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Structural changes in a cross-linked polymer caused by an active organosilicon monomer
:1390
G . n . AI~DREYEVSKAYAet a~,
(2) A study has been made of the effect of temperature, nature of initiator and structure of ester radical in ~-methaeryloxyethyldialkyl phosphites, fl-methacryloxyethyldialkyl phosphates and mixed anhydrides of methaerylic and dialky! phosphorous acids on the rate of polymerization and properties of polymers. (3) Phosphorus-containing esters of methaerylic acid of the types indicated have been copolymerized with methylmethacrylate and the properties of the copolymers determined. Transb~ted by E. SEMERE REFERENCES
1. A. N. PUDOVIK, N. G. KHUSAINOVA and E. I. KASHEVAROVA, Vysokomol, soyed. 5, 1376, 1963 2. A. I. PUDOVIK, E. I. KASHEVAROVA and V. M. GORCHAKOVA, Zh. obshch, khimii 84: 2213, 1964 3. A. N. PUDOVIK, E. I. KASHEVAROVA and G. L. GOLOVEN'KIN, Zh. obshch, khimii 34: 3240, 1964 4. G. S. KOLESNIKOV, Ye. F. RODINOVA and G. M. LUK'YANOVA, Izv. AN SSSR, Seriya khimich., 538, 1964
STRUCTURAL CHANGES IN A CROSS-LINKED POLYMER C A U S E D B Y A N ACTIVE 0RGANOSILICON MONOMER* G. I). ANDREYEVSKAYA, YU. A. GORBATKINA, N. B. GUSEVA, B. A. KISELEV A. I. MIKHAL'SKII and V. N. STEPANOVA Institute of Chemical Physics, U.S.S.R. Academy of Sciences
(Received 16 A~j~t 1964) IT WAS shown previously [1, 2] that some organosilicon monomers can modify a reinforced system b y simultaneous interaction both with the material of the polymer binder and with the surface of glass fibres. I t was found in paper [2] that the modification a butvar-phenol polymer with AM-2 amine-containing organosilicon monomer leads to the formation of cross-linked structures having improved physico-mechanical, and higher adhesive properties than the initial polymer. I t was therefore interesting to establish the effect of the relative content in the polymer of an active compound on the physico-mechanical properties of polymers of other types and show the structural changes which take place as a result of modification.
* Vysokomol. soyed. 7: No. 7, 1254~-1257, 1965.
Cro~-!inl~ed. polFmer
~$9g
A VFT polymeric binder was used for the investigation which is a phenolformaldehyde resin of resol type 1 modified by "ViniAex" (polyvinylforma!ethylal) with a ratio of 1.0 : 0.9, respectively, The AM-2 active compound was added to a 20o//oalcoholic~acetone polymer solution in the proportions of 1.3 and 5~o by weight. From the compositions obtained thin films (maximum 15/~ thickness) were made and their mechanical properties tested: tensile strength, tensile elastic modulus and the stress/strain curves i.e. the dependence of deformation on stress at constant rate of deformation. For comparison, films free from the active compound were tested. I n addition, the strength of adhesion to glass fibres of an alkali-free composition was measured for modified and "pure" polymer compositions. Polymerization of films (and also specimens for thermo-mechanical tests and bonding with glass fibres) was carried out by gradually increasing .temperature (over 3 hours) to 180 °, and retention at this temperature for 3 hours. The methods of preparing and testing the films and methods of determining adhesion strength have been described previously [3, 4]. Figure 1 presents the dependence of physico-mechanical properties of VFT polymer films on the relative content of the active AM-2 compound in polymer.
-
/ 0 2 4 6 Amount of AH-2, %
FIG. 1. Depenctence of physico-mechanical properties of ~ T polymer films on the content of active compounds in the polymer: ]--mod, u]us of elasticity; 2 - - t e ~ f l e strength; 3--breaking elongation; 4--adhesive strength to fibres. The tensile strength values (curve 2) and the tensile elastic modulus (curve ]) are plotted along" the ordinate axis (to the left); elongation at break (curve 3) and adhesion strength to glass fibres (curve 4), to the right. Along the abscissa axis is plotted the AM-2 content in the composition (~/o of weight of polymer). Each point on the curves of Fig, 1 which illustrate the variation of mechanical properties of films, represents an arithmetical mean of 10-15 measurements; adhesion strengths were determined as an average of 30-50 tests. The deviation in all the experiments was less than 5-7 ~/o.
| ~92
O . D . ANDREYEVSKAYAet ~ .
