Tonkabot wrote:...(Now if you can tell me what an HSE plastic is and what an LSE plastic is.... I don't know)
H and L SE plastics stand for high and low "surface energy". It's about the number of molecular (van der Waals) bond sites available on the surface of a material. High surface energy plastics have lots of end-chain molecules that the adhesive can attach to, and so things like ABS work well with glues. LSE plastics, are notoriously hard to bond, and include the traditional non-stick plastic like HDPE, PTFE, delrin, nylon, and so on. I'm not an expert, and that's why I'm not going to recite more of my feeble knowledge. Instead....
http://machinedesign.com/archive/bondin ... y-plastics
Below is a chunk of the text with what appears to be the pertinent information. In addition, check out the table of materials and relative surface energies near the end of the article. It helps give that big picture....like why the tape sticks like crazy to the glass, but less to the PEI.
Surface energy also influences adhesion. It defines the ability of adhesives and pressure-sensitive adhesive (PSA) tapes to "wet out" plastic surfaces to allow adhesion. Surface wet out refers to how well a liquid or viscoelastic solid flows and intimately covers a surface. Maximum adhesion develops when the adhesive or viscoelastic PSA tape thoroughly wets out the surface to be bonded. The greater the wet out, the better the surface coverage and the greater the attractive forces between adhesives and plastic surfaces. Surfaces with high surface energy bond more readily because they are easier to wet with conventional adhesives and tapes than are low-energy surfaces.
Surface energy is a relative phenomenon. To gauge the effects of surface energy on adhesion, one must compare the surface energy of a liquid or viscoelastic solid to that of a solid surface. A liquid or viscoelastic solid possessing a lower surface energy than a solid surface will spontaneously wet out the solid surface.
High surface energy plastics such as ABS and polycarbonate bond well with standard conventional adhesives and tapes possessing lower surface energy (LSE). But wet out becomes a challenge when using these same adhesives and tapes to bond LSE plastics such as polypropylene, TPOs, and polyethylene. Conventional adhesives and tapes can't wet them out properly resulting in minimal contact with the plastic surface and unsatisfactory bonds.
Traditionally, these LSE plastics have been primed, flame treated, or corona treated to raise surface energy and make them more suitable for bonding with conventional tapes and adhesives. As design and production engineers shift to LSE plastics, they need better and more efficient ways of attaching LSE plastics to themselves, metals, or other materials.
Regards,
Thom
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