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DENSITY AND SURFACETENSION
MEASUREMENTS OF PURE POLYPHENYLS
AND SOME POLYPHENYL MIXTURES
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It«.
11
Sift
1963
Ρ
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«iifihiï Mltff'l
ORGEL Program
Joint Nuclear Research Genter Ispra Establishment - Italy
Heat Transfer Department mm
visite
Neither the Euratom Commission, its contractors nor any person acting on their behalf
Io Make any warranty or representation, express or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this document, or that the use of any information, apparatus, method, or process disclosed in this document may not infringe privately owned rights; or
2° — Assume any liability with respect to the use of, or for damages resulting from the use of any information, apparatus, method or process disclosed in this document.
ÏI
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U
E.C.2, ι! » V
giving the reference: «EUR 165.e Densityand surfacetension measurements of pure polyphenyls and some polypheny! mixtures»
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EUR 1 6 5 . e
DENSITY AND SURFACE-TENSION MEASUREMENTS OF P U R E P O L Y P H E N YLS AND SOME P O L Y P H E N YL M I X T U R E S by G. FRIZ and H. VOSSEN.
European Atomic Energy Community - EURATOM. ORGEL Program. Joint Nuclear Research Center. Ispra Establishment (Italy). Heat Transfer Department. Brussels, February 1963 - pages 7 + figures 5.
The note presents two simple capillar}- methods for determining the density and the surface tension of polyphenyls.
Density is determined by measuring the length of a liquid thread and weight difference. Above the boiling point a sealed capillar}' is used. Surface tension is measured by the horizontal capillary method with optical observing of the liquid surface a t the capillary end. Results are presented for Diphenyl-, Terphenyl-isomers and two industrial mixtures.
EUR 1 6 5 . e
DENSITY AND SURFACE-TENSION MEASUREMENTS OF P U R E POLYPHENYLS AND SOME P O L Y P H E N Y L MIXTURES by G. F R I Z and H. VOSSEN.
European Atomic Energy Community - EURATOM. ORGEL Program. Joint Nuclear Research Center. Ispra Establishment (Italy). Heat Transfer Department. Brussels, February 1963 - pages 7 + figures 5.
The note presents two simple capillary methods for determining the density and the surface tension of polyphenyls.
Density is determined by measuring the length of a liquid thread and weight difference. Abo\-e the boiling point a sealed capillar}' is used. Surface tension is measured by the horizontal capillary method with optical observing of the liquid surface a t the capillar}' end. Results are presented for Diphenyl-, Terphenyl-isomers and two industrial mixtures.
í j a n - í o o s n s í i i l j ^ l í í i l l » * » !
EUR 1 6 5 . e
DENSITY AND SURFACE-TENSION MEASUREMENTS OF P U R E POLYPHENYLS AND SOME P O L Y P H E N Y L MIXTURES by G. FRIZ and H. VOSSEN.
European Atomic Energy Community - EURATOM. ORGEL Program. Joint Nuclear Research Center. Ispra Establishment (Italy). Heat Transfer Department. Brussels, February 1963 - pages 7 + figures 5.
The note presents two simple capillary methods for determining the density and the surface tension of polyphenyls.
Density is determined by measuring the length of a liquid thread and weight difference. Above the boiling point a sealed capillary is used. Surface tension is measured by the horizontal capillar)- method with optical observing of the liquid surface a t the capillary end. Results are presented for Diphenyl-, Terphenyl-isomers and two industrial mixtures.
