bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and formation of cellulosic chars
Authors: Sekiguchi Yuki , Frye James S. , Shafizadeh Fred 
Published: April 2003

AbstractThe formation and structure of chars produced on heating of cellulose, lignin, and wood have been investigated by FTIR and CP/MAS 13C‐NMR, and the results have been discussed in conjunction with parallel permanganate oxidation studies reported before. These data show that when cellulose is heated for 5 min within the temperature range of 325–350°C, the IR bands associated with hydroxyl and glycosidic groups in cellulose disappear, and new bands signal the formation of unsaturation and carbonyl groups by dehydration and rearrangement. The NMR data also show the disappearance of the glycosyl carbons at 60–110 ppm and the appearance of methyl and other paraffinic carbons at 0–60 ppm, aromatic carbons at 110–170 ppm, carboxyl carbons at 170–190 ppm, and carbonyl carbons at 190–220 ppm. On heating at 400°C the IR and NMR signals for the glycosyl groups completely disappear, the signals for carbonyl and carboxyl groups diminish, and those for the aromatic and paraffinic groups expand. At this stage the char contains about 69% aromatic and 27% paraffinic carbons. At the temperature range of 400–500°C the paraffinic carbon content is reduced to 12%, and a highly aromatic (88%) char is produced. This is consistent with the permanganate oxidation studies which show the production of polycyclic aromatic structures resulting from extensive condensation and crosslinking at these temperatures. The chars produced from wood and lignin at 400°C had about the same aromatic carbon content as the corresponding cellulose char; however, the char yields were higher due to the presence of the methoxy phenyl groups that survive the heating process, as indicated by strong NMR signals at 55 and 148 ppm.
Reactions of functional polymethacrylates grafted on phosphate‐modified calcium carbonate
Authors: Nakatsuka Takuo , Yamashita Shinzo 
Published: April 2003

AbstractFive methacrylate monomers of methyl (MMA), dimethylaminoethyl (AEMA), 2‐chloroethyl (CEMA), 2,3‐epoxypropyl (GMA), and 2‐hydroxyethyl (HEMA) were graft‐polymerized in fine yields onto the calcium carbonate, which surface had been modified with 2,2′‐dimethyl‐2,2′‐azobisbutyronitrile‐4,4′‐dicarboxyethyl bisdihydrogenphosphate (AZDP). For the GMA and HEMA, styrene (St) was used as a hydrophobic comonomer for convenience to make homopolymers easily removed. The resulting grafted polymers were treated with such reagents: methyl iodide for the poly‐AEMA (pAEMA), sodium diethyldithiocarbamate (NaETC) for the poly‐CEMA (pCEMA), 2,2′‐iminodiethanol for the poly‐co‐GMA–St (pGMA–St), and m‐trifluoromethylphenyl isocyanate for the poly‐co‐HEMA–St (pHEMA–St). Diffusive reflectance infrared spectroscopy indicated that these reactions resulted in excellent yields, whereas the detection of the product from NaETC and 6‐chlorohexyl dihydrogenphosphate (CHP)‐modified calcium carbonate failed. The results of thermal analyses (DSC–TG), gel permeation chromatography (GPC), and changes of their surface wettabilities toward water are also discussed.
Glow discharge polymerization of tetramethylsilane by capacitive coupling of 20 kHz frequency and surface hardening of polyethylene sheet
Authors: Inagaki N. , Ohnishi Y. , Chen K. S. 
Published: April 2003

AbstractGlow discharge polymerizations of tetramethylsilane (TMS) were performed by the capacitive coupling of a 20 kHz frequency in comparison with those by the inductive coupling of a 13.56 MHz frequency. The polymers prepared by the former coupling were poorer in carbon and hydrogen, but richer in silicon than those prepared by the latter coupling. These two polymers showing similar infrared spectra contained CH3, CH2, CH, SiOC, SiOSi, SiCH3, and SiCH2CH2Si groups. Some physical properties involving surface energy, thermal stability, and absorption spectra in the regions of the UV and visible light were determined. This coating procedure was applied for surface hardening of a polyethylene sheet. The surface hardness of the polyethylene sheet was enhanced by a coating of plasma films prepared from TMS or the TMS/O2 mixtures. Surface hardness was determined by the pencil method and hardness was enhanced from 2B to 2H. The adhesion between these plasma films and polyethylene sheet was good even when immersed in 0.9% NaCl solution at 40°C for 10 days.
Hybrid copolymerization of alkyl vinyl ethers with glycidyl ethers
Authors: Solaro R. , D'Antone S. , Orsini M. , Andruzzi F. , Chiellini E. 
Published: April 2003

