bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimum method for osmotic pressure measurements with membrane‐permeating solutes
Authors: Hayduk W. , Laudie H.
Published: April 2003

Osmotic pressure experiments were conducted with PVC samples of different molecular weights dissolved in THF, using both a block osmometer and a Hewlett‐Packard automatic osmometer equipped alternately with Schleicher and Schuell 07 and 08 membranes to optimize the procedure for accurate osmotic pressure measurements. It was found that, provided a flow of solvent could be maintained through the membrane and into the solution, an osmotic pressure of good accuracy was obtained even though the membrane was nominally much too coarse for the polymer analyzed.
Terpolymers. I. The mechanical properties and transition temperatures of terpolymers of n‐octadecyl acrylate, ethyl acrylate, and acrylonitrile
Authors: Jordan Edmund F. , Riser George R. , Salber Charles , Wrigley A. N.
Published: April 2003

Earlier work revealed that the internal plasticization of polyacrylonitrile by the higher n‐alkyl acrylates or N‐n‐alkylacrylamides yielded only brittle copolymers. This difficulty was circumvented in the present work by starting with copolymers of acrylonitrile and ethyl acrylate, over the range of compositions, and further modifying these by incrementally displacing the ethyl acrylate in each recipe by n‐octadecyl acrylate through terpolymerization. In this way, the stepwise small reduction in Tg for the base ethyl acrylate–acrylonitrile copolymers was greatly increased for each of the terpolymers. Compositions were obtained ranging from glassy, brittle terpolymers, with glass transitions above room temperature, to soft plasticized polymers having sufficient polar networks retained from the nitrile to confer useful properties. The decline in the glass temperature was shown to be dependent on the free volume conferred by the side‐chain methylene groups of each acrylate ester. In contrast, the decline in tensile and flexural strengths and moduli for the terpolymers having glass transitions above room temperature was produced entirely by the presence of the methylene groups of the 18‐carbon ester. The glass transition region corresponded to room temperature when the acrylonitrile content of the base copolymer had been reduced to 50 mole‐%. Terpolymers of this nitrile content and lower had the low moduli and large elongations of plasticized compositions. An equation was developed which correlated empirically the glass transitions and the mechanical properties with the weight fraction of the acrylate esters for the glassy terpolymers.
Drag reduction in dilute polymer solutions
Authors: Kelkar J. V. , Mashelkar R. A.
Published: April 2003

The problem of drag reduction in a helically coiled tube is examined experimentally. The general problems involved in the correlation of drag reduction data are analyzed critically, and some important recommendations are made based on the findings of this work. A phenomenological approach is suggested for correlating the drag reduction data. An examination of the straight‐tube data from the literature and the coiledtube data obtained in this work shows that for a variety of aqueous polymer solutions the data could be uniquely correlated by the following equation:

where β = reduced friction factor and De′ = modified Deborah number.
Thermomechanical behavior of poly(carborane–siloxane)s containing CB5H5C cages
Authors: Roller M. B. , Gillham J. K.
Published: April 2003

The thermomechanical spectra of two new carborane–siloxane polymers containing five‐boron carborane cages in the backbones are reported and discussed. The polymers are the homopolymer, HO[Si(CH3)2CB5H5CSi(CH3)2O]nH, and the random copolymer with 20 mole‐% of the ten‐boron meta‐carborane analogue, [Si(CH3)2CB10H10CSi(CH3)2O]. The mechanical spectra (∼1 cps) were determined from −180° → +625° → −180°C (ΔT/Δl = 3.6°C/min for T > 25°C and 2°C/min for T < 25°C) using the semimicro thermomechanical technique, torsional braid analysis. In nitrogen, both polymers displayed secondary transitions at −140°C. The glass transition (Tg) for the homopolymer was −60°C and for the copolymer was −52°C. The homopolymer had a melting point of +70°C. The copolymer was amorphous. The high‐temperature stability in nitrogen of both polymers appeared to be identical; thermal stiffening commenced at 400°C, continued to 625°C, and resulted in materials that were typical of highly crosslinked resins. In air, the homopolymer began to stiffen catastrophically near 270°C, while the copolymer began to stiffen similarly nearly 50°C higher. The intrinsic elastomeric nature together with the thermomechanical results prompted further study of the copolymer. Thermomechanical cycling studies in nitrogen and air are reported for the copolymer. Some correlating TGA and DTA are also discussed.
Interaction of Biebrich Scarlet with keratoses from performic acid‐oxidized wool
Authors: Rao L. Seshagiri , Rattee I. D.
Published: April 2003

The interaction of the acid dye Biebrich Scarlet (C.I. Acid Red 66) with α‐, β‐, and γ‐keratoses obtained from wool fiber by performic acid oxidation was studied. The extrapolated saturation values of dye bound to protein and the association constants for the interactions were obtained. Maximum dye uptake was found for α‐keratose, followed by γ‐ and β‐keratoses, in that order. Incorporation of varying amounts of m‐cresol in the dye solutions showed no significant effect. There was no indication of an interaction between m‐cresol and the keratoses from direct studies.
Thermal stability of “living” polymer–lithium systems
Authors: Kern W. J. , Anderson J. N. , Adams H. E. , Bouton T. C. , Bethea T. W.
Published: April 2003

The thermal stabilities of polybutadienyllithium, polyisoprenyllithium, and polystyryllithium solutions have been determined in hydrocarbon solvents. Kinetic analysis indicated that a complex mechanism was involved in the thermolysis of polybutadienyllithium. The thermal stability was observed to increase with increasing lithium concentration, suggesting the presence of competitive reactions in addition to the expected elimination of lithium hydride. The thermal stability of the three systems studied was consistent with their reported degrees of association: dimeric polystyryllithium was less stable than tetrameric polyisoprenyllithium or hexameric polybutadienyllithium.
Thermolytic reactions of polybutadienyllithium
Authors: Anderson J. N. , Kern W. J. , Bethea T. W. , Adams H. E.
Published: April 2003

In addition to the expected elimination of lithium hydride, metalation and addition reactions have been observed as competitive, thermolytic reactions of polybutadienyllithium. The importance of these reactions at temperatures frequently utilized for the polymerization of butadiene was illustrated and the effect of these reactions on the macrostructure of polybutadiene determined.
Thermal conductivity of polymers filled with particulate solids
Authors: Sundstrom Donald W. , Lee Yu‐Der
Published: April 2003

The thermal conductivities of polystyrene and polyethylene containing several different particulate solids were measured over a range of solid concentrations. Experimental data were compared with results predicted by theoretical models for two‐phase media. The equations of Bruggeman and Cheng‐Vachon both gave reasonable agreement with measured results. The applicability of these equations does not appear to depend upon the structure of the polymer.
On the mechanisms for drag reduction: A viscoelastic evaluation based on a bead‐spring model
Authors: Ting R. Y.
Published: April 2003

Two possible drag reduction mechanisms were examined by studying the viscoelastic effects of polymer solutions for the separate cases of oscillatory shear flow and elongational flow. The constitutive equation used was based on a modified dumbbell molecular model which predicts non‐Newtonian viscosity and both the primary and the secondary normal stress differences. It can be shown that when this constitutive equation is arranged in the form of the Oldroyd model, the latter becomes a special case of this more general equation. The present results show that viscoelastic effects on the mean local rate of energy dissipation of a fluid element in an oscillatory motion are negligibly small. However, such effects introduce very large increases in the elongational viscosity as the stretching rate exceeds a certain limiting value and the flow time exceeds the terminal relaxation time of the fluid. The relative merits of these findings as possible explanations of turbulent drag reduction are briefly discussed.
Thermal degradation of polymers. V. Vacuum pyrolysis of poly(p‐N,N‐dimethylaminostyrene). The products volatile at pyrolysis temperature, liquid or gaseous at room temperature
Authors: Still R. H. , Evans M. B. , Whitehead A.
Published: April 2003

The products obtained on degradation of poly(p‐N,N‐dimethylaminostyrene) in vacuo are described. The effects of molecular weight and pyrolysis temperature are discussed and the behavior compared with polystyrene under similar conditions. Product analysis has revealed significant differences between the products of degradation obtained from the two polymers, and mechanisms involving methyl‐group migration have been proposed and discussed to account for the anomalous behavior of poly(p‐N,N‐dimethyl‐aminostyrene). The liquid products of pyrolysis have been separated and identified by gas‐liquid chromatography using the Kovats retention index, and quantitative analysis is also described. Analysis of the gaseous fraction by mass spectrometry is described.
Thermal degradation of polymers. VI. Vacuum pyrolysis of poly(p‐N,N‐dimethylaminostyrene). The residue and the fraction volatile at pyrolysis temperature, involatile at room temperature
Authors: Still R. H. , Whitehead A.
Published: April 2003

The effect of the extent of degradation of poly(p‐N,N‐dimethylaminostyrene) on the quantity and composition of the residue and the effect of pyrolysis temperature on the fraction volatile at pyrolysis temperature are discussed. The behavior of poly(p‐N,N‐dimethylaminostyrene) is compared to that of polystyrene. A significant difference has been found for the behavior of the residue from poly(p‐N,N‐dimethylaminostyrene), which is ascribed to a crosslinking reaction involving the dimethylamino substitutent. Mechanisms to account for the observed products of degradation have been suggested and are discussed.
Prevulcanization inhibitor of sulfur‐free thiuram vulcanization
Authors: Ducháček Vratislav
Published: April 2003

On the basis of Mooney scorch measurements at 120°C and of continuous measurements of vulcanization in a Vuremo curemeter at 145°C, sulfenamides which function as inhibitors of the sulfur‐free thiuram vulcanization have been investigated. It was found that the actual prevulcanization inhibitor is 2‐mercaptobenzothiazole. Its formation from sulfenamides is activated by zinc dimethyldithiocarbamate since the vulcanization of rubber by thiuram disulfides in the presence of zinc oxide is always accompanied by the formation of zinc dithiocarbamate. It seems probable that the inhibition effect of 2‐mercaptobenzothiazole is attributable to the formation of a complex with zinc dimethyldithiocarbamate which decreases the reaction rate in the initial steps of the sulfur‐free thiuram vulcanization and thus causes the scorch delay.
Thermal and hydrolytic degradation of poly(1,4‐cyclohexylenedimethylene terephthalate)
Authors: Wampler F. C. , Gregory D. R.
Published: April 2003

