bluuebunny/crossref_metadata_2025_split huggingface dataset:
Penetration of plasma surface modification. II. CF4 and C2F4 low‐temperature cascade arc torch
Authors: Krentsel E. , Fusselman S. , Yasuda H. , Yasuda T. , Miyama M. 
Published: April 2003

AbstractThe depth of surface modification by low‐temperature cascade arc torch is investigated. A stack of 10 sheets of nonwoven fabrics of polyester fibers is exposed to a low‐temperature cascade arc torch containing CF4 or C2F4, and the fluorination effect is examined by ESCA. It is shown that interaction of chemically reactive species, created in a low‐temperature cascade arc torch, with the surface is not limited to the surface contacted by the torch (flame). The results indicate that the fluorination effect is observed on surfaces which are shadowed from the torch by overlying fibers. The highest degree of fluorination is found on the second layer, rather than on the first layer which the torch contacts directly. No significant differences in the trends of penetration of CF4 and C2F4 treatment through porous samples are observed. However, ESCA data show principal differences in chemical structures of the surfaces treated with CF4 (nonpolymer‐forming gas) and C2F4 (polymer‐forming gas). These results indicate that chemically reactive species induced by the excited species of argon rather than primary species created by the ionization process seem to play predominant roles in the surface treatment as well as the low‐temperature cascade arc torch polymerization of perfluorinated compounds. © 1994 John Wiley & Sons, Inc.
Effect of polarity of the medium on the stereospecific polymerization of propylene by ansa‐zirconocene catalyst
Authors: Vizzini James C. , Chien James C. W. , Babu Gaddam N. , Newmark Richard A. 
Published: April 2003

AbstractPropylene was polymerized with rac‐ethylene‐bis (1‐η5‐indenyl)dichlorozirconium/methylaluminoxane in solvents of different polarity. The poly (propylene) formed was separated by solvent extraction; 13C‐NMR and DSC measurements were made on the polymer fractions. The poly(propylene) in each solvent fraction has its characteristic molecular weight steric pentad distributions, melting transition temperature, and enthalpy for fusion irrespective of the polymerization medium. The results suggest that the medium dielectric constant does not affect the polymerization rate or the intrinsic stereoselectivity, propagation and chain transfer rates a given catalytic species but can alter the occurrence of steric insertion errors through shifting of distributions of the propagating species producing poly(propylenes) of different stereoregularities. © 1994 John Wiley & Sons, Inc.
Determination of the reactivity ratios of methyl acrylate with the vinyl acetate, vinyl 2,2‐dimethyl‐propanoate, and vinyl 2‐ethylhexanoate
Authors: Noël Lilian F. J. , Van Altveer Jeroen L. , Timmermans Menno D. F. , German Anton L. 
Published: April 2003

AbstractThe course of composition drift in copolymerization reactions is determined by reactivity ratios of the contributing monomers. Since polymer properties are directly correlated with the resulting chemical composition distribution, reactivity ratios are of paramount importance. Furthermore, obtaining correct reactivity ratios is a prerequisite for good model predictions. For vinyl acetate (VAc), vinyl 2,2‐dimethyl‐propanoate also known as vinyl pivalate (VPV), and vinyl 2‐ethylhexanoate (V2EH), the reactivity ratios with methyl acrylate (MA) have been determined by means of low conversion bulk polymerization. The mol fraction of MA in the resulting copolymer was determined by 1H‐NMR. Nonlinear optimization on the thus‐obtained monomer feed–copolymer composition data resulted in the following sets of reactivity ratios: rMA = 6.9 ± 1.4 and rVAc = 0.013 ± 0.02; rMA = 5.5 ± 1.2 and rVPV = 0.017 ± 0.035; rMA = 6.9 ± 2.7 and rV2EH = 0.093 ± 0.23. As a result of the similar and overlapping reactivity data of the three methyl acrylate–vinyl ester monomer systems, for practical puposes these data can be described with one set of reactivity data. Nonlinear optimization of all monomer feed–copolymer composition data together resulted in rMA = 6.1 ± 0.6 and rVEst = 0.0087 ± 0.023. © 1994 John Wiley & Sons, Inc.
Emulsion copolymerization of tetrafluoroethylene and propylene with redox system containing tert‐butylperbenzoate. I. Polymerization conditions and components
Authors: Kostov G. K. , Chr. Petrov P. 
Published: April 2003