From the curves presented in Fig. 1 it can be concludedthat modification of ~ F T polymers b y an organo-silicon monomer increases the modulus of elasticity and strength and proportionally reduces the relative elongation of films; films modified by an active compound in the proportion of 3~/o of polymer weight have the most satisfactory mechanical properties. The mean values of elasticity moduIns and strength of "pure" and modified specimens were 412 and 450 kg/mm 2 and 7.7 and 8.0 kg/mm s, respectively. The relative elongation of modified films decreased compared with the unmodified ones from 2.1 to 1.96°/o. • The increase in the adhesive strength of modified polymers, is due, in all ~robability, to the increased possibility of interaction o f the aminogroups of an organo-silicon monomer with the methylol groups of the phenol component of resin. I t is also possible that, by interaction between the OH-groups contained in the VFT polymer structure and the NH~ groups of the active compound, hydrogen bonds: - - O H . . . l~rI-- are formed. T h e improvement of mechanical properties of films by an active compound is, apparently, due to the fact that, as a result of reactions throughout the whole polymer bulk, denser cross-linked structures are formed. In order t o verify this ~ssumption, a comparative investigation was carried out of the thermo-mechanical behaviour (in a Kargin balance) of modified and unmodified polymer speci~nens and the character of the stress/strain curves studied. Figure 2 shows thermo-mechanical curves obtained by studying the depend° ~nce of deformation on temperature of YFT polymer specimens cured at 180° for 3 hours. When plotting the thermoomechanical curves, a stress of 4.25 kg/cm 3 was applied, for 15 sec; the rate of heating was 45 degrees/hour. The sharp maximum on the thermoomechanical curve of an unmodified polymer is, apparently, due to the fact that during hardening complete polymeriza= ~ion was not achieved and further heating not only resulted in increased mobility o f the separate sections of the structural network but also in formation of addition° ~1 cross-links. At the same time the character of the thermo-mechanical cu~rve ,of modified specimens clearly illustrates the variation of polymer structure under the effect of an active compound: the deformation capacity decreased approximately 6-fold and glass temperature increased from 93-95 ° to 170-180 °. These variations are due to the formation of a denser network, to the increase of the number of cross-links formed during polymer cross-linking into a three-dimensional structure. The thermo-mechanical behaviour of modified and unmodified VFT polymer specimens shows a satisfactory correlation with the curves obtained by plotting the stress/strain curves of films. The stress/strain curves of films, which characterize strain, strength and the moduls of elasticity, were plotted by studying the dependence of deformation on stress at constant rate of deformation of 0.25-0.30~/mlu. To examine the components of total polymer deformation, we determined the dependence of deformation on time during the period of relieving the specimens and established that at room temperature in a VFT
Cross-l~ked p o ~ e z
18S
polymer of cross-llnked structure t h e deformations were practically completely reversible, i.e. were formed of elastic and high-elastic deformations and plastic, irreversible deformations were not detected. Similar results were Obtained in references [2, 3].
~5 ~
,~ &O-
1
I
20
80
140
200 T, °C
0
Fzg. 2
04
I
1.2 5"tpein , %
I
20
F~o. 3
FI6. 2. Thermo-mechanical curves of a modified (2) und unmodified (1) ~TFT polymer. FI6. 3. Stress/strain diagr~m~ of modified (1) and unmodified (2) polymer fllmR. Figure 3 illustrates typical stress/strain diagrams of films which contain 3% active compound (curve 1) and of lmmodified films (curve 2). The linear section on the curve characterizes the modulus of elasticity and the non-linear section, the high-elastic deformations. The steeper rise in the linear section of curve ] (modified films) in the stress/strain diagram, compared with curve 2 (unmodi6ed films), should be attributed to the formation of a denser network. From the study of the thermo-mechanical behaviour and character of curves in the stress/strain curves of modified and unmodified WFT polymer specimens it can thus be concluded t h a t a denser cross-linked structure is formed by the effect of an active compound. CONCLUSIONS
(l) I t was shown t h a t the addition of a small number of amine-containing organo-silicon monomers to a VFT polymer composition leads to structural modification and to the formation of cross-linked polymers with a greater density of cross-lintts t h a n in the initial polymer. This was established b y the study of the thermo-mechanical behaviou~ and nature of the stress/strain curves for modified and unmodified polymers. (2) Modification of the VFT polymer binder with an active monomer also causes increased adhesion to the surface of glass fibres. T randated by E. SEZ~'gl~3¢
,150~
V.N. SOEOLOVet ~ .
