Innovation within the PE100 class
This series of blog posts will provide an overview of the new developments within the PE100 class of compounds, beginning with PE100 LS (Low Slump). If you haven’t already, read over the Introduction to Next Generation PE Pip Grade Resin.
As polyethylene pipe resins based on the PE100 material class have developed, various acronyms have been introduced. The main ones are clarified here and the performance of the different grades of PE100 are summarised in Figure 2, and will be discussed throughout the next few posts individually.
PE100 LS (Low Slump)
The higher-pressure characteristics of PE100 have enabled its use in water mains systems requiring diameters above 750 mm, for example. When the pipe wall thickness and PE100 pipe dimensions are thicker for large diameter-pipe in PN16-rated pipe networks exceeds 80mm, control over dimensional tolerances becomes challenging, as gravity causes the molten PE to flow downwards after exiting the extrusion die, before fully solidifying.
This “slumping” or “sagging” of a PE100 pipes leads to a non-uniform wall-thickness distribution, which cannot be tolerated in pressurised pipe applications. Slumping is especially an issue for thick-walled polyethylene plastic pipes as the PE takes longer to solidify. 8 Resin manufacturers developed “low slump” grade resins to address this market need. The modified rheology of these resins delivers exceptional melt strength, allowing pipes with up to 135 mm wall thickness to be manufactured. Installation of PN16 water mains with 1200mm diameter are becoming commonplace in Australia.
Figure 2. Property balance for PE100 specialty resins optimised to operate under specific conditions. RT = Temperature Resistance, LS = Low Slump, RD = Resistance to Disinfectants.