bluuebunny/crossref_metadata_2025 huggingface dataset:
The drag reduction of dilute polymer solutions as a function of solvent power, viscosity, and temperature
Authors: Peyser Paul , Little R. C.
Published: April 2003

The frictional drag reduction of high molecular weight poly(ethylene oxide) and polystyrene solutions under turbulent flow conditions has been studied as a function of temperature, solvent power, and solvent viscosity. A rotating‐disc apparatus was used to make the drag reduction measurements. For aqueous poly(ethylene oxide) solutions, at concentrations well above that needed to produce maximum drag reduction, all drag reduction data reduced to a common curve when per cent drag reduction was plotted against the Reynolds number for the flow. However, for poly(ethylene oxide) solutions below this optimum concentration, the drag reduction‐versus‐Reynolds number curves showed decreasing drag reduction with increasing temperature. The data are explained primarily in terms of the inverse temperature solubility characteristics of poly(ethylene oxide) in water. The per cent drag reduction of polystyrene in nonaqueous liquids was found to be greater in good solvents than in poor ones. It was also found that increases in solvent viscosity and decreases in temperature increased the per cent drag reduction. The results are discussed in relation to the current drag reduction theories and are shown to be in opposition to Virk's theory. It is concluded from the data that drag reduction is very likely a function of a relaxation time phenomenon involving the polymer molecules and the flow system. The results also emphasize the importance of considering solvent power, viscosity, and temperature in the design of an efficient drag reduction system.
New method for MWD determination in branched polymers
Authors: Ram Arie , Miltz Joseph
Published: April 2003

GPC data for long‐chain branched polymers (low‐density polyethylene) are interpreted with the aid of a polynomial expression for intrinsic viscosity in terms of the molecular weight. The resulting molecular weight distribution curves agree well with those derived in an earlier work based on certain assumptions regarding the degree of long‐chain branching.
Heat‐resistant polymers containing the low molecular weight closo‐carboranes. III. The preparation of polycarboranesiloxane polymers by alcoholysis
Authors: Kesting R. E. , Jackson K. F. , Newman J. M.
Published: April 2003

A new synthesis for carboranesiloxane polymers has been discovered. It involves the alcoholysis of the bischlorodimethylsilylcarborane monomers and the generation of the HCl catalyst in situ. Alcoholysis is applicable to the synthesis of most carborane‐siloxane polymers, with the probable exception of the SiB‐1 homopolymers of the larger carboranes. The attack of the BH moieties in the carborane cage can be minimized both by the utilization of a tertiary alcohol and by the addition of excess acid when a primary alcohol is employed.
Influence of starch granule swelling on graft copolymer composition. A comparison of monomers
Authors: Fanta George F. , Burr Robert C. , Doane W. M. , Russell C. R.
Published: April 2003

Seven monomers, which varied widely in water solubility and ionic charge, were graft polymerized onto both unswollen starch and starch that had been swollen by heating in water to 60°C. Polymerizations were initiated with ferrous ammonium sulfate hexahydrate–hydrogen peroxide and, where applicable, with ceric ammonium nitrate. Graft copolymers were freed of ungrafted homopolymer by solvent extraction and were characterized by weight percentage of synthetic polymer incorporated in the graft copolymer, molecular weight of grafted branches, and grafting frequency. The influence of starch granule swelling on graft copolymer structure varied with the monomer used and could not be predicted on the basis of water solubility of monomer or its resulting polymer. With acrylonitrile and acrylamide, swollen starch gave higher molecular weight and less frequent grafts than unswollen starch. However, methyl methacrylate, N,N‐dimethylaminoethyl methacrylate · HNO3, N‐t‐butylaminoethyl methacrylate. HNO3, and 2‐hydroxy‐3‐methacryloyloxypropyltrimethylammonium chloride produced less frequent graft of higher molecular weight when starch was unswollen. With acrylic acid, graft molecular weight was independent of starch granule swelling, although grafting was less frequent when swollen starch was used.
Glass transition phenomenon in vinylidene chloride–acrylonitrile copolymers
Authors: Kryszewski M. , Mucha M.
Published: April 2003

Investigations of glass transition phenomena were carried out on vinylidene chloride—acrylonitrile copolymers, purified commercial samples of known composition. With a view to analyzing this effect, the following physical parameters were investigated: specific volume Vs,25, Tg, and volume expansion coefficients αL, αg, and Δα. The experimental results were analyzed on the basis of semiempirical and theoretical equations describing transitions to the glassy state. It was found that Tg dependence on weight fraction C2 of acrylonitrile may be described by Wood's equation, with k = 5.88. Applying Gibb's and Kanig's theories as well as relations given by Hirai and Small, the energies associated with intermolecular interactions (A*AB, E0, Eh, CED), and intramolecular interactions (stiffness energy ε) were calculated for copolymers of different composition. The copolymer Tg was found, above all, to depend on the stiffness energy ε, which increases with increasing acrylonitrile content in the copolymer.
Grafting of wool with vinyl monomers by using trichloroacetic acid–bis(acetonylacetonato)‐copper(II) cocatalyst
Authors: Hebeish A. , Bendak A. , Kantouch A.
Published: April 2003

