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Subject: Re: [DCHAS-L] 4 more Re: [DCHAS-L] Regulations for Snorkels

Date: Feb 26, 2019 21:07 UTC

Author: Monona Rossol <0000030664c37427-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU>

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Subject: [DCHAS-L] Scientist says some pollution is good for you -

Date: Feb 27, 2019 10:31 UTC

Author: Eugene Ngai <eugene_ngai**At_Symbol_Here**COMCAST.NET>

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From: Tadeusz Wysocki Jr. <tswysocki**At_Symbol_Here**GMAIL.COM>

Subject: Re: [DCHAS-L] polymer curing question

Date: Feb 27, 2019 00:37 UTC

Reply-To: ACS Division of Chemical Health and Safety

In-Reply-To: Re: [DCHAS-L] polymer curing question

Demystify: 

All valid points.
Short chained polymeric polyisocyanates know as PAPI has low monomer levels.
These are used in moisture cured urethane adhesives ( Gor**la Glue , and urethane foam in a can found in most hardware stores.

I would worry more about some aromatic diamines used to cure Toluene Di-isocyanate based urethanes for the higher temp uses.
Aromatic diamine such as MOCA - methylene bis chloro-aniline- which hepato-toxin, rapid skin penetration and tissue absorption, and has been considered a liver carcinogen.
These compound were melt blended so minimum solvents were used as such.

Aliphatic dianhydrides are used to cure methylene bis- di-isocyantes.
Many soft foam prothesis used in skin contact medical applications such used in mastectomy survivors cosmetic reconstruction are MDI/polyol/ water.
Your memory foam is one of those.

Use anhydrous isopropanol, or anhydrous MIBK or acetone if you can.
or you could,....
If this is only a small scale proof of concept evaluation then place the coupons inside a metal mesh cage just like Sir Humphrey Davy's Lamp for the coal mines and put it into a high flow oven.
Ted.




On Tue, Feb 26, 2019 at 10:34 AM Monona Rossol <0000030664c37427-dmarc-request**At_Symbol_Here**lists.princeton.edu> wrote:
Thanks Tammy, and if they are doing urethane curing, we are looking at one or more of the isocyanates with TLV-TWAs usually set at 0.005 ppm. Whenever we think about safety and LELs, we need to also consider health and the TLVs.

Monona Rossol


-----Original Message-----
From: Tammy M. Lutz-Rechtin <tlutzrec**At_Symbol_Here**UARK.EDU>
To: DCHAS-L <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
Sent: Tue, Feb 26, 2019 9:48 am
Subject: Re: [DCHAS-L] polymer curing question

Don't forget these two solvents, although common, are reproductive hazards (1B) with verifiable effects on pregnant women.
-Tammy Rechtin
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of Monona Rossol
Sent: Tuesday, February 26, 2019 8:38 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] polymer curing question
I repeat: DMF has a TLV-TWA of 5 ppm And add:
NMP has a WEEL-TWA of 10 ppm and NMP is on a short list proposed for a consumer product ban due to its toxicity.
Those health standards are miles below their LEL concentrations, so I worry about where that oven exhaust is going, especially if they are used in academic labs in someone's project rather than in a planned industrial use. I have very low confidence in ventilation systems designed for academic labs and especially the locations at which they exhaust.
My advice: follow the ducts.
Monona

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