bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature effect on polymer mechanochemistry
Authors: Casale Antonio
Published: April 2003

The influence of temperature is a fundamental variable for the mechanochemical processes of high polymers. However, it is generally recognized that the effect of temperature in this process is not always direct, as in normal chemical reactions, but is mainly indirect involving change in the properties (principally elastic and viscous), in the physical state of the system, and consequently in the mechanism of rupture. The negative temperature coefficient has been considered a prime criterion of a mechanochemical reaction by many researchers. Recently, it has been suggested that the negative temperature coefficient is really due to the viscous heating during polymer deformation and the low thermal conductivity of polymers.

The aim of this paper is to reevaluate the role of temperature on mechanically induced reactions of polymers. In light of evidences published in the last 30 years, the dependence of mechanochemical reaction on temperature must involve the overlapping of the following factors: (1) the usual positive dependence of rate on temperature, as predicted by Arrhenius equation; (2) the true experimental temperature, which depends on viscous heating and on thermostatting efficiency; and (3) the breaking tension at the center of the polymer chain which is inversely dependent on temperature, i.e., greater at the higher viscosity and the slower relaxation at the lower temperatures, this last factor being dominant in determining the characteristic negative temperature coefficient for polymer mechanochemistry.
Removal of cupric ion from solution by contact with peanut skins
Authors: Randall John M. , Reuter F. William , Waiss Anthony C.
Published: April 2003

Certain tannin‐containing agricultural wastes, such as peanut skin, are highly efficient ion exchange materials for the removal of cupric ion from aqueous waste solutions. Concentrations of Cu2+ as high as 200–1000 ppm can be reduced to less than 0.5 ppm by pouring the waste solution through a short column of peanut skin. The column packing can take up greater than 10% of its weight in copper, even from 50 ppm solution. Complete regeneration of the packing is readily achieved by eluting the Cu2+ from the column with 0.1 N HCl. The ion exchange process is pH dependent, with optimum removal of copper from solution occuring in the 5–7 pH range. Two hydrogen ions are liberated into solution for each Cu2+ attached to the peanut skin, so pH decreases as reaction continues, inhibiting the reactions. Thus, a continuous column process would be more efficient than a stepwise batch process.
Reactions catalyzed by soda lime glass. II. Polymerization of methyl methacrylate
Authors: Moustafa A. B. , Diab M. A.
Published: April 2003

Rates of sodium bisulfite‐initiated polymerization of methyl methacrylate (MMA) in water were determined in the presence and absence of colorless and colored soda lime glass (amber glass). The rate of polymerization increased in the presence of glass. For example, the rate of polymerization increased from 1.3 × 10−5 mole/(1.sec) to 3.9 × 10−5 mole/(1.sec) when amber glass (200 mesh) concentration was varied from 0 to 30 g/l. of the reaction mixture at 40°C. It was found that the finer the particle size of the soda lime glass, the higher was the conversion percentage of monomer to polymer. A glass–polymer combination containing 20 g glass was prepared and subjected to Soxhlet extraction with benzene; the insoluble polymer part was found to increases as initiator concentration was decreased.
Change of polypropylene film surface by chromic acid mixture treatment
Authors: Kato Koichiro
Published: April 2003

Polypropylene films were treated with chromic acid mixture. The change in the treated films was investigated by comparing change in amount of 2,4‐dinitrophenylhydrazones formed in the treated films with their change in wettability with water. Oxidation of the film surface zone, partial breakdown of polymer in the film surface zone, and oxidation of surface zone bared from the film inner zone seemed to occur with increase in treatment time or with increase in treatment temperature.
Exclusion chromatography using controlled‐porosity glass. I. Comparison with styrene gels
Authors: Spatorico A. L.
Published: April 2003

The instrumental parameters influencing the calibration of a gel permeation chromatograph (GPC) using column packings of Corning CPG‐10 porous glass have been evaluated. The porous glass system used a set of columns 1.6 × greated in length and 0.6 × smaller in diameter than the Styragel system, which was used for comparison. The dependence of retention volume of polystyrene calibrants on eluent flow rate and on sample size was similar in both systems. Samples of poly(methyl methacrylate), poly(vinyl choloride), and poly(4,4′‐isopropylidenediphenylene 1,1,3‐trimethyl‐3‐phenylindan‐4′,5‐dicarboxylate) fractions were examined, and the molecular weights, obtained by using the hydrodynamic volume concept, were in satisfactory agreement with the light‐scattering data for both chromatographic systems. Corrections for axial dispersion, for the polyester fractions and polystyrene samples, were probably equivalent in these two chromatographic systems.
Effect of temperature on the course of thiuram‐accelerated sulfur vulcanization
Authors: Ducháček Vratislav
Published: April 2003

Tetramethylthiuram disulfide‐accelerated sulfur vulcanization of styrene‐butadiene rubber has been investigated at temperatures from 100°C to 170°C over 0.5 to 600 min. Continuous measurements in a Vuremo curemeter were used to estimate the extent of crosslinking, which was plotted against cure time. Apart from the induction period (ti), the kinetic graphs are satisfactory represented by a rate equation assuming three independent first‐order reactions: fast crosslinking, degradation, and slow crosslinking. The rate equation contains seven kinetic parameters. Over the temperature range studied, there is no difference between the values of activation energy for ti−1, for fast crosslinking, and for degradation. The activation energy of slow crosslinking only is significantly greater. Due to the presence of Aerosil, the reciprocal values of the induction periods and the values of the ultimate extents of fast crosslinking are increased, and the values of the rate constants of degradation and slow crosslinking are decreased. Simultaneously, the activation energy of slow crosslinking is also significantly decreased. On the basis of these results, the proposed theory of tetramethylthiuram disulfideaccelerated sulfur vulcanization supposing that zinc dimethyldithiocarbamate is the actual accelerator in this type of curing system is discussed.
Synthesis of peracid‐type resins and their characteristics as oxygen transfer agents
Authors: Takagi Toru
Published: April 2003

Synthesis of peracid‐type resins (PAR) by oxidation of carboxylic acid‐type ion exchangers with H2O2 in sulfonic and sulfuric acid media has been studied. Influence of composition of the resins and acid concentration of the media on the conversion of carboxylic to percarboxylic acid groups in the resins is discussed. PAR can oxidize various organic compounds in good conversion. It is especially noteworthy that the increase in the polarity of the solvent increased the rate constants in the epoxidation of cyclohexene with PAR, in contrast with the low molecular weight peracids, and the epoxidation of 1‐olefins, geometric isomers of cyclododecene, and cholesterol with PAR took place selectively with regard to chain length or steric configuration. The results are discussed on the basis of distribution effect, protective effect with polymer, steric interactions between overall molecule of the substrates and polymer matrix, and other factors.
Solvent effect on the time constant of concentrated polymer solutions
Authors: Rao Vadlamudi G. , Gandhi K. S.
Published: April 2003

The time constant, τ, signifying the onset of non‐Newtonian behavior of polymer solutions is known to be a function of mass concentration, C, molecular weight, M, temperature, T, and zero shear viscosity, η0. Williams' theory predicts that the time constant is also affected by the solvent character. To study the predicted effect, the time constants of poly(methyl methacrylate) solutions in chlorobenzene (good solvent) and m‐xylene (poor solvent) were experimentally determined. It was found that the ratio of the time constant to the Rouse relaxation time was a function of the combined variable CM. For all values of CM, both the time constant and the ratio of the time constant to the Rouse relaxation time were larger in a poor solvent than in a good solvent. This behavior may be attributed to the relatively stronger attractive interpolymer molecular forces present in solutions in poor solvents. As the temperature is raised the poor solvent becomes better and the ratio of the time constant to the Rouse relaxation time is found to become independent of solvent character.
Preparation of reverse osmosis membranes by surface modification of polymeric films. I. Surface acetylation of cellulose
Authors: Hillman J. J.
Published: April 2003

Surface acetylation of cellophane to afford an asymmetric membrane having high desalination ability (as high as 98% sodium chloride rejection) is described. The films were characterized by multiple‐internal‐reflectance microscopy (MIR), dyeing tests, light microscopy, and determination of water and sodium chloride transport properties in reverse osmosis cells. Surface modification employing acetyl chloride and acetic anhydride was studied in detail: the influence of the cellophane employed, the degree of cellophane activation, reaction time, reagent concentration, and diluent were assessed. Mixed acetylation reactions are also discussed as well as an evaluation of various postconditioning treatments used to increase desalination.
An apparatus for the measurement of dynamic mechanical properties of polymers in a gas medium with the vibron viscoelastometer
Authors: Murayama Takayuki , Silverman Bernard
Published: April 2003

The Vibron Viscoelastometer is useful for obtaining dynamic mechanical properties of film and fibers in atmospheres at 0 and 100% relative humidity. No apparatus has previously been available for obtaining dynamic mechanical properties in a gas medium; however an apparatus and procedure have been developed for measuring these dynamic properties in a gas medium using the Vibron instrument. This technique will be useful in studies on the effects of different gases on polymers in the process and on the effects of gas treatments on materials. A new gas cell which is adaptable for other mechanical testing instruments such as the Instron, Tensometer, and Torsion Pendulum is also discussed.
Polypropylene fibers melt‐spun in the presence of torsional shear
Authors: Andersen P. G. , Test S. , Deo S. R. , Carr S. H.
Published: April 2003

Melt‐spun fibers of isotactic polypropylene have been formed using specific combinations of shearing and elongational flow. Such rheological conditions were achieved with a take‐up device capable of subjecting molten polymer filaments continuously to various combinations of torsional and elongational strains. Relationships were determined between mechanical properties of the resulting fibers and their molecular organizations. The results obtained indicated that these flow fields would produce fibers whose mean‐preferred‐chain‐orientation directions ranged between being tilted radially from a direction parallel with the fiber axis (no torsional shear strain imposed) and having some additional tilt that is tangential with respect to the fiber circumference (some torsional shear strain imposed). It is not possible to resolve the observed helical chain tilts into contributions from crystalline and amorphous regions, respectively.
The rheological properties of molten mixtures of polyoxymethylene and copolyamide: Their fibrillation and microstructure
Authors: Ablazova T. I. , Tsebrenko M. B. , Yudin A. B. V. , Vinogradov G. V. , Yarlykov B. V.
Published: April 2003

