[Beowulf] materials for air shroud?

David N. Lombard dnlombar at ichips.intel.com
Wed Sep 14 08:29:30 PDT 2011

On Tue, Sep 13, 2011 at 02:05:30PM -0600, mathog wrote:
> FYI,
> Finally, I tried gluing two pieces at right angles using a high melt 
> hot glue.  The hot glue gun
> claims to run at 395F, and the glue stick was nothing special, just 
> generic high temperature
> hot melt.  Mixed results.  After it cooled and was allowed to set 
> overnight I tried to
> tear the two pieces apart by hand, pulling in opposite directions, and 
> they held together.
> However, I was able to snap the pieces apart by folding it at the 
> junction.  (Applying quite
> a lot of torque to the junction.)  The glue completely let go of the 
> top of the "T", all of it
> stayed on the vertical part.  At this point it was easy to peel the 
> rest of the glue off.
> Seems like the bonding was good perpendicular to the surface, but 
> pretty weak
> parallel to it. If the piece wasn't physically abused it would likely 
> hold together in an
> air shroud.  I had read somewhere that the hot glue melts the 
> polypropylene so that it was
> effectively a weld, but that is not how it turned out with this glue.  
> Neither piece of plastic
> was distorted where the glue had been, so clearly not melted.  There 
> are specialty hot melts made
> of polyethylene or polypropylene, and those may actually weld this 
> material.

This is my expectation with /consumer/ hot glues--they're good for
temporary work, but are not a long-term adhesive.  

Did you try some of the hobby plastic adhesives?  Plastruct has a "Plastic Weld"
solvent cement. They list ABS, Butyrate, Styrene, Acrylic, and "more".
Perhaps "more" includes your propylne.  Another brand is "Tenax 7R". The
former is MEK and the latter MC; both need careful handling.

Finally, you could try the PVC Priming Fluid or even PVC Pipe Adhesives.

These are all solvent glues and will weld the materials.

David N. Lombard, Intel, Irvine, CA
I do not speak for Intel Corporation; all comments are strictly my own.

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