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Method of continuous determination of deformation and chemical changes in fibres over a wide range of temperature and stress
Deformation and chemical changes in fibres
1889
where R is the universal gas constant, w h i c h is 1.987 cal/mole,deg, a n d C--the scale ratio y/x. The value of k was calculated for a n y temperature from the expression k =
-
(dc/dt)lo"
and agreement with the Arrhenius equation verified from the linearity of the diagram plotted in coordinates y = l o g k a n d x = 103/T (Fig. 3). The Table indicates t h a t kinetic parameters calculated b y this method show satisfactory agreement with results of isothermal analysis (ITA) derived b y the authors and available in the literature [4].
CONCLUSIONS B y polyesterification of adipic acid and diethylene glycol it was shown experimentally t h a t kinetic parameters of polyeondensation can he calculated from results of dynamic thermochemical analysis.
TranslaSed by E. SEM'ERE REFERENCES 1. V. P. RYBACHUK and S. I. O M E I . ' C ~ . N K 0 , Vysokomol. soyed. A13: 220, 1971 (Translat e d in P o l y m e r Sci. U.S.S.R. 18: 1,252, 1971) 2. V. P. RYBACHUK, S. I. 0 M E L ' C ~ 0 and K. A. KORNEV, Dokl. A N Ukr.SSR, set. B., 340, 1971 3. E. S. FREEMAN and B. CARROLL, J. Phys. Chem. 62: 394, 1958 4. I. VANCHO-SZlKERCSANYI, E. MAKAY-B~DY, E. SZABO-RETHY and P. I:H~SC~HBERG, J. Polymer Sei. 8, A-l: 2861, 1970
METHOD OF CONTINUOUS DETERMINATION OF DEFORMATION AND CHEMICAL CHANGES IN FIBRES OVER A WIDE RANGE OF TEMPERATURE AND STRESS* A. T. KALASHNIK,L. G. Kuzx~.TSOVA, I. N. Alq'DREYEVA and N. V. MJ:K~AmOV (dec.) All-Union Scientific Research I n s t i t u t e for Synthetic Fibres
(Received 19 May 1972) IN addition to reversible processes, irreversible processes resulting in a change in physical and mechanical properties m a y take place in fibres when heated. By studing these processes valuable information m a y be obtained concerning the t y p e of d e f o r m a t i o n effects a n d their dependence on t e m p e r a t u r e and other experimental conditions, which enables us to determine conditions of h e a t t r e a t m e n t developing fibres with the requisite properties and help to establish t h e relation between initial structure a n d the chemical behaviour of fibres during the s t u d y of pyrolytic processes. * Vysokomol. soyed. A15: No. 7, 1680-1682, 1973.
1890
A. T. KALASHNIX et al.
The methods described for studying deformation effects in polymers during heating [1-4] eua bled us to make observations at comparatively low temperatures (up to the initial decomposition of the polymer), but it was impossible to examine the behaviour of polymers in vacuum and various media with the simultaneous study of chemical and deforanation processes and analysis of breakdown products.
Fie. 1. Layout of the device used for the continuous determination of deformation and chemical processes in fibres: / - - l o a d , 2 - - m a r k , 3--lower quartz support, 4 - clamps, 5 - heating spiral, 6 - container for the thermoeouple, 7--fibre specimen, 8"thermoeouple, 9--reactor, / 0 - - u p p e r support, 1 1 - - t h i n section, 12--wrench, 13--detachable part of the reactor, 1 4 - - t h i n section for connection to the vacuum device or the: device used for the analysis of volatile products. To study those processes in polymers during heating, we proposed a method of conti. nuous measurement of deformations in fibres with a constant linear increase from room
Deformation and chemical changes in fibres
1891
temperature to any given temperature up to 1000 °. The m e t h o d enables us to examine contraction and elongation of fibres in different m e d i a - - v a c u u m , inert atmosphere, air etc.
The fact t h a t these effects can be measured continuously with a gradual increase in temperature enables us to study process kineties. I f necessary, this process can also be investigated at constant temperature and stress of fibre specimens. I n parallel with the study of deformation processes, the apparatus proposed enables us to analyse breakdown products of fibrous materials and study kinetics of breakdown, since it can easily be joined to the inlet system of the mass-spectrometer or to the chromatograph. The main elements of the apparatus (Fig. 1) are: reactor, in which the specimen is placed, cathetometer for measuring the variation in fibre length during deformation and means of linear temperatur6 variation. The accuracy of measuring the length of specimens was
o.o17o.
6! [
z!
z!
