bluuebunny/crossref_metadata_2025 huggingface dataset:
Photochemical degradation of poly(ethylene terephthalate). IV. Surface changes
Authors: Blais P. , Day M. , Wiles D. M.
Published: April 2003

The chemical, physical, and mechanical changes in the surface properties of poly‐(ethylene terephthalate) film produced by ultraviolet light have been examined. Attenuated total reflection infrared spectroscopy has indicated that numerous chemical scission reactions occur in the front surface layer facing the source of irradiation, resulting in the formation of carboxylic acid endgroups. This preferential surface phtodegradation has been confirmed by examining the cross section of irradiated film by electron beam‐induced luminescence. Conventional electron microscopy revealed little changes in the surface appearance of irradiated film. However, indirect techniques were devised which indicated that changes do occur in the physical properties of the surface. These observed changes are believed to be responsible for the decrease in film tensile strength, which has been shown to be a surface phenomenon and not a bulk property.
Modification of oxidized lignins with styrene
Authors: Katuščák S. , Mahdalík M. , Hrivík A. , Minárik V.
Published: April 2003

The effect of original and ozonized lignins upon the polymerization of styrene was investigated. It was found that the unoxidized lignin prepared by hydrolysis of spruce wood meals with 42% HCl retards the thermal polymerization of styrene. The ozonization of HCl‐lignin leads to its chemical transformation during which two types of functional groups are formed: those inhibiting and those initiating the polymerization of styrene. Moreover, the polymerization of styrene in the presence of oxidized HCl‐lignin affords both homopolymer and grafted copolymer. The amount of the grafted copolymer depends upon the concentration of active oxygen in lignin formed during oxidation, upon the temperature of polymerization, and, finally, upon the kind and concentration of the solvent used in the polymerization system.
Preparation and copolymerization of divalent metal salts of ethylene glycol–methacrylate–phthalate
Authors: Matsuda Hideaki , Miyoshi Noriyuki
Published: April 2003

Divalent metal salts of ethylene glycol–methacrylate–phthalate (EMP) were prepared by the reaction of EMP and divalent metal ions in aqueous solution. The divalent metal salts obtained, except for the Pb salt, have melting points which decrease in the order of Ca > Ba > Mg > Zn > Cd salt. The Zn and Cd salts are fairly soluble in most organic solvents. Therefore, the Zn salt and Cd salt were selected for the copolymerization with MMA, styrene (St), and hydroxyethyl methacrylate (HEMA). In the copolymerization, the rates of copolymerization increased markedly as the concentration of metal salts increased. Moreover, the systems containing MMA copolymerized more rapidly than those containing St. As for the physical properties of the copolymers obtained, compressive strength and Rockwell hardness were improved by introducing metal salts into the polymers; and heat distortion temperature and tensile and flexural strengths were also improved by selecting the most suitable concentration of metal salts according to the species of metal salts and vinyl monomers. The TGA and the boiling water resistance of the copolymers were also discussed.
Physical structure of phenolaniline–formaldehyde resol resin and its kaolin–filled phenoplasts
Authors: Bozveliev L. G. , Mihajlov M. G.
Published: April 2003

An investigation of the physical structure of samples of phenoaniline–formaldehyde resol resin in uncured and cured state, and of its phenoplasts containing different ratios of kaolin filler, was made with the aid of electron microscope pictures. The uncured and cured resin consists of microglobules of a size of 40–80 Å, which agglomerate to form larger‐sized globules of various dimensions. After a mathematical elaboration of the results of a large number of measurements, it was established that the diameters of the globules are casual values distributed in accordance with the normal (Gaussian) law. Both in the resin and in the kaolin‐filled phenoplasts (at a rate of 25 to 47 vol‐%), after curing at 170–180°C and a pressure of 300 kg/sq cm, the mean diameter of the observed globules was of a rather steady value and remained within the limits of 230–240 Å (with a standard deviation of 30–40 Å). A method was elaborated of determining the mean thickness of the adsorption coating of the resin on the filler particles. Calculations show that in the filling interval we have chosen, the thickness of the absorption coating is not below 1.8–0.6 times the mean thickness of the globules.
Factors influencing the market for tires and tire fibers
Authors: Sonnecken Edwin H.
Published: April 2003

Not only technology, but domestic and international economic considerations, social developments, consumer lifestyles, and political pressures are the determinants of tomorrow's tire market. Tires for global markets are subject to international competition and world tire standards. Over‐the‐road highway tires—auto and truck—need improved technology to meet government safety regulations at affordable user costs. Grading and labeling implies substantial pressure on constructions and fibers. Vehicle design changes to meet demands of changing lifestyles bring other implications for tire and fiber markets. Cost per ton of freight hauled is becoming increasingly important. Earthmover tires of the future will be required to haul greater loads at higher speeds, meaning much larger vehicles, bigger tires, and higher ton miles per hour of payload.
Epoxy thermosetting systems: Dynamic mechanical analysis of the reactions of aromatic diamines with the diglycidyl ether of bisphenol A
Authors: Babayevsky P. G. , Gillham J. K.
Published: April 2003

