I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
October 1953
ACKNOWLEDGMENT
The work discussed was performed as a part of the research project sponsored by the Reconstruction Finance Corp., Office of Synthetic Rubber, in connection with the Government Synthetic Rubber Program. The authors are indebted t o Elizabeth Peterson Leighly and Helen Miklas for the infrared data on the cinnamaldehyde copolvmers. The other infrared data were furnished by the Anderson Physical Laboratories, Champaign, Ill., and the authors are especially indebted to R. L. Bohon for his aid in their interpretation. The Micro-Tech Laboratories, Skokie, Ill., performed the microanalyses reported. The authors are indebted to Stanley Detrick, E. I. du Pont de Semours & Co., for the MP-635-S used as an emulsifier in the acid-side recipes. This emulsifier had the following percentage composition : Sodium alkanesulfonates, approximately Cle
Vnreacted hydrocarbons
Sodium chloride Sodium sulfate Balance water, and about 3% isopropyl alcoho
49 5
10.3 0.86 0.4
SUMMARY
h study of the cwolymerization of butadiene with cinnamaldehyde, cinnamic acid, methyl cinnamate, ethyl cinnamate, and trans-cinnamonitrile showed that all these monomers yield rubbery copolymers with butadiene and certain of these have been evaluated and compared to current synthetic rubbers of the GR-S type. In general, these monomers to the extent of 10 to 90 parts of butadiene yield copolymers roughly equivalent to the standard GR-S which contains approximately 25 parts of styrene. The cinnamic acid-butadiene copolymer has excellent tensile strength. The trans-cinnamonitrile copolymer shows no improvement in oil resistance over GR-S. These cinnamic acid derivatives all enter the growing butadiene copolymer chain somewhat more slowly than does butadiene, so that the copolymers contain a lower percentage of the comonomer than does the charging stock used. Some experiments were conducted on the copolymerization of these cinnamic acid derivatives with other monomers than butadime, the copolymerization of the furan analogs of the cinnamic
2317
acid derivatives, and the copolymerization of a-cyano-@-phenylacrylic acid derivatives. LITERATURE CITED
Bartlett, J. H., U. S. Patent 2,612,475(Sept. 30,1952). Bechert, C.,J . prakt. Chem., 50 (2),1 (1894). Blicke, F. H., Ber., 47, 1352 (1914). BobaIek,E.G.,U.S.Patents2,470,752,2,470,757 (May24,1949). Britton, E. C.,Marshall, H. B., and LeFevre, W. J., Ibid., 2,341,175(Feb.8,1944). Carpmael, A., and I. G. Farbenindustrie A,-G., Brit. Patent 387,381(Feb. 6,1933). Carrick, J. T., J . prakt. Chem., 45 (2),501 (1892). Du Pont de Nemours & Co., Inc., E. I., Brit. Patent 494,752 (Oct. 25, 1938). Emerson, W. S., U. S. Patent 2,498,616(Feb. 21,1950). Erlenmeyer, E., Ann., 137,334 (1866). Frank, R. L., Adams, C. E., Blegen, J. R., Deanin, R., and Smith, P. V., IND. ENG.CHEM.,39,887 (1947). Garvey, B. S., Jr., Am, SOC.Testing Materials, D 471431‘. Gavatin, J., Swedish Patent 121,341 (April 6, 1948). Gehman, S. D.,Woodford, D. E., and Wilkinson, ‘3. S., Jr., IND. ENG.CHEM.,39, 1108 (1947). Gohsez, J., Bull. sac. chim. belg., 41,477 (1932). Habgood, B. J., Hill, R., Isaacs, E., and Morgan, L. B., U. S. Patent 2,231,623(Feb. 11, 1941). I. G. Farbenindustrie A.-G., Brit. Patent 368,567 (March 10, 1932). Inglis, J. K.H., “Organic Syntheses,” Coll. Vol. I, 2nd ed., p. 254, New York, John Wiley & Sons, 1941. Lapworth, A., and Baker, W., Ibid., p. 181. Marvel, C. S., Fukuto, T. R., Berry, J. W., Taft, W. K., and Labbe, B. G., J. Polymer Sci., 8,599 (1952). Marvel, C. S., and McCain, G. H., J . Am. Chem. Soc., 75,3272 (1963). Marvel, C . S., and Meinhardt, A., J . Polymer Sci., 6,733 (1951). Marvel, C. S., Menikheim, V. C., Inskip, H. K., Taft, W. K., and Labbe, B. G.,Ibid., 10,39 (1953). Marvel, C. S., Peterson, W. R., Inskip, H. K., Taft, W. K., and Labbe, B. G., IND. ENQ.CKEM., 45, 1532 (1953). Marvel, C. S., and Wright, J. C., J . Polymer Sci., 8 , 495 (1952). Mayo, F. R., and Walling, C., Chem. Revs., 46, 191 (1950). Plaut, H., and Ritter, J., J. Am. Chem. SOC.,73,4076 (1951). Posner, T.,J . prakt. Chem., 82 (21,425(1910). Seymour, R. B., U.S. Patent 2,465,318(March 22,1949). Stoesser, S. M., and Lowery, R. D., Ibid., 2,232,930(Feb.25, 19411. (31) Swart, G.H., Ibid., 2,594,824(April 29,1952). (32) Vanderbilt Co., R. T., New York, N. Y., “Vanderbilt Rubber Handbook,” 9th ed., p. 65,1948. (33) Wagner-Jauregg, T.,Ber., 63, 3213 (1930). RECEIVBD for review May 8, 1953.
