Final Technical Report COMBUSTION KINETICS OF TETRAFLUOROETHYLENE Richard A. Matula Department of Mechanical Engineering The University of Michigan Supported by: AIR FORCE OFFICE OF SCIENTIFIC RESEARCH GRANT NO. AF-AFOSR-1144-66 September 1967

TABLE OF CONTENTS Page LIST OF ILLUSTRATIONS iv ABSTRACT v I. INTRODUCTION 1 II. EXPERIMENTAL FACILITIES AND TECHNIQUES A. Facilities 2 B. Experimental Techniques and Procedures 2 III. ANALYTICAL DEVELOPMENTS 7 A. Infrared Analysis 7 B Gas Chromatographic Analysis 7 IV. EXPERIMENTAL RESULTS 11 A. Preliminary CF20 Pyrolysis Results 11 B. Preliminary C2F4 Reaction Rate Studies 15 1. C2F4 Pyrolysis 15 2. C2F4 Oxidation Experiments 18 REFERENCES 19 iii

LIST OF ILLU'STRATIONS Table Page i. Column Materials Studied for General C/F'/O Compound Separations 8 20 CO2 Rate Constant in CF20 Pyro'.Jysis 1.4 35 CF20 Rate Constant in. CF20 Pyrolysis 14 4o Temperature Dependence of kl(T) and k2(T) 1.5 5o Rate Constants for the Pyrolysis of C2F4 18 Figure 1, Static facility system schematic. 3 2 The furnace. 4 3. Static reactor vessel, 5 4. Typical chromatogram of C02 - CF20 mixture. 9 5 Typical chromatogram of C2F4 oxidation prod.uctso 10 6. Rate of production of CO2 as a:function of initial. CF20 concentration. 12 7o Rate of consumption of CF20 as a function of initial CE20 concentration. 13 8. C2F4 hal.f-life as a function of initial C2F4 concentration. 1.6 8,, c2F4 2F4~~~~~~~~~1\

ABSTRACT The oxidation kinetics of tetrafluoroethylene and the pyrolysis of carbonyl fluoride are being experimentally studied in the temperature range 500 -7500K. Both infrared spectroscopic and gas chromatographic techniques have been developed for the quantitative analysis of all important reaction productso The pyrolysis of CF20 has been studied in the temperature range 500 -750~K. When the studies are conducted in a quartz reactor vessel, the only significant gaseous products are CF20, C02, and SiF4o Preliminary analysis of the kinetic data indicate that both the heterogeneous rate of production of C02 and rate of consumption of CF20 are half order with respect to CF20. Prior to the initiation of the C2F4 oxidation experiments, the pyrolysis of C2F4 was studied at 636~K. The only important product was c-C4F8, and the rate was shown to be second order with respect to C2F4. The second order rate constants as evaluated from both the experimentally determined rate of production of c-C4F8 and the rate of decrease of C2F4 are reported. Preliminary oxidation experiments employing an equimolar mixture of 02 and C2F4 at 636~K and an initial pressure of 50 mm of Hg indicate that the oxidation reaction is fast and that the only significant reaction products are CF4, C02, and CF20. Additional. work with these systems is being continued under the sponsorship of the Air Force Office of Scientific Research Grant No. AF-AFOSR-1144-66.

I. INTRODUCTION In many practical applications the detailed flow fields about reentry vehicles can only be calculated if the kinetics of the flow field are known. The flow field chemistry may be particularly important when combustion reactions are possible. Frequently, the ablation products of reentry vehicles may, undergo exothermic reactions in the boundary layer or the wake, and therefore, the combustion kinetics of' ablation products are important in determining the state of' the flow field including the wake electron densities. Teflon (C2F4)n which is classified as a subliming ablator has been employed as an ablation material in a number of investigations.-4 Under the action of the aerodynamic heating, the Teflon surface begins to depolymerize into the monomer (C2F4), that has a very high vapor pressure, after the surface reaches its ablation temperature. Under most conditions, the monomer flashes directly into the vapor phase without passing tbrough the liquid state. The Teflon ablation is given by (C2F4)polymer+(C~eC4)vapor+ 750 B/lbm (C2F4) The C2F4 vapor may participate in the following combustion reaction in the boundary layer or vehicle wake (C2F4)vapor + O.+2CF20 + 3,200 B/lbm(C~F4) (2) Comparing Eqs. (1) and (2) it is seen that the energy liberated by the combustion process is approximately four times the heat of ablation. Therefore, if the exothermic combustion reaction takes place to any extent in the boundary layer or wake, the flow field will be strongly influenced. The above discussion indicates that a general understanding of chemical kinetics of the C/F/O/N reaction system, including the oxidation of C2F4 and the pyrolysis and further reactions of the various oxidation products, is necessary before a complete understanding of the flow field in the region near a reentry vehicle using a Teflon ablation shield can be obtained. The purpose of the present research project is to study the oxidation kinetics of tetrafluoroeth..y3l.ern.e and the thermal. stability of one of the important oxidations products, CF20, in the temperature range 500-1000~K. Preliminary experimental results are included in this report. Additional work with these systems is being continued u.nder the sponsorship of the Air Force Office of Scientific Research Grant Noo AF-AFOSR-1144-66o

II. EXPERIMENTAL FACILITIES AND TECHNIQUES A. FACILITIES A schematic diagram of the static reaction system is shown in Fig. 1. The vacuum system has been constructed from special greaseless vacuum stopcocks and glass to metal seals which are rated at 10-8 torr. The two furnaces are designed for a maximum operating temperature of 1500~K. Temperature control to within T 20K is obtained by automatically regulating the power input to the heaters. In order to insure that the longitudinal temperature gradients in the furnace cavity are negligible, guard heaters have been installed at each end of the furnaces. A sketch of a typical furnace is shown in Fig. 2. The present design can be readily adapted for flow system operation in the event that this becomes necessary. A schematic diagram of a typical quartz reactor is shown in Fig. 3. Excellent analytical facilities are available for the analysis of C/F/O compounds. A Beckmann IR-10 spectrophotometer with a spectral range from 300-4000 cm-1 is available, and gas analysis cells with path lengths up to one meter can be employed for the required infrared analyses. A library consisting of the spectra of many of the important C/F/O compounds has been developed in the past year. Gas chromatography instrumentation including both thermal conductivity and ionization detectors are also available for product analysis. Methods have been obtained for the gas chromatographic determination of all important compounds. In particular a column has been developed which will allow the simultaneous determination of CO2 and CF20 (see Section III). B. EXPERIMENTAL TECHNIQUES AND PROCEDURES The gases utilized in this research program were purchased from commercial sources. Ultra high purity oxygen (minimum purity = 99.95%), and CF20 with a suggested minimum purity of 97% were purchased from the Matheson Company. Gas chromatographic analysis of the CF20 indicated that the only significant impurity was C02. However, it was determined that the C02 impurity in the CF20 had a mole fraction of approximately 0.08. The tetrafluoroethylene used in the present experiments was purchased from the Columbia Organic Chemicals Company. The manufacturer specified that the minimum purity of the C2F4 was 99%. Gas chromatographic analysis of the C2F4 indicated that the majority impurity was c-C4F8 which had a mole fraction of approximately 0.6%._ The actual experimental data has been obtained by applying the standard experimental procedures that have been developed in our laboratory. The re

Vacuum Pump C 2 F Storage Temperature ControlJ Furnace Control Calibration Gas Gesls V cuum 0-2 Reaction ~~~~~~~~Stopcocks R Ilfaeaction CF 0Disoiaio CF2p0risensoitn To Gas Analysis Precision Dial C2 F4Oxdto Experiments ~System Manometer Experimet 1Fig. 1. Static facility system schematic.

