Recycling heat bonded LDPE and HDPE

Hey Guys,

I am currently on a product development internship at Skunkworks Surf co. where we create sustainable surfboards. Currently I am trying to deal with some of the waste that comes from our production line.
We use LDPE and HDPE in the boards and for a great deal we have the two separated. One way we are going to deal with the LDPE is to densify it and send it back to our manufacturer to make EPE out of it again.

Now the problem we are facing is that we have pieces of HDPE that we heat bond to our LDPE foam, this bond is very strong and makes it so that when we rip the HDPE of the foam a small amount of LDPE is left on it. Because there is LDPE mixed with the HDPE, companies won’t recycle it (probably because of the difference in properties of LDPE and HDPE).

I have attached a picture of one piece of HDPE sheeting with EPE foam residu on it, the right side of the sheet is slick and has no residu on it, you can see the thin rough layer on the left with the foam on it.
One way I was thinking of separating the two was using the difference in melting temperatures, LDPE melts earlier (110~) than HDPE (130~). Anyone tried this out with any plastics?

Or any other idea how to tackle this?