GLASS RUBBER TRANSITIONS OF CELLULOSIC POLYMERS BY DYNAMIC MECHANICAL ANALYSIS

The glass–rubber transition temperatures (Tg) of several cellulosic polymers [hydroxypropyl methylcellulose (HPMC), hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC)] have been examined using dynamic mechanical analysis (DMA). The melting temperatures of the above polymers were examined using a hot stage melting point apparatus. The primary Tg of three different grades of HPMC (3, 6, and 15 cps) were determined to be 160, 170, and 175 °C, respectively. The primary Tg of the HEC film was determined as 120 °C. The HPC film did not indicate a primary Tg. These cellulosic polymers also displayed secondary transitions. Hot stage melting of HPMC and HPC was observed at 225 to 254 °C and 190 to 195 °C, respectively. The HEC powder did not exhibit a melting temperature, but became darker at temperatures >150 °C. Copyright © 1990 Wiley‐Liss, Inc., A Wiley Company