  We have obtained HST/STIS data for a total of eleven polars as part of a
program aimed to compile a homogeneous database of high-quality far-ultraviolet
(FUV) spectra for a large number of cataclysmic variables (CVs). Of the eleven
polars, eight were found in a state of low accretion activity (V347Pav, VVPup,
V834Cen, BLHyi, MRSer, STLMi, RXJ1554.2+2721 and V895Cen) and three in a state
of high activity (CDInd, ANUMa and UWPic). The STIS spectra of the low-state
polars unambiguously reveal the photospheric emission of their white dwarf (WD)
primaries. We have used pure hydrogen WD models to fit the FUV spectra of the
low-state systems (except RX J1554.2+2721, which is a high-field polar) in
order to measure the WD effective temperatures. In all cases, the fits could be
improved by adding a second component, which is presumably due to residual
accretion onto the magnetic pole of the WD. The WD temperatures obtained range
from 10800K to 14200K for log g = 8.0. Comparing the WD temperatures of polars
to those of non-magnetic CVs, we find that at any given orbital period the WDs
in polars are colder than those in non-magnetic CVs. The temperatures of polars
below the period gap are consistent with gravitational radiation as the only
active angular momentum loss mechanism. The differences in WD effective
temperatures between polars and non-magnetic CVs are significantly larger above
the period gap, suggesting that magnetic braking in polars might be reduced by
the strong field of the primary.
