Natural rubber pyrolysis: Study of temperature-and thickness-dependence indicates dimer formation mechanism

A review of dipentene (dl-limonene) production from waste tire pyrolysis

“…In Fig. 4 the intramolecular cyclization of radical 1 yielding dipentene is presented [18,19,22,25].…”

“…Some researchers have propounded that dipentene can also be formed via dimerization of two isoprene monomers [16,19,20,25]. Groves et al based this assumption on the fact that the monomer/dimer ratio increases for higher temperatures and decreases for larger particle sizes [25].…”

Limonene ethers from tire pyrolysis oil

“…It has been known that tire pyrolysis oil contains DLlimonene produced by depolymerization of natural rubber occurring by b-scission at double bonds [1] or by monomer recombination via a Diesel-Alder reaction [2]. The major products of the isoprene dimer species are DL-limonene [1-methyl-4-(1-methylethenyl)-cyclohexene] and 1,4-dimethyl-4-vinylcyclohexene.…”

Pyrolysis of latex gloves in the presence of Y-zeolite

“…The formation of aromatic species is explained by secondary reactions involving cyclisation, dehydrogenation, and aromatization of short chain olefins through the Diels-Alder mechanism (Chen and Qian, 2002;Chien and Kiang, 1979;Groves et al, 1991).…”

“…Processing of waste rubber by pyrolysis has been intensively investigated in recent years, particularly with regard to scrap tyres (Berrueco et al, 2005;Conesa et al, 2004;Galvagno et al, 2007;Kyari et al, 2005;Li et al, 2005;Oledzka et al, 2006). The pyrolysis of natural rubber has also been investigated (Groves and Lehrle, 1992;Groves et al, 1991;Seidelt et al, 2006) as has the pyrolysis of natural rubbers main constituent, polyisoprene (Chen and Qian, 2002;Chiantore et al, 1995;Chien and Kiang, 1979). However, latex gloves present a special case because of the additives which are present, for example, calcium carbonate or cornstarch is used to powder the gloves.…”