bluuebunny/crossref_metadata_2025_split huggingface dataset:
A rheological study of the low molecular weight butyl polymer
Authors: Drexler Leonard H. 
Published: April 2003

AbstractA rheological study has been performed to characterize the low molecular weight butyl polymers using a couette coni‐cylindrical viscometer. The bulk viscosity was determined as a function of temperature, weight‐average molecular weight, viscosity‐average molecular weight, and shear rate. The temperature dependence of the viscosity, while adequately represented by the Williams, Landel, and Ferry equation, is best described by an Arrhenius equation for the temperature range investigated. The viscosity is shown to vary with the 3.5th power of the weight‐average molecular weight above a critical molecular weight and to the 1st power below this molecular weight. Although the ratio of the weight‐average molecular weight to the number‐average molecular weight usually affects the flow properties of polymers, this was not true for the polymers investigated. The bulk viscosity was found to be independent of the molecular weight distribution for the temperature and shear rate range studied. It has been shown that a definite relationship exists between the bulk viscosity and the viscosity‐average molecular weight as determined by dilute solution viscosity. A mathematical model has been developed to relate these two parameters as a function of temperature and shear rate.
Time‐dependent effect of spherulite size on the tensile behavior of polypropylene
Authors: Remaly L. S. , Schultz J. M. 
Published: April 2003

AbstractThe mechanical behavior of isotactic polypropylene following primary crystallization is known to be dependent on the aging time (e.g., at room temperature). This aging time effect is believed to be related to a form of additional crystallization (sometimes called secondary crystallization). We show in the present work that the aging characteristics depend on spherulite size and that indeed the spherulite size effects reported by others very likely reflect chain rearrangements upon aging, rather than some property associated with the as‐crystallized material.
Poisson's ratio for rigid plastic foams
Authors: Rinde J. A. 
Published: April 2003

AbstractPoisson's ratio for several low‐density plastic foams has been determined in both tension and compression. For polystyrene bead foams and a polyurethane foam, Poisson's ratio is greater in tension than compression. In compression, Poisson's ratio is not linear, showing a larger value below the yield strain and a value near zero for high strains. For 0.05 and 0.10 g/cc polystyrene bead foam, Poisson's ratios are 1/3 in tension and 1/4 in compression below the yield strain; at higher strains, the value in compression is in the range 0.03–0.07.
Polymer fractionation by repeated extraction
Authors: Klein J. , Friedel H. 
Published: April 2003

AbstractAll current fractionation techniques—based on sol–gel equilibria—are characterized by a variation of the solvent power after each fractionation step in a discontinuous as well as in a continuous way. Overlapping of consecutive fractions is the consequence of this procedure. It can be shown that this overlapping can be diminished essentially by a multistage technique based on complete extraction at a given solvent power which then will be changed in discontinuous steps. As a further consequence, it is possible to obtain very homogeneous fractions of M̄w/M̄n < 1.03. A theoretical analysis of this technique on the basis of phase equilibrium data will be given, the results of which can be confirmed experimentally.
Dynamic young's and shear moduli of graphite fiber‐reinforced high‐temperature matrix resins
Authors: Dudek T. J. 
Published: April 2003

AbstractThe resonant frequencies of unidirectional graphite fiber‐reinforced polyimide (Skybond 703) and polyquinoxaline resin composite beams were determined. The Timoshenko beam theory was employed to compute both the longitudinal Young's modulus (E11) and the effective transverse‐longitudinal shear modulus (G12) from the set of resonant frequencies of the beams. E11, E22, and G12 were determined for a 64% by volume Modmor II‐reinforced polyimide (Skybound 703) composite, and E11 and G12 were determined for cured and postcured Modmor II‐reinforced polyquinoxaline (PQ) composites. Dynamic E11 and E22 results were found to agree with experimentally determined static flexural moduli. Voids present in these high‐temperature resin composites to an extent of 5–13% by volume appeared to lower the effective shear and longitudinal moduli of the composites.
Evaporation rate and equilibrium phase separation data in relation to casting conditions and performance of porous cellulose acetate reverse osmosis membranes
Authors: Kunst B. , Sourirajan S. 
Published: April 2003

