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Determination of crystallinity in polytetrahydrofuran
Determination of crystallinity in polytetrahydrofuran
1901
(3) I t is proposed to use these methods to explain the structural properties of cellulose hydrate fibres, according to the method of formation and orientation.
Translated by E, SEMERE REFERENCES 1. G. V. NIKONOVICH and Kh. U. USMANOV, Khimich. volokna, No. 6, 39, 1967 2. A. I. MEOS and M. N. VISItNYAKOVA, Khimich. volokna, No. 5, 20, 1960 3. Zh. G. VASILENKO and N. V. MIKIIAIL0V, Vysokomol. soyed. B10: 2405, 1968 (Not translated in Polymer Sci. U.S.S.R.) 4. V. A. BERESTNEV, K. Kh. R A Z I K 0 V and V. A. KARGIN, Vysokomol. soyed. 5:1156, 1963. (Translated in Polymer Sci. U.S.S.R. 5: 1, 1964)
D E T E R M I N A T O N OF CRYSTALLINITY IN POLYTETRAHYDROFURAN * E. F. VAI~SHTEIN,M. YA. KUSttNEREV, A. A. P o r o v and S. G. ENTELIS Institute of Chemical Physics, U.S.S.R. Academy of Sciences
(Received 4 June 1969) THE physical and mechanical properties of polymers are chiefly determined by their crystallin~ phase content. The literature describes very extensively the various methods of determining crystallinity [1-3]. This paper aims at developing methods for determining the crystallinity of polytetrahydrofuran (PTttF). METHODS OF EXPERIMENT I R spectra of the eopolymers were obtained in a UR-10 Carl Zeiss (German Democratic Republic) spectrophotometer in the 500-1500cm -1 range. Crystallizing pol~mers were melted at 50 ° and simultaneously applied on K B r crystals and in the holder of the sample for X-ray analysis. Crystallinity was determined in a pseudo-equilibrium state. When the variation ia optical density of absorption bands was complete in the spectrum, simultaneous I R spectroscopic and X-ray measurements were carried out. Saxnple temperature was carefully controlled to prevent melting. The crystallinity of the polymers was determined in a URS-50Z apparatus by the reflection method. The crystallinity of P T H F polymers of molecular weights ranging from 2000 to 10,000 was determined. X-ray method. X-ray photographs of amorphous polymers show an intense halo with a m a x i m u m at d = 4 . 3 A, whereas in Debye crystallograms of partially crystallized polymers the interplanar distances have the strongest maxima iu this range (d 4.38 and 3.57 A) [4]. Determining the degree of crystallinity from the intensities of individual peaks is hardly * Vysokomol. soyed. A l l : No. 7, 1671-1673, 1970.
1902
E.F.V.~I~SHT]~IN et al.
advisable since the half-width of lines depends largely on the size of crystals and their defects. As a consequence of structural defects intensities are redistributed between individual max i m a. The intensity ratio of the amorphous halo o f a partially and wholly amorphous sample gives an inaccurate value, since it is overlapped by reflections of the crystalline sample. We propose a method for determining crystallinity which is based on the ratio of the integral intensities of reflections with indices 002 and 202 to the overall integral intensity of these reflections and the amorphous halo situated under these peaks (Fig. 1). The area under these reflections and the amorphous halo is accepted as the measure of the integral intensit its.
z0
5"
FIG. 1. Determining the crystallinity of P T H F . The cross-hatched area belongs to the amorphous part of the sample" 1 - - d = 3 . 5 7 (202), 9 - - d = 4 . 3 8 A (002). I t should be noted t h a t this method is relative as the area under the other reflections shown in the X - r a y photographs was not taken into consideration and because the effect of lattice defects on the intensities of individual peaks is unknown. Determining crystallinity from the areas of all the peaks and the amorphous halo showed a 5~o discrepancy compared with results obtained by the m e t h o d proposed. Therefore, because of its great simplicity and speed it is highly advisable to determine crystallinity from the intensity of the two strongest reflections. I n all cases a somewhat lower crystallinity is determined. I R spectroscopy. To determine crystallinity it is advisable to use bands with ~-polarization and amorphous bands.* I t has been pointed out [5] t h a t amorphous bands suitable for analytical purposes could not be established in the spectrum of P T t t F . Therefore, to obtain calibration curves, X - r a y * Bands characterizing vibrations of the crystalline lattice itself are below the spectrum range studied.
Scientific conference on physico-chemistry of polymers in Bulgaria
1907
filler in tile mixture. I t was noted t h a t this law only holds for linear polymers and not for weakly branched systems. Tile plenary paper by Yu. V. Zelenev (U.S.S.R.) "Physical Methods of Investigating P o l y m e r s " dealt with the possibility of using meehanieM, electrieal, magnetic, optieM and thermophysieM methods, which help to examine the macroscopic manifestation of variations in molecular mobility in polymers of different structures. A method was proposed for tile evaluation of effective frequencies of different types of molecular motion from results of static (not frequency) methods of investigation (methods of temperstare/deformation curves and radiothermolumineseenec, thermophysicM methods: dilatemerry, calorimetry and differential thermal analysis). The opening paper by K. Mush and t~. Kosfcld (German Federal Republic) "Luminescent Properties of Fine Plastic Scintillators"' described results of investigating polystyrene-tetrapheny! butadienc scintillators 0"5 InIn in thickness. The authors discussed the mechanism of non-radical energy transfer by diffusion us a result of dipole resonance. Me'~surement of the temperature dependence of scintillation intensity in the glass transition range indicates that the time of molecular q u a n t u m energy transfer decreases with ml increase in temperature us a consequence of the mobility of phenyl groups and main polymer chains. The opening paper by A. S. K u z ' mmskii (U.S.S.R.) "Ageing of E l a s t o m e r s " contained an analysis of the specific bchaviour of rubber-like polymers during ageing and examined problems of stabilization of rubbers., I t was noted t h a t effects such as fatigue, frietionM wear, chemical relaxation and aceumulatien of irreversible residual deformation in rubbers arc based on mechanical and chemicM processes. The main factors influencing atmospheric ageing of rubbers, according to application, light and operational conditions, were indicated. The author defined the chief problems of fm'ther investigations of ageing (modification of resins, use of polymer stabilizers, supression of heterolytie processes, development of non-eolouring stabilizers and stabilizers for high temperatures). The paper by B. Filip and K. ~Vulf (German Democratic Republic) entitled "RheologieM Studies of Concentrated Solutions of Cellulose X a n t h a t e and Polyacrylonitrile" described results of investigating the relation between the chemical parameters and theological values of viscose and polyaerylonitrile solutions in dimethyltbrmamide during flow in short capillaries. I t was noted t h a t with the same Newtonian initiM viscosity various chemicM parameters have a marked effect on solution flow in shear stress. Among the sectional papers were ones by Yu. S. Li p at o v et al. (U.S.S.R.) entitled "Effect of Solid Surface on the Structure of Boundary Layers of Polymer Coatings and Adhesion to Different Substrata" and "Microscopic Studies in the Structural Field of Reticular Polyurethmte Rubbers and Thermally Oriented Polyamide Fibres". There was considerable interest amoltg the participants of the conference in the paper by T. D. Shermergor (U.S.S.R.) "Elastic and Rheologieal Characteristics of P o l y m e r s " , in which the modern aspects of' the mechanics of a heterogeneous viseo-elastie m e d i u m are examined. Interesting papers were read by V. K a b a i v a n o v et al. (Bulgaria): "Investigation of the Copol?maerization of Vinyl Acetate and Crotonaldehyde", "Polycondensation Resins from Isoeyanuratcs and Organo-Silicon Compounds" and " S t u d y of Copolymerization Kinetics of Trioxane and Styrene under the Catalytic Effect of" the Complex". Papers by M. N a t o v et al. (Bulgaria): " S t u d y of Rheological Properties of Elastomers" and "Breakdown Mechanism of Thermoplastic Materials" were of considerable interest, among the participants. Papers by M. Mikhailov et al. (Bulgaria) " S t u d y of the Growth of Edrite Structures in a Thin Layer of Melted Polyoxymethylene D i a e e t a t e " and "Dependence of the Conformation of FormMdehyde Polymers o~ Conditions of P r e p a r a t i o n " and by I. Mladenov et al. : "Electrically Conductive Vulcanizates, filled with Modified Graphite" and " S t u d y of the Possibilities of Reducing Ageing of Vuleanizates" shoud also be mentioned. Finally, papers by P. H e d v i g and M. Kisben6 (Hungary) 'Thermoelectric Studies of Irreversible Transitions in Polyvinyl Chloride P ro d u ct s " and by M. Pivinskii (Poland) "Modified Melamine-Formaldehyde Besin for Moulding Powders" are w o r t h y of mention.
1904
Y u . V. Z E L E N E V
3. I. I. NOVAK, V. A. SUCHKOV and Ye. A. IVANOVA, Vysokomol. soyed, A9: 2742, 1967 (Translated in Polymer Sci. U.S.S.R. 9: 12, 3104, 1967) 4. E. F. VAINSHTEIN, M. Ya. KUSHNEREV, A. A. POPOV and S. G. ENTELIS, Vysokomol. soyed. A l l : 1606, 1969 (Translated in Polymer Sci. U.S.S.R. l h 7, 1820, 1969) 5. K. IMADA, H. TADOKORO, A. U M E H A R A and S. MURAHASHI, J. Chem. Phys. 42: 8, 1965
REPORTS ALL-UNION SYMPOSIUM ON RELAXATION EFFECTS* Yu. V. ZELENEV THE All-Union Symposium on relaxation effects in structural liquid media was held from 31st October to 3rd November, 1969 in Dushanbe in the Physieo-Teehnical Institute of the Tadzhik S.S.R. Academy of Sciences and in the Tadzhik V. I. Lenin State University. Three plenary and six sectional meetings were held during the Symposium (work was carried out in two sections: "Acoustic relaxation" and "Optical Spectroscopic Studies of Relaxation") and results of theoretical and experimental investigations of relaxation effects in high molecular weight compounds were discussed in detail. The main opening paper by S. Ya. Frenkel' "Structural Relaxation and Orientation Melting in Pol?~mer Solutions" analysed conditions of applicability of relaxation ideas within the framework of equilibrium thermodynamics and causes leading to irreversibility. Special properties of intramolecular phase transition of the sphere--globule type, which are the most general characteristics of structural relaxation in polymer solutions, were examined. I t was noted t h a t the chief experimental facts in the study of structural relaxation of polymer solutions are: structural hysteresis during cyclic variations of temperature, continuous heterophase fluctuations and larger structural formations in the equilibrium range and blurring of binodals and spinodals in the diagrams of coexistence. The paper by I. G. Mikhailov and L. I. Savina "Structural R e l a x a t i o n in E p o x y Resins" dealt with ultrasonic investigations of epoxy resins with different viscosities over a wide range of temperature. I t was noted t h a t the velocity of the ultrasonic vibrations measured at 1-3 Mc/s for resins of low viscosities shows a linear dependence on temperature and a negative temperature coefficient. The ultrasonic absorption coefficient measured by a pulse method at frequencies of 3 to 54 Me/s is characterized by a reduction for resins of low viscosity with increase in temperature and by an increase with increase in frequency. Highly viscous resins are characterized by a m a x i m u m absorption coefficient which on increasing the frequency is displaced to high temperatures. The higher the viscosity of the resin, the higher the temperature at which the m a x i m u m sound absorption coefficient is observed, i.e. relaxation of shear viscosity takes place. I n their paper " R e l a x a t i o n Effects in Liquid Structural Micro- and Macro-heterogeneous Polymer Compositions" G. M. B a r t e n e v and Yu. V. Zelenev examined results of studying molecular motion in amorphous polymers. Amorphous high molecular weight substances in the glassy .and high-elastic states (or in the solid aggregate state) are at the same time typical structur* Vysokomol. soyed. A12: No. 7, 1674-1675, 1970.
1901
(3) I t is proposed to use these methods to explain the structural properties of cellulose hydrate fibres, according to the method of formation and orientation.
Translated by E, SEMERE REFERENCES 1. G. V. NIKONOVICH and Kh. U. USMANOV, Khimich. volokna, No. 6, 39, 1967 2. A. I. MEOS and M. N. VISItNYAKOVA, Khimich. volokna, No. 5, 20, 1960 3. Zh. G. VASILENKO and N. V. MIKIIAIL0V, Vysokomol. soyed. B10: 2405, 1968 (Not translated in Polymer Sci. U.S.S.R.) 4. V. A. BERESTNEV, K. Kh. R A Z I K 0 V and V. A. KARGIN, Vysokomol. soyed. 5:1156, 1963. (Translated in Polymer Sci. U.S.S.R. 5: 1, 1964)
D E T E R M I N A T O N OF CRYSTALLINITY IN POLYTETRAHYDROFURAN * E. F. VAI~SHTEIN,M. YA. KUSttNEREV, A. A. P o r o v and S. G. ENTELIS Institute of Chemical Physics, U.S.S.R. Academy of Sciences
(Received 4 June 1969) THE physical and mechanical properties of polymers are chiefly determined by their crystallin~ phase content. The literature describes very extensively the various methods of determining crystallinity [1-3]. This paper aims at developing methods for determining the crystallinity of polytetrahydrofuran (PTttF). METHODS OF EXPERIMENT I R spectra of the eopolymers were obtained in a UR-10 Carl Zeiss (German Democratic Republic) spectrophotometer in the 500-1500cm -1 range. Crystallizing pol~mers were melted at 50 ° and simultaneously applied on K B r crystals and in the holder of the sample for X-ray analysis. Crystallinity was determined in a pseudo-equilibrium state. When the variation ia optical density of absorption bands was complete in the spectrum, simultaneous I R spectroscopic and X-ray measurements were carried out. Saxnple temperature was carefully controlled to prevent melting. The crystallinity of the polymers was determined in a URS-50Z apparatus by the reflection method. The crystallinity of P T H F polymers of molecular weights ranging from 2000 to 10,000 was determined. X-ray method. X-ray photographs of amorphous polymers show an intense halo with a m a x i m u m at d = 4 . 3 A, whereas in Debye crystallograms of partially crystallized polymers the interplanar distances have the strongest maxima iu this range (d 4.38 and 3.57 A) [4]. Determining the degree of crystallinity from the intensities of individual peaks is hardly * Vysokomol. soyed. A l l : No. 7, 1671-1673, 1970.
1902
E.F.V.~I~SHT]~IN et al.
advisable since the half-width of lines depends largely on the size of crystals and their defects. As a consequence of structural defects intensities are redistributed between individual max i m a. The intensity ratio of the amorphous halo o f a partially and wholly amorphous sample gives an inaccurate value, since it is overlapped by reflections of the crystalline sample. We propose a method for determining crystallinity which is based on the ratio of the integral intensities of reflections with indices 002 and 202 to the overall integral intensity of these reflections and the amorphous halo situated under these peaks (Fig. 1). The area under these reflections and the amorphous halo is accepted as the measure of the integral intensit its.
z0
5"
FIG. 1. Determining the crystallinity of P T H F . The cross-hatched area belongs to the amorphous part of the sample" 1 - - d = 3 . 5 7 (202), 9 - - d = 4 . 3 8 A (002). I t should be noted t h a t this method is relative as the area under the other reflections shown in the X - r a y photographs was not taken into consideration and because the effect of lattice defects on the intensities of individual peaks is unknown. Determining crystallinity from the areas of all the peaks and the amorphous halo showed a 5~o discrepancy compared with results obtained by the m e t h o d proposed. Therefore, because of its great simplicity and speed it is highly advisable to determine crystallinity from the intensity of the two strongest reflections. I n all cases a somewhat lower crystallinity is determined. I R spectroscopy. To determine crystallinity it is advisable to use bands with ~-polarization and amorphous bands.* I t has been pointed out [5] t h a t amorphous bands suitable for analytical purposes could not be established in the spectrum of P T t t F . Therefore, to obtain calibration curves, X - r a y * Bands characterizing vibrations of the crystalline lattice itself are below the spectrum range studied.
Scientific conference on physico-chemistry of polymers in Bulgaria
1907
filler in tile mixture. I t was noted t h a t this law only holds for linear polymers and not for weakly branched systems. Tile plenary paper by Yu. V. Zelenev (U.S.S.R.) "Physical Methods of Investigating P o l y m e r s " dealt with the possibility of using meehanieM, electrieal, magnetic, optieM and thermophysieM methods, which help to examine the macroscopic manifestation of variations in molecular mobility in polymers of different structures. A method was proposed for tile evaluation of effective frequencies of different types of molecular motion from results of static (not frequency) methods of investigation (methods of temperstare/deformation curves and radiothermolumineseenec, thermophysicM methods: dilatemerry, calorimetry and differential thermal analysis). The opening paper by K. Mush and t~. Kosfcld (German Federal Republic) "Luminescent Properties of Fine Plastic Scintillators"' described results of investigating polystyrene-tetrapheny! butadienc scintillators 0"5 InIn in thickness. The authors discussed the mechanism of non-radical energy transfer by diffusion us a result of dipole resonance. Me'~surement of the temperature dependence of scintillation intensity in the glass transition range indicates that the time of molecular q u a n t u m energy transfer decreases with ml increase in temperature us a consequence of the mobility of phenyl groups and main polymer chains. The opening paper by A. S. K u z ' mmskii (U.S.S.R.) "Ageing of E l a s t o m e r s " contained an analysis of the specific bchaviour of rubber-like polymers during ageing and examined problems of stabilization of rubbers., I t was noted t h a t effects such as fatigue, frietionM wear, chemical relaxation and aceumulatien of irreversible residual deformation in rubbers arc based on mechanical and chemicM processes. The main factors influencing atmospheric ageing of rubbers, according to application, light and operational conditions, were indicated. The author defined the chief problems of fm'ther investigations of ageing (modification of resins, use of polymer stabilizers, supression of heterolytie processes, development of non-eolouring stabilizers and stabilizers for high temperatures). The paper by B. Filip and K. ~Vulf (German Democratic Republic) entitled "RheologieM Studies of Concentrated Solutions of Cellulose X a n t h a t e and Polyacrylonitrile" described results of investigating the relation between the chemical parameters and theological values of viscose and polyaerylonitrile solutions in dimethyltbrmamide during flow in short capillaries. I t was noted t h a t with the same Newtonian initiM viscosity various chemicM parameters have a marked effect on solution flow in shear stress. Among the sectional papers were ones by Yu. S. Li p at o v et al. (U.S.S.R.) entitled "Effect of Solid Surface on the Structure of Boundary Layers of Polymer Coatings and Adhesion to Different Substrata" and "Microscopic Studies in the Structural Field of Reticular Polyurethmte Rubbers and Thermally Oriented Polyamide Fibres". There was considerable interest amoltg the participants of the conference in the paper by T. D. Shermergor (U.S.S.R.) "Elastic and Rheologieal Characteristics of P o l y m e r s " , in which the modern aspects of' the mechanics of a heterogeneous viseo-elastie m e d i u m are examined. Interesting papers were read by V. K a b a i v a n o v et al. (Bulgaria): "Investigation of the Copol?maerization of Vinyl Acetate and Crotonaldehyde", "Polycondensation Resins from Isoeyanuratcs and Organo-Silicon Compounds" and " S t u d y of Copolymerization Kinetics of Trioxane and Styrene under the Catalytic Effect of" the Complex". Papers by M. N a t o v et al. (Bulgaria): " S t u d y of Rheological Properties of Elastomers" and "Breakdown Mechanism of Thermoplastic Materials" were of considerable interest, among the participants. Papers by M. Mikhailov et al. (Bulgaria) " S t u d y of the Growth of Edrite Structures in a Thin Layer of Melted Polyoxymethylene D i a e e t a t e " and "Dependence of the Conformation of FormMdehyde Polymers o~ Conditions of P r e p a r a t i o n " and by I. Mladenov et al. : "Electrically Conductive Vulcanizates, filled with Modified Graphite" and " S t u d y of the Possibilities of Reducing Ageing of Vuleanizates" shoud also be mentioned. Finally, papers by P. H e d v i g and M. Kisben6 (Hungary) 'Thermoelectric Studies of Irreversible Transitions in Polyvinyl Chloride P ro d u ct s " and by M. Pivinskii (Poland) "Modified Melamine-Formaldehyde Besin for Moulding Powders" are w o r t h y of mention.
