bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of coordinated monomers. VI. Molecular complex formation of methyl methacrylate coordinated to stannic chloride with styrene or toluene
Authors: Hirai Hidefumi , Komiyama Makoto 
Published: April 2003

AbstractThe equilibrium constants for the complex formation between stannic chloride and methyl methacrylate were determined in n‐hexane–toluene solution at 0, −20, and −30°C by using the absorption band at 350 nm. Continuous variation plots at −20°C in n‐hexane based on the 1H‐chemical shifts definitely show a 1:1 interaction between the coordinated methyl methacrylate and styrene or toluene. The magnitudes of the shifts for the four groups of protons in methyl methacrylate are found to be in a specific ratio in common with the 1:2 complex–styrene or ‐toluene system. The equilibrium constants for the ternary molecular complex formation between the 1:2 complex and styrene or toluene were determined in n‐hexane in the temperature range −50 to +20°C by use of the chemical shifts. The concentrations of the complex species in the alternating copolymerization solutions were estimated by use of the equilibrium constants. There is a linear relationship between the enthalpy and the entropy changes for the ternary molecular complex formation, which is governed by the enthalpy factor. The specificity of the interactions indicates a specific time‐averaged orientation of benzene ring to the coordinated methyl methacrylate. The effects of the coordination of methyl methacrylate to stannic chloride were discussed on the basis of results of 13C‐NMR spectroscopy.
Kinetic approach to radiation–induced grafting in the polyethylene–styrene system
Authors: Imai Masahiko , Shimizu Harumichi 
Published: April 2003

AbstractTo investigate the mechanism of radiation‐induced grafting in this system, the increase of monomer concentration in the polyethylene film in styrene vapor was evaluated by measuring the weight increase and formulated to be V([M∞] − [M]). The decay of radical concentration was also measured by ESR and the rate constant of the decay was determined. The alkyl type radical was affected only a little by styrene, while the allyl type radical was much affected by styrene. A new computer investigation method was proposed to clarify the reaction mechanism. The data obtained were substituted into differential equations and used to calculate the pattern of increase of the degree of grafting for the preirradiation method with reaction in the vapor phase. Results of these calculations suggest that only allyl type radicals induce grafting reactions and that the grafting reaction seldom occurs in the region of grafted polystyrene.
Photo‐induced cellulose radicals capable of initiating graft copolymerization
Authors: Kubota Hitoshi , Ogiwara Yoshitaka , Matsuzaki Kei 
Published: April 2003

AbstractThe decay behavior of cellulose radicals produced by photo‐irradiation at room temperature and the characteristics of photo‐irradiated cellulose samples to initiate graft copolymerization of methyl methacrylate (MMA) were investigated. ESR spectra of such untreated, swollen, oximated, and ferric ion‐sensitized samples irradiated at room temperature were constructed mainly of a single absorption line with a line width of 20 to 22 gauss and a g value of 2.003, and it is surely conceivable that the radicals showing a singlet spectrum should agree with those of alkoxy end produced at either the C1 or C4 position of the glucose unit by the scission of glucosidic bonds. The decay of radicals was accelerated by contact of various solvents with the samples, the activity decreasing in the order, water ≈ methanol ≫ acetone > dioxane. On the other hand, the decay of radicals by vinyl monomers became smaller in the order, methacrylic acid > MMA ≈ styrene. Graft copolymerization of MMA by a photo‐irradiated sample was effectively initiated with the use of a certain amount of water or methanol, but not with acetone and dioxane. As no initiation can occur with the unirradiated sample, it is concluded that the initiation of graft copolymerization on the photo‐irradiated sample is attributable to cellulose radicals showing a singlet spectrum which are formed in photo‐irradiation at room temperature.
Mechanism of vinyl chloride polymerization
Authors: (Rogozinski) M. Ravey , Waterman J. A. , Shorr L. M. , Kramer M. 
Published: April 2003