AbstractQuantitative data on solvent evaporation rates and equilibrium phase separation compositions corresponding to different film casting conditions are given, and the results are discussed with reference to reverse osmosis data on membrane performance. A typical evaporation rate curve plotted on a semilog scale consists of an initial linear part from whose slope evaporation rate constants b have been determined. For a given casting solution composition and temperature, an optimum value of b exists for best membrane performance, and identical values of b result in same membrane performance. Treating the casting solution as a polymer–solvent–nonsolvent ternary system, the data on equilibrium phase separation compositions have been plotted in a triangular diagram for solution temperatures of −10°, 0°, and 24°C. The data indicate that even small changes in solution temperature can bring about significant changes in solution structure and hence membrane performance, and useful conclusions on solution structure can be drawn from such phase equilibrium diagrams. The data and correlations presented here offer a quantitative confirmation of the governing significance of the solution structure‐evaporation rate concept relating to the mechanism of phase separation and pore formation in the surface region during the process of making reverse osmosis membranes.
Thermal decomposition products of cellulose
Authors: Tsuchiya Yoshio , Sumi Kikuo 
Published: April 2003

AbstractUntreated and flame‐retardant‐treated cellulose were thermally decomposed under vacuum and the products were quantitatively analyzed by gas chromatography. An unidentified product at a retention index of 2270 (between 5‐methylfurfural and 5‐hydroxymethylfurfural), α‐ and β‐D‐glucose, and a group of “dimers” that have not been reported previously were found in this study. The identification of this unknown product should assist in studies on the thermal decomposition of cellulose and further the understanding of the mechanism of flame retardancy.
Solution viscosity–molecular weight relationship for polystyrene
Authors: Rogers Morris G. 
Published: April 2003

AbstractThe 10% solution viscosity has been used extensively as a measure of molecular weight for the commercial production of polystyrene. Recently, poor correlations have been observed between 10% solution viscosity and molecular weight as measured by gel permeation chromatography. Lowering the concentration improves the correlation. At 0.2%, the log–log plot of viscosity versus molecular weight becomes linear.
Sulfoalkylation of a polybenzimidazole with propanesultone
Authors: Jenöszita  , Marvel C. S. 
Published: April 2003

AbstractPoly‐2,2′‐(m‐phenylene)‐5,5′‐bisbenzimidazole has been alkylated with propanesultone to yield polymers which are readily dyed with basic dyes. Propanesultone has been used to convert cellulose, starch, phenolformaldehyde resin, and various vinyl copolymers into hydrophilic materials which dye readily or act as ion exchange resins.1–5 It seemed likely it would react with a polybenzimidazole to make the polymer more water absorptive and readily dyeable with basic dyes. Hence this work was undertaken.
Effect of mixing on melt flow properties of high‐density polyethylene
Authors: Hirata Sadao , Hasegawa Hiroshi , Kishimoto Akira 
Published: April 2003

AbstractAn investigation has been made into the effect of mixing by a screw extruder upon the molecular characteristics and the melt flow properties of high‐density polyethylene. The crosslinking between molecules predominates over the scission of a molecule at an early stage of mixing, but with further increase in the degree of mixing, this situation reverses itself to bring about the formation of branched polymers. Static flow and dynamic viscoelastic properties of molten high‐density polyethylene change considerably with increase in the degree of mixing. The apparent viscosity drops rather sharply after mixing. The dynamic properties for the original resin show smaller frequency dependence of the viscosity and larger dependence of the rigidity than those for extrudates. The relaxation spectra become broader with increase in mixing. These may mainly be due to the change of the molecular characteristics of high‐density polyethylene with mixing by an extruder.
Studies on nitroaniline–sulfuric acid compositions: Aphrogenic pyrostats
Authors: Poshkus A. C. , Parker J. A. 
Published: April 2003

