摘要:

AbstractAmorphous films of poly‐2‐vinylpyridine—I2complex have strong absorption over the entire visible spectrum. The photovoltaic properties of solar cells made from thick films of the polymer‐iodine complex deposited over a tin oxide layer have been studied. The conversion efficiency of white light into electricity is 5 × 10−2%. This transformation yield is obtained by combining a low open‐circuit voltage with a rather high short‐c

ISSN:0021-8995    

DOI:10.1002/app.1982.070270101

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

年代:1982

数据来源: WILEY

摘要:

AbstractApproximate analytic results for two problems involving the inflation of rubber inner tubes and tires are summarized with a view to prompting a comparison of the theory with experimental results. The problems considered are the uniform inflation by internal pressure of a toroidal rubber inner tube or tire which is a perfect torus either in the deformed or undeformed state. The inner tubes or tires are assumed to be free to inflate, that is, they are assumed not to be constrained, for example by a wheel.

ISSN:0021-8995    

DOI:10.1002/app.1982.070270102

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe ultrafiltration process was modelled in three separate stages with distinctive time constants. It was shown that in the first stage lasting less than 5 s a quasi‐steady‐state concentration profile is reached on the membrane/solution interface. In the second stage of 1–10‐min solute adsorption on the membrane surface including the pores controls the permeation rate. The third stage is governed by a reaction mechanism which produces a surface gel causing flux decline at a slower rate than in the previous adsorption step. This polymerization of the protein to a gel on the membrane was shown to be second order in the interface protein concentrations. A reproducible and inexpensive method has been developed to attach food‐grade proteases onto UF membranes by producing a primary adsorbed layer of enzyme which then retards the rate of gel formation on the ultrafilter. This resulted in 25–78% improvement in cumulative permeate yield in a standard 22‐h run when processing 0.5% albumin or hemoglobin. The enhanced fluxes with self‐cleaning membranes were modelled by incorporating an enzyme activity term to counteract the deposition of gel on the membrane surface and altering the apparent order of the ge

ISSN:0021-8995    

DOI:10.1002/app.1982.070270103

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

年代:1982

数据来源: WILEY

摘要:

AbstractHydrogels with various degrees of crosslinking were synthesized from 2‐vinylpyridine and divinylbenzene/ethylbenzene monomers using gamma irradiation. The influence of the solvent solubility parameter, ionic strength, and temperature on swelling and gel density were studied. Adsorption of water vapor on these gels was determined, and the data were used in the calculation of free energy changes involved in the process. Finally the drug release behavior‐crosslink content relation was investigated. It was found that increase in crosslinking agent content adversely influenced swelling, gel density, and water vapor adsorption. The solvent solubility parameter was found to influence swelling more than ionic strength. Contrary to what was expected, it was not possible to classify the drug release behavior as first or

ISSN:0021-8995    

DOI:10.1002/app.1982.070270104

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

年代:1982

数据来源: WILEY

摘要:

AbstractImpact resistant plastic foam of dehydrochlorinated poly(vinyl chloride) (DHPVC)—poly(methyl methacrylate) (PMMA) was prepared for cryogenic insulation in space vehicle by the method of compression molding and chemical blowing. Impact resistance was achieved by the formation of the polymer blend, dehydrochlorinated poly(vinyl chloride)‐poly(methyl methacrylate), during the process of foaming the mold at the temperature of 200°C. The polymer blend was separated from the plastic foam and the compatibility was investigated by ultraviolet, infrared spectral studies and differential scanning calorimetry (DSC). The compatibility of dehydrochlorinated poly(vinyl chloride) and poly(methyl methacrylate) was highlighted on the basis of allylic activation introduced in the thermally modified poly(vinyl chloride). The thermodynamic views were also correlated. The versatility of the present method for impact‐resistant foam was point

ISSN:0021-8995    

DOI:10.1002/app.1982.070270105

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

年代:1982

数据来源: WILEY

摘要:

AbstractTemperature dependencies of viscoelastic functions of the three‐component models of composite materials in the transition state temperature range of polymer binder have been studied. On the basis of theoretical calculations for the models, a conclusion has been made about the conditions for shift of the relaxation maxima along the temperature axis. Also conditions for their resolubility on tan δ curves were determined for materials such as filled polymers as well as anisotropic laminated and reinforced plastics with deformation of the components in series. These effects are due to the change in properties of the boundary layer of the polymer. They are entirely dependent on the concentration ratio between the boundary layer and the bulk of the binder polymer and on the difference in their glass temperaturesTg. Concentration of the high‐modulus filler affectsTgof the composition. This is due to the change in the ratio of concentrations of the polymer in the boundary layer and in the bulk. With parallel deformation of the components of the three‐component model, resolubility and shift of the relaxation maxima depend not only on the above factors, but also on the reinforcing filler concent

ISSN:0021-8995    

DOI:10.1002/app.1982.070270106

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

年代:1982

数据来源: WILEY

摘要:

AbstractConversion and molecular weight distribution are computed and compared for uncatalyzed and catalyzed nonequimolecular polycondensation in continuous flow‐stirred tank reactors (CSTRs) using two different kinetic schemes proposed by Flory and Lin, respectively. The contrast between the two schemes is also remarkable as found in the batch reactors. The polydispersity indices in the CSTRs are substantially larger than those obtained in the batch reactors. Also, the molecular weight distribution splits into two curves for odd and even homologues regardless of the two different schemes. An extremely long rersidence time is needed to obtain the higher conversion accompanying a large polydispersity index as compared to the batch reactors. The polydispersity can be expressed in CSTR asx̄w/x̄n= 2 Σ ∞n=1n2Nn(R+1−2P)/

ISSN:0021-8995    

DOI:10.1002/app.1982.070270107

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe gas‐chromatographic retention of a series ofn‐alkanes at effectively zero coverage was measured on a poly(ethylene terephthalate) film surface, and the free energy of adsorption per—CH2—segment ofn‐alkane at zero surface coverage, ΔḠ 0A(CH 2), was calculated. This quantity is a direct measure of the London (nonpolar) interactions of the surface. A value of 40 mN/m for γ1/2, the London Component of the polyester surface free energy, may be estimated from the gas‐chromatographic results, in good agreement with results from contact angle measurements. The complete adsorption isotherm and spreading pressure forn‐decane were also measured by finite‐concentration gas chromatography. The method is restricted to polar or crystalline polymers, where then‐alkane does not penetrate the bulk of the materia

ISSN:0021-8995    

DOI:10.1002/app.1982.070270108

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe water and salt transport properties of untreated and heat‐treated poly(vinyl alcohol) (PVA) membranes were investigated. Water and salt permeabilities decreased abruptly as a result of heat treatment. The effect of heat treatment on the water and salt transport in PVA is expressed mainly by changes in the activation energies of the corresponding permeability coefficients. Due to the fact that the decrease in the salt permeability with heat treatment was considerably greater than the decrease in the water permeability, a pronounced improvement in the salt rejection of PVA membranes was found as a result of heat treatmen

ISSN:0021-8995    

DOI:10.1002/app.1982.070270109

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

年代:1982

数据来源: WILEY

摘要:

AbstractA new technique is presented which permits the quantitative characterization of the dynamic viscoelastic properties of polymer melts and liquids. A new sample holding system with oscillatory shear platen and modification of the amplifier and oscillating unit made it possible to measure rheological properties of the viscous liquids using the Rheovibron. The dynamic shear modulus, viscosity, and internal friction of acrylic dope, and silicone fluids are obtained by using the new procedure and developed mathematical expressions. This technique will be useful in studies on the rheological properties characterization of polymer melts and liquids in conjunction with process parameters.

ISSN:0021-8995    

DOI:10.1002/app.1982.070270110

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

年代:1982

数据来源: WILEY