Experimental and Theoretical Study of Cis-1,4-polyisoprene Pyrolysis

Pyrolysis of natural rubber (NR) is an environmentally friendly solution as a clean recycling process. The pyrolysis of cis-1,4-polyisoprene is studied with a focus on the quantity and quality of final products from experimental and theoretical aspects. Although much research has been conducted on the experimental pyrolysis of NR, but little information is available about the theoretical part of this process. For experimental pyrolysis, a small-scale science lab quasi-reactor was used and residue after pyrolysis was identified by FT-IR and GC-MS analyses. The ReaxFF molecular dynamic simulations as a novelty method are performed at different temperatures. Increasing temperature promotes the dissociation of chemical bonds between the monomers. It was found that, at the beginning of the simulations, the C-C bonds between monomers break and form C5. This result is consistent with experimental observations. Also, the main gas product is CH4. The fragmentation paths involve the breakage of C-H and C-C bonds. It means that the C-C bond of side methyl groups in the main chain is broken and subsequently methyl radical is formed. Then, several C-H bonds are broken conducting to form H free radicals, Next, CH3 and H free radicals combine to form the CH4 molecule.