ISSN:0021-8979    

DOI:10.1063/1.1722096

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

By use of the electrostatic vibroscope method, dynamic measurements have been made of the Young's modulus derived from bending and the torsional modulus of nylon 66 and Dacron filaments ranging in draw ratio from one (undrawn) to six. Quasistatic measurements have also been made to obtain the Young's modulus derived from extension. The dynamic values of the Young's modulus increase from draw ratio one to draw ratio six by a factor of 3.5 for nylon 66 and 5.8 for Dacron. The torsional moduli of both filament types exhibit no appreciable changes with increasing draw ratio.The ratio of the Young's modulus to three times the torsional modulus, which ratio is unity for a homogeneous isotropic material with a Poisson's ratio of ½, is about three for nylon 66 and greater than five for Dacron at a draw ratio of six. These results, along with those obtained at lower draw ratios, indicate that both filaments become progressively anisotropic with drawing, the extent of the anisotropy reflecting mainly the changes in the Young's modulus. As a check on the experimental procedures, the elastic moduli have also been measured for a 1‐mil drawn tungsten wire.

ISSN:0021-8979    

DOI:10.1063/1.1722097

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

The relaxation process of viscous flow may be visualized as the sudden shifting of some small patch on one side of a shear surface with respect to the neighboring material on the other side of the shear surface. Any shear surface will divide a mosaic of such patches lying on the two sides of the surface. Except for the simplest systems, this mosaic of patches will be heterogeneous and can be described by groups each characterized by its mean relaxation time &bgr;n, byxnthe fractional area of the shear surface which the group occupies and by &agr;n, a characteristic shear volume divided bykT. The resulting generalized expression for viscosity is&eegr;=n=1nxn&bgr;n&agr;nsinh−1&bgr;ns˙&bgr;ns˙,wheres˙is the rate of shear. This equation is applied to masticated natural rubber, polystyrene, X‐672 GR‐S, X‐518 GR‐S rubber, and Vistanex LM‐S polyisobutylene. All applications give good agreement with experiment. The known criticisms of Eyring's simple relaxation theory for viscous flow are reviewed, and are apparently taken care of in this general treatment.

ISSN:0021-8979    

DOI:10.1063/1.1722098

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

The authors' theory developed in the preceding paper I is applied to solutions of polystyrene, polyisobutylene, X‐518 GR‐S rubber, and lime base grease with good agreement with experiment. The parameters,xn/&agr;nand &bgr;n(see the abstract of the paper I), were calculated, and are tabulated; these parameters are proportional to the surface concentration and the relaxation time of thenth group of flow units, respectively. The effects of the molecular weights of polymers, concentration, solvent, and temperature on these parameters were studied. Our results establish the following facts:(1) The heterogeneity of flow units increases with increasing molecular weight.(2) In the range of low concentration, &bgr;n(relaxation time) is independent of concentration, while the areal concentration of non‐Newtonian units increases more rapidly than proportional to the bulk concentration of a polymer.(3) A ``good'' solvent increases the concentration of non‐Newtonian units, while the contrary is true for a ``poor'' solvent.(4) In poor solvent solutions, the concentration of non‐Newtonian units increases with increasing temperature, while the concentration is independent of temperature in good solvents.

ISSN:0021-8979    

DOI:10.1063/1.1722099

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

Creep measurements were carried out at 80°C on cellulose acetate fractions characterized as to molecular weight distribution by the equilibrium ultracentrifuge. Stress levels were low enough that linear viscoelastic behavior was observed. Although the effect of molecular weight was not marked, the presence of low molecular weight material in a sample decreased the amount of permanent set and increased the recoverable deformation. In all cases, more than half of the recoverable deformation occurred in less than 10 sec. The results suggest that there was present some sort of a network, although no direct x‐ray evidence for crystallinity could be seen.

ISSN:0021-8979    

DOI:10.1063/1.1722100

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

Measurements of the ultrasonic absorption of water have been made up to pressures of 2000 kg/cm2. The data show that both the shear and compressional losses decrease as the pressure is raised. Comparison of these results with the values predicted by Hall's theory of sound absorption in water shows that the theory must be modified to be in agreement with the experimental data. The modification consists of assuming that the open or ice type of packing is associated with the higher free‐energy state. If this modification is made, the observed data is in excellent agreement with theory. This result leads to the conclusion that even at 0°C less than 30 percent of the molecules in water are arranged in the ice type of packing. The results also indicate that the free‐energy difference between the two states of packing in water is temperature dependent.

ISSN:0021-8979    

DOI:10.1063/1.1722101

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

The superposition principle and the theories of mechanical equation of state, strain, and time hardening were applied to the creep under changing loads of four unfilled thermoplastics—polyethylene; monochlorotrifluoroethylene (Kel‐F), crystalline; polyvinylchloride (Geon‐404), annealed; and polystyrene.A comparison of the theoretical results predicted by these theories with the experimental results indicated the accuracy with which these theories described the creep behavior under changing loads for the above materials.

ISSN:0021-8979    

DOI:10.1063/1.1722102

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

The action of water solutions of dimethyl formamide on Dinitrile A fibers was studied using the stress‐relaxation technique. After prior conditioning and stress relaxation in water, the addition of dimethyl formamide‐water solutions produced an exponential stress relaxation. It was found that the rate and extent of stress relaxation in dimethyl formamide‐water solutions is dependent on the dimethyl formamide concentration. The rate of stress relaxation in dimethyl formamide‐water solutions is also dependent on the cross‐sectional area and the state of orientation of the fiber. These data can best be explained by postulating that the rate of diffusion of the dimethyl formamide‐water solution into the fiber controls the rate of stress relaxation. The diffusion coefficient is found to be concentration dependent, and the diffusion process has an activation energy of 14 kcal.

ISSN:0021-8979    

DOI:10.1063/1.1722103

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A study of the rheological properties of lubricating oils was made by means of semiquantitative measurements of the viscosity and elasticity of surface and interfacial films. A torsion‐pendulum type, surface viscometer was used. A refined, uncompounded mineral oil was shown to possess neither surface nor interfacial viscosity or elasticity. One additive in mineral oil showed surface viscosity and elasticity, and two additives developed these properties at an oil‐water interface. The aged, viscous surface and interfacial films studied were found to be non‐Newtonian.

ISSN:0021-8979    

DOI:10.1063/1.1722104

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

The results of recent measurements of the viscosity and thermal conductivity of argon have shown the importance of studying these transport phenomena over a large density range in different regions of the reduced temperature. It appears that the Chapman‐Enskog theory cannot give an adequate description of the new experiments. It has not yet been possible to give a full account of the observations. However, a less rigorous theoretical discussion demonstrates the relevant physical features of the problem. For the moment it serves to indicate a new experimental program. This research may contribute to a more clear understanding of the transport properties in different states of a material, including the difficult intermediate region between the gas and liquid state.

ISSN:0021-8979    

DOI:10.1063/1.1722105

出版商:AIP    

年代:1955

数据来源: AIP