I have been doing Finite Element Analyses of a part and have been trying to find creep information for LLDPE. My client has already asked his supplier and got no help. (In fact supplier said "there is no change with time in the modulus") Temperature will not be elevated and I'm looking for 5 to 10 year creep modulus values. As an estimate I have been using 1/3 of the short term datasheet modulus value.

Can anybody steer me to some data?

Thanks

Jerzy

Change raw material suppliers ton someone who is reputable and competent.
Borealis springs to mind

http://www.borealisgroup.com/about/production-site...

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules

Oh

And it will creep a lot.

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules

Thank you Pat for the speedy reply. I should have mentioned that I'm looking for rotational molding grades. I checked your link, but
they seem to offer only film extrusion grades.

Thanks again for the reply.

Jerzy

I thinkk you might find that creep data transfers accross a wide variety of grade. It is level of crystallinity (density) sensitive, but not molecular weight sensitive.

I am not really up to date on who now makes LLDPE. Maybe also Dow.

Rotational moulding grades are pretty much low MW grades with lots of heat stabiliser and no nucleating agents or mould release. They are injection moulding barefoot resin ground to a fine powder with heat stabiliser.

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules

A Google search for LLDPE creep data gives this link as hit 4

http://www.google.com/url?sa=t&rct=j&q=lld...

That paper gives some data.

Chris

Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
Instant Downloads & Inexpensive
www.plastictraining.com

This is the last hit on the first page of that search. Gives actual creep data for roto molding grades

http://www.qenos.com.au/internet/home.nsf/web/CTHS...

Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
Instant Downloads & Inexpensive
www.plastictraining.com

Thank you Chris. I had seen the first article on film, but the Quenos link was new. It is exactly what I'm looking for, but requires password.

I don't buy resins, but I'll see if my client has dealt with the company.

Thank you again (and also Pat for his comments).

I sent you a star.

jerzy

Sorry Qenos----I mistakenly added a "u".

jerzy

I checked before and the link Qenos Roto Grades Creep Data requires no password, it gives you an Excel file

Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
Instant Downloads & Inexpensive
www.plastictraining.com

Hello Chris,
But the EXCEL sheet is password protected: it downloads OK but won't open without the password--on my machine it won't anyway.
My client is getting a password.
Thanks again
Jerzy