bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal properties of random copolyesters of PET and 3‐ and 3,5‐bromo‐substituted p‐hydroxybenzoic acids. II
Authors: Balachandar M. , Balakrishnan T. , Kothandaraman H. 
Published: April 2003

AbstractMelt‐polycondensation of poly(ethylene terephthalate) (PET) and 3‐bromo‐p‐acetoxybenzoic acid or 3,5‐dibromo‐p‐acetoxybenzoic acid in different mole ratios yielded random copolyesters. The copolyesters have higher Tgs than PET because of an increase in mol % of the substituted p‐oxy‐benzoate units and follow Wood's equation for copolymer Tgs. Using this equation, we calculated the Tgs of the homopolymers of 3‐bromo‐p‐oxybenzoate and 3,5‐dibromo‐p‐oxybenzoate, which are not available experimentally, to be 113 and 123°C, respectively. Up to certain percentages of the comonomer composition the copolyesters exhibited cold crystallization and melt transitions which we attribute to the crystallizable segments of PET. The variation in melting temperatures in the composition of the copolymer was explained by Flory's theory. The differences in the melting behavior of the polymer, annealed at various crystallization temperatures for a constant time interval, throws light on the morphological changes that took place in it. Using the Hoffman and Weeks method, we determined the extrapolated equilibrium melting temperatures of these copolyester which were used to calculate the enthalpy of melting for the crystallizable units.
Plasma polymerization of hexafluoroethane
Authors: Masuoka Toshio , Yasuda H. 
Published: April 2003

AbstractIt was found that when hydrogen is mixed in a plasma, hexafluoroethane polymerization is accelerated. ESCA and IR spectroscopy were used to characterize the resulting polymers and to reveal the reaction mechanism. At relatively low hydrogen/hexafluoroethane ratios and radio‐frequency powers of 30 and 100 W (13.56 MHz), no hydrogen could be detected in the polymers with IR spectroscopy. However, after the ratio had increased above one, the hydrogen content increased abruptly. Thus, hydrogen might be looked upon as a sort of scavenger for active fluorine species. ESCA deconvolution analysis of the C1s peaks of the polymers indicated that the polymer structures were uniform throughout the reactor in the hydrogen/hexafluoroethane system at 30 W, even though the distribution of the deposition rate could still be observed. By examining sodium chloride powder exposed to the plasma with IR spectroscopy, it was possible to detect various fluorosilicates, which indicated ablation of the reactor's glass wall by the plasma.
Contribution to the study of self‐avoiding random walks (SARW) confined to strips and capillaries
Authors: Lautout‐Magat Marguerite 
Published: April 2003

AbstractA flexible chain that can assume all possible positions on a lattice without intersection of segments (self‐avoiding random walk, SARW) has been used for a long time as a model of polymers in highly dilute solution, taking into account the excluded volume. In this article, we extend to a SARW subject to spatial constraints an analytical accurate method we have established for a SARW on an unbounded lattice. We now consider a square or cubic lattice extending without limit in the x direction but confined to D layers in the other directions. This is a model for the study of constrained macromolecules the behavior of which is important for instance in connection with the properties of thin polymeric films or fibers, or with the solubility of biopolymers in lipid bilayer membranes. We give recurrence relationships for calculating Cn, the total number of configurations, and xn, the mean x projection of the end‐to‐end separation, for a chain length n. Our method, being analytical, allows a considerable economy of computational time with respect to other methods such as Monte Carlo calculations. It enables us to investigate the asymptotic behavior of xn and to write the partition function of the system.
Functional polymers. XVI. Synthesis and polymerization of 2(2‐hydroxy‐5‐isopropenylphenyl)‐2H‐benzotriazole and a new synthesis of 2(2‐hydroxy‐5‐vinylphenyl)2H‐benzotriazole
Authors: Nir Zohar , Vogl Otto , Gupta Amitava 
Published: April 2003

