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Methods of investigation radiographic method for studying the structure of polymer composites
Structure of polymer composites
2941
REFERENCES 1. A.L. VOLYNSKII and N. F. BAKEYEV, Vysokodispersnoye orientirovannoye sostoyanie polimerov (Highly Disperse Oriented State of Polymers). p. 192, Moscow, 1984 2. A. L VOLYNSKII, V. S. LOGINOV, N. A. PLATE and N. F. BAKAYEV, Vysokomol. soyed. A23, 805, 1981 (Translated in Polymer Sci. U.S.S.R. 23: 4, 902, 1981) 3. A. L VOLYNSKII, V. S. LOGINOV and N. F. BAKEYEV, Vysokomol. soyed. B22: 484, 1980 (Not translated in Polymer Sci. U.S.S.R.) 4. L. M. Y A R Y S H E V A , L. Yu. PAZUKHINA, N. M. KABANOV, G. M. LUKOVKIN, A. L. VOLYNSKII and N. F. BAKEYEV, Vysokomol. soyed. A26: 388, 1984 (Translated in Polymer Sci. U.S.S,R. 26: 2, 433, 1984) 5. A. L. VOLYNSKH, V. I. GERASIMOV and N. F. BAKEYEV, Vysokomol. soyed. AIT: 2461, 1975 (Translated in Polymer Sci. U,S.S.R. 17: 11, 2831, 1975) 6. A. L VOLYNSKII, N. A. SHITOV and N. F. BAKEYEV, Vysokomol, soyed. A23: 859, 1981 (Translated in Polymer Sci. U.S.S.R. 23: 4, 959, 1981) 7. H, R. BROWN, J. Polym. Sci. Polym. Phys. Ed. 21: 483, 1983 8. A. L VOLYNSKH, O. V. KOZLOVA and N. F. BAKEYEV, Vysokomol. soyed. A27: 2169, 1985 (Translated in Polymer Sci. U.S.S.R. 27: 10, 2436, 1985) 9. A. L. VOLYNSKI1, V. S. LOGINOV, N. A. PLATE and N. F. BAKEYEV, Vysokomol. soyed. A22: 2727, 1980 (Translated in Polymer Sci. U.S.S.R. 22: 12, 2991, 1980) 10. G. M. LUKOVKIN, L. M. YARYSHEVA, L. Yu. KABAL'NOVA, A. L. VOLYNSKII, P. V. KOZLOV and N. F. BEKAYEV, Vysokomol. soyed. A29: 198, 1987 (Translated in Polymer Sci. U.S.S.R. 29: 1,224, 1987)
Polymer ScienceU.S.S.R.Vol. 31, No. 12, pp. 2941-2943, 1989 Printed in Poland
0032 3950/89 $10.00+.00 © 1991 PergamonPress pie
METHODS OF INVESTIGATION RADIOGRAPHIC METHOD FOR STUDYING THE STRUCTURE OF POLYMER COMPOSITES* A. Yu. SHAULOV, M. A. LYAPUNOVA, G. A. GR1GORYAN, G. D. Z m r K o v and
A.
V.
SHISHKOV
Institute of Chemical Physics, U.S.S.R. Academy of Sciences
(Received 6 February 1989) For investigating the structure of a composite material - its dimensions, form and distribution in space of the particles of one of its components, the method of radioautography was applied. To this end, a tritium-labelled divinylstyrene block-copolymer was synthesized; this was applied to the surface of a dispersed filler and introduced into a polyethylene matrix. From microphotographs evidence was obtained indicating that the elastomer encapsulating * Vysokomol. soyed. A31: No. 12, 2678-2679, 1989.
2942
A. Yu. SHAULOVet aL
the filler, after forming of the material predominantly remains at the surface of the filler. A histogram of the distance distribution between the nearest elastomer particles is presented. The probability of a uniform distribution of distance between the nearest elastomer-coated particles (0. 65), and the mean thickness of the elastomer layer (25 nm) were evaluated. STuoi~s of the topology of polymer composites (space distribution, form and diemensions of component particles) are needed in the development of new materials. The basic methods for studying the topology of such systems presently are optical and electron microscopy [1], which require special shading methods. However, these methods have some substantial drawbacks: low sensitivity and the need of complicated instrumentation. As an alternative approach to studies of the structure of polymer composites we may regard the method of radioautography, in which a radioactive label, as a source of nuclear radiation covalently bound to the studied object, is introduced into one of the phases in the blend. The radiation is recorded by a photographic emulsion; the latent image - "autograph" after development cart be studied with a microscope. The application of a photoemulsion magnifies the "image" of individual atoms to the dimensions of the photosensitive grain which determines the resulution of the method (0" 18 m-1) [2]. The main advantages of radioautography are the minimum "disturbance" of the object studied introduced by the label, and the extraordinary sensitivity of the method, enabling us to record individual atoms of the readioactive element, and consequently also monolayers of the polymer. We investigated the possibility to apply radioautographY in the study of a heterogeneous syst e m - a polymer filled with a dispersion carrying an elastomer coating; particularly we tried to determine the distribution function of inter-particle distance, and the particle shape and dimensions. To t his end ~e have synthetized an elastomer labelled by tritium ( T ) - t h e radioactive isotope of hydrogen (3H). Nuclear characteristics of the isotope: half-life 12.3 years, soft fl-radiation (Ea = 17-9 keV), with a short range of/~-particle path in condensed phase (1 #m). The synthesis of the radioactive elastomer was carried out by bombarding a divinylstyrene block-copolymcr (DST-30, M = l . 2 x 105) by hot tritium atoms, generated over the surface of a glowing tungsten filament (2000 K) [3]. In this way we obtained a polymer with a stable ~ / C - T bond, exhibiting a very low rate of exchange with a hydrogen atom under normal conditions. The grafting of the label proceeded by way of hydrogen detachment and subsequent recombination of the polymer radical fragment with atomic tritium RI -- H3C
+ T --, Rt - (~H2 + H T
R1 - - CH2 + T --* Rt - CH2T and by hydrogenation of the double bond R2 - ( - H 2 C - C H = C H - CH2 - ), - R2 + 2T --* Rz - ( - H2C - CHT - CHT - C H - ) , - Re The resulting polymer (T-DST-30) was reprecipitated by ethanol from solution in diethyl ether. Specific activity of the polymer was 0' 8 curie/g. The studied objects were two composites: a blend of H D P E (M=3-1 ×105, T,,=132 °) with T-DST-30 (vol.~), and a blend of H D P E with glass spheres coated with the labelled elastomer (20 wt.yo relative to the filler, mean sphere diameter 40 /~m, Ssp=0"4 m 2 / g ) , a t a volume content of f i l l e r - 1~ . The elastomer was introduced into the blend from a solution in diethyl ether, in the first case onto powdered PE, in the second case onto the filler; the solvent was removed by vehement stirring. The dry blend was granulated and pressed at 160 °. The image - "autograph" of the labelled polymer was obtained by application of the highly sensitive photoemulsion U K onto the surface of the composite. Exposure time was 8 hr. The obtained image was photographed in an optical microscope. The radioautograph of a comFosite containing the filler with the labelled elastomer is shown
Structure of polymer composites
2943
in Fig. 1; Fig. 2 demonstrates the result of a statistical treatment of the d a t a - a histogram of the distribution of interparticle distance r r=
[(X--Xj)2+(y--yj)2] 1/2,
where x, y are particle coordinates. Numerical data were treated using the computer "Nova-3" of the "General Data" company. The number of points from the photograph, included in the calculation, was 200. A preliminary check has shown that the number of particles with mutually superimposed images is negligible and cannot introduce an appreciable error into the final result, D 100
-
50
2 FIG. 1
q
G r;mm
FIo. 2
I~qG. 1. Radioautography of an elastomer applied to glass spheres and distributed in PE matrix. Concentration of glass spheres 1 vol.~o, concentration of elastomer T-DST-30:20 w t . ~ relative to filler. FIo. 2. Histogram of distances between the nearest particles of labelled elastomer. A comparison of the autographs of the elastomer coating the filler, and of that introduced directly into the volume of PE has shown that the size of the images, of near to spherical shape, in the first case varies within 20 to 100 am, while tlae size of elastomer particles in PE does not exceed the size of the photoemulsion grain (1 am). This indicates that in the proces of material forming, the elastomer applied to the filler remains distributed over its surface. The mean calculated thickness of the elastomer layer was equal to 25 nm. The probability of a uniform distribution of elastomer particles was 0"65. The authors are indebted to N. V. Uvarova and M. B. Yevgenev for supporting this work and for supplying the photoemulsion samples.