Dynamic mechanical behavior during the reactions of four aromatic diamines (m‐phenylenediamine, 4,4′‐diaminodiphenylmethane, 4,4′‐diaminodiphenyl sulfone, and benzidine) with the diglycidyl ether of bisphenol A was studied by torsional braid analysis under isothermal conditions. Depending on the cure temperature, three types of behavior were observed: (I) below Tgg (the glass transition temperature of the reactive systems at the gel point); (II) between Tgg and Tg∞ (the glass transition temperature of the ultimately cured polymers); (III) above Tg∞. Overall activation energies and apparent overall rate constants of the cure reactions based on third‐order overall kinetics were determined before gelation, after gelation but before vitrification, and after vitrification, using gelation time, relative rigidity, and glass transition temperature Tg(t) of the polymers as kinetic terms. The influence of cure temperature and structure of the diamines on the kinetic parameters is discussed.
Modification of nylon 6 by organochlorosilanes. I. Chemical reaction
Authors: Varma I. K. , Mandal R. , Varma D. S.
Published: April 2003

The reaction of nylon 6 with dimethyldichlorosilane and vinylmethyldichlorosilane was investigated. Bright, 20‐denier monofilament, nylon 6 yarns with 12.83% nitrogen, 61.16% carbon, and 10.16% hydrogen content were taken. Benzene or toluene was used as solvent for the reagents. The extent of reaction was estimated from the increase in weight of the parent yarn. Reaction was carried in the presence of nitrogen or in atmospheric oxygen (air). The per cent weight gain increased with increase in concentration of reagents, time, and temperature of the reaction. Viscosity and dyeability of the modified samples were measured, and in some samples the percentage of carbon, hydrogen, and nitrogen was also determined.
Modification of nylon 6 with organochlorosilanes. II. Physical properties
Authors: Varma I. K. , Mandal R. , Varma D. S.
Published: April 2003

The physical properties of nylon 6 yarn treated with dimethyldichlorosilane (DMCS) and vinylmethyldichlorosilane (VMCS) in nitrogen atmosphere or air in the presence and absence of an amine have been compared with those of ether‐extracted parent yarn. Treatment with DMCS in nitrogen resulted in marginal improvement in breaking stress, considerable increase in breaking elongation, and elastic behavior, whereas initial modulus was decreased. A decrease in density, birefringence, and moisture regain with increase in per cent weight gain was observed. Mechanical damping was decreased considerably up to an optimum weight gain after which it was increased. Thermal properties were also determined, and results are discussed in relation to mechanical properties. The results indicate that the overall thermal stability has decreased in the chemically treated yarns. Treatment with organochlorosilanes in the presence of air results in a chain‐scission reaction and a decrease in mechanical properties.
Polymerization of laurinolactam. I. Impurities in industrial laurinolactam and their influence on anionic polymerization
Authors: Bukac̆ Z. , S̆ebenda J.
Published: April 2003

Fractions containing predominantly cyclododecanone (0.02%), C24 hydrocarbons (0.02%), and probably isomers of the mono‐ and diunsaturated 13‐membered lactam (0.05%) were isolated from industrial laurinolactam. Both the cyclic ketone and unsaturated lactams slow down the anionic polymerization of laurinolactam, but they exert only insignificant or no effects on the molecular weight of the resulting polymer if the polymerization has been activated with N,2‐disubstituted 3‐oxoamide. On the other hand, the molecular weight is greatly affected by the type of catalytic system. Of the purification techniques tested, the most effective and advantageous one was crystallization from 1,2‐dimethoxyethane.
Viscoelastic properties of epoxy resins. II. Antiplasticization in highly crosslinked epoxy system
Authors: Hata Naoaki , Yamauchi Ryo , Kumanotani Ju
Published: April 2003

The effect of the addition of certain low molecular weight compounds to highly crosslinked epoxy resins was investigated. The behavior which is known as antiplasticization, such as increases in modulus and yield strength and the elimination of β‐transition, was observed in the highly crosslinked system as well as in the reported cases of thermoplastics—poly(vinyl chloride), bisphenol A polycarbonate, and polysulfone. Chlorinated biphenyl was found to be one of the most effective antiplasticizers examined in the present paper. However, the remarkable reduction in compressive strain at break and impact strength was not recognized for the highly antiplasticized samples. These phenomena have been interpreted on the basis of free volume concept.
Sorption behavior of mercuric salts on chemically modified wools and polyamino acids
Authors: Friedman Mendel , Masri Merle Sid
Published: April 2003

Wool derivatives with sulfhydryl, thiosulfate, imidazole, pyrrolidone, or pyridine side chains were prepared and tested as potential scavengers for mercury salts in aqueous solution. More mercury is bound by these derivatives than by native wool or by certain commercial ion exchange resins under similar conditions. The presence of chloride ion, but not sulfate ion, in aqueous media decreased the extent of binding of mercuric chloride to both native and modified wools. The relative binding of mercuric chloride by various poly(amino acids) suggest that mercury is taken up by proteins by processes other than (or in addition to) specific combination with free functional groups. Two possibilities are suggested: the protein may act as a solid solvent for the mercurial, or the mercurial may form aggregated deposits within the protein after the specific binding sites have been occupied. These studies are intended to elucidate factors that govern mercury interaction with wool and other proteins and to develop improved scavengers for toxic metals.
Thermomechanical behavior of a polynorbornadiene
Authors: Roller M. B. , Gillham J. K. , Kennedy J. P.
Published: April 2003