Abstract2(2‐Hydroxy‐5‐isopropenylphenyl)2H‐benzotriazole was synthesized in 40% overall yield starting from o‐nitroaniline. Diazotization in aqueous hydrochloric acid gave o‐nitrophenyl diazonium chloride which was condensed with p‐hydroxyacetophenone; the azo compound was reduced to 2(2‐hydroxy‐5‐acetylphenyl) 2H‐benzotriazole with zinc powder in sodium hydroxide solution and the 2‐hydroxy group of the compound was acetylated. Treatment of the acetyl compound with methyl Grignard reagent resulted in the methylation of the 5‐acetyl group to 2[2‐acetoxy‐5(2‐hydroxy‐2‐propyl)phenyl]2H‐benzotriazole which was then dehydrated with potassium hydrogen sulfate to the desired 2(2‐hydroxy‐5‐isopropenylphenyl)2H‐benzotriazole. This monomer did not homopolymerize, but was copolymerized readily with styrene, methyl methacrylate, and n‐butyl acrylate with azobisisobutyronitrile as the initiator. 2(2‐Acetoxy‐5‐acetylphenyl)2H‐benzotriazole was also reduced with sodium borohydride to form 2[2‐acetoxy‐5‐(1‐hydroxyethyl)phenyl]2H‐benzotriazole which was dehydrated and hydrolyzed to the known 2(2‐hydroxy‐5‐vinylphenyl)‐2H‐benzotriazole. This route provides a novel and simpler synthesis of 2(2‐hydroxy‐5‐vinylphenyl)2H‐benzotriazole.
Spectrophotometric studies of CT complexes of poly(N‐vinylhalogenocarbazole)s with 2,4,7‐trinitrofluorenone
Authors: Pielichowski Jan , Obrzut Jan 
Published: April 2003

AbstractThe effect of chlorine, bromine, and iodine at the 3 and 3,6 positions on a carbazole ring with thermodynamic properties, that is, enthalpy, entropy, and a stability constant of CT complex poly(N‐vinylcarbazole–2,4,7‐trinitrofluorenone), were studied in a temperature range of 268–323 K. The discussion of the results obtained, based on linear free‐energy relationships, stressed the advantageous influence of the halogen substituent in the carbazole ring on the properties of the poly(N‐vinylcarbazole)–2,4,7‐trinitrofluorenone complex.
On the interaction of triphenylmethyl salts with α‐methylstyrene
Authors: Velichkova R. , Panayotov I. M. , Doicheva J. , Heublein G. , Schutz H. , Adler P. , Spange S. , Wondraczek R. 
Published: April 2003

AbstractThe interaction of triphenylmethyl salts with α‐methylstyrene and 1,1‐diphenylethylene was investigated. With 1,1‐diphenylethylene at a monomer‐initiator ratio of 2 (room temperature), mainly 1,1,3‐triphenyl‐3‐methyl‐indane was isolated, whereas at a ratio of 100 (−10°C), the dimer 1,1,3,3‐tetraphenylbutene‐1 mainly formed. In both cases no addition of the trityl group was registered. In the interaction of α‐methylstyrene with Ph3C+SbCl at a monomer‐initiator ratio of 2(room temperature) a pure 1,3,3‐trimethyl‐1‐phenylindane was isolated and no addition of the trityl group to the double bond was recorded. The initiation reaction of α‐methylstyrene polymerization by trityl and chlorinated trityl salts was studied at temperatures from −20 to 0°C and different concentrations. The oligomers obtained with (pCI‐C6H4)3C+ were investigated by elemental analysis and fluorescence spectroscopy. The presence of Ph3CH in the reaction mixture was demonstrated by GLC and NMR spectra. The results obtained give evidence that the initiation of α‐methylstyrene polymerization involves hydride abstraction from the monomer.
Synthesis and characterization of thermoplastic polyesters and polyamides from sebacyl bisketene
Authors: Garner David P. 
Published: April 2003

