A NEW KINETIC-MODEL FOR THE ACCUMULATION OF POLY(3-HYDROXYBUTYRATE) IN ALCALIGENES-EUTROPHUS .1. GRANULE GROWTH

A new kinetic model is proposed for the accumulation of poly(3-hydroxy butyrate) (PHB) in Alcaligenes eutrophus. The model developed is close ly related to the descriptive model of Harkins for the emulsion polyme rization process. The PHB accumulation is discussed in terms of polyme rization events such as initiation, propagation and termination, takin g into account the heterogeneous nature of the system. Experimental re sults on the PHB accumulation in Alcaligenes eutrophus can be describe d in both a quantitative and qualitative manner by the model. Further, it is shown that the decrease in the rate of polymerization during th e PHB accumulation can be explained by coalescence of the granules. Th e decrease of the molecular weight of the polymer formed during the ac cumulation process can be fully explained in terms of the kinetic mech anisms of progapation and chain transfer, and the effect of granule si ze on these.