摘要:

AbstractThe dynamic mechanical properties of titanium dioxide‐filled poly(vinyl acetate) have been studied at filler concentrations of 0, 10, 20, 30, and 40 wt.‐% TiO2by using a torsional pendulum. The damping factor was found to increase with higher temperatures. At 40°C., the damping factors for the different TiO2concentrations were estimated to be the same. Damping factors above 40°C. were difficult to obtain due to the rubbery nature of the TiO2–poly(vinyl acetate) systems. From 24 to 35°C., 10 wt.‐% TiO2‐poly(vinyl acetate) was closer in damping factor increase to unfilled poly(vinyl acetate) than to the higher TiO2‐content polymers. At all temperatures, damping factors decreased with higher TiO2concentration. As the temperature decreased to 0°C., damping factors for the filled systems approached a common value. Potential energy of filled systems as indicated by shear modulus values is increased by higher TiO2concentrations and lower temperature. Kinetic energy for the filled systems, as shown by the out‐of‐phase modulus, is actually increased by larger filler concentration and higher temperature. A model is proposed where introduction of TiO2filler acts to increase general long‐range polymer chain stiffening and at the same time enables short‐range chain mobility to rise, possibly through gr

ISSN:0021-8995    

DOI:10.1002/app.1966.070100501

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

年代:1966

数据来源: WILEY

摘要:

AbstractThe stress–strain properties of TiO2‐filled poly(vinyl acetate) have been studied at filler percentages of 0, 10, 20, 30, and 40% TiO2over a strain‐rate range of 100–5000%/ min at 24°C. Tensile strength, Young's modulus, and offset yield strengths all were found to increase with higher strain rates and higher TiO2contents. Ultimate elongations decreased with greater TiO2content and higher strain rates. Shift factors for volume fraction of filler were estimated for tensile properties as function of test rate. Stress relaxation studies have shown a reduction in relaxation times with increasing TiO2content. Calculations of the out‐of‐phase Young's modulus were made as a function of filler content employing a box‐type of distribution of relaxation times. A possible explanation for the stress–strain behavior observed is that introduction of TiO2changes the internal viscosity of the system, similar to the effect of temperature. This would also mean that the ultimate properties would be dependent on filler content and strain rate because viscous resistance to chain deformation would be altered. The effect of filler on stress relaxation could be thought of being due to an increase in short‐

ISSN:0021-8995    

DOI:10.1002/app.1966.070100502

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

年代:1966

数据来源: WILEY

摘要:

AbstractParlodion membranes formed by the dipping technique using solutions of Parlodion in isoamyl acetate of concentrations extending to 3% have been characterized. The thickness of the membrane increased with increase in the viscosity of the membrane‐forming solution. Although the membrane resistance increased with increase in its thickness, the specific resistance ρ of the different membranes was not a constant but increased with increase in thickness and showed a tendency to attain a limiting value. The effects of different cations at the same concentration and of the same cation at different concentrations on membrane properties have been studied. Membranes formed by multiple dips into the same solution and into different solutions of Parlodion have also been characterized in respect of their electrical resistance, capacitance, and specific resistance. In general, all Parlodion solutions on a second dip gave membranes of increased thickness and resistance. Subsequent dips always increased membrane thickness and resistance except in the case of 0.25% solution which produced a membrane of approximately the same thickness and resistivity. The dipping and the spreading techniques of membrane formation have been used to introduce stearic acid, phosphatidyl L‐serine, and cholesterol into the Parlodion matrix, and the lipoidal membranes so prepared have been character

ISSN:0021-8995    

DOI:10.1002/app.1966.070100503

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

年代:1966

数据来源: WILEY

摘要:

AbstractThe equilibration of water between aqueous gelatin solution and physically separate cakes of ice was observed. Typically, the water content of the solutions reached a nearly steady value several times before final equilibrium, reasons for which are discussed. The equilibrium gelation concentrations were found to be 72 ± 1%, 77 ± 2%, and 80 ± 3% at −10, −21, and −33°C., respectively, in moderately good agreement with predictions based on the vapor pressure measurements of Bull at higher tem

ISSN:0021-8995    

DOI:10.1002/app.1966.070100504

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

年代:1966

数据来源: WILEY

摘要:

AbstractConductometric and potentiometric titration behavior of emulsions of ethyl acrylate copolymers with acrylic acid and methacrylic acid was investigated. On the conductometric titration curves of the emulsions of the copolymers with more than 5 mole‐% of the acids, two equivalence points, based on the copolymerized acids, were observed, but only one equivalence point was observed on potentiometric titration. Almost all of the copolymerized acids could be detected by both titration methods. The change in optical density of the dilute emulsions with their pH was measured. The particles of these emulsions were studied under an electron microscope. These results showed that, when the pH of the emulsions was raised, the surface layers of the particles began to dissolve and their cores started to swell near the pH of their first equivalence points. When the pH was again lowered the dissolved polymers coagulated, tiny particles were formed, and the swollen cores were dehydrated. The surface layers thickened with increasing amount of the copolymerized acid. These behaviors were very similar in the emulsions of the copolymers with acrylic acid and methacrylic acid. The quantity of water‐soluble polymers formed in the course of the emulsion copolymerization was approximately 3–4% or slightly more. This quantity depended only slightly upon the amount and type of the copolymerized acid. The acid contents of the water‐soluble polymers were higher in cases of the copolymers with acrylic acid than in those with methacrylic acid. No relationship with the amount of copolymerized acid was esta

