Before the pressurization trials of the four independent experiments,
the sample bag was rapidly equilibrated to the established
temperature and introduced into the compression chamber, previously
equilibrated at the same temperature. The samples for subzero
experiments were quickly pre-cooled by liquid nitrogen
vapour and then equilibrated to the set temperature. The chamber
was filled by flushing the pressurizing medium from the bottom
inlet and keeping the cover vent valve open until the complete
removal of the air. After an appropriate temperature equilibration
time, the pressure was increased by 100 MPa/min, while the
decompressionwas almost immediate. A 300 s treatment time was
used in all of the experiments. The pressure and temperature
combinations were determined according to a two variable central
composite design (CCD, 14 runs) with pressures ranging from 100
to 300 MPa and temperatures ranging from 5 C to 45 C.