bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multifunctional polycondensation and gelation: A kinetic approach
Authors: Stafford J. W. 
Published: April 2003

AbstractThe size distributions of a number of multifunctional polycondensation systems have been derived from kinetic reaction schemes. The size distribution obtained for a self‐condensing multifunctional monomer is equivalent to the classic distributions derived by Flory and Stockmayer, and distribution expressions for mixtures of monomers of different functionalities have also been obtained. Molecular weight expressions have also been calculated for the same systems. In some case, these are exactly the same as those calculated by others, and in some cases the expressions differ from those by others only in the kind of average used for the mean functionality of the mixed monomer systems, but in other cases, the differences are more marked. In gelation, comparison with a number of actual gel point data shows that although the critical point Pcrit for gel formation calculated from Pcrit = 2/f was generally closer to actually measured gel points than when Pcrit = 1(f –1), neither method of calculating Pcrit can be regarded as completely reliable. The cause of the divergence from theory is interpreted in terms of intramolcular reaction, and the nature of this type of reaction is discussed and comparisons made with other gelling systems.
The nonaqueous, potentiometric titration of free hydrochloric acid in chloride‐containing polymers
Authors: Reigler Paul F. , Larson Jeff , Bowman Lyle 
Published: April 2003

AbstractThe thermal and/or catalytic degradation of chloride‐containing polymers causes dehydrohalogenation which produces hydrochloric acid. A nonaqueous method has been developed for the termination of hydrochloric acid. The sample is dissolved in tetrahydrofuran and titrated potentiometrically with a standard tetrabutylammonium hydroxide solution in a 7.5% (V/V) aqueous tetrahydrofuran solution with a combination glass‐calomel electrode. The method has a relative precision of ±3.7% at the 95% confidence limit and a sensitivity of 25 ppm HCI.
Functional polymers. XIV. Grafting of 2(2‐hydroxy‐5‐vinylphenyl)2H‐benzotriazole onto polymers with aliphatic groups
Authors: Pradellok Witold , Vogl Otto , Gupta Amitava 
Published: April 2003

AbstractSuccessful grafting of 2(2‐hydroxy‐5‐vinylphenyl)2H‐benzotriazole onto saturated aliphatic CH groups of polymers has been accomplished. When the grafting reaction was carried out in chlorobenzene at 150–160°C with di‐tertiary butylperoxide as the grafting initiator, grafts as high as 20–30% at grafting efficiencies of 50 and 80% have readily been obtained. It was very important to carry out the grafting reaction in tubes sealed under high vacuum since trace amounts of oxygen cause complete inhibition of the grafting reaction by the phenolic monomer. Grafting reactions were carried out on a variety of different polymers including atactic polypropylene, ethylene/vinyl acetate copolymer, poly(methyl methacrylate), poly(butyl acrylate), and polycarbonate.
Methylene malonamide. I. Synthesis and reactivity of the monomer
Authors: Jasne S. J. , Haas H. C. , Moreau R. D. , MacDonald R. L. 
Published: April 2003

AbstractThe first confirmed synthesis of methylene malonamide (MeMal) is reported. This monomer was prepared by the thermal elimination or fluoride‐ion‐initiated elimination of trimethylsilyl chloride from α‐chloro‐α(trimethylsilyl‐2‐methyl) malonamide. Spectral data for the monomer are given. MeMal has been shown to be unstable in a variety of protic organic solvents, including water and alcohols, thus giving the appropriate (α‐methyl) substituted malonamides. MeMal is stable in most aprotic solvents.
Polymerization of acrylonitrile. Kinetics of the reaction initiated by the Ce(IV)/thioacetamide redox system
Authors: Samal Rajani K. , Nayak M. C. , Panda G. , Suryanarayana G. V. , Das D. P. 
Published: April 2003