REFERENCES 1. ]3. A. KISELEV, Plast. massy 8: 36, 1963 2. Yu. A: GORRATKINA, N. B. GUSEVA, G. D. ANDREYEVSKAYA and G. S. GALA.
KHOVA, Vysokomol. soyed. 6: 1911, 1964 3. A. L. RABINOVICH, Vysokomol. soyed. 1: 998, 1959 4, G. V. SHIRYAEVA, Yu. A. GORBATKINA and G. D. ANDREYEVSKAYA, Zh. fiz. khimii 37: 237, 1963
THE ROLE OF WATER IN THE SYNTHESIS OF URETHANE POLYMERS FROM POLYESTERS* V. N. SOKOLOV, L. YA. RAPPOPORT, I. YA, PODDUB~Y'I and N. P. APUKHTINA S. V. Lebedev Scientific Research Inst. qf Synthetic l~ubber (Receive~ 16 August 1964) AS IS well known, water can react with various compounds containing isocyanate groups and is therefore Of great importance in the Synthesis of urethane polymers [1]. From a stud ~ of the reaction of water with mono-isocyanates, a scheme was proposed according to which the reactions take place in two stages: 1) amine formation and 2) interaction of the amine o b t a i n e d with isocyanate, as a result of which symmetric di-N-substituted urea is formed. In fact, the interaction of water with isocyanates, apparently, takes place according to a much more complex system, b y the formation of numerous unstable intermediate products
[2, 3]. In the case of asymmetrical di-isocyanates, water firstly reacts with the most reactive isocyanate groups: thus, for example, during the interaction of telinyl-2,4-di-isocyanate (2,4-TDC) with water, the isocyanate group which is in the p-position in relation t o the methyl group, takes part in the reaction, whereas the less active o-NCO-group does not react, under certain conditions. In addition, the formation of an electropositiv.e urea group reduces the reactivit y of free isocyanate groups even more [4, 5]. The reaction of water with isocyanates depends to a considerable extent on the medium in which the reaction occurs and firstly on the solubility of the components [6]. As far as the reactions of water are concerned during the synthesis of urethane polymers, they have been very little investigated and the literature available refers to polyurethane foams. * Vysokomol. soyed. 7. No. 7, 1258-1263, 1965
G . n . AI~DREYEVSKAYAet a~,
(2) A study has been made of the effect of temperature, nature of initiator and structure of ester radical in ~-methaeryloxyethyldialkyl phosphites, fl-methacryloxyethyldialkyl phosphates and mixed anhydrides of methaerylic and dialky! phosphorous acids on the rate of polymerization and properties of polymers. (3) Phosphorus-containing esters of methaerylic acid of the types indicated have been copolymerized with methylmethacrylate and the properties of the copolymers determined. Transb~ted by E. SEMERE REFERENCES
1. A. N. PUDOVIK, N. G. KHUSAINOVA and E. I. KASHEVAROVA, Vysokomol, soyed. 5, 1376, 1963 2. A. I. PUDOVIK, E. I. KASHEVAROVA and V. M. GORCHAKOVA, Zh. obshch, khimii 84: 2213, 1964 3. A. N. PUDOVIK, E. I. KASHEVAROVA and G. L. GOLOVEN'KIN, Zh. obshch, khimii 34: 3240, 1964 4. G. S. KOLESNIKOV, Ye. F. RODINOVA and G. M. LUK'YANOVA, Izv. AN SSSR, Seriya khimich., 538, 1964
STRUCTURAL CHANGES IN A CROSS-LINKED POLYMER C A U S E D B Y A N ACTIVE 0RGANOSILICON MONOMER* G. I). ANDREYEVSKAYA, YU. A. GORBATKINA, N. B. GUSEVA, B. A. KISELEV A. I. MIKHAL'SKII and V. N. STEPANOVA Institute of Chemical Physics, U.S.S.R. Academy of Sciences
(Received 16 A~j~t 1964) IT WAS shown previously [1, 2] that some organosilicon monomers can modify a reinforced system b y simultaneous interaction both with the material of the polymer binder and with the surface of glass fibres. I t was found in paper [2] that the modification a butvar-phenol polymer with AM-2 amine-containing organosilicon monomer leads to the formation of cross-linked structures having improved physico-mechanical, and higher adhesive properties than the initial polymer. I t was therefore interesting to establish the effect of the relative content in the polymer of an active compound on the physico-mechanical properties of polymers of other types and show the structural changes which take place as a result of modification.
