Abstract: The invention relates to a novel process for the anionic polymerization of lactams, in which: (a) (i) a catalyst capable of creating a lactamate and (ii) a regulator chosen from the amides of formula R1—NH—CO—R2, in which R1 can be substituted with a radical R3—CO—NH— or R3—0— and in which R1, R2 and R3 denote an aryl, alkyl or cycloalkyl radical, are dissolved in the molten lactam; the temperature of this reaction mixture being between the melting point of the lactam and 15° C. higher in order to ensure its good stability, (b) the solution from step (a) is introduced into a mixing device and is then heated to a temperature which is sufficient to obtain bulk polymerization of the lactam in no more than 15 minutes. (b) is usually a continuous reactor, for example an extruder; however, it can be replaced with a mold.

Abstract: The process for the manufacture of (co)polymer powders by aqueous suspension polymerization of at least one monomer which is polymerizable in suspension is conducted in the presence of at least one free-radical generator as catalyst, of at least one dispersing agent and, in addition, of at least one inhibitor scavenging free radicals of at least one complexing agent.

Abstract: Polyimides or poly(amide-imides), especially those containing a polysiloxane unit are improved by heating such polymers or their polyamic acid precursors with a polyfunctional aromatic compound. The polyfunctional aromatic compound is one which contains at least two reactive groups which may be --NH.sub.2, --COOH, --OH or secondary amino groups with at least one of the reactive groups being --NH.sub.2 or --COOH.

Abstract: Anionic polymerization of lactams is carried out in an extruder into which at least one lactam, at least one catalyst and at least one activating agent are introduced and wherein the mixture of said substances is polymerized prior to being extruded through an extrusion die. The output rate of the polymerized substance is controlled by transfer means, such as a metering pump, arranged between the outlet of the body of the extruder and the extrusion die.

Abstract: The instant invention relates to a method for purifying lactams wherein the lactam to be purified is contacted in the fused state with inorganic adsorption agents.The said method comprises contacting the lactam to be purified in the fused state with an inorganic adsorbent, then separating the lactam from the adsorbent and regenerating said adsorbent if desired, wherein said adsorbent is impregnated with at least one impregnation compound selected from the group consisting of an acid and the alkali metal salts which are thermally stable and exert no action on the lactam at temperatures lower tha 250.degree.C.