u00b0 f air with dew point u2212 40 u00b0 c for 24 hrs or until the moisture level was below 250 ppm the dry blend was fed to a single barrel extruder set for 199 u00b0 c 390 u00b0 f temperature and melt kneaded to form a heat layer composition having 3000 ppm jc30 cas in the natureworks 4060d pla b core layer a core layer b composition blend of 85 natureworks crystalline pla 4032 and 15 amorphous pla natureworks 4060d was dried with 74 u00b0 c 165 u00b0 f air of dew point u2212 40 c for 24 hours or until the moisture level was below 250 ppm this dry blend was fed to a single screw extruder and melt kneaded at temperature of 210 u00b0 c 410 u00b0 f to form the melt core composition c polymeric barrier receiving layer antiblocking additive fuji silysia grade 310p silica u201c 310p silica u201d of 2 7 u03bcm particle size was compounded at 10 wt into a 19 wt isophthalic acid 81 wt terephthalic acid copolyester of ethylene glycol to form antiblocking masterbatch mb3 the isophthalic acid copolyester ipet had a solution intrinsic viscosity of 0 70 as determined from a single point measurement at 0 5 wt concentration in dichloroacetic acid at 25 u00b0 c the masterbatch was prepared in a twin screw extruder equipped with vacuum devolatilization and was then extruded as strand and pelletized a polymeric barrier receiving layer c composition.