bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of aging on polyimide: A study of bulk and interface chemistry
Authors: Buncick Milan C. , Denton Denice D. 
Published: April 2003

AbstractWe are investigating the bulk and interfacial chemistry of polyimide (PI) exposed to heat and relative humidity (RH) stress (85°C/85% RH) over long periods to understand the long‐term reliability aspects of PI for microelectronic applications. The PI surface chemistry and the PI–Si interface chemistry was followed with electron spectroscopy for chemical analysis (ESCA). For exposure times greater than 550 h, the PI surface exhibits significant changes in emission structure and atomic concentration. The PI–Si interface indicates little change in the PI chemistry when compared to control samples. The water‐contact angle at the PI surface shows no statistically significant change as a function of exposure time. Bulk and surface chemistry were followed with Fourier transform infrared spectroscopy (FTIR) in a grazing incidence reflection configuration. There were measurable differences in FTIR spectra between aged and control samples only for the case of very thin PI layers. These results suggest that for exposure times of less than 1100 h, chemical changes in PI occur primarily at the PI–air interface for samples 1 μm thick and greater. These changes represent a possible rearrangement of the imide structure and may be a form of deimidization of the polymer, but the final state is not polyamic acid. The PI surface chemistry changes observed with ESCA are reversible upon reheating to the cure temperature.
Pervaporation membranes for ethanol–water mixture prepared by plasma polymerization. III. Perfluorocarbon membranes
Authors: Masuoka Toshio , Iwatsubo Takashi , Mizoguchi Kensaku 
Published: April 2003

AbstractPervaporation membranes for the ethanol–water mixture were prepared by plasma polymerization of tetrafluoroethylene, perfluoropropane, and perfluoropropylene onto porous substrates. The influence of the monomers on the elemental ratio (F/C) of the polymer depositions by X‐ray photoelectron spectroscopy was rather small compared with that of the W/FM parameter (W = wattage for plasma excitation, FM = mass flow rate of a monomer). The optical emission spectroscopy indicated the similarity of gaseous species formed in the plasmas. The membranes were found ethanol‐permselective, showing separation coefficients (αEtOH) around 4–7 and a wide range of permeation rates (J), 10–10−2 kg/m2 h, for the 4.8 wt % ethanol solution at 40°C. The αEtOH of the membranes with thicker depositions could be correlated to the F/C ratios as a measure of membrane hydrophobicity. It was thought that, by making a plot αEtOH against J values for the perfluorocarbon membranes, they could be classified into three groups on thickness of deposition. The ethanol‐separation mechanisms for each group, which may contain four kinds of mass transfer schemes, i.e., distillation through larger pores, flow of sorption layer at the liquid–membrane interface, and diffusions through deposition or substrate, were also discussed.
Fractionation and characterization of linear low‐density polyethylene at a lower critical solution temperature (LCST)
Authors: Barbalata Alla , Bohossian Takouhi , Delmas Genevìve 
Published: April 2003

AbstractThe composition and molecular weight distribution of linear low‐density polyethylenes (LLDPE) have been determined by fractionation and characterization at a lower critical solution temperature (LCST). The fractionation in 2,4‐dimethyl pentane takes advantage of the fact that the LCST is sensitive to the side‐group content as indicated by the 70 K difference between the LCSTs of PE and polypropylene at the same molecular weight (MW). Temperature‐rising elution fractionation (TREF) and LCST fractions are compared by IR and SEC and also by a new method based on turbidity at an LCST. It is found that the LCST fractionation is sensitive to MW and TREF largely depends on a comonomer content. Calibration of the LCST method for MW distribution and effect of the nature of the comonomer on the LCST are discussed. The LCST technique associated with IR analysis is found to be quite effective for characterizing LLDPE.
Flame‐retarding modification of nylon 6 textile
Authors: Yao Kang De , Han Weiping , Han Dechang 
Published: April 2003

AbstractFor the purpose of flame retardation, nylon 6 textile was first hydroxymethylated and then the methylol group containing nylon 6 textile was finished with Pyrovatex CP at 160–170°C. The limiting oxygen index (LOI) value increased from 23.6 for the original textile to 31.4 for the modified one. The mechanism of flame retardation was investigated using thermogravimetry (TGA), differential scanning calorimetry (DSC), elemental analysis, infrared spectroscopy, and X‐ray diffraction. Results reveal that Pyrovatex CP plays a flame‐retarding role in both the condensed and gas phases.
Synthesis and separation characteristics of strongly basic anion‐exchange resins prepared from different monomers
Authors: Etoh T. , Miyazaki M. , Harada K. , Nakayama M. , Sugii A. 
Published: April 2003

