INDUSTRIAL A N D ENGINEERING CHEMISTRY PUBLISHED BY THE A M E R I C A N C H E M I C A L S O C I E T Y WALTER J . M U R P H Y , EDITOR
Systematic Procedure for identification of Synthetic Resins and Plastics T.
P. GLADSTONE SHAW
Research Laboratories, The Shawinigan Chemicals, Limited, Shawinigan Falls, Quebec, Canada
tion. Where the same resin is listed in different places in the tables it is because of similarity in properties of related resins which could not be distinguished without use of the trade name, or a few borderline cases which might fall in both places.
The procedure given will identify most resins of commercial importance at the present time. Once the resin has been isolated in as pure a condition as possible it Is necessary to determine to which of eight groups it belongs, then to proceed systematically to its tentative identification. Confirmatory testa are applied to confirm or disprove this. In the latter event, or if short cuts are possible because of the history of the resin, use i s made of a classification of the properties for the various general types of resins.
PREPARATION OF SAMPLE
I n most fields there are published methods (2, 8, I 4 , f6) covering the separation of vehicles, pigments, or plasticizPrs from the resinous constituents that may be encountered. It is beyond the scope of this paper to do more than briefly indicate the methods employed. REMOVALOF VEHICLES AND PLASTICIZER. In handling a solution, addition of a nonsolvent such as ligroin or water to precipitate the resins is useful. The plasticizer will usually be left
EVERY
chemist employing resinous substances is confronted a t some time with the task of identifying a resin. No detailed procedure has so far appeared which would enable a systematic attack on this problem to be made, although a number of methods suitable for a few common resins are known ( I , IO, 13). The method given in this paper has proved very serviceable in these laboratories for the past two years. This method of analysis depends upon using a single resin for the group and systematic procedures. The general order of procedure to be followed on an unknown sample is:
Table I.
Separation of Groups
(Sample previously separated from solvents,. plssticisers, fillers, pigments. dyes, and other resins) Halogens Strongly positive: Test according to Group A. Negative: Test for nitrogen and sulfur. Nitrogen and sulfur Nitrogen hsitive sulfur negative or very weakly positive: Teat according to Broup B. Nitrogen and sulfur positive: Test according to Group C. Nitrogen ne ative sulfur positive: Teat socording t o Grou D. Nitrogen an% sulfhr negative: Teat for saponification nun8er. Sa onification No. Ever 325: Test according to Group E. 120 to 325: Teat according to Grou F. Leas than 120: Teat for acetyl numger. Acetyl No. Over 40: Test according to Grou 0 Less than 40: Test according t o &o;p H.
1. Se aration of the resin or resins from the solvents, plasticizers, illers pigments, and dyes 2. Separat!on of mixtures into individual resins 3. Classification of the separated resin according to the group tests 4. Identification by following the scheme for the group &to which the resin falls, so as to arrive a t the probable identity of the resin 5. Confirmation by specific tests
Cases will occur where the confirmatory tests do not yield a clear-cut identification. This may be due to imperfect separation of a mixture or the presence of a resin which is not covered in this paper. Table II. Separation of Group A Some general reactions (Halogens preseni) are given below which A. Test solubility in ligroin Insoluble: Teat solubility in hot acetone Soluble: Chlorinated will help to identify the diphenyls. Confirm Soluble: Polyvinyl Insoluble: Teat solubility in ethyl acetate type of resin in such by Test VI. Melt Soluble: Chlorin- Insoluble: Teat solubility in ethylene dichloride with very little de~~~~~~;~~~~ cases. Insoluble: Teat composition. High dium $$~ji Soluble: Polyvinyl chloride or low refractive index aolubility in pyriThe scheme will func111 acetate polyvinyl type. Confirm I1 by Test d m chloride acetate tion with the particular c o p o l y m e re.. r e s i n s used a n d w i t h Confirm by Teat I1 a l l i e d r e s i n s ; but i t will n o t d i s t i n g u i s h B. Solubility in pyridine between different degrees Soluble: Test solubility in tetrachloroethane of p o l y m e r i z a t i o n of Insoluble: Cashew Soluble,: Polyvinyl po;yl$zr& f, chloride-acrylate cot h e same monomer. m by 'rest turn black. Polypolymer. Hard VI vinylidene ohloE'"l"ype % '%?e II.and V t Soft It has not been possireain. Low refracride reains. Conin dioxane, other sticky black resin tive index ble t o cover all t h e firm by'Test I1 goye;y;lpi r e s i n s for e a c h t y p e ; 11. Sulfur m u ally preaent therefore, it is necessary to confirm the identifica-
-
541
s42
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Vol. 16, No. 9
in solution. If test-tube experiments show this method is not feasible, the solution may be poured into boiling water or dried by evaporation. Both the latter methods leave the pigments and plasticizers in the resins and they will require further treatment. Oily vehicles may usually be removed by precipitation of the resin by a nonsolvent. PIGMENTS AND FILLERS. Finely divided pigments sometimes offer considerable difficulty. If the pigment is held by Alundum or paper thimbles a Soxhlet extraction of the vehicle-free resins by a solvent will do. At times repeated filtration in the presence of a filter aid such as Filter-Cel on a suction or pressure filter, using a very dilute solution in a low-viscosity solvent, is required. Centrifuging will serve in some cases. DYES. Dyes are even worse to handle but precipitation by a nonsolvent, a procedure which must be repeated several times for removal of vehicles and plasticizers, usually leaves most of the dye in solution. Preliminary tests often indicate a solvent for the dye which has sufficient swelling action on the resin for a Soxhlet extraction of the dye to be made. MIXED RESINS
Where a mixture of resins is suspected, these must be separated into as pure fractions as possible by suitable extraction or precipitation procedures designed to meet the particular case in hand. Fractions so separated, dried, and free from solvent are treated independently by the methods given below. METHODS FOR SEPARATION OF GROUPS
The following tests are applied in the order given (Table I) :
5 m
-
I
HALOGENS.Beilstein's copper wire test is convenient (9, 11, 18). All substances in Group A give a strong test. A faint test may be ignored as due to volatile impurities or salts. It is necessary to make sure that some of,the resin actually enters the flame with the wire. Halogens may also be detected in a portion ot the filtrate from the sodium fuslon by acidifying and boiling with nitric acid, thep adding silver nitrate.NITROGEN.The usual sodium fusion (9, fl, 18) with the development of Prusman blue infhe presence of ferric salts is used. SULFUR.A drop of the filtrate.from the sodium fusion apphed to a silver coin qmckly develops a dark stain in the presence of sulfur. ACID NUMBER. While not required for group separation, this figure is conveniently obtained at this time and is useful as a confirmatory figure later. Accurately weigh about 1gram of resin and place it in 100 cc. of neutral dioxane, alcohol, or other suitable solvent. Then warm gently under an air condenser for about 1 hour. Titrate the free acid .with aqueous 0.1 N sodium hydroxide, using phenolphthalein indicator. Acidnumber = 56.1 x normality of NaOH X cc. of NaOH uaed weight of sample SAPONIFICATION NTJMBEB. To the neutral solution above, in a soft-glm i h k , add 25 cc.
