Thermal degradation of cellulosic materials

The mechanism of thermal degradation of cellulose appears to include two reactions. The first reaction consists of dehydration and the second one of scission of C-O bonds in the chains between the rings or within the rings [457], This can give rise to levoglucosan [457]  

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Thermal degradation of cellulosic materials proceeds through a complex series of concurrent and consecutive chemical reactions. Fig. 1 provides an outline of the general sets of the degradation reac-... 

The rate and kinetics of the thermal degradation of cellulosic materials have been investigated under a variety of conditions. However, these studies often relate to one of the physical effects produced by the overall process of heating or pyrolysis, instead of the kinetics of the individual chemical reactions involved. Consequently, the results are controversial and confusing. The variation of the results obtained under different conditions provides a vivid indication of the complexity of the reactions involved and the limited value of the overall kinetic data. 

Rate and Energy of Activation for Thermal Degradation of Cellulosic Materials ... 

The normal degradation of cellulose to the flammable tar, levoglucosan, is reduced and the charring of this compound is promoted. Shafizadeh and coworkers used thermogravimetric (TG) and thermal evolution analysis (TEA) data, to confirm two different mechanisms involved in flameproofing cellulosic materials ... 

Eco-friendly biodegradable polymers and biocomposites are relatively novel materials that can contribute to reduce the dependence on fossil sources. Because of their renewable nature and biodegradability, environmentally benign composite materials with properties comparable to those of some widely used commodities can be produced. Py-GC/MS has developed as a useful tool for the study of thermal degradation of such polymers and composites, and many studies have recently been published for biodegradable polymers, such as polycaprolactone (PCL), polyhydroxyalcanoates (PHAs) and their copolymers,poly(lactic acid) (PLA), and carbohydrates, including starch and cellulose. 

The self-ignition temperature of PVF film is 390°C. The limiting oxygen index (LOI) for PVF is 22.6% (120), which can be raised to 30% in antimony oxide-modified film (121). HF and a mixture of aromatic and aliphatic hydrocarbons (122) are generated from the thermal degradation of PVF. Toxicity studies, ie survival and time to incapacitation, of polymers, cellulosics (123,124), and airplane interior materials (125) expose mice to pyrolysis products and show PVF thermal degradation products to have relatively low toxicity. 

Analysis of the effect of cellulose derivatives on PP, PS and PE thermal degradation showed that the presence of cellulosic materials produced a slight increase in the degradation temperature associated with a change in the degradation mechanism of PP. The yield of monomer and trimer from the thermal decomposition of PS was reduced in the presence of cellulose derivatives, indicating that radical chain reactions are hindered by the presence of lignocellulosic char. On the other hand, the effect of PP on the thermal decomposition... 

The thermal degradation characteristics of lignocellulosic materials are strongly influenced by their chemical composition (cellulose, hemicellulose and lignin contents). The proportions of these constituents in rice husks vary to some extent between varieties, which may influence their kinetic behaviour 547250. The results of thermal degradation of rice husks show the two-step nature of the TG curves and the dual peak characteristics of the DTG curves, confirming the presence of two distinct reaction zones during... 

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