1300958 Polyamides SOC NATIONALE DES PETROLES D'AQUITAINE 30 Dec 1969 [31 Dec 1968] 63362/69 Heading C3R In the activated anionic solution polymerization of lactams having more than 10 C atoms in the ring in a continuously agitated organic solvent the temperature is progressively raised so that no temperature at or above 90‹ C. is reached until the percentage P of polymer powder formed by weight of monomer plus polymer is at least aT-b where T is the temperature and a and b are constants determined experimentally by plotting the value of P at which lump formation ceases to occur at various temperatures. For lauroyl lactam, which is the only lactam mentioned in the Specification, a= 0À5 and b = 40. For this lactam P is preferably within the range 0À5T-40 to 24(T-80)<SP>1</SP>/ 3 . Control of the rate of temperature rise may be effected on a time scale determines experimentally. Various conventional catalysts, activators and solvents are mentioned. 1 to 15 wt. per cent of polymer powder may be dispersed in advance in the monomer and all or part of the activator and/or catalyst introduced continuously at least during a part of the polymerization. The process is stated to give a fine powder product without lump formation. Reference is made to Specifications 1,300,956 and 1,300,957.