ANALYTICAL EDITION
September, 1944
Table Apply Test IV Blue color: Nitrocellulose or nitrocellulose acetate. Distinguish by rate of burning; acetate ma be identified by metxod of Sinionds and Ellis ( 1 6 ) .
V.
Table Test NO.
I
I1 I11
Property Sought Solubility 95% ethanol Acetone Ether Ethyl acetate Dioxane Pyridine Acetio acid Carbon tetrachloride Tetrachloroethane Benaene Hot water Liebermann-Storch Carbonate fusion Odor
VI
Char Fume Nitrates Odor on ignition
XI
Char Fume Distillate Formaldehyde
IV
XI1
IV.
Separation of Group
(Halonens absent. nitronen Dresent. No blue color: Apply Test XI Negative: Apply Test I11 Odor of NHI and burning hair. Odor like hot aniline, Polyamide resin. Confirm butadiene-acrylo niby Test VI. Note Glue trile copolymer. gelatin or alb&nenord; Confirm by action of might 6ppear here. Physiacetone cal form, positive biuret reaction, solubility in hot water can be expected to indicate such substances.
Nitrocellulose
B
sulfur absent) Positive: Violet color. Apply Test XI1 Negative: Test solubility in pyridine Soluble: MelamineInsoluble: Urea-forf o r m a 1d e h y d e maldehyde resin. resin. Confirmby Confirm b Teats 111 and V I Tests 111 and VI
UreaMelamineFormaldehyde Formaldehyde Resin Resin
Polyamide Resin
NO: evolved
Neg.
Neg.
Neg.
NHa
Formaldehyde
NH: burnin hair
SI. Blue
......... ......... .........
......... Red
Xanthoproteic Refractive index 20° C. specific gravity
c.
.... 1.60 1.4
POS. Nil Nil Neg. Neg. burn- Formaldehyde NH: ing hair Pos. Poa. 81. white v.91. Nil Nil Purple Strong red violet Neg. Neg. 1.66 1.66
+
POS.
$08.
+
SI. Neg. NH:
1.16
1.16
Pos. SI. SI. Neg.
Nsg.
Neg.
Neg.
+
Like hot aniline
Burnin hair and H !Is
NHI burnin hair $os. 91.
Neg. Burning hair PW.
Nil
POE.
Cons. white Neg. Like hot aniline
v.91. Neg. Burning hair
PN.
Pos.
Pale violet Pos.
..........
Weaklypos.
1.64 1.1
........
1.62 0.96-1.01
.......
Heav yel. Sz:
1.3b
VI. Separation of Group C
TESTI. SOLUBILITY. Place about 1 gram of sample in a test tube with 10 cc. of solvent, shake a t room temperature several
Odor like hot aniline. See butadieneacrylonitrile copolymer in Grou? B
hours, then note carefully whether the resin is soluble, partly soluble, or insoluble. or whether there is anv color
in the solvent or resin. TEST 11. LIEBERMANN-STORCH REACTION.Place a small fragment of resin on a spot plate and cover with a few drops of acetic anhydride. Now add 1 drop of concentrated sulfuric acid, so that it enters the liquid. Note the color reactions in the liquid and on the resin surface. Observe over a period of half an hour. List the colors in the order of their formation. TEST111. ODORON CARBONATE FUSION. This test suppresaes the acid constituents in the volatile decomposition products and allows some odors to be more readily recognized. Fuse a piece of resin with 1.25 cm. (0.5 inch) of anhydrous sodium or Dotassium carbonate in a test tube. Note odors. fumes, and iendency to char. TESTIV. NITRATE.Dissolve a few crystals of diphenylamine in about 0.5 cc. of 90% sul-
cc. of NaOH sample) X 56.1 X normality of NaOH weight of sample
TESTS USED IN XHEMATIC PROCEDURE AND FOR CONFIRMATION
Heavy Nil Neg.
.......