The rheological properties of molten mixtures of polyoxymethylene and copolyamide have been investigated by the methods of capillary viscometry over a wide range of shear stresses. It has been found that at relatively close values of the melt viscosity polyoxymethylene (POM) and copolyamide (CPA) form mixtures which differ markedly in viscosity and elastic properties from the original polymers. Depending on the magnitude of the shear stress, the viscosity of mixtures of definite composition may be either higher or lower than the viscosity of the components. Three‐ to tenfold swelling of the stream emerging from the capillary is observed for such mixtures, whereas at the same temperatures and stresses no swelling of the POM and CPA extrudates is practically observed. The data obtained are accounted for by the fact that the flow of mixtures through the capillary involves the formation of hundreds of thousands of ultrathin fibres of POM in the matrix of CPA, which are oriented along the flow axis.
Determination of heats of volatilization for polymers by differential scanning calorimetry
Authors: Frederick W. J. , Mentzer C. C.
Published: April 2003

In the design of thermal degradation processes for polymers, the energy to degrade or volatilize the materials soften must be known. The heats of volatilization for six polymers were measured by differential scanning calorimetry (DSC), where the area under the degradation endotherm peak was shown to be directly proportional to the heat of volatilization. Values measured for poly(methyl methacrylate), which yields monomer quantitatively in the temperature range investigated, agree well with theoretically predicted values. Reproducibility of the method is shown by an average standard deviation of ±10% for the six polymers investigated. Caution must be used when applying data obtained by this method to thermal conditions widely differing from those employed in the DSC.
Thickness variation in the thermoforming of poly(methyl methacrylate) and high‐impact polystyrene sheets
Authors: Lai M. O. , Holt D. L.
Published: April 2003

The influence of material flow properties on the variation of wall thickness in a thermoformed part was investigated by measuring the thickness reduction at the pole of free‐formed axisymmetric domes of poly(methyl methacrylate) and high‐impact polystyrene. It was found that at a given pole height, the thickness reduction in poly(methyl methacrylate) was less than in high‐impact polystyrene, i.e., the wall thickness in a part formed from poly(methyl methacrylate) will be more uniform than in a part formed from high‐impact polystyrene by the same technique. This difference in formability was ascribed to a difference in the dependence of the flow stress σ at the thermoforming temperatures on time. The flow stress of both materials was given by σ = Ktm′ϵn, but whereas n was approximately 1 for both materials, m′ was −0.052 and −0.33 for poly(methyl methacrylate) and high‐impact polystyrene, respectively. A physical argument and simple analysis led to the conclusion that a large (negative) value of the “stress relaxation index” in a material reduces the degree of uniformity of sheet thickness in a formed part.
Polyurethane–polyacrylate interpenetrating polymer networks. II
Authors: Frisch K. C. , Klempner D. , Migdal S. , Frisch H. L. , Dunlop A. P.
Published: April 2003

Two component topologically interpenetrating polymer networks of the SIN type (simultaneous interpenetrating networks) composed of a melamine‐cured polyacrylate and three different polyether‐based polyurethanes were prepared. The linear polymers and prepolymers were combined in solution, together with the necessary crosslinking agents and catalysts, films were cast and subsequently chain extended and crosslinked in situ. In all cases, maxima in tensile strength significantly higher than the tensile strengths of the component networks occurred at 50% polyurethane : 50% polyacrylate. This was explained by an increase in crosslink density resulting from interpenetration. One of the interpenetrating polymer networks showed only one glass transition temperature (Tg) (measured calorimetrically) intermediate in temperature to the Tg's of the components and as sharp as the component Tg's. This is indicative of phase mixing and indicates at least partial chain entanglement (interpenetration). Some enhancement of other physical properties was also noted.
Effect of polymeric silane coupling agents on adhesion of polypropylene and polystyrene to glass
Authors: Inoue Hiroshi , Kohama Shigemi
Published: April 2003

The coupling performance of some polymeric silane compounds was compared with that of the monomeric silanes for adhesion of polypropylene (PP) and polystyrene (PS) to glass. A silylated poly‐1,2‐butadiene was found to be effective for PP and, on the other hand, some copolymers derived from styrenyl triethoxysilane or γ‐methacryloxypropyl trimethoxysilane for PS. Benzoyl peroxide also showed a pronounced effect on the adhesion of PP, rather than that of PS. The adhesion strength was approximately correlated with the contact angles of the resin melts on the coated glass, intensively suggesting the dependence of compatibility between resinous matrix and coupling agent on the adhesion. Their critical surface tensions, thermal behavior, and infrared spectra were also measured to discuss the relationship between the surface constitution and the adhesion effect.
The limits of linear viscoelasticity in poly(methyl methacrylate) and poly(ethyl methacrylate)
Authors: Bertilsson Hans , Jansson Jan‐Fredrik
Published: April 2003

The limit of linear viscoelasticity is determined for poly(methyl methacrylate) (PMMA) and poly(ethyl methacrylate) (PEMA) in uniaxial tension creep over the temperature range of 20° to Tg −10°C. The time span covered is from 10 to 1000 sec. The linear limit is defined as the point at which the creep compliance deviates by more than 1% from its mean value in the linear viscoelastic range. For both materials, the stress limit of linear viscoelasticity falls to a minimum or plateau level at a temperature below Tg. It is suggested that the β‐mechanism plays an important role in the existence of this minimum.
Anionic graft copolymers. I. Poly(vinyl chloride)‐g‐polystyrene. Preparation and characterization
Authors: Lechermeier G. , Pillot C. , Gole J. , Revillon A.
Published: April 2003

