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Previous by Date: Subject: Re: [DCHAS-L] Regulations for Snorkels Date: Tuesday, February 26, 2019 at 9:47:58 AM Author: Harry J. Elston <helston**At_Symbol_Here**MIDWESTCHEMSAFETY.COM> |
Next by Date: Subject: [DCHAS-L] 4 more Re: [DCHAS-L] Regulations for Snorkels Date: Tue, 26 Feb 2019 10:35:13 -0500 Author: DCHAS Membership Chair |
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
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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
-----Original Message-----
From: Tadeusz Wysocki Jr. <tswysocki**At_Symbol_Here**GMAIL.COM>
To: DCHAS-L <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
Sent: Tue, Feb 26, 2019 8:44 am
Subject: Re: [DCHAS-L] polymer curing question
Low flash point solvents are being used in the aircraft industry for urethane to metal bonding.
Same thing with uncured epoxy prepregs.
We used high flow ovens to keep below the Low Explosion Level ( LEL) for that solvent.
Safer alternatives to DMF are available,....NR-150 ( Dupont - AVIMID N ) ,......diamine cured Polyimide solution ( 50% ) was produced in 3 different solvents. NMP,
DMF and Ethanol.
Hope this helps,
Ted..
On Mon, Feb 25, 2019 at 2:03 PM Monona Rossol <0000030664c37427-dmarc-request**At_Symbol_Here**lists.princeton.edu>
wrote:
And don't forget a TLV-TWA of 5 ppm.
Monona Rossol, ACTS NYC
-----Original Message-----
From: Ellen M. Sweet <ems325**At_Symbol_Here**CORNELL.EDU>
To: DCHAS-L <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
Sent: Mon, Feb 25, 2019 10:21 am
Subject: [DCHAS-L] polymer curing question
Hi everyone,
I have a question from one of our researchers here at Cornell. Here's the background:
"The process involves synthesizing and curing a novel polymer, PDMS based PU, onto plastic "coupons" which will have DFM evaporating off.
The cure process is intended to have the polymer form onto the surface of the coupons in a thin coat and make the surface non-binding."
Our question is how to do this safely? DMF has a flash point of 58 =B0C and a vapor density of 2.52.
A known method for this curing process is to place the plastic coupons into a flammable oven that is under vacuum and flushed with nitrogen.
Can anyone suggest another method that doesn't involve the use of an oven like this? The group would have to purchase one to the tune of $50,000!
Thanks, Ellen
Ellen Sweet
Laboratory Ventilation Specialist
Department of Environmental Health and Safety, Cornell University
American Chemical Society, Division of Chemical Health and Safety
315-730-8896
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