AbstractNitroaniline‐sulfuric acid compositions, a source of a new class of aphrogenic pyrostats (intumescent fire‐quenching agents) have been studied. Thermogravimetric analysis of the compositions and their expansion products was carried out. The chemical compositions of the foams were determined, and considerable similarity was noted. Sulfur is present exclusively as sulfonic acid groups. Appreciable deamination occurs during expansion, particularly at higher acidic content. Sulfur dioxide and water are major gaseous constituents. Only 2‐ and 4‐nitroanilines can be converted into voluminous foams; they behave like difunctional monomers. 3‐Nitroaniline expands only slightly into brittle products; it acts like a trifunctional monomer.
Weathering of plasticized poly(vinyl chloride)
Authors: Dunn P. , Oldfield D. , Stacewicz R. H. 
Published: April 2003

AbstractA series of flexible plasticized poly(vinyl chloride) (PVC) compositions containing different organotin compounds and ultraviolet absorbers has been exposed for 4.5 years at four outdoor sites in Australia with widely differing climatic conditions. Loss of plasticizer by evaporation during the exposure was measured and an empirical correlation was found with the average daily maximum temperature at each site. The relative effectiveness of the organotin compounds and ultraviolet absorbers in preventing deterioration of the PVC was estimated by measuring the viscosity of the polymer after exposure. This method of assessment is compared with the results of mechanical tests on the specimens.
Functionality determination of hydroxyl–terminated butadiene prepolymers
Authors: Consaga John P. 
Published: April 2003

AbstractFunctionality of hydroxyl–terminated butadiene prepolymers (HTPB) was determined from gel point measurements as described by Strecker and French.2 Commercial HTPB samples had functionalities ranging from 1.9 to 2.6, with most of the material close to 2.0. In order to calculate functionality from gel point measurements, the hydroxyl content of the HTPB must be known. A method was developed which gave reproducible results. Curing agents used in the gel studies were viscous liquid poly‐functional isocyanates with functionalities of 2.00 and 2.50. An extensive study showed that no side reactions were occuring with the isocyanates at the temperatures employed. It is estimated that the precision of the method is ±0.80%. Functionality calculated by dividing molecular weight by equivalent weight results in lower values in all cases when compared to gel point measurements.
Adhesive bonding of polyethylene
Authors: Morris C. E. M. 
Published: April 2003

AbstractThe treatment of polyethylene film with aqueous ammonium peroxydisulfate solutions prior to adhesive bonding to aluminum has been studied. Such pretreatments resulted in the formation of adhesive joints of high strengths when bonded with a conventional epoxy adhesive. The effect on the tensile shear strength of adhesive joints of variations in the treatment time and temperature and the peroxydisulfate concentration has been examined. The use of certain catalysts for the reaction has also been studied. Tensile shear strengths at least as high as with other pretreatment methods have been obtained.
An investigation into the high temperature strength and reinforcement of natural rubber
Authors: Harwood J. A. C. , Payne A. R. , Whittaker R. E. 
Published: April 2003

AbstractThe failure criterion for amorphous polymers relating hysteresis at break with energy input to failure in tensile stress–strain tests was found to be obeyed only at very high or very low temperatures in natural rubber. Tensile results between about 80°C and 130°C show a high degree of scatter, and this behavior is attributed to the ability of natural rubber to crystallize at high strains. The modification of tensile properties by the addition of carbon black in natural rubber is also discussed and compared with published results from SBR. The effect of changing the degree of crosslinking on the failure properties in both dicumyl peroxide and sulfur‐cured vulcanizates of natural rubber is also considered. It is found that differences in failure properties can be accounted for by the use of a crosslinking parameter from simple rubber elasticity theory in some of the failure equations.
A new photoelastic method for evaluating durability of plastics
Authors: Ohishi Fujio 
Published: April 2003

