bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grafting fluorocarbons to polyethylene in glow discharge
Authors: Yagi Toshiharu , Pavlath Attila E. , Pittman Allen G. 
Published: April 2003

AbstractA systematic surface fluorination of high‐density polyethylene was carried out using CF4, CF3H, CF3Cl, and CF3Br, in a radio‐frequency glow discharge. Based on ESCA and wettability measurements, all of these compounds provided a fluorocarbon layer on high‐density polyethylene surface, but the fluorine to carbon ratio and extractability of the films were strongly dependent on the starting materials and the location of the sample specimen in the reactor chamber as well as the duration of the reaction. The results with vertically held, CF3H‐treated samples showed a high level of nonextractable surface fluorination and very little change in wetting properties before and after extraction with CF2ClCFCl2.
Synthesis and studies of phosphorus‐containing polyurethane foams based on tetrakis(hydroxymethyl) phosphonium chloride derivatives
Authors: Sivriev Hristo , Borissov Georgij , Zabski Leszek , Walczyk Wladyslaw , Jedlinski Zbigniew 
Published: April 2003

AbstractA phosphorus‐ and nitrogen‐containing polyl is prepared by condensing tetrakis(hydroxymethyl)phosphonium chloride with diethanol amine in aqueous medium. The newly synthesized polyol‐bis(hydroxymethyl)‐N, N‐bis(2‐hydroxyethyl)aminomethylphosphine oxide (AMPO) is used in the preparation of rigid polyurethane foams with a various phosphorus content. With the view to comparing their properties, polyurethane foams are also prepared on the basis of the commercially available flame retardant diethyl‐N, N‐bis(2‐hydroxyethyl)aminomethylphosphonate (Fyrol 6). The flammability, thermal stability, and thermoechanical properties of the polyurethane foams obtained are studied. A certain difference in the behavior of the two modified polyurethane foams is observed. The polyurethane foams with AMPO exhibit a slight increase in the resistance to combustion (oxygen index) and a noticeable improvement in the thermal and mechanical properties. These differences probably arise as a result of structural and functional differences between the two types of phosphorus‐containing flame retardants.
Chelating resin: Pyridine derivatives attached to poly(styrene) beads with spacer group
Authors: Nishide Hiroyuki , Shimidzu Naoki , Tsuchida Eishun 
Published: April 2003

AbstractThe pyridine derivatives were combined to poly(styrene) beads with spacer groups or a graft chain. These spacer‐type and graft‐type pyridine beads formed their Cu complexes with high rates and large stability constants; they act as an effective chelating resin. The pyridine residues were more mobile due to the spacer group and the graft chain, compared with the poly(4‐vinylpyridine) powder.
Chlorinated hydrocarbon coupling agents for mica–polypropylene composites
Authors: Garton A. , Kim S. W. , Wiles D. M. 
Published: April 2003

AbstractThe incorporation of small amounts of a chlorinated hydrocarbon wax into polypropylene (PP) when making mica–PP composites is shown to produce a layer of degraded chlorinated hydrocarbon at the interface between the polymer and the reinforcement. Mica is shown to accelerate the thermal degradation of the chlorinated hydrocarbon, and the chlorinated hydrocarbon, or its degradation products, are shown to react with hydrocarbon analogues of the polymer. As well as modify the chemical nature of the interface, the layer of degraded chlorinated hydrocarbon is shown to modify the morphology of the interface by inhibiting the ability of the mica to nucleate the crystallization of PP from the melt.
Urethane‐based stabilizers for radiation‐crosslinked polyethylene
Authors: Shkolnik S. , Rajbenbach L. A. 
Published: April 2003

AbstractUnsaturated urethane‐based stabilizers for use in radiation‐crosslinked polyethylene were synthesized. Aromatic amine moieties were attached to allylic and acrylic monomers by means of aromatic or aliphatic diisocyanates. The synthesized stabilizers were incorporated in high‐density polyethylene films which were subjected to electron beam irradiation. The oxidative stability of the films prior to and after extraction was determined by DTA in the temperature range 185–210°C and compared with samples treated with commercial amine‐bearing antioxidants. Tensile strength and gel content were also determined. Best results were obtained with a stabilizer prepared from equimolecular amounts of allyl alcohol, tolylene‐2,4‐diisocyanate and N‐phenyl‐1,4‐phenylenediamine. Estimated lifetimes at 70°C of stabilized irradiated polyethylene samples were calculated.
Catalysis of the reaction between isocyanates and protonic substrates. III. Influence of the addition of a cosolvent on the polyurea foaming process
Authors: Merckaert P. , Jérôme R. , Teyssié Ph. 
Published: April 2003