A high‐temperature linear amorphous hydrocarbon polymer synthesized cationically from 2,5‐norbornadiene (bicyclo[2.2.1]hepta‐2,5‐diene), was studied thermomechanically with respect to physical transitions and stability in nitrogen. The glass transition temperature was determined to be 320°C (at less than 1 cps), which is probably the highest known for a linear hydrocarbon addition polymer. The thermomechanical technique of torsional braid analysis, together with thermogravimetric analysis, differential thermal analysis, infrared analysis, and solubility studies, was used to investigate the sequential events of the glass transition and degradation. The polymer is of particular interest since it is a high‐temperature plastic which in the bulk form would probably need to be processed at high speeds in the vicinity of Tg in an inert atmosphere. The presence of tertiary hydrogen atoms should render it amenable to degradation by the earth's environment.
Fractionation of polypropylene by the rising temperature method
Authors: Ogawa Toshio , Hoshino Sadao
Published: April 2003

Polypropylene having high isotacticity was fractionated by the rising temperature method. This method was then compared with the solvent gradient method through the characterization of fractions. It was found that the elution behavior in the rising temperature method was explainable by the equation of equilibrium between the polymer in dilute solution and the solid state polymer on the support, assuming that the heat of fusion and transition points for the deposited polymer were variable with polymer species.
Vinyl bromide polymerization with alkylboron and alkyl halide catalyst
Authors: Akimoto Akira
Published: April 2003

Trialkylboron–alkyl halide catalyst systems were found to induce the polymerization of vinyl bromide and other vinyl monomers at low temperatures. Tri‐n‐butylboron is the most effective catalyst. Among alkyl halide, carbon tetrachloride gives the best yield of poly(vinyl bromide). The polymerization process can be controlled by adjusting the reaction conditions of the initiating components. The rate of polymerization varies depending on the diluent.
Performance of cellulose acetate butyrate membranes in hyperfiltration of sodium chloride and urea feed solution
Authors: Wydeven T. , Leban M.
Published: April 2003

Cellulose acetate butyrate (CAB) membranes gave high salt and urea rejection with a water flux of about 3 gfd (gallons/ft2 · day) during hyperfiltration at 600 psig. Evidence was obtained which indicated that the CAB membranes used in this work were asymmetric. Membrane heat treatment increased urea rejection significantly while salt rejection was invariant, and water flux decreased. An increase in feed solution temperature caused a significant increase in water flux and a small decrease in urea and salt rejection. Increasing the pressure increased water flux and urea and salt rejection. During a 400‐hr life test, the water flux decreased by about 25% while urea rejection increased and salt rejection was invariant. The influence of pressure, membrane heat treatment, and compaction during CAB membranes life testing on urea and salt rejection provided evidence that these two solutes were rejected by somewhat different mechanisms. Salt rejection was consistent with a solution–diffusion mechanism for membrane transport and uncoupled flow while changes in urea rejection with pressure, membrane heat treatment, and compaction during life testing suggested that urea was at least partially rejected by membrane exclusion resulting from geometric factors.
Preparation and copolymerization of polyvalent metal salts of ethyleneglycol–methacrylate–phthalate
Authors: Matsuda Hideaki , Dohi Hidemi
Published: April 2003

Preparation of polyvalent metal salts of ethyleneglycol–methacrylate–phthalate (EMP) was investigated by the reaction of the Na salt of EMP and chlorides of polyvalent metals such as Al3+, Cr3+, Fe3+, Ni2+, Co2+, and Cu2+. It was found that, among the metal salts obtained the Cr salt could be obtained in the form of (EMP)2− Cr(OH) in high purity and good yield where EMP means EMP residue: (EMP)2−
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Cr(OH) is soluble in chief organic solvents and vinyl monomers such as styrene (St) and MMA. (EMP)2Cr(OH) was then copolymerized with St and MMA. As for the physical properties of the copolymers obtained, heat distortion temperature, compressive strength, and Rockwell hardness were generally improved by introducing (EMP2)Cr(OH) into the polymers. Tensile strength, flexural strength, and impact strength were also improved by selecting the most suitable concentration of (EMP)2Cr(OH) according to the species of vinyl monomers. Moreover, the physical properties of (EMP)2Cr(OH)–MMA copolymers are generally superior to those of (EMP)2Cr(OH)–St copolymers. TGA and boiling water resistance of the copolymers were also discussed.
Dynamic rheological properties of bromine‐terminated polybutadiene melts
Authors: Dunlop A. N. , Williams H. Leverne
Published: April 2003

The viscous and elastic properties of bromine‐terminated polybutadiene were investigated as functions of temperature, molecular weight, and molecular weight distribution. They were found to depend on these variables in a manner similar to other polybutadienes. It was shown that the effect on the viscous properties due to bromine terminal functionality is not as great as for carboxyl and/or hydroxyl terminal functionality. In this study it was shown that the viscosity resultant from the blending of two samples of the same polymer differing in molecular weight is dependent on the polydispersity of the polymers from which the blend is prepared. A form of the Ninomiya and Ferry theory was modified and compared with experiment. As a result of the experiments involving blending, it was shown that the temperature dependency of elasticity is less for polymers exhibiting greater polydispersity.
Studies of relaxation phenomena in polymers. I. The use of periodic square and triangular stress functions
Authors: Jansson Jan‐Fredrik
Published: April 2003

In order to evolve the methods of mechanical spectroscopy and find new methods of studying the rise of nonlinear viscoelasticity, periodic square and triangular stress functions have been used. A “new” viscoelastic function is defined, log J2 = g{log J1}, where J1 and J2 are the compliances at the time (ζ/2 + 2nζ)n→∞ for an odd, periodic, square function and an even, periodic, triangular function, respectively, with periods of 2ζ. The function shows characteristic shapes for viscoelastic spring and dashpot models. The interrelations between the complex compliance and J1 and J2 are developed; and since the sum of J1 and J2 at the time ζ/2 agrees very well with the creep compliance at the same time, J1 and J2 can be used as an interrelation between complex compliance and creep compliance. Special equipment for measuring the compliances J1 nd J2 is described.
Studies of relaxation phenomena in polymers. II. The behavior of simple polymers in their main transition region
Authors: Jansson Jan‐Fredrik
Published: April 2003

In an earlier paper, a “new” viscoelastic function, log J2 = g{log J1}, was defined. For polymers, the linear viscoelastic behavior of which is characterized by “simple segment movements” in their main transition regions, the following general properties are found: (1) The local maxima of the function for different polymers fall along a straight line width the slope approximately equal to 1.1. (2) A characteristical general shape is noticed for the function after shifting along the straight line and reducing the J1 compliance as regards the “frozen in” compliance J10. (3) J1 reflects the storage and J2, the loss mechanisms of the system. The relation J2/J1 is an expression for the average retardation time.
Studies of relaxation phenomena in polymers. IV. Superimposed transition mechanisms in polymethacrylates
Authors: Jansson Jan‐Fredrik
Published: April 2003

The existence of superimposed transition mechanisms in the “Tg region” of polymethacrylates has been indicated by several authors including Ferry and co‐workers, who also have tried to separate the mechanisms. Using the general properties of the viscoelastic function logJ2 = gα {log J1} and a simple weighting model, the α‐and β‐mechanisms have been separated. The viscoelastic function log J2 = gβ{log J1} is determined and is found to coincide both where different polymethacrylates are concerned and for the calculated as well as the directly measured data.
A statistical method for computer treatment of elastomer flex data
Authors: Derringer George C.
Published: April 2003

In flex testing of elastomers, the length of a cut is measured periodically as a function of the number of flexing cycles. In most cases a large number of measurements is accumulated for each test piece which would lead one to believe that the results should have a high degree of precision. This, however, is not the case, mainly because not all of the measurements are used to express the final result. Instead of being a precise test, flex testing is in fact notorious for its irreproducibility. A new method is proposed for computer treatment of flex data in which all of the flex measurements are fitted to an empirical equation by means of nonlinear regression analysis. From the fitted equation, more precise estimates of rate of growth and growth initiation point can be obtained than is possible using the data treatment procedures proposed by ASTM. Also a new index of flex life is defined which is conveniently scaled from 0–100. This so‐called flex index is a convenient index of overall flex behavior.
Molecular aggregation in poly(vinyl chloride)
Authors: Abdel‐Alim A. H. , Hamielec A. E.
Published: April 2003

Molecular weight distributions and molecular aggregation for poly(vinyl chloride) (PVC) polymerized in bulk at −10, −30, and −50°C have been measured using gel permeation chromatography. The aggregate content in PVC polymerized at −50°C was found to be 87 wt‐%. These spherical aggregates of mean diameter of 5000 A are formed preferentially from PVC chains having high molecular weights and long syndiotactic sequence lengths. A temperature of 200°C was used to disintegrate these aggregates into single PVC molecules. In disagreement with measurements of Mn and Mw published in the literature, our measured values do not reach a minimum but rather increase continuously with decreasing temperature of polymerization. This disagreement is most probably due to the phenomenon of molecular aggregation in PVC.
The preparation and acid‐catalyzed hydrolysis of polyoxymethylene isopropyl methyl ethers
Authors: Stanonis David J. , Vail Sidney L. , King Walter D.
Published: April 2003

The first four members of the polyoxymethylene ether series (CH3)2CHO(CH 2O)nCH3 were prepared, separated by fractional distillation and GLC, and characterized by NMR. Rate constants for the aqueous acid hydrolysis of the compounds were determined at 25°, 30°, and 35°C. Although the polyformals (n > 1) in this series hydrolyzed at essentially the same rate, they all hydrolyzed three times faster than the formal (n = 1). It is proposed that a mixed polyformal, (CH3)2CHO (CH2O)n>1CH3, undergoes two concurrent fissions to yield (1) the stem (CH3)2CHOCH2 with CH3O(CH2O)n−1 as the leaving group and (2) the stem CH3OCH2 with (CH3)2CHO(CH2O)n−1 as the leaving group. Most of the fissions occur by the first path. An equation that can aid in predicting the rate of hydrolysis of a mixed polyformal was developed and tested.
A rotating sphere viscometer
Authors: Kelkar J. V. , Mashelkar R. A. , Ulbrecht J.
Published: April 2003