AbstractVinyl polymerization of acrylonitrile initiated by the Ce(IV)/thioacetamide redox system has been investigated in aqueous sulfuric acid in the temperature range of 10–20°C. The rate of polymerization (Rp) and the rate of Ce(IV) disappearance (−RCe) were measured. The effect of certain water‐soluble organic solvents, added electrolytes, and aromatic and heterocyclic organic nitrogen compounds on the rate of polymerization has been investigated. Depending on the experimental results, we have suggested a suitable reaction scheme for the system which involves the production of initiating radicals from the oxidation of thioacetamide (TAm) by ceric ion and the termination of the polymer chain by metal ions.
Kinetics and mechanism of HCN evolution from nylon 66 and design of apparatus
Authors: Jellinek H. H. G. , Dunkle S. R. 
Published: April 2003

AbstractThe evolution of HCN from the oxidation of nylon 66 has been studied in three apparatuses of different design (all based on stream flow) over a temperature range from 390 to 700°C. Although the numerical values for rate constants (diffusion controlled) and energies of activation differ, the same mechanism is deduced from the results of the three designs. It is concluded that a simple horizontal tube in a furnace is the most efficient apparatus as far as sweeping out volatile products is concerned. The mechanism of thermal oxidative degradation has been evaluated in detail. It is shown that mechanisms where the first reaction step is not the slowest or the slowest one of first or second order all fit the experimental results. However, it is concluded that the mechanism where the first step is first order and the slowest one is the most likely one. The respective parameters have been evaluated for the results obtained from the horizontal tube apparatus.
Reduction of electroactive polymers via polyelectron transfer processes at solid electrodes
Authors: Funt B. Lionel , Hsu Li‐Chien , Hoang P. M. , Martenot J. P. 
Published: April 2003

AbstractThe reduction of an electroactive polymer at an electrode involves the transfer of a large number of electrons to a single molecule. A quantitative study of this process indicates whether the system behaves ideally. The electron transfer process in polyvinylbenzophenone and in polyvinylbenzophenone‐co‐styrene in N,N‐dimethylformamide solution was investigated by voltammetry at a rotating disk electrode. It is concluded that benzophenone (BP) groups attached to the polymer backbone are noninteracting electroactive centers and that every BP group is reducible at the electrode. The relationship between limiting current and molecular weight was examined quantitatively for a series of polymers of low dispersity with molecular weights ranging up to 300,000, and with a controlled, varied content of electroactive groups. The diffusion coefficient was determined as a function of molecular weight from the electrochemical data, and was found to be in good agreement with the theoretical model based on transport properties. The dependence of the diffusion coefficient on concentration of polymer and on temperature were investigated and activation energies determined.
Regular copolymers derived from bis(2‐oxazolines). II. Synthesis of polyamides and polyamide‐imides containing oxyethylene linkages
Authors: Chau Nguyen , Muramatsu Taeko , Iwakura Yoshio 
Published: April 2003

AbstractNew diamines containing amide and oxyethylene linkages were prepared by reduction of the corresponding dinitro compounds which were obtained by the reaction of p‐nitrophenol with arylenebis(2‐oxazolines) in dimethylformamide at 130°C. Moderate‐ to high‐molecular‐weight polyamides and polyamide‐imides containing oxyethylene linkages were prepared by the polycondensation of the diamines with diacid chlorides and tetracarboxylic acid dianhydrides, respectively. The polyamides were soluble in dimethylacetamide containing 5% of lithium chloride and dichloroacetic acid, while the polyamide‐imides dissolved only moderately in the latter solvent. Thermogravimetric analysis showed that thermo‐oxidative decomposition started at 310–330°C and at around 325°C for the polyamides and polyamide‐imides, respectively.
Photocrosslinking and photografting of vinyl polymers using poly(styrene‐co‐p‐vinylbenzophenone‐p′‐tert‐butyl perbenzoate) as a comonomer
Authors: Gupta I. , Gupta Satyendra N. , Neckers Douglas C. 
Published: April 2003

AbstractStyrene has been copolymerized with low percentages of p‐vinylbenzophenone‐p′‐tert‐butyl perbenzoate (VBPE). The resulting copolymer has been used to make graft copolymer with methyl methacrylate using UV irradiation (366 nm). The grafting efficiency has been observed to increase with time of irradiation and percentage of VBPE in the copolymer. The copolymer has also been observed to crosslink efficiently with photochemical irradiation.
Nylon 6–polyisobutylene sequential copolymers. II. Synthesis, characterization, and morphology of di‐, tri‐, and radial block copolymers
Authors: Wondraczek Reinhard H. , Kennedy Joseph P. 
Published: April 2003

AbstractNylon 6–PIB diblock, triblock, and tristar radial block copolymers have been synthesized from telechelic hydroxyl‐terminated polyisobutylene, PIB(OH)n (n = 1,2,3), by conversion of this prepolymer with hexamethylene diisocyanate (HMDI), toluene diisocyanate (TDI), N‐chlorocarbonyl diisocyanate (NCCI), and oxalyl chloride (OxCl) and using the resulting materials as macroactivators for anionic caprolactam polymerization. Prepolymers with molecular weights from 6000 to 38,000 have been employed. Derivatization with NCCI and subsequent anionic caprolactam polymerization gave highest yields and blocking efficiencies. The block copolymers have been characterized by molecular weight and composition. In addition to the expected Tg and Tm characteristics of long PIB and nylon 6 segments, DSC studies showed an intermediate glass transition at ca. −20°C. Transmission electron microscopy of di‐, tri‐, and radial blocks show increasing segregation and orientation of rubbery/crystalline domains. Tensile strengths and elongations of the block copolymers range from 16.5 to 41 MPa and 15 to 30%, respectively, and stress‐strain diagrams show the effect of block architecture on these properties.
Cu (DPM)2–initiated vinyl polymerization
Authors: Chatterji Prabha R. , Nandi Uma S. 
Published: April 2003

AbstractThe behavior of cupric dipivaloylmethide in vinyl polymerization systems was investigated with a view to understanding the mechanism of polymerization initiation. Results of polymerization reactions together with spectral investigation data are presented. Polymerization in the presence of the chelate proceeds through a free‐radical process. The corresponding kinetic and transfer constants and activation energy values suggest a normal propagation step. With the help of spectral data an attempt is made to suggest a plausible mechanism of initiation.
Reactivity ratios of ethyl acrylate, n‐butyl methacrylate copolymer system by 1H‐NMR
Authors: Pitchumani S. , Reddy C. Rami , Rajadurai S. 
Published: April 2003

AbstractEthyl acrylate (EA) and n‐butyl methacrylate (n‐BMA) copolymers were prepared in solution and the composition of the copolymer samples was estimated by 1H‐NMR spectroscopic techniques. Because the characteristic signals, which vary with the composition of the copolymer, were absent, the ratio of intensities of down‐field protons to that of the total protons was used for the estimation of copolymer composition. Reactivity ratios were calculated from these values by using the Kelen‐Tudos differential linear equation.
Synthesis and thermal characteristics of bisimides. I
Authors: Varma Indra K. , Fohlen George M. , Parker John A. 
Published: April 2003

