GLASS-FORMING TENDENCY AND STABILITY OF THE AMORPHOUS STATE IN SOLUTIONS OF A 2,3-BUTANEDIOL CONTAINING MAINLY THE LEVO AND DEXTRO ISOMERS IN WATER, BUFFER, AND EURO-COLLINS

The glass-forming tendency on cooling and the stability of the wholly amorphous state on warming have been studied by calorimetry in solutions in water, in a phosphate buffer, and in Euro-Collins of a 2,3-butanediol containing 96.7% (w/w) racemic mixture of the levo and dextro isomers and 3.1% (w/w) of the meso isomer (called 2,3-butanediol 97% dl). At equal polyalcohol concentrations, these two properties are almost the same for 2,3-butanediol 97% dl, racemic 2,3-butanediol, and levo-2.3butanediol in water. Replacing water with the buffer increases the glass-forming tendency and stability of the amorphous state. Replacing the buffer with Euro-Collins still increases the stability of the wholly amorphous state but does not change the glass-forming tendency. The glass-forming tendency and stability of the amorphous state were defined as before, but a new definition of critical cooling rates has also been given. The present solutions and previously studied solutions have been classified according to this critical cooling rate. © 1993 by Academic Press, Inc.