Foamable compositions which are usable for the manufacture of foamed, flexible, heat resistant, thermoplastic elastomeric articles, and which comprise at least:
- (a) 100 parts by weight of one or more selectively hydrogenated block copolymers, having at least two resinous blocks A of non-hydrogenated predominantly polymerized monovinyl arene, and a selectively hydrogenated elastomeric block B, wherein said block B prior to hydrogenation being predominantly a polymerized conjugated diene of polybutadiene, said block copolymer having a total apparent molecular weight from 250-600 kg/mole, and containing polymerized monovinyl arene blocks of true molecular weight of from 18 to 60 kg/mole, and said polymerized monovinyl arene content is in the range of from 20 to 35 wt %,
- b) 5 to 50 parts by weight per 100 parts by weight of component (a) of one or more selectively hydrogenated block copolymers having at least two resinous blocks A′ of non-hydrogenated predominantly polymerized monovinyl arene, and an selectively hydrogenated elastomeric block B′, wherein said block B′ prior to hydrogenation has been derived from a polymerized conjugated diene or dienes as a major component which may be mixed with 25 or less wt. % of other copolymers, and said block copolymer having a total apparent molecular weight in the range of from 50 to 180 kg/mole, while the resinous blocks A′ shown an true molecular weight in the range of from 3 to 20 kg/mole,
- c) from 42 to 80 parts by weight per 100 parts by weight of component (a) of a linear crystalline polymer comprising propylene as major component, with a Vicat softening temperature in the range of from 130° C. to 180° C. and a MFR in the range of from 0.5 to 30 dg/min and a polydisperity index of at least 4.5,
- (d) from 100 to 250 parts by weight per 100 parts by weight of component (a) of a softener compatible with blocks B and B′,
- (e) from 0.01 to 3 wt %, relative to the weight of the primary components (a) up to (e) of a solid chemical nucleating agent of the endothermic group in combination with a blowing agent, and optionally
- (f) one or more secondary components selected from PPO and/or any resins compatible with block copolymer component (a), antioxidants, UV-stabilizers, flame retardants, surface modifying agents and inorganic fillers.