Graft copolymerization of wool with methyl methacrylate (MMA) and acrylonitrile (AN) was effected under the catalytic influence of trichloroacetic acid (TCA) together with bis(acetonylacetonato)copper(II). Investigation of the action of the cocatalyst on wool in the absence of monomer revealed that the treated wool is completely soluble in dilute alkali. The effect of storage on the catalyzed wool was also studied. Increasing the period of storage, before adding the monomer, causes a significant decrease in the graft yields, indicating vitiation of some of the free radicals on the wool backbone. Based on these studies, a mechanism for the grafting reaction was proposed. Moreover, grafting of wool modified through its disulfide bonds and amino and hydroxyl groups suggests that the thiol, hydroxyl, and amino groups participate in the grafting reaction as sites for graft attachment. Wool—graft copolymers show excellent antifelt properties, particularly at higher levels of grafting.
Solutions of drag‐reducing polymers—diameter effect and rheological properties
Authors: Elliott J. H. , Stow F. S.
Published: April 2003

Solutions (0.5% by weight) of two high molecular weight drag‐reducing polymers, a polyethylene oxide and an acrylamide copolymer having anionic functionality, were prepared under low and high shear conditions. Rheological measurements demonstrated that high shear preparation causes a decrease in the size of the polymer units, the effect being markedly greater for the polyethylene oxide.

These solutions were diluted to 25 ppm and drag reduction measured in 0.047‐in. and 0.93‐in. diameter test sections. The method of solution preparation showed no significant effect in the small tube measurements. In the large tube, however, low shear solution preparation led to drag reductions comparable to those found in the small tube, while high shear preparation gave markedly lower drag reductions. These results are discussed in terms of polymer supermolecular structure.
Morphology of fabric finishes consisting of acrylic soil release polymers and durable press reagents
Authors: Warburton C. E. , Schindler A. T.
Published: April 2003

When acrylic emulsion copolymers containing a substantial proportion of methacrylic acid are mixed with durable press reagents such as dimethyloldihydroxyethyleneurea (DMDHEU) or dimethylolethyleneurea (DMEU) and applied to fabric in a one‐bath application, there is minimal coalescence of polymer dispersion particles. Polymer is embedded in a matrix of condensed methylol reagent which limits swelling of the polymer, in some cases to such an extent that its usefulness as a soil release agent is impaired. The degree of restricted swelling depends upon the soil release polymer and durable press reagents used. Nevertheless, in cases where swelling is severely restricted, excellent soil release is obtained if the matrix is removed sufficiently rapidly in washing. This is more so the case with DMEU than DMDHEU. Some polymer is insolubilized by zinc nitrate used to accelerate reaction of durable press reagent with cotton. Conclusions are based upon electron‐microscopic examination of film surfaces of durable press and soil release finishing agents as well as of surfaces of treated fabrics. Further conclusions are drawn from quantitative determination of film solubilities and chemical analysis of insoluble film residues.
Changes in mixing states of styrene–butadiene copolymer rubber and general‐purpose polystyrene resin mill blend by heat treatment
Authors: Satake K. , Shinki K. , Teraoka T. , Ibe S.
Published: April 2003

The effect of heat treatment in the so‐called phase inversion region was studied using uncured mill blends of various commercial styrene—butadiene copolymer rubbers (styrene content, 23.5 to 48 wt‐%; styrene block, 0 to 18 wt‐%) with general‐purpose polystyrene resin (blend ratio, 80–40: 20–60, in wt‐%). It was found that the effect of heat treatment on the hardening or softening phenomenon of blends is different in the random type from that in the block‐type styrene—butadiene copolymer rubber. A thorough discussion led us to conclude that this difference is caused by the strong interaction between the polystyrene block of the copolymer and the styrene homopolymer of general‐purpose polystyrene resin.
The rheology of filled polymers
Authors: Mills N. J.
Published: April 2003

The flow properties of polymer melts containing fillers of various shapes and sizes have been examined. If there is no failure of either the filler or polymer in the solid state, then the modulus enhancement for randomly distributed filler is equal to the melt viscosity enhancement under medium shear stress conditions (104 Nm−2) in simple shear flow or in oscillatory shear flow. Submicron‐size fillers, in particular, can form weak structures in the melt that greatly increase the low shear rate viscosity without changing the modulus of the solid proportionately. The highly pseudo‐plastic nature of polymer melts at shear stresses of 106 Nm−2 means that, even without orientation of filler particles toward the flow direction, the viscosity enhancement is less than at lower shear stresses.
Softening phenomenon by remilling of styrene–butadiene copolymer rubber–general‐purpose polystyrene resin blend
Authors: Satake K. , Shinki K. , Teraoka T. , Ibe S.
Published: April 2003