AbstractEmulsion polymerization of tetrafluoroethylene and propylene with ammonium perfluorooctanoate, initiated by a redox system containing tert‐butylperbenzoate (TBPB) was carried out. The effect of the components of the redox system Is (TBPB, FeSO4.7H2O, ethylenediamine tetraacetic acid (EDTA), and CH2(OH)SO2Na.2H2O) on the polymerization rate (R) and molecular weight ($\[ \bar M_n \] $) was studied. Among redox system components, Fe2+ concentration exerts the most significant effect (by power of 0.54) on the polymerization rate. It was found that R ∝ [Is]0.2–0.54 and Mn ∝ [Is]0.0–0.1 and polymerization reaction scheme was suggested for the action of the initiating system. The influence of the copolymerization conditions (pressure, temperature, stirring speed, and pH) is also discussed. The apparent activation energy of the reaction was found to be 46.0 kJ/mol. © 1994 John Wiley & Sons, Inc.
Emulsion copolymerization of tetrafluoroethylene and propylene with redox system containing tert‐butylperbenzoate. II. Polymerization mechanism
Authors: Chr. Petrov P. , Kostov G. K. 
Published: April 2003

AbstractEmulsion copolymerization of tetrafluoroethylene (TFE) and propylene (P) initiated by trilon‐rongalite catalytic system containing tert‐C4H9OH, initial monomer mixture, emulsifier (C7F15COONH4) concentration, and monomer mixture/water ratio on the polymerization rate (R) and molecular weight (M̄n
) was investigated. Both R and M̄n increased considerably with TFE content in monomer mixture up to 75 mol %. Alternating rubber‐like copolymers in a wide range of initial monomer mixture (from 55–85 mol %) were obtained. The reactivity ratio was found to be rTFE = 0.005 ± 0.04 and rp = 0.17 ± 0.07. Above the critical miscelle concentration, the effects of the initiating system Is and emulsifier Cs on R and M̄n were found to obey the following relations:

according to which emulsion copolymerization proceeds by the I case of Smith‐Ewart theory. Polymerization mechanism of the reaction studied was suggested. The copolymerization is mainly terminated by degradative chain transfer of the propagating radicals to propylene. © 1994 John Wiley & Sons, Inc.
Spectroscopic evidences for grafting of N‐vinyl carbazole on cellulose‐acetate film
Authors: Basu Samita , Bhattacharyya Amit , Mondal Parikshit Ch. , Bhattacharyya Sudhindra Nath 
Published: April 2003

AbstractN‐vinyl carbazole (VCZ) was grafted on cellulose acetate film using simultaneous cobalt‐60‐γ ray irradiation grafting technique. Absorption, excitation, and emission spectral studies on the grafted film were carried out to ascertain the grafting of VCZ on the polymer matrix. Laser‐flash photolysis studies with the solution of grafted film indicate the opening of the double bond of VCZ, which leads to the grafting. On the basis of the observed results, the mechanism of grafting in the system was proposed. © 1994 John Wiley & Sons, Inc.
Iodine binding by amylopectin and stability of the amylopectin–iodine complex
Authors: Davis Heather , Skrzypek Walter , Khan Arshad 
Published: April 2003

