The effect of phase transitions on release of n-propanol entrapped in carbohydrate glasses
1995
Levy, Gershom | Karel, M.
The mobility of an organic volatile probe (1-n-propanol), incorporated in two types of amorphous carbohydrate glasses, was evaluated by measuring probe retention as a function of time. Retention was found to depend on temperature, moisture content and the degree of matrix collapse. In sucrose glasses, crystallization and probe release occur simultaneously and both crystallization and release depend on the temperature above T(g), as predicted by the William-Landel-Ferry (WLF) equation. In sucrose:raffinose systems held above T(g), initial rapid release of the probe ('fast' release) is observed, coinciding with and presumably due to, matrix flow during collapse, followed by a much slower diffusional release. Relaxation times for collapse (tau(c), and 'fast' release (tau(FR)) above T(g) were calculated. They were found to be dependent on T-T(g) and moisture content. Dependence of relaxation times on (T-T(g)) was found to be well predicted by the WLF equation.
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