AbstractPolyurea foams can be produced from nonmiscible water and polyisocyanates. The addition of a cosolvent improves the homogeneity of the reaction medium and enhances the effectiveness of any catalyst, preferably soluble in water. Cosolvents, exhibiting an intrinsic catalytic activity, display a regulating effect on the rise profile of the foams and allow for defining performant and less expensive formulations.
Finite‐element and boundary‐element analysis of craze micromechanics
Authors: Bevan L. 
Published: April 2003

AbstractThe two numerical methods are used to estimate craze surface displacements and stresses for both isolated crazes and crazes at crack tips. The results are compared with the predictions of craze micromechanics models. The investigation includes the computation of the craze surface stress profile required to maintain a given craze opening displacement profile. The boundary element program requires less computer time than the finite element one, and similar results are obtained. The analysis also considers the craze surface displacement profile corresponding to an assumed craze surface stress distribution. The element methods produce results which are approximately the same as those obtained using the model of Verheulpen‐Heymans and Bauwens.
Modelling of reversible poly(ethylene terephthalate) reactors
Authors: Kumar A. , Gupta S. K. , Gupta B. , Kunzru D. 
Published: April 2003

AbstractThe second stage of batch poly(ethylene terephthalate) (PET) reactor with bis(2‐hydroxyethyl) terephthalate (BHET) as the feed has been simulated. In this stage, the overall polymerization is not diffusion limited and is known to be a complex reaction. In this work it has been assumed to consist of polycondensation, reaction with monofunctional compounds (cetyl alcohol), redistribution, and cyclization reactions. The forward and reverse steps of each of these have been modelled in terms of the rate constants involving functional groups and the reacted bonds. The equations for the calculation of the molecular weight distribution (MWD) in batch reactors have been written and solved numerically. The MWD reported in this work is assumed to include the monofunctional products only, and, for the case where ethylene glycol is not removed from the reaction mass, it was found to be unaffected by the choice of the redistribution rate constant (kr). Since the removal of ethylene glycol is not mass transfer controlled, its concentration in the reaction mass is assumed be given by the vapor–liquid equilibrium existing at the pressure applied on the reactor. In this work, the level of ethylene glycol concentration, yg ([G]/[P1]0), has been taken as a parameter, and, on application of vacuum, the MWD results were found to vary with kr with the sensitivity increasing with yg. It was then shown that the importance of the redistribution reaction is enhanced when the cyclization reaction also occurs. The effect of vacuum on the performance of the reactor has been studied by varying yg. For yg less than 0.01, the change in the MWD of the polymer becomes very small. The effects of polymerization temperature and initial concentration of monofunctional compounds on MWD were found to be small.
Dilute solution behavior of a cationic polyelectrolyte
Authors: Kienzle‐Sterzer Carlos , Rodriguez‐Sanchez Dolores , Rha Chokyun 
Published: April 2003

AbstractDilute solution behavior of a cationic polyelectrolyte was studied with respect to acetic acid concentration using chitosan. The reduced viscosity, ηsp/C, of chitsan solutions increases with a decrease in the polymer concentration. For a given polyelectrolyte concentration, the specific viscosity is higher at lower acid (acetic) concentration, indicating the expansion of the polyelectrolyte chain due to electrostatic repulsion as a result of the interactions between chitosan and the solvent. The relationship between intrinsic viscosity [η]∞ and acetic acid concentration suggests no conformational transition of the chitosan molecules and possible formation of intramolecular hydrogen bonds during the shrinking of the hydrodynamic domain of the polyions.
Aging and performance of structural film adhesives. I. A comparison of two high‐temperature curing, epoxy‐based systems
Authors: Pearce P. J. , Davidson R. G. , Morris C. E. M. 
Published: April 2003

AbstractThe room temperature aging of two epoxy adhesives, both of which are cured at 177°C and contain the moisture sensitive resin triglycidyl (4‐aminophenol), has been examined. It has been found that hydrolysis of this resin is the major cause of reduction in epoxide content during aging. This in turn is largely responsible for the deterioration in the performance, especially at high temperatures, of bonded joints made with aged adhesive. The advantages of using high purity resins in adhesive formulations have been demonstrated.
Viscoelastic behavior of segregated networks
Authors: Lipatov Yu. S. , Rosovizky V. F. , Maslak Yu. V. 
Published: April 2003

AbstractTemperature dependences of real E′ and imaginary E″ parts of the complex dynamic modulus for new types of so‐called segregated networks were investigated. These networks are formed by three different elastic active network chains which chemically interact one with another, distinct from interpenetrating networks. Networks based on oligourethane acrylate, methyl methacrylate, methacrylic acid, and epoxy resin taken at various ratios were investigated. The viscoelastic characteristics were determined on different stages of the network structure formation. For such networks, a very wide peak E″ is typical, which is connected with a high degree of microphase segregation. The mutual influence of the constituent networks on their relaxation maxima was observed.
Graft copolymerization of methyl methacrylate onto wool using thallium (III) ions as initiator
Authors: Misra Sivananda , Sahu Gangadhar 
Published: April 2003

AbstractThe graft copolymerization of methyl methacrylate onto wool initiated by thallium (III) perchloric was investigated in aqueous perchloric acid medium. The rate of grafting was evaluated varying the concentrations of the monomer, initiator, acid, and temperature. The rate of grafting was found to increase with the increase of the monomer and the initiator concentration. The graft yield was found to decrease upon increasing the acid concentration. Increase of temperature was accompanied with the increase of the graft yield. From the Arrhenius plot the overall activation energy was calculated to be 4.7 kcal/mol. The effect of inhibitors, various solvents, cationic and anionic surfactants, and different inorganic salts on the graft yield was studied. The grafting was considerably influenced by chemical modification of wool prior to grafting. A suitable kinetic scheme has been proposed, and a rate equation has been derived.
Saccharification of douglas‐fir wood by a combination of prehydrolysis and pyrolysis
Authors: Shafizadeh Fred , Stevenson Thomas T. 
Published: April 2003

AbstractA process has been investigated for the saccharification of wood, involving prehydrolysis, lignocellulose pyrolysis, and tar hydrolysis. In this process, ground wood was first prehydrolyzed to remove the more readily hydrolyzable hemicelluloses. The residual lignocellulose was then pyrolyzed rapidly to provide a tar containing levoglucosan and its condensation products. The tar was hydrolyzed to convert these products to glucose. Laboratory experiments have shown that this process can convert a common softwood such as Douglas‐fir to 14% char and 42% hexoses. This amounts to a 59% recovery of the hexoses: 32% from prehydrolysis and 27% from pyrolysis. The prehydrolysis served not only to remove hemicelluloses, but also to increase the yield of glucose from pyrolysis and subsequent tar hydrolysis. It has been shown that this enhancement is due to the removal of inorganic ash and the catalytic effect of trace amounts of acid remaining in the lignocellulose.
Fourier‐transform infrared study of uniaxially oriented polytetrafluoroethylene
Authors: Yeung C. K. , Jasse B. 
Published: April 2003

AbstractInfrared measurements of the dichroic ratio of polytetrafluoroethylene absorption bands provide a valuable method of determination of the orientation of chains as well in crystalline regions as in amorphous ones. The 1452 cm−1, 1545 cm−1, and 2362 cm−1 combination bands are convenient for measuring crystalline orientation while the 703 cm−1, 740 cm−1, and 786 cm−1 bands lead to amorphous orientation. The 1795 cm−1 (crystalline), 720 cm−1, and 774 cm−1 (amorphous) absorption bands are shown to be complex ones and thereby unusable for measuring orientation.
One‐point determination of intrinsic viscosity for polycarbonate, poly(phenylene oxide), and polyetherimide
Authors: Nero John R. , Sikdar Subhas K. 
Published: April 2003

AbstractIntrinsic viscosity determination for polymers can be simplified and considerable time and effort saved via a single measurement of relative viscosity at a known concentration. Several workers have proposed one‐point intrinsic viscosity methods. Of the methods in the literature, two one‐point methods were found to be as accurate as the multiple‐point graphical extrapolation procedure. These two methods, one due to Solomon and Ciuta and a nomographic technique due to Khan and Bhargava, were successfully applied for the intrinsic viscosity determination of three polymers: polycarbonate, poly(phenylene oxide) and polyetherimide.
Microencapsulation of water‐soluble materials using a copolymer of poly(vinyl chloride)
Authors: Safdy Max E. 
Published: April 2003