1904
Y u . V. Z E L E N E V
3. I. I. NOVAK, V. A. SUCHKOV and Ye. A. IVANOVA, Vysokomol. soyed, A9: 2742, 1967 (Translated in Polymer Sci. U.S.S.R. 9: 12, 3104, 1967) 4. E. F. VAINSHTEIN, M. Ya. KUSHNEREV, A. A. POPOV and S. G. ENTELIS, Vysokomol. soyed. A l l : 1606, 1969 (Translated in Polymer Sci. U.S.S.R. l h 7, 1820, 1969) 5. K. IMADA, H. TADOKORO, A. U M E H A R A and S. MURAHASHI, J. Chem. Phys. 42: 8, 1965
REPORTS ALL-UNION SYMPOSIUM ON RELAXATION EFFECTS* Yu. V. ZELENEV THE All-Union Symposium on relaxation effects in structural liquid media was held from 31st October to 3rd November, 1969 in Dushanbe in the Physieo-Teehnical Institute of the Tadzhik S.S.R. Academy of Sciences and in the Tadzhik V. I. Lenin State University. Three plenary and six sectional meetings were held during the Symposium (work was carried out in two sections: "Acoustic relaxation" and "Optical Spectroscopic Studies of Relaxation") and results of theoretical and experimental investigations of relaxation effects in high molecular weight compounds were discussed in detail. The main opening paper by S. Ya. Frenkel' "Structural Relaxation and Orientation Melting in Pol?~mer Solutions" analysed conditions of applicability of relaxation ideas within the framework of equilibrium thermodynamics and causes leading to irreversibility. Special properties of intramolecular phase transition of the sphere--globule type, which are the most general characteristics of structural relaxation in polymer solutions, were examined. I t was noted t h a t the chief experimental facts in the study of structural relaxation of polymer solutions are: structural hysteresis during cyclic variations of temperature, continuous heterophase fluctuations and larger structural formations in the equilibrium range and blurring of binodals and spinodals in the diagrams of coexistence. The paper by I. G. Mikhailov and L. I. Savina "Structural R e l a x a t i o n in E p o x y Resins" dealt with ultrasonic investigations of epoxy resins with different viscosities over a wide range of temperature. I t was noted t h a t the velocity of the ultrasonic vibrations measured at 1-3 Mc/s for resins of low viscosities shows a linear dependence on temperature and a negative temperature coefficient. The ultrasonic absorption coefficient measured by a pulse method at frequencies of 3 to 54 Me/s is characterized by a reduction for resins of low viscosity with increase in temperature and by an increase with increase in frequency. Highly viscous resins are characterized by a m a x i m u m absorption coefficient which on increasing the frequency is displaced to high temperatures. The higher the viscosity of the resin, the higher the temperature at which the m a x i m u m sound absorption coefficient is observed, i.e. relaxation of shear viscosity takes place. I n their paper " R e l a x a t i o n Effects in Liquid Structural Micro- and Macro-heterogeneous Polymer Compositions" G. M. B a r t e n e v and Yu. V. Zelenev examined results of studying molecular motion in amorphous polymers. Amorphous high molecular weight substances in the glassy .and high-elastic states (or in the solid aggregate state) are at the same time typical structur* Vysokomol. soyed. A12: No. 7, 1674-1675, 1970.