bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal decomposition of viscose rayon in the presence of inorganic additives. A kinetic study
Authors: Venkateswaran R. , Babu S. , Kumar S. Sukesh , Pillai M. Aravindakshan , Sharma P. Vishnu 
Published: April 2003

AbstractViscose rayon, like many other cellulosic materials, has a thermal decomposition reaction. The rate of change of weight loss of this material is very high at a narrow range of temperatures. When viscose rayon is impregnated with inorganic additives, there is a shift in the temperature of maximum rate of weight loss (Tmax) towards the lower side of the temperature. This effect, due to the addition of ammonium chloride, calcium chloride, and a mixture of calcium chloride and ammonium chloride, was studied in the temperature range 200–400°C through thermogravimetry and the changes observed in the values of activation energy, order of reaction, and char yield are presented in this paper.
Utilization of lignin p‐aminophenyl carbamate as a coupler for dyeing wool and nylon
Authors: Nagieb Z. A. 
Published: April 2003

AbstractLignin carbamate was prepared as a good blocking for the phenolic hydroxyl group of lignin. To reduce its color, the following was accomplished: first, condensation of lignin carbamate with p‐nitroaniline to fulfill complete blocking; second, reduction of this compound with thiourea dioxide to give a new compound; and third, diazotization of this new compound with different phenolic compounds to give highly reactive dispersed dyes that have very attractive colors. Lightfastness and washing perspiration fastness were studied, and the relationship between spectral analyses and the fastness was also considered.
Preparation and structural consideration of nitrogen‐containing derivatives obtained from dialdehyde celluloses
Authors: Maekawa Eiichi , Koshijima Tetsuo 
Published: April 2003

AbstractNitrogen‐containing derivatives obtained from dialdehyde celluloses were prepared under different pH conditions. On the basis of the results from an analytical data and IR absorption spectra of the products, the structure and characterization of nitrogen‐containing products are discussed and also evaluated concerning a hemialdal seven‐membered cyclic structure proposed by Barry et al. (J. Chem. Soc., 1953, 3631).
The effects of fillers and extenders on the cure properties of phenol–formaldehyde resin as determined by the application of thermal techniques
Authors: Waage S. K. , Gardner D. J. , Elder T. J. 
Published: April 2003

AbstractThe techniques of dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC) were used to examine the effects of the addition of various fillers and extenders (clay, pecan shell flour, and wheat flour) on the curing mechanism of a phenolformaldehyde resol. The DMTA results indicated that the curing process was unaffected by any of the additives. The DSC thermograms showed a single exothermic peak that was not influenced to a great extent by the fillers or extenders. Comparison of viscosity measurements and gel time determinations showed slight differences in the physical properties of the uncured resins.
Application of starch xanthates for cadmium removal: A comparative evaluation
Authors: Jawed Mohammad , Tare Vinod 
Published: April 2003

AbstractAttempts to solve the problem of heavy metals removal and recovery from wastewaters have led to the development and application of several techniques. One of the techniques involves application of starch and cellulose‐based products, especially xanthates. Both water‐soluble and insoluble starch xanthate processes have been claimed to be successful based on the studies conducted with relatively simple wastewaters. The major objectives of this study have been to evaluate the effectiveness of insoluble starch xanthate (ISX) for the removal of cadmium, study the effect of complexing agents/ligands on the interaction of cadmium with ISX and soluble starch xanthate (SSX), and to make overall comparison of ISX and SSX processes for cadmium removal. Both SSX and ISX can bring down the aqueous phase cadmium concentration to less than 1 mg/liter (Indian effluent discharge standard) irrespective of the pH (in the range of 3 to 7), ionic strength, and initial cadmium concentration. The metal binding capacity of ISX is maximum in the pH range of 4 to 5 and is constant irrespective of equilibrium metal concentrations as well as different doses of ISX used at lower pH values (3 to 5). The metal uptake by ISX/SSX in the presence of EDTA is affected considerably. ISX shows higher uptake of cadmium in the presence of EDTA as compared to SSX. The insoluble xanthate process appears to have an edge over soluble xanthate process in terms of metal removal capacity, reliability, and ease of operation, particularly for cadmium.
Mechanical properties of oriented poly(vinyl chloride)–poly(caprolactone) blends
Authors: Ajji A. , Renaud M. C. 
Published: April 2003