(Halogens absent, nitrogen and sulfur present) Teat solubility in hot water Soluble: Gelatin. Insoluble: Apply Teat 111 Confirmb 111 and xf Odor of burning Odor of formaldehyde. hair. CaneinSulfonamide resins. formaldehyde Resins vary from visresin. Confirm oous fluid tolow-meltby Tests VI, ing aolids. Confirm XI, and XI1 by Acid No., Saponification No., and Test XI
AEETYLNUMBER.Weigh about 2 grams of the sample accurately and place it in a Pyrex Erlenmeyer flask, add 20 cc. of pyridine-anhydride reagent, and place on a steam bath under an air condenser. Treat a blank on the reagents similarly. When all is in solution or after several hours if the resin only swells, add 25 cc. of neutral ethylene dichloride or benzene, stopper the flask, and shake vigorously. The resin should be dissolved or well broken up by this treatment. Add 100 to 150 ,cc. of distilled water and titrate with 0.5 N sodium hydroxide, using about twice the usual amount of phenolphthalein indicator. The titration requires vigorous shaking to remove the acid from the solvent layer and the red color should be permanent for a t least one minUte. REAGENT.880 cc. of pyridine (Barrett’s 2A grade), 120 cc. of 95% or better acetic anhydride.
-
Gelatin Glue Coagulated Protein
ButadieneAcrylonitrile Copolymer
Neg.
Saponification number = 56.1 X normality of NaOH X cc. of NaOH used by sample weight of sample
Acetyl number = (cc. of NaOH blank
CaseinFormaldehyde Resin
Heavy ye1. Cons. Neg.
Table
of aqueous 0.5 N sodium hydroxide and warm under reflux until the resin is all in solution but not less than 1 hour. If the resin does not dissolve, allow it to reflux overnight. Titrate excess sodium hydroxide with 0.5 N hydrochloric acid, using phenolphthalein or other indicator. For very dark solutions “Universal indicator” has proved useful. Where the resin is undissolved, vigorous shaking during titration is required to neutralize alkali absorbed by the swollen resin.
Positive : C a s e i n-formaldehyde resin. Confirm by weak sulfur test and Test VI
Resins in Group B
Burning paper
Pos.
200
Properties t$
543
~
~
~
~
~
,
resin on a spot plate. An immediate intense blue color indicates nitrocellulose or esters such as cellulose nitroacetate. Even a few per cent of nitrocellulose in another resin will yield this test, but the color will develop more slowly.
8
,
n
~
INDUSTRIAL AND ENGINEERING CHEMISTRY
544
Table Test No.
I
I1
I11
VI
XI
Property Sought Solubility 96% ethanol Acetone Ether Ethyl acetate Dioxane Pyridine Acetic acid Carbon tetrachloride Tetrachloroethane Ben li en e 10% NaOH Hot water Liebermann-Storch Carbonate fusion Odor
c 200 c.
Sulfonamide Resins* M.H.P.
K
Gelatin, Glue, 4lbumenoids
Casein-Formaldc hyde Resin
8 8
I I
See under Group
8
S S S 6 S
P.8
81.8.0. P.S.G.
I
I I
I IO I
IO 8 8
I
I
I
P.S
Neg.
Neg.
P.8
I
I
Neg.
Neg.
Formaldehyde
Formaldehyde 4- aromatio POS.
Formaldehyde
81. Formaldehyde i- aromstio
POS.
POS.
Formaldehyde matic PW.
+
aro-
Burning hair
+ NHI
PW.
SI.
V.61. Burning.hair
Pos. V.81.
POS. Heavy Nil Neg.
SI. SI.
Deep violet
Deep violet
Violet
1.69
1.696
1.66
1.36
1.86
1.31
Momanto designations. M.S.,soft, low melting point nolid.
8
Formaldehyde
SI.
81.
B. Sulfur test weakly positive
I
S S S
8 S
SI.
Char Fume Distillate Formaldehyde Refractive index 20' C. 20' Specific gravity
VII. Properties of Resins in Group C
M.S.
POa.
Char Fume Odor on ignition
Vol. 16, No. 9
SI.
M.H.P.,solid, softening about
............... ...............
6 2 O C.
K,viscous fluid.
TESTV. CARBOXYLIC ESTERS(6). Place a small piece of resin in a clean test tube and add 1 cc. of 6% alcoholic (waterwhite) sodium or potassium hydroxide, then 1 drop of a saturated alcoholic solution of hydroxylamine hydrochloride. Shake and let stand 5 minutes. Heat for about 30 seconds while boiling, add 1 drop of 1% aqueous ferric chloride solution, and add a t VI olifini. Confirmby ware of compounded butacarefully just sufficient .lo% aqueous hydrochlonc acid to disdiencstyrene oopolymer. weak sulfur teat, solve the ferric hydroxide precipitate; then cautiously add a Test V I and soluOdor of Teat VI not atrong few drops in excess. A strong violet color indicates carboxylic bilityinietrachlorowith this resin ethane and benrene acid esters. The color may be so strong - that dilution with water is necessary in Order to note it' Some crude dark cumarone resins and possibly othem will h o w strong Too much hydrochloric acid will destroy the color and is to be twt for aulfur. If solubillties ahow s u b t a n c e definitely foreign to this group, ignore aulfur test and proceed to test for other groups. avoided, but in negative tests a sufficient excess should be added (1 cc.) dro by drop to remove all doubt of the possiglity that it is insufficient. Table IX. Properties of Resins in Group D T E ~ VI. T ODORON IGNITION. Heat a piece of resin strongly in a test tube, and Organio Polysul6de Vulcanired with note odor, fumes, charring, and presence Test Property Sought Rubber Rubber Diolefins of distillate. No. TEST VII. TEST FOR PHTHALATJBB. ,.+. I Solubility 96% ethanol I I I Heat about 1 gram of resin with about I I I Acetone 2 to 3 grams of pure phenol plus 5 drops I I I Ether I I I of concentrated sulfuric acid until the Ethyl acetate I I Dioxane S melt turns orange or brown. Cool, dilute I I Pyridine 8 with water, and render alkaline with 10% I I Acetio acid I I I Carbon tetrachloride S aqueoussodium hydroxide. Characteristic 8 I Tetraohloroethane 8 red color of phenolphthalein indicatea the S Benrene I I presence of phthalates. Pule red violet to brown I1 LiebermnnnPtorch This test is preferred to the fluorescein Neg. to dark red brown Nag. test for phthalates and is less subjeot to Mercaptan + pungent Burnin rubber 81. aromatic VI Odor on ignition Pol. Ion. 81. error due to inexperience. Char Fume Heavy yel. Hea~~yel. COM. white TESTVIII. TESTFOR PHENOLIC RESMB. 81. Distillate COM. This is the reverse of the test for phthalatea. Refractive index 20' C. ............ 1.62 1.62 Heat about 1 gram of resin with about 200 c. Specific gravity 1.34 1.1-1.18 0.92 1 gram of phthalic anhydride and 3 drops Table
VIII. Separation of Group P
(Halogens and nitrogen absent, sulfur present)
Q
%$$&
Apply Test I1 Renin slowly tumn green
t3a onification Nos.
-
Table X.
Saponification Nos. 600-700, & ~ + ~ ~ , p o l Y v i n Y l polyvinyl -ten. Apply aloohol acetate. with high polyvinyl a c e t a t e . Red color or Acetyl No. high polyvinyi Negative pale violet acetate. or orange, Confirm vinylester by &a?copolymern aoteristic odor. Test VI
-
Separation of Group
E
(Halogem, nitrogen, and BUUWabient. Saponification Nos. over 326) Resin slowly turns ilightly brown, color of liquid Apply Test V changes to deep Red aolet color, Negative, orange, polybasic cellulose methyl polyaeryacid from rosin. confirm late, confirm Confirm by Tests by Testa V I and Xr. Insoluble in ben-
by Test V .! Soluble m bennene
V I and XI. S d u ~ ~ ~ SO, g ~ v pb r G a n t red which d l s a p adding
pegHon
Negative. Apply Test X I Strong red, celPale yellow or ltate. u l o s e Conacencet(1ulo.b e ative firm by Testa sqeto proxIII and ~ ~ d
rate c:;i% k"; Or
$ ~ ~ Test VI a n d solubility
$
ANALYTICAL EDITION
September, 1944
Table
545
XI. Properties of Resins of Group E
Polyvinyl Resins
p vlnyl acetate High acetate
Cellulose Esters Cellulose acetopropionate
~
Test No.
I
I1
Property Sought Solubility 9570 ethanol Acetone Ether Ethyl acetate Dioxane Pyridine Acetic acid Carbon tetrachloride Tetrachloroethane Benzene Liebermann-Storch
V
Carboxylic eaters
VI
Odor on ignition Char Fume
XI XI11
Polyvinyl acetate
and fumarates or maleates
Resin slowly turns green
Resin slowly turns green
Resin slowly turns green
Ne or resin sfghtly brown
Neg.
Strong red violet Characteristic ungent
Strong red violet Ethereal pungent
Red-violet
Strong red violet Burning paper
Strong red violet Burning
+
POS.
PO& Heavy
POa.
SI.
Cons.
V.81. Red
91. Neg. or red to orange Blue to black
V.81. Neg. to V. pale red Purple
Nil Red
SI.
Red orange
4.8 400-600
4 325-640 1.47-1.51 1.2-1.26
6 660 1.48 1.27
4.6
800
.....
1.47 1.19
.....
Table XII. Separation of Group Insoluble: Test solubility in acetone Insoluble: Do Test VI Odor: Oily and Odor: Character-
FiyT$:J:
111
V VI
VI1 IX XI XI1 XI11 XIV
medium acetate ty e. Confirm:So&e In water. Testa X I and XI11
Property Sought Solubility 95% ethanol Acetone Ether Ethyl acetate Dioxane Pyridine Acetic acid Carbon tetrachloride Tetrachloroethane Benzene Liebermann-Storch Carbonate fusion Odor
gaper
S S S S S 8 S
v.51.
Pos. Heavy white Much Neg.
Complete Orange
Neg.
Neg.
Red orange
Neg.
2 500 1.47 1.29
3 500 1.49 1.20
OS.
Pale Yel.
3 376 1.49 1.2
Nil
29 354
...
1.16
F
Char Fume Distillate Phthalates Phenols Formaldehyde Xanthoproteic reaction Acetates Aldehydes Acid No. Saponification No. Refractive index 20° C.
c.
Soluble: Apply Test VI1 Negative: Butyl Positive: Oilhenol formaldemodified al[yd?&tac~fi~~ and xrd VII, and XI1
gd'~zfi$
4,
E;I~~.J,
;:3;11
21,
Polyvinyl Acetab, 70% Hydrolysis
S
S IG
S S
8 S IG
S
S
Resin orange t o dark brown Pungent AcH
Char Fume Carboxylic esters Odor on ignition
specific gravity 200
IG S IG
Heay white V.81. Neg.
Soluble: Test aolubility in 95% ethanol Partly soluble gel. Do Test VI Soluble: Apply Test VI Odor: Formalde- Odor: Acrolein Odor: Butalde- Odor: Characterhyde regular d~ hyde, polyistic pungent, Confirm n n y l butyls1 polyvin 1 aceor coacetal. tal of. row hyest VI1 kyd. Confirm by Test VI1 Confirm b drolysis. ConTeataIII,X{ firm b Testa and XIV I & and
Table
I1
Rosin Pol baaic &id
(Halogens, nitrogen, and sulfur absent. Saponification Nos. 120 t o 325)
Teat solubility in ether
Test No. I
Polymethyl Acrylate
IG P.S.G. 8 IC Neg. Resin slowly Dark orange turns light brown Strong red Neg. Neg. violet Burning Acrylate Pins
E?
