The main objective of the present work is to analyze the influence of some important operational reaction parameters (agitation speed, polybutadiene - PB - content and initiator concentration) on the final properties of High Impact Polystyrene (HIPS) produced in bulk. Variable effects are analyzed both qualitatively and quantitatively with the help of a fractional factorial design. Physical, chemical and mechanical properties were evaluated through measurement of the weight-average molecular weight (Mw), polydispersity (PD), volume-average diameter of PB particles (D(4,3)) and impact strength (Izod). It was found that PD and D(4,3) depend strongly on the initiator concentration, rubber concentration and agitation speed; Mw depends on initiator and rubber concentrations; and Izod depends on the rubber concentration, PD and D(4,3) in the analyzed experimental range. As a consequence, it was shown that control of final polymer properties can be easily performed through proper manipulation of the analyzed operational variables.

In this work an enzymatic lactose biosensor composed of the immobilized enzymes b-galactosidase and glucose oxidase was developed. Oxygen consumption during the reaction catalyzed by these enzymes was detected. The biosensor was integrated into an FIA (flow injection analysis) system that allows measurement of lactose on-line in less than three minutes. This biosensor was used to monitor lactose concentration during the production of b-galactosidase by the yeast Kluyveromyces marxianus from cheese whey. The sensor showed good stability after four months and after almost 7000 measurements had been performed. The analytical curve was linear in the range of lactose concentration from 1 to 30 g/L.

A fed-batch alcohol fermentation on a pilot plant scale with a digital supervisory control system was evaluated as an experimental application case study of an adaptive controller. The verification of intrinsically dynamic variations in the characteristics of the fermentation, observed in previous work, showed the necessity of an adaptive control strategy for controller parameter tuning in order to adjust the changes in the specific rates of consumption, growth and product formation during the process. Satisfactory experimental results were obtained for set-point variations and sugar feed concentration load changes in the manipulated inlet flow to the fermenter

Enzymatic sensors for the continuous measurement of glucose and sucrose, with the use of an enzymatic microreactor and a continuous flow dilution line for the medium, are studied in this work. The effects of the best conditions for medium and sampling flow through the sensor were analysed for a glucose concentration range from 0.05 to 0.2 g/l , which was possible to extend to a range from 5.0 to 120 g/l using a dilution and sampling circuit with the FIA analysis methodology