AbstractHomopolymerization and copolymerization experiments of isobutyl and dodecyl vinyl ether with propylene oxide, and some glycidyl ethers have been carried out by using both conventional cationic initiators (BF3, BF3·OEt2) and 4‐chlorophenyldiazonium tetrafluoborate as cationic photoinitiator. Conventional polymerization experiments performed under vacuum at low and room temperature gave rise to a mixture of the two homopolymers, indicating that the epoxide and vinyl ethers are incompatible with respect to chemical reactivity and that apparently no hybrid copolymerization occurs. Analogous results were obtained in parallel photoinitiated polymerization experiments.
Prediction of reverse osmosis performance of cellulose acetate membrane
Authors: Devmurari C. V. , Chandorikar M. V. 
Published: April 2003

AbstractThis study illustrates the analytical techniques involved in specifying the membrane and outlines the procedure for predicting the reverse osmosis (RO) performance of these membranes using feed solutions, containing either single solutes or mixed electrolytes having a common ion. The scientific basis for such specification and prediction techniques has been extensively discussed in the literature. In the present work, the governing transport equations for RO systems, involving preferential sorption of water at the membrane–solution interface, are utilized.
Synthesis and properties of photosensitive rubbers. III. Synthesis of chloroacetylated polybutadiene and its photosensitivity
Authors: Azuma Chiaki , Hiramatsu Toshio , Tanaka Hozumi , Sanui Kohei , Ogata Naoya 
Published: April 2003

AbstractPolymers having chloroacetate groups were prepared by addition reaction of various chloroacetic acids, such as mono‐, di‐, and trichloroacetic acids, to cis‐1,4‐polybutadiene under nitrogen atmosphere for obtaining photosensitive rubbers. The structure of products obtained was identified as a cyclized polybutadiene having pendent chloroacetate groups. The amount of the incorporated substituent increased up to the maximum of around 20 mol %, and the amount of the residual unsaturated groups in the polymer backbone decreased due to the cyclization of the double bond. Chloroacetylated polybutadiene had higher photocrosslinkability by UV irradiation than chloroacetylated polybutadiene had higher photocrosslinkability by UV irradiation than chloroacetylated chitosan or PVA owing to the high reactivity of the chloroacetate groups and the double bonds in the polymer. The photosensitivity depends both on the amount of the incorporated chloroacetate groups and the residual double bonds in the polymer and also depends on the glass transition temperature (Tg) of the polymer, and the dependence of the crosslinking reaction on Tg was interpreted to be due to diffusion controlled reaction between excited dichloroacetate groups and olefinic groups in the polymer.
Mixed gases separation by fine porous freeze‐dried cellulose acetate membrane
Authors: Tanioka A. , Ishikawa K. , Kakuta A. , Kuramoto M. , Ohno M. 
Published: April 2003

AbstractA Freeze‐dried cellulose acetate membrane with high permeability and high separation factor was prepared. In the successive membrance process, the heat treatment temperature was 80°C for constant period of 10 min, acetone evaporation time was between 4 and 6 min, and the membrane was fixed during drying to prevent shrinkage. Gas permeabilities for such a membrane were inversely proportional to the square root of molecular weight, suggesting that the mechanism of gas flow through this membrane was Knudsen flow. Separation factors for H2He, ArKr, N2Kr, HeNe, H2Ne, HeAr, ArH2, HeKr, ArHe, and HeH2 were measured. These factors were higher than those of membranes reported already. Separation efficiency largely depended upon the combination of mixed gases. The combination of two atom molecules and one atom molecule lowered the separation efficiency compared with the combination of one atom molecule and one atom molecule.
Polymer/piezoelectric ceramic composites: Polystyrene and poly(methyl methacrylate) with PZT
Authors: Runt J. , Galgoci E. C. 
Published: April 2003

AbstractLead zirconate–titanate (PZT)/polymer composites have been prepared by in situ polymerization of styrene and methyl methacrylate around aligned, thin PZT rods. Hydrostatic piezoelectric coefficients (d̄h and ḡgh) measured by a dynamic technique yielded figures of merit (d̄hḡh) roughly four times that of homogeneous PZT for as‐polymerized composites. When these composites were annealed at a temperature slightly below the glass transition temperature of the matrix polymer and repoled, d̄hḡh increased nearly twofold due primarily to a reduction of the composite dielectric constant. The piezoelectric response was found to be essentially independent of frequency from 30 to 160 Hz.
Substituted 1‐[(phosphiny1)methyll‐2,4‐ and ‐2,6‐dinitrobenzenes, 1‐[(phosphinyl) methyl]‐2,4‐ and ‐2,6‐diaminobenzenes: New starting materials for preparation of fire‐resistant polymers
Authors: Mikroyannidis John A. 
Published: April 2003

