TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The vinyl aromatic polymer contains preferably 15-40 wt.% of star branched vinyl aromatic polymer.Preferred Properties: The vinyl aromatic polymer has mean melt strength of more than 12.5 cN at 210 degreesC and VICAT softening temperature of preferably 105-115 degreesC.The vinyl aromatic polymer has melt flow at condition G of less than 2.5 g/10 minutes.The vinyl aromatic polymer preferably contains 3-10 wt.% of rubbery polymer.Preferred Method: The vinyl aromatic polymer is prepared by solution or bulk polymerization.Preferred Polymer: The vinyl aromatic polymer is preferably homopolymer and is polystyrene.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Monomer: The 8-12C vinyl aromatic monomer is selected from styrene, alpha-methyl styrene and p-methyl styrene.Preferred Initiator: The tetrafunctional initiator is chosen from tetrakis-(t-amylperoxycarbonyloxymethyl)methane and tetrakis-(t-butylperoxycarbonyloxymethyl)methane.Preferred Blowing Agent: The blowing agent may contain 20-95 wt.% of blowing agent selected from 4-6C alkane preferably pentane and/or butane, and 80-5 wt.% of chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) or 30-95 wt.% of carbon dioxide and 70-5 wt.% of blowing agent selected from 4-6C alkanes and CFCs, HFCs and HCFCs or 70-95 wt.% of carbon dioxide and 30-5 wt.% of 4-6C alkane. EXAMPLE - Styrene monomer, 0.028 weight % of JWEB50(TM) (polyether tetrakis (t-butylperoxy carbonate)) and 0.1 wt.% of zinc stearate were fed into the continuously stirred tank reactor maintained at 120 degreesC. The residence time in first reactor was 2.5 hours. The partially polymerized mixture from first reactor was fed to second continuously stirred tank reactor maintained at 140 degreesC. The residence time in the second reactor was 1 hour. The resulting polymer was then devolatilized and pelletized. The conditions were such that 64% of the polymer was thermally initiated and linear. About 36% of the polymer was initiated by the peroxide and half of the resulting polymer was star branched. The weight average molecular weight, number average molecular weight and polydispersity (Mw/Mn) of the polymer were 342000, 141000 and 2.42, respectively. The polymer had mean melt strength of 37.44 cN at 190degreesC, mean stretch ratio of 79.9% at 190 degreesC, mean peak melt strength of 43.7 at 190degreesC, mean melt strength of 14.56 cN at 210 degreesC, mean stretch ratio of 236.5% at 210 degreesC, mean peak melt strength of 17.73 at 210 degreesC, Notched Izod of 0.34 ft-lb/inch, melt flow condition G of 1.4 g/10 minutes and VICAT softening temperature of 108.9 degreesC.    The obtained polymer was extrusion foamed using 5 wt.% of isopentane as blowing agent to form polymeric foam. The polymeric foam has mean load at maximum load of 2.84 lbs, mean displacement at maximum load of 1.46 inch, mean load at 1.5 deflection of 2.82 lbs, mean slope of 3.58 lbs/inch, mean part weight 4.59 g, mean sidewall thickness of 0.105 inches, mean foam density of 2.92 lbs/ft3, mean orientation along MD of 56.07%, mean orientation along TD of 56.55%, number of cells across sheet thickness along TD of 38, average cell diameter of 0.0702 mm. The number of parts with sidewall cracks was nil. The polymeric foam had fine cell structure and spherical cell shape.