Least plastic smell 3

[kris1447]

I am the owner of a weighted blanket business (used in treating Sensory Processing Disorders...common with Autism). I am not an engineer, so please forgive any inconsistencies in my question.

I have been using underwater processed PE pellets from a plastics recycling plant as weighting material in my blankets, but each lot of beads that I buy has a distinct odor that is often offensive to my clients...and each lot smells different from the last lot. I am wondering if I would be better off using PP? Would Virgin Plastic rather than reprocessed have less of an odor? I know that there are a gazillion combinations...I believe that most of the lots I've been buying have had the label LDPE (or something like that). Is there a different PE combination that I should ask for to achieve less of an odor?

Thank you in advance for any advice you may have to share.

Kristi

 

[MikeHalloran]

Post-consumer PE could have _anything_ in it.
Try some virgin material.


Mike Halloran
Pembroke Pines, FL, USA

 

[kris1447]

Thank you, Mike. In your experience, when I start shopping around for a virgin materials supplier, am I better off pursuing PP or PE in terms of price and odor?

Kristi

 

[MikeHalloran]

I think PE is cheaper, but you should check.
I don't think their natural odor is substantially different, or particularly strong. If you buy odd lots/ overruns of custom compounded stuff, well again, it could have anything in it...




Mike Halloran
Pembroke Pines, FL, USA

 

[Demon3]

There should be no smell at all from virgin PE or PP. Sounds like PE is best for you as it's cheaper and has better stability so you need less additives to protect it. Plastics cannot smell, the molecules are too large to be volatile. It's the additives or contaminants that smell. Using virgin means no contaminants and using PE means less additives like stabilizer. In the industry taste and smell is known as organoleptics so if you speak to a PE supplier like Borealis, Total, Lyondell Basell or other, tell them that you're concerned about organoleptics.

Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
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[kris1447]

Thank you so very, very much, Mike and Chris.

Chris, thank you for name dropping some starting places for researching suppliers. I tried several different Google searches but I couldn't seem to hit on the right search terminology to turn up the type of suppliers I need. I have minimal experience in this, but I suspect that my next hurdle will be finding a supplier that will sell by the ton rather than the truckload. Any advice in this regards would be most welcome.

In 2010, I purchased some 'end of run' PP lots from a supplier that were a dream come true. But then when I went back to the same supplier for a second shipment, they sent me some kind of powdery 'bisque' pellet (rather than the PP that I'd requested). I'm sure it was probably top quality and a dream come true for someone else, but for my purposes, it was completely unusable. It was at that point that I searched and found my current supplier (underwater reprocessed beads that are unpredictable in smell).

Smiles.

Kristi (in Alabama)

 

[btrueblood]

What kind of a smell is it, like poo, or chemicals, or solvents? Maybe try running a batch of the stuff through a dishwasher cycle, in a mesh basket or sieve? I'm thinking (based on what I read about the process at the link below) that it's pretty unlikely that there is a contaminant mixed into the plastic somehow, and instead is some surface contaminant (grease or oil scum that was floating on the water bath?) that is giving an odor, and if so it might wash off.

http://www.rawpolymers.com/recycled-hdpe-pellets-repro-hdpe/hdpe/

If it's a burnt rubber or burnt plastic kind of smell - likely the reprocessor ran the batch at too high a temperature, and literally scorched the plastic. I'd send it back in that case.

 

[kris1447]

Hi, btrueblood,

Thank you for that link. The smell is definitely a chemical odor...or maybe a solvent odor...I wouldn't know the difference. I'm sorry.

I tried rinsing the beads, rinsing them in vinegar, putting fans on them (thinking they just needed to air out), setting them out in full sun...none of these made any difference. What I DID find makes an improvement is to boil the beads in water with a tsp of Palmolive for 15 -30 minutes and then rinse them (boiling just in water does not help).

I followed up on all of the companies that Chris mentioned. They each gave me the names of other companies that might be able to help me...so, tomorrow I will contact those new companies. I'll be curious to see what the price difference is between virgin versus reprocessed.

Kristi

 

[patprimmer]

Food grade virgin pellets should be good but at a price premium.

Other grades can have any number of additives.

post consumer waste could contain anything, including some decayed food.

Regards
Pat
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[Demon3]

There's a local company called DAF Greenwood who recycle used medicine bottles. It's a mix of uncontaminated PE and PP. Try calling them. They're in New Jersey. I've visited them and I think they'd be able to sample you something cheap and non-smelly.

Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
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[kris1447]

Pat, thank you. I had wondered if there was a possibility that the recycled plastic could even contain food waste. Eeeew.

Chris, I have a question that I am sure will show the full extent of my ignorance...if recycled plastic could contain food waste, then could recycled medicine bottles contain traces of the medicines they once contained? I do not know enough about the recycling process to understand why it would be a concern with food, but not with medicines. Would the medicine traces (if there are any) render the plastic no longer 'non-toxic'?

I am learning so much from y'all. I really do appreciate the time y'all are taking to educate me.

