Plastics failure mechanism

N

N_Cook

Guest
I've never seen reference to this mechanism, so transcribed and placed
here.

From (UK) Hacker GP42 record player of 1966, technical bulletin, not dated
but probably close to '66

"Investigation over a period of time of reports of knob breakages have shown
that the adhesive used to fix the chrome trim has affected the material and
caused the knob to fracture after a period of time. A further investigation
by the manufacturers disclosed that the material used in one batch of knobs
was an incorrect type. DIAKON was the material specified and POLYSTYRENE was
used in error. Unfortunately there is no way in which we can easily
differentiate between these materials other than by a flame test. "

Where I used to work , there was a flow-chart wall-chart for identifying
plastics by flame test, smell/smoke character when burnt and other basic
characteristics, anyone know of a WWW version somewhere?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
 
N_Cook wrote:
I've never seen reference to this mechanism, so transcribed and placed
here.

From (UK) Hacker GP42 record player of 1966, technical bulletin, not dated
but probably close to '66

"Investigation over a period of time of reports of knob breakages have shown
that the adhesive used to fix the chrome trim has affected the material and
caused the knob to fracture after a period of time. A further investigation
by the manufacturers disclosed that the material used in one batch of knobs
was an incorrect type. DIAKON was the material specified and POLYSTYRENE was
used in error. Unfortunately there is no way in which we can easily
differentiate between these materials other than by a flame test. "

Where I used to work , there was a flow-chart wall-chart for identifying
plastics by flame test, smell/smoke character when burnt and other basic
characteristics, anyone know of a WWW version somewhere?
Click to expand...
I'm sure modern health and safety departments would have kittens at the
thought of an employee deliberately igniting plastics for the purpose of
determining the resulting smell.

Sylvia.
 
On Jun 5, 6:32 am, Sylvia Else <syl...@not.at.this.address> wrote:
N_Cook wrote:
I've never seen reference to this mechanism,  so transcribed and placed
here.

From (UK) Hacker GP42 record player of 1966, technical bulletin, not dated
but probably close to '66

"Investigation over a period of time of reports of knob breakages have shown
that the adhesive used to fix the chrome trim has affected the material and
caused the knob to fracture after a period of time. A further investigation
by the manufacturers disclosed that the material used in one batch of knobs
was an incorrect type. DIAKON was the material specified and POLYSTYRENE was
used in error. Unfortunately there is no way in which we can easily
differentiate between these materials other than by a flame test. "

Where I used to work , there was a flow-chart wall-chart for identifying
plastics by flame test, smell/smoke character when burnt and other basic
characteristics, anyone know of a WWW version somewhere?

I'm sure modern health and safety departments would have kittens at the
thought of an employee deliberately igniting plastics for the purpose of
determining the resulting smell.

Sylvia.- Hide quoted text -

- Show quoted text -
Click to expand...
Too true!
To be fair, though, the common method of doing it is to poke the
plasitc with a hot wire and see the effect and smell the odour, so one
should not be creating clouds of smoke/fumes. How the plastic reacts
to the hot wire is also a clue to its 'type'.
I saw a description at one of the sites my wife was on about Jewellery
as to the smells and effects on the plastics commonly used for
orimental purposes such as Bakelite, Catalin, acrylic, ABS and so on,
but I don't recall which one it was. Googling 'plastic jewellery'
sould turn up something.

Neil S.
 
Sylvia Else wrote:
N_Cook wrote:
I've never seen reference to this mechanism, so transcribed and placed
here.

From (UK) Hacker GP42 record player of 1966, technical bulletin, not
dated
but probably close to '66

"Investigation over a period of time of reports of knob breakages have
shown
that the adhesive used to fix the chrome trim has affected the
material and
caused the knob to fracture after a period of time. A further
investigation
by the manufacturers disclosed that the material used in one batch of
knobs
was an incorrect type. DIAKON was the material specified and
POLYSTYRENE was
used in error. Unfortunately there is no way in which we can easily
differentiate between these materials other than by a flame test. "

Where I used to work , there was a flow-chart wall-chart for identifying
plastics by flame test, smell/smoke character when burnt and other basic
characteristics, anyone know of a WWW version somewhere?

I'm sure modern health and safety departments would have kittens at the
thought of an employee deliberately igniting plastics for the purpose of
determining the resulting smell.
Click to expand...
Yeah, same here. The closest I can recall seeing to that was a US army
tech guide for identifying metals based on the kind of sparks you got
when you hit it with an angle-grinder.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
 
Where I used to work , there was a flow-chart wall-chart for identifying
plastics by flame test, smell/smoke character when burnt and other basic
characteristics, anyone know of a WWW version somewhere?
Click to expand...
My chart is from "Materials In Design Engineering", February 1959. It
doesn't appear to be posted on the net anywhere. I could send you a
scan.

