bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some analogies in the mechanical behavior of filled polymers
Authors: Lipatov Yu. S. , Babich V. F. , Rosovizky V. F. 
Published: April 2003

AbstractThe temperature and frequency dependences of complex shear modulus and mechanical losses were studied for expoxy resin composition in the presence of different amounts of quartz and polystyrene fillers. The data obtained were analyzed by the use of the Williams‐Landell‐Ferry method. It was shown that in the mechanical behavior of filled polymers, except for the well‐known temperature‐time analogy there exist some lows connected with the presence of filler. The change in filler concentration leads to the same change in the real part of complex modulus as change in frequency (concentration–time analogy), and change in temperature is equivalent to concentration change (temperature–concentration analogy). The existence of these analogies is explained by a change in deformation conditions for polymeric matrix in the presence of different amount of filler, by the existence of surface layers of polymer at the interface with solid filler, and by peculiarities of the mechanical behavior of filler. It is also established that the thickness of surface layer which was determined from experimental data depends on temperature and has an extremum in the temperature region of the α‐transition.
Triplet‐state quenching by photostabilizers of polyolefins
Authors: Adamczyk A. , Wilkinson F. 
Published: April 2003

AbstractParamagnetic nickel(II) complexes which are used as commercial photostabilizers of polyolefins are shown in laser photolysis studies to quench the triplet state of benzophenone in dilute benzene solution. The efficiency of quenching observed is less than that of diamagnetic square‐planar nickel(II) complexes which are more effective photostabilizers of polypropylene in “Xenotest” experiments. The observed rate constants for quenching of triplet benzophenone are compared with those observed by other workers for quenching of singlet oxygen, O2*(1Δg), in dilute solution. The relevance of these studies to the understanding of photodegradation in polyolefins is discussed.
An experimental study of threadline dynamics with emphasis on the effect of molecular weight on the elongational viscosity of melt‐spun poly(ethylene terephthalate)
Authors: Hill Jack W. , Cuculo John A. 
Published: April 2003

AbstractA study of a melt‐spun threadline has been carried out to determine the effect of molecular weight on the elongational viscosity of the polymer being spun. Polymer chosen for this study was poly(ethylene terephthalate) having different molecular weights. Conventional nonisothermal spinning of the polymers was carried out with cooling by free convection. Threadline surface temperatures were measured by a null‐balance technique. Threadline tension at the take‐up device was measured, and samples of the threadline were taken to obtain linear density profiles. Nonlinear least‐squares fits were applied to the linear density data to obtain equations for velocity and elongation rate. These measurements were then used to determine the threadline elongational viscosity. Least‐squares fits were made to a polynomial relating absolute temperature and elongation rate to the elengational viscosity. These results were then used to determine an activation energy of elongational flow which was found to decrease with elongation rate. Elongational viscosity was found to increase with molecular weight.
A new method of moisture penetration measurement in protective coatings
Authors: Rybicky J. , Marton J. P. 
Published: April 2003

AbstractVarious methods are used by the paint and coating technologists to evaluate the resistance of protective coatings to penetration of water through them. This article intends to introduce a new, simple method for the moisture resistance evaluation. The method uses thin metal films as the sensor and is not absolute. However, it may be very useful for comparative experiments when the paint formulator seeks an optimum performance of coating developed for moisture protection.
Strain behavior of particulate‐filled composites
Authors: Leidner J. , Woodhams R. T. 
Published: April 2003

AbstractA theoretical expression has been derived to describe the strain behavior of rigid plastic composites containing spherical filler particles. By combining the predicted ultimate strength values with the appropriate modulus relationship, the complete stress–strain history and corresponding fracture energy may be estimated. The theoretical predictions were compared with experimental values obtained for a general‐purpose polyester resin containing spherical glass beads. The influence of silane coupling agents and filler adhesion was also evaluated. Although the experimental values showed considerable scatter, the general trend agreed fairly well with the theoretical predictions.
Kinetic study of the thermal decomposition of poly(oxypropylene) glycols by differential scanning calorimetry
Authors: Van Kim Vo , Malhotra Shadi L. , Blanchard Louis‐P. 
Published: April 2003

