2334
Vol. 41, No. 10
INDUSTRIAL AND ENGINEERING CHEMISTRY
\*ellulose, have good R eather resistant qualities, clarity, and color stability. Type AB-500-1 is by itself rather low melting and somewhat soft €or many lacquer uses but offers interesting properties where solubility in the less polar solvents or a minimum susceptibility to water is desired. It also shows promise as a component of thermosensitive adhesives. Type AB-161-2 has special properties which make it desirable for certain uses, particularly the coating of airplane fabrics. It is definitely less aoluble and has poorer compatibilitieq than the other members ni rhe series. The same type esters in higher viscosity forms have approximately the same solubility and compatibility properties as the esters described above. These higher viscosity types are to bt preferred where film strength and flexibility are of major importance and where appreciably lower solids contents or higll wlution viscosities can be tolerated in application. The cellulose acetate butyrates described here offer definite ~iewpossibilities in the formulation of lacquer-type protective mat ings,
4CKNOWLEDGMEhT
The authors wish to thank Miss E. hl. Cross and 717;. H Griggs for extensive experimental work reported in this paper. LITERATURE CITED
Fordyce, C. R., and Meyer, L. W. A., IND. ENG.CHEM.,32, 1053 (1940).
Gardner, H. A , , and Sward, G. G., “Physical and Chemical Examination of Paints, Varnishes, Lacquers, and Colors,” 10th ed., pp. 164-5. Bethesda, Md., Henry A. Gardner Lsbcratory, Inc., 1946. Ibid.. D. 593. Method 11. Kline,’G. M.,Crouse, W. A . , and Axilrod, €3. M.,Modern PZastic.9, 17, No. 12,49 (1940).
Malm, C. J., Fordyce, C. R., and Tanner, H. A . IND.ENO CHEM.,34,430 (1942). O t t , E. “Cellulose and Cellulose Derivatives,” Chapter X by Gloor, W. E., pp. 107g3, 1081-2, Kern- York, Interscience Publishers, Inc.; 1943. Reinhart, F. W., and Kline, G. hl., IND.E m . CHEM..31, 1622 (1939); 32,186 (1940).
Ytull, D. R., Ibid., 39,517 (1947). RECEIVEDDecember 18, 1948.
Presented before the Division oi Paint Varnish, and Plastics Chemistry a t the 114th Meeting of the ERICAN AN CHEMICAL SOCIETY,Washington. D. C,
Evaluation of Adhesion by Ultrasonic Vibrations d
SAUL RIOSES, Suva1 Reseurch Laboratory. Washington, D . C . R . K . WIT”. b h n s Hopkins Univprsity. Baltimore, M d .
4 direct, q u a n t i t a t i v e method for measuring adhesion of organic coatings to both m e t a l and n o n m e t a l s u b s t r a t a is described. The method a n d a p p a r a t u s utilize a n electrodynamic s y s t e m for producing longitudinal u l t r a sonic vibrations in a m e t a l cylinder. A n organic film attached t o the free end of t h e vibrating cylinder separates f r o m the metal w h e n the force due to acceleration exceeds the adhesion force a t the interface. The accelerating force is d e t e r m i n e d by the frequency and the a m p l i t u d e of vibration. The method promises t o be readily applicable to manj- types of m a t e r i a l other t h a n t h o s e used in this investigation. A t present it appears to have a wide utility in the s t u d y of why two m a t e r i a l s a d h e r e a s in protective coatings and in b o n d i n g adhesives. J I o r e worlc is necesoary before the limits of this m e t h o d can b e a d e q u a t e l j determined w i t h respect to thin films.
0
RGA-C‘IC coatings such as paint, lacquer, mid varnish BCI as mechanical barriers and must remain attached to the substratum to provide protection against varying environmental Factors. (The term substratum refers to metal surfaces unlesb otherwise noted.) The phenomenon of this attachment of organic medium to the base material has been termed adhesion. In the past, adhesional forces have been separated into two broad .ategories-namely mechanical adhesion and specific adhesion. Mechanical adhesion has been defined as the bond due to the physical interlocking of the organic medium with the base metal surface irregularities. Specific adhesion has been interpreted as the bond based on the attractive forces a t the interface. Too often, the problem of developing a suitable method for measuring adhesion tias been made more difficult by the lack of realizationof what adhesionis: Adhesion is defined as the force normal to a unit area necessary to remove the film from the sub\tratuin.