AbstractChloromethylstyrene–ethylene glycol dimethacrylate (EGDMA) copolymer beads (PCMS) and dimethylaminomethylstyrene‐EGDMA copolymer (PDAMS) were synthesized by suspension polymerization as noble polymer matrices. The chemical and physical properties of the quaternized resins (PCMS‐Q and PDAMS‐Q) were approximately equal. The characteristics of both resins were examined by high‐performance liquid chromatography using columns packed with the resins. These resins served as conventional anion‐exchange resins for small organic anions, but indicated markedly different retention for large molecular anions, namely, PDAMS‐Q retained proteins having a negative net charge, but PCMS‐Q did not. It was suggested that the chemical and physical structures on the external surfaces of ion exchangers are very important in ion‐exchange chromatography of proteins.
Peel adhesion apparatus using the compound pendulum and its practical performance
Authors: Obori Hiroyoshi , Takenaga Mitsuru , Kasai Akinari 
Published: April 2003

AbstractAn apparatus for measuring the peel adhesion behavior is developed on the basis of the circular motion of the compound pendulum. The peel force versus peel rate characteristics at the increasing and decreasing rates of peeling can be measured in a half cycle of rotation of the pendulum. A personal computer plays the important roles of operating the automated apparatus and processing data in real time. To test practical performance of the apparatus, the relation between peel force and rate of peeling was investigated for various pressuresensitive adhesive (PSA) tapes over a wide peel rate range. The respective curves in peel force versus peel rate in the increasing and decreasing rate processes are consistent with each other in the rate regions where cohesive or interfacial failures occur; while in the transition region between their failures, it appears that a peel hysteresis exists. Furthermore, the conventional testing under constant rate was repeated, and good agreement with the results from the present apparatus was obtained.
Interactions at the PA‐6/PA‐66 interface
Authors: Rybnikár̆ Frantis̆ek , Geil P. H. 
Published: April 2003

AbstractRefrigerant tubing used in some mobile air conditioning systems has a nylon core, often consisting of nylon 6, nylon 66, or a copolymer thereof. A blend of the homopolymers would be more economical than the copolymer. This article deals with the structural stability of such blends during processing. The crystallization and melting behavior of laminates and solution cast blends of nylon 6 and 66 were examined. Although they do not cocrystallize readily, their at least partial miscibility in the melt and possible coincorporation as crystal defects cause reductions of the melting points and heats of crystallization and fusion of both polymers. The crystallization temperature of the nylon 6, however, increases with increasing nylon 66 content, up to ca. 60% nylon 66, a feature attributed to nucleation of the 6 by the 66. © 1992 John Wiley & Sons, Inc.
Diffusion and sorption of organic liquids through polymer membranes. VI. Polyurethane, neoprene, natural rubber, nitrile butadiene rubber, styrene butadiene rubber, and ethylene propylene diene terpolymer versus organic esters
Authors: Khinnavar Rajashekhar S. , Aminabhavi Tejraj M. 
Published: April 2003

AbstractSorption and diffusion of eight esters into six commercial polymer membranes have been studied by immersion/weight gain experiments to determine how the transport behavior is affected by the choice of the solvent molecules and the chemical structures of the polymer membranes. The temperature dependence of transport parameters was found to follow the Arrhonius activation theory. It has been proved that the kinetics of equilibrium concentration can be described by the first‐order kinetic rate equation. Furthermore, the results of transport parameters have been discussed in terms of the size, shape, and chemical nature of the diffusant molecules.
Semi‐ and fully‐interpenetrating polymer networks based on polyurethane–polyacrylate systems. XII. The influence of polymerization pressure on morphology and properties
Authors: Hourston D. J. , Huson M. G. 
Published: April 2003

