bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long‐lived polymer radicals. IV. Reactions of poly(N‐methylacrylamide) and poly(N‐methylmethacrylamide) radicals with binary mixtures of vinyl monomers
Authors: Sato Tsuneyuki , Iwaki Takahiko , Otsu Takayuki 
Published: April 2003

AbstractN‐methylacrylamide (NMAAm) and N‐methylmethacrylamide (NMMAm) were polymerized to give polymer microspheres containing living propagating radicals. The microsphere polymer radicals were allowed to react with some binary mixtures of vinyl monomers including alternating copolymerization combinations. The reaction processes were investigated by ESR spectroscopy. In the poly(NMMAm) radical/methyl methacrylate (MMA)/styrene (St) system, the propagating radical from MMA was mainly observed at the higher MMA concentration, while polySt radical prevailed at the lower MMA concentration. In the poly(NMMAm) radical/α‐methylstyrene (α‐MeSt)/diethyl fumarate system, the α‐MeSt radical was exclusively observed, while the maleic anhydride (MAn) radical was predominantly observed in the α‐MeSt/MAn system. In the MAn/diphenylethylene system, the propagating radicals from both monomers were observed at comparable concentrations. The poly(NMAAm) microsphere radical behaved differently in the reaction with the MMA/St mixture. The poly(NMAAm) microsphere was found to incorporate preferentially St, leading to formation of the St radical. The St preference was enhanced in the St/cyclohexyl methacrylate (CHMA) system. These results were in agreement with those of block copolymerization via the reaction of poly(NMAAm) radical with the MMA/St or CHMA/St mixture, where the compositions of the resulting polymers were analyzed by pyrolysis gas chromatography.
Preparation of polymer colloids by chemical reactions in aerosols. I. Poly(p‐tertiarybutylstyrene)
Authors: Partch Richard , Matijević Egon , Hodgson Anthony W. , Aiken Barlow E. 
Published: April 2003

AbstractA procedure was developed by which polymer colloids can be prepared by polymerizing aerosol droplets of monomers with an initiator in the vapor state. This work describes the formation of poly(p‐tertiarybutylstyrene) particles by exposing the corresponding monomer droplets to trifluoromethanesulfonic acid. It was found that the monomer‐to‐initiator mass ratio is the critical factor in determining the uniformity and morphology of the particles. Under ideal conditions spheres of narrow size distribution are obtained. Otherwise porous particles or soft particles with whiskers may develop. The aerosol was prepared in a falling film generator, but other procedures for producing monomer droplets may be used.
Photoconductivity and hole transport in polymers of aromatic amine‐containing methacrylates
Authors: Stolka Milan , Pai Damodar M. , Renfer Dale S. , Yanus John F. 
Published: April 2003

AbstractSubstantial hole transport can be achieved in organic polymers simply by incorporating aromatic amine groups into the monomer. Hole mobilities similar to or greater than those in poly(N‐vinyl‐carbazole) (PVK) were measured in a series of high molecular weight arylamine‐substituted polymethacrylates. The hole transport in these polymers is electric‐field‐dependent as in PVK, varying between E and E2 within a range of 4 × 104 − ∼9 × 105 V/cm. The polymers also exhibit carrier generation in ultraviolet (UV) light in the range of absorption. Synthesis of the monomers, their polymerization, and the general properties of these polymers are discussed.
Heat‐resistant metal phthalocyanine imide copolymers
Authors: Achar B. N. , Fohlen G. M. , Parker J. A. 
Published: April 2003