AbstractSebacyl bisketene was generated in solution at −78°C. Copolymerization in solution at 0°C with the secondary diamines, piperazine and N,N′dimethyl‐1,6‐hexamethylenediamine, yielded the polyamides poly(1,4‐piperazylsebacyl) and poly[(methylimino)hexamethylene(methylimino)sebacyl], respectively. The polyamides were obtained in yields of 50–90%. The former had a glass transition temperature (Tg) at 30°C and a melting temperature at 165°C, whereas the latter had only a Tg at −15°C. The polymers were insoluble in the usual polyamide solvents. Copolymerization with the diol bisphenol A yielded poly(oxy‐1,4‐phenyleneisopropylidene‐1,4‐phenyleneoxysebacyl). The polyester was obtained in yields up to 99%. Gel permeation chromatography (GPC) determinations showed molecular weights up to 50,000 when acetone was the reaction solvent but only 12,000 when tetrahydrofuran (THF) was the reaction solvent; the Tg for the polyester varied with the molecular weight with a maximum at 15°C. Tensile properties were obtained for the polyesters with molecular weights greater than 35,000.
Poly(β‐pinenes) carrying one, two, or three functional end groups. I. The effect of reaction conditions on the polymerization of β‐pinene
Authors: Kennedy Joseph P. , Liao Tung‐Ping , Guhaniyogi Suhas , Chang Victor S. C. 
Published: April 2003

Abstractβ‐Pinene was polymerized with H2O/BCl3 (protic) and p‐dicumyl chloride and sym‐tricumyl chloride (nonprotic) inifer systems in CH2Cl2 or CH2Cl2/n‐C6H14 solvents from −10 to −70°C. The effect of solvent polarity, temperature, and monomer and inifer concentration on conversions and molecular weights was investigated. Low conversions and molecular weights, M̄n = 1300–2500, obtained under these conditions suggest rapid termination.
Synthesis of high‐molecular‐weight rodlike polyamides and block copolymers
Authors: Preston J. , Krigbaum W. R. , Kotek R. 
Published: April 2003

AbstractHigh‐molecular‐weight polyamides containing p‐benzamide units can be obtained by polycondensation of monomers having preformed amide linkages in N‐methylpyrrolidone with added CaCl2 and LiCl in the presence of pyridine and triphenylphosphite (the conditions used by Higashi et al.). For example, the polyterephthalamide of 4,4′‐diaminobenzanilide having ηinh = 5.4 was obtained. Similarly, polycondensation of p‐phenylenediamine with N,N′‐bis(p‐carboxyhenyl)terephalamide produced a polymer having ηinh = 5.15. These results constitute the first demonstration that the phosphorylation reaction can be used to prepare rodlike polymers containing p‐benzamide units of molecular weights adequate for commercial‐quality fibers. Polymerization of p‐aminobenzoic acid using either Yamazaki or Higashi conditions does not lead to a polyamide having a high inherent viscosity. Block copolyamides having rigid and semiflexible blocks were prepared by using both Yamazaki and Higashi conditions. Block copolymers composed of p‐ and m‐benzamide units, and having ηinh = 3.0–3.1, were synthesized by using a rigid prepolymer obtained by applying the Yamazaki reaction to a monomer containing a preformed amide linkage, 4‐N‐(4′‐aminobenzamido)‐benzoic acid. Use of monomers having preformed amide linkages with Higashi conditions afforded block copolymers having inherent viscosities of up to 4.75.
13C‐NMR of ABS in the solid state. Characterization and relaxation studies
Authors: Jelinski L. W. , Dumais J. J. , Watnick P. I. , Bass S. V. , Shepherd L. 
Published: April 2003

