Fine structure in polyethylene terephthalate fibres

VACUUM Classified A b s t r a c t s

II - -

Vacuum

Apparatus

and

Auxiliaries

--

Abstract No. and References

II

Contd.

Table to Abstract 2 1 / I I

Properties of Non-Metallic Materials (All properties depend on impurities and fabrication nmthod)

Material

Alumina, fused Beryllia,

Melting Point, ° F 3,722

4,568

~]lax, Operating Temp. in High Vacuum, ° F

Cocf. of Ther. Exp. Per ° F

Thermal Cond. i Btu/Hr/Sq Ft / Ft, '° F

3,270

4 . 5 × 1 0 -~ (68~2,3()0F)

0.4-0.5

Excellent

9

0.35

3,630

I 5 . 1 - 5 . 2 × 1 ()-6 , (68-2,550F)

1.1-2.1

Excellent

9

[ 1 . 8 × 1 0 -3

4 . 3 × 1 0 -s (77-104F)

4.4 14.4

Excellent

0.571.0

7 . 9 - 8 . 3 × 1[) ~ ! (68-3,100K)

0.4 0.8

Poor

6

High

2 . 5 - 2 . . q X 1 0 -~ (68-2,600F)

0.2-0.3

Good

6

--

0.2 0.35

Excellent

5---7

9 . 9 ~, 1 0 ~

1,830

5×10 a

fused

Graphite Magnesia Mullite

O

Silica,

4,530 5,072

2,910

a,250 3,335 2,730-3,090

!

l 0 -s

3,720

3,775

Elect Resistivity at2,2OO~F, oh m-cm 104

1 0 la

5 > 10 -n

Fused, good; sintered, poor

--

--

Excellent

4,900

5.2-5.3 × 10 6 {68-2,550F)

Very low

Poor

7

3 × 1 0 -=

4,71(I

1 0 ~°

Zircon

4,622

3,090

2.0-3.7 × 10 6 (68-1475F)

0.2-0.3

Good

8

--

--

104

4,600-4,700

3,990

2 . 8 6 . 0 × 1 0 -6 (68 2,275F)

0.36

Fair to good

8.5

--

--

Lava, fired

~

3,990

2,190-2,280

2 . 5 - 2 . 6 x 1 0 -~ ~ (32-3,090F)

1.1 2 . 4

5 . 8 - 6 . 4 >~ 1 0 -6 I (77-2,(100F)

--

Good

Good

~ 3,630

5,180

~ 4,900

Good

Excellent

Thor(a, fused

Silicon Carbide

Load Bearing at 2 , 2 0 0 ° F

7 . 9 >( 10 ~4

3,630

2,010

Zircon(a, stabilised

O

Hardness Vapour Pressure Mobs' ] Scale ] ram. of Temp Hg F

3,110

fused

0 . 3 × 1 0 -6 (68-2,280F)

Thermal Shock R,'xistance

--

Fair

Good Good

[ 9-10

--

--

2.5

Excellent

I --

6

---

--

10 ~

Good

I

22/n

Use of P.T.F.E. In Impregnating P o r o u s Materials United Kingdom. In c o n n e c t i o n w i t h w o r k necessitating t h e electrolysis of m o l t e n s o d i u m h y d r o x i d e / p o t a s s i u m h y d r o x i d e m i x t u r e s no m e t a l s could be found suitable for use as anode material. E v e n graphite crucibles released appreciable a m o u n t s of iron into the m e l t w i t h t h e a t t e n d a n t danger of c o n t a m i n a t i n g t h e cathode. The difficulty was e v e n t u a l l y o v e r c o m e b y i m p r e g n a t i n g the graphite under v a c u u m w i t h a dispersion of P o l y t e t r a f l u o r e t h y l e n e (Teflon). The a m o u n t of iron released from anodes, treated in this m a n n e r was g r e a t l y reduced. A t t h e s a m e t i m e t h e anodes were n o t a t t a c k e d b y the m o l t e n m i x t u r e s e v e n at t e m p e r a t u r e s near 250°C. It is suggested t h a t P . T . F , E . m a y be suitable for t h e i m p r e g n a t i o n of other porous materials subject to c h e m i c a l attack.

Letter by It. Hughes

Sommaire : Apr~s une 6rude poussde sur les m a t d r i a u x appropriSs p o u r Ia fabrication d'anode, on a trouv5 que

Chem. & lndust~'.

les anodes, faites en graphite impr~gne de Teflon sous vide, d o n n e n t des rdsultats satisfaisants dans l'electrolyse de m61anges de N a O H / K O t t fondus.

12.12. 1953 1342

Fine Structure in Polyethylene Terephthalate Fibres United Kingdom. K a s s e n b e c k d e m o n s t r a t e d t h a t d r a w n p o I y e t h y l e n e t e r e p h t h a l a t e fibres possessed a surface s k i n a b o u t 2,500 ,£~ t h i c k b y m a k i n g and p h o t o g r a p h i n g in t h e electron microscope polystyrene-silica replicas of specially prepared sections. H e also s h o w e d t h a t b e n e a t h this skin lies a fine structure of oriented fibrils w h i c h appear to v a r y in d i a m e t e r b e t w e e n 250 ~ and 750 ]k. The a u t h o r s h a v e e x t e n d e d these investigations b y t e a r i n g open t h e m o n o f i l a m e n t along the axis and m a k i n g g e r m a n i u m replicas of t h e exposed surface by t h e v a c u u m e v a p o r a t i o n technique. The latter t e c h n i q u e is simpler t h a n the polystyrene-silica m e t h o d . In addition, g e r m a n i u m yields a c o m p l e t e l y structure-free replica and does n o t t e n d to crystallise in the electron beam. The results suggest t h a t there are ' f u n d a m e n t a l ' fibrils of a b o u t 200 2~ d i a m e t e r and t h a t s o m e of these group t o g e t h e r resulting in fibrils of up to a b o u t 1,000 e~_ diameter. Sommaire : La s t r u c t u r e des fibres de p o l y e t h y l e n e t e r e p h t h a l a t e pass6es 5~ Ia fili~re a dtd examinde avec l'aide de repliques de g e r m a n i u m o b t e n u e s par la t e c h n i q u e de l'6vaporation sous vide.

23/II

Density of Deposited Carbon United Kingdom. A m e t h o d is described of depositing e l e m e n t a l carbon from gaseous c o m p o u n d s c o n t a i n i n g carbon, sucl~ as m e t h a n e b y passing the gas in a closed vessel over a heated graphite rod of S ram. d i a m e t e r at an initial pressure of 15 cm. Hg. The c o a t i n g obtained was 1 2 ram. t h i c k and its m a x i m u m d e n s i t y w a s f o u n d to be 2.22 g . / c m 3 (the theoretical lattice d e n s i t y is 2,265 g./cmS). V a r y i n g the t e m p e r a t u r e s of the graphite rods and t h e initial pressures of the m e t h a n e gas it w a s found t h a t the d e n s i t y of the deposits rose w i t h the t e m p e r a t u r e of the rods and that, at c o n s t a n t t e m p e r a t u r e , the d e n s i t y of the deposit rose w i t h the initial

January, 1954

Vacuum Vol. I V No. 1

Letter by R.

A . Cobboht de P. Daubeny K. Deutseh & P. Markey

Nature I7z , 31.10. 806

1953

24/II

104