CHARACTERIZATION OF POLYMERS BY SOFTENING BEHAVIOR, THERMOGRAVIMETRIC ANALYSIS, AND DIFFERENTIAL THERMAL ANALYSIS

The thermal behavior of a large number of experimental polymers have been studied. A compilation of the softening under, thermogravimetric analysis and differential thermal analysis has been used to determine glass transition temperatures, melting points, secondary reactions, and decomposition temperatures. Softening under load produces a penetration versus temperature curve outlining the range in which glass transitions and crystalline melting occur. A second penetration step may indicate reactions with loss of material an expansion often occurs, on the other hand, when formation of gases is involved. The TGA record of weight loss versus temperature is straightforward and indicative of decomposition or other reactions involving loss of material. DTA measurements required repeated runs with up to three different instruments, and rigidly controlled test conditions to obtain reproducible results and to ascertain the significance of certain transitions and eliminate those not inherent in the polymer itself. The influence of variables in DTA and the validity of test results are discussed.