Free radical polymerizations associated with the trommsdorff effect under semibatch reactor conditions. II: Experimental responses to step changes in temperature

Several free radical addition polymerizations exhibit the diffusion limited gel or Trommsdorff effect. The models available until recently could not be applied to industrially important semibatch operations and to nonisothermal polymerizations. The recent model of Ray et al. (24) can indeed be applied to such situations. In this study, an experimental setup to study polymerizations under such conditions has been assembled. Methyl methacrylate (MMA) is polymerized in a 1-liter stainless steel, computer-controlled reactor. A series of experiments on bulk polymerization of MMA under different temperature histories (near-isothermal, step decrease, and step increase) at a fixed initiator (AIBN) concentration of 25.8 mol/m 3 have been conducted. Two important process output variables, namely, monomer conversion and average molecular weight, have been measured off-line at different sampling times during the course of polymerization. The conversion and molecular weight data are found to be in reasonable accord with model (24) predictions obtained using the experimental (nonisothermal) temperature histories, and best fit correlations for three parameters evaluated using earlier data from the literature on isothermal batch reactors (with no further curve fitting). The new model (24) can, thus, be used with some degree of confidence to design and control larger scale reactors.

[1]  K. Horie,et al.  Diffusion-Controlled Reactions in Polymer Systems , 1987 .

[2]  S. K. Soh,et al.  Diffusion‐controlled vinyl polymerization. II. Limitations on the gel effect , 1982 .

[3]  Shiping Zhu,et al.  Radical concentrations in free radical copolymerization of MMA/EGDMA , 1990 .

[4]  David S. Soong,et al.  Free radical polymerization of methyl methacrylate at high temperatures , 1985 .

[5]  Coleman B. Brosilow,et al.  Nonlinear model predictive control of styrene polymerization at unstable operating points , 1990 .

[6]  K. O'driscoll,et al.  The rate of copolymerization of styrene and methyl methacrylate—II. The gel effect in copolymerization , 1990 .

[7]  David S. Soong,et al.  Optimization of batch polymerization processes—narrowing the MWD. I. Model simulation , 1985 .

[8]  D. Soong,et al.  Optimization of batch polymerization processes—narrowing the MWD. II. Experimental study , 1985 .

[9]  Arvind Varma,et al.  Parametric sensitivity of chain polymerization reactors exhibiting the trommsdorff effect , 1989 .

[10]  H. Amrehn.  Computer control in the polymerization industry , 1977, Autom..

[11]  John P. Congalidis,et al.  Feedforward and feedback control of a solution copolymerization reactor , 1989 .

[12]  J. S. Vrentas,et al.  Molecular diffusion in polymer solutions , 1979 .

[13]  Klavs F. Jensen,et al.  On‐line molecular weight distribution estimation and control in batch polymerization , 1994 .

[14]  R. Smith,et al.  Catalysed Polymerization of Methyl Methacrylate in the Liquid Phase , 1942, Nature.

[15]  David S. Soong,et al.  A computer model for the gel effect in free-radical polymerization , 1983 .

[16]  Costas Kravaris,et al.  Nonlinear control of a batch polymerization reactor: An experimental study , 1992 .

[17]  G. E. Eliçabe,et al.  Estimation and control in polymerization reactors. A review , 1988 .

[18]  S. Gupta,et al.  Optimal temperature profiles for methylmethacrylate polymerization in the presence of end point constraints , 1991 .

[19]  P. Lagally,et al.  Zur polymerisation des methacrylsäuremethylesters1 , 1948 .

[20]  Deoki N. Saraf,et al.  Free radical polymerizations associated with the trommsdorff effect under semibatch reactor conditions. I: Modeling , 1995 .

[21]  David S. Soong,et al.  Free-radical polymerization of methyl methacrylate in tubular reactors , 1985 .

[22]  A. Hamielec.  Recent developments in free radical polymerization at high conversion-diffusion controlled termination and propagation , 1983 .

[23]  S. Gupta,et al.  Optimal parameter estimation for methyl methacrylate polymerization , 1991 .

[24]  A. Hamielec,et al.  Bulk polymerization of methyl methacrylate , 1973 .

[25]  K. O'driscoll,et al.  High‐conversion polymerization. I. Theory and application to methyl methacrylate , 1976 .

[26]  C. Kiparissides,et al.  Modeling of diffusion‐controlled free‐radical polymerization reactions , 1988 .

[27]  S. Gupta,et al.  Parameter Estimation for Solution Polymerization of Methylmethacrylate , 1993 .

[28]  K. O'driscoll,et al.  The rate of copolymerization of styrene and methylmethacrylate—I. Low conversion kinetics , 1989 .

[29]  Costas Kiparissides,et al.  Development of a General Mathematical Framework for Modeling Diffusion-Controlled Free-Radical Polymerization Reactions , 1992 .