0g
80
/zg
/$g
200
160 j r - ~
zso
J$0
l/gg
:'c
& /g
/$
Jg
FIo. 2. Relation between temperature and deformation of cellulose hydrate (1) and polyacrylonitrile fibres (2). R a t e of increasing temperature: 6 deg/min. The reactor, of quartz glass 25 ram diameter, is joined to the v a c u u m system by a thin section. A heating spiral is wound on its surface in the middle part of the reactor. The length of the heated part of the reactor is selected to ensure even temperature distribution along the entire zone in which the specimen is placed. Temperature is controlled by a thermocouple placed in a container and recorded using a K S P potentiometer. The thermocouple can be m o v ed in the container and its junction held at any point of the heated zone.
1892
A. T. K A L A S m ~ e$ a/.
The fibre specimen 5 cm in length is fixed on a support b y a.clamp. The support consists of two parts: the upper unheated p a r t - - of soft wire and the lower one, which is in the heated zone, of quartz glass. The upper wire part makes it possible te raise a n d secure the specimen above the heating zone before the experiment, or lower it with a wrench, which is in the upper removable part of the reactor. The lower par~ of the support is made of quartz glass as a material with low coefficient of linear expansion and consequently, not involving considerable error in fibre contraction. The arm is of a length which enables us to place the specimen in the middle of the heated zone. I f necessary, the specimen can be removed from the heating zone b y the wrench at a n y stage of the experiment without disturbing the hermetic sealing of the vacuum system. A quartz arm with hooks at both ends is fastened to the lower end of the specimen. This arm is intended to keep the fibre in a straightened condition. There is a marking in its lower part in order to take a reading of the length variation of the specimen by a cathetometer. When deformation effects taking place in the fibre are studied under stress, the lower part of the specimen is secured in a clamp and a support suspended on it, to which loads of different magnitudes are attached outside the heating zone. Linear temperature variation takes place using a device which alters the voltage of electric current. The rate of heating can be regulated b y applying different initial voltages. We do not here describe the device since systems of linear temperature variation are widely known and a n y of them can be used for the case described. Relevant experimental data are given as examples for cellulose hydrate and polyacrylonitrile fibres. Figure 2 shows t h a t after a slight contraction of the fibre in the temperature range of 200-300 ° spontaneous elongation takes place, followed b y marked contraction reaching 20 ~o of the initial length. Since both types of deformation of the specimen are spontaneous and are determined b y kinetic process conditions, the position of the m a x i m u m on curve 1 (Fig. 2) can be explained b y simultaneous thermal reactions in this temperature range of the breakdown of cellulose hydrate molecules, during which the polymer material undergoes specific chemical flow (elongation of the specimen) a n d b y structural conversions, resulting in increased packing density of the polymer and corresponding contraction of material volume (contraction of the specimen). An increase during pyrolysis in deformation of flow (elongation) of the specimen above a certain limit would result in the decomposition of cellulose hydrate fibre, therefore, the optimum on the thermo-relaxation curve m a y be a criterion of the efficiency of pyrolysis under given conditions. The deformation curve for a polyacrylonitrile fibre (Fig. 2, curve 2) is entirely different. Here, starting from 60 ° the fibre undergoes shrinkage which is complete at 280 °, then in the range of 280-360 ° the length of the specimen remains unchanged a n d finally, above 360 °, sudden elongation takes place which is due to chemical changes of the polymer in the fibre.
CONCLUSIONS (1) Methods were proposed for the study of deformation taking place in threads and fibres during heating to 1000% temperature being raised in a linear manner at different rates. The methods enable us to examine simultaneously deformation and chemical processes and analyse products of decomposition. (2) Relevant experimental results are given for cellulose hydrate and polyacrylonitrile fibres when heated to 400 ° .
Translated by E. SE~n~RE
Anatolii Petrovich Aleksandrov
1893
I~EFERI:NCES 1. Yu. M. MALINSKII, V. V. GUZEYEV, Yu. A. ZUBOV and V. A. KARGIN, Vysokomol. soyed. 6: 1116, 1964 (Translated in Polymer Sci. U.S.S.R. 6: 6, 1228, 1964) 2. R. I. FEL'DMAN, Kolloidn. zh. 20: 220, 1958 3. P. V. KOZLOV, I. F. KAIMIN' and V. A. KARGIN, Dokl. A. N. SSSR, 167:1 321, 1960 4. Yu. N. POLYAKOV, Khimich. volokna, No. 3, 51, 1971
ANATOLH PETROVICH ALEKSANDROV (On his 70th birthday) ACAnE~IICIAN Anatolii 1)etrovich Aleksandrov, one of the most eminent Soviet physicists celebrated his 70th birthday on 13th February, 1973. A. 1). Aleksandrov was born in Tarasheh in tile Kiev region. After completing secondary school in Kiev he worked first as an electrician and then as a teacher. A. P. Aleksandrov combined his work with studies at the physico-mathematieal faculty of Kiev University, which he completed in 1930. As a student in 1929 he wrote his first scientific paper at the Roentgen Institute. On being acquainted with this study A. I. Ioffe invited A. P. Aleksandrov in 1930 to work in the Leningrad Physico-Tectmical Institute. Among a very strong group of physicists in this Institute A. P. Aleksandrov within a short time proved to be one of the most talented and active young scientists. I n his first series of studies in the field of disruptive discharge of thin l~yers of dielectrics, which shows considerable experimental skill, he demonstrated the special role of so-called "weak points" in disruptive discharge and by revealing the errors of theoretical ideas developed at that time, he played a prominent role in the development of physics of dielectrics. The concept of weak points was also very fruitful in studies dealing with relations of decomposition of solids carried out b y a colleague of Anatolii Petrovich-- S. N. Zhurkov. They j ohltly developed the statistical theory of brittle strength and achieved experimental substantiation. This theory which is described in the mongraph entitled "Brittle Fracture" (1933) is also of significance for the modern physics theory of durability of materials, including polymers. A. P. Aleksan(h'ov was one of the founders of polymer physics. Papers by }). P. I~obeko, A. P. Aleksandrov, Ya. I. Frcnkel', V. A. Kargin et al. described (still in the middle thirties) the main ideas which determined the development in the U.S.S.R. of polymer mechanics a n d physics and which also greatly aff(~cted foreign investigations. Dealing with physics of dielectrics A. 1). Aleksandrov, still in 1933, with an insight typical of him was concerned with the outstanding electric properties of polystyrene, which in those days was an unusual material synthesized by chemists and now is widely used in high-frcquency techniques. A. P. Aleksandrov carried out intensive studies of electrical and mechanical properties of polystyrene to confirm the great tcclmical importance of this polymer, establish relations of deformation and develop numerous ways to improve its properties. Subsequent experimental and theoretical development of this trend led A. P. Aleksan* Vysokomol. soyed. AI5: No. 7, 1683-1684, 1973.
1889
where R is the universal gas constant, w h i c h is 1.987 cal/mole,deg, a n d C--the scale ratio y/x. The value of k was calculated for a n y temperature from the expression k =
-
(dc/dt)lo"
and agreement with the Arrhenius equation verified from the linearity of the diagram plotted in coordinates y = l o g k a n d x = 103/T (Fig. 3). The Table indicates t h a t kinetic parameters calculated b y this method show satisfactory agreement with results of isothermal analysis (ITA) derived b y the authors and available in the literature [4].
CONCLUSIONS B y polyesterification of adipic acid and diethylene glycol it was shown experimentally t h a t kinetic parameters of polyeondensation can he calculated from results of dynamic thermochemical analysis.
TranslaSed by E. SEM'ERE REFERENCES 1. V. P. RYBACHUK and S. I. O M E I . ' C ~ . N K 0 , Vysokomol. soyed. A13: 220, 1971 (Translat e d in P o l y m e r Sci. U.S.S.R. 18: 1,252, 1971) 2. V. P. RYBACHUK, S. I. 0 M E L ' C ~ 0 and K. A. KORNEV, Dokl. A N Ukr.SSR, set. B., 340, 1971 3. E. S. FREEMAN and B. CARROLL, J. Phys. Chem. 62: 394, 1958 4. I. VANCHO-SZlKERCSANYI, E. MAKAY-B~DY, E. SZABO-RETHY and P. I:H~SC~HBERG, J. Polymer Sei. 8, A-l: 2861, 1970
METHOD OF CONTINUOUS DETERMINATION OF DEFORMATION AND CHEMICAL CHANGES IN FIBRES OVER A WIDE RANGE OF TEMPERATURE AND STRESS* A. T. KALASHNIK,L. G. Kuzx~.TSOVA, I. N. Alq'DREYEVA and N. V. MJ:K~AmOV (dec.) All-Union Scientific Research I n s t i t u t e for Synthetic Fibres
(Received 19 May 1972) IN addition to reversible processes, irreversible processes resulting in a change in physical and mechanical properties m a y take place in fibres when heated. By studing these processes valuable information m a y be obtained concerning the t y p e of d e f o r m a t i o n effects a n d their dependence on t e m p e r a t u r e and other experimental conditions, which enables us to determine conditions of h e a t t r e a t m e n t developing fibres with the requisite properties and help to establish t h e relation between initial structure a n d the chemical behaviour of fibres during the s t u d y of pyrolytic processes. * Vysokomol. soyed. A15: No. 7, 1680-1682, 1973.
1890
A. T. KALASHNIX et al.
The methods described for studying deformation effects in polymers during heating [1-4] eua bled us to make observations at comparatively low temperatures (up to the initial decomposition of the polymer), but it was impossible to examine the behaviour of polymers in vacuum and various media with the simultaneous study of chemical and deforanation processes and analysis of breakdown products.
Fie. 1. Layout of the device used for the continuous determination of deformation and chemical processes in fibres: / - - l o a d , 2 - - m a r k , 3--lower quartz support, 4 - clamps, 5 - heating spiral, 6 - container for the thermoeouple, 7--fibre specimen, 8"thermoeouple, 9--reactor, / 0 - - u p p e r support, 1 1 - - t h i n section, 12--wrench, 13--detachable part of the reactor, 1 4 - - t h i n section for connection to the vacuum device or the: device used for the analysis of volatile products. To study those processes in polymers during heating, we proposed a method of conti. nuous measurement of deformations in fibres with a constant linear increase from room
Deformation and chemical changes in fibres
1891
temperature to any given temperature up to 1000 °. The m e t h o d enables us to examine contraction and elongation of fibres in different m e d i a - - v a c u u m , inert atmosphere, air etc.
The fact t h a t these effects can be measured continuously with a gradual increase in temperature enables us to study process kineties. I f necessary, this process can also be investigated at constant temperature and stress of fibre specimens. I n parallel with the study of deformation processes, the apparatus proposed enables us to analyse breakdown products of fibrous materials and study kinetics of breakdown, since it can easily be joined to the inlet system of the mass-spectrometer or to the chromatograph. The main elements of the apparatus (Fig. 1) are: reactor, in which the specimen is placed, cathetometer for measuring the variation in fibre length during deformation and means of linear temperatur6 variation. The accuracy of measuring the length of specimens was
o.o17o.
6! [
z!
z!
0g
80
/zg
/$g
200
160 j r - ~
zso
J$0
l/gg
:'c
& /g
/$
Jg
FIo. 2. Relation between temperature and deformation of cellulose hydrate (1) and polyacrylonitrile fibres (2). R a t e of increasing temperature: 6 deg/min. The reactor, of quartz glass 25 ram diameter, is joined to the v a c u u m system by a thin section. A heating spiral is wound on its surface in the middle part of the reactor. The length of the heated part of the reactor is selected to ensure even temperature distribution along the entire zone in which the specimen is placed. Temperature is controlled by a thermocouple placed in a container and recorded using a K S P potentiometer. The thermocouple can be m o v ed in the container and its junction held at any point of the heated zone.
1892
A. T. K A L A S m ~ e$ a/.
The fibre specimen 5 cm in length is fixed on a support b y a.clamp. The support consists of two parts: the upper unheated p a r t - - of soft wire and the lower one, which is in the heated zone, of quartz glass. The upper wire part makes it possible te raise a n d secure the specimen above the heating zone before the experiment, or lower it with a wrench, which is in the upper removable part of the reactor. The lower par~ of the support is made of quartz glass as a material with low coefficient of linear expansion and consequently, not involving considerable error in fibre contraction. The arm is of a length which enables us to place the specimen in the middle of the heated zone. I f necessary, the specimen can be removed from the heating zone b y the wrench at a n y stage of the experiment without disturbing the hermetic sealing of the vacuum system. A quartz arm with hooks at both ends is fastened to the lower end of the specimen. This arm is intended to keep the fibre in a straightened condition. There is a marking in its lower part in order to take a reading of the length variation of the specimen by a cathetometer. When deformation effects taking place in the fibre are studied under stress, the lower part of the specimen is secured in a clamp and a support suspended on it, to which loads of different magnitudes are attached outside the heating zone. Linear temperature variation takes place using a device which alters the voltage of electric current. The rate of heating can be regulated b y applying different initial voltages. We do not here describe the device since systems of linear temperature variation are widely known and a n y of them can be used for the case described. Relevant experimental data are given as examples for cellulose hydrate and polyacrylonitrile fibres. Figure 2 shows t h a t after a slight contraction of the fibre in the temperature range of 200-300 ° spontaneous elongation takes place, followed b y marked contraction reaching 20 ~o of the initial length. Since both types of deformation of the specimen are spontaneous and are determined b y kinetic process conditions, the position of the m a x i m u m on curve 1 (Fig. 2) can be explained b y simultaneous thermal reactions in this temperature range of the breakdown of cellulose hydrate molecules, during which the polymer material undergoes specific chemical flow (elongation of the specimen) a n d b y structural conversions, resulting in increased packing density of the polymer and corresponding contraction of material volume (contraction of the specimen). An increase during pyrolysis in deformation of flow (elongation) of the specimen above a certain limit would result in the decomposition of cellulose hydrate fibre, therefore, the optimum on the thermo-relaxation curve m a y be a criterion of the efficiency of pyrolysis under given conditions. The deformation curve for a polyacrylonitrile fibre (Fig. 2, curve 2) is entirely different. Here, starting from 60 ° the fibre undergoes shrinkage which is complete at 280 °, then in the range of 280-360 ° the length of the specimen remains unchanged a n d finally, above 360 °, sudden elongation takes place which is due to chemical changes of the polymer in the fibre.
