bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrostatic charge acceptance and decay of powder coating particles
Authors: Cheever G. Dale 
Published: April 2003

AbstractTechniques have been developed to measure the acceptance and decay of electrostatic charge on a wide variety of powder coatings. The measurement of the initial charge carried by the powder was affected by the amount of powder deposited. The decay of charge occurred within four time scales: (1) 1 sec, electron loss to air and to the metallic substrate; (2) 1 to 5 sec, electron flow to neutralize induced positive charge; (3) 5 to 100 sec, rapid decay from powder; and (4) 1,000 to 10,000 sec, very long term decay. Since the decay of charge was markedly affected by moisture and composition, the decay properties can be controlled by these parameters. A mathematical model was constructed describing the quantitative charge decay during the time period of 100 to 10,000 sec. There was considerable heterogeneity within the powders with regard to charge acceptance and interaction with moisture. These measurement techniques give information concerning electrostatic effects on particle transport, adhesion, and polymer electrostatic behavior which are very important variables in a powder coating process.
Phenol–formaldehyde wood adhesive characterization by proton magnetic resonance spectroscopy
Authors: Steiner P. R. 
Published: April 2003

AbstractAcetylation of phenol–formaldehyde (PF) wood adhesives afforded derivatives which could be characterized by proton magnetic resonance (PMR) spectroscopy. Through use of the chemical shift and integral parameters, relative comparisons were made for the degree of polymerization of resins prepared with different molar ratios. Additionally, PMR studies of these acetylated derivatives provided a means of determining methylol content and number of aromatic protons remaining, and to some extent gave an estimate of molar formaldehyde‐to‐phenol ratio. Experiments conducted with Ca(OH)2 and NaOH as catalysts showed the latter to be the more effective catalyst for PF systems.
Flame‐retardant poly(ethylene terephthalate)
Authors: Koch P. J. , Pearce E. M. , Lapham J. A. , Shalaby S. W. 
Published: April 2003

AbstractPoly(ethylene terephthalate) containing hexabromobenzene, tricresyl phosphate, or a combination of triphenyl phosphate and hexabromobenzene, pentabromotoluene, or octabromobiphenyl was extruded or spun at 280°C into monofilaments or low‐denier yarn, respectively. Only combinations of the phosphorus‐ and halogen‐containing compounds resulted in flame‐retardant poly(ethylene terephthalate) systems, without depreciating their degree of luster and color quality. The melting temperature, the reduced viscosity, and the thermal stability above 400°C of these flame‐retardant systems were in most cases comparable to those of poly(ethylene terephthalate) itself. Phosphorus‐bromine synergism was proposed with flame inhibition occurring mostly in the gas phase.
Stabilization of poly(vinyl chloride). I. Change in color of poly(vinyl chloride) compounded with some metal soaps
Authors: Iida Takeo , Nakanishi Motoharu , Gotō Kunio 
Published: April 2003

AbstractPoly(vinyl chloride) (PVC) with one or more metal salts added was colored by the action of heat to investigate the stabilization mechanism. The coloration and the color difference of heated PVC compound films varied according to the metal salt added. The decoloration of the colored compound films was advanced markedly in THF, DMF, acetone, and ammonia. On the other hand, the heated achromatic PVC film containing Cd/Ba soaps underwent an opposite change, from colorless to yellow orange, in the above materials. This means that the coloration of heated compound films may result from the formation of some complex (for example, π complex of the polyene with the metal chloride). Furthermore, the colored film with cadmium stearate was decolored by roll mixing with the colored film containing barium stearate. These results indicate that the stabilization with metal soaps may be founded on a physical phenomenon such aa an effect of complementary color.
Constrained optimization of cellulose acetate membrane using two‐level factorial design
Authors: Chian Edward S. K. , Fang Herbert H. P. 
Published: April 2003

