I think you are looking for the wrong craft.
Crocheting your string will thicken up but it will be still be only one strand and any damage that breaks a single strand will break your whole string. And the tight bends in which you force you string in crochet do not work well in dyneema, which is at it strongest straight.
I would go for braiding strands together, at least 8 strands in a round or semi round pattern. With that you do not need to bend your string in tight bends, the several strands will support each other and the failure of one strand will not weaken the whole of your strap.
You can find instruction for braiding online but I have added some I have online, (non commercial site, made by me.)
Here is the page where I have the links to the braids, I would go for the eight strands making a square braid, or the round eight with some extra strings for a core. Or using two or three strings for each braiding strand, a 4 strand round braid.