This invention provides a polyether-polyamide block copolymer comprising polyether blocks and polyamide blocks having a heat of crystallization of no more than 30 mJ/mg, wherein the polyether-polyamide block copolymer has thermal plasticity, and a polymer alloy of the block copolymer and a polyamide having a heat of crystallization of no more than 30mJ/mg. This invention also provides a blood compatible material, especially a hollow fiber membrane comprising the polyether-polyamide block copolymer or the polymer alloy thereof.