Kristi

 

[KENAT]

kris, given that your test of boiling the pellets in detergent laden water worked then it suggests surface contaminant as Btrue said and it may just be that you need to some how specify that the beads need to be 'clean' and then find a vendor that can do that for you.

Obviously, you'll have to come up with a reasonable definition of what 'clean' means for you. We have a standard note on most of our machined parts saying "FINISHED ARTICLE SHALL BE FREE OF OILS, LUBRICANTS AND OTHER CONTAMINANTS PRIOR TO BEING PLACED IN SEALED BAG." You'll need to come up with a different or more detailed spec, especially referencing the odor aspect, but hopefully you get my point.

Sometimes you need to actually solve problems like this, other times you just need to accurately specify what you actually need.

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[Demon3]

Tablets are solid and don't give much contamination and the bottles are all washed. Get a sample and see if it smells but make sure to tell them that's your criterion.

Chris DeArmitt - PhD FRSC CChem
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[kris1447]

"Sometimes you need to actually solve problems like this, other times you just need to accurately specify what you actually need."

Truer words have never been spoken. There is a learning curve in this (for me), and I know that I'll get more of what I actually want the more I learn how to accurately ask for it.

Thank you (everyone) for the excellent tips (and any more that you share). What I have learned so far...(correct me if I'm wrong)...

-Contaminants and additives cause odor.
-Pure Virgin PE would have no contaminants and the fewest additives resulting in virtually no odor...but probably at a premium price.
-My current bead odor (given that it is recycled plastic), probably has both internal contaminants and unknown additives as well as surface contamination. Boiling the beads in detergent/water seems to solve the odor problem (though I don't know if the internal contaminants will then result in future odor in the same beads, or once the odor is gone, it's gone).

If I got all of that right, then it is completely to the credit of this forum. Thank you.

Kristi

 

[Demon3]

Bingo...

Chris

Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
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[btrueblood]

I believe it is illegal to reprocess plastic that has not been through a wash cycle, which should (theoretically) remove any food waste. But oils/fats tend to cling to PE (ever see the red stain on your wife's tupperware after she washes the spaghetti sauce out of it?). Hot water and detergent wash should work, as you have found, I'd default to something like washing soda, to avoid the odor of the dishwashing soap and also avoid paying for that and the salt used to bulk up the liquid.

A good test for cleanliness after washing would be to take a pound or so of the washed and dried beads, and put them into a commercial, food-grade, cooking bag (the kind they sell at grocery stores to roast turkeys in). Seal the bag, maybe double-bag it, and toss it in an oven at a low temp (maybe 200 to 250 F) for an hour or two. Remove the bag, open it and sniff. Any volatile compounds left in/on the plastic should desorb when they are warm and present an odor.

You may find that repeated rinse/wash/dry cycles do a better job of extracting odors, you might also find that a wash, rinse, vacuum dry, and re-wash gives very good results. Vacuum drying tends to help force contaminants out of crevices as the water vaporizes, leaving the contaminant on surfaces more readily exposed to the detergent on the next wash cycle.

 

[kris1447]

btrueblood, that explains why sometimes after washing the beads, making a blanket with them, and then washing and putting the blanket in the dryer (heating up the 'volatile compounds') makes some of the odor reappear...but it disappears again after the blanket cools off from the dryer.

I do not have access to freeze drying. Would putting the beads in the regular deep freeze for 24 hours after boiling them do anything for it?

Thank you for the awesome tip. I will continue researching the costs and availability of virgin PE, but in the meantime, I have over 1000 pounds of these reprocessed beads and orders to fill while I'm looking for a new source. So, your advice is most appreciated.

Kristi

 

[kris1447]

Wait, I just re read your post. You said 'vacuum dry' not 'freeze dry'. I have to go look that up and see if that is something I can do. Sorry about my misquote/mis-read.

Kristi

 

[btrueblood]

Yeah, vacuum not freezing. In fact, a hot vacuum would be great, think heat lamp in a sealed box, and the wife's vacuum cleaner hooked up to it. Ok, maybe use the shop vac if you think your wife might complain.

We learned the technique in trying to decontaminate toxic rocket fuels (hydrazines) from complex parts/passages (think hydraulic valves). We could wash and wash, but the darn stuff would ooze out of crevices again, if we waited long enough or raised the temperature of the parts. But adding even one dry and re-wash/redry cycle gave an order of magnitude reduction in residual nasty stuff, and we could see approximately that kind of reduction with each cycle (two cycles put the apparent residue below the limit that we could detect its vapor). Ought to be at least worth a try.

I do like Kenat's idea too - just add a drawing note "no objectionable odor to be detectable", maybe add "when pellets are heated to 150 F" or some such.

Good luck!

 

[Compositepro]

A vacuum cleaner does not provide enough vacuum to do anything significant. Boiling in water is simpler and far more effective. The process is called steam stripping. The temperature increases the volatility of the contaminant and the steam flushes it away.