Blow moulding pre-stretched polyethylene terephthalate preforms

摘要

Hollow articles are formed from polyethylene terephthalate by axially stretching a heated preform to 2.6 - 2.75 times its original length and then radially stretching the elongated preform by blowing in a mould. The strain hardening and crystallisation during the radial stretching is increased by the mechanical conditioning of the elongation.