bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of phosphorus‐containing polyamides and copolyamides based on 1‐[(dialkoxyphosphinyl) methyl]‐2,4‐and ‐2,6‐diaminobenzenes
Authors: Mikroyannidis John A. , Kourtides Demetrius A. 
Published: April 2003

AbstractPhosphorus‐containing polyamides and copolyamides were prepared from 1‐[(dialkoxyphosphinyl)methyl]‐2,4 ‐ and ‐2,4‐diaminobenzenes. The polymers were characterized by infrared and proton nuclear magnetic resonance spectroscopy. differential scanning calorimetry, and thermogravimetric analysis. Their thermal properties were compared with those of the corresponding common polyamides. In addition, the fire resistance of some polyamides was evaluated by determining their limiting oxygen index value.
Radiation grafting of methyl methacrylate monomer on natural rubber latex
Authors: Sundardi F. , Kadariah S. 
Published: April 2003

AbstractA method of radiation grafting of methyl methacrylate (MMA) monomer on natural rubber (NR) latex has been studied. The irradiation dose in radiation emulsion polymerization of MMA monomer was lower compared to the irradiation dose for grafting of MMA monomer on NR latex, in order to obtain the same degree of conversion. This is due to the size of the rubber particles which are quite large and, hence, not sufficient to ensure an ideal emulsion polymerization. The irradiation dose for radiation grafting of MMA monomer on latex was around 300 krad to obtain a 75% degree of conversion. However, this irradiation dose was lower compared to the irradation dose for bulk polymerization of MMA monomer, in order to obtain the same degree of conversion. This is due to the gel effect in the viscous media. Radiation grafting of MMA monomer on NR latex does not influence the pH of the latex, but influences the viscosity significantly. The viscosity of the NR latex increased with an increase in irradiation dose, due to the increase of the total solid content in the latex. The MMA monomer converted to P‐MMA in NR latex was largely grafted on the NR, or at least insoluble in a solvent for P‐MMA, such as acetone or toluene. The hardness of the pure gum vulcanizate with an increase in the degree of grafting or P‐MMA content, but the other physical properties, such as tensile strength, modulus, elongation at break, and thermal stability, were not greatly influenced by the degree of grafting.
Thermodynamics of creep rupture
Authors: Papazian Harold A. 
Published: April 2003

AbstractAn earlier discussion of the entropy contributions to the well‐known Zhurkov relationship for creep rupture is developed from a more rigorous basis. It is demonstrated that well‐behaved Zhurkov materials (which follow his relationship closely) undergo quasistatic rupture (thermodynamically reversible). Other materials show modified Zhurkov behavior and can be described as undergoing nonquasistatic rupture, with an extra entropy term. By considering studies previously carried out in vacuum, this extra entropy has been attributed to surface phenomena.
Curing studies on modified epoxy and unsaturated polyester resins
Authors: Shukla Arvind , Rao R. M. V. G. K. 
Published: April 2003

AbstractExperimental studies were carried out on the curing behavior of unsaturated polyester and epoxy resins. The latter were modified with three different fillers (CaCO3, CaSiO3, and glass powder) and their curing behaviors studied. Polyesters exhibited faster cure rates than the epoxy resins. The gel time of the epoxy resins decreased with the addition of fillers. Data indicated that the peak exotherm of these thermosetting resins increased when filled with glass powder. The hardness of the curing mass increased with curing time. The use of gel‐hardness number as a quality control parameter has been suggested.
Radiation‐induced graft copolymerization of mixtures of styrene and acrylamide onto cellulose acetate. IV. Studies on some physical properties and structural characterization by means of scanning electron microscopy
Authors: Bhattacharyya S. N. , Maldas D. 
Published: April 2003

AbstractBinary mixtures of monomers, e.g., styrene and acrylamide in 1:1 methanol:water solution, were grafted onto cellulose acetate film by taking recourse to preirradiation grafting procedure. The surface modification of the films due to grafting was examined by means of scanning electron microscopy. The mechanical properties, e.g., tensile strength elongation at break, and elasticity as well as water vapor permeability of the grafted films, were investigated. In the case of ungrafted films or when acrylamide was grafted to a low extent, the film surfaces were smooth and hence were not modified to any significant extent. But when acrylamide was grafted appreciably, or when styrene was grafted singly or in binary mixture with acrylamide, the surfaces were found to be covered with fibrils. The pattern of the surface modification also changes with the increase of the extent of grafting. The observed properties of the grafted films were explained on the basis of the electron microscopic results.
Synthesis, characterization, and applications of condensate porous polymeric sorbents based on m‐phenylenediamine
Authors: Dave P. J. , Dasare B. D. 
Published: April 2003

