Some of the papers eresented in the Symposium on Analysis of High Polymers, Division of Analytical Chemistry, 139th Meeting, American Chemical Society, St. Lonis, Mo., March 1901.
Resinography of T. G. ROCHOW Cenfral Research Division, Chemical Research Deparfmenf, American Cyanamid Co., Sfamford, Conn.
b
Information about macromolecular integration into a material i s charted on several levels with respect to description, composition, and useful properties. Convenient, more or less distinct levels of organization are: (I) the theoretical molecule and its empirical domain of influence, (11) the habit, of one or more kinds of molecules as a point, edge, surface, or interface, (Ill) each phuse, amorphous or crystalline, of the bulk of molecules, and (IV) the material, a system of one or more phases, as manufactured. On each level there are both qualitative and quantitative aspects. Polymeric examples are described on the different levels of organization. The examples also demonstrate the interrelationships of composition decomposition and property-features embodied in guidecharts. These can serve the purposes of both analyst and synthesist.
-
S
prehistoric times high polymers have been very famiiiar materials, but knowledge of their composition is strictly modern history. mith the present profusion of modified and synINCE
,
thetic polymers the problems of analysis become increasingly complicated. The challenge is being met with a wide variety of analytical techniques on different kinds of samples by different workers. To correlate current knowledge and indicate further information to be obtained, classification is being considered in accord with the three classical categories (88j : description, synthesis, and understood properties. Description in morphological biology, for instance, is divided among organography, histology, and cytology (16). As in all descriptive science, the data are obtained both by direct methods-e.g., macroscopy and microscopy-and by indirect methods-e.g., x-ray diffraction and light scattering. If there are conflicting interpretations, composition and properties are not well understood until the differences are resolved. As in metallography ( 7 ) , the province of resinography must extend into chemical-physical composition and practical properties before the whole material may be fully understood. The principal purpose of this article is to
develop the extension beyond previous discussions (34-39, 47) of resinography. A recent example of resinography is the study of experimental acrylic fibers by Botty, Felton, and Anderson (61, summarized in Figure 1. Three samples were taken from successive short segments of the same wet tow. They received various treatments, exhibited different characteristics, and demonstrated varying properties. Resinography (34) like metallography is a cyclic study. In analysis the cycle involves chemical tests, physical description, and practical properties for the purpose of understanding what happened as the material was made, tested, or used. I n synthesis the procedure is directed toward predicting properties. One approach to understanding high polymers better is to assign the bulk properties directly to the chemical and physical composition (26) and imaginatively sketch the macromolecules to look like spaghetti, either as it is uncooked and arranged in a box or as it is cooked and disarranged on a plate
STRESS- STRAIN CU
rr
w
w z
.
n 0
3
E 0
E..5NGAT13N
%
Figure 1 Acrylic fibers cut successively from same wet tow and given various treatments before drying [Textile Research ); Encyclopedia of Microscopy (3611 ~
Corresponding morphologies and r+~esr-strain properties are depicted
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ANALYTICAL CHEMISTRY
Figure 2. hibit
Polyacrylonitrile fiber [ASTM Photographic Exof MicroscoPY (36)1
Electron micrograph of positive silica replica. Right diagonal port depicts small and large particles in ridges of surface. Left diagonal part, void o f deep ridges, is interpreted to b e a window broken through the surface layer of the fiber and exposing a more random organization of particles
Figure 3. Polyacrylamide from droplet of HzO and CHgOH solution containing NH&l electrolyte Dried polymer shadowed with uranium; Center of dried droplet is outride lower left-hand corner lower left, inner sector of droplet; branched and complicated filaments intermediate, zone of thin single fllaments like uncoiled macromoleculaS Upper right, outermost zone) globules about 200 A. in diameter
