International Polymer Processing, Vol.22, No.2, 190-197, 2007
Analysis of film blowing with flow-enhanced crystallization - Part 2. Linearized sensitivity and stability behavior
An analysis of the transient film blowing process is presented based on the two-phase Giesekus/rigid rod model for flow-enhanced crystallization described in Part 1 [1]. Linearized frequency analysis has been used to explore the effects of system disturbances on the process. Results show that perturbations related to heat transfer and inflation pressure are more significant than the effects of film thickness (die swell). In addition, crystallinity is shown to have a consistent stabilizing effect on the system, with more crystallinity dampening the perturbations. Stability diagrams for each material show relatively wide regions of convergence in the blow-up ratio (BUR) - draw ratio space, however, at higher BURs (>= similar to 4) the system becomes unstable for all DRs.