The kinetics of simultaneous thermal and hydrolytic degradation of poly(1,4‐cyclohexylenedimethylene terephthalate) (PCHDT) were evaluated by using a 1.5‐in.‐diam. melt extruder (≈20/1 length/diameter ratio) as a reactor. The effects of extrusion temperature (295°‐330°C), residence time (2.6–17.5 min), and moisture content (<0.001% to 0.2%) of the supply polymer on degradation were determined. The rate of degradation was measured in terms of the rate at which inherent viscosity (I.V.) decreased and the rate at which carboxyl endgroup concentration increased. The contributions of both thermal and hydrolytic degradation to the total degradation of PCHDT could be separated because the hydrolysis was rapid enough that it could be considered as occurring prior to thermal degradation. Thus, the hydrolysis merely adjusted the initial properties of the supply polymer, which was then subjected to thermal degradation. Equations were developed from an analysis of the kinetic data based on a random chain scission mechanism. The activation energies for decrease in I.V. and increase in carboxyl endgroup concentration of PCHDT from thermal degradation were determined as 33.5 and 41 kcal/mole, respectively.
Ductile and brittle behavior of amorphous polymers. Relationship with activation energy for glass transition and mechanical fracture
Authors: Aharoni Shaul M.
Published: April 2003

An equation correlating the activation energy for the glass transition with TR, a characteristic reference temperature, the fractional free volume, and the rate of change of the fractional free volume was developed. The resultant activation energies for about 30 polymers are given and favorably compare with the literature. The relationship between the activation energy and the bond‐rupture energy indicates whether a polymer will fail in a ductile or brittle fashion. More accurate results are shown to be dependent on the stress, the stress concentration, molecular orientation, frequency of load application, and temperature. Equations correlating all these with the activation energies are given. These results are in agreement with the molecular domain model. Experimental observations from the literature seem to corroborate the suggestion that the molecular domain model holds in the amorphous solid, too.
Studies on melt spinning. III. Flow instabilities in melt spinning: Melt fracture and draw resonance
Authors: Han Chang Dae , Lamonte Ronald R. , Shah Yatish T.
Published: April 2003

An experimental study has been carried out to investigate threadline instabilities in melt spinning. Two types of melt threadline instabilities, draw resonance and melt fracture, were observed under both isothermal and nonisothermal spinning conditions. Polymers investigated were polypropylene and polystyrene. Draw resonance was observed as an increase of the take‐up speed above a critical value. It was also observed that an increase in take‐up speed reduces the severity of melt fracture, whereas once draw resonance occurs the amplitude and frequency of the pulsing thread diameter increases with the take‐up speed. The phenomenon of draw resonance was investigated by taking motion pictures of the pulsing molten threadline spun vertically downward. Furthermore, a stability analysis was carried out to explain the experimentally observed draw resonance.
Thermal behavior of graft copolymers of cotton cellulose and acrylate monomers
Authors: Varma D. S. , Narasimhan Veena
Published: April 2003

Cotton cellulose yarn was grafted with methyl acrylate, ethyl acrylate, n‐butyl acrylate, and methyl methacrylate at various percentages of grafting. The effects of concentration of the initiator, concentration of the acid, and of temperature on grafting was studied and the mechanism discussed. The effect of reactivity of the monomer on the percentage graft‐on is pointed out. Thermal behavior of natural and grafted cotton yarn was studied using dynamic thermogravimetry in air at a heating rate of 6°C/min up to a temperature of 500°C. The thermal stabilities of the samples grafted with various acrylate monomers to various percentages of grafting were computed from their primary thermograms by calculating the values of IDT, IPDT, and E*. The results show that the thermal stability increases with increase in graft‐on per cent, and the thermal stabilities of natural cotton and cotton grafted with different monomers are in the order ethyl > methyl > natural cellulose > methyl methacrylate > n‐butyl acrylate.
Fractionation of ethylene–propylene copolymers
Authors: Ogawa Toshio , Tanaka Shoichi , Inaba Tadami
Published: April 2003

Ethylene–propylene (EP) copolymers were fractionated according to chemical composition, molecular weight, or monomer sequence length, which are fundamental distribution factors. Cloud points of polyethylene (PE), polypropylene (PP), and EP copolymer were determined prior to the fractionation. From the results, it was estimated that xylene–butyl cellosolve and tetralin–ethyl carbitol systems were suitable for the fractionations according to chemical composition and molecular weight, respectively. EP random‐type copolymers were fractionated using a xylene–butyl cellosolve system. Separations according to chemical composition were obtained as expected. Then, the above polymer fractions were further fractionated in a tetralin–ethyl carbitol system. and the dependence on molecular weight was observed fairly well. Furthermore, fractionation according to monomer sequence length was satisfactorily achieved by solvent extraction using ethyl ether, n‐hexane, cyclohexane, and n‐heptane. Therefore, it is concluded that the more detailed characterizations of EP copolymers are made possible by a combination of these techniques.
Friction reduction degradation in dilute poly(ethylene oxide) solutions
Authors: Gold P. I. , Amar P. K. , Swaidan B. E.
Published: April 2003

