Document GmM7vob0oMkOb565mN3RYO0j7
Dr. J.U. Barrett.
Mr. J.S. Hunter. Dr. J.A. Oardner. Mr. 0.0. Wickham/
Fulmer Library, Dr. V.MbO. Morgan. Mr. W.B. Hamer.
Dr. D.S.P. Roebuok.
Mr. S. Baxter. Mr. N.G.H. Tboaas. Dr. C.S. Morgan. Dr. D.P. Dodgson. Mr. H.B. Pate. Mr. G. Hulse.
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Application Beeearoh Laboratory Report Not L.57/2
Patel
13th August, 1957.
Job.Roi 635.151.1151 Req.lfot DF.57/32
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Further investigation of the high temperature stability of Aroolors 1243* 1248 and 1254.
Previous work on these Aroolors indicated that they were unstable at 250C. (See A.R.L.R. L.57/1). This report deals with an attenpt to determine the maximum working temperature of Aroolors In eleotrloal applications.
9mm Mlfl
Tests over a period of 25 days at 2000. and 50 days at 1750. were carried out on various Aroolors.
At 2000. Aroolor 1242 appeared to be unstable and would be unsuitable for use at this temperature. Both Lots of Aroolor 124t degraded slightly and use of this material at 2000. Is not recommended. The sample of Aroolor 1254 also showed a deterioration although at the end of the ageing period its Power Factor was still low. 0.0024, and its Volume Resistivity high, 3.11 x 1&2 ohms. ems.
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At 175C. no significant charge in electrical properties of any sample vas detected.
These results suggest that 175C is the maximum working temperature of Aroolors 1242 and 1248, and possibly 200C. for Aroolor 1254. Further long term tests are necessary to oonfirm these conclusions, and such tests have been initiated.
Details;
Representative samples of Aroolors 1242, 1248 and 1254 were selected for the tests (See Tables 1 and 2), and each sample vas treated with Fullers Earth prior to measurements and ageing.
The ageing was oarried out in two stages, first at 2000. with tests after five days, fifteen days and twenty five days, and then at 175G with tests after fifteen, twenty five and fifty days.
The test conditions were those usually maintained in
this type of measurement vis.
'
Power Factor at 1000 cps. and 100C. Volume Resistivity at 200V DC and 100C.
Results are given in Tables 1 and 2.
Discussion.
Aroolor 1242 shows a marked deterioration after ageing for 25 days at 200C. and would be unsuitable for use at this temperature. No significant difference appears between the two lots of Aroclor 1248 tested, both show a slight degradation, which would probably inorease with further ageing at 200C. The change in electrioal properties of the sample of Aroclor 1254 after ageing may be significant and further long term tests would be necessary before its use at 200C. could be reoommended.
After 50 days ageing at 175C. all samples showed very little ohange in eleotrioal properties. Discolouration had occurred in all samples, but to a. greater extent in Aroclor 1254.
Further tests are being carried out over a longer ageing period to confirm these results.
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-3It should be noted that during the ageing period soae samples exhibited an Initial Improvement In eleotrloal properties followed by a deterioration, but there la insufficient experimental evidence to lndioate whether this Is a real effect or merely due to random experimental errors. No ohange In 8.I.C. occurred In any sample over the period of ageing.
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Sample
Aroolor 1242 P.F.
Lot K.1
Vol.Res.
Aroolor 1248 P.F.
Lot X.l
Vol.Res.
Aroolor 1248 P.F.
Lot L.1
Vol.Res.
Aroolor 1254 P.F.
Lot K.16
Vol.Res.
Control 25 days at Room
temo.
0.0096 7.42 x 10U
0.0031 1.54 x 1012
0.0079 1.22 x 10*2
0.00023 7.34 x 10*2
Aged for 5 days.
Aged for 15 days.
Aged for 25 days.
0.012
0.0084 ,,
0.050
1.40 x 10*2 8.16 x 10*1 1.13 x 10**
0.012
0.0051 ,,
0.010 ..
2.05 x IQ12 9.77 x 1011 4.95 x io**
0.0074
O.OO46 ,,
0.0049
1.91 x 1012 9.88 x 101* 8.89 x IOLI
0.0012
O.OOO83 ,
0.0024
3.17 x 1012 3.11 x 10*2 1.30 x 10*2
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Saaplei? wwfl at,172.Q
3amplo
Control 50 days at Room
Aged for 15 days.
Aged for 25 days
Aged for 50 days.
Aroolor 1242 P.F.
Lot K.1
Vol.Res.
0.013 ,, 3.64 x lCU.
Aroolor 1248 P.F.
"o t L.1
Vol.Res.
0.9 .. 3.36 x 1011
'roelor 1248 P.F.
Lot H.1
Vol.Res.
0.006 ,, 6.63 x 10**
Aroolor 1254 P.F.
0.0017
Lot K.16
Vol.Res. 1.39 x 10*2
0.016 ,, .007 ,, 0.011 4.74 X 10** 6.67 x 1011 4.00 x 10*1
0.024 .. O.OO38
0.0056 ,,
3.48 x 1011 1.02 x 1012 5.35 x 10**
0,0097
0.0042
0.0056 ,,
7.96.x io*1 1.13 x 10*2 4.95 x 10**
2'010 11 0.0013
0.0013
3.1i X 10** 2.89 x 10*2 1.47 x 10*2
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