I found 2 adhesive manufacturers who claim a product will bond with polypropylene and polyethylene...

http://www.masterbond.com/elasx17.html
http://www.permabond.com/ecustomer/literature/ll499_tds_us_english.pdf

and one who claims can bond ABS, nylon, teflon...

http://www.hernonmfg.com/fusionbond

I am sure these products are all benign and non-toxic. Hah!

: I remember testing half a dozen adhesives suggested by expert marine store
: salespersons. The labels all said they could be used with
: "plastic" but all also warned to test first, which I did. I have
: broken too many mountain bike helmets to tell you for sure that I gave the
: 3M5200 a fair test, but I think I did.

: Yes, plastic was roughed up with #60 and scored with a knife as well.

: Since there is some amount of grip and the cutout to lid joint is cosmetic
: and not structural it might be fine, I would not trust it to glue the lip
: to deck joint which affects the watertight integrity.

: I cannot remember where it was but I was reading an article on a website
: about how this (profesional) guy patches HDPP boats with fiberglass and
: epoxy. He said the secret was hitting the plastic with a blow torch just
: enough to temporarilly change the plastic's molecular structure so the
: epoxy would adhere. He said he heated the plastic to just before it would
: begin to discolor. He then had a short amount of time to get the first
: layer of the patch on.

: As a side note, in my current indenture I work a bit with polypropelene and
: injection molding machines and this stuff does not even adhere to itself
: well, even at 600 degrees and under pressure. Parts, when they break,
: always break at seams.

: Not even the 5200? plastic roughed up well?