AbstractThe nitration of the substituted [(phosphinyl)methyl]benzenes by fuming nitric and sulfuric acid gave the substituted l‐[(phosphinyl)methy1]‐2,4‐ and ‐2,6‐dinitrobenzenes (1). The formation of the two dinitro isomers was demonstrated by proton nuclear magnetic ('H‐NMR) and infrared (IR) spectroscopy. The nitration of [di(isopropoxy)phosphinylmethyl]benzene gave mainly the p‐nitro derivative due to steric hindrance. The phosphinyl ester groups of 1 were hydrolyzed by acids. The substituted l‐[(phosphinyl)methyl]‐2,4‐ and ‐2,6‐diaminobenzenes (2) were synthesized by catalytic hydrogenation of 1. In addition, the corresponding di(benzoy1amino) derivatives of 2 were prepared. Some of the synthesized compounds were investigated by gas chromatography‐mass spectroscopy (GC‐MS). Compounds 2 can be used as starting materials for preparation of phosphorus‐containing polymers such as polyamides, polyimides, polyureas, and bismaleimides and as curing agents for epoxy resins.
Water‐soluble copolymers. VI. Dilute solution viscosity studies of random copolymers of acrylamide with sulfonated comonomers
Authors: Neidlinger Hermann H. , Chen Gow‐Sheng , McCormick Charles L. 
Published: April 2003

AbstractDilute solution viscosity of a series of random copolymers of acrylamide (AM) with sodium‐2‐acrylamido‐2‐methylpropane sulfonate (NaAMPS) and with sodium‐2‐sulfoethylmethacrylate (NaSEM) has been studied using a four‐bulb shear dilution capillary viscometer. The hydrodynamic volume of the copolymers in aqueous media was determined as a function of salt concentration, temperature, shear rate, and time. A linear relationship was observed between the intrinsic viscosity [η]0 and the reciprocal of the square root of ionic strength in sodium chloride solutions, with salt concentrations varying from 0.043M to 0.257M. Negative temperature coefficients for [η]0 indicate a decrease in the hydrodynamic volume of the ionic polymer molecules with increasing temperature. The relative zero‐shear‐intrinsic‐viscosity change in distilled water to 0.257M sodium chloride aqueous media is used to elucidate viscosity–structure relationships. A maximum value is reached for this parameter at a composition of about 30 mol % of ionic comonomers for AM–NaAMPS and AM–NaSEM copolymer series.
Reactions of diaminoalkanes with bismaleimides: Synthesis of some unusual polyimides
Authors: White Jerry E. , Scaia Mark D. , Snider Deborah A. 
Published: April 2003

AbstractMichael additions of the secondary diamines N,N′‐dimethyl‐1,6‐hexanediamine (14) or piperazine to the electrophilic carbon–carbon double bonds of N,N′‐bismaleimido‐4,4′‐diphenylmethane (2) or N,N′‐bismaleimido‐1,8‐octane (4) afford four unusual, high‐molecular‐weight (ηinh = 0.49–2.16 dL/g) polyimides (10–13). The most interesting of these, polymer 12 (the product of 4 and 14), is a tough elastomeric resin with a glass transition temperature (Tg) near 0°C; in contrast, 10, 11, and 13 exhibit Tg >86°C. Freshly prepared 12 is soluble and thermoplastic (12 is readily compression molded at 110°C), but the bulk polymer crosslinks slowly under ambient laboratory conditions and eventually (48 days) becomes insoluble, while 10, 11, and 13 remain soluble indefinitely. Along with further comparisons of the properties of 10–13, details of the synthesis and characterization of these new polyimides are described. Also discussed are reactions of bismaleimide 2 with 1,6‐diaminohexane, which unlike the formation of linear 10–13, generate crosslinked, insoluble products.
Calculation of profiles of temperature and state of cure developed within the rubber mass in injection molding process
Authors: Sadr‐Bazaz A. , Granger R. , Vergnaud J. M. 
Published: April 2003