AbstractMicroencapsulation of aqueous materials by the technique of organic phase separation using copoly(vinyl chloridevinyl alcoholvinyl acetate) (91:3:6% by weight) resulted in microcapusules which were isolable as a free‐flowing powder and were storable after drying. Using a dye marker in the core, the dried microcapsules were found to release the core contents through the spherical wall membrane in the presence of an exogenous aqueous medium. A technique was found for conveniently coating the dried microcapsules onto filter paper, and the partial constituents of an indicator system were encapsulated and coated onto filter paper pretreated with the complementary color‐forming constituents. The rate of color development in the wetted paper‐microcapsule system was used to assess the relative rate of release of the microcapsule core contents. Crosslinking of the poly(vinyl chloride) copolymer prior to encapsulation resulted in an attenuation of release of the microcapsule core contents.
Neutral organophosphoryl methyl ester–metal chloride interactions as applied to the dechlorination of catalyst residues in polypropylenes prepared by solventless processes
Authors: Karayannis Nicholas M. , Khelghatian Habet M. , Skryantz John S. 
Published: April 2003

AbstractA novel method of dechlorinating catalyst residues in polypropylenes prepared by solventless processes is reported. The method is based on the reaction of the metal chlorides present in these residues with neutral organophosphoryl methyl esters, such as trimethyl phosphate and dimethyl methylphosphonate. These reactions lead to the formation of M[OP(O)(OCH3)2]n or M[OP(O)(CH3)(OCH3)]n complexes, with evolution of the chloride in the form of methyl chloride. Experimental evidence presented demonstrates that inclusion of one of the preceding esters in the stabilizer package of polypropylene powders prepared by the bulk polymerization process and containing 300–650 ppm Cl, followed by extrusion and pelletization, can result in practically complete dechlorination (Cl content less than 5 ppm) of the polymer.
Studies on polymer ignition and development of a relative hazard ranking method
Authors: Miller Bernard , Martin J. Ronald , Turner Rudolph 
Published: April 2003

AbstractThe argument is presented that a primary determinant for polymer ignition is the rate of heat input during thermal decomposition. An experimental protocol is described in which a conventional thermogravimetric analyzer is used to monitor the behavior of polymeric solids brought to ignition by exposure to preheated air. The data obtained are used to establish the minimum heating rate required for ignition and the initial decomposition temperature at that critical rate. These two properties are then combined to give a numerical ranking value which seems to be a reasonable indicator of a material's ignitability hazard potential. Data for a variety of polymers and mixed systems are presented.
Processable heat‐resistant polymers. XIII. Structure–property relationship in polyamideimides
Authors: Maiti Sukumar , Ray Atanu 
Published: April 2003

AbstractNovel isomeric polyamideimides were synthesized by reacting the diacid chloride of 2‐(4‐carboxy phenyl)‐1,3‐dioxoisoindoline‐5‐carboxylic acid and o‐, m‐, and p‐phenylenediamine at 30–70°C using polar solvents. The reactivity of the isomeric amines in the polycondensation reaction was studied. The isomeric effects on the physical, chemical, thermal, and electrical properties of the polymers were also studied. The polymers were found to be soluble in highly polar solvents such as DMF, DMAC, NMP, DMSO, m‐cresol, etc. Thermal analysis indicated that polymers were thermostable and that their thermal stability follows the order para > meta > ortho. X‐ray diffraction data revealed that para polymer is crystalline in nature. Dielectric properties with the variation of frequency at room temperature indicated that the dielectric constant and dielectric loss of the polymers follow the order ortho > meta > para.
Electrophoretic deposition of polymers. II. Polyimides: A coulombic study
Authors: Alvino W. M. , Fuller T. J. , Scala L. C. 
Published: April 2003

AbstractQuantitative studies on the electrophoretic deposition of a polyimide polymer were carried out over the voltage range 25–100 V dc. Deposition yield was related to voltage, time, and coulombs and was found to obey Faraday's laws of electrolysis. Equations relating yield to voltage and coulombs were obtained from the plotted data. Results of coulombic studies indicate that the effective equivalent weight of the polymeric species being deposited is between 6800 and 7500 (i.e., amount deposited per faraday). The coulombic yield is 75 mg per coulomb. Information and speculation on the size and composition of the electroactive species are presented.
New hydantoin vinyl ether polymers
Authors: Eldin Sameer H. 
Published: April 2003

