摘要:

AbstractPolyethylene and starch–polyethylene composite films were exposed outdoors in the straw‐line of a marsh and in sea water on flow‐through seatables in the laboratory. The deterioration of these films following exposure was measured by determining changes in tensile properties, weight loss, starch loss, and carbonyl content of the sheet plastic films. Low rates of deterioration were observed for control and starch–polyethylene composite films submerged in sea water. In contrast, both starch–polyethylene composite and control polyethylene films rapidly deteriorated during exposure in the strawline of a marsh. Differences in the observed rate of deterioration of the films placed in the exposure sites is attributed primarily to photodegradation of the films placed in the strawline of a marsh. © 1993 John Wiley

ISSN:0021-8995    

DOI:10.1002/app.1993.070481201

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

年代:1993

数据来源: WILEY

摘要:

AbstractUnder proper conditions,in situpolymerizations of acrylic acid monomer solutions were performed within the microporous structures of a hydrophobic membrane, Celgard ® 2500. poly(acrylic acid) modified pores have been characterized to be permanently wettable by aqueous solutions, to be capable of gelling water to withstand increased transmembrane pressure gradients, and also to possess a higher transmembrane electrical resistance. In cases of less concentrated acrylic acid monomer solutions, a cross‐linker was employed to facilitate polymer permanency within the infrastructure of the hydrophobic membranes. © 1993 John Wiley&Sons,

ISSN:0021-8995    

DOI:10.1002/app.1993.070481202

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe concentration and separation of some metallic ions have been achieved by complexing these species with suitable macromolecules or with water‐soluble polymers in ultrafiltration. The effect of water‐soluble poly(vinyl alcohol) (PVA) on the concentration and separation of Cu2+, Ni2+, and Fe3+ions have been investigated by using EC‐PEG4000 alloy membranes in ultrafiltration experiments. The water permeability of the membranes has been measured at various pressures. The permeability of these membranes for metal ions, however, has been recorded at constant pressure but at different pH values. The highest water‐permeable membrane is also permeable for Cu2+and Ni2+, but it shows a considerable retention for Fe3+, probably as a result of the hydrolysis of Fe3+. The retentions of metallic ions and metallic ion‐PVA couples have been determined at constant pressure but varying pH and polymer concentration values. It has been shown that Fe3+/Ni2+pairs can well be separated by using PVA. © 1993 John Wiley

ISSN:0021-8995    

DOI:10.1002/app.1993.070481203

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

年代:1993

数据来源: WILEY

摘要:

AbstractThree series of novel polyurethane elastomers containing phenolphthalein as chain extenders were synthesized. The structure of the polyurethane was analyzed using IR and wide‐angle X‐ray diffraction studies. Tensile strength and percentage of elongation of all the series of polymers were studied. Thermal decomposition was studied using differential scanning calorimetry. © 1993 John Wiley&Sons,

ISSN:0021-8995    

DOI:10.1002/app.1993.070481204

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

年代:1993

数据来源: WILEY

摘要:

AbstractIn this study, three popular rheological models, which fit adequately well to viscosity data of polymeric materials, are chosen for making a comparative assessment of their applicability to practical data. The resulting nonlinear equations of the three models are solved by using Levenberg Marquardt's algorithm. The assessment of their applicability to practical viscosity data of 66 solutions of two resins in 11 solvent systems and reported data of other polymers has been analyzed. The Carreau and Ellis models have yielded unique global estimates for various rheological parameters, whereas the Cross model yielded local solutions. However, both Carreau and Cross models yielded parameter estimates with low overall residual error. The three models are found to have good applicability to viscosity data of resin solutions in good and moderate solvents; however, some deviation is observed when they are tested for solvents in which the resin has poor solubility. © 1993 John Wiley&Sons, Inc

ISSN:0021-8995    

DOI:10.1002/app.1993.070481205

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

年代:1993

数据来源: WILEY

摘要:

AbstractAcrylic acid and diethyleneglycol–dimethacrylate are grafted onto 25μm low‐density and 130μm high‐density polyethylene previously peroxidized by irradiation in air under the electron beams of an accelerator. Mohr's salt and methylene blue are used to prevent monomer homopolymerization. It is shown that sulfuric acid and Mohr's salt, respectively, enhance acrylic acid and diethylene glycol–dimethacrylate grafting. When they are combined, the influence of the monomer content on grafting kinetics is studied. Monomer content is determined by exchange capacity measurements. © 1993 John Wiley

