bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of chemical modification on tribological properties of elastomers
Authors: Bielinski Dariusz M. , Slusarski Ludomir , Affrossman Stanley , Hartshorne Mark , Pethrick Richard A.
Published: April 2003

Physical properties of surface modified synthetic elastomers were studied to understand the factors that reduce friction and provide advantages in practical use. Bromination, iodination, sulfonation, and chlorination were investigated. The coefficient of friction μ was measured using a modified version of the pin‐on‐disc apparatus. The surface energy, morphology, mechanical properties, and extent of chemical modification were also measured. An increased stiffness and microroughness were found to correlate with changes in the coefficient of friction. Sulfonation (100% H2SO4) was found to be the most effective and universally acceptable method of chemical treatment from a tribological point of view. © 1995 John Wiley & Sons, Inc.
Modeling the vulcanization of rubbers in an oscillating bicone cell
Authors: Deiber Julio A. , Bortolozzi Raül A. , Peirotti Marta B.
Published: April 2003

This work studies the evolution of dynamic rheometric functions (dynamic viscosity η′(ω) and storage modulus G′(ω)) with the degree of vulcanization and temperature of well‐characterized SBR and NBR compounds. Experiments are carried out in an oscillating bicone cell, and results are well fitted through a model that considers flow kinematics, heat transfer, curing kinetics, and rheological functions. It is possible to quantify the model parameters and to understand better the evolution of filled rubber compounds toward crosslinked networks or vulcanizates. Conclusions are also obtained on the interplay between rheological functions and molecular parameters (average molecular weight and polydispersity). Experimental evaluations of the ratios between oscillating torques, at different times of the curing process, correlate directly with changes in rheological properties of the samples studied. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of self‐metallizing gold‐doped polyimide films
Authors: Caplan Maggie L. , Stoakley Diane M. , St. Clair Anne K.
Published: April 2003

State‐of‐the‐art methods for producing reflective polymer films for space applications involve multiple steps, and the integrity of the metal–polymer interface is less than optimal. A more efficient process was developed that consists of doping polyamic acid resins with gold additives and curing them to form self‐metallizing polyimide films. Several moderately reflective, flexible metallic gold films were produced that have good thermal stability and mechanical properties, a strong metal–polymer interface, and in some cases, electrical conductivity. It was found that the polymer system, gold additive, gold concentration, and heat treatment all affect the reflectivity, flexibility, and conductivity of the resulting polyimide films by affecting the degree of metallization of the film surface. © 1995 John Wiley & Sons, Inc.
Composites of novel biodegradable copolyamides based on adipic acid, 1,6‐hexane diamine, and L‐glycine with short E‐glass fibers. II. Preparation and properties
Authors: Arvanitoyannis Ioannis , Psomiadou Eleni , Yamamoto Noboru , Blanshard John M. V.
Published: April 2003

A study was conducted on the preparation of composite materials based on novel biodegradable copolyamides reinforced with E glass fibers by using the hand lay‐up technique. Differential thermal analysis (DTA) and wide angle x‐ray diffraction patterns were employed for investigating the effect of transcrystallinity on percentage crystallinity of composites. The thermal properties of composites (Tg and Tm) were determined with DTA and dynamic mechanical thermal analyzer (DMTA) measurements. Void fractions were evaluated from density measurements and correlated to glass fiber contents. The stress–strain curves and compression strength measurements were recorded and correlated with the glass fiber content, void content, and the percentage amino acid content of the copolymers. Although high α‐amino acid contents caused a decrease in Tg and Tm and the tensile strength of copolyamides, the introduction of glass fibers was found to counterbalance this effect by initiating an increase in the percentage crystallinity. © 1995 John Wiley & Sons, Inc.
Shrinkage of short PP and PAN fibers under hot‐stage microscope
Authors: Sarvaranta L.
Published: April 2003

Marked shrinkage behavior when heated is typical of semicrystalline polymer fibers such as polypropylene (PP) and polyacrylonitrile (PAN). Shrinkage of PP and PAN fibers may give the possibility to control the spalling tendency of fiber concrete under the heat exposure of fire. Cut staple fibers are normally delivered for concrete reinforcement. Modern methods for continuous fibers cannot be used by the end‐user for shrinkage determination of commerical staple fiber grades. The shrinkage of five different commercial staple fibers specially designed for concrete reinforcement was studied under a hot‐stage microscope. Significant differences in cumulative shrinkages of the various PP and PAN fibers were detected, shrinkages being 3–15% with PP fibers and 6–7% with PAN fibers at a temperature of 150–170°C. At about 160–165°C, PP fibers melt, whereas PAN fibers continue shrinking. Hot‐stage microscopy provides a simple and a relatively accurate method for estimating thermal shrinkage of staple PP and PAN fibers, the deviations from measured average values remaining typically at 10–15%. © 1995 John Wiley & Sons, Inc.
Preparation and characterization of teflon–FEP films grafted with acrylic acid by radiochemical method
Authors: Misra B. N. , Kumar Darshan , Kaur Inderjeet
Published: April 2003

