Diffusional limitations (the gel, glass, and cage effects) are manifested in several bulk free radical homopolymerizations as well as in random copolymerizations. These are associated with decreases of several orders of magnitude of the rate constants of termination, propagation, and initiation (the initiator efficiency), respectively. These phenomena have been modeled earlier using the free volume theory for the diffusivities of primary radicals, macro‐radicals, and monomer molecules, and have been applied to homopolymerizations. In this study, a similar model is developed for random bulk copolymerizations. The parameters of the model are fitted using isothermal data on styrene acrylonitrile random copolymerization carried out in small ampoules. Thereafter, best‐fit global correlations have been developed for this system. This enables the model to be used for studying non‐isothermal copolymerizations, as well as for carrying out optimization of industrial reactors, where non‐isothermal conditions are a norm. POLYM. ENG. SCI., 55:2098–2110, 2015. © 2014 Society of Plastics Engineers

# Recoveiy of toxic metals from industrial wastewaters is an important environmentalissue. The use of liquid membrane technology has gained momentum in recent years as it allows the reuse of water and toxic metals. In this study, a bulk liquid membrane consisting of D2EHPA (ionic extractant) in n-hexane (solvent) was used to extract cadmium from an aqueous solution simulating industrial wastewater, and ammonium acetate solution was used to strip cadmium from the membrane phase. Initially, equilibrium and kinetics experiments were performed to identrfL favourable operating conditions as well as extraction and stripping rates. Then bulk liquid membrane experiments, with simultaneous extraction and stripping, were performed. More than 90% of the cadmium was recovered using the bulk liquid membrane in 120 minutes.

Bulk polymerization of random styrene‐acrylonitrile (SAN) copolymer using AIBN initiator, in nonisothermal batch reactors is optimized using single and multiple objective functions. The objectives are selected from among: minimization of the reaction time, maximization of the overall monomer conversion, and maximization of the number average molecular weight of the product. Constraints are used for the mole fraction of styrene in the copolymer produced (so as to produce copolymer having desired properties), and on the permissible range of temperature in the reactor. Pareto optimal solutions are obtained for some sample 2‐ and 3‐objective optimization problems. The optimization toolbox of MATLAB with genetic algorithm as the solver is used. Different points in the Pareto set are associated with different optimal temperature histories, a few of which are provided. POLYM. ENG. SCI., 55:2377–2387, 2015. © 2015 Society of Plastics Engineers