bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Copolymerizations 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

Diallyl 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

Copolymers 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

The 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

The 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

Ion‐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

The 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

Radical 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

Seven 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

Ring‐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.
Kinetics and mechanism of the cationic polymerization of tetrahydrofuran in solution. I. THF–CCI4 system
Authors: Matyjaszewski Krzysztof , Kubisa Przemysław , Penczek Stanisław
Published: April 2003

Polymerization of THF in CCl4 solvent was initiated with 1,3‐dioxolan‐2‐ylium eations with AsF6−, PF6−, and SbF6− anions as well as with esters of fluorosulfonic and trifluoromethanesulfonic acids. With these esters polymerization proceeds with a marked acceleration period, due to slow initiation. The corresponding rate constants of initiation and their dependence on the polarity of the THF/CCl4 mixture were determined. The rate constant of propagation on the macroion‐pairs (kp±) of the polytetrahydrofurylium cation with AsF6−, PF6−, and SbF6− and CF3SO3−, anions was found to be independent in CCl4 solvent on the anion structure and given by the expression: kp± = 2.93 × 10−2 exp {−4.7 × 103/T} at [THF]0 = 8.0M. This constant depends on the polarity of the polymerization mixture, and at 25°C for the THF‐CCl4 system, kp± = 1.78 × 10−2 exp {−4.9/D}; thus, in CCl4 at [THF]0 = 8.0M, and at 25° kp± = 4.0 × 10−21/mole‐sec. In the polymerization with derivatives of CF3SO3H (able to form the corresponding macroester) the overall polymerization rate is much lower than that with complex anions because of the reversible conversion of the macroion‐pairs into the macroester (internal return). The macroester is much less reactive than the macroionpair (102–103 times) in the monomer addition reaction. At [THF]0 = 8.0M and at 25°C, 96.5% of the growing species exists in the macroester form.

Polymerization of THF initiated with derivatives of CF3SO3H is a subject of a strong special salt‐effect. At a sufficiently high ratio of [AgSbF6] to [I]0, where the initiator I is C2H5OSO2CF3, the overall polymerization rate is equal to that observed for the polymerization of THF on the macroion‐pairs, since the internal return within the triflate ion‐pair (the macroester formation) is eliminated and polymerization proceeds on the macroion‐pairs with SbF6‐ anions exclusively.
Critical surface tension of poly(vinyl butyral) and poly(vinyl benzal) multilayers and its relation to their surface orientation. I. Effect of surface pressures during deposition
Authors: Ueno M. , Meguro K.
Published: April 2003

Critical surface tensions γc of poly(vinyl butyral) and poly(vinyl benzal) multilayers built up by the Langmuir‐Blodgett method were measured with polyhydric alcohols and n‐alkanes. The γc values of both polymer multilayers increased with increasing pressures of the piston oils used to control pressures of polymers on the water surface during deposition. The γc value of poly(vinyl butyral) multilayers built up to lower pressure of the piston oil was approximately consistent with a crystalline hydrocarbon surface, while the γc value of the multilayer built up to higher pressure of the piston oil was approximately consistent with a—CH3 rather than a CH2 CH2 surface. All results for γc values of poly(vinyl benzal) multilayers were very close to the γc value of benzene ringrich surface. The γc value of the multilayer built up to lower pressure of the piston oil almost coincided with the γc value for amorphous polystyrene, while the γc value for the multilayer built up to higher pressure of the piston oil was in fair agreement with γc for an aromatic ring edge in the crystalline state. Values of γsd, the dispersion force contribution to the surface free energy of multilayers calculated by Fowkes' relation, were in fair agreement with the corresponding observed γc values, respectively. It is concluded from these measurements that orientations and surface structures in both polymer multilayers are affected by pressure change of piston oils. The properties on monolayers of two polymers at a air‐water interface and on barium stearate multilayers are also presented.
Effects of solvent on the free‐radical copolymerizabilities of pyridazinones with styrene
Authors: Matsubara Yoshio , Enyo Kooji , Yoshihara Masakuni , Maeshima Toshihisa
Published: April 2003

Free‐radical copolymerizations of N‐methylpyridazinone (I) and N‐phenylpyridazinone (II) with styrene (M1) were carried out in various solvents. The copolymerization rates were found to increase linearly with increasing viscosities of the reaction mixtures. Monomer reactivity ratios were strongly affected by the reaction media. This might be due to solvation of the carbonyl group of the pyridazinone ring, because linear relationships between log 1/r1 and vc=o of the pyridazinones were obtained. It was also found that monomer concentration influences these copolymerizabilities.
Photopolymerization of methyl methacrylate by use of a quinoline–bromine charge‐transfer complex as the photoinitiator
Authors: Ghosh Premamoy , Mitra Partha Sarathi
Published: April 2003

