Macromolecular structure and coal pyrolysis
1988; Elsevier BV; Volume: 20; Linguagem: Inglês
10.1016/0378-3820(88)90003-3
ISSN1873-7188
Autores Tópico(s)Coal and Coke Industries Research
ResumoA molecular level explanation for the dilatometric behavior of an hvAb coal is sought. The macromolecular network structure of bituminous coals is described with emphasis on the non-covalent interactions responsible for coals being glasses at room temperature. The existence of a glass to rubber transition in coals at 600 K detected by both DSC and NMR is described and related to the initial softening and contraction observed in the dilatometer. The relationship between the phase transition and the pyrolysis chemistry simultaneously occurring is discussed and it is concluded that it is not known whether covalent bond cleavage is a cause of the phase transition. Covalent bond cleavages are not necessary for the transition to occur. In coking coals, thermally induced cross linking begins at temperatures well above Tg and after most tars have been released from the coal. The high degree of structural anisotropy of all coals is revealed by solvent swelling. Its role in coke forming processes is unknown.
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