Theory
TMA is believed to have developed from
hardness or penetration tests and was
used on polymers in 19481
.
Subsequently, it has developed into a
powerful tool in the analytical
laboratory. TMA measurements record
changes caused by changes in the free
volume of a polymer.2
While the latter
tends to be preferred by engineers and
rheologists in contrast to chemist and
polymer physicists who lean toward the
former, both descriptions are equivalent
in explaining behavior. Changes in free
volume, vf
, can be monitored as a
volumetric change in the polymer; by the