AbstractTen structurally different bisimide resins were prepared by reacting maleic anhydride/citraconic anhydride and benzophenone tetracarboxylic dianhydride with aromatic diamines and fused aromatic structures or heterocyclic groups. The amines included were 1,5‐diaminonaphthalene, 2,5‐bis(p‐aminophenyl)1,3,4‐oxadiazole, 3,3‐bis(p‐aminophenyl)phthalide, 9,9‐bis(p‐aminophenyl)fluorene. and 10,10‐bis(p‐aminophenyl)anthrone. These monomers were characterized by infrared (IR). 1H‐NMR, mass spectroscopy, and elemental analysis. Thermal polymerization of these monomers was investigated by differential scanning calorimetry. Broad exothermic peaks were observed for a temperature range of 225–380°C. Temperature of exothermic peak position was influenced by the presence of substituents at the olefinic bond, and in biscitraconimides it was 40–50°C lower than in the corresponding bismaleimides. Anaerobic char yields of cured bisimide resins ranged from 44 to 64%. Oxadiazole‐containing bisimides had low thermal stability. Increase in formula weight between the imide groups did not influence the char yields in a systematic manner. Graphite cloth laminates with two of these bisimide resins were fabricated and tested for a number of physical properties. Their limiting oxygen index was 70–72%.
Preparation of phosphorus‐containing polymers. XXVII. Polyester‐imides that contain phenoxaphosphine rings
Authors: Sato Moriyuki , Kondo Hitoshi , Yokoyama Masaaki 
Published: April 2003

AbstractNew phenoxaphosphine‐containing polyester‐imides were prepared by the interfacial polycondensation of a dichloroformyl‐phenoxaphosphine derivative containing a preformed imide ring with five bisphenols. The polymerizations, which were carried out in a chloroform‐aqueous sodium hydroxide mixture, afforded polyester‐imides with reduced viscosities of 0.60–1.55 dL/g in 61–95% yields. The preformed imide ring did not undergo hydrolysis under the polymerization conditions. Several of the polymers were soluble in chloroform and could be cast into flexible and transparent films. The phenoxaphosphine‐containing polyester‐imides have good thermal properties, exhibiting little decomposition below 400°C. They appear to be more thermally stable than phenoxaphosphine‐containing polyesters, but are not as thermally stable as the corresponding polyimides and polyamide‐imides. The order of thermal stability for phenoxaphosphine‐containing polymers in air is polyimide ≳ polybenzoxazole > polyamide‐imide ≳ polybenzimidazole > polyester‐imide > poly‐1,3,4‐oxadiazole ≳ polyamide > polyester. The polyester‐imides exhibited self‐extinguishing behavior.
Syntheses of 1,6‐anhydro‐2,3,4‐tri‐0‐benzyl‐β‐D‐altropyranose and of 1,6‐anhydro‐2‐0‐benzyl‐3,4‐0‐isopropylidene‐β‐D‐galactopyranose and their ring‐opening copolymerizations with 1,6‐anhydro‐2,3,4‐tri‐0‐benzyl (or p‐methylbenzyl)‐β‐D‐glucopyranose
Authors: Uryu Toshiyuki , Hatanaka Kenichi , Yoshinari Kaoru , Matsuzaki Kei 
Published: April 2003

AbstractThe cationic ring‐opening polymerization of 1,6‐anhydro‐2,3,4‐tri‐0‐benzyl‐β‐D‐altropyranose (TBLAT, M2) failed to give the fourth stereoregular 1,6‐α‐linked polysaccharide because of its very low homopolymerizability. However, the 1,6‐anhydro‐altrose monomer was found to copolymerize with 1,6‐anhydro‐2,3,4‐tri‐0‐(p‐methylbenzyl)‐β‐D‐glucopyranose (LGTXE, M1) with PF5 as catalyst at low temperature, giving highly stereoregular copolymers. The monomer reactivity ratios calculated by Kelen‐Tüdös method were r1 = 1.52 and r2 = 0.06. The differences in the reactivity between TBLAT monomer and other 1,6‐anhydro sugar derivatives are discussed. Moreover, 1,6‐anhy‐dro‐2‐0‐benzyl‐3,4‐0‐isopropylidene‐β‐D‐galactopyranose (ABIGA, M4), which showed no homopolymerizability under various conditions, was also copolymerized with 1,6‐anhydro‐2,3,4‐tri‐0‐benzyl‐β‐D‐glucopyranose (LGTBE, M3) at low temperature. The monomer reactivity ratios of r3 = 2.2 and r4 = 0.0 indicate that in the copolymers every galactose unit distributed as a single unit through the main chain. The cause for the lower polymerizability of ABIGA is discussed. Hydrolysis of the copolymer with trifluoroacetic acid gave a copolymer in which only galactose units contained free hydroxyl groups, which were then methylated by methyl iodide. Stereoregular 1,6‐α‐linked galactoglucan composed of free sugar units was prepared by debenzylation of the ABIGA‐LGTBE copolymer followed by hydrolysis.
X‐ray structure determination of new monomers to establish their polymerizability: Copolymerization of two tetrasubstituted electrophilic olefins with electron‐rich styrenes giving polymers with an average 1.25 functional groups per chain carbon atom
Authors: Hall H. K. , Reineke K. E. , Ried J. H. , Sentman R. C. , Miller D. 
Published: April 2003