AbstractThe title hydantoin vinyl ether polymers are water‐soluble alternating copolymers of a hydantoin vinyl ether (HVE) and maleic anhydride (MA). The copolymerization parameters are ∼0 and 0.06, respectively. The HVE/MA polymers were compared with reference poly(vinyl pyrrolidone) (PVP) and methylvinylether (MVE)/MA polymers, of approximately the same specific viscosity, with regard to two key properties: solution viscosity and complexing capability (iodine). The HVE/MA polymers gave higher solution viscosities than PVP. When compared to MVE/MA, solution viscosity was lower initially but considerably higher after standing for a longer period of time. The inverse viscosity/time relationship observed for the MVE/MA polymer was not apparent in the case of HVE/MA. With regard to complexing capability the HVE/MA polymers proved to be clearly more effective. This is thought to be due to the HVE/MA polymer structure which offers two lactam groups plus two carboxyl groups for complexing vs. one lactam and two carboxyl groups, respectively, in the case of the reference polymers.
Elevated temperature aging of HIPS
Authors: Chen. C. C. , Habibullah M. , Sauer J. A. 
Published: April 2003

AbstractThe effects of aging at 85°C on a rubber‐modified polystyrene (HIPS) have been studied as a function of aging time in both air and nitrogen. Four different types of physical measurements were carried out on the aged samples. These included mechanical relaxation measurements, tensile stress–strain measurements, creep measurements at several stresses, and measurements of fatigue lifetime under applied tension–compression stress. Aging in nitrogen is largely a physical aging process and results in higher modulus, higher tensile strength, and longer delay times to the onset of accelerating creep deformation. But tensile ductility and fatigue lifetime tend to reduce, and there is no change in location of Tg of the rubber phase. Aging in air involves both chemical and physical aging, and the changes that occur depend on which process dominates. For long‐time aging of 150 h or more, the rubber‐phase Tg is shifted to higher temperatures and the associated loss peak is broadened due to crosslinking. Also, the tensile strength, tensile ductility, creep delay time, and fatigue life all reduce. These effects are attributed to oxidative attack and embrittlement. SEM micrographs reveal variations in fracture surface morphology due to the mode of testing and to the aging medium.
On‐line measurement of surface tension and density with applications to emulsion polymerization
Authors: Schork F. J. , Ray W. H. 
Published: April 2003

AbstractThree process sensors are discussed, one for the determination of surface tension and two for the determination of liquid density. All three methods are on‐line, compatible with digital data acquisition systems, and capable of monitoring flowing process streams. The instruments are described and calibration data are given. Two mathematical models of the bubble tensiometer are developed. Data showing the application of these instruments to the monitoring of batch and continuous emulsion polymerization are given.
Flammability limits of some polymer pyrolysate–air mixtures
Authors: Day M. , Suprunchuk T. , Wiles D. M. 
Published: April 2003

AbstractSeveral textile fabrics have been heated in a closed cell and the flammability limits of the gaseous products produced determined. In addition the energy released on combustion of these gaseous products has been measured in order to obtain an indication of the heat feedback capabilites of the fabric. Comparison of the data obtained was made in order to provide an indication of the flash fire potential of the materials and their contribution to a potential fire hazard situation.
Curing reactions in elastomers. II. Carboxy‐terminated polybutadiene
Authors: Kishore K. , Verneker V. R. Pai , Vasanthakumari R. 
Published: April 2003

AbstractAttempts have been made to understand the curing reactions in carboxy‐terminated polybutadiene (CTPB), which happens to be the most practical binder in advanced solid composite propellants. The curing of CTPB has been studied for different ratios of curing agents (MAPO and Epoxide) by gel content, molecular weight, crosslink density, and penetration temperature measurements, and the optimum composition of curators for effective curing of CTPB has been determined. Activation energy calculations on the curing of CTPB with 9.5% epoxide and 0.5% MAPO in the temperature range 75–100°C gave 14.1 kcal/mol for which a diffusion‐controlled or acid‐catalyzed epoxide ring opening mechanism has been suggested for the curing process in CTPB.