The softening phenomenon by remilling of uncured blends of various commercia styrene—butadiene copolymer rubber (styrene content, 23.5 to 48 wt‐%, styrene block 0 to 18 wt‐%) with general‐purpose polystyrene resin was mainly studied by examining the blend ratio dependence of hardness and compression modulus (in logarithmic form), with special attention to the state of dispersion of the polymers. It was found that the blend of styrene—butadiene copolymer rubber with general‐purpose polystyrene resin forms a microheterogeneous polymer blend system and that the hardness and the compression modulus change in S‐shaped curves versus blend ratio. However, the degree of softening phenomenon by remilling (roll surface temperature, 70°–90°C) was found to be different for the two blend systems, i.e., random styrene—butadiene copolymer rubber and block styrene—butadiene copolymer rubber. The softening phenomenon is more pronounced in random‐type rubbers; and in some block‐type rubbers, no softening phenomenon was observed. The influence of the styrene content of the polymer is small. Further discussions have shown us that the strong interaction between the polystyrene block of the copolymer and the styrene homopolymer of the general‐purpose polystyrene resin controls the state of dispersion of polymers thereby causing this difference in the softening phenomena among the different kinds of styrene—butadiene copolymer rubbers.
The effects of reaction temperature and hydrolysis on polyamic acids and polyimides
Authors: Johnson E. L.
Published: April 2003

For some time, polyimides have enjoyed a significant degree of superiority over the other classes of thermo‐oxidatively stable polymers. This superiority is, however, offset by the tremendous difficulty associated with the processing of polyimides. In an effort to understand these difficulties and their causes, several experiments were performed which reflect the roles that reaction temperature and hydrolysis (caused by the presence of water) play during amidization and imidization. Temperatures between 0° and 120°C were found to result in progressively lower‐viscosity polyamic acids whose equivalent weights varied only slightly with increasing reaction temperatures. The presence of hydroxide ions from water were shown to cause degradation of the polymer, and the combination of temperatures above 120°C and hydroxide ions results in the rapid degradation of the polymer and lower molecular weight polyimides.
Permeabilities of coagulated cellulose acetate dialysis membranes
Authors: Yasuda H. , Ikenberry L. D.
Published: April 2003

The diffusive flux of NaCl and the hydraulic flux of pure water through coagulated cellulose acetate membranes are examined. Coagulated cellulose acetate membranes (without densification by heat treatment or drying) possess higher permeability than what may be expected from the permeabilities of the dry polymer. Their overall hydraulic permeability (ultrafiltration rate of water) is greatly dependent upon the membrane casting conditions and the resulting asymmetry of the membrane. On the other hand, the asymmetry of a membrane does not play as great a role in the diffusive permeability of a solute. With homogeneous membranes, higher diffusive flux is always accompanied by higher hydraulic permeability. With asymmetric membranes, this is not always true. The diffusive permeability of NaCl and the hydraulic permeability of water through coagulated cellulose acetate membranes can be controlled nearly independently. Consequently, high diffusive (NaCl) permeability with low hydraulic water permeability and vice versa can be obtained by varying the casting conditions and also by partially saponifying the denser portion of the membrane.
Measurement of molecular weight of poly(vinyl chloride)
Authors: Rudin Alfred , Benschop‐Hendrychova Ivana
Published: April 2003

Molecular weights of six bulk‐process and five suspension‐process PVC samples have been measured as part of a study aimed at developing a technique for gel permeation‐chromatographic analysis of this polymer in tetrahydrofuran at room temperature. Osmometric M̄n values measured in cyclohexanone appear to be valid; the results are insensitive to thermal history or ultrasonic irradiation of the solution. Corresponding measurements in tetrahydrofuran changed with measurement temperature and indicated the presence of stable supermolecular PVC aggregates in this solvent. Such aggregates can be dispersed by ultrasonic treatment of the solution for brief periods. Simultaneous degradation of PVC molecules appears to be prevented by addition of small concentrations of nonionic surfactant to the tetrahydrofuran solutions. Treated solutions are suitable for GPC analyses at ambient temperatures. The results of osmometry, light scattering, and GPC agreed well.
Barrier coatings on cellulose fiber mat
Authors: Liepins R. , Yasuda H.
Published: April 2003

Two techniques were used in the deposition of thin, pinhole‐free vapor barriers upon a Kraft fiber mat without affecting its combustibility properties. One technique involved a collodion spray precoating followed by low pressure styrene plasma coating, and the other involved a collodion spray coating. In the formation of the above coatings, two functional steps are essential: (1) surface pore covering, and (2) nonporous barrier formation.
Degradation of drag‐reducing polymers
Authors: Fisher Dennis H. , Rodriguez Ferdinand
Published: April 2003

A simple, fixed‐head flow device was used to characterize drag reduction by polymers in water. Using a parallel flow of water as a reference system, the Reynolds numbers ranged from 8600 to 12,000. The degradation of poly(ethylene oxide) and polyacrylamide during turbulent flow of dilute solutions (1 to 50 g/kl) was measured in terms of friction‐reducing effectiveness. Poly(ethylene oxide) decreases in effectiveness more rapidly than polyacrylamide in a recycling test.
The availability of hydroxyl groups in native and mercerized cotton celluloses
Authors: Bose J. L. , Roberts E. J. , Rowland S. P.
Published: April 2003

The accessibilities of the hydroxyl groups of the D‐glucopyranosyl units of slack mercerized grey yarn and of the same yarn restretched to its original length are compared with those of the original grey yarn, a purified printcloth, and a hydrocellulose. The study involved reactions of the celluloses with N,N‐diethylaziridinium chloride under conditions which ensure minimum conversion of the reagent by hydrolysis to 2‐hydroxyethyldiethylamine. Amylose was taken as a reference material in which the hydroxyl groups are assumed to be completely accessible. Selective accessibilities of the hydroxyl groups at C‐6 and C‐3 relative to those at C‐2 were determined with the same reagent by a method whose development has been described earlier. The results of this study are expressed as fractions of the hydroxyl groups at C‐2, C‐3, and C‐6 that are accessible to the reagent.
Hydrolyzed starch–polyacrylonitrile graft copolymers: Effect of structure on properties
Authors: Weaver M. O. , Gugliemelli L. A. , Doane W. M. , Russell C. R.
Published: April 2003