The significance of adhesion to subsequent protection has effected the multitude of attempts to measure it. Efforts t o evaluate adhesion date back to the early part of this century. Prior to that time simple scratch and fingernail tests were used. Differenccs in adhesion were a matter of personal comparison without quantitative standard and were subject to the technologist’s experience and intuition. This same condition prevails today. Methods described in the literature (d,.4) have been developed to measure forces related to adhesion; all of these are comparative and actually do not measure adhesion alone but depend on some related property such as toughness, cohesion, bIittleness, hardness, or elasticity. The values obtained are useful, but there is no accurate scientific method of measuring adhesion; the exploratory tool needed to study adhesion effectively is lacking. After many surveys and interviews, the present investigation !?as undertaken to develop a direct, quantitative method for measuring adhesion. The requirements for a good, reproducible method have been analyzed and include controlled forces of application that are unidirectional (planar) and normal to the interface. The method must be applicable to films as they exist on a substratum and not films removed from the metal or acted on before actual test. It should be adaptable t o measurement of changes in adhesion under conditions of exposure without destroying the film-metal interface before evaluation. Highly desirable is a method that can give the data in fundamental units of mass, length, and time. Preliminary contact with various methods for producing usable ultrasonic vibrations led to the investigation of a method for measuring adhesion directly \Tith negliable effects from other film properties. This paper deals with the development of such a method for nieasuring adhesion. .4n organic film is attached to the free end of an aluminum alloy cylinder in which longitudinal vibrations are induced electrodynamically. The film separates from the metal when the force
October 1949
2335
INDUSTRIAL AND ENGINEERING CHEMISTRY
due to acceleration exceeds the adhesion force a t the interface. The accelerating force is determined by the frequency of vibration, the amplitude of vibration, and the mass and area dimensions of the film. I n this manner the adhesion of an organic film to a metal can be accurately evaluated within a short series nf wmnd intervals of apparatus operation.
voltage is related to the alternating change of capacity and, in turn, to the alternating change of condenser plate separation. The amplitude may be varied in small, discrete increments by regulating the power input to the vibrator. The frequency can be varied by changing the length of the vibrating cylinder.
THEORY OF LOYGITUDINAL VIBRATIOh
Longitudinal vibrations of rods and cylinders involve the density and the elastic properties of the material; the displacements are in the direction of wave propagation. For small changes of length, Hooke's law applies: Stress is proportional to the elongation per unit length ( e ) or strain, and is equal t o Er where E is Young's modulus of elasticity. When a rod is stretched along its length, the increase in length IS usually accompanied by lateral contraction. By making the length large compared with the diameter, the longitudinal motion predominates grpatly and the transverse movement becomes uegligible. The force required to stretch a rod is proportional to the cross section, and the mass set in motion is also a function of the area. For a given length and material, the frequency of longitudinal vibration in the fundamental mode is independent of shape and area. Tubes, rods, and cylinders have the same frequency for a given length. The maximum acceleration occurring a t the ends of a rod vih a t i n g in simple harmonic motion is given by the expression (w2a), for the path of the periodic vibration can be analyzed as the projection of a uniform circular motion on a diameter of the circle. ( ~ 2 aequals ) 4+&, where ( d u ) =tpeak acceleration: w = 2rf0; i = fundamental resonant frequency; and a = amplitude. .Ilthough longitudinal waves in rods and cylinders can be set