A process for preparing a polyamide (P) having a melting temperature T M by polymerization from a reaction mixture (RM) at a reaction temperature T R , wherein the reaction mixture (RM) comprises the following components: (A) at least one lactam (B) at least one diamine of the general formula (I) in which R 1 , R 2 independently of one another are selected from C 1 -C 10 alkanediyl, (C) at least one dicarboxylic acid derivative selected from the group consisting of a dicarboxylic acid of the general formula (II), a dicarboxylic ester of the general formula (III), and a dinitrile of the general formula (IV) HOOC-R 3 -COOH (II) R 5 OOC-R 4 -COOR 6 (III) NC-R 7 -CN (IV) in which R 3 , R 4 and R 7 independently of one another are selected from the group consisting of a bond, unsubstituted or at least monosubstituted C 1 -C 40 alkanediyl, and unsubstituted or at least monosubstituted C 6 -C 40 arylene, where the substituents are selected from the group consisting of F, Cl, Br, I, OR 8 , C 1 -C 10 alkyl, and C 6 -C 10 aryl, where R 8 is selected from the group consisting of H and C 1 -C 10 alkyl; R 5 and R 6 independently of one another are selected from the group consisting of unsubstituted or at least monosubstituted C 1 -C 20 alkyl, unsubstituted or at least monosubstituted C 6 -C 20 aryl, and unsubstituted or at least monosubstituted C 6 -C 20 aralkyl, where the substituents are selected from the group consisting of F, Cl, Br, I, OR 9 , and C 1 -C 10 alkyl, where R 9 is selected from the group consisting of H and C 1 -C 10 alkyl; and (D) water. (A) at least one lactam (B) at least one diamine of the general formula (I) in which R 1 , R 2 independently of one another are selected from C 1 -C 10 alkanediyl, (C) at least one dicarboxylic acid derivative selected from the group consisting of a dicarboxylic acid of the general formula (II), a dicarboxylic ester of the general formula (III), and a dinitrile of the general formula (IV) HOOC-R 3 -COOH (II) R 5 OOC-R 4 -COOR 6 (III) NC-R 7 -CN (IV) in which R 3 , R 4 and R 7 independently of one another are selected from the group consisting of a bond, unsubstituted or at least monosubstituted C 1 -C 40 alkanediyl, and unsubstituted or at least monosubstituted C 6 -C 40 arylene, where the substituents are selected from the group consisting of F, Cl, Br, I, OR 8 , C 1 -C 10 alkyl, and C 6 -C 10 aryl, where R 8 is selected from the group consisting of H and C 1 -C 10 alkyl; R 5 and R 6 independently of one another are selected from the group consisting of unsubstituted or at least monosubstituted C 1 -C 20 alkyl, unsubstituted or at least monosubstituted C 6 -C 20 aryl, and unsubstituted or at least monosubstituted C 6 -C 20 aralkyl, where the substituents are selected from the group consisting of F, Cl, Br, I, OR 9 , and C 1 -C 10 alkyl, where R 9 is selected from the group consisting of H and C 1 -C 10 alkyl; and R 3 , R 4 and R 7 independently of one another are selected from the group consisting of a bond, unsubstituted or at least monosubstituted C 1 -C 40 alkanediyl, and unsubstituted or at least monosubstituted C 6 -C 40 arylene, where the substituents are selected from the group consisting of F, Cl, Br, I, OR 8 , C 1 -C 10 alkyl, and C 6 -C 10 aryl, where R 8 is selected from the group consisting of H and C 1 -C 10 alkyl; R 5 and R 6 independently of one another are selected from the group consisting of unsubstituted or at least monosubstituted C 1 -C 20 alkyl, unsubstituted or at least monosubstituted C 6 -C 20 aryl, and unsubstituted or at least monosubstituted C 6 -C 20 aralkyl, where the substituents are selected from the group consisting of F, Cl, Br, I, OR 9 , and C 1 -C 10 alkyl, where R 9 is selected from the group consisting of H and C 1 -C 10 alkyl; and (D) water. <EOS>