AbstractThe iodine binding capacity (IBC) of amylopectin (AP, from potatoes) is determined to be around 0.38% (w/w) of the total AP in the solution. The mass of iodine bound comprises about 13.6% of the mass of AP involved with the complex, suggesting that with every four iodine atoms bound there are 23 anhydroglucose residues (AGU). Since our previous study indicates that four iodine atoms within the helix of 11 AGUs form a chromophore unit in the API complex, only 48% of the AGUs (11 out of 23) in the AP molecule are directly involved with the iodine. The heat of reaction for the API complex formation is determined to be around −47 kJ/mol of I–I units bound and is significantly lower in magnitude than that of the amylose‐iodine (AI) complex [Biopolymers, 31, 57 (1991)]. A possible mechanism has been proposed for the formation of AI and API complexes with fixed compositions. © 1994 John Wiley & Sons, Inc.
Analysis of PPMMA films from oxygen plasma using X‐ray photoelectron spectroscopy
Authors: Kuruvilla Beena Annie , Zambre Madhukar , Gosavi Suresh , Gorwadkar Sucheta , Datta A. , Gangal S. A. , Kulkarni S. K. 
Published: April 2003

AbstractPlasma polymerized methyl methacrylate (PPMMA) films have been synthesised on silicon substrates in RF glow discharge using oxygen plasma. The electron beam delineation sensitivity of the PPMMA films has been studied systematically by varying oxygen and monomer flow rates. X‐ray photoelectron spectroscopy (XPS) analysis clearly illustrates how C/O ratio in the films determines the properties of PPMMA films as electron beam resist. © 1994 John Wiley & Sons, Inc.
Characterization of chloroprene and maleic anhydride copolymer by 13C‐NMR spectroscopy and pyrolysis GC/MS
Authors: Cho Won‐Jei , Choi Chi‐Hoon , Ha Chang‐Sik 
Published: April 2003

AbstractThe radical copolymerizations of chloroprene (CP) and maleic anhydride (MAH) were carried out with AIBN in 1,4‐dioxane at 60°C. The monomer reactivity ratios were estimated as r1 (CP) = 0.38 and r2 (MAH) = 0.07. Microstructures in the copolymer of chloroprene (CP) and maleic anhydride (MAH) were investigated by 75.4 MHz 13C‐and 300 MHz 1H‐NMR spectroscopies. Resonances were assigned to the monomer sequence dyads CC, CM, and MC (C = chloroprene, M = maleic anhydride). Well resolved fine structure in the 13C‐NMR spectra showed that 1,2‐ and 3,4‐structural chloroprene units were negligible in the copolymer. The pyrolysis characterization of the copolymer was also investigated by the pyrolysis gas chromatography mass spectrometry (GC/MS). The fragments of CP and MAH monomers and CP‐MAH hybrid dimer, CO, and CO2 were identified after pyrolysis of the copolymer. © 1994 John Wiley & Sons, Inc.
Hydrocarbon dispersions of acrylic microspheres with polar surface functionality
Authors: Lee Ki‐Change , Winnik Mitchell A. , Jao Tze‐Chi 
Published: April 2003

AbstractSubmicron and micron sized particles containing a crosslinked core and a polar shell were prepared by 3‐stage nonaqueous dispersion [NAD] polymerization in an aliphatic hydrocarbon medium. When a poly (12‐hydroxystearic acid) [PHS] comb stabilizer was used in all three stages, the particles produced were spherical, submicron in size, and had a relatively broad size distribution. If the monomer mixture in the third stage contained relatively large amounts of butyl acrylate, stable dispersions of sponge‐like aggregates, 3–5 μm in size, were obtained. When butyl rubber was employed as a stabilizer precursor in the seed formation step, the shape of the final particles depended upon whether a crosslinker was employed in the second stage polymerization. When a crosslinker was present, the second‐stage particles and the subsequent third‐stage particles had a shrunken, raisin‐like appearance. When no crosslinker was present, spherical particles were obtained. In both cases, the resulting third‐stage particles were easily dispersed in water containing a small amount of amine base, indicating that COOH and OH groups are located at the surface (or in a shell at the surface) in these NAD particles. © 1994 John Wiley & Sons, Inc.
Temperature effect on conducting polyaniline salts: Thermal and spectral studies
Authors: Palaniappan S. , Narayana B. H. 
Published: April 2003

