PHB Processability and Property Improvement with Linear-Chain Polyester Oligomers Used as Plasticizers

Abstract

In 2021, global petroleum-based plastic production reached over 400 million metric tons (Mt), and the accumulation of these non-biodegradable plastics in the environment is a worldwide concern. Polyhydroxybutyrate (PHB) offers many advantages over traditional petroleum-based plastics, being biobased, completely biodegradable, and non-toxic. However, its production and use are still challenging due to its low deformation capacity and narrow processing window. In this work, two linear-chain polyester oligomers were used as plasticizers to improve the processability and properties of PHB. Thermal analyses, XRD, and polarized optical microscopy were performed to evaluate the plasticizing effect on the PHB and the reflection on the mechanical behavior. Both oligomers acted as PHB plasticizers, with a reduction in Tg and Tm as a function of the plasticizer concentration, which can make it easier to handle the material in thermal processing and reduce the probability of thermal degradation. Plasticizer 2 proved to be the most promising between the two with an optimized condition of 20%, in which there was a decrease in elastic modulus of up to 72% and an increase in the maximum elongation of 467%.

Development of extrusion blown films of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) blends for flexible packaging

“…Although still modest, this property outperformed the enhancements reported in many other literature sources concerning plasticized PHBV or PHB 14,17,21,63,64 or stood on par with them. 12,15,19,20,24,65 The mechanical properties at freezer condition showed, as expected, an increase of the elastic modulus and the maximum stress. Interestingly, the elongation at break did not change.…”

“…Notably, the 4% elongation at break was achieved using ATBC. Although still modest, this property outperformed the enhancements reported in many other literature sources concerning plasticized PHBV or PHB 14,17,21,63,64 or stood on par with them 12,15,19,20,24,65 …”

Biocomposite‐based fibrous scaffolds of natural rubber/polyhydroxybutyrate blend reinforced with 45S5 bioglass aiming at biomedical applications

“…Additionally, it was impossible to distinguish the T g value of the PHB in the DSC curves. However, in the literature this value is in the −10°C and 15°C range, depending on the supply source 43,49 …”

“…However, in the literature this value is in the À10 C and 15 C range, depending on the supply source. 43,49 3 and Figure 5, the NR fibrous mat revealed characteristics typical of elastomeric polymers: a high elongation at break (ε at break ) of 738 ± 36% and a tensile strength at break (σ at break ) of 2.01 ± 0.28 MPa. On the other hand, as NR was partially replaced by PHB to form a NR-PHB fibrous bioblend, the specimen revealed a reduction in ε at break and an increase in σ at break compared to the NR fibrous mat, in which values were equal to 477 ± 25% and 4.11 ± 0.08 MPa, respectively.…”

Anomalous Mechanical Response of Stretched Film of Poly(3-Hydroxybutyrate-co-3-Hydroxyhexanoate)

“…Poly(3-hydroxybutyrate) (PHB) and its copolymers show good biodegradability even in marine environments [1][2][3], which makes them attractive to replace conventional plastics; e.g., isotactic polypropylene (PP). To date, various basic properties of PHB and its copolymers have been clari ed, such as rheological properties in the molten state [4][5][6], thermal properties including crystallization behavior [1,2,[7][8][9][10], processability [2,11,12], mechanical properties in the solid state [1,2,[13][14][15][16][17], structure and properties of blends and composites with other materials [15,[18][19][20][21][22][23], and degradation behavior [1-3, 24, 25]. The melting point (T m ) of PHB is approximately 180°C and decreases with increasing comonomer content [1,2].…”