Document meBX9XJ6N4MpDyXo7LjdDpjk

interim Report SUSPENSION POLYMERIZATION OF VINYL CHLORIDE: RATES OF POLYMERIZATION WITH MIXTURES OF DILAUROYL PEROXIDE AND DIISOPROPYL PEROXYDICARBONATE autmors* L. C. Grotz J. F. Erdmann, Group Leader atb> August 27, 1959 FIL NO: B:20:250A-I4 Project No* 510A SUMMARY A significant reduction in tbe time required for the suspension polymerization of vinyl chloride could be achieved if an initiator system could be developed to give a constant rate of polymerization. Suspension polymerizations of vinyl chloride were conducted in glass bombs with mixtures of the two initiators, dilauroyl peroxide and diisopropyl peroxydicarbonate, to determine if same combination of the two might help to overcome the autocatalytic nature of the polymerization. Several combinations of the two initiators were evaluated. Each successive increase in the initial rate of polymerization was accompanied by an increase in the maximum rate of polymerization. Some changes in the rate-conversion relationship were observed, but further work will be required to determine if the indicated improvement in rate is real or is the result of the experimental error. The hypothesis was advanced that an initiator with a shorter half-life than dlisopropyl peroxydicarbonate will be required to achieve a constant rate throughout the polymerization. Combinations of dilauroyl peroxide with peracetic acid and with dimethylanillne were also evaluated. The peracetic acid decreased the initial rate of polymerization while the dimethylaniline gave reduced rates over the entire period during which the reaction was followed. DISCUSSION Mixtures of Dlisopropyl Peroxydicarbonate - and Dilauroyl Peroxld The suspension polymerization of vinyl chloride at 50C, when initiated with 0.30 weight per cent of dilauroyl peroxide (DLP), has been shown to have an initial rate of polymerization of 2.5 and a maximum rate of 11.2 per cent DEVELOPMENT DEPARTMENT Union Capsid* Chcmicals company SOUTH CHARLESTON. WRIT VIRGINIA inn 040 CO K" B:20:250A-I4 2 conversion per hour (1). The tine required for 00 per cent conversion in this aystea is 13 hours. If a constant rate of polymerization of 11.2 per cent could be achieved, then the time to 90 per cent conversion would be reduced to 8 hours, a reduction of 38 per cent*. It has been postulated by the Texas City Development Group that the use of a small amount of a very active initiator in combination with DLP might help to achieve a more uniform rate of polymerization. The relatively high order of activity of 41Isopropyl peroxydicarbonate (IPP) suggested that this material ahonld be evaluated in combination with DLP. Suspension polymerizations of vinyl chloride sere conducted in glass bombs at 50C, and conversion-time curves were obtained for the following initiator combinations: 1. 0.047 mol per cent IPP** 2. 0.035 mol per cent IPP plus 0.012 mol per cent DLP 3. 0.0235 mol per cent IPP plus 0.0235 mol per cent DLP 4. 0.012 mol per cent IPP plus 0.035 mol per cent DLP 5. 0.004 mol per cent IPP plus 0.047 mol per cent DLP 6. 0.047 mol per cent DLP * The heat transfer capacity of production autoclaves necessitates the use of a polymerization period of around 21 hours. Under these conditions the initial rate is probably close to 1 per cent and the maximum rate close to 8 per cent conversion per hour. A constant rate of 8 per cent per hour would reduce the time required for 90 per cent conversion to 11.2 hours, a reduction of 47 per cent. ** The weight percentages are related to the mol percentages by the equation: Mol. wt. of Init. r#,,i ________*i Wt. per cent - ifol. wt. of VC1-- " LMo1 per centJ These molecular weight ratios are 6.38 and 3.30 for dilauroyl peroxide and diisopropyl peroxydicarbonate, respectively. ucc 040864 B:20:250A-I4 -3- The conversion-time curves for these systems are plotted in Figure 1 and are the best continuous curves that could be drawn through the experimental data. The rates of polymeri zation at Increments of 10 per cent conversion were calculated from the conversion curves by use of the equation: Rate f(t + A)-f(t -A) (t + -aT ' where f (t + A) is the degree of polymerisation; at the time (t + a), etc. The value* of t used were the time* required to reach the degree of