Graft copolymers of PVC‐g‐PS of controlled branching were prepared by carbanionic deactivation. The reaction products were characterized mainly by GPC. It appears that secondary reactions affect the efficiency of the grafting, chiefly at low ratios of polystyrene to poly(vinyl chloride). Techniques of grafting and analyses are discussed.
Determination of formation and relaxation of crazes by permeability measurements
Authors: Nicolais L. , Drioli E. , Migliaresi C.
Published: April 2003

Formation and relaxation of crazes on different polymeric films are determined by permeability measurements in a high pressure test cell. Thermal dependence of the films permeability has been studied and interpreted on the basis of segmental movement of the macromolecules.

These permeability measurements also offer a way to determine the glass transition temperature of amorphous films.
Strain energy functions of rubber. I. Characterization of gum vulcanizates
Authors: James A. G. , Green A. , Simpson G. M.
Published: April 2003

A plot of principal stress difference versus principal extension ratios has been used as a graphic representation of general deformation. Two analytic forms of the strain energy function for isotropic, incompressible materials are suggested. These involve five or nine terms, the coefficients of which are found by regression to the general deformation plot. The resulting stress–strain equations are used to predict particular deformations, for example, simple extension, and are also evaluated in model engineering desing experiments. These experiments use interative techniques to predict the shapes and pressures of inflated diaphragms and tubes, and it is shown that the equations lead to accurate results even at relatively high extensions.
Retention of thermal antioxidants in polyethylene by silane coupling agents. III. Copper deactivators
Authors: Albarino R. V. , Schonhorn H.
Published: April 2003

Stabilizer activity has been correlated with physical retention and state of dispersion in aged polyethylene films. Incompatibility and poor state of dispersion were found to limit long‐term performance of otherwise chemically efficient stabilizers. A practical method to improve compatibility and state of dispersion of stabilizers involves complexation of nonfunctional stabilizer phenolic groups with N‐β‐(aminoethyl)‐γ‐aminopropyltrimethoxysilane. Substantial improvement in retention and state of dispersion may be realized with antioxidant–silane weight ratios of 1:1.
Effect of nucleating agents upon the kinetics of poly(ethylene terephthalate) crystallization
Authors: Przygocki Wladyslaw , Wlochowicz Andrzej
Published: April 2003

Experiments have been conducted to examine the effect of the following agents: TiO2, CaO, MgO, BaSO4, SiO2, and Al2O3 as modifiers on the poly(ethylene terephthalate) crystallization kinetics. Modifier concentration in the polymer varied from 0.5% to 3%. Crystallization rate measurements at a temperature of 237°C were performed by dilatometric method and measurements of spherulitic growth rate, by microscopic method. It has been stated that the addition of a modifier affects the crystallization rate, dimension, and homogeneity of spherulitic sizes. The spherulitic growth rate, with the exception of that modified by CaO, does not depend on the kind and the concentration of a modifier. Heterogeneous nucleating agents exert an effect, then, mainly on the heterogeneous nucleation process. In the presence of the agents, the nucleation in the poly(ethylene terephthalate) is of athermal character. The kind of a modifier applied exerts also an effect on the final crystallization degree.
Fluorocarbon bibenzoxazole polymers: Transitions and thermal stability
Authors: Schoff C. K. , Gillham J. K.
Published: April 2003

The thermomechanical behavior (−180° to 500°C) in nitrogen is reported for two fluorocarbon bibenzoxazole homopolymers and a corresponding copolymer. The dynamic mechanical spectra were generated at low frequencies (∼1 Hz) by an adaptation of the torsional pendulum, torsional braid analysis (TBA), which uses polymer/glass braid composites as specimens. The effects of the variations in molecular structure on physical transitions and thermal stability are discussed. Of particular interest are the specific submolecular assignments for the two glassy‐state transitions (T < Tg) found for each polymer.
The states of water in cellulose acetate membranes
Authors: Taniguchi Yoshio , Horigome Shinkichi
Published: April 2003

Differential scanning calorimetric melting endotherms of wet and half‐dried cellulose acetate membranes and salt distribution coefficients were studied to clarify the states of water in membranes. We have suggested that (a) there are four states of water in cellulose acetate membranes; (b) these states of water are those of completely free water, free water very weakly interacting with polymer, bound water which can contain salts, and bound water which rejects salts; (c) the semipermeability of membranes depends on the ratio of four states of water in membranes.
The effect of UV light on the subsequent thermal volatilization of poly(methyl acrylate)
Authors: McGill W. J.
Published: April 2003

Films of poly(methyl acrylate) were exposed to UV light for periods of up to 45 min and were then degraded thermally under vacuum and at atmospheric pressure in nitrogen. Short exposures caused a marked decrease in the initial rate of thermolysis, and this was attributed to the removal of active centers. The formation of crosslinks during photolysis severely decreased the subsequent rate of volatilization of the polymer by inhibiting the unbuttoning chain reaction mechanism. Volatilization of exposed films under vacuum was slower than at atmospheric pressure in nitrogen, and this was attributed to the loss by evaporation of active centers. Activation energies for thermolysis before and after UV exposure were 160 and 167 kJ/mole, respectively. The subsequent thermal behavior of films exposed to UV light in oxygen and nitrogen atmospheres was closely similar.
Reversible amine solubilization of cured siloxane polymers
Authors: Hsiao Y.‐C. , Hill L. W. , Pappas S. P.
Published: April 2003

