Epoxy linear expansion

Figure 24.5 Comparison of linear expansion as function of temperature of an epoxy resin controi with an epoxy/silica nanocomposite and an epoxy/silica hybrid.

L.2.2 Linear shrinkage of epoxy grout shall be less than 0.080 percent and thermal expansion less than 54 x 10 mm/mm/°C (30 X lO in./in./°F) when tested by ASTM C 531 test method. 

Studies in larger temperature intervals showed that expansion obeys a parabolic law, both for linear polymers (Bongkee, 1985), and epoxy thermosets (Skourlis and McCullough, 1996) ... 

By analyzing the linear portion of the thermal expansion curves below and above T, it is possible to calculate the expansivity of each specimen taking into account its individual thickness. Through such analysis, significant variations were observed in the thermal expansivity of the cured epoxy both below and above its T. ... 

Figure 12.35. Comparison of experimental values of linear coefficient of expansion of a Ti02-filled epoxy resin with values predicted by equation (12.54). The dashed curve is for the rule of mixture, the solid curve for the predictions of equation (12.54). Temperature range -50 C to 100°C df = 1 x 10" °C Ef = 7.25 x lO psi Vf = 0.23 dip = 55 X lO" C = 7.25 x 10 psi = 0.3. (Wang and Kwei,...

It is usually the case that Of -c a and Ef > Equations 6.25(a) and (b) then predict widely differing linear thermal expansion parallel and perpendicular to the res. As an example, a, and U2 (from eqns 6.25) are plotted versus in Figure 6.14 for epoxy reinforced by glass fibres. It... 

Predicted coefficients of linear thermal expansion for aligned glass-fibre reinforced epoxy. 

The composite material of Example 6.4 is subjected to a temperature rise of 100 K. Calculate its free thermal expansion in the direction inclined at 30° to the fibres. Take the coefficients of linear thermal expansion to be 5 X 10 K and 60 X 10" K for glass and epoxy, respectively. 

The intercomponent adhesion level can be estimated quantitatively with the aid of the parameter b (Figure 9.9), which is determined by an independent method using the thermal expansion coefficient of epoxy polymers. In Figure 9.27 the curves 1-3 represent three basic types of the dependences of the linear thermal expansion coefficient of the considered epoxy polymers on the relative contents of nanoclusters. The straight line 1 illustrates the case when adhesion is absent between two structural components of natural nanocomposite and at the thermal expansion coefficients of the loosely packed matrix and nanoclusters, respectively) the loosely packed matrix will expand on heating independently from... 

Figure 9.27 The dependences of the thermal expansion linear coefficient a p on the relative fraction (p of nanoclusters. 1 - the adhesion absence on the boundary between components 2 - the mixtures rule 3 - Terner equation 4, 5 - the experimental data for epoxy polymers EP-1 (4) and EP-1-200 (5) [51]...

In Figure 9.32 the dependence of the thermal expansion linear coefficient a p on the relative fraction of nanoclnsters, which are considered as nanofiller, for epoxy polymers is addnced. As has been expected [35], an increase in results in a reduction in ttpp, comparable with that observed for polymer composites with the introduction of particnlate fillers. So, an increase in (p from 0 to 0.60 reduces a p by about 1.50 times (Figure 9.32) and with the introduction of calcium carbonate or aluminium powder with volume contents (p = 0.60 in the epoxy polymer the thermal expansion linear coefficient value decreases by 1.70-2.0 times [35]. The dependence a p(expressed analytically by the following empirical equation [62] ... 

In Figure 9.33 the dependence a p(D ) for the considered epoxy polymers is adduced, which has an expected character. The growth in the thermal expansion linear coefficient with an increase in molecular mobility level is observed. In Figure 9.33 a solid straight line shows the similar dependence oc(D p) for amorphous aromatic polyamide (phenylone S-2). As one can see, this straight line corresponds well to the data for the considered epoxy polymers. This means that irrespective of the class of polymers, their thermal expansion coefficient is defined by the molecular mobility level, which in paper [62] is characterised by the dimension... 

Figure 9.33 The dependence of the thermal expansion linear coefficient a p on the fractal dimension of the chain part between nanoclnsters for epoxy polymers. The designations are the same as in Figure 9.32. The straight line 3 shows the dependence cc(D ) for phenylone [62]...

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