Reclaiming Polyethylene Pipe

strantor said:
Here's the first of a 3 part series, the info you need is in this one and half the next one.


Well, maybe not the info you need, but the proof that it can be done with good results. Granted this guy is working with brand new buckets instead of old pipes that spent their life immersed in dirt and water, but I think it should still be feasible if you knead it up like taffy, like these guys do:

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I liked the way he layered it and came up with the nice colors. Great looking.
 
I would be tempted to recycle it by making "useful objects" out of them in their current shape. i.e. Shipping tubes. Cut them down and sell them on eBay for those who need to send documents/drawings/posters/drafts. Or possibly small camping tables, designed to be popped apart. Possibly a large scale windchime-whistle?

I use rigid tubing to ship expensive restored antique fountain pens to the purchaser. Unlike carboard tubes, I would dare the USPS to crush a thick walled plastic/PVC tube. Then again, you should never dare the USPS to break anything, to include a Tungsten brick.
 
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My desire to reclaim plastics by melting them down is more about reforming them into a shape that I need. For the most part, I wouldn't use the reclaimed plastic for items where I needed structural integrity but rather a large chunk of material. Plastic has an advantage in that it is relatively inert and it doesn't shrink or change form. Reclaimed plastic is also readily available. I haven't totaled it up but we (the wife and I) probably throw away a lb. or two a week. We heat with wood, and polyethylene and polypropylene are simple hydrocarbons so they are repurposed as fuel. More complex plastics like acetal, pvc, and polystyrene create undesirable combustion products so they go into the recycle bin,

The problem with recycling is that it often takes more energy to process them than what is saved. A good indicator is whether or not the recycler pays you or charges you to haul the stuff away. A lot of the recycled material just ends up in a landfill somewhere. NYC is notorious for shipping their waste to "somewhere else".
 
Depending on the intended manufacturing method, a given Plastic Resin will have different Melt Flows. The Melt Flow is the measurement of how Liquidity or "Molasses" like a polymer gets when it is melted. Tubing is typically extruded and tends to have a lower melt flow (more "Molasses" like) since it needs to hold its integrity as it exits the extruder and travels to the water bath, while the same resin when used for injection molding would have a high melt flow, as it needs to flow through and completely fill the molds.

So in other words. Raising the temperature beyond the melting point won't significantly change the Melt Flow of the polymer, but you can start to burn the polymer.

Also, it was common to cross-link Polyethylene (PE) Irrigation Tubing to give it strength and durability . Cross-linking also makes the tubing very hard to melt, if at all. Heat shrink tubing is typically a form of Cross-linked PE.
 
DAT510 said:
Depending on the intended manufacturing method, a given Plastic Resin will have different Melt Flows. The Melt Flow is the measurement of how Liquidity or "Molasses" like a polymer gets when it is melted. Tubing is typically extruded and tends to have a lower melt flow (more "Molasses" like) since it needs to hold its integrity as it exits the extruder and travels to the water bath, while the same resin when used for injection molding would have a high melt flow, as it needs to flow through and completely fill the molds.

So in other words. Raising the temperature beyond the melting point won't significantly change the Melt Flow of the polymer, but you can start to burn the polymer.

Also, it was common to cross-link Polyethylene (PE) Irrigation Tubing to give it strength and durability . Cross-linking also makes the tubing very hard to melt, if at all. Heat shrink tubing is typically a form of Cross-linked PE.
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Thanks, this is exactly the kind of info I need.

This stuff melts (softens) fairly readily but only partially liquefies. The "skin" of the pipe softens like taffy but does not liquefy. The pipe is at least 30 years old, so this may be due to age. In the "burnt brownie" test, I cut the pipe into 12" lengths, then quartered those lengthwise (I LOVE my little vertical bandsaw https://www.hobby-machinist.com/threads/a-vertical-bandsaw-for-a-small-shop-and-budget.94300/). I laid them in a baking pan like making lasagna. Going to experiment with different arrangements to see if I can minimize the effect of the skin, or at least get it more evenly distributed.
 
One would think chopping it up into smaller pieces would improve the process. How about building a machine to preprocess your material prior to melting?
 
matthewsx said:
One would think chopping it up into smaller pieces would improve the process. How about building a machine to preprocess your material prior to melting?
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It had crossed my mind and would be the obvious choice if I was going into the business. Looking at my old chipper/shredder, but it's an old "beater bar" type and this PE is tough and not easy to shred. I'm certain I can get usable material the way I'm going, just trying to reduce the oven time and labor required.
 
addertooth said:
I would be tempted to recycle it by making "useful objects" out of them in their current shape. i.e. Shipping tubes. Cut them down and sell them on eBay for those who need to send documents/drawings/posters/drafts. Or possibly small camping tables, designed to be popped apart. Possibly a large scale windchime-whistle?

I use rigid tubing to ship expensive restored antique fountain pens to the purchaser. Unlike carboard tubes, I would dare the USPS to crush a thick walled plastic/PVC tube. Then again, you should never dare the USPS to break anything, to include a Tungsten brick.
Click to expand...
Unfortunately, this stuff has a large radius (~10') curve to it and is almost 2" dia. It's like the industrial version of 5/8" drip emitter tube.
 
It's also possible the tubing was co-extruded, which means it has multiple layers. It could have an outer layer which resits abrasion, etc, and a more "pure" PE inner layer for potable water contact. This may be the reason your seeing a outer skin that appears to melt differently.
 
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