NOVELTY - Producing expandable granules, comprises e.g. (i) providing a polymer component comprising (a) a styrene polymer component which is formed from (a1) at least one styrene polymer and (a2) at least one styrene copolymer different from (a1), and (b) at least one thermoplastic polymer, (ii) heating the polymer component to form a polymer melt (iii) introducing a physical blowing agent component into the polymer melt to form a foamable melt, (iv) homogenizing the mixture, and (v) optionally adding additives to the polymer component in at least one of the steps (i), (ii), (iii) and/or (iv).    USE - The method is useful for producing molded parts (claimed) and particle foam molded parts for wind turbines.    ADVANTAGE - The method produces the expandable granules exhibiting enhanced solvent resistance, enhanced thermal stability and enhanced mechanical rigidity, ensures low water absorption, requires less time, and avoids degradation of the material.    DETAILED DESCRIPTION - Producing expandable granules, comprises: (i) providing a polymer component comprising (a) a styrene polymer component (90-100 wt.%, based on polymer component), which is formed from ((a1) at least one styrene polymer (30-100 wt.%, based on polymer component), each containing copolymerized styrene, alpha-methyl styrene or copolymerized mixture of alpha-methyl styrene and styrene (60-85 wt.%, based on styrene polymer) and at least one copolymerized monomer (15-40 wt.%, based on styrene polymer) including maleic acid anhydride or maleimide and (a2) at least one styrene copolymer different from (a1) (0-70 wt.%, based on polymer component) including copolymerized styrene, alpha-methyl styrene or the copolymerized mixture of styrene and alpha-methyl styrene (60-82 wt.%, based on styrene copolymer different from (a1)) and copolymerized acrylonitrile (18-40 wt.%, based on styrene copolymer different from (a1)), and (b) at least one thermoplastic polymer (0-10 wt.% based on polymer component) including aromatic polyether, polyolefin, polyacrylate, polycarbonate, polyester, polyamide, polyethersulfone, polyether ketone or polyether sulfide; (ii) heating the polymer component to form a polymer melt; (iii) introducing a physical blowing agent component (1-10 wt.%, based on polymer component) into the polymer melt to form a foamable melt; (iv) homogenizing the mixture; (v) optionally adding additives to the polymer component in at least one of the steps (i), (ii), (iii) and/or (iv); (vi) extruding the polymer melt comprising blowing agent through a nozzle plate; and (vii) granulating the melt comprising blowing agent in a liquid-filled chamber under a pressure of 1.5-15 bar to form the granulate. INDEPENDENT CLAIMS are also included for:    (1) the expandable granules, whose particles respectively contain at least 10 hollow spaces/mm3 with the size of 1-200 mu m, comprising the polymer component as mentioned above, where the styrene polymer component has a glass transition temperature of greater than or equal to 130 degrees C; and    (2) molded parts obtainable from the above produced expandable granulates, which exhibit a density of 15-300 g/l and a maximum dimensional change of 3% upon thermal loading of at least 130 degrees C.