Furnace Cavity is 5" 0. D. and 92 "Long -- Transite End Plates - High Temperature Insulation Primary Heating, 'Primary -.. Elements /Heating Elements& l14 llld l' l ilt, I/uard Hea)' /. igh Teaters I nsulation Fig. 2. The furnace. I Guard Heater' 12" ~ 118" Tie R~d Hinges ZHigh Temperature Insulationl Fig. 2. The furnace.

actants are introduced, into thl,-e reactor which s maintained at a controlled temperature, and the time dependence of the corncentration of bothnL the reactants and prodncts are determined by withdrawing samples from the reactor at -rariable time intervals and ana'lyzin.;g the samplLe wit.h t:he aid of both. the gas chromatographic and infrared anallysis equipment,, 7'Thes-e data. which are obtair~ed at variabe temperatlure, init:ial pressJ.re and reactant composition are used for the eva.l ation of the nece-sary rate eqr1ations and, the appropriate Arrheni-,s parameters.

West Hi-Vac 14135 Quartz Capillary sampling tube I Joint (female) (typ.) Quartz to Vycor West (2mm) Graded Seal (typ) Vacuum Stopcock (typ.) Quartz-64mm O.D. 60 mm L.D. Fig. 5. Static reactor vessel.

III. ANALYTICAL DEVELOPMIENTS A. INFRARED ANALYSIS Considerable effort has been expended in the past year to develop the techniques necessary for both the qualitative and quantitative analysis of compounds that are important in the C/F/0 system. A Beckmann IR-10 infrared spectrophotometer with a spectral, range 300-4000 cm-a was received during the year. This instrument has been put into operation and a library of pure component spectra of the various fluorocarbons has been established. The spectra of CF20, C02, and CO, a:l.l of which are important compounds in the C/F/O reaction system. are also included in the library. Gas absorption cells with path lengths from 5 to 100 cm are available for the required analysis. This flexibility allows a wide range of concentrations of a given molecule to be measured. In order to decrease the reaction of CF20 and other reactive fluorocarbon compounds with the gas cell windows special window materials including AgBr and AgC1. must be used. The IR facilities have also been used for the quantitative evaluation of C02 and CF20 in gas mixtures. The data obtained in these experiments are in substantial agreement with the data from gas chromatography analysis of the same mixture~ B. GAS ChROMVLATOGRAPH:IC A:IALYSIS The most important factor in the effectiveness of a gas chromatograph to quantitatively analyze gas mixtures is the selection of a column which will adequately separate all. of the components in the mixture. For our purposes columns had to be developed which could separate two classes of mixtures: (1) C2F4 - c-C4F8 mixtures and (2) 02 - C2F4 - CF4 - CO2 - CF20 mixtures. The separation of C2F4 - c-C4F8 mixtures was readily obtained by employing a 6-ft column of 3% squalane on silica gel maintained at 25~C. The C2F4 - c-C4F8 separation was also obtained by utilizing a 4-ft column of 50/80 mesh type N Poropak maintained at 100~Co Both of the above analyses were performed with a He carrier gas flow rate of 60 ml/mino A literature search indicated that the simultaneous gas chromatographic quantitative analysis of C02 - CF20 mixtures has not been reported. In order to obtain the required separation of C02 and C.F20 a systematic column evaluation program was undertakenn The various col.umns tested are listed in Table 1M It was found that excellent separation of C02 - CF20 mixtures could be obtained by using a 6-ft composite column consisting of 2 ft of 50/80 mesh Poropak (Waters Associate, Inc.) Type I" followed by 4 ft of 50/80 mesh Poropak Type N. The column was packed in 1/4 in. OiD type 315 stainless steel tubing Before final installation in the chromatograph the column was heated

