bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the reaction of bis(diisopropyl) thiophosphoryl disulfide with silica in the vulcanization of NR
Authors: Mandal Swapan Kumar , Datta Rabindra Nath , Das Prasanta Kumar , Basu Dipak Kumar 
Published: April 2003

AbstractThe reaction between bis(diisopropyl) thiophosphoryl disulfide (DIPDIS) and silica has been investigated. The study reveals that DIPDIS can be used as a coupling agent for silica. The chemical bond between the silanol groups of silica and DIPDIS has been established through the isolation and characterization of isopropyl alcohol that is eliminated from the reaction. The chemical nature of the bond is also supported by the IR analysis of the reaction products of silica and DIPDIS obtained both in the presence and absence of rubber. From the exploratory studies it is indicated that DIPDIS can also react with NR even during mixing of ingredients. When used with 2‐mercaptobenzothiazole (MBT) or N‐oxydiethylene‐2‐benzothiazole sulfenamide (OBTS) in the presence of silica, DIPDIS exhibits notable activation of cure and enhances the torque, modulus, tensile strength, and the scorch safety.
Stress relaxation and the domain structure of thermoplastic elastomer
Authors: Hsiue Ging‐Ho , Chen Der‐Jang , Liew Yeong‐Kang 
Published: April 2003

AbstractThe relationship between the stress relaxation phenomena and domain structure of thermoplastic elastomer (TPE) was studied. Two representative thermoplastic elastomers: styrenebutadiene‐styrene block copolymer (SBS) and 1,2‐syndiotactic polybutadiene (1,2‐PB), representing the amorphous glassy domain and crystalline domain, respectively, were tested in different atmospheres and temperatures. Results show that the structure of the domain has a significant effect on the stress relaxation curve. It is found that the way the glassy domain is formed determines the failure of the domain and hence the stress relaxation rate. In the case of crystalline domain, the history of heat treatment determines the crystal structure and, in turn, the stress relaxation rate.
Reactive extrusion of polypropylene I: Controlled degradation
Authors: Suwanda D. , Lew R. , Balke S. T. 
Published: April 2003

AbstractPolypropylene was degraded by injection of a free‐radical initiator during extrusion. Molecular weight distribution, molecular weight averages, and melt flow index were measured to see the effect of initiator concentration (0.00 to 0.04 wt%), temperature (200 and 220°C), and screw rpm (31 and 44). Initiator concentration was the most significant variable. In all cases, increased initiator concentration degraded the high molecular weight tail of the polypropylene and narrowed the molecular weight distribution. Melt flow index varied linearly with initiator concentration beyond 0.01 wt% initiator. Reaction temperature had no effect on the measured properties of the extrudate. This was attributed to the minimum residence time in the extruder being sufficient for all degradation reactions to be completed. It also implied that the same reactions occurred at both temperatures. Increased screw rpm slightly increased molecular weight. No interaction among initiator concentration, temperature, and screw rpm was observed.
Modeling reverse osmosis separations with strong solute‐membrane affinity at different temperatures using the finely porous model
Authors: Connell P. J. , Dickson J. M. 
Published: April 2003

AbstractThe reverse osmosis separation of toluene from water has been studied using an asymmetric cellulose acetate membrane at different temperatures, pressures, and feed concentrations. The finely porous transport model is used to describe the performance of the membrane as a function of the operating conditions. Based on experimental data, the transport parameters for the membrane are estimated. These parameters include the pore size of the membrane, the frictional parameter for the solute in the membrane pore, the relative porosity of the membrane surface, and the partition coefficients on the high and low pressure sides of the membrane. The influence of operating temperature on some of these parameters is presented and discussed. A modified form of the finely porous model which includes the effect of temperature is presented.
Investigation on the long‐term behavior of polyethylene and poly(vinyl chloride) under static load
Authors: Natov M. , Vassileva St. , Evtimova S. 
Published: April 2003

AbstractThe long‐term behavior of high density polyethylene (HDPE) and poly(vinyl chloride) (PVC) under static mechanical load is investigated. The long‐term behavior is determined as a function of stress and temperature. The applicability of the equation proposed by the authors which describes the dependence between the time‐dependent failure, stress, and temperature of the two polymers is examined. The equation, derived on theoretical considerations, represents a modification of the Arrhenius equation for the chemical reaction rate. It is found that there is a complete agreement between the experimentally determined long‐term behavior of PVC and HDPE and that calculated by the equation over the whole examined range of temperatures and stresses, with the exception of narrow intervals for HDPE where an intensive plastic deformation is developed.
Microstructural investigations of PBT/nylon 6,6 composites
Authors: Néhmé O. A. , Gabriel C. A. , Farris R. J. , Thomas E. L. , Malone M. F. 
Published: April 2003

