garage chemist
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Polybutylene terephthalate/PBT/Celanex
A few days ago I read that a plastic called PBT is in use for several applications, especially for mechanic parts, electrical connectors in automobile
applications, and a lot more.
It has several trade names, the most common being Celanex, others including Ultradur, Orgater, and so on.
It is a polyester of terephthalic acid with 1,4- butanediol.
By hydrolysis with hot NaOH solution, one could be able to obtain terephthalic acid like with PET from bottles (see the thread on this), and by
fractional distillation of the filtrate, 1,4- butanediol.
This would be the most interesting product, being a versatile reagent: by heating with H2SO4, tetrahydrofuran is obtained, and by dehydration,
butyrolactone.
By oxidation, succinic acid is obtained, which can be used to make succinimide.
This thread shall be focused on obtaining PBT plastic, if possible from OTC sources.
Does anyone know of any things made out of PBT, by chance?
Maybe extensive googling is in order for this.
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The_Davster
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http://www.cibasc.com/index/ind-index/ind-pla/ind-pla-polyme...
"used for door and window hardware, automobile luggage racks and body panels, headlight reflectors, and fiber optic cables. It is being used to
replace PVC for cable sheathing"
The cable sheathing looks most promising. How exactly would one be able to tell PVC from PBT? Unless it is written on there of course.
I also saw on another site that it is used in some windshield wipers.
EDIT: You can buy paintbrushes made of it here
http://www.hobbylinc.com/htm/tam/tam87047.htm
EDIT2: The loose tube inner tube of fiberoptic cables is PBT
EDIT3: Not a practical source http://www.e-switch.com/pdf/SeriesTL58&59Tact.pdf
EDIT4: Insulation on some coax cable connectors is PBT http://dkc3.digikey.com/PDF/EU051/0160-0161.pdf
[Edited on 10-4-2006 by rogue chemist]
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chemoleo
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I just looked up a book detailing with the characterisation of plastics.
PVC is easily told apart (green flame, part. in the presence of copper).
PETP (polyethylene terephthalate) and PBTP (polybutylene terephtalate) are both soluble in nitrobenzene. The plastic is pyrolysed (heated to
decomposition) in a test tube, with a filter paper in the upper half, which is soaked with a small amount of an aqueous alkaline (NaOH) solution of
o-nitro benzaldehyde. A blue-green colouring (which is Indigo!), which is resistant to weak HCl, points to terephtalic acid.
A characteristic simple test for PETP and PBTP is the appearance of a white sublimate (terephthalic acid?) when a sample is pyrolysed at high heat.
Possibly
A decisive differentiation between PETP or PBTP is difficult using simple tests. PETP melts betw 250-260 deg C, and PBTP at 220 deg C. This can be
different depending on additives however.
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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praseodym
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Heat of fusion and specific volume of PETP and PBTP:
For PETP, a linear relation is obtained: H* = 1411–1886v (Jg–1). Published values for the specific volume vc of the PETP crystal range from 0.660
to 0.687 cm3g–1. If vc = 0.660 cm3g–1 is accepted, a heat of fusion H = 166 Jg–1 is obtained for the PETP crystal.
For PBTP, a linear relation is also found: H* = 1296–1628v (Jg–1). With vc = 0.71 cm3g–1 one obtains H = 140 Jg–1 as the heat of fusion of the
PBTP crystal. The specific volume va of amorphous PBTP (H* = 0) is 0.796 cm3g–1 which is much higher than the hitherto used values of 0.781–0.782
cm3g–1. The reason for this difference is that va cannot directly be measured, because the low quasi-static glass temperature of 15 °C enables
quenched PBTP to undergo cold crystallization at 20 °C.
Hence, yes, it is rather difficult to differentiate PETP from PBTP.
Alles sollte so einfach wie möglich gemacht werden aber nicht einfacher.
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garage chemist
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Another trade name of PBT is Pocan.
These electrical connectors are made of PBT, with 25% glass fiber reinforcement:
http://india-berlin.com/de/d-k-steckerleisten.htm
However, such connectors are often crosslinked by gamma- rays, which makes their hydrolysis very difficult and creates many crosslinked monomers,
which will appear as insoluble slime.
Here are some casings made of PBT:
http://techcenter.lanxess.com/scp/emea/en/cases/markets/arti...
More (again reinforced with glass fiber):
http://www.industriegehaeuse.woehrgmbh.de/html/gh02sg003_230...
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