[modeleng] Re: plastic pipe - why not composite?

Such developments cost millions of dollars these days Al.

It might be possible but there needs to be a market for the end product and
a business plan to pay for it. Very few companies are doing such research
into new plastics materials because of the cost and also because there is no
urgent need for them.

The car companies have been working for YEARS to develop hi temp high
strength plastics for use in engines and are not there yet (and may never
be). If someone figured out a plastic that you could injection mould car
cylinder heads from, cheaper than cast iron, but would do the same job, the
plastic would suddenly drop in price because of high volume mass production.

Metals are the most cost effective solution today for hi temp hi pressure
applications, and in fact are cheaper than plastics for such applications.
This may change in future, but that is today's reality.




----- Original Message ----- 
From: "Allen Messer" <al_messer@xxxxxxxxx>
To: <modeleng@xxxxxxxxxxxxx>
Sent: Wednesday, April 26, 2006 11:07 PM
Subject: [modeleng] Re: plastic pipe - why not composite?


> Many years ago, my high school Chemistry teacher
> explained to us that "Freon" was an "engineered gas",
> that is, the chemical engineers had decided what
> characteristics they wanted before hand and then
> developed the formula and process to get Freon.
>
> Why can't this be done with the problem with your
> question?  Surely there are some qualified
> Chemists/Petro-chemical Engineers among us that could
> answer this question with authority.
>
> Al Messer
>
> --- alan stepney <alan@xxxxxxxxxxxxxxxx> wrote:
>
> > Rich, I was / am looking for 275F = 135C, which
> > would be the temperature at
> > about 30psi, saturated steam.
> >
> > It seems that there are some plastics that can
> > withstand that temperature,
> > but whether or not they are suitable for steam, and
> > that pressure, is
> > another matter.
> > Plus there would need to be an allowance for safety.
> >
> > With advances in plastic technology, it looks
> > possible now, and if it isnt,
> > I would say will certainly be so in the near future.
> > Alan
> >
> >
> > ----- Original Message ----- 
> > From: "R.L. Roebuck" <rlr20@xxxxxxxxxxxxxxxx>
> > To: <modeleng@xxxxxxxxxxxxx>
> > Sent: Wednesday, April 26, 2006 10:53 AM
> > Subject: [modeleng] Re: plastic pipe - why not
> > composite?
> >
> >
> > Hi there Alan,
> >
> > One more thing you may like to consider: quite
> > frequently where they
> > appear to have used a plastic for something that you
> > wouldn't have though
> > they could have used it for, they haven't used a
> > plain plastic.
> >
> > I would image that if you took a plastic that could
> > take high temp but not
> > high pressure; and then added something to it to
> > make it into a composite
> > then this would increase it's strength so that it
> > could take the pressure,
> > for example a glass filled plastic composite.
> >
> > I've got part of a truck air cussion spring a few
> > feet away from me, that
> > will take 5 tonnes of load, and it has a plastic
> > base (with steel inserts
> > for the bolting points though). It is a glass
> > plastic composite.
> >
> > The only problem is that you don't want to alter
> > it's properties so that
> > it would shatter if the steam pressure was too
> > great, you'd really want
> > it to bulge instead (if you see what I'm getting
> > at).
> >
> > Possibly someone else on the list could advise about
> > modern plastic
> > composites, or you could look up a list on the web.
> >
> > RS has a good list in it's catalogue (you may be
> > able to get to it online
> > rswww.com or I can send you a scan of the catalogue
> > pages if you want).
> >
> > They have one - PPS 40% glass filled which they say
> > has high thermal
> > mechanical strength. max long term service temp
> > 230degC.
> >
> > Thinking of materials more common to model
> > engineers, Tufnol Carp and
> > Tufnol Whale are both capable of taking up to
> > 120degC and have good
> > mechanical strength - what temp did you need again?
> >
> > Yours,
> >
> >
> > Rich.
> >
> >
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> >
>
>
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