Effects of preform deformation behavior on the properties of the poly(ethylene terephthalate) bottles

Plastics bottles made out of poly(ethylene terephthalate) (PET) are usually produced by injection stretch blow molding. Optimization of the process parameters is necessary to achieve bottles with adequate top load and burst strength. However, doing so experimentally is time-consuming and costly. To overcome this difficulty, simulation packages based on finite element analysis methods have been developed. In this study, process optimization of a 350-mL PET fruit juice bottle was carried out by means of BlowView and ANSYS simulation packages. BlowView was used for the ISBM process simulation and ANSYS for structural analysis of the bottles. The bottles were produced under different process conditions where the timing of the stretch rod movement was varied in relation to the activation of the blow pressure. The simulation results obtained through the both simulation packages were compared with experimental results. It was found that bottles of highest quality were produced if the sequencing of axial stretching and radial inflation results in simultaneous biaxial deformation of the preform. Truly biaxial orientation of PET molecules improved both top-load and burst resistances of the bottles. The structural simulation studies performed by the ANYSYS simulation package validated most of our experimental findings.