Re: Plasticizer problem
N Cook
news:WHshl.23847$wB5....@newsfe08.iad...
> "N Cook" <dive...@gazeta.pl> wrote in message
> news:gm1g0v$223$1...@inews.gazeta.pl...
> > I'm aware of the term "doll's disease" relating to the breakdown , to
> > vinegar, of the soft plastics used on antique dolls. But in my area of
> > electronics eg "rubber" grommets will "melt" hard plastic storage
> > drawers, a
> > mains cable wrapped around a hard plastic topped record deck, over a few
> > years such storage, will create "melted" ruts in the hard plastic.
Anyone
> > aware of a precise term for this plasticiser leeching process to
research
> > it
> > further, eg temp or humidity effect on the process, surface treatment to
> > avoid it etc.
>
> What you refer to as "Doll's Disease" is an entirely different phenomena
> that the leaching of plasticizer. Doll's Disease is actually a result of
> cellulose acetate reacting with the moisture in air to produce degraded
> cellulose and acetic acid (the vinegar smell). Originally it was seen in
> celluloid movie film, collar stays, etc. Celluloid is cellulose nitrate
> with a little plasticizer but the plasticizer has nothing to do with the
> reaction. With cellulose nitrate, nitric acid is produced. Once the
> reaction occurs, the acid catalyzes further degradation of the cellulosic
> plastic. Museum storage in sealed glass cases actually promotes the
> process. About all that can be done is to neutralize the acid by washing
> in a dilute sodium carbonate or bicarbonate solution, drying carefully,
and
> placing the item back in storage with flowing dry air.
>
> The problem you are seeing is the leaching out of plasticizer from
> polyvinyl chloride or polyvinyl acetate items. If you are old enough to
> remember vinyl automobile seats, you probably also remember the greasy
film
> formed on the inside of windows when the car was parked in the hot sun.
> Over time, the vinyl would get brittle, shrink, and crack. The film was
> plasticizer that evaporated from the vinyl. As it left the PVC, the
> shrinkage. brittleness and cracking occurred.
> One of the more common plasticizers was bis(2-ethylhexyl) phthalate, more
> commonly known as dioctyl phthalate or DOP. It is still in wide use
today,
> but many newer plasticizers are also available today such as
> trioctyltrimellitate (TOTM), dioctyladipate (DOA), diisononyl phthalate
> (DINP), di(2-ethyl hexyl) adipate (DEHA), acetyl triethyl citrate (ATEC),
> and even tricresyl phosphate (TCP).
>
> Plasticizers are incorporated with PVC in the manufacturing process.
> Contrary to what Armor-All® and similar products might claim, you cannot
> put plasticizer back into the vinyl with a surface applied product. Many
> products may contain significant amounts of plasticizers. Very soft and
> rubbery PVC compounds may contain as much as 40 to 50% plasticizer.
> Preventing the leaching out or evaporation of plasticizers from vinyl
> products is prevented more by the choice of plasticizer than anything
else,
> although low temperatures slow the rate significantly. The Wiki page on
> plasticizers lists a large number of plasticizers and tells where they are
> most used.
> http://en.wikipedia.org/wiki/Plasticizer#Plasticizers_for_plastics
>
> About the only way to prevent plasticizer damage to other plastics is to
> keep vinyl products away from them. Most coaxial cables for radio
> frequency use have a center conductor insulated with polyethylene, a wire
> braid shield, and a plasticized PVC jacket. When the plasticizer leaches
> from the jacket into the polyethylene, its electrical losses increase
> greatly. One modern innovation uses either aluminum foil or metalized
> polyester to wrap around the braid preventing the ingress of the
> plasticizer. But it also provides better shielding allowing the braid
> coverage to be lessened from 90 to 95% coverage to less than 75% coverage
> leading to a much lower weight.
>
> Powodzenia.
>
> --
> Dr. Barry L. Ornitz, Amateur Radio WA4VZQ
> BLOrn...@charter.net
> [transpose digits to reply]
>
Many thanks for the full reply.
I was totally unaware of the last point, so have added s.e.r as probably a
lot there are unaware also.
Recently reminded me of this effect because a "rubbery" presumably soft PVC
suspension inside a phono cartridge was leaching plasticizer and softening
the surrounding hard plastic etc. I don't know if it is also related but
often if one "rubber" drive band in a VCR or audio tape deck perishes, then
all the others are likely to fail in a sort of contagion -plasticizer gas
wafting around inside ?
Dr. Barry L. Ornitz
>
> Many thanks for the full reply.
> I was totally unaware of the last point, so have added s.e.r as probably
> a
> lot there are unaware also.
> Recently reminded me of this effect because a "rubbery" presumably soft
> PVC
> suspension inside a phono cartridge was leaching plasticizer and
> softening
> the surrounding hard plastic etc. I don't know if it is also related but
> often if one "rubber" drive band in a VCR or audio tape deck perishes,
> then
> all the others are likely to fail in a sort of contagion -plasticizer gas
> wafting around inside ?