AbstractThis work presents a method, the SUMT algorithm, to optimize the performance of the cellulose acetate (CA) membrane by maximizing the permeate flux subject to an equality constraint of salt rejection and a pair of inequality constraints for each variable. Three variables, i.e., (1) the concentration of formamide in the casting solution, (2) the time of evaporation of the membrane prior to gelling, and (3) the annealing temperature of the membrane, were selected for this optimization study. Experiments based on the two‐level factorial design were conducted for the determination of regression equations for both premeate flux and salt rejection. At a level of 97.00% rejection of a 0.5% sodium chloride solution at 600 psig, the maximum permeate flux of the CA membrane was predicted to be 14.52 gallons per day per sq. ft (gfd). This was later confirmed by experiments. The effects of the casting variables on membrane performance concluded in this study were consistent with those reported by other researchers.
Mechanism of corona–induced self‐adhesion of polyethylene film
Authors: Owens D. K. 
Published: April 2003

AbstractCorona‐treated polyethylene films have been reported to exhibit strong self‐adhesion when joined together under conditions of heat and pressure that give no adhesion with untreated films. The present study of this effect has shown that the adhesion is completely destroyed by the application of any hydrogen‐bonding liquid to the adhesive joint and that the effects of liquids is completely reversible. Joints allowed to dry recover full strength. These facts together with the results of chemical reactions conducted on the treated film surface have established that the adhesive bond is a hydrogen bond. Corona treatment forms keto groups on the polyethylene chain; these groups enolize and the enolic hydrogens bond with carbonyl groups in the adjacent sheet of film when two sheets are heated together under pressure.
Study on crystallization of nylon 6 (polycapramide). III. Effect of “crystalline memory” on crystallization kinetics
Authors: Turska E. , Gogolewski S. 
Published: April 2003

AbstractThe effect of the initial degree of crystallinity on the isothermal crystallization kinetics from the melt of nylon 6 has been examined. The investigations were carried out in the conditions which allow to maintain a “crystalline memory.” For the investigations, dilatometric and microscopic methods were used depending on the temperature range used. It has been found that for samples of initial crystallinity up to 15% there exists a possibility of the growth of spherulites either from the sporadic or simultaneous nucleation depending on the crystallization temperature. For samples with initial degree of crystallinity higher than 15% the growth of spherulites occurred always from the predetermined nuclei within the investigated range of the crystallization temperature. The crystallization rate of the samples increased with rise in initial degree of crystallinity of the samples.
Effect of high‐abrasion furnace carbon black on the course of thiuram‐accelerated sulfur vulcanization
Authors: Duchác̆ek Vratislav 
Published: April 2003

AbstractThe effect of high‐abrasion furnace (HAF) carbon black on the course of the tetra‐methylthiuram disulfide‐accelerated sulfur vulcanization of natural rubber has been investigated at temperatures from 100°C to 140°C. Continuous measurements in a Vuremo curemeter were used to estimate the extent of crosslinking, which was plotted against cure time. Results now available show (1) HAF carbon black does not alter the mechanism of the thiuram‐accelerated sulfur cure; it also has no qualitative effect on the kinetics of the vulcanization reactions involved. (2) Quantitatively speaking, essential differences take place. The rate constants of vulcanization rise considerably when HAF carbon black is used; there is a dependence on the HAF carbon black content of the rubber compound. Yet the activation energies of vulcanizations are practically the same as in carbon black‐free mixture, amounting to about 31 kcal/mole. (3) Measurements of the course of vulcanizations prove the reinforcing effect of HAF carbon black.
Polymerization of 4‐chloroformylphthalic anhydride with 4,4′‐diaminodiphenylether
Authors: Alvino W. M. 
Published: April 2003

AbstractThe polymerization of 4‐chloroformylphthalic anhydride with 4,4′‐diaminodiphenyl ether was investigated under a variety of reaction conditions. Both interfacial and solution techniques were used, with the latter method yielding the highest molecular weight polymer. Synthesis of high molecular weight polyamide‐imides requires the use of pure monomers, exclusion of moisture, and proper stoichiometry. Molecular weight control can be achieved by the addition of either aniline or phthalic anhydride. Heating of the resin solution for 1 hr at temperatures ≥ 50°C results in a large decrease in inherent viscosity as well as in the polymer properties. Tertiary amines such as triethylamine, when added to the precursor solution, markedly influence the viscosity of the resin.
Properties of poly[N,N′‐(4,4′‐diphenyl ether) 4‐amidophthalimide] film
Authors: Alvino W. M. 
Published: April 2003