AbstractA few condensate porous polymeric sorbents were synthesized based on m‐phenylenediamine–melamine–formaldehyde polycondensation using suitable porosogenic agents. They were characterized for ion‐exchange capacity, bulk density, solvent uptake, pH–titration curve, and rate of exchange. Their surface characteristics were studied using mercury porosimetry, scanning electron microscopy, and the uptake of fast green FCF dye. A selected sorbent was studied for the uptake of phenol in static and dynamic conditions, and the uptake performance was compared with commercially available porous anion exchanger Amberlite‐IRA 93. Results obtained clearly indicated that modified products have higher pore volume, higher surface area, and good ion‐exchange kinetics as compared to the conventional gel type product.
Blends of poly(ethylene terephthalate) and a polyarylate before and after transesterification
Authors: Kimura Masao , Salee Gideon , Porter Rogers S. 
Published: April 2003

AbstractBlends of poly(ethylene terephthalate) (PET) and a copolyester of bisphenol A–terephthaloylisophthaloyl (PAr) (2:1:1) have been studied both before and after transesterification. The physical blends exhibit phase separation in their amorphous states: a pure PET phase and a mixed PAr‐rich phase. In spite of this phase separation, PET crystallinity in blends, normalized to PET fraction, surprisingly goes through a maximum at 25% PAr content. The transesterfied copolymers are noncrystallizable and exhibit a single Tg between those of starting polymers, PET and PAr.
Dielectric relaxation in poly(1,4‐phenylene terephthalamide)
Authors: Murthy U. M. S. , Srinivasan Sriraman , Sobhanadri J. 
Published: April 2003

AbstractThe dielectric behavior of poly(1,4‐phenylene terephthalamide) is reported in this paper as a function of frequency (400 Hz–100 kHz), temperature (30–290°C), and the degree of polymerization (134–228). The general behavior of all the samples of different degrees of polymerization is the same except for the occurrence of the peaks at different positions on the frequency and temperature scales. This difference in behavior could be because of the combined effect of the difference in molecular weights and packing of molecules. The data are completely analyzed for the sample with degree of polymerization n = 210. Two distinct processes are observed, one being observed in the entire temperature range, another orginating in the vicinity of glass transition temperature. The former is analyzed in terms of Cole–Cole distribution and the latter is conformed with a nonexponential decay function. Activation energies are calculated from plots of I/T vs. In τ.
Properties of poly(4‐vinylpyridine‐co‐methyl vinyl ketone) membranes for reverse osmosis
Authors: Oikawa Eizo , Igarashi Yusuke 
Published: April 2003

AbstractThe copolymer prepared from 4‐vinylpyridine and methyl vinyl ketone could form a dense and tough membrane which is stronger than cellulose acetate when crosslinked with malonyl dihydrazide (MD) or 2‐phenyl‐4,6‐dihydrazino‐s‐triazine (PDT), showing a fair performance in reverse osmosis for NaCl and CoCl2 feed. The relationship between the content of MD or PDT and the membrane performance was investigated. An increase in MD or PDT led to an increase in membrane thickness and water content as well as the performance. A maximum rejection was obtained at ca. 30 mol % MD and ca. 13 mol % PDT based on MVK, and a maximum membrane strength at 20–30 mol % crosslinking agent. A membrane of a lower NaCl rejection tended to be permselective due to the complexation of the CoCl2 with membrane. About 1:1 copolymer gave membranes of a higher rejection, which may be related to monomer arrangement in the copolymer chain. There methods for the flux improvement were presented and discussed: preparation of a copolymer blend membrane containing a hydrophilic monomer, crosslinking quaternization of membranes with diiodobutane, and oximation of the membrane material in order to introduce hydrophilic groups.
Enhancement of adhesion between filler and polymer in alumina‐filled rigid polyurethane foams
Authors: Borsus J. M. , Merckaert P. , Jérôme R. , Teyssié Ph. 
Published: April 2003

