Thermooxidation of TMAHP-cellulose in dependance to its anionic form
Abstract
With the help of DTA, DTG, elementar analysis of carbonised residue and ESR spectroscopy the thermooxidation of trimethylammoniumhydroxyprophyl (TMAHP)-cellulose in dependance to its anionic form was studied. At 300°C the percentage of carbon in carbonised residue run in oxidative atmosphere is higher than for sample run in inert atmosphere. The percentage of hydrogen is decreasing simultaneously. The concentration of free radicals in thermolysed residue is also increasing due to the presence of oxygen. We propose that oxygen is abstracting the hydrogen atoms from polysaccharide and unpaired electrons on carbon atoms are formed. At 400 °C the percentage of carbon in residues run at inert atmosphere is higher than for residue run at oxidative atmosphere. Also the concentration of free radicals in residues is greater in ipert atmosphere than in oxidative one. That is why we suppose that at this temperature oxygen is bonded to polysaccharide residue and free radicals are terminated. From the semiquantitative DTA we can make the following sequence of samples according to their increasing thermooxidative effect: unmodified cellulose < A-HSO−4 < A-Br− < A-I− < A-NO−3 < A-H2PO−4 < A-CH3COO− < A-HCO−3 < A-F− < A-Cl− < A-OH−.
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