AbstractThermally stable poly(metal phthalocyanine)imide copolymers were prepared with metal(11) 4,4′,4″,4‴ ‐phthalocyanine tetraamines, 4,4′ ‐diamino diphenyl ether, and 3,3′,4,4′ ‐benzophenone tetracarboxylic dianhydride. Variables such as molar concentrations of the reagents, solvents, and temperature were investigated to optimize the conditions of the polymerization. Inherent viscosity, and infrared (IR) spectral and thermogravimetric analysis (TGA) studies were done to characterize the polymers. These polymers are stable and thier decomposition temperatures both in air and nitrogen are greater than 500°C. Their char yields at 800°C in nitrogen varied between 60 and 76%, depending on the type and concentrations of the metal phthalocyanine tetraamines. These polymers can be used to produce heat‐stable films, fibers, varnishes, and adhesives.
Reactivities of N‐alkylitaconimides in radical copolymerizations with styrene or methyl methacrylate
Authors: Oishi Tsutomu , Momoi Masaaki , Fujimoto Minoru , Kimura Tadashi 
Published: April 2003

AbstractThe radical copolymerizations of N‐alkylitaconimide (RII, R = CH3, C2H5, n‐C3H7, i‐C3H7, n‐C4H9, i‐C4H9, CH2CH2Cl, CH2C6H5) (M1) with styrene (ST) (M2) or methyl methacrylate (MMA)‐(M2) were carried out at 60°C, using azobisisobutyronitrile as an initiator in tetrahydrofuran in order to clarify the substituent effect on the copolymerizations. The monomer reactivity ratios r1, r2 and the Q1 and e1 values were determined from the results obtained. It was found that the relative reactivities 1/r2 of RII toward an attack by a poloystyryl radical could be correlated not by the steric‐substituent constant Es of the alkyl group in RII but by the polar‐substituent constant σ* in Taft's equation: log(1/r2) = ρ*σ* + δ Es. According to the above equation, the ρ* and δ values were obtained as 0.55 and 0, respectively, in the RII‐ST system, while in the RII‐MMA system, the ρ* and δ values were obtained as 0.49 and 0, respectively. It was also observed that the Q1values for RII were proportional to σ* constants and that the e1 values for RII were independent of σ* substituent constant. It was also found that the weight‐average molecular weights of the copolymers are between 8.5 × 104 and 32.5 × 104.
Stereochemistry of photoinitiated emulsion polymerization
Authors: Turro Nicholas J. , Pierola Ines F. , Chung Chao‐Jen 
Published: April 2003

AbstractThe tacticity of poly(methyl methacrylate) (PMMA) samples made by emulsion polymerization (EP) has been determined by NMR spectroscopy at higher resolution than any previous study. When photoinitiation is employed at room temperature, the polymer obtained is highly syndiotactic and more stereoregular than that obtained in homogeneous radical polymerization under the same conditions. The percentage of racemic dyads and the length of racemic sequences vary significantly with the degree of conversion and the temperature, but not with variation of the hydrophobic or the hydrophilic part of the detergent molecules. A magnetic field of 5 kG or less accelerates the polymerization reaction and increases the polymer molecular weight when dibenzyl ketone is employed as oil‐soluble photoinitiator, and has an indirect influence on the polymer tacticity. From measurements of the temperature dependence of the polymer steric composition, the difference of activation enthalphy and entropy of the meso and racemic additions have been calculated. The values do not follow the correlations from precedent literature for radical polymerization in solution if the reaction is considered a first‐order Markov process. The persistence ratio p depends on the detergent and the temperature of the EP; in some cases its difference from unity exceeds the experimental error. These results are interpreted as a conformational effect of the locus of the polymerization in the first stage of the EP (when micelles are present) that favors the racemic addition more than is expected in a homologous solvent such as an alkane, e.g., at the same temperature.
A regenerable immobilized NADH model. Reduction of α,α,α‐trifluoroacetophenone by 1, 4‐dihydronicotinamide anchored to macroreticular polystyrene
Authors: Eling Berend , Challa Ger , Pandit Upendra K. 
Published: April 2003