Heavy yel.
Pur le to hack
Acid No. Saponification No. Refractive index 20' C. 200 c. Specific gravity 7 20 c.
Pungent
Heavy yel.
Distillate Formaldehyde
est8 I1 and
Cellulose acetobutyrate
High acetyl cellulose a'cetate
S S S B IG S
$06.
Acetates
polyvinyl alcohols
XIII. Properties of Resins in Group F Polyvinyl Coacetal BuH-hd,
62 S S
IG
S
8
Polyvinyl Alcohols Mediud Acetate Type
I
I I
I
I I I I
S S IG S IO Resin red t o red brown t o brown
Resin light brown t o red brown
Pungent BuH
Pungent
Pos. P08. Heavy Heavy Red violet Red violet Pungent char- Pungent BuH acteristic Pos. POS. Heavy Heavy Nil Cona.
I I
Alkyds
Butyl Phenol Formaldehyde
Regular
modified
Oil-
Phenol and oil-modified
P.S.G. S S S
P.S.G.
P.S.G.
IO
SI.-P.S.G. 8
8
....
....I
8 IO
I
....I
8
S S
S S
8
S
8
S
S 5-1
.. ..
.. ..
IG Violet to brown t o Usually neg. Brown to rarelybrown dark brown red brown t o muddy green
+
I
.. ..
Red to brown red t o dark brown
..
Balsam formal- Formaldehyde dehyde musty Pos. Pos. POS. Heavy Heavy v.91. .. Red violet Neg. Violet Violet Red violet Pungent chsr- Phenol or cresol Formaldehyde Oily acro- Oily acroacteriatic lein lein PO#. Pos. Nil 91. Pos. V.81. Heavy brown Heavy Complete SI. SI. Cons. Much Nil cons. Nee. or weak pos. Poa. Strong pos. P08. .. Red Neg. Neg. Neg. V.S1. violet Red Nee. Neg. Neg. Pos. Neg. Neg. Neg. Ne$. Violet to blue Neg. Neg. Neg. Neg.
+
..
....
+
+
..
Red Neg. Red to green to blue Red violet
Orange Neg. Slowly green Red violet
Neg.
Red violet
Neg.
Weakly pos.
Neg.
6 255 1.46 1.16
8 140
4 120-325 1.51-1.55 1.28-1.31
2 125 1.66 1.099
20-50 150-260 1.67 1.32
25-50 140-226
10-30 160-250
....
....
.... ....
....
....
546
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 16, No. 9
Table XIV. Separation of Group G (Halogens, nitrogen, and sulfur absent. Saponification Nos. leas than 120. Acetyl N w . over 40) Insoluble:
Teat aolubility in carbon tetrachloride (B)
B. Solubility in carbon tetrachloride Soluble: Teat solubility in ether Insoluble: Teat solubility in ethyl acetate (C) Insoluble: Phenylphepol Soluble: Do Test IX Positive: Teat solubility in 95% ethanol Negative: Do Test XI1 Negative: Ethyl P-ositive: Phenol in- Soluble: Substi- Insoluble: Butyl and XI1 ftuted ormalde~henol henol formaldecelluloae. Confirm dene cumarone. by Tests I1 and VI Confirm by Testa Eyde. Confirm Confirm by by Teats VI and I1 and VI 11, XII, and XIV ---XI1 C. Solubility in ethyl acetate Insoluble: Test solubility in aoetic acid Soluble: Do Teat VI Odor of burning pa er Any other odor: Teat solubility in ether Soluble: Do Teat XI Insoluble: Phenolic ethyl cellulose. $0,: soluble polyvinyl Red, polyvinyl reem Confirm bv Insoluble: Test Violet firm by Tests 'I and O f o r n h Saponibutylal. AceTest; VI, XI, x1is Odor of Teat VI sli ht solubility in m Teat VI orefication No. $20. tyl NO. about and XIV sol. Shows cresol Shows modiied XIV acetic acid (D) Confirm by Teats 2-50. Confirm a c e t a l d e h de. rosin. Confirmby 11, V, and VI by Testa 11, V, Confirm b $est8 Teat 11. Renin M and VI dark red color 11. IX, a n i X I I D. Solubility in ace$ic acid Soluble: Test solubility in benzene Insoluble: Teat aolubility in 95% alcohol Soluble: Test solubility in 95% alcohol Insoluble: Poly- Soluble: Rosin Insoluble: Benzyl Soluble: Do Test X I Insoluble: Polyvinyl vinyl formal. modified alcellulose. Conk d. Confirmby firm by Tests 11, k;ylal.bout Acetyl S a p o n i f i c a t i o n Brown: Polyvin 1 ace- RV"tylal, 100. No. about 100. dsta I1 and V I VI, and XIV 30, No. about 150. Confirm by Tests Confirm by Teats VI, XI, and 11, V, VI, and X I Teate 11, V, VI, and Tg: XIV XIV
~.?;;-~~~Tea~sea$'i
3:.