ISSN:0021-8995    

DOI:10.1002/app.1966.070100505

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

年代:1966

数据来源: WILEY

摘要:

AbstractAn experimental study was conducted to determine previously unavailable data showing the relationship between temperature and the velocity of longitudinal ultrasonic waves through several plastics. The ultrasonic frequencies used were between 1 and 10 Mc./sec., and the temperature range covered was between room temperature and 100°C. Velocity–temperature curves were determined for nylon, a high‐ and a low‐density polyethylene, Plexiglas, Teflon, and for several reentry vehicle nose‐cone materials, including chopped nylon phenolic, tape‐wound nylon phenolic, Castable 124, Avcoat I, and Avcoat 19. Less complete data were obtained for Avco phenolic fiber glass, General Electric phenolic fiber glass, and oblique tape‐wound refrasil. These layered materials are difficult to measure, and the velocity of acoustic waves is very dependent on the direction of propagation with respect to the laminations. For most of the materials studied the velocity was found to decrease more or less linearly with increasing temperature. Typically, the velocities at 100°C. were 9–31% less than at r

ISSN:0021-8995    

DOI:10.1002/app.1966.070100506

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

年代:1966

数据来源: WILEY

摘要:

AbstractUltrasonic longitudinal wave velocities in layered materials were measured as a function of the lamination angle at several temperatures. It was found that the longitudinal wave velocity versus lamination angle curve maintains the same shape (for a given material) for temperatures between 25 and 125°C. Furthermore, it was found that the wave velocity versus lamination angle curve can be predicted to within 2% by a theoretical equation involving only the lamination angle,&thetas; (taken as the angle between the grain of the sample and the direction of sound propagation);c(0°), the measured wave velocity at an angle of 0°; andc(90°) the measured wave velocity at an angle of 90°. Finally, it was found that the longitudinal wave velocity of certain materials varies as much as 25% between lamination angles of 0° and 90°, while other materials show less variation, and some none

ISSN:0021-8995    

DOI:10.1002/app.1966.070100507

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

年代:1966

数据来源: WILEY

摘要:

AbstractThe velocity and attenuation of longitudinal bulk waves in a solid epoxy foam were measured by an acoustic pulse technique in the frequency range of 0.667–4.0 Mc./sec. and in the temperature range from ambient to 150°C. The measurements are reported with the density of the solid epoxy and with aluminum impurity loading as parameters. Over the indicated temperature and frequency ranges, complete attenuation and velocity measurements are reported for one foam corresponding to a density of 0.325 g./cc. In the density range of 0.088–0.325 g./cc. for the unloaded foams, attenuation is reported at room temperature. It is observed that the longitudinal velocities for all the densities decrease with temperature by about 40% in a span of 100°C. and that an approximately linear relation exists with temperature. The velocities in the foams loaded with small percentages of aluminum and heat‐treated at 250°C. exhibit temperature behavior which is dependent upon the combined effects of loading, density change, and epoxy properties. For the loaded foam with the highest density (1.068 g./cc.), velocity is reported to a temperature of about 250°C. The velocities of all the various density samples with the exception of the loaded foams exhibit inflections at a temperature of about 110°C. The attenuation–temperature measurements on the 0.325 g./cc. sample show similar behavior at this temperature except that the effect is much more pronounced than the velocity inflection, hence a better indication of the transition. The precision of the measurement is about 2% for the relative longitudinal velocities and about 20% for the

ISSN:0021-8995    

DOI:10.1002/app.1966.070100508

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

年代:1966

数据来源: WILEY

摘要:

AbstractIt is shown that some results of recent publications (of Longworth and Piesky and of Bartoš) can be treated as particular consequences of the principle of universality of temperature‐independent viscosity characteristics of polymer melts, earlier found by these authors. This concerns the method of determination of molecular weight by means of melt index measuring and supposition that the definite value of apparent viscosity to initial Newtonian viscosity ratio can be considered to be a criterion of elastic turbulent flow emergi

ISSN:0021-8995    

DOI:10.1002/app.1966.070100509

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

年代:1966

数据来源: WILEY

摘要:

AbstractWith the use of strain‐gauge pressure transducers, an improved constant volume apparatus has been constructed for the measurement of isothermal permeabilities of gases from thermo‐osmosis experiments. Permeabilities are reporducible to about ±5% accuracy and compare favorably with those obtained by alternative techniques. Revised values are presented for the permeability coefficients of the noble gases in ru

ISSN:0021-8995    

DOI:10.1002/app.1966.070100510

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

年代:1966

数据来源: WILEY