It cellulose that is certified by IR spectroscopy.

It clearly shows that the onset, maximum peak
degradation temperatures, moss loss at Tmax and maximum
degradation rate are increased in a linear fashion as the heating rates (?).
This temperature shift might be due to heat transfer effect. On the other hand,
the residual char yield decreased as the heating rate increased might be due to
rapid pyrolysis, which needs very high heating rate and short residence time
for the degraded products. However, there is no significant difference in the
onset and maximum peak degradation temperatures of NaCMC.

 

Case study 4

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Ge Y. et al. (2013) study on the
feasibility of preparing cellulose from sugarcane bagasse its structure
characterized by means of TGA. TGA measurements are
performed in an instrument STA449C (Netzsch) using 8?10 mg of powder sample in sealed aluminum crucibles under nitrogen flow
(20 ml/min) and heated from 25oC
to 600?C at 15oC/min.

 A small
mass loss is found for NaCMC1 in the range of 50-150 oC due to the
evaporation of the humidity of the materials or low molecular mass compounds
remaining from the chemical procedures. Furthermore, decomposition of cellulose
has a sharp mass loss at 350 oC, and it is almost decomposed to a residual
mass of 20%. On the other hand, the decomposition of NaCMC1 starts around 250
oC and it has a higher residual mass of 50%. The differences in the
starting temperature for degradation imply that NaCMC1 had a lower thermal
stability than that of cellulose, which can be due to a higher degree of order
of NaCMC1 and a less quantity of intermolecular hydrogen bondings compared to
source cellulose that is certified by IR spectroscopy. The differences in residual mass are caused by the
higher DS and molecular mass of NaCMC1 that can enhance the char-forming
ability 26.

 

Akram M.
et al. (2016),
perform TGA ramp test to determine the
main procedures of weight loss occurring during the thermal degradation of CMC
and their respective temperatures. Results confirm the preliminary findings
made by DSC. The first step is observed between 40 and 200 oC
and is attributed to the loss of moisture content, additionally
confirmed by the results of isothermal TG analysis at 100 oC
for 60 min. The onset of decomposition takes place at 242 oC,
reaching its maximum rate at around 265 oC,
before termination at 305 oC.
At the point of the highest degradation rate,
the sample will have lost 36.3 % of its initial weight. This weight loss is
attributed to the decarboxylation of CMC, releasing CO2, in addition
to the loss of hydrogen and oxygen molecules due to the splitting off of
various side groups. By the end of the main decomposition stage, the CMC sample under investigation has
lost around 50 % of its initial weight. The further
mass loss is observed as the temperature was raised up to 500 oC,
albeit at a much lower rate, leaving behind an ash content of 41 %. Applying
rate-controlled mass change conditions pinpoints the decomposition temperature
at 269 oC, where the major weight
loss stage can be clearly identified. Isothermal TG soaking tests are performed
to evaluate the time needed for CMC decomposition under various isothermally
held conditions. As the temperature is
increased from 260 to 300 oC
the decomposition time decreases from 26 to 12 min. After this period, the
decomposition reaction is complete, beyond which no further weight loss is
observed.

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