AbstractAn overall mechanistic scheme for the suspension polymerization of vinyl chloride is presented. The process can be resolved into five discrete stages, each of which presents a unique environment for the interaction of the systems parameters. It is shown that the surface area of the polymer formed during the reaction is not a major factor in autoacceleration and that the increase of kinetic chain length with conversion is due to a radical dilution effect. The latter is a direct result of the difference in rates between polymerization and radical formation, the former being greater. The increase of the initial polymerization rate and the reduction of autoacceleration brought about by chain transfer agents can be explained by the lower diffusion rate and greater bulkiness of the chain transfer agent radical relative to that of the monomer radical. The chaintransfer agent CBr4 is preferentially absorbed by PVC from solution in vinyl chloride. With lauryl peroxide as initiator it is shown that the “hot spot” is the result of a build‐up of initiator in the monomer caused by its exclusion from the polymer phase. Vinyl chloride was found to dissolve 0.03% PVC at ambient temperature and to have no effect on the decomposition rate of lauryl peroxide.
Synthesis and polymerization of 1,5‐dioxo‐1‐methyl‐4‐azaphosphepane
Authors: Shalaby S. W. , Sifniades S. , Klein K. P. , Sheehan D. 
Published: April 2003

Abstract1,5‐Dioxo‐1‐methyl‐4‐azaphosphepane was synthesized and polymeized in the presence of water, stannic chloride, or phosphoric acid. Polymers obtained by using these catalysts were shown to have lower molecular weights than nylon 6 samples prepared under identical reaction conditions. Thermal and other physical properties of the phosphorus‐containing polyamide are reported and compared with those of nylon 6.
Preparation and properties of n6‐tricarbonylchromium‐complexed arylenesiloxane polymers
Authors: Pittman Charles U. , Patterson William J. , McManus Samuel P. 
Published: April 2003

AbstractPolytetramethyl‐p‐silphenylenesiloxane (I) and polymethylphenylsiloxane (II) were prepared and subsequently reacted with hexacarbonylchromium to generate their n6‐Cr(CO)3 complexed analogs, III and IV, respectively. During the complexation reaction, completing decomposition to chromium salts took place. Furthermore a competing chain scission reaction took place resulting in lower molecular weights for the complexed polymers. Heating III and IV resulted in carbon monoxide evolution and the presence of n6‐Cr(CO)3 moieties lowered the thermal stability of the polymers.
Polymerization of diallyl phthalate and gelation of poly(diallyl phthalate) by copolymerization with styrene
Authors: Ito Koichi , Murase Yasuo , Yamashita Yuya 
Published: April 2003

AbstractIn the polymerization of diallyl phthalate in bulk at 60°C with azobisisobutyronitrile, extensive branching of the polymers obtained before gelation was ascertained from the enhanced broadening of the molecular weight distribution, coupled with the decrease of the residual unsaturation. Copolymerization of poly(diallyl phthalate) and styrene in bulk at 80°C with benzoyl peroxide was studied in detail with regard to the gel formation. The gel time increased with increasing fraction of styrene in feed. Both the gel yield and the conversion of styrene incorporated into the gel increased steadily with polymerization time, even after the total conversion of styrene exceeded 95%. The polystyrene recovered by saponification of the gel was found to carry hydroxyl groups, which should come from the copolymerized diallyl phthalate units. It was concluded that styrene behaved as a diluent in the early stage, and that the crosslinking after gelation of the system proceeded mainly through polymer–polymer reactions involving the occluded polystyryl radicals and poly(diallyl phthalate).
Fluorocarbon polymers with alternating oxyalkylene and oxysilylene units
Authors: Tanquary A. Charles , Burks Robert E. , Jackson M. Virginia 
Published: April 2003

AbstractLinear polymers were prepared by the condensation of bis(dimethylamino)dimethylsilane and 1,4‐bis(dimethylaminodimethylsily)benzene with fluorocarbon diols. 1,5‐Dihydroxy‐3‐methyl‐1,1,5,5‐tetrakis(trifluoromethyl)‐2‐pentene, the cis addition product of hexafluoroacetone and isobutylene, with the silylbenzene monomer gave a polymer that cured at room temperature to a rubber exhibiting a glass transition temperature of 0°C, low swelling in hydrocarbons, and excellent resistance to hydrolytic, oxidative, and thermal degradation, retaining its flexibility after exposure to air for 3 hr at 305°C. The polymers obtained by condensing 1,5‐dihydroxy‐1,1,5,5‐tetrakis(trifluoromethyl)‐2‐pentene, the trans addition product of hexafluoroacetone and propylene, with the silylbenzene and the silane monomers had glass transition temperatures of −12 and −50°C respectively, and greater resistance to swelling in hydrocarbons.
Highly branched acrylamide graft copolymer
Authors: Kim Oh‐Kil , Griffith James R. 
Published: April 2003