We report that aliphatic primary and secondary amines completely solubilize crosslinked silicone resins and rubber compositions at room temperature. The solubilization is attributed to nucleophilic cleavage of SiO bonds by amines, which apparently occurs selectively at crosslinking sites. The selectivity may reflect the presence of three oxygen atoms at such sites, which are expected to enhance the electrophilicity of silicon. On evaporation of amine, crosslinks are apparently regenerated as evidenced by solubility characteristics as well as film properties of the reclaimed silicones. In addition to their theoretical interest, these results are potentially important from the standpoint of commercial applications as well, including the possible reclaiming of silicone‐constituted furniture molds and the coating of heat‐sensitive materials.
Energy balances and uniaxial damage of highly filled elastomers
Authors: Lepie Albert H. , Adicoff Arnold
Published: April 2003

A propellant sample undergoes internal damage while it is tested at finite deformation. The damage consists of broken molecular chains and void spaces which form around the filler particles and contribute to failure of the propellant. Attempts were made to determine the amount of this damage from the viewpoint of energy dissipations. Mechanical energy losses, called damage energy, were computed from energy changes during tension cycling experiments carried out at different temperatures and straining rates. Shift procedures were applied to the experimental results, and a double‐reduced master curve for damage energies was obtained by using time–temperature and strain shift factors. The reduced master curve can be used to predict the extent of damage accumulated in a propellant sample during tensile tests at different straining rates and temperatures.
Thermal analysis of poly(1,3,4‐oxadiazole‐2,5 diyl‐1,2‐ethenediyl) and poly(1,4‐phenylene‐1,3,4‐oxadiazole‐2,5 diyl‐1,2 ethendiyl)
Authors: Varma I. K. , Geetha C. K.
Published: April 2003

Poly(1,3,4‐oxadiazole‐2,5‐diyl‐1,2‐ethendiyl) and poly(1,4‐phenylene‐1,3,4‐oxadiazole‐2,5 diyl‐1,2‐ethenediyl) have been prepared by condensation polymerization using fuming sulfuric acid and different quantities of terephthalic acid (T), fumaric acid (F), and hydrazine sulfate (HS). Homopolymers of F and T and various copolymers of F:T have been prepared. The polymer structure was investigated by IR and visible‐range spectra and elemental analysis. The existence of poly(1,3,4‐oxadiazole‐diylphenylene) and poly(hydrazoterephthaloyl) structures was revealed by these studies. These polymers were thermally stable, and most of them did not show a weight loss below 350°C. The relative thermal stabilities of the various polymers have been evaluated by “integral procedural decomposition temperature” and activation energy measurements.
Morphological studies on wettability and tackiness of pressure‐sensitive adhesives
Authors: Hino Kinnosuke , Ito Toshio , Toyama Mitsuo , Hashimoto Hatsujiro
Published: April 2003

The surface structure of pressure‐sensitive adhesives consisting of natural rubber and pentaerythritol ester of hydrogenated rosin has been studied using the single‐stage replica method. The fibril structure with average diameter of about 50 Å was observed on the surface of an adhesive consisting of 40 to 60 wt‐% resin at which maximum tack is obtained. The role of fibrils in adhesion is discussed.
Criterion of ion separation by reverse osmosis
Authors: Fang Herbert H. P. , Chian Edward S. K.
Published: April 2003

The order of ion separation by the NS‐100 membrane differed slightly from that of the cellulose acetate membrane. The separation of an ion by the NS‐100 membrane increased with increase in the valence of the ion, but decreased with the increase in the ionic radius. The sole criterion determining this separation order for the NS‐100 membrane was the enthalpy of hydration. An ion having a higher enthalpy of hydration is bulkier in the hydrated form and is, therefore, separated more effectively by the NS‐100 membrane, according to the diffusional model of solute separation. The permeability of an ion through the membrane material can be related to its enthalpy of hydration. By using this relationship, the separation of individual ions in aqueous solution with a given NS‐100 membrane can be predicted from a test with a sodium chloride solution.
New method of determining contact angle between monofilament and liquid
Authors: Yamaki Jun‐Ichi , Katayama Yuzo
Published: April 2003

This paper describes a method to obtain contact angle by observing the shape of a liquid drop attached to a monofilament. The relations between contact angle and the dimensions of drops are theoretically obtained. Thus, it is possible to calculate the contact angle if drop shape is measured. Through use of this method, the contact angles of epoxy resin on various kinds of monofilaments were measured. It was found that this method has practical utility for measurement of the contact angle between liquid and monofilament.
Exclusion chromatography using porous glass. II. Application to hydrophilic polymers
Authors: Spatorico A. L. , Beyer G. L.
Published: April 2003

