The Heating-rate Dependence of the Mechanical Properties of Several Polymers at Higher Temperatures

Measurements of the mechanical properties of various polymers at higher temperatures under the conditions of several heating rates were carried out in the air using the torsional braid analysis (TBA) method. It has become apparent that the examples of the dependence of the mechanical properties upon the heating rate at higher temperatures are classified into two groups. The first is characterized by the fact that the temperature of the maximum in the logarithmic decrement remains unchanged, irrespective of any changes in the heating rate. This situation is related to the physical process. On the other hand, in the case of the second group, the TBA curves are shifted to higher temperatures with an increase in the heating rate; this is the results of chemical processes. A kinetic treatment of thermal analysis, in which kinetic parameters can be calculated from the heating-rate dependence of the characteristic point in the observed curves, was used in the present study. From this analysis, the apparent activ...