AbstractThe thermal decomposition of poly(oxypropylene) glycols was studied under nitrogen and dynamic operating conditions over the temperature range of 320° to 700°K by means of a differential scanning calorimeter. The differential energy losses due to changes in emissivity of the reference and sample pans were computed by modifying the baseline of the thermograms. Kinetic parameters obtained with the help of the Borchardt and Daniels theory indicate that the reaction is zero order and that the activation energy increases with molecular weight of the polymer. The rate of heating of the sample, the rate of flow of nitrogen, and the initial mass of the sample do not have significant effects on the kinetics of the decomposition.
Electron spin resonance studies on graft copolymerization of gaseous styrene onto preirradiated polypropylene. II. Preirradiation under vacuum
Authors: Nunome Keichi , Eda Bunzo , Iwasaki Machio 
Published: April 2003

AbstractGraft copolymerization of gaseous styrene was carried out at 40°C onto polypropylene preirradiated under vacuum. In order to investigate the origin of graft initiation activity, ESR spectra of irradiated polymers were measured and discussed. Although there are about three times as many radicals trapped in the sample irradiated at −78°C as in the sample irradiated at room temperature, both the samples showed nearly same degree of grafting. This is due to the ineffectiveness of radicals trapped in the amorphous region for grafting. The samples irradiated under vacuum showed more grafting than those irradiated in an oxygen atmosphere. This is compatible with the conclusion in the previous paper that in grafting of polypropylene irradiated in an oxygen atmosphere the carbon radicals produced by hydrogen abstraction by trapped peroxy radicals are the effective active centers.
Electron spin resonance studies on graft copolymerization of gaseous styrene onto preirradiated polypropylene. III. Preirradiation under vacuum followed by exposure to oxygen at −78°C
Authors: Nunome Keichi , Eda Bunzo , Iwasaki Machio 
Published: April 2003

AbstractGrafting of styrene vapor was carried out onto polypropylene γ‐irradiated under vacuum followed by exposure to oxygen at −78°C. A comparison with the results on polypropylene irradiated in an oxygen atmosphere leads to an interesting result. Two samples were irradiated at room temperature under vacuum and in an oxygen atmosphere, respectively, the former being followed by exposure to oxygen. Although irradiation was carried out at room temperature for either sample and nearly the same amounts of the peroxy radicals are trapped, the former showed more grafting than the latter. The origin of this difference was investigated by means of electron spin resonance. Significant differences were observed in ESR spectra as well as in isothermal decays of the trapped peroxy radicals. In the former sample, the trapped peroxy radicals had a higher mobility, and consequently a significant hydrogen abstraction by the peroxy radicals was observed during storage at 40°C. This result supports the conclusion of the previous paper that the radicals effective in the grafting reaction of polypropylene preirradiated in an oxygen atmosphere are the carbon radicals which are produced by hydrogen abstraction by the peroxy radicals.
Morphologic accessibility of wood adhesives
Authors: Chow S. 
Published: April 2003

AbstractAccessibility of wood adhesives was determined using a potassium bromide‐embedding technique during resin cure. Cured resin was then extracted with water, followed by x‐ray analysis of residual potassium bromide retention in the adhesive matrix. Cured urea–formaldehyde (UF), phenol–formaldehyde resol (PF), and phenol–resorcinol formaldehyde (PRF) accommodated large quantities of potassium bromide. However, only PRF adhesive showed crystallization of trapped potassium bromide, suggesting the presence of large pore sizes in the polymer lattices. Both UF and PRF adhesives, after room‐temperature soaking, were equally resistant to water access. At higher temperature, water accessibility of UF increased greatly which may be attributed to thermal softening of the adhesive, while the accessibility of water to the PRF adhesive matrix was mainly a surface phenomenon and was not very temperature dependent. PF was highly accessible to water, even at room temperature, as a result of swelling from the presence of sodium hydroxide (catalyst). Accessibility of PRF adhesive was greatly increased by base (NaOH) solutions but not by acid (H2SO4) solutions. The UF resin showed slight increase of accessibility with increase in acidity and basicity of the water solution, but the accessibility increase of this adhesive in base solution was substantially less than that of PRF. The acid hydrolysis influence on accessibility increase of UF adhesive was far less severe than that of temperature.
Photostabilizing effect of Ni(II) chelates in polymers. II. Effect of diamagnetic chelates on polypropylene phosphorescence
Authors: Harper D. J. , McKellar J. F. , Turner P. H. 
Published: April 2003