AbstractThis work was undertaken to measure quantitatively the quality change and crack development caused by degradation of plastics with the new photoelastic scale (P scale) using split circular ring‐type specimens (C specimen). For an example, a polycarbonate specimen was used under various conditions—photodegradation, thermal degradation, solvent cracking, solvent action, and alkaline degradation. The results indicate that this method is useful for evaluating durability of plastics, and a merit of the method is to provide quick, convenient, nondestructive means of measurement with simple equipment. Besides, this C specimen is easily deflected by a spring plate with two holes. Therefore this method is also applicable to the investigation of effects of deformation on various degradations of plastics.
Energy absorption in polymeric foams. I. Prediction of impact behavior from instron data for foams with rate‐independent modulus
Authors: Meinecke Eberhard A. , Schwaber David M. 
Published: April 2003

AbstractThe processes of energy dissipation in polymeric foams are discussed. Theoretical considerations and experimental results show that impact behavior of foams with a rate independent modulus can accurately be predicted by Instron data.
The solubility of poly(vinylidene chloride) in solvent mixtures
Authors: Wessling Ritchie A. 
Published: April 2003

AbstractEffective solvents for poly(vinylidene chloride) (PVDC) were obtained by mixing a polar aprotic solvent with a less polar solvent of cyclic structure. The polar components included sulfoxides, N,N‐dialkylamides, and N‐alkyl lactams. The cyclic cosolvents included aliphatic and aromatic hydrocarbons, ketones, ethers, and thioethers. The problem of solubility of a crystalline polymer in a mixed solvent was analyzed by extending the Flory theory of melting point depression to three component mixtures. The results predict that favorable mixtures arise when at least one of the components interacts strongly with the polymer but is nearly incompatible with the cosolvent. This is in qualitative agreement with the observed behavior of PVDC.
An improved block osmometer used to determine the molecular weight distribution of commercial poly(vinyl chloride)
Authors: Hayduk W. , Kelly B. D. 
Published: April 2003

AbstractCommercial PVC was fractionated into five fractions by the incremental addition of a nonsolvent to the polymer solution. The number‐average molecular weights of the original sample and fractions were determined by osmometry. The weight‐average molecular weights of the sample and fractions were also determined by means of viscosity measurements and by the application of a Mark‐Houwink type of equation. From a knowledge of the polydispersity of each fraction and the assumption that the number distribution of molecular weights was Gaussian, the molecular weight distribution for the composite sample was determined. The block osmometer used incorporated most of the features found useful in earlier work to facilitate rapid and reliable osmotic pressure measurements. In addition, microvolume‐regulating valves were utilized in the capillary tube lines to permit an independent precise positioning of the interface level in either capillary.
Studies on tack of pressure‐sensitive adhesive tapes: On the surface contamination by adhesive mass after peeling
Authors: Toyama M. , Ito T. , Moriguchi H. 
Published: April 2003

AbstractThe presence of adhesive residue on the surface of various adherends after peeling has been confirmed using a tracer technique. Adhesive bonding is found to break by a cohesive mechanism, although the unbonding process seems apparently to be due to intersurface failure. This result supports the concept for adhesive bond breaking proposed in the preceding paper: The unbonding proceeds from the viscoelastic deformation of the adhesive mass around the wetted spots on the surface. As the number of spots in a unit area is controlled by surface energy, the tack value is dependent on the critical surface tension of the adherends.
Internal catalysis of reactions of activated vinyl compounds via tertiary amino substituents in cotton cellulose
Authors: Rowland Stanley P. , Brannan Mary Ann F. 
Published: April 2003

