Epoxies don't like to stick to polyethylene. The best repairs are made with heat by "welding" A soldering gun can be used with some donor polyethylene used as filler rod, there are plastic welders which use hot air concentrated in a small area. There are also plastic staples that melt into the existing poly parts to reinforce them and hold them together. Plastic staple tools are available on Amazon for little expense and they work quite well. Harbor Freight has a plastic welder (hot air) that isn't a lot of money.
When trying to repair odd shapes aluminum window screen can be used to reinforce the breaks by melting it into the surrounding poly in the area bridging the break.
Repairs made as suggested above can be ugly but very strong, often as strong as the original material or stronger since there is reinforcement where there was none.
Links below may be helpful:
Plastic Staple Kits

HF Plastic Welder

Plastic Welding Videos Youtube

 

I have a plastic stapler and plastic welder, both work very well.