ACCEPTED July 18, 1953
Temperature-Indicating Paints J. E. COWLING, PETER KING, AND ALLEN L. ALEXANDER Naval Research Laboratory, Washington, D. C . D
I
MMEDIATELY prior to World War 11, a few materials of foreign origin evoked considerable interest in this country as a result of their ability t o change color on reaching specific temperatures. When applied t o equipment that becomes heated during operation, they provide a convenient means for estimating the peak temperature reached during the period of use. For example, the application of small spots or stripes of several colored materials to an operating mechanism, such as a commutator on an aircraft, each of which assumes well-defined but strikingly different color characteristics a t progressive temperatures, provides a useful means of recording the top temperatures reached during flight. Furthermore, by coating an aircraft cylinder completely with a film of selected temperature-sensitive paints, a record may be produced of the maximum temperatures involved during a given operation or evaluation. Obviously such color changes should be permanent, and the
paints should not return t o their oTiginal shades before a reading can be made. The value of such data in the design of remote or difficulty accessible components is obvious. Most materials of this nature, including pigmented crayons, being of foreign origin became unavailable at the beginning of World War 11, and for this reason this work was undertaken t o establish a source of supply based on domestically available materials. During the past 2 years considerably more information has been released on the products manufactured abroad, and it has been revealed t h a t some of the compounds described herein have been studied elsewhere; however, a great many others are quite novel. Mayer (8) has described a number of compounds t h a t change color when heated. A number of patents have been issued which describe in general terms the reaction of a variety of materials sensitive t o heat. Two of these (4,6) discuss color changes occurring in selected compounds with the liberation of ammonia and
2318
INDUSTRIAL AND ENGINEERING CHEMISTRY
ammonia complexes as well as carbon dioxide and water. Color changes accompanied by the liberation of ammonia are less likely t o be reversible. Perez (8)has described the use of iodides of the heavy metals as providing color changes coincident with specific temperature levels. Furthcr, h k y e r ( 7 ) and Tyte (9) have described the use of these techniques in estimating temperature peaks. At least one independent effort has been made in the United States t o study temperature sensitive complexes with a view of incorporating them into practical formulations for estimating peak temperatures. Carter ( 1 ) has described a number of acceptable pigments for this application and has recorded considerable data in the form of time-temperature relationships in which reproducible color changes are considered reliable. Carter's list of 125 compounds ( 1 ) perhaps represents the largest group numerically that has been studied and reported in the literature. The great majority of these, however, were rejected because of instability, too gradual color change, no change, no line of discernible demarcation, or lack of reproducibility. Our experimentb indicate that in some instances this latter fault may result from lack of purity in the salt or pigment and in the selection of an appropriate matrix in which t o carry the pigments n-ithout confusing the primary color change by an adulterat'ion due t o the reactivity of the matrix Descriptive discusEions of t,he use and application of these products with little or no reference t o their chemical constituency are more abundant. Guthmann (a,3 ) has offered excellent suggestions on the wide adaptation of thermally sensitive colors to a wide variety of applications Tvith special reference to a technique for detecting flaws in aircraft cylinders. IT-illiams ( 1 0 ) has described the properties of wax crayons composed of temperaturcsensitive pigments as used currently in England. However, little is disclosed of the chemical nature of the compounds involved. The literature further indicates that while considerable study has been made of the heat stability of a large number of compounds, reports of their adaptation to practical formulations are quite limited with the exception noted (1). Such informat'ion as is available appears principally in the foreign patent literature with many of the essential det'ails lacking. As a result, some of the work described herein may appear in part a duplication of prior effort, but it was deemed essential t o provide unreported details and t o check any possible fallacies attributable to thc use of impure or improperly dispersed salts and pigments. At the outset several problems