conversion at which the rate was desired, and a value of 1/8 hour was used for a. The calculated rates are given in Table Hand are plotted in Figure 2. The results in Table II sjiow that each successive increase in the initial rate results in an increase in the maximum rate. The simple procedure of adding some ZPP to a system containing the normal amount of CLP did not help to improve the constancy of the rate. Thus, the system number 5 was constant to the extent of 12.4 2 per cent from 30 per cent to 80 per cent conversion, and system number 6, without any 1PP, was constant to the extent of 9.2 2 per cent from 30 to 80 per cent also. Perhaps some lower total concentration of the two peroxides or a different ratio might improve this picture. A system which did show a constant rate over a longer range of conversions was 0.012 mol per cent of 1PP alone at 50C. This system was the lowest concentration of IPP for which rates from 0 to 90 per cent conversion could be calculated. The measurements on this Systran were made as part of a previous study (2). The calculated rates for this system were: TABLE I System #7 Rate of Polymerization, Conversion, Per Cent Per Cent Conversion per Hour 0 5.0 10 9.4 20 13.4 30 13.0 40 14.0 50 14.8 60 15.0 70 15.6 80 16.2 90 12.4 ucc 040365 B:20:250A-I4 -4 - This system had a constant rate to the extent of 14.22 per cent from 20 to 90 per cent conversion. The results for this system are also plotted in Figure 2. The rate versus conversion curves plotted in Figure 2 give some indication that the nature of the dependence on the degree of monomer conversion can be altered by the choic of initiator system; this is especially true of the results for system number 4. However, in view of the experimental errors involved in the use of IPP, it is considered more probable that the deviations in the shapes of the curves. Including the results for systems 4 and 7, are the result of the experimental error. It is very difficult to charge the exact amounts of vinyl chloride and IPP to the bombs; a few of the "duplicate bombs" gave dlfferenc s in conversion as high as eight per cent. Since none of the indicated improvements in rate are greater than the possible experimental error, more work will be required to determine if combinations of IPP and DLP can improve the rate and to determine the extent of the improvement. The autocatalytlc nature of the polymerization of vinyl chloride has been attributed to the reduction of the rate of termination and the resultant increase in free radical concen tration (3). If a sufficiently reactive initiator could be found so that the concentration of initiator (and therefore the rate of formation of free radicals) would decrease in the same ratio as the rate of termination, then a constant rate of polymerization would be anticipated (with due allowance for the decrease in monomer concentration). The half-lives for DLP and IPP at 50C are 50 hours and 6.8 hours, respectively (4). A peroxide with a shorter half-life than 6.8 hours is probably required to radically alter the rate-conversion behavior of the suspension polymerization of vinyl chloride. Peracetic Acid or Dimethylaniline with Dilauroyl Peroxide The effects of additions of peracetic acid and of dimethylaniline (DMA) on the conversion-time behavior were also determined. Conversion-time curves were obtained from 0 to 8 hours for suspension polymerizations at 50C with the following initiator systems: A. 0.047 mol per cent DLP B. A plus 0.05 mol per cent peracetic acid C. A plus 0.0047 mol per cent DMA D. A plus 0,047 mol per cent DMA E. A plus 0.41 mol per cent DMA ucc 040866 B:2Q:250A-I4 5 The results of these Measurements are plotted in Figure 3. As can be seen In the figure, the peracetic acid lowered the rate for roughly the first hour compared to system A, but after one hour gave rates similar to A alone. The DMA, however, gave lowered rates throughout the eight hour period, with the degree of lowering directly proportional to the amount of DMA included in the system. Thus, neither peracetic acid or DMA seems capable of producing the desired uniform rate. In addition, the DMA gave the polyvinyl chlaride a poor color. PROCEDURE The usual charging techniques (5) were employed except when IPP was added to the bombs. When IPP was added, the modified procedure was used (2), whereby the IPP was added in vinyl chloride solution at -78.5C. The recipe used was as follows: Water 16.2 ml Vinyl Chloride 12.0 g E-88-H (2 per cent aqueous solution) 1.8 ml Initiator variable A sufficient number of bombs were charged in each to allow a pair of bombs to be taken from the batch each hour or halfhour (depending upon the rate of polymerization), and the degree of polymerization determined by recovery of the solids in the bombs. The difficulty usually encountered in getting exactly 12.0 grams of vinyl chloride in each bonb was partially circumvented by pairing the bombs which were high in added vinyl chloride with bombs which were low in added vinyl chloride, e.g., a bomb containing 12.3 grams of vinyl chloride would be'paired with a bomb containing 11.7 grans of vinyl chloride. The exact weights of vinyl chloride, however, were used in the calculating of the degrees of conversion. BIBLIOGRAPHY (1) Nicholas, J. S., Grotz, L. C., and Snyder, G. E., Suspensi n Polymerized Vinyl Chloride Resin: Evaluation of Dioctanoyl~ Peroxide Catalyst, Development Department, January 10, 1957 (B:20:250A-I1).-- occ 040867 B:20;250A-I4 -6- (2) Erdmann, J. F,, and Grot*, L. C., Susspi onstion Polymerised Vinyl Chloride Resin: Bat* Studies with Dllsopropyl aPeroxydlcarbohateandDiiauroyi Peroxide as initiators, Development department, August TX7TX& (B:2P:~75PA-I3). (3) Bengough, V. I., and Norrish, R. G. w,, The Meehanlam and Kinetics of the Heterogeneous PolynerlzaTISh of Vinyl Monomers. i. me Benxoyi Peroxide initiated FolymerlzatIon pyVinyi Cniorlds, nWdc. Roly. soc. (Xdfifl<inj agyu, sqi-zq (1950), (4) Connelly, B. L., Private Communlcatlo*. (5) Nicholas, J. 8., and White, 0. Q., Vinyl Chloride Suspension Resin: Development of a Tost to Monitor tne suitability of vinyl chloride ror suspension Polymerization, Development'" Department, April 18, f57 (B:20:S00B-X1). NOTEBOOK REFERENCE: D-3095 LABORATORY ACCOUNT: 1588 PERIOD: February 17 - March 7, 1858 Attachments: 3 Figures 1 Table yf ucc 040868 B:20:250A-I4 7 TABLE II SUSPENSION POLYMERIZATION OF VINYL CHLORIDE AT 50C POLYMERIZATION RATES FOR MIXTURES OF IPP* AMD DLP* INITIATORS um/um CONVERSION, % 0 10 20 30 40 50 60 70 80 90 POLYMERIZATION RATE, PER CENT CONVERSION PER HOUR 1 2 34 56 7 16.8 21.2 28.0 34.4 40.0 45.2 50.0 54.8 56.0 48.0 15.2 20.0 24.0 27.2 28.4 35.6 41.2 46.8 51.2 46.4 10.8 16.4 20.4 26.4 30.0 33.2 36.6 37.6 44.0 24.4 6.8 12,8 3.7 M 20.8 22.0 24.4 24.4 24.0 23.2 19.4 4.0 6.6 8.6 10.4 11.4 12.0 13.0 14.4 13.6 9.0 2.5 4.4 6.3 7.7 8.7 9.6 10.3 10.8 11.2 5.0 5.0 9.4 13.4 13.0 14.0 14.8 15.0 15.6 16.2 12.4 * IPP Diisopropyl PeroxydicarDonate DLP Dilauroyl Peroxide INITIATOR CONCENTRATIONS* INITITATOR ---------------UP------------ -------------CCF SYSTEM Mol % Wt % Mol % Wt % total initiator Mol % Wt % 1 0.047 0.16 mm 0.047 0.16 2 0.035 0.12 0.012 0.076 0.047 0.20 3 0.0235 0.078 0.0235 0.15 0.047 0.23 4 0.012 0.040 0.035 0.22 0.047 0.26 5 0.004 0.013 0.047 0.30 0.051 0.31 6 -- 0.047 0.30 0.047 0.30 7 0.012 0.039 - - 0.012 0.039 * Calculated as weight and mole per cent of the vinyl chloride uec 040869 SUSPENSION POLYMERIZATION OF VINYL CHLORIDE AT 50C: CONVERSION CURVES FOR MIXTURES OF IPP* AND DLP* INITIATORS s O & HOH uu >ao u o<x> oV o--j i na M ci u go to Cn ilk DEVELOPMENT DEPARTMENT B:20:250A-I4 FIGURE 3 SUSPENSION POLYMERIZATION OF VINYL CHLORIDE AT SO*C: EFFECTS OF PERACETIC ACID AND DIMETSYLANILINE ON CONVERSION Monomer C o n ve rsio n m m s m m f r ifififm ifffffififeif x pita w u MM t B:20:250A-I4 DISTRIBUTION . WS. Adamson, NYO . 0. T. Carlisle, 515 . 7. D. Dexter, 312 (2) . L. L. Dintlman, NYO . J. P. Ferrer, 514 . R. D. Glenn, NYO . G. J. Banks, 514 . D, E. Richardson, 515 . S. H. Rose, Jr., 511 (2) . W. N. Stoops, 511 . G. B. Telford, 514 . B. R. Thompson, 511 . C. A. Vales, 515 . J. C. Alexander . R. M. Berg . J. V. Biddle . F. X. Critchfield . D. L. Engle . P. T. McCoy . T. R. Miller . A. E. Montagna . J. S. Nicholas . V. S. Tamplin . C. R. Welter . R. C. Wise . D. Q. White . V. A. Yarborough Library (2) INDEX LIST Polyvinyl Chloride Diisopropyl peroxydlcarbonate Dimethylaniline Dilauroyl Peroxide Peracetic Acid Polymerization Rate Suspension Polymerization ucc 040873