Degradation of friction‐reducing effectiveness of dilute poly(ethylene oxide) solutions subjected to continuous agitation is examined in disk flow. A residual or steady‐state effectiveness is observed which disappears only at a sufficiently high Reynolds number. The onset of friction reduction appears to occur within the transition region and seems to be independent of solution concentration. The onset of degradation also appears to be independent of concentration. Prior shear working is shown to have a significant effect on residual friction‐reducing effectiveness only when the shear working is performed in a more intense shear field than that in which the friction‐reducing effectiveness is evaluated. Degradation of friction‐reducing effectiveness is compared to corresponding changes in viscosity‐average molecular weight. The experimental results are interpreted in terms of a model of the interaction between polymer molecules and the turbulent flow field.
Sorption behavior of mercuric and methylmercuric salts on wool
Authors: Friedman Mendel , Harrison Craig S. , Ward Wilfred H. , Lundgren Harold P.
Published: April 2003

Sorption by wool of mercuric nitrate, mercuric chloride, and methylmercuric chloride was measured by atomic absorption spectroscopy. Both inorganic mercury compounds are efficiently taken up at low concentrations from acid solution. The rate of binding from the nitrate is appreciably slower than from the chloride. Methylmercuric chloride is bound slowly at low pH, rapidly at pH 6. The extent of its binding is roughly 10% to 20% of that of the inorganic salts. The wool‐bound mercury can be recovered by serial extraction with aqueous citrate or ethylenediaminetetraacetate at pH 6. The residual, firmly bound mercury is roughly equivalent to the sulfhydryl sulfur. Sorption of inorganic mercury compounds at low pH roughly follows a Freundlich isotherm in the concentration range 5×10‐6 to 10−1M. Sorption of methylmercurie chloride at pH 6 follows a roughly parallel isotherm in the range 5×10−6 to 10−3M. These data suggest the potential value of wool and other animal keratins to remove and recover mercury from contaminated water. Wool may also serve as an instructive model for mercury binding and release in the body.
Identification of cis‐4,5‐epoxy‐2‐pentenal from pyrolysis of H3PO4‐treated cellulose
Authors: Lam L. K. M. , Fung D. P. C. , Tsuchiya Y. , Sumi K.
Published: April 2003

An important product, C5H6O2, from the pyrolytic decomposition of phosphoric acid, treated cellulose was isolated and identified as cis‐4,5‐epoxy‐2‐pentenal. NMR, IR UV, and mass‐spectral data of this product were analyzed and discussed. A method for the preparation of cis‐4,5‐epoxy‐2‐pentenal is presented, and a mechanism for its formation is proposed.
The drag reduction of chrysotile asbestos dispersions
Authors: Peyser Paul
Published: April 2003

The drag reduction (DR) of dispersions of Chrysotile asbestos fibers in aqueous solutions of Aerosol OT and in ethylene glycol, and of glass microfibers in water at a pH of 3 were studied as a function of concentration and temperature with a rotating disc apparatus. Only the dispersions of asbestos in aqueous Aerosol OT showed DR comparable to poly(ethylene oxide) WSR 35 (∼500,000 MW), and these dispersions were more fully studied. As was the case with Polyox WSR 35, the asbestos dispersions achieved maximum DR at a concentration of about 200 ppm. They showed no DR temperature dependence at constant Reynolds number at high concentrations but displayed a decreasing DR with increasing temperatures at low concentrations. However, the temperature effect was much smaller for the asbestos dispersions than for Polyox. The asbestos dispersions also showed a much smaller decrease of DR with time at a given disc rotation than was previously measured for poly(ethylene oxide). Electron microscope evidence indicated that less than 10% of the fibers were fully separated, and it is probable that these were the fibers which were primarily active in DR. Hence, if complete separation and dispersion could be accomplished without breaking the fibers, Chrysotile asbestos would be a most potent, not very shear‐degradable DR species.
Diffusive and bulk flow transport in polymers
Authors: Yasuda H. , Peterlin A.
Published: April 2003

The transport properties of polymer membranes in various forms which have a wide variety of practical applications, such as ultrafiltration, dialysis and blood oxygenation, depend upon the structure (homogeneous or heterogeneous) and the transport characteristics of the membrane material. Among many possible driving forces of transport, the pressure gradient and the concentration gradient are considered to be the most general forces encountered in practical use of polymer membranes. The transport of various permeants (gas, dissolved gas, liquid solvent, and solute) through porous and homogeneous (nonporous) polymer membranes under these driving forces is discussed. In the absence of a pressure gradient, the transport of permeants can be described as diffusion, regardless of the permeant phase and the membrane structure. In the presence of a pressure gradient, the transport of permeants may occur by diffusion and/or bulk flow of the permeants, depending upon the membrane structure and the nature of the permeant. In homogeneous membranes, many noninteracting permeants such as gases and nonsolvent vapors permeate by diffusion under applied pressure gradient: however, solvent in homogeneously swollen membranes moves by bulk flow and the diffusion depending on the degree of swelling of the membrane. In heterogeneous membranes under applied pressure, most permeants move by bulk flow.
An experimental study of adsorption of polymers on activated carbon: Butadiene—styrene polymers and poly(methyl methacrylate)
Authors: Sadakne George S. , White James L.
Published: April 2003

