A continuous, solvent-free process for obtaining solvent-free, fine white powders of high molecular weight alternating copolymers of maleic anhydride and a C.sub.1 -C.sub.4 alkyl vinyl ether, without odor or taste, having the molecular structure (A--B).sub.n, where A is maleic anhydride, B is an alkyl vinyl ether and n is an integer indicative of the molecular weight of the copolymer, which compri