E U R 1 6 5 . e
EUROPEAN ATOMIC ENERGY COMMUNITY - EURATOM
DENSITY AND SURFACE-TENSION MEASUREMENTS OF PURE POLYPHEN YLS
AND SOME POLYPHENYL MIXTURES
by
G. FRIZ and H. VOSSEN
1963
ORGEL Program
Joint Nuclear Research Center Ispra Establishment - Italy
Heat Transfer Department
C O N T E N T S
1. INTRODUCTION 2
2. MEASUREMENT OF DENSITY 2
2, 1. Apparatus and procedure of measur ing 2 2. 2. Est imation of accuracy, resu l t s 4
3. MEASUREMENT OF SURFACE TENSION 4
3. 1. Apparatus and procedure of measur ing 4 3. 2. Est imation of accuracy, resu l t s 5
4 . LITERATURE . . . , 7
5. DIAGRAMS
Fig. 1 Density of Diphenyl and of the Terphenyls Fig . 2 Density of OM1 and OM 2 Fig . 3 Surface tension of Diphenyl and the Terphenyls F ig . 4 Apparatus for density measurements Fig. 5 Apparatus for surface tension measurements
DENSITY AND SURFACE-TENSION MEASUREMENTS OF PURE POLYPHENYLS AND SOME POLYPHENYL
MIXTURES
SUMMARY
The note presents two simple capil lary methods for de te rmining the density and the surface tension of polyphenyls.
Density is determined by measur ing the length of a liquid thread and weight difference. Above the boiling point a sealed bapillary is used. Surface tension is measured by the horizontal capillary m e thod with optical observing of the liquid surface at the capillary end. Results a re presented for Diphenyl-, Terphenyl - i somers and two indust r ia l mix tu re s .
1. INTRODUCTION
The density of polyphenyls has a l ready been m e a s u r e d severa l t imes (R. 1, 2, 3, 4 , 5 ) . Mostly the boiling point l imited the curves , so that it was des i rab le to extend the p r e s s u r e and t e m p e r a t u r e range . On the other hand the a im was also to m e a s u r e high b o i l e r s , which a r e difficult to obtain in l a r g e r quant i t ies . By reason of th is a μ - m e thod was worked out which reques t s only the smal l quantity of about 50 mg substance .
The surface tension was measu red by BOWRING et a l . in 1961 (R. 6) with the ve r t i ca l capil lary method. In I sp ra the hor izonta l capi l lary-method was taken, for this method too reques t s only smal l tes t por t ions . The re su l t s of the two methods cor respond very well .
The measur ing p rogram s tar ted with pure substances of Diphenyl and of the Te rpheny l - i somers and the indust r ia l mix tures OM1 and OM2 from PROGIL. It will be followed by a p r o g r a m for high-bo i l e r s .
2. MEASUREMENT OF DENSITY
2 .1 . A p p a r a t u s a n d p r o c e d u r e of m e a s u r i n g
The density is measured in two steps with a slight difference. In the lower t empe ra tu r e range an open glass capi l lary (open at one end and closed at the other) is used. It is par t ly filled with the tes t liquid. Fil l ing is done with an injection-needle of g lass which is heated up together with the tes t capi l lary in a special filling furnace, as the polyphenyls a r e solid at room t e m p e r a t u r e .
In a glass furnace with an in ternal aluminium bloc (fig.4) the tes t capi l lary is heated up, and then the length of the liquid th read is m e a s u r e d . After that the difference of weight of filled and empty capi l lary is de te rmined with a μ -balance . Following a cal ibrat ing curve -obtained with water m e a s u r e m e n t s - t he re is a re la t ion be t ween volume and length of the liquid th read . Weight-difference and volume give densi ty . A li t t le cor rec t ion must be applied for t e m p e r a ture expansion of the glass capi l la ry . The dimension of the g lass ca pi l lary a r e :
m a t e r i a l l eng th o u t e r d i a m e t e r i n n e r d i a m e t e r
p y r e x 50 m m
6 m m 1 m m
The c a p i l l a r y l i e s in a b o r e of the a l u m i n i u m - b l o c , which i s s l i t t ed to a l low o p t i c a l r e a d i n g of l eng th with a c a t h e t o m e t e r by o b s e r v i n g the c a p i l l a r y in a 4 5 ° - i n c l i n e d m i r r o r . The fu rnace i s i n s t a l l ed h o r i z o n t a l l y to a s s u r e good t e m p e r a t u r e d i s t r i b u t i o n . The t e m p e r a t u r e i s m e a s u r e d wi th a t h e r m o c o u p l e in a s p e c i a l b o r e of the b l o c . In s e p a r a t e e x p e r i m e n t s it w a s v e r i f i e d tha t c a p i l l a r y - t e m p e r a t u r e and b l o c - t e m p e r a t u r e c o r r e s p o n d wi th in 0, 5 ° C .