* Vysokomol. soyed. 7: No. 7, 1254~-1257, 1965.
Cro~-!inl~ed. polFmer
~$9g
A VFT polymeric binder was used for the investigation which is a phenolformaldehyde resin of resol type 1 modified by "ViniAex" (polyvinylforma!ethylal) with a ratio of 1.0 : 0.9, respectively, The AM-2 active compound was added to a 20o//oalcoholic~acetone polymer solution in the proportions of 1.3 and 5~o by weight. From the compositions obtained thin films (maximum 15/~ thickness) were made and their mechanical properties tested: tensile strength, tensile elastic modulus and the stress/strain curves i.e. the dependence of deformation on stress at constant rate of deformation. For comparison, films free from the active compound were tested. I n addition, the strength of adhesion to glass fibres of an alkali-free composition was measured for modified and "pure" polymer compositions. Polymerization of films (and also specimens for thermo-mechanical tests and bonding with glass fibres) was carried out by gradually increasing .temperature (over 3 hours) to 180 °, and retention at this temperature for 3 hours. The methods of preparing and testing the films and methods of determining adhesion strength have been described previously [3, 4]. Figure 1 presents the dependence of physico-mechanical properties of VFT polymer films on the relative content of the active AM-2 compound in polymer.
-
/ 0 2 4 6 Amount of AH-2, %
FIG. 1. Depenctence of physico-mechanical properties of ~ T polymer films on the content of active compounds in the polymer: ]--mod, u]us of elasticity; 2 - - t e ~ f l e strength; 3--breaking elongation; 4--adhesive strength to fibres. The tensile strength values (curve 2) and the tensile elastic modulus (curve ]) are plotted along" the ordinate axis (to the left); elongation at break (curve 3) and adhesion strength to glass fibres (curve 4), to the right. Along the abscissa axis is plotted the AM-2 content in the composition (~/o of weight of polymer). Each point on the curves of Fig, 1 which illustrate the variation of mechanical properties of films, represents an arithmetical mean of 10-15 measurements; adhesion strengths were determined as an average of 30-50 tests. The deviation in all the experiments was less than 5-7 ~/o.
| ~92
O . D . ANDREYEVSKAYAet ~ .
From the curves presented in Fig. 1 it can be concludedthat modification of ~ F T polymers b y an organo-silicon monomer increases the modulus of elasticity and strength and proportionally reduces the relative elongation of films; films modified by an active compound in the proportion of 3~/o of polymer weight have the most satisfactory mechanical properties. The mean values of elasticity moduIns and strength of "pure" and modified specimens were 412 and 450 kg/mm 2 and 7.7 and 8.0 kg/mm s, respectively. The relative elongation of modified films decreased compared with the unmodified ones from 2.1 to 1.96°/o. • The increase in the adhesive strength of modified polymers, is due, in all ~robability, to the increased possibility of interaction o f the aminogroups of an organo-silicon monomer with the methylol groups of the phenol component of resin. I t is also possible that, by interaction between the OH-groups contained in the VFT polymer structure and the NH~ groups of the active compound, hydrogen bonds: - - O H . . . l~rI-- are formed. T h e improvement of mechanical properties of films by an active compound is, apparently, due to the fact that, as a result of reactions throughout the whole polymer bulk, denser cross-linked structures are formed. In order t o verify this ~ssumption, a comparative investigation was carried out of the thermo-mechanical behaviour (in a Kargin balance) of modified and unmodified polymer speci~nens and the character of the stress/strain curves studied. Figure 2 shows thermo-mechanical curves obtained by studying the depend° ~nce of deformation on temperature of YFT polymer specimens cured at 180° for 3 hours. When plotting the thermoomechanical curves, a stress of 4.25 kg/cm 3 was applied, for 15 sec; the rate of heating was 45 degrees/hour. The sharp maximum on the thermoomechanical curve of an unmodified polymer is, apparently, due to the fact that during hardening complete polymeriza= ~ion was not achieved and further heating not only resulted in increased mobility o f the separate sections of the structural network but also in formation of addition° ~1 cross-links. At the same time the character of the thermo-mechanical cu~rve ,of modified specimens clearly illustrates the variation of polymer structure under the effect of an active compound: the deformation capacity decreased approximately 6-fold and glass temperature increased from 93-95 ° to 170-180 °. These variations are due to the formation of a denser network, to the increase of the number of cross-links formed during polymer cross-linking into a three-dimensional structure. The thermo-mechanical behaviour of modified and unmodified VFT polymer specimens shows a satisfactory correlation with the curves obtained by plotting the stress/strain curves of films. The stress/strain curves of films, which characterize strain, strength and the moduls of elasticity, were plotted by studying the dependence of deformation on stress at constant rate of deformation of 0.25-0.30~/mlu. To examine the components of total polymer deformation, we determined the dependence of deformation on time during the period of relieving the specimens and established that at room temperature in a VFT
Cross-l~ked p o ~ e z
18S
polymer of cross-llnked structure t h e deformations were practically completely reversible, i.e. were formed of elastic and high-elastic deformations and plastic, irreversible deformations were not detected. Similar results were Obtained in references [2, 3].
