the present invention relates to a reactor and a process for continuous polymerization , where the reactor has an essentially tubular reactor housing . the reactor housing has a drive which runs along the geometric central axis in the flow direction and is configured as a central shaft . a rotatably arranged scraper or wiper is provided within the reactor housing ; the scraper or wiper has at least one scraper or wiper blade to run along an interior side of the reactor housing . the rotational movement of the scraper or wiper results in radial mixing of a stream within the reactor housing which dominates gravity effects and , by virtue of shaping of the scrapers or wipers , optionally makes plug flow or a loop flow or backflow within the reactor or else via an additional external pumped circulation system possible . this allows the reaction conditions in the axial direction of the reactor housing to be predicted and individually suitable reaction conditions to be set and controlled along the reactor housing , so that , in particular , a desired molecular weight distribution can be set .