Таблица 2 – Кинетика отверждения и степень сшивки вулканизатов

Отверждающий агент MBM не вступает в реакцию отверждения до Т=60 С, поэтому для дальнейших исследований не использовался.

Увеличение содержания отверждающего агента приводит к падению М_с и соответственно к повышению жесткости (модуля упругости) и снижению деформативности вулканизатов. Максимальная плотность сшивки ν_l/v наблюдается при использовании 0,2…0,3 % ТЕ и Dur и составляет 0,234 и 0,229 соответственно. Дальнейшее увеличение концентрации ароматических динитрил-N-оксидов до 0,4 % приводит к резкому повышению плотности сшивки полимера для всех исследованных отвердителей, особенно MBS. Минимальная энергия активации (32,5 кДж) наблюдается при использовании отверждающего агента TE, а максимальная – 53,5 кДж – MBS.

Оценка влияния строения ароматических динитрил-N-оксидов на динамику структурирования и кинетику процесса отверждения тетразольного полимера показала существенные различия в реакционной способности экранированных реакционных центров, что, по-видимому, можно связать с действием стерических или стереоэлектронных факторов. Представляет интерес провести расчет электронной структуры и различных индексов реакционной способности динитрил-N-оксидов (в частности, с параметрами Фукуи) в целях нахождения возможных соотношений структура – свойство.

1. Охотников М.А., Валуев В.И. Исследование кинетики отверждения полиуретанов, содержащих двойные связи в цепи, динитрилоксидами // Журнал прикладной химии. – 2002. – Т. 75. – Вып. 9. – С. 1555–1558.

2. Якубов А.И., Цыганов Д.В., Беленький Л.И. и др. Синтез стабильных функционально замещенных нитрилоксидов ароматического ряда // Известия АН СССР. Сер. хим. – 1991. – С. 1201–1203.

3. Белоусов А.М., Пазников Е.А., Петрова Г.Я. и др. Исследование низкотемпературного процесса отверждения поли-N-метилаллил-5-винилтетразола // Журнал прикладной химии.  2008. – Т. 76. – С. 1197–1199.

4. Белоусов А.М., Пазников Е.А., Петрова Г.Я. и др. Некоторые закономерности отверждения поли-N-метилаллил-5-винилтетразола N-оксидом // Ползуновский вестник. – 2004. – № 1. – С. 278–282.

5. Аверко-Антонович И.Ю., Бикмуллин Р.Т. Методы исследования структуры и свойств полимеров.  Казань, 2002. – 302 с.

6. Huggins M.L. Thermodynamic compatibility of polymers with the solvent / Ann. Acad. Sci. – 1942. – V. 43. – N. 4. – P. 32–35.
RHEO-KINETICS OF STRUCTURING AND FEATURES OF CURING OF AZOLE BINDERS BY STERICALLY DIFFICULT AROMATIC DINITRIL-N-OXIDES

P.I. Kalmykov¹, L.F. Podanyova¹, A.A. Lukashev¹, A.Yu. Mershin², A.A. Astratyev²,

P.V. Petrekov³, Ye.A. Pyznikov<sup>3

1</sup> JSC Federal Research & Production Center «ALTAI», Biysk, Russia

² Federal State Unitary Enterprise «Special Design-Technological Bureau

«Process Engineer», Saint-Petersburg, Russia

³ Biysk Technological Institute of Altai State Technical University, Biysk, Russia
Dinitrile-N-oxides of aromatic series are widely used as low-temperature hardeners of synthetic polymers during processing and manufacturing of composite materials based on plasticized polyesterurethane elastomers: 1,3-dinitrile-2,4,6-triethylbenzene and more active 1,3-dinitrile-2,4,6-trimethylbenzene. Crosslinking of polymer chains occurs due to the 1,3-dipolar cycloconnection with the formation of five-membered isoxazolines cycles in the temperature range 35–40 ºC [1, 2]. In the structure of allylated poly-N-methyl-5-vinyltetrazole, continuous individual groups are not located in the main chain, but in most accessible for the hardener side tetrazole fragments, so its reactivity to interact with these dinitrileoxide increases [3, 4].

The main factor determining the activity of dinitrile-N-oxides, apparently, is a spatial shielding of reactionary nitrile-oxide groups in a molecule by other substituents. Thus, changing the position and the nature of the substituents, it is possible both to decrease and to increase the speed of hardening of polymeric binder.

A number of new aromatic dinitrile-N-oxides with different substituents were synthesized to estimate the influence of the structure of hardeners on their activity in the process of three-dimensional grid formation from plasticized azole polymer and their properties were studied.

The studied compounds are soluble in 1,4-dioxane, acetonitrile, ethyl-acetate and limited in benzene, toluene, isopropyl alcohol, ethanol, 1,2-dichloroethane.

The ratio of the solubility of the curing agent in plasticizer and its activity is of interest.

The solubility of the obtained compounds in plasticizer, measured by refractometry method at the temperature of compositions preparation (T=23 °C) and vulcanization of products on their basis (T=40 °C), are given in Table. 1.

As it can be seen, the highest solubility has ТЕ: C_m^{40 °С} =36 % mass, moderate solubility (up to 10–20 % of the mass) is observed for hardeners ТМ, DMO, Dur, MBS и MBM (C_m^40 °С =6.6–17 % mass.), poor solubility for MBE (C_m^{40 °С}=2.5 % mass). Hardeners MBP and MBB with large amount of substituents in the molecule structure are not soluble.

In general, it can be noted that the solubility of the studied dinitrile-N-oxides in the temperature range 23…40 °C, taking into account their low concentration in the system, is high (C_m^{23 °С} >1.0 %). Therefore, it can be expected that the studied curing agents in the compositions will be completely dissolved, except MBP and MBB.

Rheo-kinetic curves of structuring the binder (ratio of polymer-plasticizer 15/85 % mass.) with dinitrile-N-oxides of various reactivity (0.216 % from NET mass) at T = 25 °C, recorded on a rotational viscometer «Brookfield» model HBDV-II+Pro in the range of effective shear rate γ= 1...5 s^–1 are given in Figure 1.



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Figure 1 – Dependence of viscosity changes of azole binder on the time, using aromatic dinitrile-N-oxides at T = 25 °C

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Name	Constitutional formula	Gross-formula	ММ	Solubility Сm, %
				23 С	40 С
Tri-ethyl (TE) 2,4,6-triethyl-1,3-benzoldinitrileoxide		C14H16N2O2	244.280	5	36
Tri-methyl (TM) 2,4,6-trimethyl-1,3- benzoldinitrileoxide		C11H10N2O2	202.199	4	17
Di-methoxi (DMO) 3,6-methoxy-1,4- benzoldinitrileoxide		C10H8N2O4	220.170	4	15
Durol (Dur) 1,4 - dinitrileoxide - 2,3,5,6 -tetramethylbenzole		C12H12N2O2	216.226	2,7	6.6
Methylene-bis-salicyloxi (MBS) 2,2’- methylene-bis(oxi)- dinitrileoxibenzole		C15H10N2O4	250.143	2,4	16
Methylene-bis-methoxi (MBM) 5,5’-methylene-bis(2-methoxinitrileoxide)		C17H14N2O4	310.295	2	12
Methylene-bis-ethoxi (MBE) 5,5’- methylene-bis (2-ethoxinitriloxidebenzole)		C19H18N2O4	338.349	1	2.5
Methylene-bis-propoxi (MBP) 5,5’- methylene-bis (2-propoxynitrileoxide benzole)		C21H22N2O4	366.403	N/s	N/s
Methylene-bis-buthoxi (MBB) 5,5’- methylene-bis (2-butoxynitrileoxide benzole)		C23H26N2O4	394.457	N/s	N/s

The rate constants of structuring (gel formation) NET at T = 25 °C with aromatic dinitrile-N-oxides (defined as time reciprocal of increasing the level of dynamic viscosity up to 250 Ps) are given in Figure 2.

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As it can be seen, the rate of structure formation is not dependent on soluble of the studied hardeners (see Figure 2 and Table. 1), it is only important that in terms of the process they were in solution.