AbstractA high molecular weight polyamide–imide polymer derived from the reaction of TMAC–DAPE has been prepared and its film properties have been evaluated. Poly‐[N,N′‐(4,4′‐diphenyl ether) 4‐amidophthalimide] film has an excellent combination of mechanical, electrical, and chemical properties at room temperature and at 200°C. A comparison of the film properties of this material with those of a commercial polyimide film, Teflon, FEP, Nomex paper, and Mylar films is also presented.
Porous polymer carbons. I. Preparation and properties of porous poly(vinylidene chloride) precursor copolymers
Authors: Howard G. J. , Knutton S. 
Published: April 2003

AbstractA series of porous solids has been prepared by the suspension polymerization of mixtures of vinylidene chloride and ethylene glycol dimethacrylate with a nonsolvating diluent. Alteration of the monomer composition and concentration leads to marked variations in the total porosity and pore sizes of the solid polymers. Scanning electron microscopy shows that the suspension‐polymerized beads consist of a microglobular interior encapsulated in a more coherent outer skin. This surface material affects the apparent density of the polymers and their behavior in mercury intrusion porosimetry and low‐temperature nitrogen adsorption.
Porous polymer carbons. II. Preparation and properties of porous poly(vinylidene chloride) carbons
Authors: Howard G. J. , Knutton S. 
Published: April 2003

AbstractSuspension–polymerized copolymers of vinylidene chloride and ethylene glycol dimethacrylate have been converted into carbons by heating to 900°C. Poly(vinylidene chloride) homopolymer may melt on a first‐stage heating at ca. 200°C and consequently yields a fused 900°C carbon; restraining the first‐stage heating to slightly lower temperatures permits the retention of the polymer morphology which is then retained on subsequent carbonization at 900°C. The crosslinked copolymers do not fuse at 200°C and lose the dimethacrylate component, apparently cleanly, in the temperature range of 350–450°C and give 900°C carbons which are shrunken pseudomorphs of the parent polymer; all structural features are retained, including the characteristic skin of the polymer particles. Thus, the macroporous character of the carbons is controlled by both the crosslinker and diluent contents of the original polymerization recipe. The 900°C carbons are also microporous; hysteresis in nitrogen (77°K) isotherms is attributed to activated diffusion since carbon dioxide (196°K) isotherms are reversible. The microporosity of these dual‐porosity carbons depends on the content of crosslinking comonomer in the parent polymer, and possible reasons for this dependence are discussed.
Polymeric ultraviolet absorber
Authors: Mizutani Yukio , Kusumoto Koshi 
Published: April 2003

AbstractPolymeric fine powder, prepared by polymerization of glycidylmethacrylate–divinylbenzene, was reacted with 2,4‐dihydroxylbenzophenone. The resultant polymer was effective as a polymeric ultraviolet absorber, and no migration was observed in polypropylene.
Rheological phenomena during the polymerization of styrene in a stirred tank
Authors: Ide Yoshiaki , White James L. 
Published: April 2003

AbstractAn experimental study of the bulk polymerization of styrene has been carried out. The rate of polymerization, molecular weight, and flow patterns around agitators as a function of conversion have been observed. The rate data are interpreted in terms of free‐radical polymerization kinetics. Duerksen and Hamielec's modified termination rate constant and initiator efficiency relations are generally consistent with our data. The flow patterns were interpreted in terms of the mechanics of viscoelastic liquids and observations for nonreacting systems. Specifically, at low conversions for spheres and similar agitators, the flow patterns are dominated by centrifugal forces with fluid drawn in at the poles and expelled at the equator for spherical agitators. At higher conversions, normal stresses interact with the centrifugal forces causing segregated secondary flow regions adjacent to the sphere. At very high concentrations, normal stresses dominate, yielding Weissenberg effects.
Some observations on the concept of the degree of crystallinity in cellulose fibers with reference to moisture effects
Authors: Ray P. K. , Bandyopadhyay S. B. 
Published: April 2003

