×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Low temp use of Polyethylene/polyproylene

Low temp use of Polyethylene/polyproylene

Low temp use of Polyethylene/polyproylene

(OP)
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?

RE: Low temp use of Polyethylene/polyproylene

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

RE: Low temp use of Polyethylene/polyproylene

(OP)
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

RE: Low temp use of Polyethylene/polyproylene


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

RE: Low temp use of Polyethylene/polyproylene

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

RE: Low temp use of Polyethylene/polyproylene

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.

RE: Low temp use of Polyethylene/polyproylene

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

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources