  Context. Earlier work suggests that slowly rotating asteroids should have
higher thermal inertias than faster rotators because the heat wave penetrates
deeper into the sub-surface. However, thermal inertias have been determined
mainly for fast rotators due to selection effects in the available photometry
used to obtain shape models required for thermophysical modelling (TPM).
  Aims. Our aims are to mitigate these selection effects by producing shape
models of slow rotators, to scale them and compute their thermal inertia with
TPM, and to verify whether thermal inertia increases with the rotation period.
  Methods. To decrease the bias against slow rotators, we conducted a
photometric observing campaign of main-belt asteroids with periods longer than
12 hours, from multiple stations worldwide, adding in some cases data from WISE
and Kepler space telescopes. For spin and shape reconstruction we used the
lightcurve inversion method, and to derive thermal inertias we applied a
thermophysical model to fit available infrared data from IRAS, AKARI, and WISE.
  Results. We present new models of 11 slow rotators that provide a good fit to
the thermal data. In two cases, the TPM analysis showed a clear preference for
one of the two possible mirror solutions. We derived the diameters and albedos
of our targets in addition to their thermal inertias, which ranged between
3$^{+33}_{-3}$ and 45$^{+60}_{-30}$ Jm$^{-2}$s$^{-1/2}$K$^{-1}$.
  Conclusions. Together with our previous work, we have analysed 16 slow
rotators from our dense survey with sizes between 30 and 150 km. The current
sample thermal inertias vary widely, which does not confirm the earlier
suggestion that slower rotators have higher thermal inertias.
