An expandable polymeric composition in bead form with enhanced processability comprising: i. a polymeric base consisting of: a) a vinyl aromatic polymer and/or b) a co-polymer containing from 50% to 99% by weight of vinyl aromatic monomers and from 1% to 50% by weight of at least one type of alkyl ester having from 1 to 18 carbon atoms derivative of acrylic or methacrylic acid, wherein the polymeric base comprises at least 2% by weight of (b) or the polymeric base comprises only (a); ii. from 0.2 to 10 parts by weight measured on 100 parts of polymeric base (i) of an expanding agent, and iii. alternatively: A) from 0 to 10 parts by weight measured on 100 parts of polymeric base (i) of an additive with plasticizer effect when (i) comprises at least 2% by weight of (b), or B) from 0.3 to 10 parts by weight measured on 100 parts of polymeric base (i) of an additive with plasticizer effect when (i) comprises only (a); said polymeric composition being characterized in that: • the molecular weight at the peak maximum Mp of (i) is comprised from 130 kDa to 190 kDa and the centrifuge average molecular weight Mz of (i) is comprised from 430 kDa to 900 kDa, • the difference (DTg) between the glass-transition temperature of a reference vinyl aromatic polymer and the glass-transition temperature of a polymeric composition consisting of said (i) and optionally (iii) is within the range from 1°C to 8°C; the reference vinyl aromatic polymer having the molecular weight distribution of (i) and composition corresponding to the vinyl aromatic fraction of (i); said molecular weights and molecular weight distribution being determined by size exclusion chromatography. i. a polymeric base consisting of: a) a vinyl aromatic polymer and/or b) a co-polymer containing from 50% to 99% by weight of vinyl aromatic monomers and from 1% to 50% by weight of at least one type of alkyl ester having from 1 to 18 carbon atoms derivative of acrylic or methacrylic acid, wherein the polymeric base comprises at least 2% by weight of (b) or the polymeric base comprises only (a); a) a vinyl aromatic polymer and/or b) a co-polymer containing from 50% to 99% by weight of vinyl aromatic monomers and from 1% to 50% by weight of at least one type of alkyl ester having from 1 to 18 carbon atoms derivative of acrylic or methacrylic acid, wherein the polymeric base comprises at least 2% by weight of (b) or the polymeric base comprises only (a); ii. from 0.2 to 10 parts by weight measured on 100 parts of polymeric base (i) of an expanding agent, and iii. alternatively: A) from 0 to 10 parts by weight measured on 100 parts of polymeric base (i) of an additive with plasticizer effect when (i) comprises at least 2% by weight of (b), or B) from 0.3 to 10 parts by weight measured on 100 parts of polymeric base (i) of an additive with plasticizer effect when (i) comprises only (a); said polymeric composition being characterized in that: • the molecular weight at the peak maximum Mp of (i) is comprised from 130 kDa to 190 kDa and the centrifuge average molecular weight Mz of (i) is comprised from 430 kDa to 900 kDa, • the difference (DTg) between the glass-transition temperature of a reference vinyl aromatic polymer and the glass-transition temperature of a polymeric composition consisting of said (i) and optionally (iii) is within the range from 1°C to 8°C; the reference vinyl aromatic polymer having the molecular weight distribution of (i) and composition corresponding to the vinyl aromatic fraction of (i); said molecular weights and molecular weight distribution being determined by size exclusion chromatography. A) from 0 to 10 parts by weight measured on 100 parts of polymeric base (i) of an additive with plasticizer effect when (i) comprises at least 2% by weight of (b), or B) from 0.3 to 10 parts by weight measured on 100 parts of polymeric base (i) of an additive with plasticizer effect when (i) comprises only (a); said polymeric composition being characterized in that: • the molecular weight at the peak maximum Mp of (i) is comprised from 130 kDa to 190 kDa and the centrifuge average molecular weight Mz of (i) is comprised from 430 kDa to 900 kDa, • the difference (DTg) between the glass-transition temperature of a reference vinyl aromatic polymer and the glass-transition temperature of a polymeric composition consisting of said (i) and optionally (iii) is within the range from 1°C to 8°C; the reference vinyl aromatic polymer having the molecular weight distribution of (i) and composition corresponding to the vinyl aromatic fraction of (i); said molecular weights and molecular weight distribution being determined by size exclusion chromatography. • the molecular weight at the peak maximum Mp of (i) is comprised from 130 kDa to 190 kDa and the centrifuge average molecular weight Mz of (i) is comprised from 430 kDa to 900 kDa, • the difference (DTg) between the glass-transition temperature of a reference vinyl aromatic polymer and the glass-transition temperature of a polymeric composition consisting of said (i) and optionally (iii) is within the range from 1°C to 8°C; the reference vinyl aromatic polymer having the molecular weight distribution of (i) and composition corresponding to the vinyl aromatic fraction of (i);