AbstractA regenerable dihydronicotinamide immobilized on a macroreticular polystyrene carrier was developed and used in an aqueous medium for the reduction of trifluoroacetophenone to the corresponding alcohol. It was shown that the second‐order rate constant for the polymer‐bound reagent is significantly lower than that of the low‐molecular‐weight analog 1‐benzyldihydronicotinamide. The observed reaction rate, however, was of the same order of magnitude as that due to enrichment of substrate in the polymeric pores. It was possible to depress the undesired side reactions to 10–15% per reaction cycle, thereby allowing reutilization of the functionalized polymer.
Copolymerization parameters of substituted aniline monomers
Authors: Chatterjee S. K. , Singh B. P. , Pachauri L. S. 
Published: April 2003

AbstractThe Kelen‐Tüdös linear graphical method was used to determine the copolymerization parameters of some halogen‐substituted (e.g., Cl, Br, I) aniline monomers. It was found during copolymerization with p‐aminobenzoic acid or p‐aminophenol that the reactivity of these monomers followed the order of their basic strength. The order of their basic strength. The order of their reactivity, however, was reversed if they copolymerized with sulfanilic acid (SA). This reversal has been interpreted in terms of the resonance stabilization of monomers, the nature of the acidic functional groups present in the comonomer, and the influence of electron‐accepting or electron‐donating groups present in the comonomers.
Radiation‐induced oxidation of polymers. Effect of antioxidant and antirad agent on oxygen consumption and gas evolution
Authors: Arakawa Kazuo , Seguchi Tadao , Hayakawa Naohiro , Machi Sueo 
Published: April 2003

AbstractThe effects of antioxidants and of an antirad agent mixed in polyethylene and ethylene‐propylene copolymer were investigated by means of oxygen consumption and gas evolution. The antioxidants were NBC, Irganox 1010, and DPPD, and the antirad agent was propyl fluoranthene (PFR). A small amount of the antioxidant (0.5 phr) in polymer decreased oxygen consumption by one‐half or one‐third compared with pure polymer, but the activity was lost with increasing irradiation. The antirad agent also decreased oxygen consumption and it was assumed to act as the energy transfer agent in the polymer matrix.
Cis‐trans isomerization of polybutadiene double bonds during olefin metathesis
Authors: Kumar V. G. , Hummel K. 
Published: April 2003

AbstractThe cis‐trans isomerization of polybutadiene double bonds during metathesis degradation using WCl6/(CH3)4Sn catalyst system has been estimated kinetically along with productive metathesis. The isomerization was followed both for noncrosslinked and for crosslinked polybutadiene. Ninety‐six percent cis‐1, 4 units are found to isomerize into ca. 75% trans‐1, 4 units. The rate of stereomutation is found to be different in the presence and absence of a low‐molecular‐weight olefin. The results are explained with the help of a stereo model originally proposed by Katz (Advances in Organometallic Chemistry, Academic, New York, 1977, Vol. 16.)
Photocleavage of the acetate of a hydroxyphenyl benzotriazole UV absorber: The search for a photo‐Fries rearrangement product
Authors: Li Xiao‐Bai , Winnik Mitchell A. , Guillet James E. 
Published: April 2003

AbstractThe acetate ester of 2‐(2H‐benzotriazol‐2‐yl)‐4‐methyl phenol [Tinuvin P] upon irradiation, either in methylene chloride solution or in poly(methyl methacrylate) films, undergoes a photocleavage reaction to regenerate Tinuvin P. No photo‐Fries rearrangement product can be detected.
Preparation of AB polyacylthioureas and related copolyacylthioureas
Authors: Shimano Yasuo , Sasaki Shoichi 
Published: April 2003