The use of a rotating sphere viscometer for the measurement of parameters in the flow curves of inelastic as well as viscoelastic liquids is examined. An experimental investigation of the primary flow around a sphere rotating in Newtonian and viscoelastic liquids is carried out by using a new “three‐dimensional particle technique.” Currently available theoretical analyses of rotation of a sphere in viscoelastic liquids are shown to be inadequate to describe the experimental primary velocity distribution data. Theoretical results for the primary distribution derived on the basis of a creeping flow of a power law liquid are found to describe the experimental data well. This distribution is then used to derive torque–angular velocity relationships, which are then confirmed experimentally for both inelastic and viscoelastic liquids. The results of this work justify the use of a rotating sphere viscometer as a useful tool for the measurement of parameters of flow curves of inelastic and viscoelastic liquids.
Practical estimation of dilute solution parameters
Authors: Rudin Alfred , Strathdee Glenn B. , Edey W. Brain
Published: April 2003

The concentration dependence of viscosities of dilute solutions of nonpolar polymers can be expressed generally as power series in concentration. Intrinsic viscosity is often estimated from zero concentration extrapolations of the Huggins and Kraemer equations, which are truncated versions of virial expressions in concentration. Neither form is strictly valid at most practical concentrations since real curvilinear relationships are forced into rectilinear forms. Prior methods of overcoming this deficiency by basing extrapolation methods for [η] on more extended power series have attempted to provide graphically useful solutions. This requires reduction of the power series to a two‐parameter (slope and intercept) form and the assumption of certain relations between the various factors in the initial multiparameter expression. In this work, power series expressions in concentration are solved directly by nonlinear regression analysis. It is shown that no two‐parameter solution is generally valid, although each may be of value in a particular context. Three‐parameter power series extensions of the basic Huggins and Kraemer equations represent dilute solution viscosities up to concentrations of 1% or 2% (w/v) very well. The computer‐assisted nonlinear regression analysis is easily extended to higher powers of concentration, and the use of four‐parameter forms is illustrated to represent viscosities of polystyrene solutions with concentrations as high as 9%.
Determination of optimal reactor system configuration for polymerization reactions. II. Effect of chain transfer, autoacceleration, and temperature profile
Authors: Shastry J. S. , Fan L. T. , Erickson L. E.
Published: April 2003

The effect of chaln transfer, diffusion control, and temperature on the optimal design and selection of polymerization reactors was investigated. Chain transfer to the monomer was examined and a parametric study of the corresponding rate constant was carried out. The Trommsdorff effect was included in the model by using a diffusion‐controlled termination process. An optimum temperature sequence was determined for this modified model by incorporating the effect of temperature on the rate constants and on the amount and rate of heat removal. Furthermore, the concept of dividing the plug flow reactor into several constant temperature zones was considered, and the effect of “zoning” on the system performance was determined.
The water absorbency of hydrolyzed polyacrylonitrile‐grafted cellulose fibers
Authors: Lepoutre P. , Hui S. H. , Robertson A. A.
Published: April 2003

The water absorbency of a bleached softwood kraft pulp, as measured by its water retention value (WRV), was increased up to 30 times by graft polymerizing polyacrylonitrile (PAN) and subsequently hydrolyzing it to sodium polyacrylate–polyacrylamide copolymer. WRV was found to be related to the initial PAN graft level rather than to the final sodium polyacrylate content, and was independent of the grafting process used. However, the ceric ion process was found superior to both the cellulose xanthate–H2O2 and ferrous ion–H2O2 redox systems in that it occasioned only a minor loss during the hydrolysis stage and the WRV was less affected by drying. The WRV remained constant as pH was lowered from 9 to 5 but dropped to the level of unmodified pulp at pH 3.5 where the sodium salt is fully converted to poly(acrylic acid). Retention of 1% aqueous NaCl was about 60% of the WRV. The swelling properties of the grafted fibers under various conditions appear to be explained by considering the grafting to act in two ways: (a) the introduction of a potentially hydrophilic component capable of generating swelling pressures and (b) the reduction in the cohesion of the fiber by the interposition of graft polymer chains in the fiber structure.
An analysis for the calendering of non‐newtonian fluids
Authors: Alston Jr. William W. , Astill Kenneth N.
Published: April 2003

Equations are derived to predict the one‐dimensional behavior of a hyperbolic tangent fluid model flowing between calendering rollers. The equations were solved numerically on a computer, and results were obtained for maximum roller pressure and the exit thickness of the fluid sheet as a function of roller speed and reservoir size for three polymers. The numerical integration employed Gauss‐Legendre quadrature and a cascading iteration scheme to solve equations in which unknowns appeared in the limits of the integrals. Unlike existing power law solutions, these results show a definite relation between roller speed and exit thickness.
Polymer compatibility
Authors: Schneier Bernard
Published: April 2003