Alan
 
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:h0arpm$jpv$1@news.eternal-september.org...
I've never seen reference to this mechanism, so transcribed and placed
here.

From (UK) Hacker GP42 record player of 1966, technical bulletin, not dated
but probably close to '66

"Investigation over a period of time of reports of knob breakages have
shown
that the adhesive used to fix the chrome trim has affected the material
and
caused the knob to fracture after a period of time. A further
investigation
by the manufacturers disclosed that the material used in one batch of
knobs
was an incorrect type. DIAKON was the material specified and POLYSTYRENE
was
used in error. Unfortunately there is no way in which we can easily
differentiate between these materials other than by a flame test. "

Where I used to work , there was a flow-chart wall-chart for identifying
plastics by flame test, smell/smoke character when burnt and other basic
characteristics, anyone know of a WWW version somewhere?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
Click to expand...
http://www.boedeker.com/burntest.htm
 
Rick <notagood@one.com> wrote in message
news:pioWl.17764$pr6.287@flpi149.ffdc.sbc.com...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:h0arpm$jpv$1@news.eternal-september.org...
I've never seen reference to this mechanism, so transcribed and placed
here.

From (UK) Hacker GP42 record player of 1966, technical bulletin, not
dated
but probably close to '66

"Investigation over a period of time of reports of knob breakages have
shown
that the adhesive used to fix the chrome trim has affected the material
and
caused the knob to fracture after a period of time. A further
investigation
by the manufacturers disclosed that the material used in one batch of
knobs
was an incorrect type. DIAKON was the material specified and POLYSTYRENE
was
used in error. Unfortunately there is no way in which we can easily
differentiate between these materials other than by a flame test. "

Where I used to work , there was a flow-chart wall-chart for identifying
plastics by flame test, smell/smoke character when burnt and other basic
characteristics, anyone know of a WWW version somewhere?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

http://www.boedeker.com/burntest.htm
Click to expand...
Thanks for that, bookmarked and saved to disc


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
 
Alan Douglas <adouglasatgis.net> wrote in message
news:fuvi25lou87u02ek79jctt1d8kmdlkfqaj@4ax.com...
Where I used to work , there was a flow-chart wall-chart for identifying
plastics by flame test, smell/smoke character when burnt and other basic
characteristics, anyone know of a WWW version somewhere?

My chart is from "Materials In Design Engineering", February 1959. It
doesn't appear to be posted on the net anywhere. I could send you a
scan.

Alan
Click to expand...


Arrived safely, I wonder what HCl smells like
 
N_Cook wrote:
Alan Douglas <adouglasatgis.net> wrote in message
news:fuvi25lou87u02ek79jctt1d8kmdlkfqaj@4ax.com...
Where I used to work , there was a flow-chart wall-chart for identifying
plastics by flame test, smell/smoke character when burnt and other basic
characteristics, anyone know of a WWW version somewhere?
My chart is from "Materials In Design Engineering", February 1959. It
doesn't appear to be posted on the net anywhere. I could send you a
scan.

Alan



Arrived safely, I wonder what HCl smells like
Click to expand...
Bit like Chlorine, and just as nasty.

Sylvia.
 
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:h0arpm$jpv$1@news.eternal-september.org...
I've never seen reference to this mechanism, so transcribed and placed
here.

From (UK) Hacker GP42 record player of 1966, technical bulletin, not
dated
but probably close to '66

"Investigation over a period of time of reports of knob breakages have
shown
that the adhesive used to fix the chrome trim has affected the material
and
caused the knob to fracture after a period of time. A further
investigation
by the manufacturers disclosed that the material used in one batch of
knobs
was an incorrect type. DIAKON was the material specified and
POLYSTYRENE was
used in error. Unfortunately there is no way in which we can easily
differentiate between these materials other than by a flame test. "
Click to expand...

I forgot to mention this in my earlier post. The causative
mechanism is stress corrosion cracking. The solvent in the glue, in
the presence of the stress caused by the tightening of the setscrew
or by the stress caused by stretching the knob to fit over a push-on
shaft, precipitates the shattering of the knob.

While stress corrosion cracking in metals is well known, it also
occurs in many plastics. A crack will start at the plastic surface
and propagate perpendicular to the applied stress. In addition to
solvents, ozone can cause stress corrosion cracking in many
plastics. Gasoline will cause stress corrosion cracking of
polyethylene terephthalate; this is the reason that you should
never store gasoline in PET soft drink bottles.

--
73, Dr. Barry L. Ornitz WA4VZQ
BLOrnitz48@charter.net
 
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