AbstractReaction of sulfinylaminobenzoyl chlorides with lead thiocyanate gave sulfinylaminobenzoyl isothiocyanates (SBIs), from which were derived aminobenzoyl isothiocyanate hydrochlorides (ABIHs). AB polyacylthioureas (PATUs) with inherent viscosities of up to 0.28 dL/g were obtained by treating the SBI with an equivalent of water in N‐methyl‐2‐pyrrolidone (NMP). Low‐temperature solution polyaddition of the ABIH afforded AB PATU with inherent viscosities of up to 0.66 dL/g, which were further increased to as high as 0.75 dL/g by adding lithium bases to the polymerization mixtures. Polyaddition of isophthaloyl diisothiocyanate with intermediate diamines formed by hydrolyzing the adducts of SBI and aromatic diamines afforded copolyacylthioureas with inherent viscosities of up to 1.15dL/g. The copolymers were generally soluble in NMP, whereas solubilities of the AB PATU in analogous solvents were relatively low. Thermogravimetric analyses in both air and nitrogen exhibited weight losses of 5% at 204–236°C for AB PATU and at 170–192°C for the copolymers.
An investigation of some aspects of the photodegradation of plasticized PVC
Authors: Williams G. E. , Gerrard D. L. 
Published: April 2003

AbstractPoly(vinyl chloride) (PVC) plasticized with a phthalate ester was photodegraded with both farultraviolet (λ mainly 254 nm) and near‐ultraviolet (λ > 280nm) light. Multiple changes in the infrared spectra of the films were thus induced. The PVC underwent oxidation, dehydrochlorination, and simultaneous chain scission and crosslinking. Some of the phthalate ester was split along the aliphatic side chains, leading to lower‐molecular‐weight analogs, while a further fraction became firmly bound to the crosslinked part of the PVC. Reaction sequences to account for this complicated series of changes are suggested.
Direct mass spectrometry of polymers. VII. Primary thermal fragmentation processes in polycarbonates
Authors: Foti Salvatore , Giuffrida Mario , Maravigna Pietro , Montaudo Giorgio 
Published: April 2003

AbstractThe primary fragmentation mechanisms in the thermal decomposition of several polycarbonates were studied by direct pyrolysis into the mass spectrometer. Our results indicate that ester exchange reactions predominate in the primary thermal fragmentation process of polycarbonates, causing the formation of cyclic oligomers.
Direct mass spectrometry of polymers. VIII. Primary thermal fragmentation processes in polyurethanes
Authors: Foti Salvatore , Giuffrida Mario , Maravigna Pietro , Montaudo Giorgio 
Published: April 2003

AbstractThe primary fragmentation mechanisms in the thermal decomposition of several polyurethanes were studied by direct pyrolysis into the mass spectrometer. Ester exchange reactions predominate in the primary thermal fragmentation process, causing the formation of cyclic oligomers, which are subsequently cleaved to open‐chain oligomers containing hydroxyl end groups.
Direct mass spectrometry of polymers. IX. Copoly(carbonate‐urethanes) prepared by reorganization of polycarbonates with piperazine
Authors: Foti Salvatore , Giuffrida Mario , Maravigna Pietro , Montaudo Giorgio 
Published: April 2003

AbstractA detailed analysis of the reaction products generated by reorganization of polycarbonates with piperazine, performed by direct mass spectrometry methods, has shown that this reaction actually follows the pathway postulated and that, at 50% piperazine incorporation level, urethanediphenol compounds are almost exclusively produced. This allowed us to obtain, by repolymerization with phosgene, alternating copoly(carbonate‐urethanes) with thermal stabilities comparable to those of the parent polyurethanes. The primary fragmentation mechanisms in the thermal decomposition of these copolymers were studied by direct pyrolysis into the mass spectrometer. Ester exchange reactions predominate here, causing the formation of cyclic oligomers, which are subsequently cleaved to open‐chain oligomers containing hydroxyl end groups.
Some aspects of tailoring flame retardancy in HET‐acid‐based flame retardants
Authors: Vijayakumar Chinnasamy Thangavel , Fink Johannes Karl 
Published: April 2003