AbstractBlends of poly(vinyl chloride) (PVC) with polycaprolactone (PCL) of different compositions were prepared from solutions in tetrahydrofuran (THF). The dried blends were stretched at different temperatures above the glass transition, and the birefringence and mechanical properties were studied. It is shown that the birefringence of PVC and the 75/25 PVC/PCL blend follows an affine deformation scheme with a decreasing number of segments with deformation. The 50/50 PVC/PCL blend shows a complex orientation behavior because of the presence of crystallinity in the PCL phase. The mechanical properties of the blends are shown to increase with orientation, and the aggregate model is acceptably followed by the amorphous oriented blends.
Polyamides and polyesters with improved mechanical properties
Authors: Fakirov Stoyko , Evstatiev Michail , Schultz Jerold M. 
Published: April 2003

AbstractAn attempt is made to establish the most proper initial structure for the obtaining of highly drawn (at room temperature) nylons and polyesters. It is found that neither the completely crystalline structure nor the fully amorphous one but a low‐crystallinity, very imperfect structure (with a large number of small crystallites) is the most suitable one. Through ultraquenching of nylon 6 and PBT melts, and storage at ambient conditions, draw ratios of 7 and 8, respectively, are achieved. Subsequent annealing results in the obtaining of doubly higher values of the elasticity modulus and tensile stress. By means of WAXS, SAXS, IR spectroscopy, and DSC measurements the obtained structure is characterized. The highly drawn and annealed samples show a strongly reduced concentration of chain folds and a lack of long spacing.
Removal and recovery of gallium and indium lons in acidic solution with chelating resin containing aminomethylphosphonic acid groups
Authors: Maeda Hironori , Egawa Hiroaki 
Published: April 2003

AbstractRemoval and recovery of gallium and indium ions in acidic solution with the macroreticular chelating resin containing aminomethylphosphonic acid groups was investigated. The resin (RMT‐P) exhibited high affinity for gallium and indium ions in sulfuric acid solution. In the column method, gallium and indium ions in sulfuric acid solution (0.05 or 0.5 mol/dm3) were favorably adsorbed on the RMT‐P when the solution containing 27.6 mg/dm3 of gallium ion or 51.4 mg/dm3 of indium ion was passed through the RMT‐P column at a space velocity of 15 h−1. The gallium and indium ions adsorbed were eluted by allowing 1 mol/dm3 sodium hydroxide or 4 mol/dm3 hydrochloric acid to pass through the column. The proposed resin appears to be useful for the recovery of gallium and indium ions in sulfuric acid solution.
Carboxyl‐terminated poly(propylene glycol) adipate‐modified room temperature curing epoxy adhesive for elevated temperature service environment
Authors: Achary P. Sasidharan , Gouri C. , Ramaswamy R. 
Published: April 2003

AbstractAn investigation was carried out into the effect of modification of an epoxy resin with carboxyl‐terminated poly(propylene glycol) adipate (CTPPGA) liquid rubber, on room temperature and elevated temperature adhesive joint strengths, after curing at room temperature (25°C) with tris‐2,4,6‐(N,N‐dimethyl amino methyl) phenol hardner. CTPPGA prepared by the esterification of poly(propylene glycol) (PPG) and molar excess of adipic acid was incorporated into the epoxy resin by the prereact method. CTPPGA modification showed significant enhancement of adhesive joint strengths over the unmodified epoxy and the joint strengths were found to depend on the molecular weight of CTPPGA and its content in the epoxy resin. The elevated temperature lap shear strength measurement made for the CTPPGA‐modified epoxy adhesive showed that the adhesive formulation has a temperature service capability up to 120°C. The results are discussed in terms of the data obtained from the tensile tests, DSC analysis, and SEM observations of the fractured surfaces.
Grafting of vinyl acetate–methyl acrylate mixture onto cellulose. Effect of inorganic salts
Authors: Fernandez M. J. , Casinos I. , Guzman G. M. 
Published: April 2003

AbstractThe effect of the addition of NaNO3 and NaCl on the graft copolymerization of a mixture of vinyl acetate–methyl acrylate onto cellulose, using ceric ion as initiator, is examined. Several grafting parameters were measured. Presence of NaNO3 affects the graft copolymerization by enhancing the cellulose oxidation, but it leaves almost unaffected the homopolymerization reaction. NaCl works similarly to NaNO3. As a consequence of salt presence, ligand changes in the ceric ion complexes, as well increase in the ionic strength of the medium, are expected.
Effect of amines on the carbanilation of cellulose with phenylisocyanate
Authors: Evans Robert , Wearne Ross H. , Wallis Adrian F. A. 
Published: April 2003

