Structure–Property Relationship in Melt-Spun Poly(hydroxybutyrate-co-3-hexanoate) Monofilaments

Abstract

Poly(hydroxybutyrate-co-3-hexanoate) (PHBH) is a biodegradable thermoplastic polyester with the potential to be used in textile and medical applications. We have aimed at developing an upscalable melt-spinning method to produce fine biodegradable PHBH filaments without the use of an ice water bath or offline drawing techniques. We have evaluated the effect of different polymer grades (mol% 3-hydroxy hexanoate, molecular weight etc.) and production parameters on the tensile properties of melt-spun filaments. PHBH monofilaments (diameter < 130 µm) have been successfully melt-spun and online drawn from three different polymer grades. We report thermal and rheological properties of the polymer grades as well as morphological, thermal, mechanical, and structural properties of the melt-spun filaments thereof. Tensile strengths up to 291 MPa have been achieved. Differences in tensile performance have been correlated to structural differences with wide-angle X-ray diffraction and small-angle X-ray scattering. The measurements obtained have revealed that a synergetic interaction of a highly oriented non-crystalline mesophase with highly oriented α-crystals leads to increased tensile strength. Additionally, the effect of aging on the structure and tensile performance has been investigated.

Extrusion and thermoforming of poly(butylene succinate–co‐butylene adipate)/poly(3–hydroxybutyrate–co–3–hydroxyhexanoate) bio‐based blends for the fabrication of disposable packaging

“…On the other hand, neat PHBH presents a Newtonian fluid‐like behavior with low viscosity 42 . The viscosity of PHBH has a strong dependency on its molecular weight, as it was demonstrated by Selli et al, 43 who tested PHBH grades with a molecular weight between 300 and 500 kDa. PHBH X131N presents a molecular weight of 440 kDa, 42 thus explaining the higher values of viscosity observed for SH2, which present a higher percentage of PHBH.…”

Effects of Soaking Solvents by an Isothermal Crystallization Process on Physical Properties and Structures in One-Step-Drawing Films of Biodegradable P(3HB) Copolymers

“…Figure shows the WAXD patterns of one-step-drawing PHBV and PHBH films with IC under different soaking conditions. The drawn film after IC in ice–water, hexane, and air showed spot reflections compared to the WAXD ring diffraction pattern of the undrawn films. , The orientation of reflection of drawn films with IC in ice–water, hexane, or air increased by stretching, and the crystal orientation evaluated from the width in the azimuthal direction of (020) reflection (Table ), indicating that the α-form crystals with 2 1 helix conformation ,, as P­(3HB) crystal form are oriented. It has been reported that P­(3HB) and its copolymer also can observe planar zigzag conformation (β-form) in highly drawn films. ,, In this study, no clearly β-form diffraction was observed because of the low drawn ratio, and the short IC time of only 24 h formed a few microcrystalline nuclei (Figure ).…”

“…The drawn film after IC in ice−water, hexane, and air showed spot reflections compared to the WAXD ring diffraction pattern of the undrawn films. 17,19 The orientation of reflection of drawn films with IC in ice−water, hexane, or air increased by stretching, and the crystal orientation evaluated from the width in the azimuthal direction of (020) reflection 19 (Table 3), indicating that the α-form crystals with 2 1 helix conformation 10,20,32 as P(3HB) crystal form are oriented. It has been reported that P(3HB) and its copolymer also can observe planar zigzag conformation (β-form) in highly drawn films.…”

“…Because of its good thermoplastic processability, biocompatibility, and biodegradability, it is considered to be one of the potential materials to replace traditional petrochemical plastics. − Poly­[( R )-3-hydroxybutyrate] P­(3HB) is known as the most widely studied homopolymer in PHA, and due to the low glass-transition temperature of ∼4 °C, the mechanical properties of P­(3HB) homopolymers after secondary crystallization will be significantly deteriorated. Therefore, it is usually copolymerized with other monomer components to improve its brittleness and stiffness to meet the needs of industrial applications. − Poly­[( R )-3-hydroxybutyrate- co -( R )-3-hydroxyvalerate] (PHBV) introduces 3HV units into the crystal lattice of P­(3HB), PHBV exhibits good biocompatibility, high-temperature resistance, and higher crystallinity. , Poly­[( R )-3-hydroxybutyrate- co -( R )-3-hydroxyhexanoate] (PHBH) belongs to the short-chain and medium-long-chain copolymerized PHAs. Compared with P­(3HB), although the introduction of the medium-long-chain monomer 3HH improves the ductility, the hardness of the material is reduced…”

Seawater-degradable, tough, and fully bio-derived nonwoven polyester fibres reinforced with mechanically defibrated cellulose nanofibres

“…[4][5][6][7] PHBH has been extensively used to fabricate plastic bags and disposable straws, 8 and has been investigated for fiberization into micrometre-sized fibres using melt-spun blowing. 9,10 Electrospinning, an efficient method for obtaining nonwoven fabrics with nanometre-sized fibres, can also be applied to PHBH, but electrospun nonwoven PHBH fibres exhibit poor mechanical properties. [11][12][13] Fillers such as nanosilica, 14 montmorillonite, 15 carbon nanotubes, 16 and glass fibres 17 have been used to enhance the mechanical characteristics of PHBH.…”