Low temp use of Polyethylene/polyproylene

[smartbull]

We are designing a telecommunications closure for outdoor use. The design calls for a living hinge and impact requirements at -20c. Does anyone know of of material in the polyproylene/polyethylene family that will sustain such conditions?

 

[Pud]

Hi,

Homopolymer Polypropylene gets brittle around 5 deg C - Co-polymer around -5 deg C.

A Linear Low Density Polyethylene (LLDPE) embrittles lower than -50 deg C (If I rememember correctly).

LLDPE will not make a hinge as durable (i.e. cycles to failure) as PP but probably will be suitable.

These materials are not too good outdoors, whatever UV stabilisers are added.

How big is this enclosure?

Rgds

Harry

 

[smartbull]

Harry;
Thanks for the info.The enclosure is approx. 8 x 18" with the living hinge at the top. We tried std. pp and the hinge worked fine as long as you perform the recommended flexing operation after molding. Cold temp on the pp though stinks. We are now trying HDPE, MDPE.
Rdgs
Tom

 

[Pud]

Hi Tom.

Be aware that the hinge, being the thinnest section by far, is going to suffer badly from surface degradation from UV, and is likely to fail. (Unless you live in NE England like me, where UV is definitely "not" a problem!! Ha!)

HDPE / MDPE are similar to LLDPE but maybe not as rigid.


Rgds


Harry

 

[smartbull]

Thanks Harry!
I'll let the forum know how we make out in the final material selection.
Rgds
Tom

 

[dgowans]

smartbull,

I'm in a similar situation. We've got an existing product undergoing some certification testing which includes impact testing at -35C. Our existing PP enclosure didn't fare well. so we're investigating alternative materials.

Care to collaborate? Our enclosure is in an outdoor application as well, so I think we're pretty much tackling the same challenge.

 

[smartbull]

dgowans;
Stay tuned, I'll let you know how we do.
Tom