AbstractVarious amines were added to carbanilation reactions of cellulose samples with phenylisocyanate in an effort to aid the preparation of cellulose tricabanilates (CTCs) for determining molecular weight distributions (MWDs). However, the amines catalyzed the conversion of phenylisocyanate to its trimer phenylisocyanurate, especially in dimethylsulfoxide (DMSO) and N,N‐dimethylformamide (DMF) media. In some of the reactions to which amines were added, the CTC products had high‐performance size exclusion chromatographic peaks that tailed badly. The tailing was not caused by incomplete carbanilation. The amines 1,4‐diazabicyclo (2.2.2) octane (DABCO) and 4‐N,N‐dimethylaminopyridine (DMAP) accelerated the dissolution of cellulose during carbanilation, while others retarded the dissolution. DABCO in pyridine assisted the carbanilation of cellulose samples, which were otherwise unreactive in pyridine, although the reactions were slower than in uncatalyzed DMSO media. However, the reactions in DMSO with added amines gave CTCs with lower degree of polymerization (DP) values, and the DP reduction was particularly severe when N‐methylimidazole was the added amine. The possible involvement of oxidation by DMSO in the depolymerization process is discussed. It was concluded that addition of amines to carbanilation reactions of cellulose has limited application for CTC preparation for MWDs.
Crystallinity and lateral crystallite size of different UHMW PE materials
Authors: Hofmann D. , Schulz E. , Fanter D. , Fuhrmann H. , Bilda D. 
Published: April 2003

AbstractNascent high‐molecular‐weight (UHMW) polyethylene (PE) samples of different origins show a rather high crystallinity of about 70–75% and contain both a major portion of orthorhombic extended chain crystallites and a minor portion of triclinic crystallites. The triclinic content is greater the higher the molecular weight of the sample and the higher the activity of the used catalyser. A melting / recooling treatment results in a reduction of crystallinity by about 15–25% and disappearance of the triclinic phase. Further, an irreversible conversion of nascent orthorhombic extended chain crystallites to orthorhombic folded chain crystallites of increased lateral dimensions and crystalline perfections takes place during the melting / recooling treatment. The results are compared to those obtained for lower‐molecular‐weight PE samples and for high‐strength / modulus PE fibers of different origins.
Effect of preextension on electrical conductivity and physicomechanical properties of butyl rubber (IIR) loaded with different types of carbon black
Authors: Hashem A. A. , Ghani A. A. , Eatah A. I. 
Published: April 2003

AbstractThe effect of preextension on the variation of the electrical conductivity (σ) of butyl rubber (IIR) loaded with high abrasion furance (HAF) and fast extrusion furance (FEF) carbon black with carbon concentration have been investigated. The change in σ has been explained as a result of the interaction between carbon and rubber and the effect of the occluded rubber.The effect of preextension on the electrical resistivity (ρ) variation with strain has also been studied. The changes have been interpreted as being due to either breakdown or reagglomeration, depending on the concentration of carbon black.
Theoretical modification of the finely porous model for reverse osmosis transport
Authors: Mehdizadeh H. , Dickson J. M. 
Published: April 2003

AbstractOne of the most significant models used to describe and predict the performance of reverse osmosis type membranes is the finely porous model (FPM). In this paper, the basic assumptions of the model are examined and modified. The two most serious problems with FPM are that an incorrect form of material balance on the solute is used and that the osmotic pressure effects are not completely taken into account for electrolytes. A modified model (called MD‐FPM), which is based on the same physical precepts is derived. Equations describing the concentration profile for both models have been derived and compared. It has been shown that the FPM can predict physically unacceptable results. Difficulties in using the parameters from the model for prediction or for membrane development work are discussed. Simulation results for the MD‐FPM model are consistent with what is expected for reverse osmosis type membranes.
Studies of macromolecular entanglements. I. Melting behavior of swelling polymers with macromolecular entanglements
Authors: Qian Baojun , Wu Zongquan , Hu Panpan , Qin Jian , Wu Chengxun , Zhao Jiongxin 
Published: April 2003