The open c a p i l l a r y - m e t h o d i s work ing up to a t e m p e r a t u r e of about 30°C be low the boi l ing poin t . Then b e g i n s a m a r k a b l e l o s s of t e s t p o r t i o n by v a p o r i s a t i o n .
By r e a s o n s of t h i s , the r a n g e above t h i s t e m p e r a t u r e i s m e a s u r ed with a c l o s e d c a p i l l a r y . Half of the c a p i l l a r y i s f i l led with the l iquid and then s e a l e d . The f i r s t m e t h o d gave a b s o l u t e dens i t y da ta be low the boi l ing poin t . S t a r t i ng with one of t h e s e v a l u e s , t he expans ion of the l iquid t h r e a d a l lows c a l c u l a t i o n of d e n s i t y without weigh ing , p rov ided tha t the c a p i l l a r y d i a m e t e r i s suff ic ient ly c o n s t a n t o v e r the l eng th . The l a s t condi t ion w a s t e s t e d b e f o r e .
The m e t h o d r e q u i r e s s o m e c o r r e c t i o n s :
1) The t e m p e r a t u r e - c o r r e c t i o n for d i a m e t e r expans ion .
2) The v a p o u r - c o r r e c t i o n which c o n s i d e r s the fact tha t a c e r t a i n po r t i on of v a p o u r i s f i l l ing the v o l u m e above the l iquid t h r e a d . To c a l c u l a t e t h i s c o r r e c t i o n , e x p e r i m e n t a l v a p o u r -p r e s s u r e da t a and i d e a l gas l aw for the vapour w e r e t a k e n .
3) An op t i ca l c o r r e c t i o n for a d i f f e rence be tween the r e a d i n g and the r e a l pos i t ion of the inne r c a p i l l a r y end, by r e a s o n of l ight r e f r a c t i o n a t the half s p h e r e d top of the o u t e r g l a s s s u r f a c e . Th i s c o r r e c t i o n w a s c a l c u l a t e d , a s s u m i n g the top to be exac t ly a half s p h e r e .
In the r a n g e be low t h e boi l ing point t he two m e t h o d s can be comp a r e d . The c o r r e s p o n d e n c e of the two m e t h o d s l i e wi th in * 3 %.
2 . 2 . E s t i m a t i o n of a c c u r a c y , r e s u l t s .
The accuracy in the absolute (open capillary) method depends on the following: determination of weight-difference and length of l i quid thread, t empera tu re measuremen t and d iamete r change with tempe ra tu re . The f irst and the second e r r o r a r e both in the range of 1 %. The tempera ture deviation should l ie within 2 °C , which r e su l t s in a maximum e r r o r of * 2 ° / ° ° · The deviations of the cal ibrat ing points from a straight line show a scat ter ing of * 2 ° / o o , which a r e assumed to come from the f irs t two sources of e r r o r . The equalized curve is expected to be within this range so that the maximum e r r o r is est imated to be in the range of - 0, 5 %.
In the case of closed capi l lary, the vapour -co r rec t ion and opt ical correct ion a r e together 1 %. If they a r e calculated with an e r ro r of 20 %, we have an e r r o r of 2 ° /oo by r eason of i nco r r ec t calculation. Together with the other effects the maximum e r r o r in density will reach 0, 5 % too. The comparison of both methods in the range below boiling point shows a deviation from the smoothed curve of l e s s than * 3 ° / o o .
