Effect of Monomers of 3-Hydroxyhexanoate on Properties of Copolymers Poly(3-Hydroxybutyrate-co 3-Hydroxyhexanoate)

Abstract

The properties of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) P(3HB-co-3HHx) copolymers with different ratios of monomers synthesized by the wild-type strain Cupriavidus necator B-10646 on sugars, and an industrial sample from Kaneka synthesized by the recombinant strain C. necator NSDG-ΔfadB1 on soybean oil, were studied in a comparative aspect and in relation to poly(3-hydroxybutyrate) P(3HB). The copolymer samples, regardless of the synthesis conditions or the ratio of monomers, had reduced values of crystallinity degree (50–60%) and weight average molecular weight (415–520 kDa), and increased values of polydispersity (2.8–4.3) compared to P(3HB) (70–76%, 720 kDa, and 2.2). The industrial sample had differences in its thermal behavior, including a lower glass transition temperature (−2.4 °C), two peaks in its crystallization and melting regions, a lower melting point (Tmelt) (112/141 °C), and a more pronounced gap between Tmelt and the temperature of thermal degradation (Tdegr). The process, shape, and size of the spherulites formed during the isothermal crystallization of P(3HB) and P(3HB-co-3ННx) were generally similar, but differed in the maximum growth rate of the spherulites during exothermic crystallization, which was 3.5–3.7 μm/min for P(3HB), and 0.06–1.25 for the P(3HB-co-3HHx) samples. The results from studying the thermal properties and the crystallization mechanism of P(3HB-co-3HHx) copolymers are important for improving the technologies for processing polymer products from melts.

Development of a Biodegradable Ternary Blend of Poly(vinyl alcohol) and Polyhydroxybutyrate Functionalized with Triacetin for Agricultural Mulch Applications

“…It is a semicrystalline molecule with both amorphous and crystalline phases, with the crystalline phase predominating the amorphous phase. This isotactic biopolymer bears structural similarities to isotactic polypropylene . The high degree of crystallinity in PHB results from polymerization, which leads to the formation of highly organized stereochemical structured macromolecules .…”

“…This isotactic biopolymer bears structural similarities to isotactic polypropylene. 15 The high degree of crystallinity in PHB results from polymerization, which leads to the formation of highly organized stereochemical structured macromolecules. 16 It is typically used not in its pure form but as an ingredient in multiblended composites.…”

Ternary Blends from Biological Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), Poly(propylene carbonate) and Poly(vinyl acetate) with Balanced Properties

“…The 3HB/3HHx copolymerization ratio can affect the physical properties of PHBH with a range from amorphous elastomer to semicrystalline plastic. Therefore, PHBH is expected to play a role in multiple fields, such as food packaging, disposable plastics and agricultural mulch films [5,6]. However, PHBH with low 3HHx content is brittle, which originated from its high crystallinity, which limits its practical applications.…”