AbstractThe microstructure of composites made from blends of poly(p‐phenylene benzobisthiazole) [PBT] and nylon 6,6 has been investigated with wide‐angle X‐ray diffraction, selected area electron diffraction, and small‐angle X‐ray scattering techniques. The composite samples investigated were spun in both fiber and film forms dilute solutions of methane sulfonic acid.The structure of the composites was found to be a microfibrillar network of PBT in a matrix of partially crystalline nylon 6,6. The diameters of the PBT microfibrils were in the range of 30 to 70 Å.
The fibrillar structure of cellulosic man‐made fibers spun from different solvent systems
Authors: Lenz J. , Schurz J. , Wrentschur E. 
Published: April 2003

AbstractThe development of new methods of spinning cellulosic fibers requires a better understanding of their fibrillar structure in order to explain their special physical properties. By means of transmission electron microscopy (TEM), light microscopy (LM), small‐angle X‐ray scattering (SAXS), and wide‐angle X‐ray diffraction (WAXD) it is shown that six different kinds of regenerated cellulosic fibers consist of uniform elementary fibrils composed of cellulose‐II crystals. Systematic distinctions between these fiber types are found with regard to the aggregation of the elementary fibrils to nonswelling bundles or clusters. The clusters differ from each other in diameter, length, and frequency of occurrence.
Crystallization of cellulose
Authors: Paralikar K. M. , Aravindanath S. 
Published: April 2003

AbstractCrystallization of cellulose from low DP acetylated hydrolyzed bagasse pulp has been studied. The morphology of the crystals obtained after crystallization at 50°C for different intervals of time (5, 20, and 40 days) revealed needle‐shaped, elongated, ribbonlike fibrous crystals. The electron diffraction pattern obtained on these crystals was typical of cellulose II lattice.
Low temperature exotherm in starch/water systems: A retrogradation marker
Authors: Kwak Yoon Tae , Winter William T. 
Published: April 2003

AbstractDSC measurements at slow ( < 1.0°C min−1) heating speeds reveal a crystallization exotherm in the −4‐−6°C region for starch/water systems. The same exotherm is not observed for other polysaccharides such as guar and is sensitive to chemical modification of the starch sample. The DSC thermograms have been interpreted in terms of three different levels of water organization in the starch matrix.
Grafting of methyl methacrylate onto guar gum by hydrogen peroxide initiation
Authors: Raval Dipak K. , Patel Ranjan G. , Patel Vithal S. 
Published: April 2003

AbstractGraft copolymerization of methyl methacrylate (MMA) onto guar gum (GG) in aqueous slurry has been carried out using hydrogen peroxide (H2O2) as initiator. The copolymers were characterized by infrared spectroscopy. The grafting parameters like percent grafting, grafting efficiency, percent add‐on, and the grafting frequency were determined, and the effect of reaction time, concentration of initiator, and [GG]/[MMA] ratios on the grafting parameters have been discussed. The decrease in % add‐on at increasing concentration of H2O2 indicated enhancement in the rate of homopolymerization of methyl methacrylate.
A method for calculating dynamic mechanical properties using fourier transforms of pulse deformation experiments
Authors: Vratsanos Menas S. , Farris Richard J. 
Published: April 2003

AbstractA general method for determining the dynamic mechanical properties of a material is presented. It involves Fourier transforms of the stress and strain responses of a material subject to arbitrary deformation. As an example, uniaxial pulse‐strain deformations were used to calculate the dynamic properties of a cured epoxy. A comparison of the properties calculated from uniaxial sinusoidal deformations and those obtained by Fourier transform analysis of the uniaxial pulse‐strain indicate excellent agreement over a wide range in mechanical behavior. These results suggest that dynamic mechanical properties may be obtained when deformations other than that of a sine wave are used.
Thermogravimetric/mass spectrometric characterization of the thermal decomposition of (4‐O‐methyl‐D‐glucurono)‐D‐xylan
Authors: Šimkovic Ivan , Varhegyi Gabor , Antal Michael J. , Ebringerová Anna , Szekely Tamas , Szabo Piroska 
Published: April 2003