were apparent almost immediately. The first was t o obtain a n adequate vehicle to carry the pigment which is sufficiently stable t o withstand the elevated t,emperatures encountered u-ithout decomposing and assuming a color likely t o confuse the pigment color change. Secondly, care was required in the selection of pigments that will assume a characteristic color change a t a specific temperature but will not assume a similar color with prolonged heating a t a somenhat lower temperature. Finally, when working with formulations to function below 100" C., selection of pigment must be made to exclude those that return t o their original color after heat,ing has ceased. Our immediate purpose n-as t o provide t v o series of materials-ne t o function between 50" and 100" C. and the second to extend from 100" to 275' C. Therefore, the availability of likely materials was surveyed with these temperature ranges in mind. Because of the relative instability of many of the compounds of cobalt along with their distinctive coloring, this element invited special interest around which many complexes might be built. By heating such compounds composition changes occur usually accompanied by distinct color alteration. The more stable compounds usually require higher t'emperatures. This fact points immediately to similar possibilities with the conipounds of nickel, iron, manganese, chromium, copper, and a few remaining elements of minor importance. Where color change results entirely from a temporary loss of water of crystallization such compounds are useful only where color difference may be observed immediately before cooling. By starting with compounds
Vol. 45, No. 10
contaiiiing alcohol of cry~tallizationsomcwhat lower transition temperatures arc obtainable, but, quite often these complexes are similar in color to those containing rr-atcr and must be read before time permits readsorption of water. PAINT PREPARATION AND EVALUhTIOiV
A number of distinctive types of resinous vehicles were studied including alkyds, pure phenolics, tung oil varnishes, sodium silicate, and several types of methacrylate polymers. From these it was apparent that a solution of methacrylate resin, properly plasticized, provided an adequate vehicle for carrying pigments, and it was used exclusively as indicated in most of the Eormulations reported here. The following cobaltous compounds iwre available r;omniercially and the C.P. grades were used n-ithout further modification: acetate: citrate, borate, fluoride phosphate, silicofluoride, and f o rma t c . Ot'her compounds investigated for use in thc 50" t < J 100" c. rnrige were prepared by reacting a saturated solution of tlie metal salt with a solution of hexamethylenetetramine or p\~ridine. Equivalent quantities of the several intermediates were placed in reaction flasks and geiit'ly heated. In general the desired product precipitates readily, although when pyridine was one reagent the reaction v a s slower, and in some instances the product was soluble in pyridine. Separation was a.ccomplished bj- evaporation of the pyridine at temperatures somewhat' below t h critical temperat,ure of the pigment concerned. The exact structural formulas of these pigments were not ascertained, and they may therefore consist of a mixture of two or more compounds. However, there was no difficulty in duplicating the reaction products repeatedly. I t is believed that the predominant compound is of the type Co(CXS),.2C&l,zK;,.lOH,O. Each pigment or complex \vas incorporated into the selected matrix (usually a solution of methacrylate resin) by passing it through a +inch three-roll mill. A s might be eupect,ed, fen- of these compounds possess good wetting properties as normally associated with good pigments. Therefore, formulas containing sufficient' pigment to provide some sort of acceptable hiding pon.er XTere someivhat pasty and were not as smooth as reyuircd of most high grade enamels. Perhaps the inclusion of some easily wetted neutral pigment would provide improved working properties. The inclusion of a whitme pigment to increase hiding strength and to enhance the physical qualities with no interference of required color characteristics mas successful in at,least one instanc.e. For application the formulat,ions mwc reduced t,o low viscosity t o provide for extremely thin films. For evaluation the paints were applied in iz long stripe over the cntire length of one side of a 4 X 12 inch anodized iliurninuni panel. In addition, a series of short narrom- equally spaced stripes \\-as applied t o the other side of the panel perpendicular to the long stripe. B3- this means a continuous and intermittent temperature gradient could be applied t o the paint'. M*hm thorough137 dry one end of the panel mas heated either in an electric furnacc or on a hot plate. In short order a