stretch blow molding

Stretch blow molding is a technique used in the plastics industry to create hollow plastic containers. It begins with a heated thermoplastic tube, called a parison, which is sealed at one end and then inflated with air, much like a balloon, inside a cool mold. This process allows the plastic to take on the shape of the mold. In stretch blow molding, the parison is expanded both in diameter and length, which biaxially orients the polymer. This orientation enhances the material's strength and, in the case of polyethylene terephthalate (PET), increases its crystallinity. This method is used to produce various containers, including bottles made from materials like PET, PVC, and polycarbonate.1