Three starch–polyacrylonitrile (S–PAN) graft copolymers containing ratios of S:PAN of 1:1.90, 1:1.16, and 1:0.64 were prepared by graft polymerization of acrylonitrile onto gelatinized starch. A fourth graft, made from granular starch, had an S:PAN ratio of 1:2.16. These grafts were hydrolyzed in potassium hydroxide under various conditions to give a series of products with varying amounts of carboxylic acid and amide groups. Maximum conversion of nitrile to carboxyl was 65%. Aqueous dispersions of the hydrolyzed S–PAN's at pH 7–8.5 were viscous, and, in general, their viscosities reflected the amount of PAN add‐on, with the highest add‐on giving the highest viscosity. Plots of the η/C versus C show that hydrolyzed S–PAN's from gelatinized starch behave as normal polyelectrolytes on dilution to low concentration but that S–PAN from granular starch does not.
Ultrasonic degradation of the gel phase in impact polystyrenes
Authors: Wagner Eric R. , Cotter Robert J.
Published: April 2003

The rupture of the crosslinked rubber membranes in the gel particles of impact polystyrene by ultrasonic energy has been discovered to be a novel route for the semiquantitative analysis of the grafted and occluded polystyrene of the composite. Applying this new technique, the weight‐average molecular weight of the matrix, grafted, and occluded polystyrene of a bulk‐polymerized impact polystyrene was found to be approximately the same.
Cationic copolymerization of 1,3‐dioxolanes and 1,3‐dioxanes with 3,4‐dihydro‐2H‐pyran‐2‐methyl(3,4‐dihydro‐2H‐pyran‐2‐carboxylate). Nonfriable pyranyl foams
Authors: Papa Anthony J. , Proops William R.
Published: April 2003

Various substituted difunctional 1,3‐dioxolanes and 1,3‐dioxanes were copolymerized with a cyclic vinyl ether, 3,4‐dihydro‐2H‐pyran‐2‐methyl(3,4‐dihydro‐2H‐pyran‐2‐carboxylate), in the presence of boron trifluoride etherate catalyst. The copolymerizations proceeded rapidly and exothermally when initiated at room temperature and produced thermosetting resins. The copolymer products possess improved abrasion resistance and toughness as compared with homopolymer of the di(dihydropyranyl) monomer. As a practical consequence of these copolymerizations it is possible to prepare low‐density pyranyl rigid foams with improved friability resistance.
Tensile deformation of nylon 66 fibers at −196°C
Authors: Daniels B. K.
Published: April 2003

Nylon fibers tested in tension at −196°C show ductile strains up to 75%. The ductility is a complicated function of draw ratio, because decreasing work hardening with decreasing draw ratio leads to a point of instability where necking begins. The necks presumably initiate fracture, have the appearnce of cracks, and have been previously seen on fibers drawn in various organic liquids. Recovery experiments showed that molecular motions involved in low temperature deformation differ from those involved in ambient temperature deformation.
The effect of added salt on the flow of highly dilute solutions of poly(ethylene oxide) polymers
Authors: Little R. C.
Published: April 2003

Early transition, early turbulence, and drag reduction were detected in flowing solutions of high molecular weight poly(ethylene oxide) condensates. Progressive addition of salt (magnesium sulfate) increased the onset point characterizing deviations from Newtonian flow for 1 ppm Polyox Coagulant solutions and eliminated early transition in the 10 ppm WSR‐35 solutions. No further drag reduction was observed when the salt molarity reached the 0.65 level. In the Coagulant solutions the onset wall shear stress characterizing the flow deviation was an inverse function of the intrinsic viscosity of the polymer in the salt solution.
Vapor and gas permeability of asymmetric membranes
Authors: Peterlin A.
Published: April 2003

The membrane with continuously varying and pressure‐dependent local permeability P may show a dependence of transport property for gases and vapors on the direction of flow. Such an asymmetry occurs only if the deviation of local permeability from ideality varies from layer to layer. In mathematical formulation, this means that the local permeability is an irreducible function of location and pressure, i.e., not a product of a function of location and a function of pressure. The membrane permeability is higher if the side with greater deviation from ideal, i.e., constant permeability, is exposed to the higher pressure. For two simple cases the currents in both directions and their ratio at constant pressure difference were calculated. It turns out that the asymmetry of permeability increases with increasing deviation from ideality up to a maximum, after which the membrane tends to return to symmetry. An additional result of this investigation is the conclusion that Fick's law, i.e., the proportionality of the diffusion current to the negative concentration gradient is inapplicable not only to inhomogeneous membranes but also to homogeneous not ideal membranes.
NMR study of water adsorbed on methyl methacrylate‐grafted cellulose
Authors: Ogiwara Yoshitaka , Kubota Hitoshi
Published: April 2003