AbstractExamination of the phosphorescence emission form polypropylene shows the lifetime of the emission to be unaffected by a hydroxybenzophenone light stabilizer but significantly shorted by a diamagnetic Ni(II) chelate stabilizer.
The distribution of olefinic linkages in elastomers
Authors: Anderson J. N. 
Published: April 2003

AbstractA method for determining the distribution of olefinic bonds in elastomers has been developed using dual detector GPC analysis of the polymer after derivatization with 2,4‐dinitrobenzenesulfenyl chloride. The method is particularly useful for determining the distribution of olefinic bonds in hydrocarbon copolymers having small levels of unsaturation.
Polar and steric effects in reverse osmosis
Authors: Matsuura Takeshi , Bednas M. E. , Dickson J. M. , Sourirajan S. 
Published: April 2003

AbstractThe effects of polar parameter Σσ* and steric parameter ΣEs on reverse osmosis separations of alcohols, aldehydes, ketones, and ethers (noncyclic) in aqueous solutions involving single solute systems and porous cellulose acetate membranes are discussed. The least‐squares and multiple‐regression analyses of solute transport parameter data show that the separation of aldehydes, just as that of alcohols, is predominantly a function of Σσ*, and that of ethers is predominantly a function of ΣEs, whereas that of ketones is best represented as a function of both Σσ* and ΣEs. The results also indicate that even where water is preferentially sorbed at the membrane solution interface, solute separation in reverse osmosis is affected by the nonpolar character of the solute molecule. A general expression for solute transport parameter in reverse osmosis is presented for further study.
Cellophane for kidney dialysis
Authors: Monk D. W. , Wellisch E. 
Published: April 2003

AbstractA new cellophane has been developed for use as a membrane in artificial kidney dialysis. Modification of the standard viscose casting and regeneration conditions produced films having permeabilities highly competitive with the cellulosic membranes presently employed in kidney dialysis. These modified cellophanes have permeabilities superior to the European cuprammonium films for all molecular species investigated. The greater permeabilities were found to be due to a much increased sweiling of these films resulting in a very small amount of cellulose which forms the barrier to molecular diffusion. These new cellophane structures also exhibit reasonable wet strength characteristics. The cellophane membranes offer the potential for obtaining a domestic membrane supply. This study indicates that although additional development work is required to produce a highly competitive membrane, these early results look extremely promising.
Studies in chemically modified celluloses. VII. Periodate oxidation of cellulose dyed with reactive dyes
Authors: Shenai V. A. , Wagh S. P. 
Published: April 2003

AbstractPeriodate oxidation of cellulose and cellulose dyed with reactive dyes at 32°C in the presence and absence of various concentrations of alkali metal chlorides and sulfates has been studied. The extent of oxidative degradation undergone by cellulose and assessed in terms of copper number and cuprammonium fluidity of the oxidized dyeing, the oxygen consumption during the oxidation, and the rate constant were shown to be markedly increased by the presence of the salts in the oxidizing solution. Borohydride and chlorous acid treatment were used to further modify the periodate oxycelluloses, and the effect of these treatments on the properties was studied.
Dynamic mechanical properties of deformed rubber‐modified acrylics
Authors: Krause S. , Broutman L. J. 
Published: April 2003

AbstractRubber‐modified acrylic polymers with rubber contents of 0, 1, 4, 7, 10, 13, and 16% were investigated to determine the effects of cold deformations on their mechanical and dynamic mechanical properties. A Rheovibron was used to determine damping as a function of temperature at four frequencies. A cold‐rolled film and a cold‐drawn film, stretched until fully crazed, were investigated. It was shown that cold deformation produces a small shift in the glass transition temperature of the rubber phase while the activation energy remains nearly unchanged. Also, the nature of the damping curve of the glassy matrix near the glass transition temperature of the matrix is altered by the appearance of a shoulder in the curve.
New static and dynamic stiffness testers
Authors: Jellinek H. H. G. , Kachi H. 
Published: April 2003