AbstractAcrylamide graft copolymerization onto poly(3‐O‐methacryloyl D‐glucose) (PMG) as a backbone was performed by the ceric ion method. The number of polyacrylamide (PAM) chains grafted was dependent upon the concentration ratio of the redox catalyst system at constant acid concentration and increased in proportion to the ceric ion concentration. A maximum number of grafts obtained, for example, was 29 onto PMG (DP = 244) under the conditions [Ce4+]/[PMG] = 1/5, [H+] = 1.0 × 10−2 mole/l. In other words, the graft frequency was 12 per 100 monomer units of PMG. Such a high frequency of the grafts was, however, greatly decreased when the acid concentration was increased. Characteristics of the highly branched structure were revealed by the relationship between intrinsic viscosity and graft frequency, which showed a downward curvature with the increasing graft frequency. Influences of acid and ceric ion concentrations on the copolymerization were kinetically evaluated. The rate of polymerization was found to be first‐order with respect to ceric ion and proportional to the square of the reciprocal acid concentration. The result suggests that the graft frequency is dependent upon the rate of polymerization.
Copolymerization behavior of vinylimidazolium salts
Authors: Salamone J. C. , Taylor P. , Snider B. , Israel S. C. 
Published: April 2003

AbstractCopolymerization studies of cationic monomers have been reported in the literature to yield wide variations in reactivity ratios and Q–e values, depending on the comonomer and the nature of the solvent. In this work are presented the copolymerization characteristics of a variety of vinylimidazolium salts in both water and ethanol solution. From these studies, the effect of solvent polarity, of substitution at the imidazolium 2‐position, of the type of counterion, and of the hydrophilic–hydrophobic character of the monomeric salts could be ascertained. The results of the study are consistent with other related investigations, in that solvent polarity and comonomer both strongly affected copolymerization.
Solid‐state ultraviolet irradiation of some maleimides and bismaleimides
Authors: Boens N. , De Schryver F. C. , Smets G. 
Published: April 2003

AbstractThe solid‐state photoreactivity of a series of maleimides and bismaleimides is studied Various crystalline maleimides are found to dimerize on irradiation by ultraviolet light Based on this discovery, the photopolymerizability of the related bismaleimides in the crystalline state is examined. As a result it is found that some N,N,‐alkylenebismaleimides polymerize into highly crystalline polymers. The polymers do not melt below their decomposition temperature (>300°C) and are practically insoluble in all solvents. The obtained irradiation products are different from the reaction products of the solution‐phase photochemistry. Closely related bismaleimides, such as members of a homologous series, show substantial differences in their solid‐state photochemical behavior; on excitation they either lead to polymers or are not reactive. This indicates that the solid‐state photoreactivity of maleimides and bismaleimides is controlled by the geometry of their crystal structure.
Cationic copolymerization of propylene oxide with tetrahydrofuran. VI. Triphenylmethyl hexafluorophosphate as initiator
Authors: Blanchard L.‐P. , Gabra G.‐G. , Hornof V. , Malhotra S. L. 
Published: April 2003

AbstractCopolymerizations at −10 to +20°C of propylene oxide (PO) with tetrahydrofuran (THF) were carried out in 1,2‐dichloroethane (DCE) under dry, inert atmospheric conditions. Reactions were initiated by triphenylmethyl hexafluorophosphate (TPM‐HFP) and subsequently followed by vapor‐phase chromatography. Vacuum‐dried residual copolymer products (RCP) were analyzed by gel‐permeation chromatography (GPC), vapor‐pressure osmometry (VPO) and nuclear magnetic resonance spectrometry (NMR). Attempts to homopolymerize THF in equimolar mixtures of DCE and THF at THF/TPMHFP ratios of 1:1 × 10−3 proved futile, while the homopolymerization of PO under identical operating conditions took place quite readily. Copolymerizations of PO–THF mixtures were easily carried out with high and often complete consumption of both monomers though, more often than not, THF was the principal residual monomer at the end of the 24 hr reaction period since, under no circumstances could additional THF be polymerized when the PO charged was completely consumed. Linearity of plots of −ln (C0/C) versus time showed the reactions to be first order with respect to both PO and THF concentrations. Influence of temperature reveals, via Arrhenius plots and overall activation energies (16.0 kcal/mole for PO and 13.0 kcal/mole for THF), that the initiator system functions similarly to other reported systems. Reactivity ratios (0.26 for PO and 0.80 for THF) indicate that monomer units tend to alternate along the chains rather than form extended segments of a given kind. This is supported by NMR analyses of RCP samples. Bimodal GPC distributions observed in the present study suggest that the copolymerization reaction may be proceeding by either a dual mechanism or a two‐step process.
Kinetics of polymerization of diallyl phthalate (DAP) by γ‐rays
Authors: Divakar D. S. , Rao K. N. 
Published: April 2003

AbstractDiallyl o‐phthalate (DAP) has been polymerised by γ‐radiation from a 60Co source and the kinetics of polymerization have been studied at several dose rates and temperatures. The results show that the rate of polymerization was proportional to I0.68, where I is the radiation dose rate. The net activation energy of the polymerization reaction (Ep − 1/2Et) was 5.02 kcal/mole, where Ep and Et are the activation energies for the propagation and termination steps, respectively. The radical yield GR for DAP was measured by the loss of diphenyl picryl hydrazyl (DPPH) used as a radical scavenger. GR in the solution after irradiation was 3.12. The ratio of the rate constants kp2/kt was calculated to be 4.09 times; 10−7 at 25.8°C and 15.0 × 10−7 at 55.4°C. At room temperature, the ratio of degradative chain transfer constant to kp, i.e., ku/kp was found to be 0.065 and ktr/ku as 0.032, where ktr is the nondegradative chain‐transfer constant. Molecular weights of these polymers as determined by vapor pressure osmometry showed that the degree of polymerization was between 8 and 10. Infrared spectra of the polymers indicated that intramolecular cyclization took place during polymerization.
Monomer reactivity ratio and Q–e values for copolymerization of hydroxyalkyl acrylates and 2‐(1‐aziridinyl)ethyl methacrylate with styrene
Authors: Chow C. D. 
Published: April 2003

AbstractCopolymers of 2‐hydroxyethyl acrylate, hydroxypropyl acrylate, and 2(1‐aziridinyl)‐ethyl methacrylate (M2) with styrene (M1) were prepared in benzene solution at 60°C. Benzoyl peroxide, 0.1–0.2 mole‐%, was used as initiator. Copolymer samples with the molar concentrations of M2 feed ranging from 0.10 to 0.85 were used to determine the reactivity ratios. Elemental analysis and nuclear magnetic resonance spectroscopy (NMR) were used to determine copolymer compositions. There was a solubility problem when the latter technique was applied. When samples which were completely soluble were analyzed, the results obtained from NMR and elemental analysis were in excellent agreement. The monomer reactivity ratios and the corresponding parameters for the copolymerization of (M1) with 2‐hydroxyethyl acrylate are: r1 = 0.38 ± 0.02, r2 = 0.34 ± 0.03; Q2 = 0.85, e2 = 0.64; with hydroxypropyl acrylate are: r1 = 0.45 ± 0.03, r2 = 0.36 ± 0.03; Q2 = 0.75, e2 = 0.56; with 2(1‐aziridinyl)ethyl methacrylate are: r1 = 0.53 ± 0.02, r2 = 0.63 ± 0.04; Q2 = 0.82, e2 = 0.25.
Effect of amines on vinyl polymerization initiated by chromous acetate–alkyl halide systems
Authors: Lee Munam , Minoura Yuji 
Published: April 2003

AbstractThe radical polymerization of vinyl monomers initiated by Cr2+–RX in the presence of various amines was studied in DMF at 30°C. Polyamines able to form the chelate complex with Cr2+ accelerated the rate of polymerization of styrene in the following order: ethanolamine > triethylenetetramine > diethylenetriamine > ethylenediamine. However, aliphatic monoamine, hexamethylenediamine, and aromatic diamine did not have any effect on the polymerization. These results suggest that the effect of multidentate ligands may be associated with chelating effects which affect the electron transfer ability of the metal complex. An apparent activation energy of 8.2 kcal/mole for the polymerization of styrene was obtained in the presence of ethanolamine. With the Cr2+–CHCl3 system, on addition of ethanolamine, the polymerization of methyl methacrylate was accelerated, and acrylonitrile and vinyl chloride, could be polymerized.
Electrochromism of indolinobenzospirans dissolved in rigid amorphous polymer matrices
Authors: Kryszewski M. , Nadolski B. 
Published: April 2003