up by various mechanical and electrical methods, an electrical rnethod-electrodynamic- 11-as selected after preliminary investigation as the most promising. I n this method the dynamic driving system develops mechani(.a1 forces by the interaction of the field of an electric current in a conductor and a steady magnetic field. A coil is placed in a steady radial magnetic field and an alternating current of the suitable frequency in the coil sets up an alternating magnetic field that interacts with the steady field to produce resonant vibration in the coil. When the coil is wrapped on a metal cylinder r)r the cylinder itself carries the current, the cylinder, of course. aperiences the vibration. The use of thin nonmagnetic cylintlers eliminates high eddv and hysteresis losses a t the higher frpquencies. Variations of this method offered good possibilities for obtaining large amplitudes in the range of 15 to 60 kc. St. Clair (6) has demonstrated the induction principle for high intensity sound generation. This Fork, in which the interacting currents Liere induced in the moving metal cylinder, provided the basis for the design of an electrodynamic generator suitable for producing ultrawnic vihrations above 15 kc iPP4RATUS
The block diagram oi the apparatus for measuring adhesion is shown in Figure 1. Variation in the gain of the system initiates the vibration in the dynamic vibrator. The signal generated by the condenser feedback is sent to a cathode follower for proper impedance matching. .%n oscilloscope and a Ballantine voltmeter record the wave shape, frequency, and voltage. From the t'olloyer, the signal voltage is sent to the preamplifiers for phasing and amplification, and then to the large power amplifier. The output of the power stack a t 100 ohms impedance is delivered to a special ultrasonic matching transformer from which a low voltage but high current signal is returned to the dynamic vibrator, completing the self-exciting oscillatory system. The amplitude of vibration is determined by the sensitive camcitance measuring setup in which the generated alternating
i
..--. Figure 1.
. .
Block Diagram of Ayparatur
Basically, the generator (an early model is showii in Figure 2) contains a vibrator-a resonant dural (24ST aluminum alloy) cylinder supported a t the center along its vertical axis-that is excited electrodynamically. The driving ring of the cylinder projects into the ring gap of a pot magnet whose central core carries the tightly wound exciting coil. The driving ring and the exciting coil are coaxial, and as a unit, function as a voltage step-down transformrr.
Figure 2.
First Yibrator Using an Electromagnet
Early attempts to provide the polarizing maglietic field centered around an electromagnet. Preliminary efforts revealed several advantages of permanent magnets over an electromagnet system. In the design now in use, cylindrical shells of Alnico were used and a magnet assembly (Figure 3, 8) designed around the properties of the shells. The gap dimensions were modified to decrease the length, and changes were introduced in the geometry of the pole pieces and in the assembling mechanism in an effort to decrease leakage lossc~s. The flux density avcraged about 11,000 gausses. .I newer design is being made to provide 16,000gausses in a gap length of 0.11 inch. There is some doubt whether such high flux densities can be realized with existing materials. Some other possibilities exist for increasing the available, energy in the gap. but these involve the sacrifice of higher frequencirs \ I B R 4 T I \ G CYLIYDEH
I n producing longitudinal vibrations in a f i t e i od of hoinogeneous material, the simplest mode of vibration is that of a half-uave length resonator-a node at the center and antinodes a t the ends Seglecting end corrections, the fundamental frequpncy is given by
where E = Young's modulus in dynes per square cm.; I = length in cm.; and p = density in grams per cubic cm.
INDUSTRIAL AND ENGINEERING CHEMISTRY
2336
Vol. 41, No. 10
surface is then measurable. T h e c a p lend themselves to all kinds of manipulations in aging, in corrosion and \Tear testing, and in subsequent adhesion evaluation. EXPERIMEVTA L PROCEDURE
Figure 3.