Translated by D. DOSKO~ILOV~. REFERENCES 1. K. B. BAKNELL, Udaroprochnye plastiki (Impact-resistant Plastics). p. 327, Leningrad, 1981 2. O. I. YEPIFANOVA, B. B. TERSKIKH and A. F. ZAKHAROV, Radioavtografiya (Radioautography), p. 245, Moscow, 1977 3. A. V. SHISHKOV, E. S. FILATOV, Ye. F. SIMONOV, M. S. UNUKOVICH, V. I. GOLDANSKII and A. N. NESMEYANOV, Dokl. A N SSSR 228: 1237, 1976
2941
REFERENCES 1. A.L. VOLYNSKII and N. F. BAKEYEV, Vysokodispersnoye orientirovannoye sostoyanie polimerov (Highly Disperse Oriented State of Polymers). p. 192, Moscow, 1984 2. A. L VOLYNSKII, V. S. LOGINOV, N. A. PLATE and N. F. BAKAYEV, Vysokomol. soyed. A23, 805, 1981 (Translated in Polymer Sci. U.S.S.R. 23: 4, 902, 1981) 3. A. L VOLYNSKII, V. S. LOGINOV and N. F. BAKEYEV, Vysokomol. soyed. B22: 484, 1980 (Not translated in Polymer Sci. U.S.S.R.) 4. L. M. Y A R Y S H E V A , L. Yu. PAZUKHINA, N. M. KABANOV, G. M. LUKOVKIN, A. L. VOLYNSKII and N. F. BAKEYEV, Vysokomol. soyed. A26: 388, 1984 (Translated in Polymer Sci. U.S.S,R. 26: 2, 433, 1984) 5. A. L. VOLYNSKH, V. I. GERASIMOV and N. F. BAKEYEV, Vysokomol. soyed. AIT: 2461, 1975 (Translated in Polymer Sci. U,S.S.R. 17: 11, 2831, 1975) 6. A. L VOLYNSKII, N. A. SHITOV and N. F. BAKEYEV, Vysokomol, soyed. A23: 859, 1981 (Translated in Polymer Sci. U.S.S.R. 23: 4, 959, 1981) 7. H, R. BROWN, J. Polym. Sci. Polym. Phys. Ed. 21: 483, 1983 8. A. L VOLYNSKH, O. V. KOZLOVA and N. F. BAKEYEV, Vysokomol. soyed. A27: 2169, 1985 (Translated in Polymer Sci. U.S.S.R. 27: 10, 2436, 1985) 9. A. L. VOLYNSKI1, V. S. LOGINOV, N. A. PLATE and N. F. BAKEYEV, Vysokomol. soyed. A22: 2727, 1980 (Translated in Polymer Sci. U.S.S.R. 22: 12, 2991, 1980) 10. G. M. LUKOVKIN, L. M. YARYSHEVA, L. Yu. KABAL'NOVA, A. L. VOLYNSKII, P. V. KOZLOV and N. F. BEKAYEV, Vysokomol. soyed. A29: 198, 1987 (Translated in Polymer Sci. U.S.S.R. 29: 1,224, 1987)
Polymer ScienceU.S.S.R.Vol. 31, No. 12, pp. 2941-2943, 1989 Printed in Poland
0032 3950/89 $10.00+.00 © 1991 PergamonPress pie
METHODS OF INVESTIGATION RADIOGRAPHIC METHOD FOR STUDYING THE STRUCTURE OF POLYMER COMPOSITES* A. Yu. SHAULOV, M. A. LYAPUNOVA, G. A. GR1GORYAN, G. D. Z m r K o v and
A.
V.
SHISHKOV
Institute of Chemical Physics, U.S.S.R. Academy of Sciences
(Received 6 February 1989) For investigating the structure of a composite material - its dimensions, form and distribution in space of the particles of one of its components, the method of radioautography was applied. To this end, a tritium-labelled divinylstyrene block-copolymer was synthesized; this was applied to the surface of a dispersed filler and introduced into a polyethylene matrix. From microphotographs evidence was obtained indicating that the elastomer encapsulating * Vysokomol. soyed. A31: No. 12, 2678-2679, 1989.
2942
A. Yu. SHAULOVet aL
the filler, after forming of the material predominantly remains at the surface of the filler. A histogram of the distance distribution between the nearest elastomer particles is presented. The probability of a uniform distribution of distance between the nearest elastomer-coated particles (0. 65), and the mean thickness of the elastomer layer (25 nm) were evaluated. STuoi~s of the topology of polymer composites (space distribution, form and diemensions of component particles) are needed in the development of new materials. The basic methods for studying the topology of such systems presently are optical and electron microscopy [1], which require special shading methods. However, these methods have some substantial drawbacks: low sensitivity and the need of complicated instrumentation. As an alternative approach to studies of the structure of polymer composites we may regard the method of radioautography, in which a radioactive label, as a source of nuclear radiation covalently bound to the studied object, is introduced into one of the phases in the blend. The radiation is recorded by a photographic emulsion; the latent image - "autograph" after development cart be studied with a microscope. The application of a photoemulsion magnifies the "image" of individual atoms to the dimensions of the photosensitive grain which determines the resulution of the method (0" 18 m-1) [2]. The main advantages of radioautography are the minimum "disturbance" of the object studied introduced by the label, and the extraordinary sensitivity of the method, enabling us to record individual atoms of the readioactive element, and consequently also monolayers of the polymer. We investigated the possibility to apply radioautographY in the study of a heterogeneous syst e m - a polymer filled with a dispersion carrying an elastomer coating; particularly we tried to determine the distribution function of inter-particle distance, and the particle shape and dimensions. To t his end ~e have synthetized an elastomer labelled by tritium ( T ) - t h e radioactive isotope of hydrogen (3H). Nuclear characteristics of the isotope: half-life 12.3 years, soft fl-radiation (Ea = 17-9 keV), with a short range of/~-particle path in condensed phase (1 #m). The synthesis of the radioactive elastomer was carried out by bombarding a divinylstyrene block-copolymcr (DST-30, M = l . 2 x 105) by hot tritium atoms, generated over the surface of a glowing tungsten filament (2000 K) [3]. In this way we obtained a polymer with a stable ~ / C - T bond, exhibiting a very low rate of exchange with a hydrogen atom under normal conditions. The grafting of the label proceeded by way of hydrogen detachment and subsequent recombination of the polymer radical fragment with atomic tritium RI -- H3C
+ T --, Rt - (~H2 + H T
R1 - - CH2 + T --* Rt - CH2T and by hydrogenation of the double bond R2 - ( - H 2 C - C H = C H - CH2 - ), - R2 + 2T --* Rz - ( - H2C - CHT - CHT - C H - ) , - Re The resulting polymer (T-DST-30) was reprecipitated by ethanol from solution in diethyl ether. Specific activity of the polymer was 0' 8 curie/g. The studied objects were two composites: a blend of H D P E (M=3-1 ×105, T,,=132 °) with T-DST-30 (vol.~), and a blend of H D P E with glass spheres coated with the labelled elastomer (20 wt.yo relative to the filler, mean sphere diameter 40 /~m, Ssp=0"4 m 2 / g ) , a t a volume content of f i l l e r - 1~ . The elastomer was introduced into the blend from a solution in diethyl ether, in the first case onto powdered PE, in the second case onto the filler; the solvent was removed by vehement stirring. The dry blend was granulated and pressed at 160 °. The image - "autograph" of the labelled polymer was obtained by application of the highly sensitive photoemulsion U K onto the surface of the composite. Exposure time was 8 hr. The obtained image was photographed in an optical microscope. The radioautograph of a comFosite containing the filler with the labelled elastomer is shown
Structure of polymer composites
2943
in Fig. 1; Fig. 2 demonstrates the result of a statistical treatment of the d a t a - a histogram of the distribution of interparticle distance r r=
[(X--Xj)2+(y--yj)2] 1/2,
where x, y are particle coordinates. Numerical data were treated using the computer "Nova-3" of the "General Data" company. The number of points from the photograph, included in the calculation, was 200. A preliminary check has shown that the number of particles with mutually superimposed images is negligible and cannot introduce an appreciable error into the final result, D 100
-
50
2 FIG. 1
q
G r;mm
FIo. 2
I~qG. 1. Radioautography of an elastomer applied to glass spheres and distributed in PE matrix. Concentration of glass spheres 1 vol.~o, concentration of elastomer T-DST-30:20 w t . ~ relative to filler. FIo. 2. Histogram of distances between the nearest particles of labelled elastomer. A comparison of the autographs of the elastomer coating the filler, and of that introduced directly into the volume of PE has shown that the size of the images, of near to spherical shape, in the first case varies within 20 to 100 am, while tlae size of elastomer particles in PE does not exceed the size of the photoemulsion grain (1 am). This indicates that in the proces of material forming, the elastomer applied to the filler remains distributed over its surface. The mean calculated thickness of the elastomer layer was equal to 25 nm. The probability of a uniform distribution of elastomer particles was 0"65. The authors are indebted to N. V. Uvarova and M. B. Yevgenev for supporting this work and for supplying the photoemulsion samples.
Translated by D. DOSKO~ILOV~. REFERENCES 1. K. B. BAKNELL, Udaroprochnye plastiki (Impact-resistant Plastics). p. 327, Leningrad, 1981 2. O. I. YEPIFANOVA, B. B. TERSKIKH and A. F. ZAKHAROV, Radioavtografiya (Radioautography), p. 245, Moscow, 1977 3. A. V. SHISHKOV, E. S. FILATOV, Ye. F. SIMONOV, M. S. UNUKOVICH, V. I. GOLDANSKII and A. N. NESMEYANOV, Dokl. A N SSSR 228: 1237, 1976