Formation of the Glassy State and Mesophase in the Water–Sodium Alginate System

Abstract

The phase transition of water–sodium alginate with water content (Wc) (grams of water/gram of dry sample) from 0 to 2.5 was studied using differential scanning calorimetry (DSC). Upon heating, glass transition (Tg), cold crystallization and melting were observed in the Wc range from 0.49 to 2.5. At a Wc less than 0.49, only Tg was observed. During cooling, the crystallization of water in the system was observed from the Wc=0.77. The above difference suggests the presence of glassy water which crystallizes during the heating process. The contribution of non-freezing water and glassy water to Tg and Cp of the system was estimated.