AbstractX‐Ray crystal structure determination for two tetrasubstituted electrophilic olefins, tetramethyl ethylenetetracarboxylate TMET and dimethyl dicyanofumarate DDCF, revealed two fundamentally different molecular structures. TMET is a nonplanar molecule that possesses two opposite ester groups planar and the others above and below the molecular plane. In contrast, DDCF is a molecule for which both ester groups lie in the plane of the double bond and nitrile groups. DDCF underwent thermal spontaneous copolymerization with electron‐rich styrenes to give 1:1 alternating copolymers in moderate yields and molecular weights. These copolymers, which result from the first copolymerizations of a tetrasubstituted olefin, possess an average functionality of 1.25 per chain carbon atom. Polymerization is made possible by low steric hindrance and the high delocalization in the propagating radical. The yields were limited by competing cycloaddition reaction. The corresponding diethyl ester also copolymerized, but not so well. Neither electrophilic olefin homopolymerized under γ‐irradiation. TMET did not copolymerize at all when treated under identical conditions.
Nematogenic block copolymers via the yamazaki reaction
Authors: Asrar J. , Preston J. , Ciferri A. , Krigbaum W. R. 
Published: April 2003

AbstractA novel extension of the Yamazaki reaction is used to prepare block copolymers having rigid blocks of poly‐(p‐benzamide) (PBA) and semiflexible blocks of polyamide‐hydrazide. A PBA prepolymer having M ≅ 10,000 was synthesized by the usual Yamazaki reaction using triphenylphosphite. As previously reported, higher‐molecular‐weight PBA could be obtained using 4‐N‐(4′‐aminobenzamido)benzoic acid containing a preformed amide linkage. Addition of p‐aminobenzhydrazide and terephthalic acid then led to formation of the polyamide‐hydrazide blocks using as the active reactant the diphenylphosphite formed as a by‐product in the first polymerization. Evidence that a block copolymer is produced includes an increase in inherent viscosity during the second step, differences in the solubility of the copolymer compared to the homopolymers, and comparison of the phase diagram of the block copolymer in N‐methylpyrrolidone having 4% added LiCl with those of a random copolymer, and of mixtures of the two homopolymers. The critical concentration required to form a nematic phase in solutions of the block copolymers is correlated with the length (or axial ratio) of the rigid block, and with its proportion in the copolymer.
New processable polyaromatic ether‐keto‐sulfones as colorless, clear film‐forming materials
Authors: Lee Byung H. , Marvel C. S. 
Published: April 2003

AbstractNew processable polyaromatic ether‐keto‐sulfones were prepared from 4,4′‐diphenoxydiphenyl sulfone, terephthaloyl chloride, isophthaloyl chloride, and bis‐p‐carboxyphenylacetylene dichloride (IV) in a Friedel‐Crafts‐type polymerization. The white polymers obtained form colorless, transparent, strong films and can be cast into a glass‐fiber laminate. One polymer was prepared which incorporated biphenylene‐2,6‐dicarboxylic acid dichloride as crosslinking sites; this heat‐cured polymer was completely insoluble in sulfuric acid.
Determination of rate constants of benzoyl peroxide and azobisisobutyronitrile dissociation via polymerization kinetics
Authors: Ng S. C. , Chee K. K. 
Published: April 2003

AbstractA linear expression is derived from Tobolsky's equation related to the dead‐end polymerization method to determine the rate constant for the initiator dissociation. This novel graphical method applies remarkably well to the kinetic data collected by dilatometry from the polymerization of methyl methacrylate initiated by 2,2′‐azobisisobutyronitrile and benzoyl peroxide in toluene at 60°C. Results obtained for these two initiators are consistent with those published in the literature. Applicability of the method is confined to at least 5% and at most 13% decomposition of initiator. However, these limiting values are sensitive to the experimental techniques employed. The effects of induced decomposition of benzoyl peroxide and thermal polymerization of methyl methacrylate are shown to be negligible in the present investigations.
Nonionic polymer surfactants
Authors: Landoll L. M. 
Published: April 2003

AbstractNonionic water‐soluble polymeric surfactants have been prepared by addition of long‐chain n‐alkyl epoxides to nonionic cellulose ethers. The polymers exhibit properties which can be explained by interchain association. The relationship between hydrocarbon‐modifier carbon number and the onset of association follows a linear relation analogous to those observed for monomeric nonionic surfactants.
Acid‐base properties of solid polyelectrolytes: Dissociation of cellulosic polyanions
Authors: Shet R. T. , Atanu E. Y. 
Published: April 2003

AbstractThe potentiometric titration behavior of nitrogen dioxide and periodate‐chlorite oxycellulose has been studied both in the presence and absence of sodium chloride. The apparent pK values in general increase with increasing degree of dissociation, but the reverse is true for periodate‐chlorite oxycellulose in the absence of added salt. This behavior is interpreted in terms of electrostatic and hydrogen bonding interaction of carboxyl groups. The Gibbs–Donnan theory of polyaid dissociation was applied to calculate the intrinsic dissociation constant pK′0. Assuming a model having a uniform potential distributin throughout the fiber, good agreement with the expected value of 3.24 was found (compared to pK′0 = 3.25 calculated for periodate‐chlorite oxycellulose).
Emulsion polymerization of styrene: Nucleation studies with nonionic emulsifier
Authors: Piirma Irja , Chang Manchium 
Published: April 2003

AbstractThe nucleation mechanism of styrene emulsion polymerization in the presence of the nonionic surfactant Emulphogene BC‐840 was investigated. It was found that the conversion‐time curves of this system show two rate regions. The change in rate occurs at ca. 40% conversion. Second‐stage nucleation leads to a faster rate and consequently to a bimodally dispersed latex. The particle size distribution is relatively narrow before 40% conversion. The bimodally dispersed latex shows a bimodal molecular weight distribution in gel permeation chromatography and the results from fractional “creaming” of the latex indicate that the small‐size particles contain the higher‐molecular‐weight polymer.
A study of the spectra of diacetylenic phospholipid polymers in solvents and dispersions
Authors: Pons Miquel , Johnston David Samuel , Chapman Dennis 
Published: April 2003

AbstractPhospholipids, of which phosphoryl cholines are a specific example, are the most common lipid components of cell membranes. Synthetic acetylenic phospholipids form closed model membranes, vesicles, or liposomes when dispersed in water. Below the temperature at which lipid chain crystallization occurs irradiation of vesicles causes polymerization of the diacetylene groups. In chloroform solution the spectrum of the polymer is independent of temperature. However, when the polymer is dissolved in methanol or dispersed in water with another lipid spectral changes occur. As solution or dispersion is cooled a second peak appears on the long wavelength side of the original absorption and gradually increases in intensity. Evidence that suggests that this peak is associated with aggregated polymer chains is presented. It appears that within the aggregates exciton coupling splits the excited state into two new levels and only transitions to the level of lowest energy are allowed.