New routes to high processing polyethylene pipe grades. Is it a way to PE125?

Session 6A
2:40 pm

Pierre Belloir, Total Petrochemicals Research Feluy

It is a challenge today to find new technical routes for reduction of energy consumption during the pipe extrusion process keeping in the same time high throughputs. It is a challenge for any raw material supplier as well as for the machine manufacturers.

Knowing that the extruder takes 50% of the whole electricity consumption involved in the pipe manufacturing process, it is normal that the efforts are concentrated on the energy spent for the polymer melting. However recent innovations on downstream equipment must be noted and allow an optimization of the throughput and energy consumption.

It is suitable the energy requested for polymer melting comes from shear heating (mechanical energy) rather than from extruder heater bands ; to avoid the extruder is a bottleneck, a reduced head pressure must be ideally achieved. The extruders’ manufacturers have solutions to address this point but it is up to raw material suppliers to go beyond the actual limitations, in other words to understand how the head pressure could be reduced by a modification of the polymer structure without losing the characteristics of qualified materials, how the melt viscosity could be reduced at the processing shear rate while keeping the mechanical properties of PE80 or PE100.

No simple modification of the molecular weight target of the actual commercial PE pipe grades could be envisaged to answer this question. A technological breakthrough is required to explore new rheological behaviours ; metallocene catalysed PE offer an excellent platform to start this development. The actual data show promising results with new references in terms of relationship between well known Melt Index and machine processing. A new window of molecular structures is being evaluated and the route to higher mechanical properties opened like a potentially PE125 at low melt viscosity. So if the route to high processing PE100 leads to PE125, double energy savings are at the end of the road as thinner pipes will be produced for the same pressure rating.

Daniel Libert
Polyolefins, TS&D Pipe & Blow Moulding

Pierre Belloir
Polyolefins, TS&D Pipe & Blow Moulding Technical Manager