Thermogravimetric analysis of cellulose

Abstract

An application of TGA technique to elucidate the chain reaction mechanism of cellulose pyrolysis is discussed. The mathematical expressions for isothermal kinetics are modified for use with temperature‐programmed kinetics. It is shown that in temperature‐programmed kinetics, the initial reaction should theoretically be a pseudo zero‐order type, whereas the latter part should be a pseudo first‐order type. Experimental data from the present study and from the literature are in good agreement with the theory. Energies of activation for the initiation and the propagation steps of cellulose pyrolytic reactions are analyzed from TG data. Various cellulose samples, such as adsorbent cotton, vibratory ball‐milled absorbent cotton, mercerized commercial yarn, mercerized and treated commercial yarn, dewaxed‐kiered cotton, and microcrystalline cellulose are included in this study. A basic problem which is associated with all thermogravimetric kinetic expressions is also discussed.

Biocompósitos de acetato de celulose e fibras curtas de Curauá tratadas com CO2 supercrítico

“…A liberação dos grupos acetila das cadeias de acetato de celulose, assim como a ruptura das cadeias poliméricas, tanto do acetato de celulose como dos produtos celulósicos das fibras, acontece a 350 °C [22,24] . Acima de 380 °C ocorre a oxidação dos resíduos ricos em carbono [25] . É possível observar uma menor temperatura de oxidação dos resíduos para os compósitos em relação ao acetato de celulose plastificado, devido à presença de grupos oxidantes na lignina como as hidroxilas, o que acelera a oxidação dos produtos finais nos biocompósitos.…”

Preparation and thermal characterization of films containing liquid crystals in a cellulose acetate substrate for externally regulated applications

“…The DTG curve shows a main process centered at T ¼ 376 C, corresponding to the pyrolysis of the polymer skeleton backbone, and a secondary process centered at T ¼ 311 C that other authors assigned to deacetylation of CA. [18][19][20] Furthermore, a low weight-loss region appears around 100 C. This peak can be associated to the moisture content in the CA already observed by DSC. The mass loss calculated for this process was Dw ¼ 3.27%.…”

“…[18][19][20] In the DTG curves it is also possible to observe the appearance of new secondary processes at lower temperatures (T > 280 C). Such processes increase with the COC content and therefore can be associated to its presence in the films.…”

Characterization and Evaluation of Thermodynamic Parameters for Egyptian Heap Fired Rice Straw Ash (RSA)

“…The second stage within the 200-550 ºC range amounts to (5.2 -11.3 %) would correspond to the burning of the carbonaceous material in the samples. The last step in the range (550 -800 ºC) is of low mass (1.4 -2.6 %) and may represent the combustion of carbon that was firmly adsorbed on the surface of the solid materials remaining or the volatilization of some metal oxides (Kenawy I.M.M., 1994;Chetterjee P.K., 1968). Table 3, gives the results of the differential Thermal analysis of the tested heap fired rice straw ash samples.…”