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|Title: ||Extrusion of low density polyethylene tubular film|
|Authors: ||Siddig, Baha E.|
|Issue Date: ||1974|
|Publisher: ||© Baha Eldin Siddig|
|Abstract: ||Melt capillary flow has been employed to characterise some low
density polyethylene grades, differing in degree of an incorporated slip agent
The same grades were processed into blown film under different
extrusion conditions by varying screw speed, blow-up ratio and haul-off rate.
The rheological properties affected by the slip agent were,
namely, the melt viscosity and the critical shear-rate, after which fracture
(turbulence) of the given extrudate occurred.
Ease of draw-down property was found to be lower for the low
slip grades and increased significantly with increasing degree of slip.
(ASTM) and (B.S.) methods were used to test the mechanical
properties of the films produced from the film-blowing process under the
same above extrusion variables. The effect of these variables on tensile,
tear and impact strengths of each grade were analysed. Orientation of the
molecular structure, during its passage through the die and immediately
after extrusion, as a result of longitudinal or transverse direction drawing
strongly affected these properties.
Increasing the extrusion variables, generally, resulted in a
balanced orientation in both machine and transverse directions (balanced
film) and an optimum blow-up ratio was found for a film of balanced
An attempt was made to correlate characteristics of flow of the
different polyethylenes with the above extrusion variables and, hence, with
the mechanical properties of the consequent films.|
|Description: ||A Masters Dissertation, submitted in partial fulfilment of the requirements of the award of Master of Science of Loughborough University.|
|Sponsor: ||The British Council|
|Appears in Collections:||MSc Theses (Materials)|
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