AbstractHET acid was condensed with either ethylene glycol or 1,4‐butanediol to yield the respective oligoesters. These oligoesters were characterized by molecular weight, measured by vapor‐pressure osmometry. The degradation mechanism of oligoesters of HET acid with either ethylene glycol or 1,4‐butanediol was elucidated. The thermal properties of these polyesters were studied using differential thermal analysis and thermal volatilization analysis. The mechanism of degradation was proposed on the basis of pyrolysis–gas chromatography studies, the degradation products being subsequently identified by mass spectrometry. It turned out that in the course of decomposition, hexachlorocyclopentadiene was formed, which is believed to be the active substance for flame retardance in these systems. The aspect of tailoring flame retardancy by changing the chemical environment, i.e., by using different diols, is discussed.
Polystyrene degradation during combustion
Authors: Brauman S. K. , Chen I. J. , Matzinger D. P. 
Published: April 2003

AbstractA novel driven‐rod, radiant pyrolysis technique has been used to study steady‐state linear regression of vertically mounted polystyrene rods degrading under high‐flux, nonflaming conditions that simulate those of combustion. With this technique a reliable, reproducible temperature‐depth profile (identical for combustion and radiant pyrolysis) for polystyrene has been obtained and used to successfully calculate the observed mass loss rate. Residues and volatiles have been analyzed. Mechanistic treatment of these results indicates that degradation of polystyrene under these rapid‐heating conditions is similar to that under more conventional slow‐heating conditions in the absence of oxygen. Oxidation is unimportant in the condensed‐phase degradation of polystyrene in this configuration. This radiant pyrolysis technique has also been used to obtain the heat of gasification of polystyrene.
Terpolymerization of acrylonitrile, styrene, and 2,3‐dibromopropyl acrylate
Authors: Saric Karla , Janovic Zvonimir , Vogl Otto 
Published: April 2003

AbstractThe terpolymerization of acrylonitrile with styrene and 2,3‐dibromopropyl acrylate in emulsion and dimethyl formamide solution was investigated. Polymerizations, when stopped at low conversions, yielded terpolymers that showed good agreement between experimental and theoretical copolymerization composition data, calculated from the Alfrey‐Goldfinger equation. The relationship between monomer feed and terpolymer compositions is displayed on triangular coordinate graphs proposed by Slocombe. By using a computer program the lines of unique composition and binary azeotropic composition for both systems were established. In the case of emulsion polymerization the azeotropic ternary point was determined at a molar ratio for acrylonitrile/styrene/2,3‐dibromopropyl acrylate of 0.27/0.61/0.12. The experimental results of emulsion terpolymerization fit the calculated curves satisfactorily over a wide range of monomer compositions up to high conversions. The influence of 2,3‐dibromopropyl acrylate on the thermal and flammability characteristics of the terpolymers is described.
Preparation and polymerization of thyroxine methacrylate monomers
Authors: Burdick Brent A. 
Published: April 2003

AbstractThyroxine methyl ester amides of mono‐, di‐, and tri‐glycyl methacrylates have been prepared. Water‐soluble polymers formed from thyroxine methacrylate monomers by free‐radical copolymerization with acrylamide had molecular weights of (2–4) × 104 (by viscometry). A fluorescent polymer was prepared by copolymerization with a fluorescein methacrylate monomer. Similarly, a polymeric thyroxine material was prepared with amine functionality by copolymerization with N‐3‐aminopropylmethacrylamide. These polymers may have interesting biological and immunochemical properties.
Phosphorus‐containing imide resins. III
Authors: Varma Indra K. , Fohlen George M. , Parker John A. 
Published: April 2003

AbstractThree imide monomers were prepared by reacting maleic anhydride; 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane dianhydride, bis(m‐aminophenyl) methyl phosphine oxide, and tris(m‐aminophenyl) methyl phosphine oxide, and tris (m‐aminophenyl) phosphine oxide. The characterization was done by elemental analysis and infrared spectroscopy (IR). These monomers were soluble in acetone. Their thermal polymerization was investigated by differential scanning calorimetry (DSC). The temperature of the exothermic peak position was influenced by the presence of free amino group in the monomer and was about 50°C higher in monomers that did not contain amino group. Anaerobic char yield of imide monomers cured at 270 ± 2°C for 30 min ranged from 58 to 64%. Graphite cloth laminate fabricated from one of these resins had a limiting oxygen index of 100.
Dielectric investigation on mercerized cotton and some of its hydrolysis residues
Authors: Elshafee E. , Moteleb M. M. Abdel , Kinawi A. , Shinouda H. G. , Rizk H. A. 
Published: April 2003

