bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of carboxymethylated cotton prepared in nonaqueous media
Authors: Perrier Dorothy M. , Benerito Ruth R. 
Published: April 2003

AbstractMercerized 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

AbstractFlow 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

AbstractA 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

AbstractExperimental 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

AbstractA 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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractMelt 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.
Reverse osmosis separation of organic acids in aqueous solutions using porous cellulose acetate membranes
Authors: Matsuura Takeshi , Sourirajan S. 
Published: April 2003

AbstractReverse osmosis data obtained using porous cellulose acetate membranes and aqueous feed solutions involving one of 22 monocarboxylic acids, seven dicarboxylic acids, and four hydroxycarboxylic acids have been analyzed. The operating pressure used was 250 psig in all cases, and the solute concentration used was ∼100 ppm in most cases. The results yield the following physicochemical criteria for preferential sorption at the membrane–solution interface with respect to the un‐ionized acid. At pKa = 4.2 (for monocarboxylic acids), or Taft number (σ*) = 0.6 or Hammett number (σ) = 0, neither the un‐ionized acid nor water is preferentially sorbed at the membrane–solution interface; at pKa < 4.2 (for monocarboxylic acids) or σ* > 0.6 or σ > 0, the un‐ionized acid is preferentially sorbed at the membrane–solution interface. For practical purposes, preferential sorption of water at the membrane–solution interface may be considered negligible in the σ* region of 0 to 0.6. The results also show that the criterion of acidity of the molecule governing the extent of its repulsion or attraction at the membrane–solution interface is valid for both ionized and un‐ionized acid. Further, when the acid molecule contains three or more straight‐chain carbon atoms not associated with a COOH group, the nonpolar character of the molecule also affects its separation in reverse osmosis.
Estimation of molecular weight distribution parameters for free‐radical polymerization
Authors: Reich Leo , Stivala S. S. 
Published: April 2003

AbstractA method is described which allows the precise estimation of molecular weight distribution parameters p and A which pertain to free‐radical polymerizations. Thus, expressions are developed which allow the estimation of (1 − p) by means of a programmable calculator using molecular weight distribution data derived from GPC. Values of A may subsequently be calculated by means of a plot of one of the expressions given. Values of (1 − p) and A obtained in this paper were checked using theoretical values as well as by a comparison between calculated and observed values. The agreement between calculated and theoretical or experimental values indicates that the method presented for the estimation of (1 − p) and A is both reliable and relatively rapid. Previously reported methods for the estimation of (1 − p) and A have involved curve‐fitting trial calculations as well as more precise interpolation procedures. However, the latter are based on single‐peak maximum values.
Viscosity–temperature relationships for cellulose acetate–acetone solutions
Authors: Johnston H. Krik , Sourirajan S. 
Published: April 2003

AbstractViscosity measurements were made for dilute solutions of three grades of cellulose acetate (acetyl content 39.8%, molecular weight M̄v30270 to 46250) in acetone in the temperaturetrange of 10° to 35°C. The data satisfied the Mark‐Houwink equation, [η] =KM̄, where [η] = limiting viscosity number andKand α are Mark‐Houwink constants. The values of [η] and α decreased with increase in temperature, and straight‐line correlations were obtained for −d[η]/dtversus M̄vand log η versus 1/T(absolute temperature). The results are discussed in terms of solution properties of cellulose acetate in acetone and their possible relevance to reverse osmosis membrane science.
Preparation of cellulose triacetate and cellulose tricarbanilate by nondegradative methods
Authors: Hall David M. , Horne James R. 
Published: April 2003

AbstractA method for obtaining triacetate having a D.S. of 3.0 has been obtained by acetylating the cellulose with acetic anhydride–pyridine reagent containing a catalytic amount of acetyl chloride. The process is rapid and nondegradative. Cellulose tricarbanilate can be prepared without recourse to pyridine solutions by using dimethylformamide (DMF) as solvent and triethylenediamine (1,4‐diazobicyclo[2.2.2]octane) as catalyst. The DMF solution of the cellulose tricarbanilate can be cast directly into films or the polymer easily recovered owing to the solubility of the reaction solvent and impurities in water.
The mechanism of carrier dyeing
Authors: Ingamells W. , Peters R. H. , Thornton S. R. 
Published: April 2003

AbstractThe accelerated rate of diffusion of disperse dyes into synthetic fibers caused by various dyebath additives (“carriers”) has been correlated with their plasticizing action. The rate of change in length of Acrilan filaments with temperature under dyebath conditions enabled the effects of the carrier on the Tg of the filaments to be measured, and the results for different concentrations of carrier at one temperature could be superimposed on a common curve by employing suitable shift factors. The shift factors, as well as the variations of the diffusion coefficients of dyes with temperature and carrier concentration, both matched a WLF relationship, confirming that the dyeing process is controlled by the segmental mobility of the polymer. Indirect experimental evidence suggests that the same relation will describe the effect of carriers on the dyeing of poly(ethylene terephthalate) substrates with disperse dyes.
Shear degradation of water‐soluble polymers. I. Degradation of polyacrylamide in a high‐shear couette viscometer
Authors: Abdel‐Alim A. H. , Hamielec A. E. 
Published: April 2003

AbstractThis manuscript reports an experimental investigation of the mechanical degradation of polyacrylamide in aqueous solution using a high‐shear couette viscometer. Equilibrium molecular weight distributions (MWD) at various shear stresses were measured by gel permeation chromatography. Degradation data indicate that the MWD becomes narrower at higher shear stresses, in general agreement with Bueche's midpoint break theory. An empirical correlation of the critical molecular weight and degrading shear stress is presented. It has the form

where Mc is the critical molecular weight and τ is the degrading shear stress in dynes/cm2.
Poly(vinyl alcohol) hydrogels. Formation by electron beam irradiation of aqueous solutions and subsequent crystallization
Authors: Bray James C. , Merrill Edward W. 
Published: April 2003

AbstractAqueous solutions of poly(vinyl alcohol) were submitted to varying doses of electron beam irradiation. By modification of the classical Flory‐Huggins equations appropriate to the initial state of solution of the polymer, the molecular weight between crosslinks, Mc, was calculated as a function of radiation dose, initial polymer concentration, and temperature. Following crosslinking in the solution state, crystallization was induced by dehydrating the network at temperatures above 90°C. Following dehydration, the polymer network was reequilibrated with water and its tensile properties compared with identically prepared hydrogels not subjected to crystallization by dehydration. Greatly enhanced values of ultimate tensile strength and resistance to tear result from the treatment producing crystallization, compared with those of the crosslinked but not previously dehydrated gels.
The influence of carbon black on the extrusion characteristics and rheological properties of elastomers: Polybutadiene and butadiene–styrene copolymer
Authors: White James L. , Crowder Jerry W. 
Published: April 2003

AbstractAn experimental study of the influence of carbon black loading, particle size, and structure on the extrusion characteristics of polybutadiene and butadiene–styrene copolymer synthetic rubber is described. The development of extrudate distortion and its mechanisms are considered. The viscosity and die swell have been related to black loading, particle size, and structure. Generally, it is found that black surface area and structure acts to increase viscosity and decrease elastic memory. This situation is analyzed in terms of the theory of nonlinear viscoelasticity. Two mechanistic theories are described which may explain this behavior. One theory is based on the continuum mechanics analysis of suspensions of particles in viscoelastic media. The rheological behavior of the black compounds is explained in terms of the increased severity of deformation in the polymer matrix surrounding the particle agglomerates. The second theory is based on the view of an entanglement network containing black particles. Polymer chains may be adsorbed onto the surface giving rise to increased entanglement densities.
Microcapillary oxidation‐reduction polymers
Authors: Hamilton William J. , Krause Kenneth J. , Wagner Herman B. 
Published: April 2003

Abstract“Replica gel” polymers, characterized by their extremely high specific surface area, have not previously been prepared in “redox” form. Some illustrative syntheses are described, and the capability of these materials to oxidize acetic acid and to epoxidize oleic acid and cyclohexene is demonstrated.
An empirical model for viscosity of filled and plasticized elastomer compounds
Authors: Derringer George C. 
Published: April 2003

AbstractAn empirical model is proposed for viscosity of elastomers containing one or more fillers and/or one or more plasticizers. Only one coefficient for each filler and plasticizer is required, and the coefficients themselves are viewed as basic filler and plasticizer characteristics. The model has found wide applicability to many elastomer systems.
Interaction of gases with ablative composites. II. Water
Authors: Honeycutt R. H. , Wightman J. P. 
Published: April 2003

AbstractThe sorption of water vapor on two heat shield composites SLA‐561 and SLA‐561V and the SLA components was measured over the pressure range of 10−3 to 10 torr and at 25°, 30°, and 35°C. The sorption of water vapor by both the composites and the components varied directly with pressure and equilibrium was attained typically within 30 min. The sorption of water by SLA‐561V, phenolic spheres, and silica fibers varied inversely with temperature. The mechanism proposed for the interaction of water vapor with the SLA composites was a combination of absorption and adsorption.
Structural analysis of phenolic resole resins
Authors: King P. W. , Mitchell R. H. , Westwood A. R. 
Published: April 2003

AbstractThe chemical structure and cure characteristics of a group of phenolic resole resins were studied by means of three major analytical techniques. In particular, the effects on structure and reactivity of formaldehyde/phenol ratio and the type of reaction catalyst used were studied. Gel permeation chromatography was used to determine resin molecular weight distributions, and NMR, to determine chemical structural features. In this connection a selective oxidation procedure, converting free methylol groups to adehydes, has allowed unambiguous determination of methylene ether bridge structures to be made from the NMR data. The F/P ratio in a resole largely determines the type of molecular structures which are formed. However, triethylamine as a catalysts tends to favor methylene ether bridge formation, whereas sodium hydroxide favors methylene bridges. The rate and direction of subsequent thermal cure of the resoles prepared is shown by differential scanning calorimetry to depend markedly on the type of catalyst present during the curing stage. The DSC curing curves are interpreted in the light of the structural information provided by NMR.
Rapid assessment of weathering stability from exposure of polymer films. II. The effectiveness of different regions of the solar spectrum in degrading an ABS terpolymer
Authors: Davis A. , Gordon D. 
Published: April 2003

AbstractA simple and rapid method has been developed to determine the relative effectiveness of the different regions of the solar spectrum in weathering a polymer. The method is based on measuring the rate of degradation of the polymer in film form, exposed outdoors under a range of materials which transmit different amounts of solar UV. The stability of an unpigmented ABS terpolymer has been examined using this method. It has been shown that the relatively small amount of solar radiation in the range of 295–340 nm accounts for 41% of the total degradation process. Longer wavelengths are shown to be progressively less effective; wavelengths greater than 450 nm (which account for nearly 90% of the total energy of the solar spectrum) contribute less than 5% to the degradation process.