Polymerization of MMA was carried out in presence of visible light (440 nm), quinoline‐bromine charge‐transfer complex being used as the photoinitiator. The initiator exponent was observed to be 0.5 up to 0.014 M initiator concentration; when chloroform was used as the solvent, the monomer exponent was found to be unity. The polymerization was inhibited in presence of hydroquinone but little inhibitory effect was observed in the presence of air. An average value of k2p/kt for this photopolymerization system was found to be (1.08 ± 0.22) × 10‐2. Kinetic and other evidence indicates that the overall polymerization takes place by a radical mechanism.
Thermosetting diphenyl sulfone‐based maleimides
Authors: Kwiatkowski G. T. , Robeson L. M. , Brode G. L. , Bedwin A. W.
Published: April 2003

Thermosetting arylimides were prepared by reaction of sulfone ether diamines with maleic anhydride followed by chemical imidization of the intermediate polyamic acid with acetic anhydride/sodium acetate. These arylimides could be thermally cured to afford heat stable systems possessing high glass transition temperatures (Tg) and moderate to high modulus plateaus above the Tg, depending upon the molecular weight between maleimide sites. The addition type curing process alleviates problems associated with the fabrication of other polyimide systems, since volatiles are not liberated and lowviscosity, high‐solids solutions can be prepared in common organic solvents. Thermal, mechanical, adhesive and fabrication characteristics are reported for the sulfone‐based arylimides, which indicate utility in spectrum of high‐temperature applications.
Block sequence distributions and homopolymer content for condensation polymers undergoing interchange reactions
Authors: Kotliar A. M.
Published: April 2003

A mathematical analysis is developed to compute the sequence structure resulting from the interchange reactions that occur with condensation polymers. Computed examples demonstrate the flexibility and limitations of this synthesis technique in attaining novel block copolymers.
Self‐crosslinkable polymers. I. Copolymerization of glycidyl methacrylate with 2‐vinylpyridine and 2‐vinyl‐5‐ethylpyridine
Authors: Tanaka Yoshio , Atsukawa Morishige , Shimura Yukio , Okada Akira , Sakuraba Hideki , Sakata Tokuji
Published: April 2003

A soluble and self‐crosslinkable linear copolymer with pendant epoxy and pyridyl groups was obtained from glycidyl methacrylate (M1) and 2‐vinylpyridine (M2) or 2‐vinyl‐5‐ethylpyridine (M2) by the action of azobisisobutyronitrile. The monomer reactivity ratios were determined in tetrahydrofuran at 60°C: r1 = 0.510, r2 = 0.620 with 2‐vinylpyridine and r1 = 0.57, r2 = 0.62 with 2‐vinyl‐5‐ethylpyridine. These were consistent with the calculated values with the reported Q and e values for these monomers. The intrinsic viscosities of the copolymers with 2‐vinylpyridine and with 2‐vinyl‐5‐ethylpyridine were found to be 0.17–0.19 and 0.26–0.38, respectively, in tetrahydrofuran at 30°C; they were independent of the copolymer composition. The copolymers were amorphous, had no clear melting points, and became insoluble crosslinked polymers under heating without further addition of any curing agents.
Study on radiation‐induced polymerization of vinyl monomers adsorbed on inorganic substances. I. Radiation‐induced polymerization of styrene adsorbed on several inorganic substances
Authors: Fukano Kazuyuki , Kageyama Eiichi
Published: April 2003

The radiation‐induced polymerization of styrene adsorbed on silica gel, white carbon, silicic acid anhydride, zeolite, and activated alumina was carried out to elucidate the effect of properties of inorganic substances on the polymerization. The rate of adsorbed state polymerization on these inorganic substances was very fast in comparison with that of bulk‐state polymerization. The amount of unextractable polymer depends on the specific surface area and chemical compositions of these inorganic substances. Inorganic substances which contain aluminum as a component element are more likely to be grafted than those which consist of SiO2alone. The molecular weight and molecular weight distribution of unextractable polymer and extractable polymer differ from one another in each inorganic substance. In case of silicic acid anhydride, unextractable polymer has smaller molecular weight than extractable polymer. These results suggest that unextractable polymer cannot be extracted due to chemical bonds with the inorganic surface.
Studies on reactions of the N‐phosphonium salts of pyridines. XIV. Wholly aromatic polyamides by the direct polycondensation reaction by using phosphites in the presence of metal salts
Authors: Yamazaki Noboru , Matsumoto Makoto , Higashi Fukuji
Published: April 2003

