CORE-Materials
External surface of blow-moulded HDPE
DoITPoMS, University of Cambridge
The surface shows periodic ridges at right angles to the flow direction. These are indicative of flow instability and a periodic slipping of the melt at the die wall. It also shows surface scratches which are typical of polymer surfaces. Hard abrasive particles, dragged across the surface, have displaced material to form grooves and ridges.
System
High density polyethylene (HDPE)
Composition
Not specified
Reaction
Processing
A 'parison' (tube) is continuously extruded into a mould which periodically closes together with a knife, to cut suitable lengths which are then expanded to fill the mould
Applications
Blow moulding is a continuous process used in the manufacture of bottles as well as sheets, bags, and tubes.
Sample preparation
The specimen has been sputter-coated with gold, to give a conducting surface
Technique
Scanning electron microscopy (SEM)
Contributor
J A Curran
Organisation
Department of Materials Science and Metallurgy, University of Cambridge
External surface of blow-moulded HDPE
DoITPoMS, University of Cambridge
The surface shows periodic ridges at right angles to the flow direction. These are indicative of flow instability and a periodic slipping of the melt at the die wall. It also shows surface scratches which are typical of polymer surfaces. Hard abrasive particles, dragged across the surface, have displaced material to form grooves and ridges.
System
High density polyethylene (HDPE)
Composition
Not specified
Reaction
Processing
A 'parison' (tube) is continuously extruded into a mould which periodically closes together with a knife, to cut suitable lengths which are then expanded to fill the mould
Applications
Blow moulding is a continuous process used in the manufacture of bottles as well as sheets, bags, and tubes.
Sample preparation
The specimen has been sputter-coated with gold, to give a conducting surface
Technique
Scanning electron microscopy (SEM)
Contributor
J A Curran
Organisation
Department of Materials Science and Metallurgy, University of Cambridge