Radiation-induced graft polymerization of acrylic acid onto poly(3-hydroxybutyrate) and its copolymer

Abstract

A typical hydrophilic monomer, acrylic acid (AAc) , was graft polymerized onto poly(3-hydroxybutyrate) (PHB) and its copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(HB-HV)] by 60Co- γ -rays preirradiation technique. Degree of grafting (Xg) of PHB was higher than that of the copolymer of 24 mol% HV content (24M sample). The grafting was mainly introduced into the amorphous regions of the whole samples, while the crystalline regions remained almost unchanged. The Xg of the grafted sample estimated by the thermogravimetry was very close to that estimated from weight increase. Biodegradability steeply increased by introduction of small amount of grafted AAc because of the improvement of wettability between the polymer and an enzyme solution, then decreased as Xg increased much more.