Miscibility and Biodegradation Behavior of Melt-Processed Blends of Bacterial Poly(3-Hydroxybutyrate) with Poly(Epichlorohydrin)

Toughening Biosourced Poly(lactic acid) and Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) Blends by a Renewable Poly(epichlorohydrin-co-ethylene oxide) Elastomer

A series of sustainable polymer blends from renewable poly(lactic acid) (PLA), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P_3,4HB), and poly(epichlorohydrin-co-ethylene oxide) (ECO) elastomer were fabricated via a melt blending method to gain balanced physical performance. The interplay of the composition, mutual miscibility, and viscosity ratio of the pristine PLA, P_3,4HB, and ECO elastomer resulted in diverse phase structures of the ternary blends. An excellent flexibility at an elongation of 270% was achieved for the PLA/P_3,4HB/ECO (70/20/10) blend with a core-shell structure. The PLA/P_3,4HB/ECO (70/10/20) blend with a phase-separated structure exhibited a high impact strength of 54 KJ/m², which is 25 times over that of the neat PLA. The relationship between the phase structure and physical performance of the blend was analyzed based on the compositions, surface tension, and physical characteristics of the neat components. Combining the compatibilization of the P_3,4HB phase and ECO elastomer toughening played a crucial role in enhancing the mechanical properties of the blends.

Bacterial poly(3-hydroxybutyrate): an optical microscopy and microfocus X-ray diffraction study

Two-dimensional spatially resolved microfocus X-ray diffraction has been used to investigate spherulites of pure bacterial poly(3-hydroxybutyrate) (PHB) and of a blend of natural and synthetic atactic PHB (a-PHB) crystallized at a relatively high temperature (Tc = 140 degrees C). Both samples investigated contained practically two-dimensional spherulites, characterized by wide extinction bands (band spacing > 80 microns). The X-ray diffraction patterns confirmed that the unit cell alpha-axis is oriented along the spherulite radius in PHB and that the same is true for the a-PHB containing blend. Comparison of the matrix of diffraction patterns with the polarized optical micrograph of the scanned sample area indicated a very clear correlation between pattern changes and banding, yielding a straightforward picture of the structural variations within the spherulite.