to i80~C and purged with heLium (60 ml/min for two hours). Prior to each series of runs the column was conditioned by passing three 250 mm of Hg samples through it. TABLE 1 COLUMN MIATERIALS STUDIED FOR GENERAL C/F/O COMPOUND SEPARATIONS Solid Support Stationary Phase Activated Alumina Activated Silica-Gel Activated Al'umina with 10% NaCl Activated Charcoal Activated Molecular Sieve, 5A Activated Molecular Sieve, 13x Poropak Type N Poropak Type Q Poropak Type R Poropak Type S Poropak Type T Tee Six kTeflon) 10% Carbowax 300 Tee Six 5% Kel F Oil No. 10 Kei F 300 LD 5% Kel F Oil. No. 10 Tee Six 5% Fluorolube Chromosorb W 5% SE-30 Chromosorb T 5% DC-702 Chromosorb P 20% Silicone Oil DCFS 1.265 Chromosorb P 20% Silicone Oil DC 710 Chromosorb P 20% QF-1 Fluoro-Silicone Oil Chromosorb P 20% Versilube F-20 Chromosorb P 20% SE-S2 Chromosorb W 20% Kel F Oil. No. 10 A typical chromatogram indicating the separation of CF20 and CO2 as obtained with the column described above is shown in Fig. 4. The operating conditions corresponding to the results given in Fig. 4 areD column temperature 23'^C carrier gas (helium) flow rate 60 ml/min. The detector response was determined to be linear when the CF20 concentration was varied by a factor of approximately eleven and the curve of detector response vs. concentration of CF20 extrapolated to the origin. This indicates that, once the column is conditioned, CF2O absorption on the co-l -mn is essential.ly nonexistent' A typical chromatogram showing the separation of 02, CF, C02, CF20, and C2F4 on the coiumn described above is given in Fig. 5.

C02 CF20 w LC z 0 a3, 0 LIJ wJ I I I I I 0 3 6 9 12 15 TIME, MIN Fig. 4. Typical chromatogram of C02 - CF20 mixture. 9

w CF W)C F20 z C. 02 C) w 0 3 6 9 12 15 18 Fig.. Typical chromatogram of C2F4 oxidation products. 0 0 I I I I I I 0 3 6 9 12 15 18 TIME, MIN Fig. 5. Typical chromatogram of C2F4 oxidation products. 10

IV. EXPER IMENTAL RESULTS A. PRELIMINARY CF20 PYROLYSIS RESULTS The pyrolysis of CF20 with initial CF20 pressures ranging from 25 to 600 mm of Hg has been studied in the temperature range 500-750~K. When the studies were conducted in a quartz reactor vessel, gas chromatographic and infrared anai.ysis of the gaseous reaction products indicated that the only important products were CF20, C02, and Si:F4. Preliminary experiments have been undertaken in order to determine the form of the rate equation for this heterogeneous reaction. The following rate laws were assumed d [CO:.o.s = d% k~:l.T) [CF2o0 (3) A F20 d=. [= k2(T) [CF20~ (4) The numerical values of a and D in Eqs. (3) and (4) were determined by measuring thle initial rate of formation, and decay of C02 and CF20, respectively, as a function of initial CF20 concentration. The initial rates were evaluated by employing the following equations~ Rca [CO:, it, - [C-a~o (5) 2C0W At.t LCF2O j [CFO i j 'O-0 ] o t. (6) At As indicated in Section II the concentrations of C02 and CF20 as a function of time were determined by gas chromatographic techniques. The reaction time (At) used in Eqs. (5) and (6) was held constant for any series of runs at a given temperature. In order to insure thati the finite difference approximation of tlhe actual slopes of the C02 and CF20 vs. time curves were a reasonable approximation, the reaction times were varied from 30 min at the low temperature to 5 min at the highest temperature. This technique insured that the change in CIF20 concentration for an experiment was relatively small (5 -O%). Typical curves for the rate of production of CO2 and the rate of decrease of CF20 concentration are given in Figs. 6 and 7, respectively. It is apparent from these results that both a and a are approximately one half and that the prel..iminary data can be conveniently represented by the following rate expressionso

60 40 2 T = 7430 K. slope -.51 8. 0 1 _To~~~~T 6860K. 4U.2 '3.'6.8 1.0 '2. '4.. '8 No. F20] X106 (moles/cc) Fig. 6. Rate of production of C02 as a function of initial CF20 concentration. 12