AbstractIn this paper the swelling and melting behavior of several polymers, particularly acrylic fibers, is studied by thermomicroscopy and differential scanning calorimetry in detail. It is confirmed that the protrusion peak on the tail part of the DSC thermogram of swelling polymers is closely associated with the macromolecular entanglements. The proposed swelling DSC method is proved to be very effective for studying polymer entanglements. It is also shown that the melting point, whether of paracrystalline region or of entanglement structural unit, can be well fitted to Flory's melting point depression theory.
Electrochemical polymerization of N‐vinylcarbazole
Authors: Bhadani Suraj N. 
Published: April 2003

AbstractThe electrolysis of N‐vinylcarbazole in the solution of quaternary ammonium salts in dichloroethane leads to polymer formation in the anolyte. The effect of monomer concentrations, current levels, and nature of supporting electrolytes on the polymerization has been investigated. The polymerization is free radical with bromide salt and cationic with perchlorate or hexachloroantimonate salt. The poly(N‐vinylcarbazole) gets oxidized at the anode and can be cycled between the oxidized and neutral states. The oxidized polymers at the electrode may exhibit electrical conductivity.
Solvent‐induced crystallization in polyetherimide thermoplastics and their carbon fiber composites
Authors: Nelson K. M. , Seferis J. C. , Zachmann H. G. 
Published: April 2003

AbstractSolvent‐induced crystallization (SINC) was observed in a polyetherimide (PEI), a thermoplastic used as a matrix in carbon fiber composites. This observation was made using wide angle X‐ray scattering (WAXS), differential scanning calorimetry (DSC), and optical microscopy. It was discovered that methylene chloride induces crystallization in the PEI by penetrating the surface and swelling the bulk polymer. Prepreg processed using N‐methyl pyrrolidone (NMP) was also crystalline. One processed above the crystalline melting point (Tm), no crystallinity in the sample was found, as the PEI did not crystallize from the melt. The observed crystallization of both the neat polymer and its carbon fiber prepreg was exclusively through a solvent‐induced process, although it is likely that the mechanism through which crystallization occurs during solvent prepreg processing is different than the diffusion‐controlled mechanism demonstrated with methylene chloride. A solvent prepregging process may involve a low molecular weight or monomer solution as well as other polymerization by products. Measurements using WAXS showed a maximum degree of crystallinity of 30%, as induced by methylene chloride. A value of 85 J/g for the heat of solvent‐induced crystallization in the PEI was calculated from the DSC measurements.
The effect of gamma ray irradiation on the mechanical properties of large cross‐section oriented polyethylene rods
Authors: Sangster D. F. , Barry D. B. 
Published: April 2003

AbstractThe effect of gamma irradiation, in acetylene, on large diameter oriented polyethylene has been investigated. The dependency of gel content, melting point, and crystallinity on dose was evaluated. The gel content dose relationship showed two regions, indicating that an effective network is formed at low doses, 60 kGy. Irradiating the oriented rod in acetylene was found to more than double the initial tensile modulus. This improvement in the tensile properties resulted in improved creep–strain resistance for the material. These improvements in the mechanical properties were attributed to crosslinks formed both in the amorphous regions and at the surfaces of the crystalline regions. At high does > 180 kGy degradation of the oriented polymer resulted in a deterioration in mechanical properties.
Hydroperoxidation of EPDM rubber using singlet oxygen: Synthesis and grafting studies
Authors: DeRosa T. F. , Kaufman B. J. , Broas J. E. 
Published: April 2003

AbstractChemically generated singlet oxygen hydroperoxidizes the ethylidene double bond in terpolymers of ethylene, propylene, and ethylidene norbornene (EPDM rubber). The EPDM–hydroperoxide was reduced exclusively to 2‐(1‐hydroxylethyl)‐norborene‐EPDM rubber using either triphenylphosphine or sodium sulfite. Thermal decomposition of EPDM–hydroperoxide in the presence of either methyl methacrylate or 2‐ or 4‐vinyl pyridine free radically grafted these monomers to the rubber. In the absence of graftable monomer, however, thermal decomposition of EPDM‐hydroperoxide generated an intractable polyether.
Copolymerization of alkyl methacrylates with triallyl cyanurate. Determination of monomer reactivity ratios
Authors: Ryttel Anna 
Published: April 2003

AbstractThe free‐radical copolymerization of propyl, pentyl, hexyl, heptyl, octyl, and dodecyl methacrylates with triallyl cyanurate was investigated. The reactivity ratios were determined using the methods of Fineman‐Ross and Kelen‐Tüdös. The Alfrey‐Price Q and e values for the methacrylates were also evaluated. The effect of the length of alkyl group in methacrylates on reactivity ratios is discussed.
Superstructure in ultrahigh speed spun fibers of poly(ethylene terephthalate)
Authors: Fujimoto K. , Iohara K. , Ohwaki S. , Murase Y. 
Published: April 2003

AbstractUltrahigh speed spinning of poly(ethylene terephthalate) (PET) was carried out at various take‐up velocities from 5 to 10 km/min. The superstructure of as‐spun fibers was characterized by small‐angle X‐ray scattering (SAXS), wide‐angle X‐ray diffraction (WAXD), viscoelastic properties, and scanning electron microscopy (SEM). Above 6 km/min the peaks or shoulders that are due to the interference between microfibrils appear on the equatorial SAXS intensity curves. The interfibrillar spacing estimated from the peak position increases with increasing take‐up velocity. Comparison of the spacing with the lateral crystal sizes estimated from the broadness of the crystal (hk0) WAXD peaks indicates that the microfibril diameter becomes thick with increasing take‐up velocity. Although the orientation and density in amorphous region for high‐speed spun fibers are very low on the average, it can be seen that a few highly extended tie molecules exist in that region, and the number of these molecules increases with increasing take‐up velocity. The modes and mechanisms of fibrillation induced by a rubbing test are discussed relating to these results.
Empirical modelling and scale‐up of a semi‐batch polyestrification process
Authors: Dairanieh Issam S. , Khraishi Nadia 
Published: April 2003

AbstractA semi‐empirical kinetic model that fits laboratory data and predicts pilot plant data was developed. The model is a modified version of a recently reported third‐order kinetic equation for the reaction of nonstoichiometric amounts of hydroxyl and carboxylic groups. The model can be used to quantify the effects of reaction temperature and inert gas flow rate on the reaction rate. The Arrhenius temperature dependence of the rate constant permitted the calculation of the reaction activation energy (53.6 kJ/mol). The gas flow rate dependence is an empirical function of the molar ratio of reactants to inert gas. The same function is simultaneously used as the process scale‐up rule. The mathematical model can be potentially used for commercial‐sized reactors.
A pseudouniversal calibration procedure for the molecular weight determination of cellulose
Authors: Vidal P. F. , Basora N. , Overend R. P. , Chornet E. 
Published: April 2003

AbstractSize‐exclusion chromatography of carbanilated cellulose of polystyrene‐divinylbenzene packing has been used to determine the molecular weight distribution of the polymer with tetrahydrofuran as the eluent. The reproducibility and the accuracy of the method is discussed in this paper with reference to depolymerized organosolvent‐treated celluloses. A comparison between the results obtained from the universal calibration approach and the viscosity‐average degree of polymerization, derived from the determination of the intrinsic viscosity in cupriethylene diamine solutions, is presented
A highly fluorinated epoxy resin. III. Behavior in composite and fiber‐coating applications
Authors: Twardowski T. E. , Geil P. H. 
Published: April 2003

AbstractThe behavior of a highly fluorinated epoxy resin used as a composite matrix material with AS‐4 fibers and as an AS‐4 fiber coating was studied. The composite mechanical properties were obtained, and the adhesion of the matrix to the fibers was evaluated. Comparisons of uncoated and fluoropolymer coated AS‐4 fibers using single fibers embedded in an Epon 828 matrix were made. Substantial improvement in fiber critical length, and therefore fiber‐matrix adhesion, was observed.
A rheological model for iron oxide suspensions
Authors: Lin Yih‐Shen , Liu Ta‐Jo , Chu Ning‐Jo 
Published: April 2003

AbstractWe have examined the rheological properties of a Co‐adsorbed γ‐Fe2O3 magnetic suspension with polyurethane (PU) as a binder and methyl ethyl ketone (MEK) or cyclohexanone (CH) as a solvent. A Haake RV20 viscometer was used to measure the suspension viscosity and the vane method was adopted to determine the fluid yield stress. A rheological model which can be viewed as a combination of the Casson model and the Bingham model is proposed to describe the suspension viscosity. The effects of temperature, particle content, and binder concentration are included in the model.