E modulus

E Modulus of elasticity N/ni ibftft NPSH Net positive suction head m ft... 

E = Modulus of elastioity, Ibflin (multiply tabulated values by 10 )... 

E, = modulus of elasticity at design maximum or design minimum temperature, Ibf/in (MPa)... 

Estimate the thermal shock resistance AT for the ceramics listed in Table 15.7. Use the data for Young s modulus E, modulus of rupture c, and thermal expansion coefficient a given in Table 15.7. How well do your calculated estimates of AT agree with the values given for AT in Table 15.7 ... 

In each of the following equations a = maximum tensile stress, E = modulus of elasticity and t = specimen thickness. 

E modulus of elasticity or Young s EVOH ethylene-vinyl alcohol... 

Me = the cross-link density of melt cr = stress E = modulus... 

Ep/E = modulus of filler/modulus of unfilled elastomer

volume fraction of filler... 

Figure 7. Layered silicate particles in a polymer and their effect on the E-modulus...

The phenomenological ordering of polymers projected for use as constructing materials is not an easy matter. Sometimes the temperature stability is used as a criterion, i.e., the temperature up to which the mechanical properties remain more or less constant. Another attempt for classification, uses the E modulus or the shape of the curve of stress-strain measurements (see Sect. 2.3.5.1). In general one can say that semicrystalline thermoplastics are stiff, tough, and impact-resistant while amorphous thermoplastics tend to be brittle. Their E... 

In contrast, the curve E2 (isotactic polypropylene) is characteristic for partially crystalline polymers. The modulus is three decades higher than in an elastomer. At the glass transition temperature [T (2) 0 °C] the decay of the E modulus is small it does not drop to the lower level of the molten state before the melting point. 

The hardness of a polymer can also be estimated from the modulus of elasticity E (high E modulus indicates high hardness). The advantage here is that every region of elasticity and every degree of hardness can be detected with a single kind of measurement (determination of stress-strain-behavior or torsional oscillation). 

For a semi-crystalline polymer the E-modulus shows between Tg and (in which region it is already lower than below Tg), a rather strong decrease at increasing T, whereas with amorphous polymers, which are used below Tg, the stiffness is not much temperature dependent (apart from possible secondary transitions). The time dependency, or the creep, shows a similar behaviour. 

When the rubber is heated from 253 K to 298 K, the E-modulus becomes 298/253 = 1.18 times higher. The wall stress in the balloon will increase by 18% and the diameter decreases to 20/1.18 = 17 cm. Gradually the air in the balloon will be heated up, and the pressure will increase proportionally to the absolute temperature. Eventually the old diameter of 20 cm will be reached. 

A value for E of about 3 GPa is normal for an amorphous polymer in the glassy state, unless below Tg a strong secondary transition occurs such as with PC, so that the E-modulus at ambient temperature is significantly lower. 

The blending of short glass fibres results in an increase of the E-modulus to e g. its threefold over the whole temperature region. If the slope of the log E - T curve is small, such as with semi-crystalline polymers between Tg and T, a vertical shift causes a considerable horizontal shift (see MT 8.1.2.), so a strong increase of the softening points, which are of importance in applications at higher temperatures. 

Apparently all four curves intersect at the same point, namely at the temperature at which A and B have the same E-modulus. Each blend has the same modulus at this temperature. This situation may occur when B is a glassy amorphous polymer and A... 

The photoelastic behavior of nonionized PAAm network and ionized P(AAm/MNa) network prepared by the copolymerization of AAm with MNa ( MNa = 0.05) was investigated in water-acetone mixtures [31]. For a pure PAAm network, the dependences of all photoelastic functions (see Eqs. (15) and (16)), i.e. modulus G, strain-optical function A and stress-optical coefficient C, on the acetone concentration in the mixtures are continuous (Fig. 17). At ac = 54 vol %, the ionized network undergoes a transition which gives rise to jumpwise change in G, A and C also the refractive index of the gel n8 changes discontinuously. While in the collapsed state the optical functions A and C are negative, in the expanded state they are positive. 

E modulus data for Norton hardness grades (after Moser, 1980)... 

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