Determination of the glass transition of powder samples using Dynamic Mechanic Analysis on compacts
Artikel i övriga tidskrifter, 2010
Dynamic Mechanic Analysis, DMA, is a
sensitive method to determine the glass
transition temperature (Tg) of materials.
Several different sample geometries such as
three point bending, stretched films or
compressed cylinders, are commonly used.
The Tg of a powder is related to its “sticky
point”, i.e. the temperature when the powder
particles interact instead of flowing freely.
The determination of powder Tg is not
straightforward using DMA due to the
limiting geometry. Here it is demonstrated
that the Tg of powder samples can
be effectively and correctly determined
by DMA on compacts in compression mode,
using a standard wedge shaped probe usually
utilized in three point bend analysis. The
analysis of compacts holds the benefits of
analysing powder samples as received from
manufacturers, being relatively robust with
regard to deformation as the material
becomes rubbery, and enabling easy sample
preparation and handling.