bluuebunny/crossref_metadata_2025_split 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

AbstractPhysical 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

AbstractThis 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

AbstractState‐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

AbstractA 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

AbstractMarked 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

AbstractIn 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

AbstractThe 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

AbstractHigh‐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

AbstractThe 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

AbstractCastor 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

AbstractIt 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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractApplication 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

AbstractThe 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

AbstractThis 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

AbstractAn 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

AbstractEpoxy 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

AbstractSpraying 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

AbstractA 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.