Graft cellulose samples were prepared by three different initiation methods, and the widths of the NMR absorption spectra of samples were measured at various water contents. Samples prepared by both hydrogen peroxide and adsorbed ceric ion methods exhibited maximum widths of NMR absorption spectra at about 10% grafting, whereas the corresponding values for the sample prepared by the conventional ceric ion method were about 30%. Even a minimum value was found on the sample prepared by the latter method. The reason for such different water‐binding behaviors of samples is discussed from the viewpoint of difference in the composition of graft celluloses.
The graft copolymerization of styrene and lignin. II. Kraft softwood lignin
Authors: Phillips R. B. , Brown W. , Stannett V. T.
Published: April 2003

The radiation‐induced graft copolymerization of styrene and various kraft softwood lignins was studied. Expression of the results as the usual “per cent graft” was impossible, because grafting caused the lignin to become extractable in solvents for the styrene homopolymer. However, evaluation of the effects of various solvents on the degree of reaction was made through an indirect, and possibly more characteristic, measure. Grafting was least pronounced under conditions of low lignin accessibility (e.g., when less than 10% methanol was present), but increased with the addition of better lignin solvents or with higher methanol concentrations. The precipitating nature of the latter conditions was also found to contribute to an accelerated rate of grafting. Surprisingly, the graft copolymer was found to degrade at higher doses. Proof of grafting is offered in a fractionation scheme. Measurement of the molecular weight of the polystyrene separated from the lignin backbone allows the estimation of approximately one polystyrene graft per lignin molecule in benzene‐extractable copolymers. Two glass transition temperatures could be detected in several fractionated copolymers.
Mechanical and relaxation properties of polystyrene molded at high pressures
Authors: Dale W. C. , Rogers C. E.
Published: April 2003

Atactic polystyrene glasses were molded at high pressures by cooling the polymer melt at pressures up to 5000 atm. Changes found in the properties of the samples included: a lower mechanical damping factor at temperatures from 50°K to 300°K; a higher compressive elastic modulus; a maximum in compressive yield stress at a molding pressure around 1000 atm; faster relaxation at yield; appearance of an exothermic dilational relaxation below Tg when the samples were heated; and faster relaxation in methyl ethyl ketone vapor. The observed behavior is interpreted in terms of a model based on pressure‐induced heterogeneities in local order. The initial effect of increased molding pressure is to produce a more compact polymer which has less segmental mobility and more extensive interchain forces. Above molding pressures of about 1000 atm, a second effect develops due to the apparent formation of localized conformations which are stable under the high‐pressure vitrification conditions, but not at room conditions. The spontaneous decay of these high‐energy regions leads to subsequent formation of microvoid defects and more rapid structural relaxation effects. The existence of an optimum molding pressure somewhat below 1000 atm is indicated for polystyrene.
Polyelectrolyte effect and conformational transition in a restricted polyacid structure
Authors: Healy E. M. , Ramsley A. O. , Natsios B. A.
Published: April 2003

In a polyacid consisting of polyacrylic acid attached to a polyamide matrix, marked effects in equilibrium acid–base characteristics are observed, attributable to a hindered polyelectrolyte structure. In the presence of neutral electrolyte, the very high values found for pKa drop sharply. A break in the Henderson‐Hasselbalch curve indicates a conformational transition at α = 0.55 which is deferred to 0.95 by the presence of neutral electrolyte.
The production of rubber‐modified polystyrene. Some criteria influencing the selection and design of the agitator system
Authors: Freeguard G. F. , Karmarkar M.
Published: April 2003

The importance of selecting the most suitable form of agitation for the prepolymerization step in the production of rubber‐modified polystyrene by a bulk polymerization procedure is related to the non‐Newtonian behavior of the polymerizing system and to the existence of a minimum shear rate requirement. The procedure for the design and calibration of a small‐scale reactor system is described which is shown to produce an adequate phase inversion of the prepolymer and from which data can be evaluated for any change in scale of the operation. Structural patterns in the final polymer are linked with average shear levels in the reactor.
The effect of solvent traces on the ultraviolet degradation of poly(vinyl chloride)
Authors: Kamal M. R. , El‐Kaissy M. M. , Avedesian M. M.
Published: April 2003

The ultraviolet degradation of poly(vinyl chloride) films was studied in a photoreactor which supplied energy near 3000 Å. It was noted that the rate of degradation and color development was increased when the level of residual solvent in the cast films was increased. Two solvents were employed in the study: tetrahydrofuran and dichloroethane. The amount of residual solvent was correlated with the height of a characteristic peak at 2800 Å for tetrahydrofuran and 1900 Å for dichloroethane. Films which had very small traces of solvent showed excellent resistance to ultraviolet degradation, even in the absence of ultraviolet stabilizers. The analysis of solubility data showed that chain scission was controlling in the early stages of exposure, while crosslinking was controlling at later stages. As a result, it was not possible to apply Charlesby's treatment of radiation‐induced degradation. Comparison with the results obtained by other workers for degradation at 2537 Å showed that degradation at this wavelength was much faster than degradation at 3000 Å. Furthermore, degradation at 2537 Å appeared to be controlled by crosslinking at all stages of exposure.
Action of alkali metal hydroxides on cotton
Authors: Zeronian S. H. , Cabradilla K. E.
Published: April 2003