AbstractFive different polyaniline salts have been prepared by chemical polymerization of aniline in aqueous solution of different acids. Polyaniline samples have been heat treated at four different temperatures (150, 200, 275, and 375°C) and characterized by electron paramagnetic, electronic absorption, and infrared spectral measurements. Thermal stabilities of the chemically synthesized polyaniline salts have been studied by thermal analysis and spectral methods. Polyaniline salts undergo a three‐step weight‐loss process in the heating cycle. The first step (up to 110°C) corresponds to the loss of water molecules from the polymer chain. In the second step (110–275°C), a small amount of acid escapes as volatile gas, and after 275°C the polymer undergoes oxidative thermal degradation in the third step. It was found that thermal stability of polyaniline salts depends on the counteranion used and the polymer is apparently stable up to 250°C. No structural changes have taken place up to 200°C and this has been confirmed from infrared and electronic absorption spectra. No definite correlation exists between conductivity and spin concentration. © 1994 John Wiley & Sons, Inc.
Thermoreversible reaction of diels—alder polymer composed of difurufuryladipate with bismaleimidodiphenylmethane
Authors: Kuramoto Noriyuki , Hayashi Keiji , Nagai Katsutoshi 
Published: April 2003

AbstractThermoreversible reaction of Diels‐Alder polymer composed of difurufuryladipate with bismaleimidodiphenylmethane was studied in dimethylformamide solution. The retro‐Diels‐Alder degradation occurred gradually at 90°C and Diels–Alder polymerization proceeded quickly at 60°C. © 1994 John Wiley & Sons, Inc.
Synthesis of end‐functionalized polystyrenes with organosilicon end‐capping reagents via living cationic polymerization
Authors: Miyashita Kazuaki , Kamigaito Masami , Sawamoto Mitsuo , Higashimura Toshinobu 
Published: April 2003

AbstractThe end‐functionalization of living polymers with bases (methanol, benzylamine, diethyl sodiomalonate, and sodium methoxide) and organosilicon compounds [X  Si(CH3)3;X : CH2C(CH3)COO, CH3COO, CH2CHCH2, C6H5] was investigated in the living cationic polymerization of styrene initiated with the 1‐phenylethyl chloride/SnCl4/nBu4NCl system in CH2Cl2 at −15°C. The four bases and C6H5SiMe3, independent of their structures, were apparently incapable of reacting with the living end and invariably led to polystyrenes with the ω‐end chlorine [∼ ∼ ∼ CH2CH(Ph)Cl] originated from the initiating system. The number‐average end‐functionality (F̄n) of the chloride, determined by 1H‐NMR, was close to unity (F̄n > 0.9). The presence of chlorine in the polymer was also confirmed by elemental analysis. In contrast, the quenching by the trimethylsilyl compounds with X = methacryloxy, acetoxy, and allyl gave ω‐end‐functionalized polystyrenes with the corresponding terminal groups (X) for which the F̄n values were close to unity (F̄n > 0.9). The effects of the structure of silyl compounds on end‐capping are also discussed. © 1994 John Wiley & Sons, Inc.
Synthesis and kinetics of polymerization of unsaturated monomers with OH groups in their structure: I.3‐hydroxyneopentyl acrylate
Authors: Iglesias M. T. , Guzmán J. , Riande E. 
Published: April 2003

