Spiralling optical morphologies in spherulites of poly(hydroxybutyrate)

Synthesis and Properties of Degradable Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] Derived from Waste Fish Oil

“…Polymers of the PHA family are characterized by the formation of extremely large spherulites [ 98 ]. The rate of formation, size, and morphology of spherulites are determined by many factors, but the key one is the temperature at which polymer crystallization occurs [ 99 ]. The influence of the 3HV monomer content in the P(3HB- co -3HV) copolymers synthesized on WFO or butyric acid was shown in the study of the spherulite formation rate and morphology ( Figure 9 and Figure 10 ).…”

Biodegradable Polyhydroxyalkanoates with a Different Set of Valerate Monomers: Chemical Structure and Physicochemical Properties

“…In the paper of Laycock and colleagues [ 81 ], the coarse and fine structures of spherulites obtained confirmed that P(3HB- co -3HV) is a mixture of nominally block and/or random copolymers with a very wide compositional distribution. It is known that the shape and size of spherulites in PHA are influenced by many factors, with the key factor being the temperature at which crystallization occurs, while the periodicity and regularity of the structure of spherulite bands can change depending on the conditions of crystallization, as well as the molecular weight of the polymer [ 82 ]. Ding and Liu [ 83 ] found that non-striped and double banded spherulites can form in PHA during isothermal crystallization from a thin melt at both low and higher crystallization temperatures.…”

Transitional Ring Bands Constructed by Discrete Positive- and Negative-Birefringence Lamellae Packed in Poly(1,6-hexamethylene adipate) Spherulites

“…Keller et al used a concept based on the scheme in Figure to illustrate a continuous spiral model based on birefringence alternation into banded rings in poly­(4-hydroxy butyrate) (PHB), where the lamellae behave as single crystal plate and rotate continuously from edge-on to flat-on (along the radial direction) and repeat the cycles (Figure c). In addition to the model of continuity between flat-on and edge-on lamellae interconnected as spirals, there is another possibility where lamellae of all orientations (flat-on, edge-on, tiled lamellae, etc.)…”

“…Schematic representations of the optical signs of the spherulite using a sensitive tint plate, (a) negative-type spherulite and (b) positive-type spherulite, as well as two possible lamellar constructions, (c) continuous twist of lamellae in producing alternate bands vs (d) lamellae with perpendicular orientations and discontinuity …”