temperature gradient was established along the entire length of the panel whereupon the paints began to change color. Changes progrcssed along the stripes as the temperature gradient increased until the nmxinium and constant gradient was reached. At that point no further color change occurred in the pigments recomniended here. The peak temperature gradient was maintained for 6 hours to ensure that a t lower temperatures gradual drifting to colors resembling the critical color differential did not occur. On reaching the maximum tempera.ture t,he significant line of demarcation was noted t o distinguish any drifts that might follow as a result of continued heating. I n order t o check the stability of these systems further, the panels were heated again the fojlowing day a t the same temperature with no shift or change in the degree or location of the color difference established initially. Temperature measurements along the surface of the panels \%-ere '
e
October 1953
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
made by conveniently located thermocouples and/or by a surface pyrometer. The temperature existing a t the point of greatest color differential was taken as the critical temperature for that material. As the panels cooled they were observed carefully for any trend toward a reversion t o original color or any other significant signs of color deviation. In some instances the pigments reverted to their original color gradually and in others they assumed an "off shade" of their initial hue. In some such cases sufficient contrast in shade was maintained t o be of essentially the same value as if no reversion had occurred. It was noted that some pigments assumed their original color in a matter of a few hours whereas others required a week or more. From scores of compounds examined, those listed below appear t o be of greatest significance for practical application t o this problem. In many instances no changes were discernible and in others differences were considered to be of no practical value and are not reported. All temperatures noted are accurate within
2319
Ammonium vanadate Ammonium u r m a t e Copper pyridine thiocyanate Chromium ethylenediamine chloride Chromium ethylenediamine thiocyanate Aquopentaminecobaltic chloride These compounds were incorporated into a formula approximately as follows: Complex, grams Methacrylate solution (30% solids), grams Dibutyl phthalate, grams Lacquer thinner, cc. Titanium dioxide, grams
23 50 25 20 10
The color changes and temperature a t which thcy occur are noted in Table I.
1 5 " c.
~~
1. Cobaltous hexamethylenetetramine iodide ( Co1z.2C~H22N~.TABLEI. COLOR CHAKGESAND TEMPERATURES lOHzO)-from dull brownish-pink t o green a t 50" C. The color AT WHICH T I i E Y OCCUR change is sharp and the contrast exct.llent. However, on cooling the green reverts in a few hours to a dull but light pink. This Temp. color is emily distinguishable from the original shade, and the Range, Compound Color Change C. line of demarcation is sharp Chromium ethylenediamine chloride Yellow t o red 117-121 2. Cobaltous pyridine arsenate [CO(ASO~)~.(P~~)~.~OHZO]Red to blaok 26lF278 from brown to light blue-green at 50" C. The color change is ' Copper pyridine thiocyanate Green t o brown 117-122 sharp and the contrast excellent. On cooling the blue-green Brown t o black ,032-260 changes to a light tan which also displays excellent contrast Aininoniuin vanadate White to pink 128-134 and a sharp line of demarcation with the original brown. Pink to black 160-lfi8 3. Nickclous hexamethylenetetramine bromide (NiBrZ.Yellow to red Chromium ethylenediamine thio115 -124 2C&l&4.10H~O)-from green to blue at 62" C. The color cyanate Red to black 240-263 change is sharp and distinct, but on cooling this contrast is lost Red to black 168-176 Aquopentaminecobaltic chloride as the pigment reverts in a few hours to its original shade of green. 4. Cobaltous hexamethylenetetramine thiocyanate [Co(CNS)2.2C~H12N4.10H20]-from orangepink to blue a t 74" C. The color change is sharp and the contrast excellent. This DISCUSSION color change slowly reverts to a light pink over a period of a week or more. The final color is also easily distinguished from the From the results of the work reported herein it is evident t h a t original. hundreds of compounds of interest to this application exist. 