SU717649A1 - Method of determining devay rate constant of initiator of polymerizing monomer in viscous medium - Google Patents

Description

(54) METHOD FOR DETERMINING THE CONSTANT VELOCITY OF THE INITIATOR DECOMPOSITION IN A VISCOUS POLYMERIZED MEDIUM 12

MONUMS OUo AND (jo. - initial and current:: polymerization rates, t - polymerization time;; .TI. This method, according to the authors, according to one kinetic curve, calculates Krasp. For viscous media of the sample. However, In our view, the described method of determining the decay constant of the initiator in a viscous medium of the polymerizing monomer has drawbacks. First of all, it is necessary to carry out the measurement of the value with some definite depth of conversion, and with increasing conversion, not interrupted The reaction viscosity is wfadcbj, as a result of which the mines of all the elementary constants of the process that determine the value of the current rate of plimerization, therefore, the values calculated according to the indicated dependence (2) of the Spin value can be reliable. , the authors of the equation do not describe the kinetics of homophase polymerization at deep degrees of transformation, the chemical reaction, such as the decomposition of the initiator, the formation, growth and breakage of polymer chains trimer solution of polymer in myomero or, more precisely, in solution of monomer in polymer (in polymer phase). At the same time, knowledge of the true values of the constants of the elementary stages of the polymerization process in the whole range of conversion and in particular; The rate constants of the decomposition; a: yes, the initiator, is necessary for a quantitative description of the synthesis of the polymer of the product, the correct choice of the technological regime of the polymer, and the quality control of the resulting polymer. The purpose of the present invention is to fly; determination of the initiator decay rate constant for any degrees of progression. . . This goal is achieved by the fact that at any two times, at selected time points t and t, respectively, the amounts of polymer Z and Z formed, with n, the continuous dosage of gaseous monomer and constant relative pressure of my meter vapor within 0.50 - 0.99 and calculate the decay companion using the formula: I / ai HZ VdflJUt Iz Krasp. - the rate constant E aspAndiniTor; the amount of polymer formed at times t. ); Polymerization rates measured at two different points in time. The following process was obtained in the process of polymerization of an unchanged composition of the nd phase: (d) dis | the initial and current amount of polymer, M is the monomer concentration in the polymer phase, the amount of initiator in the polymer phase, the efficiency of initiation in the polymer phase, the molar volumes of monomer and polymer in the polymer phase, cC is the monomer content in the polymer phase, M is the amount of monomer in the polymer phase, the rate constants c f, tey growth, chain breakage and initiator disintegration, respectively, e after the introduction of the designator denotes the amount of polymer formed per unit mass of the polymer phase (vi., n) sl kinetic parameter, predicted which is a combination of the kinetic characteristics of the polymerization process, which, under the condition of a constant composition of the phase, is a constant value, is rewritten as 2. carrying out the polymerization of the specified conditions and the kinetic curve of the polymer that forms in the polymer, arbitrary points corresponding to two timeization values, t. and t values of the polymer, forming these moments - Z and Z t. But for them the value of quickerization - (l)), you can determine the value of the initiator decay rate constant corresponding to the selected composition of the polymer phase from the specified dependence (3), ha g For carrying out experiments on the determined Cross, such “onomeric” ones as vinyl chloride and wines or chloride / ethylene, propylene, tri-ethylene, or other easily boiling liquids, whose vapor pressure at operating temperatures will be high AQcTaTO4HcS, may be chosen, as a result, their vapor pressure will be high. The polymer phase will not control the accumulation of the polymer product. This can be carried out in an apparatus consisting of two main parts: the working installation and the technical device. The schematic equipment is shown in the figure. The main elements of the working installation are the calibrated capillary p 1 for monomer.

The values of the constants for the decay in the polymer phase of the initiators of ethylhexyl peroxydicarbonate (PDEG) and acetylcyclohexylsulfonyl peroxide (ACP), determined for different polymerization conditions

vinyl chloride in the mass of condensable from the dispenser through the valve 2 and through a transitional capillary 3 and crane 4 connected to the capillary 1 ampoule 5 for a polymer containing the initiator in question. A thermostatted device is a paired thermostat consisting of two sections 6 and 7 in which the temperature of the heat transfer medium is monitored using a thermometer 8. Dp preventing the flow of heat transfer media, one of which in the capillary b section provides the vapor pressure of the monomer. in the system, and the other in section 7 for the ampoule is the reaction temperature; a gasket 9 is provided, pressed by a cap nut 10. The relative temperature of the heat carrier flows determines the relative value: monomer vapor pressure, and as a result, the composition of the polymer phase. Below are examples that clarify the essence of the proposed method for determining the decay constant of the initiator in the polymer phase by means of experiments carried out in the described equipment, and the results of the Krasp measurements are given in Table.