AbstractThe balance of the reinforcement and flame retardancy of rigid polyurethane foams (PUR) may be envisaged by controlling the dispersion and adhesion of the filler. Encouraging results are reported by grafting onto the filler surface a polymer miscible and reactive with the foam‐forming ingredients. It appears that polyethers may do for PUR foams what the silanes do for glass fiber reinforced plastics.
Flocculation of metal‐bearing waste waters using cellulose and its graft copolymers
Authors: Graczyk T. , Hornof V. 
Published: April 2003

AbstractSeveral types of cellulose (wood pulp) and their graft copolymers with water‐soluble monomers were tested for their activity as flocculation aids. They were employed as additives to lime in flocculation experiments involving a simulated mine water containing iron, zinc, and copper salts. The results show that all the cellulosic products had a beneficial effect on the removal of iron, and to a lesser extent on the removal of zinc. The final concentration of ferric ions after 30 min was comparable with that produced by commercial flocculants (Magnifloc, Aquafloc). No improvement of flocculation activity was obtained upon grafting various polar monomers and their mixtures onto dissolving pulp.
Physical and chemical interaction mechanisms in silicone rubbers
Authors: Štefcová P. , Schätz M. 
Published: April 2003

AbstractSilicone rubbers were prepared with graded concentrations of two different fillers—conventional silica capable of both physical and chemical interactions with the methyl vinyl siloxane polymer and magnetic ferrite powder capable of physical interaction only. The mechanical properties of the experimental rubbers (containing both these fillers at the same time) gave characteristic plots of property isolines in the two filler concentration coordinates. To obtain theoretical counterparts of these plots, physical considerations were used to define the polymer–filler contact surface area in real polymer–filler systems and to derive probable variants of its filler concentration dependence. A mathematical model of the polymer–filler interaction was developed and was explored by computing a series of model diagrams. Comparison of the experimental and computed plots indicated that, even with a chemically active filler present, physical interaction mechanisms are dominant; their contribution in determining the mechanical properties of filled silicone rubbers appears to exceed 93%.
Optimization of nylon 6 reactors with end‐point constraints
Authors: Gupta Santosh K. , Damania B. S. , Kumar Anil 
Published: April 2003

AbstractOptimal temperature profiles for nylon 6 polymerization in plug–flow reactors have been obtained with end‐point constraints involving the degree of polymerization and the cyclic dimer concentration, using the most recent kinetic information. Computations suggest that the temperature at the feed end of the reactor must be maintained close to the highest permissible level (determined by the boiling point of the ϵ‐caprolactam). The temperatures in this region control the degree of polymerization more than other variables. Thereafter, the temperature should be reduced. This second zone controls the undesirable cyclic dimer concentration. The effect of a systematic change of values of the various design variables is studied. The profiles obtained herein are qualitatively similar to those obtained by earlier workers using similar formulations. However, they differ significantly from the profiles obtained by us earlier, using different objective functions which are more relevant to the design of new reactors. Attempts have also been made to obtain a global optimal scheme to produce polymer of a desired degree of polymerization and cyclic dimer content, using as short a reactor as possible, and using the water content and the modifier concentration in the feed as the independent variables.
Properties of cast urethane elastomers prepared from poly(ϵ‐caprolactone)s
Authors: Balas Adolf , Pałka Grzegorz , Foks Janina , Janik Helena 
Published: April 2003

AbstractGeneral information on the methods of lactone polymerization has been given. The method applied in this study for obtaining poly(ϵ‐caprolactone) with the use of sodium derivatives of ethanediol, diethylene glycol, 1,5‐pentanediol, and 1,10‐decanediol has been discussed, and the results of the experiments have been given. The properties of cast urethane elastomers prepared from the obtained poly(ϵ‐caprolactone) have also been presented.
Studies of selective adsorption resins. XVIII. The influence of porosity of macroreticular chelating resin on adsorption of heavy metal ions in an aqueous solution
Authors: Maeda Hironori , Egawa Hiroaki 
Published: April 2003

AbstractIn order to choose the most practical macroreticular chelating resins for the removal and recovery of heavy metal ion from industrial waste solution, the influence of the porosity of macroreticular chelating resins on the adsorption for metal ion was studied. The four macroreticular chelating resins (RST) containing triethylenetetramine side chain with different porosity were used. It was found that the adsorption of zinc ion at its low concentration solution was affected by the porosity of the RST. Among the four resins with average pore radius of 21.0, 24.5, 28.0, and 66.5 nm, a resin with that of 66.5 nm gave the highest initial adsorption rate and the largest breakthrough capacity for zinc ion at a space velocity of 15 h−1.
Swelling of cotton fibers in ethylenediamine–morpholine mixtures
Authors: Lokhande H. T. , Sirmour S. G. , Shukla S. R. , Sinha S. B. , Patil N. B. , Chidambareswaran P. K. 
Published: April 2003

AbstractCotton fibers were treated with anhydrous mixtures of ethylenediamine and morpholine of varying proportions to study the changes in accessibility (X‐ray crystallinity index, swelling by propanol‐2 retention, formylaiton, and dyeability) as well as lattice conversions from cellulose I to cellulose II and cellulose III. Positive synergistic influence of the highest order was noticed at 70:30 (molar proportion 3:1) ethylenediamine–morpholine mixture as judged from accessibility and lattice conversion from cellulose I to cellulose II. The same critical proportion was found to give the highest order of negative synergistic effect in the lattice conversion of cellulose I into cellulose III. These opposing trends have been explained on the basis of the different mechanisms associated with the lattice conversions of cellulose I into cellulose II and cellulose III.
Reprocessing and shear modification of polyethylene
Authors: Ram Arie , Getz Shimon 
Published: April 2003

AbstractReprocessing of used polyethylene serves as a promising solution to a severe ecological and economical problem. This material, however, has frequently been exposed outdoors and demonstrates poor workability and inferior mechanical properties. In this study, we attempt to explore ways for the improvement of flow and product performance by intensive shear processing. When shearing reclaimed polyethylene (LDPE) containing some degree of crosslinking and oxidation, either by repetitive injection molding, extrusion or roll milling, the fluidity of the recycled polymer is gradually increased, frequently with rising ductility of the product and a decrease in melt elasticity. As a result, a practical way of reclaiming poor‐flowing, partially gelled polymer has been found. Additionally, the recycled material can be blended with virgin polyethylene, preferably of the linear low density type. Virgin polyethylene by itself, however, demonstrated an opposite response to intensive shear. There was a drop in fluidity, a rise in melt elasticity, and usually a decrease in ductility. All this is believed to result from the degradation processes that may consist of initiation of microgels and recombination of polymer chains by free radicals, as shown by an actual increase in intrinsic viscosity and in the higher modes of molecular weight averages. It was noted that the controlling mechanism of shear modification of virgin polymer differs from that occurring with a partially crosslinked structure. Results of the shear modification of both virgin and reclaimed polyethylene, by continuous kneading in a Brabender Plastograph, indicate mainly a chain scission mechanism. In all cases the melt viscosity dropped together with the ductility of the final product.
Graft polymerization of propylene sulfide on crosslinked polystyrene
Authors: Domb Abraham , Avny Yair 
Published: April 2003

AbstractSulfur containing graft polymers that may be of interest as polymeric transfer agents were synthesized. Graft polymerization of propylene sulfide on crosslinked polystyrene beads was investigated; both crosslinked polystyrene and its chloromethylated derivative were grafted. Crosslinked polystyrene was metallated by BuLi–TMEDA and was used to initiate anionic graft polymerization of propylene sulfide. Graft polymers of high polypropylene sulfide content corresponding to 10 mmol s/g were obtained. The grafted polypropylene sulfide was evenly distributed across the bead cross section. No change in bead surface characteristics was observed. Grafting on chloromethylated polystyrene beads was achieved by reaction between the chloromethylene groups with sulfide groups of performed polypropylene sulfide, and with terminal sodium thiolate groups of living polypropylene sulfide.
Kinetics of phase separation in segmented polyurethanes
Authors: Chee K. K. , Farris R. J. 
Published: April 2003

AbstractThe phase‐separation process in segmented copolymers is treated by first‐order kinetics which couples with the Fox equation to derive an expression for describing the change of soft segment Tg with the annealing time. Kinetic data of five commercial polyurethanes have been analyzed. The studies conclude that the phase‐segregation mechanisms involve two elementary steps which can be characterized by two discrete relaxation times. It has been shown quantitatively that a polyether‐based polyurethane (ET) recovers its original domain structure faster than a polyester soft‐segment material. The average activation energy of the demixing process of an ET polyurethane is found to be about 23 kJ.mol−1 and is not influenced by hydrogen bonding.
Effect of hollow core on the rigidity of fine fibers
Authors: Gupta Dinesh K. , Broughton Roy M. 
Published: April 2003

AbstractThe principles of torsional and transverse vibrations have been utilized to measure the torsional and bending rigidities of fibers, respectively. A simple device, based on the principle of the torsional pendulum, has been designed to test regular and hollow staple fibers of fine denier. A vibroscope (interfaced with an oscilloscope) was used to measure the linear density of the fibers, and the results were used to calculate their torsional and bending rigidity properties. The effect of hollow core on the torsional and bending rigidities of the fibers is reported.
Polymerization of hexamethyldisiloxane by plasma on activated charcoal: Investigation of parameters
Authors: Akovali G. , Hasirci N. 
Published: April 2003

AbstractThe polymerization of hexamethyldisiloxane by plasma (glow discharge) on activated charcoal was investigated. The effects of discharge power, discharge duration, and monomer flow rate on polymer deposition were examined. Maximum deposition was observed when the applied power, monomer flow rate, and discharge duration were 20 W, 50 cm3/min, and 1 h, respectively. The deposited film was investigated by IR, SEM, and ESCA. The same tests were also carried out for plasma‐induced polymer deposits.
Radiation‐grafted polymers for biomaterial applications. I. 2‐hydroxyethyl methacrylate: Ethyl methacrylate grafting onto low density polyethylene films
Authors: Cohn Daniel , Hoffman Allan S. , Ratner Buddy D. 
Published: April 2003

AbstractStudies were conducted on the radiation grafting of 2‐hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA) by the mutual irradiation technique onto low density polyethylene. Four different solution concentrations were used, and radiation doses ranged from 0.03 to 0.05 Mrad. Four copolymer compositions having different HEMA:EMA ratios were also studied using two total monomer concentrations. The kinetics of the grafting process demonstrated by the two monomers were basically different. While EMA showed a typical diffusion‐controlled kinetic pattern, HEMA exhibited a more complex behavior, the main features of which were an induction period, a slight autoacceleration and a significant drop in graft level after a maximum is reached. The difference in behavior was interpreted in terms of partitioning of monomers into the polyethylene substrate. The surface topography of the grafted films was studied by means of scanning electron microscopy. A mechanism based on osmotic cell formation was suggested for the HEMA graft system. The copolymer systems investigated showed that the graft reaction is faster in the initial stages for higher percentages of EMA in the monomer mixtures; as grafting proceeds the trend is reversed.
Control of ionic interactions in sulfonated polystyrene ionomers by the use of alkyl‐substituted ammonium counterions
Authors: Weiss R. A. , Agarwal P. K. , Lundberg R. D. 
Published: April 2003

AbstractPolystyrenes containing up to about 20 mol % sulfonic acid are reproducibly and readily prepared by the sulfonation of polystyrene at 50°C with acetyl sulfate in 1,2‐dichloroethane solution. The metal salts of sulfonated polystyrene possess extremely high melt viscosities and are soluble in single solvents such as toluene and THF only at very low sulfonate levels. Such properties are the result of the very strong ion‐dipole interactions among the metal sulfonate groups. Such strong interactions can be substantially reduced through the neutralization of the sulfonic acid with ammonia and, most especially, relatively simple low molecular weight amines. Sulfonated polystyrenes varying in sulfonic acid content from about 1 mol % to about 20 mol % were neutralized with various mono‐, di‐, and tri‐substituted alkyl amines ranging in alkyl chain length from H (ammonia) to C20, and their rheological and thermal properties were measured. As the number of substituents on the nitrogen increased, the glass transition temperature and the melt viscosity decreased. The tributylamine sulfonates possessed viscosities almost as low as unsulfonated polystyrene and the longer chain amines behaved as if internally plasticized. The properties of amine neutralized sulfonated polystyrenes are concluded to be primarily a function of amine size. Increasing the size of the amine reduces the strength of the ion‐dipole interaction by preventing close approach of the amine sulfonate groups.