Abstract13C‐NMR spectra of bulk acrylonitrile‐butadiene‐styrene (ABS) resin are reported. The styrene‐co‐acrylonitrile (SAN) carbons can be observed selectively by using high‐power proton decoupling, cross polarization, and magic angle spinning (MAS). The polybutadiene (PBd) carbons can be observed selectively by using low‐power proton decoupling, with or without MAS. Methods and conditions for using 13C‐NMR to quantify the amount of PBd in solid ABS resins are developed. The 13C‐NMR results and results from iodine monochloride titrations for PBd content are in good agreement. Resonances of PBd in ABS in the solid state are assigned on the basis of triad sequences of cis, trans, and vinyl‐1,2 geometric isomers of butadiene. Computational methods are set forth for measuring directly from the 13C‐NMR spectra the percent of cis, trans, and vinyl‐1,2 isomers in PBd in the ABS resin. The NMR measurement of PBd microstructure appears to be preferable to infrared (IR) determinations. Relaxation parameters (T1 and NOE) are reported for PBd in bulk ABS as a function of temperature and are analyzed in terms of a distribution of rotational correlation times. These relaxation parameters are similar to those of nongrafted PBd and indicate that the local motions in grafted and nongrafted PBd are similar.
A comparison of the absolute reactivity of vinyl monomers. I. Kinetic studies on radical polymerization of vinyl monomers initiated by a Mn3+–diglycolic acid redox system
Authors: Elayaperumal P. , Balakrishnan T. , Santappa M. , Lenz R. W. 
Published: April 2003

AbstractThe kinetics of polymerization of acrylamide (AM), acrylic acid (AA), and acrylonitrile (AN) initiated by the redox system Mn3+–diglycolic acid (DGA) was studied. All three systems followed the same mechanism; namely, initiation by an organic free radical arising from the oxidation of diglycolic acid and termination by the interaction of polymer radicals with Mn3+ ion. The rate coefficients ki/k0 and kp/kt were related to monomer and polymer radical reactivity, respectively. An inverse relation between monomer and polymer radical reactivity was observed. Monomers with higher Q values gave higher ki/k0 values but lower kp/kt values. The e values of the monomers were important in determining the reactivities of monomers with nearly the same Q values.
Selective synthesis of structurally isomeric poly‐β‐ester and poly‐δ‐ester from β‐(2‐acetoxy‐ethyl)‐β‐propiolactone with Al and Zn catalysts
Authors: Araki Takeo , Hayase Shuzi , Nakamura Akira 
Published: April 2003

AbstractIt was found that structurally isomeric polymers were formed by the ring‐opening polymerization of β‐(2‐acetoxy ethyl)‐β‐propiolactone with (EtAlO)n and Et(ZnO)2ZnEt catalysts; that is, the Al catalyst catalyzed normal polymerization which led to poly‐β‐ester and the Zn catalyst formed isomerized poly‐β‐ester as the main product. The polymer structure was determined by nuclear magnetic resonance (NMR), T1‐value, thermal decomposition product, and (Tg). The NMR studies for the monomer–catalyst systems indicated that the Al catalyst interacted predominately with the lactone group, whereas the Zn catalyst interacted with the side‐chain ester group. These site‐selective interactions could be related to the difference in the stereoregulation by the two catalysts during the poly(β‐ester)‐forming polymerization process.
Metal chelates in vinyl polymerization: Bulk polymerization of acrylonitrile initiated by Cu(II)–imine complexes
Authors: Marjit D. N. , Kalpagam V. , Nandi U. S. 
Published: April 2003

AbstractThis article deals with the kinetics and mechanism of acrylonitrile (AN) polymerization initiated by Cu(II)–4‐anilino 3‐pentene 2‐one[Cu(II)ANIPO], Cu(II)–4‐p‐toluedeno 3‐pentene 2‐one [Cu(II)TPO], and Cu(II)–4‐p‐nitroanilino 3‐pentene 2‐one [Cu(II)NAPO] in bulk at 60°C. The polymerization is free radical in nature. The exponent of initiator(I) is ≃ 0.5. The initiation step is a complex formation between the chelate and monomer and subsequent decomposition of the intermediate complex giving rise to free radical and Cu(I). This is substantiated by ultraviolet (UV) and electron spin resonance (ESR) studies. The activation energies and kinetic and chain transfer constants have also been evaluated.
Kinetic study of the copolymerization of tetrahydrofuran‐3,3‐dimethyloxetane: Microstructure of the copolymers
Authors: Garrido L. , Guzmán J. , Riande E. , de Abajo J. 
Published: April 2003