AbstractThe effect of a static electric field on the position of absorption bands of colored stereoisomers of two photochromic compounds of the indolinobenzospiropiran group dissolved in matrices of poly(methyl methacrylate), poly(n‐butyl methacrylate), polystyrene, and polycarbonate at room temperature was studied. In the case of matrices with the polymethacrylates the effects observed show that applied electric field produces a shift of thermal equilibrium towards stablization of stereoisomers of larger dipole moment. On the basis of kinetic measurements of attainment of thermal equilibrium on switching the electric field off, the rate constants of their interconversion have been determined. In the case of matrices with polystyrene and polycarbonate, a small red shift only was observed.
Ion‐exchange membranes based on modified polyethylene with aminoacetic acid groups
Authors: Trochimczuk Witold M. 
Published: April 2003

AbstractIon‐Exchange membranes containing aminoacetic, iminodiacetic, and ethylenediamine‐triacetic acid groups were prepared on the basis of polyethylene modified with styrene and divinylbenzene. The polyethylene modified was in the form of a film. Optimum parameters of the membranes were determined by using both the method of statistical planning of the experiments and nonlinear optimization technique. Physical and chemical properties of the membranes were investigated as well. Some observations were also made concerning the structure of the prepared membranes.
Conformation of isotactic poly(styrenesulfonic acid)
Authors: Aylward N. N. 
Published: April 2003

AbstractThe ultraviolet and fluorescence emission spectra of isotactic and syndiotactic poly(styrenesulfonic acids) have been recorded at various temperatures, dilutions, and ionic strengths. Hypochromism in the ultraviolet bands of isotactic PSSA is interpreted in terms of conformational transitions causing an alignment of aromatic residues. A conformational energy map for isotactic PSSA indicates that transitions to the (−15°, 15°) conformation are possible.
Effects of macromolecular matrix on the process of radical polymerization of ionizable monomers
Authors: Tsuchida Eishun , Osada Yoshihito 
Published: April 2003

AbstractRadical polymerization of methacrylic acid (MAA) and acrylic acid (AA) in the presence of a positively charged macromolecular matrix was studied. In the presence of a matrix, the rates of polymerization were remarkably increased, especially in high pH region. This suggests that electrostatic interaction between the macromolecular matrix and the growing chains and/or the monomer molecules plays an important role in the process of polymerization reaction. The kinetic orders were greatly influenced by the relative matrix concentration (PC) as follows: for (PC)0 > [M]0, Rp = k[M]0.9 [PC]0.3 [I]0.8≤ [M]0 Rp = k[M]0.3[PC]0[I]0,8 where [M] and [I] are monomer and initiator concentration, respectively, and k is a constant. The mechanism of the interaction of matrix with monomer and/or growing chains in the process of the propagation is discussed. The complex formed in the matrix polymerization could be easily made into fiber by spinning.
Some rheological properties of highly crosslinked polysiloxanes
Authors: Katz Dov , Zewi I. G. 
Published: April 2003

AbstractSeven crosslinked polydimethylsiloxanes were prepared from carboxyl‐terminated siloxane oligomers of different average lengths and a trifunctional imine. The 10‐sec torsion modulus was measured as a function of temperature, and compression‐deflection data were obtained on swollen specimens. Polymer‐solvent interaction parameters were calculated from equilibrium swelling ratios and modulus data. The plots of modulus versus temperature show two distinct transitions for all the crosslinked polymers. The low‐temperature transition corresponds to the siloxane chains, whereas the high‐temperature transition should be attributed to the portion of the network chain derived from the crosslinking agent and the organic part of the oligosiloxane. On shortening the siloxane blocks, both transitions shift to successively higher temperatures and higher modulus levels. However, the siloxane transition temperature shows only a limited rise even when the average block length becomes quite small. The low siloxane polymers seem to exhibit two swelling maxima, each corresponding to one of the constituents. The studied materials from nonrandom copolymeric structures typical of block polymers. Such microphase systems can probably be expected in crosslinked polymers whenever the crosslinking agent participates significantly in the network chains and its compatibility with the flexible chains species is poor.
Synthesis of polyamides by ring‐opening polyaddition: Reaction of 4,4′‐disubstituted bisazlactones with diamines
Authors: Ueda Mitsuru , Kino Kohsuke , Imai Yoshio 
Published: April 2003

AbstractRing‐opening polyaddition of 4,4′‐disubstituted bisazlactones with various diamines was carried out in N‐methyl‐2‐pyrrolidone to afford polyamides with pendant amide group having inherent viscosities of 0.17‐0.51 in quantitative yields. The solution polymerization with aliphatic diamines was almost complete at room temperature within 24 hr. Nearly all of the polyamides were soluble in polar in polar aprotic solvents and in acidic solvents. These polymers began to decompose at around 200–300°C as determined by DTA and TGA under nitrogen.