Stretch blow moulding of mineral filled PET

Injection Stretch Blow moulding is a two step processing that was designed and optimized mainly using unfilled PET resins. This study focuses on stretch blow moulding of a PET filled with a few percent of sub micronic mineral fillers. Main effects of fillers are analyzed thanks to DSC, DMA, tensile tests, free blowing on prototype machine as well as stretch blow molding using industrial SBO1 machine. It is demonstrated that fillers increases crystallization kinetics resulting in a reduction of the processing range. Difference in strain hardening induced by fillers makes it necessary to adjust blowing temperature. However main effect occurs during heating phase. Temperature within the preform is much less homogeneous than in PET making thermal gradient totally different if heating protocol is kept unchanged. Once heating is controlled to reach to equivalent thermal gradients as for PET blowing is possible and rather equivalent to that of pure PET.