0.99

PDEG

0.95 PDEG

0.88

PDEG

0.77 PDEG

0.68 PDEG

0.99 ACCP

0.95 ACP

0.88 ACP

0.77 ACCP

0.68 ACCP

8.4

27.0

76.0

77.0

3.0 5.4 20.8

61.6 83.5

6.5

57.6 17.8 86.5

3.5 14.2

50.0 91.2 10.4

44.8 93.0

21.2 64.4

208.0 77.0

3.0 19.6 62.0 83.5

202.0

6.5 17.6 60.0

192.0 86.5

3.5 14.0 53.0

176.0 91.2 47.4

Claims (4)

165.2. 93.0 Example In a; mpula 5 zagru,. Jacques) A weighed amount of polyvinyl chloride in the amount of 0.3024 g containing 0.028% ethyl hexyl peroxydicarbonate (PDEG) yryatrya and attached to the working unit. The installation is connected to the Vacuum system and vacuuming is carried out to a residual pressure of mm Hg, after which it is condensed into a capillary 1 purified from oxygen and 1.5 g of impurities of vinyl chloride. The filled installation is transferred to a thermostatic device, in each part of which, b and 7, the necessary temperatures are pre-set: in the vessel for the ampoule. , .S vessel. For capillary 5-55 After being installed in the installation, it is equal to the distance between the gaseous and liquid monomers, which is indicated by the constant position of the meniscus in the capillary 1, which is observed using a cathetometer, opening the connecting valve 4, thereby providing continuous dosage of gaseous monomer in an ampoule with a polymerizable mixture. The selected temperature regime corresponds to a relative d: p of monomers equal to the composition of the polymer phase, the monomer content of which is 13.5%, which is equivalent to the polymerization depth of vinyl chloride in the mass equal to 86.5%. One observes in time the loss of monomer in the capillary, the consumption of which causes the increment of the polymer phase. The resulting dependence is carried out graphically, the sediments along the axis of coordinates in grams are the increment of the unit mass of the polymer phase, Z, and along the abscissa in minutes the time is poly. meurization. On the resulting curve, two arbitrary points are selected, corresponding to two different values. the mass of the polymer phase, 82 g and 1.84 g formed in system K; time points ± .100 min and. t2 250 min. The production is graphical (the differentiation is for them the values of instantaneous polymerization rates () 0.1576 g / min (|| 0.1064 g / min. The selected values are substituted into the working equation (3) and the initiator decay constant is calculated. The Krasp value found. -17.8 sec. Is given in the 3rd line of the “gabl; i., Ri” and m e. P 2. The operations are carried out as described in example 1, but with a relative vapor pressure of monomer in the working installation equal to 0.77 The vial 4 is heated to a temperature, and the capillary p. 1 to a temperature of 50 ° C, which corresponds to the Contained The monomer in the polymer phase is equal to 9.8% and is equivalent to the polymerization depth of vinyl chloride in a mass equal to 91.2%. The measurement and calculation, just as described in Example 1, have a Crasp value of 14.2 x - 105 sec- (4-row tabl.), EXAMPLE 3. The experiments were carried out as described in Examples 1 and 2, but acetylcyclohexylsulfonylperoxide (ACSP) was used as an initiator. The values of Krasp determined in a similar way are given in 6-10 rows table. As follows from the given examples and analysis of the table data, the method according to the invention makes it possible to make calculations of the decay rates of initiators for any degrees of conversion of the polymerization process and provides, compared to existing methods, the advantage that with relative ease of semi-; Experimental results provide the ability to determine the true values of the decay constant of the initiator in the polymer phase, corresponding to its specific composition, which is very important in mathematical modeling of polymerization processes. DETAILED DESCRIPTION OF THE INVENTION Method for determining the decay rate constant of an initiator in a viscous medium of a polymerizable monomer by increasing the mass of a polymer per unit time, characterized in that, in order to determine the initiator decay rate constant for dl. for any degrees of conversion, determine for two arbitrarily selected points of time t and t, respectively, the amount of polymer formed Z and the continuous dosage of gaseous monomer and a constant relative vapor pressure of the monomer within 0.50-0.99, and the decay constant is calculated using the formula: 2tnfe, ; @. i asp, -ba-ti Kpoicn. constant —a decay rate of the initiator; Z and Zg are the quantities of polymer formed by the time points t and tjjr (the polymerization rates measured at two different points in time t Sources of information taken more attention in the examination 1, .Emanuel A.M., Knorre D., Kurz Chemical Kinetics, m., Higher School, 1969. 2, Bagdasar n. H.S. Theory of radical polymerization. M., Science, 1966. 3 Korolev GV, Berlin AD, Kefeli T.Ya. High Molecular Compounds, 1962, No. 4, 1520 (prototype). 4. Gladyshev, GP, Popov, VA., A radical polymerization at deep degrees of transformation, M., Nau1974. ka