By the method of equilibrium swelling it was studied the kinetics of gel fraction output P_r of the binder based on tetrazole copolymer and the parameters of vulcanization grid - molecular mass of the middle area in chain between nodes of spatial grid M_s, the effective density of cross-linking ν_l/v by known methods [5, 6] when the content of aromatic dinitrile-N-oxides ТЕ, DMO, Dur, MBS from 0.2 to 0.4 % from the binder mass in the temperature range of 30 – 60 ºС. The numerical values of the obtained kinetic characteristics of the process of curing and spatial grid of vulcanizates are given in Table 2.

Table 2 – Kinetics of cure and degree of crosslinking of vulcanizates

Dinitrile-N-oxides	Мs·103			νl/v, mole/cm3			τind40 °С, min	Кт40 °С·10–3, min–1	ΔЕА, (30…60 °С) kJ/mole
Hardener content, % mass.	0.2	0.3	0.4	0.2	0.3	0.4	0.4
TE	5.95	5.6	3.8	0.220	0.234	0.345	351	0.28	32.5
Dur	7.4	6.0	4.2	0.177	0.229	0.312	293	0.34	36.4
DMO	10.0	8.0	6.5	0.090	0.109	0.201	162	0.61	47.4
MBS	7.4	6.9	3.6	0.176	0.191	0.354	138	0.72	53.5

Curing agent MBM does not react curing up to temperature of 60 °C, therefore, it were not used for further research.

The increase in the content of curing agent leads to the decrease of M_s and, so to the increase of the rigidity (modulus of elasticity) as well as to the reduction of deformability of vulcanizates. The maximum density of crosslinking ν_l/v is observed when using the 0.2–0.3 % ТЕ and Dur, making 0.234 and 0.229 respectively. Further increase in the concentration of aromatic dinitrile -N-oxides up to 0.4 % leads to a sharp increase in the density of crosslinking polymer for all the studied hardeners, especially MBS. The minimum activation energy (32.5 kJ) is observed when using a curing agent TE and maximum – 53,5 kJ – when using MBS.

The studies of the influence of the structure of aromatic dinitrile-N-oxides on the structuring dynamics and the curing process kinetics of tetrazole polymer revealed the significant differences in reactivity of shielded reaction centers, which, apparently, can be associated with the effect of steric or stereoelectronic factors. To calculate the electronic structure and various indices of reactivity of dinitrile-N-oxides (in particular, with Fukui parameters) in order to find possible correlation between «structure – property» is of interest.

1. Okhotnikov M.A., Valuev V.I. Studies on Kinetics of Polyurethanes Curing, Having Two Bonds in Chain by Dinitroxilamides // Journ of Applied Chem. – 2002. – V. 75. – Iss. 9. – P. 1555–1558.

2. Yakubov A.I., Tsyganov D.V., Belenkiy L.I. et al. Synthesis of Stable Functionally Subtituted Nitriloxides of Aromatic Group // Izv. АN USSR. Ser. Chem. – 1991. – P. 1201–1203.

3. Belousov L.I., Paznikov Ye.A., Petrova G.Ya. et al. Studies on Low-Temperature Curing Process of Poly-N-methylallyl-5-viniltetrazole // Journ. of Applied Chem. – 2008. – V. 76.– P. 1197–1199.

4. Belousov А.М., Paznikov Ye.A., Petrova G.Ya. et al. Some Laws of Curing of Poly-N-methylallyl-5-viniltetrazole by N–oxide // Polzunov’s Vestnik. – 2004. – No. 1.– P. 278–282.

5. Averko-Antonovich I.Yu., Bikmullin R.T. Methods to Study the Structure and Property of Polymers / Kazan, 2002. – 302 p.

6. Huggins M.L. Thermodynamic compatibility of polymers with the solvent / Ann. Acad. Sci. – 1942. – V. 43. – N 4. – P. 32–35.


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С.Б. Егоров, В.И. Пегов

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S.B. Yegorov, V.I. Pegov

The paper is focused on methodologies developed for simulation of the underwater shock wave in pressure and impulse and proposes an approach for their application using the available standard charges of low power. The results of experimental approbation of the approach, that prove its correctness, are shown.