An experimental study of the extents and rates of adsorption of several polymers from various solvents onto activated carbon has been carried out. The polymers studied included polystyrene, polybutadiene, butadiene–styrene copolymers and poly(methyl methacrylate). The solvents included toluene, cumene, decalin, 2‐pentanone, and methyl ethyl ketone (MEK). Polystyrene is adsorbed from the different solvents in the order MEK, 2‐pentanone, cumene, toluene, decalin. The adsorption from toluene, decalin, and cumene is in the order polystyrene, polybutadiene butadiene—styrene copolymer. The fact that the copolymer is adsorbed less than either homopolymer is striking. The variation of molecular weight distribution with extent of adsorption has been studied. It was found that low molecular weight polymer was preferentially adsorbed in the early stages of the experiment, but high molecular weight polymer was adsorbed at longer times. The apparent adsorption rate constants have been evaluated for the various systems and resolved into external mass transfer, internal (intraparticle) mass transfer, and adsorption rate constants. The experimental data have been applied to the prediction of the elution of the polymers from chromatographic columns packed with activated carbon.
A model for gel drying
Authors: Shah Y. T. , Porter J. H.
Published: April 2003

A theoretical model for drying of a thin gel film is presented. The model is based upon the premise that as solvent is removed from any portion of a gel structure which is permeable by the solvent, the structure shrinks locally to fill the voids left by the solvent. The diffusion coefficient of solvent through the gel film is assumed to be an exponential function of concentration and temperature. The governing equations for the model indicate that for nonisothermal drying, the results of drying and shrinkage rates are functions of 13 independent dimensionless system variables. These results are obtained with the help of a computer solution of the proposed model. The computer results indicate that, except under extreme temperature conditions, the drying and shrinkage rates are most influenced by dimensionless groups M, P, and P̄, defined by eq. (9) of the paper. Furthermore, the drying and shrinkage rates are essentially independent of groups M and P for the values of M and P greater than approximately 100 and 10, respectively. The effect of variable solvent diffusivity on approximate time to achieve the steady‐state drying and shrinkage rates is approximately handled by defining a dimensionless time variable τ in terms of average solvent diffusivity. Finally, some experimental data on drying and shrinkage rates of isothermal drying of lyphogel film under natural convection condition are obtained. These data are found to be in qualitative agreement with similar computer predictions by the proposed model.
Poly(α‐methylstyrene)–poly(dimethylsiloxane) block copolymers
Authors: Noshay Allen , Matzner Markus , Karoly Gabriel , Stampa Guido B.
Published: April 2003

Block copolymers were synthesized by the condensation of dihydroxyl‐terminated poly‐(α‐methylstyrene) oligomers and bisdimethylamino‐terminated poly(dimethylsiloxane) oligomers. Manipulation of block molecular weight produced copolymers ranging in composition from 21% to 73% poly(dimethylsiloxane). Compression moldablity was found to be good. Physical properties were dependent upon siloxane content, varying from high modulus, low elongation to low modulus, high elongation materials. High siloxane‐content compositions exhibited elastomeric properties due to the two‐phase morphology of these systems. Glass transition temperatures were observed as low as −120°C for the poly(dimethylsiloxane) block and as high as + 140°C for the poly(α‐methylstyrene) block. Even higher poly(α‐methylstyrene) transition temperatures may be possible by using higher molecular weight oligomers.
The autoignition of polymers
Authors: Miller Bernard , Martin J. Ronald , Meiser Charles H.
Published: April 2003

A consistent and relatively simple method is presented for studying the unpiloted ignition of polymeric materials in contact with hot air. The ignition behavior of a particular polymer as determined by its bulk properties may be characterized by the relationship between sample mass and ignition time at constant area for a series of furnace temperatures. Extrapolation of this linear relationship at a given furnace temperature to zero mass results in an intrinsic ignition time which represents the rate of the ignition process when the time required to heat the sample to its decomposition temperature has been eliminated, i.e., the sample is brought to its decomposition temperature instantaneously. The temperature dependence of this intrinsic ignition time shows an Arrhenius relationship with an apparent activation energy of 8–10 kcal/mole for all but one material investigated. This indicates that the mechanism controlling the kinetics of such an ignition process is a physical one, most likely the diffusion of combustible gaseous products into the heated air surrounding the sample.
A new fiber‐sampling technique for infrared spectroscopy as applied to nylon 6 and poly(ethylene terephthalate)
Authors: Tirpak G. A. , Sibilia J. P.
Published: April 2003

A number of techniques have been used in the past for obtaining the infrared spectra of fine fibers. A new technique has been developed which overcomes many of the problems of previous methods. The present technique involves winding a single filament between two salt windows which are separated by a spacer which is the same or slightly greater in thickness than the fibers. This results in a layer of adjacent parallel fibers. Good‐quality polarized infrared spectra were obtained on oriented poly(ethylene terephthalate) and oriented nylon 6 fibers with the new technique. The data demonstrate the high level of “A” conformation orientation present in highly drawn nylon 6 fibers and the existance of chain folds in drawn poly(ethylene terephthalate) fibers. The structural changes which occur during the shrinkage of nylon 6 fibers are also demonstrated.
Dynamic loss energy measurement of tire cord adhesion to rubber
Authors: Murayama Takayuki , Lawton Ernest L.
Published: April 2003