Poly‐p‐benzamide of high molecular weight (ηinh = ∼ in H2SO4) was obtained by the direct polycondensation reaction of p‐aminobenzoic acid (p‐ABA) by means of diphenyl and triaryl phosphites in N‐methylpyrrolidone (NMP)‐pyridine solution containing lithium and calcium chlorides. Molecular weight of polymer varied with the amount of these salts, showing maximum values at the concentration of about 4 wt‐% of LiCl or about 8 wt‐% of CaCl2 in the reaction mixture. The reaction temperature at around 80°C gave a polymer of the highest viscosity. The polycondensation reaction was also affected by monomer concentration, solvents, and tertiary amines like pyridine. Similarly, aromatic polyamides with high molecular weight (ηinh values up to 1.34 in H2SO4) were prepared from isophthalic acid and aromatic diamines, whereas terephthalic acid gave only low‐viscosity polymers.
Investigations on poly(vinyl chloride). II. Pyrolysis of chlorinated polybutadienes as model compounds for poly(vinyl chloride)
Authors: Iida Takeo , Nakanishi Motoharu , Gotō Kunio
Published: April 2003

The pyrolysis of chlorinated polybutadienes (CPB) was investigated by using a pyrolysis gas chromatograph. CPB corresponds to poly(vinyl chloride) (PVC) constructed with head–head and tail–tail linkages of the vinyl chloride unit. Benzene, toluene, ethyl‐benzene, o‐xylene, styrene, vinyltoluene, chlorobenzenes, naphthalene, and methylnaphthalenes were detected in the pyrolysis products from CPB above 300°C, and no hydrocarbons could be detected at 200°C. The pyrolysis products from CPB were similar to those from PVC and new products could not be detected. Lower aliphatics, toluene, ethylbenzene, o‐xylene, chlorobenzenes, and methylnaphthalenes were released more easily from pyrolysis of CPB than from PVC; amounts of benzene, styrene, and naphthalene formed were small. These results support the conclusion that recombination of chlorine atoms with the double bonds in the polyene chain takes place and that scission of the main chain may depend on the location of methylene groups isolated along the polyene chain during the thermal decomposition of PVC.
Cationic polymerization of styrene by acetyl perchlorate. II. Steric structure of the polymer and nature of the propagating species
Authors: Higashimura Toshinobu , Kishiro Osamu , Matsuzaki Kei , Uryu Toshiyuki
Published: April 2003

Cationic polymerization of styrene initiated by acetyl perchlorate in CH2Cl2 yields a polymer having a bimodal molecular weight distribution. The high molecular weight and the low molecular weight portions of the polymer were separated by thin‐layer chromatography, and the steric structure of these separated polymers was investigated by 13C NMR spectra. The high molecular weight polymer had a larger racemic dyad content than the low molecular weight material. From the dependence of the steric structure of the polymer on the polarity of a solvent, it was estimated that the propagating species producing the high molecular weight material was a loose ion pair or a free ion, and that producing the high molecular weight material was a loose ion pair or a free ion, and that producing the low one was a nondissociated species.
Influence of six‐ and eight‐membered rings on the dynamical behavior of polymers
Authors: Kotlík P. , Heidingsfeld V. , Zelinger J.
Published: April 2003

Dynamic‐mechanical properties of mixtures of polymers with low molecular weight substances containing six‐ and eight‐membered rings were studied. Secondary relaxations have been found and interpreted by means of the theory of conformational motions. There is good agreement of the results with literature data.
Terpolymerization studies. III. Terpolymerization of acrylonitrile, styrene, and α‐cyanocinnamamide
Authors: Liebersohn Aharon , Kohn David H.
Published: April 2003

Acrylonitrile (M1), styrene (M2), and α‐cyanocinnamamide (α‐CCA) (M3) were terpolymerized by thermal initiation to low conversion, and the monomer feed/terpolymer composition relationship was determined by Slocombe's triangular graph. The solubility, the thermal behavior, the impact strength, and the chemical resistance of the terpolymers of various compositions were investigated.
Outer‐sphere electron‐transfer reactions of co(III)–polymer complexes in relation to its polymer effects
Authors: Tsuchida Eishun , Shigehara Kiyotaka , Kurimura Yoshimi
Published: April 2003

The outer‐sphere electron‐transfer reactions between [Co(III)(NH3)5L] (CIO4)3 [L = polyethyleneimine (PEI), L = NH3(Amm)] or cis‐[Co(III)(en)2L′Cl]Cl2 [L′ = poly‐N‐vinyl‐2‐methylimidazole(PVI), poly‐4‐vinylpyridine (PVP), N‐ethylimidazole (NEI), pyridine (Py)] and various Fe(II) were studied. In the reaction with Fe(II)‐(phen)32+, the reactivity of Co(III)–PEI was smaller than that of Co(III)–Amm due to the larger electrostatic repulsion. On the other hand, the reactivity of Co(III)–PEI was larger by a factor of 80 in the reaction with Fe(II)(H2O)62+. From the results of rapid‐scanning spectroscopy, the higher reactivity of Co(III)–PEI is caused by the coordination of free ethyleneimine residues in the Co(III)–PEI to Fe(II)–ion. Further more, the hydrophobic interaction between heteroaromatic polymer ligands and Fe(II)‐(phen)32+ brought about the higher reactivities of Co(III)–PVI and Co(III)–PVP. Three interactions caused by the essential properties of polymers are discussed in relation to conformational changes.
Effect of metals on melt oxidation of polyethylene
Authors: Egorenkov N. I. , Lin D. G. , Bely V. A.
Published: April 2003

Oxidation of polyethylene (PE) melts in contact with metals (Cu, Pb, Au, Al, Zn, Ag) has been studied by infrared spectroscopy and differential thermal analysis (DTA). These metals may be divided into two groups, depending on their activity for oxidizing PE: namely, high‐activity metals (Cu, Pb, Ag, Zn) and low‐activity metals (Al, Au). During the oxidation of PE in contact with high‐activity metals dissolution of the surface layer of metal is observed with accumulation of metal‐containing compounds (salts of carboxylic acids) in the bulk of the polymer. With low‐activity metals these phenomena are not observed. The rate of oxidation of PE on low‐activity metals approaches the oxidation rate of nonmetals (polytetrafluoroethylene and inorganic glass). With certain high‐activity metals (Cu, Pb) the process of oxidation is accelerated only in the early stage of oxidation; then the oxidation rate slows down and the oxidation process ceases. PE films separated from metal after being oxidized on it possess chemical memory, i.e., their oxidation rate depends on the nature of the metal with which they had been in contact, and on the duration of the contact oxidation. The effect of salts of carboxylic acids (metal stearates) on the oxidation of PE melts was also studied. Based on the data obtained, it is concluded that the rate of oxidation of PE melts on high‐activity metals is controlled by metal‐containing compounds which are the products of contact reactions.
Conversion of polymeric hydroxyl compounds to the corresponding halides
Authors: Cohen H. I.
Published: April 2003

Poly(hydroxyethyl methacrylate) and other polymeric hydroxy esters and hydroxyamides have been converted to the corresponding halo derivatives by the use of trialkylphosphorane dihalides.
Photopolymerization of methyl methacrylate and some other vinyl monomers with the use of chlorine as photoinitiator
Authors: Ghosh Premamoy , Chakraborty Soumen
Published: April 2003

Low concentrations (0.001–0.03M) of chlorine easily induce photopolymerization of MMA at 40°C. Kinetic data indicate that polymerization follows a radical mechanism involving complexation of monomer by the initiator and initiation takes place through radical generation during photodecomposition of the initiator‐monomer complex. Termination appears to take place bimolecularly. The kp2/kt value for MMA polymerization at 40°C was found to be 0.83 × 10−2. Rates of chlorine‐initiated photopolymerization were found to decrease in the order MMA, EMA ≫ VA, Sty > MA.
Pyrolysis and gas chromatography of plasma‐polymerized ethylene
Authors: Seeger Michael , Barrall Edward M. , Shen Mitchel
Published: April 2003

Plasma‐polymerized polyethylene (PPE) obtained on a radio‐frequency glow discharge has been analyzed by flash pyrolysis combined with in‐line hydrogenation and gas chromatography. The pyrogram of a bulk powder PPE, which had been characterized by both infrared spectroscopy and density measurements, was compared with a 400 Å thick PPE film deposited directly on the pyrolysis probe. Although the two pyrograms have a qualitative resemblance, they are substantially different from that of conventional branched polyethylene (PE). Some of the fragments exhibited by the deposited PPE are also present in pyrograms of 1,4‐polybutadiene. It is evident that the deposited film is a highly branched and unsaturated network polymer with a random arrangement of these structural features.
Reactive polypeptides. II. Photochemistry of poly(γ‐cinnamyl L‐glutamate)
Authors: Kadoma Yoshinori , Ueno Akihiko , Takeda Kenji , Uno Keikichi , Iwakura Yoshio
Published: April 2003

Poly(γ‐cinnamyl L‐glutamate) was irradiated in the presence and absence of benzophenone in dichloroethane. The irradiated polymers were analyzed by gas chromatography after hydrolysis. It was possible to assign the transformation in the presence of benzophenone to trans‐cis photoisomerization by comparing the effects with those observed for a model compound cinnamyl acetate. The equilibrium composition of cis and trans isomers in the photostationary state was similar for the model compound and the polypeptide. Photoisomerization was found to be accompanied by marked side reactions for the direct irradiation. Circular dichroism spectra were empolyed to study the structure, and no changes in the structure were found for the irradiated polymers.
Photoinitiation by radical‐cationic mechanism in the polymerization of isobutylene with lewis acids
Authors: Marek M. , Toman L. , Pilař J.
Published: April 2003

ESR spectra of Lewis acids (VCl4, TiCl4, TiBr4, SnCl4, and AlBr3) and their mixtures with isobutylene were investigated in a n‐heptane solution in the dark and under irradiation at 400–480 nm at −80 to −150°C. A signal was observed only upon irradiating mixtures of VCl4, TiCl4, or TiBr4 and isobutylene. The signal was identified as an isobutylene radical‐cation by comparison with a simulated spectrum. A signal indicating the presence of peroxy radicals were recorded in measurements carried out in the presence of oxygen; these radicals originated from reaction of the isobutylene radical‐cation with oxygen. Radical‐cation initiation by visible light is indicated by the polymerization of isobutylene by VCl4, TiCl4, and TiBr4 and by ESR spectra. The inhibiting effect of oxygen in photochemically initiated polymerization of isobutylene was also elucidated.
Chromatographic techniques for rapid measurement of gel in elastomers
Authors: Gaylor V. F. , James H. L. , Herdering J. P.
Published: April 2003

Techniques for measuring gel contents of elastomers by liquid exclusion chromatography are described. Chromatographic methods are based on solubilizing aqueous latex in a water‐miscible elastomer solvent. The resulting mixture of solubilized elastomer and dispersed gel particles is separated and analyzed by liquid chromatography, columns packed with porous glass particles and a differential refractometer detector being used. Applicability of these techniques is illustrated with results for typical nitrile elastomers in methyl ethyl ketone. Chromatographically measured gel contents in the range 30–80% gel were in good agreement with those measured by a classical, 3‐day static method. Repeatability of chromatographic measurement was ±1.35% gel. The entire analysis, including solution preparation, required less than 1 hr and can be as short as 10–20 min.
Ethylene polymerization studies with supported cyclopentadienyl, arene, and allyl chromium catalysts
Authors: Karol Frederick J. , Johnson Robert N.
Published: April 2003

Highly active catalysts for low pressure ethylene polymerization are formed when chromocene, bis (benzene)‐ or bis (cumene)‐chromium or tris‐ or bis (allyl)‐chromium compounds are deposited on high surface area silica‐alumina or silica supports. Each catalyst type shows its own unique behavior in preparation, polymerization, activity, isomerization, and response to hydrogen as a chain transfer agent. The arene chromium compounds require an acidic support (silicaalumina) or thermal aging with silica to form a highly active catalyst. At 90°C polymerization temperature arene chromium catalysts produced high molecular weight polyethylene and showed, in contrast to supported chromocene catalysts, a much lower response to hydrogen as a chain transfer agent. An increase in polymerization temperature caused a significant decrease in polymer molecular weight. Addition of cyclopentadiene to supported bis (cumene)‐chromium catalyst led to a new catalyst which showed a chain transfer response to hydrogen typical of a supported chromocene catalyst. Polymerization activity with tris‐ or bis (allyl)‐chromium appears to depend on the divalent chromium content in the catalyst. Changes in the silica dehydration temperature of supported allyl chromium catalyst have a significant effect on the resulting polymer molecular weight. High molecular weight polymers were formed with catalysts that were prepared using silica dehydration temperatures below about 400°C. Dimers, trimers, and oligomers of ethylene were usually formed with catalysts that were prepared on silica dehydrated much above 400°C. The order of activity of the different types of catalysts was chromocene/silica > chromocene/silica‐alumina > bis (arene)‐chromium/silica‐alumina ≃ allyl chromium/silica.
Trityl‐initiated copolymerizations of propylene oxide with tetrahydrofuran. VIII. Influence of reaction parameters
Authors: Blanchard L. P. , Gabra G. G. , Malhotra S. L.
Published: April 2003