AbstractPolyurethane–poly(methyl acrylate) interpenetrating polymer networks (IPNs) of fixed composition (50/50) were prepared at 60°C and a range of pressures. Increased synthesis pressures generally resulted in improved mixing of the two networks. The physical properties of the IPNs initially improved as a result of the enhanced mixing, reaching a maximum for specimens synthesized at 250 MPa. The poorer properties for the IPNs, prepared at higher synthesis pressures, have been ascribed to decreased uniformity in the network.
Synthesis and properties of cationic resins derived from polyether/polyester‐modified epoxy resins
Authors: Lee Lung‐Ta , Yang Chin‐Ping 
Published: April 2003

AbstractFour polyether and one polyester‐modified cationic resins were synthesized by reacting polyether/polyester‐modified epoxy resins with 2‐ethylhexanol‐blocked‐toluene diisocyanate (2‐EH‐blocked TDI) and diethanolamine and subsequently neutralizing the resins with acetic acid. Four different polyethers and one polycaprolactone diol (PCP) were used to react with epoxy resin to form polyether‐modified epoxy resins (1a–d) and polyester‐modified epoxy resin (1e). The extent of reaction of epoxy resin and polyether or polyester was evaluated by the change of epoxy equivalent weight and the gel permeation chromatography curve of the resulting product. Cationic resins were dissolved in suitable solvents and were mixed with deionized water to form emulsions. Some factors, such as pH value of emulsion, solvent content, and applied voltage affecting the emulsion and electrodeposition properties, were investigated. Cationic resins, prepared from PPG (#1000)‐modified epoxy resins, yielded a wider pH range of stable emulsion and also yielded deposited films with a pleasing appearance. PEG (#1000)‐modified cationic resins produced a higher deposition yield, but higher throwing power was obtained by deposition of the PCP (#530)‐modified cationic resins.
The effect of chemical composition on the miscibility of styrene/acrylonitrile/fumaronitrile terpolymers with styrene/acrylonitrile copolymers
Authors: Warakomski John M. , Dion Robert P. 
Published: April 2003

AbstractBlends were prepared of styrene–acrylonitrile–fumaronitrile (SANFN) terpolymers with styrene–acrylonitrile (SAN) copolymers and of SANFN terpolymers with SANFN terpolymers of different compositions. Miscibility was determined by differential scanning calorimetry. For three SANFN terpolymer compositions containing 11–17% fumaronitrile, a range of miscible SAN copolymers was defined. The miscibility can be predicted by using a Flory–Huggins‐type mean‐field approach.
Monitoring thermoset polymerization by using piezoelectric measurements
Authors: Perrissin‐Fabert I. , Feve M. , Jayet Y. , Merle G. 
Published: April 2003

AbstractThe electric impedance of a piezoelectric element placed inside a polymeric system depends on the viscoelastic property of the polymer. Its measurement is a sensitive and nondestructive method for monitoring the curing of such materials. The validity of this new method is shown by comparison with traditional viscoelastic and ultrasonic techniques.
Photosensitive polyimides developable with basic aqueous solutions (II)
Authors: Takano Kei , Mikogami Yukihiro , Nakano Yoshihiro , Hayase Rumiko , Hayase Shuzi 
Published: April 2003

AbstractPositive and negative photosensitive polyimides developable with basic aqueous solutions are reported. The results consist of poly amic acids and naphthoquinone diazides in which sulfonate groups have to be substituted at 4‐position. It depends on the naphthoquinone structures whether positive or negative patterns are obtained. In order to fabricate resist patterns, High‐Temperature‐Post‐Exposure‐Process (HIT‐PEB) must be utilized. The reaction mechanisms are also discussed. © 1992 John Wiley & Sons, Inc.
Annealing of commercial block polypropylene. I. Thermal and physical properties
Authors: Ito Jun‐Ichi , Mitani Katsuo , Mizutani Yukio 
Published: April 2003

AbstractInvestigations were carried out regarding the effect of annealing of ethylene–propylene block copolymer (block PP) moldings on their tensile impact strength (TIS), brittle temperature (Tb), and other mechanical properties. Annealing near the melting point improves TIS and Tb as the result of recrystallization. With a system in which a minute amount of talc is added as a nucleating agent, the degree of improving TIS through annealing is considerably less than that with a nonnucleated system. The effect of annealing on the impact strength is due to changes of fine texture and morphology of crystallites and is explicable by recrystallization and polymer diffusion. © 1992 John Wiley & Sons, Inc.
Self‐condensation of aqueous hexa(methoxymethyl) melamine: Effects of concentration, pH, and alcohol content
Authors: Snyder Donald M. , Vuk Thomas J. 
Published: April 2003