A chromatograph employing five columns packed with porous glass of pore size 1250 Å to 75 Å provided peak retention volumes (VR) that were reproducible and essentially independent of sample size and flow rate when aqueous eluents were used. Calibration was carried out with a series of dextran fractions and polystyrene sulfonate samples, both of moderately narrow molecular weight distribution. The universal calibration method, based on hydrodynamic volume, was tested for four different polymer types. All four types produced a common curve within experimental error, which indicates that absolute molecular weight distributions may be derived from aqueous exclusion chromatography data for at least these polymer types. Additional study using a higher salt concentration produced hydrodynamic‐volume plots that superposed with those above. The use of the same set of porous glass columns with polystyrene standards in three different organic solvents produced calibration curves that agreed well with the aqueous curves after corrections were made for differences in available pore volumes.
Polyimides from diisocyanates, dianhydrides, and tetracarboxylic acids
Authors: Alvino William M. , Edelman Leonard E.
Published: April 2003

High molecular weight polyimide resins have been prepared by the reaction of diisocyanates and a mixture of dianhydrides and their acids in the presence of a tertiary amine catalyst. The polyimides thus formed can be made into tough flexible films similar to those polyimides prepared by the conventional method of reacting a dianhydride with a diamine. The preparation of high molecular weight polymer is affected by the purity of reagents, the anhydride‐acid ratio, temperature, and moisture. Evidence from model compound studies is presented regarding the nature of the reaction mechanism.
Preparation of composite reverse osmosis membranes by plasma polymerization of organic compounds. III. Plasma polymers of acetylene/CO/H2O
Authors: Yasuda H. , Marsh H. C.
Published: April 2003

Reverse osmosis characteristics of composite membranes prepared by the plasma polymerization of acetylene/CO/H2O mixtures with various ratios of components are investigated; porous film of cellulose nitrate‐cellulose acetate is used as the substrate. This monomer system seems to have the following advantages: (1) A relatively short deposition time (1–2 min) is enough to produce reasonably good reverse osmosis membranes; and (2) good chemical stability of membranes can be obtained, especially in the case of chlorine resistance.
On the thermal degradation of poly(vinyl chloride). III. Structural changes during degradation in nitrogen
Authors: Abbås K. B. , Sörvik E. M.
Published: April 2003

The structural changes in poly(vinyl chloride) during thermal degradation in nitrogen at 190°C have been investigated. From gel permeation chromatography analyses no chain scission, but only crosslinking reactions were observed. An increase in the molecular weight was measured even at 0.3% conversion. For longer polyene sequences and at higher conversions, a crosslinking reaction competed with the “zipper” propagation. The secondary reactions, were more extensive at longer polyene sequence lengths. The growing polyene sequences can be terminated not only by branching reactions but also at existing pendent chloromethylene groups. A decrease in the amount of short chain branching with conversion also indicated other types of secondary reactions. Such a decrease was also observed during thermomechanical degradation in a Brabender Plastograph. The average polyene sequence length was calculated to be around 10, depending somewhat on the type of analysis used. Although allylic chlorine atoms seem to be the main points of initiation, other sites cannot be excluded as the number of initiation points increases appreciably during the early stages of the degradation. Such an increase is, of course, also consistent with a radical mechanism.
End‐wise degradation of hydrocellulose during hot alkali treatment
Authors: Johansson Mats H. , Samuelson Olof
Published: April 2003

Determinations of reducing and carboxylic acid end groups in hydrocellulose treated with hot alkali showed that the end‐wise degradation proceeded to such an extent that some of the molecules were brought completely into solution. The major carboxylic acid end groups formed in reactions competing with the end‐wise degradation were 3‐deoxyhexonic and 2‐C‐methylglyceric acids; but 2‐deoxypentonic, 2‐C‐methylpentonic, and minor amounts of aldonic acids were also formed. The formation of these stable end groups explains the observed increase in number average degree of polymerization during the treatment. The ratio between the number of lost glucose moieties and the number of carboxylic acid groups formed in the solid phase was about 170 and was only slightly affected by the duration of the hot alkali treatment.
Mechanism of low‐profile behavior in single‐phase unsaturated polyester systems
Authors: Pattison Victor A. , Hindersinn Raymond R. , Schwartz Willis T.
Published: April 2003

The mechanism of the low profile behavior in certain single‐phase polyester systems has been examined. It appears that as polymerization occurs, crosslinked beads (< 1μ) of polymer separate from the bulk solution. As the temperature rises, liquid monomer expands, counteracting polymerization shrinkage. As shrinkage surpasses expansion towards the end of polymerization, stresses are induced in the system. These are relieved internally by a series of micro cracks in the continuous matrix of the polymer rather than, as in ordinary systems, through macroscopic shrinkage of the molded part.
Study of the glass transition of poly(ethylene terephthalate) by gas chromatography
Authors: Hsiung P. L. , Cates David M.
Published: April 2003

The technique of gas chromatography is used to detect the temperature (Tg) at which the solubility of organic solutes in poly(ethylene terephthalate) (PET) becomes detectable, when the temperature is raised from below to above the glass transition temperature. For a given solute, Tg varies with the structure of PET. For a given structure of PET, Tg varies with the nature of the solute.
Craze growth and void coalescence in PMMA round notched bars
Authors: El‐Hakeem H. , Marshall G. P. , Zichy E. L. , Culver L. E.
Published: April 2003

A study of the kinetics, failure mechanism, and fracture surfaces of PMMA/methanol crazes has been made on notched circular bar specimens subjected to constant tensile loads. Failures were by void growth and coalescence inside the craze away from the notch tip and near to the specimen center. Two distinct features of void coalescence were observed; the first a cluster of very small voids (each of the order of 3.4 × 103 Å) and the second, separate larger voids which usually caused final failure.

