Fully bonded single-layer waterbar

A method for producing a single-layer waterbar, the method comprising extruding a melt-processed starting composition through an extruder die to provide an extruded profile, wherein the starting composition comprises:

• a) 40-70 wt.-%, of at least one polymer P,
• b) 30-60 wt. %, of a least one solid particulate filler F,
• c) 0.1-1.5 wt.-% of at least one chemical blowing agent CBA, wherein
• the melt-processed starting composition comprises a blowing gas, which is released from the melt-processed starting composition through surface(s) of the extruded profile discharged from the extruder die, and
• the blowing gas is released from the melt-processed starting composition through surface(s) of the extruded profile discharged from the extruder die to form an open pore structure in the extruded profile.