The dynamic loss energy measurements for characterizing adhesion using Vibron DDV‐II have been applied to the tire cord–rubber composite system, and the relationships between these dynamic measurements and static adhesion test (H‐block pull test and strip peeling test) were also investigated. Tested samples were the commercial nylon 66 tire cord and poly(ethylene terephthalate) tire cord with two adhesive systems. The degree of adhesion (adhesion factor) was obtained as the energy dissipation at the tire cord‐to‐rubber interface as measured by dynamic testing. It was shown that energy dissipation is increased at the filament–matrix interface when the composite is subjected to continuous cyclic loading if a condition of poor adhesion exists. The test was based upon the separation of the total energy dissipation in a composite under cyclic loading into a portion associated with viscous properties of the constituent materials and a second portion resulting from the lack of perfect bonding in the interfacial regions. The strip peeling measurement of adhesion exhibited an approximately linear correlation with the dynamic loss energy measurement of adhesion. The dynamic energy loss measurement is suggested as a potential source of information on the rheological characteristics of the interfacial region of bonding.
Gas‐filled polymers. I. Void morphology of polyethylene
Authors: Kolbeck A. G. , Uhlmann D. R. , Calvert P. D.
Published: April 2003

Morphologic studies of gas‐filled polyethylene show a characteristic void structure, with an interior region containing distinct gas bubbles surrounded by a surface layer of void‐free polymer. The voids in the bubbled region frequently show an elongated shape with the long dimension oriented parallel to the surface of the specimens. The gas–polymer interface within individual voids is composed of fibrils of the polymer extending into the interior of the void. Studies of the annealing temperatures required to obtain gas bubbles in the material and of the melting range of the ungasified polymer indicate that melting of the crystalline component of polyethylene is required for void formation.
Stress–strain optical study of styrene–butadiene and ethylene–propylene rubbery copolymers
Authors: Durisin J. , Williams H. Leverne
Published: April 2003

Birefringence–temperature behavior at constant stress during cooling and heating of styrene–butadiene and ethylene–propylene copolymers between −120°C and +60°C was investigated. Copolymer composition, thermal treatment, and stress levels were shown to have a pronounced effect on the photoelastic properties.
Effect of recrystallization on the solubility of poly(vinylidene chloride)
Authors: Wessling R. A. , Carter D. R. , Ahr D. L.
Published: April 2003

A study of the crystallization of poly(vinylidene chloride) from dilute solution in various solvents was carried out. The temperature at which the polymer dissolved was dependent on crystallization history. The minimum solution temperature obtained by recrystallization at high undercooling and redissolving is the preferred parameter for characterizing solvents for poly(vinylidene chloride).
Sur la dégradation thermique du polychlorure de vinyle. VI. Etapes initiales—etude générale préliminaire
Authors: Guyot A. , Bert M.
Published: April 2003

A differential conductimetric apparatus allowing the continuous titration of HCl carried by a stream of gas with a limit sensitivity of 40 nanograms is described and applied to study the initial steps of poly(vinyl chloride) thermal degradation. The powdered sample is placed in a quartz cell which may be closed and detached and placed at a chosen time interval in a reflexion diffuse UV spectrometer. The dehydrochlorination process begins just above Tg; the isotherms under argon show, after a variable time, a steady state with a zero order and an activation energy of 22 kcal. For a dehydrochlorination ratio (DR) less than 1000 ppm, the shape of the UV visible spectrum does not depend on the DR, and for the same DR it does not depend on the degradation temperature. A plot of the reflectance ratio versus the DR shows a coloration process in two steps: a rapid step followed by a slower step. The phenomenon, which does not depend on the physical state of the sample, tends to disappear if the amount of polymer is lowered and if the rate of flow of the gas is increased. It suggests that the HCl formed upon the dehydrochlorination process remains partly dissolved in the polymer. Further proof of the dissolution of HCl in the polymer is given, and a through method of titration is proposed. It is suggested that the initial steps of the dehydrochlorination follows an ionic mechanism, and might be partially reversible and diffusion controlled, although the autocatalysis which involves a rather high dehydrochlorination ratio and the presence of a large amount of dissolved HCl might initiate the radical process.
Modification of cellulose acetate reverse osmosis membranes by radiation grafting
Authors: Bentvelzen J. M. , Kimura‐Yeh F. , Hopfenberg H. B. , Stannett V.
Published: April 2003

Large excesses of a chain transfer agent, carbon tetrachloride, were introduced to a recipe for the mutual radiation grafting of styrene to cellulose acetate film. The effect of the carbon tetrachloride on the molecular characteristics as well as the reverse osmosis and time dependent mechanical properties of resulting graft copolymers was determined. Extremely short side chains were generated as a consequence of the high concentrations of chain transfer agent and the composite results further suggest that the morphology of the grafted films is best described as “destructured” or internally plasticized consequent to grafting in the presence of CCl4. Reverse osmosis fluxes increased with percent graft; salt rejection was high and unaffected by per cent graft up to 40% graft; and the tensile creep under wet conditions was significantly retarded by the grafting. These effects were shown to accrue from grafting per se by control experiments involving α‐methylstyrene which will not propagate to form a polymer under these conditions. These results are compared and contrasted with earlier work on grafting in the absence of CCl4 where long side chains of polystyrene were generated resulting in a structuring of the polymer involving domains of polystyrene‐rich material and domains of cellulose acetate rich polymer.
Effect of the continuous medium on the color of discontinuous substrates. IV. The effect of the refractive index of the continuous medium
Authors: Allen E. Hope , Faulkner D. L. , Goldfinger G. , McGregor R.
Published: April 2003