You are quite welcome. Eastman Chemical Company, a former employer, made
both cellulosic plastics and a large number of plasticizers. I even worked
on a project to replace plasticized PVC in medical intravenous solution
bags with an elastomeric polyester because of the fears of plasticizers
leaching into the solutions (which they do!). While being more expensive
than PVC, our material was much stronger allowing thinner bags which offset
this higher raw material cost. But the perimeter radio frequency sealing
process required new equipment and the bag manufacturers were unwilling to
modify their manufacturing lines.
As far as VCR decks, I cannot think of any mechanism whereby the failure of
one drive belt via plasticizer migration would cause the others to fail
unless the plasticizer leaching from one belt actually dripped on another
belt. Remember that all belts were likely made at approximately the same
time, and had been in the VCR exposed to similar high temperatures for the
same time too.
--
73, Dr. Barry L. Ornitz WA4VZQ
Dr. Barry L. Ornitz
news:gm7hik$s9m$1...@energise.enta.net...>> news:gm1g0v$223$1...@inews.gazeta.pl...
> <snip>
>> About the only way to prevent plasticizer damage to other plastics is
>> to keep vinyl products away from them. Most coaxial cables for radio
>> frequency use have a center conductor insulated with polyethylene, a
>> wire braid shield, and a plasticized PVC jacket. When the
>> plasticizer leaches from the jacket into the polyethylene, its
>> electrical losses increase greatly. One modern innovation uses
>> either aluminum foil or metalized polyester to wrap around the braid
>> preventing the ingress of the plasticizer. But it also provides
>> better shielding allowing the braid coverage to be lessened from 90
>> to 95% coverage to less than 75% coverage leading to a much lower
>> weight.
>
> generally steel, and so have thick polystyrene insulation against the
> hull, then covered with wood panels. All cables running in this space
> have to be run in a conduit, as it was found that the polystyrene would
> suck all the plasticizer out of the cable making it brittle and liable to
> break without warning.
Thanks for the follow-up, Ron.
I know that polyvinyl chloride has been banned from many applications in
Europe. I believe that this is because most garbage is incinerated in
Europe. I guess that PVC wire insulation is still permitted.
Here in the USA, electrical conduit is often made of PVC. I do not know if
quenching agents are used here to reduce the limited flammability even
more. PVC is also used extensively for plumbing. In both cases, little or
no plasticizer is used. But PVC is also used in most wire insulations, and
plasticizer is used here. Rigid polyurethane foams are usually used for
home construction and I do not believe that plasticizer leaching will cause
major problems to these foams. But polystyrene foams are used occasionally
and your warning is an excellent one.
While I am familiar with many IEC standards, my knowledge of electrical
wiring for Europe is limited. Here in the USA, we have what is known as
THHN (Thermoplastic High Heat-resistant Nylon-coated) wire. This utilizes
a thin, colored PVC insulation clad in a Nylon jacket. It is frequently
used in conduits because of the ease with which it can be pulled without
abrading the insulation. I suspect that the Nylon will provide a good
barrier to plasticizer migration too.
[UL (Underwriters Laboratories) lists THHN as oil resistant to 60° C.]
Ron Jones
> "Ron Jones" <r...@ronjones.org.uk> wrote in message
> news:gm7hik$s9m$1...@energise.enta.net...
>> Dr. Barry L. Ornitz wrote:
>>> "N Cook" <dive...@gazeta.pl> wrote in message
>>> news:gm1g0v$223$1...@inews.gazeta.pl...
>> <snip>
>
>
>
> I know that polyvinyl chloride has been banned from many applications
> in Europe. I believe that this is because most garbage is
> incinerated in Europe. I guess that PVC wire insulation is still
> permitted.
> Here in the USA, electrical conduit is often made of PVC. I do not
> know if quenching agents are used here to reduce the limited
> flammability even more. PVC is also used extensively for plumbing. In
> both cases, little or no plasticizer is used. But PVC is also
> used in most wire insulations, and plasticizer is used here. Rigid
> polyurethane foams are usually used for home construction and I do
> not believe that plasticizer leaching will cause major problems to
> these foams. But polystyrene foams are used occasionally and your
> warning is an excellent one.
> While I am familiar with many IEC standards, my knowledge of
> electrical wiring for Europe is limited. Here in the USA, we have
> what is known as THHN (Thermoplastic High Heat-resistant
> Nylon-coated) wire. This utilizes a thin, colored PVC insulation
> clad in a Nylon jacket. It is frequently used in conduits because of
> the ease with which it can be pulled without abrading the insulation.
> I suspect that the Nylon will provide a good barrier to plasticizer
> migration too. [UL (Underwriters Laboratories) lists THHN as oil
> resistant to 60° C.]
As I said - this is for boats (that of course vibrate - and cables getting
brittle - even 12V ones are not a good idea). Not sure what "standard"
mains wiring is made of - web sites tend to say things like "BASEC approved
6242Y Twin and Earth cable. Grey sheathed with harmonised core colours. BS
6004". Which is not a lot of help. They are probably reluctant to give too
much info, as the rules (here) are now that mains wiring be only carried out
by a electrican.... Nanny state....
--
Ron Jones
Process Safety & Development Specialist
Don't repeat history, unreported chemical lab/plant near misses at
http://www.crhf.org.uk Only two things are certain: The universe and
human stupidity; and I'm not certain about the universe. ~ Albert
Einstein