HDPE versus UHMWPE sifffness, bend radius

[Watco]

If we extrude a .125" diameter rod of HDPE and one from UHMWPE, which one is stiffer, or which one will have the larger bend radius?
Kevin.

 

[patprimmer]

Density and molecular weight have NOTHING to do with each other.

The higher the density of the unfilled polyethylene the higher the crystallinity. The higher the crystallinity of the PE, the higher the flexural modulus or stiffness.

Without knowing the density of the UHMWPE I cannot say for sure, but I very strongly suspect that the UHMWPE you are talking about is LDPE or MDPE and therefore is more flexible than the HDPE you mention.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers for professional engineers

 

[CoryPad]

You can get elastic modulus (tensile or flexural) information on these materials from suppliers (like LyondellBasell) or from MatWeb. HDPE comes in so many flavors that it is likely to bracket UHMWPE properties.


Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Demon3]

UHMWPE is used only for its great abrasion resistance. It has poor flow due to the high molecular weight.

So, if you need the abrasion resistance go for UHMWPE. Otherwise use regular PE.

Modulus depends way more on added filler than on the type of PE.

If you want to bend a polymer around a radius without it breaking (i.e. in cables) you want a high elongation to break.

As mentioned, you can compare all the properties for free at

http://www.matweb.com

Chris DeArmitt