Copolymers comprising polyamide blocks and polyether blocks and having improved mechanical properties

A process for producing a shaped article, said article comprising a block copolymer PAX.Y/PE comprising polyamide (PA) blocks alternating with polyether (PE) blocks, wherein said process comprises the steps of:

• a) preparing homopolyamide blocks PAX.Y by polycondensation of linear aliphatic diamines having X carbon atoms and dicarboxylic acids having Y carbon atoms, the dicarboxylic acids introduced in excess with respect to the stoichiometry, wherein said PAX.Y is selected from the group consisting of PA 10.12;
• PA 6.18;
• PA 6.14;
• PA 10.14;
• and PA 12.12,
• b) reacting said homopolyamide blocks with polyether PE blocks in the presence of a catalyst to produce a block copolymer PAX.Y/PE, wherein said PE blocks are selected from the group consisting of:
• (i) PE blocks comprising hydroxyl ends, otherwise known as PE diol blocks, so that the bonds between the PA blocks comprising carboxyl ends and the PE diol blocks are ester bonds;
• and
• (ii) PE blocks comprising NH2 ends in the case where Y has a number of carbon atoms of greater than 14, so that the bonds between the PA blocks comprising carboxyl ends and the PE blocks comprising NH2 ends are amide bonds;
• wherein said PE blocks comprise from 0 to 39% by weight of polytrimethylene ether glycol PO3G and/or polyethylene glycol PEG and from 100 to 61% by weight of polyether other than PO3G or PEG (% by weight, expressed with respect to the total weight of the PE blocks);
• c) forming said block copolymer PAX.Y/PE into a fabric, film, sheet, rod, pipe, injection-molded component, or a shoe sole;
• wherein the crystallinity of the PAX.Y block is greater than the crystallinity of a PA12 block of the same size and/or the PA/PE phase separation of said copolymer PAX.Y/PE is greater than that of a copolymer PA12/PTMG composed of PA12 blocks of the same size as the PAX.Y blocks of said copolymer PAX.Y/PE and of polytetramethylene glycol PTMG blocks of the same size as the PE blocks of the PAX.Y/PE copolymer;
• wherein the copolymer PAX.Y/PE has an improved flexural modulus of at least 300 MPa greater than a copolymer PA12/PTMG with the same size of PA block and with the same size of PE block respectively, after conditioning at 23° C. and 50% relative humidity for 14 days, wherein said copolymer PAX.Y/PE does not break after 150,000 cycles during a flex fatigue test at −10° C. (Ross Flex Test).