AbstractThe cationic copolymerization of tetrahydrofuran‐(A)‐3,3‐dimethyloxetane (B) was studied at 0°C with BF3·OEt2‐epichlorhydrin and acetylhexafluoroantimonate as initiators. The values of the reactivity ratios, calculated by the Fineman–Ross and Kelen–Tüdos methods, were rA = 0.13, rB = 8.1 and rA = 0.13, rB = 7.9, respectively. These values are in satisfactory agreement with those obtained with a kinetic scheme in which depropagation reactions were considered. The product rArB was approximately equal to unity, which indicated an ideal random copolymerization. The copolymers were also analyzed by 1H‐NMR spectroscopy. Their spectra presented a doublet at 3.1 and 3.15 ppm that corresponded to the methylene protons of the dimethyloxetane units and allowed the determination of the probabilities P(AA), P(AB), and P(BB). Good agreement was found between the values calculated by spectroscopic methods and those obtained by using the classical probability theory of copolymerization.
Metal complexes with ligands—organic phosphites as polyolefin antioxidants. III. Kinetics and mechanism of the inhibiting action of individual stable Cu(i)‐complexes with phosphites
Authors: Pobedimskii D. G. , Kurashov V. I. , Kirpichnikov P. A. 
Published: April 2003

AbstractThe general features of behavior of kinetically labile complexes (metal phosphite) revealed earlier 1,2 provide the basis for the prediction of the activity of a new class of oxidation inhibitors. These are individual, stable metal complexes with organic phosphites as main ligands. The remarkable feature of these complexes, as shown as in this article on Cu(I) complexes, is the significant increase in the stoichiometric coefficient of inhibition f due to the suppression of the additional chain consumption of phosphite in the complex. The study of the initiated oxidation of styrene and solid isotactic polypropylene has proved that the phosphite complexes with Cu(I) ion are more effective than free, noncoordinated phosphites; quantitative characteristics of the inhibiting action of these complexes have been calculated. It is proved that termination of oxidation kinetic chains on the inhibitor molecules includes oxidation of coordinated phosphite without changing the oxidation degree of the central ion of metal. During inhibition of the oxidation of the substrate with mixtures of phosphite complexes of Cu(I) and phosphites (in styrene) or with aromatic amines (in polypropylene), the phenomenon of nonadditive strengthening (synergism) was discovered and the mechanism and kinetic regularities of synergism were revealed. This investigation of the phosphite complexes of the ions of Cu(I) presents new opportunities for controlled stabilization of polymers in uncontrolled conditions.
Phenazasiline‐containing polyamides and polyesters
Authors: Kondo Hitoshi , Sato Moriyuki , Yokoyama Masaaki 
Published: April 2003

AbstractA Phenazasiline ring was incorporated into a polymer backbone by polycondensation of 2,8‐dichloroformyl‐5,10‐dihydro‐5‐methyl‐10,10‐diphenylphenazasiline (V) with aromatic diamines or bisphenols, and phenazasiline‐containing polyamides and polyesters were obtained. The polyamides were prepared by low‐temperature solution polycondensation in N‐methyl‐2‐pyrrolidone (NMP) in the presence of lithium chloride. The polyesters were synthesized by interfacial polycondensation in a mixture of 1,2‐dichloroethane and aqueous alkali in the presence of tetrabutylammonium chloride as an accelerator. These reaction conditions gave the corresponding polymers with high viscosities. The phenazasiline‐containing polyamides exhibited good solubilities in polar aprotic solvents such as dimethylformamide, dimethylacetamide, and NMP, and also in m‐cresol, although the polyesters showed limited solubilities in organic solvents. Under nitrogen, the phenazasiline‐containing polyamides and polyesters showed little degradation below 400°C and had good heat resistance.
Characterization of poly(D,L‐lactic acid) by gel permeation chromatography
Authors: Van Dijk J. A. P. P. , Smit J. A. M. , Kohn F. E. , Feijen J. 
Published: April 2003

