The evaporation of Ibuprofen from Ibuprofen-starch mixtures using simultaneous TG-DTA

The variation of the activation energy (E-act) is reported for the evaporation of Ibuprofen-starch binary mixtures in nitrogen atmosphere. It is shown that all the features of Ibuprofen and starch are still present in the mixtures. That is, the loss of water from the starch, melting of the Ibuprofen, the evaporation of the Ibuprofen, and the degradation of the starch, appearing in this order as the heating mode is progressed. The temperature range for the evaporation of Ibuprofen is moved to a higher temperature as the Ibuprofen content in the mixture is increased. This is reflected in the energy of evaporation associated with each binary mixture. The kinetic analysis of the starch degradation is also affected in that the temperature range for the degradation increases with the Ibuprofen content. This again is reflected in an analysis of the activation energy as a function of the original Ibuprofen content in the mixture. The cause of this effect is discussed in the paper. (C) 2000 Elsevier Science B.V. All rights reserved.