It is known from experience that light scattering–absorbing substrates are darker when the continuous medium is water instead of air. This is due to the decrease in scattering efficiency of the scattering particles caused by the smaller value of the ratio n1/n2 of the refractive indices of the scattering particles (n1 = 1.5 to 1.7) to that of water (n2 = 1.33) as compared to that ratio when the continuous medium is air (n2 = 1). Experimental evidence for this phenomenon is presented for polyester fabric viewed in air, water, and a concentrated sucrose solution. The wavelength range from 0.4 to 0.7 microns, and absolute “dry” reflectances from 0.02 to 0.7 were covered. The phenomenon cannot be adequately described with the Kubelka‐Munk theory of the color of scattering–absorbing substrates.1 Evidence is presented that at high reflectance values (0.4–0.7), the theory describes the color adequately and the results are consistent with a prediction based on a modified Mie equation for the scattering efficiency of “large” particles.2,3 At low reflectance values (<0.05), the Kubelka‐Munk theory breaks down completely. This is consistent with the observation that this theory is not capable of predicting precisely high dye concentrations on textiles but is quite adequate for low concentrations.
The effect of methods of drying on the fine structure, density, and some mechanical properties of jute and allied fibers
Authors: Ray P. K.
Published: April 2003

The degree of crystallinity and crystallite orientation in jute, mesta, and roselle fibers have been studied by x‐ray diffraction. Removal of water, indirectly, has been carried out by alternate immersion in methanol and benzene. It has been found that an increase in crystallinity and a decrease in crystallite orientation take place in these fibers as a result of direct drying, presumably because of the formation of an increased number of hydrogen bonds associated with direct drying. Density, tenacity, and rigidity of the fiber in the two drying conditions are in agreement with the x‐ray results.
The role of diffusion in the Ziegler polymerization of ethylene
Authors: Crabtree J. R. , Grimsby F. N. , Nummelin A. J. , Sketchley J. M.
Published: April 2003

A theoretical and experimental study has been made of the polymerization of ethylene in a slurry reactor using a highly active Ziegler catalyst in the presence of hydrogen. A model of the polymerization system has been set up in which polymerization is assumed to proceed with encapsulation of catalyst subparticles. Allowance is made for an experimentally observed first‐order decay in intrinsic catalyst activity. The theoretical prediction of the model for the monomer absorption rate behavior and the molecular weight characteristics of the polymers formed are in agreement with experimental findings. Experimental evidence is presented that in the earliest moments of a polymerization significant amounts of polymer are formed with molecular weights 100 times those in the balance of the polymerization. It is concluded that in this system the polymerization is diffusion controlled throughout the major part of the catalyst lifetime. This diffusion phenomenon, together with the gradual loss of active sites, is of vital importance in determining the molecular weight and molecular weight distribution of the polyethylene product.
Some aspects of monuron‐accelerated dicyandiamide cure of epoxy resins
Authors: Son Pyong‐Nae , Weber Carl D.
Published: April 2003

The synergistic effect of dicyandiamide and certain trisubstituted ureas in the curing of epoxy resin is shown by differential scanning calorimetry and exotherm profiles. When 3‐(p‐chlorophenyl)‐1,1‐dimethylurea (Monuron) was reacted with dicyandiamide, we could isolate dimethylamine and a derivative of dicyandiamide. The role of these products in epoxy resin curing is speculated.
Adhesion of polymers to shale rock surfaces
Authors: Raff R. A. V. , Haugen J. A. , Mostafa M. F.
Published: April 2003

In the course of a project on the application of polymers for rock bonding and reinforcement of coal mine structures, the adhesion of epoxy resins to shale mine rock was studied by infrared and Mössbauer spectroscopy. Two types of bonding were identified: primary bonds between silicates and polymer, and hydrogen bonds from organic compounds on the surface of the shale to oxygen in the polymer. These bonds contribute to the adhesive strength when epoxy resins are used to bind shale. The bonding model, when applied to furfuryl alcohol and polyester resins, predicts inferior binding in the shale system.
In situ formation and incorporation of additives into polymers during interfacial polycondensation reactions
Authors: Raff R. A. V. , Sorathia U. A. K.
Published: April 2003

One of the objectives of the work was to attempt the in situ formation of inorganic fillers during interfacial polycondensation reactions. The complementary components of the filler were added separately to the organic and aqueous phases of the system so that they formed the insoluble filler at the interface simultaneously with the polymer. Since the polyamide plastics have good molding properties, nylon 610 was selected as the principal model, but some work was also carried out with a urethane polymer. Further, coloring of nylon 610 and of a polyurethane resin was investigated by lake formation at the interface with the help of 1,2‐dihydroxyanthraquinone in the organic phase and a metal salt in the aqueous phase. In this way, red‐ and blue‐colored polymers were prepared. Finally, by adding zinc ions to the aqueous and pentachlorophenol to the organic phase, zinc pentachlorophenate was incorporated into nylon 610 during its formation. The ignition point of the resultant product was significantly higher than that of a sample to which zinc pentachlorophenate had been added by mechanical mixing.
Analysis of tanks‐in‐series model with backflow for free‐radical polymerization
Authors: Shastry J. S. , Fan L. T. , Erickson L. E.
Published: April 2003

Free‐radical polymerization in a flow reactor represented by the tanks‐in‐series model with backflow was considered. Conversions and molecular weight distributions were computed as functions of the backflow parameter, and the results were compared with the conversion and molecular weight distribution from a CSTR and those from a plug‐flow reactor. Backflow was found to be undesirable for the polymerization mechanism under investigation. Values of the degree of segregation for the tanks‐in‐series model were calculated by using Zwietering's approach as a function of backflow.
Flow properties of polystyrene solutions under high shear rates
Authors: Abdel‐Alim A. H. , Balke S. T. , Hamielec A. E.
Published: April 2003

This manuscript reports on the development of a high‐shear Couette viscometer. The main design considerations for a high‐shear concentric cylinder viscometer are reviewed and discussed. In principle, the instrument is identical to those used by other investigators. However, some modifications were found necessary. Attention is drawn to the importance of the concentricity problem. The instrument was first tested and calibrated using Newtonian standard oils. Then non‐Newtonian runs were performed using narrow polystyrene standards of molecular weights 97,200, 411,000, and 860,000. Solutions of the polymer in n‐butylbenzene ranged in concentration from 0.08 g/cc up to 0.5 g/cc. The shear rates applied ranged from 103 sec−1 up to 105 sec−1. The results obtained were compared to the molecular entanglement theory, and excellent agreement was observed.
A new apparatus for continuously monitoring the deformation of a thermoplastic material
Authors: Martinelli F. J. , Hodgkin J. H.
Published: April 2003

A new apparatus is described whereby the thermal behavior, including the deformation temperature, of a thermoplastic material may be obtained. The apparatus is intended to replace ASTM procedure No. D648‐56 and has several advantages over that procedure. Thermal behavior of several common thermoplastics under two different stresses and for three different heating rates is described. An application to the determination of optimum cure times for certain thermosetting epoxides is also described.
Intrinsic viscosity calculated by computer
Authors: Hofreiter B. T. , Ernst J. O. , Williams W. L.
Published: April 2003

A computer program has been devised for routine use which processes raw data such as polymer sample weight, moisture content, solution volume, and viscometer flow times to calculate a least‐squares‐derived intrinsic viscosity. In addition to eliminating errors inherent in graphic solutions and freeing technicians from tedious calculation, the computer output provides the 95% confidence interval of the intrinsic viscosity.
Strain rate dependence of failure processes in polycarbonate and nylon
Authors: Arad S. , Radon J. C. , Culver L. E.
Published: April 2003

A study has been made of two types of failure, namely, monotonic fractures using Charpy‐type specimens and fatigue crack propagation using rectangular plates containing an initial central notch. The work was conducted on an amorphous polymer (polycarbonate) and a semicrystalline polymer (nylon N 6.6). Monotonic tests were performed in an Instron testing machine between 0.002 and 20 in./min, and in a Charpy testing machine between 2000 and 11800 in./min. The cyclic tests (under constantKconditions) were carried out at frequencies that ranged from 0.1 to 20 Hz. A model for the relationship between the cyclic rate of crack growth and appropriate LEFM parameters, previously described, has now been converted into cyclic strain energy transformations. In computing the strain energy, the value of the time‐dependent modulus of the material was used; and under cyclic loading conditions the glassy (short time) value was employed. The authors have proposed that the modulus measurements obtained at very low temperatures, where the viscous response of the material is highly restricted, will approximate the glassy value,Eg, found by conducting relaxation measurement tests at different temperatures down to −197°C. Within the range of tests conducted, the fracture toughness values of both PC and N 6.6 apparently decrease with increase in loading rate. Fatigue crack growth in both materials is influenced by loading frequency and cyclic waveform. These variations may be related to the magnitude of the viscous energy loss and hence to the available energy for crack extension per cycle.
Polymerization in an electrodeless glow discharge. III. Organic compounds without olefinic doublebond
Authors: Yasuda H. , Lamaze C. E.
Published: April 2003

The rates of polymer deposition from various organic compounds which do not contain an olefinic doublebond in an electrodeless glow discharge were studied. The polymerization rates of these unconventional monomers are by and large similar to those of olefinic monomers reported in the previous study (part II). The rate of polymer deposition R0 from pure monomer flow can be characterized, according to the analysis used in part II, by Ro = apM2 and R0 = kFw, where pM is the vapor pressure of the monomer, Fw is the weight basis flow rate of the monomer. Type A monomers which predominantly polymerize and type B monomers which decompose in a glow discharge were also found with these unconventional monomers. The effects of structural factors on the values of a amd k and on the classification of types A and B were examined. These structures and groups—aromatic, heteroaromatic, nitrogen‐containing (e.g., >NH,NH2,CN), Si‐containing, and olefinic doublebond—favor the polymerization. These structures and groups—oxygen‐containing chlorine, aliphatic hydrocarbon chains, and cyclic hydrocarbon chains—favor the decomposition of the monomer in a glow discharge. It is postulated that the polymerization of organic compounds proceed by the recombination of excited species (probably free radicals) created by glow discharge and reexcitation followed by further recombinations in the vapor phase and at the interface.