20 0o T = 7430K. 8 I slope=.5 3 6 M 6864K. slope.5 2.2 o.8.1.2 4.8 1'.0. 4. 6. i. b E F0]o x 0o6, (moles /c c) Fig. 7. Rate of consumption of CF20 as a function of initial CF20 concentration. 13

RCO = kL(T) [CF20] / (7) R k (T) [CF2 2 /2(8) CF20 k2(T) [CF20]1/2 (8) Numerical values of kl and k2 based on Eqs. (7) and (8) and the experimental data are given in Tables 2 and 3, respectively. It should be noted that the rate constants as determined from the experimental data are relatively insensitive to the initial concentration of CF20 and hence the data are adequately represented by the rate expressions given in Eqs. (7) and (8). The average values of kl and k2 as a function of temperature are listed in Table 4. An Arrhenius plot of these data indicate that kl and k2 have activation energies of approximately 17 kcal/mole and 15 kcal/mole, respectively. TABLE 2 C002 RATE CONSTANT IN CF20 PYROLYSIS R d[CO 21 k[FC1/2 2 dt T - 735~K T - 698~K T - 6860K T - 640~K [CF20 x 106 7 6 k x 107 [CFCF2o x 106 k x [CF o X 106 k x 107 moles/cc (moles/cc)l/2 sec-l moles/cc (moles/cc)l/2 sec-' moles/cc (2moles/cc) l/2 sec- moles/cc (moles/cc)l/ secx 0.956 4.660 1.03 2.82 1.05 1.632 9.490 0.660 1.987 4.522 2.07 2.72 4.33 1.835 4.679 1.272 1.014 4.975 4.19 2.64 2.14 1.845 2. 302 0.987 12.87 2.55 4.36 1.941 0. 56 0.795 2.14 1.827 1.089 0.622 1.o6 1.972 2. 313 0.917 2.15 1.765 4.680 0.920 TABLE 3 CF20 RATE CONSTANT IN CF20 PYROLYSIS C2 k[CF,,O] CF2O 2 dt T - 735~K T - 698~K T - 686~K T - 640~K [CF20]o x 106 k x 107 [CF20o1 x 106 k x 107 [CF20]o x 106 k x 107 [CF201o x 106 k x 107 moles/cc (moles/cc)1/2 sec-1 moles/cc (oles/cc)1/2 sec moles/cc (moles/cc)1/2 sec-1 moles/cc (moles/cc)1/2 sec'-1 8.120 3.015 1.03 1.437 8.70 1.713 4.679 0.838 0.956 2. 353 2.07 1.873 4.36 1.688 2.302 0.710 0.442 2.983 4.19 1.154 2.14 1.802 1.163 0.478 8.264 3.022 1.06 1.970 2.313 0.625 1.987 3.047 2.19 1.845 4.680 0.593 1.014 2.028 o.498 1.808 0.506 1,655 1_4~~~~~~~~~~~~~~~~~

TABLE 4 TEMPERATURE DEPENDENCE OF kl.T) AND k2(T) T, klrT) x 07, k2(T) x 107 ~K (moles/cc)i/2 sec-1. (moles/cc)l/2 sec-1 755 4.72 2.91 698 2.68 Lo68 686 1,84 1.18 640 0.882 o.648 B. PRELIMINARY C2F4 REACTION RATE STUDIES 1.o C2F4 Pyrolysis Prior to initiation of the C2F4 oxidation studies, the pyrolysis of C2F4 was considered. These experiments served a dual purposes (1) check out and shake down of the experimental apparatus, and (2) results of these experiments could be checked against data previously reported in the literature.5-7 When the pyrolysis of C2F4 was carried out at 636~K, the only important reaction products were found to be C2F4 and c-C4F8o It was assumed that the equation for the rate of Loss of C2F4 was given by R~':C 'm d... =C k (T) [C2F4J (9) C2 4 d2t The numerical, value of n was evaluated by the half-life method. It is readily shown8 that the measured half life (tl/2) of a reaction can be utilized to evaluate n, int-/-n)f -- Qn(n k)) -, (n.1) In( [C2F43) (10) A plot of the experimenta.l.y measured half life of C2F4 at a reaction temperature of 636~K is shown in Fig. 8. The slope of the curve is -0.98 and hence (n.i.,) Co98 (11) Therefore the numerical value of n in Eq. (9) is 1..98 and for all practical purposes the rate equation for C2F4 is taken to be

