Abstract: The present invention relates to-a process and a device for the continuous manufacture of a polymer of an aromatic alkylene monomer e.g. styrene comprising a bulk polymerisation of the monomer and a devolatilization of the resulting polymer in at least two successive steps so as to separate the polymer from the unreacted monomer and the oligomers formed during the polymerisation. The process comprises conveying a first gas stream resulting from the first step of the devolatilization into a first zone Z1 for direct condensation and fractionation, removing a gas stream G1 comprising essentially the monomer from the top of Z1, and removing a liquid stream L1 rich in oligomers from the bottom of Z1, a portion of L1 being taken, cooled and then returned into Z1.