AbstractThe dielectric behavior of samples of mercerized and hydromercerized cotton was studied in a temperature range of 10–60°C at frequencies of 0.1–10,000 kc/s. The effects of mercerization of medicated cotton and mild hydrolysis of mercerized cotton on the two loss peaks γ and β, found in medicated cotton in this frequency‐temperature range, 1 were explored. Mercerization lowers the height of both peaks and, in addition, reveals another β relaxation process in a higher frequency range. Hydrolysis of mercerized cotton removes the γ process, causes variations in the levels of the first β maximum, depending on the time of hydrolysis, and enhances the second β process. These absorption peaks and the effects of various variables are discussed in terms of molecular structure and possible molecular motions responsible for their occurrence.
Ceric‐initiated polymerization onto polyacrylonitrile with carbohydrate end groups. Graft versus block copolymer formation
Authors: Fanta George F. , Burr Robert C. , Doane W. M. 
Published: April 2003

AbstractStarch‐g‐polyacrylonitrile (starch‐g‐PAN) copolymers were prepared by ceric ammonium nitrate initiation, and the major portion of the starch in these graft copolymers was then removed by acid hydrolysis to yield PAN with oligosaccharide end groups. Although these PAN‐oligosaccharide samples reacted with methyl methacrylate in the presence of ceric ammonium nitrate, the resulting products were largely graft copolymers rather than the expected PAN‐poly(methyl methacrylate) (PMMA) block copolymers. The following evidence is presented for a PAN‐g‐PMMA structure: (i) PAN without oligosaccharide end groups also produced a copolymer with methyl methacrylate under our reaction conditions. (ii) Starch‐g‐PAN (51 or 37% add‐on) was a less reactive substrate toward ceric‐initiated polymerization than PAN with oligosaccharide end groups. (iii) Low‐add‐on (18%) starch‐g‐PAN reacted with methyl methacrylate to give a final graft copolymer in which a large percentage of PMMA was grafted to the PAN component rather than to starch.
Decomposition rate studies of azo initiators in solution
Authors: Idage B. B. , Vernekar S. P. , Ghatge N. D. 
Published: April 2003

AbstractRates of decomposition of di(3‐hydroxybutyl)‐2,2′‐azobisisobutyrate, di(4‐hydroxybutyl)‐2,2′‐azobisisobutyrate, di(2‐hydroxyethyl)‐2,2′‐azobisisobutyrate, di(2‐chloroethyl)‐2,2′‐azobisisobutyrate, and di(2‐hydroxypropyl)‐2,2, all of which are useful in the polymerization of butadiene and isoprene, were measured by nitrogen evolution technique at 60, 70, and 80°C, respectively, in each of the three solvents, namely, toluene, dioxane, and N,N‐dimethylformamide. The thermal decompositions of these azo compounds in solution were first order, and the Arrhenius equation was used to calculate their activation energies.
Photoinitiated polymerization: Effect of the initiator absorbance
Authors: Lissi E. A. , Zanocco A. 
Published: April 2003

AbstractThe dependence of the polymerization rate and average chain length on the absorbance of the initiator in the photoinitiated polymerization of vinyl monomers has been evaluated. It is found that a simple model taking into account the spatially inhomogeneous free‐radical distribution predicts an order in initiator that changes from 0.5 at low concentration to −0.5 at high concentration. The maximum rate is obtained, irrespective to any other condition, when the absorbance of the initiator is 2.51.