  We present fully general-relativistic simulations of binary neutron star
mergers with a temperature and composition dependent nuclear equation of state.
We study the dynamical mass ejection from both quasi-circular and
dynamical-capture eccentric mergers. We systematically vary the level of our
treatment of the microphysics to isolate the effects of neutrino cooling and
heating and we compute the nucleosynthetic yields of the ejecta. We find that
eccentric binaries can eject significantly more material than quasi-circular
binaries and generate bright infrared and radio emission. In all our
simulations the outflow is composed of a combination of tidally- and
shock-driven ejecta, mostly distributed over a broad $\sim 60^\circ$ angle from
the orbital plane, and, to a lesser extent, by thermally driven winds at high
latitudes. Ejecta from eccentric mergers are typically more neutron rich than
those of quasi-circular mergers. We find neutrino cooling and heating to
affect, quantitatively and qualitatively, composition, morphology, and total
mass of the outflows. This is also reflected in the infrared and radio
signatures of the binary. The final nucleosynthetic yields of the ejecta are
robust and insensitive to input physics or merger type in the regions of the
second and third r-process peaks. The yields for elements on the first peak
vary between our simulations, but none of our models is able to explain the
Solar abundances of first-peak elements without invoking additional first-peak
contributions from either neutrino and viscously-driven winds operating on
longer timescales after the mergers, or from core-collapse supernovae.