The copolymerization of propylene oxide (PO) with tetrahydrofuran (THF) in dichloroethane (DCE) has been studied at −10, 0, +10, and +20°C. The reactions were initiated by triphenylmethyl cations associated with the following gegenions: PF6−, SbF6−, and AsF6−. The overall energies of activation (Eα of PO and Ea of THF) obtained with the three gegenions increase as one passes from PF6− to AsF6− then to SbF6−, though the magnitude of the increase in each case is not substantial. On the other hand, the associated frequency factors A show a considerable variation with the gegenion. The bimodal distributions of the molecular weights, obtained by GPC with the copolymer produced from reactions initiated with triphenylmethyl hexafluorophosphate, show that the proportions of the lower molecular weight component (L) decrease as the solvent is changed from DCE to toluene, and this is even more marked when bulk polymerization conditions are adopted. The proportions of the higher molecular weight component (H) however increase, as does its molecular weight. The GPC molecular weight distributions of the copolymers initiated with triphenylmethyl hexafluorophosphate in DCE to which water has been added, show that the molecular weight of component H decreases with increasing concentration of water, while that of component L remains practically unchanged at a value of 308. This corresponds to an average degree of polymerization (DP) of 4 to 5. The NMR and infrared spectra of copolymers prepared in the presence of still higher initial water concentrations indicate that the PO‐based polymer segments are present in excess of those required for a 1:1 copolymer.
Reaction of diisocyanates with alcohols. I. Uncatalyzed reactions
Authors: Anzuino G. , Pirro A. , Rossi O. , Friz L. Polo
Published: April 2003

Because diisocyanates are widely used raw materials in the production of urethane elastomers and foams, it is of particular interest, to know the contribution of secondary reactions to the overall reaction between diisocyanates and polyether glycols, because of the well known influence of crosslinks on the physicochemical properties of polyurethanes. A mathematical method is suggested to calculate rate constants for the primary and secondary reactions, the hypothesis being that the allophanate group is the main secondary product. The method has been verified with experimental data obtained by reacting models. In addition, the influence of the [NCO]/[OH] ratio and of temperature on the formation of the allophanate group has been studied. The method has been applied to the reaction of 4,4′‐diphenylmethane diisocyanate with poly(oxytetramethylene) glycol, a polyether glycol specifically designed for use in preparing polyurethanes. The results are in complete agreement with the experimental data.
Synthesis of polymaleamides by ring‐opening polyaddition reaction of N,N′‐disubstituted bisisomaleimides with diamines
Authors: Imai Yoshio , Ueda Mitsuru , Kanno Susumu
Published: April 2003

The ring‐opening polyaddition reaction of N,N′‐disubstituted bisisomaleimides with various diamines in N‐methyl‐2‐pyrrolidone at room temperature afforded polymaleamides having inherent viscosity up to 0.7 in almost quantitative yield. These polymers are a new class of homopolymaleamides and ordered alternating copolymaleamides. Almost all of the polyamides were soluble in a wide range of solvents such as dimethylsulfoxide, dimethylacetamide, m‐cresol, and formic acid. They did not show any melt temperature, and began to decompose at a temperature ranging between 200 and 300°C.
Preparation and addition polymerization of substituted 2‐oxazolines
Authors: McManus Samuel P. , Patterson William J. , Pittman Charles U.
Published: April 2003

