Structural analysis of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) fibers prepared by drawing and annealing processes

Abstract

Structure of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) fibers prepared by drawing and annealing processes has been analyzed through wide-angle X-ray diffraction (WAXD), density, infrared dichroism, and birefringence measurements. There are three different types of crystalline structure in these fibers: two of these are the two types of orthorhombic with different orientation modes (the ordinary c-axis orientation (cFZ), and the preferential orientation of c-axis to the direction perpendicular to the fiber axis (cЌZ)); and the third is pseudohexagonal. The weight fractions of the three types of crystals and amorphous phase were analyzed combining the WAXD integrated intensity and density data. The relation between crystalline orientation factors obtained separately from the WAXD measurement and the infrared dichroic ratio is also discussed. The birefringence of these fibers shows negative and positive values, depending on drawing and annealing temperatures. Considering the intrinsic birefringence and weight fraction of the cFZ, cЌZ, and pseudohexagonal crystals, birefringence of the amorphous phase was evaluated. The amorphous birefringence shows positive values and decreases with an increase in the annealing temperature. From the analyzed fiber structure, it was speculated that the cЌZ and pseudohexagonal crystals are preferentially formed in the drawing process irrespective of the drawing temperature.

Investigating thermal properties of and melting-induced structural changes in cold-drawn P(3HB) films with α- and β-structures using real-time X-ray measurements and high-speed DSC

“…The obtained result was in keeping with previous reports that β-crystals disappear during annealing at temperatures greater than 130 C. [28,29] Although the crystallinity of the α-film decreased at approximately 110 °C, that of the β-film increased slightly with the temperature (Figure 4). It can be seen from Figure 5B that the intensities of the α(020) and α(110) diffractions in the case of the β-film increased significantly between 110 °C and 130 °C; however, no increase in crystallinity was detected in Figure 4.…”

Low pressure plasma treatment of poly(3‐hydroxybutyrate): Toward tailored polymer surfaces for tissue engineering scaffolds

“…Because of its bacterial origin, it can be obtained in exceptionally pure form without any inclusion of catalyst residues and as a stereoregular, optical active, isotactic polyester. There have been a few studies related to the effects of thermoplastic processing conditions on the development of structure and on the resulting mechanical properties of PHB products 20–24. The application of PHB materials as tissue engineering scaffolds needs to involve both the fabrication of suitable scaffold structures (i.e., porous carriers) and the surface modification introducing the required biomolecular components, respectively.…”

Mechanical Properties and Higher Order Structures of the Bacterial Polyester Highly Oriented Films

“…Orts et al suggested that the β-form chains emanate upon stretching from the amorphous domains between 21 helix α-form lamellae [14]. However Furuhashi et al demonstrated that another formation mechanism of β-form is also possible [15]. Most reports on the properties of melt spun fibers of PHB and its copolymers indicate that the tensile strength and modulus increase with the amount of β-form crystal [10,16].…”