PO^$$
frfi;pl #,
pi?,
of concentrated sulfuric acid until a rich brown melt develops, cool, dilute with water, and render alkaline with 10% aqueous sodium hydroxide. Characteristic red color of phenolphthalein indicates presence of phenols. I n cases where tarry matter obscures the color, dilute with water and confirm by discharging the color by acid. All phenolics tested, with the exception of an oil-modified one, gave a positive reaction with this test. TESTIX. MILLON'SREAGENT FOR PHENOLIC RESINS. Prepare the reagent by dissolving 10 grams of mercury in 10 grams of fuming nitric acid without heating, then dilute with twice its volume of water, and filter off any precipitate, or allow i t to settle. Heat a small piece of resin with 1 cc. of clear reagent and boil about 2 minutes. A red color indicates phenols. As the test is characteristic of the phenol group it is also given by some proteins. The absence of nitrogen will, however, direct the test to phenolic resins. A few phenolic resins fail to yield a positive test. TESTX. CUMARONE-INDENE RESINS. This is a modified form of Ellis test (8, p. 1261 footnote; 3). With the latter it was found very difficult to decide whether the color was due to bromine or the resin. The modification gives a positive test with the usual cumarone resins but is negative with the low molecular weight polymers. Dissolve 0.1 to 0.5 gSam of resin in 10 cc. of chloroform, add 1 cc. of glacial acetic acid and 1 cc. of 10% bromine solution in chloroform, and let stand overnight. A red color indicates cumarone resins. Do a blank at the same time. Using 1 cc. of the highly colored solution, add about 1 to 2 cc. of 0.1 N sodium thosulfate and shake vigorously. The blank will discharge to a hght yellow color in the chloroform layer. A red color in the chloroform layer is evidence of the presence of high or medium molecular weight cwnsrone.resins. TESTXI. FORMALDEHYDE (6). Mix a small piece of resin and 2 cc. of 72% sulfuric acid (100 cc. of water and 150 cc. of concentrated sulfuric acid) lus a few crystals of chromotropic acid and heat by standing t i e test tube in a beaker of water a t 60" to 70" C. for 10 minutes. Run a blank a t the same time to avoid chance contamination from the laboratory air. A bright violet color indicates formaldehyde. Note the color after standing 1 hour at room temperature. TEST XII. XANTHOPROTEIC REACTION.This test depends upon the presence of a phenyl group and is usually used to identify certain proteins which contain it. It is also shown by some oils and phenolic resins. I t is sometimes useful as a confirmatory reaction. Warm a small piece of resin with concentrated nitric acid for several minutes, cool, and add an excess of ammonium hydroxide.
In the presence of a phenyl group the nitric acid is yellow, changing to an orange on addition of the ammonum hydroxide. TESTXIII. ACETATES(7). Add a 5% aqueous solution of lanthanum nitrate and 1 drop of 0.1 N iodine solution, followed by a drop of concentrated ammonium hydroxide, to a piece of the resin on a spot plate. In the presence of acetates or propionates a brown or blue coloration quickly develops in the resin. This may occur before the ammonium hydroxide is added and indicates addition of iodine to the resin. When in doubt, warm a iece of resin with a few drops of concentrated hydrochloric a c i i i n 1 cc. of water for about 10 minutes and apply the test to about 0.5 cc. of the water, making sure sufficient ammonium hydroxide is added to render it ammoniacal. TESTXIV. ALDEHYDES IN ACETALS (4). Heat a small piece of resin plus 1 cc. of reagent and 0.4 cc. of concentrated sulfuric acid on a steam bath for 2 to 3 minutes, then cool. Add a few drops of pure methanol and a layer of chloroform, then 0.5 cc. of concentrated hydrochloric acid, and shake the tube well. In the presence of aldehydes a red to purple color appears in the chloroform. Reagent: 0.01 gram of azobenzene phenylhydrazine sulfonic acid in 100 cc. of distilled water. CLASSIFICATION ACCORDING TO TYPES AND GENERAL REACTIONS
Where the substance does not appear to give the comfirmatory tests following its systematic separation by the above scheme, or where, because of its history, distinction between only a few substances is required, this classification according to types, with the reactions generally shown by them, will be found useful: Acrylate Resins. Lighkolored resins. nv about 1.49. Specific gravity 1.2. Usually without filler. Soluble in acetone, esters, benzene; insoluble in CCL, 95% ethanol, ether. Test VI, sickly sweet odor of monomer, with practically complete distillation. Alkyd Resins. Usually light color. nSo 1.54-1.59. Specific gravity 1.1-1.4. Test 11, usually brown. Test V, usually positive. Test VI formaldehyde, oily or acrolein odor, considerable distillation. +est VII, usually positive. Usually insoluble in 95% ethanol, ether, CCL. Amino and Protein Resins. Usually light-colored. ny 1.55. Specific gravity 1.1-1.35. All are insoluble in the solvents listed except melamine-formaldehyde, which is soluble in pyridine or acetic acid, and gelatin which is water-soluble.
September, 1944
ANALYTICAL EDITION
sa7
L E
42
f
$
8
cjcjicj
INDUSTRIAL AND ENGINEERING CHEMISTRY
548
Table XVI. Separation of Group
Test 111,N H I with burning hair odor characteristic of'all except melamine-formaldehyde which ves a formaldehyde odor. Test VI, similar t o Test 111. Test positive with urea-formaldehyde melamine-formaldehyde, casein-formaldehyde. Ne ative with polyamide resin and gelatin. Test XII, positive wi& gelatin and casein-formaldehyde resins only. Cellulose Esters. Usually light color. n v 1.47-1.51. Specific gravity 1.2-1.4. Nitrocellulose burns rapidly, other esters burn slowly; former yields Text IV. Test V, positive except for nitrocellulose. Test VI, odor of burning paper. Test XI, negative to red. Saponification .No., 500 to 550. Cellulose Ethers. Usually light color. ngo 1.47. S cific gravity 1.10-1.25. Solubilities vary according to ethoxyycontent, higher ethoxyl bein more soluble. Methylcellulose soluble in hot water and insolu%le in most other solvents. Test VI, odor of burning paper accom anied by benzaldehyde odor in case of benzyl cellulose. Test SIV, usually positive. Chlorinated Diphenyls. Usually light color, vary from thin liquids to hard solids. n v 1.61-1.71. Specific gravlty 1.341.95. Yield stron halogen test. Soluble in all solvents listed in Table 11. Test %I,slight acnd odor, much distillation. Cumarone-Indene Resins. Vary from light- to dark-colored liquid or solid resins. n1,0 1.6-1.66. Specific gravity 1.01-1.15.
