6 октября, 2015 
Pokraskin The highly crystalline fluoropolymers include fluorinated ethylene polyethylene, perfluoroalkoxyethylene, polychlorotrifluoroethylene and ethylene-tetrafluoroethylene co-polymer but PTFE is perhaps the most widely used and certainly best known as ‘Teflon’ in non-stick cookware.
The coefficient of friction of PTFE is lower than almost any other material and it has excellent temperature and mechanical properties although it does have a tendency to creep. The outstanding chemical resistance and electrical properties mean that it is often used in applications that require long-term performance in extreme service environments.
Like PEEK and POM, this material has a very low surface energy and so will require some form of surface treatment prior to bonding with engineering adhesives (Table 2.17). Cyanoacrylate with primer shows some adhesion but etching kits for the fluoropolymers are also available.
|
Table 2.17 Adhesive shear strengths |
(PTFE) |
|
|
Adhesive type |
Description |
Shear strength (N/mm2) |
|
Cyanoacrylate |
Standard ethyl |
2.4 |
|
Toughened |
1.4 |
|
|
Ethyl + primer |
7.2 |
|
|
Two-part acrylic |
MMA |
0.3 |
|
Polyolefin bonder |
3.1 |
|
|
Epoxy |
‘5-minute’ epoxy |
0.7 |
|
Standard epoxy |
0.3 |
|
|
Silicone |
Alkoxy silicone |
<0.3 |
|
UV acrylic |
Visible light cure |
1.0 |
|
Notes: All shear strengths are given as guidelines only and may vary considerably depending on grade of plastic, fillers, surface finish, etc. Recycling information |
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