~5 ~
,~ &O-
1
I
20
80
140
200 T, °C
0
Fzg. 2
04
I
1.2 5"tpein , %
I
20
F~o. 3
FI6. 2. Thermo-mechanical curves of a modified (2) und unmodified (1) ~TFT polymer. FI6. 3. Stress/strain diagr~m~ of modified (1) and unmodified (2) polymer fllmR. Figure 3 illustrates typical stress/strain diagrams of films which contain 3% active compound (curve 1) and of lmmodified films (curve 2). The linear section on the curve characterizes the modulus of elasticity and the non-linear section, the high-elastic deformations. The steeper rise in the linear section of curve ] (modified films) in the stress/strain diagram, compared with curve 2 (unmodi6ed films), should be attributed to the formation of a denser network. From the study of the thermo-mechanical behaviour and character of curves in the stress/strain curves of modified and unmodified WFT polymer specimens it can thus be concluded t h a t a denser cross-linked structure is formed by the effect of an active compound. CONCLUSIONS
(l) I t was shown t h a t the addition of a small number of amine-containing organo-silicon monomers to a VFT polymer composition leads to structural modification and to the formation of cross-linked polymers with a greater density of cross-lintts t h a n in the initial polymer. This was established b y the study of the thermo-mechanical behaviou~ and nature of the stress/strain curves for modified and unmodified polymers. (2) Modification of the VFT polymer binder with an active monomer also causes increased adhesion to the surface of glass fibres. T randated by E. SEZ~'gl~3¢
,150~
V.N. SOEOLOVet ~ .
REFERENCES 1. ]3. A. KISELEV, Plast. massy 8: 36, 1963 2. Yu. A: GORRATKINA, N. B. GUSEVA, G. D. ANDREYEVSKAYA and G. S. GALA.
KHOVA, Vysokomol. soyed. 6: 1911, 1964 3. A. L. RABINOVICH, Vysokomol. soyed. 1: 998, 1959 4, G. V. SHIRYAEVA, Yu. A. GORBATKINA and G. D. ANDREYEVSKAYA, Zh. fiz. khimii 37: 237, 1963
THE ROLE OF WATER IN THE SYNTHESIS OF URETHANE POLYMERS FROM POLYESTERS* V. N. SOKOLOV, L. YA. RAPPOPORT, I. YA, PODDUB~Y'I and N. P. APUKHTINA S. V. Lebedev Scientific Research Inst. qf Synthetic l~ubber (Receive~ 16 August 1964) AS IS well known, water can react with various compounds containing isocyanate groups and is therefore Of great importance in the Synthesis of urethane polymers [1]. From a stud ~ of the reaction of water with mono-isocyanates, a scheme was proposed according to which the reactions take place in two stages: 1) amine formation and 2) interaction of the amine o b t a i n e d with isocyanate, as a result of which symmetric di-N-substituted urea is formed. In fact, the interaction of water with isocyanates, apparently, takes place according to a much more complex system, b y the formation of numerous unstable intermediate products
[2, 3]. In the case of asymmetrical di-isocyanates, water firstly reacts with the most reactive isocyanate groups: thus, for example, during the interaction of telinyl-2,4-di-isocyanate (2,4-TDC) with water, the isocyanate group which is in the p-position in relation t o the methyl group, takes part in the reaction, whereas the less active o-NCO-group does not react, under certain conditions. In addition, the formation of an electropositiv.e urea group reduces the reactivit y of free isocyanate groups even more [4, 5]. The reaction of water with isocyanates depends to a considerable extent on the medium in which the reaction occurs and firstly on the solubility of the components [6]. As far as the reactions of water are concerned during the synthesis of urethane polymers, they have been very little investigated and the literature available refers to polyurethane foams. * Vysokomol. soyed. 7. No. 7, 1258-1263, 1965