What adhesive to adhere Dyneema X to Cuben in no load/stress situation?

I haven't tried bonding those materials together, but, in general, urethane adhesives (like Aquaseal) have a much higher bond strength than silicones. A silicone/cuben bond will be very weak, and I'd worry about the fabric patch peeling if the edge catches on something.

The Mylar or PET used in Cuben is just a bear to glue, to itself or anything else.
In the past, there seemed to be a consensus on this forum that Loctite Hysol 2 part urethane glue is the way to go with Cuben. Fastenal sells it in the low viscosity, or LV version, which is good with fabric. As with most adhesives, clamping usually helps. I've found it is much more sensitive to the need for precise mixing of the parts than epoxies are.

For something simpler, Joanne Fabrics sells an adhesive by Beacon called Tiger Bond that is pretty good with mylar, but not as good as the Hysol.

Everything else I've tried, allows the Cuben to peel off fairly readily, including epoxies, glues supposedly for plastic, regular urethanes like Elmer's GlueMax, contact cements, and a bunch of others.

Am not familiar with Dyneema X, but don't see how it could be any more difficult to bond than Mylar. If it is urethane coated, a urethane glue should bond to it readily.

Thanks, guys! I've decided to try sewing instead. Will make a few mock-ups to see how it goes.

Curiously, it might be the Dyneema that is harder to bond to.
This would likely be the case if the Dyneema has a DWR on it: that tends to reject most adhesives.

Cheers

Roger, you reminded me that an attempt to bond PU coated ripstop nylon to the same with the Hysol failed in places. I had thought maybe the Hysol was not mixed properly, but now wonder.

In any case, Rusty, please note that the Hysol urethane expands greatly when drying, and even when applied very sparingly, can push right through the fabric to the other side, which would mess up the symbol. You might consider bonding a Cuben patch to your Cuben with the Hysol to reinforce the area where the Symbol will be sewn on. With any urethane adhesive, I put wax paper between the clamps and the materials being bonded.

Thanks for the additional info, guys. I completely ignored my past failures in making a nice stitch around radius's and tried again this morning….thinking that I somehow received magical sewing prowess in the interim. No more such ability existed this time then last. I now give up sewing in this particular instance to ponder adhesion…and my nuttiness……