摘要:

AbstractFlow irregularities have been visually observed in solutions of polyacrylamide of high molecular weight on shear in a cone‐and‐plate rheometry (gap angle 2.3°). This anomalous flow was found to depend on molecular weight, concentration, and solvent. The onset of flow irregularities were generally at shear rates<5 sec−1. A dimensional analysis shows that the elastic component of the fluid is responsible for the anomalous flow. The onset of flow irregularities has been predicted from measurements of recoverable strain as a function of shear

ISSN:0021-8995    

DOI:10.1002/app.1979.070230401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractPoly(tetrafluoroethylene) (PTFE) of high molecular weight, 4.5 × 107, was incidentally obtained at earlier study of an emulsifier‐free emulsion polymerization of tetrafluoroethylene by radiation. In order to clarify this phenomenon, the effects of additives, in particular radical scavengers, on the molecular weight of PTFE and its polymerization behavior were studied. It was found that the molecular weight of PTFE is increased by the addition of hydroquinone, benzoquinone, α‐pinene,dl‐limonene, and ethylenediamine but is decreased by oxygen and triethylamine. A PTFE latex with molecular weight higher than 2 × 107was obtained in the presence of hydroquinone. It is concluded that additives such as hydroquinone and benzoquinone, which rapidly scavenge the primary radicals (OH·, H·, andeaq−) in the aqueous phase but not the growing polymer radicals in PTFE particles, are most effective in increasing the mole

ISSN:0021-8995    

DOI:10.1002/app.1979.070230402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractThe elastic properties of ethylene–propylene and ethylene–vinyl acetate copolymers crosslinked to different degrees were studied. A correction of the front factor with respect to temperature has been proposed for calculation of the concentration of network chains from shear modulusG. Deviations from the Gaussian approximation of the dependence of force on deformation were evalua

ISSN:0021-8995    

DOI:10.1002/app.1979.070230403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractThe thermoelastic properties of ethylene–propylene and ethylene–vinyl acetate copolymers crosslinked to different degrees were studied. An equation was proposed for calculating the relative contribution of the internal energy,fU/f, from the temperature dependence of shear modulusG. Analysis of a relation for calculatingfU/fderived on the basis of the Mooney‐Rivlin equation was

ISSN:0021-8995    

DOI:10.1002/app.1979.070230404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractThe plasma polymerization of tetrafluoroethylene in an inductively coupled radio frequency glow discharge, using a flow system, was studied. A simple long tube reactor, with the coupling coil placed at the middle of the tube and gas entrance and exit at the respective ends, was used. Deposition rates and the chemical nature of the polymer (as revealed by ESCA spectra and surface energy studies) are obtained as a function of location in the reactor tube with respect to the coupling coil and of applied energy per unit mass of tetrafluoroethylene (W/FM). It was found that a fluorinepoor polymer, containing considerable carbon–oxygen bonds (after contact with air), is obtained at all locations at highW/FM. When a lowW/FMis utilized, such a fluorine‐poor polymer is also obtained at locations downstream from the coupling coil (the location of the highest energy density) in the reactor. In the latter case a fluorine‐rich polymer containing very little oxygen is formed upstream from the coil. The polymer deposition rate distribution is also considerably broader in a highW/FMplasma than when lowW/FMis used. These results are in agreement with earlier studies indicating that fluorine abstraction and decomposition due to fluorine etching occur when the energy density, as expressed byW/FM, is

ISSN:0021-8995    

DOI:10.1002/app.1979.070230405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractA fundamental study of bubble morphology development and apparent rheological properties in foam extrusion is reported. The influence of melt temperature, die length/diameter ratio, and blowing agent level on the morphology are considered. Measurements of the influence of blowing agent on viscosity, extrudate swell, and end‐pressure losses are described. The viscosity is reduced, but extrudate swell is increased. End‐pressure losses were found to become very large relative to the die wall shear stress at low extrusion rates. These results were interpreted in terms of bubble development. The filling of molds by foaming melts was observed and is descri

ISSN:0021-8995    

DOI:10.1002/app.1979.070230406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractDried ground formaldehyde‐treated peanut skins, white ash bark, and So. Wisconsin red maple bark are efficient substrates for removal of many heavy metal ions from waste streams, but possible interference by common light metal cations has never been determined. The influence of Ca2+, Mg2+, or Na+on the removal of the heavy metal ions Pb2+, Cu2+, Cd2+, and Zn2+by the above substrates was studied in both batch and packed‐column experiments. It was found that Pb2+and Cu2+were minimally affected by the presence of these light metal ions in solution, while the uptake of Cd2+and Zn2+was significantly reduced. Calcium ion produced the greatest effect of the light metals tes

ISSN:0021-8995    

DOI:10.1002/app.1979.070230407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractThe effect of different postcure times on the fracture properties and morphology of an epoxy resin was studied. The fracture energy for crack initiation and arrest was calculated for each sample and plotted as a function of the postcure time. Nodules (25–35 nm in diameter) were observed on all fracture surfaces. Of considerable interest was the alignment of nodules in the direction of crack propagation. Longer postcure times are thought to alter the fracture energy by causing additional crosslinking in the internodular matri

ISSN:0021-8995    

DOI:10.1002/app.1979.070230408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractDirect injection enthalpimetry (DIE) with improved sensitivity constitutes a reproducible method for terminal OH group determination in telechelic oligomers. However, it requires calibration for each individual type of telechelic. Inverse gas chromatography (IGC) can also be applied to determine endgroups of butadiene oligomers using polar probe molecules which do not interact with the polymer backbone.

ISSN:0021-8995    

DOI:10.1002/app.1979.070230409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractPressure–volume–temperature relationships of three low‐density polyethylenes are reported in the temperature range of 30°–225°C and in the pressure range of 0–2000 kg/cm2. The same materials had previously been studied by the IUPAC Working Party on Structure and Properties of Commercial Polymers with regard to basic characterization, melt rheology, processing, and end use properties. They were found to be remarkably equal in basic parameters and in some of the melt rheology, but differences among the three samples were found in other rheological properties and in the processing and end use properties of blown film. We find the PVT relationships of these three samples to be practically identical. A numerical equation of state based on the Tait equation is established. It reproduces the measured specific volume data of the melts to better than

ISSN:0021-8995    

DOI:10.1002/app.1979.070230410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY