EFFECT OF GLASS-TRANSITION AND CROSS-LINKING ON RHEOLOGICAL PROPERTIES OF ZEIN - DEVELOPMENT OF A PRELIMINARY STATE DIAGRAM

Rheological properties and thermal properties are used to characterize the physical states of zein. In this research, the transition tempera ture from glassy to rubbery state of Sigma zein and purified zein was measured with differential scanning calorimetry (DSC) various moisture contents. The temperature and frequency dependence storage (G '') and loss (G '') moduli were obtained for Sigma zein with 15-35% moisture. Zein showed a networking reaction in the temperature range of 65-160 degrees C for moistures greater than or equal to 25%. Below 65 degrees C, zein behaved like an entangled polymeric fluid. As the temperature exceeded 160 degrees C, the cross-linked/aggregated zein softened. A preliminary state diagram of zein as a function of temperature and moi sture content was developed.