The new oxazoline‐containing monomers, 4‐acrylyloxymethyl‐2,4‐dimethyl‐2‐oxazoline (AOMO), 4‐methacrylyloxymethyl‐2,4‐dimethyl‐2‐oxazoline (MAOMO), 4‐methacrylyloxymethyl‐2‐phenyl‐4‐methyl‐2‐oxazoline (PMAOMO), and the previously known monomer, 2‐isopropenyl‐4,4‐dimethyl‐2‐oxazoline (IPRO), were synthesized for addition polymerization studies. The monomers were homopolymerized in benzene using a free radical initiator and in aqueous media using emulsion techniques. Molecular weights of 8,000–15,000 (M̄w) were obtained for the homopolymers. Copolymerization studies were carried out with AOMO, MAOMO, and IPRO as M1, and methyl methacrylate (MMA), methyl acrylate (MA), styrene (STY), acrylonitrile (AN), and vinyl acetate (VA) as M2 for each case of M1. Relative reactivity ratios for the fifteen copolymers and Q and e values for the three oxazoline monomers were determined. The r1 values for AOMO and MAOMO copolymerizations indicated a lower value of k11 than expected, presumably because of steric effects. The r1 values in the IPRO copolymerizations were somewhat larger than expected. It was proposed that significant electron donation to the radical center of IPRO·by resonance effects occured.
Block and graft copolymers by selective cationic initiation. III. Synthesis and characterization of bigraft copolymers
Authors: Kennedy Joseph P. , Vidal Alain
Published: April 2003

The synthesis and characterization of new bigraft copolymers poly[(ethylene‐co‐propylene‐co‐1,4‐hexadiene)‐g‐styrene‐g‐α‐methylstyrene] (Nordel‐g‐PSt‐g‐PαMeSt) and poly[(ethylene‐co‐propylene‐co‐1,4‐hexadiene)‐g‐isobutylene] (Nordel‐g‐PSt‐g‐PIB) are described. The synthesis involves the use of a polyhydrocarbon backbone containing allylic chlorines and bromines (chlorobrominated Nordel) in conjunction with a suitable alkylaluminum compound to initiate selectively the polymerization of a monomer (generally styrene) from the chloride sites and subsequently to initiate the polymerization of another monomer (α‐methylstyrene or isobutylene) from the bromide sites. Conditions conductive to selective and sequential initiation have been worked out. The pure bigrafts are obtained by selective solvent extraction and their homogeneity (by gel permeation chromatography), overall composition (by nuclear magnetic resonance spectroscopy) and molecular weight (by osmometry) are determined.
Polymérisation anionique des diènes. III. Etude thermodynamique de la propagation du butadiène et de i'isoprène par les organo‐alcalins
Authors: Salle Robert , Essel Alain , Gole Jean , Pham Quang‐Tho
Published: April 2003

The present work is concerned with the influence of the polymerization temperature on the propagation mechanisms of polyisoprenyl‐ and polybutadienyl‐alkali metals. The thermodynamic parameters of the contact ion pairs and free ions propagations have been calculated. With Li+ in dioxane solvent, the vinyl propagation is stereospecific (for isoprene, the propagation is mainly 4–3). In comparison with benzene, the vinyl propagation of the polydienyl‐Li contact ions pairs should be due to complexation of Li+ by dioxane, an electron donor having a weak dielectric constant. In general, the stereospecificity of the propagation of contact ion pairs decreases with increasing counterion size; little difference has been observed with K+ and Cs+ ion pairs in dioxane and benzene media. For isoprene, the methyl substituant should have chiefly a steric effect in the propagation of free ions, whereas it should confer a polar character to the isoprene molecule in the presence of ions pairs.
Polymerizability of unsaturated monomers capable of forming stable radicals
Authors: Kato Masao , Takemoto Yutaka , Nakano Yasuhiko , Yamazaki Masahiro
Published: April 2003

Some unsaturated monomers bearing hindered phenol and arylamine groups capable of forming stable radicals were prepared. Radical polymerizations of vinyl monomers having such groups were investigated with the use of azobisisobutyronitrile, benzoyl peroxide, cumene hydroperoxide, and tetraethylthiuram disulfide as initiator. Polymerizations of these monomers went normally only when azobisisobutyronitrile was used as initiator. The other initiators inhibited polymerizations remarkably or completely. The results suggest that radicals resulting from benzoyl peroxide and cumene hydroperoxide or tetraethylthiuram disulfide abstract hydrogen of the phenol or the amine to produce the stable radicals, thereby inhibiting the polymerization. Meanwhile, carbon radicals resulting from azobisisobutyronitrile add selectively to the vinyl double bonds of the monomers to initiate the polymerizations. The vinyl derivatives as well as allyl derivatives and cinnamic acid derivatives copolymerize easily with conventional monomers such as styrene, maleic anhydride, and butadiene, again, only when azobisisobutyronitrile was used as initiator. Antioxidative properties for styrene copolymers and butadiene‐styrene copolymers incorporating the hindered phenol monomers were investigated.
Formation of free radicals in photoirradiated cellulose. III. Effect of photosensitizers
Authors: Hon Nyok‐Sai
Published: April 2003

The effect of several photosensitizers on the formation of free radicals in cellulose has been investigated. Radicals were generated with ultraviolet light, and examined by means of ESR techniques; irradiations were carried out at 77°K. On irradiation of the sensitized celluloses with light of λ > 3400 Å, samples treated with benzoyl peroxide, hydrogen peroxide, benzophenone, riboflavin, azobisisobutylonitrile, and metallic ions Cr2+ and Ni2+ exhibited single‐line spectra with line widths of 16 to 26 gauss. Samples treated with Pb2+ and Fe3+ exhibited three‐line and five‐line spectra, respectively. On irradiation with light of λ > 2537 Å, most of the sensitized samples exhibited five‐line spectra with different relative signal intensities. Among these, samples treated with Fe3+ manifested the most prominent spectra with the strongest relative signal intensities.
Polymerization of N‐vinylcarbazole by thionyl chloride
Authors: Biswas Mukul , Kamannarayana P.
Published: April 2003

The polymerization of N‐vinylcarbazole (NVC) initiated by SOCl2 in benzene and nitrobenzene solvents was studied at 32°C. Rp is first order with respect to SOCl2 concentration and also to NVC concentration up to a certain NVC concentration, after which it falls. Rate and the molecular weight increase with increasing dielectric constant of the medium. The rate and molecular weight are depressed by the addition of amines, thiophene, and water. The degree of polymerization is independent of SOCl2 and NVC concentration. A conventional cationic mechanism has been suggested, and a suitable kinetic scheme has been proposed in conformity with the findings.
Polymerization of ethylene oxide with potassium‐graphite inclusion compounds
Authors: Panayotov Ivan M. , Berlinova Iliyana V. , Rashkov Ilya B.
Published: April 2003

The polymerization of ethylene oxide (EO) in tetrahydrofuran (THF) initiated by inclusion compounds of potassium in graphite (C24K) at 50°C was studied. During the initial slow stage of the polymerization the catalyst efficiency increases, while during the second rapid stage the reaction proceeds at a constant concentration of the active centers. The influence of the catalyst and monomer concentrations on the concentration of the active centers and on the catalyst efficiency was studied. The existence of the slow stage is explained by diffusion of ethylene oxide between the graphite planes, where both initiation and initial chain growth take place. The diffusion of the growing chains from the catalyst into the solution brings about the formation of a necessary concentration of active centers in the solution, which ensures the rapid growth of the polymer chains under homogeneous conditions. An x‐ray study of the catalyst after polymerization shows a strongly disturbed crystal structure of the graphite. Poly‐(ethylene oxide) obtained at a higher degree of conversion, does not contain low molecular weight fractions.
Mass spectrometric investigation of polymers: Thermal degradation of truxillic and truxinic polyamides
Authors: Caccamese S. , Maravigna P. , Montaudo G. , Przybylski M.
Published: April 2003

The thermal degradation mechanism of four isomeric truxillic and truxinic polyamides were investigated by direct pyrolysis in the ion source of a mass spectrometer. Thermal degradation reactions were followed directly by this method by detecting the thermal and electron impact‐induced fragments. The results obtained have shown that the thermal degradation products are sensibly different for the head‐to‐head (hh) and head‐to‐tail (ht) polymers and that the predominant pyrolytic process is the cyclobutane ring cleavage. In the hh isomers, both symmetrical and asymmetrical cyclobutane ring cleavage was detected, while in the ht isomers only symmetrical cleavage occurs; this explains the noticeable difference found in the thermal stability of the two polymer types.
Study of radiation‐induced polymerization of vinyl monomers adsorbed on inorganic substances. III. Effect of p‐benzoquinone and ammonia on radiation‐induced polymerization of styrene adsorbed on silica gel
Authors: Fukano Kazuyuki , Kageyama Eiichi
Published: April 2003

In order to elucidate the mechanism of radiation‐induced polymerization of styrene adsorbed on silica gel, the effect of p‐benzoquinone and ammonia was investigated. The high molecular weight GPC peaks of both graft polymers and homopolymers decreased with increasing p‐benzoquinone concentration, while the low molecular weight peaks of both graft copolymers and homopolymers decreased with increasing ammonia concentration. The results indicate that the high molecular weight peaks of both graft and homopolymers are formed as a result of a radical mechanism and that the low molecular weight peaks of both types of polymers are formed by a cationic mechanism. In formation of both graft polymers and homopolymers both radical and cationic polymerization take place at the same time.