An analysis of craze growth, based on fracture mechanics concepts in conjunction with simple flow analysis, suggests that the growth is controlled mainly by the ability of the environment to flow through the voided structure of the craze. Good agreement has been obtained between predicted behavior and experimental data.
Infrared detection of polymers in gel permeation chromatography
Authors: Dawkins John V. , Hemming Malcolm
Published: April 2003

A gel permeation chromatograph equipped with an on‐line Grubb‐Parsons infrared spectrometer is described. The versatility, specificity, sensitivity, and limitations of such an infrared detector are discussed with particular reference to spectrometer specification, eluent absorbance, and solute absorbance. A stable baseline is produced when this detector is operated at high temperatures, e.g., for the separation of polyethylene in o‐dichlorobenzene at 135°C. Individual functional groups in a chemically inhomogeneous solute, such as a copolymer, may be monitored by repeated injections of the solute, changing the wavelength setting between separations. This procedure is illustrated with AB poly(styrene‐b‐t‐butyl methacrylate) block copolymer in trichloroethylene at 35°C.
A rheological model of viscose rayon
Authors: Aksan Stanisława , Żurek Witold
Published: April 2003

In viscose rayon samples subjected to cyclic loading the phenomenon of supertension was observed as a variation of the linear elasticity limit in the consecutive cycles. To enable a mathematical description of this phenomenon a rheological model with an inertional‐frictional element was devised. The curves calculated on the basis of the model well approximated the experimental results.
The effect of pressure on carbon black/elastomer powders. IV. Comparison of press‐cured powders containing vulcanizing agents with mill‐mixed compounds
Authors: Angerer G. , Schilling H.
Published: April 2003

SBR latex was compounded with six different types of carbon black (SRF, FEF, HAF, SAF, HEB, and HCC‐I) and vulcanization ingredients in aqueous dispersion by means of a dispersing agent. The particle size of the carbon black agglomerates in aqueous dispersion was estimated from turbidity and light scattering measurements. It was found that the size of the aggregates is by far larger than the average particle size of the SBR‐latex used. The latex mixture containing carbon black and vulcanization ingredients was spray‐dried to a fine‐sized powder of an average particle size of 0.25 mm; this powder was subsequently vulcanized without the action of shear forces at a pressure of 200 bar. It was the aim of this study to answer the question whether latex‐stage compounded vulcanizates can be reinforced without applying shear forces, if only the distribution of the carbon black in the compound is sufficiently good. The tensile strength was used for judging reinforcement; the quality of the carbon black dispersion was estimated by means of the Cabot rating method. The carbon black dispersion in the compounded powders proved to be excellent with fine‐sized carbon blacks and was in the order of A 1 and B 2 of the Cabot scale. Scanning electron micrographs of the fracture zones and transmission electron micrographs on ultrathin cuts showed, however, differences in the microdispersion of the carbon blacks between powder‐and mill‐mixed compounds. A comparison of the mechanical properties of powder‐and mill‐mixed compounds yielded partially comparable tensile values for the powder compounds up to 20 MN/m2, but strikingly high hardness, elongation set and a pronounced stress‐softening after repeated deformation (Mullins‐effect).
An investigation of the surface areas of dyed and undyed secondary cellulose acetate by p‐nitrophenol adsorption
Authors: Blair Hal S. , McElroy Mervyn J.
Published: April 2003

The surface areas of dyed and undyed secondary cellulose acetate fibers were estimated using p‐nitrophenol adsorption. When values of specific surface area are plotted against dye concentration, there is a marked change in the region corresponding to a theoretical monolayer adsorption of the dye.
Analysis for vinyl chloride in PVC powders by head‐space gas chromatography
Authors: Berens A. R. , Crider L. B. , Tomanek C. J. , Whitney J. M.
Published: April 2003

At a temperature above the glass transition point of poly(vinyl chloride) (PVC), the solubility of vinyl chloride monomer (VCM) in PVC accurately follows Henry's law behavior for VCM contents up to 4000 ppm. This observation has lead to a rapid, simple gas‐chromatographic method for the determination of VCM in PVC from the analysis of the vapor phase (head‐space) over PVC powder samples in a sealed container. The basic experimental techniques, calculations, and examples of experimental data are given. The method can be used with any commercial gas chromatograph equipped with a flame ionization detector without instrument modification.
Block polymers from isocyanate‐terminated intermediates. IV. Properties of cured butadiene–ε‐caprolactam block polymers
Authors: Hergenrother William L. , Ambrose Richard J.
Published: April 2003

