  We have revealed the decisive role of grain-boundary-induced strain fields in
electron scattering in polycrystalline graphene. To this end, we have
formulated the model based on Boltzmann transport theory which properly takes
into account the microscopic structure of grain boundaries (GB) as a repeated
sequence of heptagon-pentagon pairs. The effect of strain field is described
within the deformation potential theory. For comparison, we consider the
scattering due to electrostatic potential of charged grain boundary. We show
that at naturally low GB charges the deformation potential scattering dominates
and leads to physically reasonable and, what is important, experimentally
observable values of the electrical resistivity. It ranges from 0.1 to 10
k$\Omega $$\mu $m for different types of GBs with a size of 1 $\mu$m and has a
strong dependence on misorientation angle. For low-angle highly charged GBs,
two scattering mechanisms may compete. The resistivity increases markedly with
decreasing GB size and reaches values of 60 k$\Omega $$\mu $m and more. It is
also very sensitive to the presence of irregularities modeled by embedding of
partial disclination dipoles. With significant distortion, we found an increase
in resistance by more than an order of magnitude, which is directly related to
the destruction of diffraction on the GB. Our findings may be of interest both
in the interpretation of experimental data and in the design of electronic
devices based on poly- and nanocrystalline graphene.