AbstractHigher and higher temperatures for vulcanization and storage bulb are being used in order to reduce the time of cure cycle in processes of rubber injection molding. The purpose of this work was to show that the temperature gradients as well as the profiles of the state of cure developed in the rubber mass could be predicted by using the kinetics of reaction, the physical properties of the rubber, and a convenient model. Although vulcanization is a complex series of reactions, the overall result by considering the heat of reaction could be described by a single first‐order reaction. The calculation was solved applying an explicit method with finite differences, by taking into account the internal generation of heat due to the cure reaction and the heat transfer by conduction with a temperature dependence of the physical properties of the rubber. The effect of the values of the temperature of the mold and storage bulb on the profiles of temperature and state of cure developed within rubber was studied by considering rubber sheets of different thicknesses.
Epoxidation of natural rubber latices: Methods of preparation and properties of modified rubbers
Authors: Burfield David R. , Lim Kooi‐Ling , Law Kia‐Sang 
Published: April 2003

AbstractStudies in the epoxidation of natural rubber latices are described. Investigated epoxidation routes include the use of bromohydrin intermediates, hydrogen‐peroxide‐catalyzed systems, and preformed peracetic acid. The latter reagent allows almost quantitative epoxidation of natural rubber up to high modification levels with no detectable side reactions. Kinetic studies show that the peracetic acid epoxidation is second order in peracid and rubber hydrocarbon with an overall activation energy of 56.2 kJ/mol. Epoxidation leads to a progressive increase in Tg and polymer density with increase in modification level. The effect of modification on solvent swelling and mechanical properties of the DICUP‐crosslinked rubbers are reported.
Adsorption of water‐soluble, nonionic polymers onto cellulosic fibers
Authors: Ishimaru Yutaka , Lindström Tom 
Published: April 2003

AbstractThe adsorption of 12 different nonionic water‐soluble polymers, methylcellulose (MC), hydroxypropylcellulose (HPC), polygalactomannan (PGM), polyglycidol (PGD), polyacrylamide (PAAm), methylolated polyacrylamide (MPAAm), polymethacrylamide (PMAAm), three differently hydrolyzed poly(vinyl acetate)s (PVAs), poly(vinyl) methyl ether (PVME), and poly(vinyl pyrrolidone) (PVP) onto bleached kraft pulp (BK), unbleached kraft pulp (UK), and a groundwood pulp (MP) has been investigated under aqueous conditions with attention to the functional groups in the polymers and the chemical character of the pulps. It was found that the adsorption was often selective toward one of the pulps. In order to gain some additional information on these interactions, some adsorption experiments were also performed on acetylated pulps. Some polymers (PGD, PAAm, MPAAm, and PVA 124) having both proton donating and accepting capability were not adsorbed onto any of the pulps. This was attributed to intramolecular hydrogen bonding in these polymers. Some polymers (PVA 224, PVME, and PVP) were strongly adsorbed onto UK but not at all onto BK. It was suggested that in these cases the adsorptive interaction was between phenolic and/or catecholic groups in the lignin on the UK and proton accepting sites on the polymers. However, for three polymers (MC, PGM, and PMAAm), a more general type of hydrogen bonding interaction was considered. For some polymers (HPC, PMAAm, and PVA 420) having hydrophobic groups, it was suggested that hydrophobic interactions were important for the adsorption.
Effects of low levels of methacrylic acid on the swelling behavior of poly(2‐hydroxyethyl methacrylate)
Authors: Pinchuk L. , Eckstein E. C. , Van De Mark M. R. 
Published: April 2003

AbstractThe effects of low levels of methacrylic acid (MAA) (less than 4 mol %) and a crosslinker (less than 0.3 mol %) on the equilibrium swelling and water content of poly(2‐hydroxyethyl methacrylate) (pHEMA) hydrogels were investigated. Numerous pHEMA disks, some of which were doped with small amounts of MAA, were placed in swelling baths simulating possible urological as well as physiological conditions. Several interesting facts are reported, such as, in dilute urea (0.15M) or in alkali solution, gels containing 2% MAA are capable of swelling to 3600% their size in mild acid, saline, or distilled water, with associated water contents that range as high as 98%. Also, gels containing small amounts of MAA and finite crosslinker content can be made that are soluble in mild urea or alkali solution. The significance of this study is that gels or gel surfaces can be fabricated that are highly responsive to their environment. In addition, since the level of MAA that cause this shrink–swell behavior are well within the impurity levels of MAA found in unpurified commercial HEMA, it is conceivable that this shrink–swell behavior may have occurred in early studies of implanted pHEMA gels, thus confusing the subsequent evaluation of its performance as a biomaterial.
Cation exchange resin from sulfonated poly‐N‐vinylcarbazole–formaldehyde copolymer
Authors: Biswas Mukul , Bagchi Subrata 
Published: April 2003

