Effect of Freeze-Line Position and Stretching Force on the Morphology of LDPE-PA6 Blown Films

Abstract

Blends of low density polyethylene (LDPE) and polyamide-6 (PA6) are produced via blown film extrusion to study the effect of freeze-line position and stretching force on blend morphology. An experimental setup is designed to measure the stretching force as a function of draw ratio (DR) and freeze-line position for 4, 6, and 10 wt% PA6 in LDPE. Numerical simulations of the non-isothermal and viscoelastic process are in good agreement with the experimental data of film dimensions. However, as reported many times in the literature, the calculated stretching force is underestimated and can be predicted more precisely by using a simple correction factor. The results also show that the dispersed phase deformation increases with DR and decreases with freeze-line height.

Film Processability, Morphology, and Properties of Polyamide-6/Low Density Polyethylene Blends

“…In the case of compatibilized blends a negligible effect is observed. In all cases the forces measured are small (1.2-1.7 N), but consistent with values reported in other studies [23][24][25]. These forces can be related to the deformation of the dispersed phase as presented in the next sections.…”

“…For the sake of clarity, Figure 2 shows only the complex viscosity of the PA6 and blends with and without compatibilizer while a complete rheological characterization of the PE was reported elsewhere [24]. In general, an increase in viscosity can be seen due to the presence of the compatibilizer.…”

“…Different draw ratios (DR ¼ V f /V 0 ), defined as the take-up roller velocity (V f ) divided by the extrusion velocity (V 0 ), were used to study the effect of this parameter on morphology, barrier, and tensile properties. One important parameter in the film blowing process that is seldom reported is the stretching force (F ) [23][24][25]. Similar to earlier investigations [24,25], Study on Properties of Polyamide-6/LDPE Blends the stretching force was measured using a device based on the principles of a torque wrench and consisting of two rubber rolls.…”

“…One important parameter in the film blowing process that is seldom reported is the stretching force (F ) [23][24][25]. Similar to earlier investigations [24,25], Study on Properties of Polyamide-6/LDPE Blends the stretching force was measured using a device based on the principles of a torque wrench and consisting of two rubber rolls. The processing conditions are given in Table 2 and further details of the equipment can be found elsewhere [25].…”

Rotational molding of compatibilized PA6/LLDPE blends

“…Blends of PA6/PE have been reported in the literature for different polymer processing techniques such as extrusion, [ 17,18 ] injection molding, [ 19,20 ] blown film extrusion, [ 21,22 ] and compression molding. [ 17 ] However, the compatibilization of PA6/PE melt blends using rotational molding has not been reported in the open literature.…”