40 30 20 10 Q; 9 ru 8 7 0 6 x 5 _+ Qu 4 Slope =-0.98 44 4 Order = 1.98 4l 3 LT = 636 K 2 1 I I l I I1 I I I 2 3 4 5 6 7 8 9 10 20 30 40 50 C2F4 x 1o6, moles/cc Fig. 8. C2F4 half-life as a function of initial C2F4 concentration. 16

RCF" k(t.T) LC2F4bI (12) The results as given in Eq. (12) are consistent with data previously reported in the literature,5-7 In order to evaluate the numerical value of k3 at 636~K the concentrations of both c-C4F8 and C2F4 were measured as a function of reaction time. These experiments were conducted with initial C2F4 pressures of approximately 50 and 100 of Hg. Since the only products are c-C4F8 and C2F4 and we have shown that the rate of decrease of C2F4 is second order, the value of k3 can be determined from both the measured time dependence of the concentrations of C2F4 and c-C4F8. The value of k3 can be evaluated from the integrated form of Eq. (12) k (a ) _ L1 1,.(1 k3(T) - 1 [C4]i [CF4]o ) The rate constant can also be evaluated in terms of the c-C4F8 measurements. The following stoichiometric reaction is valid for the pyrolysis experiments 11F 4 " 4 8 It can be shown that the rate constant k3 can also be evaluated in terms of the initial C2F4 concentration and the concentration of c-C4F8 at time t 1 = L,,8, 2[c-C4 F8 - 1 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ (15) k3 4 _ t [C2F4] ( [C2F4J - 2[c-C4F8]) The numerical value of k at 6360K, for two initial C2F4 pressures, as calculated from both Eqs. (13 and (15) are listed in Table 5. The average value of k3 at 636~K based on the C2F4 and c-C4F8 data are 199 (cc/gm-mole) sec-1 and 180 (cc/gm-mole) sec-, respectively. These two independent numerical values are in good agreement with each other, The numerical values of k3 reported in References 6 and 7 are 192 and 153 (cc/mole) sec-, respectively. The excellent agreement between the present data and the data presented in References 6 and 7 indicates that our experimental facilities and techniques are adequate. I7

TABLE 5 RATE CONSTANTS FOR THE PYROLYSIS OF C2F4 dkC2F4]2 Rd [C2F4 dt2 RC~4 = d k [- CF4] tR kC2F4 kc-C4F8 (mrin) (cc/gm-mole-sec ) (cc/gm-mole-sec) Po = 101.6 mm Hg; T = 636~K 15 206.2 176.5 30 185.2 155.8 30 185.2 173.7 60 199 3 175.0 (ikC2F4)avg 193o9 (kc-C2F4)avg 175.1 Po = 50.8 mm Hg; TR = 6360K 15 218.7 186.1 15 193.2 196.0 30 197.7 187.4 30 189.4 175.2 60 222.8 174.2 (kC2F4)avg 204o4 (kc-C4F) a 183.8 2, C2F4 Oxidation Experiments Preliminary oxidation experiments employing an equimolar mixture of 02 and C2F4 at 6360K and an initial pressure of 50 mm of Hg indicate that the reaction is fast at these conditions and that the only significant reaction products are CF4, C02, and CF20. Additional work with these systems is being continued under the sponsorship of the Air Force Office of Scientific Research Grant No. AF-AFOSR-1144-66.