In an attempt to prepare permselective membrane, grafting of acrylic acid (AAc) onto Teflon–fluorinated ethylene‐propylene (FEP) film was studied in aqueous medium by the preirradiation method in air. Grafting was carried out by heating a mixture of AAc, water, and preirradiated Teflon–FEP film in air at 93°C for definite time periods. Percentage ofgrafting was determined as a function of total dose, monomer concentration, reaction time, and amount of water. Maximum percentage of grafting (60.17%) was obtained at a total dose of 4.8 Mrad using 0.07M [AAc]. Evidence of grafting was obtained from the physical appearance and swelling behavior of the grafted film in polar solvents. Infrared spectroscopic and thermal analysis of the grafted film provided additional evidence for grafting. A plausible mechanism for grafting of AAc onto preirradiated Teflon–FEP film in air has been proposed. © 1995 John Wiley & Sons, Inc.
Ultraviolet‐induced graft reaction of quinoid compounds onto polypropylene films: Effect of synthesis conditions on hydroquinone‐g‐polypropylene
Authors: Chun Heung‐Jae , Beard Richard B.
Published: April 2003

The liquid‐phase graft reaction of hydroquinone (HQ) was carried out onto the surface of medical‐grade polypropylene (PP) films with the photosensitizer, benzophenone (BP). The effects of various reaction conditions on the graft yield of the samples and the changes in physicochemical properties of the surface of the samples were determined by FTIR/FMIR and surface tension measurements. As BP concentration was increased, the graft yield increased up to a maximum at 2.5 wt % of BP and then decreased. Graft yield was increased with irradiation time and HQ concentration before leveling at 3.5 wt %, in 150 min. The surface tension of samples were increased of graft yield up to 37 dyn/cm. © 1995 John Wiley & Sons, Inc.
Synthesis and properties of high‐sulfonated melamine–formaldehyde resin
Authors: Yunchao Huang , Fansen Zeng , Hu Ye , Chunying Liu , Zhaoqiang Wu , Weining Li , Shukai Yu
Published: April 2003

High‐sulfonated melamine–formaldehyde (HSMF) resins were prepared with 1.0–2.0 of sulfite/melamine (S/M) molar ratio. The factors affecting the preparation and the properties of the resin were studied. Chemical analysis indicated that there are 0.98–1.96 sulfonate groups per unit of the polymeric chain. The viscosity of HSMF resins is lower than that of sulfonated melamine–formaldehyde (SMF) resins, and the HSMF resins are more effective superplasticizers at small dosages of admixture. © 1995 John Wiley & Sons, Inc.
Chemical transformation of nitrile to reactive oxazoline functionality on a preformed polymer
Authors: Hseih D. T. , Peiffer D. G.
Published: April 2003

The chemical transformation of nitrile to oxazoline functionality via a soluble zinc salt‐catalyzed reaction was conducted on a series of nitrile‐containing copolymers, i.e., styrene–acrylonitrile (SAN) and nitrile rubbers. The results show that triad tacticity of the acrylonitrile groups is important in understanding the relative reactivity of SAN copolymers. Furthermore, the dielectric properties of the comonomer is also a prime factor in understanding the different degrees of reactivity of SAN, nitrile rubbers, and its hydrogenated analog forms. Enhanced reaction rates are noted with higher dielectric constants. © 1995 John Wiley & Sons, Inc.
Polymers from renewable resources. VIII. Thermal properties of the interpenetrating polymer networks derived from castor oil–isophorone diisocyanate–polyacrylamides
Authors: Parida D. , Nayak P. , Mishra D. K. , Lenka S. , Nayak P. L. , Mohanty S. , Rao K. K.
Published: April 2003

Castor oil was reacted with isophorone diisocyanate varying the isocyanate/hydroxyl ratio to produce a number of polyurethanes (PUs). All the PUs were reacted with acrylamide and methacrylamide using ethylene glycol dimethacrylate as the crosslinker and benzoyl peroxide as the initiator. Thermogravimetric analysis of the polymers was conducted using a computer analysis method for assigning the kinetic mechanism. The degradation steps have been discussed in the light of the kinetic parameters. © 1995 John Wiley & Sons, Inc.
Fracture toughness of adhesive joints. II. Temperature and rate dependencies of mode I fracture toughness and adhesive tensile strength
Authors: Lim Won Woo , Mizumachi Hiroshi
Published: April 2003

It has been known that adhesive strength shows temperature and rate dependencies reflecting visoelastic properties of an adhesive. Similarly, a critical strain energy release rate is expected to show temperature and time dependencies deformation and fracture of the adhesive occurs at the time of measurement of the critical strain energy release rate, which is a kind of fracture mechanical parameter for adhesive joints. The term “critical strain energy release rate” has usually been called “fracture toughness.” In this study, the critical strain energy release rate (GIC) of the opening mode was called mode I fracture toughness. GIC was measured over a wide range of temperatures and rates, and then a master curve was obtained by applying the temperature–rate superposition principle to the obtained data. Also, on the relation between GIC and adhesive tensile strength is discussed. © 1995 John Wiley & Sons, Inc.
Accelerated weathering‐induced degradation of unprotected multilayer polyethylene slabs. I
Authors: Yanai G. , Ram A. , Miltz J.
Published: April 2003

