0.05 to 0.1 g/g, G′ decreases suddenly, G″ has a peak, and tan δ increases, corresponds to the region where the C2 component of sorption becomes detectable. Another dispersion occurs at water contents above 0.2 g/g. A composite curve can be obtained by shifting stress‐relaxation curves obtained at different humidities along the log time axis. When only the C2 component of sorbed water is taken into account, the shift factor ac is explained by a relation of Fujita and Kishimotos' based on free‐volume theory. Shift factor for the relaxation curves of wool fibers, except for an initial part at times of less than 1 sec, are described by the same equation. The parameter β in the equation has the same value of 0.16 for both collagen and wool.
Photodehydrochlorination of carbon monoxide–vinyl chloride copolymer
Authors: Kawai Wasaburo , Ichihashi Taichi 
Published: April 2003

AbstractIn order to examine effect of the carbonyl group in carbon monoxide–vinyl chloride copolymer, poly(CO–VC), photoirradiation with a high‐pressure mercury lamp on the copolymer was carried out. Poly(CO–VC) had a rate of dehydrochlorination three times that of PVC, and the reaction involved a decrease in chlorine content. Also there was a marked change in the ultraviolet spectra of the photoirradiated films. However, no pronounced change of molecular weight was observed, but a change in Rf in TLC was observed clearly. These facts confirmed that photoirradiation of poly(CO–VC) produced a structural change by dehydrochlorination without serious decrease of molecular weight. In addition, photodehydrochlorination of the copolymer or PVC film was followed kinetically, and after ozonolysis of the dehydrochlorinated polymers, the number‐average molecular weights were measured. From the results of degree of dehydrochlorination and molecular weight, the number average of conjugated double bonds or carbonyl groups was estimated. A mechanism for dehydrochlorination process by photo‐irradiation is suggested.
Copolymers of conjugated dienes with maleic acid monoesters. IV. Reactivity ratios in copolymerization of isoprene with maleic acid monoesters
Authors: Nanu Ioan , Andrei Constantin 
Published: April 2003

AbstractResearch was carried out on copolymerization of isoprene with maleic acid monoesters in the presence of free radicals (AIBN). The aim of the study was to observe the effect of the different monoesters obtained with normal alcohols of the aliphatic series: monoethyl maleate, monopropyl maleate, monobutyl maleate, monoheptyl maleate, monolauryl maleate, and monocetyl maleate. On the basis of reactivity ratios determined by the Fineman‐Ross method and compared with the Mayo‐Lewis method, all the systems studied are typical cases of heterocopolymerization. The parameter r1 is constant for this homologous series with the exception of the low terms. The experimental results agree with the ultimate model equation (with deviation at very high values of [M10]/[M20]), but not with the copolymer composition equation which considers the effect of the penultimate unity (penultimate model). Characterization of the sequential distribution is also presented (considering the effect of the terminal group only), and deviations of the experimental results are also discussed.
Gel‐permeation chromatography. IX. Instrumental design and computer interfacing of a GPC molecular weight detector system
Authors: Ouano Augustus C. , Horne Donald L. , Gregges Annie R. 
Published: April 2003

AbstractThe detailed design and computer interfacing of a GPC molecular weight detector based on a real time viscometer are described. The working drawings presented will permit one to fabricate and duplicate the viscometer and the complete GPC molecular weight detector system. The uses and advantages of a laboratory automation system in analyzing GPC results are also described.
Degradation of polymer mixtures. IV. Blends of poly(vinyl acetate) with poly(vinyl chloride) and other chlorine‐containing polymers
Authors: Jamieson A. , McNeill I. C. 
Published: April 2003

AbstractThe degradation of the binary polymer blends, poly(vinyl acetate)/poly(vinyl chloride), poly(vinyl acetate)/poly(vinylidene chloride) and poly(vinyl acetate)/polychloroprene has been studied by using thermal volatilization analysis, thermogravimetry, evolved gas analysis for hydrogen chloride and acetic acid, and spectroscopic methods. For the first two systems named, strong interaction occurs in the degrading blend, but the polychloroprene blends showed no indication of interaction. In the PVA/PVC and PVA/PVDC blends, hydrogen chloride from the chlorinated polymer causes substantial acceleration in the deacetylation of PVA. Acetic acid from PVA destabilizes PVC but has little effect in the case of PVDC because of the widely differing degradation temperatures of PVA and PVDC. The presence of hydrogen chloride during the degradation of PVA results in the formation of longer conjugated sequences, and the regression in sequence length at high extents of deacetylation found for PVA degraded alone is not observed.
Optically active diamide as a model for studying interactions between mineral salts and nylon type polyamides in methanol solutions
Authors: Hamoud Muhie Rasoul , Vert Michel , Selegny Eric 
Published: April 2003

AbstractN,N′‐Dicaproyl (–)1,2‐diaminopropane (I) was used as a convenient model for the study of the optical activity of a nylon type polyamide: polysebacamide (–)1,2‐diaminopropane (II). ORD of I was measured in different solvents. A peculiar behavior is observed in methanol in the presence of mineral salts. The influence of 0.1M potassium salts (Cl−, Br−, SCN−, NO3−, SO4−2) and 0.1M alkaline chlorides and alkaline earth chloride hexahydrates on the optical activity of I in methanol are described. Alkaline salts and MgCl2 give approximately the same effect: there is a decrease of the rotations without change of sign. SrCl2 and CaCl2 shift ORD curves towards the negative rotations, the last one giving complete inversion. This inversion is directly related to the CaCl2 concentration and is attributed to adduct formation between amide groups and salt. Assuming that the different species are at equilibrium, an apparent equilibrium constant is obtained from the optical rotations for a complex of one mole of CaCl2 with one mole of I. Results are used to discuss the complex ORD of poly(−) 1,2‐diaminopropane sebacamide in methanol saturated with CaCl2.
Free‐radical grafting of monomers to polydienes. II. Kinetics and mechanism of styrene grafting to polybutadiene
Authors: Brydon A. , Burnett G. M. , Cameron G. G. 
Published: April 2003

AbstractA kinetic analysis of the grafting reaction has shown that, provided rubber radicals are not involved in termination reactions, the observed normal kinetics of styrene polymerization are to be expected. An expression relating the graft fraction with the rubber and monomer concentrations has been derived and its validity verified from the results reported in Part I. The observation that the molecular weight of the ungrafted PBD falls during the reaction has been explained on a theoretical basis.