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Kinetics of inhibition of radical polymerization—VII. Effect of halogenated quinones on the initiated polymerization of styrene
204
Abstracts
effects, a reversible transition takes place in the process of thermal expansion of protein solus, characterized by change in the temperature dependence of the expansion coefficient (in the range 33-37 °) and not directly connected with gelatinization. ADHESION OF POLYTETRAFLUOROETHYLENE TO METALS
A. Y a .
K o r o l e v , V. I. B e k a n d N. A. G r i s h i n , V y s o k o m o l . s o y e d . 4: No.
9,
1 4 1 1 - 1 4 1 8 , 1962. IT HAS been shown that polytetrafluoroethylene m a y be used as cement for metals. The cementing is carried out by heating the metal specimens with an interlayer of the polymer to 420-430 ° and cooling. The strength of the joints has been shown to equal 1000-1500 g/cm o n separation into layers and 130-150 kg/cm on normal pull and on shear. A very high strength of the joints reaching a value of 100 kg/cm has been observed on non-uniform pull. Conditions for the formation of a strong adhesion bond at the metal-polytetrafluoroethylene interface have been examined a n d a discussion has been made on the nature of the forces participating in the formation of this bond. THERMAL PROPERTIES OF GELATIN SOLUTIONS
T . V. B u r d z h a n a d z e , P. L. P r i v a l o v a n d N. N. T a v k h e l i d z e , V y s o k o m o l . s o y e d . 4: N o . 9, 1 4 1 9 - 1 4 2 4 , 1962. THE heat capacity of gelatin solutions of varying concentrations has been investigated from 0 to 60 °. The melting process of gelatin gels has been shown to be complex, involving a n u m b e r of separate stages. The addition of 5 M urea completely eliminates all heat absor~ption peaks, making the curve c=f(t) parallel to that for dry gelatin. The heat capacity of gelatin solutions over the entire temperature range investigated is not an additive function of the heat capacities of the constituents. KINETICS OF INHIBITION OF RADICAL POLYMERIZATION--.VI. EFFECT OF P-XYLOQUINONE ON THE INITIATED POLYMERIZATION OF STYRENE
F . T i i d S s a n d L. S i m £ n d i , V y s o k o m o l . s o y e d . 4: No. 9, 1 4 2 5 - 1 4 3 0 , 1962. THE effect of p-xyloquinone on the initiated polymerization of styrene at 40 ° and 60 o has been investigated. The elementary inhibition reaction has been found to be of zero activation energy. At the same time the frequency factor is very low (log A s = 5"04~ 0"31). Hence, inhibition is a non-adiabatic reaction, the transmission coefficient of which is of low value. An approximate calculation was made of the heat effect of the inhibition reaction for the principal compound p-benzoquinone and the reaction was found to be exothermic at least by 10 kcal. The value of the stoichiometric coefficient is independent of the temperature. KINETICS OF INHIBITION OF RADICAL POLYMERIZATION--VII. EFFECT OF HALOGENATED QUINONES ON THE INITIATED POLYMERIZATION OF STYRENE
F . T i i d 6 s , L. S i m £ n d i a n d M. Azori, V y s o k o m o l . s o y e d . 4: No. 9, 1 4 3 1 - 1 4 4 4 , 1962. THE behaviour of six halogenated quinones in the initiated polymerization of styrene has been investigated. I t has been found that considerable chain regeneration occurs in the presence of chloroquinones, the process augmenting with increase in the number of chlorine atoms in the quinone molecule. Kinetic equations have been derived, based on a detailed analysis of the process. Experimental data are in excellent agreement with the theoretical expressions. I t was found that the hulogenoquinines form molecular compounds with
Abstracts
205
styrene in the ratio 1 : 1. On the basis of these findings, a model of the chain-regeneration mechanism has been developed. The complex augments to a considerable extent the reactivity of the quinones; this can be ascribed to an increase in the transmission coefficient. The stoichiometric coefficient, as in the previous studies, is not a trivial q u a n t i t y and diminishes with increase in number and size of the substituents. ESTIMATION OF T H E MICROTACTICITY OF P O L Y M E R CHAINS F R O M T H E P E R A T U R E D E P E N D E N C E OF T H E I R DIMENSIONS (Letter to the Editor)
TEM-
O. B. P t i t s y n , V y s o k o m o l . s o e y d . 4: N o . 9, 1 4 4 5 - 1 4 4 6 , 1962. THE theory of the mean dimensions and dipole moments of stereoregular polymer chains ( - - C H 2 - - C H R - - ) ~ , developed by T. M. Birshtein and the author, predicts quite different conformations for isotactic and syndiotactie molecules of this type in solution. I t does not contradict similarity of dimensions of isotactic and ataetic molecules of polystyrene and polypropylene but indicates a considerable difference in the t e m p e r a t u r e dependence of their dimensions. The theory predicts that for isotactic polystyrene (d In ho/d In T) ~ -- 1 and for syndiotactic polystyrene ( d l n h0/dln T)_~0. Experimental data for the atactie polystyrene show that (d In h2/d In T) ~ --0"5 which means that it consists of c o m m e n s u r a t e numbers of isotactically and syndiotactieally bound m o n o m er units. This result corresponds to the theoretical prediction that non-polar sterie intramolecular interactions do not contribute velW much to the stereospeeific influence of the end of the growing polymer chain.
Tile Publisher will be pleased to quote for the supply of a full English translation of any paper abstracted in these pages.
Abstracts
effects, a reversible transition takes place in the process of thermal expansion of protein solus, characterized by change in the temperature dependence of the expansion coefficient (in the range 33-37 °) and not directly connected with gelatinization. ADHESION OF POLYTETRAFLUOROETHYLENE TO METALS
A. Y a .
K o r o l e v , V. I. B e k a n d N. A. G r i s h i n , V y s o k o m o l . s o y e d . 4: No.
9,
1 4 1 1 - 1 4 1 8 , 1962. IT HAS been shown that polytetrafluoroethylene m a y be used as cement for metals. The cementing is carried out by heating the metal specimens with an interlayer of the polymer to 420-430 ° and cooling. The strength of the joints has been shown to equal 1000-1500 g/cm o n separation into layers and 130-150 kg/cm on normal pull and on shear. A very high strength of the joints reaching a value of 100 kg/cm has been observed on non-uniform pull. Conditions for the formation of a strong adhesion bond at the metal-polytetrafluoroethylene interface have been examined a n d a discussion has been made on the nature of the forces participating in the formation of this bond. THERMAL PROPERTIES OF GELATIN SOLUTIONS
T . V. B u r d z h a n a d z e , P. L. P r i v a l o v a n d N. N. T a v k h e l i d z e , V y s o k o m o l . s o y e d . 4: N o . 9, 1 4 1 9 - 1 4 2 4 , 1962. THE heat capacity of gelatin solutions of varying concentrations has been investigated from 0 to 60 °. The melting process of gelatin gels has been shown to be complex, involving a n u m b e r of separate stages. The addition of 5 M urea completely eliminates all heat absor~ption peaks, making the curve c=f(t) parallel to that for dry gelatin. The heat capacity of gelatin solutions over the entire temperature range investigated is not an additive function of the heat capacities of the constituents. KINETICS OF INHIBITION OF RADICAL POLYMERIZATION--.VI. EFFECT OF P-XYLOQUINONE ON THE INITIATED POLYMERIZATION OF STYRENE
F . T i i d S s a n d L. S i m £ n d i , V y s o k o m o l . s o y e d . 4: No. 9, 1 4 2 5 - 1 4 3 0 , 1962. THE effect of p-xyloquinone on the initiated polymerization of styrene at 40 ° and 60 o has been investigated. The elementary inhibition reaction has been found to be of zero activation energy. At the same time the frequency factor is very low (log A s = 5"04~ 0"31). Hence, inhibition is a non-adiabatic reaction, the transmission coefficient of which is of low value. An approximate calculation was made of the heat effect of the inhibition reaction for the principal compound p-benzoquinone and the reaction was found to be exothermic at least by 10 kcal. The value of the stoichiometric coefficient is independent of the temperature. KINETICS OF INHIBITION OF RADICAL POLYMERIZATION--VII. EFFECT OF HALOGENATED QUINONES ON THE INITIATED POLYMERIZATION OF STYRENE
F . T i i d 6 s , L. S i m £ n d i a n d M. Azori, V y s o k o m o l . s o y e d . 4: No. 9, 1 4 3 1 - 1 4 4 4 , 1962. THE behaviour of six halogenated quinones in the initiated polymerization of styrene has been investigated. I t has been found that considerable chain regeneration occurs in the presence of chloroquinones, the process augmenting with increase in the number of chlorine atoms in the quinone molecule. Kinetic equations have been derived, based on a detailed analysis of the process. Experimental data are in excellent agreement with the theoretical expressions. I t was found that the hulogenoquinines form molecular compounds with
Abstracts
205
styrene in the ratio 1 : 1. On the basis of these findings, a model of the chain-regeneration mechanism has been developed. The complex augments to a considerable extent the reactivity of the quinones; this can be ascribed to an increase in the transmission coefficient. The stoichiometric coefficient, as in the previous studies, is not a trivial q u a n t i t y and diminishes with increase in number and size of the substituents. ESTIMATION OF T H E MICROTACTICITY OF P O L Y M E R CHAINS F R O M T H E P E R A T U R E D E P E N D E N C E OF T H E I R DIMENSIONS (Letter to the Editor)
TEM-
O. B. P t i t s y n , V y s o k o m o l . s o e y d . 4: N o . 9, 1 4 4 5 - 1 4 4 6 , 1962. THE theory of the mean dimensions and dipole moments of stereoregular polymer chains ( - - C H 2 - - C H R - - ) ~ , developed by T. M. Birshtein and the author, predicts quite different conformations for isotactic and syndiotactie molecules of this type in solution. I t does not contradict similarity of dimensions of isotactic and ataetic molecules of polystyrene and polypropylene but indicates a considerable difference in the t e m p e r a t u r e dependence of their dimensions. The theory predicts that for isotactic polystyrene (d In ho/d In T) ~ -- 1 and for syndiotactic polystyrene ( d l n h0/dln T)_~0. Experimental data for the atactie polystyrene show that (d In h2/d In T) ~ --0"5 which means that it consists of c o m m e n s u r a t e numbers of isotactically and syndiotactieally bound m o n o m er units. This result corresponds to the theoretical prediction that non-polar sterie intramolecular interactions do not contribute velW much to the stereospeeific influence of the end of the growing polymer chain.
Tile Publisher will be pleased to quote for the supply of a full English translation of any paper abstracted in these pages.