durfaces of the dural caps were crus-lapped with emery paper twginning with S o . 1 paper to remove the tool marks arid extending to -1 0 paper. Each cap was then lapped over a smooth chamois coated with levigated chromic oxide. The surface preparation is tedious and the nonuniformity of the caps can be laiti t o the Iiunian frnility of fatigue. So t w o surf':+ces iverci itleiiticai. iior n-a- the surface of any one cap coniplt~telyud'oi,iii, \\.iping x,ttlctl dust from tlie poli-hot1 surfaci.n-iili icii't llsii.5 tissut. aln-ays iiitrotlucccl a fen n i ~ l on i ~the. surface. Filni? ~ v ~ applied r o and alloned to d r ~ for - diffc.i,rslit 1l.ilgt lii 0; notctl in subscqueiit data. 1'01) styreilc,. \.l'Il t1 (-. It is important t u note that tl olution of ttie cap prol)lc,ni \I H lity of the method for measurB vital point in ijroadeniiig the i tig iitlhebion. Caps of any metal or nonmetallic niatcrial can l i I a ( * i ~oli i tlie main cylinder, and atlhvsion to a n-idc wloction of 1 1 1 3
Filmy are applied by drops to prepared caps, allurred t(Jtatkt2 up tyuilibrium positions, arid permitted to dry. A cap i b t h e L I hreatitd into place on tlic dural cylinder. Thcl dural cylinder is fitted on thc Bakelite guide rod and placet! in the ring gap. The ground wire fixed in the Lucite v:icuun: c1i:irnbc.r is attached to the cylinder by means of scotch tap Lucite chamber containing the micrometer rod and gage ' auri, hac tioncd on the magnet and a vacuum drawn until the prLsbeen reduced to 30 mm. of mercury or less. (Operation in a vacuum has two advantages: radiation losses of vibration are reduced and thereby permit higher amplitudes to be reached; and dangers of exposure to ultrasonic vibrations are niininiizcd because the lack of air stops the transmittal of energy through tht. atmosphere to the personnel.) The micrometer condensrr electrode is brought into positior, until it just makes contact n-ith the top of the cap. This posit,iolj is determined by inserting the neon light circuit shown in Figure 3. The light goes off when the electrode is backed off 0.00001 incl, or less. It is from this point that the d of condenser separation is adjusted to 0.007 inch. The condenser is then connected to th!. cathode follower containing the polarizing voltage. -411 circuits (Figure 5 ) as well as t'he measuring voltmeterr art. turned on. Closing the plate switch of the power amplifier start+ the vibration. The "on interval" of vibration lasts but 1.5 seconds, long enough for full amplitude to he developed. The power to the exciting coil is adjusted in discrete steps until the proper amplitude is reached. Each discrete power change usually requires a separate start-up, a t present; modifications are under way to make continuous operation possible. T h e point of separation which is visible in the indepeiident movement of the film is judged to be the limiting value of the force necrssary for rupture. In all cases the film was observed t,o
, .
~i~~~~~ 4.
~~~~l
~
~ - l Showirla i ~ ~ Attachment d ~ ~ ~ Sample Caps
,,f
2337
INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1949
intact and no portion was found to remain on the cap m-hen viewed under a microscope. The ambient temperature rise of the cvlinder differs in-ignificantly from zero tJe
RESULTS
i f e ~ vsample measurements of adhesion from types of films used are presented. The legends Are explained and the force of adhesion has heen d c u l a t e d as shown in the sample calculation. Thcse few data are presented to show the type of information that is recorded and the: trend of adlitxiion noted. A more detailed survey and analysis ut' more roniplete data are presented in a suhseiiui'iit, paper (5)in which somc new conccptp of YiIhwion arc%tlisclosrtl as a rt>sult o f the qunnti.xtivi, tlata oiitained. Ihes and thcrmosetting rnaft,rials. two
Figure 5 . 1 = Preamp 'lo. 1:
+tack:
S 4 M P L E CALCtiLATIO'l OF 4DFIESIOh
Csuig the open circuit voltage theor?-, the Ballantine uutput boltage is related to the open circuit voltage of the feedback n-hich. in turn, is converted to the amplitude of displacement.
