Modulus compressive

Dielectric strength, kV mm Electrical Volume (dc) resistivity, ohm-cm Dielectric constant (60 Hz) Dielectric constant (10 Hz) Dissipation (power) factor (60 Hz) Dissipation factor (10 Hz) Mechanical Compressive modulus, 10Mb in-2 9.8-12 24-31 16-24 1014-1016 4.5-6.0 19 335-600 14 ... 

Fig. 3. Effect of density on compressive modulus of rigid cellular polymers. A, extmded polystyrene (131) B, expanded polystyrene (150) C-1, C-2, polyether polyurethane (151) D, phenol—formaldehyde (150) E, ebonite (150) E, urea—formaldehyde (150) G, poly(vinylchloride) (152). To convert...

Strengths and moduli of most polymers increase as the temperature decreases (155). This behavior of the polymer phase carried over into the properties of polymer foams and similar dependence of the compressive modulus of polyurethane foams on temperature has been shown (151). 

After some early uncertainty in the literature about the nature of the pressure sensitive bond, Dahlquist [5,6] related modulus data to tack-temperature studies and observed that the compression modulus of the adhesive had to be less than about 3 X 10 dyne/cm (3 x lO Pa) before any adhesive tack was observed. This was explained as the highest modulus that still allowed the adhesive to be sufficiently compliant to wet out or come into molecular contact with the substrate and form dispersive bonds. As other investigators [7-9] accepted this requirement it was termed the Dahlquist Criterion . 

Generally there is a stiffening effect in compression compared to tension. As a first approximation one could assume that tension and compression behaviour are the same. Thomas has shown that typically for PVC, the compression modulus is about 10% greater than the tensile modulus. However, one needs to be careful when comparing the experimental data because normally no account is taken of the changes in cross-sectional area during testing. In tension, the area will decrease so that the true stress will increase whereas in compression the opposite effect will occur. 

Throne has reported that the relationship between foam modulus and density can be generalised to other properties such as tensile strength, fatigue strength, creep properties as well as shear and compression modulus. Thus if X is the general material property then... 

P. Richetti, P. Kekicheff, P. Barois. Measurement of the layer compressibility modulus of a lamellar mesophase with a surface forces apparatus. J Phys II 5 1129-1154, 1995. 

Fiber/matrix Coupling agent Tensile strength Increase in properties [%] Young s Compression modulus strength Impact energy... 

Generic Material Type Flexural Modulus, MPa Flexural Yield Stress, MPa Compressive Modulus, MPa Compressive Stress, MPa At... 

The majority of tests to evaluate the characteristics of plastics are performed in tension or flexure hence, the compressive stress-strain behavior of many plastics is not well described. Generally, the behavior in compression is different from that in tension, but the stress-strain response in compression is usually close enough to that of tension so that possible differences can be neglected (Fig. 2-19). The compression modulus is not always reported, since defining a stress at... 

Several other factors affect the frictional forces. If one or both of the contacting surfaces have a relatively low compression modulus it is possible to make intimate contact between the surfaces which will lead to high friction forces in the case of plastics having good adhesion. It can add to the friction forces in another way. The displacement of material in front of the moving object adds a mechanical element to the friction forces. 

The test can provide compressive stress, compressive yield, and modulus. Many plastics do not show a true compressive modulus of elasticity. When loaded in compression, they display a deformation, but show almost no elastic portion on a stress-strain curve those types of materials should be compressed with light loads. The data are derived in the same manner as in the tensile test. Compression test specimen usually requires careful edge loading of the test specimens otherwise the edges tend to flour/spread out resulting in inacturate test result readings (2-19). 

Resin Material Compressive Modulus, psi x 103 Heat Distortion Temperature, °F, 264 psi Heat Resistance, Continuous °F Thermal Expansion, in./in.- C x 10-5 Thermal Conductivity, cal/cm2-sec-°C-cm x 10 4 Volume Resistivity, ohm-cm... 

This conclusion is supported by the experimental result " given by the pulsed-NMR measurement that the spin-spin relaxation time T2 is considerably shorter for the gel than that for the matrix mbber vulcanizate, which of course, indicates that the modulus is considerably higher for the gel than for the matrix mbber. More quantitatively, Maebayashi et al. measured the acoustic velocity of carbon gel by acoustic analysis and concluded that the compression modulus of the gel is about twice that of matrix mbber. Thus, at present, we can conclude that the SH layer, of course without cross-linking, is about two times harder than matrix cross-linked mbber in the filled system. 

Most mechanical and civil engineering applications involving elastomers use the elastomer in compression and/or shear. In compression, a parameter known as shape factor (S—the ratio of one loaded area to the total force-free area) is required as well as the material modulus to predict the stress versus strain properties. In most cases, elastomer components are bonded to metal-constraining plates, so that the shape factor S remains essentially constant during and after compression. For example, the compression modulus E. for a squat block will be... 

The responses chosen all relate to important foam properties. We believed that yi, the emulsion droplet size, determines y2, the cell size in the resultant foam, and we wished to determine whether this is true over this range of formulations. The foam pore size ys should determine the wetting rate y7, so these responses could be correlated, and yg, the BET surface area, should be related to these as well. The density y and density uniformity ys are critical to target performance as described above, and ys, the compressive modulus, is an important measure of the mechanical properties of the foam. 

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