The in‐depth degradation of unprotected low density polyethlene (LDPE) induced by photooxidation was studied by following the carbonyl content and other by‐product groups as well as the retention of mechanical properties as a function of time and distance from the surface. The multilayer slabs were prepared by hot pressing of nine LDPE film layers. Weathering of the samples was performed in a Q.U.V. apparatus running dry at 55°C for different time periods. The carbonyl content, as measured by FTIR spectra, showed a parabolic symmetry around the center layer which was least affected. Oxygen barriers placed on one or both surfaces of the slabs significantly reduced the photooxidation. The retention of mechanical properties followed a similar profile as that of the carbonyl. However, the outermost layers, especially those that were close to the UV‐radiation source were slightly more affected. The results of this study lead to the conclusion that photooxidation is autocatalytic and is affected primarily by diffusion of oxygen. © 1995 John Wiley & Sons, Inc.
Solid‐state polycondensation of poly(ethylene terephthalate): Kinetics and mechanism
Authors: Zhi‐Lian Tang , Gao Qiu , Nan‐Xun Huang , Sironi Claudio
Published: April 2003

A numerical method to seek a solution for the solid‐state polycondensation (SSP) proces has been proposed to analyze the mechanism of SSP. Results expound that, for the industrial SSP process of PET, the overall reaction rate in a single pellet is appropriately simulated by the diffusion and reaction rate jointly controlling the model. From the core to the surface the SSP rate increase monotonically due to a gradual reduction of the concentration of such by‐products as ethylene glycol and water. However, the SSP rate at any location within the pellet is constrained between two purely reaction rate controlling cases. © 1995 John Wiley & Sons, Inc.
Fracture toughness of phenolphthalein polyether ketone
Authors: Han Yanchun , Yang Yuming , Li Binyao , Wang Xuhui , Feng Zhiliu
Published: April 2003

The static and impact fracture toughness of phenolphthalein polyether ketone (PEK‐C) were studied at different temperatures. The static fracture toughness of PEK‐C was evaluated via the linear elastic fracture mechanics (LEFM) and theJ‐integral analysis. Impact fracture toughness was also analyzed using the LEFM approach. Temperature and strain rate effects on the fracture toughness were also studied. The enhancement in static fracture toughness at 70°C was thought to be caused by plastic crack tip blunting. The increase in impact fracture toughness with temperature was attributed two different mechanisms, namely, the relaxation process in a relatively low temperature and thermal blunting of the crack tip at higher temperature. The temperature‐dependent fracture toughness data obtained in static tests could be horizontally shifted to match roughly the data for impact tests, indicating the existence of a time–temperature equivalence relationship. © 1995 John Wiley & Sons, Inc.
Synthesis of uniform PMMA microspheres employing modified SPG (shirasu porous glass) emulsification technique
Authors: Omi Shinzo , Katami Ken'ichi , Taguchi Tetsuya , Kaneko Kazuyoshi , Iso Mamoru
Published: April 2003

Application of the particulate microporous glass membrane (SPG) was extended to the synthesis of fairly monodisperse poly(methyl methacrylate) (PMMA) microspheres. Hydrophilic monomers have been believed to yield polymer particles of a broad size distribution when the SPG technique was employed. This difficulty was overcome by adopting the droplet swelling technique. The primary uniform emulsion composed of a mixture of hydrophobic diluent (and/or monomer), cosurfactant, and initiator was prepared with an SPG membrane and was allowed to absorb MMA (and diluent) under the principle of the degradative diffusion process from droplets in the secondary emulsion. The coefficient of variation of PMMA spheres was around 10%. Porous PMMA spheres possessing up to 185 m2/g of specific surface area were obtained as well as one‐eyed spheres and smooth and solid spheres. © 1995 John Wiley & Sons, Inc.
Thermodynamical approach to polymer rheology
Authors: Furukawa Junju
Published: April 2003

The model of pseudocrosslink is extended to polymer rheology. There exist various sizes b of 4–16 between transition points A and B. Each link is connected with a chain having length nb and relaxation time τb. nb is equal to b2 and τb is proportional to nb2. A, B, and C (polymer terminal) divide the stress‐relaxation spectrum into four zones. In the AB zone, successive dissociation of links occurs from a small size to a large one and rigidity G is decreased with time t as G ∝︁ t−0.5 and viscosity η is increased as G ∝︁ t0.5. In the BC zone, dissociation of the B link proceeds along a molecule of length n in a mode of squeezing of molecule and η becomes constant, but G still decreases due to increase of unperturbed end‐to‐end distance of chain and G ∝︁ t−0.5. However, dynamic elasticity becomes constant due to a small amplitude. At high shear, links are loosened and G and η are much decreased. Beyond C, molecule flows and η increases as η ∝︁ γ−0.8 n3.5, but high shear rate γ diminishes the effect of n due to extension of the molecule. Extensional viscosity η* is affected by the change of shape as η* ∝︁ t1.5 and gives an overshoot. Under load, creep occurs and it is proportional to t1/2–1/3. © 1995 John Wiley & Sons, Inc.
Water‐soluble sulfonated phenolic resins. II. Surface property and effectiveness as a dispersing agent
Authors: Hsu K. C. , Lee Y. F. , Chiang S. Y.
Published: April 2003

This article presents the surface activeity of a synthetic sulfonated phenolic resin (SPR) and evaluates its performance in cement mortars. It is indicated that the prepared SPR has the characteristics of a polymeric surfactant that can decrease the surface tension of water. When resin was added into cement mortars, the resulting materials exhibited better workability, more consolidated stucture, and higher compressive strength than the untreated. Therefore, SPR could be used as a water reducing admixture for cementitious materails. In addition, resins with higher sulfonate group content and low molecular weight appear to be more effective. © 1995 John Wiley & Sons, Inc.
Minimum‐time strategy to produce nonuniform emulsion copolymers. II. Open‐loop control
Authors: Echevarria Antonio , De La Cal Jose C. , Asua Jose M.
Published: April 2003

An iterative approach was developed to determine the optimal monomer addition policies in real emulsion copolymerization systems in which only limited kinetic information is available. The approach was applied to obtain widely different copolymer composition profiles for the emulsion copolymerization of butyl acrylate and styrene. The approach involves a series of semicontinuous emulsion copolymerizations carried out in an openloop control mode. Each reaction was used to obtain an estimation of the kinetics of the process that was used to calculate the monomer addition profiles for the next experiment. The method is model‐independent and converges rapidly. © 1995 John Wiley & Sons, Inc.
Effect of low earth orbit atomic oxygen exposure on epoxy functionalized siloxanes
Authors: Connell J. W. , Crivello J. V. , Bi D.
Published: April 2003

Epoxy functionalized siloxanes (EFS) are a novel class of UV curable monomers that can be rapidly photopolymerized to give transparent coatings and composites. Thin films of these materials have been subjected to low Earth orbit exposure to atomic oxygen (AO) aboard the space shuttle. It was found that UV cured samples of all four different EFS monomers exhibited excellent AO resistance both to ambient in‐flight conditions as well as exposure at 120°C. Based on SEM, STM, XPS, and weight loss data, it was proposed that AO exposure of these materials efficiently produces a thin layer of SiOxat the surface of the sample. This layer provides a barrier toward further attack by AO. © 1995 John Wiley & Sons, Inc.
Transformation of polymers in a stream of low‐temperature arc discharge plasma
Authors: Skorokhod Alex Z. , Pisanova Elena V. , Zhandarov Serge F. , Yurkevich Oleg R.
Published: April 2003

Spraying of polymer materials in a low‐temperature plasma stream is a very efficient way of depositing polymer coatings on large surfaces. The deposition of powdered polymers by an arc discharge plasma flow and spraying from the bulk have been compared. The properties of powdered polymers do not change considerably during transportation by the stream because of the short residence of the particles in the plasma. When spraying from the bulk, polymers are transported in the form of melt droplets (polyethylene, polycarbonate) or in gaseous phase (polytetrafluoroethylene); autohesion of the droplets or secondary polymerization occurs, respectively, on the substrate surface. This process offers high‐quality thin films and coatings whose structure depends significantly on the characteristics of the substrate as well as on the structure of the source polymer. Obtained polymer coatings contain nitrogen and oxygen entrapped from the atmosphere as well as (on the glass surface) the products of glass etching. This fact enables one to vary widely the properties of the coatings. Furthermore, the problem of obtaining combined protective coatings in which polymer melt fills the pores between metal particles can be solved successfully in a united technological cycle including plasma spraying of the polymer and the metal. © 1995 John Wiley & Sons, Inc.
Molecular weight distribution of a segmented copolymer of PET–PCL
Authors: Fai Woo Ka , Chi Wu , Zhu Ma De , Lie Luo Xiao
Published: April 2003

A recently developed method of combining both the results of static and dynamic laser light scattering (LLS) was applied to characterize the segmented copolymer of poly(ethylene terephthalate‐co‐caprolactone) (PET–PCL) with 48% PET content. Unlike the traditional three‐solvent method proposed by Bushuk and Benoit for copolymers, this method requires only two solvents. For each solvent, the apparent weight average molecular weight (Mw,app) was measured by static LLS. Then Mw,app was used as a constraint to convert the line‐width distribution from dynamic LLS into the apparent molecular weight distribution. Finally, the two apparent molecular weight distributions were combined to give both the true molecular weight distribution and the estimated chain composition distribution of the copolymer. We found that the PET–PCL sample with 48% PET is nearly uniform in the chain composition. © 1995 John Wiley & Sons, Inc.
Weldline strength in injection molded HDPE/PA6 blends: Influence of interfacial modification
Authors: Fellahi S. , Fisa B. , Favis B. D.
Published: April 2003

Most injection molded objects contain defects known as weldlines. This defect may introduce an element of weakness affecting the object's performance. Weldlines are particularly problematic in multiphase materials where the situation may be exaggerated by component mismatch on the two sides of the interface that results in additional weakening when the two components do not adhere well to each other. In addition, weldline behavior is influenced by orientation and morphological effects. This paper deals with relationships between the structure and the mechanical properties in injection molded high density polyethylene polyamide‐6 blends. The weldline effect is investigated in detail. Two molds were used to generate weldlines: a double‐gated tensile bar cavity in which the weldline results from the meeting of two melt fronts flowing into each other from opposite directions, and a film‐gated rectangular plaque mold with a circular insert that divides the melt front in two. Following the recombination of the fronts, there is additional flow as the melt fills the mold cavity. Two preparations containing 75 vol % of polyamide‐6 and 25 vol % of polyethylene with and without compatibilizer were studied. In the first case, a compatibilizer was incorporated into the polyethylene prior to compounding with the polyamide‐6. In the directly molded tensile bar the minor phase is strongly oriented parallel to flow. Only in the core, which represents about 10% of the sample thickness, do the dispersed phase particles assume spherical shape. The morphology of the weldline is closely related to that of the skin: the elongated structures are oriented parallel to the weldline plane. The effect of the compatibilizer on the mechanical properties (without the weldline) of the directly molded tensile bars is minor: It is overshadowed by the flow‐induced morphology. The weldline strength loss is about 40% in the noncompatibilized blend. The introduction of the compatibilizer has restored the material's ability to yield and the properties are close to those measured without the weldline. For the second type mold, the effect of the weldline is less pronounced and the effect of the distance from the insert is negligible. The anisotropy is quite pronounced in the noncompatibilized blend. In compatibilized blends, all tensile properties are unaffected by the presence of weldline, except for the 2‐mm‐thick plaque in the position close to the insert. The properties in the direction parallel to flow are similar to the type I mold and not affected by the increase of plaque thickness. Consequently one may question the utility of the directly molded tensile specimens in studying various aspects of the mechanical behavior of multiphase materials where the flow‐generated structure is very different from that found in “real” injection molded parts. © 1995 John Wiley & Sons, Inc.
Surface reactive acetal functional waterborne core–shell particles
Authors: Kjellqvist Kerstin , Rassing Jörgen , Wesslén Bengt
Published: April 2003

Core–shell particles were prepared using a two‐stage emulsion polymerization of styrene and ethyl acrylate. The particle surfaces were modified by introducing an acetal functionality, suitable for acid‐catalyzed crosslinking processes. Surface functionalization was performed in two principally different ways: In the first method, 4‐aminobutyraldehyde dimethylacetal was used for grafting through transesterification of ethyl acrylate residues at the surface or through reactions with epoxy groups introduced in the second‐stage polymerization. In the second method, 4‐acrylamidobutyraldehyde dimethylacetal was used as a comonomer to ethyl acrylate in the second‐stage polymerization. The reactive particles were used as crosslinking agents in an acid‐curing coating system. © 1995 John Wiley & Sons, Inc.
Absorption–desorption histories through a sphere with a change in dimensions, with constant concentration on surface during absorption, and finite volume of surrounding during desorption
Authors: Bouzon J. , Benghalem A.
Published: April 2003

Liquids are transferred through nonporous polymers provoking a change in dimension. A mathematical treatment of the process of radial diffusion through a sphere with consequent change in dimension is made, as well as a numerical treatment of the process. The case is considered when the concentration of the liquid on the surface is constant during absorption and then the surrounding fluid is of finite volume and strongly stirred during the stage of desorption. The kinetics of absorption–desorption histories are calculated for various values of the volume expansion due to the presence of liquid. The profiles of concentration as well as the kinetics of change in dimension are also evaluated. Two parameters are introduced: the maximum of the volume expansion of the polymer and the ratio between the amount of liquid in the polymer and that contained in the surrounding at the final equilibrium of desorption. © 1995 John Wiley & Sons, Inc.
Mechanical instability of swollen PVC films
Authors: Teschke O. , Kleinke M. U. , Galembeck F.
Published: April 2003

The swelling of soft coating on a tough substrate immersed in solvent is investigated. Equilibrium aspects of the coating deformation due to swelling as well as its kinetics have been explored; in particular, the appearance of patterns on the originally smooth surface of the swollen film is described and modeled. The patterns are the result of a mechanical instability such as buckling or wrinkling. The time dependence of the wrinkles height is measured and, by using the energy dissipation criterion for wrinkle spread, the ratio of the adhesion energy by the bulk modulus is determined as a function of swelling time. © 1995 John Wiley & Sons, Inc.
Reactive diluents and properties of ultraviolet‐cured polycarbonate urethane acrylates
Authors: Krongauz Vadim V. , Tortorello Anthony J.
Published: April 2003

Polymer films obtained from photocurable formulations were investigated by tensile methods and dynamic mechanical analysis. The polymer formulations contained photoinitiator, urethane diacrylate oligomer, and acrylic reactive diluent. It was found that diluent concentration may strongly affect the glass transition temperature and elastic modulus of the cured coating. When the diluent homopolymer glass transition temperature is larger than that of oligomer homopolymer, the glass transition temperature and elastic modulus of the coating film increase with the increase of the diluent concentration. When the diluent homopolymer has lower glass transition temperature than the homopolymer of the oligomer, the increase in diluent concentration leads to a decrease in glass transition temperature and elastic modulus of the UV‐cured coating film. The effect of the testing temperature on tensile storage modulus of the films containing different concentrations of reactive diluents was studied as well. The data indicated that a variety of coatings with wide ranging but predictable properties can be formulated from previously examined starting materials but used at different concentrations. © 1995 John Wiley & Sons, Inc.
Study on application of block copolymers composed of poly(vinyl alcohol) and polyacrylamide to paper sizing
Authors: Okaya Takuji , Sato Toshiaki , Ono Isao , Maruyama Hitoshi , Terada Kazutoshi
Published: April 2003