(44). With the development of the electron microscope (%), however, replicas of fractured (39) and unfractured surfaces of polymers, such as experimental acrylic fibers (Figure 2) depict some fundamental particles which look more like meatballs than spaghetti. While the arrangement and compactness of such particles has been related to bulk properties of the skin, core, and whole fiber (67, there is still the problem of relating all of this to the discrete macromolecule, its fundamental behavior, and its own properties : Level I, The Discrete Macromolecule. Regarding fundamental particulate behavior, attempts were made to observe particles coil and uncoil in the manner of macromolecules in very dilute solution as the quality of solvent is changed from poor to good ( I S ) . I n the conventional electron microscope the sample is exposed to the very high vacuum of the path of the electron-beam, so the specimen cannot be in any solvent which will volatilize in the electron microscope before observation can be made. Therefore, the chosen technique was to dry some tiny droplets of dilute solution (41) on a thin carbon substrate and thereby to vary conditions across the droplet before inserting it into the electron microscope. To increase contrast between particulate boundaries and their background, the specimen was shadowed with uranium in a high vacuum. I n one set of experiments a commerical sample of polyacrylamide, with molecular weight evidently in the millions from data on light scattering, was highly diluted in water (a good solvent) and methanol (a poor solvent) to which had been added a little ammonium chloride (an electrolyte which neutralizes inherent charges and volatil-
izes in high vacuum). Figure 3 is an electron micrograph of a sector of one dried droplet. Near the periphery there are globular shapes such as would be expected of macromolecules on the verge of precipitation. Evaporation, however, favored removal of methanol and consequent concentration of water to such a degree of good solvency that the macromolecules apparently uncoiled. The resultant filaments are delicately pictured in the diagonal middle of Figure 3 as thin short stringers. They are shown in longer sequences, in apparent branches and possible parallel aggregation toward the lower left corner of Figure 3, In the left diagonal direction the concentration of macromolecules was in-
Level I.
Description Macromolecular domain of influence
A further problem is to describe, treat, and determine properties of macromolecules while they are situated in the solid polymer. I n classical work, Moore and Peck (30)solved the problem in polyethylene. They chose samples in which the presence of relatively large particles (500 to over 1000 A. in diameter) had been strongly indicated by low-angle light scattering methods. I n pure cast films, purposely etched and shadowed, they observed round particles about 500 A. in diameter. The particles manifested the property of insolubility in those hot solvents which dissolve smaller molecules. Moore and Peck reasoned that the conditions of preparation favored long-chain branchir.g and consequently round shapes. Employing the Billmeyer postulates, they showed that the intrinsic viscosity was low, relative to the weight average molecular weight. It remained to decompose the particles and prove them to be single molecules because they could not be subdivided without changing description and properties. Using principles such as described by Vassallo (46), Moore and Peck used mild pyrolysis on the branched chains, decreased the weightaverage molecular weight without much change in viscosity, and saw smaller particles. Under specific conditions of polymerization the configuration in and among macromolecules may be varied in kind and degree. The configuration is characterized by methods such as are described by Gailey ( I @ , Luongo ( 9 4 , Critchfield and Johnson (9), and Gibson and Heidner ( I 7). Such information and presumably all characterizations, behaviors, and properties of the macromolecule may be classified as follows:
Discrete Macromolecule
Composition
Properties
Atoms in stoichiometric Chemical reactivity, inherproportion and stereo arent solubility rangement
creasing and so were the chances bf aggrrgation. I n the middle diagonal of Figure 3 the picture is reminiscent of electron micrographs of Hall and Doty (19), who observed and measured the rod-like particles in macromolecularly fractionated samples of pure proteins. I n their case the calculated average molecular weights are in reasonable agreement with the interpretations of data on bulk solutions by methods such as were discussed by Billmeyer ( 4 ) : flow birefringence, viscosity, lightscattering, and sedimentation rate.
By domain of influence is meant the effective realm of one macromolecule as differentiated from that of a contiguous or interlocked molecule. The primary effect is to round out boundaries where there is minor penetration by other molecules. Another influence is on illuminating emanations such as an electron beam, so that even isolated macromolecules manifest a rounding of detail which is beyond the detecting (23) and/or resolving power of the method of description. Relationships among description, composition, and properties are close VOL, 34, NO. 13, DECEMBER 1961
1
Figure 4, Unshadowed SiO, replica of fractured melamine-formaldehyde molded resin Particles, 700-800 A. in diameter, are evidently composed of smaller particles, 150-200 A. in diameter
and classification may be arbitrary. For example, electric polarization (B) is closely connected with descriptive properties. The relationships are shown better, perhaps, as a circle. There is continuity between levels, too. . Khile describing, distinguishing, and understanding a single molecule are fundamentally important, evidence is piling up (8) to support Eirich (10) and his colleagues (39) that the fundamental particle involved in solution (44,fracture (12), or etching niay actually be an aggregate or micelle (12) of theoretical molecules. A recent electron microscopical study of fractured compression-moldings of melamine-formaldehyde polymer confirms earlier observations (40) that the globules of colloidal sizes and origin are convoluted. Khile the visibility is still not as good as desired, the conviction remains that the convolutions are related (SS, 59) to the domains of influrnce of the theoretical molecules.
(3611
For example, in Figure 4, the small particles (whether alone or in larger globules) are classified as the macromolecular spheres of influence (on Level I ) ; the larger particles are better classified as the colloidal type, that is, on Level 11.
Level 11, Macromolecules AssoOne or Two Directions. As illustrated in Figure 5 the fundamental particles of the species may be ciated in
arranged in one direction, along a n edge (of a hole) or in two directions in a surface (interface). I n these situations the macromolecules must be in contact with the same and different kinds of molecules to various extents. h especially interesting situation is the monolayer as illustrated by the films partially covering the three holes
Positive silica replica; no shadawing metal left, rougher side cast against air Right, smoother side cast against smooth solid
ANALYTICAL CHEMISTRY
COPY
Shadowed a t 10' with U Particles shown as envelopes around holes (white) and as monolayers p o r tially covering the holes, formerly bubbles. In matrix, particles tend to b e grouped but not as distinctly as in original polymerized emulsion nor as in pressure molding
Figure 6. Commercial film of a polyester showing difference in texture between the two sides
112
Figure 5. Polyacrylonitrile as thin self-supporting film cast from dilute solution in ethylene carbonate [ASTM Bull. ( I ) ; ASTM Photographic Exhibit (5); Encyclopedia of Micros-
in the middle of Figure 5. If these monolayers are plane associations of the macromolecular spheres of influence, and they seem to be, information obtained from the Langmuir film balance (3, 33) should contribute to the understanding of the peculiar properties of the more complex commercial films, fibers, sponges, latices, gum plastics, adhesives, etc. Even one surface of a film may be different from the other. A decade ago, Eirich and Mark observed that many commercial films slipped against themselves more easily when folded one way than the other. This was shown (If) (Figure 6) to be due to a difference in surface texture ( 2 7 ) . The difference can be related to the manufacturing procedure of casting one face against a smooth solid surface while the other
Fdgure7. Commercial film of nylon showng differences in texture between the two sides [Encyclopedia of Microscopy
(36)1 Positive silica replica; no shadowing metal Left, rougher side cast in air Right, smoother side cast against smooth solid
face was hardening roughly in the air. While some of the slipperiness may be assigned to the nature of the molecule itself, the difference between two faces of the same film is largely the effect of manufacturing conditions (on Level 11). Crystalline habit is practically independent of the crystal system and is related to conditions and properties on Level 11. Figure 7 is another electron micrograph reported by Eirich and Mark (11). X replica of pach side of a nylon foil is pictured. The smoother side is immediately apparent. The rougher side is that way because the radial crystallites were free in the air to grow upward to some extent. The size, shape, and distribution of the grains of radial aggregates are d s o attributes of Crystalline habit. Fracture may occur and be described as intragranular, intergranular (between crystallites), or simply between the most fundamental particles shown. h’ot only are we concerned on Level I1 with texture of surfaces or topography (20) (and not merely with shape of test pieces) but also sometimes n-ith the “memory” of intermediate particles (36) OT granules. The old grain boundary may be revealed by fracturing (39), relief-polishing, or sometimes by annealing as illustrated in Figure 8. Generally, man-made orientation may be classed as a process on Level 11, that is, arrangement of macromolecules in one or two directions by man-applied forces to obtain prescribed shapes and
Figure 8.