AbstractThe synthesis of new unsaturated monomers containing functional groups has been theoretically analyzed by considering a simple kinetic scheme. In the reactions between acetyl and acryloyl chloride with neopentylglycol, it was shown that the comparison between theoretical and experimental results, does not allow us to conclude that the two rate constants controlling the reactions are equivalent. Kinetic experiments of the polymerization of 3‐hydroxyneopentyl acrylate were carried out in benzene and 1,4‐dioxane solution at different temperatures. Dilatometric techniques and nonlinear least‐squares methods were used to obtain kinetic data and to determine the kinetic constants, respectively. The values of \documentclass{article}\pagestyle{empty}\begin{document}$k_p /k_t^{1/2}$\end{document}
for this monomer were found higher in dioxane than in benzene due, probably, to the fact that in the last solvent the polymerization is heterogeneous. The activation energy, determined by using different values of \documentclass{article}\pagestyle{empty}\begin{document}$k_p /k_t^{1/2}$\end{document}
was found 7.6 kcal/mol.
The stereostructure of the polymers derived from 3‐hydroxyneopentyl acrylate and 3‐acetoxyneopentyl acrylate was determined by 13C‐NMR spectroscopy from the analysis of the resonance signals belonging to the carbonyl groups, obtaining values for the fraction of isotactic dyads in the range 0.36 ± 0.03 for both polymers. Finally, the glass transition temperatures of both polymers, determined calorimetrically, were found 281 and 255 K, respectively. © 1994 John Wiley & Sons, Inc.
Molecular composite. II. Novel block copolymer and semi‐interpenetrating polymer network of rigid polyamide and flexible polyimide
Authors: Chang Ken‐Yuan , Chang Hurng‐Ming , Lee Yu‐Der 
Published: April 2003

Abstract2,2'‐Dimethyl‐4,4'‐diamino‐biphenyl was used to prepare a lyotropic amine‐terminated polyamide (PBTA) prepolymer with terephthaloyl dichloride, and an amide oligomer with reactive endcaps of maleimide, respectively. The former was employed in an attempt to increase the solubility of PA/PI block copolymers, and the latter to produce a three‐dimensional (isotropic) reinforced molecular composite through the technology of a semiinterpenetrating polymer network (semi‐IPN). PBTA prepolymer was copolymerized with an amine‐terminated polyimide via a coupling reaction using terephthaloyl dichloride. The resultant block copolymers were characterized by IR, NMR, ηinh and GPC to confirm that the copolymerization reaction was precisely accomplished, as well as to determine their composition and molecular weight. Thermal analysis and lyotropic behavior were also studied for these copolymers. Rigid‐rod amide oligomer was crosslinked in the presence of another flexible polyimide. Five sets of semi‐IPN films were prepared under varying compositions. The curing conditions were investigated by DSC; in addition, the cured semi‐IPNs exhibited a single phase (1 Tg) according to examination by an instrument for thermally stimulated current (TSC). No large‐scale phase separation was observed in SEM images of the fractured surfaces. © 1994 John Wiley & Sons, Inc.
Fullerenated carbazole polymers via bromination
Authors: Thomas Rhys N. 
Published: April 2003

AbstractSurface‐substituted and homogeneous fullerenated polymers were produced by bromination followed by a Friedel‐Crafts reaction. Control over bonding patterns was provided by the bromination, which enabled the production of photodegradation‐resistant fullerenated polymers. © 1994 John Wiley & Sons, Inc.
Asymmetric zirconocene precursors for catalysis of propylene polymerization
Authors: Fierro Ricardo , Chien James C. W. , Rausch Marvin D. 
Published: April 2003

AbstractRacemic isopropylidene (1‐η5‐cyclopentadienyl)(1‐η5‐indenyl) dichlorozirconium and the 3‐methylindenyl derivative have been synthesized and characterized. These precursors activated with methylaluminoxane produce poly(propylene) with hemiisotactic microstructures. © 1994 John Wiley & Sons, Inc.
New results of the free radical ring‐opening polymerization
Authors: Letsch Jörg , Klemm Elisabeth 
Published: April 2003