5. Cobaltous acetate [ C ~ ( C ~ H ~ O ) ~ l.pink ~from to purple Depending on the scale of application of such techniques a more a t 82" C. The color change is excellent in quality. On coolmg, elaborate investigation may be justified t o establish more clearly the blue very slowly reverts to its original color, the process the exact mechanism of change with a view of providing a wider requiring 2 weeks or more t o reach completion. range of materials indicative of more narrow temperature bands, 6. Cobaltous fluoride ( CoF2j-from orange-pink to light pink with slight lavender tint a t 84" C. The contrast is fair and The experiments described here indicate that complexes of cothe line of demarcation sharp. This new color does liot revert. baltous chloride with ammonia, hydroxylamine, hexamethylene7. Cobaltous borate [Co3(Bo3)2]-from drab pink to purple tetramine, pyridine, ethylenediamine, hydrazine, etc., possess at 85" C. The contrast is fair, but the line of demarcation is distinct properties applicable t o the problem and that most of not sharp as the shade changes very gradually over a range of these compounds are easily prepared. Similarly complexes of from about 82" to 92" C. This compound about 10" C.-i.e., sloivly reverts to its original color on cooling, requiring 2 or more many additional cobalt salts are possible. Furthermore, analoweeks to reach completion. gies with compounds of iron, nickel, and copper should exist. 8. Cobaltous pyridine thiocyanate [Co(CKS)z(Pyr)2.10Hz0) From these experiments it would appear that several general con-from lavender to blue a t 93" C. The contrast is excellent and clusions are ,justified. the line of demarcation sharp. The color is stable. A very thin coat of this paint must be used for good results. 1. The relative instability of coordination compounds such 9. Cobaltous silicofluoride (CoSiF~)-from a dull orangeas the cobalt amines makes this class of materials an ideal one pink t o a bright pink a t 99 C. The quality of the color change from which to obtain temperature indicating paint pigments is excellent and it does not revert on cooling. that are sensitive to relatively low temperatures. 10. Cobaltous phosphate [C03(PO&]-from pink to blue a t 2. The stability of the complex compound and hence the 112' C. The color does not revert on cooling. This pigment minimum temperature a t which a change of color will occur is gave the sharpest contrast of all those investigated. materially affected by the type of amine incorporated; the 11. Cobaltous citrate [Co(citrate)z]-from pink to purple a t stability increases as the alkalinity of the amines increases but 110' C. The contrast is good and the line of demarcation sharp. decreases as the molecular size of the amine group increases, This color change does not revert with cooling. 3. Many common cobaltous inorganic salts have temperature12. Cobaltous formate [Co(CH0)2]-from pink t o deep indicating qualities. The relative stability among this class of lavender (or purple) a t 116" C. This change is sharp and the compounds results, as would be expected, from the properties of contrast excellent. There is evidence that the color very slowly the elements or groups in the role of the anion, with the exception reverts upon cooling. However, the rate a t which the purple of iodides which, because of their peculiar properties, may vary reverts to pink is too slow to estimate the amount of time that from their predicted qualities. would be required for the process to become complete. 4. Certain groups such as thiocyanates, thiosulfates, phosphates, and arsenates have shown consistently superior qualities when incorporated as one constituent in both the simple salts In going beyond the temperature range already discussed, the and the coordination compounds. It appears that complexes following compounds were found t o be most promising among containing a suitable metal, an amine, and one of the above a large number investigated. Most of these compounds were groups or a similar group offer the greatest possibilities in the prepared in the laboratory by standard, accepted methods, formulation of temperature indicating pigmentq.
2320
INDUSTRIAL AND ENGINEERING CHEMISTRY
TABLE 11. PIGMENTS FOR TEMPER? PURE RAXGE 5 0 " TO 116" C. Temp., C. 50
Cobaltous pyridine arsenate Nickelous hexamethylenetetraminc bromide 82U Cobaltous hexamethylenetetramine thiocyanate 7-1. Cobaltous acetate 82 Cobaltous pyridine thiocyanate 93 Cobaltous silicofluoride 99 Cobaltous citrate Ilk Cobaltous formate 116 a This change is not permanent; readin:: i n u i t be made shortly after ternpeiature is lowered.
TARLE111. PIGXENTS FOR TEBIPERA~URE RASGE 119" 270" C .
TO
Temp.,
c.
Chromium ethylenediainine crichloride Chromium ethylenediamine thiocyanate Ammonium vanadate Ammonium vanadate Copper pyridine thiocyanate Chromium ethylenediamine thioryanate Chromium ethylenediamine trichloride
119 121 132 164
245 252 270
From these experiments it appears that the compounds shown
in Table 11,properly incorporated into a working formulation, will provide a series of temperature-indicating coatings covering the range from 50" t o 116" C. fairly completely. I n the higher range perhaps the gaps are somewhat wider; however, additional investigation should provide materials quite sensitive in these areas.