AbstractDilute aqueous solutions of hexa(methoxymethyl)melamine have been found to form colloidal suspensions of cross‐linked polymer under acidic conditions in a manner similar to nonalkylated methyolmelamines. Experiments have shown that the time to onset of turbidity is quite sensitive to solution pH, with a sharp maximum in the rate observed at pH 1.22 under the specific conditions used in this study. Solutions were unexpectedly stable at pH values below the maximum. Suppression of the condensation process was also observed in the presence of added alcohols, with the magnitude of the rate‐retarding effect influenced by the alcohol structure. © 1992 John Wiley & Sons, Inc.
Free‐radical polymerization of styrene with a binary mixture of symmetrical bifunctional initiators
Authors: Yoon Won Jung , Choi Kyu Yong 
Published: April 2003

AbstractThe kinetics of bulk styrene polymerization catalyzed by a binary mixture of symmetrical bifunctional initiators has been investigated. When the bifunctional initiators having different thermal stabilities are mixed, an unsymmetry in the initiator functions is formed in situ via propagation, chain transfer, and termination reactions. For the quantification of the polymerization kinetics, a kinetic model has been developed using the molecular species modeling technique. For various polymerization conditions, good agreements between the model predictions and experimental data have been obtained. It is shown that polymerization rate and molecular weight can be easily regulated under isothermal reaction condition by changing the initiator composition. A comparison of the detailed kinetic model with a simple kinetic model for monofunctional initiators has also been made to illustrate the molecular weight increasing effect of the bifunctional initiator system. © 1992 John Wiley & Sons, Inc.
DAC‐coated resins for hemoperfusion
Authors: Yan Jun , Xu Rongnan , Zhou Peiqing , Lu Zhounian , Wu Xinhua , Wu Zhaoguang 
Published: April 2003

AbstractThis paper reports the use of diacetylchitin (DAC)‐coated macroreticular resin HS‐12 as an adsorbent in hemoperfusion. Sixteen dogs acutely intoxicated with pentobarbital were hemoperfused, either with the coated resin (n = 8) or raw resin (n = 8). The results showed the coating greatly improved resin hemocompatibility. The clearance rates for the coated and raw resins were 195 mL/min for the first 5 min at a flow rate of 200 mL/min. In clinical practice, 12 patients who were acutely intoxicated by drugs, such as pentobarbital and phenobarbital, were hemoperfused and saved. © 1992 John Wiley & Sons, Inc.
Supermicron poly(butyl acrylate)/polystyrene core‐shell latexes
Authors: Cook D. G. , Rudin A. , Plumtree A. 
Published: April 2003

AbstractLatex particles of up to 2 μm can be made by standard emulsion polymerization methods, but attempts at larger sizes usually results in a crop of smaller particles or coagulation of the latex. In this work, it is shown that use of an oil‐soluble initiator (2,2′ azodiisobutyronitrile [AIBN]) provides a means by which large (6 μm diameter) polybutyl acrylate latex particles can be made by sequential core‐shell polymerizations. It is suggested that the limited water solubility of AIBN decreases the formation of secondary particles and that the lower ionic strength of the water phase enhances stability of the latex compared to a conventional persulfate initiator. To further minimize formation of secondary particles, long reaction times and progressively larger proportions of seed latex are used in successive reactions. © 1992 John Wiley & Sons, Inc.
Effects of CF4/O2 gas plasma power/exposure time on dielectric properties and breakdown voltages of PVDF films
Authors: Mammone Robert J. , Binder Michel 
Published: April 2003

AbstractDielectric properties and electrical breakdown strengths were measured on 12‐μm‐thick poly(vinylidene fluoride) films before and after exposure to various power levels and exposure times in a 96% CF4/4% O2 gas plasma. Significant changes in dielectric constant, dielectric losses, and breakdown voltages were observed. Breakdown voltages for PVDF films as a function of exposure time and plasma power appear to go through a maximum. © 1992 John Wiley & Sons, Inc.
Speciality polyurethane soft segments. II. Mixing studies in micro‐RIM using polyether diamine oligomers containing backbone urea moieties
Authors: Harris Robert F. , Anderson Robert M. , Shannon David M. 
Published: April 2003

