IUPAC definition : A residue from pyrolysis of organic material or tar distillation which is solid at
room temperature, consisting of a complex mixture of numerous, essentially aromatic
hydrocarbons and heterocyclic compounds. It exhibits a broad softening range instead
of a defined melting temperature. When cooled from the melt, pitches solidify without
crystallization.;
Scope note : the ratio of aromatic to aliphatic hydrogen depends mainly on the source of the starting
material. the hydrogen aromaticity (ratio of aromatic to total hydrogen atoms) varies
between 0.3 and 0.9. the aliphatic hydrogen in pitch is largely associated with alkyl
side chains substituted on aromatic rings. the content of heterocyclic compounds in
pitches varies depending on their origins. also, the softening temperature can vary
in a broad range between about 320kand 570kdepending on the molecular weight (relative
molecular mass) and composition of the constituents.;
A residue from pyrolysis of organic material or tar distillation which is solid at
room temperature, consisting of a complex mixture of numerous, essentially aromatic
hydrocarbons and heterocyclic compounds. It exhibits a broad softening range instead
of a defined melting temperature. When cooled from the melt, pitches solidify without
crystallization.