In this calculation, the recorded root mean square values are *nnvertedto peak voltages and accelerations. Voltage output (recorded) = 0.38 = 0.045 Zero Corrected voltage = 0.335
Front V e w of Electronic Gear
2 = preamp So. 2 : 3 = Ballantine voltmeter: 5 = oscillo-cope: 6 = ow illator; 7 = voltmeter
1 - powrr
F/A4is the calculated force of adhesion (of nt:cwsity, an averagr value) for the particular film xvhose dimensions appear to the Left in the corresponding horizontal row. S , is the related point stress as defined. (3),and calculated as shnn-n in the sample calculation. Polystyrene (molecular m i g h t 80,000 to 00,POLYSTYRESE. 000) mas deposited from a toluene solution in layers. The mass was permitted to dry for 144 hours at 40" C. The d of condenser separation was 0.007 inch and the frequency of t h e dural cylinder xas 22,500 cycles per second:
This voltage output (,from ralibratiou curve) corresponds t i l
1- = 2.75 (root mean square) X 1.41 The amplitude is given by 0.036 T' = -L-arid d d - a
=
=
3.89 volts
0.007 inch
4
0.310 0,300 0.295
li
0,180 0.165 0,185 0.12.5 0.130 0.125
a = 0.00086 inch = 0.00218 em. The peak acceleration is given by uzu o r 22.5)2(103)2 x (3.14)2(2)2 x o . 0 0 ~ 1 8= -437 X l o 5em. per squa,re The force is given by mz or
(437 X 1oj) X 0.047 grain
=
0,0302 0.0273 0 0260 0 02ib 0.0283 0,0973 0.0294 0.0297 0.0200
0.387 0.407 0.415
0.31 0.28 0.27
32.4 30.5 28 1
134.2 131.2 127 F
0.636 0.654 0 625
0.19 0.18.; 0.19 0 11 0 11.5 0.10
10 i 9.7 10.9 6 ,8 6.2 1 [I
$8.3 43.2 49 . 4
0,502 0 651
0.780
I'olyhtyrenr (molecular veight 80,000 to 00,POLBSTYRESE. 000) was deposited from a toluene solution. The mass was permitted to dry for 80 hours at 45" C. The d of condenser separation was 0.007 inch and the frc,qucncy of thtl dural cylintitsr was 23,600 cycles per second:
204.5 X lo4 dynes
'l'hv area of film contact is 0.518 square em. and the stress k ' ~ 4is
204.5
x
Voltage. Volt 0.530
10"0.518 = 3gt5 X lo4 dynes per square r m .
Since 1 pound per square inch equals 6.89 X lo4 dynes ptsr qquare em., the stress or adhesion is
=
df rla
0.440
0.465
= d a z p polgstyrena X maximum height = (437 X lo5) X (1.01) X 0.026 = 118 X
0.403
0.400
E'/,% = 395 X 104j6.89X lo4 = 57.2 pounds per squarr iiic:h To calculate S,, the densit?. is con5ideri.d constant.
$tress
l1.k
I(i 3 13 i
IO'
dynes per square m i . = 172 pounds prr square inch
The following samples of adht&ii data have been obtained 13) k.xperimenta1 procedures outlined previously. T h e voltage coliinin indicates the voltage generated by the vibrator a t the time of 5eparation of the film from the metal. The amplitude is nhrained from the voltage as shown in the sample calculation. The columns mass, area, and maximum height record the dirnrnsions of the film removcd at the corresponding voltagr.
Mass, Gram 0.0468 0.0571 0.0310 0 0582 0.0481
Srea, Sq. Cin. 0.611 0.606 0.295 0.573 0,595
Max. Height. Cin. 0.23 0.27 0.285
0.23 0.23
P , 'I,
Lh./Bq. Ill. 68.2 84.2
62.1 67.5 60.2
Sm.
Lh. 'S(i In. 213 191 177 li3 179
VTHH. \717H€I:c:opiilynier of vinyl ftccrate and vinyl chloride, \vas deposited froin an acetone solution in thin layers. The rnass was pcrmittcd to dry for 72 hours at 40" C. The d of conclenser separation n-as 0.007 inch and the frequency of the dural rylinder was 23,600 c y c l ~ per s srcond:
4
H
Voltagr Volt
l\Ia>s. Gram
0.380 0.340 0.290 0,300 0.160
0,0076 0,0106 0.0104 0.0095
0.145
0.120 0 lXl
0.0103 0.0083 0.0175 0.01fli
=\rea,
Sq. Cm. 0.273
11ax. Height, Ciii.
0.299 0.275 0.281
0.12 0 . 15 0.15 0.14
u . 374
0.09
0.368 0.440
0.369
0.09
0.11 0.09
P'l.4. Lb. 'Sq In. 17.8 19.9 18.3 16.7 6.1 5.2 8.0
6.4
Sn,
1.h.. 811
In. 104 113 100 94 27.1
26.9 "2.4 26 P
INDUSTRIAL AND ENGINEERING CHEMISTRY
2338
4CKhOWLEDGMENT
Vol. 41, No. 10
BIBLIOGRAPHl
The authors wish to express their gratitude t o C. F. Bonilla of the Johns Hopkins University for his assistance in this investigation. In addition, the writers thank P. Borgstrom and A. L. Alexander of the Kava1 Research Laboratory who made it possible For the major portion of the experimental work to be done a t the Saval Research Laboratory. The kind cooperation of P. N. Arnold of the Sound Division, the excellent aid of C. Bloedorn in the design and construction of electronic systems, and the fine machine work of R . Chambers, all of the Naval Research Laboratory, are hereby gratefully acknowledged.
(1) Gaines, N., Physics, 3, 209-29 (November 1932). ‘2) Gardner, H., “Physical and Chemical Examinations
01
Paint$.
Varnishes, Laquers, and Colors,” 10th ed.,pp. 175-81.Retheada. Md., H. A. Gardner Laboratory, Inc., 1946. 13) Moses, Saul, IXD. EXQ.CHEM., 41, 2338 (1949). (4) New York Production Club, OficiuE Digest Federation Paint & Varnish Production Clubs, p. 141 (October 1939); p. 167 ( O r tober 1940). ( 5 ) St. Clair, H. W., Rev. Sci. Instrurncm.3, 12,No. 5, 250 (1941). RECEIVXD July 9, 1948. Presented before t h r Division of Paint, Varmsh. a n d Plastics Chemistry a t t h e 114th hlwtin. I f t.he AMERICAS CHEMICAL SOCIETY.Wa-hineton. D. C.
THE NATURE OF ADHESION Analysis of the data on the adhesion of polystjrene.
VYHH, and methyl methacrylate systems to aluminum alloy has shown that adhesion in the cases investigated depends on the presence of a fluid, or quasi fluid, or mobile state at or near the film-metal interface. The data. obtained frnm the new technique in measuring adhesion
I
N A precedirig paper ( 1j, the ultrasonic niethod for nieasuring the adhesion of organic coatings to metal substrata was described. This paper presents results of adhesion measurements and a discussion of the correlations leading to a partial explanation of adhesive forces. The following tables of adhesion data were obtaiiied by experimental procedures as outlined ( I ) . The voltage column indicates the voltage generated by the vibrator a t the time of separation of the film from the metal. The amplitude column i. obtained from this voltage reading as shown in the sample calculation ( 1 ). The colunins mass, area, and maximum height record the dimensions of the film removed a t the corresponding voltage. The column F I B is the calculated force of adhesion (of necesjity, an average value) for the particular film whose dimensionGroupappear to the left in the corresponding horizontal ron ings A , B, etc. call attention to differences in F/A under the ham(’ !drying conditions. 8, ip the related point, streqs R Q defined in a Inter section.
by ultrasonic vibrations, represent adhesion as defined in a previous paper ( I ) . An explanation of simple example+ is offered in support of the concept of mobility. The general picture of mobility is now being developed for all types of adhesion between the variou- nrganic system. a n d -~ihstrata.
Polystyrene (mo1ecular weight 80,OOU to 90,OOO) with depuaiteti from a solution of benzene (about 11% solids) in one thin film The mass was permitted to dry for 20 hours a t 25’ C. The d of condenser separation was 0.007 inch. The frequencv of the dural was 25,000 cycles per second:
I).