AbstractInstruments have been developed for the testing of stiffness of polymers in various gaseous environmental “atmospheres” over a large range of temperatures. They are based on the cantilever principle, where a small strip of a specimen is deflected statically or periodically. Changes in stiffness are measured as function of the bending force or power input, respectively. The dynamic instrument responds very sensitively to the onset of cracking in specimens due to ozone exposure. The static instrument is well suited for measuring the onset of rapidly increasing stiffness as temperatures are lowered.
Newer intermediates for plastics and coatings. III. Polyesters based on methylene‐di‐β‐oxynaphthoic acid
Authors: Kondekar Ninad , Potnis S. P. 
Published: April 2003

AbstractA tetrafunctional dibasic acid, methylene‐di‐β‐oxynaphthoic acid (MDNA), has been used for preparation of unsaturated polyester resins. The films obtained from these products have excellent chemical and physical properties comparable to epoxy resins and to a large extent balance some of their shortcomings such as darker color, higher viscosities, and higher cooking temperatures. The possible applications of these resins are coatings where acid, corrosion, and thermal resistance are of primary importance.
DSC study on recrystallization of amorphous cellulose with water
Authors: Kimura Minoru , Hatakeyama Tatsuko , Nakano Junzo 
Published: April 2003

AbstractThe recrystallization of amorphous cellulose at various relative humidities was studied to clarify the relation between the amount of adsorbed water in cellulose and the molecular motion by the DSC method. The initial recrystallization kinetics of amorphous cellulose at various relative humidities were observed on the basis of the exothermic peak between 380° and 470°K in a DSC curve. The recrystallization occurred easily by conditioning at higher than 80% R.H., but hardly by conditioning at lower than 65% R.H. These facts suggest that the conformation of cellulose seems to be easily changeable if cellulose has a moisture regain which is approximately comparable to capillary water. When the Avrami equation was applied to the slope of calorific value versus conditioning time at higher than 80% R. H., it also appeared that the mode of recrystallization growth of amorphous cellulose exposed to water vapor is one‐dimensional.
Electroinitiated polymerization of trioxane dispersed in n‐hexane and n‐heptane
Authors: Mengoli Giuliano , Vidotto Graziano 
Published: April 2003

AbstractThe possibility of electroinitiating the polymerization of melted trioxane dispersed in nhexane and n‐heptane has been investigated. It was found that the addition under stirring of an electrolyte to these dispersions added a satisfactory electrolytic conductivity: this fact allows, by a fast current pulse, the anode transfer of a charge suitable to initiate the polymerization process. The kinetics of the polymerization do not exhibit substantial induction periods and depend both on the charge initially transferred to the system and on the diluent‐to‐monomer ratio. The molecular weights of the products, which are generally high, are controlled by the same parameters and by the extent of the monomer‐to‐polymer conversion. The effect on the process of the background electrolytes perchlorate and tetrafluoborate of tetrabutylammonium has been investigated, and the possible initiation mechanism has been discussed. The conditions also for obtaining thermally stabilized products by trioxane–1,3‐dioxolane copolymerization in the same systems have been shortly investigated.
A radial cell model for a tubular polymerization reactor
Authors: Schrenk L. , Kuester J. L. 
Published: April 2003

AbstractA cell model for the prediction of temperature and concentration gradients in a nonisothermal tubular polymerization reactor at steady state is presented. Both radial and longitudinal gradients are considered. The complete molecular weight distribution is calculated as well as the leading moments of the distribution. The model is easily reduced to predict the performance of a plug‐flow tubular reactor, batch reactor, and continuous stirred tank reactor (CSTR). The specific polymerization mechanism application consists of free‐radical initiation, propagation, and combination termination.
Modified bead spring theory of dilute polymer solutions. III. Inclusion of multiple relaxation times
Authors: Everage A. E. , Gordon R. J. 
Published: April 2003

AbstractA previously derived constitutive equation, representing a blending of the molecular dumbbell theory and a continuum theory of anisotropic fluids, has been extended to the multidumbbell (Rouse‐Zimm) case. The equation thus derived yields predictions equivalent to the Rouse‐Zimm theory in small‐amplitude dynamic shearing, with the exception that the introduction of an “effective molecular weight” as the concentration of polymer is increased is no longer required. In simple shearing flow, the theory predictions are far superior to those of the Rouse‐Zimm model, yielding realistic non‐Newtonian viscosity behavior, a positive primary normal stress difference, and a negative secondary normal stress difference. In stress relaxation following the cessation of steady shearing flow, the rate of relaxation is found to depend to the initial velocity gradient, but the effect is predicted to be too small to be observed experimentally in typical dilute polymer solutions. The effects of molecular weight, molecular weight distribution, and polymer–solvent interaction are explicitly accounted for, and in all cases the theory predictions are in excellent qualitative agreement with accepted experimental behavior.
Photosensitized degradation of polyolefins
Authors: Cernia E. , Mantovani E. , Marconi W. , Mazzei M. , Palladino N. , Zanobi A. 
Published: April 2003

AbstractThe effect of aromatically substituted dienes such as 1,1,4,4‐tetraphenylbutadiene (TPB) as sensitizers of the accelerated oxidative photodegradation of polyethylene has been studied. The mechanism of photosensitization has been investigated by ESR and IR spectroscopy, while the degradation rate has been monitored by following the change of the mechanical properties during accelerated indoor and outdoor weathering tests. It was found that TPB is an efficient sensitizer for the oxidative degradation of polyethylene. The degradation of the polymer takes place via 1O2 formation, and it was interpreted on the basis of two simultaneous processes. In the first, excited singlet oxygen (1O2) is produced by TPB itself or by ketonic impurities present in the polymer. In the second, 1O2 reacts with TPB giving benzophenone, peroxides, and other oxygenated products which in turn can promote the degradation of polyethylene. Irradiation carried out in the absence of air seems to rule out the possibility of a photodegradation mechanism via excitation of TPB to an upper excited state capable of hydrogen abstraction from the polymer.
Grafting of formaldehyde‐crosslinked and cyanoethylated cotton cellulose with acrylate monomers
Authors: Varma D. S. , Narasimhan Veena 
Published: April 2003

AbstractFormaldehyde‐crosslinked cotton and cyanoethylated cotton were grafted with methyl, ethyl, and n‐butyl acrylates and methyl methacrylate using ceric ion as initiator. It was observed that the graft yields for formaldehyde‐crosslinked cotton were significantly higher than those for native cotton. An increase in the bound formaldehyde resulted initially in a decrease in molecular weight of grafts; but later on, an increase was observed. In the case of cyanoethylated cottons, increasing the degree of substitution resulted in increase in graft yields. Molecular weights of the grafts increase up to a D.S. of 0.3, after which they decrease. These results are interpreted in terms of rates of initiation and termination being influenced by production of additional sites due to swelling of cellulose fibers.
The effects of branching and other physical properties of anionic polyacrylamides on the flocculation of domestic sewage
Authors: Anthony Alan J. , King Paul H. , Randall Clifford W. 
Published: April 2003

AbstractThis investigation was undertaken to evaluate the effect of long‐chain branching of anionic polyacrylamides on the flocculation of domestic sewage. The polyelectrolytes were polymerized using a redox couple, selectively hydrolyzed, and then characterized by means of light‐scattering photometry. Coagulation tests were then employed to evaluate the synthesized polymers. The optimum polymer dose for suspended solids removal was used as the basis for evaluating each anionic polyacrylamide fraction with respect to its ability to flocculate domestic sewage. The results of this investigation indicated that as the weight‐average molecular weight increased, the optimum polymer dose decreased. For polymers of similar molecular weights and differing radii of gyration, as the radius of gyration increased, the optimum polymer dose decreased, indicating that the “linear” polymers were more efficient in removing suspended solids than the “branched” polymers.