AbstractA conceptual effort has been made here to reconcile two approaches of defining the degree of crystallinity by the x‐ray diffraction method, (a) one as proportion of x‐ray diffracting matter in the entire fibrous material, and (b) another as the extent of qualitative perfection of the crystalline region only, since these two approaches often lead to opposite conclusions from the same set of observations.
Reaction during cure of a blocked isocyanate–epoxy resin adhesive
Authors: Hartz Roy E. 
Published: April 2003

AbstractModel compound reactions of isocyanate sources with alcohols and an epoxy resin indicated that the major reaction product from the phenol‐blocked methylenebisphenylene diisocyanate and epoxy resin‐based adhesive dip for poly(ethylene terephthalate) cord was a polyurethane. A significant portion of the hydroxyl groups required for the reaction were formed by ring opening of the epoxide groups of the resin. The reaction rate for the unblocking of the isocyanate source was inhibited in the presence of polyester yarn finishes containing sulfated esters of fatty acids. Also, compounds containing carboxylic acid groups and sulfonic acid groups inhibited the unblocking step. Amines and their salts catalyzed the unblocking step. A mechanism for the polyurethane adhesive–polyester bond based upon physical interaction is postulated. The presence of certain nonsulfated ester finishes permitted good wetting of the polyester surface and penetration of the adhesive into the polyester. By contrast, sulfated ester finishes result in poor wetting and penetration by the adhesive on the polyester. By contrast, sulfated ester finishes result in poor wetting and penetration by the adhesive on the polyester. The latter finishes resulted in a weak boundary layer between the adhesive and the cord.
The kinetics of two‐phase bulk polymerization. I. Monomer and initiator distribution
Authors: Ludwico W. A. , Rosen S. L. 
Published: April 2003

AbstractRubber‐reinforced thermoplastics are produced commercially by dissolving a rubber in the monomer of a glassy polymer and commencing polymerization with a free‐radical initiator. Beyond a few per cent conversion, the incompatibility of the two polymers causes a phase separation, with each phase containing one nearly pure polymer. Subsequent polymerization occurs in each phase. The heterogeneous nature of the reaction can influence both the kinetics of the reaction and the amount of grafting in the product. The fact that only monomer which polymerizes in the rubber phase can possibly graft establishes an upper limit to the amount of grafting and hence influences the mechanical properties of the product. It is shown theoretically how unequal partitioning of monomer and initiator between the phases can influence the extent of grafting, and can also explain the kinetic rate reductions which have been observed in such systems. The distributions of monomer and benzoyl peroxide and azobisisobutyronitrile initiators between the phases have been determined experimentally for a styrene–polystyrene–polybutadiene system. They cannot account for the rate reduction observed in such systems.
Variability of ultimate properties of elastomers
Authors: Fedors R. F. 
Published: April 2003

AbstractThe measurement of the ultimate properties of elastomers is characterized by variability in the data. For example, when a sufficient number of specimens is tested, distributions in the values of the stress‐at‐break, strain‐at‐break, and time‐to‐break are commonly obtained. It is pointed out that such variability can be rationalized on the basis of variations in both the degree of crosslinking and in the size of naturally occurring flows present in the elastomer.
A computer implementation of frequency–temperature superposition for dynamic mechanical transformations
Authors: Engel P. A. , Sacher E. 
Published: April 2003

AbstractThe usual procedure for shifting dynamic mechanical data, involving the construction of a master plot, was compared with a simpler, computer‐implemented double shift procedure, which obviates the need for such a construction. Data reproducibility indicates that the double shift may successfully be shifted to frequencies greater than one decade to either side of the experimental range.
Analysis of a living polymer mixture by use of small‐molecule gel permeation chromatography
Authors: Cox James H. , Anthony Rayford G. 
Published: April 2003

AbstractA procedure is presented for determining the concentration of polymer lithium, alkyllithium, and monomer by use of small‐molecule GPC. The system poly(styryllithium), butyllithium, styrene, and benzene are used to illustrate the method. The method as presented has a lower limit on the direct measurement of butyllithium concentration of 0.00005 molar. If the total carbon‐bound lithium is to be determined, the limit can be appreciably lowered. The styrenebenzene separation was obtained for concentration ratios of 1:5 or greater. Several suggestions are presented for improving these analyses.
Anomalous behavior of electrical conductivity and thermal noise in carbon black‐containing polymers at Tg and Tm
Authors: Klason Carl , Kubát Josef 
Published: April 2003