AbstractA number of samples of poly(D,L‐lactic acid) (PLA) with weight‐average molecular weights M̄w in the range 15,000–350,000 were prepared by a ring‐opening polymerization. The molecular weight distributions (MWDs) of these samples were determined by gel permeation chromatography (GPC). The method involves a universal calibration of the columns on the basis of polystyrene standards and a rapid iteration algorithm leading to the establishment of the Mark–Houwink relationship. In addition, osmometry and viscometry data are presented. The effect of hydrolytic degradation on the MWD of two PLA samples was studied by GPC.
The aging of living α‐methylstyryl oligomers. I. The kinetics of aging
Authors: Comyn J. , Glasse M. D. 
Published: April 2003

AbstractSolutions of living oligomers of α‐methylstyrene in THF age in two ways. In “decay” the UV‐visible absorption of the anion slowly disappears but in “transformation” the peak at 340 nm is replaced by a new one at 430 nm. Decay follows first‐order kinetics, while transformation depends upon a photochemical process and requires the presence of excess monomer. This monomer is consumed in a second‐order reaction to produce an intermediate from which new anions are formed.
The mechanisms of latex particle formation and growth in the emulsion polymerization of styrene using the surfactant sodium dodecyl sulfate
Authors: Lichti Gottfried , Gilbert Robert G. , Napper Donald H. 
Published: April 2003

AbstractA new method is presented that provides experimental information which is qualitatively and quantitatively sensitive to assumptions made as to the mechanisms of free radical entry and of latex particle formation in emulsion polymerization systems. The method consists of (1) obtaining (by electron microscopy) the full particle‐size distributions (PSDs) at several different times soon after the cessation of latex particle nucleation, (2) using these PSDs to determine the volume dependences of the various rate coefficients governing particle growth by fitting the data to the appropriate evolution equations, and (3) employing these empirical rate coefficients to find that time dependence of the nucleation rate which fits the early‐time PSD (again using the evolution equations). This method is quite sensitive to mechanistic assumptions: for example, one is able to determine whether or not the nucleation rate is an increasing or decreasing function of time. The technique is applied to a styrene nucleation system employing sodium dodecyl sulfate as surfactant at well above the critical micelle conventration. The data cannot be fitted even qualitatively by a simple one‐step nucleation mechanis, whether it involes micellar entry or homogeneous nucleation. It is found, on the other hand, that the results can be accurately fitted by assuming that coagulation events between primary colloidal particles, perhaps formed by homogeneous nucleation, dominate both the nucleation process and the entry of free radicals into mature latex particles. In addition, the data indicate that the rate of free radical entry into the latex particles decreases with increasing particle size, at least for particles of unswollen radius less than ca. 40 nm.
N‐chlorination of nylon fabric and polyurea‐6
Authors: Koutinas A. A. , Demertzis P. G. 
Published: April 2003

AbstractIn this article the preparation of N‐chloro Nylon fabric, with Nylon‐66 as weft and Nylon‐6 as warp is described. The N‐chlorination of this fabric was achieved by using tertiary butyl hypochlorite in carbon tetrachloride as the chlorinating agent. The percentage of N‐chlorinated amide groups in the fabric obtained was 30.6. Methods of preparation of N‐chloro polyurea‐6 are also reported. The N‐chlorination of these compounds was acheived in a heterogenious medium. N‐chloro polyurea‐6 was prepared by reacting it with tert‐butyl hypochlorite. In Polyuera‐6 the percentage of N‐chlorination was equal to 100. The 100% N‐chlorinated polyurea‐6 did not giveNHbands at 3.05 and 6.50 μ in the infrared spectra.