Bohn has compiled a list of polymer pairs on which compatibility studies have been reported. The list contains 13 polymer pairs for which, according to Bohn, compatibility as solids may be considered to be definitely established, at least within some regions of proportions. The approach used here is based on calculations which provide a value whose magnitude apparently differentiates between mixtures in Bohn's list which are either compatible as solids or incompatible. Data calculated on mixtures of styrene–acrylonitrile copolymers not included in Bohn's list systematize according to the same classification.
Electron irradiation of poly(olefin sulfones). Application to electron beam resists
Authors: Bowden M. J. , Thompson L. F.
Published: April 2003

All the poly(olefin sulfones) examined degraded rapidly under electron irradiation. The dose required to effect a molecular weight distribution completely separated from the original distribution as required for fractional solution development was similar for all polymers, viz., 1–2 × 10−6 coulomb/cm2. This indicates that they all have similar values for G(scission). The film thickness of the exposed area decreased at a rate dependent on olefin structure and temperature. This process, termed vapor development, has been attributed to concurrent chain scission and depolymerization. Factors determining the rate of depropagation are discussed.
Elastic and viscoelastic behavior of ethylene–propylene copolymers
Authors: De Candia F. , Vittoria V.
Published: April 2003

The viscoelastic behavior of an ethylene–propylene copolymer is analyzed. Two different vulcanization procedures were followed; in the first a binary mixture of initiator‐polymer was used, while in the second the polymer was diluted by a solvent. The networks thus obtained show a different viscoelastic behavior depending on the different vulcanization procedure used. Results, analyzed in terms of supramolecular organization being present in the amorphous material, give some important information about the molecular nature of the C2 coefficient of the Mooney‐Rivlin equation, and therefore about the well‐known deviations from the Gaussian theory shown by all rubber‐like networks.
Dynamic mechanical studies of four elastomeric fibers at low, intermediate, and high extensions
Authors: Hourston D. J. , Meredith R.
Published: April 2003

A dynamic mechanical study of four elastomeric threads has been made: the threads comprise natural rubber, nitrile rubber, Lycra, and Spanzelle. The dynamic loss modulus (E″) and the dynamic storage modulus (E′) were studied over a wide range of temperature (−110°C to 180°C) and the transitions were interpreted in the light of the chemical composition of the materials. The threads were investigated at 2%, 200%, and 400% static strain at a frequency of 110 Hz.
An equation of state for molten polymers
Authors: Rao Krishna , Griskey Richard G.
Published: April 2003

A simple, generalized equation of state has been developed for molten polymers. The equation yielded calculated pressure–volume–temperature data that deviated by 1% or less from experimentally determined data. The use of the equation requires only that the polymer's glass temperature and density at 25°C and 1 atm be known. Polymer glass temperatures can also be estimated with the equation.
On the origin of order‐disorder in drawn polyacrylonitrile
Authors: Hinrichsen Georg
Published: April 2003

Drawn polyacrylonitrile can be characterized only insufficiently with regard to its molecular and supermolecular structures which substantially determine the physical properties. This paper points out that the so‐called “superstructure” of polyacrylonitrile fibers can be cleared up after suitable thermooxidative treatment using x‐ray small‐angle scattering technique. The chemical reactions during the thermo‐oxidative treatment lead to a “self‐contrasting” effect so that the fibers as such are severely damaged yet information about the supermolecular structure can be obtained. The investigations show that changes in the course of fiber production (spinning, drawing, and annealing processes) affect alterations of the superstructure. The described method of investigation represents a so far unknown possibility for the purpose of detecting the supermolecular structure of drawn polyacrylonitrile.
Retention of antioxidants in polyethylene by silane coupling agents
Authors: Albarino R. V. , Schonhorn Harold
Published: April 2003

Antioxidant additives in polyethylene films have been shown to diffuse to the surface where they are subsequently lost, exposing the polymer to oxidation. Compatibility of antioxidants with polyethylene may be increased by use of silane coupling agents. In this study, three approaches to antioxidant modification are examined: (1) bonding antioxidant directly to silicon, (2) coupling the silane to an antioxidant hydroxyl function, and (3) dissolving antioxidants in silanes. All three approaches are shown to be effective in reducing antioxidant loss by diffusion.
ESR studies of free radicals in photo‐initiated graft polymerization reactions with cotton cellulose
Authors: Reine Alden H. , Hinojosa Oscar , Arthur Jett C.
Published: April 2003

Electron spin resonance (ESR) spectra of free‐radical intermediates formed during photo‐initiated graft polymerization reactions of acrylamide, methacrylamide, and diacetone acrylamide onto purified cotton cellulose were recorded. Purified cellulose was saturated with aqueous solutions of the vinyl monomers (0.5M) and then photolyzed under nitrogen by near‐ultraviolet light (3100–4100 Å, peak near 3500 Å) at −196° and 40°C. Other samples of cellulose were saturated with aqueous solutions of the monomers, dried, and then photolyzed at 40°C. In the absence of cellulose, either poorly resolved or no free‐radical spectra were generated on photolysis of the monomers. Photolysis of dried cellulose at 40°C and wet cellulose at −196°C initiated formation of a cellulosic radical that generated a singlet spectrum. Photolysis of wet cellulose at 40°C generated no ESR detectable radical; however, photolysis of wet cellulose that contained monomer at 40°C generated poorly resolved spectra. The ESR spectra of the propagating copolymer radicals recorded were poly(acrylamide), three lines; poly(methacrylamide), five lines; and poly(diacetone acrylamide), two lines (doublet).
Mechanical relaxations of poly(vinylidene fluoride) and some of its copolymers
Authors: Kalfoglou Nikos K. , Williams H. Leverne
Published: April 2003

