Tingting Su

Effect of Hydroxyl Monomers on the Enzymatic Degradation of Poly(ethylene succinate), Poly(butylene succinate), and Poly(hexylene succinate)

Poly(ethylene succinate) (PES), poly(butylene succinate) (PBS), and poly(hexylene succinate) (PHS), were synthesized using succinic acid and different dihydric alcohols as materials. Enzymatic degradability by cutinase of the three kinds of polyesters was studied, as well as their solid-state properties. The biodegradation behavior relied heavily on the distance between ester groups, crystallinity, and the hydrophilicity-hydrophobicity balance of polyester surfaces. The weight loss through degradation of the three kinds of polyesters with different hydroxyl monomers took place in the order PHS > PBS > PES. The degradation behavior of the polyesters before and after degradation was analyzed by scanning electron microscopy, differential scanning calorimetry, powder X-ray diffraction, Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis. The decrease in relative intensity at 1800–1650 estedpolyesters were degraded simultaneously. The frequencies of the crystalline and amorphous bands were almost identical before and after degradation. Thus, enzymatic degradation did not change the crystalline structure but destroyed it, and the degree of crystallinity markedly decreased. The molecular weight and polydispersity index only changed slightly. The thermal stability of the three kinds of polyesters decreased during enzymatic degradation.

Preparation, characterization, and biodegradation of poly(butylene succinate)/cellulose triacetate blends

Poly(butylene succinate) (PBS) and cellulose triacetate (CT) were blended using chloroform as solvent. The solid-state properties of PBS/CT blends were confirmed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), thermogravimetric analysis, scanning electron microscopy (SEM), and water contact angle measurements. FTIR results show that PBS and CT were physically blended. Tensile strength was not distinguished when the weight percent of CT was <15%, and Youngs modulus increased gradually with increasing CT. DSC and XRD results show that the crystals were homogeneous, and crystallinity had no apparent decrease when <10% CT was added to the PBS matrix. However, the addition of more CT components could destroy the crystal behavior of PBS. SEM showed that no phase separation occurred between the two materials. The addition of CT increased the hydrophilicity of PBS/CT1-15 blends. The weight loss was nearly 90% after 16h of degradation for PBS/CT10. The appropriate proportion of PBS to CT was 90:10.

Difference in solid-state properties and enzymatic degradation of three kinds of poly(butylene succinate)/cellulose blends

Biodegradable poly(butylene succinate) (PBS) was blended with cellulose microcrystalline (CMC), cellulose acetate (CA), and cellulose triacetate (CTA), respectively, to improve its properties and reduce its cost. The differences in solid-state properties and enzymatic degradation were investigated using FTIR, DSC, XRD, and SEM analysis. SEM images show that the fillers stick up above the matrix and form some pores in both PBS/CMC and PBS/CA blends because of their poor compatibility. Whereas fine particles of PBS and CTA are uniformly mixed and tightly packed together. The degree of crystallinity decreases for PBS/CTA blends, thereby showing that CTA molecules destroy the crystal uniformity. Youngs modulus is increased at average values of 43% after blending. The weight loss ratios of PBS/CMC and PBS/CA blends both reach approximately 85% after 4 h. SEM images show that the spherulitic texture in the surface easily formed cracks and holes and contributed to enzymolysis. In PBS/CTA samples, the weight loss ratio declined to 16% after 4 h. The surfaces are smooth and the enzymolysis occurs only on the surface.

Optimization of medium composition for 3-hydroxycarboxylic acid production by Pseudomonas mendocina–biodegraded polyhydroxybutyrate

We optimized the culture medium for 3‐hydroxycarboxylic acid production by Pseudomonas mendocina DS‐04‐T–biodegraded polyhydroxybutyrate (PHB) using the Plackett–Burman design, steepest ascent method, and Box–Behnken design. The optimized concentrations of the constituents of the culture medium were as follows: PHB (7.57 g/L), NH4Cl (5.0 g/L), KH2PO4 (2.64 g/L), Na2HPO4·12H2O (12 g/L), MgSO4·7H2O (0.5 g/L), and CaCl2·2H2O (5 mg/L). The yield of 3‐hydroxycarboxylic acid obtained using the optimized culture medium was 56.8 ± 1.64%, which was 2.5‐fold higher than that obtained when the unoptimized culture medium was used.

Enzymatic degradation of poly(butylene succinate) with different molecular weights by cutinase

Poly(butylene succinate) (PBS) films with different molecular weights were enzymatically degraded by cutinase. Changes in the properties of the films before and after enzymatic degradation were studied through scanning electron microscopy, differential scanning calorimetry, thermogravimetry, X-ray powder diffraction, proton nuclear magnetic resonance, and gel-permeation chromatography analysis. The weight loss of the films initially decreased and then increased with increasing molecular weight. Crystallinity was inversely proportional to weight loss and tended to decrease with prolonged degradation time. Crystalline and amorphous regions were simultaneously degraded. The thermal stability of PBS films decreased after enzymatic degradation. PBS was the main component of the enzymatically degraded polymers. The molecular weights of the films did not considerably change before and after degradation by cutinase.

Blending Modification of PHBV/PBS/PEG and its Biodegradation

ABSTRACT This study used poly(butylene succinate) and poly(ethylene glycol) to modify poly(3-hydroxybutyrate-co-3-hydroxyvalerate). The results showed that the incorporation of poly(butylene succinate) and poly(ethylene glycol) improved the mechanical properties of blends. The results showed that crystallinity of the poly(ethylene glycol)-containing blends decreased, so do the crystallization temperature and melting temperature of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) component of blends. Poly(butylene succinate)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/poly(ethylene glycol) ratio of 50:20:30 was chosen owing to its good properties. The poly(3-hydroxybutyrate-co-3-hydroxyvalerate) component of blends can be degraded completely by Pseudomonas mendocina DS04-T, whereas this strain cannot degrade poly(butylene succinate) and poly(ethylene glycol). Apart from poly(butylene succinate), Fusarium sp. FS1301 can also biodegrade poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(ethylene glycol). GRAPHICAL ABSTRACT