The invention relates to a copolymer containing rigid polyamide PA blocks and flexible blocks, characterized in that it includes at least one carboxylic acid chain end blocked with a polycarbodiimide, said copolymer according to the invention being in noncrosslinked linear form. The invention also relates to the use of a polycarbodiimide in a process for manufacturing a copolymer containing rigid polyamide PA blocks and flexible blocks, including at least one carboxylic acid chain end, for improving the extrudability of the copolymer, the drawability of the copolymer, the abrasion resistance, the tear strength and the durability of the copolymer, without increasing its dispersity.