Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

PTFE BEHAVIOUR

Status
Not open for further replies.
FrankSmith

FrankSmith

Industrial
Joined
May 13, 2004
Messages
2
Location
IE
We have recenty done some work laminating 4 mils of PTFE film to roughened (240 grit) copper plates in a high temperature press (380 deg C). When we cut the now laminated product from 3'X3' sheets into panels of 1'X1' with a saw the edge of the panel show excellent adhesion between the copper and the PTFE. However further in the panel ~1/4" the bond is poor and it is easy to peel the film from the copper plate. If the product is left for 2 weeks the bond further in towards the centre improves. This improvement is accelerated if the product is baked unsupported in an oven for a number of hours above 100 deg C. Can anyone explain this phenomenon . Is there a stress relieve occurring within the material due to cold flow of ptfe, is the bake of the material relieving this stress ?.
 
Sort by date Sort by votes
When designing components made of PTFE, the relatively high degree of thermal expansion must be taken into consideration:
20-100 °C: = 16 · 10-5 1/K
20-200 °C: = 23 · 10-5 1/K

Recordings of the coefficient of linear expansion reveal two conspicuous transitions:

At 19°C there is a conversion within the crystal phase (<19°C triclinic, > 19°C hexagonal), which corresponds to a significant increase in thermal expansion.
At app. 327°C there is even higher unsteadiness, i.e. the crystal melting point

The following chart depicts the correlation between temperature and thermal expansion.

therm_exp.jpg


Regards,

Peter P
 
Upvote 0 Downvote
Frank
If it is correct to assume that by the edges you are referring to the original sheet edges and not the newly cut edges then I suspect the problem is due to some gas evolving during the bonding process. It is likely to be most apparent towards the centre and least apparent on the edges.
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

M
  • Locked
  • Question Question
PTFE
Replies
1
Views
2K
EdClymer
EdClymer
V
  • Locked
Sealing material PTFE alternatives
Replies
1
Views
2K
bcd
bcd
Johnwoo1991
  • Locked
  • Question Question
Rptfe and Ptfe Cg
Replies
0
Views
888
Johnwoo1991
Johnwoo1991
SiggiN
  • Locked
  • Question Question
Epoxy behaviour
Replies
4
Views
394
Tmoose
Tmoose
SandraB
  • Locked
  • Question Question
PTFE streamliner
Replies
0
Views
223
SandraB
SandraB

Part and Inventory Search

Sponsor

Back
Top