Free radical crosslinking of unsaturated bacterial polyesters obtained from soybean oily acids

Poly(-3-hydroxy alkanoate) containing unsaturated side chains, PHA-soybean, were produced by feeding Pseudomonas oleovorans with soybean oily acids ob tained from soybean oil. Unsaturation of PHA-soybean were found to be 10 mo l-% of unsaturated side chains. Main saturated part of the biopolymer was Poly(3-hydroxy octanoate) with mi nor hexanoate and decanoate units. PHA films were crosslinked via free radi cal mechanism by means of thermally or under UV irradiation in the presence of benzoyl peroxide, benzophenon, and/or ethylene glycol dimethacrylate (E GDM). Crosslinking yield of the PHA films were found to be from 81 to 93 wt .-% from the sol-gel analysis. Swelling properties of the crosslinked PHA f ilms in chloroform and toluene were also studied. Me values of crosslinked PHAs were also calculated using Flory-Rehner equation. The crosslinked biop olyester obtained by thermally at 60 degreesC with benzoyl peroxide indicat ed the highest crosslinking density. Glass transition temperatures (Tg) of crosslinked biopolyester samples were changed from -33 to -45 degreesC whil e that of PHA-soybean was -60 degreesC.