ISSN:0021-8995    

DOI:10.1002/app.1993.070481206

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

年代:1993

数据来源: WILEY

摘要:

AbstractWe give a survey on mechanically induced emission phenomena (acoustic emission [AE], neutral particle emission [NE], electron and charged particle emission [EE/PIE], radio wave emission [RE] of polymers and briefly summarize these effects in unfilled and glass‐fiber‐reinforced bisphenol‐A‐polycarbonate. A general treatment of the photon emission kinetics in terms of analysis and description, using a convolution function, is proposed. The kinetics obey a power law decay in time. By examining a model mechanism for the interfacial failure of the composite, i.e., by peeling of glass/polymer laminates, we show that the origin of the photon emission is the polycarbonate matrix after cleavage of the glass/polymer interface. Spectral characteristics of mechanically induced luminescence of glass‐filled polycarbonate and of the peeling spectra of the model system of glass/polycarbonate laminates are discussed. Different brands of polycarbonate yield identical spectra. Spectra recorded during peeling in vacuum are very similar to those recorded during deformation of the composite. Polarized fluorescence spectroscopy and electronbeam luminescence were used to obtain further information about the intrinsic polycarbonate–chromophores that are available for mechanically induced photon emission. © 1993 John Wil

ISSN:0021-8995    

DOI:10.1002/app.1993.070481207

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

年代:1993

数据来源: WILEY

摘要:

AbstractLow resorcinol content cold‐setting urea–resorcinol–formaldehyde (URF) resins were prepared. Most of these adhesives had water‐resistant properties, whereas some also presented weather‐ and boil‐proof adhesive characteristics and performance. URF resins of acceptable adhesive performance were also prepared by inducing branching by introducing a certain amount of resorcinol or of polyflavonoid mimosa tannin extract as a branching unit. Resorcinol content as low as 12.7 and 12.15% on total liquid resin were obtained by this method while still maintaining adhesive performance and water‐resistant properties. © 1993 John W

ISSN:0021-8995    

DOI:10.1002/app.1993.070481208

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

年代:1993

数据来源: WILEY

摘要:

AbstractFracture surface morphology and orientation distribution in the extrusion‐molded sheets of a thermotropic liquid crystalline copolyester amide were investigated by scanning electron microscopy (SEM), wide‐angle X‐ray diffraction (WAXD), and polarized Fourier transform infrared (FTIR) microspectroscopy. The layerlike morphology consisting of two outer layers and a central layer between them was observed on the fracture surface. The microscopic orientation functions in the extrusion‐molded sheets were evaluated from the polarized FTIR microspectra that were measured in the microscopic domain 40 μm wide using a redundantly apertured infrared microscope. The microscopic orientation function in the outer layer was shown to be higher than that in the central layer. The effects of the draw‐down ratio and extrusion temperature on the orientation distribution and the layerlike morphology are discussed. © 1993 John Wile

ISSN:0021-8995    

DOI:10.1002/app.1993.070481209

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

年代:1993

数据来源: WILEY

摘要:

AbstractPressure‐normalized gas fluxes for defect‐free integral‐asymmetric membranes prepared according to a dry/wet phase inversion process were measured as a function of temperature and pressure and compared to measurements on thick isotropic films. Asymmetric membranes were prepared from polysulfone, polycarbonate, and poly(ester carbonate). The activation energies of permeation for O2and N2in the range of 25–55°C were higher for the asymmetric polysulfone membranes than for a thick isotropic film. O2/N2selectivities of the asymmetric membranes are higher than those for isotropic films. The asymmetric membranes did not show the typical dualmode behavior for the CO2flux as a function of pressure as determined for thick films. Differences in the free volume and its distribution in the ultrathin skin layer of the asymmetric membranes compared to isotropic films may be responsible for these results. © 1993 John Wiley&

ISSN:0021-8995    

DOI:10.1002/app.1993.070481210

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

年代:1993

数据来源: WILEY