Isothermal ageing effects

Based on the assumption that there is no chemical interaction or any synergistic effect caused by physical changes in the blends, theoretical weight losses of the blends can be calculated, using the isothermal aging data of the individual components as well as their weight percents in the blends. The results are compared with the experimental data in Table IV (BCB/K-353) and Table V (BCB/Dicyanate). 

Isothermal age mode The sample is directly heated to the desired initial temperature. At this temperature, the instrument seeks for an exothermal effect as above. 

Alternative analytical methods are the JCAHR isothermal single relaxation time model [Kovacs et al., 1979] and the peak shifting technique, [Hutchinson, 1992]. None of these attempt to use the data to predict long-term aging effects for which a different approach is necessary. 

Xiang 235, Jones FR. Effect of isothermal ageing on thermomechanical stability of carbon fibre reinforced PMF-15 resin matrix composites. In Found MS, editor. Experimental techniques and design in composites materials. Sheffield Academic Press 1995. pp. 406—20. 

In a study on the thermal and UV ageing of two commercial polyfoxymethy-lene) (POM) samples, one of which was a copolymer (see related study discussed later under Section 4.3, thermogravimetric analysis (TGA)), used in car interior applications, involving both DSC and TGA, isothermal OIT measurements were made at several different temperatures [8]. One conclusion from this study was that "extrapolation of the OIT data from high temperatures (molten state) to ambient temperatures in the solid state does not reflect effective antioxidant performance at room temperature", and thus measurements close to the melting point are not appropriate for reliable lifetime estimations. 

Consider, now the dependence of 0 upon potential under the condition that AGe varies with 0. It will he less dramatic (i.e., d dV will be much smaller) than in the situation represented by the original, simpler, corresponding, Langmuir equation [Eq. (7.153)]. If the latter isotherm is applicable to a variation of 0 with potential at constant concentration, the surface is effectively either empty of intermediate (0 1) or near to 0 = 1. With Frumkin-Temkin in control, 0 varies linearly and more slowly with V than it does with the Langmuir equation. Thus, from (7.156), at constant cp... 

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