AbstractPronounced maxima in resistivity–temperature curves have been found at or above Tg for a number of amorphous polymers (PS, PMMA, PVC) containing a small percentage of carbon black. The maxima appeared only after a certain period of storage at T < Tg or at heating rates substantially higher than those used in cooling the samples prior to the measurement. For this reason, no maxima were observed during cooling. In crystalline polymers (PE, PP), maxima at Tm appeared both on heating and cooling. Marked relaxation effects (time‐dependent resistivity) were recorded in the Tg and Tm regions. Good agreement was found between resistivity and thermal noise data.
Factors affecting the photo‐induced graft copolymerization of methyl methacrylate onto fibrous polymer
Authors: Ogiwara Yoshitaka , Kubota Hitoshi , Yasunaga Toshio 
Published: April 2003

AbstractThe effects of sample swelling, photosensitizer, and solvent on the photo‐induced graft copolymerization of methyl methacrylate onto fibrous polymers such as Vinylon, nylon 6, and polyester were examined. Each separate factor, sample swelling, or solvent, or their combination, increased activity of polymerization. Only some sensitizer were effective. Studying the ESR spectra of photo‐irradiated polymers also showed that either the sample swelling, the photosensitizer, or the organic solvent is very effective for the formation of polymer radicals under irradiation.
The near infrared spectra of some polyamic acid resins
Authors: Crandall E. W. , Johnson E. L. , Smith C. H. 
Published: April 2003

AbstractThe absorption spectra of a series of polyamic acids prepared using various reaction conditions were studied using the ultraviolet (UV), visible, and near‐infrared (IR) ranges. The near‐IR proved most valuable; the amidization and imidization processes could be followed by observing the change of intensities of the 1950‐nm combination amine band and a band at 2300 nm assumed to be a function of the amide group.
A new rheological constitutive equation for the network model of polymer melts
Authors: Ronca G. , Conti W. 
Published: April 2003

AbstractA new network model is suggested and a constitutive equation is developed on the basis of the assumed validity of Boltzmann's superposition principle for the shear stress. The predictions of the model concerning the relaxation behavior of polymer melts after steady shear or instantaneous deformation are compared to Lodge's theoretical results and to experimental data from the literature.
Formation of 2,4‐dinitrophenylhydrazones in high‐density polyethylene film irradiated with ultraviolet light
Authors: Kato Koichiro 
Published: April 2003

AbstractPolyethylene films were irradiated in air by ultraviolet light. 2,4‐Dinitrophenylhydrazine was reacted on the irradiated films. The changes in amounts of carbonyl groups and 2,4‐dinitrophenynlhydrazones formed in the films were inferred by comparing their absorptions in the infrared and ultraviolet spectra, respectively. It seems that the contents of carbonyl groups formed in the amorphous regions in the high‐density polyethylene films by the irradiation were larger than the contents of carbonyl groups formed in the amorphous regions in the low‐density polyethylene films. The decreases in contact angles of water on the high‐density polyethylene films by the irradiation were larger than the decreases in the contact angles on the low‐density polyethylene films. The amounts of 2,4‐dinitrophenylhydrazones formed in the irradiated high‐density polyethylene films were less than the amounts of 2,4‐dinitrophenylhydrazones formed in the irradiated low‐density polyethylene films.
The structural color in the polymer blend of poly(methyl methacrylate) and polystyrene
Authors: Uemura Yukikazu , Aoyagi Masaya 
Published: April 2003

AbstractMorphologic and optical studies were performed on the coloring of poly(methyl methacrylate) (PMMA) and polystyrene (PS) opal sheet. It was concluded that the origin of color is the polymer structure itself. There exist three structures in the colored polymer blend: small PS spheres are dispersed in the PMMA matrix, and each PS sphere contains smaller PMMA spheres within it. The dimension of the smaller PMMA spheres is of the same order as the wavelength of visible or near‐infrared light. The coloring measured by a spectrometer is well interpreted by the equation of structural color derived by Clewell qualitatively.