Butadiene–ε‐caprolactam block polymers containing a high proporation of 1,2 units in the butadiene‐segments were synthesized and physical properties were measured on the cured copolymers. Flexural strength and impact resistance both increase regularly with increasing ε‐caprolactam content in peroxide cured copolymers. This behavior is explained by the higher values of flexural modulus and impact resistance for poly(ε‐caprolactam) compared with peroxide‐cured polybutadiene resins. Copolymers reinforced with silica showed higher heat distortion temperatures but lower impact resistance than corresponding unfilled samples. Arrhenius plots of flexural properties at various test temperatures were linear. Both flexural modulus and strength decreased regularly with increasing test temperature. Flexural properties of filled copolymers were relatively unaffected by heat aging up to 204°C for several weeks, however, dramatic decreases in these properties were noted in a matter of days when heat aging was done at 260–316°C. These results are explained by the rapid degradation of poly(ε‐caprolactam) above its melting point. Block polymers whose butadiene segments contained a high proportion of 1,4 units were also synthesized. These copolymers were elastomeric when cured with either sulfur or peroxide.
Mechanical degradation of dilute solutions of high polymers in capillary tube flow
Authors: Culter John D. , Zakin Jacques L. , Patterson Gary K.
Published: April 2003

Experimental results on mechanical degradation in capillary tubes of polyisobutylene polymers in dilute solution are described. In laminar flow, degradation is independent of tube length, indicating that entrance effects are dominant. This shows that capillary experiments do not yield explicit information on the effect of shear stress on mechanical degradation. In turbulent flow, large entrance effects are also observed, but some degradation does take place in the fully developed flow region.
Porous polymer carbons. V. Macroporous carbons from crosslinked α‐chloroacrylonitrile polymers
Authors: Ehigiamusoe R. E. , Howard G. J.
Published: April 2003

Suspension copolymerizations of α‐chloroacrylonitrile and divinylbenzene have been carried out both with and without diluents. The polymers are macroporous except for those without diluent and of higher crosslinker content. At a fixed divinylbenzene content, the macroporosity increases with diluent content and is always higher with nonsolvating diluent. The gross morphologic features of the polymers depend on the crosslink density and on both the nature and amount of the diluent; scanning electron micrographs of typical examples are shown. Semicarbons are readily produced by dehydrochlorination. On full carbonization at 900°C, microporous carbons are produced which have some residual nitrogen‐containing groups able to act as specific sites for anionic adsorbates. Homopoly α‐chloroacrylonitrile fuses on heating to 900°C unless it has been previously dehydrochlorinated by treatment with base. All crosslinked polymers give carbons which are pseudomorphs of the original specimens.
Client‐side monitoring for Web mining
Authors: Fenstermacher Kurt D. , Ginsburg Mark
Published: April 2003

“Garbage in, garbage out” is a well‐known phrase in computer analysis, and one that comes to mind when mining Web data to draw conclusions about Web users. The challenge is that data analysts wish to infer patterns of client‐side behavior from server‐side data. However, because only a fraction of the user's actions ever reaches the Web server, analysts must rely on incomplete data. In this paper, we propose a client‐side monitoring system that is unobtrusive and supports flexible data collection. Moreover, the proposed framework encompasses client‐side applications beyond the Web browser. Expanding monitoring beyond the browser to incorporate standard office productivity tools enables analysts to derive a much richer and more accurate picture of user behavior on the Web.
DocCube: Multi‐dimensional visualisation and exploration of large document sets
Authors: Mothe Josiane , Chrisment Claude , Dousset Bernard , Alaux Joel
Published: April 2003

This paper presents a novel user interface that provides global visualizations of large document sets in order to help users to formulate the query that corresponds to their information needs and to access the corresponding documents. An important element of the approach we introduce is the use of concept hierarchies (CHs) in order to structure the document collection. Each CH corresponds to a facet of the documents users can be interested in. Users browse these CHs in order to specify and refine their information needs. Additionally the interface is based on OLAP principles and multi‐dimensional analysis operators are provided to users in order to allow them to explore a document collection.
ZstatFlu®‐II test: a chemiluminescent neuraminidase assay for influenza viral diagnostics
Authors: Achyuthan Komandoor E. , Pence Lisa M. , Appleman James R. , Shimasaki Craig D.
Published: April 2003

The ZstatFlu®‐II test is a highly sensitive, specific, rapid, point‐of‐care chemiluminescent diagnostic test for influenza infection. Influenza viral neuraminidase‐specific substrate, spiroadamantyl‐1,2‐dioxetane‐4,7‐dimethoxy‐N‐acetyl‐neuraminic acid, is at the core of the ZstatFlu®‐II Test. The enzymatic reaction was carried out at 25°C and neutral pH, representing the optimum assay conditions for influenza types A and B viral neuraminidases. The results were outputted on a Polaroid™ High Speed Detector Film. Positive results appeared as a ‘+’‐shaped white film image; negative results produced no image. The ‘glow’ kinetics, facilitated by a unique combination of light enhancers, also ‘tuned’ the wavelength of emission to match the spectral properties of the film. The substrate hydrolysed non‐enzymatically at acid pH or at temperatures above 25°C. In order to minimize false positives, the ZstatFlu®‐II Test was formatted with 0.3–0.4 Km substrate and freezing the test kit until use. The pH optimization of the ZstatFlu®‐II test is discussed with reference to model compounds of sialyl‐glycosides. A nucleophilic attack or an electrostatic stabilization of a developing carbonium ion under the influence of the adjacent carboxyl group was probably responsible for non‐enzymatic hydrolysis of the substrate. Intramolecular general acid catalysis is proposed as a mechanism for the lability of the O‐glycosidic linkage of the substrate. Copyright © 2003 John Wiley & Sons, Ltd.