EXPANDABLE VINYL AROMATIC POLYMERIC COMPOSITIONS

The present patent application relates to an expandable polymeric composition with an enhanced processability which comprises: i. a polymeric base comprising: a) from 0% to 100% by weight measured on the total base (i) of a vinyl aromatic polymer, b) from 100% to 0% by weight measured on the total base (i) of a co-polymer containing from 50% to 99% by weight of vinyl aromatic monomers and from 1% to 50% of at least one type of alkyl ester having from 1 to 18 carbon atoms, derivative of acrylic or methacrylic acid, 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 a plasticizing 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 a plasticizing effect when (i) comprises only (a), said polymeric composition being characterized in that: ? the molecular mass at the maximum peak Mp of (i) ranges from 130 kDa to 190 kDa and the centrifugal average molecular mass Mz of (i) ranges from 430 kDa to 900 kDa, ? the difference in the glass-transition temperature (DTg) measured between a vinyl aromatic polymer having a molecular weight distribution (MWD) of (i) and composition of the vinyl aromatic fraction alone of (i), and a polymeric composition consisting of (i) and (iii), ranges from 1?C to 8?C.