Vol. 45, No. 10
Similarly Table I11 lists compounds providing adequate color differentials between 119" and 270" C. I n this case, however, it should be noted that in most instances two definite color changes occur in the same compounds but each change is separate and distinct. A major gap exists between 164" and 245" C. for which a good number of compounds surely exist. Subsequent studies are designed t o extend this range and make it more complete. In the application of these materials it is suggested that standard controls be prepared for correlating results of service application. Photographic standards used for illustrative purposes cannot be considered reliable for reference because of differences of color photography reproducibility. The differences existing in the color picture, however, are reliable comparatively and accuiateli iepieserit degree8 of rliffermce that map be expected. LITERAL'URE CITED (1) C a r t e r , A . J., Chrysler Corp., Rept. 5503-1-01 (Ntri~ch2 3 , 3942).
(2) Guthman, K., Stahl. u. Eisen, 70, 116-18 (1960). (3) Zbid., 62, 477-482 (1942). (4) I G. Farbenindustrie, French Patent 822,308 (Dee. 28, 1937). ( 5 ) I. C . Farbenindustrie, British Patent 478,140 (Jan. 10, 1938). ( G ) Mayer, H. T., Farben.-Chem., 8, 230-7 (1937). (7) Meyer, Walter, mien. pharm. Wochschr., 74, 96-7 (1941). ( 8 ) Perez, H. G., Chem. Zenty., 11, 3481 (1936). (9) Tyte, L. C., Proc. I n s t . Mech. Engrs. ( L o n d o n ) , 152, 226-31, 240-1 (1945). (10) Williams, G. A,, Electronic Eng., 18, 208 (1946). RECEIVED for review blarch 6, 1953. ACCEPTED June 17, 1953. Preeented before t h e Division of Paint, Plastics, and Printing I n k Chemistry at the 123rd Meeting of t h e AMERICAN CEEXICALSOCIETY,LOS Angrlrs, Calif.
Preparation of yeable Fiber-Forming Compositions REACTION OF ACRY LONITRILE-VINYL CHLOROACETATE COPOLYMERS WITH AMINES GEORGE E. HAM AND PAUL W-. GANX The Chemstrand Corp., Decatur, Ala.
HE use of polyacrylonitrile in the preparation of textile T f i bers has received wide attention since the original work of Rein (4)in Germany. A major deterrent to broad textile application of polyacrylonitrile, however, has been its poor affinity to dyes of all general classes. Because the excellent dgeabilitL- of NOOI with acid dyes is generally attributed t o the presence of basicr amino groups in the polymer, efforts toward improving the dyrability of polyacrylonitrile, particularly with acid dyes, were directed along the lines of introducing suitable basic groups into the polymer. T o accomplish this end copolymers of acrylonitrile and alkenyl chloroacetates were prepared by a suspension technique in the presence of potassium persulfate as catalyst and were allowed to react with amines in solution or on the fiber surface to pioduce basic groups along the polymer chain. Copolymers of acrylonitrile with 2 to 10% vinylpyridine are reported to possess improved dyeability ( 1 ). For the initial experiments acrylonitrile-vinyl chloroacetate copolymers were utilized. Vinyl chloroacetate was prepared by vinylation of chloroacetic acid with acetylene in the presence of mercuric acetate (6). For the ropolpmerization of acrylonitrile
and vinyl chloroacetate rapid rates of polymerization wei e observed at greater than 80% acrylonitrile, using 0.5 to 1.0% potLtssium persulfate as catalyst and 0.1 to 0 . 5 % Acto 450 as suspending agent a t 75" to 80" C. and a t 3 to 6/1 water-monomer ratio (see Table I). Appreciable loss of vinyl chloroacetate (10 t o 50%) was obtained, due to hydrolysis to acetaldehyde and rhloi oacetic acid under the conditions of copolymerization. The loss of vinyl chloroacetate was found t o rise with increasing percentages of that monomer in the charge and with increasing reaction times. The hydrolysis of vinyl chloroacetate was also accompanied bs a marked decrease in molecular weight of the copolymer as measured by deciease in specific viscosity, presumably due to the action of acetaldehyde as a regulator. Acrylonitrile copolymers r o ~ i taining 2 to 15% vinyl chloroacetate were readily spun from solution in N,N-dimethylformamide to yield lustrous, colorless fibers of good heat resistance and tenacity. For optimum reaction with amines the acrylonitrile-vinyl chloroacetate copolymer was treated in the dimethylformamide solution with the stoichiometric quantity of amine (preferably tertiary) for replacement of active chloyine in the copolymer.