AbstractThe tertiary amino groups of 2‐diethylaminoethyl substituents in cotton cellulose have been found to be effective catalysts for reactions of activated vinyl compounds with cellulosic hydroxyl groups. These reactions proceed more slowly and to lesser extents at equilibrium than the corresponding reactions catalyzed by quaternary ammonium substituents. The crosslinking of cotton cellulose with divinyl sulfone is catalyzed by (C2H5)2NCH2CH2 substituents and by (C2H5)2NCH2CH(OH)CH2 substituents, with the development of moderate levels of wrinkle recovery. On the other hand, only the former substituents catalyze the reorganization of the crosslinkages during recure (160°C, 10 min), with substantial increases (40°) in wrinkle recovery angles. These same 2‐diethylaminoethyl substituents are effective in catalyzing the reorganization of crosslinkages from divinyl sulfone which are introduced into the cotton by conventional external catalysis (i.e., NaOH); this effectiveness can be overcome by the introduction of excessive crosslinkages into the cellulosic composition.
Separation of liquid mixtures by using polymer membranes. II. Permeation of aqueous alcohol solutions through cellophane and poly(vinyl alcohol)
Authors: Huang Robert Y. M. , Jarvis Neil R. 
Published: April 2003

AbstractThe permeation and separation characteristics of four different alcohol—water systems through cellophane and poly(vinyl alcohol) membranes were investigated. The homologous series of linear alcohols n‐propanol, ethanol, and methanol as well as isopropanol were studied. A specially designed permeation cell was used to study permeation rates at temperatures ranging from 30° to 50°C. The dependency of both permeation and separation on the molecular size and shape of the permeating species was discussed qualitatively. The temperature dependence of the permeation rate for both pure compounds and binary mixtures was expressed by Arrhenius‐type relationships. The rate was found to increase with increasing temperature while the separation decreased. Activation energies of 4–9 kcal/mole were calculated for alcohol—water solutions through cellophane, and of 8–15 kcal/through poly(vinyl alcohol). Departure of permeation rates from the ideal rates were discussed in terms of permeation “enhancement” or “depression.” These phenomena were explained in terms of both the plasticizing action of water and the “clustering” of water molecules within the polymer network.
Rheological interpretation of heat generation associated with fatigue of polycarbonate
Authors: Higuchi Masakazu , Imai Yasufumi 
Published: April 2003

AbstractTemperature change was measured of polycarbonate under monotonically increasing tensile and pulsating tensile loads. In the former case, the specimen temperature began to rise when an appreciable amount of viscoelastic strain was noticed on the stress—strain diagram. The rise, θv, could be formulated as a function of the viscoelastic strain, εv:

In fatigue tests, the average temperature began to rise immediately after the decrease due to the thermoelastic effect. The amount of the heat generation, σ, was nearly constant for each cycle throughout the fatigue process and has a relation to the fatigue life, Nf, (αa)·Nf = constant, where a is another adjustable constant. From a rheological aspect of dissipation energy, the equation is transformed to a relation between the viscoelastic strain and the fatigue life as εV1/2 · Nf = constant, which is similar to the one for metals given by Manson and Coffin.6 The temperature rise in the fatigue was also related to the viscoelastic strain. The relation is of the same form as for static tension but less by a factor of one order.
A boat‐casting technique for the preparation of very thin plastic films suitable for optical studies
Authors: Humphrey J. S. 
Published: April 2003

AbstractA meniscus coating technique utilizing a Teflon “boat” for dispensing a viscous solution of a polymer in a volatile solvent upon a suitable substrate provides very thin plastic films (>ca. 0.5 μm) which are usually of acceptable optical quality for spectrophotometric measurements.
Enhancing the permeation characteristics of polyethylene by membrane irradiation in the fully swollen state
Authors: Siegel Richard D. , Coughlin Robert W. 
Published: April 2003

AbstractFully swollen, low‐density polyethylene films were irradiated, vacuum dried, reswollen, and subsequently permeability tested using tritiated toluene and benzene as penetrants. The treatment improved the permeability of polyethylene up to 88%, with the enhancement strongly dependent on the choice of the irradiation solvent. These results suggest a potentially practical process for improving the performance of semipermeable membranes.