AbstractThe reaction of 5‐ring ketene‐O, N‐acetals with peroxides was investigated. It was shown that benzoyl peroxide adds to monomers 5a and 5b by ring opening, giving the corresponding linear diester amides 6a and 6b, respectively. The ketene‐O,N‐acetal 5c adds benzoyl peroxide, without ring opening, by addition to the exomethylene group, giving the cyclic‐O,N‐acetal diester 6c. With phthaloyl peroxide cyclic esteramides 7 and oligomeric products are formed. The chemical structures of the addition products were confirmed by NMR spectra and elemental analysis. © 1994 John Wiley & Sons, Inc.
Ester derivatives of α‐hydroxymethylacrylates: Itaconate isomers giving high molecular weight polymers
Authors: Avci Duygu , Kūsefǧlu Selim H. , Thompson Robert D. , Mathias Lon J. 
Published: April 2003

AbstractNew ester derivatives of ethyl α‐hydroxymethylacrylate were synthesized using acid chlorides (traditional solution reactions), sodium salts of acids (with phase transfer catalysis), and trifluoroacetic anhydride (trifluoroacetate). The interfacial process gave high yields of clean products under very mild conditions. Derivatives obtained include the formate, acetate, hexanoate, stearate, benzoate, trifluoroacetate, and adamantanoate. Bulk polymerizations with 2,2′‐azobis (isobutyronitrile) gave high molecular weight polymers with intrinsic viscosities of over 2 dL/g and molecular weights of several million [based on size‐exclusion chromatography (SEC) comparison to polystyrene standards]. These high molecular weights were the result of autoacceleration in the bulk as shown by monitoring molecular weight with respect to conversion. Solution polymerization in benzene gave more typical polymer, e.g., the acetate derivative showed an SEC molecular weight of 52,000. Glass transition temperatures for the n‐alkyl esters decreased from the formate (77°C) to the hexanoate (15°C); the stearate showed a side‐chain melting point of 40°C but no Tg. Glass transitions were observed for the trifluoroacetate, benzoate, and adamantanoate polymers at 69, 130, and 214°C, respectively. Solution 13C‐NMR showed evidence of tacticity information for the formate and acetate derivatives with appaent preference for syndiotactic polymer formation similar to that of methyl methacrylate. FTIR and solid‐state 13C‐NMR analysis gave spectra with functional group peaks and chemical shift values expected based on composition. The stearate monomer and polymer gave solid‐state 13C chemical shifts of 34 and 33 ppm, respectively, for the central CH2 units consistent with monoclinic and orthorhombic crystal packing. © 1994 John Wiley & Sons, Inc.
Synthesis, characterization, and properties of colorless rigid‐rod poly(benzobisthiazole) derived from bicyclo[2.2.2]octane
Authors: Dotrong M. , Dotrong M. H. , Wang C. S. , Song H. , Moore G. J. , Evers R. C. 
Published: April 2003

AbstractPolycondensation in polyphosphoric acid of 2,5‐diamino‐1,4‐benzene dithiol dihydrochloride with bicyclo[2.2.2]octane‐1,4‐dicarboxylic acid, as well as the corresponding dimethyl ester or diacid chloride, led to rigid‐rod benzobisthiazole polymers. Colorless and soluble polymers with intrinsic viscosities as high as 30.6 dL/g (methanesulfonic acid, 30°C) were obtained. The ultraviolet‐visible spectrum of a polymer film cast from methanesulfonic acid under reduced pressure displayed no absorptions in the visible range (400–900 °m). The polymer was thermooxidatively stable up to 420°C in air as determined by thermogravimetric analysis. Fibers spun from a lyotropic polyphosphoric acid solution exhibited a tensile strength of 300–450 Ksi, a modulus of 26 Msi, and a compressive strength of 53 Ksi. Wide‐angle X‐ray scattering patterns of polymer fibers indicated a 3‐dimensional crystal structure rather than a nematic liquid crystal structure. © 1994 John Wiley & Sons, Inc.