A. Mas et al., POLY(HYDROXYBUTYRATE) AND POLY(HYDROXYBUT YRATE-CO-HYDROXYVALERATE) MICROFILTRATION MEMBRANES - FORMATION - DEPENDENCY ON HYDROXYVALERATE CONTENTS, Bulletin des Societes chimiques belges, 105(5), 1996, pp. 233-246
Filtration properties and structure of polyhydroxybutyrate, poly(hydro
xybutyrate-co-9% hydroxyvalerate) and poly(hydroxybutyrate-co-22% hydr
oxyvalerate) microfiltration membranes prepared by the inversion phase
method are correlated with coagulation bath composition, non solvents
percentages (% NS) (tetrahydrofuran, dimethylformamide, ethanol) and
hydroxyvalerate contents (% HV). Ternary phase diagrams are discussed
with respect to polymers solubility parameters and solvent-non solvent
mixtures solubility parameters just as phase separation occurs. The s
low or rapid membranes formation was studied by comparing the initial
solution composition to the binodal curve values. Volumic fluxes, sele
ctivity and % NS variations were explained from this concept. Only the
9% HV copolymer presents a spherolitic structure which results from a
larger cristallization velocity during this phase inversion method co
nditions.