1.5,;
\lass, Gram 0,0028 0,0026 0.0027 0,0026 0,0028 0,0027 0.0027 0,0026 0,0026 0 0029
4 1
1l i
0 0030
\-olcage
Volt 1 ) . 136
0,140
0.135 Cl.160 0.155 0. I55 0.145 0.145 12, 1.55
Polysty~ene(molecular weight 80,000 t o 90,000) n as deposited From a solution of toluene in two or three layers to form the film. The mass was permitted to dry for 80 hours a t 45’ C. I n this qeries, the d of condenser separation was 0.007 inch with the exception of the first run in which d was 0.005 inch. The frequency i f the dural cylinder was 23,600 cycles per qecond: 1Ia.a. Gram
.Ires, Sq. Cm.
0.580 0,290
0,0468
0.636 0.534 0.560 0,518 0,639 0.602
0,300 0,380 0.640
0.515
0.463 0.405 0,400 0,440
0.530 0.355 0.345
n
4113
0,0646 0.0560 0.0520 0,0400 0,0450 0.0481 0.0522 0.0582 0.0510
0.0468 0.0830
0,0542 0.0571
Mean
0.595
Height. Cm. 0.22 0.24 0.22 0.29 0.21 0.215 0.23
0.601
0.24
0.573 0.595 0.611 0.560 0,550 0.606
0.25 0.236 0.23 0.24 0.24 0.27 0.238 0.02
Standard deviation
Max, Height Cm.
iInpiiruae
0.0102 0,0064 0.0089 0.0064 0,0085 0.0089 0.0086 0.0076 0.0076 0.0103
0.000698 0 000557 0,000581 0.000546 0,000686 0.000686 0,000648 0.000648 0 000688 0 000648 o oon648
Cm.
0.010?
I A Lh. Sq. In 2.52 1.86 2.02 1.85 2.4i 2.36
2.2:, 2.15 2.20 2.58 2.52 2.B 0 . 2.5
0 00s-
n nrl
Alethy1 iriethaciylate polyme~wan depwted from a solutioii
d acetone and methyl ethyl ketone. The mass applied in several
DATA
Voltage. Volt
0.282 0.281 0,280 0.282 0,282 0.282 0.281 0,283 0,283 0.283
\lean Standard deriarinn
~
Max.
Area,
Sq. Cm. 0,282
FIA, implitude, Lb./Sq. Cm. In. 1).00222 69.8 0.00164 0,00181 0.00196 0,00328 0.00268 0,00234 0.00209 0.00208 0.00227 0.00279 0,00186 0.00181 n.no213
63.4 52.2 $7.2 64.7 63.9 60.2 58.1 67.5 62.1 68.2 56.3 57.0 64.2 61.8 4.9
s.,
Lh./Sq.
In.
157 j31 ~ 7 2 180 229 191 i79 167 173 177 213 147 145 191
lavers TIas permitted to dry for 100 hours at 40” C. The d of contlenwr separation was 0.007 inch. and the frequencx o i t h p i111r;il n as 22,500 cycles per second: \oltage Volt U.430 10.330 0.4Al)
0.326 0.42.5 17.405
0.335 0,370 0,340
o RZO
Xlssi Gram
Area 8q. Cm
0.0220 0,0365 0.016: 0,0270 0,0240 0,0280 0,0293 0,0282 0,0300 0.0310
0,402 0.578 0.400 0.430 0,475 0.492 0.460 0.474 0,470 0.469
Mean
3tandard deviation
Max. Height Cm. 0.2i
0.24 0.14 0.24 0.23 0.23 0.26 0.25 0.26 0.26 0.24 0.03
41np11
tude Cm IJ.0022t 0,00172 0,00233 0.00165 n.00221 0.00211 0.00171 0.00191 0.00178 11 n
m~n
FQA, Lh./Sc,. In. 35.6 31.5 28.0 30.2 32.4 34.7 31.6 32.8 33.1
32.3
&m.
Lb./Bq
In. 207 141
112 136 174 18i 1.52 16i 156 151
32.2 2.0
VYHH (cupolymer of vinyl acetate and v111yl chloride) was deposited from a solution of acetone in several thin layers. The mash naq permitted to dry for 72 hours a t 40” C. In these series. the d of condenser separation was 0.007 inch, and the frequency of the dural rvlinder was 23,600 cycleq per second:
