The influence of fine structure on the pyrolysis of cellulose. I. Vacuum pyrolysis

Abstract

synopsisThe effects of crystallinity, orientation and degree of polymerization on the vacuum pyrolysis of cellulose have been investigated. Natural, modified and manmade celluloses were characterized and the kinetics of their pyrolysis a t 251OC studied. The hightemperature pyrolysis of these samples was also investigated by means of DSC and TGA. At 251°C all of the samples showed a rapid, initial weight loss followed by a linear (weight loss)1/2 versus time dependency. Both the initial weight loss and the subsequent reaction rate were dependent upon the crystallinity of the sample. The reaction rate was shown to be inversely proportional to (DP)'/' and related to the orientation. Effects of crystallinity and orientation could also be seen in the DSC thermograms and in the apparent energies of activation. Results are interpreted in terms of probable mechanisms of the uncatalyzed pyrolysis of cellulose.

Analytical Techniques as a Tool to Understand the Reaction Mechanism

“…Apparently this temperature is in agreement with the thermogravimetric results on cellulose decomposition [48]. The reaction rate of cellulose decomposition was shown to be inversely proportional to the degree of polymerization and related to the orientation and crystallinity during thermal decomposition in vacuum [49][50][51]. Levoglucosan appears to be produced from the less ordered regions.…”

Cellulose nanofiber–titania nanocomposites as potential drug delivery systems for dermal applications

“…Moreover, thermal stability and heat resistance also have a close relationship with the crystallinity degree. In particular, crystalline regions in cellulose are much more stable than amorphous parts in cellulose [34][35][36] . Therefore, increase of crystallinity degree during chemical treatment also improved the heat resistance of PCNF and CNF_TiO 2 samples.…”

The Overview of Thermal Decomposition of Cellulose in Lignocellulosic Biomass

“…Briodo et al [87] found that crystalline cellulose and undergoes a large change in DP before weight loss occurs. Similarly, Basch and Lewin [88] proposed that if cellulose depolymerized by an unzipping process then the number of free chain ends, as reflected by DP, will influence the initiation rate. Radlein [46] presented that one cellulose sample which has been heated to 180 o C for several hours and has a very low DP appears to give an abnormally high yield of levoglucosan.…”