Phase Behavior and Thermal Properties for Binary Blends of Compositionally Fractionated Poly(3-hydroxybutyrate-co-3-hydroxypropionate)s with Different Comonomer Composition

Abstract

Bacterially synthesized poly(3-hydroxybutyrate-co-3-hydroxypropionate) [P(3HB-co-3HP)] samples were compositionally fractionated using solvent/nonsolvent fractionation techniques. Binary blends between these compositionally fractionated P(3HB-co-3HP) samples, with much narrower comonomer compositional distribution, were prepared, and their thermal and crystallization behavior were studied using differential scanning calorimeter (DSC) and polarized optical microscopy. It was found that, in the amorphous phase of these blends, the miscibility mainly depends on the difference of 3HP contents (or 3HB contents) between the two components of the blend. When the difference of 3HP content between two copolyesters is less than 30-40 mol %, they become miscible in the amorphous phase. The type of crystal lattice, miscibility, and difference of the spherulite growth rate between the two components of the blend appear to be the important factors controlling the crystalline phase behavior. The results are compared with those of unfractionated P(3HB-co-3HP)s and the effects of comonomer composition and its distribution on the properties of unfractionated copolymers are discussed.

Effects of pH of Fermentation Medium on Biosynthesis of Poly[(3‐hydroxybutyrate)‐co‐(3‐mercaptopropionate)] by Wautersia eutropha

“…The principal components of P(3HB‐ co ‐3MP) pH6.5 and P(3HB‐ co ‐3MP) pH7.0 were the copolyesters with more than 60 mol‐% 3MP unit content and that with about 20 mol‐%, respectively. In other words, an amorphous area of 3HB‐unit rich P(3HB‐ co ‐3MP) and that of 3MP‐unit rich P(3HB‐ co ‐3MP) are immiscible in each other 8,13,30,31. It was known that the bacterially synthesized 3HB‐rich P(3HB‐ co ‐3MP) took the crystalline structure of 3HB type, and the 3MP‐rich P(3HB‐ co ‐3MP) took the crystalline structure of 3MP type 25.…”

“…The comonomer unit which was different from the other comonomer unit composing the crystalline phase might be excluded from the crystalline phase. It was suggested that the character in an amorphous area of original polymer had been decided by the difference of the crystalline type 13,15,30,31…”

Comonomer‐Unit Compositions, Physical Properties and Biodegradability of Bacterial Copolyhydroxyalkanoates

“…Na et al have also investigated the physical behavior and thermal properties of the blends between fractionated P(3HB‐ co ‐3HP)s 33. The blend is miscible in the amorphous phase when the difference in 3HP‐unit content between two copolyesters is less than 30–40 mol‐%.…”

Enhanced mechanical properties of PLA/PLAE blends via well-dispersed and compatilized nanostructures in the matrix

“…So and hard segment crystallization and phase separation can be estimated from thermal transitions such as glass transition temperature, melting temperature, and crystallization temperature. [37][38][39] Our results indicate the poor miscibility of PLA and PLAE. In general, with an increased PLAE content, the T g-PLAE tends to shi to a higher temperature while T g-PLA is slightly lowered.…”