properties (18). A summary is given below. Level
II.
Macromolecules Associated in One
Description Habit of particles in point, edge, or surface
Composition Kinds, %molecules contacting same or different kind
Level 111, Each Phase of Macromolecules Associated in Three Directions. On this level the three-dimensional interior of each phase is to be considered. Khile a polymer may possibly be in the vapor state and sometimes in the liquid state, i t more commonly is present as a rubber, glass, or any one of t h e crystalline species or polymorphs (29). Crystallization (on Level 111) is three-dimensional spacing and orientation according to crystallographic systems as a result of inter- or intramolecular forces. Characteristics and properties of crystals are to be differentiated from those of relatively crude and variable order in one or two dimensions as a result of extra-molecular stress (on Level 11). Crystallinity, generally, is estimated and characterized by x-ray diffraction (48) or by differential thermal analysis (21). Kegative information of any kind is not proof of absence. A microscopical search, too, may reveal nothing or it may reveal heterogeneities which indicate the presence and approximate quantities of an unexpected crystalline
Commercial poly(methyl methacrylate)
Reticuiution i s definitely related to habit of size and shape c: molding grain Left, after experimental compression molding Right, after annealing at 1 1 6’ C.
phase. For instance, the molded surface of a sample of polyamide examined
or Two Directions Properties Specific surface; rates of reactions
simply by reflected light with a metallographic microscope indicated the presence of polyhedral particles. The contrast was enhanced by the use of crossed polars. General visibility was improved by slightly polishing the specimen to remove mold marks and matclips and to give the apparent crystsls relief over the softer amorphous resin. The internal presence of such particles was quickly confirmed by cutting and polishing a cross section. While the preparation of thin sections, parallel and perpendicular to a molded face, took longer, it was judged to be worthwhile to provide samples for further microscopical and x-ray examination. Figure 9, taken by transmitted light of a thin section between crossed polars, showed very convincingly the extensive presence of polyhedral anisotropic particles with definite parallel or symmetrical extinction. Yet none of the samples mentioned above gave an indication of crystallinity by usual x-ray methods. Subsequently the amorphous polyamide as preferentially dissolved and centrifuged away. The concentrated particles then gave a sharp x-ray diffraction pattern which was identical nith that of a recrystallized sample. The latter was used to obtain definitive and determinative optical and goniometric properties. Infrared spectra indicated that the crystals were derived from a cis-configuration of the monomer and were probably oligomeric, whereas the amor-
Figure 9. Polyamide in thin section parallel to a molded face shown between crossed polars with transmitted light Crystals are of an oligomer by interpretation of infrared data
VOL. 33,
NO. 13, DECEMBER 1961
1818
Figure 10. styrenes
Crystallizable and
noncrystallizable poly-
Figure 1 1 . Polystyrenes, approximately half ketone-insoluble (isotactic)
Particles mounted in air and specimens are between almost crossed palarr Left, ketone-insoluble sample. M a n y parts of particles are shown bright and practically ail particles manifested sharp extinction every 90' of rotation. Optical data plus sharp melting and repeated recrystallizations a r e criteria of true crystallinity Right, ketone-soluble sample. lsctrcpic (all black) apparently noncrystallizable particles were expected from the origin, treatment, and x-ray characteristics. Sample also contained particles resembling those on left
Incubated so that all crystallizable polymer is practically completely crystallized and is located in middle of drop as melted. Edge of drop is partly shown in lower right. Photomicrograph of sample between almost crossed pclars
phous high polymer was evidently derived by a trans-configuration of the monomei. Thus a difference in characteristics, behavior, and proprrties between two phases on Level 111 (and between particulate and relatively continuous habits on Level 11) is related to the nincromolecular Level I. The over-all properties of the two phases together is to be considered, hornever, on Lcwl IV, An e\aniple of variation among phases in a single high polynier was piovided by adding approximately equal weights of the ketone-soluble and ketone-insoluble fractions obtained by polymerization of styrene in the presence of a typical Ziegler catalyst. The powders before admixture are illustrated in Figure 10. The ketone-insoluble fraction is shown (on the left) to be composed almost entirely of anisotropic grains mhich gave a sharp x-ray diffraction pattern, characteristic of crystallized isotactic polystyrene. The ketone-eoluble fraction is shown (on the right) to contain the expected isotropic granules which are uncrystallized and prpsumably noncrystallizable. Although unexpected, judging from the data on over-all solubility and x-ray diffraction, the anisotropic phase too, was present in the ketone-soluble fraction. The last ($8) of these anisotropic granules to melt on a Kofler hot stage did so a t 228' C. as compared with 230" C. for the last of the ketoneinsoluble fraction. In both samples the refractive index in one position of extinction was very close to 1.610; in the other eutinction-position the index varied as expected of the rhombic (29) Rystem. The values varied in different viems between 1.610 and 1.620. 84
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ANALYTICAL CHEMISTRY
While the proportion of crystallized grains in the ketone-soluble fraction was somewhat less than indicated in the small field shown in Figure 10, the proportion was substantial and was confirmed by repeated melting and recrystallizing. Some of the admixture of equal parts by weight of the two fractions (shown in Figure 10) was melted on the hot microscopical stage (RS) and incubated a t temperatures inducive to crystallization through ten cycles without mixing. The typical appearance is shown in Figure 11. Nost of the crystallizable species has been crystallized and is the phase situated in the middle of the drop. The noncrystallizable macromolecular species has been segregated in the aniorphous phase in the periphery of the drop. The small particles shown black throughout the sample are derived from the catalyst and may be ignored in the entire series, Figures 10 through 13. At the beginning of the seventh cycle of melting and cooling, tEe location of crystallizable and noncrystallizable species was nearly as shon-n in Level 111.
a t which the cracks were healed together, a delicate refractive interface was observed in the amorphous phase. At first the interface was a thin line in the shape of a disk or doughnut, but later (at higher temperatures) the interface widened and darkened into the shapes of islands as shown in Figure 12. Apparently the glassy state represents a phase distinct from the rubbery one. The corresponding specific vohmes are very different as indicated by the spaces between the two phases. The glass transition (SI, 44) was observed within a rnide range of temperatures, presumably because of the composition gradient existing between the isotactic and atactic configurations. At temperatures zbove those of the room and below those a t which the islands, cracks, and strain-anisotropy all disappear, at least some crystals were grown and their locality and habits could be observed as illustrated in Figure 13. Thus, characteristics, behavior, and properties of each phase may be studied in situ by microscopical (7, $8) methods. To be fully understood, each phase should be studied both macroscopically and microscopically as indicated below.
Each Phase of Macromolecules Associated in Three Directions
Description Each phase: liquid rubber, glass, Crystalline
Composition Kinds, yo components in space: rsndom or order
Figure 11 Then the specimen was meited and chilled in air to room temperature. As usuai this was done without stirring and a composition gradient existed between crystallizable (isotatic) and iioncrystallizable (atactic) varieties. During reheating through the annealing temperatures
Properties Bulk properties of
each
phase; absolute solubility
The highest temperature of melting crystals is closest to the melting point of the pure crystalline phase; a small range indicates impurity; a wide range could indicate variation in composition of ~t crystalline solid solution. Level IV, the Whole Material, Including Macromollecules, Surfaces,
Figure 12.