Block copolymers of poly(vinyl alcohol) (PVA) and polyacrylamide (PAAm) were investigated as paper additives. The mixture of both homopolymers in aqueous solution caused phase separation, which indicated incompatibility. The block copolymers were soluble in water without macrophase separation. In the case of surface sizing to paper, PVA–b‐PAAm as well as PAAm afforded stiffness to paper, whereas PVA could not. In the case of internal sizing, the block copolymers with anionically modified PAAm revealed excellent improvement in paper properties, whereas PAAm made the tearing strength worse. Brittle polymers such as PAAm appear to afford stiffness to paper, but also make the paper brittle. PVA that is a tough polymer due to high crystallinity and low glass transition temperature can afford toughness to paper, at the expense of stiffness. The block copolymers seem to retain the desirable properties of each simultaneously. © 1995 John Wiley & Sons, Inc.
Interfacial aspects of latex ipns for toughening polycarbonate. I. Synthesis and characterization
Authors: Hu R. , Dimonie V. L. , El‐Aasser M. S. , Pearson R. A. , Sperling L. H. , Hiltner A. , Mylonakis S. G.
Published: April 2003

Core/shell structured latex particles with an interpenetrating polymer network (IPN) core(polymer A and polymer B) and glassy shell (polymer C) were synthesized by emulsion polymerization techniques. Polymer A was poly(butadiene‐stat‐styrene) (90/10) (P(Bd/S)). Polymer B was either poly(butyl acrylate‐stat‐methyl methacrylate) (60/40) or poly(butyl acrylate‐stat‐styrene) (60/40) prepared by a sequential IPN technique to form the cores. The glass transition temperatures, Tg, of polymer A and polymer B were around −70 and 10°C, respectively. The shell, polymer C, poly(styrene‐stat‐acrylonitrile) (72/28), was polymerized with grafting onto the IPN core by a semicontinuous process. The particle size and particle size distribution were measured by light‐scattering, capillary hydrodynamic fractionation, and transmission electron microscopy. The glass transition temperatures were determined by differential scanning calorimetry. The polymer A (particle sizes between 200–270 nm) with different gel fractions was used to characterize the effect of gel fraction on IPN morphology. A core/shell type phase separation was observed for IPN particles when using a polymer A with > 90% gel fraction. A distribution of polymer B domains in polymer A was obtained when using polymer A with a 40% gel fraction. A good coverage of polymer C on the IPN core particles was obtained at a core/shell ratio of one to one. A broad glass transition range for the core/shell structured latex particles was observed. In article II of this series, these latex particles will be used to toughen such engineering thermoplastics as polycarbonates to understand the particular toughening theories of these polymers. © 1995 John Wiley & Sons, Inc.
Adsorption properties and microporous structure of adsorbents produced from phenolic resin and biomass
Authors: Simitzis J. , Sfyrakis J. , Faliagas A.
Published: April 2003

Mixtures of novolac resin and olive stone biomass in proportions 20 : 80 (w : w) are cured, pyrolyzed up to 1000°C (material C20a), and activated with steam (material C20a). The adsorption properties of these materials and a commercial activated carbon (CC) are investigated based on the adsorption of nitrogen and pentane. The adsorption capacity, the surface area determined by the BET and DRK equation, and the pore volume determined as micropore volume by the DR equation, and as cumpulative pore volume related to the Kelvin equation, for the materials follow the order C20a > CC > C20. The DR equation can be applied for the adsorption of nitrogen on the materials examined in the region of P/Po = 0.005 up to 0.3 that exceeds in both sides the common range for the applicability of the DR equation. The activated materials C20a and CC are mainly microporous and reveal the type I isotherms of the Brunauer classification for nitrogen adsorption. The only pyrolyzed material, C20, contains both micropores and mesopores and reveals characteristics of both types I and II. The number of layers for C20a and CC is lower than 2 and for C20 is more than 2. © 1995 John Wiley & Sons, Inc.
Tensile mechanical property evaluation of natural and epoxide‐treated silk fibers
Authors: Dunaway Dwayne L. , Thiel Brad L. , Viney Christopher
Published: April 2003

Silkworm cocoon silk and spider major ampullate (drag line) silk exhibit macroscopic tensile properties that, while impressive in the context of polymer fibers, are highly variable. The variability is linked to the cross‐sectional geometry being nonuniform: silk fiber cross section changes significantly over distances that are small compared to the scale on which diameters are averaged by typical characterization techniques. This characteristic must be taken into account when evaluating chemical treatments (in the present case infiltrating with crosslinkable epoxide) that are aimed at improving strength or stiffness. The magnitude of any change in mechanical property must be considered in relation to the spread in values recorded prior to treatment. An apparent improvement in the mean value of a tensile property may turn out to be statistically insignificant when compared to the standard deviations associated with those data. Previous authors do not address this simple assessment of significance. © 1995 John Wiley & Sons, Inc.
On the assessment of hydrogels for fluid absorbency
Authors: Dave Ashok , Vaishnav Ujval , Desai Rakesh , Shah Amrish , Ankleshwaria Bhupin , Mehta Mahesh
Published: April 2003

