Preparation of block copolyamides

Block copolyamides have been prepared by polymerization of amino‐ and carboxyl ended propolyamides of relatively low molecular weights. The structures of the block copolyamides were ascertained from the melting point vs. composition curves, the solubilities in methanol, and by dilatometry, in which two breaks, each corresponding to the melting temperature of one type of block segments, were observed. The amide interchange reaction, which disturbs the block regularity, is depressed at temperatures below 250°C. No practical differences in the thermal properties were observed between the two block polymers prepared by prepolyamide polymerization and by amide interchange of homopolyamides.