Chemistry Reference
In-Depth Information
Starch
TGAT
IPN
IXN
Starch XN
225
250
275
300 25
350 75
400 25
450 75
500
Temperature (
o
C)
Fig. 7.13
Derivative weight loss of the decomposition peaks of the five biohybrid materials
containing materials is the major feature and demonstrating the large difference
the presence of even a small amount of starch makes to these materials in terms of
their ability to store water. In addition the interaction between water and starch in
these biohybrids varies as well. For pure starch the water release extends from 50 °C
to just above 200 °C. This is similar to the behaviour observed for the IPN of the
biohybrid as the starch networks continues to closely resemble that of pure starch.
However the water release observed for the intercrosslinked hybrids is significantly
narrower with completion of the water loss below 180 °C and much of that occur-
ring at temperatures around 100 °C. This behaviour seems to be dependent on the
extent of interaction between the starch component of the hybrid material and the
degree to which the interaction disrupts the native structure of the starch.
The second major feature of the thermal analysis of the hybrid materials occurs
between 300 and 450 °C depending on the hybrid. The derivative of the weight loss
of the TGA results for this region is shown for all of the materials in Fig.
7.13
. These
weight loss peaks correspond to the decomposition of the organic components of
the materials. In the case of pure starch a single narrow feature in the derivative
of the weight loss is observed from 290 °C and 320 °C with a peak 310 °C due to
the decomposition of the starch. For the organosilicate material without starch, no
decomposition is observed until 360 °C with a broad peak at 395 °C tailing off to
470 °C. This delayed decomposition is due to the short propyl-chains present in the
organosilica materials. In the case of the IPN, the decomposition for both the starch