The swelling of cotton increased continuously as the concentration of LiOH solution was raised progressively to saturation. In contrast, the swelling of cotton treated with NaOH or KOH leveled off at higher concentrations after increasing initially. The maximum swelling achieved with NaOH was higher than that obtained with LiOH, which was higher than that given by KOH. Accessibility of cotton treated with LiOH solutions, as indicated by sorption ratios, was lower than that of cotton treated with NaOH or KOH solutions of similar concentrations. The level‐off degree of polymerization (LODP) of cotton treated with similar concentrations of alkali decreased in the order LiOH, NaOH, KOH. The reactivity, as indicated by acetylation, of cotton treated with alkali metal hydroxides, washed with water, and never dried was measured. At concentrations between 5.5.N and 8.2N, the rate of increase of reactivity was relatively low for cotton treated with NaOH, and no increase was observed for cotton treated with KOH. The reactivity of LiOH‐treated cotton continued to increase sharply up to treatment with a saturated solution of the alkali. A limited number of observations were also made on cotton treated with CsOH and RbOH. Accessibility, reactivity, extent of swelling, and LODP values, together with x‐ray data, are discussed in relation to the fine structure of the alkali‐treated fiber.
The glass transition temperature of a filled binder by nuclear magnetic resonance and thermal mechanical analysis
Authors: Price E. , French D. M. , Tompa A. S.
Published: April 2003

The glass transition temperatures of a binder and filled binder were determined by wide line proton nuclear magnetic resonance and by thermal mechanical analysis. The NMR study indicated only one transition temperature for the binder and three transition temperatures for the filled binder. TMA data gave two transition temperatures each for the binder and for the filled binder. These transition temperatures in the filled binder were interpreted as representing two phases: one for the filler‐oriented binder and one for the bulk phase. A comparison of the transition temperatures of the binder and filled binder indicates that the transition temperature of the former is raised by the presence of the filler. It was also found that the presence of water lowered the transition temperature of the filled binder used in this work.
Photochemical degradation of poly(ethylene terephthalate). II. Effect of wavelength and environment on the decomposition process
Authors: Day M. , Wiles D. M.
Published: April 2003

Poly(ethylene terephthalate) has been irradiated with UV light of different wavelengths and in various atmospheres. The extent of degradation was monitored by measuring the tensile strength, molecular weight, carboxylic acid endgroups, and fluorescence emission of the polymer. The importance of wavelengths <315 nm in causing deterioration was demonstrated to be mainly due to strong surface absorption which results in surface crazing and ultimate fracture under stress. Irradiation in nitrogen and under vacuum were found to give similar results, but with oxygen present in the system several significant differences were observed. In nonoxidative irradiations, crosslinking and discoloration of the polymer occurred. Under oxidative conditions, chain scissions and fluorescent material build‐up resulted, whereas no crosslinking and only slight discoloration was observed. The possibility of a photo‐oxidation reaction has thus been suggested, involving hydroperoxide formation, to explain the discrepancy in results obtained for the two types of environments.
Photochemical degradation of poly(ethylene terephthalate). III. Determination of decomposition products and reaction mechanism
Authors: Day M. , Wiles D. M.
Published: April 2003

The vacuum photolysis and air photo‐oxidation of poly(ethylene terephthalate) were studied using light in the wavelength ranges of 225–420 nm and 300–420 nm. The volatile photodegradation products were determined by mass‐spectrometric and gas‐chromatographic analysis; CO and CO2 were found to be the predominant products. In addition, the rates of formation of carboxylic acid endgroups and the net weight losses of the film samples were determined as a function of irradiation time. Quantum yields for the initial rates of formation of CO and CO2 and of COOH within the film were calculated. On the basis of the results obtained, in this and the preceding papers in this series, reaction mechanisms have been proposed for the photochemical degradation of the polymer. The production of CO and COOH in both vacuum and air have been attributed mainly to a Norrish type I cleavage and a Norrish type II photorearrangement, respectively. It has also been concluded that, in the presence of air, an oxidative reaction sequence occurs whereby alkyl radicals produced on photolysis react with oxygen to form ROO. radicals. These subsequently react further to produce CO2 as the main volatile product of photooxidation.
Changes in porosity of treated lint cotton fibers. I. Purification and swelling treatments
Authors: Porter Blanche R. , Rollins Mary L.
Published: April 2003

Changes in the internal morphology of lint cotton fibers during purification and swelling treatments were investigated by measurement of nitrogen adsorption at liquid nitrogen temperature. Surface areas and pore size distributions were calculated from the adsorption isotherms and compared with findings from measurements of changes in crystallinity and in fibrillar aggregation as shown by electron micrographs. The adsorption measurements were made on fibers which were either preswollen in water or taken from the rinse water after treatment and solvent exchanged through methanol and n‐pentane to helium. The large changes found in surface area, pore size distribution, and fibrillar aggregation were accompanied by changes in crystal structure in fibers treated with 5.0M sodium hydroxide. Large changes following treatment with phosphoric acid occurred in pore structure and fibrillar aggregation without concomitant change in crystallinity.
Changes in porosity of treated lint cotton fibers. II. Treatments for chemically modifying cotton
Authors: Porter Blanche R. , Rollins Mary L.
Published: April 2003

Changes in the internal morphology of chemically modified lint cotton fibers were investigated by measurement of nitrogen adsorption at liquid nitrogen temperature. Surface areas and pore size distributions were calculated from the adsorption isotherms and compared with findings from measurements of changes in crystallinity and of fibrillar aggregation as shown by electron micrographs. Fibers were either preswollen in water or taken from the rinse water and solvent exchanged through methanol and n‐pentane to helium before adsorption measurements were made. Unless reacted in the presence of water, the wrinkle resistance treatments studied caused losses in surface area of 55% or greater. Changes in surface area and porosity of cottons reacted with monofunctional reagents designed to give protective and other types of finishes were dependent on the type of reaction used.
Pyrolysis and combustion of cellulose. III. Mechanistic basis for the synergism involving organic phosphates and nitrogenous bases
Authors: Hendrix James E. , Drake George L. , Barker Robert H.
Published: April 2003

The flame retardation mechanisms for cellulose treated with systems based on aromatic phosphates and phosphoramides have been investigated through pyrolysis studies on cellulose and related model compounds. Pyrolysis of cellulose treated with phosphates or phosphoramides proceeds through formation of cellulose phosphate or phosphoramide esters, followed by subsequent ester pyrolysis to yield a dehydrated cellulose char. Formation of phosphoramides during pyrolysis of flame retardants containing phosphorus and nitrogen constitutes a possible basis for reported phosphorus‐nitrogen synergistic effects observed in commercial flame retardants. Efficiency of ester formation is higher, and subsequent pyrolysis is lower for phosphoramides than for phosphate esters. The build‐up of a thermally stable crosslinked matrix in the residue occurs on pyrolysis of cellulose treated with phosphoramides. Such crosslinking seems to be effective in enhancing flame retardation.
Relationship in polypropylene melt between its linear viscoelasticity and its steady capillary flow properties
Authors: Fujiyama Mitsuyoshi , Awaya Hiroshi
Published: April 2003

It is the object of the present study to obtain clear knowledge of the relations in the polypropylene melt between its linear viscoelasticity and its nonlinear steady capillary flow, paying particular attention to the elastic properties in its capillary flow. By representing the linear viscoelasticity numerically with zero‐shear viscosity, η0, and steady‐state compliance, J, evaluation has been made of the properties concerning the elasticity of polymer melt in the capillary flow, such as non‐Newtonianity, the entrance pressure loss, the end correction, the Barus effect, and the melt fracture. The steady flow viscosity η, the entrance pressure loss P0, the critical shear stress, τc, and the critical shear rate $\dot \gamma _c$ at which melt fracture begins to occur are subject to η0 as follows:

From the well‐known relationship between η and the weight‐average molecular weight M̄w, these quantities are governed by M̄w. Meanwhile, for such quantities as structural viscosity index N, end correction coefficient ν, and elastic pressure loss ratio P0/P, following correlations hold:

As η0 and J are respectively determined mainly by M̄w and the molecular weight distribution MWD, these quantities are governed by both M̄w and MWD. Physical meanings of η0·J and η02 · J are, respectively, mean relaxation time and a measure of stored energy in steady flow. The Barus effect has a positive correlation to J, ν, and P0/P. (The symbol ∝ employed here means positive correlation.)
Optical detection of thermal transitions in high polymers
Authors: Kovacs A. J. , Hobbs S. Y.
Published: April 2003

This report describes a series of recent experiments in which various thermal transitions including stress relaxations and glass transitions in high polymers were characterized by observing birefringence changes during heating and cooling. An automatic recording device employing a hot stage, polarizing microscope, photocell, and chart recorder was employed in these investigations. A general discussion of the utility and advantages of the technique of thermo‐optical analysis (TOA) as well as its deficiencies is presented. Characteristic birefringence–temperature profiles of a number of amorphous and semicrystalline polymers are included.
A generalized method for correcting instrument spreading in gel permeation chromatography
Authors: Chang Kun S. , Huang Robert Y.
Published: April 2003

A general method of chromatogram correction for skewed instrument spreading in gel permeation chromatography is presented. The correction method is so general that there is no restriction on the shape of the spreading function. It admits nonsymmetric, non‐Gaussian as well as nonconvolution type. Aspects of solution techniques are discussed and an illustrative example is given to elucidate the method.
Polyimidazopyrrolones and related polymers. II. Polyimidazopyrrolones from aromatic dianhydrides and 3,3′‐dichloro‐5,5′‐diaminobenzidine
Authors: Bower G. M. , Frost L. W.
Published: April 2003

The preparation of 3,3′‐dichloro‐5,5′‐diaminobenzidine and its polymeric reaction products with pyromellitic dianhydride and 3,4,3′,4′‐benzophenonetetracarboxylic dianhydride are described. The soluble amine–acid–amide form of the polymer is stable at higher concentrations than the corresponding polymers from 3,3′‐diaminobenzidine or 3,3′,4,4′‐tetraaminodiphenyl ether. Infrared spectra indicate that polybenzimidazopyrrolone structure is formed after cure. The preparation and properties of films and glass‐reinforced laminates prepared from the polymers are described.
Sodium cellulosates–preparation from various alkoxides and reactivity toward 2‐chloroethyldiethylamine
Authors: Soignet D. M. , Berni R. J. , Perrier D. M. , Benerito R. R.
Published: April 2003

