respectively, indicating that more pyrolysis vapor was generated
by adding more sawdust.
A smooth line in the unmixed rubber curve and fold line points
in the curves with sawdust at the temperature of 366 C were
observed (Fig. 2a). When the temperatures were lower than
366 C, the major pyrolysis was on sawdust. As the temperatures
exceeded 366 C, the major pyrolysis component would be on
the rubber. The decomposition temperature of rubber was 310–
490 C (Fig. 2b), while 270–380 C for sawdust (Ren et al., 2012).
The rubber macromolecules were broken down into aromatic
hydrocarbon and macromolecule condensation coke-like substance
at the low temperature stage (Williams and Taylor, 1993).
As the temperature increased, many small molecule chain hydrocarbons,
such as alkanes and olefins, were generated as a result
of the secondary reaction. Meanwhile, the aromatic substances
were rebuilt because of the Diels–Alderpolymerization (Islam
et al., 2009) by the small molecular chain of hydrocarbons. With
the adding of sawdust, the oxygen-reaction in rubber pyrolysis
was accelerated, resulting in a creation of oxygen-containing derivatives
of hydrocarbons (Table 3) and a great amount of oxygencontaining
small molecules gases, such as CO, CO2, and H2O. Most
oxygen-containing derivatives of hydrocarbons can condensed into
pyrolysis oil and small molecules gases that can be collected for
combustion or other uses.