CONCLUSIONS (1) Methods were proposed for the study of deformation taking place in threads and fibres during heating to 1000% temperature being raised in a linear manner at different rates. The methods enable us to examine simultaneously deformation and chemical processes and analyse products of decomposition. (2) Relevant experimental results are given for cellulose hydrate and polyacrylonitrile fibres when heated to 400 ° .
Translated by E. SE~n~RE
Anatolii Petrovich Aleksandrov
1893
I~EFERI:NCES 1. Yu. M. MALINSKII, V. V. GUZEYEV, Yu. A. ZUBOV and V. A. KARGIN, Vysokomol. soyed. 6: 1116, 1964 (Translated in Polymer Sci. U.S.S.R. 6: 6, 1228, 1964) 2. R. I. FEL'DMAN, Kolloidn. zh. 20: 220, 1958 3. P. V. KOZLOV, I. F. KAIMIN' and V. A. KARGIN, Dokl. A. N. SSSR, 167:1 321, 1960 4. Yu. N. POLYAKOV, Khimich. volokna, No. 3, 51, 1971
ANATOLH PETROVICH ALEKSANDROV (On his 70th birthday) ACAnE~IICIAN Anatolii 1)etrovich Aleksandrov, one of the most eminent Soviet physicists celebrated his 70th birthday on 13th February, 1973. A. 1). Aleksandrov was born in Tarasheh in tile Kiev region. After completing secondary school in Kiev he worked first as an electrician and then as a teacher. A. P. Aleksandrov combined his work with studies at the physico-mathematieal faculty of Kiev University, which he completed in 1930. As a student in 1929 he wrote his first scientific paper at the Roentgen Institute. On being acquainted with this study A. I. Ioffe invited A. P. Aleksandrov in 1930 to work in the Leningrad Physico-Tectmical Institute. Among a very strong group of physicists in this Institute A. P. Aleksandrov within a short time proved to be one of the most talented and active young scientists. I n his first series of studies in the field of disruptive discharge of thin l~yers of dielectrics, which shows considerable experimental skill, he demonstrated the special role of so-called "weak points" in disruptive discharge and by revealing the errors of theoretical ideas developed at that time, he played a prominent role in the development of physics of dielectrics. The concept of weak points was also very fruitful in studies dealing with relations of decomposition of solids carried out b y a colleague of Anatolii Petrovich-- S. N. Zhurkov. They j ohltly developed the statistical theory of brittle strength and achieved experimental substantiation. This theory which is described in the mongraph entitled "Brittle Fracture" (1933) is also of significance for the modern physics theory of durability of materials, including polymers. A. P. Aleksan(h'ov was one of the founders of polymer physics. Papers by }). P. I~obeko, A. P. Aleksandrov, Ya. I. Frcnkel', V. A. Kargin et al. described (still in the middle thirties) the main ideas which determined the development in the U.S.S.R. of polymer mechanics a n d physics and which also greatly aff(~cted foreign investigations. Dealing with physics of dielectrics A. 1). Aleksandrov, still in 1933, with an insight typical of him was concerned with the outstanding electric properties of polystyrene, which in those days was an unusual material synthesized by chemists and now is widely used in high-frcquency techniques. A. P. Aleksandrov carried out intensive studies of electrical and mechanical properties of polystyrene to confirm the great tcclmical importance of this polymer, establish relations of deformation and develop numerous ways to improve its properties. Subsequent experimental and theoretical development of this trend led A. P. Aleksan* Vysokomol. soyed. AI5: No. 7, 1683-1684, 1973.