AbstractA thermogravimetric/mass spectrometric (TG/MS) system was used to characterize the thermolysis reactions of (4‐O‐methyl‐D‐glucurono)‐D‐xylan. The mass spectrometric peaks, measured as function of time, were attributed to water, methanol, carbon monoxide, carbon dioxide, formaldehyde, formic acid, acetic acid, acetone, acrolein, 2‐furaldehyde, and 3‐hydroxy‐2‐penteno‐1,5‐lactone. The time derivative of the thermogravimetric curve (DTG) consisted of two partially overlapping peaks, indicating a multistep mechanism. The mass spectrometric intensities of the peaks assigned to methanol and 2‐furaldehyde coincided with the first DTG peak, suggesting that the first DTG peak represents both dehydration and fragmentation pathways. Methanol, water, formyl group, and carbon dioxide contributed to both of the DTG peaks. This indicates that the dehydration, decarboxylation, and decarbonylation took place in two steps. The compounds observed only in the second DTG peak and later (acetone, formic acid, formaldehyde, acrolein, acetic acid, and 3‐hydroxy‐2‐penteno‐1,5‐lactone) are probably products of reactions which occur after the collapse of the original polysaccharide structure.
Micromechanical properties of polyether block amide copolymers
Authors: Alberola Nicole 
Published: April 2003

AbstractA series of polyether block amide copolymers based on poly(tetramethylene oxide) of molecular weight 1000 or 2000 and polyamide 12 of molecular weight between 600 and 4000 with varying PE/PA weight ratio (from 80 to 20%) were studied by using dynamic mechanical spectroscopy and differential scanning calorimetry. Dynamic mechanical experiments showed three main relaxation peaks related to, the subglass transition of the soft segments, the glass transition of the soft segments, and the glass transition of the hard segments. A quench, carried out on a 70% PA copolymer from 110 to 15°C, leads to a decrease in the storage modulus. This result should be related to the destruction of physical ties.
Morphology of composite film prepared by polymerizing styrene in poly(vinyl chloride) film
Authors: Mizutani Yukio , Nishimura Toshihiko , Nishimura Masakatsu 
Published: April 2003

AbstractStyrene and the styrene‐additive mixtures (kerosene, dioxane, ethylene dichloride, or dioctylphthalate) were soaked into a poly(vinylchloride) film and then styrene was polymerized. Subsequently, poly(styrene) was extracted with CCl4 and the microporous membrane was obtained, of which the morphology was studied. It is elucidated that the additives affect the morphology of the resultant composite films.
Processing–property interactions in poly(vinylidene fluoride). I. An analysis of melt stress history in an extensional flow geometry
Authors: Khomami B. , McHugh A. J. 
Published: April 2003

AbstractA numerical and experimental analysis of the melt flow history of poly(vinylidene fluoride), PVF2, in an extensional flow, film‐processing geometry is presented. Numerical computations were carried out for both Newtonian and power law flow in an impinging channels die using a finite‐element technique. Computations demonstrate that a strong extensional flow exists in the region from the stream impingement point to a distance about 0.75 D downstream where D is the channel height at the impingement point. Measurements of the stress fields using the technique of flow birefringence showed that in consequence of the changing flow kinematics from the stream impingement region to the downstream converging channels region, both the isochromatic and isoclinic patterns exhibit a pronounced axial positional dependence. Excellent qualitative and quantitative agreement was found between measured and calculated shear stress fields. However, large differences were exhibited between calculated and measured normal stress differences along the symmetry axis of flow. Results to be presented in a companion paper (Part II) demonstrate that the strong extensional flow which occurs in this geometry is sufficient to produce oriented, row‐nucleated structures in the extruded PVF2 films.
The role of hindered piperidine (HALS) compounds for the stabilization of polypropylene against oxidation reactions caused by ozone and oxidative products formed during photolysis of ozone
Authors: Lucki J. , Rabek J. F. , Rånby B. , Watanabe Y. 
Published: April 2003

