AN INVESTIGATION OF THE PARISON SAGGING BEHAVIOR DURING THE EXTRUSIONBLOW MOLDING OF COPOLYESTER PETG

The shear and elongational rheological behaviours of a copolyester the rmoplastic were determined. The copolyester was then extrusion blow mo ulded into bottles. The parison extrusion behaviour was studied as the output rate and melt temperature were varied. The inflation behaviour was studied as a function of the inflation pressure. The processing b ehaviour was correlated to the rheological properties of the polymer m elt. A mathematical model of the extrusion blow moulding process devel oped for polyolefins was tested to verify its application to the copol yester material. From the experimental results it has been shown that the copolyester has suitable rheological behaviour for the extrusion b low moulding process. The process model would require additional param eters to be considered before it could be used for prediction of copol yester melt behaviour in extrusion blow moulding.