Amorphous polystyrene
Atactic (noncrystallizable) in periphery of drop (edges of which a r e shown on right) to isotoetic (crystallizable) in middle. Melt had been chilled to room temperatures and was heated slowly to extent that some islands of glassy state remain
and Phases.
Jt’hile the synthesist and analyst are busy with molecules, surfaces, and phases, the engineer is making, testing, and consuming materials. He may imagine t h a t he has a simple solid continuum ( 1 4 , but he may actually have a system of phases. Each phase may contribute its own properties in proportion to its average concentration or there may be synergism among various molecules, interfaces, and phases ($0). For example, polystyrene today must have, among other properties, higher impact strength than the polystyrene of yesterday. Analytical chemists may do a tremendous job in determining that a desirable polystyrene type contains a certain per cent of butadiene and an oil of several identified constituents. Yet its high impact strength may not be understood until it is observed that i t is a poly-phase system “polyblend” (44) (gum plastic) (43) as illustrated in Figure 14. The glassy phase may be tangibly separated from the rubbery one and reconstituted only to reveal that the size and shape of the dispersed phase are important, too. Systems containing monomeric or oligomeric molecules such as by-products, pigments, delustrants, or reinforcing agents are also involved in the whole material on Level IV. To summarize Level IV:
Figure 13. Polystyrene varying across field in proportion of isotactic and atactic [Encyclopedia of Microscopy (6611 Light micrograph of unrtirred sample between partially crossed polar9 by transmitted illumination. Sample quenched in air, warmed slowly until glassy (discontinuous) phase was almost entirely transformed to rubbery (continuous) phase, held a t slightly lower temperature for some eolcniei of crystals to farm, quenched again to freeze the three eoexistent phases and l o result in both isotropic (black) and anisotropic (white) cracks
Figure 14. Alloy (gum plastic) high in polystyrene containing particles of synthetic rubber [Encyclopedia of Microscopy
(3611 Polished and etched (benzene in methanol ca. 1:4); bright field reflected illumination
decomposition, and practical properties. Some differences in these respects between a polymer and other plastic materials, such as metals, waxes, and putties, may be understood from the macroniolecular characteristies of polymers. Manipulations of kind and estent
Iv. The Whole Material: phases and Interfaces of Various Molecules Description Composition-Decomposition Useful Properties Material: laminate, latex, Kinds, yo,and distribution Properties as manuiacfoam, fabric of phases; changes tured, tested, or used levei
SUMMARY
Polymeric materials, like all materials, may be analyeed on the bases of descriptive characteristics, composition-
among the configurations and conformations of giant molecules by the molecular engineer (66) explain Some important changes in material properties such as chemical and thermal stability. But
there are also kinds and degrees of properties which depend chiefly upon shape and specific surface such as the flexibility of a fiber or foil, the rigidity of a sphere, and the rapid rate of dissolution of a powder (in contrast with one piece of the same weight). Moreover, the characteristics and properties of a batch of polymer made into a certain shape will vary with conditions resulting in qualitative and quantitative changes in amorphous or crystalline phases. That is, the ultimate properties of the material in use depend not only on the composition and configuration of theoretical macromolecules but also on the mechanical and thermal treatment of surfaces and three-dimensional phases on several levels as revealed by resinography : VBL. 33, NO. 13, DECEMBER 19611
e
1815
\Y. C., “Fusion Methods in Chemical Microscopy,” Interscience, New York, 1957. (29) Miller, H. L., Kielsen, L. E., J . Polynier Sci. 44, 391-5 (1960). (30) Moora, L. D., Peck, V., Ibid., 36, 141-53 (1959). (31) Newman, S.,Cox, W. P., Ibid., 46, 29-49 (1960). (32) Reisner, J. H., RCA Sci. Inst?. 6 , KO. 1, 14-21 (1961). (33) Ries, H. E., Jr., Sci. Bmerican 204, March, 1961, pp. 152-64. (34) Rochow, T. G., Am. SOC. Testing Materials, Spec. Tech. Publ. No. 143, 81-93 (1952). (35) Rochow, T. G., IXD. E N A CHEY., AXAL.En. 11!,629-34 (1938). (36) Rochow, 1. G., Resinography in “Encyclo edia of Microscopy,” ed. by G. L. d a r k , pp. 525-37, Reinhold, New York, 1961. i ) Rochom, T. G., Gilbert, R. L., in (3”Protective and Decorative Coatings,” ed. by J. J. Mattiello, chap. 5, T’ol. 5 Wilcy, S e w York, 1946. (38) Rochow, T. G., Rochow, E. G., Science 111, 271-5 (1950). (39) Rochow, T. G., Home, F. G., ASAL. CHEM.21, 461-6 (1949). (40) Rochow, T. G., Rowe, F. G., electron micrograph exhibited at 9th meeting, Electron Microscope Society of America, Philadelphia, Pa., Sov. 9-10, 1951. (41) Siegel, B. M., Johnson, D. H., Mark, H., J . Polymer Sci. 5, 111-20 (1949). (42) Statton, W. O., Am. SOC. Testing &laterials Spec. Tech. Pub. No. 247, 242-56 (1958). (43) Thompson, M. S.,“Gum Plastics,” p. 1, Reinhold, New York, 1958, (44) Tobolsky, 9. V., “Properties and Structure of Polymers,” pp. 81-2, Wiley, New Yorlr, 1960. (45) Tsvetkov, V. N., Boitsova, N. N., Vvsokomolekulyarnye Soedineniya 2, ii76-88 (1960). (46) Vassallo, D. A,, A N ~ L CHEM. . 33, 1823 (1961). (47) Weissberger, A., ed., “Physical Methods in Organic Chemistry,” pp. 1620-3, 1701. I, Part 11, 3rd ed., Interscience, New York, 1960 (Cha . 32 on Electron IJIicroscopy by F. Hamm) .
(28) AIcCrone, Organization of Polymers into Materials
LWQ~ Description Composition-Decomposition Properties I Macromolecular domain Atoms in stoichiometric Chemical reactivity, inproportion and stereoherent solubility of influence arrangement I1 Habit of particles in a Kinds, yo molecules con- Specific surfaces; rates of tacting same or different reactions; etc. point, edge, or surface kind 111 Each phase: liquid rub- Kinds, yo components in Bulk properties at each space: random or order phase: absolute soluber, glass, crystalline bility IV Material: laminate. lstex, Kinds, 5’0 and distribution Properties as manufacof phases; changes tured, tested, or used foam, fabric The classification is meant to he flexible enough to encompass additional information aiid n m knosvledge so as to increasr understanding of present materials and point the nay toward improvement. ACKNOWLEDGMENT
The author gratefully acknowledges the experinicntal and interpretive skills of his colleague, Ann hl. Thomab, in electron microecopical experiments illustrated by Figures 3 and 4. He also acknowledges the advice of Donald 1)‘. Davis and the Microscopical Group. Donald L. Swanson, Ivor H. Updegraff, Henry P. Wohnsiedler, and William G. Deichwt. LiTERATURE CITED
(1) d S l ’ X Bull., July 1952, p. 22. (2) Bacskai, R., Pohl, H. A,, J , Polymer Sci. 42, 151-7 (1960). (3) Beredjick, S . , Ahlbeck, R. A,, Kmei, T. K., Iiies, H. E., Jr., Ibid., 46, 268-70 (1960). (4) Bdlmeyer, F. W., Jr., unpublished data. (5) Botty, M. C., ASTM Photogra hic Exhibit. 50th Meeting, New York &ty, June 23-2T, 1952. (6) Botty, hl. C., Felton, C. D., Anderson, R. E., Textile Research J . 30, 959-65, (1960). (7) Chamot, E. 321.. Mason, C. W., “Handbook of Chemical Microscopy,” Vol. I, 3rd ed., Wiley, New York. 1958. (8) Chem. Eng. .Vews, Kov. 2, 1959, p. 39
(9) Critchfield, F. E., Johnson, D. P., ANAL. CHEX 33, 1834 (1961). ( l o ) Eirich, F., private communication, hov. 6, 1957. (11) Eirich, F., Mark, H., CongzBs Intern. Nicroscopie Electronipe Paris, Sept. 14-22, 1950. (12) Erath, E. H., Spurr, It. A., J . Polymer Sei. 35, 391-9 (1959). (13) Flory, P. J., “Principles of Polymer Chemist*ry,” p. 424, Cornel1 University Press, Ithaca, N. Y., 1953. (14) Freudenthal, A. M . j Phus. Today 12, 16-19 (1959). (15) Frey-Wyssling, A,, “Submicroscopic Mor hology of Protoplasm,” 2nd. Englsh ed., Elsevier, New York, 1953. (16) Gailey, J. A., h . 4 ~ CHEM. . 33, 1831 (1961). (17) ,Gibson, &I. E., Jr., IIeidner, R. H., Ibzd., 33, 1825 (1961). (18) Gloor, W. E., Modern Plastics 38, 111-14, 212 214 (1960). (19) Hall, C. h., Doty, P., J . Am. Chem. SOC.80, 1269-74 (1958). (20) Hock, C. W Abbott,, A. ii., Rubber Age 82, Dee. 1957, pp. 471-5. (21) Ke, B., Division of Analytical Ghemistry, 139t,h Meeting, ACS, St. Louis, Mo., March 1961. (22) Lindsay, R. B., Rhode Island College J . 1, 7-12 (1959). (23) Loveland, R. P., Am. Soc. Testing Materials Bull. Yo. 143, 95 (1952). (24) Luongo, J. P., ASAL. CHEM. 33, 1816 (1961).
(25) Mark, H., Chem. W e e k 76, April 2, 1958, p . 36-40. (26) Mar!. , H.., Sci. American 197. 81-9 (1957). (27) Mark, H. F., Tobolsky, A. V., “Physical Chemistry of High Polymeric Systems,” p. 27, Interscience, New York, 1950.
-
1.
RECEIVEDfor review July 17, 1961. Accepted September 19, 1961. Division
of Analytical Chemistry, 139th Meeting, ACS. St. Louis, %Io., March 1961.
9. P. LUONGB Bell Telephone laboraforie;, Inc., Murray Hill,
b Absorption spectroscopy has been utilized to characterize the chemical structure (and structural abnormalities) of polymers. Among the examples described are the determination of the various olefinic groups, identification of substituted aromatks, crystallinity measurements, pyrolysis techniques, olyethylene branching studies, quantitative determinakions, and following induced structural changes. Ultraviolet s p e c ~ ~ o 5 c o ~ean y also contribute to
N. 1.
polymer studies. Examples such as the quantitative determination of polymer additives-Le., antioxidants, expanding agents, slip agents, etc.--are described.
large number of publications on the subject indicate that the use of absorption spectroscopy for the structural analysis of polymers has grown rapidly during the past 10 to 16 HE
years. This widespread use of infrared has coincided with the rapid growth of the synthetic and natural resins industries since about 1946. During this time a n advanced polymeriaation technology has produced polymers whose structures as well as structural abnormalities necefisitated a new and more suitable technique for their identification. The unique capabilities of infrared spectroscopy became recognized as a means of fulfilling the analytical