&,
Test No.
I1
Property Sought Solubility 96 o/ ethanol Acezone Ether Ethyl acetate Dioxane Pyridine Aketic acid Carbon tetrachloride Tetrachloroethane Benrene Ligroin Ldebermann-Storch
V VI
Carboxylic eatem Odor on ignition
I
X XI XI1 XI11 XIV
Char Fume Dietillate Cumarone resins Formaldehyde Xanthoproteic reaotion Acetatea Aldehyde Acid No. saponification No. Acetyl No. Refractive index 20' C. 200 c. Specific gravity 200.
Pol methyl
Metfkrylate
Terpene Reain
H
Insoluble in 95% ethanol and acetic acid. Usually soluble in ether, acetone, esters, dioxane, or pyridine. Test 11,red color characteristic which may change to brown or violet, rarely to green. Test VI, indenelike odor and almost complete distillation. Test X, positive with higher molecular weight polymers. Hydrogenated cumarone resin insoluble in acetone and Test I1 weak orange; otherwise similar. Phenolic Resins. Vary from light to dark resins, usually solids. ny 1.47-1.7. Specific gravity 1.1-1.27. Mostly soluble in pyndine, acetone, ether, tetrachloroethane, dioxane, and ethyl acetate, but usually insoluble in 95% ethanol. Heat-reacted forms may be insoluble in all solvents. Test 11, may be negative but browns predominate. Test VI, odor of phenol or formaldehyde with considerable distillation. Test IX, frequently positive. Test XII, positive. Test XIV, frequently positive. Resin Products. Straw to highly colored liquids and solids. nLo 1.52-1.61. Specific gravity 1.03-1.22. Soluble in most solvents used in solubility test with the following exceptions: Polybasic acid insoluble in CCL,benzene. Dihydromethyl abietate, partially soluble in pyridine or acetic acid. Red colored modified resin (Vinsol) insoluble in CCL or benzene.
-
Table XVIL
~
Properties of Resins of Group H Polystyrene
Low polymer oil
Cumarone Reaini Hydrogenated cumarone Polyindene indene reain
I S I
I S
8 8 S I S 8 I
S S I S
S S
8
S S
.... Bright red
Neg.
Neg.
Nee.
Scarlet to red violet
Neg. Sickly sweet odor of monomer V.81. SI. white Complete Neg. Neg.
Neg. Like coal gaa
Neg.' Styrene
Nee. Indene
Indene
Nil VSI. Complete Neg. Neg.
Nil Cons. white Complete
Nil Nil Complete Neg. Orange Neg.
Nag.
Neg.
Neg.
.... ....
P08. Heavy yel. Much Pos. Neg. Neg.
4 20 0 1.49 1.19
2 0 0
2
2 0
0 1.59 1.05
0
...
...
...
...
... ...
Vol. 16, No. 9
.... ....
Neg.
....
0
1.60 1.01
....
.... .... 7 0 0
1.6-1.66
1.10
I I S S
S
S I SCG 8 S
I Lightorange Neg. Indene Nil Complete Nil Neg. Neg. Nee. Neg. Red 6 0 0
...
...
High m.p. cumarone
I
S s-I 8 S S
I 8-1
8
P.S-s
....
Red t o purlish red t o grown
....
Indene
SI.
Complete SI. Pos. Neg. Neg.
....
.... 2 0 0
1 .&I. 66
1.10
ANALYTICAL EDITION
September, 1944
Test 11, red to violet color. Test V. If any odor it is pine or balsamlike, resin distills without residue. Saponification number low except for hydrogenated rosins and the polybasic acid. Acid number over 100 only in case of the Vinsol resin. Acetyl number zero except for Vinsol resin. Rubber and Rubber Substitutes. Halogen Containing. Chloro rene is black rubbery resin, characteristic odor insoluble in alfsolvents. Rubber h drochloride and chlorinated rubber light colored. Former insolugle in all except tetrachloroethane; latter soluble in ethyl acetate, dioxane, and pyridine. Cashew nut oil pol mer is sticky black resin soluble in pyridine only. &&diene Copolyners. Black rubbery solids. Butadienestyrene copolymer insoluble in all solvents. Butadiene acrylonitrile copolymer insoluble in all solvents, contains nitrogen. Poly’sobutylenes and Co o l p e r s with Diolefins. Light-colored fluids to rubbery solids. 8opolyrners usually dark colored. Polysul e Rubbers. Contain much sulfur. Specific gravit 1.34. So uble in dioxane, pyridine, tetrachloroethane. Test I[ red violet changing to brown. Test VI, mercaptan odor, considerable distillate. Vulcanized Natural Rubber. Contains sulfur. ng0 1.52. Specific gravity 1.1-1.18. Insoluble in all solvents. Test VI, characteristic odor of burning rubber, no distillate. Sulfonamide Resins. Light colored varying from soft viscous fluid to hard resins. ny 1.56-1.60. Specific gravity 1.31-1.36. Soluble in most solvents shown in Table VI, insoluble in CCL Test XI, strong violet. Terpene Resin. Light-colored solid. Soluble in ether, CClr, tetrachloroethane, benzene, ligroin. Insoluble in 95% etha.no1, acetone, dioxane, ethyl acetate, acetic acid. Test VI, odor like coal gas, distills completely. Vinyl Resins. Halogen-containing. Strong test for halogen. Very light-colored solids. ny 1.53-1.61. Specific gravity 1.21.75. Insoluble in ligroin and benzene. Test 11, blue or green color slowly develops in resin. Polyvinyl Esters. Colorless solids. na2 1.47. Specific gravity 1.19. Polyvinyl acetate soluble in all the solvents except ether and ligroin. Copolymers insoluble hi ether and ligroin but may also be insolu&le in the other solvents. Test 11, resin turns green; this is characteristic. Test V, red violet. Test VI, characteristic odor, very slight distillate containin the acid usually acetic. Test XI, red to negative. Test X h , blue or pur le to black. Saponification No. 400 to 600. Polyvinyl AZco!oGAcetate. Light-colored r e m . na; 1.47-1.55. Specific gravity, 1.2-1.33. Low and medium acetates insoluble in everything except water. High acetates soluble in Test 11, green to brown color. Test V, red violet. pungent acidic odor, no distillate. Test XIII, violet to blue or purple. Acetyl number, low acetate type, 1080 to 1270, Saponification No.: low acetate, 0 to 119; medium acetate, 120 to 325; high acetate, 325 to 540.