The dynamic mechanical properties of poly(vinylidene fluoride) have been studied under isochronal conditions and the effect of thermal treatment examined. The results are compared with a product of different molecular weight distribution. The study also included the mechanical relaxation spectra of copolymers of vinylidene fluoride and chlorotrifluoroethylene at four compositions and four frequencies as a function of temperature. The thermodynamic parameters associated with the main relaxations were determined and the results discussed on the basis of available information on the drgree of crystallinity, copolymer heterogeneity, and main chain flexibility.
Properties of carboxymethylated cotton prepared in nonaqueous media
Authors: Perrier Dorothy M. , Benerito Ruth R.
Published: April 2003

Mercerized cotton printcloth was converted to sodium cellulosates of various degrees of substitution by reaction with sodium methoxide in methanol. These sodium cellulosates were reacted with sodium monochloroacetate in dimethyl sulfoxide at room temperature. The sodium hydroxide pretreatment affected not only the yield of the sodium cellulosate but also the degree of conversion of cellulosate to carboxymethyl (CM) cellulose. The nonaqueously prepared CM cottons had fabric properties that differed from the properties of CM cottons prepared by conventional aqueous methods. By the nonaqueous method, CM cottons of increased capacity, or degree of substitution (D.S.), were obtained by a one‐treatment procedure. These CM cottons in the sodium salt or acid form were insoluble in water and in 23% NaOH. Those of D.S. of about 0.3, when in the acid form, possessed improved wrinkle recovery angles. The salt form of CM cotton acts as a built‐in catalyst for the reactions of cotton with methylolated ureas such as dimethylolurea (DMU) and dimethylolethyleneurea (DMEU). However, only DMU was effective in imparting improved conditioned and wet wrinkle recovery to CM cotton. Initial replacement of Na+ ions of CM cotton by H+ was easily accomplished. After replacement of approximately half of the Na+ ions, it was more difficult to replace the remaining half of Na+ from CM cottons that had been prepared in nonaqueous media. Affinity of carboxylate ions in CM cottons prepared nonaqueously for cations did not decrease with size of cation even though affinity for H+ ions was greatest.
Flow properties of aqueous solution of methylcellulose
Authors: Amari Takeshi , Nakamura Matao
Published: April 2003

Flow properties of aqueous solution of methylcellulose, especially nonlinear viscoelasticity, were investigated. The peculiar flow properties of the aqueous solution of methylcellulose were compared with the existing theories of non‐Newtonian viscosity of concentrated polymer solutions and the experimental results obtained for the aqueous solution of sodium alginate which behaves as polyelectrolyte in solution. The characteristic time for the formation of entanglement couplings between molecular chains was mainly examined. To investigate the elastic behavior under steady‐shear flow, normal stress difference was measured with a coaxial cylinder apparatus, and extinction angles were determined with a flow birefringence apparatus. The values of normal stress difference obtained by the mechanical and the optical methods coincided with each other. For the aqueous solution of methylcellulose as reported for solutions of nonpolar polymers, the relation between normal stress difference and shear stress was represented by a single curve irrespective of temperature and concentration. Non‐Hooken behavior was observed for the relation between recoverable shear and shear stress and attributed to the strong intermolecular interactions and the stretching‐out effect of structural networks.
Mechanism of stabilization of poly(vinyl chloride). I. The cleavage of organotin compounds by aqueous hydrochloric acid
Authors: Rockett B. W. , Hadlington M. , Poyner W. R.
Published: April 2003

A number of organotin compounds with the general formula RnSnY4‐n where R = alkyl and aryl, Y = thiolate, carbothiolate, and carboxylate, and n = 0, 1, 2, 3 were cleaved with aqueous hydrochloric acid to give the corresponding organotin chlorides and thiols, carbothiolic acids or carboxylic acids. The organotion salts were also evaluated as thermal stabilizers for PVC, and their efficiency was compared with the nature of the aqueous acid cleavage products.1
Physicochemical studies of poly(hexene‐1). III. Application of dilute solution theories
Authors: Lin F. C. , Stivala S. S. , Biesenberger J. A.
Published: April 2003

Experimental data on dilute solutions of poly(hexene‐1), obtained from viscosity, osmometry, and light scattering in various solvents, previously reported, were treated and compared with various hydrodynamic theories of linear polymers. It was found that poly(hexene‐1) can best be described by the model of Flory‐Fox. Furthermore, the data were found to conform to the treatment of Kinsinger and Ballard for nonpolar polymers in the α‐olefin series in the unperturbed state.
Molecular weights from fractionation data by a simplified log‐normal treatment
Authors: Reich Leo , Stivala S. S.
Published: April 2003

A simplified procedure is presented to estimate the two adjustable parameters in a lognormal distribution function. From values of these parameters, the weight distribution function, W(M), as well as various molecular weight averages can be calculated. The method was applied to fractionation data selected at random for several polymers. The agreement between calculated and reported values appears to be good.
Studies on tack of pressure‐sensitive adhesive tapes: On the relationship between pressure‐sensitive adhesion and surface energy of adherends
Authors: Toyama Mitsuo , Ito Toshio , Nukatsuka Hiroshi , Ikeda Masamichi
Published: April 2003

The relationship between wetting and pressure‐sensitive adhesion was studied using an adhesive composed of poly(butyl acrylate) and various adherends of different surface tension. The amount of adhesive deposit was determined quantitatively by tracer technique although the unbonding process was apparently observed as interface failure. The adhesive force and amount of deposit were both dependent on the critical surface tension of the adherends. Maximum tack value and contamination were observed with adherends whose critical surface tension was close to that but a little higher than that of the adhesive. The adhesive force obtained was lower than cohesive strength of adhesive. From this evidence, a mechanism for pressure‐sensitive adhesion was discussed: the bond breaks in the addesive mass around the very minute spots where interaction is at work between adhesive and adherend. Inasmuch as the density of the minute spots per unit area depends on the surface tension, the adhesive force also depends on the surface tension.
Glass transition temperatures of poly(alkyl α‐cyanoacrylates)
Authors: Kulkarni R. K. , Porter H. J. , Leonard F.
Published: April 2003

The glass transition temperatures of the poly(alkyl α‐cyanocrylates) were determined by the dilatometric technique, and some of the values were checked by differential thermal analysis. The data indicate that the Tg's appear to decrease with increase in the size of the alkyl group, for a given molecular weight range. It was also found that the Tg of poly(methyl or butyl α‐cyanoacrylate) increased with molecular weight. All cyanoacrylates, excepting methyl and ethyl esters, formed only low molecular weight polymers in aqueous surroundings. Therefore, they have characteristic low glass transition temperatures, causing coalescence at low temperatures.
Influence of the dynamic stress intensity factor on cyclic crack propagation in polymers
Authors: Radon J. C.
Published: April 2003

A relationship of the form

developed for the evaluation of cyclic crack propagation in tensile/tensile fatigue was used to investigate the effects of frequency on fatigue crack growth. In order to establish the correlation between stress intensity K and dK/dt at 21°C, dynamic fracture toughness tests were performed on a range of polymers. It was shown that, in general, fracture toughness increased with the strain rate applied. Consequently, a decreasing trend in the crack growth rate was observed in the fatigue tests performed at higher frequencies. The occurrence of other localized peaks of fracture toughness recorded at various temperatures and strain rates is described. The fractography of fatigue surfaces is also discussed.
On the thermal degradation of poly(vinyl chloride). II. The effect of atmosphere
Authors: Abbås Kent B. , Sörvik Erling M.
Published: April 2003

The early stages of the thermal degradation of PVC were studied. Two commercial, suspension‐polymerized resins were thermally treated at different temperatures and oxygen contents. Dehydrochlorination kinetics were followed by conductometric measurements and the formation of polyene sequences by ultraviolet‐visible spectroscopy. Crosslinking and chain scission were followed by gel chromatography (GPC) and viscometry. No chain scission was observed in nitrogen atmosphere and no crosslinking in oxygen. Degradation in air proceeded by both reactions. The rate of dehydrochlorination for one of the investigated polymers increased linearly with the logarithm of the oxygen pressure. In nitrogen, an increasing degradation temperature was found to give both an increasing crosslinking and less discoloration. In oxygen, chain scission reactions showed a slight temperature dependence. The temperature effect on the discolorations was similar to that in nitrogen. The main difference between the investigated resins was the amount of internal doubled bonds in the original polymers, the ratio being 2:1. The higher amount resulted in a higher rate of dehydrochlorination, a larger extent of chain scission in oxygen, and a lower extent of crosslinking in nitrogen. Both in oxygen and nitrogen, the obtained results are consistent with allylic mechanisms. In nitrogen, the polyene formation supposedly proceeds by a unimolecular reaction and crosslinking by an intermolecular nonradical dehydrochlorination. In oxygen, radical reactions are superposed and may lead to chain rupture via β‐scissions of alkoxy radicals.
The effect of melt history, pressure, and crystallization temperature on spherulite size in bulk isotactic polypropylene
Authors: Reinshagen J. H. , Dunlap R. W.
Published: April 2003

Melt history, pressure, and crystallization temperature are three variables that may be used to vary spherulite size in polymer systems. In this study, bulk polypropylene samples were given various melt treatments and then isothermally crystallized under constant pressure. Spherulite size was found to increase with increasing severity (i.e., increased temperature or time at temperature) of melt treatment, explained by the thermal deactivation of nucleation sites. Spherulite size also increases with increasing crystallization temperature, owing to a smaller driving force for nucleation and the deactivation of increasing numbers of nuclei at higher crystallization temperatures. An analogous effect of pressure was also found, and a simple model to compare increased pressure and decreased crystallization temperature was derived.