REFERENCES 1o Economos, C., "Ablation Tests on Plastic Models in a Hypersonic Wind Tunnel," ARS Jo, 1074-1081 (July 1962). 2. Steg, L., and Lew, H., "Hypersonic Ablation," AGARD Hypersonic Conference TCEA, Rhode-St. Genese, Belgium (April 3-6, 1962). 3. Steg, L., "Materials for Reentry Heat Protection of Satellites," ARS J., 815-822 (September 1960). 4. Adams, M., "Recent Advances in Ablation," ARS Jo, 625-632 (September 1959). 5. Atkinson, B., and Atkinson, V. A., "The Thermal Decomposition of Tetrafluoroethylene," J. Chem. Soc. (London), 2086 (April-June 1957). 6. Atkinson, B., and Trendwith, A. B., "The Thermal Decomposition of Tetrafluoroethylene," J. Chem. Soc. (London), 2082 (April-July 1953). 7. Lacher, J., Tompkin, G., and Park, J., "The Kinetics of the Vapor Phase Dimensions of Tetrafluoroethylene," J. Am. Chem. Soc., 74, 1963 (1952). 8. Frost, R. G., and Pearson, A. A.A. Kinetics and Mechanism, 2nd Edition, John Wiley and Sons, Inc., p. 42 (1965). 19

Unclassified Security Classification DOCUMENT CONTROL DATA - R&D (Security claseificatton of title. body of abstract and Indexing annotation muet be entered when the overall report is classilied) 1. ORIGINATING ACTIVITY (Corporate author).a. REPORT SECURITY C LASSIFICATION The University of Michigan Unclassified Department of Mechanical Engineering 2 b GROUP Ann Arbor, Michigan 3. REPORT TITLE COMBUSTION KINETICS OF TETRAFLUOROETHYLENE 4. DESCRIPTIVE NOTES (Type of report and inclueive datea) Final Technical Report 5. AUTHOR(S) (Last name. first name, nitial) Matula, Richard A. 6. REPO RT DATE 7a. TOTAL NO. OF PAGES 7b. NO. OF REFS September 1967 23 8 8a. CONTRACT OR GRANT NO. 9F. ORIOINATOR'S REPORT NUMBER(S) AF-AFOSR- 1144-66 b. PROJECT NO. c. 9Sb. OTHER R PORT NO(S) (Any other numbera that may be assigned thia report) d. 10. A V A IL ABILITY/LIMITATION NOTICES Copies are available from the originator. 11. SUPPLEMENTARY NOTES 12. SPONSORING MILITARY ACTIVITY Air Force Office of Scientific Research 13. ABSTRACT The oxidation kinetics of tetrafluoroethylene and the pyrolysis of carbonLyl fluoride are being experimentally studied in the temperature range 500-7500K. Both infrared spectroscopic and gas chromatographic techniques have been developed for the quantitative analysis of all important reaction products. The pyrolysis of CF20 has been studied in the temperature range 500-750'K. When the studies are conducted in a quartz reactor vessel, the only significant gaseous products are CF20, C02, and SiF4. Preliminary analysis of the kinetic data indicate that both the heterogeneous rate of production of C02 and rate of consumption of CF20 are half order with respect to CF20. Prior to the:nitiation of the C2F4 oxidation experiments, the pyrolysis of C2F4 was studied at 636~K. The only important product wag c-C4F8, and the rate was shown to be second order with respect to C2F4. The second order rate constants as evaluated from both the experimentally determined rate of production of c-C4F8 and the rate of decrease of C2F4 are reported. Preliminary oxidation experiments employing an equirmolar mixture of 02 and C2F4 at 636~K and an initial pressure of 50 mm of Hg indicate that the oxidation reaction is fast and that only the significant reaction products are CF4, C02, and CF20. Additional work with these systems is being continued under the sponsorship of the Air Force Office of Scientific Research Grant No. AF-AFOSR-1144-66. DD 1 *JANR64 1473 Unclassified Security Classification

Unclassified Security Classification 14. _ LINK A LINK B LINK C KEY WORDS ROLE WT ROLE WT ROLE wT Tetrafluoroethylene Oxygen Carbonyl Fluorine Reaction rates Gas phase reactions Reaction kinetics Combustion kinetics Gas chromatography INSTRUCTIONS 1. ORIGINATING ACTIVITY: Enter the name and address imposed by security classification, using standard statements of the contractor, subcontractor, grantee, Department of De- such as: fense activity or other organization (corporate author) issuing (1) "Qualified requesters may obtain copies of this ~~~~~~~~~~the report. ~report from DDC." 2a. REPORT SECUI~TY CLASSIFICATION: Enter the oval, 2a. REPORT SECUTY CLASSIFICATION: Enter the. over- (2) "Foreign announcement and dissemination of this all security classification of the report. Indicate whether "Restricted Data" is included. Marking is to be in accordance with appropriate security regulations. (3) "U. S. Government agencies may obtain copies of this report directly from DDC. Other qualified DDC 2b. GROUP: Automatic downgrading is specified in DoD Di- users shall request through rective 5200. 10 and Armed Forces Industrial Manual. Enter the group number. Also, when applicable, show that optional. markings have been used for Group 3 and Group 4 as author- (4) "U. S. military agencies may obtain copies of this ized. report directly from DDC Other qualified users 3. REPORT TITLE: Enter the complete report title in all shall request through capital letters. Titles in all cases should be unclassified.,, If a meaningful title cannot be selected without classification, show title classification in all capitals in parenthesis (5) "All distribution of this report is controlled. Qualimmediately following the title. ified DDC users shall request through 4. DESCRIPTIVE NOTES: If appropriate, enter the type of.... report, e.g., interim, progress, summary, annual, or final. If the report has been furnished to the Office of Technical Give the inclusive dates when a specific reporting period is Services, Department of Commerce, for sale to the public, indicovered. cate this fact and enter the price, if known. 5. AUTHOR(S): Enter the name(s) of author(s) as shown on 11. SUPPLEMENTARY NOTES: Use for additional explanaor in the report. Enter last name, first name, middle initial. tory notes. If military, show rank and branch of service. The name of the principal author is an absolute minimum requirement. 12. SPONSORING MILITARY ACTIVITY: Enter the name of the departmental project office or laboratory sponsoring (pay6. REPORT DATE: Enter the date of the report as day, ing for) the research and development. Include address. month, year; or month, year. If more than one date appears on the report, use date of publication. 13. ABSTRACT: Enter an abstract giving a brief and factual summary of the document indicative of the report, even though 7a. TOTAL NUMBER OF PAGES: The total page count it may also appear elsewhere in the body of the technical reshould follow normal pagination procedures, i.e., enter the port. If additional space is required, a continuation sheet shall number of pages containing information. be attached. 7b. NUMBER OF REFERENCES: Enter the total number of It is highly desirable that the abstract of classified reports references cited in the report. be unclassified. Each paragraph of the abstract shall end with 8a. CONTRACT OR GRANT NUMBER: If appropriate, enter an indication of the military security classification of the inthe applicable number of the contract or grant under which formation in the paragraph, represented as (TS). (S), (C), or (U) the report was written. There is no limitation on the length of the abstract. How8b, 8c, & 8d. PROJECT NUMBER: Enter the appropriate ever, the suggested length is from 150 to 225 words. military department identification, such as project number, 14. KEY WORDS: Key words are technically meaningful terms 14. KEY WORDS: Key words are technically meaningful terms subproject number, system numbers, task number, etc..boe n, s u. or short phrases that characterize a report and may be used as 9a. ORIGINATOR'S REPORT NUMBER(S): Enter the offi- index entries for cataloging the report. Key words must be cial report number by which the document will be identified selected so that no security classification is required Identiand controlled by the originating activity. This number must fiers, such as equipment model designation, trade name, military be unique to this report. project code name, geographic location, may be used as key 9b. OTHER REPORT NUMBER(S): If the report has been words but will be followed by an indication of technical conassigned any other report numbers (either by the originator e assignment of links, rules, and weights is optional or by the sponsor), also enter this number(s). 10. AVAILABILITY/LIMITATION NOTICES: Enter any lirmitations on further dissemination of the report, other than those Unclassified Security Classification

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