Hydrogels are capable of absorbing fluids like water to the extent of several fold. Since this is an important characteristic property of any hydrogel, it is necessary to employ a simple and accurate method for its assessment. Several methods reported in the literature have been discussed for their scope as well as limitations. A comprehensive approach on the basis of polymer structure–property application is made to evaluate suitable methodology for two types of hydrogels, continuous and discrete. Representative methods for both type are suggested with detailed experimental procedures and results. The work provides com parative data with suggested methods which could be useful to the practitioner. © 1995 John Wiley & Sons, Inc.
Structure–property relationship in fibers spun from poly(ethylene terephthalate) and liquid crystalline polymer blends. II. Effect of spinning temperature on fiber properties
Authors: Petrović Zoran S. , Farris Richard
Published: April 2003

A series of fibers based on neat poly(ethylene terephthalate) (PET) and PET/10% liquid crystalline polymer (LCP) blends were spun at various temperatures, ranging from 250 to 310°C, and the effect of spinning temperature on properties was studied. Improved tensile strengths and higher moduli of hot‐drawn fibers were obtained with fibers spun at and above 300°C, which was explained by increased transesterification and the randomized structure of the PET/LCP blends. © 1995 John Wiley & Sons, Inc.
Highly dispersed titanium(IV) oxide on α‐cellulose surface: An XPS, SEM, and XRD study
Authors: Da Silva Lindomar R. Damasceno , Gushikem Yoshitaka , Gonçalves Maria Do Carmo , Filho Ubirajara P. Rodrigues , De Castro Sandra C.
Published: April 2003

Interaction of titanium chloride with a cellulose surface and the decurrent modifications introduced on its morphology were studied by scanning, electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The chemical analysis of the surface was carried by X‐ray photoelectron spectroscopy (XPS) and changes in the crystallinity upon chemical treatment was determinded by the X‐ray diffraction (XRD) technique. Interaction of titanium with cellulose occurs only at the surface and a decrease of its crystallinity was observed with the amount of metal oxide incorporated into the solid matrix. © 1995 John Wiley & Sons, Inc.
Catalyzing the curing reaction of a new benzoxazine‐based phenolic resin
Authors: Ishida H. , Rodriguez Y.
Published: April 2003

The effect of potential catalysts on the curing reaction of a new type of phenolic resins obtained from benzoxazine precursors is studied. These novel resins solve the shortcomings of traditional phenolics because they cure by a ring‐opening mechanism that avoids the release of volatiles. Isothermal and nonisothermal differential scanning calorimetry (DSC) data is used to determine the influence of the catalysts on the curing kinetics. Fourier transform infrared (FTIR) spectroscopy is also applied. The benzoxazine chosen for this study is a purified benzoxazine monomer based on bisphenol‐A, formaldehyde, and aniline. The as‐synthesized benzoxazine precursor is also studied to determine the influence of the dimers and higher oligomers in the curing mechanism. The presence of these structures seems to catalyze the curing reactions. The activation energy and overall reaction order of the as‐synthesized precursor are determined. Among the catalysts tested, adipic acid shows the most promising results. For all the cases studied the curing reaction is autocatalyzed up to a diffusion‐controlled stage. © 1995 John Wiley & Sons, Inc.
Miscibility and shear creep resistance of acrylic pressure‐sensitive adhesives: Acrylic copolymer and tackifier resin systems
Authors: Kim Hyun‐Joong , Mizumachi Hiroshi
Published: April 2003

The miscibility between an acrylic copolymer and a tackifier resin was investigated in terms of phase diagrams, glass transition temperatures (Tg's), and dynamic mechanical properties of blends. Shear creep resistance (holding power, tb) of the blends was measured as a function of both temperature and stress (σ0) in order to obtain the master curves. It was found that the shear creep resistance of the pressure‐sensitive adhesives (PSAs) was closely related to the miscibility between the components and viscoelastic properties of the blends. The master curve of the miscible blends shifts toward a longer time scale as the amount of tackifier resin in the blend is increased as a result of the modification of the bulk properties, and their behavior greatly depends on the glass transition temperature (Tg) and storage modulus (G′) of the blends. However, the master curve of immiscible blends where two phases exist in the system does not shift greatly toward a longer time scale, because Tg and the storage modulus of the blend do not change greatly. © 1995 John Wiley & Sons, Inc.
Miscibility of blends of epoxidized natural rubber and poly(ethylene‐co‐acrylic acid)
Authors: Mohanty S. , Roy S. , Santra R. N. , Nando G. B.
Published: April 2003

The blends of epoxidized natural rubber (50 mol %) (ENR) and poly(ethylene‐co‐acrylic acid) (PEA) (6 wt %) are demonstrated to be partially miscible up to 50% by weight of PEA and completely miscible beyond this proportion. The miscibility has been confirmed by a DSC study which exhibits a single second‐order transition (Tg) for the 30 : 70 and 50 : 50 (ENR : PEA) blends. For the 70 : 30 (ENR : PEA) blend, the Tg's shift toward an intermediate value but do not merge to form a single Tg, making the blend partially miscible. The miscibility has been assigned to the esterification reaction between – OH groups formed in situ during melt blending of ENR and – COOH groups of PEA. The occurrence of such reactions have been confirmed by UV and IR spectroscopic studies. The existence of a single phase of the blends beyond 50 wt % of PEA has been shown by SEM studies. © 1995 John Wiley & Sons, Inc.
Chelate membrane from poly(vinyl alcohol)/poly(n‐salicylidene allyl amine) blend. II. Effect of co(II) content on oxygen/nitrogen separation
Authors: Choi Moon Jae , Park Chang Kyu , Lee Young Moo
Published: April 2003

Facilitated transport of oxygen was performed through chelate membranes containing cobalt with selective oxygen binding ability as a fixed oxygen carrier. Chelate membranes were obtained from Schiff base membranes after treating a poly(allyl amine) (PAAm) and poly(vinyl alcohol) (PVA) blend with salicylaldehyde. It is confirmed that the OO stretching peak through a frequency change in FTIR could be seen at 1150 cm−1 between cobalt in the membrane and incoming oxygen. The permeability of oxygen through Schiff base membranes was 2.01−2.98 × 10−13 [cm3 (STP) cm2/cm s cmHg] and oxygen permselectivity was in the range of 1.83−3.27. For chelate membranes, both the permeability of oxygen and oxygen selectivity increased to 2.15−2.82 × 10−12 [cm3 (STP) cm2/cm s cmHg] and around 8, respectively. Permselectivity of chelate increased as a result of facilitation of O2 and inhibition of N2 transport. Detailed results and the mechanism of facilitation of oxygen are discussed on the basis of molecular interactions. © 1995 John Wiley & Sons, Inc.
Magnetic resonance image attributes of the bovine corpus luteum during development and regression
Authors: Hilton Jennifer L. , Baerwald Angela R. , Sarty Gordon E. , Adams Gregg P. , Pierson Roger A.
Published: April 2003

To determine whether magnetic resonance (MR) image attributes of the corpus luteum (CL) reflect its physiologic status at different phases of the bovine ovarian cycle, we analyzed the numerical pixel values (NPVs), relaxation rates, proton densities (PDs), and apparent diffusion coefficients (ADCs) from T1‐, T2‐, and diffusion‐weighted in vitro images and maps of the CL acquired at defined phases of luteal function. Ovaries were removed and serum samples taken on days 3, 6, and 10, or ≥17 (day 0 = ovulation), representing metestrus (n = 10), early diestrus (n = 7), mid‐diestrus (n = 9), and proestrus (n = 7), respectively. Regions of interest (ROIs) in each quadrant of the CL (which occupied at least 20% of the quadrant) were selected for analysis. Three MR image slices were analyzed: the slice with the greatest cross‐sectional area of the CL, and the slices acquired immediately before and after that slice. The mean NPVs of the CL in T1‐weighted images increased at each phase from metestrus (1,104 ± 40 msec) to early diestrus (1,119 ± 77 msec), to late diestrus (1,206 ± 43 msec) and proestrus (1446 ± 80 msec; P < 0.001). The mean NPVs in T1‐weighted images were higher in regressing CL (proestrous) than in any other phase (P < 0.002). Grayscale heterogeneity of CL in T1‐weighted images tended to increase during regression (P < 0.07). Regressing CL (proestrus) exhibited higher T1‐weighted mean NPVs (P < 0.01) and tended to have greater heterogeneity (P < 0.06) than growing (metestrus) and mature (diestrus) CL, even though similar progesterone concentrations were observed. The increased brightness and heterogeneity of regressing CL in T1‐weighted images appeared to be correlated with increased connective tissue and triglyceride content and decreased vascularity. It is anticipated that diagnostic markers for luteal viability and atresia in the in vitro bovine model will be applied to in vivo studies in women. Anat Rec Part A 272A:454–459, 2003. © 2003 Wiley‐Liss, Inc.
Improvement of RMI performance by generating efficient code
Authors: Maeda Kazuaki
Published: April 2003

The author developed an RMI (referred to here as xRMI) that includes a code generation function for object serialization and confirmed its effectiveness. The distinguishing characteristics of xRMI are that it combines runtime code generation for object serialization and migration of generated code while maintaining the ease of use of the Java RMI. This enables the time required for the second and subsequent client‐side serializations to be reduced and high‐speed deserialization to be done at the server side by migrating the code for deserialization, which is generated at the client side, to the server side. As a result, xRMI runs faster than standard Java RMI, and a significant performance improvement can be expected for network applications. This paper presents the background for the research and describes the basic design and implementation of xRMI, as well as experiments for confirming xRMI performance. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(10): 79–88, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1178
Environment for multiprocessor simulator development
Authors: Wakabayashi Masaki , Amano Hideharu
Published: April 2003

To develop multiprocessor systems for continuing the precipitous increase in performance seen in recent years, it is important to include performance prediction at a preimplementation stage. Since software simulation, which is one such performance prediction technique, has a high degree of flexibility, it is used in diverse situations. To simulate a multiprocessor system, a simulator is implemented for a specific architecture. However, this method has accompanying implementation costs for building a simulator for each different target architecture. In this paper, the authors propose the multiprocessor simulator library ISIS as a multiprocessor simulator construction support system. ISIS is a collection of multiprocessor system internal function block simulators. Multiprocessor simulators having any kind of architecture can be constructed by combining function block simulators. Compared with conventional techniques, implementation costs can be reduced without directly impairing simulator runtime costs. Several multiprocessor simulators were implemented by using ISIS, and their execution speeds and implementation costs were evaluated. Sufficient runtime speeds were obtained for practical uses at extremely low implementation costs. ISIS has actually been used in research for on‐chip multiprocessor cache systems, and various kinds of knowledge have been obtained from the evaluation results of that research. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(10): 74–84, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10122