The measur ing p rogram s tar ted with the pure substances Diphenyl, o - , m - , and p-Terphenyi and the mix tu res OM1 and OM 2 of PROGIL. The t empera tu re range extended from the point of fusion up to 41§-420°C. The resu l t s a r e presented in d iagram 1 and 2.
3 . MEASUREMENTS OF SURFACE TENSION.
3 .1 . A p p a r a t u s a n d p r o c e d u r e of m e a s u r i n g .
F igure (5) shows the principle of the appa ra tus . A capil lary is placed im a furnace in horisontal posit ion. It i s filled about 20 m m with t e s t liquid. A l ight -source with para l le l beam and a te lescope allow optical observation of the flat capi l lary end. A smal l p r e s s u r e pushes the liquid to th is end. Without p r e s s u r e the liquid surface i s curvedas a half sphe re . At a cer ta in p r e s s u r e this surface i s p lane. In th is moment a l l the surface ref lects the light while at higher o r lower pres -s u r e s only a l i t t le spot appea r s . The effect i s ve ry sens i t ive . The p r e s s u r e i s measured with an ins t rument which allows reading of l-2/lOO m m H 2 0 p r e s su re (Minisi
-5-
The requi red liquid portions a re in the range of 50 mg.
The relat ion between surface tension and p r e s su re in the case of full wetting liquids i s very simple:
d , . a = — · Δ ρ (d = diameter of capillary)
4
With a cer ta in contact angle α we have the formula:
σ cos α = — · Δ ρ
The organic liquid was observed in a free capillary and the
contact angle was est imated to be zero , but this is not sufficient for
exact m e a s u r e m e n t s . By reason of this additional measurement s were
done with the bubble pressure method, which is independent of contact
angle. The mean resu l t was: both method correspond within 1%.
This work will be repor ted previously.
The capil lary is heated up in a furnace with internal bored coppercyl inder . Tempera tu re regulation was done by taking a constant tension source with regulating t r ans fo rmator . The tempera ture mea surement was effected in the same way as in the density appara tus .
The capil lary was calibrated with tes t l iquids, so that we have a re la t ive method. Test liquids were: water , benzene, glycerine, formic acid, carbon te t rachlora tüm and alcohol. Mean values from 5 ta bles were taken. They gave a maximum deviation from the best straight line of l e s s than 0, 8 %.
3 .2 . E s t i m a t i o n of a c c u r a c y , r e s u l t s .
The scat ter ing of p r e s s u r e readings at a cer tain t empera tu re
was within the range of * 3 ° /oo . The maximum deviation of the table
values from the straight line were 8 % o . Other sources of e r r o r a r e :
inclination of capil lary and change of diameter with length. The f irst
e r r o r was suppressed by a careful leveling, taking the liquid thread
itself as level indicator . The second source was proved by filling the
capil lary with different quantities of liquid.
-6-
The capillary diameter was found to have sufficient constancy. The tempera ture deviation should be the same as in the density appara tus , which resul ts in a maximum e r r o r of 4 ° /oo . Considering all these sources of e r r o r , we should have an overal l maximum e r r o r of about 1, 5 % for the product
σ · cos a
Assuming α to be zero, we give in d iagram 3 the r e su l t s of the measurements with Diphenyl and the three Terphenyls . The resul ts a re compared with the measuring points of BOWRING (Ref .AEEW-R 41) of I96I, which a re obtained with the ver t ica l capil lary method.
The diagram contents additionally the curve for a specia l Hexa-phenyl which was obtained within the measur ing program of pure high-boi le rs .
LITERATURE
Rl BOWRINGR.W. GARTON D. Α.
R2 ANDERSON Κ.
R3 CORK J. M. et a l .
R4 STONE J. P . et al .
R5 G E R C K E R . H . ASANOVICH G.
R6 BOWRING RW. et al .
AERE R/R 2762
ANL-5121(1953)
Rev. Sc. Ins t r . 1(1950) 563
Ind. Eng. Chem. 50 (1958)
NAA-SR-4484
AEEW-R 41
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