Thermal degradation behavior of poly[(R)-3-hydroxybutyrate-co-4-hydroxybutyrate]

The thermal degradation behavior of poly[(R)-3-hydroxybutyrate-co-16 mol%-4-hydroxybutyrate] (P(3HB-co-16 mol%-4HB)) was investigated based on spectroscopic analysis its pyrolyzates and two kinetic modeling approaches. Pyrolyzate revealed that trans-crotonic acid, cis-crotonic γ-butyrolactone, their oligomers (dimers trimers) were produced following P(3HB-co-16 mol%-4HB). analyses confirmed the this copolymer changed depending time and/or temperature parameters. Specifically, process proceeded in at least steps, (i) initial random (ii) subsequent 0th-order weight loss, which indicated unzipping 3HB units. Based 13C NMR two-dimensional methods, it determined units starting from chain end may stop or volatilize an oligomer when reaction reaches a 4HB unit randomly present copolymer.