  Several processes in the early universe might lead to the formation of
primordial black holes with different masses. These black holes would interact
with the cosmic plasma through accretion and emission processes. Such
interactions might have affected the dynamics of the universe and generated a
considerable amount of entropy. In this paper we investigate the effects of the
presence of primordial black holes on the evolution of the early universe. We
adopt a two-fluid cosmological model with radiation and a primordial black hole
gas. The latter is modelled with different initial mass functions taking into
account the available constraints over the initial primordial black hole
abundances. We find that certain populations with narrow initial mass functions
are capable to produce significant changes in the scale factor and the entropy.
