DIFFERENT APPROACH FOR THE CORRELATION OF THE TG OF MIXED AMORPHOUS SYSTEMS

An empirical equation relating the glass transition (measured dynamically) of mixed systems to their pure components Tgs can be fitted by the following relationship: In Tg=m1InTg1+ m2InTg2. where m is either volume or wt % of each component. The thermodynamic implications of the logarithmic relationship have been considered and it is shown that other relationships governing the Tg of mixed systems (Fox equation etc.) can be derived using certain thermodynamic constraints. A general power law dependence of log Tg on the apparent activation energy of Tg at a given frequency is also ascertained from experimental data and it is shown that this power law relationship can be obtained from the WLF approach to the glass transition. From this, a relationship concerning the apparent activation energies of Tg (at a fixed frequency) of a mixed system as a function of the pure component activation energies is derived. © 1979.