Sodium cellulosates were prepared by reacting premercerized cotton fabrics with sodium salts of selected alcohols. The degree of conversion to the cellulosate was related to the Taft polar substituent constant, σ*, of the alkoxide R group. Increase in size of the R group in the alkanol series did not decrease the degree of cellulosate formation. The extent of reaction of the cellulosates with 2‐chloroethylidiethylamine in tertiary butanol to form diethylaminoethyl cellulose (DEAE‐cotton) did not increase with the sodium ion content of the starting cellulosate substrate.
Time–temperature superposition of large‐strain shear properties of the ethylene–propylene copolymer system
Authors: Bahadur S. , Ludema K. C.
Published: April 2003

The principle of time temperature superposition for some mechanical properties of polymers is well known, particularly where strains are on the order of 1% or less. For large strains the simple data transformation techniques are not useful, probably because of morphological changes in the polymer. Morphological changes have the effect of changing the mechanical properties, thus necessitating a shift on the verticle axis as well as horizontal axis where mechanical properties are plotted on the ordinate and strain rate, e.g., is plotted on the abscissa. By the Rouse and Zimm theories of flexible chain polymer molecules a relationship is shown between a verticle shift and a horizontal shift, thereby making it unnecessary to determine the exact nature of morphological changes in the polymer when strained. Six polymers were strained to the fracture point and the shear modulus and fracture strength data were used to demonstrate the technique of simultaneous verticle and horizontal transformation of data.
Polymer encapsulation of colloidal asbestos fibrils
Authors: Xanthos M. , Woodhams R. T.
Published: April 2003

The free‐radical polymerization of several monomers in an aqueous suspension containing chemically opened chrysotile asbestos fibrils was investigated with the intention of promoting complete encapsulation of the individual colloidal fibrils. The degree of polymer deposition on the colloidal substrate is dependent upon several factors including monomer and polymer solubility, initiator type, ionic comonomers, and degree of interfacial wetting. Successful encapsulation was achieved by the addition of novel unsaturated polyelectrolytes which served a dual role as dispersing agent and comonomer. Such methods are useful for the preparation of reinforced composites with controlled interfacial properties. In one example, it is shown that asbestos fibrils surrounded by a rubbery layer can impart greater toughness to a reinforced composite, compared to a composite in which the rubbery phase is dispersed at random or isolated from the interface. The technique can be extended to other types of fillers. The various methods of chemically “opening” asbestos are summarized.
Studies on mixture dyeing. IV. Equilibrium adsorption of direct dyes
Authors: Morita Zenzo , Iijima Toshiro , Sekido Minoru
Published: April 2003

Chrysophenine G (C.I. Direct Yellow 12), Benzopurpurine 4B (Red 2), Sirius Red 4B (Red 81), Sirius Supra Blue BRR (Blue 71) and Sky Blue 6B (Blue 1) were selected as typical direct dyes, and the equilibrium adsorptions on cellulose (Cellophane) from the 1:1 and 2:1 molar mixture dye baths were investigated at 90° and 70°C. The standard affinity in mixture dyeing was obtained by the equation derived from the assumption of monodispersed and diffusive adsorption. The standard affinity in mixture dyeing was nearly equal to that in single dyeing, except for the Chrysophenine G–Sky Blue 6B system. However, judging from the fiber and solution log sum plots, there was a definite difference between mixture and single dyeing. It was explained by the change of activity of dye and sodium ions on substrate followed by the marked change of the total adsorption. The adsorption behavior of direct dyes is discussed in detail from the viewpoint of concentration dependence of the activity coefficient of dye and sodium ions on the substrate.
Determination of parameters in convected Maxwell model from linear viscoelastic parameters
Authors: Hlaváček B. , Seyer F. A.
Published: April 2003

Owing to its simplicity and general ability to correctly portray a number of important flow phenomena, the two‐parameter Maxwell model has been employed in a number of important engineering studies. The relation of this equation to linear viscoelasticity and to some molecular theories is considered. A new rule is developed which shows how the shear‐dependent relaxation time and viscosity of the Maxwell model can be determined from linear viscoelastic parameters. It is thus shown that the two‐parameter Maxwell model may be more general than earlier anticipated.
Esterification of styrene–maleic anhydride copolymer by mixed alcohols
Authors: Aoyagi J. , Shinohara I.
Published: April 2003

A copolymer (MW = 1800) of styrene (St) and maleic anhydride (MAn) was esterified with an excess amount of an alcohol mixture, and then the relation between the esterification rates of the individual alcohols and the contents of the esters in the esterific copolymer was examined. At first, the rate constant of an individual esterification was obtained for four different alcohols (n‐butanol, i‐amylalcohol, and benzylalcohol) in a noncatalyst system. Then, the mixed esterification of n‐butanol and i‐amylalcohol was carried out; from the analysis of the ester contents, the following equation was obtained:

From this result, it was concluded that, in esterification with alcohols involving n species, the content of the individual ester can be expressed by the following equation:

where [P] = concentration of esters in the copolymer, [B]0 = initial concentration of alcohols, and k = rate constant of esterification (i,j = 1,2…,n).