AbstractA cross‐linked copolymer of poly‐N‐vinylcarbazole and formaldehyde has been sulfonated to yield a cation exchange resin. The resin has been characterized by elemental analysis and by evaluation of total and salt‐splitting capacities and pH‐metric titration behavior. The resin has improved capacity (ion exchange) relative to other N‐vinylcarbazole based resins and behaves as a polymeric dye.
Effect of pH of silane solution on the adhesion of polyimide to a silica substrate
Authors: Suryanarayana Darbha , Mittal K. L. 
Published: April 2003

AbstractWe show that the pH of the aminosilane solution has a significant effect on its efficacy as an adhesion promoter. Furthermore, the maximum adhesion is observed to be in the pH range close to the natural pH of the dilute silane solution. It would be interesting to extend this kind of study to other silanes as well as to various coating materials.
Rheological behavior of polymer blends
Authors: Chuang Hsiao‐Ken , Han Chang Dae 
Published: April 2003

AbstractSteady and oscillatory shearing flow properties of compatible and incompatible polymer blend systems were measured, using a cone‐and‐plate rheometer. The compatible blend systems investigated are blends of two low‐density polyethylenes (LDPE) having different values of molecular weight and blends of poly(methyl methacrylate) (PMMA) with poly(vinylidene fluoride) (PVDF). The incompatible blend system investigated is a blend of poly(methyl methacrylate) (PMMA) with polystyrene (PS). It was found that (1) plots of first normal stress difference (τ11 – τ22) vs. shear stress (τ12) and plots of storage modulus (G′) vs. loss modulus (G″) for the LDPE blends become independent of temperature and blend composition; (2) plots of τ11 – τ22 vs. τ12, and G′ vs. G″ for the PMMA/PVDF blends become independent of temperature but dependent upon blend composition. It was found further that, for the incompatible PMMA/PS blends, the dependence of τ11 – τ22 on blend composition, when plotted against τ12, is different from the dependence of G′ on blend composition, when plotted against G″. However, in both compatible and incompatible blend systems, plots of τ11 – τ22 vs. τ12 and plots of G′ versus G″ are independent of temperature. The seemingly complicated composition‐dependent rheological behavior of the incompatible blend system is explained with the aid of photomicrographs describing the state of dispersion.
Properties of 2,3‐dicarboxy cellulose combined with various metallic ions
Authors: Maekawa Eiichi , Koshijima Tetsuo 
Published: April 2003

Abstract2,3‐Dicarboxy cellulose and partially oxidized 2,3‐dicarboxy cellulose were prepared in good yields from the corresponding dialdehyde cellulose obtained by periodate oxidation of cellulose according to a modification of the method described by Hofreiter, Wolff, and Mehltretter [J. Am. Chem. Soc., 79, 6457 (1957)]. The 2,3‐dicarboxy cellulose oxidized to nearly 100% oxidation level was completely soluble in water, but the 2,3‐dicarboxy cellulose of 70% oxidation level was not. The former 2,3‐dicarboxy cellulose took up various metallic ions other than alkali metals to form a precipitate or solid. The metal contents taken up corresponded to the theoretical values calculated as combined in the form of metallic salt of the carboxylic acid group. 2,3‐Dicarboxy cellulose combined with metallic ions such as copper, cobalt, and nickel ions gave viscous, gel‐like products, which solidified when exposed to air. The properties of products combined with such metallic ions are discussed.
Mechanical and transport properties of coextruded films
Authors: Kim Y. J. , Han C. D. , Song B. K. , Kouassi E. 
Published: April 2003

AbstractTwo‐layer films were produced by using the blown‐film coextrusion apparatus constructed in our laboratory. For this study, we have produced films of the following combinations: (1) LDPE/CXA 3095; (2) LDPE/Plexar 3; (3) LDPE/EMA; (4) nylon 6/LDPE; (5) nylon 6/CXA 3095; (6) nylon 6/Plexar 3; (7) nylon 6/EMA. Tensile properties of the coextruded films were measured with an Instron testing machine, and correlated to processing variables, namely, takeup ratio and blowup ratio. From tensile property measurements, we have found that both the ultimate tensile strength and the tensile modulus of coextruded films follow the additivity rule with respect to the volume fraction of the individual components. With the films produced, we also conducted dynamic mechanical measurements with the aid of a Rheovibron Dynamic Viscoelastometer DDV‐II, and attempted to test the Zorowski–Murayama theory to determine the adhesion characteristics of the coextruded films. Furthermore, permeability of the coextruded films to gases (namely, N2, O2, and CO2) was measured by using a pressure differential apparatus constructed in our laboratory. We have found that the permeability of composite films follows the inverse additivity rule, i.e., the reciprocal of the permeability of composite film is given by the sum of the reciprocals of the permeabilities of the individual layers.