Properties of PE-HD
Properties of PE-HD
(OP)
Can anyone suggest a source for;
Stress plotted against strain for varying times say 1 year, 10 years and 20 years? at say 20°C.
Better still a family of curves at varying temperatures, say 20°C, 30°C and 50°C.
I need to determine the tangent Modulus and the secant Modulus for black PE-HD as used for manufacture of chemical storage vessels.
Many Thanks
Ed
Ed Clymer
Resinfab & Associates
England






RE: Properties of PE-HD
RE: Properties of PE-HD
Dwight
In UK we build large vessels to 80-100 m3 from sheet.
Sheet manufacturers are in general not helpful with data - but we are still trying.
If anyone knows of good source - would be appreciated
Ed
Ed Clymer
Resinfab & Associates
England
RE: Properties of PE-HD
RE: Properties of PE-HD
ht
They mention large containers and creep resistance, so I assume they have creep data.
RE: Properties of PE-HD
Their older literature is a more likely source, as the modern marketing trend is to remove obstacles, like complicated looking data from the literature.
I will look in my collection, but I fear I only have it for nylon.
Be careful that the data you use is for a grade with similar density, similar vinyl acetate content if any, and similar melt flow index. Sheet extrusion grade is normally very low melt flow index, which will give a somewhat higher elongation than the more often quoted injection moulding grades.
Regards
pat pprimmer@acay.com.au
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RE: Properties of PE-HD
Thanks to djv and pprimmer for their help.
The root of problem, is that sheet extruders do not know (or will not say!) which grades and who are producers of the polymers they use.
The search continues: if any one has information it would still be appreciated. The DVS 2205 code does produce graphs (repeated in BS EN 1778 and EN 12573) could anyone comment on accuracy?
Regards
Ed
Ed Clymer
Resinfab & Associates
England
RE: Properties of PE-HD
You might try Borealis in Europe or Chevron Phillips Chemical Company in the USA.
The problem is that the values of modulus will vary depending upon the loading and the rate of loading. The stress/strain relationship will be non linear.
You might use FEA to get answers to the ninth decimal place and then add a 50% safety factor because of he vagaries of the properties of the material.
Any modelling will need the properties changed to check the design sensitivity. So the initial starting values dont have to be that precise.