TM
549
Polyvinyl Acetals. Light-colored resins. nSo 1.46-1.50. avit 1.11-1.23. All insoluble in ether, CCL, ligrom. %%b:% in &oxme, pyridine, tetrachloroethane, or acetic acid. Test 11, usually brown. Test V, red violet. Test VI, chsracteristic odor of aldehyde indicates type; little distillate. Test XI, violet with formals, red or brown with acetals, red with butyrals. Test XIV, usually red violet, formals may be negative. Polystyrene. Light-colored resin. ny 1.59. Specific gravity 1.05. Soluble in dioxane, p dine, CCL, tetrachloroethane, benzene. Insoluble in 95% e t g o l , acetone, ether, acetic acid, ligroin. Test VI, odor of styrene, complete distillation. Saponification No. zero. ACKNOWLEDGMENTS
Thanks are due to K. G. Blaikie and A. H. Heatley for their helpful criticism and to T. Bruce and 0. Heroux who cooperated in checking the analytical scheme. LlTERATURE CITED
(1) Bandel, G., Angew. Chem., 51, 570 (1938). (2) Ellis, Carletpn, “Chemistry of Synthetic Resins”, Vol. 11, p . 1258.New York, Reinhold Publishing Corp., 1935. (3) Ellis, Carleton, “Synthetic Resins and Their Plastics”, p. 53, New York, Chemical Catalog Co., 1923. (4) Feigl, F.,“Spot Tests”, p. 283, New York, Nordemann Publishing Co., 1939. (5) Ibid., p. 295. ( 6 ) Ibid., p. 328. (7) Ibid., p. 330. (8) G a r d n e r , H.A.,“Physical and Chemical Examination of Paints., Varnishes, Lacquers, and Colors”, 6th ed.,. pp. 898, 1034, Washington, D.C.. Institute of Paint and Varnish Research, 1933. (9) K a m m Oliver, “Qualitative Organic Analysis”, p. 133, New York, J o h n Wiley & Sons, 1932. (10) Nechamkin, H., IND. E N G . C H E M . ,ANAL.ED., 15,40 (1943). and Kipping, S., “Organic C h e m i s t r y ” , pp. 16, (11) Perkin, W.H., 17,Philadelphia, J. B.Lippincott Co., 1911. (12) Shriner, R . L., and Fuson, R. C., “Systematic Identification of Organic Compounds”, p. 112,New York, J o h n Wiley & Sons, 1940. (13) Simonds, H . R.,and Ellis, Carleton, “Handbook of Plastics”, New York, D. Van Nostrand Co.. 1943. T h i s book, which appeared after this paper was submitted, contains a useful system of analysis. (14)Ibid., p. 738. (15) Ibid., p. 779. (16) Stafford, R.W., I N D .Fso. CHEM..ANAL.ED., 14,694 (1942).
Table XVII. Properties of Resins of Group H (Continued) Cumarone Resins (Cont’d) Medium m.p. cumarone
Soft cumarone
Ethyl abietate
Rosin Products Dihydromethyl abietate
8
S
S 8 S
8 S S S
S
....
....
PS-S .Orange to brick red
S
....
Indene Nil V.61. Comdete POS.to neg. Neg.
....
.... ....
0 0 0
1,8-1.08 1.10
S S
8
P.8 P.8 8 5 S
S
S
Hydrogenated rosin
Butadiene.copolymer styrene
S S S
IG
S 8
IG IG
S
S
S
....
..,.
....
Red t o purplish red t o green or brown
Ked t o violet to blue t o black
Red to violet to green to blue
....
Neg. Pine Nil Nil Complete
Red to violet to purple to green Neg. Pine Nil Nil Complete
Red
Neg.
Neg.
Indeiie Nil V.SI. Complete Pos. to neg. Neg. t o weak violet
....
....
Pos.
....
....
0 0 0 1.6-1.86 1.10
26 0 1.53
....
4
1.03
....
Neg. Faint balsam Nil Nil Complete
....
POS.
....
Neg.
Neg.
.... 8
26 0 1.52 1.03
....
186
Neg.
Neg.
I
I
IG
IQ
IG IG Pale blue to grBy green Slighi’ityrene
Neg. V.SL aromatic
POS,
SI.
Cons. white Considerable
Cons. white 81. Neg. Nee.
....
....
....
.... 0
8
0 0
1.08
0.94
.1.63 ..
Polyisobutylene
I I
S S S S
Synthetic Rubbers Isobutylene copolymer with diolefins
....
.... ....
Like coal gas Nil v.91. Nil
.....
Pale violet
.....
..... .....