AbstractThe role of hindered piperidine (HALS) photostabilizers for the photostabilization of polypropylene films against oxidative reactions caused by ozone and oxidative species formed during photolysis of ozone under UV irradiation (i.e., atomic oxygen and singlet oxygen) has been investigated and discussed. It has been found that ozonization and/or photoozonization of 2,2,6,6‐tetramethyl‐piperidine (I) and piperidinoxy radical (2,2,6,6‐tetramethylpiperidino‐1‐oxy) (II) gives a high yield (91–98%) 2,6‐dimethyl‐2‐hydroxy‐6‐nitro‐heptane. Ozonization and/or photoozonization of HALS probably occur by a similar mechanism as reported for (I) and (II). HALS photostabilizer reacts with ozone and/or photolysis products of ozone (atomic oxygen and/or singlet oxygen) and loses its function in the photostabilization process. For that reason protection of polypropylene against photooxidative degradation and photoozonization is of great commercial importance.
Characterization of rubber particle size distribution of high‐impact polystyrene using an image analysis method
Authors: Hall R. A. 
Published: April 2003

AbstractAccurate characterization of high‐impact polystyrene (HIPS) rubber particle size distribution has been achieved using an automatic image analysis system. The new method involves preparation of a microscope slide consisting of a dilute suspension of HIPS particles in a polymer matrix. Images of silhouetted rubber particles of true diameter are obtained using an image processor and particle size calculations can be made with a minimum of editing of the binary image. The new method provides measurement of true rubber particle diameters because the particles in the prepared slide are not swollen by any solvent.
Stirring‐induced solution crystallization of ultra high molecular weight polyamide 6
Authors: Doppert H. L. , Van Dijk J. G. 
Published: April 2003

AbstractUnstable solutions of ultrahigh molecular weight polyamide 6 have been prepared by adding a nonsolvent to the polymer solution. Crystallization of the polyamide from such a solution proceeds very slowly. It has been found, however, that vigorous stirring of the unstable solutions induces rapid fibrous crystallization of the polymer. The fiber mat consists of irregularly shaped fibers. A low temperature and a high stirring rate are among the conditions necessary to obtain a high yield of fibrous material. The fibers formed upon stirring have a higher molecular weight than the polyamide 6 molecules which remain in the solution. The melting point of the fibers depends on the speed of the paddle stirrer. The differential scanning calorimetry (DSC) thermogram reveals higher melting temperatures of the fibrous material if higher stirring rates have been applied.
The equilibrium water content of some thermoplastic hydroxyalkyl methacrylate polymers
Authors: Stevenson W. T. K. , Sefton M. V. 
Published: April 2003

AbstractThe equilibrium water content (EWC) of thermoplastic 2‐hydroxypropyl methacrylate and 2‐hydroxyethyl methacrylate homopolymers from technical grade monomer and of copolymers of the latter with methyl methacrylate has been measured in distilled water and in phosphate‐buffered saline (PBS). In distilled water, as expected, EWCs increased monotonically with the proportion of hydrophilic monomer in the polymer and showed only a small dependence on molecular weight. In contrast, the degree of swelling (and in some cases dissolution) and “freezable” water content of polymers in PBS were shown to be anomalously high and to be a consequence of ionization at pH 7.4 of methacrylic acid incorporated into the polymer in small quantity (< 1 mol %) as an impurity. Initial studies indicated a strong relationship between copolymer molecular weight and small molecule permeability in distilled water.
Recovery of uranium from seawater. VI. Uranium adsorption ability and stability of macroporous chelating resin containing amidoxime groups prepared by the simultaneous use of divinylbenzene and ethyleneglycol dimethacrylate as crosslinking reagent
Authors: Nakayama Morio , Uemura Keiji , Nonaka Takamasa , Egawa Hiroaki 
Published: April 2003

AbstractMacroporous chelating resins (RNH‐DVB‐1G) containing amidoxime groups with various degrees of crosslinking were synthesized by varying the amount of divinylbenzene (DVB) and ethyleneglycol dimethacrylate (1G). It was confirmed that the content of amidoxime group decreased with an increase in the degree of crosslinking. On the other hand, the amount of amidoxime group hydrolyzed by acid treatment showed a tendency to decrease with an increase in degree of crosslinking. From the measurement of specific surface area and pore size distribution, it was found that the macropore of RNH‐DVB‐1G with the same degree of crosslinking was remarkably affected by the composition of crosslinking reagent (DVB and 1G). The RNH‐DVB‐1G prepared in the present work were applied to the recovery of uranium from seawater. It was found that the uranium adsorption ability of RNH‐DVB‐1G with the same degree of crosslinking was remarkably affected by the proportion of DVB and 1G, although each RNH‐DVB‐1G had the same content of amidoxime group. In the case of RNH‐DVB‐1G prepared with 25 mol% of crosslinking reagent, the resin prepared with 10 mol% of DVB and 15 mol% of 1G showed the high adsorption ability for uranium in seawater. These results indicate that the simultaneous use of DVB and 1G contributes to the formation of effective macropore and micropore for recovery of uranium from seawater and the increase of chemical and physical stability.
Surface‐modified polysulfone hollow fibers
Authors: Higuchi Akon , Iwata Noboru , Tsubaki Masayuki , Nakagawa Tsutomu 
Published: April 2003

AbstractControlled reactions on the inner side, outer side, and both sides of the surfaces of polysulfone ultrafiltration hollow fibers with propane sultone and Friedel‐Crafts catalysts were developed. EPMA measurements and MTR spectra for the chemically modified fibers suggested existence of CH2CH2CH2SO3− segments on the modified surfaces. The modified fibers were found to have smaller molecular weight cut‐off than nonmodified fibers, and the fibers modified on the internal surfaces gave better rejection of polyethylene glycol 6000 than those modified on the external surfaces, although the fibers that reacted with solution of the propane sultone and SnCl4 at 70°C and 80°C showed negative rejection of the polyethylene gylcol. Absorption of polyethylene glycol on the modified fibers is estimated to be less than the nonmodified fibers from the flux ratios of aqueous polyethylene glycol solution to pure water. This effect is attributed to the heparinlike active group of modified segments.
Diffusional aspects for the chlorination of the sulfonated poly(styrene‐co‐divinylbenzene) resin beads
Authors: Ihm Son‐Ki , Ahn Jou‐Hyeon , Widdecke Hartmut , Struß Klaus , Klein Joachim 
Published: April 2003

AbstractThe diffusional process in the chlorination of sulfonated poly(styrene‐co‐divinylbenzene) bead was investigated through a general model as well as direct observation with electron microprobe. Two modes of diffusion, namely the pore diffusion and gelular permeation, were analyzed by two system parameters through a two‐phase model. The effective pore and gelular diffusivities estimated from the x‐ray energy‐dispersive analysis data on the chlorine profile and the conversion suggest that, even for the same crosslinking, the diffusivity of chlorine in the gelular bead is larger by several orders of magnitude than that for the gelular microparticle in the macroreticular bead.
Miscibility in poly‐p‐phenylene terephthalamide/nylon 6 and nylon 66 molecular composites
Authors: Kyu Thein , Chen Tsuey Ing , Park Ho‐Sung , White James L. 
Published: April 2003

AbstractMiscibility and crystallization of poly‐p‐phenylene terephthalamide (PPTA)/nylon 6 and nylon 66 composites prepared by coagulation of isotropic ternary sulfuric acid solutions were studied. The apparent crystallinity of nylon 6 and nylon 66 in molecular composites was investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy. The solvation of nylon 6 crystals in PPTA matrix was observed when the PPTA content exceeds 70 wt%. Cross‐hydrogen bonding seems to be responsible for the virtual disappearance of nylon 6 crystals. Specific interaction between PPTA and nylon 6 macromolecules and phase separation during thermal treatment has been discussed.
Distribution of MBS emulsion particles in immiscible polystyrene/SAN blends
Authors: Fowler M. E. , Keskkula H. , Paul D. R. 
Published: April 2003

AbstractThe effect of mixing technique and sequence on the distribution of methacrylated‐butadienestyrene (MBS) emulsion particles in immiscible blends of polystyrene (PS) and a styrene/acrylonitrile copolymer (SAN) was examined using transmission electron microscopy. The shell of the emulsion particle is essentially poly(methyl methacrylate) (PMMA), which is miscible with SAN but immiscible with PS. In simple thermodynamic terms, the MBS particle should have an affinity for SAN over PS. It was found, however, that the sequence of mixing had a strong influence on the location of the MBS particles. If the PS‐SAN interface is established before the addition of the MBS particles, the MBS particles are located exclusively in the SAN phase. If the MBS particles are present at the time the PS‐SAN interface is formed, then the particles line up at the interface.