I have used DP-8005 on PP. It is a pain to use - the "pot" life is tiny, and
if you leave it for more than a minute you have to replace the nozzle,
wasting the adhesive in it as well, so you have to do a lot of joints all at
once, with a lot of planning and maybe a second pair of hands, it ain't
cheap - but it does work. It sticks.
Haven't used 3030, but afaik it's pretty similar.
The plastic bumper repair trade uses "polyolefin adhesion promotors" - you
might try them. You spray them on then apply eg epoxy or polyurethane within
a few seconds. I have heard some encouraging reports. If you do please let
me know how you get on.
Something that I'd like to try would be using something susceptible to
microwaves (which is a fancy way of saying it absorbs them) in the joints,
then putting the assembly in a microwave oven. In theory the susceptor heats
up and melts the HDPE in just the right place and manner while the rest of
the assembly is unaffected :) ... in theory ...
Agreed a hot chromic/phosphoric acid etch involves a lot of nasty and
expensive chemicals and equipment, but it works for PP and should work for
HDPE too. I do plating and so have the needed chemicals, heated tanks etc to
I don't know what the technique is called, but passing the material quickly
through a hot flame can help adhesion too. I use this with a good PU
(Polyseal40 from Hodgson Sealants UK) on PP and it works well enough for me
- it's not as strong as etching or DP-8005 though.
Of the three stronger bonding methods I have tried on PP, I'd order them:
etching and PU, DP-8005, flaming and PU.
I also tried epoxy which is strong but it gets a bit brittle and flakes off
after a month or two, I don't know quite why - the wrong epoxy is my guess,
too rigid, a bit of flexibility is probably useful, after all the PP or HDPE
is flexible, and the PU I use is an adhesive sealant that remains flexible
I don't know much about corona treatment, but it's the only thing I can
think of that I haven't mentioned so far.
Gorilla glue? No-more-nails (though Pinkgrip works better)? If you don't
need a lot of strength ...
There is also a clear PU "ultragrip" "ultraflexible" sealant that works
fairly well too, the name escapes me, if you are interested I can find it
but it may be available in the UK only.
Oh, maybe hot-melt glue too, the stuff they use for sticking labels on HDPE
bottles, sticky but not very strong.
I don't know these adhesives although I can easily imagine what they are (2K
acrylics, cyanoacrylates, ...).
Bonding HDPE is very hard, as you might guess, especially if you are not
using corona or plasma treatment.
But I remember formulating some polyurethane with chlorinated polyolefin (I
used the ones of Eastman, API or DKSH) which behave not so bad.
In fact, everything depends on what kind of stress the system is supposed to
withstand... it would have been easier to try to bond polypropylene (PP)
instead, but if your choice of HDPE is done ...
Hope this will help, in a way or another.
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