AbstractPolyether polyamines containing preformed urea moieties in their backbone, prepared by the reaction of aminated polyglycols with urea, were used to fabricate high modulus urea polymers by reaction injection molding (RIM) on micro‐RIM equipment. A formulation was studied based on a 2000 g/mol molecular weight polyether diamine containing about 4 internal urea moieties/molecule as the soft segment and Isonate 143L and diethyltoluenediamine (DETDA) as the hard segment (60 vol %). Mixing was measured by the temperature rise produced by injection of the components into an adiabatic cup as a function of the B‐side Reynolds number at the mixhead. B‐Side Reynolds numbers of about 300 or above were required for adequate mixing in this system. Plaques were made and compared to the corresponding polyether diamine without urea moieties. The formulation containing preformed urea moieties in the soft segment produced urea polymers with superior properties such as higher modulus, greater strength, increased hardness, superior organic solvent resistance, and improved green strength at demold. Impact properties were reduced. © 1992 John Wiley & Sons, Inc.
Transmittance and mechanical properties of PMMA‐fumed silica composites
Authors: Abramoff Bennet , Covino Josephine 
Published: April 2003

AbstractThe transmittance, flexure strength, Young's modulus, and Vickers hardness of poly(methyl methacrylate) (PMMA), filled with fumed silica, was measured. Transmittance decreased with increasing content of filler. At 2 vol % filler content, composites had a higher transmittance with a lower surface area of fumed silica (larger primary particle size) because the lower surface area filler was better dispersed. At 4 vol % filler content, composites had a higher transmittance with a higher surface area fumed silica (smaller primary particle size). Flexure strength and Young's modulus of the composites was measured using three point bending. Addition of fumed silica led to a decrease of strength. Also, addition of fumed silica led to an increase of Young's modulus and Vickers hardness. © 1992 John Wiley & Sons, Inc.
Gel permeation chromatography of vegetable‐oil‐based printing ink vehicles
Authors: Erhan S. Z. , Bagby M. O. 
Published: April 2003

AbstractThe apparent weight‐average molecular weights (Mw) of ink vehicles made from soybean, safflower, sunflower, cottonseed, and canola oils were compared by gel permeation chromatography (GPC), and the correlation between viscosity and Mw of these vehicles was established. Apparent Mw of vegetable oil gels that were used in vehicle preparation were also obtained by GPC. © 1992 John Wiley & Sons, Inc.
Effect of epoxy–amine stoichiometry on cured resin material properties
Authors: Palmese G. R. , McCullough R. L. 
Published: April 2003

AbstractSizings and/or surface treatments are commonly employed to enhance the interaction of fiber reinforcements in polymer matrix composites. These modifications can induce physical and chemical interactions that cause local stoichiometric imbalances to occur that can affect the properties of the polymer matrix in the vicinity of the fiber surface. This work reports the results of an experimental study of the influence of stoichiometric imbalance on the thermoelastic properties of an epoxy–amine resin. It is shown that the modulus and glass transition temperature are significantly affected by relatively small variations in stoichiometry. These results suggest that a fiber‐induced interphase region in thermosetting composites can exhibit material properties that are significantly different from those of the bulk resin. © 1992 John Wiley & Sons, Inc.
Photograft copolymerization of methyl methacrylate on viscose fiber using titanium(III) chloride–potassium persulfate redox initiator in a limited aqueous system
Authors: Maji Tarun Kumar , Banerjee Amar Nath 
Published: April 2003

AbstractThe graft copolymerization of methyl methacrylate (MMA) onto viscose fibers were studied under photoactive conditions with visible light using titanium(III) chloride—potassium persulfate as redox initiator in a limited aqueous system. Polymerization carried out in the dark at 40 ± 1°C produced little graft copolymer whereas that in the presence of light at 40 ± 1°C produced significant grafting. Percent grafting, percent total conversion, and grafting efficiency (%) were studied by varying time, initiator concentration, monomer concentration, solvent composition, and pH of the medium. High percent grafting (∼ 200%), high grafting efficiency (∼ 98%), and percent total conversion (∼ 47%) were obtained with little homopolymer formation. A suitable mechanism for grafting has been discussed and also the characterization of the grafted fibers were studied by Fourier transform infrared (FTIR) spectroscopy, thermogravimetry and scanning electron microscopy (SEM). © 1992 John Wiley & Sons, Inc.