ABSTRACT
A processability difference between extrusion (including single-stage blow molding) and injection molding exists in that in extrusion the molten polymer is forced through a die into the atmosphere and then cooled to shape, while in injection molding the material is fully enclosed and cooled under pressure. Although extrusion is arguably the more demanding of a material's rheological properties, such data are important in injection molding for mold design while variations can cause mold filling variability, weld line weaknesses, shrinkage, warpage, and dimensional variations as well as final mechanical property deficiencies.
